US3097414A - Woodell - Google Patents

Description

July 16, 1963 R. WOODELL 3,097,414

CRIMPABLE FIBERS OF REGENERATED CELLULOSE Filed Oct. 50, 1958 2 Sheets-Sheet 1 INVENTOR RUDOL PH WOODELL ATTORNEY July 16, 1963 R. WOODELL 3,097,414

CRIMPABLE FIBERS OF REGENERATED CELLULOSE Filed Oct. 50, 1958 2 Sheets-Sheet 2 INVENTOR R UDOL PH WOODELL ATTORNEY United States Patent 3,097,414 CRIMPABLE FIRE 0F REGENERATED CELLULOSE Rudolph Woodell, Kinston, N.C., assignor, by mesne assignments, to Beaunit Corporation, a corporation of New York Filed Oct. 30, 1958, Ser. No. 770,656 2 Claims. (Cl. 28-452) This invention relates to novel and useful crimpable rayon fibers, and a process for their production.

The production of crimpable filaments by extruding two or more viscoses, having different shrinkage potentials, through the same spinneret hole is known. While these multi-component filaments are superior in certain respects to single component filaments, i.e., in ease of crimping and crimp retention, they are deficient in other characteristics such as abrasion resistance and resistance to soiling.

It is an object of this invention to provide a new and useful crimpable viscose rayon fiber.

Another object is to provide a crimpable fiber which crimps readily in water and has excellent crimp retention, abrasion resistance and resistance to soiling.

Another object is to provide a process for producing such fibers.

These and other objects will become apparent in the course of the following specification and claims.

In accordance with the present invention a viscose rayon fiber is provided consisting of two components, a first component having a transverse cross-section characterized by a smooth substantially uncrenulated contour and a thick, preferably at least 80% skin, and a second component having a transverse cross-section characterized by a smooth contour and a core surrounded by a skin, the percentage of skin in the second component being substantially less than the percentage of skin in the first component and the two components being fused together along their entire length to form a single coherent fiber. Preferably the second component has at least about 20% less skin than the first component. It is also preferable that each component is substantially oval in shape and the two components are joined in such manner that their long axes, if extended to intercept one another, form a T.

The process for forming the yarn described above comprises preparing two viscoses, A and B, adding to viscose A a small amount of cyclohexylamine as a coagulation modifier, extruding the two viscoses simultaneously in side-by-side relationship through the same spinneret hole into a coagulating and regenerating bath containing from about 6.5 to about 10% sulfuric acid, from about 12 to about 23% sodium sulfate, at least about zinc sulfate, and a small amount of cyclohexylamine, viscose A having a salt index of at least 5, viscose B having a salt index of at least 2, and stretching the yarn. Preferably the salt index of viscose A is at least 3 units higher than that of viscose B.

FIGURE 1 is an exploded view of a device useful in the extrusion of the yarn of the present invention.

FIGURE 2 is a rear view of the equalizer and separator section of the device illustrated in FIGURE 1.

FIGURES 3 and 4 are illustrations of the yarn cross sections produced as described in Examples I and III respectively.

The following examples are cited to illustrate the invention. They are not intended to limit it in any manner. The apparatus used in each example is that shown in FIGURE 1. The yarn produced is extruded through the orifices 1 of spinneret plate 2, the said plate being positioned against the equalizer and separator section 3 by means of internally threaded spinneret adapter 4,

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flange 5 of the spinneret plate being held against the front face of the equalizer and separator section by the face 6 of the said spinneret adapter. Concentric cylindrical separator rings 7 extend through the equalizer and separator section, the said rings being supported by the pressure equalizer plate 8 (shown in FIGURE 2) which holds them in fixed relation to the circumference of the said equalizer and separator section. The concentric cylindrical separator rings are beveled to a sharp edge which extends beyond the engaging threads of the equalizer and separator section to such an extent that when the spinneret plate 2 is positioned as previously described the sharp edges of the separator rings are immediately adjacent to the back face of spinneret plate 2 and so arranged that each edge bisects each orifice in a particular ring of the said orifices. Pressure equalizer plate 8 (FIGURE 2) contains concentrically arranged holes 9 fitting into spaces between the concentric separator rings previously described and act to control the pressure of, and prevent pressure surges in, viscose delivered to the spinneret plate. Pressure equalizer plate 8 fits by threaded means onto a concentric conduit 10 which contains openings 11 through which various viscoses may be pressure fed to the system.

Example I Two viscoses, A and B are prepared in the conventional manner. Viscose A containing 8% recoverable cellulose, and 7% alkali, calculated as sodium hydroxide, is prepared from cotton linters pulp using 30% carbon disulfide based on the air dry weight of the pulp. Sulficient cyclohexylamine is added to the viscose during the mixing operation to give a concentration of 0.15% by weight. Viscose B is prepared in an identical fashion except that the cyclohexylamine is omitted. Viscose A is ripened to a salt index of 8.3 and a viscosity of 40 poises while viscose B is ripened to a salt index of 2.7 and a viscosity of 45 poises. Viscoses A and B are then supplied by means of separate gear pumps, each having a delivery of 158 gpm to alternate openings of a concentric conduit as illustrated in FIGURE 1. In this manner the two viscoses are extruded through each of the spinneret holes in side-by-side relationship by means of the separator rings and pressure equalizer assembly. A spinneret of 1 inches diameter having 250 holes of 0.008 inch diameter arranged in three concentric circles, the diameter of the circles being /2 inch, 1 inch, and 1% inches respectively is employed.

The viscoses are extruded into a coagulating and regenerating bath containing 9.0% sulfuric acid, 17.5% sodium sulfate, 9.5% zinc sulfate, and 0.1% cyclohexylamine, the temperature of the bath being 60 C. The filaments are lead for a distance of 31 inches through the bath, then over a Y convergence guide and for a further distance of 119 inches, the yarn being confined in the bath by means of a series of roller guides. By means of tension type roller guides, the yarn is stretched 29% between the spinneret and wind-up based on jet velocity and Wind-up speed. The yarn is led upwardly from the coagulating bath to and around a power-driven feed wheel, then downwardly to a centrifugal spinning bucket where it is Wound into a cake in the conventional manner. The peripheral speed of the feed wheel is 50 y.p.m. The yarn is purified and dried in the conventional manner. Thereafter it is passed through a slashing machine where it is treated with a hot aqueous finish solution, stretched 12% and then dried under tension and wound onto pirns.

The yarn filaments are examined by cutting thin transverse cross-sections in the conventional manner, dyeing these cross sections and examining them under high magnification. The cross sections are dyed following the method described by Morehead and Sisson, Textile Research Journal, 15, 4445 (1945) except that pontamine yellow dye is substituted for calcomine yellow dye. Measurements made on ten filament cross'sections selected at random give an average of 90% skin for one portion of the cross section while the other portion had an average of 57% skin. Both parts of the cross section are substantially uncrenulated and shaped as illustrated in FIG- URE 3. The filament denier of the finished yarn is 22 denier per filament. When the yarn is placed in water at 90 to 100 C. in a relaxed state followed by drying in a relaxed state, it is found that the yarn has an excellent crimp. On repeated wetting and drying of the yarn, the crimp is retained substantially to the same extent as found in the original crimped yarn. When the yarn is fabricated into a tufted carpet in the conventional manner, the carpet is found to have superior abrasion resistance and resistance to soiling as compared to similar carpets fabricated from conventional crimped yarns.

Example 11 Two viscoses, C and D, are prepared, viscose C being prepared in the same manner as viscose IA of Example I and viscose D being prepared in the same manner as viscose B of Example I. Viscose C is ripened to a salt index of 8.0 and a viscosity of 81 poises while viscose D is ripened to a salt index of 2.7 and a viscosity of 95 poises. The two viscoses are then supplied to a common spinneret by means of separate gear pumps, each having a delivery of 58.1 g.p.m. The viscoses are extruded through a spinneret of 1 inch diameter, having 120 holes of 0.008 inch diameter arranged in two concentric circles, the diameter of the circles being inch and 4 inch respectively. The two viscoses are extruded through each of the spinneret holes as described in Example I into the coagulating bath of Example I. The filaments are led for a distance of 44 inches through the bath, then over a Y convergence guide and for a further distance of 170 inches, the yarn being confined in the bath by means of a series of roller guides. The yarn is then led upwardly from the coagulating bath to a first power driven 'feed wheel, then to a second power driven feed wheel rotating at the same speed as the first but having a sufficiently larger diameter tostretch the yarn 46%. A hot aqueous solution containing 2.0% sulfuric acid, 3.9% sodium sulfate and 2.1% Zinc sulfate at a temperature of 93 C. is jetted onto each of the feed wheels at the top. By means of a snubbe-r roller in combination with each feed wheel, the yarn is given a sufiicient number of passes around the feed wheel to give the yarn a travel of 160 inches in this area. The yarn is led from the second feed Wheel, which has a peripheral speed of 50 y.p.m., downwardly to 13. centrifugal spinning bucket where it is wound into a cake in the conventional manner. The yarn is purified and dried in the conventional manner. Thereafter it is passed through a slashing machine where it is first passed through a hot aqueous finish solution, stretched 12% and then dried under tension and wound onto pirns. The yarn denier is 2400.

When the yarn is relaxed in a hot water bath at 90 to 100 C. and then dried in a relaxed state, it has an excellent crimp. When the yarn is fabricated into a tufted carpet, the results are substantially the same as found in Example I with filament cross sections substantially the same as in Example I. The filament denier of the finished yarn is denier per filament.

Example III Viscoses are prepared and spun and the yarn purified exactly as described in Example II except that each viscose is extruded at a rate of 72.8 g.p.m. to give a yarn of denier per filament. On examination of the filament cross sections as described in Example I, the skin in one portion of the cross section is found to amount to 77% of the total area on the average while in the other section.

portion of the cross section 44% of the total area is skin. The two portions of the cross section are substantially uncrenulated and the shape of the cross sections are substantially as shown in FIGURE 4.

When the yarn is relaxed in hot water at -100 C. and then dried in a relaxed state, it has an excellent crimp. When the yarn is fabricated into tufted carpets, the results are substantially the same as found in Example I.

The foregoing examples illustrate the advantages of the novel and useful crimped fibers of the present invention. By providing a filament having a relatively thick skin as compared to the crimped yarns of the prior art, the strength and abrasion resistance of the fiber is improved, while the smooth substantially uncrenulated contour leads to improved resistance to soiling. In addition, the unique shape of the cross section provides relatively high bulk.

The essential factor in producing the fibers of this invention is the extrusion of two viscoses, one containing cyclohexylamine modifier and the other containing no modifier, into a coagulating and regenerating bath containing a small amount of cyclohexylarnine modifier and a substantial concentration of zinc sulfate. The combination of modifier in the viscose and in the bath gives one component of the filament a heavy skin and a noncrenulated contour while the other component has a much thinner skin but still has a substantially non-crenulated contour due to the action of the modifier in the bath. The zinc salt in the bath is required since the coagulation modifier is not effective in its absence.

The amount of cyclohexylamine required in the viscose will vary depending upon the viscose composition, the coagulating bath composition and other factors. However, in general it is desirable to have at least 0.05% present. Too much modifier in the viscose should be avoided for reasons of economy and to avoid spinning difficulties. For optimum results, the amount of modifier in the viscose should be adjusted to the level required to give from about 90 to about skin in the cross This can usually be accomplished by using concentrations in the range of from about 0.1 to about 0.25%, although under some conditions it may be desirable to use larger amounts in the range of from about 0.5 to about 1.0%.

The minimum amount of cyclohexylamine modifier in the coagulation bath should be at least about 0.05% and the amount used should be regulated in relation to the amount used in the viscose so that the skin thickness of the filament component formed from the unmodified viscose is substantially less than the skin thickness of the filament component formed from the modified viscose. The amount required for this purpose will vary depending on the composition of the coagulating bath, the amount of modifier used in the viscose and other conditions but ordinarily will fall in the range of from about 0.05 to about 0.25%. The regulation of the modifier in the bath is easily accomplished by one skilled in the art. Since the cyclohexylamine added to the viscose is leached from the spinning filaments into the bath, it is usually not necessary to add the material directly to the bath. In some cases, however, it may be desirable to remove part of the cyclohexylamine from the bath in order to avoid unduly high concentrations. This may be conveniently accomplished by carbon adsorption as described in US. 2,787,618 or by other suitable methods.

The composition of the viscoses used in the process of this invention is not critical. V-iscoses produced with from about 27 to about 43% carbon disulfide based on the dry weight of the pulp used are satisfactory. The viscose may contain from about 5.5 to about 9.5% recoverable cellulose and from about 4.0 to about 8.0% alkali calculated as'sodium hydroxide. The ripeness or maturity of the viscose at spinning may vary from about 5 to about 15 units as measured by the salt index method for the viscose containing the cyclohexylamine modifier and from about 2 to about 15 salt index units for the other viscose. It is preferable, although not essential, that the viscose containing ithfi cyclohexylamine modifier have -a salt index at spinning about 3.0 units higher than the other viscose.

Coagulating and regenerating baths suitable for use in the present invention may contain from about 6.5 to about sulfuric acid, from about 12 to about 23% sodium sulfate and at least about 3% zinc sulfate in addition to the cyclohexylamine modifier. Other metal salts which may supplement the action of the zinc sulfate may be added if desired. The acidity of the bath should be regulated to as low a level as is commensurate With satisfactory spinning.

The yarn should be stretched at least about 40% While passing through the bath. Where a hot secondary bath is used, the stretch may be concentnated in this bath or it may be divided between the two baths as may be desired.

After the yarn leaves the bath, it is wound into a cake in a centrifugal spinning bucket or Wound on a bobbin and thereafter purified and dried in the conventional manner.

Afler purification, the yarn is preferably given additional stretch after thorough wetting and is then dried in the stretched condition. The stretching is conveniently applied by passing the yarn through a slashing machine of the type used in the production of tire cord yarn. If the customary aqueous finish is applied to the yarn, the yarn is Wetted with this before stretching.

The yarn crimps readily when allowed to relax in hot water followed by drying in a relaxed state. Instead of water, various aqueous solutions as are well known in the art may be used in the crimping operation.

While the process of this invention is suitable for producing low denier per filament yarns, it is particularly advantageous in the production of high denier per filament, i.e. above 10 d.p.f., Water crimpable yarns.

The fibers of this invention may be used wherever rayon fibers are customarily employed. However, they are particularly suitable for the production of tufted carpets and cut pile fabrics.

Many modifications of the invention described herein will be apparent to those skilled in the art from a reading of the above without a departure from the inventive concepts.

What is claimed is:

1. A regenerated cellulose fiber consisting essentially of a pair of substantially oval cross section components fused together along their entire lengths so that the long axes of said oval cross sections form a T when extended to the point of interception, each of said components having a smooth substantially uncrenulated contour, and comprising a core completely surrounded by a thick skin, one of said components having at least 20% more skin by cross sectional area than the other.

2. A regenerated cellulose fiber as defined in claim 1 wherein one of said components has at least skin by cross sectional area.

References Cited in the file of this patent UNITED STATES PATENTS 1,944,378 Thenoz Jan. 23, 1934 2,234,763 Hoelkeskamp Mar. 11, 1941 2,310,785 Herrmann Feb. 9, 1943 2,337,969 Bugge Dec. 28, 1943 2,439,814 Sisson Apr. 20, 1948 2,517,694 Merion et a1. Aug. 8, 1950 2,535,044 Cox Dec. 26, 1950 2,535,045 Cox Dec. 26, 1950 2,572,217 Thurmond Oct. 23, 1951 2,572,936 Kulp Oct. 30, 1951 2,674,025 Ladisch Apr. 6, 1958 FOREIGN PATENTS 514,638 Great Britain Nov. 14, 1939 51,307 Netherlands Oct. 15, 1941

Claims (1)

1. A REGENERATED CELLULOSE FIBER CONSISTING ESSENTIALLY OF A PAIR OF SUBSTANTIALLY OVAL CROSS SECTION COMPONENTS FUSED TOGETHER ALONG THEIR ENTIRE LENGTHS SO THAT THE LONG AXES OF SAID OVAL CROSS SECTIONS FORM A T WHEN EXTENDED

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