GB437446A - Improvements in or relating to aqueous vinyl resin dispersions or emulsions and to their manufacture and use - Google Patents

Abstract

Stable, highly concentrated (i.e. over 30 per cent, e.g. 50--65 per cent) aqueous dispersions or emulsions of water-insoluble polymers or mixed polymers of unsaturated organic compounds containing one olefinic double linkage, e.g. acrylic acid and its homologues and derivatives thereof, vinyl esters, ethers and halides and styrols, are manufactured by concentrating an aqueous dispersion or emulsion of one or more of the said polymers containing one or more hydrophile groups (i.e. groups which give rise to water solubility in soaps, e.g. the groups COO Na, COOK and COONH4) in the substances constituting the disperse phase. The hydrophile group or groups may be introduced into the molecule of the polymer or polymers before, during or after polymerization. Thus the polymerization of emulsions of monomeric bodies may be carried out in the presence of small quantities of unsaturated substances containing hydrophile groups, such as water soluble monomeric salts of polymerizable acids, e.g. sodium acrylate. Alternatively compounds containing saponifiable groups may be partially saponified by the action of relatively small quantities of alkali before, during or after polymerization or emulsification. The concentration may be effected by centrifuging or by evaporation or both, if desired with the assistance of further chemical reagents. Specifically heavy solvents or swelling agents for the polymers may be added before concentration, whilst softening agents, e.g. phthalic acid esters, natural and artificial resins, oils, dyestuffs or other colouring matters and solvents may be added before, during or after polymerization and/or concentration. The products, if necessary after dilution with water to the desired viscosity may be employed for the production of coatings or layers on suitable surfaces, e.g. wood, metal, glass, leather or paper, for the production of films, e.g. for safety glass, for the production of intermediate layers of all kinds, as lacquers, impregnating agents for textiles and other porous material and for the production of electrical insulating materials. The films and coatings may be rendered resistant to water by treatment with acids or solution of salts which form water-insoluble salts with the hydrophile groups. In examples: (1) acrylic acid methyl and ethyl esters are polymerized in emulsion in water containing Turkey red oil, hydrogen peroxide and sodium acrylate, and the resulting dispersion is centrifuged; (2) a 25 per cent dispersion of polyacrylic acid methyl ester is warmed with a small amount of caustic soda and then centrifuged; the product, diluted to 50 per cent concentration, is suitable for the production of coatings on wood or other surfaces by painting or dipping; (3) as in (2) except that the concentration is effected by evaporation in vacuo; the product may be employed for the production of coatings on wood, metal and other materials which coatings may be rendered less sensitive to water by treatment with alum solution or dilute hydrochloric acid; (4) as in (3) except that the saponifying agent is ammonia; films and coatings from the product may be made resistant to water by heating; (5) acrylic acid methyl ester is polymerized in emulsion in water containing Turkey red oil, hydrogen peroxide and acrylic acid and the product is neutralized with ammonia and concentrated by evaporation in vacuo. The Provisional Specification comprises also the concentration of the emulsions or dispersions by mechanical means alone. In an additional example, a 25 per cent dispersion of polyacrylic acid methyl ester is shaken up with a softening agent and then centrifuged. The product is suitable for the production of films, especially for safety glass.ALSO:Stable, highly concentrated (i.e. over 30 per cent. e.g. 50--65 per cent) aqueous dispersions or emulsions of water-insoluble polymers or mixed polymers of unsaturated organic compounds containing one olefinic double linkage, e.g. acrylic acid and its homologues and derivatives thereof, vinyl esters, ethers and halides and styrols, are manufactured by concentrating an aqueous dispersion or emulsion of one or more of the said polymers containing one or more hydrophile groups (i.e. groups which give rise to water solubility in soaps, e.g. the groups COONa, COOK and COONH4) in the substances constituting the disperse phase. The hydrophile group or groups may be introduced into the molecule of the polymer or polymers before, during or after polymerization. Thus the polymerization of emulsions of monomeric bodies may be carried out in the presence of small quantities of unsaturated substances containing hydrophile groups, such as water soluble monomeric salts of polymerizable acids, e.g. sodium acrylate. Alternatively compounds containing saponifiable groups may be partially saponified by the action of relatively small quantities of alkali before, during or after polymerization or emulsification. The concentration may be effected by centrifuging or by evaporation or both, if desired with the assistance of further chemical reagents. Specifically heavy solvents or swelling agents for the polymers may be added before concentration, whilst softening agents, e.g. phthalic acid esters, natural and artificial resins, oils, dyestuffs or other colouring matters and solvents may be added before, during or after polymerization and/or concentration. The products, if necessary after dilution with water to the desired biscosity, may be employed for the production of coatings or layers on suitable surfaces, e.g. wood, metal, glass, leather or paper, for the production of films, e.g. for safety glass, for the production of intermediate layers of all kinds, as lacquers, impregnating agents for textiles and other porous material and for the production of electrical insulating materials. The films and coatings may be rendered resistant to water by treatment with acids or solutions of salts which form water-insoluble salts with the hydrophile groups. In example: (1) acrylic acid methyl and ethyl esters are polymerized in emulsion in water containing turkey red oil, hydrogen peroxide and sodium acrylate, and the resulting dispersion is centrifuged; (2) a 25 per cent dispersion of polyacrylic acid methyl ester is warmed with a small amount of caustic soda and then centrifuged; the product, diluted to 50 per cent concentration, is suitable for the production of coatings on wood or other surfaces by painting or dipping; (3) as in (2) except that the concentration is effected by evaporation in vacuo; the product may be employed for the production of coatings on wood, metal and other materials, which coatings may be rendered less sensitive to water by treatment with alum solution or dilute hydrochloric acid; (4) as in (3) except that the saponifying agent is ammonia; films and coatings from the product may be made resistant to water by heating; (5) acrylic acid methyl ester is polymerized in emulsion in water containing turkey red oil, hydrogen peroxide and acrylic acid and the product is neutralized with ammonia and concentrated by evaporation in vacuo. The Provisional Specification comprises also the concentration of the emulsions or dispersions by mechanical means alone. In an additional example, a 25 per cent dispersion of polyacrylic acid methyl ester is shaken up with a softening agent and then centrifuged. The product is suitable for the production of films, especially for safety glass.