Patent GB-408654-A (GB)
Title: Improvements in the treatment of textile fabrics
IPC: D06M13/12
Filed: 1932-07-08
Abstract: The properties of fabrics consisting of or containing artificial silk yarns comprising cellulose acetate or other organic derivatives of cellulose are modified by subjecting such fabrics to the controlled action of neutral organic shrinking agents which are true solvents for the cellulose derivatives so that the reduction in length of the yarns is of the order of 5--30 per cent.  The yarns may be of low twist, e.g. up to 25 turns per inch, or may be of a cr<\>zepe or other high twist, in which case the shrinking treatment is applied after the fabric has been scoured or otherwise treated to produce the cr<\>zepe effect. Alternatively, both low and high twist yarns may be present.  The yarns may be of uniform denier or special effects may be obtained by employing slub yarns or yarns of varying denier.  The invention is also applicable to fabrics containing staple fibre yarns.  The fabrics may contain only fibres consisting of organic derivatives of cellulose, such as cellulose acetate, formate, propionate or butyrate, ethyl or benzyl cellulose, cellulose nitroacetate, ethyl cellulose acetate or oxyethyl cellulose acetate, or may contain such fibres in admixture with other fibres such as natural silk, wool or cotton, and the artificial silk yarns may be such as have been delustred by the incorporation therein of substances such as oils, waxes or pigments or by treatment with hot or boiling aqueous media or moist steam.  The control of the shrinkage is effected mainly by adjusting the concentration of the shrinking agent but the temperature and time factors and the tension, if any, applied during the shrinking may also be varied.  Specified shrinking agents are diacetone alcohol, acetone, monomethyl glycol, glycol monacetate, methyl glycol monoacetate, dioxane, and homologues and substitution products thereof, mono-, di- and tri-acetins and ethyl lactate.  Most of these require dilution with another liquid to moderate their shrinking action, and specified diluents are water, glycol, glycerine, benzene, toluene, xylene, benzine, petrol ether, kerosene, hexahydrobenzene, tetra- or deka-hydronaphthalene, carbon tetrachloride, trichlorethylene and perchlorethylene. Delustration may be effected by the use as shrinking agents of water miscible solvents, especially such as are more volatile than water, with water as a diluent.  For shrinkage without delustration diluents, e.g. hydrocarbons or chlorinated hydrocarbons, may be used, which are relatively inert toward the cellulose derivatives.  The shrinking agent may be applied by a bath treatment or by a padding, spraying, printing or stencilling process or local application may be effected with the aid of a resist.  When a water-soluble shrinking agent is used suitable resists are polymerized vinyl compounds, e.g. polymerized vinyl acetate, or oxidized linseed or other drying oils. When a water immiscible shrinking agent is used, the resist may be a water-soluble compound, e.g. gelatine, polyvinyl alcohol or starch. Albumen resists may be used with both types of shrinking agent.  The shrinking agent may subsequently be removed, e.g. by evaporation or by washing with a suitable non-solvent or diluent. Delustration may be effected by washing with water to remove water miscible solvents or lustre may be more or less retained by washing with aqueous solutions of the same or a different solvent in a lower concentration or with aqueous solutions of salts such as sodium sulphate or chloride.  The treated fabrics may be subsequently embossed or may be subjected to local or uniform saponification.  Local application of the shrinking agent may be employed in conjunction with a local application of dyes, pigments or discharges.  The following examples are specified.  (1) A cellulose acetate fabric, having both weft and warp of low twist, is shrunk by treatment for 5 minutes at room temperature in an acetone-water mixture containing 40 per cent by volume of acetone and is washed and dried.  (2) A fabric having a cellulose acetate warp of low twist and a cellulose weft of cr<\>zepe twist is secured to produce a cr<\>zepe effect and is then treated as in (1).  (3) A fabric having both warp and weft of cellulose acetate staple fibre yarn of high twist is scoured to produce a cr<\>zepe effect and is then treated as in (1).  (4) A cellulose acetate plain woven fabric having both warp and weft of low twist cellulose acetate yarn is passed for 30 seconds through a 50 per cent acetone-water mixture at room temperature and is washed and dried.  The product in each case is a springy fabric of soft handle and dull lustre.  The processes of Specifications 391,480, 392,160, 392,191, and 395,353 are disclaimed.  Specification 336,217, [Class 2 (ii)], also is referred to.