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EP1287191B1 - Procede de fusion-soufflage a attenuation mecanique - Google Patents

Procede de fusion-soufflage a attenuation mecanique Download PDF

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Publication number
EP1287191B1
EP1287191B1 EP01927152A EP01927152A EP1287191B1 EP 1287191 B1 EP1287191 B1 EP 1287191B1 EP 01927152 A EP01927152 A EP 01927152A EP 01927152 A EP01927152 A EP 01927152A EP 1287191 B1 EP1287191 B1 EP 1287191B1
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EP
European Patent Office
Prior art keywords
filaments
dope
air
diameter
fibers
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EP01927152A
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German (de)
English (en)
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EP1287191A1 (fr
Inventor
Mengkui Luo
Vincent A. Roscelli
Senen Camarena
Amar N. Neogi
John S. Selby
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Weyerhaeuser Co
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Weyerhaeuser Co
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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
    • D01D5/0985—Melt spinning methods with simultaneous stretching by means of a flowing gas (e.g. melt-blowing)
    • 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
    • D01D5/16—Stretch-spinning methods using rollers, or like mechanical devices, e.g. snubbing pins
    • 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

Definitions

  • the present invention relates to a process for producing filaments employing a modified meltblown process and more particularly to a process for producing lyocell filaments employing a modified meltblown process that mechanically attenuates the filaments.
  • lyocell filaments known as a meltblown process
  • a fluid dope is extruded through a row of orifices to form a plurality of filaments while a stream of air or other gas stretches and attenuates the hot filaments.
  • the latent filaments are treated to precipitate the cellulose.
  • the filaments are collected as continuous filaments or discontinuous filaments.
  • Lyocell filaments produced by an existing meltblown process are characterized by variability in diameter along their length, variability in length and diameter from filament to filament, a surface that is not smooth and a naturally imparted crimp.
  • lyocell filaments made by a meltblown process exhibit fibrillation at desirably low levels.
  • a dry-jet wet process involves the extrusion of a fluid dope through a plurality of orifices to form continuous filaments in an air gap.
  • air in this gap is stagnant, but sometimes air is circulated in a direction transverse to the direction that the filaments are traveling in order to cool and toughen the filaments.
  • the formed continuous filaments are attenuated in the air gap by a mechanical tensioning device such as a winder.
  • a tensioning device has a surface speed that is greater than the speed at which the dope emerges from the orifices. This speed differential causes the filaments to be mechanically stretched resulting in a reduction in the diameter of the filaments and the strengthening thereof.
  • the filaments are then taken up by a conveyer or other take up device after they have been treated with a non-solvent to precipitate the cellulose and form continuous filaments. These filaments can be gathered into a tow for transport and washing. Staple fibers can be made by cutting a tow of the filaments. Alternatively, the continuous filaments can be twisted to form a filament yarn.
  • Lyocell filaments formed by a dry-jet wet process are characterized by a smooth surface and little variability in cross-sectional diameter along a filament length. In addition, diameter variability between dry-jet wet filaments is low. Further, lyocell filaments from the dry-jet wet process have little if any crimp, unless the filaments are post-treated to impart such crimp. It is believed that the susceptibility of lyocell filaments made by a dry-jet wet process to fibrillate is greater than the susceptibility of fibers made by known meltblown processes to fibrillate.
  • lycell filaments made by a dry-jet wet process or lyocell fibers made from such filaments may be preferred for applications where low natural crimp, smooth surfaces, low variability in cross sectional diameter along a fiber and low variability in diameter from fiber to fiber are desirable, they still may be more susceptible to fibrillation compared to lyocell fibers made using known meltblown processes.
  • WO 99/47733 discloses a process for forming lyocell fibers comprising forming a dope from cellulose which is extruded through a series of small diameter orifices into a high velocity airstream plane generally parallel to the extruded fibers. Thus the fibers are stretched as they cool. The stretching causes some degree of longitudinal molecular orientation and reduces the ultimate fiber diameter. The stretched fibers are picked up by a rotating pick up roll on to which they are accumulated. This rotating pick up roll causes an external force to the filaments in a direction parallel to the length of the filaments.
  • US-A-4,416,698 refers to the preparation of a lyocell fiber in which cellulose is dissolved in a solvent (t.amine N-oxide). The solution is then extruded or spinned first into air to form a filament then stretched before it is precipitated by treating it with a non-solvent.
  • a solvent t.amine N-oxide
  • This invention provides a process for forming lyocell fibers, comprising forming a dope from cellulose; extruding the dope through a plurality of orifices into a flowing gas stream; stretching the filaments with the flowing gas stream to form substantially continuous elongated filaments; and regenerating the filaments; wherein before regenerating the filaments the filaments are further stretched by applying an external force in a direction parallel to a length of the filaments to attenuate the filaments, the external force being provided by something other than the gas stream or gravity.
  • Lyocell filaments produced by a process carried out in accordance with the present invention and lyocell fibers cut from such filaments exhibit desirable properties such as low susceptibility, smooth surfaces, low variability in cross-sectional diameter along the filament or fiber length and from fiber to fiber and little natural crimp.
  • the filaments and fibers possess strength properties to make them suitable for many applications where lyocell filaments and fibers are presently used or contemplated.
  • a further advantage of the present invention is that it will enable higher speed spinning of lyocell filaments compared to the speed at which filaments are spun using conventional dry-jet wet or melt blowing processes. Higher speed spinning will result in increased production rates by increasing dope throughput. Alternatively, if dope throughput is not increased, fiber diameter can be decreased.
  • the degree to which the extruded filament is attenuated by the gas and the degree to which the filament is attenuated mechanically in accordance with the present invention can vary. For example, in certain embodiments it may be preferred that the gas provides most of the attenuation with little mechanical attenuation. In other situations it may be preferred that little attenuation results from introducing the extruded filament into the gas stream and that most of the attenuation be provided mechanically.
  • Bicomponent cellulose filaments comprising cellulose and other polymers and filaments comprising blends of cellulose and other materials can also be produced using a process carried out in accordance with the present invention by forming dopes from combinations of cellulose with other polymers.
  • a dope is formed by dissolving cellulose, preferably in the form of wood pulp in an amine oxide, preferably a tertiary amine N-oxide containing a non-solvent for cellulose such as water.
  • the wood pulp can be any of a number of commercially available dissolving or non-dissolving grade pulps from sources such as the Weyerhaeuser Company, assignee of the present application, International Paper Company, Sappi Saiccor sulfite pulp, and prehydrolyzed kraft pulp from International Paper Company.
  • the wood pulp can be a high hemicellulose, low degree of polymerization pulp as described in U.S. Patent Application Serial Nos. 09/256,197 and 09/185,432 and International Publication No. WO 99/47733 which are incorporated herein by reference.
  • amine oxide solvents useful in the practice of the present invention are set forth in U.S. Patent No. 5,409,532 .
  • the presently preferred amine oxide solvent is N-methyl-morpholine-N-oxide (NMMO).
  • NMMO N-methyl-morpholine-N-oxide
  • Other representative examples of solvents useful in the practice of the present invention include dimethylsulfoxide (DMSO), dimethylacetamide (DMAC), dimethylformamide (DMF) and caprolactan derivatives.
  • DMSO dimethylsulfoxide
  • DMAC dimethylacetamide
  • DMF dimethylformamide
  • caprolactan derivatives caprolactan derivatives.
  • the pulp can be dissolved in amine oxide solvent by any art-recognized means such as are set forth in U.S. Patent Nos. 5,534,113 ; 5,330,567 and 4,246,221 .
  • FIGURE 1 shows a block diagram of the presently preferred process for forming lyocell filaments from cellulose dopes.
  • the cellulose in the form of pulp is physically broken down, for example by a shredder, before being dissolved in an amine oxide-water mixture to form the dope.
  • the pulps can be dissolved in an amine solvent by any known manner, e.g., as taught in McCorsley U.S. Patent No. 4,246,221 .
  • the pulp can be wet in a nonsolvent mixture of about 40% NMMO and 60% water.
  • the ratio of pulp to wet NMMO can be about 1:5.1 by weight.
  • the mixture can be mixed in a double arm sigma blade mixer for about 1.3 hours under vacuum at about 120°C until sufficient water has been distilled off to leave about 12%-14% based on NMMO so that a cellulose solution is formed.
  • NMMO of appropriate water content may be used initially to obviate the need for the vacuum distillation. This is a convenient way to prepare spinning dopes in the laboratory where commercially available NMMO of about 40%-60% concentration can be mixed with laboratory reagent NMMO having only about 3% water to produce a cellulose solvent having 7%-15% water. Moisture normally present in the pulp should be accounted for in adjusting necessary water present in the solvent. Reference might be made to articles by Chanzy, H. and A.
  • the- dope is processed through a meltblown head which extrudes the dope through a plurality of orifices into a turbulent air stream moving generally parallel to the direction the dope exits the orifices, rather than directly into an air gap where there is no air flow or an air flow transverse to the direction that dope exits the orifices as in the case of a dry-jet wet process.
  • Parallel air flow describes the flow of air downstream from the point where the dope exits the orifices.
  • the air exiting the meltblown head may not necessarily be traveling parallel to the direction that the filaments are traveling; however, at some point downstream from the point where the dope exits the orifices, in accordance with the present invention, the air begins to flow in a direction that is parallel to the direction that the filaments are traveling.
  • the high-velocity air draws or stretches the filaments. This air attenuation differs from mechanical attenuation by providing more variable tension and may not provide a continuous tension due to the turbulence of the air flow.
  • This non-mechanical stretching serves two purposes: it causes some degree of longitudinal molecular orientation and accelerates the filaments rapidly as they leave the nozzle orifice, thus reducing the ultimate fiber diameter.
  • the air stream is also believed to stabilize the latent filament as described below in more detail.
  • additional attenuation of the filaments is accomplished by applying an external force to the filaments in a direction parallel to the length of the filaments where such external force is supplied by something other than the gas stream or gravity.
  • an external force is provided by a mechanical device such as a take-up device in the form of a winder or take-up roll.
  • Such devices provide a mechanical attenuation that complements and is in addition to the attenuation provided by the air stream.
  • the latent filaments can be regenerated before they are taken up by the device providing the mechanical attenuation.
  • the process carried out in accordance with the present invention produces substantially continuous elongate filaments which, once they are regenerated, are collected as substantially continuous elongate filaments.
  • Such continuous elongate filaments are in contrast to shorter, staple noncontinuous fibers produced by prior meltblown processes, such as the one described in International Publication No. WO98/26122 .
  • the dope is delivered at somewhat elevated temperature to the spinning apparatus by a pump or extruder at temperatures from 70°C to up to about 140°C.
  • the temperature of the dope should not be so high that rapid decomposition of the solvent occurs or so low that the dope becomes brittle and unspinnable.
  • Regenerating solutions are nonsolvents such as water, a water-NMMO mixture, lower aliphatic alcohols, or mixtures of these.
  • the NMMO used as the solvent can then be recovered from the regenerating bath for reuse.
  • the regenerating solution is applied as a fine spray at some predetermined distance below the extrusion head.
  • FIGURE 2 shows details of a presently preferred embodiment of a modified melt blowing process formed in accordance with the present invention.
  • a supply of dope is directed through an extruder and positive displacement pump, not shown, through line 200 to an extrusion head 204 having a multiplicity of orifices.
  • Compressed air or another gas is supplied through line 206.
  • Latent filaments 208 are extruded from orifices 340 (seen in FIGURE 3) in the Z-direction. These thin strands of dope 208 are picked up by the high velocity gas stream traveling in the Z-direction created by air exiting intermittent slots 344 (FIGURE 3) in the extrusion head.
  • the filaments are significantly stretched or elongated as they are carried downward by the air stream.
  • the now stretched latent filaments strands 208 pass between opposing spray pipes 210, 212 and are contacted with a water spray or other regenerating liquid 214.
  • the regenerated filaments 215 are picked up by a rotating pickup roll 216 which serves as the source of the external force that causes the mechanical attenuation of the filaments.
  • a new roll 216 is brought in to stretch and collect the filaments without slowing production, much as a new reel is used on a paper machine.
  • the surface speed of roll 216 is faster than the linear speed of the descending filaments 215 so that the filaments are mechanically drawn.
  • the mechanical force exerted on the filaments by the take up device is related to the surface speed of the roll 216, the rate that the filaments are carried by the gas stream, and the speed the dope is expelled from the orifices.
  • a moving foraminiferous belt may be used in place of the roll to collect and mechanically stretch the filaments and direct them to any necessary downstream processing.
  • the roller is operated above a minimum surface speed that imparts at least some mechanical attenuation to the filaments.
  • the maximum speed at which the roller can be operated will be determined by a number of factors including the maximum speed at which a continuous filament can be formed.
  • the filament will tend to be larger in diameter as opposed to a filament formed when the roller is operated at a higher speed.
  • Continuous filaments have been made using winder speeds ranging from about 200-1000 meters/minute. It should be understood that the present invention is not limited to a specific type of take up device, other types of take up devices such as conveyers, belts, rollers, and the like can provide satisfactory results.
  • the regeneration solution containing diluted NMMO or other solvent drips off the accumulated fiber 220 into container 222. From there it is sent to a solvent recovery unit where recovered NMMO can be concentrated and recycled back into the process.
  • FIGURE 3 shows a cross section of a presently preferred extrusion head 300 useful, in the presently preferred process.
  • a manifold or dope supply conduit 332 extends longitudinally through the nosepiece 340.
  • a capillary or multiplicity of capillaries 336 descend from the manifold. These decrease in diameter in a transition zone 338 into the extrusion orifices 340.
  • Gas chambers 342 also extend longitudinally through the die. These exhaust through slits 344 located adjacent the outlet end of the orifices. Slits or slots 344 are located intermittently along the length of head 300, centered on the orifices 340.
  • slots 344 can vary depending upon a number of factors, such as the volume of air which is desired to flow through slots 334 as well as the desired velocity of the gas exiting slots 334. Generally, smaller slots will provide higher velocity gases for a given pressure within chamber 342, and larger slots will provide lower gas velocities at similar pressures in chamber 342. For the orifice diameters described below, slots having a width of the order of 2.54 x 10 -4 meters (0.01 inches) and a length of 00635 meters (0.25 inches) have been found to be suitable.
  • Internal conduits 346 supply access for electrical heating elements or steam/oil heat.
  • the gas supply in chambers 342 is normally supplied preheated but provisions may also be made for controlling its temperature within the extrusion head itself.
  • the dope is extruded into a flowing gas stream which travels in a direction substantially parallel to the direction that the dope is extruded through orifice 340.
  • Gas exiting slits 344 join at some predetermined angle to form a single jet which flows along the axis dividing the angle formed by the two opposing streams of gas.
  • the jets exiting slits 344 join at an included angle of 60° and merge to form a single jet which flows parallel to the direction that the dope is extruded through slit 340.
  • the mean air direction is provided in a direction that is substantially parallel to the direction that the dope is extruded from slot 34.0 and the direction that the latent filaments travel.
  • FIGURE 3 illustrates a preferred embodiment of an extrusion head useful in accordance with the present invention
  • extrusion beads described in U.S. Patent No. 4,380,570 and U.S. Patent No. 5,476,616 are examples of useful extrusion heads.
  • Another suitable extrusion head is described in GB 2337957A to Law .
  • the capillaries and nozzles in the extrusion head nosepiece of FIGURE 3 can be formed in a unitary block of metal by any appropriate means such as drilling or electrodischarge machining.
  • the nosepiece may be machined as a split die with matched halves 348, 348" (FIGURE 3). This presents a significant advantage in machining cost and in ease of cleaning.
  • Spinning orifice diameter may be in the 300-600 ⁇ m range, preferably about 400-500 ⁇ m with a L/D ratio in the range of about 2.5-10. Most desirably a lead in capillary of greater diameter than the orifice is used. Capillaries that are about L2-2.5 times the diameter of the orifice and that have' a L/D ratio of about 10-250 are suitable. Larger orifice diameters utilized in the presently preferred apparatus and method are advantageous in that they are one factor allowing greater throughput per unit of time. e.g.. throughputs that equal or exceed about 1 g/min/orifice.
  • larger diameter orifices are not nearly as susceptible to plugging from smalt bits of foreign matter or undissolved material in the dope as are the smaller nozzles.
  • the larger nozzles are much more easily cleaned if plugging should occur and construction of the extrusion heads is considerably simplified, in part due to lower pressures required.
  • Operating temperature and temperature profile along the orifice and capillary preferably fall within the range of about 70°C to about 140°C to avoid a brittle dope or rapid solvent degradation. It appears beneficial to have a rising temperature near the exit of the spinning orifices. There are many advantages to operation at as high a temperature as possible, up to about 140°C where NMMO begins to rapidly decompose.
  • throughput rate may generally be increased due to a reduction of viscosity at higher dope temperatures.
  • die decomposition temperature may be safely approached at the exit point since the time the dope is held at or near this temperature is very minimal.
  • Air temperature as it exits the melt blowing head can be in the 40°-140°C range, preferably about 70°C.
  • the minimum velocity of the gas stream is preferably greater than the velocity of the dope exiting the orifices so that at least some attenuation of the formed filament is caused by the gas stream.
  • the gas maximum velocity will depend on the end result desired. At some maximum velocity staple (discontinuous) fibers will be formed, as opposed to continuous filaments which tend to be produced at lower gas velocities.
  • the gas velocity can be adjusted in relation to the surface speed of the roller and dope flow rate to tailor the amount of non-mechanical stretching imparted by the gas stream compared to the mechanical stretching imparted by the take up device.
  • gas pressure at the entrance to 0.00635 meters (0.25 inch) long and 2.54 x 10 -4 meters (0.010 inch) wide slots 344 ranging from about 413.7 Pascals (0.06 psi) to about 13100.5 Pascals (1.90 psi) provide gas velocities of just greater than zero (0) up to sonic.
  • an air pressure in chambers 342 of about 2757.9 Pascals (0.4 psi) provides an air velocity at the exit of slots 344 of approximately 175 meters/second when the slots 34 are 0.00635 meters (0.25 inch) long and 2.5 x 10 -4 meters (0.01 inch) wide.
  • Varying the humidity of the gas can affect the properties of the produced fibers, for example air with a higher humidity tends to produce fibers that have smaller diameters, as compared to fibers made using air with a lower humidity.
  • a minimal gas flow parallel to the direction the dope exits the die in a conventional dry-jet wet process will stabilize the formed filaments from lateral movements which otherwise may result in adjacent filaments becoming fused to each other.
  • a minimal gas flow parallel to the direction the dope exits the die may avoid spring back of the latent filaments which can result in the formation of loops due to the elasticity of the latent filaments.
  • An additional benefit of providing a gas flow parallel to the direction the dope exits the die relates to the ability to assist in guiding the filaments to the take up device after they are initially formed by the die.
  • Lyocell filaments having the following properties have been produced by a process carried out in accordance with the present invention: Fineness: about 2.2 to 0.5 dtex Dry Tenacity: about 33 to 42 cN/tex Wet Tenacity: about 22 to 28 cN/tex Dry Elongation: about 11% to 14% Wet Elongation: about 12% to 15% Loop Tenacity: about 13 to 18 cN/tex Dry Modulus: about 670 to 780 cN/tex Wet Modulus: about 170 to 190 cN/tex Bundle Strength: about 33 to 47 cN/tex Diameter variability along fiber about 6 to 17 CV% Diameter variability between fibers about 10 to 22 CV% Fibrillation index: about 0 to 1 Dyeability Good
  • lyocell filaments of less than one denier can be produced in accordance with the present invention. Specific examples of properties of lyocell filaments produced by a process carried out in accordance with the present invention are described below.
  • This comparative example illustrates the production of lyocell fibers using a dry-jet wet process without air attenuation.
  • Dope was prepared from an acid treated pulp described in International Publication No. WO99/47733 having a hemicellulose content of 13.5% and an average cellulose degree of polymerization of about 600.
  • the treated pulp was dissolved in NMMO to provide a cellulose concentration of about 12 weight percent and spun into filaments by a dry-jet wet process as described in U.S. Patent No. 5,417,909 .
  • the dry-jet wet spinning procedure was conducted by Thuringisches Instut fur Textil-und Kunststoff-Forschung.
  • This comparative example illustrates the production of lyocell filaments using a melt-blowing process without mechanical attenuation.
  • a dope was prepared from an acid treated pulp described in Example 10 of International Publication WO99/47743 having a hemicellulose content of 13.5% and an average degree of polymerization of about 600.
  • the acid treated pulp was dissolved in NMMO.
  • NMMO n-methyl methacrylate
  • Nine grams of the dried, acid-treated pulp were dissolved in a mixture of 0.025 grams of propyl gallate, 61.7 grams of 97% NMMO and 21.3 grams of 50% NMMO producing a cellulose concentration of about 9.8%.
  • the flask containing the mixture was immersed in an oil bath at about 120°C, a stirrer was inserted, and stirring was continued for about 0.5 hours until the pulp dissolved.
  • the resulting dope was maintained at about 120°C and fed to a single orifice laboratory melt blowing head.
  • Diameter at the orifice of the nozzle portion was 483 ⁇ m and its length about 2.4 mm, a L/D ratio of 5.
  • a removable coaxial capillary located immediately above the orifice was 685 ⁇ m in diameter and 80 mm long, a L/D ratio of 116.
  • the included angle of the transition zone between the orifice and capillary was about 118°.
  • the air delivery ports were parallel slots with the orifice opening located equidistant between them. Width of the air gap was 250 ⁇ m and overall width at the end of the nosepiece was 1.78 mm.
  • the angle between the air slots and centerline of the capillary and nozzle was 30°.
  • the dope was fed to the extrusion head by a screw-activated positive displacement piston pump. Air velocity was measured with a hot wire instrument as 3660m/min. The air was warmed within the electrically heated extrusion head to 60-70°C at the discharge point. Temperature within the capillary without dope present ranged from about 80°C at the inlet end to approximately 140°C just before the outlet of the nozzle portion. It was not possible to measure dope temperature in the capillary and nozzle under operating conditions. When equilibrium running conditions were established a continuous fiber was formed from the dope. Throughput was greater than about 1 gram of dope per minute.
  • a fine water spray was directed on the descending fiber at a point about 200 mm below the extrusion head and the fiber was taken up on a roll operating with a surface speed about 1/4 the linear speed of the descending fiber.
  • the properties of the collected fibers are summarized in Table 1 below under the heading MB.
  • Examples 1-3 illustrate and describe embodiments of a process for producing lyocell filaments in accordance with the present invention and are intended for illustrative purposes and not for purposes of limiting the scope of the present invention.
  • a dope for forming lyocell filaments was made by dissolving in N-methyl morpholine N-oxide a kraft pulp having an average degree of polymerization of about 600 as measured by ASTM D 1795-62, and a hemicellulose content of about 13% as measured by a Weyerhaeuser Company Dionex sugar analysis method.
  • the cellulose concentration in the dope was 12% by weight.
  • the dope was extruded from a meltblowing die that had 20 nozzles having an orifice diameter of 457 microns at a rate of 0.625 grams/hole/minute.
  • the orifices had a length/diameter ratio of 5.
  • the die was maintained at a temperature ranging from 100 to 130 degrees Celsius.
  • the dope was extruded into an air gap 12.7 centimeters long before coagulation with a water spray. Air at a temperature greater than 90 degrees Celsius and a pressure of 137895 Pascals (20 psi) was supplied to the head. The air pressure in the air cap (chamber 342 in FIGURE 3) was about 2757.9 Pascals (0.4 psi) and flowed at a rate of about 0.028 meters 3 per minute (18 SCFM). This provided an air velocity at the exit to the air slots of about 175 meters/second. In this example, the slots were 0.00635 meters (0.25 inches) long and 2.5 x 10 4 meters (0.010 inches) wide.
  • the formed filaments were taken up by a winder operating at a speed of 500 meters/minute which was greater than the linear speed of the filaments in the air gap. Water was used to precipitate the cellulose from the formed filaments. The water was' applied by spraying it onto the filaments in advance of the winder. Four different samples were made using the above process. The samples were designated MBA-1 through MBA-4.
  • TTTK test using DIN EN ISO 1973 dry tenacity (TTTK tests using DIN EN ISO 5079), dry elongation (TTTK test using DIN EN ISO 5079), wet tenacity (TTTK test using DIN EN ISO 5079), wet elongation (TTTK test using DIN EN ISO 5079), relative wet tenacity (i.e., wet tenacity/dry tenacity), loop tenacity (TTTK test using DIN 53 843 T2), dry modulus (TITK test using DIN EN ISO 5079); wet modulus (TTTK test using DIN EN ISO 5079), diameter variability CV% (microscope measurement of 200 fibers for among fiber CV% and 200 readings from a bundle strength (stelometer measurement by International Textile Center.
  • the fibrillation index was determined by viewing SEM photos of about 100 fiber segments about 10 microns in length. If 0 to 1 fibril/segment was observed, the fiber was rated 0. If each segment included 5-6 fibrils or the segments became fragmented as in FIGURE 5, a rating of 10 was assigned. TABLE 1 Sample DJW-Newcell® filament MBA-1 MBA-2 MBA-3 MBA-4 DJW-TITK DJW.
  • the resulting filaments MBA-1 through MBA-4 possess similar tenacity as commercial lyocell filaments made by a dry-jet wet process available from Newcell GmbH & Co. KG, Kasino Str., 19-21 D-42103 Wuppertal as Newcell ® (DJW-Newcell ® ), but have higher dry elongation than such commercial filaments.
  • the filaments of Example 1 also have higher loop strength compared to lyocell staple fibers prepared from similar dopes using the TITK dry-jet wet method described in comparative Example 1.
  • the fibers of Example 1 also have higher dry modulus compared to lyocell staple fibers prepared from similar dopes using the TITK dry-jet wet method of comparative Example 1.
  • the fibers of Example 1 have lower tendency to fibrillate than commercial lyocell fibers produced by a dry-jet wet process available from Accordis Company under the trademark TENCEL ® (DJW-Tencel ® ) and the DJW-TITK fibers.
  • the fibers of Example 1 (MBA-1 through MBA-4) have higher dry and wet tenacity, and lower diameter variability both among and along the fibers.
  • This example illustrates properties of lyocell fibers having a fineness on the order of 1 denier produced in accordance with the present invention. Lyocell filaments having a denier less than 1 can be produced by adjusting the dope viscosity, dope throughput in the orifices, and the winder speed as described below.
  • the resulting filaments MBA-5 through MBA-20 generally had lower diameters and lower diameter variability among the filaments compared to meltblown fibers made without mechanical stretching as described above in Comparative Example 1 and below in Comparative Example 2.
  • FIGURE 6 is a graph representing the average diameter and the average coefficient of variability among the filaments for MBA-1 through MBA-16 produced using the various winder speeds described in Example 1 : From the graph, it is observed that as the winder speed increases, the dry fiber diameter decreases as well as the coefficient of variation.
  • Example 1 In order to produce filaments using a conventional meltblown process without mechanical attenuation, the procedure of Example 1 was repeated using a dope as described in Example 1 with the exception that the winder speed was 0 meters/minute. Under these conditions, the formed filaments had an average diameter of 26.1 microns and a coefficient of variation among fibers of 44%.
  • Example 1 The procedure of Example 1 was repeated using a different air pressure.
  • the winder speed was 500 meters/minute.
  • the pressure of the air supplied to the meltblowing head was 6895 Pascals (1 psi) which resulted in a pressure of about 413.7 Pascals (0.06 psi) in the air cap (chamber 342 in FIGURE 3).
  • This low pressure provided a perceptible flow of air in'the air gap travelling at a velocity greater than the linear velocity of the filaments exiting the orifices.
  • the air flow was observed to attenuate the extruded filaments.
  • the average diameter of the filaments produced was 14.74 microns.
  • the filament diameter ranged from 64.12 to 7.10 microns.
  • Example 1 The procedure of Example 1 was repeated using a different air pressure and winder speed.
  • the pressure of the air supplied to this meltblowing head was 0 Pascals (0 psi) resulting in no flow of air in the air gap. Under these conditions filaments could not be produced at a winder speed of 500 meters/min. At such winder speed with no air flow the extruded dope was observed to break up.
  • a dope for forming lyocell filaments was made by dissolving in N-methyl morpholine N-oxide, a Kraft pulp having an average degree of polymerization of about 750 as measured by ASTMD1795-62 and a hemicellulose content of about 13% as measured by a Weyerhaeuser Company dionex sugar analysis method.
  • the cellulose concentration in the dope was about 12% by weight.
  • the dope was extruded from a melt blowing dye that had 20 nozzles having an orifice diameter of 457 microns at a rate of 0.625 grams/hole/minute.
  • the orifices had a length/diameter ratio of 5.
  • the nozzle was maintained at a temperature ranging from 100° to 130°C.
  • the dope was extruded into an air gap 12.7 cm long before coagulation with a water spray. Air at a temperature greater than 90°C and a pressure of about 137895 Pascals (20 psi) was supplied to the head. The air pressure in the air cap (Chamber 342 in FIGURE 3) was about 2757.9 Pascals (0.4 psi) and flowed at a rate of about 0.51 Meters 3 per minute (18 SCFM). This provided an air velocity at the exit to the air slots of about 175 meters/second.
  • the formed filaments were taken up by a winder operating at a surface speed of about 900 meters/minute. Water was used to precipitate the cellulose from the formed filaments. The water was applied by spraying it onto the filaments in advance of the winder.
  • the collected filaments (MBA-20) were washed and dried and then subjected to the tests described above in Example 1 to assess their fineness, dry tenacity, dry elongation, wet tenacity, wet elongation, loop tenacity, and fibrillation properties. The following values were observed: Fineness (dtex) 1.12 Dry Tenacity (cN/tex) 42.10 Wet Tenacity (cN/tex) 28.10 Dry Elongation (%) 10.60 Wet Elongation (%) 13.10 Loop Tenacity (cN/tex) 16.40 Fibrillation Index 2.00 Average Diameter (microns) 9.40 Diameter Variability (CV%) 21.00

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  • Engineering & Computer Science (AREA)
  • Textile Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Mechanical Engineering (AREA)
  • Spinning Methods And Devices For Manufacturing Artificial Fibers (AREA)
  • Artificial Filaments (AREA)
  • Solid-Sorbent Or Filter-Aiding Compositions (AREA)
  • Crystals, And After-Treatments Of Crystals (AREA)
  • Holding Or Fastening Of Disk On Rotational Shaft (AREA)
  • Physical Deposition Of Substances That Are Components Of Semiconductor Devices (AREA)

Claims (11)

  1. Procédé pour former des fibres Lyocell, comprenant :
    la formation d'une dope à partir de cellulose ;
    l'extrusion de la dope au travers d'une pluralité d'orifices dans un courant de gaz s'écoulant pour produire des filaments ;
    l'étirage des filaments avec le courant de gaz s'écoulant pour former des filaments allongés sensiblement continus ; et
    la régénération des filaments ;
    caractérisé en ce que, avant la régénération des filaments, les filaments sont davantage étirés en appliquant une force externe dans une direction parallèle à une longueur des filaments pour amincir les filaments, la force externe étant fournie par quelque chose d'autre que le courant de gaz ou la gravité.
  2. Procédé selon la revendication 1, caractérisé en ce que le courant de gaz s'écoule sensiblement parallèlement à la direction dans laquelle la dope est extrudée au travers des orifices.
  3. Procédé selon la revendication 1, caractérisé en ce que la force externe est fournie par un dispositif mécanique.
  4. Procédé selon la revendication 3, caractérisé en ce que le dispositif mécanique est un rouleau d'entraînement.
  5. Procédé selon la revendication 4, caractérisé en ce que le rouleau d'entraînement est actionné à une vitesse de surface qui est supérieure à la vitesse à laquelle les filaments sont transportés par le courant de gaz.
  6. Procédé selon la revendication 5, caractérisé en ce que la vitesse de surface est comprise entre environ 200 et environ 1 000 mètres/minute.
  7. Procédé selon la revendication 3, caractérisé en ce que le dispositif mécanique est une bande poreuse.
  8. Procédé selon la revendication 7, caractérisé en ce que la bande poreuse est actionnée à une vitesse de surface qui est supérieure à la vitesse à laquelle les filaments sont transportés par le courant de gaz.
  9. Procédé selon la revendication 8, caractérisé en ce que la vitesse de surface est comprise entre environ 200 et environ 1 000 mètres/minute.
  10. Procédé selon la revendication 1, caractérisé en ce que l'étape d'étirage des filaments avec le courant de gaz s'écoulant diminue le diamètre des filaments.
  11. Procédé selon la revendication 1, caractérisé en ce que l'étape d'étirage supplémentaire des filaments en appliquant une force externe diminue le diamètre des filaments.
EP01927152A 2000-04-21 2001-04-17 Procede de fusion-soufflage a attenuation mecanique Expired - Lifetime EP1287191B1 (fr)

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US19883700P 2000-04-21 2000-04-21
US198837P 2000-04-21
PCT/US2001/012554 WO2001081664A1 (fr) 2000-04-21 2001-04-17 Procede de fusion-soufflage a attenuation mecanique

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US9422641B2 (en) 2012-10-31 2016-08-23 Kimberly-Clark Worldwide, Inc. Filaments comprising microfibrillar cellulose, fibrous nonwoven webs and process for making the same
JP6122666B2 (ja) * 2013-03-07 2017-04-26 東京エレクトロン株式会社 ホッパー及び溶射装置
CN108291344B (zh) * 2015-11-10 2022-02-25 营养与生物科学美国4公司 非织造葡聚糖网
EP3536851A1 (fr) 2018-03-06 2019-09-11 Lenzing Aktiengesellschaft Fibre lyocell présentant une tendance accrue à la fibrillation
EP3674452A1 (fr) * 2018-12-28 2020-07-01 Lenzing Aktiengesellschaft Filière, procédé de chauffage d'une filière et procédé lyocell
CN110616466B (zh) * 2019-09-29 2020-08-28 恒天海龙（潍坊）新材料有限责任公司 一种再生纤维素强力丝及其制备方法
CN111910275B (zh) * 2020-07-10 2021-10-01 青岛大学 一种组合式异形熔喷纺丝模头及其生产方法

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US4416698A (en) * 1977-07-26 1983-11-22 Akzona Incorporated Shaped cellulose article prepared from a solution containing cellulose dissolved in a tertiary amine N-oxide solvent and a process for making the article
DE69716092T2 (de) * 1996-08-23 2003-01-30 Weyerhaeuser Co., Tacoma Lyocellfasern und verfahren zu ihrer herstellung
US6210801B1 (en) * 1996-08-23 2001-04-03 Weyerhaeuser Company Lyocell fibers, and compositions for making same
CN1279734A (zh) * 1997-11-20 2001-01-10 康诺科有限公司 用以集合连续喷气纺纤维的方法和装置

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BR0110198A (pt) 2003-02-11
MXPA02010371A (es) 2003-04-25
ATE376597T1 (de) 2007-11-15
JP2003531313A (ja) 2003-10-21
CN1191395C (zh) 2005-03-02
TW561205B (en) 2003-11-11
KR100676572B1 (ko) 2007-01-30
KR20020091205A (ko) 2002-12-05
CA2405091A1 (fr) 2001-11-01
EP1287191A1 (fr) 2003-03-05
AU2001253631A1 (en) 2001-11-07
CA2405091C (fr) 2009-06-30
CN1425081A (zh) 2003-06-18
DE60131077D1 (de) 2007-12-06
BR0110198B1 (pt) 2011-09-06
WO2001081664A1 (fr) 2001-11-01
JP4593865B2 (ja) 2010-12-08

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