A second look at vinyl

Vinyl.

The word conjures up all sorts of negative images: those awful vinyl roofs, cheesy fake woodgrain paneling, searing hot upholstery on summer days. If you're a radical environmentalist, there are even more negative connotations: officially known as polyvinyl chloride (PVC), vinyl is a chlorine-based plastic that can produce toxins when burned, and is supposedly difficult to recycle.

But sit back and relax in a Mercedes-Benz AG or BMW AG model and breathe in the luxurious leather-like smell of their M-B Tex or "Leatherette" interiors. You might come away with an entirely different perception of the material. It can be a very pleasant, low-cost alternative to real leather.

As a Mercedes spokesman aptly says, "There's good vinyl, and there's bad vinyl."

But if you've tried to clean dog hair off your cloth seats recently, or are disgusted by the worn, thread-bare spots on your old minivan's upholstery, you might start to think there is no such thing as bad vinyl. One auto-writer veteran of the dog-hair wars recently got misty-eyed when he talked about how easy it is to clean the original white vinyl upholstery on his restored 1975 Chevrolet Caprice convertible.

Vinyl may have almost disappeared from roofs and seating upholstery on cars, but it certainly hasn't left the automotive scene. It is regarded by most engineers and designers as an extremely durable, weatherable, flexible, low-cost plastic.

It's used for the skin of many instrument panels, as the covering for interior door panels and support pillars, armrests and as the pseudo leather that surrounds the "leather seating surfaces" of many upscale vehicles. Vinyl also is used for the plastic covering on instrument panel wire harnesses, exterior parts such as rub strips, door cladding and other trim. And it's still used for upholstery on some light trucks and vans.

Vinyl began becoming popular in the late 1940s when metal parts coated with simulated wood-grain vinyl replaced real wood veneers on the exterior of some cars for that classic "woody" look. By the 1960s, it took over vehicle interiors. The Geon Co., North America's largest marketer of vinyl compounds, brags about the snazzy red-and-white design it helped create for the interior of the 1962 Ford station wagon. It resembles the two-tone cloth schemes recently developed for some trendy new cars such as the Pontiac Sunfire.

By the 1970s, though, new fabrics started to take over seating surfaces. Consumers like cloth upholstery because it "breathes" and doesn't get hot and sticky in the summer. It also offers many more styling opportunities, says Kendy Ball Kutchek, automotive market manager for Interior Textiles at DuPont Automotive.

Style and taste over the years have changed in favor of fabrics, she says. While the look ofvinyl and chrome were popular in the 1950s, she says today's consumers like a softer, more colorful look that suits fabrics well. If car buyers want a more monochromatic look, they opt for a leather interior, Ms. Ball Kutchek observes.

Unless, of course, they can't afford the extra $1,000 to $1,500 for leather. That's the main reason vinyl still shows up on numerous luxury cars as faux leather.

Fabric materials also have become much more durable and easier to clean over the years. DuPont recently introduced a new nylon fabric called "Xtra Life," which it claims sets new standards in durability. Nevertheless, even fabric supporters admit their material can't compete with good ol' vinyl when it comes to cleaning up melted ice cream, animal hair or petrified peanut butter and jelly sandwiches.

Vinyl proponents argue that many of the material's drawbacks can be overcome with design. Mercedes' seats, for instance, are deeply ribbed to provide better ventilation. The material also is designed to look and feel very much like leather, so it doesn't look cheap. Vinyl upholstery is standard on Mercedes' "entry level" C-class cars as well its diesel-powered E300 and E320 station wagon. It's also available on several BMW models, in addition to cloth or leather. A small number of other luxury vehicles likewise offer vinyl upholstery.

The aesthetics and comfort of cloth vs. vinyl aren't the only issues facing vinyl suppliers and users. Much more serious -- and emotional -- is the environmental aspect. Vinyl is made from petroleum and chlorine. Some powerful environmental groups such as Greenpeace are "trying to ban the chlorine molecule from the periodic chart," as one automotive engineer puts it.

Vinyl advocates and most automotive recycling experts say fears about vinyl's toxicity are unfounded. "In its monomer state it is a possible carcinogen, but not in it's polymer state," says Claudia M. Duranceau, senior research engineer-Worldwide Recycling Planning at Ford Motor Co. "Chlorine and PVC have been getting a bum rap."

Vinyl can -- and is -- being effectively recycled in several different ways, she says. Geon currently is working with the U.S. Council for Automotive Research (USCAR) Vehicle Recycling Partnership on a project to recycle the vinyl coverings of old wiring harnesses. Other suppliers have perfected a process to separate the vinyl skin of instrument panels from their urethane foam backings so both materials can be recovered and reused.

However, only about 3% of all the vinyl produced annually in the U.S. is used in the transportation industry, says Ms. Duranceau.

Even so, scientific evidence often isn't important in the court of public opinion, and vinyl's reputation has been under attack by groups such as Greenpeace in both the U.S. and Europe.

Anti-vinyl activism is particularly strong in Germany, where environmental issues are highly politicized and the "Green" party now is the third most powerful political entity.

Despite their vinyl upholstery offerings in the U.S., German automakers say they are actively eliminating plastics made with chlorine compounds. U.S. automakers so far don't seem to have made any moves in this area.

Meanwhile, vinyl producers are aggressively defending their turf against competitors in the U.S., improving their material and trying to expand into other application areas. New resins and compounds are being developed that will allow vinyl to compete more effectively with thermoplastic olefins (TPOs) and urethane materials.

Vinyl suppliers also are working closely with automakers and vendors -- such as glass producers -- to develop less-costly and more heat-resistant instrument panel designs.

"What we are trying to do is coordinate expectations of the OEMs and Tier One suppliers in providing properties for these applications with new (vinyl) products," says a Geon executive. "We're doing more than just supplying the resin."

One reason "cheap" and "vinyl" often are used in the same sentence has little to do with the material itself. Instead, it usually relates to the fact that the vinyl's embossed texture doesn't match with the texture of adjacent hard plastic components. The result: a mismatched, low-quality appearance.

General Motors Corp.'s Inland Fisher Guide Div., now known as Delphi Interior and Lighting Systems, recently revealed a relatively simple and low-cost method of eliminating this aesthetic problem. It was first used for the instrument panel (IP) assembly on GM's '94 S-Series trucks, and now is being expanded to numerous other interior applications.

Senior Project Engineer Pamela S. Greenwald explains that an IP typically consists of a plastic substrate covered with foam and vinyl and includes components such as the glove box door, ashtray and filler panels. These latter components are made of different materials, such as hard plastics, which are injection-molded.

Matching texture patterns between different plastics and manufacturing processes always has been difficult, Ms. Greenwald says. In most cases a texture for all of the parts is chosen from a "master plaque." This pattern then is transferred to the vinyl via an extrusion/embossing process and to "hard" components where it's etched using injection-molding tools.

Thus initially, all the materials have the exact same texture pattern. But once the vinyl is stretched over the severe angles of the IP's substructure and vacuumformed in place, its texture becomes distorted in several areas while the hardpart textures etched from the master plaque remain unchanged. The result is what Ms. Greenwald calls "a loss of harmony."

A team at Delphi Interior attacked this problem by partitioning the IP into various zones and scribing small circles on the vinyl sheet. After vacuum forming, the circles deformed into elliptical shapes. Engineers found that distortion across the IP ranged from a low of 6% at the glove box door to a hefty 169% at the driver-side fuse box access panel.

This exercise confirmed that a singletexture master plaque could not be used for all components. Instead, the team developed specific textures for each non-vinyl component according to its location, then crafted removable models of each component, placed them in the IP and finally vacuum-formed a vinyl sheet over the whole assembly as if it were entirely vinyl-covered.

The deformed texture pattern of the vinyl over each part was then turned into a specific "texture map" for each hardplastic component, which was etched into the molding tools. The resulting glove-box door texture used in the tooling, for instance, imitates the 6% distortion the engineers found in their research, while the driver-side fuse box door incorporates the 169% distortion. In short, a match between the soft vinyl and hard plastic parts was achieved.

The team wasn't quite done yet, Ms. Greenwald says, because certain random elements in the textures were hard to match. Numerous vinyl swatches were collected for each part, and the patterns that were used had the most generic texture around the periphery of the part, where differences between surrounding vinyl parts can be most apparent.