Patent GB-580205-A (GB)
Title: Improvements in textile printing
IPC: D06P5/15
Filed: 1944-06-16
Abstract: Printing; regenerated celluloses, dyeing.-In the discharge printing of fabrics of animal or cellulosic fibre, e.g. wool, silk, cotton or cuprammonium or viscose artificial silk, by dyeing or printing them with an azo dyestuff and then discharging portions thereon by printing with a discharge paste containing a reducing agent, the purity of the white pattern is enhanced by treating the fabric, or at least that portion of it which is to receive the discharge paste, with a small proportion (e.g. 0.02 to 0.2 per cent calculated on the weight of the treated portions of the fabric) of the free acid or a water-soluble salt of 4 : 41-di-(benzoylamino)-stilbene-2 : 21-disulphonic acid or a substitution product thereof substituted in the benzoyl nuclei, before, during or after, or after the operation of colouring or discharging.  Conveniently, the stilbene derivative may be incorporated in the discharge paste, which may be applied by machine printing, screen printing or spray printing.  The initial dyeing may be effected by processes appropriate to the fabric treated, e.g. on cotton fabrics by means of direct cotton azo dyestuffs or by the formation of insoluble azo pigments on the fibre, or on wool by acid azo dyestuffs or by those used with mordants, e.g. chrome mordants.  In examples: (1) cotton fabric is dyed brown with the trisazo dyestuff salicylic acid \sM benzidine --> m-toluylenediamine \sM sulphanilic acid, printed with a discharge paste containing sodium formaldehyde sulphoxylate dihydrate, gum tragacanth thickening, the sodium salt of 4 : 41-bis - (p - aminobenzoylamino) - stilbene - 2 : 21 - disulphonic acid and sodium carbonate, dried, steamed and rinsed; (2) the dyestuff in (1) is replaced by the black dyestuff 4 : 41-diaminodiphenylamine - 2 - sulphonic acid (1 mol.) \sQ (alkaline) gamma-acid (2 mols.) \sQ (alkaline) m-phenylenediamine (2 mols.); (3) the dyestuff in (1) is replaced by the pink dyestuff obtained by reduction and phosgenation of the dyestuff p-nitraniline-o-sulphonic acid --> gamma-acid; (4) cotton fabric dyed as in (1) is padded with an aqueous solution of the stilbene derivative of (1) and then printed with a discharge paste containing sodium formaldehyde sulphoxylate and gum tragacanth thickening, dried, steamed, rinsed and dried; (5) in the process of (4), the treatment with the stilbene derivative is applied at the end of the process; (6) viscose artificial silk fabric is dyed black with the dyestuff of (2) from a bath containing the stilbene derivative of (1), printed with the discharge paste of (4), dried, steamed, rinsed and dried; (7) scoured chlorinated wool fabric is dyed violet or red with the chromium complex of the dyestuff 4-chloro-2-anisidine --> 2-naphthol-6 : 8-disulphonic acid or 4-chloro-2-aminophenol-6-sulphonic acid --> 1-phenyl-3-methyl-5-pyrazolone, printed with a discharge paste containing sodium formaldehyde sulphoxylate dihydrate, zinc formaldehyde sulphoxylate, glycerol, gum tragacanth thickening, sodium citrate, the stilbene derivative of (1) and sodium carbonate, dried, steamed, rinsed, soaped, rinsed and dried; (8) natural silk twill fabric is dyed with the second chromium compound of (7), printed with a discharge paste containing sodium formaldehyde sulphoxylate dihydrate, gum senegal thickening, sodium citrate, the stilbene derivative of (1) and sodium carbonate, dried, steamed, rinsed and dried.  Other dyestuffs suitable for producing the ground colour are: 4-nitro-2-aminoanisole --> (on the fibre) the m-nitroanilide of 2 : 3-hydroxynaphthoic acid (red shades on cotton or viscose artificial silk); dianisidine \sQ (alkaline) 1-amino-8-naphthol-2 : 4-disulphonic acid (blue, for cotton or viscose artificial silk); aniline --> (alkaline) H-acid (acid) \sM benzidine --> m-phenylenediamine or phenol (black and dark green, for cotton). Other stilbene derivatives specified are 4 : 41-bis-(p-acetylaminobenzoylamino)-stilbene-2 : 21-disulphonic acid and 4 : 41 - bis - (p - ureidobenzoylamino) - stilbene - 2 : 21 - disulphonic acid (obtainable by condensing 4 : 41 - bis - (p - aminobenzoylamino) - stilbene 2 : 21-disulphonic acid and sodium cyanate in aqueous medium in the presence of a small quantity of acetic acid).