Patent GB-388796-A (GB)
Title: Improvements in or relating to crepe yarns and fabrics and the manufacture thereof
Filed: 1931-08-22
Abstract: Crape yarns are produced by shrinking yarns containing cellulose derivatives with a latent solvent for the derivative in high concentration, and applying a high degree of twist to the shrunk yarns.  Specified shrinking agents are methylene chloride, chloroform, tetrachlorethane, and ethyl acetate, and these may be used alone or somewhat diluted with a diluent such as benzene, toluene, xylene, benzine, petrol ether, kerosene, carbon tetrachloride, trichlorethylene, or perchlorethylene.  The shrinking agent may be applied to the wound or travelling yarn or during the manufacture of the yarn, e.g. by dry-spinning, and the amount of shrinkage may be modified by applying tension to the yarn.  After shrinking, the yarn may be rinsed with benzene or other inert solvent for the shrinking agent; the yarn may also be lubricated, e.g. by adding a lubricant such as olive oil to the rinsing solvent.  The twist may be applied in a single stage or in a number of stages (cf. Specification 357,576, [Group IX], with or without intermediate steaming (cf. Specification 386,374, [Group IX]); before, during, or after twisting or after forming the yarns into fabrics, as may be appropriate, the yarns may be sized, swollen or scoured by any of the treatments described in Specifications 348,589, 352,000, 352,451, 357,084, and 357,169, to enhance the crape effect.  Yarns of fine filament denier, such as are described in Specification 357,577, [Group IX], may be used. A differential shrinkage may be produced by applying the shrinking agent intermittently, or by using yarns comprising shrunk and unshrunk filaments or filaments shrunk to different degrees, or previously shrunk or unshrunk cellulose derivative yarns of more than one type.  Specified cellulose derivatives from which the yarns may be made are cellulose formate, acetate, propionate, butyrate, and nitroacetate, methyl, ethyl and benzyl cellulose, and cellulose etheresters; the yarns may contain filaments of other materials such as natural silk or reconstituted cellulose. The cellulose derivative filaments may also be wholly or partly in the form of staple lengths, admixed or not with staple fibres of other materials such as silk, wool or cotton, or with continuous filaments of other materials such as silk or reconstituted cellulose.  The shrunk and twisted yarns may be incorporated into fabrics as the whole or part of the weft, or also in the warp. Preferably, threads of low twist are employed in the warp, and both crape threads having a left-hand twist and crape threads having a right-hand twist in the weft; for example, pairs of threads of left-hand twist may alternate with pairs of right-hand twist. Alternatively, use may be made of a yarn of high twist doubled with a yarn of low twist, or of two yarns of opposite directions of twist doubled together.  The fabrics may also contain slightly or highly twisted yarns of other materials such as natural silk or reconstituted cellulose, or unshrunk cellulose derivative yarns; low-twist shrunk yarns of cellulose derivative may also be present. Specifications 332,903, [Class 120 (iii), Yarns &c.], 356,233, 370,040, 371,910; 375,355, [Group IX], 378,910, 380,504; and 386,344, [Group IX], also are referred to.