Morton International, Inc.

Morton Thiokol Inc.

Frederick L Cummings

Glenn D Correll

Unsaturated polyester resin coating powder composition consisting essentially of at least one unsaturated polyester resin; at least one copolymerizable second resin; and an initiator which comprises 1,1'-di(t-butylperoxy)-3,3,5-trimethylcylcohexane (AE), or which contains a small proportion of a fast initiator and a relatively large proportion of a slow initiator as defined herein. Initiator AE has been found to work better as a single initiator than other initiators previously employed in in-mold powder coating formulations. The combination of initiators works better than either one alone, and better than any of the few moderate rate initiators available. A method is also disclosed for forming a cured unsaturated polyester surface coating on a cured unsaturated polyester substrate by coating one of the previously stated powder compositions on a heated mold surface so the coating flows and coalesces to form a partially crosslinked coating, then putting a charge of reinforced polyester resin in the mold and closing the mold, maintaining a suitable pressure and temperature for a time sufficient to cure the fill resin and the coating. The coating and substrate are crosslinked across the interface between them when the part is cured. Use of then present compositions in such a process has been found to provide improved surface characteristics of the coating.

In-mold coating powders with two initiators or

Unsaturated polyester resin coating powder composition consisting essentially of at least one unsaturated polyester resin; at least one copolymerizable second resin; and an initiator which comprises 1,1'-di(t-butylperoxy)-3,3,5-trimethylcyclohexane (AE), or which contains a small proportion of a fast initiator and a relatively large proportion of a slow initiator as defined herein. Initiator AE has been found to work better as a single initiator than other initiators previously employed in in-mold powder coating formulations. The combination of initiators works better than either one alone, and better than any of the few moderate rate initiators available. A method is also disclosed for forming a cured unsaturated polyester surface coating on a cured unsaturated polyester substrate by coating one of the previously stated powder compositions on a heated mold surface so the coating flows and coalesces to form a partially crosslinked coating, then putting a charge of reinforced polyester resin in the mold and closing the mold, maintaining a suitable pressure and temperature for a time sufficient to cure the fill resin and the coating. The coating and substrate are crosslinked across the interface between them when the part is cured. Use of the present compositions in such a process has been found to provide improved surface characteristics of the coating.

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Reading, PA, United States of America

Frederick L Cummings