Patent GB-670190-A (GB)
Title: Non-flocculating phthalocyanine pigmented cellulose nitrate coating compositions
IPC: C09D101/18
Filed: 1949-05-17
Abstract: A non-flocculating phthalocyanine pigmented cellulose nitrate coating composition is obtained by including in the composition at least 0.2 per cent, based on the weight of the composition, of ethyl or methyl cellulose or dynamite cellulose nitrate, i.e. a cellulose nitrate of the kind used for making explosives and characterized by a nitrogen content of 12.15 to 12.35 per cent, very high viscosity (40-200 seconds in a 3 per cent solution in acetone by a specified standard method), and by the tendency of its solutions to form a gel structure or false body.  The addition of the substances specified inhibits the tendency of phthalocyanine pigments ("Monastral Blues and Greens"), to flocculate and separate out of the coating compositions on standing for a short time, e.g. 1-2 hours.  The anti-flocculating agent may be incorporated at any stage of the manufacture, e.g. with the phthalocyanine pigment in the dispersion stage, or with another pigment dispersion which is to be used as a tinting agent, or it may be added to the pigmented lacquer.  In an example, a phthalocyanine blue pigment is incorporated in an intermediate lacquer with cellulose nitrate ( 1/4 second Hercules), blown castor oil, and dibutyl phthalate, and this lacquer is diluted with solvents and a hydrogenated castor oil modified alkyd resin. To this lacquer there is added a tinting lacquer containing titanium dioxide, cellulose nitrate, alkyd resin, blown castor oil dibutyl phthalate, solvents, and diluents, and also a solution of ethyl cellulose (of ethoxyl content 43-45 per cent and a viscosity of 50 centipoises for a 5 per cent solution in a mixed solvent containing 70 parts of toluene and 30 parts of ethyl alcohol).  The resulting lacquer contains 0.5 per cent of ethyl cellulose.  The solvents and diluents used include ethyl alcohol, butyl alcohol, butyl acetate, methyl ethyl ketone, methyl isobutyl ketone, methyl isobutyl carbinol, petroleum naphtha, petroleum xylol, and toluene.  In another example, a pigmented intermediate is obtained by mixing dry cellulose nitrate with a chlorinated phthalocyanine green pigment, blown castor oil and dibutyl phthalate, and this composition is diluted with additional vehicle including a coconut oil modified glycerol phthalate resin, and malic acid.  The tinting lacquer so obtained is mixed with a titanium dioxide tinting lacquer and with ethyl cellulose.  In another example, a lacquer is prepared by mixing cellulose nitrate, ethyl cellulose, ester gum, damar resin, citric acid, titanium dioxide, phthalocyanine blue pigment, and solvents, plasticizers, and diluents.  In another example, a lacquer containing phthalocyanine blue pigment, cellulose nitrate, oil modified glycerol phthalate resin, plasticizers, and solvents, is mixed with a titanium dioxide lacquer containing cellulose nitrate, oil modified alkyd resin, dynamite cellulose nitrate, and solvents, diluents and plasticizers. Instead of titanium dioxide, other pigments, e.g. bone black, chrome yellow, or aluminium powder, may be used to shade the phthalocyanine lacquers. Specification 499,790 is referred to.