Patent GB-611321-A (GB)
Title: Improvements in and relating to the colouring of textile fibres by means of water insoluble dyestuffs
IPC: D06P1/02
Filed: 1946-01-22
Abstract: Textile fibres (e.g. wool, silk, cotton or rayon) are coloured by applying thereto (e.g. by dyeing, foularding or printing) azo dyestuffs, the only solubilizing groups of which are sulphonic groups linked to nitrogen atoms of secondary amino groups, and submitting the fibres to an acid treatment (whereby the sulphonic acid groups are split-off and the dyestuffs rendered insoluble in water).  In the acid dyeing of animal or artificial fibres, the bath should be not too acid if simultaneous developing of the dye is to be avoided (which requirement may be achieved by the addition of a reagent such as borax, and acetate, e.g. sodium or ammonium acetate, or soap), though in certain cases development may be effected simultaneously with dyeing.  In the application of the dyes by foularding or printing, the solutions and colours containing the dyes may contain other usual ingredient, especially solubilizing or hygroscopic substances.  Development may be effected by steeping in a bath showing the desired acidity at a suitable temperature, by passage through an acid atmosphere of a substance rendered acid thereby, e.g. salts of volatile bases such as ammonium salts, esters regenerating their acid through hydrolysis, or certain salts such as fluorosulphorates or iminodisulphorates.  Examples describe (1) the dyeing of wool yarn from a bath containing ammonium acetate and developing with dilute sulphuric acid in the same or a different bath; (2) and (3) the dyeing of loaded or non-loaded silk from a bath containing soap or borax and developing similarly; (4) and (5) the printing of cotton fabric with a paste containing thiodiglycol, acetin, urea and starch-tragacanth thickener and developing in a boiling bath containing sulphuric acid and sodium sulphate or in saturated steam containing acetic acid, and (6) the printing of cotton with a paste containing thiodiglycol, ammonium sulphocyanide and starch-tragacanth thickener and developing by steaming, using certain of the dyestuffs described in Specification 611,320, or the following alternative dyestuffs: 1 : N2-dimethyl-2 : 4-diaminobenzene-N2 : N4-disulphonic acid --> 2-hydroxynaphthocarbozole-3-carboxylic acid p-anisidide or 2 : 3-hydroxynaphthoic acid 2-methyl-4-methoxyanilide; the same diazo component or N1-methyl-1 : 4-diaminobenzene-N1 : N4-disulphonic acid or N1-(41-methoxy phenyl) - 1 : 4 - diaminobenzene - N1 : N4 - disulphonic and \sQ di-(2 : 3-hydroxynaphthoyl)-dianisidine.  In (5), a shade approaching black is obtained with a mixture of the dyestuff from the last-named diazo component and 2 : 3-hydroxynaphthoic acid o-anisidide and that from the same diazo component and di-(acetoacetyl)-o-tobidine.  The Specification as open to inspection under Sect. 91 comprises also the application of the acid treatment to the dyestuffs in substance, in an example of which the dyestuff from 41-methoxy - N - phenyl - 4 - amino - 1 - diazobenzene-N-sulphonic acid and 2 : 3-hydroxynaphthoic acid o-anisidide is boiled with dilute sulphuric acid.  This subject-matter does not appear in the Specification as accepted.