GB763367A - Process for the manufacture of dispersions of pulverulent substances - Google Patents

Abstract

A powder, e.g. a paint pigment, may be dispersed in a liquid, highly viscous or plastic medium by mixing together in any desired order said powder with said medium and a salt of an acid phosphoric acid ester of an aliphatic, cycloaliphatic, aromatic, aliphatic-aromatic or cycloaliphaticaromatic alcohol having at least 6 carbon atoms per molecule. Preferably the powder is impregnated with the salt of the acid phosphoric acid ester prior to dispersion, but the salt may be dispersed in the medium before, during or after the addition of the powder to the medium. Impregnation may be effected e.g. by stirring the powder into a solution or suspension of the salt in aqueous or organic media, separating off said powder and then drying; or by applying a solution in the form of spray or mist to a dry pigment; or by grinding and crushing the salts and powder in an edge-runner mill. After impregnation the powder is worked into the media, if desired at elevated temperature, (e.g. with normally solid materials) by known methods such as stirring or milling. Preferred proportions of the salts are 0.2 to 10 per cent, preferably 0.1 to 5 per cent by weight of the powder. The following powders are mentioned; inorganic oxides, hydroxides and salts, such as are used in varnishes and paints as colour pigments or blending agents: e.g. ochre, red lead, iron oxide, titanium oxide, zinc sulphide, barium sulphate, calcium carbonate; metal powders such as metal bronzes; fillers for rubber and rubber regenerates, such as carbon black, zinc oxide, finely dispersed silica, silica gel, calcium silicate dispersions or aluminium silicate dispersions; powder bases, such as talcum, rice flour, and starch; Fuller's earth, pumice stone powder, kaolin, alumina, active carbon, cork and wood powders. The following acid phosphoric acid esters are mentioned: acid mono-esters or di-esters of orthophosphoric acid which are derived from hexyl-, octyl-, dodecyl-, oleyl-, cyclohexyl-, alkylcyclohexyl-, naphthalenebenzyl-, menaphthyl-, or tetrahydromenapththyl-alcohols. The following are specified as bases for the acid esters: alkalimetal, alkaline earth metals, earth metals, amonia, acyclic and cyclic organic bases, such as dibutylamine, octylamine, trialkanolamines, cyclohexylamine, and dialkylcyclohexylamines. Mixtures of different phosphoric acid esters can also be used, as can mixtures of different salts, which may be derived, for example, from ammonia or organic bases and alkaline earth metals or earth metals. In examples (1) red iron oxide is dispersed in an ester gum-linseed oil varnish with the use of the cyclohexylamine salt of a mixture of acid phosphoric acid alkyl esters obtained by the action of phosphorous pentoxide upon a fatty alcohol mixture (2) silica gel is dispersed in crepe rubber, with the addition of zinc oxide, sulphur and mercaptobenzthiazol disulphide, with the aid of the triethanolamine salt of an acid dodecyl-tetrahydro-menaphthyl-phosphoric acid ester and (3) yellow ochre is dispersed in a linseed oil varnish using the dimethylcyclohexylamine salt of a mixture of acid mono- and di-oleylphosphoric acid esters.ALSO:A pulverulent filler may be dispersed in a natural rubber or rubber regenerate by mixing together in any desired order said powder with said rubber and a salt of an acid phosphoric acid ester of an aliphatic, cycloaliphatic, aromatic, aliphatic-aromatic or cycloaliphatic-aromatic alcohol containing at least 6 carbon atoms per molecule. Preferably the powder is impregnated with the salt of the acid phosphoric acid ester prior to dispersion but the salt may be dispersed in the rubber before, during or after the addition of the powder thereto. Impregnation may be effected e.g. by stirring the powder into a solution or suspension of the salt in aqueous or organic media, separating off said powder and then drying; or by applying a solution in the form of spray or mist to the dry powder; or by grinding and crushing the salt and powder in an edge-runner mill. After impregnation the powder is worked into the rubber, if desired at elevated temperature, by known methods such as milling. Preferred proportions of the salts are 0,2 to 10 per cent, preferably 0,1 to 5 per cent by weight of the powder. The following fillers are mentioned: soot, zinc oxide, finely dispersed silica, silica gel, calcium silicate dispersions and aluminium silicate dispersions. The following acid phosphoric acid esters are mentioned: acid monoesters or di-esters of orthophosphoric acid which are derived from hexyl-, octyl-, dodecyl-, oleyl-, cyclohexyl-, alkylcyclohexyl-, naphthalene-, benzyl-, menaphthyl-, or tetrahydromenaphthyl-alcohols. The following are specified as bases for the acid esters: alkali, alkaline earth and earth metals, ammonia, acyclic and cyclic organic bases, such as dibutylamine, octylamine, trialkanolamines, cyclohexylamine, and dialkylcyclohexylamines. Mixtures of different phosphoric acid esters can also be used, as can mixtures of different salts, which may be derived, for example, from ammonia or organic bases and alkaline earth metals or earth metals. In an example silica gel is dispersed in crepe rubber, with the addition of zinc oxide, sulphur and mercaptobenzthiazol disulphide, with the aid of the triethanolamine salt of an acid dodecyl - tetrahydro - menaphthyl - phosphoric acid ester.