New coatings technologies combine to improve SMC

Citation

(2006), "New coatings technologies combine to improve SMC", Anti-Corrosion Methods and Materials, Vol. 53 No. 5. https://doi.org/10.1108/acmm.2006.12853eab.003

New coatings technologies combine to improve SMC

New coatings technologies combine to improve SMC

Keywords: Automotive industry, Coatings, Chemical technology

An OEM-led research collaboration is developing new interrelated technologies that allow sheet molding composite (SMC) parts to be powder- primed without sacrificing the quality of the SMC class A surface. Key technology participants include General Motors Research and Development, Tier One supplier Meridian Automotive Systems, resin supplier AOC and coatings supplier Red Spot Paint & Varnish.

Powder primers help improve the workplace and environment by reducing volatile organic compound (VOC) emissions and overspray waste. OEM facilities want to apply powder primers to steel and SMC body parts that are sent side-by-side through E- coat and paint- coating cycles.

When powder primed, conventional SMC develops a leather-like surface appearance during the powder-primer high-temperature cure cycle. At General Motors R&D, the issue came under the full technical scrutiny of Hamid Kia, principal researcher and world-renowned automotive SMC authority.

Jeff Robbins, Director of R&D for SMC supplier Meridian Automotive Systems, says, “GM research concluded that the failure mechanism was a combination of air and moisture that is released when a common low- profile additive (LPA) is used. After defining the problem and determining the thresholds, Hamid Kia challenged companies in the automotive-supplier value chain to work together toward a synergistic solution.”

To evaluate different SMCs, Meridian Automotive provided tooling and molding equipment that are used in regular production. Full-size parts molded with different SMCs were sent to GM assembly plants for standard powder-primer application and cure. These production-scale trials validated laboratory data and ensured that the solution could be implemented without changing process or equipment parameters.

AOC's role was to develop a special, low-moisture-content formulation, which incorporated new LPAs in a synergistic fashion. The new additives continue to provide the traditional LPA function of contributing to reduced shrinkage and improved surface finish.

“All our new low-moisture-content SMCs are based on high-performance Atryl brand TCA resins,” points out Ed Kleese, Technical Services Manager for AOC. “SMCs made with Atryl TCA are bringing increased toughness, reduced surface waviness and superior class A finishes to a host of car and truck applications.”

To achieve even greater surface quality in powder-primed parts, Hamid Kia encouraged automotive plastics-coating manufacturer Red Spot to develop a new SMC primer. The Red Spot primer is applied by Meridian before SMC parts are shipped to the GM facility. The Red Spot primer is conductive so that the electrostatically charged solid particles of the OEM powder coating process will be attracted to the SMC part surface.

“Red Spot research led by Dr Keith Cannon results in a conductive powder- capable SMC primer with a unique patent-pending technology, says Marilyn Bara, new Product Marketing Director for Red Spot. “In essence, the new low-permeability coating technology forms a layer that significantly controls the release of moisture from the SMC into the powder primer. Combining our proprietary primer with low-moisture composite takes the surface quality of powder-primed SMC to extraordinary levels.”

Headquartered in Allen Park, Mich., Meridian Automotive Systems, Inc., is a leading supplier of technologically advanced components, modules and systems to automobile and truck manufacturers. For more information, contact Jeffrey R. Robbins, Director R&D, Meridian Automotive Systems, at Meridian facilities in Allen Park. Tel: 313/253.4036; e-mail: jrobbins@meri dianautosystems.com. The company web site is www.meridianautosystems.com.