Patent ID: 8841357
Filing Date: 2014-09-23
Classification: B41J,C08G,C09D,Y10T

Abstract:
1. A binder for ink-jet printing ink, comprising: a polyurethane (A) that has a hydroxyl group at a molecular terminal, has a weight-average molecular weight of 30,000 to 70,000, and is obtained by preparing a urethane prepolymer having an isocyanate group at a molecular terminal through a reaction of a polyisocyanate (a1) and part of a polyol (a2) and then causing a reaction of the urethane prepolymer and the polyether polyol (a2-1); and an aqueous medium (B), wherein: the hydroxyl group present at the molecular terminal of the polyurethane (A) is a hydroxyl group derived from the polyether polyol (a2-1); the equivalent ratio of an isocyanate group [X] in the polyisocyanate (a1) to a hydroxyl group [Y] in the polyol (a2), isocyanate group [X]/hydroxyl group [Y], is in the range of 0.930 to 0.995; and the polyol (a2) contains the polyether polyol (a2-1), which is represented by general formula [I]: where R represents an alkylene group having 3 to 8 carbon atoms, and n is an average number of addition moles of a structural unit RO, n being in the range of 8 to 55.