MAGNETIC RECORDING MEDIUM

摘要

PURPOSE: To enhance wear resistance and residual magnetic induction at and under a high temp. and high humidity and to obtain a defectless layer surface and a narrow magnetic field intensity distribution by using OH group-contg. polyurea urethane and polyurethane urea (meth)acrylate as a binder compsn. in a magnetic layer. CONSTITUTION: The polyurethane urea (meth)acrylate consists of poly (meth) acrylate having terminal OH groups up to two pieces per mol and a mol.wt. of 200 to 50000, 0.1 to 10wt.% diisocyanate, 30 to 80wt.% triisicyanate, 20 to 60wt.% isocyanate exhibiting functional 4 to 10. The polyurea (meth)acrylate is brought into reaction with an aliphat. polyisocyanate mixture having average functionality of NCO groups of 3 to 6 pieces per mol. The NCO groups of 2 to 3 pieces per piece of the OH group react and the residual NCO groups are converted to a substd. terminal urea group having multifunctional amine or plural kinds of the multifunctional amine mixture varying from each other.