Catalyst-containing polymer coatings formed by chemical grafting
The present invention relates to coating compositions and methods of forming catalyst-containing coatings on substrates for catalytic heater devices. The coatings are formed by a chemical grafting method, which chemically bonds the coating (and catalysts contained therein) to the substrate. The resulting coatings have high temperature resistance and inhibit or prevent catalyst migration to the substrate, thereby maintaining catalytic activity and desired temperatures over prolonged use.
1 . A method of forming a catalyst-containing polymer coating on a catalytic heater substrate, the method comprising:
providing a liquid coating composition comprising:
a washcoat base comprising a catalyst material, wherein the catalyst material comprises a hexachloroplatinate salt, and
a chemical grafting admixture comprising one or more monomers and/or prepolymers, one or more grafting initiators, and one or more coupling agents dispersed or dissolved in a solvent system; and
applying the liquid coating composition to a surface of the substrate and forming the catalyst-containing polymer coating thereon.
2 . The method of claim 1 , wherein forming the catalyst-containing polymer coating on the substrate comprises:
reacting the substrate surface with the one or more grafting initiators to form free radical active sites on the substrate surface;
chemically bonding the one or more monomers and/or prepolymers and/or coupling agents to the active sites on the substrate surface; and
polymerizing the monomers and/or prepolymers to form a polymer matrix comprising the catalyst material secured therein.
3 . The method of claim 1 , wherein the one or more monomers and/or prepolymers comprise vinyl, epoxy, and/or acrylic monomers.
4 . The method of claim 1 , wherein the one or more monomers and/or prepolymers comprise hydroxyl, chloro, carboxyl, or glycidyl groups.
5 . The method of claim 1 , wherein the one or more graft initiators comprise one or more metallic salts selected from the group consisting of silver nitrate, silver perchlorate, ferrous ammonium sulfate, silver acetate, copper acetate, and combinations thereof.
6 . The method of claim 1 , wherein the one or more coupling agents comprises one or more titanate salts comprising two or more amino groups.
7 . The method of claim 1 , wherein the admixture further comprises a grafting regenerator.
8 . The method of claim 7 , wherein the grafting regenerator comprises a peroxide compound.
9 . The method of claim 1 , wherein the substrate comprises ceramic fibers.
10 . The method of claim 1 , wherein the solvent system comprises methanol and/or glycerol.