Patent GB-870994-A (GB)
Title: Aqueous emulsion copolymers and thickening procedures using them
IPC: C09D133/06
Filed: 1957-11-20
Abstract: Relates to a stable aqueous dispersion of a water-insoluble emulsion copolymer containing 25% to 70% by weight of methacrylic acid, at least 10% by weight of a copolymerized lower acrylate component constituted by one or more copolymerized acrylic acid esters of a C1 to C4 alcohol, and 0% to 40% by weight of one or more other copolymerized neutral monoethylenically unsaturated monomers, the dispersion containing a dispersing agent and having a solids concentration of from 25% to 50% by weight. The lower alkyl acrylate may be methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, isobutyl or t-butyl acrylate, and the other monomers include any other acrylate, methyl or butyl methacrylate, an itaconate, vinyl acetate, vinyl chloride, acrylonitrile, methacrylonitrile and styrene.  The copolymers may also incorporate from 0,1% to 0,8% by weight of a cross-linking agent, preferably divinyl benzene, diallyl phthalate or diallyl maleate, the Specification including a list of others which may be used.  The copolymers may be solubilized by neutralization with a base such as ammonia, sodium, potassium or lithium hydroxide, methylamine, trimethylamine, an ethylamine, monoethanolamine, diethanolamine, triethanolamine or piperidine.  The dispersing agent may be of the anionic or non-ionic type such as the higher fatty alcohol sulphates, alkali metal or amine salts of higher fatty acids, rosin soaps, sulphonated compounds, alkylphenoxypolyethoxy ethanols, polyethoxyethanol derivatives of methylene linked alkyl phenols, or ethylene oxide condensation products and other derivatives thereof. The copolymers may be produced by polymerization in aqueous emulsion in the presence of an initiator such as an alkali metal or ammonium persulphate or t-butyl hydroperoxide, preferably in the presence of a reducing agent such as sodium metabisulphite or a promoter such as iron or copper ions, preferred dispersing agents being sodium a -hydroxyoctadecane sulphonate, sodium lauryl sulphate and t-octylphenoxypolyethoxyethanol containing about ten oxyethylene units.  The dispersions of the invention may be used for thickening aqueous systems such as polymer dispersions, natural or synthetic rubber latices, aqueous coating compositions water-base paints, drilling muds, pigment suspensions, and may also be used as soil-conditioners and floc-stabilizers.  Polymer and synthetic rubber dispersions which may be stabilized include those of copolymers of butadiene with acrylonitrile or styrene, polystyrene, polyvinyl chloride, copolymers of vinyl chloride with vinylidene chloride, acrylonitrile or vinyl acetate, polyvinyl acetate, polyacrylates, polymethacrylates, or copolymers of acrylates or methacrylates with vinyl chloride, vinyl acetate, acrylonitrile or styrene. Specification 426,265 is referred to.ALSO:Thickeners for aqueous dispersions.  Aqueous dispersions of titanium dioxide or calcium carbonate are thickened by the addition of the sodium salt of a copolymer of 60% by weight ethyl acrylate, 40% methyl methacrylate and 0.2 or 0.25% (on the total of the other two monomers) of dialkyl phthalate.  Insoluble coatings.  To 24 parts by weight of a 40% solids aqueous dispersion of a copolymer of ethyl acrylate, methyl methacrylate and methacrylic acid in the proportions of 50:17:33 by weight, are added 73.8 parts of water and 2.2 parts of 28% ammonia; there is added a solution containing 4 parts of the dihydrate of zinc acetate and 4.4 parts of 28% ammonia, and the pH adjusted to about 9.5 with ammonium hydroxide.  The resulting solution may be coated on glass, wood, steel or aluminium panels and dried to yield a water-insoluble coating.  Specification 426,265 is referred to.ALSO:Soil conditioning.  An alkaline soil containing about 20% sand, 60% silt and 20% clay is sprayed with a 0,3% solids aqueous dispersion of the acid form of a copolymer of ethyl acrylate, methyl methacrylate and methacrylic acid in the proportions of 50 : 17 : 33 by weight, in such an amount that the soil sample contains 77% moisture and 0,10% polymer on the weight of the soil.  Aid for filtration and sedimentation.  A suspension containing 10 grams of kaolin per 100 c.c. in 0,18N sodium chloride at pH 7,6 has its settling rate increased and its filtration time reduced by incorporating into the suspension a dispersion having 40% solids concentration of the sodium salt form of the above copolymer, so as to provide 0,1% of the copolymer on the weight of clay. Specification 426,265 is referred to.