Carboxylic-acid functional polyurethane polymers and their use in magnetic recording media

A composite for magnetic recording comprising:

• (a) a substrate having a from side and a back side;
• (b) a dispersion coating on at least one side of said substrate comprising a carboxylic acid functional polyurethane polymer comprising the reaction product of:
• (i) one or more polyisocyanates;
• (ii) one or more polyols;
• (iii) one or more compounds selected from the group consisting of cyclic dicarboxylic acid anhydrides bearing at least one additional polar group in addition to its polar anhydride group;
• dicarboxylic acid(s) bearing at least one additional polar group in addition to its two polar carboxyl groups which are capable of forming cyclic anhydrides;
• and mixtures thereof;
• and
• (c) a magnetizable pigment and optionally a nonmagnetizable pigment dispersed in said dispersion on at least one side of said substrate.

A magnetic recording media having a magnetizable layer of pigment particles which are dispersed in a binder wherein said binder comprises the a carboxylic acid functional polyurethane polymer comprising the reaction product of:

• (i) one or more polyisocyanates;
• (ii) one or more polyols;
• (iii) one or more compounds selected from the group consisting of cyclic dicarboxylic acid anhydrides bearing at least one additional polar group in addition to its polar anhydride group;
• dicarboxylic acid(s) beating at least one additional polar group in addition to its two polar carboxyl groups which are capable of forming cyclic anhydrides;
• and mixtures thereof.

A composition comprising:

• (a) about 5 to 95 weight percent of a vinyl chloride copolymer;
• and
• (b) about 5 to about 95 weight percent of a polymer selected from the group consisting of a carboxylic acid-functional polyurethane polymer comprising:
• a plurality of --COOH groups pendant from a polyurethane polymer backbone, wherein the polyurethane polymer has an --COOH equivalent weight of from about 1000 to about 100,000;
• wherein said carboxylic acid-functional polyurethane polymer is obtained by the condensation reaction of at least one hydroxyl group pendant from said polyurethane polymer backbone with an aliphatic polar-group substituted dicarboxylic acid anhydride selected from the group consisting of anhydrides represented by formula I, ##STR8## wherein R.sup.1, R.sup.2, R.sup.3, and R.sup.4, are independently selected from the group consisting of --H, --OH, --COOM, --SO.sub.3 M, --SH, --CH.sub.2 COOM, --SCH.sub.2 COOM, --P(.dbd.O)(OM).sub.2, --OP(.dbd.O)(OM).sub.2, and --Y, wherein at least one of R.sup.1, R.sup.2, R.sup.3, and R.sup.4 comprises a moiety other than --H or --Y;
• Y is selected from the group consisting of linear alkyl groups comprising from about 1 to about 10 carbon atoms, branched alkyl groups comprising from about 1 to about 10 carbon atoms, and aryl groups comprising from about 6 to about 10 carbon atoms;
• M is a cation selected from the group consisting of alkali metal cations, H.sup.+ and ammonium cations;
• R.sup.1 and R.sup.2 together or R.sup.3 and R.sup.4 together can optionally be .dbd.CHCOOH;
• X is a divalent moiety independently selected from the group consisting of ##STR9## n represents an integer selected from the group consisting of 0 and 1;
• R.sup.5 and R.sup.6 are independently selected from the group consisting of --H, --OH, --COOM, --SO.sub.3 M, --SH, --CH.sub.2 COOM, --SCH.sub.2 COOM, --P(.dbd.O)(OM).sub.2 --OP(.dbd.O)(OM).sub.2, and --Y, wherein M and Y are as defined above;
• and
• R.sup.7 is a monovalent moiety independently selected from the group consisting of --CH.sub.2 COOH, --CH.sub.2 CH.sub.2 COOH, --CH.sub.2 CH.sub.2 N(CH.sub.2 COOH).sub.2, --(CH.sub.2).sub.6 N(CH.sub.2 COOH).sub.2, --(CH.sub.2 CH.sub.2 O).sub.2 CH.sub.2 CH.sub.2 N(CH.sub.2 COOH).sub.2, and --CH.sub.2 CH.sub.2 N(CH.sub.2 COOH) CH.sub.2 CH.sub.2 OH.