| abstract |
The invention relates to a sulfonated, thiol, and hydroxy-functional polyurethane polymer which comprises: (i) a polyurethane backbone; (ii) at least one SO₃M group pendant from the polyurethane backbone, wherein the polyurethane backbone has an SO₃M equivalent weight of from about 2,000 to about 100,000, and wherein M is selected from the group consisting of H+, NR₄+ wherein R can be H+ or an alkyl group, Li+, Na+, K+, and mixtures thereof; (iii) at least two crosslinkable hydroxy groups pendant from the polyurethane backbone, wherein the polyurethane backbone has a hydroxy equivalent weight of from about 500 to about 50,000; and (iv) at least one -SH group pendant from the polyurethane backbone. The invention also relates to vinyl/polyurethane copolymers made therewith which are particularly useful as binders in magnetic recording media and a method of making the copolymers. The invention also relates to certain nonsulfonated thiol and hydroxy functional polyurethane graft copolymers and dispersions made therewith. |