Classifications

• • 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
• • 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
• • 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
  • D01F6/00—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof
  • D01F6/02—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from homopolymers obtained by reactions only involving carbon-to-carbon unsaturated bonds
  • D01F6/04—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from homopolymers obtained by reactions only involving carbon-to-carbon unsaturated bonds from polyolefins
• • 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
  • D01F6/00—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof
  • D01F6/02—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from homopolymers obtained by reactions only involving carbon-to-carbon unsaturated bonds
  • D01F6/04—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from homopolymers obtained by reactions only involving carbon-to-carbon unsaturated bonds from polyolefins
  • D01F6/06—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from homopolymers obtained by reactions only involving carbon-to-carbon unsaturated bonds from polyolefins from polypropylene
• • 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
  • D01F6/00—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof
  • D01F6/58—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from homopolycondensation products
  • D01F6/62—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from homopolycondensation products from polyesters
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/29—Coated or structually defined flake, particle, cell, strand, strand portion, rod, filament, macroscopic fiber or mass thereof
  • Y10T428/2904—Staple length fiber
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/29—Coated or structually defined flake, particle, cell, strand, strand portion, rod, filament, macroscopic fiber or mass thereof
  • Y10T428/2913—Rod, strand, filament or fiber
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/29—Coated or structually defined flake, particle, cell, strand, strand portion, rod, filament, macroscopic fiber or mass thereof
  • Y10T428/2913—Rod, strand, filament or fiber
  • Y10T428/2915—Rod, strand, filament or fiber including textile, cloth or fabric
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T442/00—Fabric [woven, knitted, or nonwoven textile or cloth, etc.]
  • Y10T442/60—Nonwoven fabric [i.e., nonwoven strand or fiber material]
  • Y10T442/601—Nonwoven fabric has an elastic quality
  • Y10T442/602—Nonwoven fabric comprises an elastic strand or fiber material
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T442/00—Fabric [woven, knitted, or nonwoven textile or cloth, etc.]
  • Y10T442/60—Nonwoven fabric [i.e., nonwoven strand or fiber material]
  • Y10T442/608—Including strand or fiber material which is of specific structural definition
  • Y10T442/614—Strand or fiber material specified as having microdimensions [i.e., microfiber]
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T442/00—Fabric [woven, knitted, or nonwoven textile or cloth, etc.]
  • Y10T442/60—Nonwoven fabric [i.e., nonwoven strand or fiber material]
  • Y10T442/608—Including strand or fiber material which is of specific structural definition
  • Y10T442/614—Strand or fiber material specified as having microdimensions [i.e., microfiber]
  • Y10T442/626—Microfiber is synthetic polymer

Definitions

• the present invention relates to low denier, high extensible fibers, soft extensible nonwoven webs comprising such fibers, and disposable articles comprising such nonwoven webs.
• Nonwoven webs formed by nonwoven extrusion processes such as, for example, meltblowing and spunbonding processes may be manufactured into products and components of products so inexpensively that the products could be viewed as disposable after only one or a few uses.
• Representatives of such products include disposable absorbent articles, such as diaper, incontinence briefs, training pants, feminine hygiene garments, wipes, and the like.
• Nonwovens that can deliver softness and extensibility when used in disposable products.
• Softer nonwovens are gentler to the skin and help to provide a more garment-like aesthetic for diapers.
• Nonwovens that are capable of high extensibility at relatively low force can be used to provide sustained fit in products such as disposable diapers, for example, as part of a stretch composite, and facilitate the use of various mechanical post-treatments such as stretching, aperturing, etc.
• Extensible materials are defined herein as those capable of elongating, but not necessarily recovering all or any of the applied strain.
• Elastic materials on the other hand, by definition, must recover a substantial portion of their elongation after the load is removed.
• World Patent Application WO 00/04215 discloses a specific bond pattern designed to produce a high elongation nonwoven fabric, specifically for skin-core polypropylene staple fibers.
• the bond pattern has sites in adjacent rows staggered such that they do not overlap one another in the machine direction of manufacture (MD).
• MD machine direction of manufacture
• the sites are rectangular in shape and cover a total bond area of ⁇ 20%. They disclose that fibers at an angle of 35-55° from the MD will not be bonded and therefore allow for higher cross direction of manufacture elongation.
• U.S. Patent Nos. 5,804,286 and 5,921,973 disclose blends of polyethylene and polypropylene with and without a miscible ethylene-propylene copolymer that produce soft, strong nonwovens with low fuzz and good elongation.
• World Patent Application WO 00/31385 discloses polypropylene blends with ethylene copolymers and
• U.S. Patent No. 6,015,317 discloses blends of 2 different ethylene polymers, both for improved bonding and fabric elongation while maintaining good spinning performance.
• 5,616,412 disclosess filaments (2-4 denier per fiber) of polypropylene and higher molecular weight polystyrene that exhibit higher elongation as compared to filaments of only polypropylene.
• U.S. Patent No. 5,322,728 discloses soft nonwovens with good elongation comprising ethylene copolymers
• U.S. Patent No. 4,769,279 discloses soft nonwovens with good elongation comprising ethylene acrylic copolymers.
• 4,804,577 and 4,874,447 disclose extensible meltblown nonwovens comprising a blend of a polyolefin and an elastomeric copolymer of an isoolefin and a conjugated diolefin, for example an isobutylene-isoprene copolymer.
• U.S. Patent No. 5,349,016 discloses drawn fibers of grafted propylene polymers (e.g. styrene or methyl methacrylate grafted onto the polypropylene backbone) that have higher bend recovery and modulus, and in some cases elongation over the neat polypropylene control.
• U.S. Patent No. 6,080,818 discloses fibers for nonwovens comprising a blend of isotactic polypropylene and an atactic flexible polyolefin that have higher elongation than if the flexible polymer was not included.
• U.S. Patent No. 5,494,736 discloses a high elongation carded nonwoven from high elongation fibers that are laid down to be more cross direction oriented than conventional carded fabrics. Bond areas claimed are in the range of 8-25%.
• a means for producing low denier fibers with high elongation to break is disclosed. This combination of properties is accomplished by altering the spinnerette design on fiber lines to have small capillary diameters that maintain the desireable high spinning speeds, but result in moderate to low drawdown ratios as compared to the high drawdown ratios of conventional spinning processes.
• a particular embodiment of the present invention encompasses fibers with a diameter in the range of 5 to 25 microns that are produced by melt spinning a polymer composition such that the drawdown ratio is less than 400, the mass throughput is in the range of 0.01 to 2.0 grams per minute per hole, and the spinnerette diameter is less than 200 microns.
• An alternative embodiment of the present invention encompasses fibers with a diameter in the range of 5 to 25 microns that are produced by melt spinning a polymer composition such that the drawdown ratio is less than 400, the fiber elongation to break is greater than 400 percent, and the spinnerette diameter is less than 200 microns.
• Nonwoven webs with this combination of properties are particularly well suited for use in disposable absorbent articles such as diapers, incontinence briefs, training pants, feminine hygiene garments, wipes, and the like, as they are able to be used in portions of the article where extensibility and softness can aid in the article's comfort and overall performance.
• Figure 1 is a graph illustrating the percent elongation to break of a 400 melt flow rate polypropylene melt spun at 0.2 grams per minute per hole using an 86 micron diameter capillary and a 570 micron diameter capillary.
• absorbent article refers to devices that absorb and contain body exudates, and, more specifically, refers to devices that are placed against or in proximity to the body of the wearer to absorb and contain the various exudates discharged from the body.
• absorbent articles that are not intended to be laundered or otherwise restored or reused as an absorbent article (i.e., they are intended to be discarded after a single use and, preferably, to be recycled, composted or otherwise disposed of in an environmentally compatible manner).
• a "unitary” absorbent article refers to absorbent articles that are formed of separate parts united together to form a coordinated entity so that they do not require separate manipulative parts like a separate holder and liner.
• nonwoven web refers to a web that has a structure of individual fibers or threads which are interlaid, but not in any regular, repeating manner.
• Nonwoven webs have been, in the past, formed by a variety of processes, such as, for example, air laying processes, meltblowing processes, spunbonding processes and carding processes, including bonded carded web processes.
• microfibers refers to small diameter fibers having an average diameter not greater than about 100 microns, and a length-to-diameter ratio of greater than about 10.
• the diameter of the fibers comprising a nonwoven web impact its overall softness and comfort, and that the smaller denier fibers generally result in softer and more comfortable products than larger denier fibers.
• the diameters are in the range of about 5 to 25 microns to achieve suitable softness and comfort, more preferable in the range from about 10 to 25 microns in diameter, and even more preferable in the range from about 10 to 20 microns in diameter.
• the fiber diameter can be determined using, for example, an optical microscope calibrated with a 10 micrometer graticule.
• meltblown fibers refers to fibers formed by extruding a molten thermoplastic material through a plurality of fine, usually circular, die capillaries as molten threads or filaments into a high velocity gas (e.g., air) stream which attenuates the filaments of molten thermoplastic material to reduce their diameter, which may be to a microfiber diameter. Thereafter, the meltblown fibers are carried by the high velocity gas stream and are deposited on a collecting surface to form a web of randomly dispersed meltblown fibers.
• a high velocity gas e.g., air
• spunbonded fibers refers to small diameter fibers that are formed by extruding a molten thermoplastic material as filaments from a plurality of fine, usually circular, capillaries of a spinneret with the diameter of the extruded filaments then being rapidly reduced by drawing using conventional godet winding systems or through air drag attenuation devices. If a godet system is used, the fiber diameter can be further reduced through post extrusion drawing.
• consolidation and “consolidated” refer to the bringing together of at least a portion of the fibers of a nonwoven web into closer proximity to form a site, or sites, which function to increase the resistance of the nonwoven to external forces, e.g., abrasion and tensile forces, as compared to the unconsolidated web.
• Consolidated can refer to an entire nonwoven web that has been processed such that at least a portion of the fibers are brought into closer proximity, such as by thermal point bonding. Such a web can be considered a "consolidated web”.
• a specific, discrete region of fibers that is brought into close proximity, such as an individual thermal bond site can be described as "consolidated".
• Consolidation can be achieved by methods that apply heat and/or pressure to the fibrous web, such as thermal spot (i.e., point) bonding.
• Thermal point bonding can be accomplished by passing the fibrous web through a pressure nip formed by two rolls, one of which is heated and contains a plurality of raised points on its surface, as is described in the aforementioned U.S. Pat. No. 3,855,046 issued to Hansen, et al..
• Consolidation methods can also include, but are not limited to, ultrasonic bonding, through-air bonding, resin bonding, and hydroentanglement.
• Hydroentanglement typically involves treatment of the fibrous web with high pressure water jets to consolidate the web via mechanical fiber entanglement (friction) in the region desired to be consolidated, with the sites being formed in the area of fiber entanglement.
• the fibers can be hydroentangled as taught in U.S. Pat. Nos. 4,021,284 issued to Kalwaites on May 3, 1977 and 4,024,612 issued to Contrator et al. on May 24, 1977, both of which are hereby incorporated herein by reference.
• nonwoven web of the present invention can find beneficial use as a component of a disposable absorbent article, such as a diaper, its use is not limited to disposable absorbent articles.
• the nonwoven web of the present invention can be used in any application requiring, or benefiting from, softness and extensibility, such as wipes, polishing cloths, furniture linings, durable garments, and the like.
• the extensible, soft nonwoven of the present invention may be in the form of a laminate.
• Laminates may be combined by any number of bonding methods known to those skilled in the art including, but not limited to, thermal bonding, adhesive bonding including, but not limited to spray adhesives, hot melt adhesives, latex based adhesives and the like, sonic and ultrasonic bonding, and extrusion laminating whereby a polymer is cast directly onto another nonwoven, and while still in a partially molten state, bonds to one side of the nonwoven, or by depositing melt blown fiber nonwoven directly onto a nonwoven.
• thermal bonding adhesive bonding including, but not limited to spray adhesives, hot melt adhesives, latex based adhesives and the like, sonic and ultrasonic bonding, and extrusion laminating whereby a polymer is cast directly onto another nonwoven, and while still in a partially molten state, bonds to one side of the nonwoven, or by depositing melt blown fiber nonwoven directly onto a nonwoven.
• polymer composition generally includes, but is not limited to, homopolymers, copolymers, such as, for example, block, graft, random and alternating copolymers, terpolymers, etc., and blends and modifications thereof.
• polymer composition shall include all possible geometrical configurations of the material. These configurations include, but are not limited to, isotactic, syndiotactic and random symmetries.
• Preferred polymer compositions comprise polyolefins such as polyethylene and polypropylene, or polyesters such as poly(ethylene terephthalate) and copolymers thereof.
• Preferred additional polyesters include, but are not limited to, poly(lactic acid) (e.g., Lacea from Mitsui Chemicals, or EcoPLA from Dow Cargill), poly(caprolactone) (e.g., Tone P787 from Union Carbide), poly(butylene succinate) (e.g., Bionolle 1000 series from Showa Denko), poly(ethylene succinate) (e.g., Lunare SE from Nippon Shokubai), poly(butylene succinate adipate) (e.g., Bionolle 3000 series from Showa Denko), poly(ethylene succinate adipate), aliphatic polyester-based polyurethanes (e.g., Morthane PN03-204, PN03-214, and PN3429-100 from Morton International), copolyesters of adipic acid, terephthalic acid, and 1 ,4-butanediol (e.g., Eastar Bio from Eastman Chemical Company, and Eco
• the polymer compositions may further include various nonpolymeric components including, among others, nucleating agents, antiblock agents, antistatic agents, slip agents, pro-heat stabilizers, antioxidants, pro-oxidant additives, pigments, fillers and the like. These additives may be employed in conventional amounts although, typically, such additives are not required in the composition in order to obtain the advantageous combination of softness and extensibility.
• melt flow rate of the polymer composition is suitable for the fiber producing method of interest, for example, melt spinning or melt blowing.
• the melt flow rate of a polymer composition can be determined using, for example, the methods outlined in ASTM D1238.
• the term "extensible” refers to any fiber, which, upon application of a biasing force, is elongatable to at least about 400 percent without experiencing catastrophic failure, more preferable to at least 600 percent elongation without experiencing catastrophic failure, and even more preferable to at least 800 percent elongation without experiencing castastrophic failure.
• the percent elongation to break can be determined using, for example, the method outlined in ASTM D3822, and is defined as the expanded length at break minus the initial test gauge length divided by the initial test gauge length multiplied by 100.
• Continuous fibers, staple fibers, hollow fibers, shaped fibers, such as multi-lobal fibers and multicomponent fibers can all be produced by using the methods of the present invention.
• Component as used herein, is defined as a separate part of the fiber that has a spatial relationship to another part of the fiber.
• Multicomponent fibers commonly a bicomponent fiber, may be in a side -by-side, sheath-core, segmented pie, ribbon, or islands-in-the-sea configuration.
• the sheath may be continuous or non-continuous around the core.
• the fibers of the present invention may have different geometries that include round, elliptical, star shaped, rectangular, and other various eccentricities.
• the fibers of the present invention may also be splittable fibers. Splitting may occur by rheological differences in the polymers or splitting may occur by a mechanical means and/or by fluid induced distortion.
• the diameter of a noncircular cross section fiber is the equivalent diameter of a circle having the same cross-sectional area.
• V x is the total fiber velocity
• Q the mass throughput per spinnerette hole
• P f the density of the fiber
• d the diameter (or equivalent diameter) of the fiber.
• the total fiber velocity is composed of two main components
• V X V 0 + V A
• V 0 is the fiber exit velocity from the spinnerette
• V A the apparent velocity of the fiber associated with attenuation of the filament.
• the most notable contributions to determining V A are the inertial, drag and rheological forces.
• the N A forces are what develop the orientation in the filament.
• the exit velocity of the fiber is calculated according to Equation 3 and depends only on Q and the diameter (or equivalent diameter) of the capillary D
• the density p me ⁇ t in this case is the polymer melt density.
• D is the only variable and thus the exit velocity depends only on the diameter of the capillary.
• mass throughputs of about 0.01 grams per minute per hole are considered minimal.
• mass throughputs greater than about 2.0 grams per minute per hole can lead to die flow instabilities, for example melt fracture or wall slippage, leading to difficulities in processing or in collecting product of suitable quality. Therefore, it is preferred that mass throughputs be in the range of 0.01 to 2.0 grams per minute per hole, more preferable in the range of 0.2 to 1.0 grams per minute per hole, and even more preferable in the range of 0.6 to 0.8 grams per minute per hole.
• the mass throughput per hole can be determined, for example, by collecting the extrudate for a given amount of time and then dividing the value of the total mass collected by the time interval over which it is collected and by the number of holes in the spinnerette for which filaments are exiting.
• the drawdown ratio V x /V 0 or attenuation velocity V A can be lowered without lowering throughput by increasing the fiber velocity as it exits the spinneret capillary (V 0 ). This can be accomplished by using a smaller capillary diameter.
• a useful characteristic spinning number that captures much of of the present disclosure is given by
• the exit velocity V 0 of a melt spinning grade polypropylene filament would be approximately 2.5 m/min.
• conventional high speed melt spinning systems must run at or above about 2000 m/min fiber velocities V x to produce a good uniform nonwoven fabric, then the drawdown ratio V x /V 0 would be about 800 and the spinning number S x would be about 7980 microns/(g/min/hole), with the properties associated with such a fiber (e.g., high orientation and low elongation).
• the exit velocity of the filament would be much higher at about 183 m/min, and V x /V 0 would be much lower at approximately 11 and S x would be much lower at about 403 microns/(g/min/hole), for similar spinning conditions.
• the resulting fibers would have lower orientation and higher residual elongation.
• the diameter of the fibers comprising a nonwoven web impact its overall softness and comfort, and that the smaller denier fibers generally result in softer and more comfortable products than larger denier fibers.
• the diameters are in the range of about 5 to 25 microns to achieve suitable softness and comfort, more preferable in the range from about 10 to 25 microns in diameter, and even more preferable in the range from about 10 to 20 microns in diameter. In order to maintain small diameter fibers for uniformity, coverage and softness, this would conventionally require that the throughput Q be lowered. This, however, reduces total output of material leading to a less desireable economic impact.
• mass throughputs of about 0.01 grams per minute per hole are considered minimal.
• mass throughputs greater than about 2.0 grams per minute per hole can lead to die flow instabilities, for example melt fracture or wall slippage, leading to difficulities in processing or in collecting product of suitable quality. Therefore, it is preferred that mass throughputs be in the range of 0.01 to 2.0 grams per minute per hole, more preferable in the range of 0.2 to 1.0 grams per minute per hole, and even more preferable in the range of 0.6 to 0.8 grams per minute per hole.
• the fiber velocities V x must generally be greater than about 500 m/min, on newer moderate speed systems the fiber velocities must generally be greater than about 2000 m/min, and on newer high spinning speed systems the fiber velocities must generally be greater than about 3000 m/min.
• drawdown ratios V x /V 0 will generally result in higher residual fiber elongation to break.
• drawdown ratios of less than about 400 are generally sufficient to produce fibers with elongations to break suitable for producing the soft extensible nonwovens of the present invention, more preferable are drawdown ratios less than about 150, and even more preferable are drawdown ratios less than about 50.
• spinnerette diameters of less than about 200 microns are generally sufficient, more preferable are spinnerette diameters of less than about 150 microns, and even more preferable are spinnerette diameters of less than about 100 microns.
• the term "extensible” refers to any fiber, which, upon application of a biasing force, is elongatable to at least about 400 percent without experiencing catastrophic failure, more preferable to at least 600 percent elongation without experiencing catastrophic failure, and even more preferable to at least 800 percent elongation without experiencing castastrophic failure.
• EXAMPLE 1 This example demonstrates the melt spinning of a polypropylene resin according to the invention. Specifically, a polypropylene resin with a melt flow rate of 400 (Valtech HH441 from Basell Polyolefins Company, Wilmington, DE) is spun into fibers using a vertical single-screw extruder which is mounted on a platform that can be raised and lowered, and which is equipped with a single-hole capillary die and a capillary of about 86 microns in diameter. The molten filament exits the capillary die into ambient air at approximately 25°C, and is drawndown with a height adjustable air drag device that uses compressed air supplied at high pressures to produce a stream of air that surrounds and draws the filament.
• a polypropylene resin with a melt flow rate of 400 (Valtech HH441 from Basell Polyolefins Company, Wilmington, DE) is spun into fibers using a vertical single-screw extruder which is mounted on a platform that can be raised and lowered
• EXAMPLE 2 This example demonstrates the high extensibility of fibers produced according to the invention. Specifically, fiber samples from Example 1 are tested according to ASTM standard D3822. Testing is performed on an MTS synergie 400 tensile testing machine (MTS Systems Corporation, Eden Prairie, MN) equipped with a 10 Newton load cell and pneumatic grips. Tests are conducted at a crosshead speed of 2 inches per minute on single fiber samples with a 1 inch gage length. Samples are pulled to break, and the percent elongation to break is recorded and averaged for 10 specimens collected at the same air gun pressure. The resulting elongations to break are shown in Figure 1, where the spinning speed is calculated according to equation (1) using the fiber diameters measured by microscopy. This example demonstrates that fibers with small diameters (-10-20 microns) can also have high elongations to break (> 600%) when fabricated according to the invention.
• COMPARATIVE EXAMPLE 3 This example compares the fiber extensibilities from Example 2 with those generated using a conventional sized spinnerette. Specifically, the polypropylene resin from Example 1 is melt spun into fibers using a capillary with a diameter of about 570 microns following the procedure and conditions outlined in Example 1, and the elongations to break are determined according to the method outline in Example 2. The resulting elongations to break are shown in Figure 1, where the spinning speed is calculated according to equation (1) using the fiber diameters measured by microscopy. This example demonstrates the enhanced extensibility that is achievable at comparable fiber diameters or spinning speeds when the fibers are spun according to the invention.

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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)
• Nonwoven Fabrics (AREA)
• Spinning Methods And Devices For Manufacturing Artificial Fibers (AREA)

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• 2002
  • 2002-12-03 WO PCT/US2002/038381 patent/WO2003052179A1/en not_active Application Discontinuation
  • 2002-12-03 CA CA002470378A patent/CA2470378A1/en not_active Abandoned
  • 2002-12-03 JP JP2003553045A patent/JP2005513279A/ja not_active Withdrawn
  • 2002-12-03 CN CN02827320.6A patent/CN1615380A/zh active Pending
  • 2002-12-03 AU AU2002352998A patent/AU2002352998A1/en not_active Abandoned
  • 2002-12-03 EP EP02789964A patent/EP1461479A1/de not_active Withdrawn
  • 2002-12-13 US US10/319,021 patent/US20030124348A1/en not_active Abandoned

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