1. from forest to market - iggesund paperboard · 1. from forest to market ... pensive catalogues...

7IGGESUND PAPERBOARD | Reference Manual

1. From forest to market

Paperboard the natural choice 9

The philosophy of choice 15

The paperboard product 17

Choices of raw material 19

Differences paper and paperboard 22

Fibre to board 26

The paperboard machine 36

Extrusion coating and lamination 38

Board lamination 44

Design and carton construction 46

Consumer use and appeal 56

Distribution and storage 57

Retailing 60

Taint and odour neutrality 61

Migration into foodstuffs 65

Reference Manual | IGGESUND PAPERBOARD 8

Paperboard – the natural choice




When Iggesund published the Paperboard Reference

Manual in 1992 it was an attempt to create a reference

manual for everyone who works professionally with paper-

board material. Over the years the book has been much

appreciated, and in addition to its purely professional use

within the graphics and packaging industries, the book

also features in courses given by a number of universities

and other third-level educational institutions. Our ambition

has been to maintain a high level of factuality and neutrality

of information so that the Paperboard Reference Manual

will remain a credible work of reference.

In this, the second, revised edition, we have continued

with this tradition, with one exception. In this introduction

you are now reading, we discuss some aspects of paper-

board which are not so easy to quantify or assess.

Paperboard – a natural materialAs a material, paperboard is special. It is the material with

the highest added value within the material system com-

prised of paper and paperboard, and is most often used

for packaging and high-quality printed materials.

This material system includes everything from virgin

fi bre-based paperboards, such as Invercote and Incada,

to paper products made of fi bres that have been repeat-

edly recycled. In the market for paper-based products,

pricing is typically based more on price per unit of weight

than price in relation to the end result in terms of its func-

tions, visual appearance and economy of production.

In a typical advertising or packaging project, great effort

is taken to fi nd the right designer and photographer, and

to handle all the produced material in the optimal way

throughout the production chain. As manufacturers of

high-quality paperboard, we are sometimes astonished

at how casually many producers of packaging and printed

materials choose their input material, after having taken

considerable care over the quality of the entire process

that precedes printing or converting. It is easy to fi nd ex-

pensive catalogues or cartons whose colour-printed areas

have cracked along the crease even before any consumer

or reader has handled them. There are also countless

brochures, whose cover, if it had been made of stiff pa-

perboard instead of thick fi ne paper, would have had far

greater impact on the recipient’s experience of quality.

Virgin fi bre-based paperboard is the paper-based mate-

rial with the greatest added value, and for many applica-

tions there are simpler and more cost-effective solutions.

However, for anyone who wants the possibility of creating

more complex shapes to attract attention, for anyone

who wants taint- and odour neutrality, or for anyone who

is looking for the ultimate in printing properties, our virgin

fi bre-based paperboards, Invercote and Incada, are inter-

esting options. If the potential purchaser then explores

how these paperboards behave in graphic post-produc-

tion or in packaging lines, the conclusion is even more

clear: the key issue is not price per kilo, it is performance.

When purchasing the input material, it is important to as-

sess the cost per useable end product instead of merely

considering the price per kilo.

Experiencing paperboard European paperboard normally has a multi-layer structure

that creates a stiffness which exceeds that of all single-

layer, cellulose fi bre-based materials. This stiffness is part

of the quality that we offer our customers and that can be

exploited to reinforce the quality experience or reduce the

grammage of the input material.

Another parameter which is often used when choosing a

material is the degree of measured whiteness. Whiteness

as measured on the paper and board market is a simple

number which is a combination of three different measured

values. The equation by which these values are assessed

is such that paperboards which look completely different

can have the same whiteness value. What is most absurd

is that the blue shade, which causes major problems when

printing accurate skin tones, is rewarded in this combined

calculation of whiteness. At Iggesund, we have deliber-

ately chosen not to attain the highest whiteness measure-

ment. We do not want our paperboard to become bluer in

a purely optical sense, which would make it harder for our

customers to accurately reproduce skin tones. We would

have no problem becoming even whiter if we wanted to,

but we have chosen a whiteness level for good colour

reproduction.

Paperboard within the goods fl owPaperboard is one of the most widely used packaging

materials in the world thanks to the economic benefi ts it

offers throughout the chain from producers to consumers.

Carton blanks can be transported fl at and cost effectively

until they are erected and fi lled with the contents they are

designed to protect and preserve throughout the dis-

tribution chain to the consumer. The printing properties

of paperboard packaging make it easy to convey both

commercial messages that encourage purchase and

legally required information about the contents. Paper-

board packaging can also be recycled as a material or its

stored biogenic energy can be recovered via combustion

or anaerobic digestion in accordance with the appropriate

environmental targets. Paperboard is also compostable,

which means that as a material it functions in all the waste

streams listed in the European directive on packaging and

packaging waste (EC94/62).



For a better environmentAt Iggesund, paperboard production goes hand in hand

with sustainable forest management. For every tree which

is harvested and used in our production process, we plant

three or four new ones. The result is a sustainable closed-

loop cycle that stretches over a century or more. Those of

us who are now collecting the pine cones containing the

seeds for these new trees will not be alive when Iggesund

harvests the trees that will be the fruits of our labour.

Our operations at both Iggesund and Workington are

energy effi cient and their environmental performance fi g-

ures are well within the limits prescribed by their permits.

One of our long-term goals is to further minimise the im-

pact of our large-scale industry on the local environment.

At the most fundamental level, we live off what nature

gives us. A business that bases its operations on this fact

– and has done so for more than four centuries – must

have a sustainable and long-term approach.

We produce one of industrial society’s most environ-

mentally sustainable products. It is made from a renew-

able raw material and can be recycled both as energy and

material. It has minimal impact on our air and water, and

produces no waste material that is sent to landfi ll.

As a material, paperboard is a good component in any

sustainable environmental strategy.

We work within the most sustainable material system in

existence. We have been responsible stewards of our raw

material for centuries. Our manufacturing is integrated

– we transform our own timber into pulp that is optimised

for board production, which gives advantages of produc-

tion economy, quality and quality consistency. Rising

energy prices and more stringent environmental demands

are increasing paperboard’s relative competitiveness

versus other material systems.

On the horizon are a greater use of biomass, smarter

energy solutions that further improve our economy of

production, and new spinoff products that make the forest

raw material even more interesting. Paper and paperboard

are a material system whose raw material is renewable,

whose products are recyclable in many ways, and where

there already exist sophisticated systems for on-site recy-

cling and energy recovery.

Our history goes back many centuries but our material

still has a long future ahead of it!

Paperboard is a natural material with many applica-

tions. As a print medium, paperboard can withstand all the

strains and stresses involved in the use of advanced fi nish-

ing techniques. Paperboard is also highly durable, ensur-

ing that printed materials will last for a long time. Typical

graphical applications are book covers, cards, and CD

and DVD covers. Paperboard packaging is a competitive

method of conveying products from the manufacturer to

the consumer while also being easy to recycle. In terms of

graphic design, paperboard’s excellent printing properties

give brand owners great freedom to express their brand’s

individuality and thereby attract the consumer’s attention.

Compared to other materials, paperboard made of virgin

fi bres has high performance and relatively low weight. It

is safe for consumers to use because it contains known

substances and is made in the same way every time.

In most cases paperboard packaging remains folded or

fl at until the products are packed. Thanks to paperboard’s

small volume and low weight, large amounts of energy are

saved in the transport chain. Paperboard cartons can be

dimensioned to maximise the use of loading pallets, which

leads to further signifi cant energy savings in the distribu-

tion chain. When paperboard cartons have served their

purpose they can be folded and compressed before being

transported to a suitable recycling station. At every step

of the way, paperboard packaging saves more energy and

has lower environmental impact than most other packag-

ing solutions.

Paperboard is made from timber, which is a renewable

resource. Sunlight and water make the trees grow, while

they also bind carbon dioxide and give off the oxygen es-

sential to life. The forest’s closed ecological loop provides

us the raw material for paperboard, while used cartons

and printed matter have their own role to play in the recy-

cling system of a sustainable society.

An overall viewIn considering the merits of packaging and graphical ma-

terials, or the impact of their manufacture on the environ-

ment, it is important to take a holistic view. The issues to

be considered will normally include four key subjects – the

use of raw materials and energy; the production process;

product and function; and final recycling or disposal.

It is meaningless and misleading to address narrow

issues within any of these broad headings, and at the

same time ignore considerations arising from the wider,

overall view.

Meeting real needsAs one of the longest surviving materials for communica-

tion and packaging, paperboard has been meeting the

requirements of many societies for a long time.

Nowadays, discussions about the general topic of

packaging often focus on the issue of whether or not

packaging actually serves a useful function. The question

is often raised in very simplistic terms – is packaging really

necessary?

In fact, effective packaging has helped to revolutionise

the mass distribution of products in advanced industrial so-

cieties. In many cases the existence of effective packaging

actually saves spillage and waste by protecting and

preserving products en route from the manufacturer to the

retailer and on to the consumer.

Packaging meets real needs. Consumers need to have

a wide choice of conveniently available, well presented and

well packaged products from which to choose. Manufac-

turers and retailers need to effectively impart information

and attract purchasers.



Raw materials As we explain in the description of our manufacturing

process, the wood fi bre used to produce our products is a

renewable resource. The managed forests which supply

the timber are constantly replenished. A vigorously grow-

ing forest is effi cient in absorbing carbon dioxide, fi xing

carbon, and producing oxygen.

Energy The chemical pulping process is highly energy effi cient and

the chemical recovery in the pulping process is also very

high. The production of pulp and the manufacture of pa-

perboard are carried out on the same site in a continuous

integrated process, giving benefi ts in quality, effi ciency,

and economy.

Taint and odourThe taint and odour characteristics of the packaging itself

are of prime importance where long term close or direct

contact must not impair those characteristics of the prod-

uct it is designed to protect.

The selected packaging must therefore be produced

from raw materials which are made from pure materi-

als, selected and processed under carefully controlled

conditions. Following manufacture, the application of inks

and varnishes also requires careful control to ensure that

residues do not remain and have an impact on the taste

and odour of the product.

Knowledge materialThe Iggesund Paperboard Reference ManualThe Iggesund Paperboard Reference Manual is part of the

Iggesund Anchor MaterialIggesund Anchor Material, a body of information material

that also consists of the following publications:

• Iggesund Product Catalogue• Paperboard – the Iggesund Way• Graphics Handbook – Paperboard the Iggesund Way• www.iggesund.com

The Reference ManualThe Reference Manual is the most extensive and techni-

cal of these texts. It attempts to convey all the collected

knowledge we can present with regard to the design and

production of paperboard applications. The Reference The Reference

ManualManual is primarily a consultative document intended to

assist readers who wish to improve their possibilities of

getting the most out of their paperboard material. It places

great emphasis on paperboard properties, since these de-

fi ne and limit the performance it is possible to achieve with

this natural material – whether that performance involves

effectively conveying a message or effi ciently transporting

a product through the entire distribution chain.



The objective of the Iggesund Anchor MaterialIggesund Anchor Material is to assist

people involved in specifying, selecting, printing, convert-

ing or using paperboard. Both the experienced paper-

board user as well as the less frequent user should fi nd the

information they require within this information package.

The Iggesund Paperboard Reference Manual contains the following information• basic facts about paperboard

• paperboard appearance and performance properties,

and their interdependencies

• paperboard conversion methods and the possibilities/

requirements they place on paperboard properties.

The Product Catalogue provides• facts and fi gures about paperboard properties

• general technical information about paperboard

handling, quality assurance, product safety regulations,

sustainability and paperboard terminology.

Paperboard – the Iggesund Way

Contains basic facts about Invercote and Incada and the

paperboard manufacturing process. It also describes the

customer benefi ts available from Iggesund Paperboard’s

mills and paperboard manufacturing processes, customer

support and service.

The Graphics Handbook – Paperboard the Iggesund Way

Focuses primarily on graphical production and fi nishing,

and only touches on the topics of packaging design and

materials knowledge. Selected parts and digital versions

of the publications are available on www.iggesund.comwww.iggesund.com.

If you require further help, please contact your local

Iggesund Paperboard representative.

The information in the Iggesund Anchor Material Iggesund Anchor Material is

correct at publication. It is subject to review as part of

Iggesund Paperboard’s commitment to continuing prod-

uct development.


The philosophy of choice


The paperboard choice is determined by the end use

application. We recommend, as the fi rst priority, that the

end use needs are analysed in terms of appearance and

performance.

Aspects of appearance and performance needs for the

two major applications, graphical and packaging prod-

ucts, are described below.

GraphicsGraphical applications can be postcards, brochures, or

book covers. The purpose is to convey a message and

paperboard is the medium. The medium is always a part

of the message, so the appearance of the medium must

correspond to the message it carries.

Printed texts and graphic images are used to convey

the message. A metallic, glossy or matt appearance is an

effective way of giving the graphical product, such as a

magazine cover, an exclusive image. Relief and creative

shapes can be used to generate interest.

A graphical product that may be handled many times,

for example a book cover, requires considerable durability.

Transportation costs can be a major part of the total

production cost in graphical applications, for example

postage costs when mailing brochures to customers.

PackagingThe primary task of a package is to protect the contents

from the surrounding environment, which might include

impacts during handling, pressure in stacking, and

extremes of temperature and moisture. In addition to its

strength the paperboard package is also very suitable for

promotional purposes.

During transportation the protection requirement is

decisive, but on a shelf in the grocery store the package

is more promotional than protective. The major purposes

of the package, which can change in emphasis during the

products life cycle, are:

• Protect the product during transportation and storage.

• Promote the product with an attractive appearance.

• Inform the consumer about how to use the product.

• Protect the product during consumer use.

The demands for protection might vary as well as the

needs for promotion. Each end use application has its own

combination of protection and promotional requirements.

Promotional needsThe package promotes the product and creates an im-

age of the product for the customer. The product and the

package must create the same impression. An exclusive

perfume needs a package with a corresponding appear-

ance, for example a metallic fi nish. Pharmaceutical prod-

ucts often have packages which are very white to empha-

sise the image of a clean and effi cacious product.

Packages with creative shapes attract attention. An exist-

ing product might be given a new package to increase

sales. Paperboard as a material provides endless options

for constructing creative shapes.

Physical protection needsThe concept of physical protection involves the end user’s

requirement that the packages withstand external forces

in order to protect and hold its contents under various

condi tions. This protection is needed during transport

and storage.

To meet extreme requirements, e.g. deep-freeze appli-

cations, additional functional protection is required.

Protection can also be vital during use. A cigarette pack,

for example, must still look attractive after being carried in

a handbag or pocket.



Possibilities and contradictionsPromotional and physical protection needs are met by

the properties of the paperboard, e.g. smoothness, stiff-

ness and strength. Whilst it is always possible to fi nd an

optimum paperboard solution for packaging and graphi-

cal needs it is important to realise that properties such as

smoothness, stiffness and strength, while they all vary with

density, do so in different ways due to the laws of nature.

Limitations due to the laws of natureStiffness and strength are two properties which are depend-

ent on the density of the paperboard, but in opposite ways.

This contradiction is due to the laws of nature and is related

to the characteristics of the cellulose fi bres. The general re-

lationship between stiffness, strength, surface appearance

and density is shown in the illustrations.

Relative economy of productionIf a product is expensive, the package will be more intri-

cate and exclusive to match the product. However, the

cost of the package as a percentage of the value of the

product is still very low.

Runnability is a property which is of great importance

when comparing the economy of production of various

materials. If the chosen paperboard causes a lot of pro-

duction stops in converting and fi lling, due to low runnabil-

ity, it will result in a costly package. A wise choice in the

beginning saves a lot of money in the end. When consid-

ering production economy in choosing paperboard it is

important to have an overall view.

ConsistencyThe importance of consistency cannot be overemphasised.

The demand for consistency applies to all paperboard

properties, including both appearance and performance

parameters.

Two aspects of consistency are relevant:

• consistency within the order

• consistency between orders.

The cost benefi t of conversion and use without prob-

lems and wastage is signifi cant. Short runs with frequent

make-ready stops for new jobs put increased demands on

reliability. It is a great advantage if settings from a previous

run can be used again and again, thereby avoiding costly

adjustments.

When choosing a paperboard it is therefore important

to choose a paperboard supplier that has a documented

reliability. The consistency criterion is probably the most

important paperboard requirement.

ST

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DENSITY DENSITY

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DENSITY


The paperboard product


Since the mid-19th century the primary source of cellu-

lose fi bre has been wood. The fi bre is separated by either

chemical or mechanical means from naturally occurring

species. In the case of Iggesund these species are mainly

spruce, pine and birch from managed forests in Scandina-

via and elsewhere in Europe. Such forests are maintained

and expanded by the industries that rely on good access

to timber. As a result of these efforts the stock of growing

trees is increasing every year. In many areas growth now

exceeds the amount of timber that is harvested.

This careful forest management ensures that even in the

future the forests will form part of the sustainable cycle of

nature and be a permanent source of raw materials.

The fi bres in a tree trunk run parallel to its length. The

fi bre length varies according to the tree species. The rela-

tionship is indicated by the table below.

Spruce fi bre – long and fl at Birch fi bre – short and cylindrical

Pine fi bre – long and fl at Mixed fi bres of spruce, pine and birch

Species

Spruce

Pine

Birch

Fibre length mm

3.1 – 3.5

2.0 – 3.0

0.9 – 1.2

Fibre width μm

19 – 50

22 – 50

20 – 35

Shape

Ribbon fl at

Ribbon fl at

Cylindrical with pointed

ends



Cellulose and the laws of natureCarbon dioxide and water are converted into simple

glucose-based sugars by the action of sunlight on the

green chlorophyll-containing cells of the plant kingdom.

This process is known as photosynthesis and is accompa-

nied by the emission of oxygen. The natural sugars can be

polymerised in plants to produce cellulose.

Cellulose has a high molecular weight and a straight-

chain molecular structure. Plants use cellulose to grow

by constructing cells – what we call fi bres – and other struc-

tures which support the life of the plant. Each species has

its own characteristic fi brous structure. Many tree species

have been cultivated and developed over time into a renew-

able source of raw materials for the production of a wide

range of paper and paperboard products. Careful forest

management and the manufacture of paper products are

therefore closely linked.

Cellulose makes up around 44 % of the wood fi bre.

Pure cellulose fi bres are soft, fl exible and white. The other

constituents are hemicelluloses, lignin and extractives.

Hemicelluloses are a group of substances related to cellu-

lose but have lower molecular weight and a more compli-

cated chain structure. Lignin is a more complex polymer

and very different from cellulose. It is hard and brittle. Both

hemicelluloses and lignin occur in the fi bre but the main

concentration of lignin is between the fi bres, giving adhe-

sion and rigidity to the structure of wood.

The process of fi bre separation, or pulping, takes ad-

vantage of the differences between lignin and cellulose.

More laws of natureThere are natural properties which all wood fi bres have to

a greater or lesser degree as well as specific properties

associated with the fi bres of particular tree species. Fibre

characteristics are also infl uenced by the method of pulp-

ing which is used.

The general properties • The ability of fi bres to grip each other and bond into a

strong, homogeneous structure.

• Flexibility, shape and dimensional properties which en-

able fi bres to form a uniform interlaced network.

• The capacity of the fibres to be favourably modified,

mechanically or by using additives, during the production

process.

Different levels of magnifi cation of the wood fi bre,

revealing the difference between the seasonal growth

and a close-up of the fi bre showing its hollow interior

and the thin layer of lignin holding the fi bres together

CARBON DIOXIDE (CO2)

SUNLIGHT

OXYGEN (O2)

WATER (H2O)

CHLOROPHYLL

SUCROSE, ETC


Choices of raw material


Types of fi breBasically the choice is between long fi bres (spruce/pine)

and short fi bres (e.g. birch). The board maker carefully se-

lects and blends different fi bres to achieve the appearance

and functional properties desired for specifi c products.

Types of pulpThere are three different pulping processes, which all pro-

duce different kinds of pulp: mechanical, chemical, and

recycled fi bre.

MechanicalThis process gives a very high yield of fibre from the tim-

ber. The presence of lignin in the pulp makes the fibres

hard and rigid. This produces a paperboard with high

stiffness, limited strength, low density and lower resil -

i ence. Mechanically separated virgin fibre pulp contain-

ing lignin reacts more strongly to changes in external

environment, humidity and temperature, a reaction that

can have a negative effect on flatness and dimensional

stability.

As a result, paperboard made solely from mechanical

pulp is relatively weak. The paperboard retains the yel-

lowish colour of the wood used and is pure because it

is made solely of natural and known raw materials.

ChemicalThis process preserves the length of the virgin fi bre. The

pure cellulose extracted has a high degree of consolida-

tion. Both of these features produce a very strong paper-

board sheet.

The fibre is flexible and soft, giving good creasing,

embossing, and die-cutting properties and low dust

generation.

Bleached cellulose pulp has high whiteness, brightness

and light stability. Paperboard made of virgin fi bre pulp has

the highest possible purity and provides packaged prod-

ucts with the best odour and taste neutrality.

RecycledThis separation and recycling process utilises a wide vari-

ety of waste paper and board. Each time a fi bre is recycled

it is contaminated and shortened and its capacity for con -

solidation is reduced. This means that virgin fibre must

be added to maintain the quality of recycled pulp. Recy-

cled pulp is carefully cleaned and screened during stock

preparation. Mixed waste paper is not usually de-inked

for paperboard manufacture and hence the pulp may

retain traces of inks, adhesives and other residues which

together give this kind of paperboard a grey colouration.

The resulting product has less predictable composition

and poorer functional properties than virgin fi bre-based

boards.

Mechanical pulp Chemical pulp



In addition to the types of fi bres and pulp, the construction

and coating of the paperboard sheet also affect the paper-

board’s fi nal properties. Selecting and combining types of

fi bres, the pulp preparation process, sheet construction

and coating give the paperboard the fi nal properties it

needs to meet a wide variety of market demands.

Solid bleached board (SBB)SBB is made exclusively from bleached chemical pulp. It

usually has a coated top surface and some grades are also

coated on the reverse side. The term SBS (Solid Bleached

Sulphate), derived from the method of pulp production, is

sometimes used to describe this product.

This is a medium density paperboard with excellent sur-

face printing properties to meet graphical and packaging

needs. It gives a wide scope for structural design and can

be cut, creased and embossed with ease. It is a pure and

hygienic primary fi bre paperboard and is suitable for the

packaging of aroma and fl avour sensitive products.

Folding box board (FBB)FBB comprises middle layers of mechanical pulp sand-

wiched between outer layers of chemical pulp. The top

layer of chemical pulp is bleached and pigment coated.

The back of the paperboard is cream (manila) in colour.

This is because the back layer of bleached or unbleached

chemical pulp is translucent, allowing the colour of the

middle layers to infl uence the appearance. The back layer

may, however, be thicker or have pigment coating – this

product is known as White Back Folding Box Board. The

combination of inner layers of mechanical pulp with outer

layers of chemical pulp creates a strong and stiff sheet,

taking advantage of the well-known I-beam principle in

physics. The mechanical pulp can be of CTMP (Chemi-

thermomechanical pulp), RMP (Refi ner mechanical pulp)

or TMP (Thermomechanical pulp) origin. This is a low den-

sity material with high stiffness. Fully coated grades give

excellent printing and visual impact. This is a primary fi bre

paperboard with consistent purity for product safety.

Solid unbleached board (SUB)SUB is made exclusively from unbleached chemical pulp.

The base board is brown. To achieve a white surface it

might be coated, sometimes in combination with a layer

of bleached, white fi bres under the coating.

The paperboard is used where there is a high strength

requirement, e.g. carrier sleeves, liquid packaging, etc.

Bytas ut till 3-skickt , Elisabeth pratar

med elena

FBB cross section

Coating

Bleachedchemical pulp

Unbleachedor bleachedchemical pulp

Mechanicalpulp

SUB cross section

Unbleachedchemical pulp

Coating

SBB cross section

Coating




White lined chipboard (WLC)WLC comprises middle plies of recycled pulp. The top lay-

er or liner of bleached chemical pulp is frequently pigment

coated. The second layer or underliner may also comprise

bleached chemical pulp or mechanical pulp.

The reverse side layer can be made from specially

selected recycled pulp or may be white through the use

of bleached chemical pulp. There are additional grades of

unlined chipboards with coloured (dyed) liner plies.

This is a medium density product which is widely used

in general packaging. It is diffi cult to generalise about WLC

because of the wide range of qualities available.

Abbreviations/keys According to DIN 19303

GZ Coated SBB

AZ Cast Coated SBB

GC1 Coated FBB, white back

GC2 Coated FBB, cream back

GN Coated SUB, white or brown back

GT Coated WLC, cream or white back

GD1 Coated WLC, grey back (spec.volume >1.45 cm³/g)

GD2 Coated WLC, grey back (spec.volume 1.3 to 1.45 cm³/g)

GD3 Coated WLC, grey back (spec.volume <1.3 cm³/g)

UZ Uncoated SBB

UC1 Uncoated FBB, white back

UC2 Uncoated FBB, cream back

UT Uncoated WLC, cream or white back

UD Uncoated WLC, grey back

SBB Solid Bleached Board

FBB Folding Box Board

SUB Solid Unbleached Board

WLC White Lined Chipboard

G Gestrichen, coated

U Ungestrichen, uncoated

A Gussgestrichen, cast coated

Z Chemisch gebleichte Frischfasern, bleached virgin

chemical pulp

C Holzstoff, virgin mechnical pulp

N Chemisch ungebleichte Frischfasern, unbleached

virgin chemical pulp

WLC cross section

Coating


Bleachedreclaimed pulp

Selected wasteor unbleachedchemical pulp

Selected waste


Differences paper and paperboard

Cross section of a multi-ply paperboard


Defi nition of the term paperboard varies. According to the

ISO standardisation body, a paper product with a gram-

mage exceeding 200 g/m² is called paperboard; however

the defi nition by the Confederation of European Paper In-

dustries, CEPI, reads “paper is usually called board when

it is heavier than 220 g/m²”. Paper board can be made in

a single ply or, more commonly, in several plies (multi-ply).

For quality reasons paperboard usually requires a com-

bination of several layers of fi bre in the wet state. When

studying the traditional paperboard market one can see

that multi-ply paperboard is already made at 160 g/m².

Two clear features distinguish paperboard compared

to paper:

• Paperboard contains a greater proportion of long fi bre

than paper.

• Paperboard does not normally contain fi llers.

At Iggesund Paperboard we claim that paperboard is a

heavier paper product of multi-ply construction.

The advantages of the multi-ply construction lie in the

ability to optimise fi bre characteristics in the different plies

to reach certain functionalities. This is done by varying the

content in each ply. The main features to vary are:

• proportion of long and short fi bres in the respective plies

• type of pulping method

• treatment of pulp to improve strength or bulk quality and

distribution of broke in the structure.

To be able to fully utilise the potential of optimising char-

acteristics in the paperboard it is crucial that the multi-ply

construction consist of at least three plies.

The existence of a middle ply enables the paperboard

maker to optimise surface characteristics in the outer

plies without losing stiffness and paperboard converting

advantages which are built in to the middle ply. The dual-

ply or single ply construction will always lead to one or

more compromises. Features which are easier to optimise

in a multi-ply construction than in a single ply construction

without compromising are:

• bulk

• strength

• stiffness both through high thickness and strong outer

plies

• surface smoothness in combination with desired

strength or stiffness achievements

• functional features in the respective plies such as in-

creased moisture resistance in surface or middle plies.

The ability to alter all these parameters has resulted in a

wide range of products in the industry which target certain

applications and end uses by tailoring features, as can be

seen in the following pages. The advantage of a multi-ply

construction in a paperboard mill is that the quality can be

adapted to different end uses by utilising the possibilities

of fi ne tuning the features mentioned above. This makes

it possible for one supplier to manufacture and supply

paperboard to meet the demands of several different end

uses, whereas a single-ply or dual-ply producer has more

limited possibilities.

Coating

Top ply

Centre plies

Bottom ply



Characteristics of paperboard manufactureIn the beginning of the 20th century the production and

distribution of goods and food products increased and so

did demands for better protection of these items. A cheap

and easy solution was to use boxes made of thicker paper.

A change in the retail industry at this time from selling

products in loose bulk to selling products that were pre-

packed placed demands on packaging to be used not only

for protection but also for display. It became more import ant

to attract the consumer to recognise a product in the store

and pick up a specifi c product for purchase.

Papermakers had to specialise in order to meet box con-

verters’ demands for strong and stiff boxes which protect

the products from collapse during transport and which also

provide good printing and display functions.

Traditional thick paper was no longer good enough. As

a result, the fi rst paperboard machines were developed in

the United States.

Board machines are commonly built for optimum produc-

tion between 200 g/m² and 1000 g/m² while paper machines

have their optimum production grammage range from 70 to

200 g/m² depending on the intended application/end use.

From the layman’s point of view, a paperboard machine

and a paper machine can appear to be very similar. The dif-

ferences lie in the details. To examine these, we must look at

the different sections on the two machines’ confi gurations.

Fibre selection and stock preparationFor a board maker, the selection and refi ning of fi bres

depend both on the specifi c surface properties required

for printing and display and on the requirements for box

converting and the subsequent protection of the box’s

contents.

Using strong and long chemical fi bres from softwood

in the outer layers of a board and more bulky fi bres in the

middle layer is ideal for achieving the relevant stiffness and

strength properties.

Chalk is cheaper than fi bre and is often used by paper-

makers to reduce cost, improve opacity and improve sur-

face properties. However, chalk cannot be used by board

makers because doing so results in a deterioration in the

strength properties of the board. Both board and paper can

be made from recycled fi bres but the same issue of strength

arises, because recycled fi bres are weaker than virgin fi bres.

Stock preparation for board makers must be optimised

for stiffness, strength and surface properties. In contrast,

papermakers can focus solely on surface properties.

In producing board and paper for packaging foods, fatty

foods or liquids, manufacturers add chemicals to prevent

the fi bres absorbing grease or liquid from these contents.

Chemicals used for this type of application must comply

with regulations and directives from the EU and from the

FDA in the United States.

The wet end Paper and board are today produced both on a single wire

machine and on a multi-wire machine.

A board manufacturer selects the multi-wire construc-

tion of the wet end to meet the required surface, stiffness

and strength properties.

For a board maker with a multi-wire machine, the ideal

method is to combine different types of chemical fi bres in

the outer layers to achieve strength and good surface pro-

perties, and then to use one or more centre layers made

of more bulky fibres. Fibres produced by a mechanical

pulping process provide more bulk and are often used by

board makers in the centre layers.

Single-wire machines permit fewer possibilities to opti-

mise bulk, and board makers must compromise more

between stiffness, strength and surface properties.

Board manufacturers who use virgin fi bre are able to

specialise and optimise the sheet better, although board

manufacturers who use recycled fi bre will use similar tech-

niques in how they select and refi ne the fi bre.

The press sectionPhysically pressing out the water from the sheet in the

press section uses less energy than evaporating the water

in the drying section of the machine.

For a board maker, it is essential not to destroy the

strength and bulk properties of the sheet (which have

been built up in the wet end of the machine) in the press

section. At the same time, it is important to press out as

much water as possible so as not to lose economy of

production.

Over the years, board manufacturers have developed

press sections that are more forgiving and have a longer

press nip in order to achieve a high dryness of the sheet

before entering the drying section without compressing

the sheet too much and destroying its bulk, stiffness and

strength.

The drying sectionThere is no major difference between a board machine and

a paper machine. The drying section will typically consist

of a number of steam fi lled cylinders in contact with the pa-

per or board; the number used will depend on the amount

of water to be evaporated. The steam pressure in these

cylinders will be adjustable to control the rate of evapora-

tion and the fi nal moisture content.

CalenderingPre-calendering is used to make the surface of the uncoated

base paper or board as smooth and even as possible so as

to prepare the sheet for the subsequent coating operation.

Finish calendering or gloss calendering is used to improve

the coated surface and/or increase the gloss of the paper.



Cross section of paperboard

Both paper- and board makers also use calendering tech-

niques to achieve improved surface properties. However,

excessively hard calendering can easily destroy the bulk of

the sheet and thus the stiffness and strength properties of

the board.

Various types of calendering techniques have been

developed in the board industry such as soft nip, long nip

and metal belt calenders. Using these techniques it is pos-

sible to improve the surface without reducing the bulk.

CoatingThe coating operations for paper and board are basically

the same. The difference lies in the coating recipes. Board

manufacturers have different requirements than paper

manufacturers, depending on the intended application.

Converting board into boxes carries specifi c demands,

such as suitability for gluing functions. These must be taken

into account when optimising the coating recipe and testing

its suitability. Because one of the function of packaging is

to protect and not to contaminate its contents, liquid board

and board used to package food must be taint and odour

neutral. Accordingly, the chemicals used in the coating

must meet all the relevant safety requirements.

Winding, slitting and sheetingThere are no major differences between paper- and board

makers with regard to the winding, slitting and sheeting

operations. In order to provide the correct end user ap-

plication and be able to guarantee that the paperboard

has been produced under carefully controlled conditions,

board makers must have a system of full traceability

throughout the process.

100 μm


Fibre to board

Fibre to board

Today’s processes of separating fi bre and making paper-

board take place in facilities characterised by capital

intensity, high production volumes and the application of

the latest techniques of materials handling, continuous

production and process control.

In many cases, including the mills of Iggesund Paper-

board, the production of pulp and the manufacture of

paperboard are carried out on the same site in a continu-

ous integrated process, giving benefi ts in quality, effi ciency

and economy.

Managed forests provide the primary source of cellulose

fi bre from wood varieties such as spruce, pine and birch.

The fi bre is separated by mechanical or chemical pulp-

ing and the whiteness and purity may subsequently be

improved by bleaching.

Processing on the paperboard machine starts with the

formation of a layer of entangled fi bres on a moving wire

or plastic mesh from which water is removed by drainage.

Further layers of pulp are usually combined in the wet state.

More water is subsequently removed by pressing and dry -

ing. Paperboard is coated on-line or off the machine to

improve the printing surface. Large diameter, full machine-

width reels are produced by the machine. These reels are

subsequently cut into smaller reels or sheeted, labelled,

and wrapped prior to dispatch to the customer.

The forestry cycleThe virgin fi bre for paperboard is derived from naturally

occurring species such as spruce, pine and birch, which

provide fi bres with suitable characteristics. These species

are supplied by managed forestry operations in Sweden

and other parts of Europe.

To maintain sustainable development, including the re-

quirements for biological diversity, modern forest manage-

ment makes use of several combined methods. Detailed

planning is done at both a county and local level. Natural

regeneration, planting and sowing are used. Biologically

sensitive areas and old growth forests are protected ac-

cording to the local conditions.

Another important characteristic is that managed for-

estry is an integrated operation whereby wood for pulping

is harvested with wood for the timber industry. Thinnings,

the smaller diameter trees taken from the forest at vari-

ous stages to allow other trees room to mature, are used

to produce pulp. When mature trees are harvested, the

thicker part of the trunk is used as sawn timber, and the

tapered top goes to the pulp mill. This ensures maximum

use of the harvested timber.

Making the best use of raw materials is a key principle

within Iggesund Paperboard. The trees supplied to the

mills are transformed into paperboard – but also into the

energy that drives the production process, heats nearby

homes and dries sawn timber. Other end products are soil

compost and road-building material. Using the entire tree

is an important part of our ambition to carry out sustain-

able production.

From timber to fi bre – the pulping processThe timber logs which are delivered to the pulp mill are fi rst

debarked, since bark does not contain fi bre suitable for

pulp manufacture. Bark is removed by friction, as logs are

tumbled together in a rotating drum. The bark is then used

as a fuel within the mill or composted to create garden soil.

The next process depends on the type of separation or

defi bration process used.

Pulp manufactureBasically the choice is between long fibres (spruce and

pine) and short fibres (birch). The boardmaker optimises

sheet forming, appearance and performance properties

with an appropriate choice and blend of fi bres to meet the

needs of particular products.

PLANTING0-3 years

CLEANING3-15 years UK

3-30 years Sweden

HARVESTING30-50 years UK80-120 years Sweden

THINNING15-30 years UK30-80 years Sweden

pulpwood

pulpwood

sawn timber


Fibre to board


Fibre to board

Mechanical pulp characteristicsThis process gives a very high yield from the timber. The

presence of lignin has a number of implications – the fi bre

is hard and rigid and this gives the sheet a limited degree

of consolidation, high bulk (low density), resilience, dimen-

sional stability, and stiffness.

The presence of lignin and the limited degree of consoli-

dation would make a sheet made solely from mechanical

pulp relatively weak. The pulp retains the colour of the

wood used and is of known natural composition and purity.

Refi ner mechanical pulp (RMP) is a two-stage process in

which the debarked logs are fi rst converted into small fl at

chips. These chips, with a moisture content of 25–30 %,

are forced between the rotating metal discs of a refi ning

machine. The heat and water vapour generated soften the

lignin so the fi bres can be separated. The pulp is screened

and cleaned and fi bre clumps are reprocessed.

Mechanical pulping results in a very high yield. About

95 % of the wood is converted to fi bre. Mechanical fi bre

separation requires high levels of electric power, and some

of the energy is usually recovered and used as heat in the

process.

Logsof raw

material

De-barking

Bark forfuel or

compost

Chippingand

washing

Refinerdefibration Bleaching

Washing+

Pulp toboard mill

WOODCHIPSILO

To screensand cleaners

REFINEDFIBRE

BLEACHING

REFINER

Preheater

EXCESS CHIPSRECIRCULATE

CHIP WASHERAND DEWATERER

Preheater

CONVEYORS

Preheater

MeteringScrewConveyors


Fibre to board

Chemical pulp characteristicsThis process preserves fi bre length and the pure cellulose

develops a high degree of consolidation, both features that

give a very strong sheet.

The fi bre is fl exible and soft, giving good creasing, emboss-

ing, and cutting properties and with low dust generation.

Bleached cellulose pulp has high whiteness, brightness,

and light stability. This material has the highest purity and

provides products with the best odour and taint neutrality.

In the chemical process timber is fi rst converted into wood

chips. These are then cooked in chemical solutions to dis-

solve 80–90 % of the lignin, allowing the fi bres to separate

easily.

The sulphate process, which is used within Iggesund,

also permits effi cient chemical recovery and energy utilisa-

tion. The fi bre yield of unbleached chemical pulp relative to

wood is in the range of 50–65 %. The dissolved lignin and

resins from the wood are used in internal energy generation.

De-barking

Barkforfuel

Chippingand

washing

Impreg-nation

Continuouscooking

Washingand

straining

Oxygendelignifi-

cation

Diffusionbleaching

Washing+

Pulp toboard mill

Chemicalrecoveryenergy

generation

Logsof raw

material

Oxygen delignification Final washDoublestraining

NaOH

Pressurediffuser wash

Modified continuouscooking

O2

CIO2 CIO2 O2

H2O2NaOH CIO2 CIO2

PULP

DIFFUSER BLEACHING

DEFIBRATION

CHIPS


Fibre to board

Chips +liquor

High pressure steam

Washliquor

Chips

Impregnated chips(incl. liquor)

Pulp

Caustic soda/sodium sulphidesolution (white liquor)

Causticsoda/sodiumsulphidesolution(whiteliquor) Black liquor

in recycleloop

Reverseflowcooking

Forwardflowcooking

DIGESTERIMPREGNATOR


Fibre to board

BleachingAll the varieties of pulp used in the manufacture of paper-

board can be bleached to infl uence colour and purity.

Chemical pulp is brown in colour, the colour density

depending on the cooking process and degree of lignin

removal. While unbleached pulp may be used for some

purposes, such as corrugated board boxes, it is neces-

sary to whiten the pulp for many graphical and packaging

applications.

The whitening of pulp is called bleaching, though the

process can take many forms depending on a number

of factors. These include the degree of colour change

required, choice of chemicals, method of treatment and

whether coloured compounds are removed (delignifi ca-

tion) or merely changed in colour.

All these factors have technical and economic implications,

not least of which is their environmental signifi cance.

Whitening methods fall into three categories:

• Bleaching by delignification using chlorine gas. This

approach has largely been replaced by processes with

better environmental safeguards. The use of oxygen is

being progressively introduced instead.

• Bleaching by oxidation using materials such as chlorine

dioxide, hydrogen peroxide or sodium hypochlorite.

• Bleaching by reduction using materials such as sodium

bisulphite.

If the pulp mill is integrated with paperboard manufac-

ture, the pulp is pumped to intermediate storage facilities.

If the pulp is sold to the open market it is dried in sheets

or by fl uffi ng and drying in hot air. Market pulp is baled for

shipment.


Fibre to board

Pulp (stock) preparationIf the pulp is bought in bales it is fi rst mixed by agitation in

water in a large vessel known as a hydra pulper. All pulp,

including the pulp which comes straight from the pulp mill

without drying, is then treated in various ways to prepare it

for use on the paperboard machine. The processed pulp

is referred to as “stock”. The consolidation properties of

fi bre can be improved by mechanical processing – refi ning

– which modifi es the surface structure of the fi bre. Swelling

in water expands the fi bres’ surface area, thereby increas-

ing their strength and ability to consolidate.

Additives such as internal sizing can be used to increase

the water repellency of fi bres, and retention aids to increase

dry strength. Fluorescent whitening agents (FWAs), also

known as optical brightening agents (OBAs), can be added

as required to increase the whiteness.

Discards and trimmings from the board making process

– called “broke” – are broken up and mixed into the stock

in varying amounts depending on which paperboard layer

the stock is intended for.

Finally, the “consistency” (fi bre/water ratio) is fi nely

adjusted prior to pumping the stock to the paperboard

machine.

FormingThe fibre suspension in water, at a consistency of around

99 % water, is “formed” in several even layers on a mov-

ing wire or plastic mesh. Each layer has a specific stock

composition suited to the layer’s function in the board

construction. The composition and properties of the stock

depend on the amount of long vs. short fi bres, the kind of

pulp, its degree of refi nement, retention properties, and

the proportion of broke that has been added. The water is

drained with vacuum assistance from the layer of entang-

led fi bres. The layers are brought together in the wet state.

PressingAt the end of the wire section and moving at a speed of

between 100–500 m/min the combined sheet or web is

suffi ciently consolidated to briefl y support its own weight

as it is transferred to the press section on an absorbent

textile blanket. Here the board is pressed together with

blankets between hard rollers and, with vacuum assist-

ance, more water is removed, reducing the moisture

content to around 60–65 %.

DryingThe moisture content is further reduced to 5–10 % (de-

pending on the product) by passing the sheet over steam-

heated steel cylinders. Some machines include in their

drying section a very large heated cylinder with a polished

steel surface. A wet paperboard web will adhere to the cyl-

inder surface and be progressively dried while at the same

time achieving a very smooth board surface. This cylinder

is known as an MG (machine glazing) or Yankee cylinder.

Surface sizingA starch solution can be applied to the paperboard surface

to improve strength and anchor surface fi bres fi rmly in the

sheet. Within Iggesund Paperboard the baseboard is sur-

face sized prior to being coated. When board is surface

sized a starch-based solution is applied to both sides of

the product: this improves surface strength and anchors

the fi bres to the sheet.

CalenderingPassing the sheet through a series of nips between steel

rollers or a soft nip calender can improve its smoothness

and adjust its thickness.

BASEBOARD

SURFACE SIZE

Surface sizing principle


Fibre to board

The forming process

Headbox Fibre suspension

Formed sheet

Wire

The forming process

H2O H2O H2O H2O H2OH2O

H2O98%

H2O90%

H2O80%


Fibre to board


Fibre to board

CoatingPaperboard products are coated to improve the appear-

ance of the product and also to improve performance

during printing.

The processAfter surface sizing the board is coated using blade

coaters, air knife or curtain coating. In a blade coater the

coating is applied to the baseboard using an applicator roll

or a jet applicator. The sheet continues up to a blade that

removes the excess coating. The excess coating is recir-

culated and reused. Once the excess coating has been

removed the paperboard is dried prior to the application

of the next layer of coating.

The coatingWhite pigmented coatings are applied to the print side of

the board and sometimes also to the reverse side. These

consist of selected mineral pigments and synthetic bind-

ers, dispersed in water. Selection depends on product

requirements and processing conditions. The application

and smoothing technique ensures a specifi ed coat weight

and smoothness. Smoothing may be by roll bar, air knife

or blade. There may be one, two or even three coating

layers applied to achieve the required appearance, colour,

smoothness and printing properties. The largest component

of a coating in terms of mass is the pigment. The pigment

used is usually a calcium carbonate (ground marble), clay

or a mixture of the two. The nature of the particles that

make up the pigment has profound effects on the proper-

ties of the paperboard. Calcium carbonate has a very high

whiteness but a relatively low opacity. Clay has a lower

whiteness and its use results in a smooth surface with a

higher gloss level and higher opacity. The second largest

constituent of a coating is the binder, which is often a latex

supplied as a water-borne emulsion. At this stage the latex

is a large number of very small particles. When the latex

is heated during the papermaking process the latex melts

and forms a fi lm that binds the pigment particles to one

another and also to the baseboard. Many other chemicals

are also routinely added to coatings to improve the per-

formance of the coating in the production process and

the performance of the fi nished paperboard.

Brushing and glazingSome paperboard machines incorporate equipment for

further surface enhancement by brushing and glazing.

ReelingThe fi nal process on the paperboard machine is to reel up

the paperboard in the full machine width to specifi ed reel

diameters.

TOPCOATPRECOAT

BASEBOARDBASEBOARDBASEBOARD

SURFACE SIZE

COATING


The paperboard machine

1

1

1

23


The basic features of a typical paperboard machines is

shown below.

1. Multi-ply formingIn contrast to paper, Iggesund paperboards are built up

in several layers, or plies. Fibres are supplied via inlets

(“headboxes”) at the wet end of the paperboard machine.

Concentration at the wet end is approximately 0.3 % fi bres

and 99.7 % water. A low fi bre concentration is essential in

order to obtain as uniform a distribution of fi bres as pos-

sible in each layer. The fi rst layer is formed on a plastic wire

and the water drains downwards. The subsequent layers

are stabilised on two upper wires and water drainage is

done both upwards and downwards depending on wire

and position. In the wet state, the layers of fi bre consoli-

date easily.

Precision in the distribution of fi bres and the consolida-

tion of the fi bre layers is a basic condition for qualities such

as fl atness, smoothness, strength and good creasing

properties.

2. PressingWhen the paperboard web reaches the press section,

water content has dropped to 80–85 %. The press section

is important for achieving the correct consolidation of the

fi bre layers. Sandwiched between two fabrics (felts), the

paperboard web is pressed between hard rolls. The water

is effectively removed so that moisture content in the pa-

perboard at the end of the press section is 60–65 %.

Here, qualities such as fl exibility, stiffness and runnability

are ensured.

3. DryingThe drying section allows optimal control over the drying

process. The paperboard web passes over steam-heated,

polished cylinders which gradually reduce the moisture.

A sophisticated system controls the temperature of the

cylinders to ensure that the web tension is under control

during the drying process.

The drying section establishes a uniform moisture pro-

fi le, fl atness and stability.

4. Surface sizingHere a starch solution is applied to one or both sides to

prepare the paperboard for coating. Surface sizing binds

the fi bres to the surface, making the paperboard more

uniform and dense.

5. CalenderingThe paperboard is passed between rotating steel rolls to

further increase surface smoothness. This process also

controls the paperboard’s thickness and density.

3

4

5

6

9

9

7

9

8

6. Surface coatingThe liquid, white-pigmented coating is applied and

smoothed out over the surface with a blade on either

one or both sides depending on the product. Each layer

is dried independently by infra-red and hot air dryers.

The surface coating section allows paperboard to be

coated twice on both sides to provide a high degree of

whiteness, smoothness and gloss. Coating also deter-

mines the surface’s ink and varnish receptivity.

7. Calendering and polishingThe fi nal gloss of the surface is achieved by gloss calen-

dering in a gloss calender or brush polisher. In the gloss

calender the paperboard web passes between a heated

hard steel roll and a soft polymer roll. In the brush polisher

the paperboard is polished by rotating brushes.

These processes give a uniform, smooth surface – which

is essential for good printing and varnishing.

8. Reel-upThe paperboard web is reeled onto a large steel core,

together weighing 30–40 tonnes depending on the pro-

duct. Each fi nished reel of paperboard is given a unique

identifi cation code which allows the product to be traced

all the way back to the raw materials.

9. Online measurement and controlThe web passes thousands of measuring points from

which data is transmitted to the central control system.

Optical on-line measurement is carried out on the mov-

ing web to check thickness, grammage, coating weight,

moisture content, whiteness and gloss. The resulting

regulation and control capabilities are a prerequisite for

uniform, high quality.

FORMATION SURFACE DEWATERING PRESSING DRYING SIZING DRYING GLAZING COATING GLAZING WINDING

STOCK

Moisture Moisture

Grammage

Thickness

Fibreorientation

OpticalProperties

Formation

Moisture

Grammage

Coat weight

BOARD MACHINE

ONLINE MEASUREMENTMoisture

Grammage

Thickness

Coat weight

Gloss

Optical properties




Extrusion coating and lamination


Paperboard is coated with plastics to combine the me-

chanical properties of the paperboard with the barrier and

sealing properties of plastics. Paperboard combined with

a relatively small number of plastic materials will provide

the extra features needed to make the paperboard suit-

able for a number of specially demanding applications.

Extrusion coating is a process whereby molten plastic is

applied to paperboard and subsequently chilled to form an

extremely thin, smooth layer of uniform thickness.

The molten plastic can be used as an adhesive to lami-

nate a plastic fi lm or a metal foil.

Extrusion coating and lamination are used to achieve:

• moisture protection

• barrier to water vapour, oxygen, aroma, etc.

• grease resistance

• heat sealability

• sales appeal, for example shiny surfaces.

Sales appealThe use of extrusion coated and laminated paperboard

provides outstanding promotional benefi ts in terms of

visual appeal and consumer handling.

High gloss is created by extrusion coating and a specifi c

high gloss chill roll. A metallic effect is created by lamina-

tion with aluminium foil or metallised polyester fi lm. These

materials and processes also provide tactile sensations

of high quality and luxury which the consumer associates

with high value products packaged in these materials.

Examples of extruded and laminated products providing sales appeal • PE (polyethylene) extrusion coating of paperboard with a

gloss or matt fi nish. Printing and gluing (with cold glue) can

be done on a corona-treated surface.

• PP (polypropylene) and PET (polyethylene terephthalate)

are two heat resistant polymers that, applied on the board,

can be used in oven applications.

• Aluminium foil and metallised polyester film may be

laminated to the paperboard to provide a metallic effect.

Printing can be done on a pre-treated surface.

Functional coatingPaperboard as such is suitable for the packaging of dry

products in general. However, plain paperboard is only

suitable for direct contact with moist and greasy foods to

a limited extent, because moisture will affect the mechani-

cal properties of the paperboard, and absorbed grease

will cause stains. Such effects will obviously reduce the

protective function of the package and may detract from

the appearance as well.

Extrusion coating or lamination adds a thin layer of

plastic to the paperboard. Plastic coatings can provide

resistance to grease and moisture and, where appropri-

ate, be heat resistant. Plastic coatings can be heat sealed

and in some constructions these seals can be leak proof.

Depending on the application, the paperboard may be

extrusion coated on one or two sides.

Aluminium lamination provides packages with a barrier

to light, moisture, grease and gases. The aluminium foil

is often plastic coated to provide product safety and heat

sealing abilities.

Key characteristicsA number of process parameters infl uence the

grammage of the coating. The most important are:

• fl ow of the plastic melt

• temperature of the plastic melt.

Print on a foil laminated paperboard where the metal details of the guitar

is locked out of the photograph so that the metallic sheen underneath

is entirely exposed



Applications

Liquids

Frozen foods

Ovenable packs

Description

Ice cream and soft drinks require a good water barrier.

Two side extrusion coatings are often required to main-

tain the rigidity of the cups. First class runnability in the

cup forming machine is an absolute necessity.

Frozen foods which are pre-frozen and packed as such

can usually be packed in one-side plastic coated paper-

board. Other products, which are packed wet and even

hot for chilling and freezing in the package, will generally

require a two-side plastic coated paperboard to ensure

that the package functions reliably all the way to the

consumer.

The packaging material must resist moisture and grease

at elevated temperatures without penetration into the

paperboard. The paperboard is given a heat-resistant

plastic coating, which must not affect the taste or odour

of the food.

Examples

Drinking cups

Ice cream

Frozen vegetables

Seafood

Baking using the pack-

ages as a baking mould

The extrusion coating



4

2

3

3

1

Extrusion coating and lamination machine

1. UnwindingThe paperboard is loaded into an unwinding position.

2. Surface treatmentThe paperboard surface is pre-treated with an electrical

corona discharge. The plastic fi lm can be treated with

ozone. These methods increase the adhesion of the

plastic to the paperboard.

3. Extrusion coatingPlastic granules such as polyethylene (PE), polypropylene

(PP) and polyethylene terephthalate (PET) are converted

by pressure and heat to the molten state in the barrel of the

extruder. The molten plastic passes through a narrow slit

in the automatically controlled die and onto the surface of

the paperboard. The control of temperature is critical. The

plastic surface is immediately pressed against the chilled

face of a steel roll, controls the fi nish of the plastic surface.

Reverse- side coatings have an NSO (Non-Set-Off) fi nish

and print-side coatings usually have a gloss fi nish.

Extrusion lamination machine

Moltenplastic

Moltenplastic

Coronatreatment

Coronatreatment

Coronatreatment

NSOChill-roll

Chill-roll

Reel up

Ozone

Ozone

Foil


4

3 5

2

6

4. Extrusion laminationAn unwind station is located immediately after the initial

plastic coating is applied. Foil or fi lm can be fed from this

position into the nip between the molten plastic fi lm and

the chill roll such that the plastic initially performs the

functions of an adhesive.

5. Corona treatmentPrint-side plastic coatings are subjected to corona

treatment to achieve good ink wetting. One-side plastic

coatings are also corona treated to improve the sealing

characteristics and permit gluing with emulsion adhesives.

6. Reel-upThe paperboard is wound onto large steel cores (drums)

in batches of between 1 and 3 tonnes depending on the

product. Each drum is given a unique in-house identifi ca-

tion code.




Extrusion and lamination materialsThe materials used for extrusion coating and extrusion

lamination are paperboard, paper, plastic resins, plastic

fi lms and aluminium foil.

There are many types of coating resins and many of

them have special features for specific end user appli-

cations. Film and foil suppliers produce both standard

interchangeable products as well as their own speciality

niche products. These can be combined with paperboard

to create a great variety of products.

Plastic coating resins are selected for very low taint and

odour properties so that the packed products will not be

affected.

European waste legislation stipulates that packaging

material should be easily separable to enable recycling

when possible. The plastic layer on extrusion coated

material is by nature difficult to separate from the board,

which makes it difficult to comply with these regula-

tions. Mono materials, which are made from one basic

raw material, are sometimes seen as better alternatives

than composites such as extrusion-coated paperboard.

Composites exist because they are efficient and reliable

in providing the required functions. Promoting mono

materials usually means sacrifi cing functional performance

and adopting packaging materials with signifi cantly lower

effi ciency.

However, if the amount of the plastic barrier is below a cer-

tain level (currently 5 % of the total weight) the packaging

material is regarded as a mono material from a tax point

of view. There are well-proven processes in use today

that can separate plastics and foils from the fi bres. These

fi bres can then be used for the production of recycled fi bre

products. To facilitate recycling and maintain the quality of

the recycled materials, it is always an advantage to sort at

the source.

Key properties required for extrusion coating and lamination:

• surface properties such as structure, smoothness,

strength and profi le

• surface strength properties such as z- and tearing

strength and stiffness

• hydroscopic properties such as moisture, fl atness and

dimensional stability

• fl atness and dimensional stability

• cleanliness of edges and surface

• polymer adhesion

• odour/taint neutrality.

Key properties for glue lamination:

in addition to the above

• surface water absorption

• gluability.

Raw material

Polyethylene (PE)

Polypropylene (PP)

Polyethylene terephthalate

(PET)

Aluminium foil

Metallised PET fi lm

Additional properties

Good moisture barrier and sealability.

Good grease and moisture barrier. Resists high tempera-

tures and is sealable.

Very good grease resistance at elevated temperatures.

The amorphous coating is heat sealable and heat resistant.

Good fl avour barrier and smooth surface with high gloss.

Very high gloss and good printing characteristics. Good

fl avour barrier.

Applications

Frozen food, ice cream,

cups and confectionery.

Ready-made food for

reheating in the package.

Trays for reheating and for

baking.

Luxury products and

chocolates.

Gifts, wines and confec-

tionery.



Additional coating propertiesThe strength characteristics of the paperboard are slightly

changed after extrusion coating and lamination. Plastic

coating with low density PE does not alter the stiffness but

PP or PET coatings will increase the stiffness considerably.

The toughness of the resin gives increased tear strength to

plastic-coated paperboard.

Plastic adhesionPlastic adhesion is a dimensionless property defi ning the

relationship between the adhesive and cohesive strength

of the paperboard surface. The bonding should ideally be

higher than the internal bond of the paperboard in order to

create fi bre tear. See Test Method in the Gluing chapter.

Adequate adhesion is important for most converting

operations, such as printing and heat sealing.

For production control an internal method is used.

The plastic coating or fi lm is pulled off at specifi ed angles

and the degree of fi bre tear is determined. The ranking is:

6 = 100 % fi bre tear, 1 = no fi bre tear.

If the strength of the paperboard/pigment coating is

stronger than the bond between the paperboard and the

plastic coating, no fi bre tear is achieved (e.g. fully pigment-

coated paperboard). Then a different scale of evaluation is

applied and the ranking is: 6 = excellent adhesion, 1 = weak

adhesion. In these cases the adhesion can also be measured

as peel strength at a 125 ° angle. The result is expressed as

N/cm width.

The plastic adhesion is mainly governed by:

• surface properties of the baseboard

• pre-treatment of the baseboard (corona and ozone)

• heat content of the plastic melt when applied to the

paperboard.

Corona treatment is necessary when:

• The plastic surface is to be printed (to enable the ink to

wet the surface).

• Emulsion glue is to be used (to enable the glue to wet the

surface).

Corona treatment also improves heat sealability. Two-side

corona treatment is not available because such a material

would give severe blocking problems between the sheets.

The corona-treated plastic surface is extremely sensitive. Any

rubbing, touching by hand, etc. will destroy the treatment.

During production the corona level is mainly affected by

mechanical damage. The moisture content of the paper-

board can also infl uence the level. For two-side PE-coated

paperboard we strongly advise never to stack more than

two pallets high.

Pinholes Pinholes are microscopic holes that might appear in the

plastic film during the coating process. In most cases,

a limited number of pinholes is acceptable. The main

reasons for the appearance of pinholes are irregularities

in the base paperboard (too high surface roughness, loose

fi bres, etc.), an uneven coating profi le or too low a plastic

grammage.

Measurable properties Pinholes

Coloured denaturised alcohol is applied on the test

surface. After 5 minutes the remaining liquid is wiped

off. Pinholes are indicated from the reverse side as

green spots. The number of pinholes is expressed as

number/m².

DROP OF INK

DROP OF INK

UNTREATED PLASTIC SURFACE

TREATED PLASTIC SURFACE

PAPERBOARD

PAPERBOARD


Board Lamination

Board Lamination

The basic paperboard products are produced in a limited

range of thicknesses because of the need for effi ciency

in paperboard manufacture. However, this thickness and

stiffness range is extended considerably when two or

more layers of paperboard are glue laminated together

into equal-sided products with the same smooth and

white printing surface on both sides. The many raw materi-

als available provide numerous combinations so that many

customer needs may be met.

Laminated paperboard offers good rigidity and smooth-

ness which, when combined with excellent visual appeal,

makes the package look more attractive to the consumer

in the store.

Laminated paperboard is smooth and fl at with good

cohesion and adhesion. The combination of stiff ness and

converting possibilities makes it suitable for the packaging

of expensive and luxury products.

Packaging that will come in direct contact with foodstuffs

must be designed for each specifi c end use.

Evaluation of paperboard laminationMost of the evaluation is done off-line. The aim is to deter-

mine and document that:

• the glue covers the whole web

• the glue keeps the webs together after drying

• the sheets are fl at and free from twist

• the pallets are fl at

• there is no damage (e.g. indentations) to the surfaces

• there is no visible dust or loose particles that can disturb

the converting operation.

Glue lamination machine

7. UnwindingThe glue lamination machine has four unwind stands.

8. DryingIR (infra-red) driers are used to control the shape of the

sheets.

9. GluingWater-based adhesives are used to glue the board webs.

10. Press NipAfter gluing, the webs are pressed together.

11. Sheeting and StackingThe glued board is sheeted and stacked on pallets in line.

7

9

11

8

10


Board Lamination

Evaluation of extrusion coating and laminationThis process lends itself to control and continuous moni-

toring of the coat weight, coating profi le, thickness and

moisture profi les during production.

The following properties are measured off-line:

• adhesion

• surface smoothness (printing side, reverse side)

• surface tension (treated side)

• pinholes

• fl atness of the sheet

• heat sealability (where applicable)

• odour and taint neutrality

• surface defects

• blistering (where applicable).

Conversion operations in practiceSlightly different settings and techniques are necessary

with extrusion-coated and laminated products in printing,

die-cutting, creasing, gluing, and sealing. They are well

established and do not cause problems in practice.

Low odour printing inks and the programmed airing of

pallets are important to prevent the absorption of taint into

the plastic coating. Always use well-proven procedures

as prescribed by the printing ink supplier. Uniform coat

weight is important for successful conversion.

When paperboard is glue laminated together to give a

thicker and stiffer product, the following changes should

be considered:

Conversion operation

Printing

Die-cutting and creasing

Gluing

Packing

Considerations for extrusion coated and laminated products

Printing on a plastic-coated surface requires corona treatment of the plastic to make it

wettable. In addition, the basically non-absorbent nature of the surface requires the use

of printing inks that do not require absorbency. Such inks are available and they can

also be used on pigment coated surfaces.

Plastic-coated or laminated products with an extra tough layer like PET should prefer-

ably be die-cut from the plastic-coated side. In general, plastic surface layers improve

creasability because they have very good elongation before breaking and tend to

reduce the risk of surface cracking in the creases compared with plain paperboard.

Corona treatment improves the sealing characteristics and permits the gluing of one-

side PE-coated paperboard with emulsion adhesives.

The friction between the blanks should be considered, especially when they are made

with a glossy PE on the outside. The glossy corona-treated surfaces may tend to stick

together if not protected with printing ink or varnish plus spray powder.

Such sticking or blocking tendencies may also appear in some packing lines if the un-

printed glossy PE has to slide past polished steel guides. The remedy is to use varnish

and spray powder on the exposed areas of the paperboard.

Conversion operation

Printing

Die-cutting and creasing

Gluing

Considerations for glue laminated products

Stiffness may make fl atbed printing necessary. Two-side pigment coating means that

the reverse side is as smooth as the printing side. This can cause printing ink set-off.

Creasing must be carefully evaluated; the thicker products will need double creasing or

scoring. Die-cutting and creasing will require higher pressure; this may affect the wear

of the dies.

Gluing is done pigment coating to pigment coating. This procedure will be slightly differ-

ent compared to gluing the printing side to the normal reverse side. The higher stiffness

and different creases will give much higher spring-back force, so glue seams must be

well developed before pressure is released.


Design and carton construction


How is paperboard used and how can you get the most

out of it as a material? Whether you are using the paper-

board for a book or brochure cover or for a packaging it is

important to have a detailed knowledge of how it should

be handled and what demands will be made on it from the

various players involved in the chain between manufac-

turer and consumer or sender and recipient. Matching the

requirements for an appealing design with the require-

ments for cost-effective production, simple logistics and

good functioning in a retail environment is not an easy

task. In the following chapters we have chosen to focus

on functional requirements, mainly in the packaging chain,

before we go on to describe paperboard properties that

affect your choice of the most appropriate material.

The appearance of a package or graphical product is

decided during the design process. Paperboard is a ver-

satile material which provides an almost endless number

of possibilities. This means that when designing shapes

the only limitation is your own imagination. The design

comprises both the surface appearance and the shape

or structural design, and these two aspects of design are

discussed separately.

Brand owners and designers need to have a good un-

derstanding of the different stakeholders and their respec-

tive needs in order to make the most of the packaging and

its potential.

Examples of infl uencing factors• the brand itself

• the core product

• printer/converter

• packer/fi ller

• distributor

• retailer

• consumer

• legislation

• non-governmental organisations such as environmental

organisations.

Surface designThe surface design of a packaging or graphical product

based on paperboard comprises the effect of its print

presentation with the possible additional use of varnish-

ing, embossing, hot foil stamping, extrusion coating or

lamination.

The end user must defi ne and describe the surface

design needs of the packaging or graphical product. This

usually relates to the promotional and information needs

concerning the product and its use.

The designer has to prepare suggestions to meet the

surface design needs described by the end user. This may

have consequences concerning the choice of conversion

process, which in turn affects the choice of paperboard.

The converter has to reproduce the ordered quality in

such a way that it conforms with the agreed surface design

using the specifi ed paperboard.

The best basis for achieving the desired visual impact

is by using paperboard based on primary fi bres with uni-

formly white-coated surfaces with a high smoothness and

a good print reproduction.

When discussing surface design we usually mean the

exterior or print side of the product. Aspects of surface de-

sign, depending on the product and its use, may also ap-

ply to the reverse side or inside surface. The inside surface

may be printed, as with chocolate and cosmetics cartons,

or it may be important to convey a hygienic image, as with

food and pharmaceutical packaging.

Examples of surface designFeatures which can be used in surface design are de-

scribed below. Often a combination of techniques

is used.

Text and pictures bring the product’s message to the

customer. The shape and colour create an image for the

product. High whiteness together with smoothness give

good print reproduction.

Key paperboard propertiesThe decisive paperboard properties for achieving good

design are:

• printability

• whiteness

• surface smoothness

• ink absorption and drying

• rub resistance

• lightfastness

• strength and elasticity.



Text, colour and images

Printing

Metallic appearance

Glossy or matt appea-

rance

Relief

Description

Text and pictures bring the product’s message to the

customer. The shape and colour create an image for the

product. High whiteness together with smoothness gives

good print reproduction.

A metallic appearance is effective in giving the product a

luxury image.

A way to attract attention is to create a contrast between

glossy and matt areas of the design.

An overall effect such as a linen fi nish or high relief of

specifi c parts of the design will give the product an

exclusive image.

Achieved by

• choice of paperboard

• print method

• post print fi nishing


• aluminium foil lamination

• metallised polyester fi lm

lamination

• metallic ink printing

• hot foil stamping

• cold foil transfer

• effect varnishes


• varnishing

• gloss PE extrusion

coating

• fi lm lamination


• embossing & debossing

• effect varnishes



Structural designPaperboard is widely used for graphics and packaging

applications where its versatile cutting, creasing, folding,

locking and gluing properties, together with its strength,

make it suitable for a wide range of functional and creative

structural designs.

Both creative shape and functional shape are important

aspects of the structural design. Packaging applications

have to meet functional needs, such as protection during

distribution and storage, and ease of handling and display

at the point of sale, as well as fulfi lling the consumer’s de-

mands. Creative design is used for promotional purposes.

The graphics designer has the freedom to use a wide

range of shapes.

Critical aspects of structural design differ depending

on both the conversion and packing processes and also

the ultimate end use. To a converter these are the quali-

ties of stiffness, creasability and fl exibility and the ease

with which paperboard can pass through the conversion

process.

An end user only sees the fi nal carton shape. The critical

aspects are good presentation, effective protection and

durability, when prolonged or extended use is required.

From a sales or promotional point of view the visual appeal

is vital. Structural design provides creative ideas for pro-

moting new products but perhaps the main responsibility

is to provide a functional shape which in the majority of

cases is based on accepted or specifi ed carton shapes.

Popular carton shapesThe potential of paperboard to provide an almost end-

less range of carton shapes is considerable. Some of the

more popular shapes are described in the following table

together with the specifi c requirements these place on

conversion and end use.

Type of carton shape

Simple rectangular or

square carton shape

Hinge lid carton

Simple rectangular or

square carton shape

Description

The rectangular or square cross-section with a large or

main display panel is the most widely used carton shape.

It is based on a simply cut and creased square or rectan-

gular sheet, or blank, of paperboard. The carton is side

seamed, leaving ends which are closed after the product

is loaded.

The product, method of fi lling and the way the pack will

be stored and displayed will have a major infl uence on

the dimensions. The ratio of the sides of the main panel is

usually between 5:3 and 5:4 as these dimensions display

well. This may not be possible if the product is an object or

objects with differing dimensions. The rectangular shape

also makes effi cient use of space in storage, distribution

and merchandising. Shelf stability of the pack will also be

taken into account in defi ning panel dimensions as well as

the facings expected to be made available for display with

products sold through supermarkets.

The dimensions of the unit package also infl uence the

dimensions of the transit outer (secondary packaging) and

the pallet plan. It is worth considering the latter at an early

stage as a difference of a few millimetres in one or two

dimensions can signifi cantly affect distribution costs.

This style of carton is widely used for cigarettes. It includes

a U-card inner frame, which assists the packing of the

product, is part of the unique fl ip-top closure and increases

the compression strength. Security and additional pack

protection is achieved by the use of an overwrapped heat-

sealed clear fi lm.




Flanged and double-

walled carton

Trays

Top load tray erected

cartons

Cartons with windows

and plastic panels

Display outers

Description

These designs give added strength and rigidity. A popular

use is for assortments of chocolate confectionery. They

may have double-walled hinged lids or separate lids and

bases.

Two popular applications are available:

1. Thermo-formed trays made from extrusion-coated

paperboard enabling lids to be applied by heat sealing.

These trays may be slightly tapered. With a heat-resistant

plastic extrusion coating, e.g. PET, these trays are used

for heating chilled and frozen foods in microwave and

conventional ovens. These trays can also be used to

cook bakery products.

2. Shallow trays (25–38 mm deep) with glued or locked

corners to hold groups of cartons or other types of pack-

ages for stretch and shrink wrapping.

These cartons comprise a tray erected carton (glued or

locked corners) with a hinged top flap. The product is

loaded from above, i.e. top load. There are two main types

of closure:

1. The top fl ap has an extended tuck in fl ap feature which

tucks in and can lock into the front panel of the tray. This

type of pack is usually fi lm overwrapped for product pro-

tection and security.

2. The top flap is extended on three edges which fold

down over the outside of three of the sides of the tray

and are sealed by hot melt adhesive. Alternatively, if the

paperboard is PE coated on one or two sides the closure

can be made by heat sealing.

These cartons can be used to show the product inside the

carton. The windows can simply replace cut-outs of the

paperboard in one panel or form part of patented, more

sophisticated systems in which the clear plastic incorpo-

rates creases and replaces paperboard on two or more

sides of the carton.

These cartons may have crash lock or lock end bases and

specially designed top fl aps. The cartons hold a number

of unit packages which are sold individually from the outer

in a point of sale display. The top fl ap and, optionally, addi-

tional portions of the side panels are creased and perfo-

rated so that they can be opened and partly tucked down

behind the product and the back panel, thereby attracting

attention to and promoting sale of the product.

Flanged and double

walled cartons

Trays

1

2

Top load tray

erected cartons

1

2

Display

outers

and plastic panels




Lined cartons

Cartons with internal

display fi tments

Sleeves

Sleeves with inner

sliding components

Other shapes of paper-

board packaging

Description

In this style a fl exible material (paper/PE, paper/foil/PE,

etc.) is either positioned inside a side seam glued carton

blank by the cartonmaker, or is applied on the packag-

ing line. The base of the barrier material is then sealed

or folded on the packaging line, the base of the carton

sealed, product fi lled, pouch sealed or folded and fi nally

the top carton fl aps sealed or tuck-in closed. Associated

with this type of design are cartons incorporating plastic

ends, tamper-proof, and product protecting diaphragms.

These cartons can be used to protect sensitive products,

they can be gas fl ushed or vacuumised, e.g. for coffee,

and they can be liquid tight or provide protection against

the ingress of moisture vapour.

These have paperboard fi tments inside the carton which

support and display the contents. The carton may have a

top opening hinged or separate lid or it may be a windowed

carton of the types already described. The fitments may

be integral parts of the carton blank or separate structures

added during the packaging operation. Another type of fit-

ment is a divider. These can also be either an integral part

of the carton blank or a separate fi tment.

Paperboard sleeves can be wrapped tightly around other

items, e.g. a ready prepared meal in a lidded tray, “six pack”

for plastic pots or other containers, or pre-wrapped prod-

ucts such as cheese. The sleeves are sealed by either

locking tabs or adhesive.

Typical examples are:

1. matchbox

2. hull and slide cigarette carton.

Typical examples are:

1. triangular shape, e.g. chocolate confectionery

2. hexagonal shape, e.g. chocolate confectionery

3. wallet style, e.g. hosiery

4. tubes, e.g. tubes with paperboard or plastic ends for

products such as confectionery and cosmetics.

Other packages with a high degree of ingenuity in design.

They display the product and often use additional paper-

board fi tments to support the product. Other additional

confectionery products are often incorporated in the

packages. These are usually, but not exclusively, associ-

ated with confectionery and toy packaging where they

have a play value after use. In other product areas they are

associated with gift packing.

is

the carton

Cartons with internal

display fitments

Sleeves

sliding components

Other shapes of

paperboard packaging

1

2

3

4




Cartons for

hanging

Cartons with

curved panels

Blister and skin

packaging

Tubs

Composite

packages

Plastic-coated

barrier cartons

Media

Description

This feature can be incorporated by extending the back

panel of a rectangular fi tment display shaped carton, fold-

ing the panel over and tucking it inside the carton. A hole

may be punched through two thicknesses of paperboard

which may be reinforced with a plastic clip for merchandising.

Interesting shapes can be created with curved creases

or straight creases meeting other creases at other angles

than 90 °. Typical examples are:

1. curved panels

2. round corners.

A printed card, often printed on both sides, is used to

support the product by either enclosing the product in a

plastic tray, the fl anges of which are then heat sealed to

the card or, alternatively, by folding extended panels of

the plastic over the edges of the card or by draping clear

plastic over the product and sealing to the whole area of

the card.

For example ice cream tubs. Tubs of this type may also

have circular paperboard lids.

Granular powder products e.g. retortable packages.

Plastic and foil containing laminates with paperboard.

1. For example milk, fruit juice. Two-side PE coated paper-

board and other plastic foil laminations on paperboard.

2. Cartons with PE on both sides can have heat-sealed

side and end seals which are liquid tight and can give

moisture vapour protection to the contents. These cartons

can also have PE on the reverse only, in which case they

may be sealed with a fl exible diaphragm material having

PE on one side to seal across the end closure.

There are different solutions for covers entirely out of

paperboard. They can have sliding components, a perfo-

rated or die-cut slit or folds that hold the discs.

artons for hanging

ment display

Cartons with

curved panels

12

and skin

ging

Tubs

CD



ClosureThe type of closure, opening feature and, where required,

reclosure feature can be chosen from a number of design

options. These features provide security and protection of

the contents during storage, distribution and at the point

of sale and, subsequently, convenience for the consumer.

Types of closure

Glued or sealed end

Tuck end

Lock end

Crash lock

Description

The style shown has full-depth overlapping outer fl aps

with the inner fl aps meeting. This gives a leak-proof style

for powdered or granular products in direct contact with

the paperboard. The inner fl aps never exceed the depth

of the outer fl aps as this would lead to an uneconomical

use of paperboard. The outer fl aps may be shorter than

the depth of the carton, in which case they are known as

economy fl aps. The most common type of adhesive used

is hot melt, although emulsion adhesives are also used.

The position and pattern of the adhesive applied can be

varied to suit the needs of security, opening and reclosure.

Alternatively, if the paperboard is extrusion coated with

PE (or other thermoplastic material) on one or both sides,

secure closures can be achieved by heat sealing, usually

with hot air or direct gas fl ame.

The top fl ap has an extended crease-hinged section which

is folded through 90 ° and simply tucked down into the

carton. With tuck-in fl aps at each end there is a choice of

whether they tuck in on the same side or on the oppo-

site side. Small cuts at each end of the hinged tuck flap

crease give greater security against accidental opening.

For greater security and product protection a heat-sealed

transparent overwrapping fi lm can be used.

An alternative is to overlap a self-adhesive label across

the 90 ° angle between the end and main panel, i.e. over

the tuck-in entry position. It is also possible to position

adhesive between the underside of the tuck-in panel and

the inner fl aps. The tuck-in cannot then be opened without

rupturing this glued area.

1. Used as the base of a carton with a simple tuck-in fl ap

at the top.

2. The carton has extra cuts in each side panel fl ap for

extra security. For greater security and product protection

a heat sealed transparent overwrapping fi lm can be used.

The cartonmaker pre-glues this style, which is quickly

hand erected by the packer. It is usually used as the base

of a carton and can support a considerable weight.

Lock end

1 2

Crash lock

d or sealed, end



Opening and reclosing featuresThe tuck-end carton clearly has an effi cient method of

opening and reclosure once the overwrapping fi lm or other

method of security is broken. There are several

opening designs for glued-end cartons – some of which

incorporate reclosure features.

Types of opening

Tear strip

Perforation

Pull tab

Perforated press

opening

Glue lines

Perforated panel

Concora

Description

If the overlapping fl ap is full or nearly full depth, a tear strip

with a lead-in tab comprising two intermittent lines of cuts

can be incorporated across the full width of the panel

between the glue line and the flap crease. This design is

not normally used for reclosure, though it can be to meet

special needs.

Both overlapping flaps can be perforated in the same

positions in two parallel lines so that by means of a lead-in

tab both thicknesses of paperboard can be removed. This

method of opening is not suitable for reclosure.

The edge of the outer overlapping fl ap incorporates a tab

to facilitate pulling and tearing – not suitable for reclosure.

A push-in area is perforated in the top of the face panel,

with the perforations extending and widening into the end

panels, so that a clean tear-open is achieved, providing a

partial reclosure.

Normally, the glue line is continuous across the full width

of the end fl ap. If, however, the glue line is not applied in

the middle area, a fi nger can be carefully slid under the

fl ap so that by breaking the glued area to the right and left

it is possible to open the carton. Reclosure is achieved by

inserting a tab in the outer fl ap into a cut in the under fl ap.

A variation of this form of opening is to replace the line of

adhesive with a row of dots of adhesive which more readily

break open. Another alternative allows the use of a con-

tinuous line of adhesive. In this case the underlapping fl ap

is printed and varnished, leaving small areas without print

and varnish such that good adhesion is only achieved over

these areas. The perimeter of these areas can be scored

so that tearing is limited to the areas of good adhesion.

A perforated area in one of the main panels of the carton

can be removed allowing access to the product, e.g. facial

tissues.

Through a scoring (half-cut) on both sides (printed side +

reverse side) of the carton, tear tabs can be worked out,

guaranteeing a fail-safe opening of the packaging without

the assistance of a plastic strip.

The appearance of the sales packaging on the shelf will

not be negatively affected by this scoring.

p

PAPERBOARD

Tear strip Hot-melt adhesiveon underside

Interrupted glue line

Glue lines



Conversion, packaging, and graphics fi nishingThe following operations are used by converters, pack-

ers, and graphic fi nishers to make creative and functional

shapes.

Creasing makes the paperboard fold accurately along

well-defi ned lines.

Die-cutting produces a blank for further conversion. It is

usually performed at the same time as creasing. Perfora-

tions can be used to facilitate opening. Tabs and slits can

be cut in separate panels. When tabs are inserted into the

slits a self-locking permanent structure is created.

Folding is usually performed to 90 ° or 180 ° angles.

Gluing means applying glue on a side fl ap, pressing it to

a carton panel and maintaining the pressure until the glue

seam has set. The paperboard is converted to a perma-

nent shape.

Heat sealing, heat and pressure can be used to seal

plastic coated surfaces or surfaces to which a pattern of

hot melt adhesive has been applied in an earlier operation.

Key paperboard characteristics Stiffness is probably the most important property related

to packaging structural design. As we have seen, this

property is closely related to other strength related fea-

tures, such as fi bre composition, particularly in the outer

layers, and thickness.

Important considerations for carton panels are stiffness,

panel dimensions, paperboard grade and fi bre orientation.

Paperboard stiffness is anisotropic with respect to the

machine direction (MD) and cross direction (CD).

Box compression strength is closely related to structural

design requirements.

When packed cartons are stored or transported they are

often stacked in such a way that the boxes are subjected

to compression loading. In practice the strength require-

ment of the fi lled carton is dependent upon:

• Package design, i.e. shape and general strength due to

the structure.

• Whether the contents support the package or not.

• Design and strength of transit package (the outer, etc.)

• Storage and distribution method – palletisation, stacking

and climatic conditions.

• Conversion route – presence of barrier materials may be

relevant in some methods of distribution.

Carton design must take into account the stresses

that are likely to be exerted on creases during the pack-

ing process and also during end use. To this end, creases

must be well formed to avoid premature failure under com-

pression, and must also provide a crease stiffness that is

suitable for the packaging operation. Folded creases and

adjacent panel size must not exert unnecessary stresses

during the gluing operation and subsequent handling and

storage.

Key paperboard properties The following paperboard properties are important for

achieving good structural design:

• stiffness

• tensile strength

• compression strength

• box compression strength

• tear strength

• creasability and foldability

• elasticity

• density

• plybond

• lamination strength (for plastic coatings and laminates).


Consumer use and appeal

Consumer use and appeal

The efforts of the manufacturers of paperboard, printers,

converters, manufacturers and packers of goods, distribu-

tors, and retailers must ultimately ensure consumer appeal

and satisfaction with cost-effective, effi cient packaging

that has a sound environmental background.

What are consumer needs? All consumers look for

“value for money” and “fi tness for purpose” and require a

clear demonstration of brand values and access to prod-

uct information. The information, form and functions need

to be adapted to demographic groups or individuals with

special needs.

From a consumer’s point of view, the key requirements of

packaging are to promote or provide:

• product declaration

• handling instructions

• brand recognition

• product protection

• oxygen-, light- and moisture barriers

• convenience

• safety in use

• recyclability

• economic use of resources and accurate representation

– not excessive nor deceptive

• a responsible attitude to the environment

• “intelligent” packages

• and to separate and fi x the contents.

Consumers expect packaging to be functional, easy to

handle and safe to use. They require packaging to give

“easy recognition of product”, be “easy to locate” in the

store and refl ect the perceived value. Instructions for use

and disposal must be clear and distinct. These are all ap-

pearance features relating to the material, shape, decora-

tion, and printed matter.

Packages should be tamper evident, especially for food,

gift packages, and products for personal use. Adhesive

joints and opening devices must remain secure. Packages

must not appear damaged or faded on the shelf, this being

equated with old or badly handled stock. Packages which

attract condensation after purchase, i.e. frozen and chilled

food and ice cream, should have good moisture resistance.

With multi-portion packaging the consumer requires

packages which are easy to open, close and reclose,

and ultimately empty the package entirely. A perforated

opening should be easy to tear, whilst a hinged tuck-in fl ap

must not tear after repeated opening and reclosing during

the life of the package.

Packaging should not deteriorate in use or storage, and

proximity to other products should not be allowed to affect

the fl avour or aroma of the product.

An element of “convenience” is necessary depending on

the product and the method of use. This can be achieved

in a number of ways through the material and package

design, depending on the nature and use of the product.

Key paperboard characteristicsAs with retailing, the decisive characteristics are depend-

ent on the type of product under consideration.

The consumer expects packaging to be effi cient and

functional and to meet needs in terms of the appearance

and performance requirements of specifi c products. The

properties of appearance and performance do interact;

thus, for example, a poor appearance usually leads to

a poor performance. Key characteristics as regards

consumer appeal primarily concern the cost effectiveness

of paperboard packaging and its sound environmental

background.


Distribution and storage


Distribution and storage comprise those activities occur-

ring between the point at which the product is packed and

its ultimate point of sale in the retail store, supermarket,

vending machine, pharmacy, etc.

At the end of the packing line the packages are collated

by hand or by machine in groups of 6, 12, 24, etc. for

packing in a transit package. This may comprise:

• A shallow-depth paperboard tray which is subsequently

stretch or shrink wrapped in fi lm.

• An open-ended corrugated fi breboard sleeve which is

subsequently stretch or shrink wrapped in fi lm.

• A corrugated case with glued or taped closure. There is

also a shelf-ready corrugated case which has a crocodile-

type opening and is designed to go directly on the super-

market shelf.

• A unit of 6/12/etc. packs simply shrink wrapped in fi lm

with no additional paperboard protection.

These transit packages are usually palletised, alternate

layers being packed in a different pattern or plan to give

stability to the load. The pallet load may be further stabi-

lised with strapping or stretch fi lm.

Standard retail pallets are reusable with a common size

being 1000×1200 mm.

Pallet loads are stored in warehouses which may or may

not be heated. Frozen and chilled foods are stored in ap-

propriate conditions, i.e. –20 °C to –35 °C for frozen prod-

ucts and 0 to +3 °C for chilled products. Storage is usually

freestanding, limited to two pallets high, or in racking.

It is unusual for full pallet loads to be delivered directly

from the manufacturer to the retail store except in the case

of very large stores. Pallet loads are usually distributed to:

• Distribution warehouses of major retail organisations.

These are strategically placed to meet the stocking

requirements of a number of the company’s stores in a

given area. Mixed loads are “picked” or made up to meet

the needs of the respective stores. This means that mixed

numbers of transit packages of different products are

placed in special cages, often in a somewhat random ar-

rangement.

• Distribution warehouses of companies which are inde-

pendent of both the manufacturer and the retail stores.

The procedure for distribution is the same as that de-

scribed previously.

• Distribution warehouses of independent cash and carry

companies. These companies display pallet loads of

goods in bays or racking allowing small retailers to pick the

goods for themselves. This type of distribution has led to a

more attractive cash and carry transit package, e.g. shrink

wrapped to allow the more attractively printed individual

cartons to be seen, or by the use of pre-printed white lin-

ers for corrugated cases.

Key paperboard characteristicsThe main requirement of both the individual carton or

other forms of packaging is for stacking, handling, and

transit protection. Stacking requires vertical compression

strength. That may be assessed under static or dynamic

loading on a pallet, a transit package or an individual pack-

age. Handling of transit packages requires strength to

resist impact and uneven compression in mixed loads.

Transport hazards usually refer to impact and can be

checked on sliding planes or by drop testing. Some sensi-

tive products may need special cushioning protection and

the needs can be assessed on variable frequency vibration

tables and by the use of special records in practical transit

tests. Vibration can cause damage to the package by

scuffi ng or rubbing adjacent surfaces.

These requirements may also have to be met in frozen

(–20 °C to –35 °C), chilled (0 to +3 °C), very damp or wet

conditions, or very hot and dry conditions.

Key propertiesIn general the strength-related properties are:

• grammage

• thickness

• moisture content

• stiffness

• compression strength (short span)

• box compression strength

• water resistance (frozen and chilled food distribution).

Distribution and storage in practiceThe following factors are essential to good distribution and

storage:

• The strength of paperboard

• The structural design of the unit package

• The nature of the product, i.e. if it contributes to the

strength of the package

• The strength and structural design of the transit package

• The pallet plan. The dimensions of the unit transit

package can now be examined by computer to give the

optimum utilisation of the pallet volume. This also leads

to the best stacking performance as a result of close and

interlocked packing on the pallet.

Some additional comments are, however, necessary for

particular conditions of storage and distribution, see the

following page.



Distribution and storage conditions

Frozen food and ice cream

Chilled food

Very damp or wet conditions

Very hot conditions

Descriptions and actions

The storage temperature will be around –20 °C. The printed or varnished

print must not craze at this temperature.

The storage temperature is 0 to +3 °C and the main hazard is the very high

relative humidity which raises the moisture content of the paperboard with

a consequent loss of stiffness and strength. There are a number of ways of

reducing this effect such as by using a tight sleeve where the product is in a

plastic or aluminium foil tray, or by packing the product directly into a plastic

coated paperboard tray with a printed heat sealed plastic coated paper-

board lid. The paperboard can be made more resistant to moisture by:

• Hard sizing all layers of the paperboard, thereby improving its edgewise

wicking tendency.

• Functional coating with plastic, aluminium foil, wax or moisture resistance

varnish.

The paperboard can be given enhanced moisture resistance as discussed

under “Chilled food”. These conditions also demand a coating on the paper-

board and a choice of compatible inks and varnish with good keying, wet

rub, and scuff resistant properties.

Here the main problem to arise is blocking, i.e. the sticking together of

sheets or packages. It is avoided by the choice of a suitable paperboard

coating and compatible non-blocking inks and varnish.

SummaryAppearance needs are provided by surface and structural

design. Performance needs relate to printing, conversion

and use. This may involve special protection or functional

requirements relating to the paperboard product or to any

other products with which it may be in contact, or to the

handling, storage and use of the product.

Design in the broadest sense highlights every need which

must be incorporated into the choice of paperboard for every

graphical or packaging product.


Edge water absorption, Wick testIn many wet applications such as deep-freeze packaging,

or for drinking cups, a higher degree of water resistance

is needed. Examples of the most demanding applications

might be the packaging of hot spinach, or cups for tea

or coffee. Even if the inside of the package or the cup is

plastic coated, the edges normally remain exposed. The

Wick test is the method commonly used to evaluate water

absorption via the paperboard edges.

The mechanism involves capillary attraction, which is

reduced when the paperboard has been treated with a

sizing agent. As only the paperboard edges are involved in

this test, the internal sizing of the paperboard and also the

type of fi bre in use are of major importance.

The test sample is covered on both surfaces with a

waterproof tape and cut to a specifi c size. The sample is

then weighed before being placed in water at 80 °C, so

that water can only be absorbed through the edges. After

20 minutes the sample is weighed again and the increase

in weight recorded as the Wick test value in kg/m². This

wicking test is used for testing of Solid Bleached Board

products.

Surface water absorption, Cobb testThe Cobb value quantifi es the amount of water absorbed

via the paperboard surface during the Cobb test.

In the offset litho printing process, where water is used,

there is a need for some degree of water holdout. For

packaging applications for deep freeze/ chilled foods the

requirements can be demanding.

The paperboard sample is weighed and a cylinder with

a cross sectional area of 1 dm² is placed on the sample.

Water (100 ml) is poured into the cylinder. After 1 minute

the cylinder is emptied and excess water blotted from the

surface. The weight increase is registered as the one-

minute Cobb value in g/m².

The test can be used for the outer surfaces as well as

the internal layers of a multi-ply paperboard. The centre

plies are tested after delamination of the outer plies.

Hard-sized Folding Box Board products, where the

middle plies are additionally treated to give high water

resistance for deep-freeze and chilled food applications,

are tested using an extended time. The commonly speci-

fi ed time is 3 minutes, with the test also performed on the

middle plies, in addition to the outer plies.

On pigment coated surfaces water absorption is to a

large extent dependant on the coating composition. For

uncoated surfaces internal sizing and composition of the

surface size are important.

The internal sizing of fi bres is of vital importance in slow-

ing down the water absorption of the centre plies.


Covered surface

Open edge


Retailing

Retailing

Retailing comprises the activities involved in offering

goods for sale to the general public.

In most cases the consumer can inspect the product

and choose at the point of sale, stores and supermarkets.

Retailers often market their own private brands alongside

other producers’ branded products. They are therefore

involved in all the aspects of package specifi cation, includ-

ing the choice of paperboard.

In case of mail order, internet sales, vending machines

and the issuing of prescription medicines in pharmacies,

the customer does not handle the goods prior to pur-

chase. Packaging protection and information are vital to

meet functional needs and emotional satisfaction (post-

purchase satisfaction). The package is the last part of the

brand communication chain, as it is often kept for storage,

e.g. CDs and perfume bottles.

The retailing requirements of a package are listed below:

• Brand appeal.

• Transit packages for packaged and graphical products

must arrive in good condition, thereby ensuring that the

contents are also in good condition.

• The transit packages should be convenient for transpor-

tation, handling, opening, and recycling.

• Unit packages should be convenient for stacking and

display. They should be shelf-stable and make optimum

use of the space available.

• Unit packages should have structural and graphical

designs which promote the product. The graphics should

be appealing, distinctive and informative.

• Unit packaging should provide appropriate protection for

the product to prevent damage and maintain the quality of

the contents.

• Unit packages should conveniently conform to the needs

of the retailer in respect of store handling,

e.g. bar codes, ability to apply labels, provide tamper

evidence, safety in handling and in packing at check-outs.

Equally, the requirement to complete the sale safely and

conveniently applies to mail order, internet sales, vending,

and prescription dispensing.

• Primary and/or secondary (display trays) packaging

needs to conform to the retailers’ shelf space standards

and to their standard transit packaging sizes.

Key paperboard characteristicsThese characteristics will vary depending on the type of

product being considered. Guidance is given for major end

uses at www.iggesund.comwww.iggesund.com.

In general the paperboard characteristics necessary will

be those providing promotional and protective features.

These features may vary from surface and structural

appearance to box compression strength and taste and

odour neutrality.

Key propertiesKey paperboard features for the retailing process:

• Print reproduction (whiteness, gloss, smoothness)

• Product protection (stiffness, compression strength,

tearing resistance, water absorption, taste and odour

neutrality)

• Designability (Good creasing, embossing and folding

characteristics, gluability)

• Wide grammage and thickness range enables a well-

adapted choice, depending on protection and perform-

ance need.

There is also an important environmental dimension for

the manufacturer and retailer to consider which is con-

sumer driven. Certifi cation schemes, such as PEFC and

FSC, have been introduced to ensure a sustainable chain

of custody from the forest to the consumer. Details regard-

ing certifi cations are available on www.iggesund.comwww.iggesund.com.


Taint and odour neutrality


One purpose of a package is to protect its contents from

damage. For many products, such protection also in-

cludes preservation of the product’s fl avour. The package

itself must not contribute to any unacceptable alterations

by releasing or absorbing odorous substances which

could affect susceptible products such as cigarettes

and chocolate.

Odour from paperboard can arise from a number of

sources such as wood resins from mechanical pulp or

residual chemicals from chemical pulp. During the produc-

tion of the paperboard, biological activity may produce

odorous substances. Furthermore, the coating contains

synthetic binders, and there is a risk that these impart an

odour to the paperboard.

Mechanical and chemical pulps are selected to mini-

mise odour and steps are taken within the mill to eliminate

biological activity in the machine systems. The paperboard

is tested on a regular basis to ensure that the risk of taint-

ing of food is minimised. In addition, coating materials are

subject to stringent specification and control to reduce

tainting risks.

Experience has, however, shown that by far the greatest

risk of tainting of sensitive products by cartons comes

from the printing ink or varnish residues remaining in the

paperboard after printing. Ink solvents and vehicles are

often absorbed into the paperboard and may be absorbed

by the fibres only to be released later. Paperboard may

also absorb odorants during storage, and care should be

taken to store the paperboard in an odour-free area prior

to printing.

Different printing methods can cause odour problems to

varying degrees. Classical offset ink, based on drying oils,

develops large amounts of volatile substances when dry-

ing. It is essential that the printed sheets are well dried and

well aired to prevent problems. Modern “odourless” offset

inks, which reduce these risks, are available.

UV curing of offset inks is sometimes used to obtain a

very high gloss. In case of insuffi cient or irregular curing

this printing technique can cause odour problems. Grav-

ure printing is often considered the safest method to avoid

odour problems provided the solvents are carefully chosen

and the drying is suffi cient.

To detect and measure volatile and possibly odorous

substances in paperboard or paperboard cartons, gas

chromatography is often used. Ideally, each volatile sub-

stance in the sample is represented by a peak in the chro-

matogram and the peak area indicates the concentration

of the substance.

The paperboard choice Paperboard that will be used for the packaging of sensitive

goods such as foodstuffs or tobacco should be tested to

ensure that it meets required taint and odour standards.

As mentioned earlier, the surface coating composition and

pulp are some possible sources of odorous substances in

the paperboard. Printing inks can also cause odours and

different printing methods show major differences in odour

contribution.

Both Folding Box Board (where mechanical and chemi-

cal pulps are used in combination) and Solid Bleached

Board (where only pure chemical pulp is used) consist of

primary fi bres, which means that their contents are known.

Chemical pulp offers the least contribution to taint and

odour.

Time: 16,997 MinutesTYPICAL CHROMOTOGRAMS: WLC, FBB and SBB


Characteristics of taint and odour neutrality A paperboard carton must be as free as possible of odor-

ous substances which could originate from:

• the pulp used in the paperboard

• the coating of the paperboard

• extrusion coating

• printing, lamination or other conversion steps.

Assessment of taint and odourAn optimised paperboard package will not interact with

its contents in such a way that their odour and fl avour are

changed. In order to be regarded as a good performer with

regard to taint and odour, a paperboard must therefore

have a very low concentration of odorous substances.

Different pulp and coating characteristicsBleached chemical pulp contains cellulose and only traces

of impurities. These are small amounts of fatty acids, resins

and other impurities which could create odour problems.

Fatty acids will oxidise in storage, if present, and develop

a “woody” or even rancid odour.

Mechanical pulp contains large amounts of lignin (wood

substance) and resins containing fatty acids. A paperboard

based on this type of pulp could contribute to taint and odour

risks, but these can be diminished with a proper manufac-

turing technique and screening.

Primary fi bres can be fairly well controlled but second-

ary fi bres are often of unknown origin and have undergone

various converting stages such as printing before being

reclaimed and reused. This means there is a considerable


Chromatogram of unprinted paperboard

Chromatogram of printed paperboard



risk of inconsistency in the amount of contamination and

impurities in the paperboard, leading to variations in the

board’s taint and odour characteristics. A paperboard

based on recycled fi bres is therefore not recommended

for the packaging of sensitive products.

Most high-class packaging boards have a pigment

coating to ensure good printability. The binders in the

coating are normally latices, which may contain various

organic substances as impurities. Some of these could

create odour problems and must be carefully controlled.

Key propertiesFor paperboard and cartons to be taint and odour neutral,

the following features play a crucial role:

• primary fi bre

• the coating ingredients

• the plastic coating

• the printing method used.

Measuring equipmentThe most sensitive instrument available to measure the

odour and/or flavour of a substance is a human being.

Only humans can describe an odour or a flavour. The

members of trained panels assign numerical ratings and

record their impression of tainting flavours or volatile

odours experienced. By using no fewer than eight asses-

sors, accurate and objective results may be achieved.

A number of sensory test methods are available. The

choice of test method is dependent on factors such as the

specific issue (e.g. type of products, type of questions)

and how quickly the results are needed.

Instrumental techniques are valuable complements to

the human assessments. Headspace sampling combined

with gas chromatography (GC) is used to measure chemi-

cal compounds that are released from the products. To

identify the compounds, this method is combined with

mass spectrometry (MS).

In headspace sampling, the volatile substances that

are released are collected in gas form. In GC the volatile

substances are separated through differences in boil-

ing points and absorption rates in the GC column. Their

concentrations are recorded with a detector, normally a

fl ame ionisation detector (FID). However, the instrument

cannot differentiate between odorous and non-odorous

substances. To solve this problem it is possible to split the

gas stream after the separation and lead one part to the

instrument. The other part is led to a person who sniffs the

gas stream and notes whether there is a noticeable odour.

Quality controlFor quality control two methods may be used. The fi rst

uses a panel which compares the outturn sample (either

fi nished product or raw material) with a reference. In the

second a gas chromatogram is run to detect any new

peaks indicating contamination or to note major changes

in the concentration of known odorous substances.

When evaluating a gas chromatogram it is important

to select compounds which are known as risk factors if

they occur above the detection threshold. These com-

pounds are of course different for different applications;

for instance, cigarettes and chocolate are susceptible to

different compounds.

Sampling and sample handlingTo achieve proper measurements attention must be paid

to the sample handling. Due to the sensitive nature of this

type of analysis some important issues are to avoid per-

fume and perfumed soap before handling the samples and

to use proper aluminium foil as protection for the samples.

Please consult the Laboratory for Sensory and Chemical

Analyses for advice.

Iggesund Paperboard’s Laboratory for Sensory and

Chemical Analyses is accredited (accreditation number

1740 ISO/IEC 17025) for the following analyses:

Type of test

Robinson EN1230-2

Odour EN1230-1

Difference testing Triangle

test (ISO 4120) Duo-trio

test (ISO 10399)

Methods

Intensity of taint resulting

from interaction material –

test medium.

Odour intensity of the

materials.

Pair-wise comparison

(mod. ISO 5495).

Type of information

Scores (0 – 4)

Scores (0 – 4)

The certainty of that there

is a difference.

Remark

The standard test medium

is ground chocolate but

other media can be chosen.

The materials are put into

glass flasks and subse-

quently the air of the glass

fl ask is smelled.

Two samples are compared.

Can be applied both to taint

and odour.


Gas chromatography principle


TAINT TEST

PROCEDURE

(LSCA)

Stored in jarroom temp, 2 days

Pieces equal to2 A4 sheets are cut into strips

VARNISH

PAPERBOARD

INK

FOOD SIMULANT (CHOCOLATE)placed in indirect contact with the sample Chocolate assessed

C 100%M 100%Y 100%B 100%

92

51

31

CARRIER GAS COMPUTER

COLUMN OVEN

COLUMN

INJECTOR

DETECTORSAMPLEA/D

CONVERTER

CHROMATOGRAMS


Migration into foodstuffs

Migration into foodstuffs

The maximum amounts of substances allowed to migrate

into packed foodstuffs are limited by regula tions that have

been sharpened in recent years. To ensure that our board

materials fulfi l the stipulated requirements, migration tests

are performed. These tests bring different types of food

simulants into contact with the board and then store them

for specific time periods at a specified temperature. The

type of test food and the choice of time and temperature

depend on the intended use of the packaging materials.

After this contact period, the amounts of substances

that have migrated into the food simulant may be weighted

(resulting in an estimate of total migration) or specifically

analysed (resulting in identifi cation and quantifi cation of

the substances).

The limits apply to packaging materials made of several

components. It is important to realise that while the board

is often the basis of the packaging, other components

such as printing inks and varnishes may contribute con-

siderably to the migration.

Specifi c methods may also be used to analyse amounts

of certain substances, such as optical bleaching agents,

that are not well quantified when applying the more gene-

ral migration tests.

MIGRATION TEST

PROCEDURE

(FABES)

Stored in migration cell

1 dm² is cut Migrants identified and quantified (GC)

VARNISH

PAPERBOARD

INK

FOOD SIMULANT (TENAX)placed on the sample

Migrants dissolvedin solvent

40°C10 days

C 100%M 100%Y 100%B 100%

MIGRATION TEST PROCEDURE (FABES), OBA:s

ETHANOL+WATER

1 g cut paperboard OBAs in extract quantified (UV-spectrum)Stored at 60°C, 2 days.Migrants are extracted

PAPERBOARD

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