Patent GB-421613-A (GB)
Title: Improvements in the manufacture and treatment of artificial filaments, yarns and thelike containing organic derivatives of cellulose
IPC: D01F2/28
Filed: 1933-06-27
Abstract: Artificial filaments, threads, yarns, ribbons, or similar textile materials containing an oxyalkyl cellulose organic ester having not more than one oxy-alkyl radicle per C6H10O5 molecule, are subjected to saponification.  The products may have an affinity for cotton colours after having undergone a relatively small loss in weight consequent upon saponification.  Particularly suitable oxy-alkyl esters of cellulose are those containing the oxy-ethyl, oxy-propyl, dioxy-propyl, or chlor-oxy-propyl radicle and the acetyl or other lower aliphatic acidyl group.  Cellulose derivatives containing mixed ether or mixed ester groups may be used.  The ether content may be ,25, ,5, or ,75 ether group per unit of cellulose.  Filaments, threads, and the like of high tenacity are obtained by processes involving a considerable stretching of the materials, i.e. a stretching of the order of 200 to 500 per cent or more of their original length, either during production e.g. by the wet-spinning processes of Specifications 340,324, and 343,062, or subsequently to production, as described in Specifications 277,089, 323,790, [both in Class 2 (ii)], 370,430, and 371,461.  The extent of saponification is at least sufficient to confer an affinity for cotton dyes, e.g. corresponding to a loss in weight of the materials of 5--10 or 20 per cent, and preferably amounts to substantially complete removal of the ester groups present.  As saponifying agents there may be employed caustic soda or potash, trisodium phosphate, sodium silicate, ammonia, ethanolamines, or methylamines, in aqueous, aqueous-alcoholic, or alcoholic solution.  In batch saponification, a 1--3 or 5 per cent solution of the saponifying agent in an alcoholic medium may be employed.  Aqueous saponifying agents may be used either in batch processes or continuous processes, e.g. processes in which a number of filaments are passed continuously in warp formation through the saponifying bath.  Suitable saponification processes are those described in Specifications 314,446, 314,447, 316,521, 318,468, [all in Class 2 (ii)], 351,417, 402,104, 402,105, 402,106, and 403,071.  The filaments or the like, either before or after the saponification step, may be subjected to shrinking, as described, for example, in Specification 389,823, by treatment with solvents or latent solvents.  The following examples are given; (1) dry spun artificial threads which have been stretched to 300 to 500 per cent of their original length, and which consist of an acetone-soluble oxy-ethyl cellulose acetate containing 2,25--2,75 acetyl groups obtained from a cellulose ether containing ,25 to ,5 oxy-ethyl group, are saponified by means of a 4 per cent aqueous solution of caustic soda containing 25 per cent of sodium chloride; (2) a dry spun yarn containing from ,75 to ,5 oxy-ethyl groups and 2,25 to 2,75 acetyl groups is saponified in hank or cake form by means of a ,4 per cent solution of caustic soda in methyl alcohol; (3) dry spun yarns which have been stretched to 400--600 per cent of their original length, and which comprise an oxy-ethyl cellulose acetate containing ,5 ether group and 2,5--2,75 acetyl groups, are impregnated with 8 per cent aqueous caustic soda and passed over heated rollers.  The Provisional Specification comprises the saponification of oxy-alkyl cellulose esters in general, and refers also to Specifications 165,519, 177,868, 179,234, 198,023, 203,092, 207,562, 249,173, 300,998, 308,322, 308,323, 309,201, 312,095, 312,096, 312,098, 325,233, [all in Class 2 (ii)], 340,325, 340,437, 380,504, 380,505; and 414,751, [Group VIII].