US3007766A

US3007766A - Production of viscose rayon

Info

Publication number: US3007766A
Application number: US781491A
Authority: US
Inventors: Elssner Richard; Elling Gertrud
Original assignee: American Enka Corp
Current assignee: Akzona Inc
Priority date: 1958-01-04
Filing date: 1958-12-19
Publication date: 1961-11-07
Anticipated expiration: 1978-11-07
Also published as: DE1052054B; BE574151A; GB864821A; FR1211235A; NL107735C; NL234167A; CH411220A

Description

dfidlfidii Patented Nov. 7, 1961 PRODUCTION F VISCOSE RAYON Richard Elssner, Randerath, Germany, and Hugo Elling,

deceased, late of Oberbruch-Grebben, Germany, by

Gertrud Elling, sole heir, Oberbruch-Grebben, Germany, assignors to American Enlra Corporation, Enka,

N.C., a corporation of Delaware No Drawing. Filed Dec. 19, 1953, Ser. No. 781,491

Claims priority, application Germany Jan. 4, 1958 3 Claims. (Cl. 18-64) This invention relates to the production of rayon threads and fibers and more particularly to the production of such threads and fibers having low elongation values and high strength values.

The threads or fibers having such low elongation values and high strength values find particular use in rubber products.

In order to define the relationship between the strength and elongation, the following formula has been developed: modulus M=1OO times break strength (grams/ den.):-elongation percent. Thus, if it is desired to obtain a thread or fiber of low elongation with a high break strength, it is necessary to obtain one with a high modulus.

In order to illustrate this comparison, the following Table I is provided which compares the normal rayons (Nos. and 6) with cotton (No. 1) and certain special rayons (Nos. 2, 3 and 4).

It will be seen from an observation of this table that the moduli of Fortisan, a rayon produced by the saponification of acetate cellulose, and Lilienfeld rayon, are higher than that of cotton. However, both of these fibers are difficult to manufacture. Normal rayons show very low moduli which renders them undesirable, and it is only the special rayon (No. 4) which approaches the desirable modulus, but even this is lower than desired. This special rayon was prepared by viscose being spun after addition of 1.5 grams per kilogram of viscose of an ethoxylated coconut oil amine in a spinning bath containing zinc sulfate and formaldehyde.

It is therefore an object of the present invention to provide a process for manufacturing rayon threads and fibers of improved physical properties.

An additional object of the present invention is to provide a simple and economical process for manufacturing rayon blends and fibers of low elongation values and high strength values.

it is a further object of this invention to provide a rayon fiber or thread having low elongation value and high strength value.

It has been found by the present invention that rayon threads and fibers of low elongation values and high breaking strength and therefore high moduli can be obtained by adding to the viscose rayon solution a watersoluble alkali metal salt of a strong acid. Up to 50 grams/ kg. of such a salt may be added. This will be in addition to the use of also-called modifier in the viscose, such as an ethoxylated amine or similar agent such as ethoxylated fatty acids or alcohols, polyethylene glycols, amines, polyamines, quaternary ammonium compounds,

or their ethoxylated derivatives. The modifier may be present to the extent of 0.3 to 3.0 grams/kg. of viscose.

The preferred method of accomplishing this invention is to add the alkali metal salt to the caustic soda dissolving solution for the cellulose Xanthate.

The thus obtained viscose, after it has been filtered, deaerated, and finally ripened in the known manner, is spun into a spin bath containing sulfuric acid, zinc sulfate and sodium sulfate. The thread or fiber is then passed into an intermediate bath containing sulfuric acid, Zinc sulfate, sodium sulfate and preferably formaldehyde, and finally into a second acid bath containing sulfuric acid, zinc sulfate, sodium sulfate and preferably formaldehyde in different concentrations than used in either the first acid bath or the intermediate bath. Thereafter the thread or fiber thus obtained is simultaneously stretched and dried.

The alkali metal salt of the strong acid may be any one of the following which have been found to accomplish the objects of this invention: sodium sulfate, sodium chloride, potassium sulfate, potassium chloride, sodium nitrate or potassium nitrate. The alkali metal salts of phosphoric acid have been found to give a lower moduli than the above listed salts. The salts of weak acids are ineffective and will not accomplish the objects of this invention.

The following Tables II and III illustrate the effect of using various quantities of sodium sulfate and sodium chloride, respectively, in the process of this invention. These salts were added, together with 1.5 grams of an ethoxylated coconut oil amine of a molecular weight of about 1100 per kilogram of viscose.

Table II Amount of Strength, Elongation, Modulus Na SOi g./den. percent No. added to the viscose,

gjkg. dry wet dry wot dry wet Table III Strength, Elongation, Modulus Amount of N aOl added to the gJden. percent viscose, gjkg. dry wet dry wot dry wet l 5.1 4.1 14 j 28 3e 15 5.0 3.8 11 1 23 46 17 5.2 4.0 9 21 57 19 5.4 4.0 8 20 67 20 Thus the alkali metal salt may be added in proportions of 350 grams/kg. of viscose.

In addition, cords manufactured from the thus treated viscose and having the construction 1650 den. 1 x 2 ZXS 12 x 12 revealed the characteristics as shown in Table IV.

Table IV Cord 00nd. Cord ovendried Strength, Elonga Strength, Elongag./den. tion, Modulus g./den. tion, Modulus Percent Percent It has been shown that in the preferred operation of this invention the alkali metal salt is added to the viscose followed by addition of an ethoxylated coconut oil amine. This amine has the general formula:

in which n is between 8 and 14, x plus y=about 20 and and the molecular weight is about 1100.

In addition to this amine, other compounds such as ethoxylated fatty acids, ethoxylated fatty alcohols, polyethylene glycols, amines, polyamines, quaternary ammonium compounds, or their exthoxylated derivatives may also be used. These addition agents may be added in proportion of 0.3 to 3.0 grams/ kg. of viscose with the preferred proportion being 1.5 grams/ kg.

It is known that the breaking strength and therefore the moduli of threads and fibers may be increased further by stretching the thread or fiber during their drying which follows the second acid bath. In addition, further improvement may be obtained by adding to the intermediate bath 0.5 to 5% of formaldehyde.

The following Tabe V illustrates the effect of these two aids. The organic additive used in the examples below was used in these experiments.

Table V Strength, ElongagJden. tion, Modulus HCOH Drypercent iug dry wet dry Wet dry Wet Without NazSO4.---- 3. 8 3.1 29 32 13 With NazSOt.-. 3. 4 2. 4 14 19 24 13 with Na2SO4 3. 8 2. 7 8 8 48 33 with NiqSO4--- 4. 6 3. 3 9 10 51 32 in which n is between 8 and 14, x plus y=about and the molecular weight is about 1100, is added to the viscose in the proportion of 1.5 grams/ kg. of viscose.

This viscose, following filtering, deaeration, and ripening in the known manner, is spun with a gamma number of about 48 and a viscosity by the ball-falling test of 93 seconds. A spinning nozzle having 1000 orifices of a diameter of 60 microns each is used to obtain a titre of 1650 denier.

The spun thread runs from the spinning nozzle through a horizontally disposed tube of a length of 50 cm. and an internal diameter of 20 mm, which tube is submerged in an acid spinning bath. This bath is maintained at 48 C. and contains 4.3% sulfuric acid, 13.0% sodium sulfate, and 6.0% zinc sulfate. The spun thread leaves the tube and passes over a guide roller to a godet rotating at 19 m./ min.

The thread is caused to travel four times around this godet by a grooved roller arranged below it. This grooved roller is submerged in a so-called intermediate bath containing 22 grams/kg. sulfuric acid, grams/kg. sodium sulfate, 38 grams/ kg. zinc sulfate, and 18 grams/kg. formaldehyde and maintained at 30 C. The above proportions are expressed in grams per kilogram of bath solution.

From this intermediate bath, the thread passes around a second godet, rotating at a speed of 40 m./min., and through a second acid bath. This second acid bath contains 15 grams/kg. sulfuric acid and small amounts of sodium sulfate, zinc sulfate and formaldehyde. The proportion of the sulfuric acid is based on the total bath composition. The trajectory length of this second acid bath is 140 cm.

The thread passes from this second acid bath around a third godet rotating at 35.8 rn./min., into a slowly rotating bucket. The mass of threads While remaining in this bucket is deacidified, desulfurized and sized by any methods known in the art. Thereafter, the thread is removed from the bucket and stretched 11% in a final stretching assembly While being simultaneously dried.

The thread produced by this method is indicated in Table II as No. 6. The thread has a very desirable high breaking strength, low elongation value and therefore a high modulus.

In the operation of this invention, cellulose of any origin may be used, such as linters, high-grade celluloses, and standard rayon celluloses. It is possible to vary the cellulose content or the cellulose/caustic ratio without departing from the scope of this invention.

The viscose solutions obtained by the process of this invention are spun with a gamma number between 56 and 35 into acid baths which contain preferably more than 20 grams/ kg. of zinc sulfate. In addition, the spinning baths may contain viscose and/or spinning auxiliaries such a lauryl pyridinium chloride, or other surface-active agents.

While the present invention has been described in a preferred manner, it will be understood that many changes and modifications may be made in the methods of procedure without departing from the scope of this invention.

What is claimed is:

1. A process for the production of high strength viscose rayon threads and fibers having a high modulus determined by the following formula: M S divided by E, wherein M is the modulus, S is the dry strength in grams per denier, and E is the dry elongation, which comprises extruding viscose containing about 3.0 to 50 grams per kilogram of viscose, of an alkali metal salt of the class consisting of sodium sulfate and potassium sulfate, about 0.3 to 3.0 grams per kilogram of viscose, of a modifier of the class consisting of polyethylene glycols, ethoxylated amines and their quaternizedderivatives, into an aqueous acid zinc-containing spin bath, passing the thus produced threads to an intermediate bath containing formaldehyde, and finally collecting the threads.

2. A process according to claim 1 in which the alkali metal salt is sodium sulfate.

3. A process according to claim 1 in which the modifier is ethoxylated coconut oil amine of the general formula:

(CH2. SE20) XH Cn 2n+l N (enacmonn in which n is between 8 and 14 and x plus y equals about 20.

4. A process according to claim 1 in which about 0.5% to 5.0% by weight of formaldehyde is used in the intermediate bath.

5. A process according to claim 4 in which the intermediate bath is maintained at about room temperature.

6. A process according to claim 5 in which the threads after having been collected and purified are dried under tension.

7. A process for the production of high strength vis- M=100 S divided by E wherein M is the modulus, S is the dry strength in grams per denier, and E is the dry elongation, which comprises extruding viscose containing about 3.0 to 50 grams per kilogram of viscose, of an alkali metal salt of the class consisting of sodium sulfate and potassium sulfate, about 0.3 to 3.0 grams per kilogram of viscose, of a modifier of the class consisting of polyethylene glycols, ethoxylated amines and their quaternized derivatives, into an aqueous acid zinc-containing spin bath, passing the thus produced threads to an intermediate bath containing taining formaldehyde, and finally collecting the same. 8. A process according to claim 7 in which the threads after having been collected and purified are dried under tension.

References Cited in the file of this patent formaldehyde, passing the threads to a third bath con- 15 2,937,070

UNITED STATES PATENTS Coe Apr. 6, 1948 Kayser Oct. 26, 1948 Thurmond Oct. 23, 1951 Lekkerkerker Apr. 2, 1957 Cox et a1. Sept. 16, 1958 Hollihan et a1. Sept. 16, 1958 Cox May 17, 1960

Claims

1. A PROCESS FOR THE PRODUCTION OF HIGH STRENGTH VISCOSE RAYON THREADS AND FIBERS HAVING A HIGH MODULES DETERMINED BY THE FOLLOWING FORMULA: M=100XS DIVIDED BY E, WHEREIN M IS THE MODULUS, S IS THE DRY STRENGTH IN GRAMS PER DENIER, AND E IS THE DRY ELONGATION, WHICH COMPRISES EXTRUDING VISCOSE CONTAINING ABOUT 3.0 TO 50 GRAMS PER KILOGRAM OF VISCOSE, OF AN ALKALI METAL SALT OF THE CLASS CONSISTING OF SODIUM SULFATE AND POTASSIUM SULFATE, ABOUT 0.3 TO 3.0 GRAMS PER KILOGRAM OF VISCOSE, OF A MODIFIER OF THE CLASS CONSISTING OF POLYETHYLENE GLYCOLS, ETHOXYLATED AMINES AND THEIR QUATERNIZED DERIVATIVES, INTO AN AQUEOUS ACID ZINC-CONTAINING SPIN BATH, PASSING THE THUS PRODUCED THREADS TO AN INTERMEDIATE BATH CONTAINING FORMALDEHYDE, AND FINALLY COLLECTING THE THREADS.