| 摘要 |
PURPOSE:To enhance solvent resistance and traveling durability and to improve the dispersibility of magnetic powder by using a specified polyurethane resin as the component of a binder for dispersing ferromagnetic powder in a magnetic material to be applied on a nonmagnetic base. CONSTITUTION:The magnetic recording medium is formed by coating the nonmagnetic base with the magnetic material formed by dispersing the ferromagnetic powder into the binder. The phosphorus-contg. polyurethane resin of 6,000 to 50,000mol.wt. having at least 150 to 500eq/t hydroxyl group in the molecule chain and 5 to 1,000eq/t at least one kind of the phosphorus compds. expressed by formula I to formula V in the molecule chain is used as the component of the above-mentioned binder. In the formulas, X, Y denote an ester-forming function group; R1 denotes a hydrocarbon group, etc.; R2 denotes an alkyl group, etc. R3, R4 denote an alkylene group, etc.; M denotes an alkaline metal atom, etc. The magnetic recording medium which has the excellent solvent resistance and traveling durability and is improved in the dispersibility of the magnetic powder is obtd. in this way. |
