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5/1/2000 | 13 MINUTE READ

Engineering Thermoplastics

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Expect to see numerous entries in automotive engineering thermoplastics at NPE, including a totally new amorphous thermoplastic that is said to provide a breakthrough in color and gloss retention outdoors without painting. Besides exterior body panels, new automotive materials for under-hood, interior, structural, and mechanical parts like gears will also be plentiful.

After automotive, the next biggest category of new materials is aimed at electrical/electronic, appliance, and business-machine applications. Look for new conductive resins, tougher glass-reinforced compounds, and flame-retardant grades without halogen (some also without phosphorus).

There will be plenty to choose among new TPOs, TPVs, TPUs, and TPEs of all types and hardnesses. Soft-touch overmolding grades will be one particular emphasis. In addition, specialty compounds containing high filler levels for metal-like weight or thermal conductivity will also make their debut.

New shot at body panels

Samples of the first new plastic in more than 10 years to be launched by GE Plastics will appear at the show. Because of its reported ability to retain high gloss and depth of color outdoors without paint, GE is hoping for a new breakthrough in auto body panels. For now, GE will only say that its still-developmental "W4 Polymer" is a brand-new amorphous thermoplastic resin and not an alloy. It boasts inherent weatherability without additives, combined with very high gloss (greater than 100 at 60°), good heat resistance (HDT around 135 F at 264 psi), and toughness similar to that of polycarbonate. It also shows good scratch resistance and chemical resistance to gasoline.

After 12 months of exposure in Arizona and Florida, all W4 samples reportedly retain better than 95% gloss. GE also says unpainted W4 polymer stays glossy after more than 25,000 hr of xenon-arc accelerated weathering, versus 15,000 hr for most uv-stabilized plastics. Thus W4 reportedly meets auto companies' requirement for 10-year gloss retention without the need for painting. Automotive fascia will likely be the first application when the resin becomes fully commercial in 2002.

Although injection molding grades will follow later, the resin's stiff flow is not currently suited to molding large critical-appearance parts. For now, GE is concentrating on extrusion applications. It envisions using thermoformed thin sheets of W4 as inserts that are backed up with another unpigmented polymer (e.g., Xenoy polycarbonate/polyester alloy) in an injection mold. At an expected cost of over $2/lb, this in-mold decorating process is seen as an economical means of providing a self-colored part with a weatherable surface.

Another candidate for unpainted body panels is an addition to the Surlyn Reflection Series of "supergloss" ionomer/nylon-copolymer alloys from DuPont Engineering Polymers. Higher flow allows it to be molded at lower temperatures, DuPont says.

GE will also introduce a new, high-heat, conductive grade of Noryl GTX nylon/PPO alloy for injection molded body panels that will be electrostatically painted. Like GE's first conductive Noryl GTX, it contains special carbon microfibers for conductivity. But this new developmental grade has higher flow and is expected to withstand the e-coat cure cycle (195 C or 383 F for 30 min) to permit on-line painting. It is slated to go commercial this summer.

GE also plans to introduce new vibration-damping technology for Noryl and Noryl GTX that could be applied to body panels. It uses new resin and additive technology that absorbs vibration without the use of fillers that also increase stiffness. Besides automotive, this technology has potential uses in printers and medical equipment.

Among other new appearance-grade automotive materials to look for at the show, LG Chemical of Korea will show its weatherable ASA, which is used in unpainted side-mirror housings.

Automotive TPOs & TPVs

Huntsman Corp. is launching AP7310-HS, a TPO for auto interiors that is said to provide unmatched head-impact protection. One of the first products Huntsman has made with the Mitsui Hypol process, this is a 10-MI, heat-stable grade with tensile strength of 3100 psi, flex modulus of 145,000 psi, and Gardner Impact of 310 in.-lb.

Equistar Chemicals, LP, is launching new high-stiffness TPOs designed to replace metal in auto exteriors.

ATC Inc. is introducing ATX 832 (30 MI) and ATX 39 (6-8 MI), two highly scratch-resistant, low-gloss TPOs that offer stiffness and toughness for partially padded, unpainted instrument panels.

M.A. Hanna Engineered Materials will show off its first line of TPV compounds, based on technology from its Italian joint-venture partner So.F.teR. These Forprene TPVs have Shore hardnesses from 35A to 60D. Grades are tailored for injection molding, extrusion, blow molding and calendering. They include heat-stabilized, copper-stabilized, uv-stabilized, flame-retardant, very high-flow, and anti-fogging grades.

The Milastomer line of TPVs from Mitsui Chemicals of Japan is being introduced here by Calsak Corp. Available grades range from soft like vulcanized rubber to semi-hard grades like RIM urethane. They are aimed at automotive, appliances, sporting goods, and building materials.

Merquinsa North America, Inc., Duncanville, Texas, is showing its new Pearlcoat line of polyester-based TPUs of 85-95 Shore A. They are designed for powder slush-molding to replace PVC in interior automotive skins.

More automotive contenders

There's also lots new to see at NPE in automotive materials for under-hood and structural uses. For example, three new conductive resins for fuel systems are being featured by DuPont Engineering Polymers. One is Zytel FE8209, a nylon 66 with a proprietary toughener that compensates for the effects of carbon-black loading. The result is Izod impact strength comparable to standard nylon, DuPont claims. Also new are two conductive Delrin acetals for fuel systems: One is much stiffer than non-conductive grades, and the other has more than double the Izod impact strength of other conductive acetals. By showtime, DuPont plans to be ready to start sampling a new acetal with better resistance to hot diesel fuel--e.g., 2000 hr at 90 C (194 F).

DuPont is also unveiling two new series of Zytel HTN high-temperature nylons, 53G and 54G, aimed at structural components for automotive powertrain chassis and interior uses such as pedal boxes, dashboard frames, and seat parts. They are said to mold very easily using hot water rather than oil for mold-temperature control. Initial grades contain 50% glass. They reportedly combine high strength, stiffness, and toughness at high temperatures, and properties are said to change little from dry to wet conditions.

A new Delrin acetal grade from DuPont is designed for higher load gears for small automotive electric motors, such as window lifts. It is said to achieve uniform crystallization on all surfaces of the gear teeth and has shown excellent lifetime performance in actual gear tests.

Six new grades of GE's Valox PBT and Noryl GTX for automotive connectors and other under-hood parts are expected to outperform existing PBTs and nylons in USCAR thermal-aging tests. New additive formulations are said to improve the temperature and humidity performance of Valox "K" resins and the long-term heat aging of Noryl GTX "W" grades to allow users to meet and exceed USCAR IV 10-year warranty standards.

Honeywell Engineered Applications & Solutions (formerly AlliedSignal Plastics) is introducing new grades of Capron nylon 6 for gas-assist injection molding. SEGM35 H1 (15% glass, 25% mineral) is for high-fill applications such as vehicle mirror housings, roof racks, door handles, and bezels. Capron HM with 50% or 63% glass are high-modulus grades that reportedly offer better flow, smoother surfaces, and less tool wear than competitive grades.

Focus on aesthetics

GE Plastics' new marketing emphasis on improving the aesthetics of plastics products is evident in its new Visualfx resin portfolio for designers of automotive, appliance, and consumer- electronic products. It applies a variety of special-effects coloring approaches to many of GE's engineering thermoplastics. They include "Light Diffusion" translucent effects--such as "frost" and "ice" for Lexan polycarbonate; "Energy" intense glow-like effects for Cycolac ABS, Cycoloy PC/ABS, and PC; "Intrigue" color-shifting technology that produces a 3D illusion as color changes with viewing angle. The latter is available for PC and new transparent Noryl PPO grades. In addition, GE offers new speckle, marble and metallic colors and has expanded its Magix metal-sparkle family beyond ABS to include PC/ABS and select grades of Noryl.

Two brand-new visual effects will be featured at the show. "Pearlescence" colors for Lexan show a fluid, swirly appearance, with high depth of color. "Diamond" colors uses special glass flakes to create a shimmering look. The first Diamond grades are based on translucent ABS or PC. Opaque and various "shimmer" colors will follow.

In addition, GE's new Noryl PN275 is a plateable PPO alloy with higher heat resistance than in the past. Its HDT is 275 F at 66 psi, compared with 235 F in the past. Heat resistance plus NSF approval for potable-water applications are said to make it a contender for brass replacement in plumbing parts. It also has potential in auto wheel covers.

Lots for E/E & appliances

A new PTFE-free grade of DuPont's Delrin acetal is said to extend the life of gears in office machines by 15%. Also new is a general-purpose grade of Delrin that is said to flow better than the company's high-impact 100 Series while also offering higher impact strength than the low-viscosity 500 Series g-p resins.

JLM Engineered Resins is introducing Polyform homopolymer acetal from Europe. It is being made in a new plant in Greece that belongs to Polyform Ltd., a U.K. joint venture of JLM and Alabama-based Science International, which contributed new polymerization technology. JLM is the exclusive distributor in the Americas. Initial grades include g-p,low-wear/low-friction, uv-stabilized, high-stiffness, toughened, and extrusion grades.

A new flame-retardant nylon 66 for circuit-board assemblies, coil forms, and other e/e components reportedly reduces part costs by increasing molding productivity. DuPont's Zytel FR50 HF is available in a brominated version and a non-halogen, phosphate-based grade. Its melt viscosity is about 40% below that of regular Zytel FR50. It also has increased thermal stability.

Lati USA, Mt. Pleasant, S.C., is introducing Latamid 66 HZ G/25-V0 HF, the company's first flame-retardant nylon 66 that is both halogen- and phosphorous-free. It is said to offer a UL 94V-0 rating at 0.1 mm and GWT 960 C at 1 mm. It also boasts a CTI of 400 v.

Also new from DuPont are several developmental conductive grades of its Zytel DMX, a modified nylon 66 said to maintain very consistent properties in wet or dry conditions. The new versions contain carbon fibers and/or particles to achieve shielding values from 25 to 75 db, reportedly meeting the requirements of most electronic devices such as computers, hard drives, and cell phones.

Radici Plastics USA, Rochester Hills, Mich., is introducing the Meramid industrial-grade nylon 6 and 66 products.

LG Chemicals is bringing in from Korea new halogen-free FR PBTs. The Lutrel GN series (glass reinforced) has UL 94V-0 ratings down to 1/32 in. (0.8 mm) thickness, glow-wire temperature of 960 C, and CTI values of 600 v. Also new is Lupox SV-120, an HMW PBT that meets the strict requirements for optical-fiber tubing.

DuPont is launching Zenite 6244 liquid-crystal polymer (LCP), which reportedly matches the shrinkage of PPS in long multi-pin connectors and other e/e parts. It therefore can run on existing tools and eliminates the flash associated with PPS. In one case, it was shown to cut molding cycles by up to 75%.

Two new additions to the lower cost Zenite 3000 LCP series from DuPont boast very low warpage. Grades 3224 (20% mineral) and 3226 (30% mineral, 10% glass) have been proven in a number of connector molds where standard glass-filled reportedly LCPs failed to meet to requirements for flatness and coplanarity of mating sockets and receptacles.

Lati USA will showcase Later T compounds based on Shell's Corterra PTT polyester. Glass-reinforced grades reportedly combine the rigidity, strength, and heat resistance of PET with the lower processing temperature of PBT.

In amorphous engineering resins, GE Plastics has brought out Noryl Eco-Flo. Designed to meet European and Asian "eco-label" requirements, these UL94-rated FR grades contain no halogens or heavy metals. What's new is higher flow without changing mechanical or thermal properties, plus UL certification to use up to 50% regrind vs. only 25% for previous grades.

GE also has just come out with its first Noryl Material Handling grade, MH230, for pallets. GE says it is the first to receive a UL classification for fire-resistant pallets, and it also satisfies National Fire Protection Association (NFPA) standards for indoor use and storage of plastic pallets.

GE will also show off its new transparent Noryl resins. First launched in a sheet-extrusion grade for thermoformed packaging, they are now offered in injection molding versions for housewares, consumer electronics, telecommunications, and business machines. The TN series comes in four grades with HDTs of 230-310 F at 66 psi. High-impact and FDA grades are included. They offer 86% light transmittance and HDTs up to 310 F at 66 psi.

In keeping with the vogue for see-through computer housings, LG Chemical will show TR557 transparent ABS. Tough and easy flowing, it can be molded or extruded into toys, cosmetic cases, and appliance housings.

Nylons made in Israel will be presented by Nilit Ltd. (represented here by J.A.Z. Associates). New additions to its Polynil line include P-50FI, a fast-cycling nylon 66 designed specifically for small, multicavity injection molds. Also new are Polynil P-230PI and P-230C, lubricated nylon 66 resins for non-stick production of blown film.

Lots of TPOs, TPEs, TPUs

A full range of new thermoplastic elastomers will arrive at the show. For example, Equistar will unveil a new medical-grade TPO that is said be more heat-resistant than other TPOs so that it can withstand autoclaving.

A new line of SEBS-based TPEs designed to replace silicone in disposable medical devices is being unveiled by AlphaGary Corp., Leominster, Mass. Evoprene Super G materials are said to provide excellent ozone and uv resistance, with low compression set, high heat resistance, and excellent tensile strength. Grades are available for both molding and extrusion.

Multibase is featuring Multiprene, a new low-compression-set TPE.

FlexGel TPEs, a new family based on a metallocene polyolefin elastomer, will be introduced by Poly Chem Alloy, Inc. They come in hardnesses from 0 Shore A to 45D. The line includes two extrusion coating compounds (4007 and 4397) of 50 to 65 Shore A for use as a coating over PE foam or wire and cable insulation.

Among several new products from GLS Corp. are super-soft versaflex CL 2000X TPE alloys designed for overmolding onto substrates such as PP. These water-clear, non-oily, non-tacky TPEs come as soft as 3 Shore A.

Versalloy high-temperature, oil- and chemical-resistant TPEs for injection and extrusion are being launched by GLS. Positioned to compete with TPVs that have good chemical resistance and low compression set at high temperatures, these specialized TPEs of 45-65A hardness are said to be well suited to applications such as grips for power tools and garden equipment. The series includes an FDA grade (55A).

A newly expanded portfolio of faster cycling TPUs from BFGoodrich Specialty Plastics includes Estane grades with shore hardness from 70A to 85D and Estaloc glass-reinforced grades with flexural moduli from 50,000 to over 1 million psi. Inherently compatible, Estaloc substrates and Estane soft-touch overmoldings are said to provide a wide range of design options.

Highly filled specialties

You'll see evidence at NPE of the growing interest in high-density filled compounds for vibration-damping automotive components, medical x-ray shields, and high-inertia parts such as flywheels, seatbelt locking mechanisms, and weights or ballast for sporting goods, machinery, and instrumentation. They even have potential in lead-free bullets that protect the environment.

LNP Engineering Plastics will be featuring its newly expanded line of high-specific-gravity compounds, which now covers 14 resin families and specific gravities of 1.7 to 10. The Thermocomp HSG family now includes TP elastomers and extrudable grades, plateable, and FDA grades.

M.A. Hanna is joining the competition with its new line of high-density, non-toxic, metal-filled compounds. Ecomass and Polymetal compounds consist of 80% or more powdered tungsten dispersed in a thermoplastic and are designed to replace lead and other high-gravity metallic materials. There are currently eight compounds ranging in specific gravity from 6 to 11. Typical prices are $10-15/lb. A radiation-shielding formulation said to provide efficiency comparable to lead, but with a 35% lower density. A 96%-tungsten/nylon 12 compound is being used to make bullets for the U.S. Army.

Hanna has also come out with a series of thermally conductive filled compounds for molded heat sinks, shrouds, thermostats, heat exchangers, and radiant-heating coils used in computers, appliances, cell phones, and business machines. Called Thermal-Tech, they consist of 25-30% loadings of proprietary powdered fillers and fibers in any of a wide range of engineering thermoplastics. They are priced in the range of $20-25/lb.