| 摘要 |
<p>1293869 Chromium dioxide composition E I DU PONT DE NEMOURS & CO 3 July 1970 [10 July 1969] 32468/70 Heading H1H A ferromagnetic chromium dioxide composition comprises more than 75% by weight of the total composition of acicular particles of ferromagnetic chromium dioxide stabilized against reductive degradation and dispersed in a binder comprising a preformed polyurethane resin and a polyfunctional isocyanate hardening agent. The stabilized chromium dioxide is preferably obtained by treating particles of CrO 2 with a reducing agent, e.g. sodium bisulphite, so as to reduce the surface layer of the particles and form a protective coating. The composition may contain other resins in addition to the polyurethane resin (many being specified), a vinylidene chloride/acrylonitrile copolymer being preferred. The composition may also contain a dispersing agent (many of which are specified), e.g. soya lecithin, and a lubricant, e.g. stearamide, squalane or stearates. The compositions may be made into self-supporting films or may be coated on to a film of cellulose acetate or polyethylene terephthalate.</p> |
