Patent GB-932810-A (GB)
Title: Improvements in the treatment of highly crystalline regenerated cellulose fibres
IPC: D06M11/155
Filed: 1961-11-17
Abstract: Never dried regenerated cellulose fibres having a degree of crystallinity above 50% are treated whilst under tension first with a swelling agent for the regenerated cellulose and then with a cross-linking agent for the regenerated cellulose.  The swelling agent, which is preferably applied at a temperature of 15 DEG -40 DEG C. for 15-50 seconds at a concentration of 5-80% by weight, may be an alkali metal hydroxide, zinc chloride or sodium zincate.  The cross-linking agent may be formaldehyde, a "reactant type" resin, e.g. methylated methylol urea, N-methylol-N-alkyl triazones, N-methylol-N-alkyl melamines and methylated or unmethylated methylol ethylene-or 1,2-propylene ureas, an aminoplast resin precondensate, e.g. urea-formaldehyde, melamine-formaldehyde, dicyandiamide-formaldehyde and guanidine-formaldehyde condensates and combinations thereof and methylol-amineepihalohydrin compounds, a formaldehyde-acrolein resin, an acetone-formaldehyde resin or a polyepoxy resin.  The cross-linking agent may be applied as an aqueous solution or dispersion containing 4-25% by weight of the agent, 10-50% of a catalyst based on the weight of the agent and other textile finishing agents, e.g. hand builders, lubricants and water repellents such as silicone resins.  After treatment with the cross-linking agent the fibres may be squeezed and dried at a temperature below 100 DEG C. for 20 seconds-2 hours and, when a heat hardenable resin is used, cured by heating.  The regenerated cellulose fibres having a degree of crystallinity above 50% may be produced by spinning unaged viscose into a zinc-free bath containing less than 30 g./l. H2SO4 and less than 50 g./l. Glaubers salt at a temperature below 30 DEG C. and drawing the fibres produced in the bath at a progressively increasing speed until regeneration is complete.  Specifications 730,226, 732,573, 796,815, 872,656, 878,655 and 930,132 are referred to.ALSO:The dimensional stability of textile fibres of regenerated cellulose having a degree of crystallinity above 50% is improved by treating them under tension first with a swelling agent for the regenerated cellulose and then with a cross linking agent for the regenerated cellulose.  The swelling agent, which is preferably applied at a temperature of 15 DEG -40 DEG C. for 15-50 seconds at a concentration of 5-80% by weight, may be an alkali metal hydroxide, zinc chloride or sodium zincate.  The cross-linking agent may be formaldehyde, a "reactant type" resin, e.g. methylated methylol urea, N-methylol, N-alkyl triazones, N-methylol, N-alkyl melamines and methylated or unmethylated methylol ethyleneor 1,2-propylene ureas, an aminoplast resin precondensate, e.g. urea formaldehyde, melamine formaldehyde, dicyandiamide-formaldehyde and guanidine-formaldehyde condensates and combustions thereof and methylol-amino-epihalo-hydrin compounds, a formaldehyde-acrolein resin, an acetone-formaldehyde resin or a polyepoxy resin.  The cross-linking agent may be applied as an aqueous solution or dispersion containing 4-25% by weight of the agent, 10-50% of a catalyst based on the weight of the agent and other textile finishing agents, e.g. hand builders, lubricants and water repellents such as silicone resins.  After treatment with the crosslinking agent the fibres may be squeezed and dried at a temperature below 100 DEG C. for 20 seconds-2 hours and, when a heat hardenable resin is used, cured by heating. Between the swelling and cross-linking treatments the fibres may be washed, dried and processed, e.g. made up into yarn, fabric or garments, or "Sanforized" (Registered Trade Mark). Continuous filaments, yarns or woven, knitted or non-woven fabrics made wholly from the highly crystalline regenerated cellulose or from blends containing at least 50% by weight of the highly crystalline regenerated cellulose with cotton, nylon, polyester, acrylic, polyethylene or polypropylene fibres or up to 15% by weight of normal regenerated cellulose fibre may be treated.  As shown in the drawing, fabric 1 may be passed through a bath 3 containing the swelling agent to a stenter frame 9 where it is sprayed with water from spray heads 10 and 11 while it is stretched in the direction of the welt.  It is then passed through a water bath 14, an acid bath 17 containing a weak acid, e.g. 0,5%-1,5% acetic acid and a water bath 20 to bath 25 where it is treated while still under tension with a solution of the cross-linking agent. Excess solution is removed by squeeze rollers 28 and the fabric is then dried and if desired cured by passage through oven 29. Specifications 730,226, 732,573, 796,815, 872,656, 878,655 and 930,132 are referred to.