Patent GB-612207-A (GB)
Title: Improvements relating to the saponification of cellulose ester yarns
IPC: D01F2/28
Filed: 1946-05-17
Abstract: <PICT:0612207/IV(a)/1> Yarns of cellulose acetate or other cellulose carboxylic acid ester are subjected to saponification when in the form of flat-ended, annular, self-supporting cakes, by causing the saponifying liquor to pass radially through the cakes, each of which is held between sealing plates, and the distance between these decreased as the denier of the yarn decreases during the treatment, and retaining means are operated to prevent any movement apart of the plates.  At intervals during the treatment the flow of liquor may be stopped while the plates are adjusted. Saponification may be continued until completely regenerated cellulose material is obtained.  The saponifying liquor may be an aqueous, or alcoholic solution of an organic or inorganic base, and it may be used at temperatures of 20 DEG -100 DEG  C.  Stretched cellulose acetate yarns may be saponified with 0.1-5.0 per cent solutions of caustic soda at 20 DEG -90 DEG  C.  These solutions preferably contain 5-20 per cent of sodium acetate or sulphate. As shown, saponifying liquor is forced under controlled pressure and rate of flow through pipe 4, distribution header 7, and the artificial yarn cake 6 into the open tank 5.  The cake 6 is set on plate 10 and covered with plate 11 which is maintained in contact with the cake by means of the wheel 13, screwed sleeve 12, and screwed portion 9 of the distributing head 7.  The wheel 13 is operated from time to time during the saponification to compensate for the loss in pressure due to the shrinkage of the yarn.  The flow of liquor may be stopped by valve 2, while the adjustment is being made.  The liquor may be re-circulated via valve 16 or sent to waste via valve 17.ALSO:<PICT:0612207/IV (c)/1> Yarns of cellulose acetate or other cellulose carboxylic acid ester are subjected to saponification when in the form of flat-ended, annular, self-supporting cakes, by causing the saponifying liquor to pass radially through the cakes, each of which is held between sealing plates, and the distance between these plates is progressively decreased as the denier of the yarn decreases during the treatment, and retaining means are operated to prevent any movement apart of the plates.  At intervals during the treatment the flow of liquor may be stopped while the plates are adjusted. Saponification may be continued until completely regenerated cellulose material is obtained.  As shown, saponifying liquor is forced under controlled pressure and rate of flow through pipe 4, distribution header 7 and the artificial yarn cake 6 into the open tank 5.  The cake 6 is set on plate 10 and covered with plate 11 which is maintained in contact with the cake by means of the wheel 13, screwed sleeve 12, screwed portion 9 of the distributing head 7. The wheel 13 is operated from time to time during the saponification to compensate for the loss in pressure due to the shrinkage of the yarn.  The flow of liquor may be stopped by valve 2 while the adjustment is being made.  The liquor may be re-circulated via valve 16 or sent to waste via valve 17.