JP6623646B2 - Sheet - Google Patents

Description

  The present invention relates to a sheet-like material having high mechanical properties, flexibility, lightness and quality, and a method for producing the same.

  Artificial leather is widely used in applications such as shoes, bags, and sports shoes, taking advantage of its design, and also has a possibility of obtaining performance that cannot be obtained with natural materials, and its application range is wide. . As a method for producing artificial leather, a sheet-like material including a fiber structure formed from ultrafine fibers has long been known. The fiber structure formed from the ultrafine fibers is, for example, generally a fiber structure obtained by selectively dissolving and removing only the sea component from the fiber structure made of the sea-island composite fiber. By using such a method, it is possible to obtain a fibrous structure composed of ultrafine fibers, but when selectively removing sea components, or by press processing for adjusting the thickness, the voids between the fibers are significantly increased. Therefore, there is a problem that sufficient lightness cannot be obtained. In order to solve such a problem, there is known a method of using a fiber structure formed from hollow fibers as a sheet.

  Specifically, artificial leather including polyester-based hollow fibers having an apparent fineness of 2.0 denier, having one hollow portion, and having a hollow ratio of 40 to 85% has been proposed. There has been a problem that hollow collapse is likely to occur due to an external force (see Patent Document 1).

  Separately, an artificial leather substrate made of a nonwoven fabric made of a hollow fiber having 5 to 50 hollow portions in a fiber cross section and an elastic polymer has been proposed (see Patent Document 2). The fineness was as thick as 3.5 dtex and poor in flexibility. Separately, artificial leather made of ultrafine fibers having a hollow portion and having a single fiber fineness of 0.1 decitex or less has been proposed, but the number of hollows is one, and the stability of the fiber cross section is lacking ( See Patent Document 3.).

  Patent Document 4 proposes a hollow fiber having a hollow ratio of 10 to 35% and a single-fiber fineness of 0.1 to 3.5 dtex, but a hollow fiber obtained by flow drawing has an excellent quality. In addition to not being able to obtain artificial leather having the sheet, the sheet had poor flexibility even when manufactured.

Japanese Patent No. 3924360 Japanese Patent No. 4004938 Japanese Patent No. 4869462 JP 2014-210990 A

  Therefore, an object of the present invention is to provide a sheet-like material having high mechanical properties, flexibility, light weight, and quality, and a method for manufacturing the same in view of the above-mentioned problems of the related art.

  That is, the present invention is intended to solve the above problems, and the artificial leather of the present invention comprises a nonwoven fabric and an elastic polymer mainly composed of ultrafine hollow fibers having an average single fiber diameter of 0.05 to 10 μm. A sheet-like material provided as a component, wherein the ultrafine hollow fiber has a hollow portion extending in the fiber longitudinal direction therein, and the hollow portion has 2 to 60 hollow portions when a cross section of the ultrafine fiber is observed. A sheet-like material which can be observed, and wherein the total area of the hollow portion in the cross section is 30 to 80% of the area of the cross section.

  According to a preferred embodiment of the sheet material of the present invention, the average single fiber diameter of the ultrafine hollow fibers is in a range of 0.1 to 6 μm.

  The ultrafine hollow fiber used in the present invention is formed from a conjugate fiber having a structure in which an island component of a hardly eluting component is arranged in a sea component of an easily eluting component, and a removable polymer component is arranged in the island component. be able to.

  ADVANTAGE OF THE INVENTION According to this invention, the sheet-like material suitable for artificial leather which has high mechanical characteristics like a solid fiber, is soft, lightweight, and excellent in texture is obtained.

  In the present invention, the ultrafine hollow fiber is a fiber having an average single fiber diameter as described below and having a hollow portion as described below inside.

  The nonwoven fabric constituting the sheet-like material of the present invention is mainly composed of ultrafine hollow fibers, and it is important that the ultrafine hollow fibers have an average single fiber diameter in a range of 0.05 to 10 μm. By setting the average single fiber diameter to 0.05 μm or more, sufficient mechanical strength can be maintained for the sheet-like material, and by setting the average single fiber diameter to 10 μm or less, flexibility in artificial leather can be obtained. . A more preferable range of the average single fiber diameter is in a range of 0.1 to 6 μm. Here, “mainly” means that the nonwoven fabric accounts for 60% or more, preferably 80% or more of the total mass of the nonwoven fabric.

  Examples of the polymer constituting the ultrafine hollow fiber used in the present invention include polyester, polyamide, polyolefin and polyphenylene sulfide. Polycondensation polymers represented by polyesters and polyamides often have a high melting point, and when made into sheets such as artificial leather using fibers made of these polycondensation polymers, physical properties such as mechanical properties Since it shows good performance, it is preferably used in the present invention.

  Specific examples of polyester include polyethylene terephthalate, polybutylene terephthalate, potitrimethylene terephthalate, and the like. Specific examples of polyamide include nylon 6, nylon 66, nylon 610, and nylon 12.

The polymer constituting the ultrafine hollow fiber used in the present invention may contain additives such as particles, a flame retardant and an antistatic agent.
As the cross-sectional shape of the ultrafine hollow fiber, that is, the shape formed by the outer periphery of the fiber, for example, a polygon such as a circle, an ellipse, a flat shape, a triangle, a fan shape, a cross shape, a Y shape, an H shape, an X shape, a W shape, C-type and π-type can be used.

  Ultrafine hollow fibers having a hollow portion suitably used in the artificial leather of the present invention, for example, a polymer plate of the sea-island component described in JP 2011-174215 A, a measuring plate having a plurality of measuring holes for measuring, It can be manufactured by using a composite spinneret capable of forming various cross-sectional shapes by combining a distribution plate having a plurality of distribution holes with a merging groove for merging the discharged polymer flows from a plurality of measurement holes.

  It is important that the hollow portion existing inside the ultrafine hollow fiber used in the present invention extends in the longitudinal direction, and that 2 to 60 hollow portions are observed when the cross section of the ultrafine hollow fiber is observed. . Since the number of hollow portions is two or more, a wall surface (support crossing the fiber cross section) is formed between each hollow portion, so that the rigidity of the ultrafine hollow fiber can be improved as compared with the case where only one hollow portion is provided. It becomes possible, and the collapse of the ultrafine hollow fiber can be suppressed. There is no particular upper limit on the number of hollow portions in the ultrafine hollow fiber. However, if the number is excessively increased, the effect of improving mechanical properties cannot be expected, and on the other hand, productivity may be reduced. It is desirable that the number is not more than the number. More preferably, the range is 3 to 40.

  Here, the transverse section is a plane that appears when the ultrafine fiber is cut on a plane orthogonal to the fiber axis. In addition, extending means a state in which the hollow is formed continuously in the longitudinal direction of the ultrafine fiber, and the hollow is desirably continuous from one end to the other end of the fiber.

  The method for measuring the number of hollow portions in the microfiber is, for example, cutting out a cross section (cross section) orthogonal to the fiber axis direction of the microfiber, observing the cross section with a scanning electron microscope at 3000 times, The number of hollow portions in 30 single fibers randomly extracted in a visual field of 30 μm × 30 μm is counted, and the number is determined by the number average value.

  In the microfiber hollow fiber used in the present invention, the total area of the hollow portion in the cross section is 30 to 80% of the area of the cross section (the ratio of the hollow portion may be hereinafter referred to as “hollow ratio”). Is more preferable, and it is more preferable that it is 40 to 70%. If the hollow ratio is less than 30%, sufficient flexibility cannot be obtained, and if the hollow ratio exceeds 80%, the hollow portion tends to be crushed and the flexibility tends to decrease.

  The method of measuring the hollow ratio is such that the cross section of the ultrafine hollow fiber is observed at a magnification of 3000 using a scanning electron microscope, and the total area Sa of the cross section of the single fiber is determined from 30 randomly extracted single fibers. The total area within the closed curve surrounded by the outer contour of the fiber cross section including the hollow section) and the hollow area Sb of the single fiber cross section are measured and calculated as Sb / Sa × 100 (%).

  The hollow portion here may be continuous or discontinuous in the length direction of the ultrafine fiber. From the viewpoint of surface condition and strength, it is preferable that no hollow hole is formed in the fiber side surface.

  The cross-sectional shape of the hollow portion may be a desired shape such as a round shape or a polygonal shape depending on the purpose, but a round shape is preferred from the viewpoint of the morphological stability of the fiber cross section. The arrangement of the hollow microfibers in the cross section may be concentrically arranged, radially arranged, or an arbitrary arrangement.

  When naps are formed on the surface of artificial leather using ultra-fine hollow fibers, the fibers are lighter, so that the naps are more dispersible than when there is no hollow portion, and the quality and touch are improved. .

  In a preferred embodiment, the ultrafine hollow fiber is obtained from a sea-island composite fiber. The ultrafine hollow fiber used in the present invention is a sea-island composite fiber, which is divided into a sea (outside sea) component due to a polymer component easily soluble in a solvent used in a solvent extraction step described later and an island component due to a polymer component hardly soluble in a solvent. In addition, it can be obtained by forming a composite fiber in a form having a region composed of a polymer component removable by a solvent inside the island component and also called a Nakaumi component, that is, a so-called Nakaumi entering sea-island type composite fiber.

  The sea-island-in-sea composite fiber having a sea in the sea, for example, described in Japanese Patent Application Laid-Open No. 2011-174215, a measuring plate having a plurality of measuring holes for measuring the polymer flow of the sea-island component, and a discharge polymer flow from the plurality of measuring holes are combined. It can be manufactured by using a composite spinneret capable of forming various cross-sectional shapes by combining a distribution plate having a plurality of distribution holes in a merging groove.

  The obtained Nakakai conjugate fiber is formed into a sheet to form a nonwoven fabric. A known method can be adopted as a method for forming a nonwoven fabric.

  Next, in making the sheet-like material of the present invention, a step of extracting and removing the easily-eluting component with a solvent and a step of providing an elastic polymer are required, but depending on the purpose, any of the steps is first. Is also good.

  An ultrafine fiber having a hollow portion can be obtained by extracting and removing the outer sea component and the middle sea component by dissolution and removal with a solvent or the like, or by extrusion or centrifugation utilizing fluidity.

  The outer sea component is preferably dissolved and removed with a solvent or the like as in the prior art, and the middle sea component may be removed by extrusion or centrifugation utilizing fluidity, in addition to the same dissolution treatment as the outer sea component.

  The outer sea component and the middle sea component in the sea-in-sea-in-sea type composite fiber of the middle sea may use the same polymer or different polymers, respectively.However, from the viewpoint of the ease of forming a hollow structure, is the middle sea component the same as the outer sea component? It is a preferred embodiment to use a component that is more easily eluted (dissolved) than the open sea component.

  The sea-island / sea-island composite fiber used in the sheet material of the present invention preferably has a shrinkage ratio at a temperature of 98 ° C. of 5 to 40%, more preferably 10 to 35%. By setting the shrinkage in the above range, the quality of the product when used as artificial leather can be improved.

Specifically, in the method of measuring the shrinkage, first, a load of 50 mg / dtex is applied to the bundle of composite fibers, and 30.0 cm is marked (L ₀ ). Then, it is treated in hot water at a temperature of 98 ° C. for 10 minutes, the length before and after the treatment (L ₁ ) is measured, and (L ₀ −L ₁ ) / L ₀ × 100 is calculated. The measurement is performed three times, and the average value is used as the contraction rate.

  In the present invention, a nonwoven fabric in which bundles of ultrafine hollow fibers (ultrafine fiber bundles) are entangled is preferably used from the viewpoint of the uniformity and strength of the surface of artificial leather.

  As the form of the ultrafine hollow fiber bundle, the ultrafine fibers may be slightly separated from each other, may be bonded or not bonded, may be partially bonded, and may be aggregated. Can be taken.

  As the nonwoven fabric used in the artificial leather of the present invention, a short fiber nonwoven fabric obtained by forming a laminated web of short fibers using a card or a cross wrapper and then performing a needle punch or a water jet punch, a spun bond method or a melt blowing method A long-fiber nonwoven fabric obtained by a papermaking method, a nonwoven fabric obtained by a papermaking method, or the like can be used. Among them, short fiber nonwoven fabrics and spunbonded nonwoven fabrics are preferably used because those having good thickness uniformity and the like can be obtained.

  In the nonwoven fabric constituting the sheet-like material of the present invention, not only the above-mentioned ultrafine hollow fibers but also other fibers can be mixed. Examples of other types of fibers to be mixed include fibers made of a thermoplastic resin such as polyester, polyamide, polyolefin, and polyphenylene sulfide.

  The single fiber fineness of the conjugate fiber used in the present invention is preferably in the range of 2 to 10 dtex, more preferably in the range of 3 to 9 dtex, from the viewpoint of entanglement such as a needle punching step.

  As for the type of the conjugate fiber used in the present invention, a sea-island type conjugate fiber is preferably used from the viewpoints of high quality, quality and touch when used for artificial leather, as described later.

  In the nonwoven fabric used in the present invention, a woven fabric or a knitted fabric can be laminated or lined in the nonwoven fabric for the purpose of improving strength or the like. In a case where the nonwoven fabric and the woven / knitted fabric are laminated and integrated by a needle punch, it is a preferred embodiment that the yarn of the woven / knitted fabric is a strongly twisted yarn in order to prevent the fibers constituting the woven / knitted fabric from being damaged by the needle punch. The twist number of the yarn constituting the woven or knitted fabric is preferably in a range of 700 T / m to 4500 T / m. The fiber diameter of the single fibers constituting the woven or knitted fabric may be the same as or smaller than the fiber diameter of the ultrafine hollow fibers of the nonwoven fabric made of the ultrafine hollow fibers.

It is important that the sheet-like material of the present invention has a nonwoven fabric mainly composed of the above-mentioned ultrafine conjugate fiber and an elastic polymer. When the elastic polymer is applied in a form present on the surface of the nonwoven fabric, the binder effect of the elastic polymer can not only prevent the ultrafine fibers from falling off the artificial leather, but also provide an appropriate cushioning property. It becomes possible. In addition, the elastic polymer refers to a polymer or a polymer composition or a mixture that exhibits elasticity such as rubber when an external force is applied within a use temperature range of the sheet-like material.As the elastic polymer that can be used in the present invention, Polyurethane, polyurea, polyurethane / polyurea elastomer, polyacrylic acid, acrylonitrile / butadiene elastomer, styrene / butadiene elastomer and the like can be used, but polyurethane is preferably used from the viewpoint of flexibility and cushioning properties.

  As the polyurethane, for example, at least one kind of polymer diol selected from polyester diol, polyether diol, polycarbonate diol, or polymer diol such as polyester polyether diol having an average molecular weight of 500 to 3,000, and 4,4′-diphenylmethane At least one diisocyanate selected from an aromatic diisocyanate or the like, an alicyclic diisocyanate such as isophorone diisocyanate, and an aliphatic diisocyanate such as hexamethylene diisocyanate; ethylene glycol, butanediol, ethylenediamine and 4,4 ′ Polyurethane obtained by reacting at least one low-molecular compound having two or more active hydrogen atoms, such as diaminodiphenylmethane, in a predetermined molar ratio; Sex products thereof.

  The mass average molecular weight of the polyurethane elastomer is preferably 50,000 to 300,000. When the mass average molecular weight is 50,000 or more, more preferably 100,000 or more, and still more preferably 150,000 or more, the strength of the artificial leather can be maintained and the composite fiber can be prevented from falling off. By setting the mass average molecular weight to 300,000 or less, more preferably 250,000 or less, it is possible to suppress the increase in the viscosity of the polyurethane solution and facilitate the impregnation of the nonwoven fabric.

  The elastic polymer may contain an elastomer resin such as polyester, polyamide, and polyolefin, an acrylic resin, and an ethylene-vinyl acetate resin.

  In addition, the elastic polymer used in the present invention may include, if necessary, pigments such as carbon black, dye antioxidants, antioxidants, light stabilizers, antistatic agents, dispersants, softeners, coagulation regulators, Additives such as flame retardants, antibacterial agents and deodorants can be included.

  Further, as the elastic polymer, any of an elastic polymer dissolved in an organic solvent and an elastic polymer dispersed in water can be used.

  The content of the elastic polymer is preferably 5 to 200% by mass based on the nonwoven fabric formed by entanglement of the ultrafine hollow fibers. The surface state, cushioning property, hardness and strength of the artificial leather can be adjusted by the content of the elastic polymer. When the content is 5% by mass or more, more preferably 20% by mass or more, and still more preferably 30% by mass or more, fiber shedding can be reduced. On the other hand, when the content is 200% by mass or less, more preferably 100% by mass or less, and still more preferably 80% by mass or less, a state in which the ultrafine fibers are uniformly dispersed on the sheet surface can be obtained.

The basis weight of the sheet material of the present invention is preferably in the range of 100 to 500 g / m ² . By setting the basis weight to preferably 100 g / m ² or more, and more preferably 150 g / m ² or more, sufficient form stability and dimensional stability can be obtained when artificial leather is used. On the other hand, by setting the basis weight to preferably 500 g / m ² or less, more preferably 300 g / m ² or less, sufficient flexibility can be obtained when artificial leather is used.

  The thickness of the sheet material of the present invention is preferably in the range of 0.1 to 10 mm. By setting the thickness to preferably 0.1 mm or more, preferably 0.3 mm or more, sufficient morphological stability and dimensional stability can be obtained. On the other hand, by setting the thickness to preferably 10 mm or less, more preferably 5 mm or less, sufficient flexibility can be obtained.

  In a preferred embodiment, the sheet-like material of the present invention has at least one surface subjected to a napped treatment. By doing so, a precise touch can be obtained when suede-like artificial leather is used.

  The sheet-like material of the present invention may be formed as a coating layer (silver surface layer) made of a resin and used as artificial leather with silver.

  Examples of the resin component that forms the coating layer include polyurethane, polyolefin-based elastic, polyamide-based elastic, acrylic-based elastic, silicone-based elastic, diene-based elastic, nitrile-based elastic, fluorine-based elastic, and polystyrene. Emulsions of elastomers such as elastomers, halogen elastomers, and the like, and resin liquids such as suspensions, dispersions, and solutions. These may be used alone or in combination of two or more. Among these, polyurethane is preferable because of its excellent abrasion resistance and mechanical properties. Further, the resin component may contain a colorant, an ultraviolet absorber, a surfactant, a flame retardant, an antioxidant, and the like, if necessary.

  The thickness of the grain surface layer is preferably in the range of 0.03 to 3 mm, more preferably in the range of 0.05 to 0.5 mm.

  The thickness of the artificial leather with grain after the formation of the grain surface layer is preferably in the range of 0.2 to 12 mm, and more preferably in the range of 0.4 to 5 mm.

  Next, the sheet-like material and the like of the present invention and the method for producing the same will be described more specifically by way of examples.

  As a method for obtaining ultrafine hollow fibers, two or more thermoplastic resins having different solubility in a solvent or the like are used for the sea component and the island component, and the sea component is dissolved and removed using a solvent or the like in a later step. Sea-island composite fibers with island components as ultra-fine fibers, or peel-type composites in which a plurality of thermoplastic resins are alternately arranged radially or in layers on the fiber cross-section, and each component is separated and separated into ultra-fine fibers. Fiber or the like can be employed. Specifically, the polymer flow of the sea-island component described in JP-A-2011-174215, a measuring plate having a plurality of measuring holes for measuring, and a merging groove for merging the discharged polymer flows from the plurality of measuring holes. By using a composite spinneret capable of forming various cross-sectional shapes by combining a distribution plate having a plurality of distribution holes, a sea-island composite fiber can be produced. The ultrafine hollow fiber of the present invention can be achieved by arranging the distribution holes in the island component of the sea-island composite fiber so that the Nakaumi component can be formed.

  The fiber entangled body (nonwoven fabric) constituting the sheet material of the present invention can be obtained as a fiber entangled body (nonwoven fabric) by a step of producing a composite fiber web and a step of subjecting the composite fiber web to an entanglement treatment. Before dissolving and removing the polymer of the easily dissolvable component of the composite fiber or by physical or chemical action from the obtained nonwoven fabric, and before and / or after the raising of the ultrafine fibers into and / or after the raising treatment, the polyurethane is used as the main component. An artificial leather can be obtained by applying an elastic polymer to the nonwoven fabric, substantially coagulating and solidifying the elastic polymer, and performing a raising process to form naps on the surface and make the thickness uniform, Further, artificial leather is obtained through a step of finishing by dyeing.

  It is important that the ultrafine hollow fiber having a hollow portion constituting the sheet material of the present invention has 2 to 60 hollow portions in the ultrafine hollow fiber having an average fiber diameter of 0.05 to 10 μm. The formation of the hollow portion is preferably obtained from a precisely controlled sea-island composite fiber, and has a hollow portion by forming a Nakaumi component in the island component of the sea-island fiber and extracting and removing the Nakaumi component. Ultrafine hollow fibers can be obtained.

  The conjugate fiber used in the present invention is preferably provided with a buckling crimp. This is because the buckling crimp improves the entanglement between the fibers when the short-fiber nonwoven fabric is formed, and enables high density and high entanglement. In order to impart a buckling crimp to the conjugate fiber, a normal stuffing box type crimper is preferably used.However, in order to obtain a preferable crimp retention coefficient in the present invention, the processing fineness, crimper temperature, crimper load and In a preferred embodiment, the indentation pressure and the like are appropriately adjusted.

The crimp retention coefficient of the ultrafine fiber-generating fiber to which the buckling crimp has been imparted is preferably in the range of 3.5 to 15, more preferably 4 to 10. When the crimp retention coefficient is 3.5 or more, the rigidity in the thickness direction of the nonwoven fabric is improved when the nonwoven fabric is formed, and the entanglement in the entanglement step such as needle punching can be maintained. Further, by setting the crimp retention coefficient to 15 or less, the fiber web is excellent in the opening property of carding without excessive crimping.
The crimp retention coefficient here is represented by the following equation.
・ Crimp retention coefficient = (W / L−L ₀ ) ^1/2
W: Crimp disappearance load (load at the time when the crimp is fully extended: mg / dtex)
L: Fiber length (cm) under crimp extinction load
L ₀ : fiber length (cm) under 6 mg / dtex. Mark 30.0 cm.

  As a measuring method, first, a load of 100 mg / dtex is applied to the sample, and thereafter, the load is increased in increments of 10 mg / dtex, and the state of crimp is confirmed. A load is applied until the crimp is fully extended, and the length of the marking (elongation from 30.0 cm) in a state where the crimp is fully extended is measured.

  Extraction and removal of the sea component and the sea component in the island component of the conjugate fiber used in the production of the sheet material of the present invention are performed before, after, and after the elastic polymer is applied when producing artificial leather. It can be performed at any stage after the treatment.

  As a method for obtaining the nonwoven fabric constituting the sheet-like material of the present invention, as described above, a method of entanglement of the fiber web with a needle punch or a water jet punch, a spun bond method, a melt blow method, a papermaking method, or the like is employed. Above all, in order to form the above-mentioned ultrafine fiber bundle, a method of performing a treatment such as a needle punch or a water jet punch is preferably used.

  As described above, the nonwoven fabric may be formed by laminating and integrating the nonwoven fabric and the woven or knitted fabric, and a method of integrating these by a needle punch, a water jet punch, or the like is preferably used.

  In the needle used for the needle punching process, the number of needle barbs (cutting) is preferably 1 to 9. By using preferably one or more needle barbs, efficient intertwining of fibers becomes possible. On the other hand, by setting the number of needle barbs to preferably nine or less, fiber damage can be suppressed.

  The number of conjugate fibers such as microfiber-generating fibers that catch on the barb is determined by the shape of the barb and the diameter of the conjugate fiber. Therefore, the barb shape of the needle used in the needle punching step has a kick-up of 0 to 50 μm, an undercut angle of 0 to 40 °, a throat depth of 40 to 80 μm, and a slow strength of 0.5 to 0.5 μm. １．０1.0 mm is preferably used.

The number of punches is preferably 1000 to 8000 / cm ² . By setting the number of punches to preferably 1000 / cm ² or more, denseness can be obtained and high-precision finishing can be obtained. On the other hand, by setting the number of punches to preferably 8000 / cm ² or less, it is possible to prevent deterioration in workability, fiber damage, and decrease in strength.

  When the woven or knitted fabric and the nonwoven fabric made of the ultrafine fiber-generating fiber are laminated and integrated, the barb direction of the needle of the needle punch should be 90 ± 25 ° which is preferably perpendicular to the traveling direction of the woven or knitted fabric and the nonwoven fabric. Thereby, it becomes difficult to catch the easily-wound weft.

  When performing the water jet punching, it is preferable to perform the water in a columnar flow state. Specifically, in a preferred embodiment, water is jetted from a nozzle having a diameter of 0.05 to 1.0 mm at a pressure of 1 to 60 MPa.

The apparent density of the nonwoven fabric made of the conjugate fiber after the needle punching treatment or the water jet punching treatment is preferably 0.15 to 0.45 g / cm ³ . By setting the apparent density to preferably 0.15 g / cm ³ or more, the artificial leather can obtain sufficient form stability and dimensional stability. On the other hand, by setting the apparent density to preferably 0.45 g / cm ³ or less, a sufficient space for providing the elastic polymer can be maintained.

  From the viewpoint of densification, the nonwoven fabric made of the sea-in-sea-island type ultrafine fiber-generating fibers obtained in this manner is preferably shrunk by dry heat or wet heat or both to further increase the density. .

  As a solvent for dissolving the sea component and the sea component forming the hollow portion in the ultrafine fiber (island component) from the ultrafine fiber-generating fiber of the conjugate fiber, sodium hydroxide is used if the sea component is polylactic acid or a copolyester. Can be used. When the Nakaumi component can be dissolved and removed with the same solvent as the ocean component, a very fine hollow fiber can be produced by a single dissolution treatment, which is a preferred embodiment also from the viewpoint of simplicity of the process.

  Further, the ultrafine fiber generation processing (desealing treatment) can be performed by immersing a nonwoven fabric made of ultrafine fiber generation type fibers in a solvent and squeezing the liquid.

  In addition, known devices such as a continuous dyeing machine, a vibro-washer type desealer, a liquid jet dyeing machine, a Wins dyeing machine, and a Jigger dyeing machine can be used for the ultrafine fiber generation processing. Further, the ultrafine fiber generation processing can be performed before the napping treatment or can be performed after the napping treatment.

  The elastic polymer may be applied before the ultrafine fiber generation processing, or may be applied after the ultrafine fiber generation processing or after forming the hollow portion.

  N, N'-dimethylformamide, dimethylsulfoxide and the like are preferably used as a solvent used when imparting polyurethane as an elastic polymer, but it is preferable to use a water-dispersed polyurethane liquid in which polyurethane is dispersed as an emulsion in water. You can also.

  The elastic polymer is applied to the nonwoven fabric by immersing the nonwoven fabric in a solution of the elastic polymer dissolved in a solvent or the like, and then dried to substantially solidify and solidify the elastic polymer. In the case of a solvent-based polyurethane solution, it can be coagulated by dipping in an insoluble solvent, and in the case of a water-dispersible polyurethane liquid having a gelling property, a dry coagulation method of gelling and then drying is used. Can be coagulated. In drying, it is preferable to heat at a temperature that does not impair the performance of the nonwoven fabric and the elastic polymer.

  In a preferred embodiment, the sheet-like material of the present invention has at least one face raised. The napped treatment can be performed using a sandpaper or a roll sander. In particular, by using sandpaper, uniform and dense nap can be formed. Furthermore, in order to form uniform nap on the surface of the sheet, it is preferable to reduce the grinding load. In order to reduce the grinding load, it is more preferable that, for example, the number of buffing stages is multistage buffing of three or more stages, and the number of sandpaper used for each stage is in the range of No. 120 to No. 600 specified by JIS. It is.

  The sheet-like material of the present invention can contain, for example, functional agents such as dyes, pigments, softeners, anti-pilling agents, antibacterial agents, deodorants, water-repellent agents, light-proof agents, and weather-resistant agents.

  It is preferable to dye the sheet-shaped material of the present invention. As a dyeing means, a liquid jet dyeing machine is preferably used because it can soften by adding a rubbing effect while dyeing artificial leather. The dyeing temperature is preferably from 70 to 140C. When the ultrafine hollow fiber is a polyester fiber, a disperse dye is preferably used. In addition, reduction washing can be performed after dyeing.

  For the purpose of improving the uniformity of the dyeing, it is preferable to use a dyeing assistant at the time of dyeing. Furthermore, finishing treatments such as a softening agent such as silicone, an antistatic agent, a water repellent, a flame retardant, and a lightfast agent can be performed. The finishing treatment can be performed after the dyeing or in the same bath as the dyeing.

  Further, the sheet-like material of the present invention may be formed as a coating layer (silver surface layer) made of a resin and used as artificial leather with silver. As a method of forming the silver surface layer, a method of directly coating a resin on a sheet-like material or a dry surface forming method of bonding a resin film formed on release paper to the surface of the sheet-like material via an adhesive layer is used. However, it is also a preferred embodiment to combine these methods to form a laminated structure on the surface of the sheet.

The coating amount of the silver layer is preferably in the range of 30 to 300 g / m ² , and more preferably in the range of 50 to 200 g / m ² . With the above range, the balance between the mechanical characteristics and the feeling can be maintained.

  Since the sheet-like material of the present invention has flexibility, mechanical properties, and lightness, it is used for shoes, bags, sports shoes, miscellaneous goods, clothing, automobile interior materials, disc curtains for CDs and DVDs, polishing cloths, and cleaning. It is suitably used for industrial materials such as tapes and wiping cloths. Further, by forming a silver surface such as polyurethane on the surface, it can be suitably used as artificial leather with silver.

  Next, a sheet-like material of the present invention and a method for producing the same according to the present invention will be described with reference to examples. However, the present invention is not construed as being limited to such examples.

[Measurement method and processing method for evaluation]
(1) Melting point of polymer:
As the melting point, a peak top temperature indicating the melting of the polymer at 2nd run was determined as the melting point of the polymer using DSC-7 manufactured by Perkin Elmer. At this time, the heating rate was 16 ° C./min, and the sample amount was 10 mg. The measurement was performed twice, and the average value was defined as the melting point.
(2) Polymer melt flow rate (MFR):
4 to 5 g of sample pellets are put into a cylinder of an electric furnace for an MFR meter, and the amount of resin (g) extruded for 10 minutes under the conditions of a load of 2160 gf and a temperature of 285 ° C. using a melt indexer (S101) manufactured by Toyo Seiki Co., Ltd. Was measured. The same measurement was repeated three times, and the average value was set as MFR.

(3) Average single fiber diameter of microfibers in the sheet:
The average single fiber diameter was determined by observing the cross section of the single fiber with a scanning electron microscope (SEM Keyence Corporation, model VE-7800) at a magnification of 3000 times. The single fibers were randomly extracted within a visual field of 30 μm × 30 μm, and the diameters of 50 single fibers were measured. However, this was performed at three places, the diameter of a total of 150 single fibers was measured, and calculated as a number average value. When the fiber had an irregular cross-section, first, the cross-sectional area of the single fiber was measured, and the diameter of the single fiber was calculated by calculating the diameter when the cross-section was regarded as a circle.

(4) Number of hollow portions in ultrafine fibers:
The number of hollow portions was determined by observing the cross section of a single fiber at a magnification of 3000 using a scanning electron microscope (SEM). Single fibers were randomly extracted within a visual field of 30 μm × 30 μm, the number of hollow portions was obtained for 30 fibers, and the number average value thereof was calculated.

(5) Hollow Ratio The hollow ratio was determined by observing the cross section of a single fiber at a magnification of 3000 using a scanning electron microscope (SEM). The single fiber is randomly extracted within a visual field of 30 μm × 30 μm, and the total area Sa of the cross section of the single fiber for 30 fibers (the entire area within the closed curve surrounded by the outer contour of the fiber cross section, including the hollow portion) And the hollow area Sb of the single fiber cross section was measured and determined as Sb / Sa × 100 (%), and the number average value was obtained.
(6) Flexibility of artificial leather:
About the flexibility of the obtained artificial leather, the sensory evaluation was implemented by 20 healthy men and women. The artificial leather was cut into a circular shape having a diameter of 250 mm, and the tactile sensation when gripped with the palm was used to judge it in one step within the following range of 5-1 to obtain the average value of 20 persons. The evaluation result was 4 or more, and the flexibility was good.
5: Having flexibility and moderate resilience.
4: Having flexibility and resilience, but slightly less.
3: Some flexibility and little resilience.
2: Inflexibility and slight resilience. Or
It has some flexibility and no resilience.
1: Inflexible, hard, no resilience, paper-like.

(7) Product surface quality:
About the surface quality of the obtained artificial leather, the sensory evaluation was implemented by 20 healthy men and women. Evaluation was made that the nap length was uniform and the nap fiber was good in dispersibility, 5 was the best, 1 was the worst, and judged in increments of 5 to 1 They were asked and averaged by 20 people. The evaluation result was 4 or more, and the quality was good.
5: The nap length is uniform, the dispersibility is sufficient, and the touch is good.
4: The nap length was slightly disturbed, but the fibers were dispersed and the touch was good.
3: Some have long or short naps, and fibers have a slightly poor dispersion.
2: The nap fibers are disordered, the dispersion of the fibers is often poor, and the touch is poor.
1: The nap fibers are sparse, the fibers are not dispersed, and the touch is rough.

[Example 1]
<Raw cotton>
(Island component polymer)
Polyethylene terephthalate (PET) having a melting point of 260 ° C. and an MFR of 46.5 was used.

(Sea component polymer)
Polystyrene (PSt) having a Vicat softening point of 100 ° C. and an MFR of 120 measured according to JIS K7206 was used.

(Spinning / drawing)
Using the above sea component polymer and island component polymer, using a sea-island composite spinneret having 14 islands / hole, 4 sea islands / 4 sea islands, and 14 islands each having 4 sea middle sea components, spinning temperature At 285 ° C. and the mass ratio of the island component / the middle sea component / the open sea component was 47/23/30.

  Next, the film was stretched in two stages in a stretching solution bath at a temperature of 85 ° C. so that the total magnification was 2.7 times, and crimped using a stuffing box type crimper to obtain a sea-island composite fiber. The obtained sea-island composite fiber had a single fiber fineness of 3.8 dtex and a shrinkage at a temperature of 98 ° C. of 14.0%. This composite fiber was cut into a fiber length of 51 mm to obtain a raw cotton of sea-island type composite fiber.

<Non-woven fabric>
Using the above raw cotton, a laminated fiber web was formed through a card and a cross wrapper process. Next, the obtained laminated fiber web was needle-punched at a needle depth of 7 mm and a punch number of 2700 / cm ² using a needle punching machine in which one needle having a total barb depth of 0.075 mm was implanted. Then, a nonwoven fabric having a basis weight of 770 g / m ² and an apparent density of 0.198 g / cm ³ was produced.

<Sheet-like object>
After shrinking the above non-woven fabric with hot water at a temperature of 98 ° C., the non-woven fabric is impregnated with a 13% aqueous solution of PVA (polyvinyl alcohol), and dried with hot air at a temperature of 120 ° C. for 10 minutes. A nonwoven fabric having a PVA mass of 50% by mass based on the mass was obtained. The non-woven fabric thus obtained was immersed in trichlorethylene to dissolve and remove the sea component, thereby obtaining a non-woven fabric (desealed sheet) made of ultrafine fibers. The non-woven fabric (desealed sheet) made of the ultrafine fibers thus obtained is immersed in a DMF (dimethylformamide) solution of a polycarbonate-based polyurethane having a solid content adjusted to 12%, and then immersed in an aqueous solution having a DMF concentration of 30%. To coagulate the polyurethane. Thereafter, PVA and DMF are removed with hot water and dried with hot air at a temperature of 110 ° C. for 10 minutes, whereby a non-woven fabric (polyurethane-containing sheet) having a polyurethane content of 55% by mass based on the mass of the ultrafine fibers composed of island components is used. Got. Thereafter, the sheet was cut in half in the thickness direction by a cut having an endless band knife, and the non-cut face was ground in three steps using JIS # 150 sandpaper to form naps, thereby producing a sheet-like material. Furthermore, dyeing was carried out with a disperse dye using a circular dryer to obtain a sheet.
The ultrafine fibers in the obtained sheet had an average single fiber diameter of 4.4 μm and a hollow ratio of 44%. The flexibility of the sheet was 4.8 and the surface quality was 4.7. Table 1 shows the results.

[Example 2]
<Raw cotton>
(Island component polymer and sea component polymer)
The same island component polymer and sea component polymer as those used in Example 1 were used.

(Spinning / drawing)
Using the above sea component polymer and island component polymer, using 14 islands / hole, 6 middle islands / sea island type composite spinneret with 14 islands and 6 middle sea components in each island, island component A raw cotton of sea-island composite fiber was obtained in the same manner as in Example 1, except that the mass ratio of the / sea sea component / outside sea component was 39/27/34 and the fineness of the sea-island composite fiber was 6.1 dtex.

<Non-woven fabric>
Using the above raw cotton, processing was performed in the same manner as in Example 1 to produce a nonwoven fabric.

<Sheet-like object>
A sheet was obtained in the same manner as in Example 1 except that the above nonwoven fabric was used.
The ultrafine fibers in the obtained sheet had an average single fiber diameter of 5.5 μm and a hollow ratio of 50%. Further, the flexibility of the sheet-like material was 4.6, and the surface quality was 4.1, which was good.

[Example 3]
<Raw cotton>
(Island component polymer and sea component polymer)
The same island component polymer and sea component polymer as those used in Example 1 were used.

(Spinning / drawing)
Example 1 was repeated except that the above sea component polymer and island component polymer were used, the mass ratio of the island component / the middle sea component / the open sea component was 54/20/26, and the fineness of the sea-island composite fiber was 3.6 dtex. In the same manner as above, raw cotton of sea-island type composite fiber was obtained.

<Non-woven fabric>
Using the above raw cotton, processing was performed in the same manner as in Example 1 to produce a nonwoven fabric.

<Sheet-like object>
A sheet was obtained in the same manner as in Example 1 except that the above nonwoven fabric was used.
The ultrafine fibers in the obtained sheet material had an average single fiber diameter of 4.4 μm and a hollow ratio of 35%. Further, the flexibility of the sheet-like material was 4.5, and the surface quality was good at 4.5.

[Example 4]
<Raw cotton>
(Island component polymer and sea component polymer)
The same island component polymer and sea component polymer as those used in Example 1 were used.

(Spinning / drawing)
Example 1 Example 1 was repeated except that the above sea component polymer and island component polymer were used, the mass ratio of the island component / the middle sea component / the open sea component was 23/34/43, and the fineness of the sea-island composite fiber was 4.2 dtex. In the same manner as above, raw cotton of sea-island type composite fiber was obtained.

<Non-woven fabric>
Using the above raw cotton, processing was performed in the same manner as in Example 1 to produce a nonwoven fabric.

<Sheet-like object>
A sheet was obtained in the same manner as in Example 1 except that the above nonwoven fabric was used.
The ultrafine fibers in the obtained sheet material had an average single fiber diameter of 4.4 μm and a hollow ratio of 68%. The flexibility of the sheet material was 4.9, and the surface quality was good at 4.7.

[Example 5]
<Raw cotton>
(Island component polymer and sea component polymer)
The same island component polymer and sea component polymer as those used in Example 1 were used.

(Spinning / drawing)
Using the sea component polymer and the island component polymer described above, using a sea-island composite spinneret having 14 islands / holes and 48 middle islands / 48 islands, each having 14 seas and 48 seas in each island. A raw cotton of sea-island composite fiber was obtained in the same manner as in Example 1, except that the mass ratio of / sea sea component / outside sea component was 39/27/34 and the fineness of the sea-island composite fiber was 3.9 dtex.

<Non-woven fabric>
Using the above raw cotton, processing was performed in the same manner as in Example 1 to produce a nonwoven fabric.

<Sheet-like object>
A sheet was obtained in the same manner as in Example 1 except that the above nonwoven fabric was used.
The ultrafine fibers in the obtained sheet material had an average single fiber diameter of 4.4 μm and a hollow ratio of 50%. Further, the flexibility of the sheet-like material was 4.7, and the surface quality was good at 4.6.

[Example 6]
<Raw cotton>
(Island component polymer and sea component polymer)
The same island component polymer and sea component polymer as those used in Example 1 were used.

(Spinning / drawing)
Using the above sea component polymer and island component polymer, the island component is obtained by using a sea-island composite spinneret having 38 islands and 6 middle sea components each having 6 seas in each island. A raw cotton of sea-island composite fiber was obtained in the same manner as in Example 1, except that the mass ratio of the / sea sea component / outer sea component was 44/25/31 and the fineness of the sea-island composite fiber was 3.4 dtex.

<Non-woven fabric>
Using the above raw cotton, processing was performed in the same manner as in Example 1 to produce a nonwoven fabric.

<Sheet-like object>
A sheet was obtained in the same manner as in Example 1 except that the above nonwoven fabric was used.
The ultrafine fibers in the obtained sheet had an average single fiber diameter of 2.5 μm and a hollow ratio of 45%. The flexibility of the sheet was 4.6, and the surface quality was 4.6.

[Example 7]
<Raw cotton>
(Island component polymer)
Nylon 6 having a melting point of 220 ° C. and an MFR of 58.0 was used as an island component polymer.

(Sea component polymer)
The same sea component polymer as used in Example 1 was used.

(Spinning / drawing)
Raw cotton of sea-island type composite fiber was obtained in the same manner as in Example 1 except that the above sea component polymer and island component polymer were used.

<Non-woven fabric>
Using the above raw cotton, processing was performed in the same manner as in Example 1 to produce a nonwoven fabric.

<Sheet-like object>
Using the above non-woven fabric, artificial leather obtained in the same manner as in Example 1 was treated with a gold-containing dye ("Irgalan" Red 2GL) [manufactured by Ciba Specialty Chemicals] at 4.0% owf, bath ratio 1: 100, pH = 7, temperature 90 ° C, time 60 minutes, washed with water and dried to obtain dyed artificial leather.
The ultrafine fibers in the obtained sheet had an average single fiber diameter of 4.4 μm and a hollow ratio of 44%. Further, the flexibility of the sheet-like material (product) was 4.6, and the surface quality was 4.2.

Example 8
<Raw cotton>
(Island component polymer)
The same island component polymer as that used in Example 7 was used.

(Sea component polymer)
PET obtained by copolymerizing 8.5 mol% of sodium 5-sulfoisophthalate having a melting point of 240 ° C. and an MFR of 100 was used.

(Spinning / drawing)
Raw cotton of sea-island type composite fiber was obtained in the same manner as in Example 1 except that the above sea component polymer and island component polymer were used.

<Non-woven fabric>
Using the above raw cotton, processing was performed in the same manner as in Example 1 to produce a nonwoven fabric.

<Sheet-like object>
Dyeing after dyeing was carried out in the same manner as in Example 7 except that the above nonwoven fabric was treated for 30 minutes with a 20 g / L aqueous sodium hydroxide solution heated to a temperature of 90 ° C. to dissolve and remove sea components. A sheet was obtained.
The ultrafine fibers in the obtained sheet had an average single fiber diameter of 4.4 μm and a hollow ratio of 44%. The flexibility of the sheet was 4.2, and the surface quality was 4.1.

[Comparative Example 1]
<Raw cotton>
(Island component polymer and sea component polymer)
The same island component polymer and sea component polymer as those used in Example 1 were used.

(Spinning / drawing)
Example 1 was repeated except that the sea component polymer and the island component polymer were used, the mass ratio of the island component / the middle sea component / the open sea component was 72/12/16, and the fineness of the sea-island composite fiber was 3.3 dtex. In the same manner as above, raw cotton of sea-island type composite fiber was obtained.

<Non-woven fabric>
Using the above raw cotton, processing was performed in the same manner as in Example 1 to produce a nonwoven fabric.

<Sheet-like object>
A sheet was obtained in the same manner as in Example 1 except that the above nonwoven fabric was used.
The ultrafine fibers in the obtained sheet material had an average single fiber diameter of 4.4 μm and a hollow ratio of 20%. The flexibility of the sheet was 3.4, and the surface quality was 4.3, which was poor.

[Comparative Example 2]
<Raw cotton>
(Island component polymer and sea component polymer)
The same island component polymer and sea component polymer as those used in Example 1 were used.

(Spinning / drawing)
Using the above sea component polymer and island component polymer, the island component is obtained by using a sea-island composite spinneret having 14 islands / hole and 1 / inland sea, each having 14 islands and one sea in each island. The raw cotton of the sea-island composite fiber was obtained in the same manner as in Example 1, except that the mass ratio of the / sea sea component / outside sea component was 39/27/34 and the fineness of the sea-island composite fiber was 3.9 tex. Non-woven fabric>
Using the above raw cotton, processing was performed in the same manner as in Example 1 to produce a nonwoven fabric.

<Sheet-like object>
A sheet was obtained in the same manner as in Example 1 except that the above nonwoven fabric was used.
The ultrafine fibers in the obtained sheet material had an average single fiber diameter of 4.4 μm and a hollow ratio of 50%. The flexibility of the sheet was 3.3, and the surface quality was 4.2, which was poor.

[Comparative Example 3]
<Raw cotton>
(Island component polymer and sea component polymer)
The same island component polymer and sea component polymer as those used in Example 1 were used.

(Spinning / drawing)
Using the above sea component polymer and island component polymer, the mass ratio of the island component / sea component is set to 80 using a 16 islands / hole sea-island composite spinneret having 16 islands and no island component in each island. The raw cotton of the sea-island composite fiber was obtained in the same manner as in Example 1 except that the fineness of the sea-island composite fiber was 4.2 tex.

<Non-woven fabric>
Using the above raw cotton, processing was performed in the same manner as in Example 1 to produce a nonwoven fabric.

<Sheet-like object>
A sheet was obtained in the same manner as in Example 1 except that the above nonwoven fabric was used.
The ultrafine fibers in the obtained sheet had an average single fiber diameter of 4.4 μm. The flexibility of the sheet was 3.6, and the surface quality was 3.8, which was poor.

[Comparative Example 4]
<Raw cotton>
(Island component polymer and sea component polymer)
The same island component polymer and sea component polymer as those used in Example 1 were used.

(Spinning / drawing)
Using the above sea component polymer and island component polymer, the island component is formed using a sea-island composite spinneret having 10 islands / hole and 6 middle seas / 6 islands, each having 10 middle sea components in each of 10 islands. A raw cotton of sea-island type composite fiber was obtained in the same manner as in Example 1, except that the mass ratio of the / sea sea component / outside sea component was 50/35/15 and the fineness of the sea-island type composite fiber was 13.4 tex. Non-woven fabric>
Using the above raw cotton, processing was performed in the same manner as in Example 1 to produce a nonwoven fabric.

<Sheet-like object>
A sheet was obtained in the same manner as in Example 1 except that the above nonwoven fabric was used.
The ultrafine fibers in the obtained sheet material had an average single fiber diameter of 11 μm and a hollow ratio of 50%. The flexibility of the sheet material was 3.5, and the surface quality was 2.5, which was not excellent in touch on the surface.

[Comparative Example 5]
<Raw cotton>
(Island component polymer and sea component polymer)
The same island component polymer and sea component polymer as those used in Example 1 were used.

(Spinning / drawing)
Using the above sea component polymer and island component polymer, using 14 islands / hole, 6 middle islands / sea island type composite spinneret with 14 islands and 6 middle sea components in each island, island component The raw cotton of the sea-island composite fiber was obtained in the same manner as in Example 1 except that the mass ratio of the / sea sea component / outer sea component was 15/60/25 and the fineness of the sea-island composite fiber was 3.0 tex. Non-woven fabric>
Using the above raw cotton, processing was performed in the same manner as in Example 1 to produce a nonwoven fabric.

<Sheet-like object>
A sheet was obtained in the same manner as in Example 1 except that the above nonwoven fabric was used.
The ultrafine fibers in the obtained sheet had an average single fiber diameter of 4.4 μm and a hollow ratio of 85%. The flexibility of the sheet was 3.2 and the surface quality was 4.1, which was poor.

INDUSTRIAL APPLICABILITY The present invention can be suitably used for applications such as shoes, bags, and sports shoes.

Claims (3)

  It is a sheet-like material having a nonwoven fabric mainly composed of ultrafine hollow fibers having an average single fiber diameter in the range of 0.05 to 10 μm and an elastic polymer as components, and the ultrafine hollow fibers extend in the fiber longitudinal direction inside thereof. Having a hollow portion, the hollow portion can be observed 2 to 60 when the cross section of the ultrafine hollow fiber is observed, and the total area of the hollow portion in the cross section is the cross section of the cross section A sheet-like material characterized by having an area of 30 to 80%.   The sheet-like article according to claim 1, wherein the average single fiber diameter of the ultrafine hollow fibers is in a range of 0.1 to 6 µm.   3. The sheet according to claim 1, wherein the sheet is artificial leather having naps on at least one surface.