Patent GB-410498-A (GB)
Title: Improvements in or relating to the colouration of cellulose esters and ethers
IPC: D06P3/34
Filed: 1932-10-08
Abstract: Cellulose esters and ethers, dyeing; printing.--  Cellulose esters or ethers are coloured by applying thereto in substance dyestuffs obtainable by coupling diazo compounds obtained by diazotizing 4-amino-3-nitro-benzenes substituted in the 1-position by an alkyl or alkoxy group or halogen with 3-amino-1-alkyl compounds of the benzene series capable of coupling in the p-position to the amino group, yellow to orange shades being obtained, which are readily dischargeable by means of reducing discharging agents, e.g. stannous chloride discharges or zinc formaldehyde sulphoxylate discharges. Suitable components are: diazo components: 4-amino-3-nitrotoluene, 4-amino-3-nitro-1-methoxy- or 1-ethoxybenzene and 4-amino-3-nitro-1-chlorobenzene; coupling components: m-toluidine, monoamino - 1 : 4 - dialkylbenzenes, e.g. p-xylidine, and p-cresidine, or N-alkyl derivatives thereof, e.g. dimethyl-m-toluidine.  The process is applicable to the production of dischargeable black shades by colouring the materials with the dyestuffs specified and also with navy blue dyestuffs, e.g. by first dyeing the materials in navy blue shades and then topping with the yellow or orange dyestuffs specified.  The process is applicable to the colouration of cellulose acetate, formate, propionate or butyrate or other esters, or the ethyl, benzyl or other ethers of cellulose, and also to the colouration of the cellulose derivative portion of mixed materials containing cellulose esters and ethers in admixture with other textile fibres, e.g. wool, silk or other animal fibres, or cotton, regenerated cellulose or other cellulosic materials, which other fibres may be coloured in the same or different shades either before, after or simultaneously with the colouration of the cellulose esters or ethers, or, according to the Provisional Specification, they may be coloured by the same dyestuffs as the cellulose derivatives when they possess the requisite affinity. The colouring matters may be applied to the materials in the form of aqueous suspensions or dispersions, or from solutions in organic solvents. The dispersions may be obtained in any desired manner, e.g. by grinding, e.g. in colloid mills, by dissolving in a solvent and mixing with water containing or not protective colloids or dispersators or both, or by treatment with dispersing agents, alone or in the presence of protective colloids or liquids, e.g. water, or both, or by effecting the coupling in the presence of protective colloids with or without dispersing agents. Any desired dispersators may be employed, e.g. those of Specifications 219,349, 224,925, 242,393, 242,711, 269,960, 273,819, 273,820, 322,737, and 323,788, [all in Class 15 (ii)]. The dispersion may be effected in the dyebath itself, but advantageously the dyestuffs are first brought into the form of more or less concentrated preparations, whether liquid, solid or semi-solid, adapted to yield, by addition of water with or without further dispersators or protective colloids or both, aqueous suspensions or colloidal solutions which may be directly employed. The physical properties of the dyestuffs may be improved by the method of Specification 402,054, e.g. the dyestuff prepared by diazotizing and coupling and filtering off may be treated with steam, and the dyestuffs may then be milled with water or otherwise converted into aqueous dispersions.  The colouring matters may be applied to the materials in any convenient manner, e.g. by dyeing padding or other method of uniform application, or by printing, stencilling or other mode of local application.  In examples: (1) a cellulose acetate fabric is dyed with an aqueous dispersion of the dyestuff 3 - nitro - 4 - aminotoluene --> p - xylidine, producing orange shades readily dischargeable with zinc formaldehyde sulphoxylate; (2) a cellulose acetate woven fabric is first dyed by dispersion methods with p-aminobenzeneazodimethylaniline, which is diazotized and developed on the fibre with b -oxynaphthoic acid producing a navy blue shade; the material is then topped with 2-nitro-4-methylbenzeneazo-p-xylidine, printed with a discharge paste containing zinc formadehyde sulphoxylate (known under the Registered Trade Mark "Decroline"), diethylene glycol, ethyl lactate and gum arabic, dried, aged, washed off and again dried, whereby a white pattern on a black ground is obtained; (3) an aqueous paste of 2-nitro-4-methoxybenzeneazo-m-toluidine is heated with turkey red oil and the dispersion is boiled with a dilute soap solution; a cellulose acetate woven fabric is dyed from this bath and then printed with the discharge paste employed in (2), producing a white discharge on a golden yellow ground.  Reference has been directed by the Comptroller to Specifications 219,349, [Class 15 (ii)], and 397,470.