Epoxy resin coating powders - by grinding homogeneous mixt of styrene/maleic anhydride copolymer, carboxylic anhydride and

摘要

Coating compsn. based on a partly cured, powdered epoxy resin with a m.p. 100 degrees C is prepd. by (a) mixing a molten styrene-maleic anhydride copolymer having a moler ratio styrene-maleic anhydride of 1-10 : 1 at a mol. wt. of 500-5000, and contg. at least two anhydride rings per molecule, with a carboxylic anhydride with a m.p. below 100 degrees C, the molar ratio of anhydride to copolymer being 1-9:1, until a clear soln. is formed (b) adding compatible epoxy resin, the ratio of anhydride equivs. of the copolymer and the anhydride to the epoxy equivs. of the epoxy resin being 0.4-2: 1, (c) heating the mixt. until a soln. or dispersion is formed (d) transferring the molten mass to a roller mixer of maintaining the formed sheet at a temp. at least equal to the softening point which is 40-140 degrees C, (e) adding a curing catalyst uniformly to the surface of the sheet (f) folding the sheet and passing it continuously through the contact zone of the rollers to form a uniform mixt. (g) removing and cooling the sheet, (h) grinding to give particles passing a sieve with a 840 mesh, and (i) grinding in a ball mill to give epoxy resin particles, of which =75% have a size 149 mu. Epoxy resin particles are resistant to cold flow.