Low viscosity, high Tg dispersion for magnetic tape - with binder contg. polyester-oligo-urethane or hydroxy-oligo-urethane in addn. to hard and soft polymer

摘要

The novel feature in a magnetic recording material having a magnetic layer comprising a finely-divided magnetic pigment and a crosslinker in a binder mixt. contg. (A) a binder of Tg below 10 deg.C. and (B) a binder of TG above 30 deg.C. is that the binder mixt. also contains (C) an OH-contg. oligourethane or polyesteroligourethane. USE/ADVANTAGE - The material can be used as a video tape. Use of this three-component binder gives a low viscosity magnetic dispersion which can be spread at high speed on the carrier tape in stripe-free condition to give a prod. with good electro-acoustic properties (in partic. low modulation roar), good stability in a VHS E-120 cassette to harsh conditions, (e.g. 40 deg.C./85% RH), low drop-out and a softening pt. higher than that for conventional recording materials. Adhesion drop in tape coiling is reduced.