Patent GB-599490-A (GB)
Title: Pigments
IPC: C09B57/10
Filed: 1944-02-03
Abstract: Pigments, most of which are fluorescent and some also paramagnetic, are manufactured by condensing an inner metallic complex (the metal of which has a valency greater than one) of 8-hydroxyquinoline or a substitution product thereof (not bearing substituents containing azo groups) upon an undissolved substratum, which may be paramagnetic substance and is preferably at least slightly basic, e.g. by (a) adding an alkali or an alkaline-reacting material to a suspension of the substratum in a concentrated solution of the 8-hydroxyquinoline compound and a salt of the metal, or (b) adding to such concentrated solution a substratum which, though normally insoluble, is capable of acting as a precipitating agent by partial dissolution, or (c) adding to such concentrated solution, in which the metal salt is in excess, a quantity of an alkali or an alkaline-reacting material sufficient to precipitate the metal complex and simultaneously the hydroxide of the metal by reaction with the excess of metal salt, or (d) treating a concentrated solution of the 8-hydroxyquinoline compound and a salt of a first metal of valency greater than one with a hydroxide or an alkaline-reacting salt of a second metal which forms an insoluble substratum by reaction with the acid radical of the first salt, or (e) treating a concentrated solution of the 8-hydroxyquinoline compound with excess of an alkaline-reacting oxide of the metal.  In examples: (1) red magnetic iron oxide is suspended in an ethanolic solution of 8-hydroxyquinoline and zinc nitrate, and an aqueous ethanolic solution of potassium hydroxide is added to precipitate a paramagnetic pigment with a yellow-green fluorescence in ultra-violet radiation; (2) the iron oxide in (1) is replaced by titanium dioxide and the 8-hydroxyquinoline by its 7-methyl derivative; (3) a suspension of magnesium oxide in aqueous ethanol is stirred with an ethanolic solution of 8-hydroxyquinoline and zinc nitrate; (4) the magnesium oxide in (3) is replaced by alumina; (5) an aqueous ethanolic solution of sodium hydroxide is added to a concentrated ethanolic solution of 5 : 7-dichloro-8-hydroxyquinoline and excess of aluminium sulphate, producing a pigment which has a bright yellow fluorescence in ultraviolet radiation; (6) barium hydroxide hydrate is added to a concentrated aqueous ethanolic solution of 8-hydroxy quinoline and zinc sulphate to form a pigment with a barium sulphate substratum, which fluoresces whitish-green; (7) excess of zinc oxide is added to a stirred solution of 8-hydroxyquinoline in ethanol. Additional starting materials are, one the one hand, compounds of calcium, cadmium, copper beryllium and magnesium, and, on the other hand, 2-, 5- and 6-methyl- and 5-amino-8-hydroxyquinoline, and the diazaphenanthrene obtained by condensing 5-amino-8-hydroxyquinoline with glycerine in the presence of sulphuric acid according to the Skraup synthesis.  The Specification as open to inspection under Sect. 91 comprises also the use, as starting materials, of azo derivatives of 8-hydroxyquinoline, e.g. its 5-benzeneazo derivative. This subject-matter does not appear in the Specification as accepted.