Patent GB-459766-A (GB)
Title: Process for the production of azo dyestuffs on the fibre
IPC: D06P1/12
Filed: 1936-05-09
Abstract: Azo dyes, forming upon the material; printing; Schiff's bases.--Azo dyestuffs are prepared on the fibre by impregnating the fibre with an alkali salt of a coupling component and with a Schiff's base of the general formula R--N=CH--R<1>, where R is an aromatic radicle free from solubilizing groups and R<1> is a radicle containing at least one solubilizing group, and submitting the treated fibre to the action of diazotizing agents. Alternatively, the coupling component, the Schiff's base and an alkali nitrite are printed in the same paste on the fibre and the colour is then developed by acidification, e.g. by passage into a warm bath containing acid, by padding on the wrong side in the cold in an acid bath followed by drying on a drum at a higher temperature, by acid steaming in a Mather-Platt apparatus, or by ordinary steaming preceded by impregnation with acid vapours.  The fabric may be printed at the same time with other dyestuffs, e.g. substantive dyestuffs, basic dyestuffs, chrome colours or sulphuric esters of leuco derivatives of vat dyestuffs, or with other pastes capable of producing different effects on the fabric, e.g. for discharging or resist formation.  The Schiff's bases employed may be prepared by condensing a primary aromatic amine free from solubilizing groups with an aldehyde containing a solubilizing group or groups, e.g. an aliphatic, isocyclic or heterocyclic aldehyde containing one or more sulphonic or carboxylic groups or a collection of hydroxy groups, or by employing an aldehyde free from solubilizing groups and sulphonating the condensation product.  Suitable coupling components are the arylides of b -hydroxynaphthoic acid, of o-hydroxycarbazolecarboxylic acids, of o-hydroxynaphthocarbazolecarboxylic acids, of b -hydroxyanthracenecarboxylic acids or of acylacetic acids.  In examples: (1) sodium benzaldehyde-2 : 4-disulphonate is refluxed with p-toluidine in alcohol; alternatively, the condensation is effected in aqueous media; the product is mixed with b -hydroxynaphthoic acid anilide and sodium nitrite, the mixture is pasted with caustic soda and a thickening agent, the paste is printed on cotton and a red print is developed by acid steaming; (2) sodium benzaldehyde-o-sulphonate is used in the process of (1); (3) o-phthalaldehydic acid and m-chloraniline are refluxed in alcohol; the product, mixed with sodium nitrite and the sodium salt of a naphthol, is used to produce red-scarlet prints; (4) 4- or 5-chloro-o-toluidine is condensed with sodium benzaldehyde o-, m- or p-sulphonate by refluxing in alcohol; (5) sodium benzaldehyde-o-sulphonate and 4-chloro-o-toluidine are heated together to 130--140 DEG  C.; (6) m-chloraniline is employed in the process of (5); (7) cotton fabric is impregnated with a paste containing the product of (4), the o-toluidide or o-phenetidide of b -hydroxynaphthoic acid, sodium nitrite, sodium carbonate, alcohol, caustic soda, sodium sulphoricinate and gum tragacanth, and after drying a red or scarlet dyeing is developed by passage through a warm bath containing formic acid and sodium sulphate, or by padding on the wrong side in an aqueous bath containing formic acid, oxalic acid and sodium sulphate and then drying on a drum; (8) orange prints are produced by the use of a paste containing the product of (6), b -hydroxynaphthoic acid o-toluidide, alcohol, caustic soda, sodium sulphoricinate, sodium nitrite and gum tragacanth, developing being effected as in (7); (9) sodium benzaldehyde-2 : 4-disulphonate is condensed with 5-chloro-o-toluidine by boiling in aqueous alcohol; the product, mixed with 2 : 3-hydroxynaphthoic acid and sodium nitrite is used for printing as in the preceding examples; (10) the condensation product of salicylaldehyde with 4-chloro-o-toluidine is heated with concentrated sulphuric acid; the product, dissolved in caustic soda to which sodium nitrite is added, and mixed with a b -hydroxynaphthoic acid arylide, e.g. the o-toluidide, is used for the production of red prints; (11) 1-methyl-3-amino - 4 - methoxy - 6 - benzoylaminobenzene is refluxed with sodium benzaldehyde-o-sulphonate in alcohol; (2) 1 : 4-diethoxy-3-amino-6-benzoylaminobenzene is refluxed with sodium benzaldehydedisulphonate in ethyl or methyl alcohol; (13) violet or blue prints are obtained with pastes containing the product of (11) or (12), b -hydroxynaphthoic acid anilide, sodium nitrite, sodium carbonate, alcohol, caustic soda, sulphoricinate, thiodiglycol, and starchtragacanth thickening, with or without urea or sodium isopropylnaphthalenesulphonate, developing being effected by acid steaming; (14) sodium acetaldehydedisulphonate is refluxed with 4-chloro-o-toluidine in alcohol; (15) a solution of 4-chloro-o-toluidine and glucose in methyl alcohol is evaporated to small volume; (16) yellow prints are produced by the process of (7), using a paste containing the product of (14) or (15) and the p-toluidide of acetoacetic acid; (17) cotton fabric is printed with the paste of (7) and simultaneously with a paste comprising tannin and concentrated Methylene Blue N.B.I., dried, impregnated with acetic and formic acid vapours, steamed, passed through tartar emetic solution and soaped, yielding a red design on a background of blue design.