Decorative Top-Coat of NexPrene(R) 9075A Thermoplastic Elastomer Improves Product Quality, Appearance, and Weatherability of Automotive Door Seal

Provides easy color match and excellent weathering

MANSFIELD, Texas, Dec. 1 -- Hong Yang Sealings of Guiyang, China, is using new materials and a proprietary process to significantly improve both the quality and weatherability of co-extruded automotive door seals with a colored decorative top-coat.

Conventional designs for such an application include three primary features: (1) a foamed thermoset rubber bulb that contacts the door to provide the functional seal; (2) a back-bone of solid thermoset rubber, extruded over a metal structure, to clamp onto a car's door frame; and (3) a wing with a colored top-coat, which is visible in the interior and serves to cover the edges of headliners, pillars, and carpeting.

NexPrene(R) TPV replaces thermoset rubber or conventional TPV

For the top-coat, instead of a traditional thermoset material, Hong Yang has selected a NexPrene(R) 9075A vulcanized thermoplastic elastomer (TPV) from Solvay Engineered Polymers, Inc. The NexPrene TPV is delivered as a natural that is UV stabilized. Color concentrate is added during production to produce the top-coat in various colors, including "champagne" and "light stone."

"Hong Yang prefers the clean, consistent, easily colored natural that TPVs in the NexPrene 9000 series provide," says Kevin Cai, product development manager at Solvay Engineered Polymers. "Thermoset EPDM is difficult to make in color, and the use of sulfur-based curing agents limits the choice of palette to the darker shades. And regardless of titanium dioxide or pigment concentrations, it doesn't weather well. Conventional phenolic-cured TPV may be better than thermoset EPDM in colorability, but natural grades of these materials still exhibit unacceptable levels of color variation, and they do not weather well when colored in light hues."

Use of NexPrene 9075A improves product quality and weatherability

Mr. Hui Wang, deputy general manager at Hong Yang, points out that "NexPrene TPV allows us to improve our product quality significantly. It enables us to match the top-coat to any color that our OEM customers require. In the past with colored thermoset EPDM as top-coat, the color could change even before the weatherseals were assembled onto the vehicle. With NexPrene(R) TPV as the top-coat, the top-coat will not show noticeable color change even after many years of use, based on our extensive heat-aging and accelerated weathering tests."

Cai adds that the use of NexPrene 9075A TPV also simplifies material handling. "Because our NexPrene 9000 series TPVs do not contain any moisture absorbing components, they do not need to be dried prior to processing, as do conventional, phenolic-cured TPVs."

Proprietary process benefits appearance and performance

Hong Yang has developed its own EPDM/TPV co-extrusion process for applying the TPV top-coat to the door seal. The unique approach results in better adhesion between the color layer and the thermoset backbone than that achieved by other commonly used methods. The NexPrene 9075A material also provides a deeper and more distinct grain than afforded by thermoset rubber or conventional thermoplastic elastomer materials.

Door seals for Chinese automotive market

Hong Yang produces several different door-seal profiles for vehicles sold in China. All of them use NexPrene TPV to provide the colored top-coat. The parts are made in the company's plant in Guiyang, in southern China.

The finished, top-coated profiles are cut to length to fit the door openings of various vehicles, and corner moldings are joined to the profiles by overmolding. The completed loops are shipped to the OEMs to be assembled into the door frames. Hong Yang is the largest independent automotive weatherseal producer in China. The company supplies about 20 to 25% of the weatherseals for the Chinese automotive market.

Experience, resources, and global support

Solvay Engineered Polymers, Inc., is the leading supplier of thermoplastic polyolefin (TPO) materials and technology to the North American automotive industry, with significant sales to European and Asian carmakers. The company is headquartered in Mansfield, Texas, with sales and marketing operations and an Automotive Applications Development Center in Auburn Hills, Michigan. Its manufacturing, distribution, and research and development facilities are located in Mansfield and Grand Prairie, Texas. Additional resources in Shirley, Massachusetts are dedicated to the development and manufacture of the company's line of vulcanized thermoplastic elastomers (TPVs).

The production and engineering operations of Solvay Engineered Polymers are certified to the standards of ISO/TS 16949:2002 for quality systems. More information about its products and capabilities can be found at http://www.solvayengineeredpolymers.com/ .

Solvay Engineered Polymers is a member of the Solvay Group, an international chemical and pharmaceutical group headquartered in Brussels, Belgium. The Solvay Group, whose companies employ about 30,000 people in 50 countries, recorded consolidated sales for 2005 of EUR 8.6 billion, generated by its three sectors: Chemicals, Plastics and Pharmaceuticals. SOLVAY (Euronext: SOLB.BE -- Bloomberg: SOLB.BB -- Reuters: SOLBBt.BR) is listed on the Euronext stock exchange in Brussels. Details are available at http://www.solvay.com/ .

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