| 摘要 |
PURPOSE:To improve the dispersibility, wear resistance and heat resistance of magnetic powder, by using a binder which contains a specific quaternary copolymer, low-molecular weight plasticizer and trifunctional low-molecular weight isocyanate. CONSTITUTION:A magnetic layer is formed by using a binder which contains a quad copolymer of 200-600 polymerization degree consisting of 70-80wt% vinyl chloride, 1-5wt% vinyl acetate, 2-10wt% acrylic ester, and 10-20wt% vinyl alcohol, a plasticizer of <=800 molecular weight, such as phthalic ester and fatty acid dibasic acid ester, and trifunctional low-molecular weight isocyanate. Consequently, the dispersibility of magnetic powder is improved and the magnetic recording medium superior in wear resistance and heat resistance (having the magnetic layer which never gets adhesive at high temperature and high humidity) can be obtained. |
