Patent GB-462899-A (GB)
Title: Improvements in the treatment of regenerated cellulose material
IPC: D06Q1/02
Filed: 1935-08-17
Abstract: Pattern effects, permanent to washing, are obtained on regenerated cellulose materials such as fabrics, yarns, films, or sheets, by impregnation locally or uniformly with caustic alkali of such concentration and under such conditions of treatment that the regenerated cellulose is temporarily plasticized but not parchmentized, deforming the plasticized material to give pattern effects by mechanical force applied thereto or released by the plasticizing treatment, and removing the alkali by washing or by acidifying and then washing.  Caustic soda solutions of concentrations below 6 per cent or caustic potash solutions between 6 and 20 per cent may be used for impregnating the materials.  The alkali may be applied by printing and in this case the concentration of the caustic soda may be as high as 18 per cent or more, the effective concentration in view of the presence of thickening agents in the printing solution and of the method of application being equivalent to a 6 per cent solution applied by full impregnation without thickeners.  Films or fabrics may be impregnated with 4 per cent caustic soda solution, the excess solution removed by squeezing, the wet materials passed through an embossing calender, and then soured, washed, and dried. Fabrics treated may have a cotton warp and regenerated cellulose weft.  The embossing is fixed permanently on the weft but disappears from the cotton warp in the subsequent washing treatment.  Permanent moir<\>ae effects may be obtained by impregnating a regenerated cellulose fabric with caustic soda solution of below 6 per cent strength, and passing it in double layer between mangle bowls, then washing and drying.  Instead of using the same fabric as the second layer, another fabric may be used. Combined moir<\>ae and embossed effects may be obtained by passing the impregnated cloth in double layer between the bowls of an embossing calender.  The calender bowls may be used hot or cold. Regenerated cellulose fabric containing cr<\>zepe twisted yarn may be treated locally with caustic soda solution of less than 6 per cent strength.  When the fabric is subsequently subjected to the cr<\>zeping operation, the parts treated with alkali cr<\>zepe less than the untreated parts and a pattern effect is produced.  The action of the caustic alkali may be locally inhibited by applying resists of gums or starch.  In examples, viscose artificial silk fabric, or a fabric with cotton warp and viscose artificial silk weft is treated with caustic potash or soda solution and then passed through a heated embossing calender. In another example, two pieces of viscose poplin impregnated with dilute caustic soda are superimposed with their wefts at a small angle to each other, and passed through plain or embossed mangle bowls.  In another example, a viscose cr<\>zepe fabric is printed before cr<\>zeping, with a caustic soda solution thickened with starch and then dried.  It is then immersed in boiling soap solution for the purpose of cr<\>zeping, then washed and dried.  A flat pattern on a cr<\>zeped ground is obtained.  Viscose fabric is printed with a paste containing about 17 per cent of caustic soda and 3,5 per cent of starch.  It is then passed through an embossing calender.