Classifications

• • 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
  • D01F8/00—Conjugated, i.e. bi- or multicomponent, artificial filaments or the like; Manufacture thereof
  • D01F8/04—Conjugated, i.e. bi- or multicomponent, artificial filaments or the like; Manufacture thereof from synthetic polymers
  • D01F8/16—Conjugated, i.e. bi- or multicomponent, artificial filaments or the like; Manufacture thereof from synthetic polymers with at least one other macromolecular compound obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds as constituent
• • 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
• • 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
  • D04H1/4382—Stretched reticular film fibres; Composite fibres; Mixed fibres; Ultrafine fibres; Fibres for artificial leather
  • D04H1/43825—Composite fibres
  • D04H1/43828—Composite fibres sheath-core
• • 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
  • D04H1/4382—Stretched reticular film fibres; Composite fibres; Mixed fibres; Ultrafine fibres; Fibres for artificial leather
  • D04H1/43825—Composite fibres
  • D04H1/4383—Composite fibres sea-island
• • 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
  • D04H1/4382—Stretched reticular film fibres; Composite fibres; Mixed fibres; Ultrafine fibres; Fibres for artificial leather
  • D04H1/43825—Composite fibres
  • D04H1/43832—Composite fibres side-by-side
• • 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
  • D04H3/005—Synthetic yarns or filaments
  • D04H3/009—Condensation or reaction polymers
• • 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
  • D04H3/14—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 yarns or filaments produced by welding
• • 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
  • D04H3/14—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 yarns or filaments produced by welding
  • D04H3/147—Composite yarns or filaments
• • 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
• • 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
  • Y10T428/2929—Bicomponent, conjugate, composite or collateral fibers or filaments [i.e., coextruded sheath-core or side-by-side type]
• • 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]
  • Y10T442/637—Including strand or fiber material which is a monofilament composed of two or more polymeric materials in physically distinct relationship [e.g., sheath-core, side-by-side, islands-in-sea, fibrils-in-matrix, etc.] or composed of physical blend of chemically different polymeric materials or a physical blend of a polymeric material and a filler material
  • Y10T442/641—Sheath-core multicomponent strand or fiber material

Definitions

• the present invention relates to a polyphenylene sulfide (sometimes abbreviated as "PPS”) composite fiber which consists primarily of resins comprising PPS as their main constituents and which is excellent in heat resistance and chemical resistance, and to a nonwoven fabric made from the fiber.
• PPS polyphenylene sulfide
• a PPS resin has excellent characteristics such as heat resistance, flame retardancy and chemical resistance, and is suitable for engineering plastics, films, fibers, nonwoven fabrics, and the like.
• nonwoven fabrics utilizing these excellent characteristics are expected to be used for industrial applications such as heat-resistant filters, electrical insulating materials and battery separators.
• Another proposed nonwoven fabric is a heat-resistant nonwoven fabric produced by spinning fibers comprising 30 wt% or more of a PPS fiber with a degree of crystallinity of 25 to 50% at a spinning rate of 6000 m/min or more, and integrating the fibers by thermal bonding (see Patent Literature 2).
• the fibers produced by high-speed spinning at a spinning rate of 6000 m/min or more have a high crystallinity, which leads to insufficient thermal bondability resulting in a nonwoven fabric of a low mechanical strength.
• Patent Literature 3 is concerned with a thermally adhesive composite fiber and a nonwoven fabric, which are made of a resin consisting primarily of polyphenylene sulfide and are excellent in heat resistance, flame retardancy and chemical resistance.
• An object of the present invention is to provide a polyphenylene sulfide composite fiber having both thermal dimensional stability and excellent thermal bondability and a nonwoven fabric being made from the fiber and having a high mechanical strength.
• the present invention relates to a polyphenylene sulfide composite as defined in claim 1.
• the present invention also relates to a nonwoven fabric made from the polyphenylene sulfide composite fiber.
• the PPS composite fiber of the present invention has both thermal dimensional stability and excellent thermal bondability.
• the nonwoven fabric of the present invention has both thermal dimensional stability and excellent mechanical strength, and therefore can be used for various industrial applications.
• the fiber consists primarily of component A and component B and that each of the components comprises PPS as its main constituent. With this configuration, the fiber exhibits excellent heat resistance, flame retardancy and chemical resistance.
• the term "consists primarily of” means that the components account for 90% by mass or more of the total mass of the fiber.
• the term "comprises as its main constituent” means that a particular ingredient accounts for 85% by mass or more of the total mass of the resin, component, or the fiber.
• PPS composite fiber of the present invention is a PPS composite fiber consisting primarily of component A and component B, component A being a resin that comprises polyphenylene sulfide as its main constituent, component B being a resin that comprises polyphenylene sulfide as its main constituent, having a higher melt flow rate than component A, and forming at least part of the surface of the fiber.
• fibers produced by a common spinning process have fiber structure in which orientation and crystallinity increase from the center of the cross section of the fiber to the surface of the fiber.
• This structure is created as follows: cooling of fibers spun from a spinneret proceeds from the fiber surface toward the inside of the fibers, and due to the cooling, the fluidity beneath the fiber surface is reduced, causing the concentration of spinning stress on the fiber surface, and then oriented crystallization proceeds therefrom.
• the fiber surface which is crucially important for thermal bonding, has a high crystallinity, resulting in insufficient thermal bondability.
• the present invention employs a composite fiber consisting primarily of component A and component B, component A being a resin that comprises polyphenylene sulfide as its main constituent, component B being a resin that comprises polyphenylene sulfide as its main constituent and having a higher melt flow rate than component A.
• component A being a resin that comprises polyphenylene sulfide as its main constituent
• component B being a resin that comprises polyphenylene sulfide as its main constituent and having a higher melt flow rate than component A.
• spinning stress is concentrated on component A, and thereby the orientation and crystallization of component B is suppressed.
• at least part of the fiber surface is formed of component B with suppressed orientation and crystallinity, and as a result the fiber has thermal dimensional stability and very excellent thermal bondability.
• the fiber comprising polyphenylene sulfide as its main constituent has a lower crystallinity in at least part of the fiber surface than in the center of the cross section of the fiber when the crystallinity of the fiber surface is measured in the region from the fiber surface to 1 ⁇ m in radially inward direction of the fiber.
• the fiber provided with such fiber structure with the opposite configuration to that of the structure of fibers produced by common spinning process achieves both thermal dimensional stability and very excellent thermal bondability.
• the PPS in components A and B preferably contains 93 mol% or more of p-phenylene sulfide units.
• the PPS containing 93 mol% or more of p-phenylene sulfide units, more preferably 95 mol% or more of p-phenylene sulfide units, provides excellent spinnability and produces fibers with excellent mechanical strength.
• Components A and B each preferably contain 85% by mass or more of the PPS resin, more preferably 90% by mass or more of the PPS resin, further more preferably 95% by mass or more of the PPS resin, for achieving heat resistance, chemical resistance, and the like.
• Components A and B each may contain a thermoplastic resin other than the PPS resin as long as the effects of the present invention are not impaired.
• thermoplastic resin other than the PPS resin include polyetherimide, polyethersulfone, polysulfone, polyphenylene ether, polyester, polyarylate, polyamide, polyamide-imide, polycarbonate, polyolefin, and polyether ether ketone.
• Components A and B each may contain additives such as nucleating agents, delustrants, pigments, antifungal agents, antimicrobial agents, fire retardants and hydrophilizing agents, as long as the effects of the present invention are not impaired.
• the MFR of component A of the present invention as measured in accordance with ASTM D1238-70 is preferably 50 to 300 g/10 min.
• the MFR is 50 g/10 min or more, more preferably 100 g/10 min or more, adequate fluidity is obtained, and thereby an increase in the back pressure at the spinneret is suppressed and breakage of fibers during drawing and stretching is prevented.
• the MFR is 300 g/10 min or less, more preferably 225 g/10 min or less, an appropriately high polymerization degree or molecular weight is obtained, and thereby sufficient mechanical strength and heat resistance for practical use are obtained.
• the MFR (as measured in accordance with the above ASTM D1238-70) of component B of the present invention is higher (i.e., the viscosity is lower) than that of component A.
• the difference obtained by subtracting the MFR of component A from the MFR of component B is 10 g/10 min or more, preferably 50 g/10 min or more, more preferably 100 g/10 min or more. With this condition, spinning stress imposed to component B is reduced, and thereby the oriented crystallization of component B is suppressed.
• the difference obtained by subtracting the MFR of component A from the MFR of component B is 1000 g/10 min or less, preferably 500 g/10 min or less, more preferably 200 g/10 min or less. With this condition, adequate fluidity is obtained, and thereby stable spinning can be performed.
• the amount of component B is preferably 5 to 70% by mass of the total amount of the PPS composite fiber.
• the amount of component B is 5% by mass or more, more preferably 10% by mass or more, further more preferably 15% by mass or more, strong thermal bonding is achieved efficiently.
• the amount of component B is 70% by mass or less, more preferably 50% by mass or less, further more preferably 30% by mass or less, the decrease in mechanical strength is prevented.
• component B forms at least part of the fiber surface.
• component B exposed to the surface of the fiber contributes to thermal bonding.
• component A is preferably successively disposed in the longitudinal direction of the PPS composite fiber of the present invention. The successive disposition of component A in the longitudinal direction of the fiber more effectively concentrates spinning stress on component A and suppresses the orientation and crystallization of component B.
• Examples of the composite form of the PPS composite fiber of the present invention include a core-sheath type of which the cross section has circle-shaped component A surrounded by concentric donut-shaped component B, an eccentric core-sheath type in which the center of component A is not coaxial with the center of component B, an islands-in-the-sea type containing component A as the sea component and component B as the island component, a side-by-side type containing components A and B lying side-by-side, a segmented pie type in which components A and B are alternately arranged in radial segments, and a multilobal type containing several portions of component B arranged around component A.
• the core-sheath type in which the component B occupies the entire surface of the fiber and which is excellent in spinnability.
• the average single fiber fineness of the PPS composite fiber of the present invention is preferably 0.5 to 10 dtex.
• the average single fiber fineness is 0.5 dtex or more, more preferably 1 dtex or more, further more preferably 2 dtex or more, the spinnability of the fiber is maintained and frequent breakage of the fiber during spinning is prevented.
• the average single fiber fineness is 10 dtex or less, more preferably 5 dtex or less, further more preferably 4 dtex or less, the amount of the extruded molten resin per spinneret hole is appropriately reduced so that the spun fibers are sufficiently cooled, thereby preventing the deterioration of spinnability caused by fusion of the fibers.
• the fiber with such average single fiber fineness can produce a nonwoven fabric not having varying mass per unit area but having excellent quality of the surface.
• the average single fiber fineness is preferably 10 dtex or less, more preferably 5 dtex or less, and further more preferably 4 dtex or less.
• the PPS composite fiber of the present invention can be produced as a multifilament yarn, a monofilament yarn or a staple yarn, and can also be used to produce any types of fabrics such as woven fabrics and nonwoven fabrics.
• the PPS composite fiber of the present invention is especially preferably used to produce a nonwoven fabric. This is because, in a nonwoven fabric, the PPS composite fibers thermally bonded to each other and thereby enhance the strength of the nonwoven fabric.
• nonwoven fabrics examples include needle punched nonwoven fabrics, wet-laid nonwoven fabrics, spun lace nonwoven fabrics, spunbonded nonwoven fabrics, meltblown nonwoven fabrics, resin-bonded nonwoven fabrics, chemical-bonded nonwoven fabrics, thermally bonded nonwoven fabrics, tow-opening nonwoven fabrics, and air-laid nonwoven fabrics.
• spunbonded nonwoven fabrics preferred are spunbonded nonwoven fabrics, which are excellent in productivity and mechanical strength.
• the nonwoven fabric made from the PPS composite fiber of the present invention exhibits a high mechanical strength after thermal bonding, and therefore the nonwoven fabric of the present invention is preferably produced by integrating the fibers by thermal bonding.
• the mass per unit area of the nonwoven fabric of the present invention is preferably 10 to 1,000 g/m 2 .
• the mass per unit area of the nonwoven fabric of the present invention is 10 g/m 2 or more, more preferably 100 g/m 2 or more, further more preferably 200 g/m 2 or more, the nonwoven fabric exhibits sufficient mechanical strength for practical use.
• the mass per unit area of the nonwoven fabric of the present invention is 1,000 g/m 2 or less, more preferably 700 g/m 2 or less, further more preferably 500 g/m 2 or less, the nonwoven fabric exhibits adequate breathability and thereby will not cause high pressure drop when used as a filter or the like.
• the product of strength and elongation per mass per unit area of the nonwoven fabric made from the thermally bondable composite fiber of the present invention is preferably 25 or more.
• Product of strenght and elongation per mass per unit area longitudinal tensile strength N / 5 cm ⁇ longitudinal tensile elongation % / mass per unit area g / m 2
• the nonwoven fabric When the product of strength and elongation per mass per unit area is 25 or more, more preferably 35 or more, further more preferably 40 or more, the nonwoven fabric has sufficient mechanical strength for use in severe environment.
• the upper limit of the product of strength and elongation per mass per unit area is not particularly defined, but the product of strength and elongation per mass per unit area of the nonwoven fabric of the present invention is preferably 100 or less so that the nonwoven fabric is not too hard to handle.
• the PPS composite fiber of the present invention can be produced by a conventional melt spinning process.
• a PPS resin as the core component and a PPS resin as the sheath component are melted in separate extruders, metered, fed to a spinneret for core-sheath composite spinning, and melt spun into continuous fibers.
• the fibers are cooled with a conventional cooling device that blows air laterally or circularly, an oil is applied to the fibers, and the fibers are taken up on a winder with a take-up roller to produce a core-sheath composite fiber as undrawn fibers.
• the wound undrawn fibers are drawn with a conventional drawing machine having a plurality of pairs of rollers at different circumferential speeds, crimped in a stuffer-box crimper or the like, and cut into a desired length with a cutter such as an EC cutter.
• the wound undrawn fibers are drawn with a drawing machine, taken up, and, if necessary, subjected to processing such as twisting and false twisting.
• a process for producing a composite-fiber nonwoven fabric by spunbonding process which is a preferred embodiment of the nonwoven fabric of the present invention, will be described below.
• Spunbonding process is a production process involving melting a resin, spinning continuous fibers from the molten resin by extruding it from a spinneret, cooling and solidifying the fibers, drawing and stretching the fibers with an ejector, collecting the fibers on a moving net to form a nonwoven web, and thermally bonding the web.
• the spinneret and the ejector may be in various shapes such as a circular shape and a rectangular shape. Inter alia, a combination of a rectangular spinneret and a rectangular ejector is preferred so that the amount of compressed air to be used is relatively small and the continuous fibers hardly fuse to each other or rub against each other.
• the spinning temperature for melting and spinning the resin is preferably 290 to 380°C, more preferably 295 to 360°C, further more preferably 300 to 340°C.
• the spinning temperature within the above range allows the resin to be in a stable molten state and to exhibit excellent spinning stability.
• Components A and B are melted in separate extruders, metered, and fed to a spinneret for composite spinning, and spun into composite fibers.
• Cooling of the spun continuous composite fibers may be performed by, for example, a method in which cold air is forced to blow over the continuous fibers, a method in which the continuous fibers are allowed to cool down at ambient temperature around the fibers, a method in which the distance between the spinneret and the ejector is adjusted, or a combined method thereof. Cooling conditions can be appropriately adjusted based on the discharge rate per spinneret hole, the spinning temperature, the ambient temperature, and the like.
• the continuous fibers solidified by cooling are drawn and stretched by compressed air ejected from the ejector.
• the methods and conditions for drawing and stretching the fibers by means of the ejector are not particularly limited, but preferred are methods that efficiently promote the crystallization of the PPS fibers, in particular, a method in which the fibers are drawn and stretched at a spinning rate of 3,000 m/min or more by compressed air that is heated to 100°C or higher and then ejected from the ejector, or a method in which the fibers are drawn and stretched at a spinning rate of not less than 5,000 m/min and less than 6,000 m/min by compressed air (at normal temperature) ejected from the ejector that is disposed so that the compressed air outlet of the ejector is 450 to 650 mm distant from the bottom of the spinneret.
• the drawn PPS composite fibers are collected on a moving net to form a nonwoven web, and the obtained nonwoven web is integrated by thermal bonding to form a nonwoven fabric.
• the thermal bonding can be performed by, for example, thermal pressure bonding using various types of rolls, such as a hot embossing roll pair of upper and lower rolls each having an embossed surface, a hot embossing roll pair of a roll having a flat (smooth) surface and a roll having an embossed surface, and a hot calendering roll pair of upper and lower flat (smooth) rolls; and through-air bonding involving passing hot air through a nonwoven web in the thickness direction thereof.
• thermal bonding using a hot embossing roll pair which improves the mechanical strength and allows the nonwoven fabric to retain adequate breathability.
• the emboss pattern on the embossing roll (s) may be circle, oval, square, rectangle, parallelogram, diamond, regular hexagon, regular octagon, or the like.
• the surface temperature of the hot embossing roll pair is preferably 150 to 5°C lower than the melting point of PPS.
• the surface temperature of the hot embossing roll pair is not lower than the temperature that is 150°C lower than the melting point of PPS, more preferably not lower than the temperature that is 100°C lower than the melting point of PPS, further more preferably not lower than the temperature that is 50°C lower than the melting point of PPS, the fibers are sufficiently thermally bonded and thereby flaking off and fluffing of the resulting nonwoven fabric are prevented.
• the surface temperature of the hot embossing roll pair is not higher than the temperature that is 5°C lower than the melting point of PPS, holes in the press-bonded parts due to melting of the fibers are prevented from being generated.
• the linear pressure applied by the hot embossing roll pair during thermal bonding is preferably 200 to 1500 N/cm.
• the linear pressure applied by the hot embossing roll pair is 200 N/cm or more, more preferably 300 N/cm or more, the fibers are sufficiently thermally bonded and thereby flaking off and fluffing of the resulting sheet is prevented.
• the linear pressure applied by the hot embossing roll pair is 1500 N/cm or less, more preferably 1000 N/cm or less, the raised portions of the embossing roll(s) are prevented from biting into the nonwoven fabric and thereby difficulty in removing the nonwoven fabric from the roll (s) and the breakage of the nonwoven fabric are prevented.
• the bonded area formed by the hot embossing roll pair is preferably 8 to 40%.
• the bonded area is 8% or more, more preferably 10% or more, further more preferably 12% or more, the resulting nonwoven fabric will have sufficient strength for practical use.
• the bonded area is 40% or less, more preferably 30% or less, further more preferably 20% or less, the resulting nonwoven fabric is prevented from being formed into a film-like fabric that hardly exhibits the advantages of a nonwoven fabric, such as breathability.
• the term "bonded area” herein refers to the ratio of the area of the nonwoven web in contact with both of the raised portions of the upper roll and the raised portions of the lower roll, relative to the total area of the nonwoven web.
• the term "bonded area” herein refers to the ratio of the area of the nonwoven web in contact with the raised portions of the roll having raised and recessed portions, relative to the total area of the nonwoven web.
• the nonwoven web before thermal bonding can be temporarily bonded under a linear pressure of 50 to 700 N/cm with calender rolls at 70 to 120°C.
• the calender rolls may be a combination of upper and lower metal rolls or of a metal roll with a resin or paper roll.
• the MFRs of the resins used were measured in accordance with ASTM D1238-70 under the conditions of a measurement temperature of 315.5°C and an applied load of 5 kg.
• the spinning rates V (m/min) were calculated based on the following formula using the average single fiber fineness F (dtex) and the discharge rate of the resin per spinneret hole D (hereinafter abbreviated to discharge rate per hole: g/min) under various settings.
• V 10000 ⁇ D / F
• Fibers were taken from the nonwoven web collected on a net and were embedded in a resin (a bisphenol epoxy resin, curing time: 24 hours).
• the embedded fibers were sectioned with a microtome to prepare a sample of a fiber cross section with a thickness of 2.0 ⁇ m.
• This sample was analyzed by laser Raman spectroscopy under the conditions described below. From the obtained Raman spectrum, the full width at half maximum of the phenyl ring-S stretching band (around 1080 cm -1 ) was determined.
• the full width at half maximum of the phenyl ring-S stretching band (around 1080 cm -1 ) in the Raman spectrum of PPS becomes smaller as crystallization proceeds with the increase in structural order and the equalization of the environment around the vibration. Based on this tendency, the determined value of the full width at half maximum was used to evaluate the crystallinity (a smaller full width at half maximum means a higher crystallinity).
• a 100 mol% linear polyphenylene sulfide resin (Toray Industries, Inc., product number: E2280, MFR: 160 g/10 min) was dried in nitrogen atmosphere at 160°C for 10 hours and used as component A.
• a 100 mol% linear polyphenylene sulfide resin (Toray Industries, Inc., product number: M2588, MFR: 300 g/10 min) was dried in nitrogen atmosphere at 160°C for 10 hours and used as component B.
• the component A was melted in an extruder for a core component, and the component B was melted in an extruder for a sheath component.
• the components A and B were metered to provide an A:B mass ratio of 80:20.
• the components were spun from a rectangular-shaped core-sheath spinneret with a hole diameter ( ⁇ ) of 0.55 mm at a discharge rate per hole of 1.37 g/min at a spinning temperature of 315°C to form continuous core-sheath composite fibers.
• the spun fibers were cooled and solidified in an atmosphere at a room temperature of 20°C, and were passed through a rectangular ejector disposed at a distance of 550 mm from the spinneret.
• the fibers were drawn and stretched by the air that was heated to 200°C with an air heater and ejected from the ejector at an ejector pressure of 0.17 MPa.
• the drawn fibers were collected on a moving net to form a nonwoven web.
• the obtained core-sheath composite long fibers had an average single fiber fineness of 2.9 dtex.
• the spinning rate was 4,797 m/min.
• the crystallinity was lower in the surface of the fibers than in the center of the cross section of the fibers. The occurrence of the breakage of the fibers during 1 hour spinning was zero and thus good spinnability was observed.
• the nonwoven web was then temporarily bonded under a linear pressure of 200 N/cm and at a temporary bonding temperature of 90°C using a pair of upper and lower metal calendering rolls installed in the production line.
• the nonwoven fabric was then thermally bonded under a linear pressure of 1000 N/cm and at a thermal bonding temperature of 200°C using an embossing roll pair which provided a 12% bonded area and which consisted of an upper metal roll having a polka-dot emboss pattern and a lower flat metal roll, to give a core-sheath composite long-fiber nonwoven fabric.
• the obtained core-sheath composite long-fiber nonwoven fabric had a mass per unit area of 260 g/m 2 , a product of strength and elongation per mass per unit area of 54 and thermal shrinkage rates of 0.1% in the longitudinal direction and 0.0% in the transverse direction.
• Core-sheath composite spinning and nonwoven web forming were performed in the same manner as in Example 1 except that the ejector pressure was 0.15 MPa.
• the obtained core-sheath composite long fibers had an average single fiber fineness of 3.2 dtex.
• the spinning rate was 4,317 m/min.
• the crystallinity was lower in the surface of the fibers than in the center of the cross section of the fibers. The occurrence of the breakage of the fibers during 1 hour spinning was zero and thus good spinnability was observed.
• the nonwoven web was temporarily and thermally bonded to give a core-sheath composite long-fiber nonwoven fabric in the same manner as in Example 1.
• the obtained core-sheath composite long-fiber nonwoven fabric had a mass per unit area of 260 g/m 2 , a product of strength and elongation per mass per unit area of 51, and thermal shrinkage rates of 0.1% in the longitudinal direction and 0.1% in the transverse direction.
• Core-sheath composite spinning and nonwoven web forming were performed in the same as in Example 1.
• the obtained core-sheath composite long fibers had an average single fiber fineness of 2.9 dtex.
• the spinning rate was 4, 797 m/min.
• the crystallinity was lower in the surface of the fibers than in the center of the cross section of the fibers. The occurrence of the breakage of the fibers during 1 hour spinning was zero and thus good spinnability was observed.
• the nonwoven web was temporarily and thermally bonded to give a core-sheath composite long-fiber nonwoven fabric in the same manner as in Example 1 except that the thermal bonding temperature was 140°C.
• the obtained core-sheath composite long-fiber nonwoven fabric had a mass per unit area of 260 g/m 2 , a product of strength and elongation per mass per unit area of 62 and thermal shrinkage rates of 0.1% in the longitudinal direction and 0.0% in the transverse direction.
• Core-sheath composite spinning and nonwoven web forming were performed in the same manner as in Example 1.
• the obtained core-sheath composite long fibers had an average single fiber fineness of 2.9 dtex.
• the spinning rate was 4,797 m/min.
• the crystallinity was lower in the surface of the fibers than in the center of the cross section of the fibers. The occurrence of the breakage of the fibers during 1 hour spinning was zero and thus good spinnability was observed.
• the nonwoven web was temporarily and thermally bonded to give a core-sheath composite long-fiber nonwoven fabric in the same manner as in Example 1 except that the thermal bonding temperature was 240°C.
• the obtained core-sheath composite long-fiber nonwoven fabric had a mass per unit area of 260 g/m 2 , a product of strength and elongation per mass per unit area of 50 and thermal shrinkage rates of 0.1% in the longitudinal direction and 0.1% in the transverse direction.
• Component B was not used.
• the component A was melted in an extruder, metered, and spun from a rectangular-shaped single-component spinneret with a hole diameter ( ⁇ ) of 0.50 mm at a discharge rate per hole of 1.37 g/min at a spinning temperature of 315°C.
• the spinning and nonwoven web forming were performed in the same manner as in Example 2.
• the obtained single-component long fibers had an average single fiber fineness of 2.4 dtex.
• the spinning rate was 4,920 m/min.
• the crystallinity was higher in the surface of the fibers than in the center of the cross section of the fibers. The occurrence of the breakage of the fibers during 1 hour spinning was zero and thus good spinnability was observed.
• the nonwoven web was temporarily and thermally bonded to give a single-component long-fiber nonwoven fabric in the same manner as in Example 1 except that the thermal bonding temperature of the embossing roll pair was 260°C.
• the obtained single-component long-fiber nonwoven fabric had a mass per unit area of 260 g/m 2 , a product of strength and elongation per mass per unit area of 4 and thermal shrinkage rates of 0.0% in the longitudinal direction and 0.1% in the transverse direction.
• Examples 1 to 4 in which the PPS of the sheath component had a lower viscosity than the PPS of the core component, had a lowered crystallinity on the surface of the fibers.
• the core-sheath composite long-fiber nonwoven fabrics made therefrom had greatly improved values of the product of strength and elongation per mass per unit area and more excellent mechanical strength, as compared with the single-component long-fiber nonwoven fabric of Comparative Example 1.
• the nonwoven fabric made from the thermally bondable composite fiber of the present invention has both thermal dimensional stability and excellent mechanical strength, and is therefore suitable for various industrial filters, electric insulating materials, battery separators, membrane materials for water treatment, heat insulating materials, hazmat suits, and the like.

Landscapes

• Engineering & Computer Science (AREA)
• Textile Engineering (AREA)
• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Nonwoven Fabrics (AREA)
• Multicomponent Fibers (AREA)

Applications Claiming Priority (3)

Publications (3)

Family

ID=50341430

Family Applications (1)

Country Status (6)

Families Citing this family (11)

Family Cites Families (22)

• 2013
  • 2013-09-18 WO PCT/JP2013/075134 patent/WO2014046120A1/ja active Application Filing
  • 2013-09-18 KR KR1020157002349A patent/KR102030381B1/ko active IP Right Grant
  • 2013-09-18 JP JP2014536871A patent/JP6102932B2/ja active Active
  • 2013-09-18 US US14/429,957 patent/US20150240390A1/en not_active Abandoned
  • 2013-09-18 EP EP13839069.5A patent/EP2899303B1/en not_active Not-in-force
  • 2013-09-18 CN CN201380048763.7A patent/CN104641027B/zh active Active

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events