| 摘要 |
1,222,985. Coated sheet material. ARTHUR D. LITTLE, Inc. 10 May, 1968 [15 May, 1967], No. 22396/68. Heading B2E. A high gloss coating may be formed on a fibrous substrate by (a) forming an oil-in-water emulsion comprising an aqueous dispersion of a film-forming binder material as continuous phase and a water-imiscible volatile liquid which is essentially a non-solvent for the binder material as discontinuous phase and which has a boiling point which is not less than that of water, the binder being susceptible to moulding under heat and pressure and capable of forming an opaque film in the form of a bubble structure, substantially all the globules of the water-imiscible liquid in the emulsion being no greater than 1 micron, (b) applying a film of said emulsion to the surface of a substrate, (c) stabilising the structure of the applied emulsion film by evaporating first a portion of the water of the emulsion and forming a matrix of film-forming binder material having distributed throughout minute globules of water-imiscible liquid, the dimensions of which remain substantially the same as those of the continuous phase in the emulsion film, (d) evaporating substantially all of any remaining water from the matrix and evaporating the water-imiscible liquid and the globules to provide multitudinous air-binder interfaces to create a broken bubble structure within the essentially continuous film, substantially all of the interfaces being no greater than 1 micron in dimension so that there is formed a bright, opaque coating on the substrate, (e) treating the surface of the coating to superficial smoothing of the surface without essentially altering the bubble structure and (f) calendering the resulting surface at a elevated temperature at at least 100 lbs. per linear inch to form a high-gloss coating, the conditions of the calendering being such that the bubble structure is not substantially destroyed. The substrate may be a bleached sulphite web. The coating may be by means of an air-knife. Finely divided particulate material may be present in a coating layer, for example, titanium dioxide. The binder may be a protein, such as casein, soya protein, zein, animal glue or gelatines, waterdispersable elastomers such as natural and synthetic rubbers, water-soluble, film-forming synthetic resins, e.g. polyvinyl alcohols, and water-dispersable thermoplastic resins, e.g. polyacrylates, polyvinylacetates, and chlorides, copolymers of vinyl acetate and vinyl chloride, of vinyl acetate and ethylene and copolymers of acrylates. Pigments and ink absorbers may be present and the same material may serve both functions. |
