New dimensions

Much like they have always been, current developments in engineering resin applications are a product of market forces, long-term investment in research and feedback from customers.

“Our people in the field are continuously taking the pulse of the industry, listening to what customers want in terms of material performance,” says Greg Adams, general manager, global marketing for GE Plastics. “From this interaction we come up with trends and predictions as to where the market is going.”

The demand for more visually appealing, aesthetic grades of engineering resins, which began in earnest a few years ago, has intensified, reports Adams. While OEMs and processors are looking to create brand identity with new color schemes, they are also seeking to reduce costs associated with painting.

Geloy XTW provides three to five times the color and gloss retention of traditional ASAs, according to GE tests. The product, which is part of the company’s X GEN resin portfolio launched at last year’s NPE, is generating much interest among OEMs and suppliers, says Adams. The pre-colored resin is designed to better withstand the severe weathering effects of UV exposure and, as well, extend the long-term performance characteristics of products in the most extreme outdoor applications, such as automotive and siding.

“With an automotive mirror shell that is painted white, which is 30% of the market, if you scratch the surface, you see black,” says Adams, noting that there are still more mirror shells being painted than made using molded-in color. “There’s room for growth in this area. In addition to the quality issue with paint, more suppliers are talking about eliminating the investment in paint lines, which is substantial.”

With most of the easier plastic-for-metal substitutions already made, engineers are looking to conquer more rugged applications. A case in point is one of the world’s first plastic washing machine pulleys made from a glass-reinforced grade of DuPont’s Zytel nylon. Most washing machines use an aluminum pulley to spin the machine’s inner drum. Merloni UK Ltd., the largest domestic appliances manufacturer in Great Britain, worked with injection molder Rolinx Plastics Company in the development of the plastic pulley. Tests showed pulleys made from Zytel offered the best combination of mechanical performance properties and cost effectiveness.

In another metal replacement application, Pennsylvania-based injection molder Viking Plastics replaced aluminum-threaded block connectors for an air conditioning unit with a new line of snap connectors made of DSM Engineering Plastics’ Stanyl high heat polyamide. Stanyl PA46 met the high-heat requirements demanded of an under-hood application; as well as possessing good chemical resistance, excellent long-term heat aging performance and good creep resistance.

Global electronics OEM Philips Electronics is using a newly developed grade of Dow Chemical’s PC/ABS blend, Emerge, in the manufacture of a flat panel TV. The resin, Emerge 7560, is the highest flow PC/ABS blend on the market, according to Dow. Additionally, the ignition-resistant grade does not contain chlorine or bromine. The resin’s high-flow properties, combined with high-heat and high-impact performance typical of PC/ABS blends, make it suitable for television enclosures, and in particular flat panel applications.

“With the increasing popularity of flat panel applications, some TV leaders are seeking an alternative polymer choice for TV cabinet materials,” says Karen Shepard Jackson, marketing and sales manager for Emerge resins at Dow. She reports that the 7560 grade is ideal for molding the thinner, more intricate and lower-weight housings and parts used in the next generation of large TV cabinet designs.

In its flat panel application, Phillips utilized Dow’s Promatch Self-Coloring service, which enabled it to bring the product to market quicker. Dow says more molders are using self-coloring to create customized aesthetics and react to new trends and styles. The material is also available as a pre-colored resin.

INROADS IN AUTOMOTIVE EXTERIORS

Bayer has introduced a new paintable nylon/ABS blend for exterior auto body applications that eliminates the need for a conductive primer. Triax TP 3161 provides higher heat distortion resistance (356 F to 392 F) than other competitive thermoplastics used for body panel applications. This ensures that parts are able to withstand the high temperatures encountered in drying ovens during e-coating. This means parts can be mounted directly on the steel framed body-in-white and pass through the entire process “online”, avoiding special handling.

“With Triax TP 3161 there is no longer any need to use a conductive primer,” says Thomas Malek, bodywork applications manager at Bayer Polymers. “This enables cost savings in materials, technical complexity, labor and logistics.”

Malek also notes that the Triax grade is about 50% stiffer than comparable PPO/PA blends, which in turn allows engineers to design parts with thinner walls without additional reinforcements. Weight savings can be as much as 50% compared with a steel panel. Additionally, Triax has a lower coefficient of linear expansion than PPO/PA blends, which eliminates the need to design in wide gaps between neighboring parts.

DaimlerChrysler recently received the Grand Award for the roof module on its new Smart Roadster at the Society of Plastic Engineer’s annual International Innovation Awards. The module incorporates a three-layer, co-extruded Lexan SLX polycarbonate film supplied by GE Plastics. The film is highly weather-resistant and produces a Class A molded-in color surface without the need for clear coating. The film can be applied over a variety of thermoplastic and thermoset substrates through an in-mold decoration process. When back-molded with a PC/PBT resin and subjected to various OEM paint specification tests, Lexan SLX film in most cases performed better than or equal to exterior paint systems, according to the company.

A German manufacturer of utility vehicles recently incorporated thermoplastic body panels into one of its multi-purpose, specialty vehicles. The cab of Multicar’s FUMO vehicle consists of a steel frame clad with panels thermoformed from BASF Corp.’s Luran S (ASA). The company, which was used to working in metal, was looking for a way to reduce manufacturing costs of its low volume vehicles.

“When selecting the right plastic, we had to find a material that would best match the steel frame in terms of manufacturing and thermal expansion,” explains Matthias Cramer, Multicar’s chief designer.

Luran S is a styrene-based polymer that contains acrylic rubber, which imparts high impact strength. The cab’s roof, back, B-pillar trim and front panel are vacuum formed and bonded to the steel frame with a special adhesive.

Today’s higher performing engineering resins are making new dimensions the norm.