| 摘要 |
<p>1,135,649. Coating compositions. UNITED SHOE MACHINERY CORP. 15 Dec., 1965 [18 Dec., 1964], No. 53160/65. Headings C3C, C3P and C3R. [Also in Division B2] Coating compositions suitable for depositing porous films comprise an aqueous dispersion of a film-forming polymeric material and fine droplets, of which from 30-60% have dimensions in the range of 0À001-0À003 mm. and substantially the remainder of said droplets have dimensions in the range of 0À003-0À010 mm., of a water-immiscible volatile organic liquid in which the polymeric material is insoluble or substantially insoluble, said liquid being suspended in the aqueous phase of said dispersion and being present in an amount of 25-300% based on the weight of said polymeric material. Preferred organic liquids are petroleum hydrocarbon fractions, e.g. mineral spirits, petroleum naphtha and kerosene; others mentioned are halogenated hydrocarbons and nitroparaffins. The polymeric material may be, for example, a latex of a butadiene-acrylonitrile copolymer which may be carboxylated, an acrylic ester polymer or copolymer emulsion, a latex of polyvinyl chloride or copolymer of vinyl chloride with e.g. vinyl acetate, or a latex of an elastomeric polyurethane, formed by reacting a polyester or polyether polyol with excess of a polyisocyanate and then chain extending the -NCO terminated condensate by reaction with a compound such as a polyol, polyamine or amino-alcohol. The composition may include a modifier to improve gel strength of the coatings, e.g. casein rendered water-soluble by treatment with an alkaline material, polyvinyl alcohol, methyl cellulose, and the insoluble resinous residue obtained from the distillation of pine tar resin. Other components which may be added include waxes or wax-like substances, gums, colouring agents, e.g. carbon black or zinc oxide, and mineral fillers. After a coating has been deposited on a surface, it is coalesced by evaporating water whereby the polymer particles gel; and when the solvent droplets are evaporated a porous coating is obtained.</p> |
