Patent GB-1113990-A (GB)
Title: Improvements in and relating to the treatment of pigments
Inventor: FELD RAOUL
IPC: C09C1/36
Filed: 1964-07-22
Abstract: A pigment comprises paraticles which have been contacted with 0.1-5% wt. of an ester of a carboxylic acid which acid contains at least two hydroxy groups and at least one carboxylic acid group, all of the carboxylic acid groups present in the compound being esterified.  The hydroxy groups may be on adjacent carbon atoms.  The compound may contain two carboxylic acid ester groups, e.g. a dihydroxy dicarboxylic acid ester.  The ester group of the compound may be an alkyl, e.g. of 2 to 20 C atoms, aryl, aralkyl or cycloalkyl group. Diesters of dihydroxy maleic acid or tartaric acid and n-propyl gallate are specifically referred to.  The particles may be treated by contact with the liquid compound or a solution of the solid or liquid compound in a solvent, e.g. alcohol, acetone or water.  The treated particles may be dried at 120 DEG  C. and may be milled.  The pigment particles may be TiO2 which may have small quantities of a hydrated metal oxide on the surface, e.g. hydrated Al2O3 or TiO2 or may be SiO2, blanc fixe, lithopone, BaCO3, ZrO2, ZnO, Al2O3, chrome yellow or phthalocyanine.  The particles preferably preclassifed before being treated. Alternatively the particles may be treated during a wet-milling operation.  The treated pigments can be incorporated in paint or lacquer media e.g. acrylic or alkyd media. In the Examples the treated pigment is mixed with an oil paint consisting of linseed oil pentaerythritol modified alkyd resin, soya lecithin oil and white spirit or long oil soyapentaerythritol modified alkyd resin.ALSO:A pigment comprises particles which have been contacted with 0.1-5% wt. of an ester of a carboxylic acid which acid contains at least two hydroxy groups and at least one carboxylic acid group, all of the carboxylic acid groups present in the compound being esterified.  Di-esters of dihydroxy maleic acid or tartaric acid and n-propyl gallate are specifically referred to. The particles may be treated by contact with the liquid compound or a solution of the solid or liquid compound in a solvent, e.g. alcohol, acetone or water.  The treated particles may be dried at 120 DEG  C. and may be milled.  The pigment particles may be lithopone or phthalo-cyanine.ALSO:A pigment comprises particles which have been contacted with 0.1-5% weight of an ester of a carboxylic acid which acid contains at least two hydroxy groups and at least one carboxylic acid group, all of the carboxylic acid groups present in the compound being esterified.  The hydroxy groups may be on adjacent carbon atoms.  The compound may contain two carboxylic acid ester groups e.g. a dihydroxy dicarboxylic acid ester.  The ester group of the compound may be an alkyl, e.g. of 2 to 20 C atoms, aryl, aralkyl or cycloalkyl group.  Diesters of dihydroxy maleic acid or tartaric acid and n-propyl gallate are specifically referred to. The particles may be treated by contact with the liquid compound or a solution of the solid or liquid compound in a solvent e.g. alcohol, acetone or water. The treated particles may be dried at 120 DEG  C. and may be milled. The pigment particles may be TiO2 which may have small quantities of a hydrated metal oxide on the surface e.g. hydrated Al2O3 or TiO2 or may be SiO2, blanc fixe, lithopone, BaCO3, ZrO2, ZnO, Al2O3, chrome yellow or phthalocyanine.  The particles are preferably preclassified before being treated. Alternatively the particles may be treated during a wet-milling operation.