Classifications

• • D—TEXTILES; PAPER
  • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
  • D06M—TREATMENT, NOT PROVIDED FOR ELSEWHERE IN CLASS D06, OF FIBRES, THREADS, YARNS, FABRICS, FEATHERS OR FIBROUS GOODS MADE FROM SUCH MATERIALS
  • D06M15/00—Treating fibres, threads, yarns, fabrics, or fibrous goods made from such materials, with macromolecular compounds; Such treatment combined with mechanical treatment
  • D06M15/19—Treating fibres, threads, yarns, fabrics, or fibrous goods made from such materials, with macromolecular compounds; Such treatment combined with mechanical treatment with synthetic macromolecular compounds
  • D06M15/21—Macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
  • D06M15/327—Macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds of unsaturated alcohols or esters thereof
  • D06M15/333—Macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds of unsaturated alcohols or esters thereof of vinyl acetate; Polyvinylalcohol
• • D—TEXTILES; PAPER
  • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
  • D06M—TREATMENT, NOT PROVIDED FOR ELSEWHERE IN CLASS D06, OF FIBRES, THREADS, YARNS, FABRICS, FEATHERS OR FIBROUS GOODS MADE FROM SUCH MATERIALS
  • D06M15/00—Treating fibres, threads, yarns, fabrics, or fibrous goods made from such materials, with macromolecular compounds; Such treatment combined with mechanical treatment
  • D06M15/19—Treating fibres, threads, yarns, fabrics, or fibrous goods made from such materials, with macromolecular compounds; Such treatment combined with mechanical treatment with synthetic macromolecular compounds
  • D06M15/37—Macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
  • D06M15/564—Polyureas, polyurethanes or other polymers having ureide or urethane links; Precondensation products forming them
• • D—TEXTILES; PAPER
  • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
  • D06N—WALL, FLOOR, OR LIKE COVERING MATERIALS, e.g. LINOLEUM, OILCLOTH, ARTIFICIAL LEATHER, ROOFING FELT, CONSISTING OF A FIBROUS WEB COATED WITH A LAYER OF MACROMOLECULAR MATERIAL; FLEXIBLE SHEET MATERIAL NOT OTHERWISE PROVIDED FOR
  • D06N3/00—Artificial leather, oilcloth or other material obtained by covering fibrous webs with macromolecular material, e.g. resins, rubber or derivatives thereof
  • D06N3/0002—Artificial leather, oilcloth or other material obtained by covering fibrous webs with macromolecular material, e.g. resins, rubber or derivatives thereof characterised by the substrate
  • D06N3/0004—Artificial leather, oilcloth or other material obtained by covering fibrous webs with macromolecular material, e.g. resins, rubber or derivatives thereof characterised by the substrate using ultra-fine two-component fibres, e.g. island/sea, or ultra-fine one component fibres (< 1 denier)
• • D—TEXTILES; PAPER
  • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
  • D06N—WALL, FLOOR, OR LIKE COVERING MATERIALS, e.g. LINOLEUM, OILCLOTH, ARTIFICIAL LEATHER, ROOFING FELT, CONSISTING OF A FIBROUS WEB COATED WITH A LAYER OF MACROMOLECULAR MATERIAL; FLEXIBLE SHEET MATERIAL NOT OTHERWISE PROVIDED FOR
  • D06N3/00—Artificial leather, oilcloth or other material obtained by covering fibrous webs with macromolecular material, e.g. resins, rubber or derivatives thereof
  • D06N3/12—Artificial leather, oilcloth or other material obtained by covering fibrous webs with macromolecular material, e.g. resins, rubber or derivatives thereof with macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds, e.g. gelatine proteins
  • D06N3/14—Artificial leather, oilcloth or other material obtained by covering fibrous webs with macromolecular material, e.g. resins, rubber or derivatives thereof with macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds, e.g. gelatine proteins with polyurethanes
• • D—TEXTILES; PAPER
  • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
  • D06N—WALL, FLOOR, OR LIKE COVERING MATERIALS, e.g. LINOLEUM, OILCLOTH, ARTIFICIAL LEATHER, ROOFING FELT, CONSISTING OF A FIBROUS WEB COATED WITH A LAYER OF MACROMOLECULAR MATERIAL; FLEXIBLE SHEET MATERIAL NOT OTHERWISE PROVIDED FOR
  • D06N2201/00—Chemical constitution of the fibres, threads or yarns
  • D06N2201/10—Conjugate fibres, e.g. core-sheath, side-by-side
• • D—TEXTILES; PAPER
  • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
  • D06N—WALL, FLOOR, OR LIKE COVERING MATERIALS, e.g. LINOLEUM, OILCLOTH, ARTIFICIAL LEATHER, ROOFING FELT, CONSISTING OF A FIBROUS WEB COATED WITH A LAYER OF MACROMOLECULAR MATERIAL; FLEXIBLE SHEET MATERIAL NOT OTHERWISE PROVIDED FOR
  • D06N2209/00—Properties of the materials
  • D06N2209/10—Properties of the materials having mechanical properties
  • D06N2209/103—Resistant to mechanical forces, e.g. shock, impact, puncture, flexion, shear, compression, tear
• • D—TEXTILES; PAPER
  • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
  • D06N—WALL, FLOOR, OR LIKE COVERING MATERIALS, e.g. LINOLEUM, OILCLOTH, ARTIFICIAL LEATHER, ROOFING FELT, CONSISTING OF A FIBROUS WEB COATED WITH A LAYER OF MACROMOLECULAR MATERIAL; FLEXIBLE SHEET MATERIAL NOT OTHERWISE PROVIDED FOR
  • D06N2209/00—Properties of the materials
  • D06N2209/10—Properties of the materials having mechanical properties
  • D06N2209/105—Resistant to abrasion, scratch
• • D—TEXTILES; PAPER
  • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
  • D06N—WALL, FLOOR, OR LIKE COVERING MATERIALS, e.g. LINOLEUM, OILCLOTH, ARTIFICIAL LEATHER, ROOFING FELT, CONSISTING OF A FIBROUS WEB COATED WITH A LAYER OF MACROMOLECULAR MATERIAL; FLEXIBLE SHEET MATERIAL NOT OTHERWISE PROVIDED FOR
  • D06N2211/00—Specially adapted uses
  • D06N2211/10—Clothing
• • D—TEXTILES; PAPER
  • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
  • D06N—WALL, FLOOR, OR LIKE COVERING MATERIALS, e.g. LINOLEUM, OILCLOTH, ARTIFICIAL LEATHER, ROOFING FELT, CONSISTING OF A FIBROUS WEB COATED WITH A LAYER OF MACROMOLECULAR MATERIAL; FLEXIBLE SHEET MATERIAL NOT OTHERWISE PROVIDED FOR
  • D06N2211/00—Specially adapted uses
  • D06N2211/12—Decorative or sun protection articles
  • D06N2211/14—Furniture, upholstery
• • D—TEXTILES; PAPER
  • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
  • D06N—WALL, FLOOR, OR LIKE COVERING MATERIALS, e.g. LINOLEUM, OILCLOTH, ARTIFICIAL LEATHER, ROOFING FELT, CONSISTING OF A FIBROUS WEB COATED WITH A LAYER OF MACROMOLECULAR MATERIAL; FLEXIBLE SHEET MATERIAL NOT OTHERWISE PROVIDED FOR
  • D06N2211/00—Specially adapted uses
  • D06N2211/12—Decorative or sun protection articles
  • D06N2211/26—Vehicles, transportation
• • D—TEXTILES; PAPER
  • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
  • D06N—WALL, FLOOR, OR LIKE COVERING MATERIALS, e.g. LINOLEUM, OILCLOTH, ARTIFICIAL LEATHER, ROOFING FELT, CONSISTING OF A FIBROUS WEB COATED WITH A LAYER OF MACROMOLECULAR MATERIAL; FLEXIBLE SHEET MATERIAL NOT OTHERWISE PROVIDED FOR
  • D06N2211/00—Specially adapted uses
  • D06N2211/12—Decorative or sun protection articles
  • D06N2211/28—Artificial leather
• • 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
  • Y10T428/26—Web or sheet containing structurally defined element or component, the element or component having a specified physical dimension
  • Y10T428/268—Monolayer with structurally defined element

Definitions

• the present invention relates to a sheet-shaped material having both good softness and a high-quality appearance and exhibiting a good abrasion resistance, the sheet-shaped material being produced by using a waterborne polyurethane as a binder resin to reduce the amount of organic solvents used in the production process and thereby to reduce the burden on the environment; and also relates to a process for producing the sheet-shaped material.
• Sheet-shaped materials comprised primarily of a fibrous substrate and polyurethane have excellent characteristics that cannot be found in natural leather, and are widely used in various applications. Among them, leather-like sheet-shaped materials using a polyester fibrous substrate have excellent light resistance, and thus have been increasingly applied to clothing, chair upholstery, automobile interior materials and others.
• Such sheet-shaped materials are typically produced by a wet coagulation process involving impregnating a fibrous substrate with a polyurethane solution in an organic solvent and then immersing the resulting fibrous substrate in a solvent that does not dissolve the polyurethane (i.e., water or a mixed solution of an organic solvent and water) to coagulate the polyurethane.
• a solvent that does not dissolve the polyurethane i.e., water or a mixed solution of an organic solvent and water
• the organic solvent used to dissolve the polyurethane is a water-miscible organic solvent such as N,N-dimethylformamide (hereinafter, also called “DMF”).
• Patent Literature 2 employs particular strategies in (i) the step of ultra-fining fibers with an aqueous alkaline solution and (ii) the step of impregnating a waterborne polyurethane.
• the dissolution of the PVA is inhibited by the addition of borax to the aqueous alkaline solution
• the dissolution of the PVA in water is inhibited by using a PVA having a degree of saponification of 98% and a degree of polymerization of 500.
• the effect of the addition of borax in the step of ultra-fining fibers is limited because the duration of the immersion in the aqueous alkaline solution should be long enough to ultra-fine fibers.
• the addition of borax to the aqueous alkaline solution cannot completely prevent the dissolution of the PVA in water.
• the degree of polymerization of the PVA is too low to completely prevent the dissolution of the PVA in water.
• the dissolution of the PVA in the waterborne polyurethane dispersion cannot be prevented, and the PVA dissolved in the waterborne polyurethane dispersion becomes an obstacle to stable control over the adhesion of the polyurethane to the fibers, resulting in a sheet-shaped material having a hard texture.
• Patent Literature 1 JP 2002-30579 A
• Patent Literature 2 JP 2003-096676 A
• Patent Literature 3 JP patent No. 4644971
• An object of the present invention is to provide a process for producing a sheet-shaped material having both an elegant, napped appearance and a soft texture and exhibiting a good abrasion resistance, the process using a reduced amount of organic solvents, thereby reducing the burden on the environment; and a sheet-shaped material produced by the production process.
• the process according to an aspect of the present invention for producing a sheet-shaped material comprises the successive steps of:
• the process comprises the step of preparing a polyvinyl alcohol aqueous solution in which the concentrations of methyl acetate, acetic acid and methanol are 0.1 to 50 ppm.
• the step of generating the microfibers is performed by treatment with an alkaline aqueous solution.
• the process further comprises the step of performing heating at 80 to 170° C. after the addition of the polyvinyl alcohol.
• the fibrous substrate comprising microfiber-generating fibers as its main constituent is integrated with a woven fabric and/or a knitted fabric by entanglement.
• a resulting sheet-shaped material preferably has a density of 0.2 to 0.7 g/cm 3 .
• the production process of the present invention is environmentally friendly and yet provides a sheet-shaped material having both an elegant appearance and a soft texture, which qualities the conventional art could not achieved concurrently, and also exhibiting a good abrasion resistance.
• the process according to an aspect of the present invention for producing a sheet-shaped material comprises the successive steps of:
• a preferred feature of the process of the present invention for producing a sheet-shaped material is that the steps (i) to (v) are performed in the above order. That is, the following steps are successively performed: adding an aqueous solution of a polyvinyl alcohol (also called PVA) having a degree of saponification of 98% or more and a degree of polymerization of 800 to 3500 to a fibrous substrate comprising microfiber-generating fibers as its main constituent, generating microfibers from the microfiber-generating fibers (the removal of a sea component), adding a waterborne polyurethane dispersion to the fibrous substrate comprising the microfibers as its main constituent and having the added PVA, and removing the PVA from the fibrous substrate.
• PVA polyvinyl alcohol
• the resulting product has an elegant appearance and soft texture and exhibits good physical properties such as a good abrasion resistance.
• the PVA in water migrates along with the migration of the water toward the surface and the PVA concentrates in the surface region of the fibrous substrate (migration phenomenon).
• migration phenomenon a large amount of the PVA adheres to the surface region of the fibrous substrate and a small amount of the PVA adheres to the inside.
• Such migration of the PVA allows the waterborne polyurethane to be added later to mainly adhere to the inside of the fibrous substrate.
• large voids are formed between the fibers and the polyurethane in the surface region, where a large amount of the PVA once adhered.
• the sheet-shaped material with such voids, after napping treatment, can give an elegant appearance with a napped surface on which the raised fibers are not bundled but uniformly separated.
• voids derived by the removal of the EVA and voids derived by the removal of the sea component are formed between the polyurethane and the microfibers. These voids further efficiently reduces the area where the microfibers are in direct contact with and held by the polyurethane. As a result, the texture of the resulting sheet-shaped material is soft, but the physical properties such as abrasion resistance tend to be deteriorated.
• the step (i) of dissolving, in water, a EVA having a degree of saponification of 98% or more and a degree of polymerization of 800 to 3500 to prepare a PVA aqueous solution in which the concentrations of methyl acetate, acetic acid and methanol are 50 ppm or less will be described below.
• Methyl acetate, acetic acid and methanol are generated as the degree of saponification increases during the saponification of polyvinyl acetate, which is a precursor used in the synthesis of a PVA. Methyl acetate, acetic acid and methanol are also generated by the decomposition of the residual polyvinyl acetate that has not undergone sufficient saponification.
• the concentrations of methyl acetate, acetic acid and methanol in the PVA aqueous solution are 50 ppm or less, the formation of the intermolecular hydrogen bonds in the PVA is facilitated at the time of heat-drying, and thereby the dissolution of the PVA in water (including hot water), an acid aqueous solution, or an alkaline aqueous solution is inhibited.
• the facilitated formation of the intermolecular hydrogen bonds in the PVA also allows the heat-drying temperature to be set at a relatively low level, for example, at 80 to 140° C., and thereby the thermal decomposition of the PVA is inhibited.
• the concentrations of methyl acetate, acetic acid and methanol in the PVA aqueous solution are more preferably 0.1 to 50 ppm.
• concentrations of methyl acetate, acetic acid and methanol are present in such small quantities, they are weakly bonded to the PVA molecules via hydrogen bonding and thereby decreases the intermolecular distance in the PVA, and as a result, the formation of the intermolecular hydrogen bonds in the PVA is facilitated. Too high concentrations of methyl acetate, acetic acid and methanol inhibit the formation of the intermolecular hydrogen bonds in the PVA, and therefore the concentrations are more preferably 0.3 to 40 ppm, even more preferably 5 to 40 ppm.
• the concentrations of methyl acetate, acetic acid and methanol in the PVA aqueous solution are analyzed as follows.
• a 24-mL test tube or flask for heating is placed 1 g of a PVA aqueous solution, and the solution is heated at 90° C. for 1 hour.
• the generated gas in an amount of 0.1 mL is taken with a gas-tight syringe from the test tube or flask for heating.
• the gas is introduced into a GC/MS (a mass spectrometer directly connected to a gas chromatograph), and the concentrations are analyzed.
• the above-described low concentrations of methyl acetate, acetic acid and methanol in the PVA aqueous solution can be achieved by either using a PVA that generates small amounts of methyl acetate, acetic acid and methanol when heated alone without the addition of water, or by prolonging the length of time for heating to rise the temperature at the time of dissolving a PVA in water for preparing the PVA aqueous solution.
• a higher degree of saponification leads to the generation of smaller amounts of methyl acetate, acetic acid and methanol. Therefore, preferred is a PVA with a high degree of saponification, as high as 98% or more.
• the temperature to which the PVA in water is heated is preferably 80 to 100° C.
• the heating time is preferably 1 hour or more. The methyl acetate, acetic acid and methanol may be completely removed from the PVA aqueous solution.
• the PVA to be added to the fibrous substrate has a degree of saponification of 98% or more and a degree of polymerization of 800 to 3500.
• the degree of saponification of the PVA is 98% or more, the PVA does not dissolved away in the waterborne polyurethane dispersion during the addition of the waterborne polyurethane. If the PVA is dissolved away in the waterborne polyurethane dispersion, the PVA cannot exhibit a sufficient effect of protecting the surface of the nap-forming microfibers.
• a waterborne polyurethane dispersion in which the PVA has been dissolved is added to the fibrous substrate, the PVA is incorporated into the polyurethane and the PVA then becomes difficult to be removed. Consequently, the adhesion between the polyurethane and the fibers cannot be stably controlled, resulting in a hard texture.
• the solubility of a PVA in water varies with its degree of polymerization.
• a smaller degree of polymerization of the PVA leads to a larger amount of the PVA dissolved away in the waterborne polyurethane dispersion during the addition of the waterborne polyurethane.
• a higher degree of polymerization of the PVA leads to a higher viscosity of an aqueous solution of the PVA.
• the degree of polymerization of the PVA is preferably 1000 to 3000, more preferably 1200 to 2500.
• the viscosity of an aqueous solution of 4% by mass of the PVA at 20° C. is preferably 10 to 70 mPa ⁇ s.
• the viscosity of the PVA aqueous solution is within this range, an appropriate migration structure is formed in the fibrous substrate at the time of the drying, and the resulting sheet-shaped material will exhibit balanced physical properties including softness, surface appearance, and abrasion resistance.
• the viscosity is 10 mPa ⁇ s or more, more preferably 15 mPa ⁇ s or more, formation of an excessive migration structure can be prevented.
• the viscosity is 70 mPa ⁇ s or less, more preferably 50 mPa ⁇ s or less, even more preferably 40 mPa ⁇ s or less, the PVA readily infiltrates the fibrous substrate.
• the glass transition temperature (Tg) of the PVA is preferably 70 to 100° C.
• the glass transition temperature of the PVA is 70° C. or higher, more preferably 75° C. or higher, the softening of the PVA during the drying step is prevented, and the fibrous substrate thereby can maintain dimensional stability and the resulting sheet-shaped material will not have a poor surface appearance.
• the glass transition temperature is 100° C. or lower, more preferably 95° C. or lower, the fibrous substrate is prevented from becoming excessively hard and difficult to handle.
• the melting point of the PVA is preferably 200 to 250° C.
• the melting point of the PVA is 200° C. or higher, more preferably 210° C. or higher, the softening of the PVA during the drying step is prevented, and thereby the fibrous substrate can maintain dimensional stability and the resulting sheet-shaped material will not have a poor surface appearance.
• the melting point of the PVA is 250° C. or lower, more preferably 240° C. or lower, the fibrous substrate is prevented from becoming excessively hard and difficult to handle.
• the tensile strength of the PVA in the form of a film is preferably 400 to 800 kg/cm 2 .
• the tensile strength of the PVA film is 400 kg/cm 2 or more, more preferably 450 kg/cm 2 or more, deformation of the fibrous substrate during handling is prevented, and the resulting sheet-shaped material will not have a poor surface appearance.
• the tensile strength of the PVA film is 800 kg/cm 2 or less, more preferably 750 kg/cm 2 or less, the sheet having the added PVA is prevented from becoming excessively hard, and thereby the formation of wrinkles by buckling or other defects during handling is prevented.
• the tensile strength herein is determined using a film of the PVA with a thickness of 100 ⁇ m at a temperature of 20° C. and a humidity of 65%.
• the step (ii) of adding the PVA aqueous solution to a fibrous substrate comprising microfiber-generating fibers as its main constituent, so that the fibrous substrate has the polyvinyl alcohol in an amount of 0.1 to 50% by mass based on the mass of the fibers contained in the fibrous substrate will be described below.
• the fibrous substrate in the present invention typically comprises microfiber-generating fibers as its main constituent.
• the microfiber-generating fibers are used to generate microfibers through the step of ultra-fining the microfiber-generating fibers, and the generated microfibers provide an elegant appearance on the surface of the sheet-shaped material.
• the average single fiber diameter of the microfibers generated from the microfiber-generating fibers through the step of ultra-fining is 0.3 to 7 ⁇ m.
• the average single fiber diameter is 7 ⁇ m or less, more preferably 6 ⁇ m or less, even more preferably 5 ⁇ m or less, the resulting sheet-shaped material will have excellent softness and an excellent nap quality.
• the resulting sheet-shaped material When the average single fiber diameter is 0.3 ⁇ m or more, more preferably 0.7 ⁇ m or more, even more preferably 1 ⁇ m or more, the resulting sheet-shaped material will exhibit an excellent chromogenic property for dyeing, an excellent separability of fibers aggregated into bundles during napping treatment by, for example, grinding with a sandpaper or the like, and an excellent loosening property of fibers.
• the microfiber-generating fibers may be (a) islands-in-the-sea fibers, which are prepared using two types of thermoplastic resins having different solvent solubilities as the sea and island components and which can generate microfibers from the island component through the dissolution and removal of the sea component with a solvent or the like; or (b) splitting composite fibers, which are prepared by alternately arranging two types of thermoplastic resins in radial segments or multi-layered segments in the cross-section and which can generate microfibers through splitting the fibers by peeling and separating the segments.
• the islands-in-the-sea fibers can give voids in an appropriate size between the island components, i.e., between the microfibers, through the removal of the sea component, and thus are preferred for achieving softness and good texture of the sheet-shaped material.
• the islands-in-the-sea fibers include islands-in-the-sea composite fibers, which are prepared by spinning two types of alternately aligned components (sea and island components) from a spinneret for islands-in-the-sea composite spinning; and blended-spun fibers, which are prepared by blending two types of components (sea and island components) and spinning them into fibers.
• islands-in-the-sea composite fibers because the fibers can generate microfibers having uniform fineness and sufficient length, which sufficient length contributes to the strength of the sheet-shaped material.
• the island component of the islands-in-the-sea fibers is not particularly limited and may be a thermoplastic resin capable of being subjected to melt spinning, including polyesters such as polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate, and polylactic acid; polyamides such as 6-nylon and 66-nylon; acrylics; polyethylenes; polypropylenes; and thermoplastic celluloses.
• polyester fibers are preferred because of their strength, dimensional stability, and light resistance. Due to environmental concerns, the fibers are preferably made from recycled materials or plant-derived materials.
• the fibrous substrate may comprise mixed fibers made from different materials.
• the sea component of the islands-in-the-sea fibers is not particularly limited, and may be, for example, polyethylenes; polypropylenes; polystyrenes; copolymerized polyesters prepared by copolymerizing sodium sulfoisophthalate, polyethylene glycol, or the like, and polylactic acid; or PVAs.
• PVAs polylactic acid
• copolymerized polyesters prepared by copolymerizing sodium sulfoisophthalate, polyethylene glycol, or the like, and polylactic acid because these polymers are alkali-degradable and can be degraded without any organic solvent.
• a PVA because it is soluble in hot water.
• the cross-sectional shape of the fibers constituting the fibrous substrate is not particularly limited, and may be a circular shape, an oval shape, a flat shape, a polygonal shape such as a triangular shape, or a modified cross-sectional shape such as fan and cross shapes.
• the average single fiber diameter of the fibers constituting the fibrous substrate is preferably 0.3 to 20 ⁇ m.
• a smaller value of the average single fiber diameter results in a sheet-shaped material having more excellent softness and a more excellent nap quality.
• a larger value of the average single fiber diameter results in a sheet-shaped material exhibiting a more excellent chromogenic property for dyeing, a more excellent separability of fibers aggregated into bundles during napping treatment by, for example, grinding with a sandpaper or the like, and a more excellent loosening property of fibers.
• the average single fiber diameter is thus more preferably 0.7 to 15 ⁇ m and particularly preferably 1 to 7 ⁇ m.
• the fibrous substrate in the present invention may be a woven fabric, a knitted fabric, a nonwoven fabric, or the like.
• a nonwoven fabric because it gives a sheet-shaped material having a good surface appearance after napping treatment on the surface.
• the nonwoven fabric may be a staple nonwoven fabric or a filament nonwoven fabric.
• a filament nonwoven fabric has a smaller amount of fibers which lie in the thickness direction of a resulting sheet-shaped material and which is to form a nap by napping, as compared with a staple nonwoven fabric.
• a filament nonwoven fabric thus tends to give a less dense nap, resulting in a poor surface appearance. Therefore preferred is a staple nonwoven fabric.
• the fiber length of the staples in the staple nonwoven fabric is preferably 25 to 90 mm.
• the fibers can be entangled to yield a sheet-shaped material having an excellent abrasion resistance.
• the fiber length is 90 mm or less, the fibers can yield a sheet-shaped material having excellent texture and quality.
• the fiber length is more preferably 30 to 80 mm.
• the method for entangling the fibers or fiber bundles to yield a nonwoven fabric may be needle punching or water-jet punching.
• a preferred embodiment of the nonwoven fabric is a nonwoven fabric having a structure in which bundles of microfibers (microfiber bundles) are entangled.
• the entangled bundles of microfibers improve the strength of the sheet-shaped material.
• Such a nonwoven fabric can be obtained by entangling microfiber-generating fibers and then generating microfibers therefrom.
• a woven fabric or a knitted fabric may be integrated inside the nonwoven fabric by entanglement for the purpose of improving the strength and other properties.
• the woven fabric include plain woven fabrics, twill woven fabrics, and satin woven fabrics, and preferred is plain woven fabrics in view of the cost.
• the knitted fabric include circular knitted fabrics, tricot fabrics, and raschel fabrics. The fibers constituting such woven and knitted fabrics preferably have an average single fiber diameter of 0.3 to 20 ⁇ m.
• the addition of the PVA reduces the area where the woven fabric and/or the knitted fabric is in direct contact with and held by the waterborne polyurethane that is to be added later, thereby softening the texture of the resulting sheet-shaped material.
• This softening effect is significant especially in cases where the woven fabric and/or the knitted fabric is made of fibers other than microfiber-generating fibers.
• the amount of the PVA to be added to the fibrous substrate is 0.1 to 50% by mass and preferably 1 to 45% by mass based on the total mass of the fibers in the fibrous substrate.
• the amount of the PVA to be added is 0.1% by mass or more, the resulting sheet-shaped material has good softness and texture.
• the amount of the PVA to be added is 50% by mass or less, the resulting sheet-shaped material has good processability and good physical properties including abrasion resistance.
• the method for adding the PVA to the fibrous substrate is not particularly limited, and may be any method commonly used in the art.
• Preferred is a method involving dissolving the PVA in water, impregnating the fibrous substrate with the PVA solution, and heat-drying the substrate, so that the PVA can be uniformly added. If the drying temperature is too low, a longer drying time is required. On the other hand, if the drying temperature is too high, the PVA becomes completely insoluble and cannot be dissolved and removed later.
• the drying temperature is preferably 80 to 140° C., and more preferably 110 to 130° C.
• the drying time is usually 1 to 20 minutes, and is preferably 1 to 10 minutes and more preferably 1 to 5 minutes in view of the processability.
• heat treatment may be performed after the drying.
• the heating treatment is preferably performed at 80 to 170° C.
• the heating temperature is more preferably 80° C. to 140° C.
• step (iii) of generating microfibers having an average single fiber diameter of 0.3 to 7 ⁇ m from the microfiber-generating fibers contained in the fibrous substrate as its main constituent will be described below.
• the ultra-fining treatment (the removal of the sea component) of the fibrous substrate comprising microfiber-generating fibers as its main constituent can be performed by immersing the fibrous substrate in a solvent and wringing out the solvent.
• the solvent for dissolving the sea component may be an organic solvent such as toluene and trichloroethylene.
• the solvent may be an aqueous solution of alkali such as sodium hydroxide.
• the solvent may be hot water. Due to environmental concerns regarding the process, the removal of the sea component is preferably performed with an aqueous solution of alkali such as sodium hydroxide or with hot water.
• step (iv) of adding a waterborne polyurethane to the fibrous substrate comprising the microfibers as its main constituent and having the added PVA will be described below.
• the waterborne polyurethane includes (I) forcibly emulsified polyurethanes, which have been forced to be stably dispersed in water with use of a surfactant, and (II) self-emulsifying polyurethanes, which have hydrophilic structures in their molecular structures and are capable of being dispersed and then stabilized in water without use of any surfactant. Both types of polyurethanes can be used in the present invention.
• the method for adding the waterborne polyurethane to the fibrous substrate is not particularly limited, but preferred is a method in which the waterborne polyurethane is impregnated into or applied to the fibrous substrate, then coagulated and heat-dried, because the waterborne polyurethane is uniformly added by this method.
• the concentration of the waterborne polyurethane dispersion (the amount of the polyurethane contained in the waterborne polyurethane dispersion) is preferably 10 to 50% by mass and more preferably 15 to 40% by mass in view of storage stability of the waterborne polyurethane dispersion.
• the waterborne polyurethane dispersion used in the present invention may contain a water-soluble organic solvent in an amount of 40% by mass or less based on the total amount of the polyurethane dispersion for the purpose of improving the storage stability of the polyurethane dispersion and the productivity of the sheet.
• the amount of the organic solvent is preferably 1% by mass or less in view of the environmental safety at the production site for the sheet, and the like.
• the waterborne polyurethane dispersion used in the present invention preferably has a heat-sensitive coagulation property.
• the polyurethane can be added uniformly in the thickness direction of the fibrous substrate.
• heat-sensitive coagulation property refers to a property that, when the polyurethane dispersion is heated and reaches a certain temperature (heat-sensitive coagulation temperature), reduces the flowability of the polyurethane dispersion and then coagulates the polyurethane.
• the waterborne polyurethane is added to the fibrous substrate, then coagulated by dry coagulation, wet-heat coagulation, wet coagulation, or any combination thereof, and dried to give the fibrous substrate having the added polyurethane.
• a realistic method for coagulating a waterborne polyurethane not exhibiting a heat-sensitive coagulation property is dry coagulation.
• the polyurethane tends to migrate toward and concentrate in the surface region of the fibrous substrate and then to harden the texture of the resulting sheet-shaped material having the polyurethane added.
• Such migration can be prevented by adjusting the viscosity of the waterborne polyurethane dispersion by the addition of a thickener.
• the migration can be prevented by the addition of a thickener before the subsequent dry coagulation.
• the heat-sensitive coagulation temperature of the waterborne polyurethane in the present invention is preferably 40 to 90° C.
• the heat-sensitive coagulation temperature is 40° C. or higher, the polyurethane dispersion has good storage stability and the adhesion of the polyurethane to the machines during operation is prevented.
• the heat-sensitive coagulation temperature is 90° C. or lower, the migration of the polyurethane toward the surface of the fibrous substrate is prevented.
• a heat-sensitive coagulant may be added to the polyurethane dispersion, as appropriate.
• the heat-sensitive coagulant include inorganic salts such as sodium sulfate, magnesium sulfate, calcium sulfate, and calcium chloride; and radical initiators such as sodium persulfate, potassium persulfate, ammonium persulfate, azobisisobutyronitrile, and benzoyl peroxide.
• the polyurethane dispersion can be added to the fibrous substrate by impregnation, application, or other methods, and the polyurethane can be coagulated by dry coagulation, wet-heat coagulation, wet coagulation, or any combination thereof.
• the temperature for the wet-heat coagulation is preferably equal to or higher than the heat-sensitive coagulation temperature of the polyurethane and is preferably 40 to 200° C.
• the temperature for the wet-heat coagulation is 40° C. or higher, more preferably 80° C. or higher, the polyurethane can coagulate in a shorter period of time and the migration phenomenon is more efficiently prevented.
• the temperature for the wet-heat coagulation is 200° C. or lower, more preferably 160° C. or lower, thermal degradation of the polyurethane and of the PVA is prevented.
• the temperature for the wet coagulation is preferably equal to or higher than the heat-sensitive coagulation temperature of the polyurethane and is preferably 40 to 100° C.
• the temperature for the wet coagulation in hot water is 40° C. or higher, more preferably 80° C. or higher, the polyurethane can coagulate in a shorter period of time and the migration phenomenon is more efficiently prevented.
• the temperature for the dry coagulation and the drying temperature are preferably 80 to 140° C.
• the temperature for the dry coagulation and the drying temperature are 80° C. or higher, more preferably 90° C. or higher, the productivity is excellent.
• the temperature for the dry coagulation and the drying temperature are 140° C. or lower, more preferably 130° C. or lower, thermal degradation of the polyurethane and of the PVA is prevented.
• the polyurethane after being subjected to the coagulation, may be subjected to heat treatment.
• the heat treatment reduces the number of the interfaces between the polyurethane molecules, thereby strengthening the polyurethane.
• the heat treatment is preferably performed after removing the PVA from a sheet having the waterborne polyurethane added.
• the temperature for the heat treatment is preferably 80 to 170° C.
• the polyurethane used in the present invention is preferably obtained by reaction of a polymer diol and an organic diisocyanate with a chain extender.
• polymer diol examples include, but are not particularly limited to, polycarbonate diols, polyester diols, polyether diols, silicone diols, and fluorine diols, and copolymers obtained by combining them.
• polycarbonate diols and polyether diols preferred are polycarbonate diols and polyether diols.
• polycarbonate diols and polyester diols preferred are preferred.
• polycarbonate dials and polyester diols more preferred are polycarbonate dials and polyester diols, and particularly preferred are polycarbonate diols.
• the polycarbonate diols can be produced by, for example, transesterification of an alkylene glycol and a carbonate or reaction of phosgene or a chloroformate with an alkylene glycol.
• alkylene glycol examples include, but are not particularly limited to, linear alkylene glycols such as ethylene glycol, propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,9-nonanediol, and 1,10-decanediol; branched alkylene glycols such as neopentyl glycol, 3-methyl-1,5-pentanediol, 2,4-diethyl-1,5-pentanediol, and 2-methyl-1,8-octanediol; alicyclic diols such as 1,4-cyclohexanediol; aromatic dials such as bisphenol A; glycerin; trimethylolpropane; and pentaerythritol.
• the polycarbonate diol may be either a polycarbonate diol obtained from a single type of alkylene
• polyester diols are exemplified by polyester diols obtained by condensation of various low molecular weight polyols and polybasic acids.
• low molecular weight polyols examples include, but are not particularly limited to, ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,3-butanediol, 1,4-butanediol, 2,2-dimethyl-1,3-propanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 1,8-octanediol, diethylene glycol, triethylene glycol, dipropylene glycol, tripropylene glycol, cyclohexane-1,4-diol, and cyclohexane-1,4-dimethanol. These polyols may be used singly or in combination of two or more of them. Adducts prepared by adding various alkylene oxides to bisphenol A are also usable.
• polybasic acids examples include, but are not particularly limited to, succinic acid, maleic acid, adipic acid, glutaric acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, phthalic acid, isophthalic acid, terephthalic acid, and hexahydroisophthalic acid. These acids may be used singly or in combination of two or more of them.
• polyether diols examples include, but are not particularly limited to, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and copolymerized diols obtained by combining them.
• the number average molecular weight of the polymer diol used in the present invention is preferably 500 to 4000.
• the number average molecular weight is 500 or more, more preferably 1500 or more, the texture of the sheet-shaped material is prevented from becoming excessively hard.
• the number average molecular weight is 4000 or less, more preferably 3000 or less, the polyurethane can maintain its strength.
• organic diisocyanate examples include, but are not particularly limited to, aliphatic diisocyanates such as hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, isophorone diisocyanate, and xylylene diisocyanate; and aromatic diisocyanates such as diphenylmethane diisocyanate and tolylene diisocyanate.
• aliphatic diisocyanates such as hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, and isophorone diisocyanate.
• chain extender examples include, but are not particularly limited to, amine chain extenders such as ethylenediamine and methylenebisaniline; and diol chain extenders such as ethylene glycol.
• amine chain extenders such as ethylenediamine and methylenebisaniline
• diol chain extenders such as ethylene glycol.
• Polyamines prepared by reacting a polyisocyanate with water may also be used as the chain extender.
• the polyurethane may be used in combination with a crosslinking agent for the purpose of improving water resistance, abrasion resistance, hydrolysis resistance, and other characteristics.
• the crosslinking agent may be an external crosslinking agent, which is added to the polyurethane as a third component, or an internal crosslinking agent, which previously introduces reaction points into the molecular structure of the polyurethane to form crosslinked structure.
• an internal crosslinking agent is preferred because it can form crosslinking points uniformly throughout the molecular structure of the polyurethane and alleviates the reduction in softness.
• the crosslinking agent may be a compound having an isocyanate group, an oxazoline group, a carbodiimide group, an epoxy group, a melamine resin, a silanol group, or the like. Excessive crosslinking tends to harden the polyurethane, resulting in a sheet-shaped material with a hard texture. Therefore preferred is a crosslinking agent having a silanol group in view of the balance between reactivity and softness.
• the polyurethane used in the present invention preferably has a hydrophilic group in its molecular structure.
• a hydrophilic group exists in the molecular structure of the polyurethane, the polyurethane, when dispersed in water, will have higher dispersibility and stability.
• the hydrophilic group may be any hydrophilic group including cationic groups such as quaternary amine groups; anionic groups such as a sulfonate group and a carboxylate group; nonionic groups such as a polyethylene glycol group; combinations of a cationic group and a nonionic group; and combinations of an anionic group and a nonionic group.
• cationic groups such as quaternary amine groups
• anionic groups such as a sulfonate group and a carboxylate group
• nonionic groups such as a polyethylene glycol group
• combinations of a cationic group and a nonionic group and combinations of an anionic group and a nonionic group.
• particularly preferred are the nonionic hydrophilic groups, which are free from concerns of yellowing by light or harmful effects by a neutralizer.
• a neutralizer is required.
• the neutralizer used is a tertiary amine such as ammonia, triethylamine, triethanolamine, triisopropanolamine, trimethylamine, and dimethylethanolamine
• the amine is volatilized by heating during the sheet production or drying and is released outside the system.
• a device for recovering the volatilized amine is required to be installed. If the amine is not volatilized by the heating but remains in a sheet-shaped material as the end product, the amine may be released in the environment when, for example, the product is burned.
• the polyurethane having a nonionic hydrophilic group is preferred.
• the neutralizer for the anionic hydrophilic group is required and the neutralizer is a hydroxide of an alkali metal or an alkaline earth metal, such as sodium hydroxide, potassium hydroxide, and calcium hydroxide
• the polyurethane wetted with water shows a shift to alkaline pH.
• the polyurethane having a nonionic hydrophilic group requires no neutralizer, there is no need for concerns about the deterioration of the polyurethane by hydrolysis.
• the waterborne polyurethane used in the present invention may contain various additives, including pigments such as carbon black; flame retardants such as phosphoric flame retardants, halogen flame retardants, silicone flame retardants, and inorganic flame retardants; antioxidants such as phenol antioxidants, sulfur-containing antioxidants, and phosphorus-containing antioxidants; ultraviolet absorbers such as benzotriazole ultraviolet absorbers, benzophenone ultraviolet absorbers, salicylate ultraviolet absorbers, cyanoacrylate ultraviolet absorbers, and oxalic acid anilide ultraviolet absorbers; light stabilizers such as hindered amine light stabilizers and benzoate light stabilizers; hydrolysis inhibitors such as polycarbodiimide; plasticizers; antistatic agents; surfactants; softening agents; water repellents; coagulation modifiers; viscosity modifiers; dyes; antiseptics; antimicrobials; deodorants; fillers such as cellulose particles and microballoons; and inorganic particles such as silica particles and titanium
• the waterborne polyurethane may also contain inorganic foaming agents such as sodium hydrogen carbonate and organic foaming agents such as 2,2′-azobis[2-methyl-N-(2-hydroxyethyl)propionamide] in order to form large voids between the fibers and the polyurethane.
• inorganic foaming agents such as sodium hydrogen carbonate
• organic foaming agents such as 2,2′-azobis[2-methyl-N-(2-hydroxyethyl)propionamide]
• the amount of the polyurethane contained in the fibrous substrate comprising microfiber-generating fibers as its main constituent in the present invention is preferably 1 to 80% by mass based on the total mass of the sheet-shaped material.
• the amount of the polyurethane contained in the sheet-shaped material is 1% by mass or more, more preferably 5% by mass or more, the sheet-shaped material will have high strength and the fibers are prevented from falling off from the sheet-shaped material.
• the amount of the polyurethane contained in the sheet-shaped material is 80% by mass or less, more preferably 70% by mass or less, the texture of the sheet-shaped material is prevented from becoming excessively hard and the sheet-shaped material will have a nap of good quality.
• step (v) of removing the PVA from the fibrous substrate comprising the microfibers as its main constituent and having the added PVA and waterborne polyurethane will be described below.
• the PVA is removed from the fibrous substrate having the added polyurethane, and a soft sheet-shaped material is obtained.
• the method for removing the PVA is not particularly limited, but in a preferred embodiment, the PVA is dissolved and removed by, for example, immersing the sheet in hot water at 60 to 100° C., and wringing out the water from the sheet with a mangle or the like.
• the process of the present invention for producing a sheet-shaped material may comprise, after at least the addition of the waterborne polyurethane to the fibrous substrate having the PVA added is performed, the step of cutting the fibrous substrate in half thickness-wise.
• the PVA migrates toward the surface, and thus a large amount of the PVA adheres in the surface region of the fibrous substrate, whereas a small amount of the PVA adheres to the inside of the fibrous substrate.
• the waterborne polyurethane is added and the fibrous substrate is cut in half thickness-wise to give a sheet-shaped material having a structure in which a small amount of the waterborne polyurethane adheres to the side to which a large amount of the PVA has adhered, whereas a large amount of the waterborne polyurethane adheres to the side to which a small amount of the PVA has adhered.
• the side to which a large amount of the PVA once adhered i.e., the side to which a small amount of the waterborne polyurethane has adhered
• the previous presence of the large amount of the PVA allows the formation of large voids between the polyurethane and the nap-forming microfibers, such large voids give the freedom of movement to the nap-forming fibers, and as a result the sheet-shaped material will have soft surface texture, an appearance of good quality and soft-touch texture.
• the side to which a small amount of the PVA once adhered i.e., the side to which a large amount of the waterborne polyurethane has adhered
• the nap-forming fibers are strongly held by the polyurethane, which provides a high-quality appearance with a short nap with a more density and also provides a good abrasion resistance.
• the process comprises the step of cutting the sheet in half thickness-wise, the production efficiency is also improved.
• At least one face of the sheet-shaped material may be subjected to napping treatment to raise a nap on the surface.
• the napping method is not particularly limited, and may be any conventional napping method in the art, such as buffing with a sandpaper or the like. An excessively short nap is unlikely to provide an elegant appearance, whereas an excessively long nap is likely to cause pilling.
• the length of the nap is thus preferably 0.2 to 1 mm.
• silicone or the like may be added as a lubricant to the sheet-shaped material.
• a lubricant is preferred because it facilitates napping by surface grinding and provides the surface with excellent quality.
• An antistatic agent may also be added before the napping treatment. The addition of an antistatic agent is preferred because it prevents the dust generated during grinding of the sheet-shaped material from depositing on the sandpaper.
• the sheet-shaped material can be dyed.
• the dyeing can be performed by various methods commonly used in the art. Preferred is a method using a jet dyeing machine because the machine softens the sheet-shaped material by kneading at the same time as the dyeing.
• the dyeing temperature varies with the type of the fibers but is preferably 80 to 150° C.
• the dyeing temperature is 80° C. or higher, more preferably 110° C. or higher, the attachment of a dye to the fibers is efficiently performed.
• the dyeing temperature is 150° C. or lower, more preferably 130° C. or lower, deterioration of the polyurethane is prevented.
• the dye used in the present invention is not particularly limited as long as the dye is appropriately selected depending on the type of the fibers constituting the fibrous substrate.
• a disperse dye can be used.
• the fibers are polyamide fibers, an acid dye, a metal complex dye, or a combination thereof may be used.
• the sheet-shaped material may be subjected to reduction cleaning after the dyeing.
• a dyeing aid is used during the dyeing.
• the dyeing aid improves the uniformity of the dyeing and the reproduction of the color.
• finishing treatment can be performed using a fabric softener such as silicone, an antistatic agent, a water repellent, a flame retardant, a light stabilizer, an antimicrobial agent, or other finishing agents.
• the density of the thus obtained sheet-shaped material of the present invention is preferably 0.2 to 0.7 g/cm 3 .
• the density is 0.2 g/cm 3 or more, more preferably 0.3 g/cm 3 or more, the sheet-shaped material is provided with a dense and high quality surface appearance.
• the density is 0.7 g/cm 3 or less, more preferably 0.6 g/cm 3 or less, the sheet-shaped material is prevented from having a hard texture.
• a test tube or flask for heating In a 24-mL test tube or flask for heating was placed 1 g of a PVA aqueous solution, and the solution was heated at 90° C. for 1 hour. The generated gas in an amount of 0.1 mL was taken with a gas-tight syringe from the test tube or flask for heating. The gas was introduced into a GC/MS, and the concentrations of methyl acetate, acetic acid and methanol were analyzed. The detection limit of GC/MS is less than 0.1 ppm.
• a dispersion of 10% by mass of a PVA in water was poured in a polyethylene tray with a size of 5 cm in length, 10 cm in width and 1 cm in height.
• the dispersion was air-dried at 25° C. for 8 hours, and then heat-treated in a hot-air drier at 120° C. for 2 hours to give a dried film of the PVA with a thickness of 100 ⁇ m.
• the tensile strength of the dried film of the PVA was determined with a tensile tester in accordance with Method A (Strip method) specified in JIS L1096 (2010) 8.14.1.
• An average single fiber diameter was determined as follows. A photograph of the surface of a fibrous substrate or a sheet-shaped material was taken in a scanning electron microscope (SEM) at a magnification of 2000. The diameters of randomly selected 100 fibers were measured, and the average was calculated to determine the average single fiber diameter.
• SEM scanning electron microscope
• the diameter of the circumcircle of the modified cross section was measured as a single fiber diameter.
• 100 fibers were selected so that the ratio of each type of fibers is equal to the actual existence ratio, and the average single fiber diameter was determined.
• the fibers in the woven fabric or knitted fabric for reinforcement were excluded from the sampling for the determination of the average single fiber diameter.
• the surface appearance of a sheet-shaped material was evaluated by 20 panelists including 10 healthy adult males and 10 healthy adult females. Visual evaluation and sensory evaluation were performed and scored based on the following criteria with 5 grades. The grade which had the largest number of the panelists was taken as the grade for the surface appearance of the sheet-shaped material. Grades 3 to 5 were regarded as good surface appearance.
• Grade 5 a uniform nap of the fibers were observed, the fibers were well separated, and the appearance was good.
• Grade 4 the material was evaluated as between Grade 5 and Grade 3.
• Grade 2 the material was evaluated as between Grade 3 and Grade 1.
• Grade 1 the fibers were very poorly separated throughout the whole surface or the napped fibers had a long length, and the appearance was poor.
• Nylon fibers being made of nylon 6 and having a diameter of 0.4 mm were cut perpendicularly to the longitudinal direction of the fibers into a length of 11 mm, and 100 cut fibers were aligned and bundled.
• 97 bundles were arranged in a concentric circle pattern of 110 mm diameter having 6 circles of increasing diameter (one bundle was placed at the center, 6 bundles were arranged along the circumference of a circle of 17 mm diameter, 13 bundles.
• the arranged bundles were used as a circular brush (the number of nylon yarns was 9700 in total).
• a circular sample (diameter: 45 mm) was taken from a sheet-shaped material and the surface was abraded with the circular brush under the conditions of a load of 8 pounds (about 3629 g), a rotation speed of 65 rpm, and a rotation of 50 times. The difference in the mass before and after the abrasion was determined. The average of five samples was calculated to determine the abrasion loss (mg), and the abrasion loss was used to evaluate the abrasion resistance.
• PVA NM-14 produced by The Nippon Synthetic Chemical Industry Co., Ltd.
• the mixture was heated to 90° C.
• the mixture was stirred for 2 hours while the temperature was maintained at 90° C. to give a PVA aqueous solution with a solid content of 10% by mass.
• concentrations of methyl acetate, acetic acid, and methanol in the PVA aqueous solution were 10.2 ppm, 0.8 ppm, and 5.2 ppm, respectively.
• a polyethylene terephthalate copolymerized with 8 mol % of sodium 5-sulfoisophthalate was used as the sea component, and a polyethylene terephthalate was used as the island component.
• the sea and island components were used at a ratio of 45% to 55% by mass to give islands-in-the-sea composite fibers with 36 islands per filament and an average single fiber diameter of 17 ⁇ m.
• the obtained islands-in-the-sea composite fibers were cut into a length of 51 mm to prepare staples.
• the staples were subjected to carding and cross lapping to form a fibrous web.
• the fibrous web was needle punched to give a nonwoven fabric.
• the thus obtained nonwoven fabric was shrunk by being immersed in hot water at a temperature of 98° C. for 2 minutes and was dried at a temperature of 100° C. for 5 minutes to give a nonwoven fabric as a fibrous substrate.
• the nonwoven fabric as a fibrous substrate was impregnated with the PVA aqueous solution, and dried under heating at 140° C. for 10 minutes to give a sheet to which the PVA was added so that the amount of the PVA adhering to the nonwoven fabric was 30% by mass based on the total mass of the fibers in the nonwoven fabric as a fibrous substrate.
• the sheet having the added PVA was immersed in a 10 g/L aqueous sodium hydroxide solution at 95° C. for 30 minutes for the removal of the sea component from the islands-in-the-sea composite fibers to give a sea component-removed sheet.
• the average single fiber diameter of the fibers on the surface of the sea component-removed sheet was 3 ⁇ m.
• Polyhexamethylene carbonate was used as a polyol and dicyclohexylmethane diisocyanate was used as an isocyanate to give a self-emulsifying polycarbonate polyurethane liquid.
• APS ammonium persulfate
• APS heat-sensitive coagulant
• the sea component-removed sheet having the added PVA was impregnated with the polycarbonate polyurethane dispersion.
• the sheet was treated in a wet-heat atmosphere at a temperature of 100° C. for 5 minutes, then dried with hot air at a drying temperature of 120° C. for 5 minutes, and dry-heated at a temperature of 140° C. for 2 minutes to give a sheet to which the polyurethane was added so that the amount of the polyurethane adhering to the sheet was 30% by mass based on the total mass of the fibers in the nonwoven fabric.
• the sheet having the added polyurethane was immersed in hot water at 95° C. for 10 minutes to give a sheet from which the added PVA was removed.
• the PVA-removed sheet was cut in half thickness-wise.
• the surfaces opposite to the cut surfaces were subjected to napping treatment by grinding with a 240-mesh abrasive belt.
• the sheet was then dyed with a disperse dye by using a circular dyeing machine and subjected to reduction cleaning to give a sheet-shaped material.
• the obtained sheet-shaped material had a good surface appearance, a soft texture, and a good abrasion resistance.
• Example 2 In the same as in Example 1, a nonwoven fabric as a fibrous substrate was produced.
• the nonwoven fabric as a fibrous substrate was treated with the PVA aqueous solution in the same manner as in Example 1 except that the amount of the PVA adhering to the nonwoven fabric was adjusted by controlling the degree of wringing after the impregnation, to give a sheet to which the PVA was added so that the amount of the PVA adhering to the nonwoven fabric was 20% by mass based on the total mass of the fibers in the nonwoven fabric as a fibrous substrate.
• Example 2 In the same manner as in Example 1, a waterborne polyurethane dispersion was prepared.
• Example 2 In the same manner as in Example 1, a sheet-shaped material was produced.
• the obtained sheet-shaped material had a good surface appearance, a soft texture, and a good abrasion resistance.
• a polyethylene terephthalate copolymerized with 8 mol % of sodium 5-sulfoisophthalate was used as the sea component, and a polyethylene terephthalate was used as the island component.
• the sea and island components were used at a ratio of 20% to 80% by mass to give islands-in-the-sea composite fibers with 16 islands per filament and an average single fiber diameter of 30 ⁇ m.
• the obtained islands-in-the-sea composite fibers were cut into a length of 51 mm to prepare staples.
• the staples were subjected to carding and cross lapping to form a fibrous web.
• the fibrous web was needle punched to give a nonwoven fabric.
• the thus obtained nonwoven fabric was shrunk by being immersed in hot water at a temperature of 98° C. for 2 minutes and was dried at a temperature of 100° C. for 5 minutes to give a nonwoven fabric as a fibrous substrate.
• the nonwoven fabric as a fibrous substrate was treated with the PVA aqueous solution in the same manner as in Example 1 to give a sheet to which the PVA was added so that the amount of the PVA adhering to the nonwoven fabric was 30% by mass based on the total mass of the fibers in the nonwoven fabric as a fibrous substrate.
• the nonwoven fabric as a fibrous substrate was treated for the removal of the sea component from the islands-in-the-sea composite fibers in the same manner as in Example 1 to give a sea component-removed sheet.
• the average single fiber diameter of the fibers on the surface of the sea component-removed sheet was 4.4 ⁇ m.
• a waterborne polyurethane dispersion prepared in the same manner as in Example 1 was used.
• Example 2 In the same manner as in Example 1, a sheet-shaped material was produced.
• the obtained sheet-shaped material had a good surface appearance, a soft texture, and a good abrasion resistance.
• PVA NM-11 produced by The Nippon Synthetic Chemical Industry Co., Ltd.
• the mixture was heated to 90° C.
• the mixture was stirred for 2 hours while the temperature was maintained at 90° C. to give a PVA aqueous solution with a solid content of 10% by mass.
• concentrations of methyl acetate, acetic acid, and methanol in the PVA aqueous solution were 7.2 ppm, 0.4 ppm, and 2.4 ppm, respectively.
• a nonwoven fabric produced in the same manner as in Example 1 was used as a fibrous substrate.
• the nonwoven fabric as a fibrous substrate was impregnated with the PVA aqueous solution, and dried under heating at 140° C. for 10 minutes to give a sheet to which the PVA was added so that the amount of the PVA adhering to the nonwoven fabric was 30% by mass based on the total mass of the fibers in the nonwoven fabric as a fibrous substrate.
• a waterborne polyurethane dispersion prepared in the same manner as in Example 1 was used.
• Example 2 In the same manner as in Example 1, a sheet-shaped material was produced.
• the obtained sheet-shaped material had a good surface appearance, a soft texture, and a good abrasion resistance.
• PVA NH-26 produced by The Nippon Synthetic Chemical Industry Co., Ltd.
• a degree of saponification of 99% and a degree of polymerization of 2600 was added to water at 25° C.
• the mixture was stirred for 2 hours while the temperature was maintained at 90° C. to give a PVA aqueous solution with a solid content of 10% by mass.
• concentrations of methyl acetate, acetic acid, and methanol in the PVA aqueous solution were 32.2 ppm, 8.3 ppm, and 20.1 ppm, respectively.
• a nonwoven fabric produced in the same manner as in Example 1 was used as a fibrous substrate.
• the nonwoven fabric as a fibrous substrate was impregnated with the PVA aqueous solution, and dried under heating at 140° C. for 10 minutes to give a sheet to which the PVA was added so that the amount of the PVA adhering to the nonwoven fabric was 10% by mass based on the total mass of the fibers in the nonwoven fabric as a fibrous substrate.
• a waterborne polyurethane dispersion prepared in the same manner as in Example 1 was used.
• Example 2 In the same manner as in Example 1, a sheet-shaped material was produced.
• the obtained sheet-shaped material had a good surface appearance, a soft texture, and a good abrasion resistance.
• a polyethylene terephthalate copolymerized with 8 mol % of sodium 5-sulfoisophthalate was used as the sea component, and a polyethylene terephthalate was used as the island component.
• the sea and island components were used at a ratio of 20% to 80% by mass to give islands-in-the-sea composite fibers with 16 islands per filament and an average single fiber diameter of 30 ⁇ m.
• the obtained islands-in-the-sea composite fibers were cut into a length of 51 mm to prepare staples. The staples were subjected to carding and cross lapping to form a fibrous web.
• a plain woven fabric using a polyethylene terephthalate (PET) hard twist yarn of 84 dtex and 72 filaments with a twist of 2000 T/m was stacked, and the fibrous web and the plain woven fabrics were needle punched together to give a nonwoven fabric.
• the thus obtained nonwoven fabric was shrunk by being immersed in hot water at a temperature of 98° C. for 2 minutes and was dried at a temperature of 100° C. for 5 minutes to give a nonwoven fabric as a fibrous substrate.
• the nonwoven fabric as a fibrous substrate was impregnated with the PVA aqueous solution, and dried under heating at 140° C. for 10 minutes to give a sheet to which the PVA was added so that the amount of the PVA adhering to the nonwoven fabric was 15% by mass based on the total mass of the fibers in the nonwoven fabric as a fibrous substrate.
• the nonwoven fabric as a fibrous substrate was treated for the removal of the sea component from the islands-in-the-sea composite fibers in the same manner as in Example 1 to give a sea component-removed sheet.
• the average single fiber diameter of the fibers on the surface of the sea component-removed sheet was 4.4 ⁇ m.
• a waterborne polyurethane dispersion prepared in the same manner as in Example 1 was used.
• Example 2 In the same manner as in Example 1, a sheet-shaped material was produced.
• the obtained sheet-shaped material had a good surface appearance, a soft texture, and a good abrasion resistance.
• Example 2 In the same as in Example 1, a nonwoven fabric as a fibrous substrate was produced.
• the nonwoven fabric as a fibrous substrate was treated in the same manner as in Example 1 to give a sheet to which the PVA was added so that the amount of the PVA adhering to the nonwoven fabric was 30% by mass based on the total mass of the fibers in the nonwoven fabric as a fibrous substrate.
• Polyhexamethylene carbonate was used as a polyol and dicyclohexylmethane diisocyanate was used as an isocyanate to give a self-emulsifying polycarbonate polyurethane liquid.
• a thickener (SN-THICKENER 627N produced by San Nopco Limited) was added in an amount of 5 parts by mass based on 100 parts by mass of the solid content of the polyurethane liquid. Water was then added to adjust the overall polyurethane solid content to 20% by mass to give a waterborne polyurethane dispersion.
• the sea component-removed sheet having the added PVA was impregnated with the polyurethane dispersion.
• the sheet was dried with hot air at a drying temperature of 100° C. for 30 minutes to give a sheet to which the polyurethane was added so that the amount of the polyurethane adhering to the sheet was 30% by mass based on the total mass of the fibers in the nonwoven fabric.
• Example 2 In the same manner as in Example 1, a sheet-shaped material was produced.
• the obtained sheet-shaped material had a good surface appearance, a soft texture, and a good abrasion resistance.
• a nonwoven fabric produced in the same manner as in Example 1 was used as a fibrous substrate.
• the nonwoven fabric as a fibrous substrate was impregnated with the PVA aqueous solution, and dried under heating at 140° C. for 10 minutes to give a sheet to which the PVA was added so that the amount of the PVA adhering to the nonwoven fabric was 10% by mass based on the total mass of the fibers in the nonwoven fabric as a fibrous substrate.
• Polyhexamethylene carbonate was used as a polyol and dicyclohexylmethane diisocyanate was used as an isocyanate to give a self-emulsifying polycarbonate polyurethane liquid.
• APS ammonium persulfate
• APS heat-sensitive coagulant
• the sea component-removed sheet having the added PVA was impregnated with the polyurethane dispersion.
• the polyurethane was coagulated in hot water at 80° C. and was dried with hot air at a drying temperature of 100° C. for 15 minutes to give a sheet to which the polyurethane was added so that the amount of the polyurethane adhering to the sheet was 30% by mass based on the total mass of the fibers in the nonwoven fabric.
• Example 2 In the same manner as in Example 1, a sheet-shaped material was produced.
• the obtained sheet-shaped material had a good surface appearance, a soft texture, and a good abrasion resistance.
• a nonwoven fabric produced in the same manner as in Example 1 was used as a fibrous substrate.
• the above-obtained nonwoven fabric as a fibrous substrate was immersed in a 10 g/L aqueous sodium hydroxide solution at 95° C. for 10 minutes for the removal of the sea component from the islands-in-the-sea composite fibers to give a sea component-removed sheet.
• the average single fiber diameter of the fibers on the surface of the sea component-removed sheet was 3 ⁇ m.
• the sea component-removed sheet was impregnated with the PVA aqueous solution prepared in the same manner as in Example 1, and dried under heating at 140° C. for 10 minutes to give a sheet to which the PVA was added so that the amount of the PVA adhering to the sea component-removed sheet was 30% by mass based on the total mass of the fibers in the sea component-removed sheet.
• a waterborne polyurethane dispersion prepared in the same manner as in Example 1 was used.
• the sea component-removed sheet having the added PVA was impregnated with the polycarbonate polyurethane dispersion.
• the sheet was treated in a wet-heat atmosphere at a temperature of 100° C. for 5 minutes, then dried with hot air at a drying temperature of 120° C. for 5 minutes, and dry-heated at a temperature of 140° C. for 2 minutes to give a sheet to which the polyurethane was added so that the amount of the polyurethane adhering to the sheet was 30% by mass based on the total mass of the microfibers.
• Example 2 In the same manner as in Example 1, a sheet-shaped material was produced.
• the obtained sheet-shaped material had a good surface appearance and a soft texture, but the abrasion loss was relatively large.
• PVA GL-05 produced by The Nippon Synthetic Chemical Industry Co., Ltd.
• the mixture was heated to 90° C.
• the mixture was stirred for 2 hours while the temperature was maintained at 90° C. to give a PVA aqueous solution with a solid content of 10% by mass.
• concentrations of methyl acetate, acetic acid, and methanol in the PVA aqueous solution were 70.1 ppm, 40.1 ppm, and 100.3 ppm, respectively.
• a nonwoven fabric produced in the same manner as in Example 1 was used as a fibrous substrate.
• the nonwoven fabric as a fibrous substrate was impregnated with the PVA aqueous solution in the same manner as in Example 1 except that the amount of the PVA adhering to the nonwoven fabric was adjusted by controlling the degree of wringing after the impregnation, to give a sheet to which the PVA was added so that the amount of the PVA adhering to the nonwoven fabric was 10% by mass based on the total mass of the fibers in the nonwoven fabric as a fibrous substrate.
• a waterborne polyurethane dispersion prepared in the same manner as in Example 1 was used.
• Example 2 In the same manner as in Example 1, a sheet-shaped material was produced. To the obtained sheet-shaped material, the polyurethane did not uniformly adhere due to partial dissolution of the PVA into the aqueous alkaline solution and the waterborne polyurethane dispersion. As a result, the sheet-shaped material had a poor surface appearance with a poor separability of the fibers and with no dense nap and had a hard texture.
• PVA NL-05 produced by The Nippon Synthetic Chemical Industry Co., Ltd.
• the mixture was heated to 90° C.
• the mixture was stirred for 2 hours while the temperature was maintained at 90° C. to give a PVA aqueous solution with a solid content of 10% by mass.
• concentrations of methyl acetate, acetic acid, and methanol in the PVA aqueous solution were 6.1 ppm, 0.4 ppm, and 1.1 ppm, respectively.
• a nonwoven fabric produced in the same manner as in Example 1 was used as a fibrous substrate.
• the nonwoven fabric as a fibrous substrate was impregnated with the PVA aqueous solution in the same manner as in Example 1 except that the amount of the PVA adhering to the nonwoven fabric was adjusted by controlling the degree of wringing after the impregnation, to give a sheet to which the PVA was added so that the amount of the PVA adhering to the nonwoven fabric was 10% by mass based on the total mass of the fibers in the nonwoven fabric as a fibrous substrate.
• a waterborne polyurethane dispersion prepared in the same manner as in Example 1 was used.
• Example 2 In the same manner as in Example 1, a sheet-shaped material was produced. To the obtained sheet-shaped material, the polyurethane did not uniformly adhere due to partial dissolution of the PVA into the aqueous alkaline solution and the waterborne polyurethane dispersion. As a result, the sheet-shaped material had a poor surface appearance with a poor separability of the fibers and with no dense nap and had a hard texture.
• a nonwoven fabric produced in the same manner as in Example 1 was used as a fibrous substrate.
• the nonwoven fabric as a fibrous substrate was treated with the PVA aqueous solution in the same manner as in Example 1 except that the amount of the PVA adhering to the nonwoven fabric was adjusted by controlling the degree of wringing after the impregnation, to give a sheet to which the PVA was added so that the amount of the PVA adhering to the nonwoven fabric was 55% by mass based on the total mass of the fibers in the nonwoven fabric as a fibrous substrate.
• a waterborne polyurethane dispersion prepared in the same manner as in Example 1 was used.
• Example 2 In the same manner as in Example 1, a sheet-shaped material was produced.
• the obtained sheet-shaped material had a soft texture.
• the excess amount of the PVA resulted in insufficient holding of the fibers by the polyurethane.
• the sheet-shaped material had a poor surface appearance with an excessively long nap and had a poor abrasion resistance.
• a sheet-shaped material was produced in the same manner as in Example 1 except that no PVA aqueous solution was prepared and that no PVA was added or removed.
• the obtained sheet-shaped material had a hard texture and had a poor surface appearance with no nap.
• Tables 1 and 2 show the test conditions in Examples and Comparative Examples and the evaluation results for the sheet-shaped materials.
• the sheet-shaped materials obtained in Examples 1 to 8 had a good surface appearance, a soft texture, and a good abrasion resistance.
• the sheet-shaped materials obtained in Comparative Examples 1 and 4 had a poor abrasion resistance
• the sheet-shaped materials obtained in Comparative Examples 2 to 5 had a poor surface appearance.
• the sheet shaped materials of Comparative Examples 2, 3 and 5 had a hard texture.
• the sheet-shaped material obtained according to the present invention is suitable as interior materials having a very elegant appearance, such as surface materials of furniture, chairs, walls, seats in vehicles including automobiles, trains, and aircrafts, ceiling, and interior decoration; clothing materials, such as shirts, jackets, upper and trim and the like of shoes including casual shoes, sports shoes, men's shoes and ladies' shoes, bags, belts, wallets, and a part of them; and industrial materials such as wiping cloth, abrasive cloth and CD curtains.

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• Synthetic Leather, Interior Materials Or Flexible Sheet Materials (AREA)
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• Chemical Or Physical Treatment Of Fibers (AREA)

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• 2013
  • 2013-11-27 EP EP13859092.2A patent/EP2927368B1/en active Active
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