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Ultramid® Grades in Extrusion

The material of choice for demandingrequirements in the packaging andextrusion field

Ultramid® – the clear choice

Ultramid® is BASF’s trade name for itsline of polyamide (PA) products. BASFbegan manufacturing Ultramid®

polyamides over 50 years ago. Today,BASF is one of the world’s largestproducers of polyamides. Our line ofnylon products includes Ultramid® B(nylon 6), Ultramid® C (nylon 6/66copolymer) and Ultramid® A (nylon66).

Good packaging product assortment. Ultramid® nylon provides “transparency”

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Table 1: Melting temperaturesof Ultramid® resins

Ultramid® Polyamide Melting nylon type temperatures (°C)

B PA 6 220 (428 °F)

C PA 6/66 190-195 (374-383 °F)

A PA 66 260 (500 °F)

The Ultramid® nylon extrusiongrades, available in a wide variety ofviscosities and additive packages,are used in nearly all fields of pack-aging. Due to their outstanding prop-erties, they have become indispens-able to many applications.

Viscosity classThe following numbers specify the vis-cosity class by Relative Viscosity in96%/23°C sulphuric acid (i.e 33 forRV 3.3)

3 = easy flowing, low melt viscosity32 = intermediate viscosity33 = intermediate viscosity36 = intermediate to high viscosity40 = high viscosity50 = very high viscosity

The melt index (MI), measuredaccording to ISO 1133, decreases asthe molecular weight rises and is acommon measurement method forpolyolefins. However, as polyamidesare susceptible to melt-viscosity alter-ing moisture absorbtion, this methodis not commonly used.

AdditivesL = lubricatedN = nucleatedXL = extra high lubricatedA = antiblocking agentH = heat stabilized

Suffix01 for cylindrical pellet shape (no number = oval shape)

Example:B40 LN (PA6, high viscosity, RV = 4,0lubricated, nucleated)

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Ultramid® nylon – more than just ahigh-tech productUltramid® nylon is engineered espe-cially for your packaging application.

Moreover, BASF provides its cus-tomers the wide assortment of ser-vices that you expect from a leadingsupplier of engineering plastics,including:

worldwide availability of Ultramid®

nylon grades from manufacturing locations and sales offices throughout the world

uniform product quality lot-to-lot through the consistent application of BASF’s high quality standards which are identical all over the world

certification in accordance with ISO 9001.

Most importantly, we offer our cus-tomers comprehensive technical sup-port. Experienced technical servicerepresentatives specializing in extru-sion processes respond quickly toyour questions about materials andprocessing. Our laboratories are avail-able to perform an extensive array oftests to analyze materials and helpyou in your product development. Inaddition, our plastics processing facili-ties give you access to film extrusionpilot lines that help us work togetherto optimize your manufacturingprocess.

Ultramid® nylon’s strong crystallinecohesion is responsible for its highmelting point and high thermal stabili-ty, as well as for its hardness, abra-sion resistance and high gas andaroma barrier properties. The strongintermolecular bonding in the amor-phous zones provide polyamides withhigh impact strength and elasticityand impart polyamide films withexcellent thermoforming characteris-tics.

The semicrystalline nature of poly-amides results in an excellent combi-nation of properties and also makesthem an important raw feedstock forpackaging materials. For extrusionapplications, Ultramid® nylon is thematerial of choice if those propertiesare required:

oxygen barrier

flavor and aroma barrier

good mechanical properties

high transparency

thermoformability

heat-resistance

Nomenclature

The Ultramid® nylon range consists ofPA 6 grades, PA 66 grades andcopolyamides, such as PA 6/66.

Ultramid® extrusion grades are desig-nated by letters and digits which indi-cate chemical composition, viscosityand additives.

The letter (A, B, C) placed after theUltramid® nylon product name identi-fies the type of polyamide:

PA 6 grades Ultramid® BPA 6/66 grades Ultramid® CPA 66 grades Ultramid® A.

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Ultramid® nylon film propertiesand applications

Ultramid® nylons are especially well-suited for the packaging sector due totheir high strength, outstanding ther-moformability, high thermal stability,including resistance to sterilizing tem-peratures, and very good barrierproperties towards gases, especiallyoxygen, flavors and aromas.

In multilayer constructions with poly-ethylenes (LDPE, LLDPE, EVA), high-quality flexible film may be producedfor vacuum packaging of oxygen-sen-sitive foods such as ham, cheese,processed food and sausage. Vacu-um packaging is one of Ultramid®

nylon’s main applications today.

Ultramid® nylon films’ good thermo-formability guarantees particularlywell-shaped vacuum packing withgood contact clarity and outstandingappearance as well as good cost effi-ciency.

Ultramid® nylon is well suited for theproduction of biaxially oriented(BOPA) film which provides high stiff-ness, puncture resistance, barrier andtransparency.

Nylon sausage casing is characterizedby a high oxygen barrier as well asgood printing properties and gageconsistency.

Due to their special property profilesUltramid® nylon based mono- or mul-tilayer constructions may also beused in industrial applications such asrelease films for sheet molding com-pound (SMC), prepregs or roof under-felt sheeting.

The selection of the suitable Ultramid®

nylon grade is determined by film

Ultramid® nylon: It’s obvious what’s in the package,when you use Ultramid® nylon

Table 2: Standard properties of Ultramid® nylon films (film thicknesses 20-100 µm)

B36 LN C33 LN01 B33 Lcast film blown film BOPA film

25 µm 25 µm 15 µm

Melting temperature DSC °C 219 196 219

Density g/cm3 1.128 1.12 1.129

Tensile modulus MD MPa 1.600 1.400

Tensile modulus TD MPa

Stress at break MD MPa 85 80 260

Stress at break TD MPa 80 80 250

Elongation at break MD % 380 450 95

Elongation at break TD % 400 450 100

Oxygen Transmission Rate 23 °C/50 % rh cm3/m2d bar 18 21 25

CO2 Transmission rate 23 °C/0 % rh cm3/m2d bar 160 180 200

Water Vapor Transmission Rate 23 °C/85 % rh g/m2d 40 50 80

1000

100

10

1

-0,1

-0,01

Oxy

gen

Tran

smis

sion

Rat

e (m

l µm

/m2 ·

d b

ar

Relative humidity (%)0 6020 40 80 100

PEPPPET

Ultramid® nylon aromatic PAEVOH

Fig. 1: Barrier properties of polyamide films

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The compression ratio should be be-tween 3:1 and 3.5:1 (Fig. 2). The flightdepth depends on the screw diame-ter D and on the melt viscosity.

Barrier screws are used especially forconstant output. More gentle fusionand transport at constant speed arepossible in a narrow output range.

The screw clearance (radial clearancebetween the screw and barrel) shouldbe 0.1 to 0.2 mm to minimize leak-age.

property requirement, the processingmethod to be applied and, in the caseof coextruded films, on the viscositiesof the other polymers involved.Ultramid® B36 LN is typically com-bined with PE-LD or PE-LLD of 3.0-4.0 g/10min melt index, whereasUltramid® B40 L or B40 LN is coex-truded in combination with PE of 0.8-1.0g/10 min melt index.

Typical values for the properties offilm made from Ultramid® nylon areprovided in table 2.

Fundamentals, screw geometryand processing temperatures

Barrier or three-section screws havingan length of 24 to 28 D and a con-stant pitch of 1 D are generally con-sidered to be suited for processing ofUltramid® nylon (cf. Table 3).

For screws having diameters above90 - 150 mm, shear sections locatedat 22 - 25 D are recommended.

Screen packs having a mesh count of400 to 3,600/cm2 are usually recom-mended for the required backpres-sure and good melt homogeneity.

Processing temperature of Ultramid®

A grades is typically in the range of270 to 290°C, 240 to 270°C forUltramid® B and 210 to 260°C forUltramid® C. Suitably powered heaterbands and drives (e.g. 10 kW heaterpower and 60 kW drive power for anextruder having a screw diameter of60 mm) with precise controllers forscrew barrels, adapters and dies arerequired. Lubricants and nucleationagents have no significant effect onthe resultant melt temperature.

16

14

12

10

8

6

4

2

0

hE

hA

hA = flight depth in the metering section

hE = flight depth in the feed section

Standard screwShallow screw

Flig

ht d

epth

(mm

)

Screw diameter D (mm)30 40 60 80 9050 70 100 110 120

Table 3: Guide values for screw geometry (extrusion)

Length of sections

Total length L 20-28 D

Feed section LE 8-9 D

Transition section LÜ 4-6 D

Metering section LA 8-13 D1)

1) with shear section, length 1 -2 D

Fig. 2: Screw flight depths for three-section screwsin extrusion machines

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Processing techniques formanufacturing filmFlat film (cast film) and tubular film(blown film), which are used primarilyfor packaging food, may be extrud-ed from Ultramid® B, C and Agrades of medium to high viscosity,usually in the form of a multilayer filmcontaining polyethylene.

Blown film Multilayer blown film from Ultramid®

B or C resins, polyolefins and suit-able adhesive materials may be cox-etruded utilizing commercially avail-able equipment as used for manu-facturing of polyethylene blown film.Especially in the case of a non-sym-metric layer structure (e.g. PE/tie/PA/Ultramid® C), copolyamides arepreferred to produce highlythermoformable and flexible multilay-er film with high transparency andlow curl. The curl may be furtherreduced by humidification of the filmby a hot-water bath. Monolayerblown film may also be producedusing Ultramid® B grades orUltramid® A44.

The die gap should be approx. 1.0 -1.2 mm (multilayer film) or 0.5 mm(monolayer film). The extruded film iscooled with air, a take-off speed ofmore than 30 m/min (100 ft/min) isachievable. Typical blow-up ratio (diediameter/tube diameter) lies in therange of 1:3.0.

The tube should be collapsed asclose as possible to the solidificationzone (frost line) so that the film is laidflat while still warm and flexible.

Downward extrusion into a cold-water(6-20°C) cooling bath with outside orin/outside water cooling is also possi-ble. In this case, line speed up to 150m/min is feasible. Typical thickness oftubular film made from Ultramid®

nylons is 20 to 180 µm. Table 4 con-tains an example of tubular film extru-sion processing parameters.

Cast filmCast film (flat film) is mainly extrudedfrom Ultramid® B nylon grades. It isnormally drawn to a thickness of 20to 200 µm (1 to 8 mils) from T- orcoathanger dies of up to 2,000 mm(6.5 ft) wide. The die gap should beapprox. 10 -12 mm (multilayer film),line speed of 120 m/min is possible.For efficient production, extrudershaving screws of 60 -150 mm (2.5-6.0 in.) in diameter (25 to 28 D inlength) are recommended.

Film properties and quality (i. e. toler-ances, dimensional stability, machin-ability and transparency as well asthermoformability), are highly deter-mined by the processing conditions.The chill- roll temperature should beset to 20 -40°C for thermoforming filmof high transparency or 80 -120°C forfilm of high dimensioned stability.

Oriented PA filmBiaxially oriented (BOPA) film may bemanufactured from Ultramid® B resinsby rapid cooling of film and subse-quent simultaneous or sequentialstretching in machine and transversedirection. Cast (tenter frame) or blown(double bubble) technology may beapplied. Stretch ratio will usually bebetween 2.7 and 3.2 (both machineand transverse direction).

Artificial sausage casing may be man-ufactured from Ultramid® nylon asboth conventional as well as biaxiallyoriented shrinkable blown film.

PA 66 (Ultramid® A44) is primarily usedfor unoriented film, while PA 6 (Ultra-mid® B40 L) is highly suited for oriented,shrinkable film. Biaxially oriented cas-ing is frequently coextruded with poly-olefins in order to achieve therequired water vapor barrier in a mul-tilayer film application.

For processing examples, refer to table 4.

Table 4: Examples of film extrusion processing parameters for Ultramid® nylon

Product Unit B36 LN C33 01 B32B33 L

Production process cast film blown film BOPA film

Film type multilayer multilayer PA/PA/PA film

film PE/PA film PE/PA

Film width mm 1800 900 4200

Film thickness (total/PA) µm 120/30 90/15 15

Screw diameter mm 90 60 175

L/D 28 28 28

Screw sections L/D 9/5/14 9/5/14 9/5/14

Flight depth lf/lm1) mm 14/14.5 8/2.5 18/6

Heater temperatures Cylinder °C 265 250 265Adapter °C 260 245 260Die °C 260 245 260

Melt temperature °C 265 250 265

Melt pressure bar 120 150 150

Screw speed RPM 50 70 65

Output (total/PA) kg/h 500/180 250/50 750

Die T-die circular die T-die

Die width2) mm 2000 300 4500

Die gap mm 1.2 1.2 2

Blow-up ratio 2.2

Cooling chill-roll 30°C air 12°C chill-roll 12°Cair knive, IBC electrostatic pinning

vacuum box

Stretching (MDO/TDO) 3.2/3.0sequential orsimultaneous

Winding speed m/min 70 35 150

1) Flight depth in the feeding zone (lf) and the metering zone (lm)2) w = die width, d = die diameter

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Cast film

Quality control

Vacuum packaging Sausage casing

Blown film

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Processing of monofilaments

The following Ultramid® grades areused for the production of stretchedmonofilaments such as industrialwires, fishing lines, tennis racketstrings, weed trimmer lines, bristlesand dolls’ hair.

Ultramid® B27 E, a polyamide 6 of lowviscosity, is optimally suited for blend-ing with other Ultramid® grades for theproduction of monofilaments of dia-meters up to 0.7 mm. Applicationsinclude fishing lines, monofilamentsfor fishing nets, bristles and finemonofilaments for industrial fabrics.

Ultramid® B33 L, a polyamide 6 ofintermediate viscosity, is the general-purpose grade for the production offine and medium gage monofilamentsfor the fisheries sector and industrialapplications such as filters, paperscreening fabric and bristles. Thesemonofilaments are stronger and moreflexible than B27 E monofilaments.

Ultramid® B40 L is particularly suitablefor manufacturing stretched monofila-ments having medium and relativelythick diameters of up to 5 mm and forbristles.

Table 5: Monofilament processing

Ultramid® Unit B33 L C40 XL A34

Product Monofilaments, Monofilaments Monofilaments,bristles for fishing lines bristles(general) (general)

Production technique Extrusion, water quenched, stretched between rolls

Dimensions 2) mm d = 0.30 0.30 0.51

Screw diameter D mm 45 45 45

L/D 25 25 25

Flight depth hE/hA mm 8.0/2.5 8.0/2.5 7.0/2.2

Screw sections1) 6/7/12 6/7/12 9/4/12

Heater temperaturesbarrel °C 260/290/285/275 270/280/275/270 275/290/280/280adapter 275 265 280die 275 265 280

Melt tempereature °C 275 265 280

Melt pressure bar 120 32 42

Screw speed min-1 55 32 42

Type of die Die x 30 Die x 20 Die x 10Dimensions mm 1.40

2.0 d 3.0 d

Additional cooling Waterbath Waterbath10-20 °C 35-40 °C

Take-off/Stretching 7-roll set 7-roll set 7-roll set7-roll /3-roll set 7-roll /3-roll set 7-roll /3-roll setStretch ratio1:4.0Stretch temperature 1:5,7; 2-step 1:4.5210 °C 130 °C/230 °C 200 °C

Take-off speed m/min 25.0 20.0 20.0

Weight per unit length g/m 0.0806 (stretched) 0.0806 (stretched) 0.232 (stretched)

Output kg/h 16.8 10.3 10.8

1) Length of feed/compression/metering sections as multiple of screw diameter D.

2) s = thickness, d = diameter, b = width; for dimensions of roads and tubes see DIN 16980, 16983, 16982

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Ultramid® A27 E and A34 are used forrelatively stiff bristles and monofila-ments. Ultramid® A34 is also used inblends with Ultramid® B33 L for making weed trimmer lines.

Ultramid® C33 and C40 XL are suitablefor the manufacture of high-gradesports angling lines, hook monofila-ments, long lines of up to 2.0 mmand tennis racket strings.

Extrusion lines for monofilaments andbristles mainly consist of a single-screw extruder, spinning pump (precision gear pump), spinneret (multiple die), waterbath for cooling,roll stretching units, hot-water stretch-ing bath and/or hot-air stretchingchannels. The ratio of the peripheralspeeds of the roll stretching units,usually seven-roll sets, correspondsto the stretching ratio which is prefer-ably in the range of 1:4 to 1:6.Depending on the type of monofila-ment stretching, is done in one ormore steps. The subsequent shrink-age or relaxation step comprises of afurther hot-air channel and a set ofthree rolls which run at a lowerperipheral speed depending on therequired percentage shrinkage (e.g. 5to 10%).

Special methods involving particularknow-how are occasionally used forthe production of monofilaments orwires having large diameters (> 3 mm).

Table 5 provides examples of mono-filament extrusion.

Other extrusion applications

Ultramid® provides high resistance tolubricants, engine fluids, hydraulic andradiator oils, aliphatic and aromatichydrocarbons and many other sol-vents– even at elevated temperatures.Therefore tubes for central lubricationsystems, fuel and oil pipes, pneumaticand hydraulic control lines and Bow-den cables are produced utilizing highviscosity grades Ultramid® A44, B40 L,B50 L. Corrugated tubes for theautomotive industry are made ofUltramid® B40 L or B50 L.

As the global leader in nylon for build-ing wire jacketing, BASF Corpora-tion knows what it takes to succeedin this industry. By replacing a largeportion of the PVC insulation with athin layer of durable, abuse-resistantUltramid® nylon, performance increas-es while costs decrease. Our specialgrade of nylon not only provides ahigher level of abrasion resistance,end-use temperature rating, andhydrocarbon resistance, but alsoreduces PVC consumption, overallcost and weight. Of course, as youwould expect of a leader, we have theknow-how to successfully processthis product as well. Simply contactyour BASF representative.

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Post-processing of Ultramid®

Surface coatingDue to its outstanding resistance tomost solvents, Ultramid® may be coat-ed in one or several layers of variouspaints which adhere well and have noadverse effects on mechanical proper-ties. One- or two-component paintswith binders matched to the substrateare suitable.

MetallizingArticles made from the various Ultra-mid® grades may be metallized in highvacuum following priming or by elec-troplating after suitable preliminarytreatment. Excellent surface qualitycan be achieved.

DyeingUltramid® may be colored in the dye-bath using water dispersible, or watersoluble dyes.

ConditioningArticles manufactured of Ultramid®

resins will achieve their optimumtoughness and final dimensions onlyafter moisture absorption. Condition-ing by exposing products to warm,humid air or steam, or passingthrough hot water, will ensure rapidhumidity absorption to a level of 2.5-4% the equilibrium content in contactwith air at average relative humidity.(cf. Fig. 3)

0 6020 40 80 100

8

6

4

2

0

Temperature range 10 - 70 °C

C33, C40 LB33 L, B40 L, B50 LA27 E, A34, A44

moi

stur

e ab

sorp

tion

(%)

Relative humidity (%)

Fig. 3: Equilibrium moisturecontent of Ultramid®

as a function of relative humidity in the temperaturerange 10-70°C

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Safety precautions during processingUltramid® resins will decompose, asall thermoplastic polymers, whenexposed to excessive heat, e.g. whensetting too high processing tempera-tures or when cleaning equipment byburning off. Besides Caprolactamsmoke (in case of Ultramid® B and C),gaseous decomposition products,mainly ammonia and carbon monox-ide may be formed, especially whenthe resin is heated to above 310°C. Attemperatures above 350°C, smallquantities of pungent smelling vaporsof aldehydes, amines and othernitrogenous decomposition productsmay also formed.

Generally, measures should be takento ensure ventilation and venting ofthe work area, preferably by means ofan extraction hood over extrudercylinder and die.

Food legislation

Certificates regarding the status ofUltramid Extrusion grades withrespect to agency compliance can beobtained by contacting BASF.

Ultramid® nylon extrusion grades(Ultramid® B, C) fulfil the requirementsof the European Directive2002/72/EC dated 6th August 2002related to “plastic materials and arti-cles to come into contact with food-stuffs” and its amendments and therequirements of the Bedarfsgegen-ständeverordnung (German ordinance)in the revised version of 23.12.1997(Monomers an other starting sub-stances) including the 9th amendmentof the ordinance of 07.04.2003 andthe BfR (former BgVV/BGA) – Recom-mendation X. “Polyamid”, dated01.06.98.

The following restrictions for Ultramid® B grades have to beensured:

Caprolactam:SML(T) = 15 mg/kg, together with itssodium salt expressed as caprolac-tam.

The following restrictions for Ultramid® C grades have to beensured:

Caprolactam:SML(T) = 15 mg/kg, together with itssodium salt expressed as caprolac-tam

Hexamethylenediamine:SML = 2,4 mg/kg

The meaning of the used abbrevia-tions are:

SML(T) = specific migration limit infood or in food simulant expressed as total of moiety of substance(s) indicated SML = specific migration limit in foodor in food simulant

Ultramid® B extrusion grades complywith the FDA Regulation 21 CFR177.1500, “Nylon resins” Section (b)6.1. Ultramid® C extrusion gradescomply with the FDA Regulation 21CFR 177.1500 “Nylon resins”, Section(b) 4.2 and should be used only forlaminates complying with 21 CFR177.1395.

Supply form and storage

Ultramid® is supplied predried andready for processing in a variety ofmoisture proof containers, such asboxes, big bags (Asia) and bulk con-tainers.

To ensure that the perfectly dry mate-rial delivered cannot absorb moisturefrom the air, the containers must bestored in dry rooms and always care-fully sealed again after portions ofmaterial have been withdrawn. Ultra-mid® can be kept indefinitely in theundamaged bags. Containers storedin cold rooms should be allowed toequilibrate to normal temperature sothat no condensation on the pelletsmay occur.

Note

The data contained in this publicationare based on our current knowledgeand experience. In view of the manyfactors that may affect processing andapplication of our product, these datado not relieve processors from carry-ing out their own investigations andtests; neither do these data imply anyguarantee of certain properties, northe suitability of the product for a spe-cific purpose. Any descriptions, draw-ings, photographs, data, proportions,weights etc. given herein may changewithout prior information and do notconstitute the agreed contractualquality of the product. It is the respon-sibility of the recipient of our productsto ensure that any prosprietary rightsand existing laws and legislation areobserved. (August 2004)

Please consult your local Represen-tative regarding product selectionand availability in your area.

Do you have technical questionsabout Ultramid®?

We will be happy to assist you at ourExtrusion Infopoint:

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