Patent GB-955283-A (GB)
Title: Pigment treatment process
Inventor: DEVERELL-SMITH RAYMOND
IPC: C09C3/08
Filed: 1961-07-03
Abstract: A process for making pigments more suitable for incorporation in " waxless carbon papers " comprises treating with a cationic dispersing agent, an aqueous dispersion of a pigment containing an anionic dispersing agent which dissolves in water to give a 0.2% by weight solution having a surface tension of at least 40 dynes per centimetre.  The pigment may be carbon black or an organic pigment of the azo, phthalocyanine, anthroquinone, thioindigoid or polycyclic series or complete lakes of basic dyestuffs, e.g. Victoria Pure Blue and Methyl Violet.  The anionic dispersing agents specified are sodium salts of formaldehyde-naphthalene sulphonic acid condensates and lignin sulphonic acids; and the cationic dispersing agents, quaternary ammonium compounds having a higher aliphatic hydrocarbon radical (e.g. octyl, dodecyl, cetyl, octadecyl, oleyl and abietyl), e.g. cetyl trimethyl ammonium bromide, cetyl dimethylethyl ammonium ethylsulphate and cetyl pyridinium bromide, betaines, e.g. octadecyl betaine, and octadecylamine hydrochloride. In the examples an aqueous dispersion of carbon black or a phosphotungstomolybdic acid lake of Methyl Violet or Victoria Pure Blue containing the sodium salt of formaldehyde-naphthalene sulphonic acid condensate is mixed with an aqueous solution of cetyl pyridinium bromide, octadecylamine hydrochloride, diphenyl guanidine hydrochloride or cetyl dimethyl ammonium ethylsulphate and then dried.  The pigments so formed are dispersed in oil (mineral, vegetable or animal) and mixed with a copolymer of vinyl acetate and chloride, toluene and methyl ethyl ketone and used to coat tissues to produce waxless carbon papers.ALSO:A composition for coating paper tissues to produce waxless carbon papers comprises a copolymer of vinyl acetate and vinyl chloride, oil (mineral, animal or vegetable), and a pigment which has been prepared by treating with a cationic dispersing agent, an aqueous dispersion of the pigment containing an anionic dispersing agent which dissolves in water to give a 0.2% by weight solution having a surface tension of at least 40 dynes per centimetre.  The pigment may be carbon black or an organic pigment of the azo, phthalocyanine, anthroquinone, thioindigoid or polycyclic series or complete lakes of basic dyestuffs.  The anionic dispersing agents specified are the sodium salts of formaldehyde - naphthalene sulphonic acid condensates and lignin sulphonic acids; and the cationic dispersing agents specified are cetyl trimethylammonium bromide, cetyldimethylethyl ammonium ethyl sulphate, cetyl pyridinium bromide, octadecyl betaine, octadecylamine hydrochloride and diphenyl guanidine hydrochloride.ALSO:A process for making pigments more suitable for incorporation in "waxless carbon papers" comprises treating with a cationic dispersing agent, an aqueous dispersion of a pigment containing an anionic dispersing agent which dissolves in water to give a 0.2% by weight solution having a surface tension of at least 40 dynes per centimetre.  The pigment may be carbon black or an organic pigment of the azo, phthalocyanine, anthroquinone, thioindigoid or polycyclic series or complete lakes of basic dyestuffs, e.g. Victoria Pure Blue and Methyl Violet.  The anionic dispersing agents specified are sodium salts of formaldehyde-naphthalene sulphonic acid condensates and lignin sulphonic acids; and the cationic dispersing agents, quaternary ammonium compounds having a higher aliphatic hydrocarbon radical (e.g. octyl, dodecyl, cetyl, octadecyl, oleyl and abietyl), e.g. cetyl trimethyl ammonium bromide, cetyl dimethylethyl ammonium ethylsulphate and cetyl pyridinium bromide, betaines, e.g. octadecyl betaine, and octadecylamine hydrochloride.  In the examples an aqueous dispersion of carbon black or a phosphotungstomolybdic acid lake of Methyl Violet or Victoria Pure Blue containing the sodium salt of formaldehyde-naphthalene sulphonic acid condensate is mixed with an aqueous solution of cetyl pyridinium bromide, octadecylamine hydrochloride, diphenyl guanidine hydrochloride or cetyl dimethyl ammonium ethylsulphate and then dried.  The pigments so formed are dispersed in oil (mineral, vegetable or animal) and mixed with a copolymer of vinyl acetate and chloride, toluene and methyl ethyl ketone and used to coat tissues to produce waxless carbon papers.ALSO:Into waxless carbon papers are incorporated pigments prepared by treating with a cationic dispersing agent an aqueous dispersion of the pigment containing an anionic dispersing agent which dissolves in water to give a 0.2% by weight solution having a surface tension of at least 40 dynes per centimetre.  The pigment may be carbon black or an organic pigment of the azo, phthalocyanine, anthraquinone, thioindigoid or polycyclic series or complete lakes of basic dyestuffs, e.g. Victoria Pure Blue and Methyl Violet.  In the examples the treated pigments are dispersed in oil (mineral, vegetable or animal) and mixed with a copolymer of vinyl acetate and vinyl chloride, toluene and methyl ethyl ketone and the resultant compositions are used to coat tissues to produce waxless carbon papers.