| 摘要 |
<p>A composition comprises 10-90% by weight of an organic copolymer containing halogen, carbon, oxygen and hydrogen having a plurality of hydroxyl groups and more than 6% by wt. of fluorine and 90-10% of polysilic acid (calculated as SiO2), e.g. obtained by a hydrolysis of ethyl silicate which has not been allowed to reach the silica gel stage. The copolymer is preferably formed from units of (a) one or more hydroxyalkyl vinyl ethers having up to ten carbons in the alkyl and (b) tetrafluoroethylene and/or trifluorochloroethylene; alternatively the hydroxyl groups are obtained by hydrolysis of a vinyl acetate copolymer with (b). A further monomer may be added, e.g. 2-methoxyethyl vinyl ether, or octadecyl vinyl ether. The compositions are dissolved in solvents to form coating compositions. Suitable solvents are mixtures of C1-C5 alkanols, water and optionally C1-C3 alkanoic acids and trichlorethylene The solutions may also contain block copolymers of mixed polyalkylene oxides with dimethyl siloxane, "Cellosolve" (Registered Trade Mark) derivatives and cross-linking agents, e.g. peroxides, acids, aldehydes or metallic driers.ALSO:Coating compositions comprise solutions of a mixture of (a) 90-10% by wt. of an organic copolymer having a plurality of hydroxyl groups and containing more than 6% by wt. of fluorine and (b) 10 - 90% by wt. (calculated as SiO2) of polysilicic acid, the soluble product obtained by hydrolysis of e.g. ethyl silicate which has not been allowed to reach the silica gel stage. Preferred copolymers are of tetrafluoroethylene with vinyl acetate (which is hydrolysed after polymerisation) or a hydroxyalkylvinylether (see Division C3). The mixtures are dissolved in an alcohol which may contain water, a C1 - C3 alkanoic acid or trichloroethylene and the solutions may also contain a block copolymer of polyalkylene oxides with dimethyl siloxane or Cellosolve (registered Trade Mark) derivatives. The solutions may be applied by flowing, spraying or dipping to painted surfaces, metal, glass, wood or particularly to thermoplastic materials such as polymethylmethacrylate. The solvent is removed by drying in air or heating in an oven at 90-180 DEG C for 10 - 60 minutes. The coats may be 0.1 - 20 microns in thickness.</p> |
