GB1037304A - Aqueous paint compositions - Google Patents

Abstract

Titanium dioxide particles are coated with an organic aminohydroxy compound of formula <FORM:1037304/C1/1> wherein R and R1 are alkyl or hydroxy-substituted alkyl groups or where one is an alkyl or hydroxy-substituted alkyl group and the other is hydrogen. The aminohydroxy compound is added to water and the pigment in quantity at least 0.1%, or it may be incorporated at the fluid energy milling stage of the TiO2 manufacture. Anatase or rutile may be used, coated or uncoated, the preferred pigment being rutile coated with a metal and/or metalloid oxide, e.g. Al2O3, TiO2, CeO2, ZrO2 and/or SiO2 or with a phosphate. R and R1 may contain 1 to 5 C atoms, examples of the organic compound including 2-amino-1-butanol, 2 - amino - 2 - methyl - 1 - propanol, 2 - amino-2 - methyl - 1:3 - propanediol and tris(hydroxymethyl) aminomethane. In the production of coating compositions a film-forming material is also incorporated in the aqueous dispersion of TiO2.ALSO:In the production of coating compositions, a film-forming material is added either before or after the dispersion of titanium dioxide particles in an aqueous liquid in the presence of an organic aminohydroxy compound of general formula <FORM:1037304/C3/1> wherein R and R1 represent alkyl or hydroxysubstitute alkyl groups, or one may represent an alkyl or hydroxy-substituted alkyl group and the other hydrogen. Water-based stoving paints are prepared by dispersing the TiO2 in the presence of the aminohydroxy compound in a dilute solution of a water-soluble resin, e.g. an acrylic/melamine-formaldehyde or ureaformaldehyde resin, an alkyd/melamine-formaldehyde or urea-formaldehyde resin, a phenolic/alkyd-formaldehyde resin or an alkyd resin, by vigorous milling. More water-soluble resin may then be added. When preparing emulsion paints, the TiO2 is dispersed in water containing the aminohydroxy compound and an emulsified polymer mixture is then added, containing, e.g. polymers of vinyl esters of aliphatic monocarboxylic acids having 2 to 8 carbon atoms, such as vinyl acetate; polymers of acrylic or methacrylic esters of aliphatic monohydric alcohols containing from 1 to 10 carbon atoms such as methyl, ethyl, propyl, or butylacrylates or methacrylates; polymers of acrylonitrile; polymers of vinylidine chloride; polymers of styrene or butadiene or copolymers thereof, or copolymers of styrene or utadiene and diesters of maleic or fumaric acids and aliphatic monohydric alcohols containing 1 to 10 carbon atoms. Thickeni g agents such as cellulose ethers and/or polyacrylate salts, corrosion inhibitors, e.g. sodium benzoate or nitrite and/or film forming aids, e.g. cellulose or butyl carbitol acetate may be added to the resulting emulsion. In Example 1 aqueous dispersions of a rutile pigment coated with Al2O3 and TiO2 are prepared in the presence of (i) 2-amino-1-butanol, (ii) 2-amino-2-methyl-1-propanol, (iii) 2-amino-2-methyl-1,3-propanediol or (iv) tris-(hydroxymethyl) aminomethane and blended with polyvinyl acetate containing 15% dibutyl phthalate. In Example 2, a coated rutile pigment of the same type is ball milled with a melamineformaldehyde/acrylic resin, water and compound (i), (ii) or (iii).