公开(公告)号：CA995068A

公开(公告)日：1976-08-17

申请号：CA179850

申请日：1973-08-28

Applicant: BASF AG

Inventor： HARTMANN JOB W ,  HARTMANN HANS J ,  ROLLER HERMANN ,  STRITZINGER HEINZ ,  FALK ROLAND

IPC: C09D5/23 ,  G11B5/702 ,  G11B5/738

Abstract: 1445152 Magnetic coating BASF AG 29 Aug 1973 [30 Aug 1972] 40667/73 Heading B2E A flexible magnetic recording media is produced 'by applying a 0.05-1.5 microns thick intermediate coating to a dimensionally stable plastics film which acts as base and subsequently applying a layer of a fluid magnetic dispersion consisting of a finely divided magnetically anisolbropic magnetic pigment, an organic binder which does not cross-link during the dispersion of the magnetic pigment, is free from isocyanate groups and is dissolved in a volatile organic solvent which does not react with isocyanate groups and, optionally a dispersing agent and other conventional additives, orienting the magnetic particles in a magnetic field, drying the magnetic coating and optionally subjecting the magnetic coating to a surface treatment, the intermediate coating comprising a vinylidene chloride copolymer which does not react with isocyanate groups containing 5-70% by weight of a scluble polyisocyanate, and the binder and/or dispersing agent for the magnetic coating containing groups which react with isocyanate groups. The base may be polyethylene terephthalate film. Suitable vinylidene chloride copolymers are copolymers containing at least 70% of vinylidene chloride units, and suitable comonomers are methyl methacrylate, dimethyl maleate, methacrylonitrile and especially acrylonitrile. The magnetic pigments in the magnetic coating may be gamma-iron oxide, magnetite, ferromagnetic chromium dioxide, fenromagnetic metals and metal alloys. Suitable binders for the magnetic coating are vinyl chloride-vinyl ester copolymers, vinylidene chloride-acrylonitrile copolymers, copolyamides, soluble thermoplastic polyester-urethanes, polyvinyl formals and mixtures thereof. Hydroxyl groups or other groups which react with isocyanate groups may be provided in the binder by using copolymers of 50-80% vinyl chloride and 20-50% vinyl esters into which 4-20% by weight of vinyl alcohol units have been introduced by partial hydrolysis. Dispersing agents having groups that react with isocyanate groups mentioned are oleic ethanolamide, isostearic acid, stearic acid, oleic acid, lecithin. Other additives mentioned are lubricants, e.g. metal soaps, fatty acids, waxes, silicon oils, conductive carbon, talc, silicates. The oriented and dried magnetic coatings may be calendered and the coating webs then slit in the longitudinal direction.

公开(公告)号：CA1002822A

公开(公告)日：1977-01-04

申请号：CA185447

申请日：1973-11-09

Applicant: BASF AG

Inventor： HARTMANN JOB W ,  OSTERTAG WERNER ,  SAND RUDOLF ,  SCHAEFER DIETER ,  HARTMANN HANS J

IPC: C08L63/00 ,  G11B5/708 ,  G11B5/73 ,  G11B5/733

Abstract: The invention relates to magnetic discs in which first a non-magnetic intermediate layer and then the magnetic coating are applied by conventional methods to an aluminum disc. The intermediate layer applied to the non-magnetic metallic carrier disc is a hard non-magnetic coating which can be polished and which consists of a dispersion of a pulverulent mixture of finely divided inorganic non-magnetic pigments having a Mohs' hardness of at least 7 in a binder which can be cured and which provides firm cohesion of the pigment particles and good adhesion thereof to the non-magnetic base disc, the pigment mixture containing at least 3 percent by weight of corundum powder having a particle size of from about 1 to 20 mu u. Magnetic discs with very thin magnetic coatings which possess good magnetic and mechanical properties and whose thickness varies only minimally are thus produced in a simple manner.