Product and Properties Guide

DuPont™ Elvamide®

resins

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Table of Contents

Introduction .................................................................................................................................................................... 1

Features and Uses .......................................................................................................................................................... 1

Physical Properties ........................................................................................................................................................ 2

Specifications ................................................................................................................................................................. 3

Chemical Properties ....................................................................................................................................................... 3

Solution Technique ........................................................................................................................................................ 3

Thermosetting Adhesive Uses ..................................................................................................................................... 7

Textile Adhesive Uses ................................................................................................................................................. 11

Extrusion and Molding Uses ....................................................................................................................................... 12

Test Methods for Elvamide® Resins .......................................................................................................................... 17

Special Safety Precautions ........................................................................................................................................ 17

Packaging ...................................................................................................................................................................... 18

Patent Status ................................................................................................................................................................. 20

Regulatory Status ......................................................................................................................................................... 20

IntroductionElvamide® resins are thermoplastic polyamides thatcombine the inherent toughness of nylon with easeof processing in solvent as well as melt systems.Elvamide® resins differ from conventional nylonsin that they offer:• Alcohol solubility• Lower melt-processing temperatures• High elongation• Ability to cross-link with thermosetting resins

Elvamide® resins can be used singly or in a combi-nation and can be further modified by formulatingwith plasticizer or other resins to meet specific end-use requirements. For most uses, they are appliedfrom solvent solutions. They can also be meltcompounded as, for example, in the manufacture ofpigment concentrates or for extrusion into filmadhesives for heat reactivation. Their relatively lowmelt-processing temperature allows use with heat-sensitive pigments and substrates.

Like Zytel® nylon resins, Elvamide® resins aresuitable for molding and extrusion. They are tough,withstand impact and resist abrasion, but are softerand more flexible than conventional nylons.Melting points for Elvamide® multipolymer resinsrange from 115°C (239°F) to 160°C (320°F),compared with 265°C (509°F) for high temperatureresistant 66 nylon homopolymer.

Features and UsesThe important features of Elvamide® resins arelisted below:• Abrasion resistance• Impact resistance• Resistance to most oils, solvents and gasolines• Pigment dispersing ability• Melting point• High tensile strength• Natural lubricity• Toughness at high and low temperatures• Alkali resistance• Antioxidant ability

It is this combination of outstanding propertieswhich results in benefits for a variety of uses.

Textiles• Thread Bonding—solutions of Elvamide® resins

bond filaments into a strong thread that resistsabrasion and high needle temperatures, prevent-ing thread fraying and needle jamming at highsewing speeds.

• Salvage Bonding—high melting point and tensilestrength make Elvamide® a good bonding mate-rial for salvage edges, especially for knits,preventing unraveling and easing conversionoperations.

• Fabric Bonding—film adhesives of Elvamide®,which are reactivated by heat, provide strongfabric-to-fabric bonds that resist laundering anddry cleaning, especially on nylon fabrics.

AdhesivesAlone or in combination with epoxy, phenolic orother thermosetting resins, Elvamide® provides filmadhesives with superior toughness, impact resis-tance and flexibility.

Adhesives based on Elvamide® resins are especiallyeffective for bonding metal/metal laminates ofsimilar or different metals.

Pre-impregnated glass fibers as well as carbonfibers can be formed into structural elements offishing rods, sporting goods, antennas, etc. that arehighly impact resistant.

CoatingsCoatings based on Elvamide® resins are relativelyclear and non-tacky, and provide abrasion resis-tance and durability for fish and playpen netting,nylon seat belts, fabric screening, wire andcable, tennis racquet strings, and plastic films.Elvamide® provides a tough tie-coat for articles tobe extrusion-coated with type 66 nylon. BecauseElvamide® resins are highly resistant to mosthydrocarbons, they offer excellent protection forarticles such as conveyor belts and fuel tanks ofrubber or other elastomers.

Color ConcentratesThe compatibility of Elvamide® resins with othernylons such as types 6, 66, 610 or 612 make it anexcellent color concentrate carrier resin for moldedand extruded nylon articles.

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Moldings and ExtrusionsElvamide® resins provide relatively soft, flexible,impact-resistant moldings and extrusions.

BindersElvamide® 8061 strength retention at elevatedtemperatures and low processing temperaturesmake it a preferred binder for rocket fuels,explosives, and lubricants.

Other ApplicationsElvamide® resins offer toughness, flow characteris-tics, solvent resistance and quick set for hot-meltinks with improved printability.

Elvamide® resins serve as an antioxidant andnonmigratory stabilizer when blended in variousplastics.

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Physical PropertiesTable 1 shows typical values for physical proper-ties of Elvamide® resins. Elvamide® 8061 is oftenpreferred for thread bonding applications andextruded products.

Elvamide® 8063 is more gel resistant than 8061and is preferred for solutions which are stored forprolonged periods.

Elvamide® 8066 is a low melting point resindesigned particularly for textile adhesive uses. Itcan also be combined with thermosetting resins inmetal laminating adhesives, where it permits curingat lower temperatures than Elvamide® 8061. Inaddition, it has found application as a color concen-trate carrier resin.

Table 1Typical Physical Properties of Elvamide® Resins

ASTM Elvamide® Elvamide® Elvamide® Elvamide®

Typical Propertiesa Method Units 8061 8063 8023R 8066

Form — — 3-mm (1/8 in) 3-mm (1/8 in) 3-mm (1/8 in) 3-mm (1/8 in)cubes spheres spheres spheres

Color — — transparent to transparent to transparent to transparent toopaque opaque opaque opaque

Moisture Content D789 % 0–0.7 0–0.7 0–5.0 0–5.0

Melting Point D3418 °C (°F) 156 (313) 158 (316) 154 (309) 115 (239)

Relative Viscosity — — 70–100 70–100 24–36 21–29

Specific Gravity D792 — 1.08 1.08 1.07 1.0823/23°C (73/73°F)

Water Absorption, % D570 % 3.1 3.4 3.4 1.424 hr immersion

Rockwell Hardness D785 R 71 71 65 —

Shore Hardness D2240 D 75 75 70 72

Tensile Strengthb D638 MPa (psi) 51.4 (7,500) 51.7 (7,500) 51.0 (7,400) 39.0 (5,700)23°C (73°F)

Elongation at Breakb D638 % 320 315 370 37023°C (73°F)

Flexural Modulusb D790 MPa (psi) 952 (138,000) 903 (131,000) 490 (71,000) —23°C (73°F)

Characteristics — — General purpose; Greater gel Low viscosity Softer resincombines good resistance. for special with lower

solubility, abrasion Lower solution high solids melting pointresistance and viscosity than solutions. for textile

toughness. 8061. adhesives.

a These data describe Elvamide® resins but are not intended to serve as specifications.b Samples conditioned in equilibrium with atmosphere and 50% RH.

Elvamide® 8023R offers the highest solids solutionat a given temperature when compared with theother grades of Elvamide®.

The Elvamide® resins as packaged have a lowmoisture content. To protect against further mois-ture uptake these resins are shipped in moisture -barrier bags. If Elvamide® is to be used wheremoisture can be a problem, care should be takenonce the bag is opened to avoid exposure to highhumidity. On the other hand, moisture may contrib-ute to ease of solution; in this case, the resin can beimmersed in water overnight before dissolving.(See Table 6.)

SpecificationsTo ensure consistent solution or melt viscosity,DuPont controls relative viscosity for each gradeof Elvamide® to the following specifications:

Grade Relative Viscosity8023R 24–368061 70–1008063 70–1008066 21–29

Test procedures for measuring relative viscosity aredescribed on page 17.

Chemical PropertiesElvamide® resins are insoluble in water. They resisthot or cold aqueous alkali solutions and most saltsolutions for weeks or months. Acetic acid attacksthe resin slowly; stronger acids react more rapidly.Formic acid will dissolve Elvamide® resins. Mostoxidizing agents react with Elvamide® but oxygenand oxygen-containing gases including ozone havelittle effect unless elevated extrusion temperaturesare used.

The Elvamide® resins are highly resistant topetroleum-based products, showing little changeafter prolonged contact with lubricating oils andgreases, or aliphatic and aromatic hydrocarbons.

The higher fatty acids, such as stearic acid have noappreciable effect on Elvamide® until a temperatureof 150°C (302°F) is reached. The nylon resins arealso resistant to most organic solvents includingconventional lacquer solvents and diluents, carbondisulfide, esters, ethers, and amides.

Elvamide® resins contain carboxyl, amide andamine groups which react with thermosetting resinsto form cross-linked structures. With epoxy resins,the amide groups along the nylon resin chain takepart in the reaction.

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Solution TechniqueSolvent SelectionSelection of a solvent or solvent system for formu-lating and applying Elvamide® resin is very impor-tant and depends on the desired solids level andsolution viscosity, solution stability requirements,nature of the substrate, processing equipment aswell as the ultimate application technique.

The most popular solvents for Elvamide® resin aremethanol, ethanol and 2-propanol, and mixtures ofthese with water. Other solvents for Elvamide®

resin include benzyl alcohol, furfuryl alcohol,formic acid, phenol and m-cresol.

Anhydrous methanol is the most effective solventand will dissolve up to 50% by weight ofElvamide® 8061 or 8063 with heating.

Typical StabilityOn prolonged storage at room temperature orbelow, solutions of Elvamide® resin may showclouding or gelation; solution stability is increasedas the temperature increases. Gelled solutions canbe restored by gentle heating (no open flame) andstirring prior to use.

In alcohol-water solvent systems, the intermolecu-lar nylon hydrogen bonding is reduced and therebydecreases solution time and the tendency for gelformation.

Stability of Elvamide® 8061 in alcohol/watermixtures can be improved by the addition of smallamounts of benzyl alcohol or other high-boilingsolvents. See Table 4. With multicomponentsolvent systems the boiling point of any azeotropeshould be considered.

As shown in Tables 2 and 3, Elvamide® 8063 giveslower viscosity for a given solids content thanElvamide® 8061 and is more gel resistant.

Methanol solutions containing 40 wt% Elvamide®

8061 should be used promptly as gelation occurs inless than 3 hr at 25°C (77°F). At 50% solids, themaximum stability is reduced to 30 min.

Elvamide® 8023R gives the lowest viscositysolutions and is preferred where high solids arerequired. At least 30% can be dissolved readily inalcohol/water mixtures by stirring at 45–60°C(113–140°F) for approximately 1 hr. Table 5 showstypical solution viscosities. After two weeks atroom temperature, the 30% solids solution in-creased in viscosity but had not gelled.

Table 2Typical Solution Stability of Elvamide® 8061

Brookfield Viscosity, mPa·s (cP)a Gelation, daysa

Parts (wt) Solvent Composition 10% Solids 20% Solids 10% Solids 20% Solids

100 Methanol 30 280 10b 3

85/15 Methanol/water 39 610 10–11 6

90/10 Ethanol/water 103 1860 10–11 6

80/20 Ethanol/water 111 1960 10–11 6

100 1 -Propanol 66 — 2 —

90/10 1 -Propanol/water 76 — 10 2

aStability (gelation) tests and viscosity measurements were made at 25°C (77°F).bSolution cloudy but still mobile.

Table 3Typical Solution Stability of Elvamide® 8063

Brookfield Viscosity, mPa·s (cP) Gelation, daysParts (wt) Solvent Composition 10% Solids 20% Solids 10% Solids 20% Solids

100 Methanol 14 155 30–31 <1

85/15 Methanol/water 21 253 30–31 25–26

90/10 Ethanol/water 37 — <1 —

80/20 Ethanol/water 42 730 25–26 25–26a

100 SDAb #30 alcohol, 200 proof 28 gel 2–3 1 hr

100 SDA #2B, 190 proof 36 578 25–26 <1

a Solution cloudy but remains fluid.b See Chemical Handbook for SDA (specially denatured alcohol) formulas.

Table 5Typical Solution Viscosity of Elvamide® 8023R

Methanol/Water % Brookfield Viscosity,Parts by Wt Solids mPa·s (cp)a

85/15 20 130

80/20 20 140

80/20 30 1,030

aMeasured at 25°C (77°F) with model LVT, #1 spindle.

Table 4Typical Stability Improvement with High Boiling Solvents

15% Solids Elvamide® 8061Nylon Multipolymer Resin

High Boiling Solvent Amount 70/30 Ethanol/Water 80/20 Ethanol/Water

Time Before Gelation, Days (23°C, 73°F)

None — 1 7

Benzyl alcohol 5% 16 26

Furfuryl alcohol 5% 4 26

m-Cresol 5% 4 15

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PreparationFor solutions of Elvamide® resins up to 20% solids,the resin pellets should be added to the solvent withcontinuous stirring. The mixture should then beheated (no open flame) with continued stirring to atemperature that is 5–10°C (9–18°F) below thereflux point of the solvent or solvent mixture. Usualtemperatures are 54–60°C (130–140°F).

For suggested preparation equipment see Figure 1.The use of a reflux condenser is preferable forsolution preparation. Explosion-proof electric or airmotor agitator drives are adequate for most solutionoperations.

Heating and stirring should continue for at least onehour after solution appears complete in order toinsure that all particles have dissolved. Solvent-swollen resin particles are colorless and transparent,and consequently are difficult to detect.

Tank cover with hinged lid

Solvent resistant gasketa around lid

Positive lid hold-down latch(es) to compress

gasket

Outlet valve

Propeller, crescent or anchor agitator

Metal tank with hot water jacket

Sealb around shaft where entering tank

cover

Explosion proof air or gear reduction motor

Optional reflux condenser

Figure 1. Equipment for Preparing Solutions

NOTE: Add ventilation over tanks as necessary to remove fumes fromwork areas. All metal parts should be grounded according toapplicable codes and practices for handling flammablesolvents.

a Suggested materials include Nordel® synthetic rubber or othermaterials recommended by gasket suppliers as suitable for use withmethanol or other alcohol.

b Seals of Teflon® fluorocarbon resin or other materials recommendedby their suppliers as suitable for use with methanol, etc.

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Table 6Typical Solution Times

Solvent, Temperature, Solution Time,wt% °C (°F) hr

Elvamide® 8061100 methanol 57 (135) 2100 methanol 39 (103) 4.5–580/20 methanol/water 42 (107) 370/30 methanol/water 44 (112) 3100 2-propanol 71 (160) Insoluble after 3 hr80/20 2-propanol/water 71 (160) 2.75

Pre-weta Elvamide® 8061100 methanol 39 (103) 4

Pre-driedb Elvamide® 8061100 methanol 39 (103) 5.5–6

Elvamide® 8063100 methanol 39 (103) 3

NOTE: All solutions contained 8% solids.a Elvamide® 8061 was pre-wet by soaking in water at 39°C (103°F) for 16 hr.b Elvamide® 8061 was pre-dried for 7 days in a vacuum dessicator.

Total time required depends on solvent type, resinconcentration and type of agitation. Typical solu-tion times are summarized in Table 6. Overnightsteeping of the resin, preferably with periodicagitation, expedites dissolution. The time requiredfor completing the solution depends on the solventmixture used and the concentration resin particlesize desired.

When solvent solutions are stored or handled,adequate ventilation should be provided. See thesection on Safety Precautions in this bulletin.Detailed information on safe handling of flammableliquids can be obtained from the National FireProtection Association* or from your solventsupplier.

The above precautions are not intended to be allinclusive. They should be supplemented by goodmanufacturing procedures, prevailing industrystandards and the recommendations of solventsuppliers.

* NFPA Std. No. 30, “Flammable Combustible Liquid Code,” NFPA,Battery March Park, Quincy, MA 02269

Dispersions of Elvamide® 8063 in water at 10%solids are available from General Plastics Corp.*For information, contact your sales representative.(See back cover.)

ProcessingSolutions of Elvamide® resins can be applied bydipping, brushing, spraying, or with conventionalcoaters designed to handle solvent-based systems.

Because of their relatively low melting temperaturecompared to molding grade nylon resins,Elvamide® resins also can be processed usingstandard melt compounding techniques.

Unless heat is used during drying, atmosphericmoisture may cause a cloudy or opaque coating.Clear coatings can be obtained from anhydroussolvent systems if the drying temperature issufficiently high to offset the cooling effect ofevaporation and prevent condensation of atmo-spheric moisture on the surface. The requiredtemperatures can be maintained with infrared heator a circulating-air oven designed for use withflammable solvents.

To obtain a clear film using an aqueous solventsystem (such as an alcohol/water mixture), a fusiontreatment is recommended. By heating the coatingabove the resin melting point, optimum clarity,adhesion and physical properties can be developed.

Formulating SolutionsGrades of Elvamide® resins can be formulated witheach other or with modifiers to produce a varietyof properties. Generally modifiers are used withElvamide® to improve adhesion to specific sub-strates, to vary blend toughness and flexibility,or for an optimum balance between cost andperformance.

Typical modifiers for Elvamide® resins includeplasticizers, thermosetting resins, thermoplasticresins and elastomers. See Table 7 for a listing ofmodifiers compatible with Elvamide® resins.

One plasticizer commonly used with Elvamide®

resin is 2-ethyl-1, 3 hexanediol at amounts up to15 parts per hundred resin.

*55 LaFrance Ave., Bloomfield, NJ 07003

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Table 7Typical Modifiers Compatible with Elvamide® Resins

Plasticizers

Glycols Ethylene glycol2-Ethyl-1, 3-hexanediol

Phenols Octyl phenolResorcinol

Sulfonamides Bisphenol Aa

NBBSb

Thermosetting Resins

Epoxy Aralditec

Derakanea

Epond

Melamine/ Formaldehyde Cymele

Resimenef

Phenol/ Formaldehyde

a Dow Chemical Co. d Resolution Performance Productsb Unitex Corp. or Proviron Inc. e Cytec Industries Inc.c Ciba-Geigy Corp. f Solutia Inc.

Thermosetting or cross-linking resins of the epoxy,phenolic or melamine formaldehyde type arefrequently used as resin modifiers. Elvamide® resinreacts with these at curing temperatures to producehybrid thermoset- thermoplastic compositions. SeeTable 7 for examples.

In blends with epoxies or phenolics, 15–20%Elvamide® resin significantly improves the tough-ness and flexibility of the cured resin withoutimpairing tensile strength or chemical resistance.The amine and carboxyl end groups on Elvamide®

resins as well as the amide hydrogens along thechains enable Elvamide® resins to cross-link withthermosetting resins during the curing cycle. Theseblends with thermosetting resins are especiallyuseful in high-strength structural adhesives dis-cussed in more detail in the following section.

Combinations of Elvamide® resin and thermoplasticmaterials (Table 7) can be applied as resin solu-tions or hot melts.

Thermosetting Adhesive UsesHigh-strength, fatigue-resistant polyamide/thermo-set resin adhesives were initially developed to meetrequirements set by aerospace engineers designinglightweight, smooth-surfaced, honeycomb struc-tures of aluminum. (These developed into a rangeof uses mentioned on pages 1 and 2 under “Adhe-sives.”) They found adhesive bonded metal/metallaminates to have many advantages:

• no rivets to cause buckling of surfaces betweenpoints of contact

• no stress concentrations at isolated points ofcontact

• no high-temperature distortion of bonded parts• no electrochemical corrosion between dissimilar

metals• simplification of design

Today, interest in adhesive bonding extendsthrough wide segments of the metal-fabricatingindustry. Laminates of stainless steel to sheets ofcarbon steel for architectural panels, automotivetrim, and window frames are examples of the cost-saving specialties possible. Adhesive bonding alsopermits the lamination of metal to other materials-such as glass and plastics.

Formulation requirements differ from one use toanother. The development of high lap shearstrengths may be the dominant need in one applica-tion; high peel strengths in another.

Although Elvamide® 8061 and 8066 can functionas heat-activated adhesives (good shear and peelstrength), the addition of a thermoset resin, e.g.20%, which cross-links with polyamide duringcuring, eliminates creep and gives an adhesive ofsuperior toughness and flexibility. The bondsformed during the curing of compositions ofElvamide® 8061 and thermoset resins are capableof withstanding severe deformation; they are alsosignificantly stronger than the bonds developed in

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adhesives based on thermoset resins alone. Adhe-sives of Elvamide® 8061 and epoxy resin, forexample, develop much higher peel strengths thanthe corresponding straight epoxy formulations.

Blends of Elvamide® 8061 and thermoset resin areuseful in preparing postformable laminates as wellas for other metal-to-metal bonding operations, forsandwiching honeycomb cores between metalsheets, and for bonding metals to various othersubstrates.

Formulating AdhesivesStructural adhesive formulations combineElvamide® 8061 (65–90% of total resin) with athermosetting resin (35–10%), a thermoset-curingagent, fillers (optional), and a solvent (evaporatedif adhesive is used in film form). On heat-curing,the polyamide cross-links with the thermosettingresin to become an integral part of the curedadhesive. Elvamide® 8061 contributes toughness,flexibility, and good flexibility retention to thecured blend while giving bonds higher in both peelstrength and shear strength than those obtained withthe thermosetting resin alone. Application ofElvamide® 8061/thermoset adhesives can be fromsolution or as dry film.

Selection of Thermosetting ResinsMany thermosetting resins are sufficiently compat-ible with Elvamide® 8061 to permit their use inadhesive blends. Combinations of Elvamide® 8061with epoxy resins of the bisphenol-A type andrelatively high epoxy content are particularlyeffective in providing high-strength, flexible bonds.Table 8 compares the shear strength of aluminum-to-aluminum bonds prepared in the laboratory usingtypical thermosetting resins in combination withElvamide® 8061. Note the superior lap shearstrengths given by the epoxy-type resin. (Peelstrengths are likewise optimum.)

Table 8Typical Adhesive Formulations Based on Elvamide® 8061 and Thermoset Resins(Material bonded: unprimed 0.16 cm [0.064 in] Alclad 2024-T3 aluminum alloy sheet; 1.3 cm [0.5 in] lap)

Thermosetting Resin Curing Agent Zn Dust Lap Shear Strength,Trade Name Type Type phra Filler, %b mPa (psi)c

Epon 828d epoxy DICYe 10 0 42.7–45.5 (6200–6600)

Epon 828 epoxy DICY 10 33.3 30.3–32.4 (4400–4700)

Resinox 410f phenolic TETAg 10 33.3 21.4–22.8 (3100–3300)

Aerotex 607h melamine- Phenol 50 33.3 14.5–20.7 (2100–3000)formaldehyde

a Parts (wt)/l00 parts thermosetting resin c Ambient conditions e dicyandiamide, Cytec Industries g triethylenetetramine, Dow Corp.b Based on total solids d Resolution Performance Products f Solutia Inc. h Cytex Industries, Inc.

Ratio of Elvamide® 8061 to Thermosetting ResinThe optimum combination of bond strength andflexibility is generally achieved with blends con-taining 60–80% Elvamide® 8061, based on totalresin content (see Figure 2). At concentrations ofElvamide® 8061 above this range, shear strengthdeclines and the adhesive begins to assume thethermoplastic character of unmodified Elvamide®

8061. Adhesive blends containing less than 60%Elvamide® 8061 are less flexible, have lower peelstrength and lower shear strength. However, as littleas 20% Elvamide® 8061 significantly improves theflexibility of brittle thermosetting resins.

35

30

25

20

15

10

– 5,500

– 5,000

– 4,500

– 4,000

– 3,500

– 3,000

– 2,500

– 2,000

– 1,500

– 1,000100 110 120 130 140 150 160 170 180 190 200 210 220

CODE: Elvamide® / Epoxy ratio

80/20

90/10

10b phr DICY

7 phr DICY

Lap

Shea

r Ten

sile

c , MPa

Lap

Shea

r Ten

sile

c , psi

Epoxide Equivalent of Epoxy Resin

Figure 2. Typical Shear Strengtha of Adhesives of Elvamide® 8061 and Epoxy Resin

a After 1-hr curing at 163°C (325°F) using dicyandiamide (DICY). Material bonded: unprimed 0.16-cm (0.064 in) Alclad 2024-T3 aluminumalloy sheet; 1.3-cm (0.5-in) lamp.

b Parts per hundred parts of total resin.c Ambient conditions.

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Curing Agents and Cure SchedulesThe polyamide chains of Elvamide® 8061 resincontain carboxyl and amine end groups which reactwith thermosetting resins during cure to form cross-linked structures. With epoxy resins, the amidegroups along the nylon resin chain also take part inthe reaction. There is no specific epoxide equiva-lency of Elvamide® resins. Complete cure of anepoxy resin with Elvamide® 8061 takes place athigh temperatures (e.g., 60 min at 232°C [450°F])in the absence of a conventional curing agent.However, the addition of a curing agent for the

thermosetting resin in an adhesive based onElvamide® 8061 gives a more practical curingcycle.

In formulations of Elvamide® and thermosettingresin, the curing agent concentration depends on thetype and amount of thermosetting resin used.Figure 2 shows the effect of both epoxide equiva-lency of the epoxy resin and curing agent concen-tration on the lap shear strength of adhesives ofElvamide® 8061 and epoxy resin.

In general, the resin manufacturer’s recommenda-tions should be followed with regard to type andamount of curing agent and cure schedules for theparticular thermosetting resin used. To developmaximum bond strength, however, the glue lineshould be heated above the melting point of theElvamide® nylon multipolymer resin, i.e., above160°C (320°F) for adhesives based on Elvamide®

8061. Because of its lower melting point,Elvamide® 8066 permits curing at temperaturesas much as 56°C (100°F) below those requiredusing Elvamide® 8061.

With blends of Elvamide® 8061 and epoxy resincontaining rapid curing agents, high peel strengthbonds have been obtained in as short a time as10–15 sec at 177–204°C (350–400°F). Longer cureschedules and suitable pretreatment of the substratesurface can increase the peel strength.

Examples of curing agents suitable for use informulations of Elvamide® 8061 and epoxy resinare given in Table 9. Suggested concentrations foruse with epoxy resins having an epoxide equivalentof 189 (e.g., “Epon 828,” “Araldite 6005”) areshown.

Table 9Curing Agents for Formulations of Elvamide® 8061 and Epoxy Resin

Curing Agent phra Characteristics

Dicyandiamideb (DICY) 10 Latent curing agent requiring high temperature for cure; suggestedfor developing maximum bond strength.

Triethylenetetraminec (TETA) 10 Active curing agent for use where rapid cure is required; can befurther accelerated by catalysts, e.g., 1 phr of phenol or resorcinol;gives high peel strength bonds in less than 1 min at 177°C (350°F).

Epon C-111d 100 Active curing agent; chemically an amine adduct of an epoxy resin;Curing Agent (solution slower than TETA but tends to develop higher bond strength.

as supplied)

DICYa + USB-11Oe 10 Rapid cure system; stable at 27°C (80°F); gives superior peelAminoborane each strengths in 60 sec or less at 232°C (450°F).

a Parts (wt) curing agent per 100 parts epoxy resin (epoxide equivalent, 189). d Resolution Performance Productsb Cytec Industries, Inc. e U.S. Borax Inc.c Dow Corp.

Effect of FillersAdding 20–40% of a suitable filler to a formulationof Elvamide® 8061 and thermosetting resin in-creases the peel strength of the adhesive, butusually at a sacrifice in shear strength. Table 10illustrates the effect of fillers on the peel and shearstrengths of a typical blend of Elvamide® 8061 andepoxy.

Table 10Effect of Fillers on Bond Strength

% Based ona Peel Strengthb Lap Shear Strengthc,d

Filler Total Solids kN/m (lb/in) mPa (psi)

None — 10.5–14.0 (60–80) 42.7–45.5 (6200–6600)

Alumina 33.3 14.9–27.0 (85–154) (not determined)

Glass, hammer-milled 33.3 10.5–14.0 (60–80) (not determined)

Zinc dust 33.3 14.7–16.5 (84–94) 30.3–32.4 (4400–4700)

a Adhesive is 75/25/10 Elvamide® 8061/ Epon® 828/DICY. Curing conditions are 60 minutes at 163°C (325°F).b Material bonded: 24 gauge Al foil to 0.16 cm (0.064 in) Alclad 2024-T3 sheet (unprimed). Peel strength of adhesive determined (ambient conditions) by climbing drum

method, 180° angle.c Material bonded: unprimed 0.16 cm (0.064 in) Alclad 2024-T3 sheet; 1.3 cm (0.5 in) lap.d Ambient conditions.

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Fillers assist in maintaining the desired glue linethickness, because filled compositions have lesstendency than unfilled resin blends to exude fromthe glue line during heat-curing. With some ther-mosetting resins, addition of fillers may be neces-sary to prevent excessive bond shrinkage duringcure.

Effect of Exposure on BondsThe effect on bond strength of heating, exposure toultraviolet light, and immersion in water and typicalsolvents is illustrated in Table 11. Adhesives ofElvamide® 8061 and epoxy resin lose approxi-mately 50% of their bond strength at temperaturesapproaching 93°C (200°F), but show excellentstrength at cryogenic temperatures.

A

C

H

U

T

S

l

n

T

a

b

c

d

Table 11Effect of Exposure on Bond Strength

(Material bonded: unprimed 0.16 cm [0.064 in] Alclad 2024-T3 sheet; 1.3 cm [0.5 in] lap)

Exposure Testa Lap Shear Strengthb, mPa (psi)gent Time Epoxy: Araldite® 6005c Epon® 828d

ontrol 33.8 (5200) 42.7 (6200)

eat (not determined) 20.7 (3000)

ltraviolet light (Weatherometer) 60 hrs 29.0 (4200) (not determined)

ap Water 7 days 32.1 (4650) 43.8 (6360)

alt Spray 10 days (not determined) 41.4 (6000)

sopropanol 7 days 35.0 (5080) (not determined)

-Hexane 7 days 33.1 (4800) (not determined)

ransmission oil 7 days 31.7 (4600) (not determined)

All tests at 21° (70°F) except that for heat; to test effect of heat on bond, specimen was held at 82.2°C (180°F) during test procedure. Although the effect of lowtemperature has not been determined in DuPont laboratories, Elvamide® 8061 /epoxy adhesives are known to have excellent strength characteristics under cryogenicconditions. Adhesive is 75/25 Elvamide® 8061/Epoxy. Ciba Specialty Chemicals resin cured 60 min at 204°C (400°F); no curing agent. Resolution Peformance Products resin cured 60 min at 163°C (325°F); 10 phr dicyandiamide.

Preparation of AdhesivesIn preparing adhesives for application from solvent,the Elvamide® 8061 resin should be put intosolution before adding the thermosetting resin. Themost practical solvents for Elvamide® 8061 are thelower aliphatic alcohols and mixtures of these withwater. Anhydrous methanol [b.p., approx. 64°C(148°F)], the most effective solvent of the series,will give hot mixtures containing up to 50 wt%Elvamide® 8061.

Preparing Liquid AdhesivesAdding the thermosetting resin to the solutionof Elvamide® 8061, then stirring briskly, gives asolution which, for solids concentrations of

10

10–30%, will remain stable at room temperatureover several months. Formulations containing latentcatalysts designed for high temperature cure havealso shown good stability at room temperature.

Systems containing active curing agents mustbe stored in tight containers in a cool location toprevent evaporation of the solvent. Loss ofsolvent results in rapid cure of the adhesive at roomtemperature.

When preparing a liquid adhesive for immediateuse, one simply combines the solution ofElvamide® 8061 with the thermosetting resin,curing agent (if used), and filler (if used) at roomtemperature, stirs briskly for 15–30 min, thenapplies—e.g., by brush.

Preparing Adhesive FilmsAdhesives for application in film form can beformulated using latent curing agents. TheElvamide® 8061 and thermosetting resin are firstdissolved in a compatible solvent system just as inpreparing solvent-type adhesives. Curing agent,fillers, and any other additives are then incorpo-rated. The solution is cast on a release surface,dried at 93–121°C (200–250°F) or below, andstripped. Suitable casting surfaces include stainlesssteel, films of Elvanol® polyvinyl alcohol, andTeflon® fluorocarbon film.

As with any coating operation, adhesion dependsnot only on the composition of the adhesive butalso on the extent of contact of the adhesive withthe substrate. Maximum bonding requires uniformcontact and this, in turn, requires a clean substratesurface and an even coat of adhesive.

Application TechniquesSurface PreparationCleaning and etching the metal substrates beforebonding insures maximum bond strength. In thework reported in Tables 8, 10, and 11, the alumi-num alloy sheet or aluminum foil was vapordegreased, then immersed for 10 min at 66°C(150°F) in a pickling bath of the followingcomposition:

Parts by Weight

Sodium dichromate 31Concentrated sulfuric acid 50Water 170

The test specimens were rinsed in cold then hot tapwater, dried in an oven at 60°C (140°F), and usedimmediately. Etching the solvent-cleaned surfacesincreased bond strength by approximately 10%.

Adhesive ApplicationWhether the adhesive is applied from solution or infilm form, the amount should be sufficient to give afinal cured glue line at least 0.025 mm (1 mil)thick. Solution-type adhesives are evenly applied toone or preferably both of the surfaces to be joinedand allowed to dry before the parts are assembled.Formulations containing active curing agents areunstable even at room temperature once the solventhas evaporated. Films deposited from adhesivesof Elvamide® 8061 and epoxy resins formulatedwith active curing agents are no longer fusible after24 hr at room temperature. To avoid prematurecure, solvent should be driven off at or near roomtemperature, the parts assembled, then heat-curedpromptly.

Bond Formation and CureIn the bonding operation, surfaces previouslycoated with solution-type adhesive, or interleavedwith film-form adhesive, are brought together under

11

sufficient pressure to maintain good contact. Heat isthen applied to bring the glue line to cure tempera-ture. To develop maximum bond strength, theadhesive layer must be heated above the meltingpoint of Elvamide® 8061. The optimum tempera-ture will depend on the system-usually 177–191°C(350–375°F) for conventional curing schedules,210–232°C (410–450°F) for quick cures. Asdiscussed, Elvamide® 8066 permits lower curingtemperatures than Elvamide® 8061. The objectivesare to permit good wetting of the surfaces by themolten adhesive and to insure homogeneousinteraction of the Elvamide® and thermosettingresin for maximum cross-linking during curing.

Adhesives containing active curing agents shouldbe brought to flow-temperature rapidly, i.e., within5 min or less. Otherwise, cure will have advancedtoo far by the time the prescribed temperature isreached to permit good flow and wetting, and bondstrength will be poor.

The cure times specified in Tables 10 and 11 andin the section on curing agents refer to duration ofheating after the glue line has reached the tempera-ture designated.

Textile Adhesive UsesElvamide® 8066, a low-melting resin, is designedparticularly for textile adhesive uses such asembroidery and label attachment, heat sealabledecorative tapes and fabric stiffening. The resingranules as supplied can be extruded into film orcryogenically ground to produce a fusible powder.

Because of its low moisture sensitivity and resis-tance to dry-cleaning solvents, Elvamide® 8066 canprovide fabric-to-fabric bonds with excellentresistance to laundering and dry-cleaning. Table 12illustrates the strength of fabric-to-fabric sealsattainable with Elvamide® 8066 and shows theeffect of scaling temperature on bond strength.

Table 12Heat Seal Strengtha of Elvamide® 8066

Peel Strength, kN/m (gm/in)Heat Seal Temperature, °C (°F) Elvamide® 8066 Type 12 Nylon

121 (250) 0.23–0.33 (600–850) 0.23 (600)

135 (275) >0.77 (>2000) 0.58 (1500)

149 (300) >0.77 (>2000) >0.77 (>2000)

a 0.08 mm (0.003 in) films of resin sealed between two strips of 65/35 Dacron® polyester/cotton fabric for 2 sec at 138 kPa (20 psi).

Extrusion and Molding UsesElvamide® resins expand DuPont’s family of nylonresins for specialty uses such as those mentioned onpage 1.

Figure 3 shows the effect of temperature on meltviscosity of Elvamide® 8061.

Figure 3. Melt Viscosity vs. Melt Temperature (Shear Stress = 3 x 105 dynes/cm2) L/D = 16

400 440 480 520 560 600

200 220 240 260 280 300 320Melt Temperature, °C

Mel

t Vis

cosi

ty, m

Pa·s

(cP)

Melt Temperature, °F

10,000,000

1,000,000

100,000

543

2

543

2

Elvamide® 8061

Based on resin moisture <0.10%

Extruder OperationExtrusion ConditionsFor Elvamide® 8061, a melt temperature of218–232°C (425-450°F) is suggested. The tempera-tures of the die, adapter, neck, and front zones ofthe barrel should be controlled at the desired melttemperature. See Table 13, “TroubleshootingGuide.”

1

Resin HandlingAll nylon resins are hygroscopic and, therefore,readily absorb moisture from the atmosphere. Forexample, with 66 homopolymer nylon resin, aslittle as 0.05 wt% water gain in the resin candecrease the melt viscosity sufficiently to seriouslyimpair an extrusion. If the total moisture contentexceeds about 0.15–0.20 wt% then bubbling orsplaying of the melt will occur.

DuPont Elvamide® resins for extrusion requiredrying to a moisture level less than 0.2 wt%.

2

Table 13Troubleshooting Guide-Extrusion Process

Issue Possible Cause Corrective Means

1. Bubbles in melt a. Excessive moisture a. Use resin directly from bag.(constant bubbling b. Keep hopper covered.or frothing) c. Use counter-current purge of nitrogen gas in hopper.

d. Store resin at same temperature as around extruder.

b. Overheating of melt a. Lower controller settings.b. Check controllerc. Check thermocouple.d. Use proper thermocouple location.e. Be sure thermocouple is properly seated.f. Increase the number of control zones.g. Reduce screw speed.h. Use barrel cooling.i. Use proper screw.

c. Excessive hold-up a. Increase the output—it may be too low for the extrusiontemperature.

b. Improve the streamlining of the system, particularly the die.

2. Erratic bubbles in the melt a. Entrapped air a. Use proper screw.(e.g., periodic bubbling) b. Lower barrel heats.

c. Increase back pressure (screen pack, valve, or changetemperature profile).

d. Check controller units.

3. Surging a. Inadequate reservoir a. Use a slower screw speed.of melt b. Use proper screw.

c. Change temperature profile—raising rear usually helps,especially for screw with short feed zone.

d. Check for a temperature cycle.e. Increase back pressure by valving or by using a heavier

screen pack.f. Increase land length of die.g. Reduce die slot opening.

b. Bridging in feed a. Prevent bridging by starting up with rear zone set belowsection melting point on nylon resin.

b. Try increasing rear and center barrel temperatures.c. Use cooling water in the feed section of the screw.d. Calibrate temperature control units of feed zone.

c. Bridging in transition a. Increase rear and center rear barrel temperatures.zone b. Use screw with longer feed section.

d. Slippage in belt drive a. Tighten belts.

4. Bridging in feed zone a. Poor shutdown a. Turn heat off in rear and rear center zone and extrude atof screw procedure shutdown.

b. Use cooling water on feed section of screw.

5. Overloading the extruder a. Rear barrel temperature a. Raise rear temperature.too low b. Check thermocouple and controller of rear zone.

b. Wedging of cubes a. Don’t use undercut feed throat.between flight land and b. Increase rear temperature.barrel wall

c. Degraded resin on a. Use acrylic purge and clean extruder.screw land (after too b. Use high screw speed.many start-ups andshutdowns)

(continued)

13

6. Carbon specks a. Dirty equipment a. Make sure extruder is clean.b. Use purge procedure.

b. Extruder run dry at a. Leave some resin in feed throat at shutdown.shutdown b. Change screen pack after purging at high speed.

7. Poor caliper control a. Extruder surging a. See issue #3.b. Lower rear barrel temperture.

b. Variable take-off a. Repair or rebuild take-off.b. Change to DC drive.

c. Inadequate temperature a. Insulate as much as possible.b. Calibrate control units for minimum on/off cycle.

Table 13Troubleshooting Guide-Extrusion Process

Issue Possible Cause Corrective Means

(continued)

Under normal operating conditions in areas of lowhumidity or in air-conditioned plants, hopperresidence times of up to one hour can be toleratedwithout any noticeable moisture pickup. However,in areas of high humidity where long hopperresidence times are required, it is good practice toprovide a very slow purge of dry air or nitrogeninto the base of the hopper to prevent moisturepickup. Under these conditions, a constant meltviscosity of the resin being processed will beensured. A cover for the hopper should be used atall times to eliminate dirt.

Hopper driers may be used to insure the resin ismaintained in a dry condition. The air supplied tothe hopper should be passed through a molecularsieve or equivalent-type dehumidifier to eliminatemoisture.

Start-upThe start-up technique is very important as itinvolves the safety of both operating personnel andmachine. In addition, proper start-up of extrusionequipment will greatly facilitate smooth operationfor extended periods without costly shutdowns.Start-up techniques will vary depending uponwhether or not the machine is clean.

Clean MachineFor start-up with a clean machine, the temperaturecontrollers of the die, neck, adapter, and barrelextension zones are set at operating temperaturesfor the particular resin and process. (As a rule ofthumb, set temperatures 17°C [30°F] above themelting point of the nylon resin being processed.)This is a good opportunity to check the operation ofcontrollers.

14

When these zones reach the operating temperature,the remaining barrel zones, except the rear, areheated to the same temperature. The rear zone isdeliberately kept below the melting point of thenylon resin to prevent overheating and possiblebridging problems during start-up. Feed throatcooling water is turned on. Cooling of the entirescrew is not recommended in processing nylon;however, cooling of the feed zone (5 flights) iseffective in solving some specific feeding problemslike erratic or nonuniform feeding.

When all zones have been at the desired tempera-tures for 20–30 min, the resin may be fed into thehopper. The screw should be turned on at a slowspeed (5–10 rpm). When it has been establishedthat the screw is picking up the resin properly, thebarrel rear zone is raised to the desired operatingtemperature.

Until one becomes familiar with the specific nylonresin being extruded, it is suggested that the resinbe hand fed gradually until melt appears at the die.At this point, the melt should be clear and the melttemperature should have leveled out. It is desirableto use a pressure gauge and an ammeter to monitorthe extruder performance at start-up. For maximumsafety of the equipment, the pressure gauge shouldbe located between the end of the screw and thebreaker plate.

Full MachineIn the extrusion of nylon, the equipment usuallyhas been shut down with resin remaining in themachine to prevent oxidation that might occur ina partially empty extruder. When possible, it is

suggested that the machine be purged with a fairlylow melting resin such as polyethylene beforeshutting down. This will insure the resin will bemelted before the extruder is restarted again. Caremust be exercised in starting a full machine toprevent bridging in the feed zone, localized over-heating resulting in resin degradation, and coldspots (unmelted plugs in sections such as theadapter).

The following procedure will facilitate a smoothand safe start of a full machine:

Set all controllers from the front barrel section(metering zone) forward about 28°C (50°F) abovethe resin melting point. The other barrel controllersare left in the off position to prevent overheatingthe rear section of the screw. Bridging of the screwwill then be prevented. When all the controllershave reached the set point, then the barrel control-lers are turned on and set to the operating tempera-ture. When all controllers reach the set point, theextruder is ready to be started. Feed throat coolingwater is used during this start-up operation.

The screw is now set at a low or idle speed untilsmooth flow from the die is obtained. If melt flowis not observed, the screw is turned off and thebarrel rear is raised 28°C (50°F). The machine isallowed to set under this condition for a fewminutes and the screw is again turned to slow oridle speed until smooth flow is obtained. Once theflow from the die has been observed, the barrel rearis set to the desired operating temperature and safeextrusion can then be undertaken. Watch for anyexcessive melt pressure and amperage during thestart-up—this indicates the presence of an unmeltedplug.

ShutdownFor a brief shutdown of 30 min or less, no changesare required. However, certain procedures shouldbe followed when the extruder containing nylon isto be shut down for periods longer than 30 min.

For subsequent extrusion operation with minimumloss of time and material, the following pointsshould be observed:• Continue to use feed throat cooling water.• Drop the extruder temperature setting to 11°C

(20°F) above the melting point of the nylon resin.• Maintain extrusion at reduced speed.

1

• Continue to feed resin to the screw. This preventsthe formation of air pockets or voids in the diewhich would cause the resin to oxidize, resultingin inferior melt in the next start-up.

• When all control, as well as melt temperatureshave dropped below 5°C (9°F) over meltingpoint, the screw power and heat can be turned off.At this temperature, the resin is sufficientlyviscous to prevent material exuding from the die.The point at which extrusion should cease mayalso be determined by the amperage limit of theindividual equipment. This limit should beestablished for each installation.

An alternative method shutdown involves purgingthe extruder with polyethylene. A medium-densitypolyethylene resin can be used to purge nylon fromthe extruder without changing the temperatureprofile. Screw speed may be varied, however, tohelp purge. When the melt appears clear, the die,adapter, and neck temperature settings are reducedbelow the nylon melting point. When the moltenextrudate indicates that the purging has beencompleted, the normal polyethylene shutdownprocedure is followed. The temperature of the die,neck piece adapter, and barrel is turned off. Thescrew power is turned off when the temperature ofthe barrel has dropped below the nylon meltingpoint.

Film CastingSince Elvamide® resins have lower melting pointsthan conventional nylon molding and extrusionresins, lower chill-roll temperatures are required.The maximum chill-roll temperature to preventsticking of Elvamide® 8061 is about 41°C (105°F).

By operating the chill roll at as high a temperatureas possible, the rate of crystallization is increased,less post-crystallization occurs and roll conforma-tion problems are minimized.

The processing conditions of melt temperature,quench temperature, air gap and rate influence thephysical properties of cast nylon film. The follow-ing general statements indicate the more significanteffects of these conditions. The degree of the effectdepends on the specific resin being processed.

5

Effect of increasing melt temperature

• Transparency and gloss increase• Haze decreases• Impact strength increases

Effect of increasing quench temperature

• Yield strength increases• Haze increases• Transparency and gloss decrease• Impact strength decreases

Effect of increasing air gap

• Haze increases• Transparency and gloss decrease

Effect of increasing rate

• Haze decreases• Transparency and gloss increase

Of the above variables, rate and air gap have thegreater influence on properties.

Resin DryingAll Elvamide® resins go through a multiple-phasedrying cycle with hot, dry air before packaging.

The equilibrium moisture content of the nylondecreases as the moisture content of the incomingair decreases. If the moisture content of the incom-ing air is too high, it is not possible to dry the nylonsufficiently at reasonable drying temperatures.

Hopper DryersA typical dehumidified hopper-dryer systemconsists of a filter, blower, dehumidifier, heater anda hopper. Air is circulated by the blower throughthe dehumidifier. The dehumidifier air is thenheated and passed through the resin in the hopperand back to the dehumidifier via a filter. Pneumaticconveyers, or preferably vacuum systems, are usedto feed resin into the hopper.

The rate of drying in a hopper dryer will be essen-tially the same as that in a tray oven for the samedrying temperature and inlet air humidity. Anadvantage of the hopper-dryer system is thecounter-current flow of polymer to air. The driestair contacts the driest polymer since the polymer isexiting at the bottom of the hopper and the dry air isentering at the bottom of the hopper.

16

A number of potential problems associated withhopper dryers includes:• Incoming dry virgin resin subjected to unnec-

essary heating or air tends to discolor. Separatedrying of regrind can eliminate this problem.

• Uneven flow of resin through the hopper. Thisproblem is most noticeable in the conical sectionabove the throat of the hopper. It is possible thatin a poorly designed hopper, the moisture level ofthe molding powder might vary enough toproduce erratic molding conditions.

• Insufficient holdup time for drying wet nylon ona fast cycle.

• Inability to maintain a truly closed system.• Inability to maintain a constant drying tempera-

ture. Insulation of the hopper minimizes thisproblem.

Vacuum DryingElvamide® resins can be dried in vacuum ovens orin rotary vacuum tumbler dryers. Figure 4 showsthe absolute pressure required to achieve a givenequilibrium moisture content for nylon at variousdrying temperatures.

Figure 4. Vacuum Required to Dry Nylon Resins

79°C(175°F)

110°C(230°F)

91°C(195°F)

Absolute Pressure

Wei

ght P

erce

nt W

ater

in N

ylon

(at E

quili

briu

m)

0.3

0.2

0.1

0

kPa 0 1.7 3.4 5.1 6.8 8.4Mercury, mm 0 12.7 25.4 38.1 50.8 63.5

Mercury, in 0 0.5 1.0 1.5 2.0 2.5

The preferred way to operate a vacuum drying ovenis as follows:Charge the oven with the nylon resin to be dried.Apply vacuum to the drying vessel. Heat the vesselto the selected drying temperature. The dryingprocess is complete when the oven pressure readingcorresponds to the pressure required at the desiredmoisture level given in Figure 4. One precautionthat must be taken in this case is to measure thevacuum in the drying vessel itself and not at thevacuum source. To minimize color formation, it isdesirable to evacuate the vessel before heating thepolymer.

Any leakage of room air into the oven will makethe above-described drying technique invalid. Thisdoes not mean that nylon can not be dried in avacuum vessel that has some leaks. In such cases,estimation of the final moisture content of the nylonis not possible unless the amount of leakage andthe relative humidity of the air leaking into the ovenare known.

Test Methods for Elvamide® ResinsNylon resins can be distinguished from otherplastics by a simple burning test. Place a smallpiece of the resin in a “Pyrex” tube and heat theend of the tube gently with a small flame until thepolymer has partially melted and some decomposi-tion has occurred. Scorched nylon gives off anunmistakable odor similar to that of burning hair.

Shown below are test methods for Elvamide® themost important of which is relative viscosity.

Relative ViscosityRelative viscosity is a calculated value of the ratioof absolute solution viscosity to the absoluteviscosity of the solvent. It is measured for an8.4 wt% solution of Elvamide® resin in 90% formicacid solvent (0.11 g resin/mL formic acid). Theabsolute viscosity of formic acid is determinedusing a Cannon-Fenske size 75 viscometer. ABrookfield Viscometcr is used to determine theabsolute viscosity of the Elvamide®/formic acidsolution. The spindle and speed should be selectedto give a viscosity highest on the 100 scale. Vis-cosities should be determined at 25°C (77°F).

Melting PointDSC is used to determine the melting point ofElvamide® resins. Applicable test methods are ISO3146 and ASTM D3418 using second melt points.

1

Special Safety PrecautionsSolution PreparationWhen preparing solutions of Elvamide® resins inflammable solvents, precautions must be taken toavoid ignition of flammable vapors by staticelectricity during the transfer of the resin toa dissolving kettle.

All metal parts of the mixing and processingequipment must be grounded. In addition, precau-tions must be taken to avoid discharging the staticcharges which may be generated within the bags ofElvamide® or on the operator during the transferoperation. It is not recommended that Elvamide®

resin be transferred from the bag directly to theblend tank unless the resin has previously been wetdown with water.

Some suggested alternatives for minimizing thehazard are:• Transfer Elvamide® resin from the bag to an

unlined metal container at a location away fromthe flammable vapor area. Ground the containerto the blend tank. Then transfer Elvamide® resinfrom this container to the blend tank using ametal funnel which is grounded to the tank.The free fall distance for the resin should beminimized.

• Mount a grounded metal funnel or trough abovethe blend tank. The cubes of Elvamide® resinshould travel for at least several feet along themetal surface. The point where Elvamide® istransferred from the bag to the funnel or troughshould be well ventilated to reduce the concentra-tion of flammable vapors. With floor-level tankopenings, a grounded metal tray may be used.

After pouring Elvamide® resin from a bag, theoperator should ground himself in a safe locationbefore he approaches the potentially flammableenvironment near the opening of the blend tank.

Operations involving solvents must be adequatelyventilated to limit operator exposure to permissiblelevels. Reference should be made to Section1910.1000 of Title 29, Code of Federal Regula-tions, and to the Threshold Limit Values (TLV)published by the American Conference of Govern-mental Industrial Hygienists for guidance oracceptable concentrations of solvent vapors in theworkplace atmosphere. Protect eyes and skin fromcontact with solvents by using goggles, gloves andother protective equipment.

7

These suggestions are not intended to be all inclu-sive. They should be supplemented by good manu-facturing procedures, prevailing industry standardsand the recommendations of the equipment manu-facturers. In any operation that involves the han-dling of flammable solvents, the utmost care shouldbe taken to avoid static accumulation and otherpossible ignition sources. Open flames should beprohibited, and nonsparking motors and toolsshould be used.

Molding and ExtrusionWhile the molding and extrusion of Elvamide®

resins is ordinarily a safe operation, considerationshould be given to the following:*

(A) Since Elvamide® resins are molded at hightemperatures, the molten resin can inflict severeburns. Furthermore, above the melting point,moisture and other gases may generate pressure inthe cylinder which, if suddenly released, can causethe molten polymer to be violently ejected throughthe nozzle.

To minimize the chance of an accident, the instruc-tions given in this manual should be followedcarefully. Potential hazards must be anticipated andeither eliminated or guarded against by followingestablished procedures—including the use of properprotective equipment and clothing.

Be particularly alert during purging and wheneverthe resin is held in the machine at higher than usualtemperatures or for longer than usual periods oftime—as in a cycle interruption.

In purging, be sure that the high volume (booster)pump is off and that a purge shield is in place.Reduce the injection pressure and “jog” the injec-tion forward button a few times to minimize thepossibility that trapped gas in the cylinder willcause “splattering” of the resin.

If there is any suspicion that gases are being formedin the cylinder, move the purge shield in place,back the nozzle away from the mold, turn off allheats except to the nozzle and the nozzle adaptor,and leave the machine until it cools below themelting point of the resin. Then, with purge shieldstill in place, reheat the cylinder to the minimummold temperature. If jogging the injection or screwrotation buttons does not produce melt flow, a plugexists. In that case, shut off cylinder heats as beforeand follow your established safe practices for

18

removing the nozzle. Always assume that gas maybe trapped behind the nozzle. A face shield andprotective long-sleeve gloves should be used.

In the event molten polymer does contact the skin,cool the affected area immediately with cold wateror an ice pack and get medical attention for thermalburn. Do not attempt to peel the polymer from theskin.

(B) Small amounts of gases and particulate matter(i.e., oligomers) are released during the molding orextrusion of Elvamide® resin. As a general prin-ciple, we recommend adequate ventilation duringthe processing of all plastic resins. However,gaseous products are produced in much smallerquantities than is particulate matter and, as long asthis is kept below the OSHA limit** for nuisancedusts, gases should be well below toxic levels.

Injection molding normally releases substantiallyless volatiles and, therefore, requires less ventila-tion. However, during purging, volatiles release issimilar to that in extrusion.

(C) Granules of Elvamide® resin present a slippinghazard if spilled on the floor. They should be sweptup immediately.

Epoxy ResinsCertain formulations utilize mixtures of Elvamide®

resin and epoxy resins. Epoxy resins are combus-tible and must be kept away from heat and openflame. Avoid prolonged contact with skin andbreathing vapor or spray mist. Keep containerclosed when not in use. Provide adequate ventila-tion when epoxy formulations are being prepared.Before proceeding with any compounding work,consult and follow label directions and handlingprecautions from suppliers of epoxy resins.

PackagingElvamide® resins are supplied as approximately1/8 in colorless transparent cubes or beads. Theyare packaged in 25 kg (55 1b) net moisture barrierpaper bags which maintain extremely low moisturelevels. Pallet loads of 1000 kg (2,200 lb) areunitized.

* Refer also to “Operator Safety Tips” leaflet published by the Societyof Plastics Engineers, Inc., Greenwich, CT 06830.

**Title 29, CFR 1910.1000, Air Contaminants.

Bag ConstructionThe standard 25 kg (55 1b) bag for Elvamide®

resins is pictured in Figure 5. Its multi-plyconstruction, shown schematically in Figure 6,is designed for extra strength, easy opening andexcellent protection against moisture pickup. Gradeidentification, manufacturing lot number and timecode are stenciled on the bottom of the bag, clearlyvisible in palletized loads.

Precautions in HandlingSpecial safety precautions are printed on the backof each bag in English, French, German, Italian,Danish, and Dutch to help operators use Elvamide®

resin safety. The precautions include among others:• Avoid ignition of flammable vapors from such

solvents by static electricity during the transferof the resin to a dissolving kettle.

• Insure that work area is adequately ventilated tolimit operator exposure to solvents to permissiblelevels.

• Protect eyes and skin from contact with solventsby using goggles, gloves, and other protectiveequipment.

Figure 5. Standard 25 kg (55.1 lb) Bag for Elvamide® Resins

FOR POSITION ONLY

1

Figure 6. Bag Construction

Positive seal—heat sealed,not stitched

Four-ply laminated moisturebarrier Kraft/polyethylene/aluminum foil/polyethylene

Two-ply natural Kraft

Kraft outer ply

Also included on the bag is the following statementregarding moisture sensitivity:

Elvamide® resins readily absorb moisture. Theresins, as packaged, have a low moisture contentand the shipping bag protects against further uptakeof moisture. In applications where moisture isdetrimental, care should be exercised, if the bag istorn or opened, to prevent exposure to high humidi-ties. If exposure occurs, the resin should be driedprior to use.

Opened bags should be folded down and tapedsecurely to minimize moisture pickup. Remainingresin should be used as soon as possible.

9

Patent StatusThe following U.S. Patents describe uses ofElvamide®:

U.S. Patent No. Use

3,336,415 Nylon/epoxy adhesive blends3,462,337 Nylon/epoxy adhesive blends3,636,136 Powdering process for nylon3,637,550 Silane-treated nylon adhesives

Regulatory StatusFDA StatusElvamide® 8023R, 8061, and 8063 comply withFDA Regulation 21 CFR 178.2010, “Antioxidantsand/or Stabilizers for Polymers,” for use only atlevels not to exceed 1.5% by weight of polyoxy-methylene homopolymer as provided in paragraph(b) (1) of Regulation 177.2480 entitled “Polyoxy-methylene Homopolymers.” Elvamide® resin is notcleared for other uses at this time.

Results of animal studies with Elvamide® 8061show there was no clinical, nutritional, biochemi-cal, or pathological evidence of toxicity whenanimals were fed at a dietary level of 10%.

Toxic Substances Control ActElvamide® resins have been reported to the Envi-ronmental Protection Agency for inclusion in theInitial Inventory as required by the Toxic Sub-stances Control Act, Title 40 CFR Part 710.

European Inventory of Existing ChemicalSubstances (EINECS)The chemical constituents of Elvamide® resins arelisted on the European Core Inventory (ECOIN) aspublished by the European Economic Communityin 1981.

20

Waste DisposalElvamide® resins may be disposed of by incinera-tion or burial but method must be in compliancewith federal, state, and local regulations.

MSDSMaterial Safety Data Sheets on Elvamide® resinsare available from your DuPont Polymersrepresentative.

ShipmentsElvamide® resins are not regulated by theDepartment of Transportation.

Freight ClassificationsTruck: Plastic materials, synthetic O/T foam,pellets, expanded or sponge granules, NOIBN

NMFC Item: 156200Rail: Plastic materials O/T liquid NOIBNUFC Item: 77810

Export ClassificationSchedule B Number 444.1210Brussels nomenclature-noneIMCO: non-regulated

NOTES

(06/02) Printed in U.S.A.Reorder No.: H-90236

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AutomotiveDuPont Engineering PolymersAutomotive Products950 Stephenson HighwayTroy, MI 48007-7013(313) 583-8000

Asia PacificDuPont Asia Pacific Ltd.P.O. Box TST 98851Tsim Sha TsuiKowloon, Hong Kong852-3-734-5345

CanadaDuPont Canada, Inc.DuPont Engineering PolymersP.O. Box 2200Streetsville, MississaugaOntario, Canada L5M 2H3(905) 821-5953

EuropeDuPont de Nemours Int’l S.A.2, chemin du PavillonP.O. Box 50CH-1218 Le Grand-SaconnexGeneva, SwitzerlandTel.: ##41 22 717 5111Telefax: ##41 22 717 5200

JapanDuPont Kabushiki KaishaArco Tower8-1, Shimomeguro 1-chomeMeguro-ku, Tokyo 153Japan(011) 81-3-5434-6100

MexicoDuPont S.A. de C.V.Homero 206Col. Chapultepec Morales11570 Mexico D.F.(011 525) 722-1456

South AmericaDuPont America do SulAl. Itapecuru, 506Alphaville—CEP: 06454-080Barueri—São Paulo, BrasilTel.: (055-11) 7266.8182Fax: (055-11) 7266.8513Telex: (055-11) 71414 PONT BR

DuPont Argentina S.A.Avda.Mitre y Calle 5(1884) Berazategui-Bs.As.Tel.: (54-1) 319-4484/85/86Fax: (54-1) 319-4417

The data listed here fall within the normal range of properties, but they should not be used to establish specification limits nor used alone as the basisof design. The DuPont Company assumes no obligations or liability for any advice furnished or for any results obtained with respect to this information.All such advice is given and accepted at the buyer’s risk. The disclosure of information herein is not a license to operate under, or a recommendationto infringe, any patent of DuPont or others. It is intended for use by persons having technical skill, at their own discretion and risk. The handling precautioninformation contained herein is given with the understanding that those using it will satisfy themselves that their particular conditions of use present nohealth or safety hazards. DuPont warrants that the use or sale of any material that is described herein and is offered for sale by DuPont does not infringeany patent covering the material itself, but does not warrant against infringement by reason of the use thereof in combination with other materials or inthe operation of any process.

CAUTION: Do not use in medical applications involving permanent implantation in the human body. For other medical applications, see “DuPontMedical Caution Statement,” H-50102.

The DuPont oval logo, DuPont™, The miracles of science™, Zytel®, Nordel®, Teflon® and Elvamide® are trademarks or registered trademarks of DuPont.

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