Patent GB-605536-A (GB)
Title: Process for refining textiles made of regenerated cellulose
IPC: D06M11/62
Filed: 1945-12-28
Abstract: Treatment of woven or knitted fabrics or hanks of regenerated cellulose with alkaline swelling agents is followed directly by treatment with acid reagents at a temperature of at least 30 DEG  C., and preferably at a temperature between 50 DEG  C. and the boiling point of the solution employed so that the alkali is immediately weakened to a point where it cannot damage the regenerated cellulose. For the acid treatment dilute solutions of organic or inorganic acids or of acid salts may be used, e.g. solutions of sulphuric, hydrochloric, acetic, formic, or oxalic acid in a concentration of 3-10 per cent.  The acid liquid may be sprayed over the fabrics or hanks and the goods may be subsequently passed through a bath of the same liquid.  The alkaline swelling treatment may be carried out with hot or cold alkali and it may be preceded by treatment with other swelling agents such as acids, organic bases, zinc chloride, ammoniacal copper oxide, or calcium thiocyanate.  Treatment with the alkaline swelling agent may be carried out under tension.  The material under treatment may be composed of regenerated cellulose alone or in association with yarns or fibres of cotton, cellulose esters or ethers, nylon, polyvinyl chloride, vinyl chloride-vinyl acetate copolymers, or other animal, vegetable or synthetic substance.  The alkali treatment may be such as to produce stiffened fabrics, opal or transparent effects, imitation wools or linen finishes.  Pattern effects may be obtained by means of reserve printing.  Mixed fabrics of regenerated cellulose and cotton may be subjected to mercerization without injury to the artificial silk components. The treatment with alkaline swelling agent may be associated with esterification, etherification, aldehyde, synthetic resin and other treatments.  The acidifying liquid may contain dyes, fillers, softening agents, humidifying agents, water-proofing agents, and other additions.  In an example, viscose staple fibre muslin is treated under tension with 25 DEG  Baume caustic soda and then immediately with 5 per cent acetic acid at 85 DEG  C.  A supple transparent fabric is obtained.  Mixed cotton and viscose woven fabric is mercerized with 32 DEG  Baume caustic soda followed immediately by treatment with 5 per cent acetic or sulphuric acid at 85 DEG  C.  Viscose muslin is given an opal woolly character by treatment with 16 DEG  Baume caustic soda at 50 DEG  C. and direct acidification with 5 per cent acetic acid at 85 DEG  C.ALSO:Treatment of woven or knitted fabrics or hanks of regenerated cellulose with alkaline swelling agents is followed directly by treatment with acid reagents at a temperature of at least 30 DEG  C., and preferably at a temperature between 50 DEG  C. and the boiling point of the solution employed so that the alkali is immediately weakened to a point where it cannot damage the regenerated cellulose.  For the acid treatment dilute solutions of organic or inorganic acids or of acid salts may be used, e.g. solutions of sulphuric, hydrochloric, acetic, formic, or oxalic acid in a concentration of 3-10 per cent.  The acid liquid may be sprayed over the fabrics or hanks and the goods may be subsequently passed through a bath of the same liquid.  The alkaline swelling treatment may be carried out with hot or cold alkali and it may be preceded by treatment with other swelling agents such as acids, organic bases, zinc chloride, ammoniacal copper oxide, or calcium thiocyanate.  Treatment with the alkaline swelling agent may be carried out under tension.  The material under treatment may be composed of regenerated cellulose alone or in association with yarns or fibres of cotton, cellulose esters or ethers, nylon, polyvinyl chloride, vinyl chloride-vinyl acetate copolymers, or other animal, vegetable, or synthetic substance.  The alkali treatment may be such as to produce stiffened fabrics, opal or transparent effects, imitation wools, or linen finishes.  Pattern effects may be obtained by means of reserve printing.  Mixed fabrics of regenerated cellulose and cotton may be subjected to mercerization without injury to the artificial silk components. The treatment with alkaline swelling agent may be associated with esterification, etherification, aldehyde, synthetic resin, and other treatments.  The acidifying liquid may contain dyes, fillers, softening agents, humidifying agents, water-proofing agents, and other additions.  In an example, viscose staple fibre muslin is treated under tension with 25 DEG Baume caustic soda and then immediately with 5 per cent acetic acid at 85 DEG  C.  A supple transparent fabric is obtained.  Mixed cotton and viscose woven fabric is mercerized with 32 DEG  Baume caustic soda followed immediately by treatment with 5 per cent acetic or sulphuric acid at 85 DEG  C.  Viscose muslin is given an opal woolly character by treatment with 16 DEG  Baume caustic soda at 50 DEG  C. and direct acidification with 5 per cent acetic acid at 85 DEG  C.