Denki Kagaku Kogyo Kabushiki Kaisha

Toshio Kagami

Shigeto Miyoshi

Kunio Iriuchijima

Kanehisa Hanabusa

Shigeru Matsushita

Yoshijiro Saito

A magnetic coating for a magnetic recording medium prepared by kneading a copolymer comprising vinyl chloride, a vinyl carboxylate ester, vinyl alcohol and an unsaturated dicarboxylic acid and/or an unsaturated dicarboxylic acid anhydride; a thermosetting resin; and a magnetic powder, in an organic solvent.

Magnetic coating for magnetic recording media

According to the invention there are provided a thermoplastic resin for use in a coating resin, and a process for preparing such resin, said thermoplastic resin being a hydrolyzed product of a vinyl chloride copolymer obtained by polymerizing 50 to 80% by weight of a vinyl chloride monomer, 20 to 40% by weight of a vinyl ester monomer and 0 to 15% by weight of a comonomer polymerizable with the vinyl chloride monomer, said vinyl chloride copolymer having an average polymerization degree of 200 to 800 and said hydrolyzed product having an absorption ratio of OH/CH in the infrared absorption spectrum of from 0.5 to 0.9.

Thermoplastic resin of hydrolyzed product of vinyl chloride copolymer

In the manufacture of a vinyl chloride copolymer solution by dissolving in an organic solvent a vinyl chloride copolymer consisting of 50 to 90 wt % of vinyl chloride and 10 to 50 wt % of vinyl ester and having a mean polymerization degree of 100 to 800 and hydrolyzing the solution in the presence of alcohol, the viscosity of the hydrolyzed solution of the vinyl chloride copolymer is adjusted to 500 to 1000 CPS and the alcohol and the organic solvent are distilled at a temperature below 60.degree. C. under a reduced pressure of 100 to 200 Torr and, when the alcohol content in the hydrolyzed solution becomes less than 0.5 wt %, the atmospheric pressure is restored.

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Takasaki, Japan

Toshio Kagami