Powdery coating media and their use
First Claim
Patent Images
1. A curable finely divided solid composition comprising (1) an epoxy compound having more than one 1,2-epoxide group and having a lower fusion point of at least 40°
- C. and (2) 2-15%, by weight, based on the solid epoxy compound, of a blocked polyisocyanate formed by the reaction of a polyisocyanate with a compound of the formula ##STR3## wherein each R is independently selected from hydrogen, alkyl, cycloalkyl, aralkyl, and aryl radicals.
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Abstract
Storage stable epoxy resin powder coating compositions are disclosed, which contain a solid epoxy resin and, as hardening agent, a blocked polyisocyanate compound or isocyanate terminated polymer, wherein the blocking agent is an imidazoline compound.
21 Citations
10 Claims
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1. A curable finely divided solid composition comprising (1) an epoxy compound having more than one 1,2-epoxide group and having a lower fusion point of at least 40°
- C. and (2) 2-15%, by weight, based on the solid epoxy compound, of a blocked polyisocyanate formed by the reaction of a polyisocyanate with a compound of the formula ##STR3## wherein each R is independently selected from hydrogen, alkyl, cycloalkyl, aralkyl, and aryl radicals.
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2. A curable finely divided solid composition comprising (1) an epoxy compound having more than one 1,2-epoxide group and having a lower fusion point of at least 40°
- C. and (2) 2-15% by weight, based on the solid epoxy compound, of a blocked polyisocyanate formed by the reaction of (a) an isocyanate terminated prepolymer obtained by reaction of a polyol with a polyisocyanate, with (b) a compound of the formula ##STR4## wherein each R is independently selected from hydrogen, alkyl, cycloalkyl, aralkyl, and aryl radicals.
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3. A curable finely divided solid coating composition having a particle size of less than 0.25 mm comprising:
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(i) an epoxy compound having more than one 1,2-epoxide group and having a lower fusion point greater than 40°
C.;(ii) lacquer additives; and (iii) 2-15 wt.% based on the solid epoxy compound of polyisocyanates blocked with cyclic amidines of the formula;
##STR5## wherein the R'"'"'s are the same or different and are selected from the group consisting of hydrogen, alkyl, cycloalkyl, aralkyl and aryl. - View Dependent Claims (4)
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5. A method for preparing the coating composition which comprises:
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a. admixing a solid epoxide compound having more than one 1,2-epoxide group and having a lower fusion point of greater than 40°
C. with a polyisocyanate blocked by a cyclic amidine of the formula;
##STR7## wherein the R'"'"'s are the same or different and are selected from the group consisting of hydrogen, alkyl, cycloalkyl, aralkyl and aryl;b. extruding the admixture at a temperature at least 30°
C. below the splitting temperature of said blocked polyisocyanate; andc. grinding the extruded mixture to a particle size less than 0.25 mm. - View Dependent Claims (6, 7, 8, 9)
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10. A method of coating a substrate which comprises:
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a. applying to said substrate the coating composition comprising; (i) an epoxy compound having more than one 1,2-epoxide group and having a lower fusion point greater than 40°
C.;(ii) lacquer additives; and (iii) 2-15% based on the solid epoxy compound of polyisocyanates blocked with cyclic amidines of the formula;
##STR8## wherein the R'"'"'s are the same or different and are selected from the group consisting of hydrogen, alkyl, cycloalkyl, aralkyl and aryl; andb. heating at a temperature above the splitting temperature of the blocked polyisocyanate.
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Specification