METHOD FOR PRODUCING POLYURETHANE RESIN, POLYUREA RESIN OR POLYURETHANE-POLYUREA RESIN, AND MAGNETIC RECORDING MEDIUM

PROBLEM TO BE SOLVED: To provide a method for producing a polyurethane resin, polyurea resin or polyurethane-polyurea resin which includes a large average molecular weight, is excellent in solubility in a solvent, and ensures excellent smoothness, electromagnetic transducing characteristics and repeated sliding durability when used as a binder in a magnetic recording medium, and to provide a magnetic recording medium which is excellent in smoothness, electromagnetic transducing characteristics and repeated sliding durability. SOLUTION: The method for producing the polyurethane resin, polyurea resin or polyurethane-polyurea resin includes reacting a diol compound and/or a diamine compound with a diisocyanate compound in the presence of 0.01-1 mol equivalent of a Bronsted acid based on the total molar quantity of urethane bonds and urea bonds in the obtained resin. The magnetic recording medium contains a resin obtained by the production method as a binder. COPYRIGHT: (C)2009,JPO&INPIT