GB640502A - Improvements in or relating to emulsion paints - Google Patents

Abstract

An emulsion paint comprises a disperse phase containing an air-drying oil vehicle in which is dispersed a pigment in an amount of from 20-76 per cent by weight of the disperse phase, a continuous aqueous phase, an emulsifying agent and a naturally occurring organic colloid in an amount of from 4-14 per cent by weight of the disperse phase, and wherein the ratio of the oil vehicle to the colloid is between 6 : 1 and 11.5 : 1. Suitable oil vehicles include oleoresinous materials such as alkyd and linseed oil-modified alkyd resins, phenol-formaldehyde resins and drying-oil ester-gum compositions. A volatile solvent, e.g. xylol and/or white spirit, may be added to increase mobility. Preferred emulsifying agents are cation-active compounds such as quaternary ammonium compounds, ammonia or amides of long chain fatty acids. Specified pigments are titanium dioxide, lithopone and zinc oxide. The specified colloid is casein. Additional protective colloids of a synthetic nature such as methyl cellulose and sodium alginates may be added to the emulsion which may also contain preservatives for the colloids, antifoaming agents and driers. These include borax, caustic soda and cobalt and lead naphthenates. The emulsion is made by first dispersing the pigment in the oil by means of a mill, adding if necessary the volatile solvent and dispersing the paste in the aqueous medium preferably in a homogenizer mill at an elevated temperature. Specification 555,289 is referred to.ALSO:An emulsion paint comprises a disperse phase containing an air-drying oil vehicle in which is dispersed a pigment in an amount of from 20-76 per cent by weight of the disperse phase, a continuous aqueous phase, an emulsifying agent and a naturally occurring organic colloid in an amount of from 4-14 per cent by weight of the disperse phase and wherein the ratio of the oil vehicle to the colloid is between 6:1 and 11.5:1. A volatile solvent, e.g. xylol and/or white spirit, may be added to increase mobility. Suitable air-drying oil vehicles are stand oils and drying oils (e.g. linseed oil) which may include rosin and oleoresinous materials (see Group IV (a)). Preferred emulsifying agents are cation-active compounds such as quaternary ammonium compounds, ammonia or amides of long chain fatty acids. Specified pigments are titanium oxides, lithopone and zinc oxide. The specified colloid is casein. Additional protective colloids of a synthetic nature such as methyl cellulose and sodium alginates may be added to the emulsion which may also contain preservatives for the colloids, antifoaming agents and driers. These include borax, caustic soda and cobalt and lead naphthenates. The emulsion is made by first dispersing the pigment in the oil by means of a mill, adding if necessary the volatile solvent and dispersing the paste in the aqueous medium preferably in a homogenizer mill at an elevated temperature. Specification 555,289 is referred to.