Method for preparing aqueous dispersion of developer and pressure-sensitive recording paper

Abstract

Herein disclosed are a method for preparing an aqueous developer dispersion which comprises the steps of dissolving, in an organic solvent, a developer which comprises a nuclear-substituted salicylic acid salt represented by the following general formula (I): ##STR1## wherein R.sub.1, R.sub.2, R.sub.3 and R.sub.4 may be the same or different and each represents a hydrogen atom, a halogen atom, an alkyl group having not more than 15 carbon atoms, a cycloalkyl group, a phenyl group, a nuclear-substituted phenyl group, an aralkyl group or a nculear-substituted aralkyl group, or two adjacent groups selected from R.sub.1 to R.sub.4 may be bonded together to form a ring; n is an integer of not less than 1; and M represents magnesium, calcium, zinc, aluminum, iron, cobalt, nickel or a basic ion thereof; emulsifying and dispersing the resulting solution in an aqueous solution of an acrylamide copolymer having a degree of polymerization of not less than 100 obtained by copolymerizing 96 to 70 mole % of acrylamide with 4 to 30 mole % of an alkyl or alkoxyalkyl, having not more than 4 carbon atoms, ester of acrylic acid, methacrylic acid, itaconic acid or maleic acid; then heating the emulsified dispersion to remove the organic solvent by distillation; and optionally finely wet-pulverizing the resulting aqueous dispersion to an extent that reduction in the average particle size of the developer dispersed in the dispersion does not exceed 10%; as well as pressure-sensitive recording paper obtained using the aqueous developer dispersion. The recording paper is substantially improved in the developing density, developing velocity and printability.

Dependencies are inferred from the claim text.