Powder coating resin process containing an aromatic carbonamide condensate

Claim 1

A process for preparing a curable powder resin composition with a sintering temperature above 40° C. and curable in the temperature range of 120° to 220° C., comprising: (A) Condensing a methylolamino compound with an aliphatic alcohol and an aromatic carbonamide of number average molecular weight less than 500 to produce an aminoplast condensate with a glass transition temperature in the range of -10° C. to 100° C., wherein the methylolamino compound is selected from the group consisting of methylolureas and methylolaminotriazines and contains no more than one unmethylolated N--H bond per molecule, wherein the aliphatic alcohol contains from 1 to 4 carbon atoms, wherein at least about 50 percent of the methylol groups of the methylolamino compound have been condensed with the aliphatic alcohol or the aromatic carbonamide, wherein the molar ratio of the aliphatic alcohol to the methylolamino compound is at least 2, and wherein the molar ratio of the methylolamino compound to the aromatic carbonamide is from about 1:0.5 to about 1.2 when the aromatic carbonamide contains one reactive group per molecule and is from about 1:0.5 to about 1:1.5 when the aromatic carbonamide contains 2 or more reactive groups per molecule, (B) Blending from about 15 to about 30 parts by weight of the aminoplast condensate with from about 85 to 70 parts by weight of a polyester resin or an acrylic resin, wherein the resin has a glass transition temperature in the range of from 60° to 100° C. and a number average molecular weight in the range of 500 to 25,000 and contains alcoholic hydroxyl groups, carboxyl groups or amide groups heat reactive with the aminoplast condensate, wherein the polyester resin has an acid number in the range of 1 to 25 or a hydroxyl number in the range of 11 to 200, and wherein the acrylic resin contains from 0.13 to 18 weight percent of hydroxyl, carboxyl or amide groups, and (C) Crushing the blend to form a powder of average particle size in the range of 20 to 150 microns.