Non-hazing UV curable powder coatings containing crystalline resins
Morton International Inc.
This invention provides a UV curable powder coating composition comprising a particulate blend of a non-crystalline unsaturated polyester base resin, a crystalline unsaturated crosslinker resin co-polymerizable with the base resin, and a photoinitiator, that exhibits reduced or eliminated hazing in the cured coating formed therefrom upon being cured at low temperatures demanded by certain heat sensitive substrates. This is accomplished by incorporating in the powder composition a recrystallization or haze inhibitor which is comprised of a crystalline epoxy resin. When this powder blend is melted for curing, the crystalline crosslinker resin visually appears to separate and recrystallize out of the molten powder less completely than it does in the absence of the recrystallization or haze inhibitor. This prevents a visible haze from developing on the surface of the coating upon curing…
1ClaimsFirst of 23
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A non-hazing UV curable powder coating composition, which comprises a film-forming particulate blend of: A) an unsaturated base resin; B) an unsaturated crosslinker resin co-polymerizable with the base resin; and, C) a photoinitiator, wherein the combination of components A) plus B) comprises a blend of at least one crystalline resin susceptible to hazing and at least one non-crystalline resin, and wherein the composition further comprises D) a recrystallization or haze inhibitor comprising at…
2Description
This is a CONTINUATION-IN-PART, of copending application Ser. No. 09/136,184filed on Aug. 19, 1998 U.S. Pat. No. 6,011,080.