| 摘要 |
PURPOSE:To provide a polyurethane resin binder composed of a specific active hydrogen-containing compound and a polyisocyanate, exhibiting excellent dispersing property to highly magnetized fine magnetic powder, processable easily by calendering, and giving a recording material having excellent abrasion resistance, etc. CONSTITUTION:The objective binder is composed of (A) an active hydrogen- containing compound composed of (i) >=250 equivalent of a high-molecular polyol and if necessary (ii) 30-250 equivalent of a low-molecular active hydrogen- containing polyfunctional compound (at least a part of the above two components is a modified silicone oil having active hydrogen-containing group) and (iii) 40-500 equivalent of a compound having carboxyl group and other active hydrogen-containing group and (B) a polyurethane having a number-average molecular weight of 5,000-150,000 and derived from a polyisocyanate. The active hydrogen-containing group is selected from OH, NH2, NH and SH. A recording material can be manufactured by mixing the binder with magnetic powder of 0.01-0.80mum diameter.
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