VTC TPE GROUPTECHNICAL AND PRODUCTEXPLANATION

TPE DefinitionThermoplastic Elastomers (TPEs), have also been described as Thermoplastic Rubbers (TPRs).TPEs are polymer based materials with similar properties at their service temperature to vulcanised rubber, but can be processed and reprocessed at elevated temperatures like a thermoplastic.

TPE DefinitionTPEs have also been defined by the classical elastomer description as materials which after the application of strain recover to approx their original shape.

Using these definitions thus excludes from the TPE class, hard materials, and it is accepted materials harder than around 80 Shore A no longer have elastomeric properties.

TPE COMPARISONS WITH THERMOSET RUBBER

Advantages:Lower Part WeightFaster Cycle TimeWaste EliminatedProcessing Energy ReducedPerfect Parts Right First Time (no trimming)Greater Design FlexibilityParts 100% Recyclable at End of Life

TPE COMPARISONS WITH THERMOSET RUBBERDisadvantages:Limited Heat and Fuel ResistanceLower Strength PropertiesPossibly Higher Material CostEstablished Specification Resistance

HARDNESS OF POLYMERIC MATERIALS

0 10 20 30 40 50 60 70 80 90

SHORE A

40 50 60 70 80

SHORE D

VTC TPE GRADES

THERMOSET RUBBER

PE

FLEXIBLE PVC

PP

TPU

EVA

ABS

INCREASING HARDNESS

TPE COMPARISONS WITH PLASTICSAdvantages:Improved Low Temperature ResistanceImproved Impact ResistanceReduced NoiseTactile, Soft Touch FeelHard / Soft Design Possibilities

TPE COMPARISONS WITH PLASTICSDisadvantages:Possibly Higher Material CostLower Strength PropertiesProcessing Inexperience / Confidence

TPE PROCESSING ECONOMICSTHERMOPLASTIC ELASTOMER FABRICATIONMATERIALSTPESHAPINGFINAL PRODUCTTHERMOSET RUBBER FABRICATIONMATERIALSGUM RUBBERFILLERSOILS ADDITIVES, ETCMIXINGSHAPINGVULCANIZE FINAL PRODUCT NEED TO R/CSCRAPSCRAPSCRAP

TPE Compositions TPEs are either polymers or more commonly compounds based on polymer(s) and additives.

TPEs which are often used as polymers without compounding are: Urethane Thermoplastic Elastomers (TPU),(eg Estane) Copolyester Thermoplastic Elastomers (TPC),(eg Hytrel) Polyamide Thermoplastic Elastomers (TPA),(eg Pebax)

TPE CompositionsTPEs which are commonly compounded materials are: Olefinic Thermoplastic Elastomers, (TPO) TPOs are blends of elastomer such as EPDM and plastic such as PP or PE Styrenic Thermoplastic Elastomers, (TPS) TPSs are blends of elastomeric polymers such as SBS or SEBS and plastic such as PS or PP Thermoplastic elastomer vulcanisates, (TPV) TPVs are dynamically vulcanised elastomer blends such as EPDM blended with plastic such as PP

Performance vs CostSBSTPVSEBSReactor MTPOCost Per Tonne PerformanceVitaprene+Dryflex

Fields of Application

Only Western Europe

Source: Christian Thomas/RAPRA

Field of Application

TPE-S

TPE-O

TPE-V

TPE-U

TPE-E

TPE-A

Total

Automobile Industry

5

72

8

10

1

2

98

Wire/Cable

-

4

1

7

2

0

14

Shoes

35

1

0

5

2

1

44

Polymer Modifications

30

2,5

2,5

1

0,3

0,2

36,5

Tubes

2

1,5

2

2,5

1,3

1

10,3

Frequent Moulding

Parts in TPE

3

6,5

7

9

1,5

1

28

Bitumen Modifications

40

0

0

0

0

0

40

Field of Construction

3

0

2,5

0,5

0

0

6

Glue/Coating Material

20

0

0

12,5

0,2

-

32,8

Film/Foil

0,5

1

0,2

4

0,3

0

6

Miscellaneous (incl. Medicin)

6,5

1,4

0,7

1

3,4

0,4

13,4

Total

145

89,9

23,9

52,5

12

5,7

329

TPE CompositionsTPOs These are normally mechanical blends (without cross-linking), of EPDM rubber and a polyolefin plastic such as PP and / or PE. Additives such as heat stabilisers (Irganox), process aids (stearates or amides), fillers (talcs or calcium carbonate), softeners (paraffinic oil), colours (carbon black, titanium dioxide); are normally added to modify properties such as flexibility, mouldability & extrudability.

TPE CompositionsTPOs Advantages: tend to have very low densities (around 0.88), consistent quality, harder grades more popular, mid to low price. Disadvantages: low hardness grades difficult, tend to have poor flow properties at lower hardness, poor recovery properties at moderate and especially elevated temperatures, cost / performance profile not very good. Applications: Harder grades used for auto bumpers, airbag covers.

TPE CompositionsTPSs There exists some confusion regarding TPSs as SBS and SEBS polymer manufacturers tend to promote their pure polymers as thermoplastic elastomers. However it is extremely rare that these polymers are used to fabricate finished parts without compounding.

TPE CompositionsTPSs SBS (Styrene Butadiene Styrene) block copolymers are available in different S to B ratios (higher S giving stiffer products), different molecular weights (higher MWt giving poorer flow but better recovery properties), and clear or oil extended (oil extension tending to give easier processing, better dispersion compounds). Typical compounds use PS (polystyrene) as a flow / hardness / process enhancing plastic additive. SBS has inherently poor weathering resistance and this can be improved by additions of other polymers such as EPDM rubber, EVA (ethylene vinyl acetate), and SEBS

POLYSTYRENE DOMAINELASTOMER MIDSEGMENT TPS BLOCK COPOLYMER -- PHASE STRUCTURE

TPE CompositionsTPSs SBS based compounds; Other additives such as heat and light stabilisers, process aids, fillers (talcs or calcium carbonate), softeners (naphthenic and paraffinic oils), colours are normally added to modify processing and end use properties. The following shows an overview of typical property changes brought about by compounding additives. These changes are only general but common to most types of polymer based TPEs

Compounding Additive Effects

TPE CompositionsTPSs SBS based compounds; Advantages: large hardness spread possible (35A to 60D), low to mid price Disadvantages: poor weathering resistance, poor recovery properties at elevated temperatures Applications: rubbery articles for moderate temperature and weathering resistance

TPE CompositionsTPSs SEBS (Styrene Ethylene Butylene Styrene) block copolymers like SBS are available in different Styrene, and Molecular Weight levels. Higher MWt grades give poorer flow but improved recovery properties. Major advantage of SEBS grades over SBS based grades are their excellent weathering and elevated temperature recovery properties. Typical compounds use PP (polypropylene) as the plastic additive.

TPE CompositionsTPSs SEBS based compounds; Due to the very high molecular weight of SEBS it is a very extendable base polymer, and can be highly extended with fillers and in particular oil to produce the widest range of hardness of any TPE family (0A to 60D)

TPE CompositionsTPSs SEBS based compounds; Advantages: can have very low densities (0.89), extremely wide hardness range with jelly like (0A) materials possible. Excellent weathering and good recovery properties up to 70 to 100 Deg C. Fast moulding cycles Disadvantages; relatively high price base polymer, can be very shear sensitive, can be difficult to obtain good dispersion

TPE CompositionsTPVs These are blends, normally of EPDM and PP, which during mixing, and under the correct high shear conditions; the elastomer is chemically cross-linked in very small domains and finely distributed in the PP. This process called dynamic vulcanisation, enables improved recovery properties at elevated temperatures, and better fluid resistance compared to the TPS compounds.

TPE CompositionsTPVs As the elastomer portion of the TPV is chemically crosslinked, enough plastic carrier must be used to enable the compound to be thermoplastically processed. Although oils, and fillers can be added, this elastomer crosslinking tends to make low hardness grades (below say 40 A) difficult

THERMOSET RUBBER - PHASE STRUCTURE

SxSSx S S S i SS xSSRUBBER CROSS-LINKED WITH CHEMICAL LINKAGES

MORPHOLOGY OF THERMOPLASTIC VULCANIZATES

RUBBER DOMAINS CROSS-LINKED WITH CHEMICAL LINKAGESVULCANIZED ELASTOMERPLASTIC MATRIX 1 MICRON

TPE CompositionsTPVs Advantages: Excellent weathering resistance, and good recovery properties up to around 100 to 120 Deg C. Feel of vulcanised rubber. Very fast moulding cycles (can be demoulded quite hot) Disadvantages: relatively expensive manufacturing process, with smaller mixing window than TPS grades. Low hardness grades difficult. Low strength at lower hardnesss

TPE CompositionsOther styles of TPEs TPZs PVC based compounds in blends with high plastisicer levels and Nitrile Rubber are promoted by some companies as TPEs. These compounds can be low in price, relatively high in strength, but tend to be of high density, unstable melt during processing, Halogen containing, poor recovery properties at elevated temperatures, can suffer from plasticiser migration, PVC odour and have a Plastic feel.

GENERAL COMPARATIVE PROPERTIES OF TPE TYPES

PROPERTYTPSSBSTPSSEBSTPVTPOTPUTPC(ETHER-ESTER)TPA(AMIDE)TPZFLEXIBLE PVCHARDNESSRANGE15A to 60D1A to 60D35A to 60D60A to 60D60A to 85D90A to 70D60A to 70D40A to 40DSPECIFIC GRAVITY RANGE0.9 to 1.30.89 to 1.30.9 to 1.10.86 to 1.01.05 to 1.251.13 to 1.251.01 to 1.21.2 to 1.35SERVICE TEMP. RANGE C- 60 to + 60- 60 to + 100- 60 to + 120- 60 to + 60- 60 to + 110- 60 to + 11060 to + 130-30 to + 70COMP. SETRESISTANCEAT ROOM TEMPGOOD(10 to 30%)GOOD(10 to 20%)GOOD(15 to 25%)FAIR(20 to 30%)FAIRFAIRPOORFAIR to GOODCOMP. SETRESISTANCEAT 70CPOOR( > 70%)FAIR to GOOD( > 35%)FAIR to GOOD( > 30%)POOR( > 70%)FAIR FAIRPOORPOOR to GOODSTRENGTHFAIR to GOODFAIR toGOODPOOR to FAIRFAIR to GOODGOOD to EXCELLENTGOODGOODGOODWEATHERING RESISTANCEPOORGOOD to EXCELLENTEXCELLENTEXCELLENTGOODGOOD to EXCELLENTGOODGOOD to EXCELLENTOIL & FUELRESISTANCEPOORPOOR to FAIRFAIR POORGOOD toEXCELLENTGOODPOOR to GOODFAIR to GOOD

VTC TPE GROUP PRODUCTSDryflex grades designed for injection mouldingVitaprene grades designed for extruded productsDryflex grades originally developed in Elastoteknik, and were predominantly TPS based grades. Produced now in Elastoteknik or VTPVitaprene grades originally developed in VTP, and were hybrid blends of several polymers. Produced now in VTP or ElastoteknikMediprene grades developed for the Medical industry only and produced in VTC France

VTC TPE GROUP PRODUCTSCompounding of Dryflex and Vitaprene The acknowledged most efficient way to mix TPE compounds is by continuous twin screw extrusion compounding. These compounders are fed by particulate polymers and additives by automatic loss in weight feeders. Another more labour intensive method is by internal mixer (Banbury mixer). This route can be more flexible, more easily fine tuned, and can feed baled polymers. Once compounded the polymer melt is extruded through a die plate fitted with high speed cutters to produce pelletised compound of typically 3mm size.

VTC TPE GROUP PRODUCTSCompounding of Dryflex and Vitaprene VTP have both internal mixers and twin screw compounders, each on a production scale, and in the laboratory, where test samples of 1 to 50 Kg can be produced. Elastoteknik have twin screw compounders, again in production and pilot plant sizes. Both sites are geared to react quickly to sampling customers with new compound developments, and continual evaluation of new compounding materials.

VTC TPE GROUP PRODUCTSProperty Identification TPE materials are distinguished by their physical properties and also by their processing characteristics. Development and testing facilities at VTP and Elastoteknik are excellent and can produce the fingerprint of all our TPE (and any competitors) compounds by evaluating chemical, rheological, and physical properties.

VTC TPE GROUP PRODUCTSProperty Identification Elastoteknik and VTP Laboratories are equipped with single screw extruders to monitor and develop correct extrudability and die swell. Both sites have injection moulding equipment to produce test plaques, and monitor mouldability, with Elastoteknik having 2K (Two Shot), overmoulding capabilities and bond strength testing equipment.

VTC TPE GROUP PRODUCTSProperty Identification Typical Testing: DSC, TGA, FTIR, Ash Content, Solvent Extraction, Specific Gravity all these can identify base polymer(s), oils, filler types, and proportions. Melt Flow Rate, Capillary Rheometry, Spiral Mould Flow all these can indicate the flowability of a compound, during extrusion or moulding. Hardness, Modulus, Elongation at Break, Tensile Strength, Tear Strength these physical properties show the flexibility and toughness of the fabricated compound. Compression Set, Tension Set, Stress Relaxation all indicate how well a material resists and recovers from deformation at different temperatures.

VTC TPE GROUP PRODUCTSProperty Identification Typical Testing: Abrasion Resistance, Flex testing how a product performs in a wearing environment. Oil and Fluid Immersion testing -- indicate how a product swells / shrinks and changes physical properties in contact with fluids at different temperatures. UV Weathering and Ozone exposure quickly show if a material will give an adequate outdoor service life. Vertical and Horizontal Burning -- characterise a materials flammability. Colourmeter testing -- identifies a products colour by a three dimensional grid number, and not just by the naked eye. Heat Ageing and Low temperature brittleness -- shows the materials long term resistance in service to temperature extremes. Fogging -- identifies if a material is suitable for in car or under glass applications.

TPE DevelopmentsThe compound database we have, of over 3000 TPE compounds, includes grades which comply with certain national and automotive standards. Such standards include the BSI and RAL glazing gasket requirements, Underwriters Laboratory flammability testing, and numerous European and global automotive specifications.

TPE DevelopmentsPriority Developments currently under way: Improved Oil and Fuel Resistance TPE grades, coupled with improved heat resistance, ideally for under bonnet products

To compete property wise and commercially with thermoset (NBR) rubber

Fuel ResistanceVolume Swell % 70h @ 23 Deg C Petrol BS7070

TPE DevelopmentsUse of Automotive Post Consumer Waste in automotive exterior trim applications Utilising Tyre Crumb at levels between 25 and 50% by weight of the total compound, and Reprocessed Polypropylene at 15 to 60%, TPE compounds, with good physical properties for exterior products, with extremely high levels of PCW can be produced at VTC

TPE DevelopmentsUse of Automotive Post Consumer Waste The tyre crumb used is available from a number of approved sources in Europe, and has a particle size around 300 microns (0.300 mm Dia.) The material is purchased to agreed tolerances on properties such as sieve analysis, ash content, volatiles The product has a controlled and accepted level of restricted substances (eg. Heavy Metals)

TPE DevelopmentsUse of Automotive Post Consumer Waste The Reprocessed Polypropylene again is available from several European sources, is supplied as a specification controlled raw material, with MFR, Strength, Impact, Melt Temperature, and Ash Content controlled, and again meeting requirements for restricted substances

TPE DevelopmentsUse of Automotive Post Consumer Waste Adjusting levels of Rubber based Tyre Crumb and Polypropylene, and addition of other compounding additives such as additional elastomer and plastic, filler, softener, process aid, stabiliser; gives VTC technologists the tools to design ranges of compounds with a wide potential property spectrum

TPE DevelopmentsUse of Automotive Post Consumer Waste Typical formulation examples: 80 Shore A 40 Shore D 50 Shore DTyre Crumb ~ 50% ~ 40% ~ 25%Repro PP ~ 15% ~ 35% ~ 55%Misc. Ingds. ~ 35% ~ 25% ~ 20%

TPE DevelopmentsUse of Automotive Post Consumer Waste All PCW compounds are produced to written in stone recipes, using consistent controlled feedstocks, with all ingredients used within a +/- 1% weighment tolerance. Compounds are mixed using identical run to run mixing cycles, and product tested to customers agreed Quality Plan which can include MFR, Hardness, S.G. and Stress / Strain parameters. Despatched lots are accompanied with a Certificate of Analysis

TPE DevelopmentsUse of Automotive Post Consumer Waste Advantages: Environmentally / ELV logical Faster moulding cycles Potential Weight Saving Tailor Made compounds Potential Noise Reduction Improved Impact Resistance, especially at lower temps.

TPE DevelopmentsUse of Automotive Post Consumer Waste Disadvantages: Odour of thermoset rubber Product finish can reflect level of crumb (Advantage ?)

TPE DevelopmentsTPV / Hybrid Compounds VTP has developed initial series of TPV compounds, the XL range, to compete with current market TPV grades, but also to offer property processing advantages such as Hopper Ready (No Drying) Easier to colour Supply of colour matched compound Tailor Made compounds to offer optimum price / performance fit

TPE DevelopmentsTPV / Hybrid Compounds Good opportunity in Auto Extruded Seals, for glazing, belt line / body seals Under bonnet seals, deflectors, shields, grommets, plugs, damper mounts, boots / bellows Oil Resistance enhancement required

TPE DevelopmentsTPV / Hybrid Compounds Testing of VTC XL grades to Ford WSD-M2D 378-A1/-A2, 379-A1/-A2, 380-A1/-A2, and 381-A1/-A3 specifications for TPV materials, has revealed compliance results; except in oil resistance and change in heat aged stress/strain properties to original. (Recent Fogging tests carried out at Elastoteknik show all XL compounds tested gave comfortable compliance)