| 摘要 |
PURPOSE:To obtain a magnetic recording medium having superior surface smoothness, squareness ratio, durability etc. and suitable for use especially as a videotape by forming a magnetic layer contg. ferromagnetic fine powder dispersed in a binder contg. polyurethane resin having one or more COOH groups in one molecule in a support. CONSTITUTION:Polyurethane resin having one or more COOH groups in one molecule is obtd. by reacting diisocyanate with polyester obtd. by the dehydration condensation of dicarboxylic acid with a compound having two OH groups and one COOH group such as dimethylolpropionic acid. Ferromagnetic fine powder is kneaded and dispersed in a composition consisting of said polyurethane resin or a mixture of the resin with other resin and of a solvent to prepare a magnetic coating material. The coating material is applied to a support and dried. The magnetic powder is uniformly dispersed, and a magnetic recording medium having superior surface smoothness, electromagnetic transducing characteristics, durability, etc. and suitable for use especially as a videotape is obtd. |
