Two-pack curable urethane adhesive

Abstract

The present invention aims to provide a two-component curable urethane adhesive that is easy to handle while it is substantially solvent-free, having weak to strong adhesive properties, and being capable of forming a cured film having excellent physical properties. The present invention provides a two-component curable urethane adhesive containing: a main agent; and a curing agent, the main agent containing at least one of a hydroxy group-containing urethane prepolymer (P1) or a polyol component (A), the hydroxy group-containing urethane prepolymer (P1) being a reaction product between the polyol component (A) and an organic polyisocyanate component (B), the curing agent containing at least one of an isocyanate group-containing urethane prepolymer (P2) or an organic polyisocyanate component (B), the isocyanate group-containing urethane prepolymer (P2) being a reaction product between the polyol component (A) and the organic polyisocyanate component (B), wherein the two-component curable urethane adhesive satisfies the following properties (1) to (5): (1) at least one of the polyol component (A) used in the hydroxy group-containing urethane prepolymer (P1) or the polyol component (A) used as the main agent contains a polyol (A1) having at least one of a group represented by a formula (1) or a group represented by a formula (2) at a molecular end thereof, and a total number of groups represented by the formula (1) in the polyol (A1) accounts for 40% or more based on a total number of groups represented by the formulas (1) and (2) in the polyol (A1); (2) an average total unsaturation degree of all the polyol components (A) used in the two-component curable urethane adhesive is 0.010 meq/g or less; (3) a weight average molecular weight of each of the urethane prepolymer (P1) and the urethane prepolymer (P2) is 1,000 to 100,000; (4) a chemical formula weight or number average molecular weight of each of the polyol component (A) and the organic polyisocyanate component (B) is 20,000 or less; and (5) a total weight of solvents in the main agent (excluding the polyol component (A)) and solvents in the curing agent (excluding the organic polyisocyanate component (B)) accounts for 5 wt % or less based on a total weight of the main agent and the curing agent, wherein in the formulas (1) and (2), each a is independently an integer of 0 or greater.

Dependencies are inferred from the claim text.