DE1494674

• Main Authors: KAWAI, ATSUSHI, KUBOTA, MASAICHI, OMOTO, SEIICHI
• Format: Patent
• Language: English
• Published: 10.04.1975
• Edition: 2
• Subjects: APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBONFILAMENTS; CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS,THREADS, FIBRES, BRISTLES OR RIBBONS; NATURAL OR ARTIFICIAL THREADS OR FIBRES; SPINNING; TEXTILES

1,080,671. Crimped viscose rayon. MITSUBISHI RAYON CO. Ltd. Aug. 4, 1964 [Sept. 10, 1963], No. 31515/64. Heading B5B. Highly crimped viscose rayon is produced by extruding a viscose containing at least 4% cellulose, at least 2% of total combined sodium calculated as sodium hydroxide, having a viscosity of from 100 to 1000 poises at 20‹ C. and a sodium chloride salt point of at least 16 into an aqueous coagulating bath containing in grams per litre 0À05 to 0À5 of zinc sulphate (anhydrous salt) 10 to 250 of sodium sulphate (anhydrous salt) 6 to 20 of formaldehyde and a concentration of sulphuric acid within the range specified below, withdrawing the filaments thus formed from the coagulating bath, stretching them under low tension in an aqueous bath which is at 60‹ to 88‹ C. and contains a concentration of sulphuric acid lower than that in the coagulating bath, the stretching tension not exceeding 0À2 gram per denier at a stretch ratio within the range specified below, and then subjecting the stretched filaments (a staple fibre obtained therefrom) to relaxation in an aqueous bath containing sulphuric acid at a concentration lower than that in the coagulating bath, at a temperature of from 30‹ to 70‹ C. to develop crimps. The concentration of sulphuric acid in the coagulating bath ranges from 2A+4 to 7A+ 8 grams per litre, A being the concentration of total combined sodium in the viscose expressed as the percentage of sodium hydroxide. The stretch ratio (expressed as the percentage ratio of the length of the stretched filaments to their original length) ranges from 2T+3À3F-96 to 4T+ 6À6F-144, T being the temperature of the stretching bath in ‹ C. and F. the concentration of the formaldehyde in the coagulating bath in grams per litre. The stretched filaments may be cut to staple fibre lengths prior to the relaxation step. The relaxed staple fibres may then be regenerated by treatment with an aqueous acidic solution at a temperature of at least 70‹ C. The cellulose content of the viscose may be 6 to 10%, and its sodium hydroxide concentration 3 to 5%. The viscosity of the viscose may be 200 to 700 poises, and its salt point 20 to 23. The D.P. of the cellulose in the viscose may be 300 to 600.