| 摘要 |
PURPOSE:To obtain a magnetic recording medium of high quality contg. well dispersed magnetic particles by using a mixture of acrylic modified polyurethane resin having a quinquefunctional branched molecular structure or higher having polyester as the skeleton with a thermoplastic resin as a binder in a magnetic layer. CONSTITUTION:Polyester polyol having 2,000-4,000mol.wt. as a skeleton is reacted with a mixture of polyether diol with polyether triol and diisocyanate to prepare quinquefunctional branched polyurethane resin or higher. The polyester polyol is a reaction product prepd. by reacting propylene glycol or 1,4-butanediol with adipic acid. The polyurethane resin is further reacted with hydroxydiethyl acrylate to prepare acrylic modified polyurethane resin having 20,000-50,000 mol.wt. The modified polyurethane resin is mixed with a thermoplastic resin such as PVC or a vinyl chloride-vinyl acetate copolymer to obtain a binder. Magnetic powder is dispersed in the binder, and the resulting coating material is coated on a support and cured with electron beams ot form a magnetic layer. This magnetic layer has superior adhesive strength to the support, and a recording medium having superior wear resistance and durability is obtd. without requiring the surface treatment of the support or the magnetic particles. |
