Presentation on theme: "TECHNICAL AND PRODUCT EXPLANATION"— Presentation transcript:
1 TECHNICAL AND PRODUCT EXPLANATION VTC TPE GROUPTECHNICAL AND PRODUCTEXPLANATION
2 TPE DefinitionThermoplastic Elastomers (TPE’s), have also been described as Thermoplastic Rubbers (TPR’s).TPE’s 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.
3 TPE DefinitionTPE’s 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.
4 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
5 TPE COMPARISONS WITH THERMOSET RUBBER Disadvantages:Limited Heat and Fuel ResistanceLower Strength PropertiesPossibly Higher Material CostEstablished Specification Resistance
10 TPE CompositionsTPE’s are either polymers or more commonly compounds based on polymer(s) and additives.TPE’s 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”)
11 TPE Compositions TPE’s which are commonly compounded materials are: Olefinic Thermoplastic Elastomers, (TPO)TPO’s are blends of elastomer such as EPDM and plastic such as PP or PEStyrenic Thermoplastic Elastomers, (TPS)TPS’s are blends of elastomeric polymers such as SBS or SEBS and plastic such as PS or PPThermoplastic elastomer vulcanisates, (TPV)TPV’s are dynamically vulcanised elastomer blends such as EPDM blended with plastic such as PP
12 Performance vs Cost TPV Vitaprene+Dryflex SEBS Performance TPO Reactor MSBSCost Per Tonne
14 TPE Compositions TPO’s 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.
15 TPE Compositions TPO’s 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.
16 TPE Compositions TPS’s There exists some confusion regarding TPS’s 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.
17 TPE Compositions TPS’s 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
19 TPE Compositions TPS’s 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 TPE’s
22 TPE Compositions TPS’s SBS based compounds; Advantages: large hardness spread possible (35A to 60D), low to mid priceDisadvantages: poor weathering resistance, poor recovery properties at elevated temperaturesApplications: rubbery articles for moderate temperature and weathering resistance
23 TPE Compositions TPS’s 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.
24 TPE Compositions TPS’s 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)
25 TPE Compositions TPS’s 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 cyclesDisadvantages; relatively high price base polymer, can be very shear sensitive, can be difficult to obtain good dispersion
26 TPE Compositions TPV’s 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.
27 TPE Compositions TPV’s 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
28 THERMOSET RUBBER - PHASE STRUCTURE SxSSSSS xSSxSS iRUBBER CROSS-LINKED WITH CHEMICAL LINKAGES
29 MORPHOLOGY OF THERMOPLASTIC VULCANIZATES VULCANIZED ELASTOMERPLASTIC MATRIX1 MICRONRUBBER DOMAINS CROSS-LINKED WITH CHEMICAL LINKAGES
30 TPE Compositions TPV’s 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 hardness’s
31 TPE Compositions Other styles of “TPE’s” TPZ’s PVC based compounds in blends with high plastisicer levels and Nitrile Rubber are promoted by some companies as TPE’s. 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.
32 SPECIFIC GRAVITY RANGE WEATHERING RESISTANCE GENERAL COMPARATIVE PROPERTIES OF TPE TYPESPROPERTYTPSSBSSEBSTPVTPOTPUTPC(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 + 11060 to + 130-30 to + 70COMP. SETRESISTANCEAT ROOM TEMPGOOD(10 to 30%)(10 to 20%)(15 to 25%)FAIR(20 to 30%)POORFAIR to GOODAT 70C( > 70%)( > 35%)( > 30%)POOR to GOODSTRENGTHFAIR toPOOR to FAIRGOOD to EXCELLENTWEATHERING RESISTANCEEXCELLENTOIL & FUELGOOD to
33 VTC TPE GROUP PRODUCTS Dryflex grades designed for injection moulding Vitaprene 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
34 VTC TPE GROUP PRODUCTS Compounding 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.
36 VTC TPE GROUP PRODUCTS Compounding 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.
37 VTC TPE GROUP PRODUCTS Property 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.
38 VTC TPE GROUP PRODUCTS Property 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.
39 VTC TPE GROUP PRODUCTS Property 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.
40 VTC TPE GROUP PRODUCTS Property 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.
41 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.
42 TPE Developments Priority Developments currently under way: Improved Oil and Fuel Resistance TPE grades, coupled with improved heat resistance, ideally for under bonnet productsTo compete property wise and commercially with thermoset (NBR) rubber
43 Fuel Resistance Volume Swell % 70h @ 23 Deg C Petrol BS7070
44 TPE Developments Use of Automotive Post Consumer Waste in automotive exterior trim applicationsUtilising 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
45 TPE Developments Use 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, volatilesThe product has a controlled and accepted level of “restricted substances” (eg. Heavy Metals)
46 TPE Developments Use 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”
47 TPE Developments Use 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
48 TPE Developments Use of Automotive Post Consumer Waste Typical formulation examples:80 Shore A Shore D Shore DTyre Crumb ~ 50% ~ 40% ~ 25%Repro PP ~ 15% ~ 35% ~ 55%Misc. Ingds. ~ 35% ~ 25% ~ 20%
49 TPE Developments Use 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 customer’s agreed Quality Plan which can include MFR, Hardness, S.G. and Stress / Strain parameters. Despatched lots are accompanied with a Certificate of Analysis
50 TPE Developments Use of Automotive Post Consumer Waste Advantages: Environmentally / ELV logicalFaster moulding cyclesPotential Weight SavingTailor Made compoundsPotential Noise ReductionImproved Impact Resistance, especially at lower temps.
51 TPE Developments Use of Automotive Post Consumer Waste Disadvantages: Odour of thermoset rubberProduct finish can reflect level of crumb (Advantage ?)
52 TPE Developments TPV / 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 asHopper Ready (No Drying)Easier to colourSupply of colour matched compoundTailor Made compounds to offer optimum price / performance fit
53 TPE Developments TPV / Hybrid Compounds Good opportunity in Auto Extruded Seals, for glazing, belt line / body sealsUnder bonnet seals, deflectors, shields, grommets, plugs, damper mounts, boots / bellowsOil Resistance enhancement required
54 TPE Developments TPV / 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)
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