TPEs add functions to gain markets

The days of double-digit growth in thermoplastic elastomers (TPEs) may have passed, but significant niche opportunities remain for economic, bondable grades and two suppliers are making their pitch.

Branching out from its flagship thermoplastic melt-processible rubber, Alcryn, resin supplier Advanced Polymer Alloys (APA) has introduced a DuraGrip TPE line, which ranges from high-performance grades to economical versions to lines that bond to engineering thermoplastics (ETP), including nylon, PC, ABS, and PC/ABS.

For its part, GLS Corp. is targeting consumer products, including toys and infant goods, with its new soft-touch Versaflex OM 9-802CL that, in addition to being clear, is said to adhere to PC, ABS, PC/ABS, and COPE.

Jeff Senich, business development manager for APA, says his company has seen some initial interest in the DuraGrip material for automotive trim parts where the TPE adds a soft touch as well as filled, nylon wire harnesses, where it functions as a gasket.

In the future, power tools also hold opportunity for grippable handles. Senich says in some instances, due to a relative dearth of capable materials, new customers had formerly sourced TPEs that, given their component''s cost and mechanical properties, were overpriced and over-engineered with previous selections running in the $6-$7/lb range.

Outside automotive, APA sees some applications in packaging, including synthetic wine corks and cap liners for carbonated soft drinks and other beverages that currently use an EVA or other barrier material as cap liners to stop carbon dioxide egress and oxygen ingress.

GLS''s Versaflex features a Shore A hardness of 40, requires no drying, and is easily colored due to the virgin material''s clarity. The resin can be precolored or loaded with 1-5% color concentrates.

For Versaflex as well as DuraGrip, adhesion to other materials, especially ETPs, is a key selling point going forward. APA''s Senich says the primary difficulty in bonding TPEs to ETP substrates, which is usually done in a multicomponent injection molding scenario, is the disparate processing temperatures, especially for nylon. APA has closed the gap somewhat with the melt temperature of Duragrip''s ETP bondable grade in the 370-420°F range, which is important as TPEs look to new markets.

"Many of the easiest TPE applications have already been achieved," Senich says. "It''s going to take a lot of application of technology and a very close alliance of the material suppliers and customers to cooperatively engineer our way through challenges going forward." Advanced Polymer Alloys, Wilmington, DE, USA; +1 302-478-8989; www.apainfo.com. GLS Corp., McHenry, IL, USA; +1 815-385-8500; www.glscorp.com

Resins/Compounds Lose those sparks

The improved Durethane C polyurethanes include an expanded range of electrostatic dissipation properties that eliminate electrostatic discharges in electronic machines. The material is available as a machinable solid thermoset polyurethane or as foam. Typically the electrostatic properties of polyurethane are adjusted by adding carbon fibers or metal powder and fiber, or by coating the surface of the part with conductive chemicals. The supplier took a different route, introducing conductive additives into the urethane precursor and thus altering the molecular form of the polyurethane. According to the supplier, the resulting material is less sensitive to changes in temperature and humidity than are traditional semiconductive materials. Durethane C serves two principal uses. One is to dissipate tribocharge (electricity generated from friction) in equipment such as printers, copiers, and other machinery with paper pathways. The other is to supply a specific charge density in applications that require charge-density control on a surface. For example, the developer roller in a laser printer uses an electrostatic charge to adjust the amount of the toner particles on the surface of the print element.

Durethane C conductive polyurethanes provide a volume resistivity in solid urethane from E5 to E10 ohm-cm at a hardness of 5 Shore A-70 Shore D, and in open- or closed-cell foams from E7 to E10 ohm-cm at a hardness of 1A-90A. Additives constitute 0.01-10% of the product by weight. The material is available in sheets, rollers, bars, rods, and tubes. MPC, Cranston, RI, USA; +1 401-946-4400; www.mearthane.com

Intricate shapes are no problem for these grades

Two Borecene Compact linear-medium-density polyethylene (PE) copolymer grades provide enhanced flow properties to fill complicated roto molds and maintain good wall thickness. These metallocene catalyst-based materials, which use the manufacturer''s patented technology to eliminate pellet grinding, offer improved economics, improve surface appearance, and enhance handling for technical products such as those used in the automotive industry. They have a density range of 0.926-0.949 g/cc.

Grade black RM8346-9004 replaces Borecene Compact grades RM8346 and RM8346RC. This material is intended for applications such as diesel fuel tanks where barrier performance needs to be superior to standard linear-low-density PE and crosslinked resins. The manufacturer says these metallocene materials have lower metling points for an equivalent density and higher stiffness than traditional materials. They also offer shorter cycle times due to their lower sintering temperature.

Natural colored Borecene Compact RM8346-1000 was developed to provide extra-high UV resistance. It replaces RM8343RC. It can also be used for diesel fuel tanks as well as natural colored products or those that include dry-color pigments for toys, boats, and marine applications. Borealis, Kongens Lyngby, Denmark; +45 45 966000; www.borealisgroup.com

Food packaging gets all wrapped up

A styrenic copolymer for microwavable food packaging applications, Dylark FG2500, combines low-temperature toughness with high-temperature rigidity for superior freezer-to-microwave performance. It also targets restaurant take-away containers and food serviceware. The material''s toughness reduces the danger of leakage or spillage when hot food is removed from the microwave or brought home in a car, says Debra van Holst, global packaging director at the manufacturer. The FDA-compliant material can be manufactured in pigmented, clear, or foamed containers. It can be processed on existing polystyrene or polyester equipment at faster cycle times and provide enhanced sealability, she says. It also offers good printability and higher material yields. Nova Chemicals Corp., Pittsburgh, PA, USA; +1 412-490-4292; www.novachemicals.com

Resins/compoundsMaterial delivers cost-effective performance in hoses, ducts

An acrylic co-elastomer provides the right mix of properties and the right price, says this manufacturer, between high- and mid-range elastomers for the automotive industry. ACE can effectively replace high-VA-content ethylene vinyl acetate, chlorinated polyethylene, and epichlorhydrin rubber (ECO) as well as in some cases acrylate rubber in intermediate-fluid and temperature-resistance applications such as turbocharger hoses (cold side), transmission oil cooler hoses, molded air ducts, and fuel hose covers. The intermediate temperature resistance makes ACE ideally suited for applications where operational performance is required in the range of -40 to 140°C. It also provides resistance to oil and other automotive fluids as well as aging at elevated temperatures.

The producer says this halogen-free material can be processed on conventional equipment and is usually crosslinked using standard diamine curatives or peroxide. Because of its low specific gravity, ACE can offer approximately 15% weight savings in final parts compared to ECO. DuPont, Wilmington, DE, USA; +1 302-774-1000; www.dupont.com

Glass with a bit of plastic

That may be an accurate description for the new long-fiber concentrate from engineering thermoplastics compounder RTP Company. Concentrates are added at a molding machine''s hopper to neat plastic; processors can potentially save on material costs, and the higher the glass-fiber loading, the less concentrate required. The new RTP concentrate includes 80% glass-fiber loading by weight, which the compounder claims is the highest long-fiber loading available.

Concentrates can be difficult to process if the matrix material/reinforcement blend is not well-managed by a compounder, but RTP says it has optimized the concentrate''s ability to blend into neat material, so that even materials with varying melt flow rates are able to be blended together. RTP Co., Winona, MI, USA; +1 507-454-6900; www.rtpcompany.com

Designer looks to acrylic/PVC sheet for inspiration

An award-winning industrial designer says thermoforming saves his time-and his customers'' money. Design teams often work with tight budgets, giving them little leeway in the product-development cycle for experimentation and adjustment, especially when it involves costly delays due to redesign. One designer, Claude Gidman, trumpets the benefits of thermoforming Kydex-brand acrylic/PVC alloy sheet supplied by Kleerdex Co. to avoid time-consuming prototyping steps such as producing patterns from CAD or drawings.

His business thermoforms the sheet into complex shapes that house, support, protect, or decorate products. He also uses it like stamped or pressed sheet metal for covers and enclosures- wthout tooling or painting.

Gidman, founder of Gidman Design Associates Ltd. (Toronto), says engineers and designers can greatly improve the properties and performance of a product by refining key features, including its shape. "At Gidman Design, we find that the more we experiment with shape, the greater the strength and quality that can be obtained without increasing cost," he says. "Failing to take advantage of creative shaping opportunities can result in product coverings which can be bland, less effective functionally, and less appealing in the marketing process."

The sheet is fire-rated, resistant to impact and a variety of chemicals, and comes in a range of standard and custom colors, sizes, thicknesses, and surface textures. It also meets or surpasses code requirements for many applications, such as those in most transportation interiors, Gidman says.

When properly designed, tooled, and formed, parts fabricated of Kydex sheet don''t thin out at the edges. Product developers can thus use the material in a relatively low-cost process like thermoforming to improve and test a design and undertake pilot production before transferring it to a more expensive process like injection molding for commercial manufacture.

Gidman Design has been able to make tooling, adequate for 10 to 20 parts and sometimes more, in its design studio and model shop and repeatedly modify it with simple wood and body-filler materials to develop the shapes needed for testing. From prototyping it''s a simple step to thermoform parts of the sheet in quantities of 50, 100, or into the thousands. For higher volumes it is necessary to have epoxy or reinforced tooling made.

The sheet can be thermoformed at temperatures between 325ºF and 390°F (162-198°C), and forms deep draws with low forces at the higher end of that temperature range. Kleerdex Company, Bloomsburg, PA, USA; +1-570-387-6997; www.kydex.com

Higher processing outputs for homopolymer

Polypropylene Malaysia has debuted the Propelinas SHAC320 series of homopolymer PP grades for tape, yarn, fiber, film, and injection molding applications. Based on feedback from processors, the supplier says the new grades give 10-15% higher processing outputs, especially for tape and yarn applications. For BOPP film production, production speed can be increased to 400 m/min, while clarity is enhanced by about 10%. Product strength for injection molded products, meanwhile, is increased by 5% compared with existing grades. The grades are manufactured using fourth-generation Super High Activity Catalyst 320 from Dow Chemical and available through Malaysian International Trading Corp. Malaysian International Trading Corp., Kuala Lumpur, Malaysia; +60-3- 2331-6373; www.petronas.com.my

Resins/compoundsHuntsman pushes PUR for pultrusion

Officials at plastics and chemcials supplier Huntsman (Auburn Hills, MI) have detailed what Hunstman claims are the first practical guidelines for pultruding urethane composites. Pultrusion typically uses unsaturated polyester resin. Work on pultrusion of PUR has been ongoing for some six years but Huntsman reckons its guide may help make PUR a commercially viable alternative to polyester.

Pultrusion, a process similar to extrusion but with parts pulled through a die and down a production line, typically makes use of thermoset resins to form parts for applications such as ladders, utility poles, or other building and contruction applications.

Huntsman''s RIMline can, says Huntsman, help pultrusion processors increase line speeds and improve secondary finishing with less waste compared to traditional pultrusion plastics. The PUR grades'' properties also may allow for parts redesign which could save material.

Michael Connolly, product manager urethane composites at Huntsman, notes that urethanes'' wetting efficiency leads to low void content, low shrinkage, and strong adhesion to glass-fiber reinforcement.

According to the supplier, some pultrusion processors already using PUR have achieved double the transverse strength, higher impact resistance, and better-tolerance parts in urethane pultrusions relative to comparable components in traditional thermosets. Huntsman markets its pultrusion-grade RIMLine for use in applications including window lineals and architectural moldings, sporting goods, and structural shapes. Huntsman Polyurethanes, Auburn Hills, MI, USA; +1 248-322-7300; www.huntsman.com/pu

New nylon-based TPE boasts high flexibility

The Nycoplastic polyamide copolymer thermoplastic elastomers (TPE) offer a flexural modulus as low as 12,000 psi coupled with good impact resistance even at low temperatures, says supplier Nycoa. Grades are available with or without plasticizers and with custom color and additive packages. According to Nycoa, these self-lubricating materials show minimal loss of properties when regrind is introduced and prove more cost-effective than competing high performance TPEs. Nylon Corp. of America (Nycoa) Inc., Manchester, NH, USA; +1 803-233-7187; www.nycoa.com

SEMIFINISHED PRODUCTSStock shapes help improve sensitivity of marine devices

As world oil consumption continues to accelerate, offshore exploration and ocean surveying have become increasingly essential for production companies to keep pace with demand. Ertacetal stock shapes (rods, plates, and tubes made of acetal copolymer) for machining are helping seismic acquisition company Sercel Europe to construct oil filler blocks for seismic streamers.

The stock shapes are deliverable in complex geometries with high chemical resistance and low specific weight. The result is a strong, flexible streamer able to map the seabed more quickly and with greater sensitivity. Quadrant Engineering Plastic Products, Tielt, Belgium; +32 51 423598; www.quadrantplastics.com

ADDITIVESCompatibilizer pairs PLA with recycled PP

Working toward the eventual goal of incorporating plant-based polylactic acid (PLA) resins with recycled polypropylene (PP) and polystyrene (PS) into 2006 products, Japanese consumer electronics manufacturer Sharp Corp. (Osaka) has developed a compatibilizer technology that allows the disparate materials to blend together in a homogenous fashion.

Three patents are pending for the technology that mixes in a new compatibilizer with PLA and reclaimed PP or PS from recycled consumer electronics products so that the PLA forms an ultrafine dispersion and enhances the physical properties of the blended material. Without the compatibilizer, gaps form at the boundary surfaces of the PLA and PP, which weakens impact and thermal resistance.

With this new technology, Sharp believes that as the price gap between plant-based plastics and petroleum- and natural gas-based resins closes, the inclusion of bioresins and recycled polymers in products will reach 30% by 2010. Sharp Corp., Osaka, Japan; +81 6 6621 1272; www.sharp-world.com

MASTERBATCHESNon-halogenated FR grades prove environmentally friendly

CESA-flam flame retardant (FR) masterbatches offer an environmentally friendly alternative to conventional halogenated grades. They have been developed for engineering materials including nylon (both neat and glass-filled), polyester, and thermoplastic urethanes. Based on proprietary phosphorous compounds instead of halogens, these masterbatches achieve the FR property through intumescence. When exposed to fire, the material foams and crosslinks, forming a stable char on the surface.

This ceramic-like protective layer provides a heat-insulating effect, reduces oxygen access, prevents dripping of molten polymer, and reduces smoke density and toxic emissions. The masterbatches have high-temperature stability, processing ease, and good colorability. Clariant, Masterbatches Division, Winchester, VA; +1 401-438-4080; www.clariant.masterbatches.com