Linear salicylic acid copolymer and its metal salt, a process for producing the same, a coloring agent containing a metal resin of the copolymer, and a coloring sheet using the coloring agent

摘要

A develper sheet fora pressure sensitive copying paper, contg. metla cpd. of a copolycondensate resin composed of salicylic acid (a), alpha, alpha'-dialkoxy-p-xylene (b) and 1,3,5trialkyl benzene of formula (I) [R1=R2=R3 C1-4 alkyl!. The resin is prepd. by reacting (a) with (b) in the presence of an acid catalyst at 110-240 deg.C. The sheet keeps a stabiltiy of a coloured image against light, plasticizer and water.