Safety solutions: For 2002, the innovative use of materials continues to play a significant role in making automobiles safer

Automotive Industries, Nov, 2001 by John Shea

While safety, ease of manufacturing and the environment all remain key concerns for the auto industry, it is safety that drives this year's use of innovative new materials -- especially as they relate to the interior.

Airbags are the focal point There are more of them; they're deploying at variable speeds; they need to stay inflated longer to help with rollover events; and they're increasingly becoming "hidden" by seamless doors lasered behind the instrument panel surface. New resins are being used to ensure that plastic pieces in the I/P and door panels don't shatter and act as projectiles when these airbags deploy New I/P skins are also helping by reducing glare from the windshield, cutting down on visual distraction.

Some of this year's new materials highlights include the following:

1. INSTRUMENT PANEL

1A. JCI's Long-Glass Fiber Polypropylene. Johnson Controls made the instrument panel on the 2002 Mercedes C-Class program in Europe stronger and safer with its long-glass fiber polypropylene (LGFPP) resin. The material was developed to ensure that once the hidden airbag deploys, there won't be plastic parts or particulate matter breaking off from the I/P and flying toward the occupants. Glass gives the I/P skin its strength. However, a traditional problem in using the material is that its strength is diminished when the strands of glass are crushed and made smaller during the injection molding process. JCI preserves the length of the glass strands (up to 5 mm and longer) by directly compounding the material internally. it is achieved by blending the glass strands into a powder and then extruding the material in the shape of a plastic log that is transferred to a fast-compression mold. End result The material has an impact strength of 61 mG/mm2, which is at least twice as strong as lower grades of plastics. JC I seeks to use the resin in a North American application.

1B. Visteon Laminate Injection Molding (VLIM). Visteon's VLIM material is able to simultaneously create a soft and hard surface through one injection mold. In the manufacturing process, a pre-formed laminate skin is inserted into a horizontal molding press before the injection cycle. In designing the mold, Visteon put the soft surface in the location where the occupant may hit their head during a collision impact. The material includes a foam-backed piece of TPO, TPU or PVC skin (depending on the program requirements). Visteon says the one-mold process is more cost effective and the material itself is 100 percent recyclable. VLIM makes its debut on the 2002 Mazda Tribute.

1C. Visteon Low-Gloss Polypropylene. Drivers often have to contend with the glare off the top of the I/P reflected in the windshield. Visteon helps to reduce this glare with its low-gloss polypropylene plastic material. Molded into the top of the I/P, the material helps achieve a claimed industry-low two to three percent gloss level versus the traditional four to 10 percent level The material is featured on the 2002 Ford Escape.

2. ACTIVE RESTRAINTS

Delphi Sealed Head Airhag. Delphi is able to extend the inflation time of an airbag tc seven seconds through its sealed head airbag. The innovation here is a proprietary sealant compound that is applied to the surface of the bag. When the bag is deployed, the sealant forces the air to escape the bag through pinholes in the fabric itself instead of the seams. Delphi says the product will debut on a 2002 European model to be announced by the customer.

3. DOOR PANEL

JCI's Eco-Cor material. Featured on the 2002 Chrysler Sebring convertible, JCI's EcoCor is an environmentally friendly door panel substrate made from a 50-50 blend of natural and polypropylene fibers, including kenaf from Texas and industrial hemp from Canada. JCI's compression mold application produces a low-cost door panel and adheres the foil cover in one step. Beyond its lighter weight and improved acoustics, Eco-Cor offers a key safety benefit: The material's longer fibers (20 m to three inches) create additional strength for the door panel. The material may collapse or break during a side-impact collision -- but it won't shard, providing additional protection for occupants.

4. B-PILLAR

Solvay Sequel 2321 Engineered Polyolefin. Solvay Engineered Polymers' Sequel 2321 is used on the B-pillar covers for the 2002 Ford Taurus and Mercury Sable. The impact-resistant material, made from an advanced TPO, doesn't splinter when the side airbag deploys during a collision event, further protecting front-seat occupants. Sequel 2321 replaces a competing polyolefin alloy and can be used on both covers for the B-pillar, simplifying the manufacturing process. The B-pillars are produced by Lear Corp.

5. FLOOR

Venture's Sandwiform material. Venture Industries' Sandwiform, featured on the 2002 Renault Avantime (cargo load floor) and Nissan Primera, offers recyclability and ease of manufacturing. Sandwiform is a composite material consisting of a "honeycombed" cellular core positioned between two thermoplastic skins reinforced with glass and polypropylene. Through thermocompression, the production is a one-step process that takes no more than 60 seconds. Simultaneous exposure to heat and compression turns the "sandwich" material into a thermoplastic composite that is strong and lightweight.