Procédé pour revêtir les feuilles de support non fibreuses, flexibles, au moyen de copolymères du chlorure de vinylidène

摘要

875,047. Coated flexible non-fibrous sheets. DU PONT DE NEMOURS & CO., E. I. Nov. 5, 1959 [Dec. 22, 1958], No. 37561/59. Class 140. Coated flexible non-fibrous base sheets are produced by coating the base sheet with an aqueous dispersion of particles of a copolymer containing at least 92.5 mol. per cent of vinylidene chloride, together with at least one other mono-olefinic monomer copolymerizable therewith, the dispersed copolymer particles being in such a condition that an infra-red absorption band at 13.3 microns appears within a period from 6 to 35 minutes after casting said dispersion into a self-supporting film, heating the coated base sheet to coalesce the coating and dry the coated sheet to a moisture content not greater than 14% by weight, and substantially immediately cooling the dried, coated base sheet to a temperature not higher than 25‹ C. The base sheet may be of regenerated cellulose, lowly etherified or esterified cellulose, e.g. cellulose acetate, nitrate or acetate-butyrate, polyethylene, polyethylene terephthalate, polyvinyl chloride or alcohol, casein, polyamides e.g. polyhexamethylene adipamide or sebacamide, polycaproamide and others described in U.S.A. Specifications 2,071,250 and 2,071,253. The copolymerizable mono-olefinic monomer may be general formula wherein R is hydrogen, halogen or a saturated aliphatic radical, and X is fluorine, chlorine or bromine, or a -CN, -C 6 H 5 , -COOH, -COOR1, -COR1, -COH, -OC 6 H 5' -CONH 2 , -CONHR1, or -CONR1 2 radical, R1 being an alkyl radical. Examples of suitable monomers are listed. The polymerization charge for producing the copolymer may include initiators, activators and accelerators (examples given), and an ethylenically unsaturated acid or acid anhydride e.g. citraconic or itaconic acids, or their anhydrides, or mixtures thereof obtainable from citric acid by distillation, acrylic, methacrylic or methyl methacrylic acid, which may be present in amount from 0.1 to 25% by weight of the total monomer charge. The aqueous dispersion may contain dispersing and stabilizing agents (examples given), and 0.1 to 1.0% by weight of hydrogen peroxide. The base sheet may be coated with an anchoring agent e.g. thermosetting aldehyde resins, titanium reaction products, polyisocyanates, polyurethanes, and polyimines (examples given) prior to the application of the aqueous dispersion.