CA2264180C - Lyocell fibers and process for their preparation - Google Patents
Lyocell fibers and process for their preparation Download PDFInfo
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- CA2264180C CA2264180C CA002264180A CA2264180A CA2264180C CA 2264180 C CA2264180 C CA 2264180C CA 002264180 A CA002264180 A CA 002264180A CA 2264180 A CA2264180 A CA 2264180A CA 2264180 C CA2264180 C CA 2264180C
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- D—TEXTILES; PAPER
- D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
- D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
- D04H1/00—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres
- D04H1/40—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties
- D04H1/54—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties by welding together the fibres, e.g. by partially melting or dissolving
- D04H1/56—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties by welding together the fibres, e.g. by partially melting or dissolving in association with fibre formation, e.g. immediately following extrusion of staple fibres
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- D—TEXTILES; PAPER
- D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
- D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
- D01F2/00—Monocomponent artificial filaments or the like of cellulose or cellulose derivatives; Manufacture thereof
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- D—TEXTILES; PAPER
- D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
- D01D—MECHANICAL METHODS OR APPARATUS IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS
- D01D5/00—Formation of filaments, threads, or the like
- D01D5/08—Melt spinning methods
- D01D5/098—Melt spinning methods with simultaneous stretching
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- D—TEXTILES; PAPER
- D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
- D01D—MECHANICAL METHODS OR APPARATUS IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS
- D01D5/00—Formation of filaments, threads, or the like
- D01D5/12—Stretch-spinning methods
- D01D5/14—Stretch-spinning methods with flowing liquid or gaseous stretching media, e.g. solution-blowing
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- D—TEXTILES; PAPER
- D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
- D01D—MECHANICAL METHODS OR APPARATUS IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS
- D01D5/00—Formation of filaments, threads, or the like
- D01D5/18—Formation of filaments, threads, or the like by means of rotating spinnerets
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- D—TEXTILES; PAPER
- D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
- D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
- D04H1/00—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres
- D04H1/40—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties
- D04H1/42—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties characterised by the use of certain kinds of fibres insofar as this use has no preponderant influence on the consolidation of the fleece
- D04H1/425—Cellulose series
- D04H1/4258—Regenerated cellulose series
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- D—TEXTILES; PAPER
- D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
- D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
- D04H1/00—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres
- D04H1/40—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties
- D04H1/42—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties characterised by the use of certain kinds of fibres insofar as this use has no preponderant influence on the consolidation of the fleece
- D04H1/4282—Addition polymers
- D04H1/4291—Olefin series
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- D—TEXTILES; PAPER
- D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
- D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
- D04H1/00—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres
- D04H1/40—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties
- D04H1/54—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties by welding together the fibres, e.g. by partially melting or dissolving
-
- D—TEXTILES; PAPER
- D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
- D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
- D04H3/00—Non-woven fabrics formed wholly or mainly of yarns or like filamentary material of substantial length
- D04H3/013—Regenerated cellulose series
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- D—TEXTILES; PAPER
- D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
- D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
- D04H3/00—Non-woven fabrics formed wholly or mainly of yarns or like filamentary material of substantial length
- D04H3/018—Non-woven fabrics formed wholly or mainly of yarns or like filamentary material of substantial length characterised by the shape
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- D—TEXTILES; PAPER
- D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
- D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
- D04H3/00—Non-woven fabrics formed wholly or mainly of yarns or like filamentary material of substantial length
- D04H3/02—Non-woven fabrics formed wholly or mainly of yarns or like filamentary material of substantial length characterised by the method of forming fleeces or layers, e.g. reorientation of yarns or filaments
- D04H3/03—Non-woven fabrics formed wholly or mainly of yarns or like filamentary material of substantial length characterised by the method of forming fleeces or layers, e.g. reorientation of yarns or filaments at random
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- D—TEXTILES; PAPER
- D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
- D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
- D04H3/00—Non-woven fabrics formed wholly or mainly of yarns or like filamentary material of substantial length
- D04H3/08—Non-woven fabrics formed wholly or mainly of yarns or like filamentary material of substantial length characterised by the method of strengthening or consolidating
- D04H3/16—Non-woven fabrics formed wholly or mainly of yarns or like filamentary material of substantial length characterised by the method of strengthening or consolidating with bonds between thermoplastic filaments produced in association with filament formation, e.g. immediately following extrusion
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- Engineering & Computer Science (AREA)
- Textile Engineering (AREA)
- Mechanical Engineering (AREA)
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Artificial Filaments (AREA)
- Spinning Methods And Devices For Manufacturing Artificial Fibers (AREA)
- Nonwoven Fabrics (AREA)
- Yarns And Mechanical Finishing Of Yarns Or Ropes (AREA)
- Chemical Or Physical Treatment Of Fibers (AREA)
- Treatments For Attaching Organic Compounds To Fibrous Goods (AREA)
Abstract
The invention is lyocell fiber characterized by a pebbled surface as seen at high magnification and having a variable cross section and diameter along and between fibers. The fiber is produced by centrifugal spinning, melt blowing or its spunbonding variation. The fibers can be made in the microdenier range with average weights as low as one denier or less. The fibers have inherently low gloss and can be formed into tight yarns for making fabrics of very soft hand. Alternatively, the fibers can be formed into selfbonded nonwoven fabrics.
Description
CA 02264180 1999-02-22W0 98l079ll PCT/US97/14762LYOCELL FIBERS AND PROCESSFOR THEIR PREPARATIONThis application claims priority from Provisional Applications Serial Nos.5 60/023,909 and 60/024,462, both ï¬led August 23, 1996.l01520253035The present invention is directed to lyocell ï¬bers having novel characteris-tics and to the method for their preparation. It is also directed to yarns produced fromthe ï¬bers, and to woven and nonwoven fabrics containing the ï¬bers. In particular, themethod involves ï¬rst dissolving cellulose in an amine oxide to form a dope. Latent ï¬-bers are then produced either by extrusion of the dope through small apertures into anair stream which draws the latent ï¬laments of cellulose solution or by centriï¬igally ex-pelling the dope through small apertures. The ï¬bers are then formed by regenerating thespun latent ï¬bers in a liquid nonsolvent. Either process is amenable to the production ofself bonded nonwoven fabrics.BACKGROUND OF THE INVENTIONFor over a century strong ï¬bers of regenerated cellulose have been pro-duced by the viscose and cuprammonium processes. The latter process was ï¬rst pat-ented in 1890 and the viscose process two years later. In the viscose process cellulose isï¬rst steeped in a mercerizing strength caustic soda solution to form an alkali cellulose.This is reacted with carbon disulï¬de to form cellulose xanthate which is then dissolvedin dilute caustic soda solution. After ï¬ltration and deaeration the xanthate solution isextruded from submerged spinnerets into a regenerating bath of sulfuric acid, sodiumsulfate, zinc sulfate, and glucose to form continuous ï¬laments. The resulting so-calledviscose rayon is presently used in textiles and was formerly widely used as reinforcing inrubber articles such as tires and drive belts.Cellulose is also soluble in a solution of ammoniacal copper oxide. Thisproperty formed the basis for production of cuprammonium rayon. The cellulose solu-tion is forced through submerged spinnerets into a solution of 5% caustic soda or dilutesulfuric acid to form the ï¬bers. Aï¬er decoppering and washing the resulting ï¬bers havegreat wet strength. Cuprammonium rayon is available in ï¬bers of very low deniers andis used almost exclusively in textiles.More recently other cellulose solvents have been explored. One such sol-vent is based on a solution of nitrogen tetroxide in dimethyl formamide. While much re-search was done, no commercial process has resulted for forming regenerated celluloseï¬bers using this solvent.W0 98/0791 1101520253035CA 02264180 1999-02-22PCT/US97/14762-2-The useï¬ilness of tertiary amineâN oxides as cellulose solvents has beenknown for a considerable time. Graenacher, in U.S. Patent No. 2,179,181, discloses agroup of amine oxide materials suitableâ as solvents. However, the inventor was onlyable to fonn solutions with low concentrations of cellulose and solvent recovery pre-sented a major problem. Johnson, in U.S. Patent No. 3,447,939, describes the use ofanhydrous N-methylmorpholine-N-oxide (NMMO) and other amine N-oxides as sol-vents for cellulose and many other natural and synthetic polymers. Again the solutionswere of relatively low solids content. In his later U.S. Patent No. 3,508,941, Johnsonproposed mixing in solution a wide variety of natural and synthetic polymers to form in-timate blends with cellulose. A nonsolvent for cellulose such as dimethylsulfoxide wasadded to reduce dope viscosity. The polymer solution was spun directly into coldmethanol but the resulting ï¬laments were of relatively low strength.However, beginning in 1979 a series of patents were issued to preparationof regenerated cellulose ï¬bers using various amine oxides as solvents. In particular, N-methylmorpholine~N-oxide with about 12% water present proved to be a particularlyuseï¬il solvent. The cellulose was dissolved in the solvent under heated conditions, usu-ally in the range of 90°C to 130°C, and extruded from a multiplicity of ï¬ne aperturedspinnerets into air. The ï¬laments of cellulose dope are continuously mechanically drawnin air by a factor in the range of about three to ten times to cause molecular orientation.They are then led into a nonsolvent, usually water, to regenerate the cellulose. Otherregeneration solvents, such as lower aliphatic alcohols, have also been suggested. Ex-amples of the process are detailed in McCorsley and McCorsley et al. U.S. Patents Nos.4,142,913; 4,144,080; 4,211,574, 4,246,221, and 4,416,698 and others. Jurkovic et al.,in U.S. Patent No 5,252,284 and Michels et al,, in U.S. Patent 5,417,909 deal especiallywith the geometry of extrusion nozzles for spinning cellulose dissolved in NMMO.Brandner et al, in U.S. Patent 4,426,228, is exemplary of a considerable number of pat-ents that disclose the use of various compounds to act as stabilizers in order to preventcellulose and/or solvent degradation in the heated NMMO solution. Franks et al., inU.S. Patent Nos. 4,145,532 and 4,196,282, deal with the difï¬culties of dissolving cellu-lose in amine oxide solvents and of achieving higher concentrations of cellulose.Cellulose textile ï¬bers spun from NMMO solution are referred to aslyocell ï¬bers. Lyocell is an accepted generic term for a ï¬ber composed of cellulose pre-cipitated from an organic solution in which no substitution of hydroxyl groups takesplace and no chemical intermediates are fonned. One lyocell product produced byCourtaulds, Ltd. is presently commercially available as Tencelâ ï¬ber. These ï¬bers areavailable in 0.9-2.7 denier weights and heavier. Denier is the weight in grams of 9000meters of a ï¬ber. Because of their ï¬neness, yarns made from them produce fabrics hav-ing extremely pleasing hands.W0 98/07911l0I520253035CA 02264180 1999-02-22PCT/US97/14762-3-One limitation of the lyocell ï¬bers made presently is a function of their ge-ometry. They are continuously formed and typically have quite uniform, generally circu-lar or oval cross sections, lack crimp as spun, and have relatively smooth, glossysurfaces. This makes them less than ideal as staple ï¬bers since it is difficult to achieveuniform separation in the carding process and can result in non-uniform blending and un-even yarn. In part to correct the problem of straight ï¬bers, man made staple ï¬bers arealmost always crimped in a secondary process prior to being chopped to length. Exam-ples of crimping can be seen in U.S. Patent Nos. 5,591,388 or 5,601,765 to Sellars et al.where the ï¬ber tow is compressed in a stuifer box and heated with dry steam. It mightalso be noted that ï¬bers having a continuously uniform cross section and glossy surfaceproduce yarns tending to have a "plastic" appearance. Yarns made from thermoplasticpolymers frequently must have delustering agents, such as titanium dioxide, added priorto spinning. Vlfrlkes et al., in U.S. Patent 5,458,835, teach the manufacture of viscoserayon ï¬bers having cruciform and other cross sections. U.S. Patent No. 5,417,909 toMichels et al. discloses the use of proï¬led spinnerets to produce lyocell ï¬bers havingnon-circular cross sections but the present inventors are not aware of any commercialuse of this method.Kaneko et al. in U.S. Patent 3,833,438 teach preparation of self bondedcellulose nonwoven materials made by the cuprammonium rayon process. Self bondedlyocell nonwoven webs have not been described to the best of the present inventorsâknowledge.Low denier ï¬bers ï¬om synthetic polymers have been produced by a num-ber of extrusion processes. Three of these are relevant to the present invention. One isgenerally termed "melt blowing". The molten polymers are extruded through a series ofsmall diameter oriï¬ces into an air stream ï¬owing generally parallel to the extruded ï¬-bers. This draws or stretches the ï¬bers as they cool. The stretching serves two pur-poses. It causes some degree of longitudinal molecular orientation and reduces theultimate ï¬ber diameter. A somewhat similar process is called "spunbonding" where thefiber is extruded into a tube and stretched by an air flow through the tube caused by avacuum at the distal end. In general, spunbonded ï¬bers are continuous while meltblown ï¬bers are more usually in discrete shorter lengths. The other process, termed"centriï¬igal spinning", differs in that the molten polymer is expelled from apertures inthe sidewalls of a rapidly spinning drum. The ï¬bers are drawn somewhat by air resis-tance as the drum rotates. However, there is not usually a strong air stream present asin meltblowing. All three processes may be used to make nonwoven fabric materials.There is an extensive patent and general technical literature on the processes since theyhave been commercially important for many years. Exemplary patents to meltblowingare Weber et al., U.S. Patent No. 3,959,421, and Milligan et al., U.S. Patent No.W0 98I0791ll01520253035CA 02264180 1999-02-22PCT/US97/14762-4-5,075,068. The Weber et al. patent uses a water spray in the gas stream to rapidly coolthe ï¬bers. A somewhat related process is described in PCT Publication W0 91/ 18682which is directed to a method for coating paper by modiï¬ed meltblowing. Coating ma-terials suggested are aqueous liquids such as "an aqueous solution of starch, carboxy-methylcellulose, polyvinyl alcohol, latex, a suspension of bacterial cellulose, or anyaqueous material, solution or emulsion". However, this process actually atornizes theextruded material rather than forms it into latent ï¬bers. Zikeli et al., in U.S. PatentNos. 5,589,125 and 5,607,639, direct a stream of air transversely across strands of ex-truded lyocell dope as they leave the spinnerets. This air stream serves only to cool anddoes not act to stretch the ï¬laments.Centriï¬igal spinning is exempliï¬ed in U.S. Patents Nos. 5,242,633 and5,326,241 to Rook et al. Olcada et al., in U.S. Patent No. 4,440,700 describe a centriï¬.r-gal spinning process for thermoplastic materials. As the material is ejected the ï¬bers arecaught on an annular form surrounding the spinning head and moved downward by acurtain of ï¬owing cooling liquid. Included among the list of polymers suited to theprocess are polyvinyl alcohol and polyacrylonitrile. In the case of these two materialsthey are spun "wet"; i.e., in solution, and a "coagulation bath" is substituted for the cur-tain of cooling liquid.Vlfrth the exception of the Kaneko et al. patent noted above, processesanalogous to melt blowing, spunbonding and centriï¬igal spinning have never been usedwith cellulosic materials since cellulose itself is basically infusible.Extremely ï¬ne ï¬bers, termed "microdenier ï¬bers" generally are regardedas those having a denier of 1.0 or less. Meltblown ï¬bers produced from various syn-thetic polymers, such as polypropylene, nylons, or polyesters are available with diame-ters as low as 0.4 pm (approximately 0.001 denier). However, the strength or"tenacity" of most of these ï¬bers tends to be low and their generally poor water absorb-ency is a negative factor when they are used in fabrics for clothing. Microdenier cellu-lose ï¬bers, as low as 0.5 denier, have been produced before the present only by theviscose process.The present process produces a new lyocell ï¬ber that overcomes many ofthe limitations of the ï¬bers produced from synthetic polymers, rayons, and the presentlyavailable lyocell ï¬bers. It allows formation of ï¬bers of low denier and with a distribu-tion of deniers. At the same time each ï¬ber has a pebbled surface, a cross section ofvarying shape and diameter along its length, and signiï¬cant natural crimp. All of theseare desirable characteristics that are found in most natural ï¬bers but are missing inlyocell ï¬bers produced commercially to the present.W0 98/0791 1l015202535CA 02264180 1999-02-22PCT/US97/14762-5-SUMMARY OF THE INVENTIONThe present invention is directed to a process for production of regener-ated cellulose ï¬bers and webs and to the ï¬bers and webs so produced. The terms "cel-lulose" and "regenerated cellulose" as used here should be construed suï¬iciently broadlyto encompass blends of cellulose with other natural and synthetic polymers, mutuallysoluble in a spinning solvent, in which cellulose is the principal component by weight. Inparticular it is directed to low denier ï¬bers produced ï¬'om cellulose solutions in amineN-oxides by processes analogous to melt blowing or centriï¬igal spinning. Where theterms "melt blowing", "Spunbonding", and "centrifugal spinning" are used it will be un-derstood that these refer to processes that are similar or analogous to the processes usedfor production of thermoplastic ï¬bers, even though the cellulose is in solution and thespinning temperature is only moderately elevated. The term "continuously drawn" refersto the present commercial process for manufacture of lyocell ï¬bers where they are me-chanically pulled, ï¬rst through an air gap to cause elongation and molecular orientationthen through the regeneration bath.The processes involve dissolving a cellulosic raw material in an amine ox-ide, preferably N-methylmorpholine-N-oxide (NMMO) with some water present. Thisdope, or cellulose solution in NMMO, can be made by known technology; e.g., as is dis-cussed in any of the McCorsley or Franks et al. patents aforenoted. In the present proc-ess, the dope is then transferred at somewhat elevated temperature to the spinningapparatus by a pump or extruder at about 90°C to 130°C. Ultimately the dope is di-rected through a multiplicity of small oriï¬ces into air. In the case of melt blowing, the -extruded threads of cellulose dope are picked up by a turbulent gas stream ï¬owing in agenerally parallel direction to the path of the ï¬laments. As the cellulose solution isejected through the oriï¬ces the liquid strands or latent ï¬laments are drawn (or signiï¬-cantly decreased in diameter and increased in length) during their continued trajectoryafter leaving the oriï¬ces. The turbulence induces a natural crimp and some variability inultimate ï¬ber diameter both between ï¬bers and along the length of individual ï¬bers.This is in marked contrast to continuously drawn ï¬bers where diameters are uniform andcrimp is lacking or must be introduced as a post spinning process. The crimp is irregularand will have a peak to peak amplitude greater than about one ï¬ber diameter and a pe-riod greater than about five ï¬ber diameters.Spunbonding can be regarded as a species of meltblowing in that the ï¬bersare picked up and drawn in an airstream without being mechanically pulled. In the con-text of the present invention meltblowing and spunbonding should be regarded as ï¬]IâlC-tional equivalents.Where the ï¬bers are produced by centriï¬igal spinning, the dope strandsare expelled through small oriï¬ces into air and are drawn by the inertia imparted by theW0 98l07911101520253035CA 02264180 1999-02-22PCT/US97/14762-6-spinning head. The ï¬laments are then directed into a regenerating solution or a regener-ating solution is sprayed onto the ï¬laments. Regenerating solutions are nonsolventssuch as water, lower aliphatic alcohols, or mixtures of these. The NMMO used as thesolvent can then be recovered from the regenerating bath for reuse.Turbulence and oscillation in the air around the latent ï¬ber strands is be-lieved to be responsible for their unique geometry when made either by the melt blowingor centrifugal spinning process.Filaments having an average size as low as 0.1 denier or even less can bereadily formed. Denier can be controlled by a number of factors including but not lim-ited to oriï¬ce diameter, gas stream speed, spinning head speed, and dope viscosity.Dope viscosity is, in turn, largely a factor of cellulose D.P. and concentration. Fiberlength can be similarly controlled by design and velocity of the air stream surroundingthe extrusion oriï¬ces. Continuous ï¬bers or relatively short staple ï¬bers can be produceddepending on spinning conditions. Equipment can be readily modiï¬ed to form individualï¬bers or to lay them into a mat of nonwoven cellulosic fabric. In the latter case the matmay be formed and become self bonded prior to regeneration of the cellulose. The ï¬-bers are then recovered from the regenerating medium, further washed, bleached if nec-essary, dried, and handled conventionally from that point in the process.Gloss or luster of the ï¬bers is considerably lower than continuously drawnlyocell ï¬ber lacking a delusterant so they do not have a "plastic" appearance. This is be-lieved to be due to their unique "pebbled" surface apparent in high magniï¬cationmicrographs.By properly controlling spinning conditions the ï¬bers can be formed withvariable cross sectional shape and a relatively narrow distribution of ï¬ber diameters.Some variation in diameter and cross sectional conï¬guration will typically occur alongthe length of individual ï¬bers and between ï¬bers. The ï¬bers are unique for regeneratedcellulose and similar in morphology to many natural ï¬bers.Fibers produced by either the melt blowing or centrifugal spinning proc-esses possess a natural crimp quite unlike that imparted by a stuffer box. Crimp im-parted by a stuffer box is relatively regular, has a relatively low amplitude usually lessthan one ï¬ber diameter, and short peak-to-peak period normally not more than two orthree ï¬ber diameters. That of the present ï¬bers has an irregular amplitude greater thanone ï¬ber diameter, usually much greater, and an irregular period exceeding about ï¬veï¬ber diameters, a characteristic of ï¬bers having a curly or wavy appearance.Properties of the ï¬bers of the present invention are well matched for card-ing and spinning in conventional textile manufacturing processes. The ï¬bers, while hav-ing many of the attributes of natural ï¬bers, can be produced in microdenier diametersW0 98/0791!l0l520253035CA 02264180 1999-02-22PCT/US97/14762-7-unavailable in nature. It is possible to directly produce self bonded webs or tightlywound multi-ply yams.A particular advantage of the present invention is the ability to form blendsof cellulose with what might otherwise be considered as incompatible polymeric materi-als. The amine oxides are extremely powerï¬il solvents and can dissolve many otherpolymers beside cellulose. It is thus possible to form blends of cellulose with materialssuch as lignin, nylons, polyethylene oxides, polypropylene oxides, poly(acrylonitrile),poly(vinylpyrrolidone), poly(acrylic acid), starches, poly(vinyl alcohol), polyesters,polyketones, casein, cellulose acetate, amylose, amylopectins, cationic starches, andmany others. Each of these materials in homogeneous blends with cellulose can produceï¬bers having new and unique properties.It is an object of the present invention to provide a method of forming lowdenier regenerated cellulose ï¬bers or cellulose blend ï¬bers from solution in an amineoxideâwater medium by processes analogous to melt blowing, spunbonding, or centriï¬1-gal spinning. _It is a ï¬irther object to provide low denier cellulose ï¬bers having advanta-geous geometry and surface characteristics for forming into yarns.It is still an object to provide ï¬bers having natural crimp and low luster.It is also an object to provide regenerated cellulose ï¬bers having manyproperties similar or superior to natural ï¬bers.It is yet an object to provide a method of forming ï¬bers of the above typesby a process in which all production chemicals can be readily recovered and reused.It is another object to provide self bonded nonwoven lyocell fabrics.These and many other objects will become readily apparent to those skilledin the art upon reading the following detailed description in conjunction with referral tothe drawings.BRIEF DESCRIPTION OF THE DRAWINGSFIG. 1 is a block diagram of the steps used in practice of the presentprocess.FIG. 2 is a partially cut away perspective representation of typical centriï¬1-gal spinning equipment used with the invention.FIGS. 3 is a partially cut away perspective representation of melt blowingequipment adapted for use with the present invention.FIG. 4 is a cross sectional view of a typical extrusion head that might beused with the above melt blowing apparatus.FIGS. 5 and 6 are scanning electron micrographs of a commercially avail-able lyocell ï¬ber at IOOX and l0,000x magniï¬cation respectively.WO 98/0791 1101520253035CA 02264180 1999-02-22PCT/US97/14762-3-FIGS. 7 and 8 are scanning electron micrographs of a lyocell ï¬ber pro-duced by centriï¬igal spinning at ZOOX and l0,000x magniï¬cation respectively.FIGS. 9 and 10 are scanning electron micrographs at 2,000X showingcross sections along a single centriï¬igally spun ï¬ber .FIGS. 11 and l2 are scanning electron micrographs of a melt blown lyocellï¬ber at IOOX and l0,000x magniï¬cation respectively.FIG. 13 is a drawing illustrating production of a self bonded nonwovenlyocell fabric using a melt blowing process.FIG. 14 is a similar drawing illustrating production of a self bonded non-woven lyocell fabric using a centriï¬igal spinning process.DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTSThe type of cellulosic raw material used with the present invention is notcritical. It may be bleached or unbleached wood pulp which can be made by variousprocesses of which kraft, prehydrolyzed kraï¬, or sulï¬te would be exemplary. Manyother cellulosic raw materials, such as puriï¬ed cotton linters, are equally suitable. Priorto dissolving in the amine oxide solvent the cellulose, if sheeted, is normally shreddedinto a ï¬ne ï¬uif to promote ready solution.The solution of the cellulose can be made in a known manner; e.g., astaught in McCorsley U.S. Patent No. 4,246,221. Here the cellulose is wet in a non-solvent mixture of about 40% NMMO and 60% water.NMMO is about 125.1 by weight. The mixture is mixed in a double arm sigma blademixer for about 1.3 hours under vacuum at about 120°C until suï¬icient water has beendistilled off to leave about 12-14% based on NMMO so that a cellulose solution isAlternatively,The ratio of cellulose to wetformed. The resulting dope contains approximately 30% cellulose.NMMO of appropriate water content may be used initially to obviate the need for thevacuum distillation. This is a convenient way to prepare spinning dopes in the labora-tory where commercially available NMMO of about 40-60% concentration can be mixedwith laboratory reagent NMMO having only about 3% water to produce a cellulose sol-vent having 7-15% water. Moisture normally present in the cellulose should be ac-counted for in adjusting necessary water present in the solvent. Reference might bemade to articles by Chanzy, H. and A. Peguy, Journal of Polymer Science, PolymerPhysics Ed. 18: l137-1144 (1980) and Navard, P. and J. M. Haudin British PolymerJournal, p 174, Dec. 1980 for laboratory preparation of cellulose dopes in NMMO-water solvents.Reference to FIG. 1 will show a block diagram of the present process. Aswas noted, preparation of the cellulose dopes in aqueous NMMO is conventional. Whatis not conventional is the way these dopes are spun. The cellulose solution is forcedW0 98/0791 1101520253035CA 02264180 1999-02-22PCT/US97/14762-9-from extrusion oriï¬ces into a turbulent air stream rather than directly into a regenerationbath as is the case with viscose or cuprammonium rayon. Only later are the latent ï¬la-ments regenerated. However, the present process also differs from the conventionalprocesses for forming lyocell ï¬bers since the dope is not continuously drawn linearlydownward as unbroken threads through an air gap and into the regenerating bath.FIG. 2 is illustrative of a centtiï¬igal spinning process. The heated cellu-lose dope 1 is directed into a heated generally hollow cylinder or drum 2 with a closedbase and a multiplicity of small apertures 4 in the sidewalls 6. As the cylinder rotates,dope is forced out horizontally through the apertures as thin strands 8. As these strandsmeet resistance from the surrounding air they are drawn or stretched by a large factor.The amount of stretch will depend on readily controllable factors such as cylinder rota-tional speed, oriï¬ce size, and dope viscosity. The dope strands either fall by gravity orare gently forced downward by an air ï¬ow into a nonâsolvent 10 held in a basin 12where they are coagulated into individual oriented ï¬bers having lengths from about 1 to25 cm. Alternatively, the dope strands 8 can be either partially or completely regener-ated by a water spray from a ringof spray nozzles 16 fed by a source of regenerating so-lution 18. Also, as will be described later, they can be formed into a nonwoven fabricprior to or during regeneration. Water is the preferred coagulating nonâsolvent althoughethanol or water-ethanol mixtures are also useful. From this point the ï¬bers are col-lected and may be washed to remove any residual NMMO, bleached as might be neces-sary, and dried. Example 2 that will follow gives speciï¬c details of laboratorycentriï¬igally spun ï¬ber preparation. 0FIGS. 3 and 4 show details of a typical melt blowing process. As seen inFIG. 3, a supply of dope, not shown, is directed to an extruder 32 which forces the cel-lulose solution to an oriï¬ce head 34 having a multiplicity of oriï¬ces 36. Air or anothergas is supplied through lines 38 and surrounds and transports extruded solution strands40. A bath or tank 42 contains a regenerating solution 44 in which the strands are re-generated from solution in the solvent to cellulose ï¬bers. Alternatively, the latent ï¬berscan be showered with a water spray to regenerate or partially regenerate them. Theamount of draw or stretch will depend on readily controllable factors such as oriï¬cesize, dope viscosity, cellulose concentration in the dope, and air speed and nozzleconï¬guration.FIG. 4 shows a typical extrusion oriï¬ce. The oriï¬ce plate 20 is bored witha multiplicity of oriï¬ces 36. It is held to the body of the extrusion head 22 by a series ofcap screws 18. An internal member 24 forms the extrusion ports 26 for the cellulose so-lution. It is embraced by air passages 28 that surround the extruded solution ï¬laments40 causing them to be drawn and to assist in their transport to the regenerating medium.WO 98107911101520253035CA 02264180 1999-02-22PCT/US97/14762-10-Example 3 that follows will give speciï¬c details of laboratory scale ï¬ber preparation bymelt blowing.The scanning electron micrographs shown in FIGS. 5-6 are of lyocell ï¬-bers made by the conventional continuously drawn process. It is noteworthy that theseare of quite uniform diameter and are essentially straight. The surface seen at l0,000Xmagniï¬cation in FIG. 6 is remarkably smooth.FIGS. 7-10 are of ï¬bers made by a centrifugal spinning process of the pre-sent invention. The ï¬bers seen in FIG. 7 have a range of diameters and tend to be some-what curly giving them a natural crimp. This natural crimp is quite unlike the regularsinuous conï¬guration obtained in a stuffer box. Both amplitude and period are irregularand are at least several ï¬ber diameters in height and length. Most of the ï¬bers are some-what ï¬attened and some show a signiï¬cant amount of twist. Fiber diameter varies be-tween extremes of about 1.5 pm and 20 pm (<0.l - 3.1 denier), with most of the ï¬bersclosely grouped around a 12 um diameter average (Q. l denier).FIG. 8 shows the ï¬bers of FIG. 7 at l0,000x magniï¬cation. The surface isuniformly pebbly in appearance, quite unlike the commercially available ï¬bers. This re-sults in lower gloss and improved spinning characteristics.FIGS. 9 and 10 are scanning micrographs of ï¬ber cross sections takenabout 5 mm apart on a single centrifugally spun ï¬ber. The variation in cross section anddiameter along the ï¬ber is dramatically shown. This variation is characteristic of boththe centriï¬igally spun and melt blown ï¬ber. _FIGS. 1] and 12 are low and high magniï¬cation scanning micrographs ofmelt blown ï¬ber. Fiber diameter, while still variable, is less so than the centriï¬igallyspun ï¬ber. However, crimp of these samples is signiï¬cantly greater. The micrograph atl0,000X of FIG. 12 shows a pebbly surface remarkably like that of the centrifugallyspun ï¬ber.The overall morphology of ï¬bers from both processes is highly advanta-geous for forming ï¬ne tight yarns since many of the features resemble those of naturalï¬bers. This is believed to be unique for the lyocell ï¬bers of the present invention.FIG. 13 shows one method for making a self bonded lyocell nonwovenmaterial using a modiï¬ed melt blowing process. A cellulose dope 50 is fed to extruder52 and ï¬'om there to the extrusion head 54. An air supply 56 acts at the extrusion ori-ï¬ces to draw the dope strands 58 as they descend from the extrusion head. Process pa-rameters are preferably chosen so that the resulting ï¬bers will be continuous rather thanrandom shorter lengths. The ï¬bers fall onto an endless moving forarninous belt 60 sup-ported and driven by rollers 62, 64. Here they form a latent nonwoven fabric mat 66. Atop roller, not shown, may be used to press the ï¬bers into tight contact and ensurebonding at the crossover points. As mat 66 proceeds along its path while still supportedW0 98/0791 11015202530CA 02264180 1999-02-22I 1 PCT/US97/14762on belt 60, a spray of regenerating solution 68 is directed downward by sprayers 70.The regenerated product 72 is then removed from the end of the belt where it may beï¬irther processed; e. g., by further washing, bleaching, and drying.FIG 14 is an alternative process for forming a self bonded nonwoven webusing centrifugal spinning. A cellulose dope 80 is fed into a rapidly rotating drum 82having a multiplicity of oriï¬ces 84 in the sidewalls. Latent ï¬bers 86 are expelledthrough oriï¬ces 84 and drawn, or lenghtened, by air resistance and the inertia impartedby the rotating drum. They impinge on the inner sidewalls of a receiver surface 88 con-centtically located around the drum. The receiver may optionally have a frustroconicallower portion 90. A curtain or spray of regenerating solution 92 ï¬ows downward fromring 94 around the walls of receiver 88 to partially coagulate the cellulose mat impingedon the sidewalls of the receiver. Ring 94 may be located as shown or moved to a lowerposition if more time is needed for the latent ï¬bers to self bond into a nonwoven web.The partially coagulated nonwoven web 96 is continuously mechanically pulled from thelower part 90 of the receiver into a coagulating bath 98 in container 100. As the webmoves along its path it is collapsed from a cylindrical conï¬guration into a planar two plynonwoven structure. The web is held within the bath as it moves under rollers 102, 104.A takeout roller 106 removes the now fully coagulated two ply web 108 from the bath.Any or all of rollers 100, 102, or 104 may be driven. The web 108 is then continuouslydirected into a wash and/or bleaching operation, not shown, following which it is dried.for storage. It may be split and opened into a single ply nonwoven or maintained as atwo ply material as desired.Example 1Cellulose Dope PreparationThe cellulose pulp used in this and the following examples was a standardbleached kraft southern soï¬wood market pulp, Grade NB 416, available from Weyer-haeuser Company, New Bern, North Carolina. It has an alpha cellulose content of about88-89% and a D.P. of about 1200. Prior to use, the sheeted wood pulp was run througha ï¬uï¬er to break it down into essentially individual ï¬bers and small ï¬ber clumps. Into a250 mL three necked glass ï¬ask was charged 5.3 g of ï¬uffed cellulose, 66.2 g of 97%NMMO, 24.5 g of 50% NMMO, and 0.05 g propyl gallate. The ï¬ask was immersed inan oil bath at 120°C, a stirrer inserted, and stirring continued for about 0.5 hr. A readilyï¬owable dope resulted that was directly suitable for spinning.W0 98/0791 1l01520253035CA 02264180 1999-02-22PCT/US97/ 14762-12-Example 2Fiber Preparation by Centriï¬igal SpinningThe spinning device used was a modiï¬ed "cotton candy" type, similar tothat shown in U.S. Patent No. 5,447,423 to Fuisz et al. The rotor, preheated to 120°Cwas 89 mm in diameter and revolved at 2800 rpm. The number of oriï¬ces could bevaried between 1 and 84 by blocking olf oriï¬ces. Eight oriï¬ces 700 pm in diameterwere used for the following trial. Cellulose dope, also at 120°C, was poured onto thecenter of the spinning rotor. The thin strands of dope that emerged were allowed to fallby gravity into room temperature water contained in the basin surrounding the rotor.Here they were regenerated. While occasional ï¬bers would bond to each other most re-mained individualized and were several centimeters in length.In addition to the process just described, very similar rnicrodenier ï¬berswere also successfully made from bleached and unbleached kraï¬ pulps, sulï¬te pulp, mi-crocrystalline cellulose, and blends of cellulose with up to 30% corn starch orpoly(acrylic acid).Diameter (or denier) of the ï¬bers could be reliably controlled by severalmeans. Higher dope viscosities tended to form heavier ï¬bers. Dope viscosity could, inturn, be controlled by means including cellulose solids content or degree of polymeriza-tion of the cellulose. Smaller spinning oriï¬ce size or higher drum rotational speed pro-duces smaller diameter ï¬bers. Fibers having diameters from about 5-20 pm (0.2-3.ldenier) were reproducibly made. Heavier ï¬bers in the 20-50 um diameter range(3.1-19.5 denier) could also be easily formed. Fiber length varies between about 0.5-25cm and depended considerably on the geometry and operational parameters of thesystem.Example 3Fiber Preparation by Melt BlowingThe dope as prepared in Example 1 was maintained at 120°C and fed to anapparatus originally developed for forming melt blown synthetic polymers. Overall ori-ï¬ce length was about 50 mm with a diameter of 635 pm which tapered to 400 pm at thedischarge end. Aï¬er a transit distance in air of about 20 cm in the turbulent air blast theï¬bers dropped into a water bath where they were regenerated. Regenerated ï¬ber lengthvaried. Some short ï¬bers were formed but most were several centimeters to tens ofcentimeters in length. Variation of extrusion parameters enabled continuous ï¬bers to beformed. Quite surprisingly, the cross section of many of the ï¬bers was not uniformalong the ï¬ber length. This feature is expected to be especially advantageous in spinningtight yams using the microdenier material of the invention since the ï¬bers more closelyresemble natural ï¬bers in overall morphology.W0 98/0791 11015202530CA 02264180 1999-02-22PCT/US97/14762-13-In a variation of the above process, the ï¬bers were allowed to impinge ona traveling stainless steel mesh belt before they were directed into the regeneration bath.A well bonded nonwoven mat was formed. _It will be understood that the lyocell nonwoven fabrics need not be selfbonded. They may be only partially self bonded or not self bonded at all. In these casesthey may be bonded by any of the well known methods including but not limited to by-droentangling, the use of adhesive binders such as starch or various polymer emulsionsor some combination of these methods.Example 4Use of Microcrystalline Cellulose Furnish to Prepare Melt Blown LyocellThe process of Example 1 was repeated using a microcrystalline ï¬lI'I'llSlâlrather than wood pulp in order to increase solids content of the dope. The product usedwas Avicel® Type PH-101 microcrystalline cellulose available from FMC Corp, New-ark, Delaware. Dopes were made using 15 g and 28.5 g of the microcrystalline cellulose(dry weight) with 66.2 g of 97% NMMO, 24.5 g of 50% NMMO and 0.05g propyl gal-late. The procedure was otherwise as described in Example 1. The resulting dopes con-tained respectively about 14% and 24% cellulose. These were meltblown as describedin Example 3. The resulting ï¬ber was morphologically essentially identical to that ofExamples 2 and 3.It will be understood that ï¬ber denier is dependent on many controllablefactors. Among these are solution solids content, solution pressure and temperature atthe extruder head, oriï¬ce diameter, air pressure, and other variables well known to thoseskilled in meltblowing and centrifugal spinning technology. Lyocell ï¬bers having an av-erage 0.5 denier or even lower may be consistently produced by either the melt blowingor centriï¬igal spinning processes. A 0.5 denier ï¬ber corresponds to an average diameter(estimated on the basis of equivalent circular cross sectional area) of about 7-8 pm.The ï¬bers of the present invention were studied by x-ray analysis to deter-mine degree of crystallinity and crystallite type. Comparisons were also made with someother cellulosic ï¬bers as shown in the following table. Data for the microdenier ï¬bersare taken from the centriï¬igally spun material of Example 2.CA 02264180 1999-02-22W0 93/07911 PCT/US97I 14762-14-Table ICrystalline Properties of Different Cellulose FibersMicrodenier Cellulose GenericFibers of Present Invention Lvocell Tencelâ CottonCrystallinity Index 67% 65% 70% 85%Crystallite Cellulose II Cellulose ll Cellulose II Cellulose ISome diï¬iculty was encountered in measuring tensile strength of the individual ï¬-bers so the numbers given in the following table for tenacity are estimates. Again, the5 microdenier ï¬bers of the present invention are compared with a number of other ï¬bers.Table 2Fiber Physical Property MeasurementsCentriï¬igallyEiber_s Cotton So. Pine Ravonlâ S_ill<_ Spun Lvocell TencelTypical Length, cm 4 0.5 40 >10â 5-25 VariableTypical Diam., um 20 40 l6 l0 5 I2Tenacity, g/d 2.5-3.0 â-- 0.7-3.2 2.8-5.2 2.1 4.5-5.0ââ Viscose processThe centruï¬igally spun lyocell with an average diameter of about 5 pm corre-10 sponds to ï¬bers of about 025 denier.The pebbled surface of the fibers of the present invention result in a desir-able lower gloss without the need for any internal delustering agents. While gloss orluster is a diï¬icult property to measure the following test will be exemplary of the differ-ences between a ï¬ber sample made by the method of Example 2 and a commerciall5 lyocell ï¬ber. Small wet formed handsheets were made from the respective ï¬bers andlight reï¬ectance was determined. Reï¬ectance of the Example 2 material was 5.4%while that of the commercial ï¬ber was 16.9%.The inventors have herein described the best present mode of practicingtheir invention. It will be evident to others skilled in the art that many variations that20 have not been exempliï¬ed should be included within the broad scope of the invention.
Claims (14)
1. Lyocell fibers characterized by variability in cross sectional diameter and cross sectional configuration along the fiber length and from fiber to fiber, and further characterized by a pebbled surface and a natural crimp
2. The lyocell fibers of claim 1 having a uniformly pebbled surface.
3. The lyocell fibers of claim 1 having an irregular crimp with an amplitude greater than about one fiber diameter and a period greater than about five fiber diameters.
4. Lyocell fibers produced by a centrifugal spinning process, the fibers being characterized by variability in cross sectional diameter and cross sectional configuration along the fiber length and from fiber to fiber, and further characterized by a pebbled surface and a natural crimp.
5. The lyocell fibers of claim 4 having a uniformly pebbled surface.
6. The lyocell fibers of claim 4 having an irregular crimp with an amplitude greater than about one fiber diameters and a period greater than about five fiber diameters.
7. Lyocell fibers produced by a melt blowing process, the fibers being characterized by variability in cross sectional diameter and cross sectional configuration along the fiber length and from fiber to fiber, and further characterized by a pebbled surface and a natural crimp.
8. The lyocell fibers of claim 7 having a uniformly pebbled surface.
9. The lyocell fibers of claim 7 having an irregular crimp with an amplitude greater than about one fiber diameters and a period greater than about five fiber diameters.
10. The lyocell fibers of claims 1, 4, or 7 in which the fiber comprises a mixture of diameters with at least a portion of said fibers being less than about 1 denier.
11. The lyocell fibers of claims 1, 4, or 7 comprising a mixture of cellulose with noncellulosic polymers.
12. A spun yarn comprising a multiplicity of the fibers of claims 1, 4, or 7.
13. The lyocell fibers of claims 1, 4, or 7 wherein the fibers are further characterized by reduced gloss compared with continuously drawn lyocell fibers lacking delusterants.
14. The lyocell fibers of claims 1, 4, or 7 wherein the fibers are further characterized as individualized and continuous.
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CA2641972A CA2641972C (en) | 1996-08-23 | 1997-08-22 | Lyocell fibers and process for their preparation |
CA002641970A CA2641970A1 (en) | 1996-08-23 | 1997-08-22 | Lyocell fibers and process for their preparation |
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PCT/US1997/014762 WO1998007911A1 (en) | 1996-08-23 | 1997-08-22 | Lyocell fibers and process for their preparation |
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CN1356413A (en) | 2002-07-03 |
CN1356414A (en) | 2002-07-03 |
KR20000068304A (en) | 2000-11-25 |
CA2264180A1 (en) | 1998-02-26 |
ES2185045T3 (en) | 2003-04-16 |
JP2007046223A (en) | 2007-02-22 |
EP0920548A1 (en) | 1999-06-09 |
JP2001501260A (en) | 2001-01-30 |
ATE225418T1 (en) | 2002-10-15 |
HK1023377A1 (en) | 2000-09-08 |
JP4134209B2 (en) | 2008-08-20 |
WO1998007911A1 (en) | 1998-02-26 |
JP4018152B2 (en) | 2007-12-05 |
DE69716092D1 (en) | 2002-11-07 |
CA2641970A1 (en) | 1998-02-26 |
EP0920548B1 (en) | 2002-10-02 |
CN1238015A (en) | 1999-12-08 |
CN1348023A (en) | 2002-05-08 |
CA2641972A1 (en) | 1998-02-26 |
CN1230579C (en) | 2005-12-07 |
CA2641972C (en) | 2012-11-13 |
CN1356412A (en) | 2002-07-03 |
DE69716092T2 (en) | 2003-01-30 |
KR100471549B1 (en) | 2005-03-07 |
CN1081684C (en) | 2002-03-27 |
BR9711352A (en) | 2000-01-18 |
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