| 摘要 |
PROBLEM TO BE SOLVED: To provide a magnetic recording medium which is excellent in running durability, magnetic parametric performance, etc. by using a bonding agent excellent in dispersibility of magnetic particle, filling property, wear resistance, heat resistance, etc. SOLUTION: A polyurethane resin having specified ranges of urethane bond density, glass transition temperature and of number average molecular weight is prepared by performing reaction of at least a polyester polyol, that is comprised of an aromatic dibasic acid and a 50-100 mol% aliphatic diol having an alkyl group of at least one carbon number in the side chain and has a number average molecular weight of a specified range, a polyester polyol, that is comprised of an aliphatic and/or alicyclic dibasic acid of 70-100 mol% and an aliphatic diol of 50-100 mol% having alkyl group of at least one carbon number in side chain and has number average molecular weight of a specified range, an aromatic polyisocyanate, and a compound, that has at least two functional groups capable of reacting with isocyanate in one molecule and also has a side chain and has molecular weight of less than 800. There are also provided a magnetic coating composition and a magnetic recording medium being produced by using the polyurethane resin and having specific ranges of urethane content, glass transition temperature and number average molecular weight. COPYRIGHT: (C)2010,JPO&INPIT |
