Patent GB-423467-A (GB)
Title: Process of colouring oxide films on aluminium or on its alloys
IPC: C25D11/24
Filed: 1934-02-06
Abstract: An oxide film formed on aluminium or alloys thereof is coloured by treating the film with an organic dye containing a metal in complex combination.  The dyeing may take place simultaneously with the production of the film, and the complex combination of the metal with the dyestuff may take place in the dye bath; also, a solution of the metalliferous dye may be sprayed or painted on the surface, or a paste thereof may be applied by printing.  The oxide film may be obtained by electrolysis in a bath containing sulphuric, oxalic, or chromic acid, or ammonium bicarbonate, or by purely chemical action employing an acid or an alkaline bath containing a salt of chromic, hydrofluoric, or hydrofluosilicic acid and, if desired, a heavy metal salt, e.g. a tungstate, a uranate, or a titanate; an example of a chemical bath comprises potassium carbonate, potassium chromate, glycocoll, and water, the aluminium being treated at a temperature of 85--100 DEG  C. for ten to sixty minutes.  The following dyes may be used: the mono-metal compounds, e.g. the chromium, copper, nickel, cobalt, titanium, vanadium, manganese, or iron compounds of suitable mono- or poly-azo dyes, the poly-metal compounds of these dyes, the complex metal compounds of suitable anthraquinone derivatives, triarylmethane dyes, azines, thiazines, or oxazines, or the complex metal compounds of natural organic dyes such as those of young fustic, old fustic, Perian berries, turmeric, quercitron, ellagic acid, cochineal, logwood, or catechin.  The following examples are given: (1) Oxidized aluminium is coloured green by immersion in an aqueous solution of the complex chromium compound of the azo-dye 5-nitro-2-aminophenol --> 2-naphthylamine-6-sulphonic acid.  (2) Blue-violet is obtained by immersion in an aqueous solution of the complex copper compound of the azo-dye 5-nitro-2-aminophenol --> (alkaline) 2-phenylamino-5-oxynaphthalene-7-sulphonic acid.  By substituting the corresponding chromium, cobalt, and nickel compounds for the copper compound, blue, grey-blue, and blue-violet films respectively are produced.  (3) An oxide film on aluminium is coloured blue-violet by means of a dye containing chromium and copper from the disazo dye 2-amino-phenol-sulphaminobenzene (two mols.) \sQ 7 : 7<1>-disulpho-5 : 5<1>-dioxy-2 : 2<1>-dinaphthylamine in a bath of 2--10 per cent strength at 60--65 DEG  C.  (4) A vivid blue is produced by means of a dye prepared from five parts of the complex chromium compound of the sulphonated triarylmethane dyestuff from one mol. 2 : 6-dichloro-benzaldehyde and two mol. orthocresotinic acid per litre of liquor, either cold or at 50 DEG  C.  (5) An oxide layer coloured red is produced by anodic treatment in an aqueous bath containing oxalic acid and the complex chromium compound of the azo-dye 4-chloro-2-aminophenol-6-sulphonic acid --> 1-phenyl-3-methyl-5-pyrazolone.  (6) A green-blue colour is produced by immersing oxidized aluminium for fifteen minutes at 60 DEG  C. in a bath prepared with four parts of the chromium compound from 1 : 2 : 4 : 5 : 6 : 8-hexaoxyanthraquinone-3 : 7-disulphonic acid per litre of liquor.  (7) A violet tint is produced by immersion in an aqueous suspension of ten per cent strength of 1 : 2 : 5 : 8-tetraoxyanthraquinone at 40 DEG  C., an aqueous solution of copper sulphate being added and the liquid boiled for one hour. (8) A brown-orange tint is produced by means of an alcohol or acetone solution of 0,5 per cent strength of the complex nickel compound of the azo-dye 4-chloro-2-amino-phenol --> resorcinol. (9) Red is produced by immersion for thirty minutes at 40--45 DEG  C. in an aqueous, alcohol, or acetone solution of 1--10 per cent strength of the complex chromium and nickel compound (50 per cent of each) of the azo-dye 4-nitro-2-amino-1-phenol --> resorcinol; yellow is produced by using the complex chromium compound of the azo dye 4-nitro-2-amino-phenol-6-sulphonic acid --> acetoacetic acid anilide; violet by using the complex copper compound of the azo dye 1-amino-2-oxynaphthalene-4-sulphonic acid --> 1-oxynaphthalene; brown by using the chromiferous complex chromium compound of the azo dye 4-nitro-2-amino-1-phenol-6-sulphonic acid --> 2-oxynaphthalene; violet brown by using the complex cobalt compound of the azo dye 4-nitro-2-amino-1-phenol --> 2-aminonaphthalene, and black by using the complex iron compound of the azo dye 4-chloro-2-amino-1-phenol --> 2-oxynaphthalene.ALSO:An oxide film formed on aluminium or alloys thereof is coloured by treating the film with an organic dye containing a metal in complex combination.  The oxide film may be obtained by purely chemical action employing an acid or an alkaline bath containing a salt of chromic, hydrofluoric, or hydrofluosilicic acid and, if desired, a heavy metal salt, e.g. a tungstate, a uranate, or a titanate; an example of a chemical bath comprises potassium carbonate, potassium chromate glycocoll, and water, the aluminium being treated at a temperature of 80-100 DEG  C., for ten to sixty minutes.