Method for preparing water-based urethane resin composition

Abstract

A method for preparing a water-based urethane resin composition by reacting a urethane prepolymer (A), which has an isocyanate group at a terminal end and has a carboxyl group in a molecular side chain, a chain extender (B) of the urethane prepolymer (A), and a basic compound (C) in a reaction solvent (D), which comprises: (1) using, as the urethane prepolymer (A), which has an isocyanate group at a terminal end and has a carboxyl group in a molecular side chain, a urethane prepolymer (a) in which 70 molar % or more of terminal isocyanate groups are attached to carbon of secondary and/or tertiary aliphatic hydrocarbons, the urethane prepolymer being soluble in an alcohol solvent (d), (2) using, as the chain extender (B) of the urethane prepolymer (A), a polyamine (b) having two or more amino groups containing active hydrogen, and (3) using, as the reaction solvent (D), a water-based solvent containing the alcohol solvent (d), has advantages in view of environmental conservation and has good productivity. According to this method, it is possible to obtain a water-based urethane resin composition, which is superior in physical properties such as water resistance and is suited for use as a binder for water-based printing ink.

Dependencies are inferred from the claim text.