Hydrated alumina binder system.

摘要

The composition and method of making a magnetic recording media using a polyurethane binder system with high lubricant retention and a high concentration of magnetic particles is described. The use of hydrated alumina with a solvent blocked isocyanate is used to produce an open cell microporosity in the cured coating wherein the individual voids are not greater than the magnetic bit cell size and the alumina particles remain in the coating to improve abrasion resistance. The porosity size is controlled by a surface active agent additive. Also shown is the method of preparing hydrated alumina with small particle size, dispersibility, and compatibility, and wherein temperature whereby the C0<Sub>2</Sub> formation that creates the porosity occurs as the polyurethane components cure.