Patent GB-396736-A (GB)
Title: Improvements in or relating to the production of pattern effects on textile and other materials
IPC: D06P5/15
Filed: 1932-02-09
Abstract: Discharge effects on textile or other materials are obtained by the action of discharging agents having an acid reaction or which liberate acid during the discharge process, in the presence of an organic base, which restricts acidity and minimizes the tendering of the material.  The organic base may be incorporated in the discharge composition or may be applied separately, e.g. by padding before or after application of the discharge composition and before steaming, ageing or like moist heat treatment.  The base employed is preferably of a weakly basic character, is advantageously water-soluble and is preferably colourless. Suitable bases are aniline and substituted anilines, aralkylated aromatic bases, e.g. benzyl ethyl aniline, heterocyclic compounds, e.g. pyridine or quinoline, or aliphatic compounds, e.g. urea and derivatives thereof, e.g. alkyl derivatives such as dimethylurea, urethanes, or ethanolamines, e.g. triethanolamine.  Any other desired substances may be present in the discharge preparation. In printing cellulose derivative materials it is advantageous to incorporate swelling agents, e.g. thiocyanates, phenols, alcohol or hydroquinone, and thickening agents.  Dyestuffs resistant to the discharging agent may be included, e.g. stannous discharges may be coloured with anthraquinone dyestuffs in the unreduced state according to the process of Specification 351,457. Basic colouring matters of the di- and triarylmethane, azine, oxazine and thiazine series may be used similarly.  The discharge preparations may be applied by any suitable method of local application, e.g. printing or stencilling.  If desired other means of minimizing tendering of the material may be employed in addition, e.g. the material may be treated with ammonia gas after printing and a preliminary drying and ageing but before any lengthy steaming or ageing.  The organic base, in addition to reducing tendering, may exercise other effects, e.g. on the lustre of the material.  Thus the delustring action of steam on cellulose acetate material may be facilitated or increased, producing a delustred pattern on a lustrous ground, e.g. delustred white or coloured discharge effects may be obtained on a cellulose acetate material by local application of a stannous discharge composition containing 30 per cent of urea followed by drying and steaming. In such cases it is preferable to employ gum tragacanth as thickening agent.  In examples: (1) a fabric composed wholly of natural silk and coloured with a dyestuff dischargeable by stannous chloride is printed with a composition containing stannous chloride, methylated spirits, urea, sodium thiocyanate, citric acid, gum arabic (1 : 1) or gum tragacanth (10 per cent) and water, and the material is then dried, aged and steamed yielding a white discharge on a coloured ground; (2) a fabric containing both natural silk and cellulose acetate and dyed with dyestuffs dischargeable by stannous chloride is printed with a composition containing stannous chloride, methylated spirits, sym-dimethylurea, sodium thiocyanate and gum arabic thickening, and is then dried, steamed, washed off and again dried.  The process is also applicable to other textile materials, e.g. materials containing other organic esters of cellulose, e.g. cellulose formate, propionate or butyrate, or cellulose ethers, e.g. methyl, ethyl or benzyl cellulose, also regenerated cellulose material, cotton materials and materials containing animal fibres, e.g. wool, and mixed materials.