| 摘要 |
<p>Film-forming compositions comprise in aqueous dispersion a blend of a homopolymer of a vinyl ester and a copolymer of a vinyl ester and a lower alkyl acrylate. The preferred vinyl ester is vinyl acetate and specified alkyl acrylates are ethyl, butyl and 2-ethylhexyl acrylates. The compositions may contain pigments, e.g. carbon black, lithopone, calcium carbonate and titanium dioxide. The compositions may be used to form adherent but readily strippable coatings on photographic film base, metals, glass, wood, paper, cellulosic materials and synthetic resins. Examples describe compositions comprising aqueous dispersions of polyvinyl acetate, a vinyl acetate 2-ethylhexyl acrylate copolymer and black pigment. The acrylate may be replaced by butyl acrylate.ALSO:Substrates may be provided with strippable coatings by applying thereto aqueous dispersions of blends of a homopolymer of a vinyl ester and a copolymer of a vinyl ester and an alkyl acrylate containing up to 8 carbon atoms in the alkyl group. The coating compositions may also comprise pigments such as carbon black, lithopone, calcium carbonate and titanium dioxide, e.g. in proportions sufficient to render the coatings opaque. Specified substrates are steels, aluminium, copper, brass, nickel, glass, wood, paper, solid synthetic resins such as urea, melamine and phenolic resins, and cellulose acetate, polyester and polyolefin films. In examples gelatin coated cellulose acetate films are provided with strippable films by casting aqueous dispersions of polyvinyl acetate, vinyl acetate/2-ethyhexyl acrylate copolymers and carbon black.</p> |
