| 摘要 |
The urethane resin for a magnetic tape comprises a polyol (A) of 450- 700 molecular weight composed of aliphatic and aromatic dibasic acid (3-8 mol ratio) and cyclic and noncyclic glycol ?0.4-0.6 mol ratio?, a diisocyanate (B), a chain-prolonging agent (C), a catalyst (D), and a polymerizing soln. (E). The diisocyanate (B) is pref. 2,4-, 2,6-tollylene diisocyanate or 4,4'-diphenyl methane diisocyanate, the agent (C) is pref. ethylene glycol, 1,4-butane diol or 1,6-hexane diol, the catalyst (D) is pref. tin octoate, tributyl amine or triethylene diamine, and the soln. (E) is pref. methylethyl ketone, tetrahydro furane and/or cyclohexanone. The urethane resin has an improved dispersibility, abrasion-resistance, mechanical strength and a thermal property.
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