IPC분류정보
국가/구분 |
United States(US) Patent
등록
|
국제특허분류(IPC7판) |
|
출원번호 |
US-0115144
(2011-05-25)
|
등록번호 |
US-8475884
(2013-07-02)
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발명자
/ 주소 |
|
출원인 / 주소 |
- GM Global Technology Operations LLC
|
대리인 / 주소 |
|
인용정보 |
피인용 횟수 :
13 인용 특허 :
3 |
초록
▼
Filler particles of a moisture-permeable, organic polymeric material are used in a polymeric coating composition, and this composition can be applied to a surface of a molded, fiber-reinforced polymeric material, such as sheet molding compound (SMC), to enable the electrostatic application of a laye
Filler particles of a moisture-permeable, organic polymeric material are used in a polymeric coating composition, and this composition can be applied to a surface of a molded, fiber-reinforced polymeric material, such as sheet molding compound (SMC), to enable the electrostatic application of a layer of a powder primer to the same surface overlying the polymeric coating. And, when the molded SMC is heated to cure the powder primer layer, the out-gassing of moisture from the heated SMC does not result in defects on the surface of the molded SMC.
대표청구항
▼
1. A method of coating a moisture-absorbing, molded sheet molding compound (SMC) article to produce at least two coating layers on a surface of the SMC article so that the coating layers are substantially free of visual defects, the method comprising the following steps in the sequence set forth: ap
1. A method of coating a moisture-absorbing, molded sheet molding compound (SMC) article to produce at least two coating layers on a surface of the SMC article so that the coating layers are substantially free of visual defects, the method comprising the following steps in the sequence set forth: applying a thin film of a polymeric coating composition to the surface of the SMC article to enable the subsequent electrostatic application of a layer of a powder primer, the polymeric coating composition comprising moisture-permeable, organic polymeric filler particles and electrically conductive particles dispersed within a polymeric binder resin precursor material; the filler particles having an average particle size of less than one micron, a melting point above a baking temperature of the polymeric coating composition and the powder primer, and being present in a sufficient amount to provide a cured polymeric coating with a coefficient of linear thermal expansion compatible with that of the SMC article,heating the SMC article to cure the polymeric coating composition and form a solid adherent polymeric coating on the surface of the SMC article,electrostatically applying the layer of powder primer overlying the polymeric coating on the surface of the SMC article; andbaking the SMC article to melt and cure the powder primer without melting the organic polymeric filler particles and form a smooth primer layer on the surface of the SMC article, the composition of the polymeric coating and the amount of organic polymeric filler particles therein being such that moisture driven from the baked SMC article diffuses through the polymeric coating and into the overlying primer layer without forming bubbles or voids in the primer layer. 2. The method of coating as recited in claim 1 wherein the solid adherent polymeric coating on the surface of the SMC article has a thickness in the range of about 20 to 25 μm. 3. The method of coating as recited in claim 1 wherein the solid adherent polymeric coating on the surface of the SMC article has a surface resistivity within a range of about 10,000 to 100,000 ohms per inch. 4. The method of coating as recited in claim 1 wherein the polymeric coating composition comprises, by weight, about 45-55% polymeric binder resin precursor material, 5-10% electrically conductive particles, and 10-15% organic filler particles, and the balance an organic solvent, and the composition being adapted for spray application of the polymeric coating to the SMC article. 5. The method of coating as recited in claim 4 wherein the solvent is xylene. 6. The method of coating as recited in claim 1 wherein the polymeric binder resin precursor material is a polyurethane system. 7. The method of coating as recited in claim 1 wherein the electrically conductive particles are particles of carbon. 8. The method of coating as recited in claim 1 wherein the polymeric coating composition comprises, by weight, about 45-55% polyurethane precursor materials, 5-10% carbon particles, and 10-15% particles of a liquid crystal polymer, and the balance an organic solvent, and the composition being adapted for spray application of the polymeric coating to the SMC article. 9. The method of coating as recited in claim 1 wherein the organic filler particles have a melting point of at least 400° F. 10. The method of coating as recited in claim 1 wherein the filler particles are particles of a liquid crystal polymer having a melting point of at least 400° F. 11. The method of coating as recited in claim 1 wherein the filler particles are particles of a liquid crystal polymer that has been extruded into thin sheets and ground into submicron-sized particles. 12. The method of coating as recited in claim 1 wherein the filler particles are particles of a liquid crystal polymer (LCP) comprising a mixture of 4-hydroxy benzoic acid and 4-hydroxy 2-naphthoic acid. 13. The method of coating as recited in claim 1 wherein the filler particles are particles of a liquid crystal polymer comprising a mixture of, by weight, 27% 4-hydroxy benzoic acid and 73% 4-hydroxy 2-naphthoic acid. 14. The method of coating as recited in claim 1 wherein the filler particles are nanofibers of hemp, flax, rutabaga, wood, or wheat straws and mixtures thereof. 15. The method of coating as recited in claim 1 wherein the filler particles are fibers of hemp, flax, rutabaga, wood, or wheat straws that have a diameter in the range of about 10 to 70 nanometers, and have been chopped to lengths that are less than one micron. 16. The method of coating as recited in claim 1 wherein the polymeric binder resin precursor material is a mixture of a polyester resin and a melamine resin. 17. A method of coating a moisture-absorbing, molded sheet molding compound (SMC) article comprising: applying a thin film of a polymeric coating composition to a surface of the SMC article by spray application, the polymeric coating composition comprising moisture-permeable, organic polymeric filler particles and electrically conductive particles dispersed within a binder resin precursor material,heating the SMC article to polymerize the binder resin precursor material and form a polymeric binder resin without melting the organic polymeric filler particles and form a solid adherent polymeric coating on the surface of the SMC article,electrostatically applying a layer of a powder primer overlying the polymeric coating on the surface of the SMC article; and, thereafterbaking the SMC article to form a smooth solid primer layer on the surface of the SMC article. 18. The method of coating as recited in claim 17 wherein the filler particles have an average particle size of less than one micron, a melting point above a baking temperature of the powder primer, and are present in a sufficient amount to provide the solid adherent polymeric coating with a coefficient of linear thermal expansion compatible with that of the SMC article.
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