PURPOSE: To improve recording performance and mechanical stability by incorpo rating a thermoplastic and elastic polyurethane binder which is easily dissolved in either and/or ketone and has good dispersability into a magnetic medium.
CONSTITUTION: This magnetic recording medium comprises a nonmagnetic substrate and a magnetic layer formed of a magnetic material which is finely dispersed in a binder containing 50wt.% thermoplastic polyurethane. The thermoplastic polyurethane is a branched-chain polyurethane which is soluble with tetrahydrofuran and contains no isocyanate group. The polyurethane has urea groups with or without OH groups on the end of the chain and 30000 to 100000mol.wt.(Mw) and comprises the following five components. (A) One mol of polydiol having 400 to 10000mol.wt., (B) 0.3 to 10 moles of mixture of 12-18C diol and diol having phosphone groups, (C) 0.01 to 1 mole of 3-25C triol or polyol. (D) 1.3 to 13 moles of 6-30C diisocyanate, and (E) 0.09 to 2 moles of 2-16C aminoalcohol or monoamine containing no OH group. The ratios of OH groups in the components (A) to (C), NCO groups in the components (D) and the amino groups in the component (E) are 1:(1.03 to 1.3):(0.03 to 0.3).
HERUMAN DEIKOBU
MIHIYAERU BOBURITSUHI
HERUMUUTO AUBUETAA
ARUBERUTO KOORU
RUDORUFU ZUYUTEINGAA
YOTSUHEN RUDORUFU
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