| 摘要 |
PURPOSE:To improve the dispersibility of magnetic powder, etc. and to obtain a recording medium having excellent durability, etc. by incorporating a specific polyurethane resin, vinyl chloride/acrylate copolymer and low mol.wt. isocyanate compd. as a binder component into a magnetic layer. CONSTITUTION:The magnetic paint contg. the polyurethane resin which is obtd. by bringing 4,4'-diphenyl methane diisocyanate into reaction with a mixture composed of butyrene adipate and tertiary alcohol such as 1,2,3-trihydroxy-2-methyl propane, has tertiary OH in the position except both terminals of the principal chain and has an average mol.wt. in a 20,000-30,000 range, vinyl chloride/acrylate copolymer and low mol.wt. isocyanate as the binder component is coated on a substrate to form the magnetic layer. Such binder improves the uniform dispersibility of the magnetic powder and the carbon black, Al2O3, etc. to be added thereto and the magnetic recording medium which has an excellent electromagnetic conversion characteristic, withstands long-term running under severe conditions such as high temp., high humidity, low temp. and low humidity and the excellent durability is thus obtd. |
