Patent ID: 8729154

Claim:
A binder for an ink jet printing ink, the binder comprising: an aqueous medium (D); and a polyurethane (C) obtained by reacting a polyol (A) containing a vinyl polymer (a1) having two hydroxyl groups at one end and at least one polyol (a2) selected from the group consisting of polyether polyols, polyester polyols, polyester ether polyols, and polycarbonate polyols with a polyisocyanate (B), wherein: the polyurethane (C) has a structure derived from the vinyl polymer (a1) in a side chain thereof, the polyurethane (C) is dispersed in the aqueous medium (D), the vinyl polymer (a1) is used in an amount in the range of 1% to 60% by mass relative to the total mass of the ingredients used in the production of the polyurethane (C), the polyol (a2) is used in a range of 5% to 80% by mass relative to the total mass of the ingredients used in producing the polyurethane (C), and the mass ratio of the vinyl polymer (a1) to the polyol (a2) is from 1/20 to 20/1.