| 摘要 |
795,780. Moistureproof coatings. BRITISH CELLOPHANE, Ltd. Oct. 8, 1956 [Oct. 12, 1955], No. 29109/55. Addition to 703,010. Class 140. Moistureproof film, sheet or like material is produced by applying to a base film of a watersensitive non-fibrous organic material, e.g. regenerated cellulose, lowly substituted cellulose ether or ester, alginic acid derivative, polyvinyl alcohol, gelatine or casein, a partially condensed hydrophilic urea-formaldehyde resin from an aqueous dispersion of pH 5 to 2, drying the treated film without curing the applied resin to an hydrophobic state and then applying to the dried film an aqueous dispersion of vinylidene chloride copolymer of pH 5 to 8 and finally heating to evaporate the water, cure the applied resin to an hydrophobic state and to consolidate the surface coating. The vinylidene chloride copolymer comprises 92 to 96 per cent vinylidene chloride. 7¥ to 2 per cent of methyl methacrylate, acrylonitrile and ethyl acrylate or any two or all three of said compounds, and itaconic or citraconic acid or anhydride or mesaconic acid or mixtures thereof. The water is finally removed from the coated film by heating until 14 per cent of less (based on the weight of the oven dry film) remains. The term " urea " includes " thiourea " and the term " urea formaldehyde " includes " urea-formaldehydealiphatic alcohol resins. |
