Magnetische Aufzeichnungsträger

摘要

Magnetic recording medium has a non-magnetic substrate and a magnetisable layer containing ferromagnetic pigment and a polymer system, containing 40-100 wt.% polymers (I) and (II), comprising 3-35 wt.% polymer (I) and 5-97 wt.% polymer (II). (I) is obtained by reacting (1) a polymer (III) of (a) 80-100 mole-% 1-25 carbon (C) alkyl or an alpha , beta -unsaturated carboxylic acid, (b) 0-20 mole-% other monomer(s) and (c) a starter and/or regulator giving hydroxyl-(OH) terminated polymer chains, with (2) a non-aromatic polyisocyanate, using 1.2-3.9 mole isocyanate (NCO) groups/mole OH groups in (III); and (3) reacting the product (a) with a compound containing NCO-reactive groups in an amount of 2-7 mole NCO-reactive groups/mole free NCO groups in (III) and (b) then with a compound that reacts with the free reactive groups and introduces ionic or ionogenic groups; or (b) with a compound containing NCO-reactive groups that introduces ionic or ionogenic groups. (II) has a molecular weight of 30 000-2 000 000 and is obtained by reacting (1) 1 mole of a polymeric diol with a number average molecular weight (Mn) of 400-10000 with (2) 0.3-1 mole 2-18 C diol, 0.01-1 mole 3-25 C polyol with NOTLESS 3 OH groups, (4) 1.3-13 mole 6-30 C diisocyanate and (5) 0.09-2 mole 2-16 C amino-alcohol. The ratio of the sum of OH groups in the diols and polyols to NCO groups in the diisocyanate to amino groups in the amino-alcohol is 1:(1.03-1.3):(0.03-0.3).