| 摘要 |
A composition for coating a polymeric, thermoplastic, dielectric base film consists essentially of an organic solvent solution of an organopolysiloxane resin having dispersed therein particles of amorphous silica, an estersil, an oxide of a metal of Group IIb, III, IV, V, VI, VII or VIII of the Periodic Table, a carbonate of Ca, Ba, Sa or Mg, calcium sulphate, finely divided clay or mica, the particles having an ultimate average particle size between 5 millimicrons and 5 microns. The siloxanes mentioned contain Si-bonded alkyl, alkenyl, aryl, haloaryl or aroxyaryl radicals. Mixtures of siloxanes may be used. Oxides specified are those of Zn, Ti, Al and Fe. Solvents specified are toluene, xylene, carbon tetrachloride and chloroform. The inorganic particles are preferably used in amount of 5 to 50 per cent by weight of the total siloxane and particles. Curing agents, e.g. lead naphthenate and octoate and zinc octoate, may also be added. Curing of the siloxane resin may be effective at room temperature or at 100 DEG to 175 DEG C. If desired adhesion between the siloxane coating and the base film may be enhanced by a sub-coating of a siloxane resin and a titanium ester, e.g. tetrabutyl- or tetraisopropyl-titanate. In examples coating compositions are composed of methylphenylsiloxane, with or without dimethylsiloxane, lead octoate, toluene and various inorganic particles. The subject matter of Specification 794,581 is disclaimed. Specification 788,151 also is referred to. |
