US2607955A

US2607955A - Spinning of viscose

Info

Publication number: US2607955A
Application number: US193746A
Authority: US
Inventors: Drisch Nicolas; Herrbach Paul
Original assignee: TEXTILE and CHEM RES CO Ltd
Current assignee: TEXTILE and CHEM RES CO Ltd; TEXTILE AND CHEMICAL RESEARCH Co Ltd
Priority date: 1949-08-25
Filing date: 1950-11-02
Publication date: 1952-08-26
Anticipated expiration: 1969-08-26
Also published as: FR63131E; BE516903A; CH315104A; DE1047371B; BE497545A; GB711642A; GB757521A; GB685631A; US2705184A; FR60194E; CH295960A; DE969389C; FR993756A; NL92810C; NL103223C

Description

Patented Aug. 26, 1952 SPINNING or viscose 'Nicclas Drisch and Paul Herrbach, Paris, France,

' assignors, by mesne assignments, to Textile and Chemical Research Company Limited, St. Peter, Port of Guernsey, Channel Islands, a corporation of Great Britain No Drawing. ;Application November 2, 1950, Se- I rial No. 193,746. In France August 25, 1949 23 Claims.

This invention relates to the production of viscose rayon, artificial staple fibre, hair, braid and the like.

The application is a continuation-in-part of application No. 140,767 filed January 26, 1950.

In French Patent No. 890,575 a process'is described for spinning viscose with the aid of a funnel of the Thiele type commonly used for the production of rayon from cuprammonium solutions of cellulose. In accordance with this process, unripe viscose having a salt point of more than 12 is extruded into a very dilute aqueous spinning bath (e. g. 0.8-1% sulphuric acid) at moderate temperature (e. g. 23-30 C.) and the filaments are fixed by treatment in a 1% sulphuric acid bath at 40 C. Usually in the cuprammonium process rather large spinneret holes are used but in the process of this patent ordinary viscose spinnerets (diameter about 0.7 mm.) are employed. The filaments ars stretched in the funnel to a fineness of about 0.1 denier or less, and a spinning speed-of about 35 metres per minute is used. In this process, however, the filaments tend to adhere to one another and the bundle of filaments obtained has, therefore, a rather harsh touch resembling'cotton; the bundles of filaments, as a result of this adhesion, can be woven or knitted without twisting.

According to the present invention a process for the production of viscose rayon, artificial staple fibre, 'hairfbraid and the like comprises extruding in filamentary form into a coagulating bath of low acid concentration, at room temperature, a Viscose having a viscosity of at least 400 poises and having a y-value above 60, and thereafter fixing the filamentary product by treatment in hot aqueous liquid.

The a-value referred to above is a measure of the degree of xanthogenation and is a term well known in this art. and Matthes in Zeitschrift fur Angewandte Chemie, vol. 17, No. 34, pages 62-4307. (August 25th, 1934.)

The high viscosity viscose employed may be obtained by either of two general methods. In one form of the invention there may be employed viscose produced from an alkali cellulose with a cellulose concentration of 6% to 10% and which has not been ripened (the product is referredto herein as an unripe viscose) and in another form of the invention there may be employed viscose which has a cellulose content of 10 to employed may be achieved by Xanthogenation of.

the alkali cellulose with-a large excess of car- It is defined by Fink, Stahn cosityof 600 poises or more and the y-value is 70 2 bon disulphide, i e. more than 5 0% calculated on thee cellulose present. In the preferred form of the invention the viscose employedhas a visto 80. Generally the viscose employed will have a low concentration of alkali, e. g. 6% or less.

The high viscosity viscoses are preferably spun through spinnerets having apertures consider-.. ably larger than normal, e. g. of about 0.10 to- 0.15 mm., and the coagulation baths employed are preferably sulphuric acid at a concentration The length of travel of the filamentary material through the bath may be,

of 10 to 15 g./litre.

for example, 0.15 to 1 metre.

In co-pending application No 58,248 (now Patent No. 2,511,699) a process is described for spinning viscose at high speed which comprises extruding the viscose through a spinning nozzle which is disposed in a coagulating bath, and passing the extruded filaments into a straight speed to 150 metres per mintue or more. Preferably the entrance to the tube is at a distance less than 3 cm. from the nozzle, the diameter of the tube is 10 to 25 mm. and the filaments travel in a straight path from the nozzlethrough the tube to the winding-off device.

By employing the conditions characteristic of this invention in apparatus of the aforesaid type, it is possible to increase the spinning speed at the spinneret to 50-o r even metres per minute, and filaments even of normal'size, i. e. up to 5 denier, can'be obtained without any appreciable adherence of the filaments to one another.

The filaments are completely, coagulated when they reach the end of the tube but are still highly plastic and can be easily stretched by 100% or 200% so that the winding speed may be as high as 200 or even 300 metres per minute.

The fixing of the yarn-is effectedby treatment with hot aqueous baths, e.,g,. hot dilute acids or I saline solutions or hot water. If. the fixing operation is carried out with the yarn under tension;

for example on spinning cakes, fibres vare'obtained, after cutting. which have-very low elongation, less than 7% which yield yarn of relatively low tenacity. However, if the fixing is carried out with the filaments in the de-tensioned condition, either by cutting before fixing or by de-tensioning the bundle of filaments before the fixing operation, the fibres have higher elongations, from 7% to 10% or more. They are'very supple and are readily converted by methods known per se, into high quality yarns.

The filamentary material obtained may be stretched (additionally to the stretching effected as it leaves the nozzle), e. g. by 100 to 200%. Yarns of varying denier, e. g. 0.5 to 4 denier, may be obtained by the process.

The following examples will serve to illustrate the invention but are not to be regarded as limiting it in any way:

EXAIWPLE I Production of the unripe viscose spinning solution greater than 800 and containing less than 2% of molecular chains having a degree of polymerisation below 200, are steeped in caustic soda lye containing 235-240 g./litre of NaOH. The sheets are pressed to expel excess lye until their weight is reduced to 280-285% of the initial alpha-cellulose content. The alkali cellulose thus obtained is shredded but not ripened. It is reacted at 28 C. with carbon disulphide, (50 parts of CS2 per 100 parts of initial alpha-cellulose) for 2 hours. The cellulose xanthate thus obtained is mixed with a small quantity of 9% caustic soda lye at 5 to 10 C. and the resulting pasty, swollen mass is dissolved in 4% caustic soda lye at to C.

The resulting solution contains about 9.5% of cellulose and 5% of caustic soda. It has a viscosity of 900 poises and the degree of polymerisation of the cellulose contained in it is still in excess of 500. Its salt point lies between 15 and 16.

The solution is filtered and degassed for 9 hours in a vacuum in the presence of 1 g./litre of a mixture of higher branched aliphatic alcohols as antiscumming agent. It is then ready for use.

Production of the filaments The viscose solution thus prepared, without any ripening, is spun in an apparatus as described in said Patent No. 2,511,699. The spinning bath used consists of sulphuric acid at a strength of 1 g./litre and the spinning is eiTected at ordinary room temperature. The spinnerets used have a diameter at least about 50% larger than is customary when spinning viscose, e. g. 0.15 mm. to yield filaments of about 1 denier, in order to increase the degree of stretching possible at the spinnerets. The stretch at this stage should be positive, i. e. the speed of the filaments leaving the spinnerets should be higher than the speed of the viscose passing through the spinnerets. Using a tube of about 5 mm. diameter metres per minute, or more, are easily obtained.

On leaving the tube the filaments are stretched by a further 150% by means of rollers as in Patent No. 2,511,699. During this stretching operation the filament may be set by treatment in a bath identical with the spinning bath but heated to 75-80 C., but if this is not done it is preferable to complete the setting of the filaments by 9.1-

4 lowing the wound yarn to stand for 2 to 3 hours in the acid state.

The yarn obtained is washed with hot water and dried. Even without any desulphurisation or bleaching treatment the yarns obtained are remarkably white. The conditions being adjusted to yield a yarn of denier/100 filaments, the characteristics of the yarn are:

Tenacity:

Dry g./denier 2.9 Wet g./denier 2.3 Elongation at break (both wet and dry) per cent 9 EXAMPLE II Linters of a degree of polymerisation of 780 are mixed in caustic soda (concentration 225 g./litre) and pressed until the ratio of the final weight of the alkali-cellulose torthe weight of alpha-cellulose contained in the pulp used is 3.

The alkali cellulose is not ripened but is shredded for 2 hours with cooling, and then xanthogenated with 55 of carbon disulphide (calculated on the alpha-cellulose content, of the pulp) for 3 hours at between 22 and 30.

A mixture of the cellulose xanthogenate and alkali is prepared containing 9% of caustic soda and 12% of cellulose and this is then slowly mixed at between 5 and 10 C. with dilute caustic soda to produce a viscose containing 6% to 7% cellulose and 5% to 6% caustic soda. The use of stronger caustic soda initially is desirable in order to secure the maximum solubility of the xanthogenate. The v-value of the product is about 80.

After filtration, ripening for 24 hours at 10 is eifected and the product is degassed in the presence of 0.5% of iso-octyl alcohol (as antifoaming agent). The viscose thus obtained has a 'y-value of 70 and a viscosity of about 500 poises.

It may be mentioned here that viscoses of high degree of polymerisation having viscosities substantially lower than 400 poises spin badly or not at all.

A rayon of 400 deniers and containing 260 filaments is spun at 50 m./min. through a spinneret having holes of 0.10 to 0.15 mm. dipping into a bath containing 10 to 15 g./litre of sulphuric acid at 18, the length of the passage de-tensioning. This procedure does not afiect the wet and dry tenacity. It has the advantage that it directly de-acidifies the yarn and permits immediate and complete recovery of the carbon disulphide.

EXANLPLE III Alkali cellulose is prepared as in Example 11, shredded for 2 hours, with cooling, ripened for 30 hours at 21 0., and xanthogenated with 60% of carbon disulphide (calculatedon the alphace1lulose).fcr 3 hours between 22 and 30 C.

By mixing the xanthogenate with caustic soda at low temperature to 5) a viscose containing 12% of cellulose and 6% caustic soda is prepared, whereafter the mixture is filtered and degassed. After ripening for 18 hours at 10 C., the -value of the product is 75.

A bundle of fibres having a total count of 5250 deniers is spun via a spinneret having 3500 holes of a diameter of 0.10 mm., into a sulphuric acid bath of concentration g./litre. The filaments are stretched between rollers to 148% and the filaments are then de-tensioned and fixed in water at 85-90 C.

No de-sulphurisation is necessary but the filaments are bleached in chlorine water (concentration 2 g./litre).

The filaments are cut to form artificial staple fibre and this product has the following properties:

Tenacity g./den.:

Dry 4.2

Wet 3.0

Elongation:

Dry 3.4

Wet 9.6

In a variant of this process the bundle of filaments is passed after de-tensioning, into a second bath composed of very hot Water, for example at 90 C. The hot Water treatment produces strongly curled fibres. I

EXAMPLE IV A viscose prepared in accordance with Example ]1 is a spun through a spinneret having slots of 0.25 x 0.05 mm. The conditions are regulated to produce flat filaments of 3 denier, which have the following properties:

Tenacity g./den.:

Dry 3.25 Wet 2.45 Elongation:

Dry 6.6 Wet 8.5

The cross-section is of very elongated form and the filaments may be cut into staple fibre. The staple fibre can be easily carded or combed and gives normally regular yarns. In use, it may be mixed with cotton in all proportions. It is an effective substitute for high tenacity staple fibre as previously used in the cotton and linen industry. The staple fibre obtained appears under the microscope as twisted fibres of the cotton type.

Modified yarns may be obtained by including white or coloured pigments or oily substances in the spinning solutions.

A particular advantage of the process of this invention is that a large proportion of the carbon disulphide used may be readily recovered. Carbon desulphide is regenerated in the spinning bath and remains dispersed therein. Some sinks to the bottom of the spinning bath and can be separated by decantation while the remainder can be recovered by treating the bath with a stream of gas or vapour and adsorbing, absorbing or condensing the carbon disulphide from the gas or vapour stream by any of the usual methods.

Yarns obtained by the processof this invention have valuable commercia1 properties; for example they may be usedfortheproduction ofjcords for reinforcing pneumatic tyres.

yarns by continuously stretching to the rupture point or by any other of the known methods, forconverting continuous yarns directly, and with-- out carding, into discontinuous yarns. The prodartificial staple fibre, -hair, braid and the like which comprises extruding in filamentary form into a coagulating bath of sulphuric acid of concentration 1 to 15 g./litre at room temperature,

a viscose containing 6% to 15% of cellulose, not 7/ over 6% sodium hydroxide, and having a vis-:

cosity of at least 400 poises and having a 'y-value above 60, and thereafter fixing the filamentary product by treatment in hot aqueous liquid.

2. A process for the production of viscose rayon, artificial staple fibre, hair, braid and the like which comprises extruding ina filamentary form into a coagulating bath of sulphuric acid of concentration lto 15-g./litre at room temperature, a viscose containing 6% to 15% of cellulose, not over 6% of sodium hydroxide, and prepared from unripened alkali cellulose by xanthogenation with more than 50% carbon disulphide, having a viscosity of at least 400 poises and havin a 'y-value above 60, and thereafter fixing the filamentary product by treatmentin hot aqueous liquid.

3. A process for the production of viscoserayon, artificial staple fibre, hair, braid and the like which comprises extruding in filamentary form into a coagulating bath of sulphuric acid of concentration 1 to 15 g./litre at room temperature, a viscose containing 10 to 15% of cellulose, not over 6% of sodium hydroxide, and prepared from ripened alkali cellulose by xanthogenation with more than 50%. of carbon disulphide, having a viscosity of at least 400 poises and having a y-value above 60, and thereafter fixing the filamentary product by treatment inhot aqueous liquid.

4. A process for the production of viscose rayon,

artificial staple fibre, hair, braid and the like which comprises extruding in filamentary form into a coagulating bath containinglo to 15 g. per litre of sulphuric "acid at room temperature, a viscose containing 6% to 15% of cellulose, not over 6% of sodium hydroxide, and prepared from unripened alkali cellulose by xanthogenation with more than 50%carbon disulphide,having a viscosity of at least 400 poises and having a y-value above 60, and thereafter fixing the filamentary product by treatment in hot aqueous liquid.

5. A process for the production of viscose rayon, artificial staple fibre, hair, braid and the like which comprises extruding in filamentary form into a coagulating bath containing 10 to 15 g. per litre of sulphuric ,acid at room temperature, a viscose containing 10 to 15% of cellulose not over 6% of sodium hydroxidaand prepared from ripened alkali cellulose by xanthogenation with more than 50% of carbon disulphide, having a viscosity of at least poises and having a 'y-value above 60, and thereafter fixing the fila- Continuous yarns may also be broken down to discontinuous 7 mentary product by treatment in hot aqueous liquid.-

6. A'process for the'pro'duction of viscose rayon, artificial staple'fib-re, hair, braid and the like which comprises extruding in filamentary form into acoagulating bath containing to g. per litre of sulphuric acid at room temperature via spinnerets with holes of 0.10 to 0.15 mm. diameter, a viscose containing 6% to 15% of cellulose, not over 6% of sodium hydroxide, and prepared from unripened alkali cellulose by xanthogenati'on with more than carbon disulphide, having a-viscosity of at least 400 poises and having a y-value above 60, and thereafter fixing the filamentary product by treatment in hot aqueous liquid.

'7. A process for the production of viscose rayon, artificia1 staple fibre, hair, braidand the like which comprises extruding in filamentary form into a coagulating bath containing 10 to 15 g. per litre of sulphuric acid at room temperature via spinnerets with holes of 0.10 to 0.15 mm. diameter, a viscose containing 10 to 15% of cellulose, not over 6% of sodium hydroxide, and prepared from ripened alkali cellulose by xanthogenation with more than 50% of carbon disulphide, having a viscosity of at least 400 poises and having a v-value above 60, and thereafter fixing the filamentary product by treatment in hot aqueous liquid.

8. A process for the production of Viscose rayon, artificial staple fibre, hair, braid and, the'like which comprises extruding in filamentary form into a coagulating bath containing 10 to 15 g. per litre of sulphuric acid at room temperature via spinnerets with holes of 0.10 to 0.15 mm. diameter, a viscose containing 6% to 15% of cellulose, not over 6% of sodium hydroxide, and prepared from unripened alkali cellulose by xanthogenation with more than 50% carbon disulphide, having a viscosity of at least400 poises and having a.' -value above 60, stretching the filamentary products at the spinneret and further stretching them by 100 to 200%, and thereafter fixing the filamentary products by treatment in hot aqueous liquid.

9. A process for the production of viscose rayon, artificial staple fibre, hair, braid and the like which comprises extruding in filamentary form into a coagulating bath containing 10 to 15g. per litre of sulphuric acid at room temperature via spinnerets with holes of 0.10 to 0.15 mm. diameter, a viscose containing 10 to 15% of cellulose, not over 6 of sodium hydroxide, and prepared from ripened alkali cellulose by xanthogenation with more than 50% of carbon disulphide, having a viscosity of at least-400 poises and having a v-value above 60,s tretching the filamentary products at the spinneret and further stretching them by 100 to 200%, and thereafter fixing the filamentary products by treatment in hot aqueous liquid.

10. A process for the production of viscose rayon, artificial staple fibre, hair, braid and the like which comprises extruding in filamentary.

form into a coagulating bath containing 10 to 15 g. per litre of sulphuric acid at room temperature via spinnerets with holes of 0.10 to 0.15 mm.

diameter, a viscose containing 6% to 15% of cellulose, not over 6% of sodium hydroxide, and prepared from unripened alkali cellulose by xanthogenation with more than 50% carbon disulphide, having a viscosity of at least 400 poises and having a -value above 60, stretching the filamentary products at the spinneret and further stretching them by 100 to 200%, and thereafter de-acidifying the products and fixing them in water at -90 C. i

11. A process forthe production of viscose rayon, artificial'staple fibre, hair, braid and the like which comprises extruding in filamentary form into a coagulating bath containing 10 to 15 gper litre of sulphuric acid at room temperature via spinnerets with holes of 0.10 to 0.15 mm. diameter, a viscose containing 10 to 15% of cellulose, not over 6% of sodium hydroxide, and prepared from ripened alkali cellulose by xanthogenation with more than 50% of carbon disulphide, having a viscosity of at least 400 poises and having a 'yr-value above 60, stretching the filamentary products at the spinneret and further stretching them by to 200%, and thereafter de-acidifying the products and fixing them in water at 85-90 C.

12. A process for the production of-viscose rayon, artificial staple fibre, hair, braid and the like which comprises extruding in filamentary form into a coagulating bath containing 10 to 15 g. per litre of sulphuric acid at room tempera- I ture via spinnerets with holes of 0.10 to 0.15 mm.

de-tensioning the products, passing them through water at 8590 C. and winding them continuously with their production.

13. A process for the production of viscose rayon, artificial staple fibre, hair, braid and the like which comprises extruding in filamentary form into a coagulating bath containing 10 to 15 g. per litre of sulphuric acid at room temperature via spinnerets with holes of 0.10 to 0.15 mm. diameter, a viscose containing 10 to 15% of cellulose, not over 6% of sodium hydroxide, and prepared from ripened alkali cellulose by xanthogenationwith more than 50% of carbon disulphide, having a viscosity of at least 400 poises and having a w-value above 60, stretching the filamentary roducts at the spinneret and further stretching them by 100 to 200%,and thereafter de-tensioning the products, passing them through water at 8590 C. and winding them continuously with their production.

14. A process for the production of viscose rayon, artificial staple fibre, hair, braid and the like which comprises extruding in filamentary form into a coagulating bath of sulphuric acid of concentration 1 to 15 g./litre at room temperature, a viscose containing 6% to 15% of cellulose,

not over 6% of sodium hydroxide, and prepared from unripened alkali cellulose by xanthogenation with more than 50% carbon disulphide, having a viscosity of at least 400 poises and having a v-value above 60, drawing the filamentary product in a straight line from the extrusion orifice through a tube immersed in said coagulating bath, of such diameter that liquid is drawn through the tube solely by the motion of the filamentary product, and thereafter fixing the filamentary product by treatment in hot aqueous liquid. 7

15.A process for the production of viscose rayon, artificial staple fibre, hair, braid and the,

like-which comprises extruding in filamentary form into a coagulating bath of sulphuric acid of concentration 1 to 15 g./1itre at room temperature, a viscose containing to of cellulose, not over 6% of sodium hydroxide, and prepared from ripened alkali cellulose by xanthogenation with more than 50% of carbon disulphide, having a viscosity of at least 400 poises and having a -value above 60, drawing the filamentary product in a straight line from the extrusion orifice through a tube immersed in said coagulating bath, of such diameter that liquid is drawn through the tube solely by the motion of the filamentary product, and thereafter fixing the filamentary product by treatment in hot aqueous liquid.

16. A process for the production of viscose rayon, artificial staple fiber, hair, braid and the like which comprises extruding in filamentary form into a coagulating bath of sulphuric acid of concentration 1 g./litre at room temperature, a viscose containing 6% to 15% of cellulose, not over 6% of sodium hydroxide, and prepared from unripened alkali cellulose by xanthogenation with more than 50% carbon disulphide, having a viscosity of at least 400 poises and having a y-value above 60, and thereafter fixing the filamentary product by treatment in hot aqueous liquid.

17. The method of spinning viscose for the manufacture of rayon and the like which comprises ejecting a solution of unripe viscose containing 6% to 15% of cellulose, not over 6% of sodium hydroxide, and having a 'y-value of at least 60 and a viscosity of at least 400 poises at a controlled rate from a spinneret having holes of from .10 mm. to .15 mm. diameter into a coagulating bath, and drawing the filaments in a straight line from said spinneret through a straight tube immersed in said bath and of a diameter such that liquid is drawn through the tube solely by the motion of the filaments.

18. The method of spinning viscose for the manufacture of rayon and the like which comprises ejecting a solution of unripe viscose having a 'y-value of at least 60 and a viscosity 01 at least 400 poises, the said viscose solution containing 9.5% to 15% of cellulose and not over 6% of caustic soda, at a controlled rate from a spinneret having holes of .10 mm. to .15 mm. diameter into a coagulating bath, and drawing the filaments in a straight line from said spinneret through a straight tube immersed in said bath and of a diameter such that liquid is drawn through the tube solely by the motion of the filaments.

19. The method of spinning viscose for the manufacture of rayon and the like which comprises ejecting a solution of unripe viscose having a 'y-value of at least 60 and a viscosity of at least 400 poises, the said viscose solution containing at least 9.5% of cellulose and at most 6% of caustic soda and having a degree of polymerization in excess of 500, at a controlled rate from a spinneret having holes of .10 mm. to .15 mm. diameter into a coagulating bath, and drawing the filaments in a straight line from said spinneret through a straight tube immersed in said bath and of a diameter such that liquid is drawn through the tube solely by the motion of the filaments.

20. The method of spinning viscose for the manufacture of rayon and the like which comprises ejecting a solution of unripe viscose containing 6% to 15% of cellulose, not over 6% of sodium hydroxide, and having a 'y-value of at least 60 and a viscosity of at least 400 poises at a controlled rate from a spinneret having holes of .10 mm. to .15 mm. diameter into a coagulating bath, and drawing the filaments in a straight line from said spinneret through a straight tube immersed in said bath and of a diameter such that liquid is drawn through'the tube solely by the motion of the filaments, the drawing of the filaments being such as to cause a positive stretching of the filaments.

21. The method of spinning viscose for the manufacture of rayon and the like which comprises ejecting a solution of unripe viscose containing 6% to 15% of cellulose, not over 6% of sodium hydroxide, and having a -value of at least 60 and a viscosity of at least 400 poises at a controlled rate from a spinneret having holes of .10 mm. to .15 mm. diameter into a coagulating bath, and drawing the filaments in a straight line from said spinneret through a straight tube immersed in said bath and of a diameter such that liquid is drawn through the tube solely by the motion of the filaments, the drawing of the filaments being such as to cause a positive stretching of the filaments, and stretching the filaments leaving the coagulating bath by a further to 200%.

22. The method of spinning viscose for the manufacture of rayon and the like which comprises ejecting a solution of unripe viscose containing 6% to 15% of cellulose, not over 6% of sodium hydroxide, and having a 'y-value of at least 60 and a viscosity of at least 400 poises at a controlled rate from a spinneret having holes of .10 mm. to .15 mm. diameter into a coagulating bath consisting of a 1% solution of sulphuric acid, and drawing the filaments in a straight line from said spinneret through a straight tube immersed in said bath and of a diameter such that liquid is drawn through the tube solely by the motion of the filaments, the drawing of the filaments being such as to cause a positive stretching of the filaments, and stretching the filaments leaving the coagulating bath by .a further 100% to 200%.

23. The method of spinning viscose for the manufacture of rayon and the like which comprises ejecting a solution of unripe viscose containing 6% to 15% of cellulose, not over 6% of sodium hydroxide, and having a 'y-value of at least 60 and a viscosity of at least 400 poises at a controlled rate from a spinneret having .10 mm. to .15 mm. diameter into a coagulating bath consisting of a 1% solution of sulphuric acid, and drawing the filaments in a straight line from said spinneret through a straight tube immersed in said bath and of a diameter such that liquid is drawn through the tube solely by the motion of the filaments, the drawing of the filaments being such as to cause a positive stretching of the filaments, and stretching the filaments leav- NICOLAS DRISCH. PAUL HERRBACH.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Name Date Fink et a1 Aug. 24, 1943 Number

Claims

1. A PROCESS FOR THE PRODUCTION OF VICOSE RAYON, ARTIFICIAL STAPLE FIBRE, HAIR, BRAID AND THE LIKE WHICH COMPRISES EXTRUDING IN FILAMENTARY FORM INTO A COAGULATING BATH OF SULPHURIC ACID OF CONCENTRATION TO THE 15 G./LITRE AT ROOM TEMPERATURE, A VISCOSE CONTAINING 6% TO 15% OF CELLULOSE, NOT OVER 6% SODIUM HYDROXIDE, AND HAVING A VISCOSITY OF AT LEAST 400 POISES AND HAVING Y-VALUE ABOVE 60, AND THEREAFTER FIXING THE FILAMENTARY PRODUCT BY TREATMENT IN HOT AQUEOUS LIQUID.