US3350488A - Process for the production of sharp-edge fibers - Google Patents

Description

Oct. 31, 1967 A. L. BREEN 3,350,488

PROCESS FOR THE PRODUCTION OF SHARP-EDGE FIBERS Original F-iled May 27, 1958 2 Sheets-Sheet 1 I A. L. BREEN Oct. 31', 1967 PROCESS FOR TEE PROD Original Filed May 27, 1958 2 sheet$-sheet 2 United States Patent Ofi 3,350,488 PROCESS FOR THE PRODUCTION OF SHARP-EDGE FIBERS Alvin Leonard Breen, Wilmington, Del., assignor to E. I. du Pont de Nemours and Company, Wilmington, Del., a corporation of Delaware Original applications May 27, 1958, Ser. No. 738,166, and June 7, 1962, Ser. No. 200,758, now Patent No. 3,188,689, dated June 15, 1965. Divided and this application Mar. 3, 1965, Ser. No. 436,888

4 Claims. (Cl. 264-171) This 200,75 No. 3,188,689 and of cation Ser. No. 738,166, filed May 27, 1

This invention relates to the man of a novel cross-section.

Much effort has be of fabrics th abandoned appli- 958. ufacture of filaments The desirability of producing textile filaments having one or more sharp longitudinal edges for obtaining silklike fabrics has long been recognized. Despite numerous proposals mainly drawn to extrusion orifice designs, it has not been feasible to aments having sharp edges in cross-section by the extrusion of melts or solutions of fiber-forming polymers. This is due to the fact that the surface of a filament formed an orifice tends to assume the cross a circle, the smallest boundary forth al area.

One object of this invention is to produce filaments of polymers having-one or more sharp longi- -sectional contour of e given cross-sectiontudinal edges.

A further object is the preparation of a fabric that has the properties of silk. Other objects will become apparent in the course of the following discussion.

In accordance with one embodiment of the invention a composed of segments of at least two dissimilar synthetic tions, said cross-section having at least aid polymers, any conthe filament may beseparated into its component n. Alternatively, all sections as in a plane or curvilinear triangle; or a multiplicity of sharp points such as in a figure formed by the joining of 2 or more simple segments as in a formee cross. Y

FIGURE 1 shows in axial section a spinneret assembly useful for this purpose. Front or bottom plate 1 with ori- 3350A Patented Oct. 31, 1S

lice

fices 2 is recessed at the back about plateau -like prot at the bottom of back rotational positioning of th FIGURE 2 shows a reduced view of the plan of th 25 front plate. Appearing in this view are four plateaus, eacl into its component sections by m 65 components should have low adhesi on to each othenQbusly this is not necessary where one component of the r is to be removed by dissolution or chemical decom- .ition. Because of their commercial availability, ease processing and excellent properties, the condensation ymers and copolymers, e.g., polyamides, polysuliamides and polyesters and particularly those that can readily melt spun are preferred for application in s method. Suitable polymers can be found for instance long the fiber-forming polyamides and the polyesters rich are described in such patents as US. Patents )71,250, 2,071,253, 2,130,523, 2,130,948, 2,190,770 and 465,319. The preferred group of polyamides comprises )ly(hexamethylene adipamide), poly (hexamethylene bacamide), poly(epsilon-caproamide) and the co- Jlymers thereof. Suitable polyesters, besides poly(ethyl- 1e terephthalate), are the corresponding copolymers )ntaining sebacic acid, adipic acid, isophthalic acid as ell as the polyesters containing recurring units derived om glycols with more than two carbons in the chain, .g., diethylene glycol, butylene glycol, decamethylene lycol and trans-bis-1,4-(hydroxy methyl)-cyclohexane.

Other groups of polymers useful as components in llaments of the present invention can be found among he polyurethanes, the polyureas, cellulose esters and :ellulose ethers as well as among the polyvinyl com- ;ounds including such polymers as polyethylene, polyicrylonitrile, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, and copolymers containing the monomers of these polymers and similar polymers as disclosed in US. Patents 2,601,256, 2,527,300, 2,456,360 and 2,436,926.

When it is desired to remove all sections composed of one polymer composition by dissolution, a solvent for such polymer is selected that will not dissolve or have an adverse effect on sections composed of other polymer compositions. Thus in Example I which appears below, formic acid was used to remove the polyamide sections from the filament having both polyester and polyamide sections in its cross-section. The extent of dissolution of the soluble portion can be controlled as desired.

Similarly, all sections composed of one polymer composition can be removed by chemical decomposition. Thus polyester sections of a polysegmented filament having alternate polyester and polyamide sections, would be degraded by treatment with hot caustic as would the copolyamide or polyurea portions of polysegmented filaments having copolyamide-polyacrylonitrile or polyureapolyacrylonitrile alternating sections by treatment with mineral acids.

In the examples, the relative viscosity (1 i.e., viscosity of a solution of polymer relative to that of the solvent is used as a measure of the molecular weight. The polyamide solutions contained 5.5 g. of polymer in 50 ml. of 90% formic acid and the viscosity was measured at 25 C. The polyester solutions contained 2.15 g. of the polymer in ml. of 7/10 mixture of tetrachlorophenyl/phenol and the viscosity was measured at 30 C.

Example I A spinneret similar to that shown in FIGURES 1 to 3 with 17 orifices was constructed. The plateau 4 was Vs in. in diameter and in. high. The counterbore 22 Was 40 mils in diameter and extended to within 48 mils of the face of the spinneret. The capillary 21 had a diameter of 12 mils. The lead hole 31 in the upper plate 7 was in. in diameter was drilled to within 94 mils of the bottom of plate 7. The upper orifices 32 were 9 mils in diameter and were drilled on a circle having a 39.5 mil radius the center of which was concentric with the upper lead hole and with the plateau in the orifice in the lower plate. The spinneret was assembled with a 3 mil thick shim 16.

Poly(hexamethylene adipamide) of a 36 was fed to chamber 9 of the spinneret and extruded to form the triangular segments of the filament and poly(ethylenc terephthalate) of 33 containing 0.3% of TiO was fed to annulus 8 and then through orifices 32 to form the formee cross segment of the filaments cross-section. The two molten polymers were extruded in the ratio of 9.5/ 10.0 by volume respectively at 290 C. and the yarn wound up at 1000 y.p.m. The yarn was drawn 4 (that is, to 400% of its original length) over an 88 C. pin and then passed over a 140 C. plate to reduce shrinkage. A cross-section of a typical filament is shown in FIGURE 7. The yarn had a tenacity of 3.9 g.p.d., an Mi (initial modulus, grams per denier) of 53, an ultimate elongation of 32% and a total denier of 50.

The yarn was knitted into a tubing which was quite lean in appearance and had poor visual covering power. The tubing was treated for 3 hours with 98% formic acid in a Soxhlet extractor, removed, rinsed with water and dried. Despite the loss of about 50% of the fiber weight by dissolution of the polyamide sections the visual covering power of the tubing was greatly increased. The extracted tubing had a soft silk-like handle and was scroopy. The cross-section of filaments remaining in the extracted fabric resembled a formee cross as shown in 108 of FIGURE 7.

Example 11 Using the same spinneret as in Example I, poly(ethy1- ene terephthalate) of 17, 26.9 containing 0.3% of TiO; was fed to chamber 8 of the spinneret and extruded as the segments of a composite filament designated 101 in FIGURE 4 while poly(hexamethylene adipamide) of m. 36 was fed to chamber 9 and extruded as the segments of a composite filament designated 102 in FIGURE 4. The polymers were extruded at 290 C. and the yarn wound up at 400 y.p.m. The yarn was drawn 43X over a 98 C. pin. The resulting yarn had a tenacity of 4.1 grams per denier, and initial modulus of 56 and had a denier per filament of 8.3. A portion of the drawn yarn was wound on a perforated metal bobbin and immer'sed in cold 98% formic acid for 3 hours. After rinsing and drying the residual polyester yarn had a tenacity of 3.8 g.p.d., a Mi of 73, an ultimate elongation of 28% and a total denier of 80 for the 68 filaments then present. typical cross-section of a filament is shown in 109 of FIGURE 8.

A portion of the original yarn was woven into a 2 X 2 twill fabric having 120 yarns per inch in the warp an 84 yarns per inch in the filling. The resulting fabric was immersed in 98% formic acid for minutes until the poly(hexamethylene adipamide) sectors were dissolved from the composite filaments. The fabric possessed all of the properties of a silk fabric as liveliness and drape, the subtle scroop of silk, the handle, the low denier per filament, the high modulus and good recovery properties.

A repetition of the above spin with positions of the 2 polymers changed gives filaments which after treatment with formic acid leaves fillet-shaped sectors of the polyester similar to segment 102 of FIGURE 4.

Example III The following example illustrates the different crosssections obtained by varying the volume of polymers delivered to various sectors of the composite filaments Using the spinneret of Example I with a three mil shim, poly(ethylene terephthalate) of n, 28.1 containing 2.0% of TiO was fed to chamber 8 of the spinneret and poly- (ethylene terephthalate) of n, 31 fed to chamber 9. The polymers were extruded at 290 C. and the yarn wound up at 1000 y.p.m. The volume of the two polymers entering the composite filaments were varied by adjustment of their respective constant displacement pumps. In the first spin the volumes of the pigmented polymer to the non-pigment polymer was 1:1 and filaments were obtained having cross-sections similar to that shown in FIG- URE 4. When the ratio of pigmented to bright polymer was set at 4/16, filaments with cross-sections similar to acetate portions of the filaments and leaves small dt FIGURE 5 were obtained. When the pumps were adfilaments of polyacrylonitrile of shape similar to justed to give a ratio of 16/4. as above cross-sections URE 8.

similar to FIGURE 6 were obtained. The composite filaments have been produced in The above spins are repeated replacing the unpigmented 5 examples by the melt spinning technique. Obvioi polyester with the copolyester poly[ethylene/poly(ethylother spinning methods like plasticized melt spinn ene oxide) glycol terephthalate] with a composition of dry spinning, wet spinning, can be employed successfi 80/20 by weight, the poly(ethylene oxide) glycol units In some instances particularly when the melting beha having a molecular weight of 6000. Upon immersing the or the solubility of the co yarns in a hot 5% solution of NaOH the segments cor- 10 would not permit spinning responding to 102, 104, 106 in FIGURES 4, 5 and 6 are methods, a combination of dissolved and residual cross-sections of poly(ethylene used. Thus, for instance, one component, can be spun h h l corresponding t 101, 103, 105 i FIG- a solution in a high boiling solvent or as a plasticized m URES 4, 5, and 6 remain in the respective yarns. While the other component is extruded as a mol l5 polymer In these instances, the solvents or plasticizt Example IV may be wholly or partially removed subsequently, pr erably by washing them out by the help of low boili Using the apparatus and polymers of Example I the l m positions of the two polymers were reversed. The polyester and polyamide were extruded at 290 C. at a ratio of 12/ 16 by volume respectively and the composite filaments Wound P at 5 00 Y-P- The Y Was drawn X in the art that by altering the shape of the orifice 21, tl

Over a P A typical cross-Section of the drawn nal cross-section can be controlled to a certain exter filament is shown in FIGURE 9. A portion of a yarn was Al h h in cross-section which resemble a square with rounde edge of a glass microscope slide under a tension of about 0 0.5 g.p.d. so that the yarn suffered a 90 change of direc- The composite filaments illustrated in this inventit 20 have substantially round cross-sections before separatit of the components. However, it will be apparent to tho st r and polyamlde segments 80 that the y Was other modificatlons of the composite filaments and henci Posed 0f filaments Whlch 1H Cross-86611011 resembled 1 of the shape of the residual filaments after dissolutior and 111 of FIGURE 9. 5 can be altered by changing the number and placement The filaments in the above drawn yarn were completely f t of 48 y p m using 2 cu ft of r P mlnllte at p S 1 are extruded through the upper orifices 32 and over the to operate the jet. plateau. Alteration of the viscosities of the component A portion of the above drawn yarn not exposed to polymers affects the configuration obtained A low v1sacetone or fragmented was wound on a perforated metal cosity polymer tends to be pushed mward more readily tube and placed in 98% formic acid at the boiling point by the flow for minutes. The tube and yarn was then placed in cold the shape of the segment th formic acid for an additional 15 minutes, rinsed with waration 1n the component filaments is also aflected by the ter and dried The residual polyester filaments which in interfacial tension and the individual tendencies of the cross-section resembled segment 110 of FIGURE 9 had polymers to wet the spinneret surfaces a tenacity of 3 6 g pd an ultimate elongation of 31% a Although the spmneret used in the examples 1s a con M1 of 68 and a denier per filament of 1 O..The yarn was venient apparatus for the preparation of the filaments of used as a filling face in the weaving of a satin with yarn t is invention it Wlll be obvious to those skilled in the of round cross-section, poly(ethylene terephthalate), as art that other spinnerets can be used. Other spinnerets a warp. The fabric had a dry, crisp, silk-like handle across permit the production of filaments or ribbons having althe filling band but was less silk-like than the fabric of ternating segments 112 and 113 as shown in FIGURE 10 Example 11. which can be split or dissolved apart to give sharp-edged Example V filaments.

The process of this invention affords a convenient Using the apparatus and polymers s in Ex mpl V, means of obtaining filaments having one or more sharp composite filaments are extruded and the continuous filapoints i cross section d of a lower d i h can b ments wound up at 5000 y.p.m. The yarn is dipped in otherwise attained Thus, the invention permits the proacetone and then drawn Over a P at The gduction of sharp-edged filaments having a denier of 0 1 to ments of polyester break and split during the drawing so 10 or larger. Its greatest utility, however, is in the range that a yarn somewhat resembling spun staple is obtained in of 0.1 to 5 denier per filament The novel filaments can which the cruciform-like filaments of polyamide in crossbe used to obtain all manner of new and novel effects section have short lengths of polyester microfibers atin fabric handle, scroop, appearance and covering power tached to a surface which pro ect beyond the original pe- Y P p 561660139 0f the P y COmPOSIfiOH and riphery of the filaments. mentary cross-section.

The invention is to be limited only by the scope of the Example VI following claims.

I claim:

Solutions of polyacrylonitrile and cellulose acetate 1. A method of making sharp-edged filaments which both in dimethylformamide are dry spun from the spincomprises spinning a composite filament of substantially neret of Example I. The resulting filaments in cross-section uniform cross-section composed of segments of at least have alternate segments of the two polymers with a crentwo dissimilar synthetic polymeric compositions, said ulated periphery. An acetate bath dissolves the cellulose 7 cross-section having at least two segments of at least one aid polymers, any contact between such'segments of References Cited same polymer being substantially point contact and UNITED STATES PATENTS rating a sharp-edged filament therefrom. The process of claim 1 wherein said separation is :532 JmPhShCd by 5 2,815,532 12/1957 Braunlich 18--8 The process of claim 1 wherern said separa'uon 18 omplished by dissolution of all segments composed FOREIGN PATENTS 211,133 11/1957 Australia.

Jne polymeric composition. 1. The process of claim 1 wherein said separation is acnplished by chemical degradation of all segments com- 10 ALEXANDER MERKEL, Primar Examiner. sed of one polymer composition. H. W. LUCKOWER, I. H. WOO, Assistant Examiners,

Claims (1)

1. A METHOD OF MAKING SHARP-EDGED FILAMENTS WHICH COMPRISES SPINNING A COMPOSITE FILAMENT OF SUBSTANTIALLY UNIFORM CROSS-SECTION COMPOSED OF SEGMENTS OF AT LEAST TWO DISSIMILAR SYNTHETIC POLYMERIC COMPOSITIONS, SAID CROSS-SECTION HAVING AT LEAST TWO SEGMENTS OF AT LEAST ONE OF SAID POLYMERS, ANY CONTACT BETWEEN SUCH SEGMENTS OF THE SAME POLYMER BEING SUBSTANTIALLY POINT CONTACT AND SEPARATING A SHARP-EDGED FILAMENT THEREFROM.

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