i october 2016 plasticizers in food contact materials...

Plasticizers in Food ContactMaterials and Adhesives

Dr. Monika Tönnießen, Hartmut Büsching I October 2016

Europe- specific content

02/11 | Plasticizers in Food Contact Materials and Adhesives

Why are plasticizers used andwhere do we find them?

Plasticizers are additives that increase the plasticity or fluidity of a material. The use of plasticizers allows improved compound processing characteristics. At the same time it provides flexibility in the final product.

Some technical effects of plasticizers are:

• Brittle materials become flexible, soft, stretchable or sticky• Improved workability and elasticity• Decrease of the elastic modulus and the glass transition temperature• Swelling or dissolving of the polymer

Plasticizers can be found in many products we use frequently in our daily life. This includes toys, gaskets, floor coverings, window profiles, varnishes and lacquers, cigarettes, chewing gum and tablet coatings. Plasticizers are also used in adhesives. As adhesives play an important role when it comes to food packaging they should be chosen with particular focus on the risk of migration of plasticizers into the foodstuff.


Definition of plasticizers

Plasticizer

Effect of plasticizers

Figure 1

Rigid PVC

• Strong dipole-dipole interaction � Crystalline structure

Externally plasticized PVC

• Incorporation of plasticizer � physical interaction � Breaking-up of the polymer chains � Amorphous structure

Internally plasticized PVC

• Incorporation of co-monomers (e.g. vinyl acetate) with large side groups � chemical bonding � Reduction of the intermolecular attractive force � Amorphous structure

Typically we differentiate two types of plasticization that are characterized by the use of either internal plasticizers or external plasticizers.

Internal plasticizers Internal plasticizers cause a chemical modification of a rigid polymer (copolymerization). The molecular weight is > 1000 Da. As a result of the (internal) chemical reaction of the plasticizer with the polymer chain, the intermolecular attractive force is reduced. The polymer beeing of crystalline structure before now shows an amorphous structure. An internal plasticizer is chemically bonded. Therefore it cannot move outside of the adhesive film. On these grounds the common understanding in the adhesive world is that internally plasticized products are considered plasticizer-free.

External plasticizers External plasticizers are added to a polymer. There is no chemical reaction with the polymer chain. The molecular weight of an external plasticizer is < 1000 Da. This relatively low molecular weight leads to a relatively high molecular mobility. External plasticizers are liquid or solid organic substances with a low vapor pressure and a high boiling point (> 250 °C). They are indifferent substances that show no chemical reaction but a physical interaction. External plasticizers break up the interaction of the polymer chains and widen their separation from each other and thus raising the polymer chain mobility. Even though the external plasticizers are not chemically bonded, they are supposed to remain in the final product and therefore also in the adhesive film after drying.

O

O R

RO

O

O

O R

O

O R

R

R

R

PO

O

O

O

O

O

ORR

O

O

O

OO

R

R

O HOR


Difference between plasticizers and solvents

Plasticizers based on esters

Figure 2

Both plasticizers and solvents are used in adhesives but with different characteristics and functions.

Solvents• Influence the production process of the final product.• Low boiling point.• Should not remain in the final product (e.g. the adhesive film).

Plasticizers• Influence the properties of the final product.• High boiling point.• Are supposed to remain in the final product and (therefore) also in the adhesive film after drying.• Internal plasticizers remain in the final product because they are chemically bonded.• External plasticizers are critical to migration as there is no chemical bonding which leads to a high tendency of migration.

Types of external plasticizers

Today there are more than 300 known external plasticizers. Approximately 100 of them are commercially important.

Plasticizers based on esterIn this documentation we focus on external plasticizers that are based on ester. Plasticizers based on ester qualify for the use in water-based adhesives because of their dipole character.

Examples of ester-based external plasticizers are: Phthalates, Adipates, Phosphates, Benzoates, Citrates and Acetates.

The most commonly added ester-based plasticizers for the use in water-based adhesives are either a mixture of benzoates or Triacetin. Especially Triacetin has been much used recently due to its good performance and very low impact on human health.

Properties of an ideal external plasticizerIf we wanted to list the properties of an ideal external plasticizer, it would look like this:

• Odorless• Colorless• Resistant against light, cold and heat• Low volatile• Not harmful• Relatively large size (i. e. extended separation of the polymer chains for a good plasticizing effect)• With polar and non-polar groups (to enable interaction with both polymer parts)• Very effective at low amount• No migration (which is impossible to realize)

Phthalates Adipates

Phosphates Benzoates

Citrates Acetates

• Triacetin

• Diisobutyl phthalate (DIBP)• Dibutyl phthalate (DBP)• Dioctyl phthalate (= Di(2-ethylhexyl)– phthalate, DOP, DEHP)

• Dioctyl adipate (DOA)• Diisononyl adipate (DINA)

§


External plasticizers and migration

In many chemicals different external plasticizers are used. According to their toxicological assessment they may or may not be used for adhesives for food contact materials.

Plasticizers like Phthalates have been commonly used for many years until critical health concerns have been raised. Today, Phthalates should not be used. They are marked as SVHC (Substances of very high concern), i. e. their use must be authorized in the EU. For us at Henkel the SVHC classification is reason enough to ban Phthalates as plasticizers!

Other types of plasticizers are under evaluation by the European Chemicals Agency (ECHA) under the Community Rolling Action Plan (CoRAP). As there is still no sufficient data available for a severe evaluation and complete assessment, the use of these alternative plasticizers is currently restricted to certain application.

Finally there are two external plasticizers that can be declared as suitable for the use with food contact material.

• Acetyltributylcitrate is not classified according to CLP classification. Anyway its use for FCM can be justified due to the toxicological assessment. However, citrates are not likely to be used in adhesives.• Triacetin represents no risk according to its toxicological assessment. It is permitted as an additive for food in the EU under the E-Number E 1518 (explicitly for chewing gum; EU No 1129/2011).

Migration of plasticizers from adhesives

Figure 3

Impact of external plasticizers on human health

In a typical packaging profile for a food packaging two materials are bonded by an adhesive to protect the foodstuff inside the packaging.

Migration is the transfer of molecules from the adhesive layer into the foodstuff causing a contamination. At the same time there is also the tendency that substances from the foodstuff migrate into the packaging. This leads to a loss of the foodstuffs' composition, i. e. to a possible quality degration.

All parts of the packaging materials contribute to the migration of the whole packaging, not only the adhesive layer!

In case the adhesive contains an external plasticizer, the small plasticizer molecules quickly migrate (definately in both directions) causing a massive contamination of the foodstuff with the plasticizer.

Possible effects of the migration of plasticizers:• Incipient dissolution of contact materials• Corrosion of contact materials• Swelling of contact materials• Adhering/sticky on the surface• Contribution to windscreen fogging• Contamination of foodstuff

Packaging

material 1 AdhesivePackaging

material 2 Food

Plasticizer

Migration


PlasticizerCAS No

HarmonizedC&L

Toxicological assessment

Phthalates

Diisobutyl phthalate (DIBP) 84-69-5 H360DfShould not be used, SVHC-substance: use must be authorized in the EU

Dibutyl phthalate (DBP) 84-74-2 H360DfShould not be used, SVHC-substance: use must be authorized in the EU

Dioctyl phthalate (= Di (2-ethylhexyl) phthalate, DOP, DEHP)

117-81-7 H400Should not be used, SVHC-substance: use must be authorized in the EU

Adipates

Dioctyl adipate (= Di(2-ethylhexyl)adipate, DOA, DEHA)

103-23-1 H360FDSome uncertainty due to lack of data, under further evaluation by ECHA (CORAP), current use might be justified for some applications

Diisononyl adipate (DINA) 33703-08-1no harmonized classification

Some uncertainty due to lack of data, use might be justified for some applications

Phosphates

Tri-2-ethylhexyl phosphate (TOP, TEHP)

78-42-2no harmonized classification


2-Ethylhexyl diphenyl phosphate 1241-94-7no harmonized classification


Benzoates

Diethylene glycol dibenzoate (DEGB) 120-55-8no harmonized classification

Some uncertainty due to lack of data, under further evaluation by ECHA (CORAP), current use might be justified for some applications

Triethylene glycol dibenzoate 120-56-9no harmonized classification


Dipropylene glycol dibenzoate 27138-31-4no harmonized classification

Some uncertainty due to lack of data, under further evaluation by ECHA (CORAP), use might be justified for some applications

Citrates Acetyltributylcitrate (ATBC) 77-90-7no harmonized classification

Use in FCM justified

Acetates Triacetin (E 1518) 102-76-1no harmonized classification

Food additive (permitted in chewing gum according to regulation (EU) No 1129/2011)

Toxicological assessment of external plasticizers

Toxicological assessment of external plasticizers

Figure 4


Plasticizer CAS No

Legislation / Restriction

(EU) No 10/2011BfR XIV

BfR XXI BfR XXXVI FDA

Phthalates

Diisobutyl phthalate (DIBP) 84-69-5 no no nomax. 0.3 mg/kg foodstuff sum of DBP and DIBP max. 0.3 mg/kg foodstuff

175.105

Dibutyl phthalate (DBP) 84-74-2

FCM: 157 SML = 0.3 mg/kg plasticizer in repeated use materials and articles con-tacting non-fatty foods

no nomax. 0.3 mg/kg foodstuff sum of DBP and DIBP max. 0.3 mg/kg foodstuff

175.105

Dioctyl phthalate (= Di (2-ethylhexyl) phthalate, DOP, DEHP)

117-81-7 no nomax. 10 %

max. 1.5 mg/kg foodstuff 175.105

Adipates

Dioctyl adipate (= Di(2-ethylhexyl)adipate, DOA, DEHA)

103-23-1FCM: 207 SML = 18 mg/kg SML (T) = 60 mg/kg

nomax. 10 %

no 175.105

Diisononyl adipate (DINA) 33703-08-1 no no no no 178.3740

Phosphates

Tri-2-ethylhexyl phosphate (TOP, TEHP)

78-42-2 no no no no 175.105

2-Ethylhexyl diphenyl phosphate 1241-94-7FCM: 392 SML = 2.4 mg/kg

no no no 175.105

Benzoates

Diethylene glycol dibenzoate (DEGB) 120-55-8 no no no no 175.105

Triethylene glycol dibenzoate 120-56-9 no no no no 175.105

Dipropylene glycol dibenzoate 27138-31-4 no no no no 175.105

Citrates Acetyltributylcitrate (ATBC) 77-90-7FCM: 138 SML (T) = 60 mg/kg

no no no 175.105

Acetates Triacetin (E 1518) 102-76-1FCM: 40 SML = OML

no no no 175.105

Plasticizers in food contact legislation

Looking at external plasticizers in food contact legislation we focus on the following legislations / restrictions:

• (EU) No 10/2011 (on plastic materials and articles intended to come into contact with food)• BfR XIV, XXI or XXXVI (recommendations of the German Federal Institute for Risk Assessment)• FDA (legislation of the U.S. Food and Drug Administration)

None of the below listed plasticizers is in compliance with the BfR XIV recommendation due to the fact that BfR XIV deals only with plasticizer-free dispersions.

Plasticizers in food contact legislation

Figure 5

Recycling – You always meet plasticizers twice!Plasticizers are not eliminated during the paper recycling process. Looking at recycled cardboard, plasticizers rather enrich during the manifold recycling steps leading to a high risk for food contact contamination when using the recycled cardboard in food packaging. You always meet plasticizers twice – first in the original packaging and again in the recycled material.

Acetyltributylcitrate and Triacetin as the most recommended substances under the toxicological point of view are listed in (EU) No 10/2011. For Triacetin the specific migration limit (SML) equals the overall migration limit (OML) meaning that this acetate is allowed to migrate up to the maximum permitted amount of non-volatile substances released into the food, the OML value of 60 mg/kg.


History of improvements for food packaging adhesives

History of improvements for food packaging adhesives containing plasticizers

1950 1990 2007 2010 2012 2016

Figure 6

Looking at the common use of external plasticizers there has been a number of improvements during the last decades. Henkel reacted whenever a substance became evaluated and/or considered as critical with respect to consumer health.

Already in 2007 important associations in Germany committed themselves to stop using the Phthalate DIBP. As a result of the aligned actions of the involved industries, DIBP in recycled cardboard dropped significantly.

Henkel does not use DBP, DIBP or other Phthalates in its products. The very high concern these plasticizers cause has made Henkel looking for alternatives from the very beginning.

DBP

DIBP

Benzoates

Triacetin

Low Migration (LM)

Plasticizer Migration potential EU BfR XIV FDA

DBPDIBPBenzoatesTriacetininternal plasticizer

highhighhighhighlow

SVHCSVHC

x

PP

x

x x

P P

P P P P P


Plasticizer-free with Henkel

Since many years Henkel has developed and promoted a low migration product range without external plasticizers. Henkel's development focuses on internally plasticized products as these are commonly considered plasticizer-free, and therefore also these Henkel products are free of plasticizers.

Adhesives play a key role in the manufacturing of food packaging.

Adhesives of Henkel’s AQUENCE LM line provide the full range of low migration water-based adhesives. All AQUENCE LM adhesives use a plasticizer-free formulation with a minimum content of critical substances compared to traditional adhesives and a significantly higher efficiency through lower adhesive consumption.

Plasticizer-free and low migration by HenkelLM (Low Migration) shows the highest advantage for food contact with the best criteria.

Safe Food Packaging with AQUENCE LM adhesivesAQUENCE LM offers a complete water-based product range for the use with packaging from bags and sacks to folding boxes.

AQUENCE LM adhesives• Full range of low migration water-based adhesives• Plasticizer-free formulation with minimum content of critical substances• Easy and clean processing• Equal or better adhesive strength compared to traditional adhesives• Significantly higher efficiency through lower adhesive consumption

AQUENCE® LM for the Packaging Industry

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Key take aways

Adhesives could contain internal or external plasticizers.

Internal plasticizers are chemically bonded. They cannot migrate into the foodstuff.

Adhesives with such plasticizers are considered ‘plasticizer-free’.

External plasticizers are small molecules with a high migration potential. They show

different toxicological behavior, some species are classified as SVHC, Triacetin is allowed

as a food additive.

Water-based adhesives containing external plasticizers cannot comply with the XIV.

BfR recommendation.

Henkel can offer plasticizer-free adhesives as low migration products. These products

are in compliance with the relevant food contact legislation (FDA, (EU) No 10/2011 and

BfR recommendation).

Literature and useful links

D. F. Cadogan, Ch. J. Howick, Ullmann’s Encyclopedia of Industrial Chemistry, Wiley-VCH Verlag, Vol. 27, p. 599-617, 2012

Römpp Online Lexikon Chemie, Thieme-Verlag, 2014 https://roempp.thieme.de/roempp4.0/do/data/RD-23-00480

Datenbank BfR-Empfehlungen zu Materialien für den Lebensmittelkontakthttps://bfr.ble.de/kse/faces/DBEmpfehlung.jsp

Database BfR Recommendations on Food Contact Materialshttps://bfr.ble.de/kse/faces/DBEmpfehlung_en.jsp?filter=clear

Plastics Regulation (EU) No 10/2011http://eur-lex.europa.eu/legal-content/EN/TXT/?qid=1476646824639&uri=CELEX:32011R0010

Hartmut Büsching works in the product development for water-based paper converting adhesives with more than 35 years of experience. His main application fields are adhesives for packaging and consumer goods. A major part of his product development projects are adhesives for food packaging.

The information provided herein, especially recommendations for the usage and the application of our products, is based upon our knowledge and experience. Due to different materials used as well as to varying working conditions beyond our control we strictly recommend to carry out intensive trials to test the suitability of our products with regard to the required processes and applications. We do not accept any liability with regard to the above information or with regard to any verbal recommendation, except for cases where we are liable of gross negligence or false intention. The information is protected by copyright. In particular, any reproductions, adaptations, translations, storage and processing in other media, including storage or processing by electronic means, enjoy copyright protection. Any exploitation in whole or in part thereof shall require the prior written consent of Henkel AG & Co. KGaA. Except as otherwise noted, all marks used in this document are trademarks and/or registered trademarks of Henkel and/or its affiliates in the US, Germany, and elsewhere. © Henkel AG & Co. KGaA, 10/2016

Further information Visit the Food Safe Packaging Premium Area offering webinars, white papers, FAQs, videos and more: www.henkel-premium-area.com

Webinars Our webinars allow you to directly communicate with our Henkel food safety experts. Check our website for the dates of upcoming webinars.

Dr. Monika Tönnießen is a chemist by profession and works in the Product Safety Department of the Henkel Adhesive Technologies division. Since 2006 she deals with customer inquiries and is an expert on all food contact related questions. She is member of the paper & packaging group of the European Adhesive Association FEICA.

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Henkel AG & Co. KGaA 40191 Düsseldorf, Germany www.henkel.com/foodsafety

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