Classifications

• • D—TEXTILES; PAPER
  • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
  • D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
  • D01F2/00—Monocomponent artificial filaments or the like of cellulose or cellulose derivatives; Manufacture thereof
  • D01F2/06—Monocomponent artificial filaments or the like of cellulose or cellulose derivatives; Manufacture thereof from viscose
  • D01F2/08—Composition of the spinning solution or the bath

Definitions

• This invention relates to improvements in methods of producing viscose.
• the procedure contemplates the satisfactory dissolution of the xanthate by subdividing the production of the lean Viscose into two stages, one involving a high alkali content for completely dissolving the xanthate and the other a dilution stage for bringing the concentrated viscose to the proper terminal dilution, the two stages being separated by a rest period, as hereinafter described.
• Viscoses which were prepared in essentially the same manner as ordinary viscoses containing 8% cellulose and 7% NaOI-I content or 7% cellulose and 7% alkali contentthat is, as made by dissolving the Xanthate in the calculated quantity of a mixture of caustic soda and water, occasioned appreciable difiiculties during the processing, both during filtration and during the spinning operations, since they always contained a relatively large amount of undissolved or incompletely dissolved broken pieces of fibres or fibrous lint.
• the essence of the present invention is therefore to subdivide the entire production of a lean viscoseior viscose of weak alkali concentration) into two stages so as first to produce a viscose of high cellulose and alkali content, 1. e., an alkali content in excess of 8% and preferably of at least about 9%, and then, after a rest period and in a second operation to dilute this concentrated viscose with very dilute caustic soda or even Water to produce the final composition desired. .
• the success. of this method finally depends (as has also been found) on the fact that it is only the higher alkali concentrations of 9, 10, 12, 15% and above which are capable of satisfactorily dissolving the cellulose Xanthate, i. e.,
• the method may with advantage be practised with the aid of a so-called vacuum Xanthate kneader in which both the xanthatingand dissolving operations may be performed.
• Example Cellulose of a type conventionally used in the rayon industry is dipped in conventional manner in caustic soda, pressed, shredded, preliminarily ripened and xanthated.
• the cellulose xanthate is then first kneaded in a suitable kneader with a suitable quantity of caustic soda so diluted as to result in the production of a viscose composition of about 16% cellulose and 9% NaOH content.
• This final composition contains about 4-5% of alkali and about 7-8% of cellulose by weight.
• the caustic soda is added gradually as the kneading and stirring proceed.
• the stirrer is allowed to continue running for one'hour in order to insure thorough dissolution, this interval being regarded as a rest period.
• the remaining solvent Water is likewise gradually added, with continued stirring, and in such an amount as to produce the desired final alkali concentration of 4.5% for an 8% cellulose content.
• the viscose obtained, when examined under the microscope, is substantially devoid of 'free fibres and presents but little diificulty during filtration and spinning.
• the steps which comprise in sequence forming an initial viscose solution having an alkali content in excess of 8% and a cellulose content of about 16% by weight, allowing said solution to rest for a period of about 15 to 60 minutes, and diluting said initial viscose solution to form a final viscose solution having an alkali content of about 4 to 5% and a cellulose content of about 7 to 8% by weight.
• the steps which comprise in sequence forming an initial viscose solution having an alkali content in excess o'f 8% and a cellulose content of about 16% by weight, allowing said solution to rest for a period of about 15 to 60 minutes, and diluting said initial viscose solution with a sodium hydroxide solution to form a final viscose solution having an alkali content of about 4 to 5% and a cellulose content of about '7 to 8% by weight.
• the steps which comprise in sequence forming an initial viscose solution having a sodium hydroxide content of about 9% and a cellulose content of about 16% by weight, allowing said solution to rest for a period of about 60 minutes, and diluting said initial viscose solution with water to form a' final viscose solution having a sodium hydroxide content of about 4.5% and a cellulose content of about 8% by weight.

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Textile Engineering (AREA)
• Artificial Filaments (AREA)

Applications Claiming Priority (1)

Publications (1)

Family

ID=7993912

Family Applications (1)

Country Status (2)

Cited By (1)

• 0
  • NL NL55047D patent/NL55047C/xx active
• 1940
  • 1940-06-01 US US338370A patent/US2296378A/en not_active Expired - Lifetime

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