| 摘要 |
PURPOSE:To enhance the dispersibility of ultrafine particle magnetic powder in a magnetic coated film by incorporating a specified copolymer and the magnetic powder. CONSTITUTION:A copolymer to be used is a resin or a soln. of the resin obtained by copolymerizing respective monomers, and the weight ratio of each component is as follows. Namely, the content of vinyl chloride in the copolymer is preferably regulated to 50-85wt%. The viscosity is too high at >85wt%, and the strength of the coated film is decreased at <50wt%. The content of vinylidene chloride in the copolymer is preferably controlled to 5-25wt%. The heat resistance is deteriorated at >25wt%, and the curl resistance is decreased at <5wt%. The content of hydroxyalkyl acrylate is preferably adjusted to 3-30wt%. The solubility in a solvent is lowered at >30wt%, and the dispersibility is reduced at <3wt%. The contents of unsaturated dicarboxylic acid and unsaturated dicarboxylic acid anhydride are preferably regulated to 0.1-5wt%. The dispersibility is reduced at <0.1wt%, and the solubility in a solvent is unfavorably deteriorated at >5wt%.
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