反应详情

100 parts of 3-phenyl-5-(α,α-dimethylbenzyl) salicylic acid was mixed by the use of Nauta mixer with 50 parts of aluminum oxide, 50 parts of styrene-methyl methacrylate copolymer which was obtained by the polymerization of 80% styrene and 20% methyl methacrylate and had a molecular weight of about 2,000 and 20 parts of an aqueous solution of 10% polyvinyl alcohol. The resultant mixture was heated and kneaded in an extruder set to 140° C. to obtain a homogeneous mass. The mass was pulverized with a grinder to form finely divided particles of color developer, 85% of which was passed through 300 mesh Tyler standard screen. The water content of the color developer was 2% on the total dry basis.