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Numéro de publicationUS3340340 A
Type de publicationOctroi
Date de publication5 sept. 1967
Date de dépôt3 déc. 1963
Date de priorité11 déc. 1962
Autre référence de publicationDE1234917B
Numéro de publicationUS 3340340 A, US 3340340A, US-A-3340340, US3340340 A, US3340340A
InventeursMytum Ernest
Cessionnaire d'origineCourtaulds Ltd
Exporter la citationBiBTeX, EndNote, RefMan
Liens externes: USPTO, Cession USPTO, Espacenet
Manufacture of crimped viscose rayon fibres
US 3340340 A
Résumé  disponible en
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Description  (Le texte OCR peut contenir des erreurs.)

United States Patent C) M 3,340,340 MANUFACTURE OF CRMPED VISCOSE RAYON FIBRES Ernest Mytum, Warwick, England, Assignor to Courtaulds Limited, London, England, a British company No Drawing. Filed Dec. 3, 1963, Ser. No. 327,818

Claims priority, application Great Britain, Dec. 11, 1962, 46,652/62 3 Claims. (Cl. 264-168) This invention is concerned with the manufacture of grilmped viscose rayon fibres having enhanced extensii 'ty.

United States patent specification No. 2,986,446 describes a process for the manufacture of crimped viscose rayon fibres by extruding a viscose containing polyethylene glycol into an acid coagulating and regenerating bath containing zinc sulphate, stretching the filaments so formed and relaxing the stretched filaments in an aqueous medium. The important properties of crimp and extensibility of the filament can be controlled by a change in one or more of the inherent features of the process, but, in general, a change which causes an increase in one property has the effect of decreasing the other. For example, the degree of crimp increases and the extensibility decreases when the filament is stretched more, whilst an increase in the zinc sulphate concentration in the bath increases the extensibility of the filament but decreases the degree of crimp. The properties of the filament can, therefore, be varied between high degree of crimp and low extension on the one hand and high extension and low degree of crimp on the other. The process is, however, incapable of producing a filament which combines the features of high degree of crimp and high extension.

Crimped staple fibres may be used as the pile of carpets. For this use, the fibres should be extensible, as this contributes to their resistance to abrasion, and resilient, to preserve the appearance of the carpet during wear. Viscose rayon fibres can be made more resilient by cross-linking the constituent cellulose, but this modification causes a decrease in extensibility. A viscose rayon fibre suitable for cross-linking and use in carpet piles, should, therefore, be highly extensible so as to be able to tolerate the inevitable fall in extensibility which accompanies crosslinking and still retain sufiicient extensibility to maintain the resistance to abrasion.

I have devised a process for the manufacture of crimped viscose rayon fibres having an increased extensibility.

According to the present invention a process for the production of crimped viscose rayon fibres comprises extruding a viscose containing from 5 percent to percent of cellulose, from 5 percent to 10 percent of caustic soda, more than 0.05 percent of a modifier and a zinc compound in the proportion of from 0.01 percent to 0.8 percent of zinc based on the weight of the viscose, at a salt figure of between 3 and 14, into a coagulating and regenerating bath containing from 5 percent to 14 percent of sulphuric acid, from 0.5 percent to 4 percent of zinc sulphate and more than 12 percent of sodium sulphate, to form incompletely regenerated filaments, stretching the filaments by at least 50 percent, cutting the stretched filaments into staple fibres and crimping the fibres by relaxing the fibres in a solution containing between 1 percent and 5 percent of caustic soda, before completing the regeneration of the cellulose in the fibres.

The increase in the extensibility of the fibre, is due, in the main, to two additions to the acknowledged, known process. The first of these is the use of a zinc compound, preferably an alkali metal zincate, in the viscose. This allows a desired degree of crimp to be obtained from a lower stretch, thus preserving to a greater extent the extensibility of the fibre. The effect is noticeable even 3,340,340 Patented Sept. 5, 1967 when the zinc sulphate concentration in the bath is high, that is at or near 4 percent and, thus, the zinc in the viscose can be used to reduce the antagonistic action of zinc in the bath to the crimp in the fibre.

The second addition is that of relaxing the incompletely regenerated fibre in a dilute caustic soda solution. This has a remarkable elfect on the extensibility, causing increases of as much as 50 percent of the preexisting extensibility without deleteriously affecting the degree of crimp. The relaxation of dried cellulose fibres in caustic soda solutions is a process which can only achieve increases of the order of 10 percent in the extensibility of the fibres, and the process is less efiicient than that of similarly treating the incompletely regenerated fibre.

Once the incompletely regenerated fibre has been rendered alkaline in the relaxing step, the regeneration of the cellulose is more economically accomplished by continuing to treat the fibre with caustic soda, which hydrolyses the xanthate groups, rather than by reverting to an acid environment, in which the regeneration is due to the decay of free xanthic acid groups. The change over from alkaline to acid conditions obviously involves the consumption of both acid and alkali. The principle of alkaline regeneration is applicable in the manufacture of all kinds of viscose rayon fibres, but, in general, is useful only where an essential alkaline treatment follows the acid coagulation step.

In a preferred form, the invention consists in extruding a viscose containing from 7.5 percent to 8.3 percent of cellulose, caustic soda such that the ratio of caustic soda to cellulose is between 0.7 and 0.9, 0.1 percent to 0.3 percent of polyethylene glycol having an average molecular weight of between 600 and 6,000 and a zinc compound in a proportion of from 0.04 percent to 0.2 percent of zinc based on the weight of the viscose, at a salt figure of from 5.5 to 8.5, into a coagulating and'regenerating bath containing sulphuric acid in a concentration of from 1.0 to 1.4 times the caustic soda content of the viscose, from 1 to 2 percent of zinc sulphate and between 22 and 24 percent of sodium sulphate, to form incompletely regenerated filaments, stretching the filaments by at least 60 percent of their original length in air, cutting the filaments into staple fibres and crimping the fibres by suspending the fibres in a solution containing between 1.5 and 2.5 percent of caustic soda, before completely regenerating the fibres.

The invention is illustrated by the following example in which percentages are by weight.

Example 1 A viscose containing 8.3 percent of cellulose, 6.2 percent of caustic soda, 0.166 percent of polyethylene glycol having an average molecular weight of 1,500, and 0.22 percent of sodium zincate was extruded at a salt figure of 6 into a regenerating bath containing 7.8 percent of sulphuric acid, 24.0 percent of sodium sulphate and 1.8 percent of zinc sulphate. The filaments so formed were withdrawn from the bath, stretched in air by 70 percent of their original length, cut into staple fibres and dropped into a solution containing 2 percent of caustic soda where they remained for 5 minutes. The fibres were then separated from the solution in a rotary extractor, washed, impregnated with acid, washed again, finished and dried.

The corresponding properties of a fibre produced by the process from which the caustic soda relaxation was omitted, were:

Air dry tenacity g./d 2.32 Air dry extensibility percent 25.3 Wet tenacity g./d 1.23 Wet extensibility percent 35.2 Waves/cm. 2.7

and when this fully regenerated fibre was treated with 2 percent caustic soda, washed and dried, the properties became:

1. A process for the production of crimped viscose rayon fibers comprising extruding a viscose containing from percent to percent of cellulose, from 5 percent to 10 percent of caustic soda, more than 0.05 percent of; a modifier and an alkali metal zincate in the proportion of from 0.01 percent to 0.8 percent of zinc based on the weight of the viscose, at a salt figure of between 3 and 14, into a coagulating and regenerating bath containing from 5 percent to 14 percent of sulphuric acid, from 0.5 percent to 4 percent of Zinc sulphate and more than 12 percent of sodium sulphate, to form incompletely regenerated filaments, stretching the filaments by at least 50 peIcent cutting the stretched filaments into staple fibres and crimping the fibres by relaxing the fibres in a solution containing between 1 percent and 5 percent of caustic soda, before completing the regeneration of the cellulose in the fibres.

2. A process comprising extruding a viscose contain ing from 7.5 percent to 8.3 percent ofcellulose, caustic soda such that the ratio of caustic soda to cellulose is between 0.7 and 0.9, 0.1 percent to 0.3 percent of polyethylene glycol having an average molecular weight of between 600 and 6,000 and an alkali metal zincate in a proportion of from 0.04 percent to 0.2 percent of zinc based on the Weight of the viscose, at a salt figurev of from 5.5 to 8.5, into a coagulating and regenerating bath containing sulphuric acid in a concentration of from 1.0 to 1.4 times the caustic soda content of the viscose, from 1 to 2 percent of zinc sulphate and between 22 and 24 percent of sodium sulphate, to form incompletely regenerated filaments, stretching the filaments by at least percent of their original length in air, cutting the filaments into staple fibres and crimping the fibres by suspending the fibres in a solution containing between 1.5 and 2.5 percent of caustic soda, before completely regeneratin g the fibres.

3. A process as claimed in claim 2 in which the cellulose in the fibres is completely regenerated by contact with a caustic soda solution.

References Cited UNITED STATES PATENTS 2,515,834 7/1950 Nicoll 264168 X 2,860,480 11/1958 Cox 264197 X 2,879,170 3/1959 Miller l06165 X 2,966,391 12/1960 Bandel 264197 X 2,986,446 5/1961 Smith 264198 X 3,046,083 7/ 1962 Baites et a1. 264-168 FOREIGN PATENTS 570,159 6/1945 Great Britain.

ALEXANDER H. BRODMERKEL, Primary Examiner.

J. H. WOO, Assistant Examiner.

Citations de brevets
Brevet cité Date de dépôt Date de publication Déposant Titre
US2515834 *13 nov. 194218 juil. 1950Du PontCellulose filaments and method of producing same
US2860480 *18 avr. 195618 nov. 1958Du PontRegenerated cellulose structures and process for producing them
US2879170 *2 oct. 195724 mars 1959Du PontChemical composition and process
US2966391 *4 oct. 195627 déc. 1960Spinnfaser AgManufacture of regenerated cellulose fibers
US2986446 *25 juil. 195730 mai 1961Courtaulds LtdCrimped regenerated cellulose fibres
US3046083 *6 juin 196024 juil. 1962American Viscose CorpMethod for producing crimped rayon staple fiber
GB570159A * Titre non disponible
Référencé par
Brevet citant Date de dépôt Date de publication Déposant Titre
US3423499 *18 févr. 196521 janv. 1969Fmc CorpProcess for spinning modified xanthated polymers
US3632468 *9 avr. 19684 janv. 1972Rayonier IncHigh-crimp, high-strength rayon filaments and staple fibers and process for making same
US4051300 *27 févr. 197627 sept. 1977Gulf South Research InstituteHollow synthetic fibers
EP0207721A224 juin 19867 janv. 1987A/G Technology CorporationAnisotropic membranes for gas separation
Classifications
Classification aux États-Unis264/168, 106/166.8, 106/166.52, 19/.46, 264/197, 19/66.1, 264/188
Classification internationaleD01D5/22, D01F11/02, D01F2/10, D01F2/06
Classification coopérativeD01F2/10, D01D5/22, D01F11/02
Classification européenneD01F11/02, D01F2/10, D01F2/06, D01D5/22