Patent GB-950073-A (GB)
Title: Process for improving the properties of regenerated cellulose fibrous material
IPC: D06M13/278
Filed: 1960-06-09
Abstract: 950,073. Modified cellulose fibres. LIPACO S.A. June 9, 1960 [June 10, 1959], No. 20258/60. Heading B5B. Regenerated cellulose fibrous material is impregnated while in the never-dried gel state with an aqueous liquid containing a permanently soluble cross-linking agent of molecular weight not over 1000 and the liquid content of the treated fibre is then mechanically reduced preferably by squeezing to less than the normal water imbibition value of the fibre in the gel state. Staple fibres or continuous filaments, made by the viscose, cuprammonium or nitrate processes may be treated. A permanently soluble cross-linking agent is defined as a compound containing at least two functional groups or labile atoms in the same functional groups which will react with the hydroxyl groups of the cellulose to link two cellulose chains together. It may be monomeric or polymeric, and may undergo polymerization under the conditions of the cross-linking reaction, but if it is a polymer or if such polymerization occurs concurrently with or prior to cross-linking, the resulting polymer will normally be linear, rather than three-dimensional and will remain water-soluble. Crosslinking agents may be selected from formaldehyde, dialdehydes, e.g. glutaraldehyde and adipaldehyde; hydroxyaldehydes, e.g. hydroxyadipaldehyde; unsaturated aldehydes, e.g. acrolein ; glycidyl aldehydes; reactant type resins, e.g. modified urea resins such as methylated methylol ureas, partially polymerized methylated methylol ureas, methylated and unmethylated methylol ethylene ureas, e.g. dimethylol ethylene urea, and methylated and unmethylated methylol 1.2 propylene ureas as well as dimethylol triazines and triazones; polyacetals (including diacetals) of polyhydroxy compounds; divinyl sulphone; dihalohydrins, e.g. dichlorohydrin; and di- and tri-aziridinyl phosphine oxides and sulphides. The aqueous liquid may contain between 0.5 and 20% by weight of the cross-linking agent, and may also contain a catalyst and a finishing agent. The temperature of the aqueous liquid is not critical, but may be between 15-50 C. and it may be contacted with the fibrous material in a number of stages. Catalyst and finishing agent may be applied as stages separate to that of the aqueous liquid. After impregnation, the fibrous material may be heated to effect crosslinking of the cellulose. In a preferred method, regenerated cellulose fibrous material is prepared having a gel water imbibition of from 120-150% and after impregnation the liquid content of the treated fibrous material is reduced to from 60-120% by weight of the ovendried treated fibre. As shown, a regenerated cellulose tow 10, made by a conventional viscose process is withdrawn from the bath 12, cut into staple fibre by device 13 and treated as a mat on conveyer belt 14 successively with acid (16), alkaline (17) and desulphurization (18) sprays, followed by water-washing (19), acid (20), and water (21) sprays. The mat is squeezed between rollers 22, 23 and passes over endless belt 24, where it is sprayed with aqueous liquid containing the cross-linking agent (25). It is then squeezed between rollers 26, 27, sprayed again with the aqueous liquid at 28, and squeezed between rollers 29, 30 with sufficient pressure to reduce the liquid content of the fibres to below the water imbibition value of the gel fibre. The mat is pulled apart in opening device 31 and the fibres passing to conveyer belt 32 dried in oven 33 at 50-100 C. and cured in oven 34 at 110-160 C. Fibres so treated have low water imbibition and dye evenly. Specification 878,655 and U.S.A. Specifications 2,786,081 and 2,859,134 are referred to. Reference has been directed by the Comptroller to Specification 930,132.