JP2012136800A - Leather-like sheet-shaped material and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for efficiently producing an eco-friendly leather-like sheet-shaped material having excellent thermal retaining properties during wearing or clothing in a production process considering environments in which an organic solvent is not used.SOLUTION: The leather-like sheet-shaped material contains a nonwoven fabric including ultra fine fibers having an average single fiber diameter of 0.3 μm or more and 7 μm or less, and a sheet-shaped material containing a water dispersion type polyurethane therein. The sheet-shaped material has a substrate layer and a piloerection layer, and a fiber density of ultrafine fibers constituting each layer satisfies the following relational expression: 2>fiber density of the piloerection layer/fiber density of the substrate layer>0.5.

Description

  The present invention relates to a leather-like sheet-like material excellent in heat retention during wearing and wearing, and environmentally friendly, and a method for producing the same.

  A leather-like sheet-like material mainly composed of ultrafine fibers and a polymer elastic body has excellent characteristics not found in natural leather, and its use has been expanded year by year for apparel, chair upholstery and automotive interior materials. Particularly in clothing applications, since it is often used as winter clothing, there is a demand for leather-like sheet-like materials that are excellent in heat retention during wearing or wearing.

  In general, a textile product having excellent functions and performances related to heat retention needs to secure an air layer for heat insulation and control the entry and exit of energy. For such a problem, for example, it has been proposed to apply a hollow fiber as a fiber (see Patent Document 1). However, if the hollow fiber can maintain its shape, it is lightweight and can retain heat, but generally it is easily crushed by external physical force, making it difficult to maintain the hollow structure and stable. There is a problem that it is difficult to obtain a warm feeling.

  Separately, a technique has been proposed in which at least one surface of a fiber fabric contains high-moisture-release moisture-absorbing exothermic organic fine particles to generate heat (see Patent Document 2). However, this proposal has a problem that it is difficult to obtain stable heat retaining performance because heat cannot be generated when the air is dry.

  On the other hand, in producing a leather-like sheet, after impregnating a nonwoven fabric with an organic solvent solution of polyurethane as a polymer elastic body, the resulting nonwoven fabric is immersed in water or an organic solvent solution that is a non-solvent of polyurethane. A method of wet coagulating polyurethane is generally employed. However, since organic solvents are highly harmful to the human body and the environment, in recent years, in the production of leather-like sheets, polyurethane water in which polyurethane is dispersed in water instead of conventional organic solvent type polyurethane is used. Methods using dispersion liquids have been studied.

  However, the history of studying an environment-friendly leather-like sheet that does not use an organic solvent in the manufacturing process is short, and the technology for enhancing its function has not been well established. In particular, a useful practical technique for imparting heat retention during wearing or wearing has not been proposed yet.

JP 2010-018907 A JP 2000-199180 A

  Accordingly, an object of the present invention is to provide a leather-like sheet-like material that is excellent in heat retention during wearing or wearing and is environmentally friendly in view of the background of the above-described prior art.

  Another object of the present invention is to provide a method for efficiently producing a leather-like sheet-like material having the above characteristics in an environment-friendly process that does not use an organic solvent in the production process by using a polyurethane water dispersion. There is.

  In order to achieve the above-mentioned object, the present inventors have conducted intensive research, and as a result, it is possible to obtain a leather-like sheet-like material that is excellent in heat retention during wearing and wearing and is environmentally friendly. I found.

  That is, the leather-like sheet-like material of the present invention is a sheet-like material containing a nonwoven fabric composed of ultrafine fibers having an average single fiber diameter of 0.3 μm or more and 7 μm or less, and water-dispersible polyurethane therein. The leather-like sheet-like material is characterized in that the material has a base layer and a raised layer, and the fiber density of the ultrafine fibers constituting each layer satisfies the following relational expression.

2> Napped layer fiber density / Base layer fiber density> 0.5
According to a preferred embodiment of the leather-like sheet-like material of the present invention, the ultrafine fibers are obtained by bonding two or more types of polyethylene terephthalate polymers having different intrinsic viscosities in a side-by-side manner along the fiber length direction. It is an eccentric core-sheath composite fiber in which a core-sheath structure in which two or more types of polyethylene terephthalate polymers having a difference in intrinsic viscosity and / or intrinsic viscosity are eccentric is formed.

  According to a preferred aspect of the leather-like sheet-like material of the present invention, the napping of the napped layer has crimps.

In addition, the method for producing a leather-like sheet of the present invention is such that two or more types of polyethylene terephthalate polymers having different intrinsic viscosities obtained from ultrafine fiber-expressing fibers are converted into side-by-side types along the fiber length direction. A non-woven fabric having a base material layer and a raised layer composed of superfine fibers having a laminated structure and / or an eccentric core-sheath structure, and a method for producing a sheet-like material containing water-dispersible polyurethane therein, (1) and the process of (2) are included in this order, The manufacturing method of the leather-like sheet-like thing characterized by the above-mentioned.
(1) a step of expressing ultrafine fibers from a nonwoven fabric composed of ultrafine fiber-expressing fibers,
(2) A step of causing crimps in the ultrafine fibers of the napped layer by subjecting the nonwoven fabric made of ultrafine fibers to a heat treatment at a temperature of 110 ° C. to 150 ° C.

  According to a preferred embodiment of the method for producing a leather-like sheet of the present invention, the ultrafine fiber expression type fiber is a sea-island type composite fiber.

  According to a preferred embodiment of the method for producing a leather-like sheet of the present invention, the nonwoven fabric is a nonwoven fabric composed of short fibers.

  According to the present invention, a leather-like sheet-like material that is excellent in heat retention during wearing and wearing and that uses an aqueous polyurethane dispersion that does not use an organic solvent in the production process can be obtained.

  Here, the heat retaining property is an index indicating the total warmth that humans feel when wearing clothing. As will be described later, the environment in which the sample is placed starts from a temperature of 25 ° C. and a humidity of 40% RH. When the temperature is changed to 27 ° C. and humidity 80% RH, the temperature difference is expressed as the value of the temperature and humidity control effect.

  The leather-like sheet-like material of the present invention is a leather-like sheet-like material containing a nonwoven fabric composed of ultrafine fibers having an average single fiber diameter of 0.3 μm or more and 7 μm or less, and water-dispersible polyurethane therein.

  The leather-like sheet-like material in the present invention has a smooth touch and an excellent lighting effect in a raised appearance such as suede or nubuck like natural leather.

  In the present invention, the ultrafine fibers constituting the non-woven fabric used in the leather-like sheet are, for example, polyester-based weights such as polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate, and polyethylene-2,6-naphthalenedicarboxylate. Various synthetic fibers made of polymers such as polymers, polyamide polymers such as 6-nylon and 66-nylon, acrylic polymers, polyethylene polymers and polypropylene polymers can be used, and combinations thereof can also be used. May be. Among them, polyester fibers made of polyester polymers such as polyethylene terephthalate, polybutylene terephthalate and polytrimethylene terephthalate are preferably used from the viewpoints of strength, dimensional stability, light resistance and dyeability, and particularly from polyethylene terephthalate polymers. An ultrafine fiber is preferable.

  The average single fiber diameter of the ultrafine fibers constituting the leather-like sheet of the present invention is 0.3 μm or more and 7 μm or less. By setting the average single fiber diameter of the ultrafine fibers to 7 μm or less, more preferably 5.5 μm or less, and even more preferably 4.5 μm or less, a sheet-like product excellent in flexibility and napped quality can be obtained. On the other hand, when the average single fiber diameter of the ultrafine fibers is 0.3 μm or more, more preferably 0.65 μm or more, and even more preferably 1 μm or more, a sheet-like product having excellent color developability after dyeing can be obtained, and raising treatment Excellent dispersibility and easy handling of fibers.

  The ultrafine fiber constituting the leather-like sheet of the present invention is a composite fiber and / or intrinsic viscosity in which two or more types of polyethylene terephthalate polymers having a difference in intrinsic viscosity are bonded side by side along the fiber length direction. It is preferable that two or more types of polyethylene terephthalate polymers having a difference are made of an eccentric core-sheath composite fiber forming an eccentric core-sheath structure. Ultrafine fibers obtained by spinning and drawing to form a structure in which polyethylene terephthalate polymers having different intrinsic viscosities are bonded side-by-side along the fiber length direction and / or an eccentric core-sheath structure, Due to stress concentration on the high viscosity side, different internal strains occur between the two components. Due to this internal strain, when the sheet is formed and heat-treated at a temperature of 110 ° C. or higher as described later, the high-viscosity side contracts greatly, strain occurs in the single fiber, and crimps appear. By this crimping, the fiber density of the napped layer portion on the surface of the sheet-like material is increased, and high heat retention is obtained for the sheet-like material.

  The composite fiber and the eccentric core-sheath composite fiber bonded to the side-by-side type are preferably composed of two types of polyethylene terephthalate polymers as described above, and the intrinsic viscosity difference between the two types of polyethylene terephthalate polymers is 0. It is preferable that it is 2 or more and 1.0 or less. When the difference in intrinsic viscosity is increased by 0.2 or more, a fiber having excellent crimp characteristics can be obtained. On the other hand, if the intrinsic viscosity difference exceeds 1.0, the crimped property of the obtained fiber is good, but the spun fiber is bent excessively to the high viscosity component side, so that the yarn is stably produced for a long time. There are times when you can't.

  In the present invention, the intrinsic viscosity of the polyethylene terephthalate polymer is preferably in the range of 0.50 to 1.50 in the high viscosity component. By setting the intrinsic viscosity to 0.50 or more, a fiber having sufficient strength and elongation can be produced. The upper limit of the intrinsic viscosity is preferably 1.50 or less from the viewpoint of ease of molding such as melt extrusion, and from the viewpoint of production cost and molecular weight reduction caused by molecular chain breakage caused by heat or shear force during the process. On the other hand, the low-viscosity component can obtain stable yarn-making properties by setting the intrinsic viscosity to 0.30 or more and 1.00 or less.

  The composite ratio of both components is preferably in the range of high viscosity component: low viscosity component = 75: 25 to 35:65 (mass%), more preferably 65:35 to 45:55 (mass%). ). Within this range, the composite ratio can be appropriately set according to the purpose of heat retention of the sheet-like material to be obtained.For example, in order to obtain a sheet-like material having an excellent soft feeling, The composite ratio difference of the low-viscosity component may be set large, and the composite ratio of the high-viscosity component may be set high compared to the low-viscosity component in order to obtain toughness.

  The intrinsic viscosity difference of the polyethylene terephthalate polymer can be adjusted to a desired viscosity by appropriately adjusting the polymerization time, temperature, catalyst amount and copolymerization component.

  The intrinsic viscosity in the present invention is a value measured at a temperature of 25 ° C. by dissolving a sample in orthochlorophenol, as will be described later.

  In addition, the polyethylene terephthalate polymer referred to in the present invention is mainly composed of a structure obtained by copolymerizing terephthalic acid or a derivative thereof and ethylene glycol or a derivative thereof. More than 50% by weight relative to the total weight. The polyethylene terephthalate polymer may include a copolymer component capable of forming another ester bond. Examples of the copolymerizable compound include dicarboxylic acids such as isophthalic acid, succinic acid, cyclohexanedicarboxylic acid, adipic acid, dimer acid, sebacic acid and sodium 5-isophthalate, ethylene glycol, diethylene glycol, butanediol, neopentyl. Examples include diols such as glycol, cyclohexanedimethanol, polyethylene glycol and polypropylene glycol. Further, if necessary, titanium dioxide serving as a matting agent, silica or alumina fine particles as a lubricant, hindered phenol derivatives and coloring pigments as an antioxidant may be added.

  The ultrafine fibers constituting the leather-like sheet of the present invention are preferably composed of the above-mentioned polyethylene terephthalate polymer because they have the most appropriate characteristics in the production of a sheet-like material having excellent heat retention. For example, when a sheet-like material is produced using ultrafine fibers using polytrimethylene terephthalate, polytrimethylene terephthalate has a property sensitive to heat, and thus easily contracts due to heat. For this reason, when processing is performed by applying this sheet-like material, crimping occurs in an unintended process due to heat applied during the processing, and as a result, the sheet-like material is poor in heat retention. On the other hand, since the composite fiber using polyethylene terephthalate develops crimps at a relatively high temperature, it can prevent crimping in unintended steps, and a sheet-like material having excellent heat retention can be obtained. . Moreover, since the composite fiber which consists of a polyethylene terephthalate type polymer has a resilience, when it is made into a sheet-like material, there is a moderate resilience and a good hand feeling can be obtained.

  Regarding the uniformity of the single fiber fineness of the ultrafine fibers constituting the leather-like sheet of the present invention, the fineness CV in the fiber bundle is preferably 10% or less. Here, the fineness CV is a percentage (%) value obtained by dividing the fineness standard deviation of the fibers constituting the fiber bundle by the average fineness within the bundle, and indicates that the smaller the value, the more uniform. . By reducing the fineness CV to 10% or less and the fineness CV, the appearance of napping on the surface of the leather-like sheet material of the present invention becomes graceful, and the dyeing can be made uniform and good. The fineness CV when the cross section of the ultrafine fiber is not a circle or an ellipse close to a circle is obtained by the same method as the calculation of the average single fiber fineness.

  The cross-sectional shape of the ultrafine fiber used in the present invention may be a round cross section, but may be a polygonal shape such as an ellipse, a flat shape, and a triangular shape, or an irregular cross section such as a sector shape and a cross shape. When the cross-sectional shape of the ultrafine fibers constituting the nonwoven fabric is an irregular cross-section, the outer peripheral circular diameter of the irregular cross-section is calculated as the fiber diameter.

  The non-woven fabric used in the leather-like sheet of the present invention may be either a non-woven fabric made of short fibers or a non-woven fabric made of long fibers. However, when emphasizing the texture and quality, a non-woven fabric made of short fibers is preferably used. .

  It is preferable that the fiber length of the short fiber in the nonwoven fabric made of the short fiber used in the present invention is 25 to 90 mm. By setting the fiber length to 90 mm or less, a leather-like sheet material excellent in texture and quality can be obtained. Further, by setting the fiber length to 25 mm or more, a leather-like sheet-like material having excellent wear resistance due to entanglement can be obtained. Moreover, it is a preferable aspect to crimp the short fiber in the short fiber nonwoven fabric because a good entangled state can be obtained. The fiber length of the short fiber is more preferably 35 to 80 mm.

The apparent density of the nonwoven fabric used in the present invention is preferably 0.10 to 0.60 g / cm ³ . If the apparent density of the non-woven fabric is within the above range, the non-woven fabric structure will be uniform, and it will be possible to avoid an extremely large variation in quality in the area direction, and the physical properties and texture of the resulting leather-like sheet will be good It becomes. The nonwoven fabric may be subjected to shrinkage treatment by warm water or steam treatment in order to improve the fineness of the fibers. Also in this case, in order to obtain a uniform and dense fiber entangled structure, the apparent density is preferably in the above range. The apparent density of the nonwoven fabric is more preferably 0.15 to 0.55 g / cm ³ .

  In addition, the nonwoven fabric used in the present invention may be configured by mixing ultrafine fibers of different materials, and for the purpose of improving the strength, a woven fabric or a knitted fabric is inserted inside the nonwoven fabric, May be laminated. The average single fiber diameter of the fibers constituting the woven fabric or knitted fabric is preferably 0.1 μm or more and 20 μm or less because of the entanglement with the ultrafine fibers constituting the nonwoven fabric.

  Examples of the type of fiber yarn constituting the woven or knitted fabric used in the present invention include filament yarn, spun yarn, innovative spun yarn, and mixed composite yarn of filament yarn and spun yarn. Since the spun yarn has many fluffs on the surface due to its structure and when the nonwoven fabric and the woven fabric are entangled with each other, it becomes a drawback if the fluff falls off and is exposed on the surface. Therefore, it is preferable to use a filament yarn. The filament yarn is roughly classified into a monofilament composed of a single fiber and a multifilament composed of a plurality of filament yarns. In the woven or knitted fabric used in the present invention, it is preferable to use a multifilament. In the case of monofilaments, the texture of the leather-like sheet may be impaired because the rigidity of the fibers becomes too high.

  The total fineness of the fiber yarn constituting the woven or knitted fabric is preferably 50 dtex to 150 dtex for reasons such as rigidity and basis weight.

Basis weight of the woven or knitted fabric is preferably 20 to 200 g / ^{m 2,} more preferably from 30 to 150 g / ^{m 2.} When the basis weight of the woven or knitted fabric is less than 20 g / m ² , the shape of the woven or knitted fabric becomes very loose. When the woven or knitted fabric is sandwiched between the nonwoven fabric and the middle layer of the nonwoven fabric, or when the woven or knitted fabric is stacked on the nonwoven fabric surface, Tends to occur and it becomes difficult to spread uniformly. Further, when the basis weight of the woven / knitted fabric exceeds 200 g / m ² , the woven / knitted fabric has a dense structure, and the nonwoven fabric and the woven / knitted fabric are not sufficiently entangled with each other, so that the nonwoven fabric and the woven / knitted fabric are not entangled. Building a structure generally tends to be difficult.

  In the fabric used in the present invention, a plain structure is preferably used as a basic structure. Twill and satin may be used as the fabric structure. However, because of the anisotropy of the structure, the behavior is different with respect to the external force in the oblique direction. Tissue is preferably used.

  Examples of the knitted fabric include a weft knitting represented by warp knitting and a tricot knitting, a lace knitting, and various knittings based on the knitting method.

  In the present invention, such a nonwoven fabric is impregnated with a water-dispersed polyurethane liquid as an elastic resin binder so that the water-dispersible polyurethane is present in the interior space of the nonwoven fabric.

  It is important that the polyurethane used in the present invention is water-dispersed polyurethane rather than organic solvent-based polyurethane. The water-dispersible polyurethane liquid is preferable from the viewpoint of environmental protection in that it does not require the use of an organic solvent, and the present invention has an object to provide a leather-like sheet-like material having excellent heat retention using the water-dispersible polyurethane liquid. .

  The water-dispersed polyurethane used in the present invention is usually handled in a state where the polyurethane is dispersed in water, and can also be obtained in this state from the manufacturer of the polyurethane. This is because once dried, it cannot be dispersed again in water.

  As the water-dispersible polyurethane, those having a structure in which a polymer diol, polyisocyanate, a chain extender and an internal crosslinking agent are appropriately reacted can be used.

  Examples of the polymer diol include polyester diol, polyether diol, and polycarbonate diol. Examples of the polyester diol include polyadipic acid such as polyhexamethylene adipate and polyneopentyl adipate, polycaprolactone, and the like. Examples of the polyether diol include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and poly (methyltetramethylene glycol). These can be used alone or in combination.

  Examples of the polycarbonate diol include polyalkylene carbonate polyols obtained by reacting glycols such as hexanediol and neopentyl glycol with alkyl carbonates or phosgene.

  The polymer diol can be used alone or in combination, and a copolymerized polymer diol obtained by mixing raw materials at the time of polymerization can also be suitably used.

  The molecular weight of the polymer diol is preferably 500 to 10,000 in terms of number average molecular weight, more preferably 700 to 5000, and still more preferably 1000 to 3000.

  In addition, by setting the number of hydroxyl groups per molecule of the polymer diol to 2 or more, a crosslinked structure can be introduced into the water-dispersed polyurethane.

  In addition, as required, polyalkylene glycols such as polyoxyethylene glycol, polyoxyethylene propylene glycol and polyoxyethylene tetramethylene glycol, ethylene glycol, propylene glycol, 1,4-butanediol, trimethylol, etc. Low molecular weight polyhydric alcohols such as propane, glycerin, pentaerythritol and sorbitol, low molecular weight alkylene polyamines such as ethylenediamine, diethylenetriamine and triethylenetetramine, ethylene oxide alone or ethylene oxide and propylene oxide, and alkylene oxides such as butylene oxide One or two or more hydrophilic components added can be mixed with a polymer diol and used.

  Moreover, as a diisocyanate used when superposing | polymerizing a water dispersion type polyurethane, what is known conventionally can be used, for example, isophorone diisocyanate, tolylene diisocyanate, 4,4'- diphenylmethane diisocyanate, p -Mentioning -phenylene diisocyanate, 1,5-naphthylene diisocyanate, xylylene diisocyanate, hexamethylene diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, 3,3'-dichloro-4,4'-diphenylmethane diisocyanate and norborane diisocyanate These can be used alone or in combination.

  Moreover, as a chain extender used when polymerizing water-dispersed polyurethane, a low molecular compound containing two or more active hydrogens capable of reacting with an isocyanate group can be used. Examples thereof include hydrazine, ethylenediamine, propylene. Examples thereof include diamines such as diamine, isophorone diamine, piperazine, and derivatives thereof, phenylene diamine, tolylenediamine, xylylenediamine, adipic acid dihydrazide, isophthalic acid dihydrazide, hexamethylenediamine, and 4,4′-dicyclohexylmethanediamine.

  For water-dispersed polyurethane liquids, water resistance such as polyester, polyamide, polyolefin, silicone and polyurethane, pigments such as dyes and carbon black, anti-fungal agents, antioxidants and UV absorbers as necessary. Agents, flame retardants, penetrants and lubricants, antiblocking agents such as silica and titanium oxide, antistatic agents, antibacterial agents, deodorants, antifoaming agents such as silicone oil, fillers such as cellulose, and polyurethane coagulation regulators Etc. may be used.

  The water-dispersed polyurethane liquid preferably has a heat-sensitive gelling property. The heat-sensitive gelation property means a property that loses fluidity when heated and becomes a gel. Migration can be suppressed by impregnating the water-dispersed polyurethane liquid and then heating to cause gelation, thereby losing the fluidity of the water-dispersed polyurethane liquid. Thereby, it can suppress that water dispersion type polyurethane is unevenly distributed in a nonwoven fabric, and can obtain favorable surface quality and a flexible texture. By having the heat-sensitive gelation property, it is possible to suppress the polyurethane migration phenomenon when the nonwoven fabric is impregnated and heat-dried.

  The heat-sensitive gelation temperature of the water-dispersed polyurethane liquid is preferably 50 to 100 ° C. By setting the thermal gelation temperature to 100 ° C. or less, the migration phenomenon can be efficiently suppressed. In addition, by setting the thermal gelation temperature to 50 ° C. or higher, as described later, it is possible to prevent thermal gelation from starting immediately at the time when the nonwoven fabric is impregnated with the water-dispersed polyurethane liquid. Stable storability can be obtained.

  The water-dispersed polyurethane liquid preferably has a heat-sensitive gelling property alone, but calcium chloride, sodium sulfate is used for the purpose of imparting heat-sensitive gelling property to the water-dispersible polyurethane liquid or lowering the heat-sensitive gelation temperature. In addition, inorganic salts such as potassium sulfate may be added.

  The concentration of the water-dispersed polyurethane liquid (content of the water-dispersed polyurethane with respect to the water-dispersed polyurethane liquid) is determined from the viewpoint of storage stability of the water-dispersed polyurethane liquid and migration phenomenon suppression when the nonwoven fabric is impregnated and dried. 15-45 mass% is preferable.

  The content (adhesion amount) of the water-dispersed polyurethane with respect to the fibers in the sheet-like product is preferably 20 to 200% by mass. By setting the adhesion amount to 20% by mass or more, more preferably 30% by mass or more, it is possible to obtain the strength of the leather-like sheet and to prevent the fibers from falling off. Moreover, by making the amount of adhesion 200 mass% or less, More preferably 180 mass% or less, it is possible to prevent the texture of the leather-like sheet material from becoming harder than necessary.

  In the present invention, the water-dispersed polyurethane may be used alone or in combination of two or more kinds, and other polymers may be used in combination. Examples of other polymers include water-dispersible and water-soluble polymers such as acrylic and silicone.

  The leather-like sheet material of the present invention has a base material layer and a raised layer, and the fiber density constituting each layer satisfies the following relational expression.

2> Napped layer fiber density / Base layer fiber density> 0.5
The leather-like sheet material satisfying the above relational expression has a composite fiber in which two or more types of polyethylene terephthalate polymers having a difference in intrinsic viscosity are bonded side by side along the fiber length direction and / or has a difference in intrinsic viscosity. As described later, a heat treatment at a temperature of 110 ° C. or higher and 150 ° C. or lower is performed on a nonwoven fabric made of ultrafine fibers made of an eccentric core-sheath composite fiber forming a core-sheath structure in which two or more types of polyethylene terephthalate polymers are eccentric. Thus, crimps are expressed in the ultrafine fibers, and the napped layer fiber density is improved. When the heat treatment temperature is lower than 110 ° C., no crimp is developed in the ultrafine fibers, and the napped layer fiber density is not improved. Therefore, it is difficult to obtain a leather-like sheet material that does not satisfy the relational expression and has excellent heat retention.

  Further, the higher the heat treatment temperature, the easier the crimping of the ultrafine fibers proceeds, and the napped layer fiber density improves, but if the napped layer fiber density / base layer fiber density value exceeds 2, the ultrafine fibers constituting the napped layer are increased. The dispersibility of the fibers is deteriorated, and a smooth touch such as suede or nubuck cannot be obtained in the raised appearance. By setting the heat treatment temperature to 150 ° C. or lower, deterioration of the dispersibility of the ultrafine fibers constituting the napped layer can be prevented.

  In the present invention, the raised layer is a layer formed by the fibers in which the sheet-like material is raised, and the base material layer is a layer other than the raised layer of the sheet-like material. In the present invention, it is important that the fiber density constituting the base material layer and the napped layer satisfies the above relational expression. By satisfying this condition, the air layer is secured and maintained in the napped portion, and is worn. It is possible to obtain a leather-like sheet-like material having excellent heat retention during time and wearing.

  The leather-like sheet material of the present invention contains functional agents such as dyes, pigments, softeners, texture modifiers, anti-pilling agents, antibacterial agents, deodorants, water repellents, light proofing agents, and weathering agents. May be included.

  Next, the manufacturing method of the leather-like sheet material of this invention is demonstrated.

  As a means for obtaining ultrafine fibers constituting the nonwoven fabric used in the leather-like sheet material of the present invention, ultrafine fiber expression type fibers can be used. After the ultrafine fiber expression type fiber is entangled into a nonwoven fabric in advance, the nonwoven fabric formed by entanglement of the ultrafine fibers can be obtained by performing ultrafine fiber formation.

  As the ultrafine fiber expression type fiber, it is possible to adopt a sea-island type composite fiber in which a thermoplastic polymer component having different alkali solubility is used as a sea component and an island component, and the island component is formed as an ultrafine fiber by dissolving and removing the sea component. it can. The sea-island type composite fiber can provide an appropriate gap between island components, that is, between the ultrafine fibers in the fiber bundle by removing the sea component, and the ultrafine fiber having a particularly small fiber diameter from each composite fiber. It is preferably used because the fibers can be efficiently expressed and a soft texture or bulkiness can be imparted to the sheet-like material.

  For the sea-island type composite fiber, a sea-island type composite base is used, and a polymer inter-array system in which two components, the sea component and the island component, are spun together, and the two components, the sea component and the island component, are mixed. A mixed spinning system for spinning can be used, but a sea-island type composite fiber by a polymer array system is preferably used in that ultrafine fibers having a uniform fineness can be obtained.

  Moreover, it is preferable that the mass ratio of the sea component and the island component in the sea-island composite fiber used in the present invention is in the range of sea component: island component = 5: 95 to 80:20. When the mass ratio of the sea component is less than 5% by mass, the island component is not sufficiently thinned. Further, when the mass ratio of the sea component exceeds 80 mass%, the productivity is lowered because the ratio of the eluted component is large. The mass ratio of the sea component and the island component is more preferably in the range of sea component: island component = 10: 90 to 60:40.

  In the present invention, when drawing an ultrafine fiber expression type fiber typified by a sea-island type composite fiber, after winding the undrawn yarn once, it is drawn separately, or the undrawn yarn is taken up and drawn continuously. Any method can be employed, such as. Stretching can be appropriately performed by a method of stretching by one to three stages by wet heat, dry heat, or both. Next, the stretched sea-island type composite fiber is preferably crimped and cut into a predetermined length to obtain a raw nonwoven fabric. A usual method can be used for crimping and cutting.

  The obtained raw cotton made of an ultrafine fiber expression type fiber is made into a fiber web with a cross wrapper or the like, and then the ultrafine fiber expression type fiber is entangled to make a nonwoven fabric. As a method for obtaining a nonwoven fabric by entanglement of ultrafine fiber-expressing fibers, a usual method such as needle punching or water jet punching can be used.

  The difference in solubility in an aqueous alkali solution in the present invention means that the dissolution rate differs by 20 times or more, more preferably by 40 times or more under the condition for expressing ultrafine fibers. When the dissolution rate is less than 20 times, it becomes difficult to control the fineness of the thermoplastic polymer component having low solubility when the ultrafine fiber is developed.

  The dissolution rate with respect to the alkaline aqueous solution can be calculated from the mass ratio obtained by setting the treatment time as 1 hour in accordance with the chemical resistance test (test solution: sodium hydroxide 10%) of JIS K6911 method (1995).

  Examples of the sea component of the sea-island composite fiber having high solubility in an aqueous alkali solution include, for example, polyesters such as polyethylene terephthalate and polybutylene terephthalate, from the viewpoint of dissolution rate in an aqueous alkali solution and spinning stability, for example, 5-sulfoisophthalic acid. Sodium, polyethylene glycol, sodium dodecylbenzenesulfonate, bisphenol A compound, isophthalic acid, adipic acid, dodecadioic acid, cyclohexyl carboxylic acid, etc., preferably 5-12 mol% copolymerized polyester or polylactic acid is used. be able to.

  In particular, from the viewpoint of heat resistance and solubility in a weak alkaline aqueous solution, it is preferable to use a polyethylene terephthalate copolymer or polylactic acid obtained by copolymerizing sodium 5-sulfoisophthalate, preferably 5 to 12 mol%. Further, these copolymers may be not only binary but also ternary or higher multi-component copolymers.

  The nonwoven fabric obtained as described above can be subjected to shrinkage treatment with warm water or steam in order to improve the denseness of the fibers. The temperature of the hot water or steam is preferably treated so that the temperature of the sheet-like material is less than 110 ° C., since crimps of the ultrafine fibers described later are expressed. If the temperature of the sheet-like material itself is kept below 110 ° C., the temperature of hot water or steam applied to shrink the sheet-like material may be 110 ° C. or more.

  In applying the water-dispersible polyurethane liquid to the nonwoven fabric obtained as described above, a method of impregnating or imparting the water-dispersible polyurethane water dispersion to the nonwoven fabric and solidifying by dry heat, water-dispersible polyurethane on the nonwoven fabric After impregnating with an aqueous dispersion, there are a method of heat-coagulation by wet heat, a method of wet coagulation in hot water and heat-drying, and a combination thereof.

  As the drying temperature and drying time, if the temperature of the nonwoven fabric becomes too high, crimps of the ultrafine fibers described later will be manifested. Therefore, it is preferable to dry the sheet material so that the temperature is less than 110 ° C. If the temperature of the sheet-like product itself is kept below 110 ° C, the temperature of the hot air applied for drying may be 110 ° C or higher.

  The water-dispersed polyurethane liquid used in the present invention can contain a water-soluble organic solvent in an amount of 0% by mass to 40% by mass with respect to the aqueous dispersion in order to improve storage stability and film forming property. However, it is preferable that the organic solvent is contained in an amount of 0% by mass or more and 1% by mass or less because of concerns such as the release of the organic solvent into the atmosphere by heating during film formation and the remaining organic solvent in the final product.

  In the method for producing a leather-like sheet of the present invention, ultrafine fibers may be expressed by treating with an aqueous alkaline solution in which a water-dispersible polyurethane liquid is applied to a nonwoven fabric composed of ultrafine fiber-expressing fibers.

  As the alkaline aqueous solution, for example, an aqueous solution such as sodium hydroxide or potassium hydroxide, an ammonia salt, or the like can be suitably used.

  The concentration of the alkaline aqueous solution is not particularly limited as long as ultrafine fibers can be expressed, and is preferably 0.05 mol / L or more and 10 mol / L or less.

  The treatment with an aqueous alkali solution involves immersing a sheet made of ultrafine fiber-generating fibers after application of water-dispersible polyurethane and performing a squeezing solution. In the case of sea-island type composite fibers, the sea components that dissolve in alkaline water are added. Since it elutes and produces | generates an ultrafine fiber, as a method, the process using a liquid dyeing machine, a refining apparatus, etc., and those combinations further is mentioned, for example.

  For the purpose of improving the generation of ultrafine fibers, heat treatment, steam treatment, and treatment with addition of a penetrating agent such as a surfactant may be performed as appropriate, and treatment with an acidic aqueous solution having a pH of 3 or less was performed in advance. Later, it may be treated with an aqueous alkaline solution. The heat treatment and steam treatment for generating ultrafine fibers are preferably performed so that the temperature of the sheet-like material is less than 110 ° C., since crimping of the ultrafine fibers described later will occur. If the temperature of the sheet-like product itself is kept below 110 ° C., the heat treatment temperature or steam treatment temperature applied to develop the ultrafine fibers may be 110 ° C. or higher.

  The leather-like sheet-like material of the present invention is a leather-like sheet-like material having a nap-like tone having napped fibers of at least one surface.

  The raising treatment for forming napped fibers of the ultrafine fiber on the surface of the leather-like sheet of the present invention can be performed by a grinding method using sandpaper or a roll sander. Before the raising treatment, a lubricant such as a silicone emulsion may be applied to the leather-like sheet.

  In addition, applying an antistatic agent before the above-described raising treatment tends to make it difficult for the grinding powder generated from the leather-like sheet-like material to be deposited on the sandpaper by grinding.

  The leather-like sheet-like material may be obtained by dividing into half or several sheets in the thickness direction of the sheet-like material before performing the raising treatment.

The method for producing a leather-like sheet according to the present invention includes the following steps (1) to (2) in this order.
(1) a step of expressing ultrafine fibers from a nonwoven fabric composed of ultrafine fiber-expressing fibers,
(2) A step of causing crimps in the ultrafine fibers of the raised layer by performing a heat treatment at a temperature of 110 ° C. or more and 150 ° C. or less on the nonwoven fabric made of the ultrafine fibers.

  For example, if the nonwoven fabric is subjected to a heat treatment at 110 ° C. or higher before the step of expressing the ultrafine fibers from the nonwoven fabric composed of the ultrafine fibers, crimps appear due to the presence of sea components around the ultrafine fibers. It is difficult to obtain the heat retention property of the present invention.

  In the method for producing a leather-like sheet of the present invention, crimping of ultrafine fibers in the raised layer is achieved by subjecting a nonwoven fabric made of ultrafine fibers to a heat treatment at a temperature of 110 ° C. or more and 150 ° C. or less. By crimping the ultrafine fibers of the raised layer, the fiber density of the raised layer is improved, and the fiber density is equal to or higher than the fiber density of the base material layer. Since the fiber density of the napped layer is high, it becomes a heat insulating layer that grips warm air, and further, good tactile sensation and surface quality can be obtained.

  In order to heat-treat the nonwoven fabric made of ultrafine fibers at a temperature of 110 ° C. or higher, a known apparatus can be used. For example, a liquid dyeing machine can be used.

  The treatment temperature needs to be 110 ° C. or more and 150 ° C. or less. However, the crimping of the ultrafine fibers is more likely to proceed when the treatment is performed at a higher temperature. However, if the treatment is carried out at an excessively high temperature, the elastic polymer comprising polyurethane as a main component is thermally deteriorated, so that the temperature is preferably 120 ° C. or higher and 150 ° C. or lower, more preferably 125 ° C. or higher and 135 ° C. or lower.

  The leather-like sheet of the present invention may be dyed. As the dyeing method, it is preferable to use a liquid dyeing machine because the sheet-like material can be softened by giving a stagnation effect at the same time as the leather-like sheet material is dyed. As the liquid dyeing machine, a normal liquid dyeing machine can be used.

  If the dyeing temperature is too high, the water-dispersed polyurethane may deteriorate, and conversely, if the dyeing temperature is too low, the dyeing to the fiber becomes insufficient. It is preferably 80 ° C. or higher and 150 ° C. or lower, more preferably 110 ° C. or higher and 130 ° C. or lower.

  Further, the heat treatment at a temperature of 110 ° C. or more and 150 ° C. or less in the step (2) may be performed simultaneously with the dyeing.

  The dye can be selected according to the ultrafine fiber constituting the nonwoven fabric, but a disperse dye is preferably used for the polyester ultrafine fiber. You may use dyes, such as an acid dye and a metal-containing dye, and the dye which combined them. When dyed with disperse dyes, reduction washing may be performed after dyeing.

  Further, for the purpose of improving the uniformity and reproducibility of dyeing, a dyeing assistant can be used during dyeing. Further, the leather-like sheet of the present invention may be subjected to a finishing agent treatment such as a softening agent such as silicone, an antistatic agent, a water repellent, a flame retardant, and a light resistance agent. The same bath as dyeing may be used.

  The leather-like sheet-like material of the present invention is suitably used as shirts, jackets, bags, belts, wallets, etc. and parts thereof, uppers of shoes such as casual shoes, sports shoes, men's shoes, women's shoes, and trims. be able to. Furthermore, the leather-like sheet-like material of the present invention is suitable for skin materials and wall materials of furniture and chairs, and further as skin materials such as seats and ceilings in interiors of vehicles such as automobiles, trains and aircraft, and interior materials. Can be used.

[Evaluation methods]
(1) Average single fiber diameter The surface of the nonwoven fabric or leather-like sheet was photographed at a magnification of 2000 using a scanning electron microscope (VE-7800 manufactured by SEM KEYENCE). Randomly select 100 elliptical fibers close to, and measure the fiber diameter. The average single fiber diameter was calculated by calculating the average value of 100 fiber diameters.

(2) Intrinsic Viscosity 0.8 g of sample polymer was dissolved in 10 mL of orthochlorophenol (hereinafter abbreviated as OCP), and the relative viscosity (ηr) was determined by the following equation using an Ostwald viscometer at a temperature of 25 ° C. Intrinsic viscosity (IV) was calculated.

ηr = η / η0 = (t × d) / (t0 × d0)
Intrinsic viscosity IV = 0.0242ηr + 0.2634
Here, η: viscosity of polymer solution η0: viscosity of OCP t: drop time of solution (second)
d: density of the solution (g / cm ³ )
t0: OCP fall time (seconds)
d0: OCP density (g / cm ³ ).

(3) Fiber diameter CV
The fiber diameter was measured by the above (1), and the fiber diameter CV was expressed as a percentage (%) obtained by dividing the fiber diameter standard deviation of the fibers constituting the fiber bundle by the average fiber diameter in the bundle. The same measurement was performed on the five bundle fibers, and the five average values were defined as the fiber diameter CV. The fiber diameter CV in the case of the irregular cross section is calculated based on the outer circumference circle of the irregular cross section.

(4) Weight per unit area of leather-like sheet Measured by the method described in JIS L 1096: 1999 8.4.2.
A test piece of 20 cm × 20 cm to 5 sheets collected, weighed respective mass (g), representing the average value in 1 m ² per mass (g / ^{m 2).}
(5) Thickness of base material layer and napped layer Using a scanning electron microscope (VE-7800 manufactured by SEM Keyence Co., Ltd.), a cross section of the sheet-like material was photographed (50 times magnification), and the base material layer and the napped layer were The thickness was measured. The number of n was 5, and the average value was obtained.

(6) Fiber density of napped layer The fiber constituting the napped layer is peeled off from a 20 cm × 20 cm sheet-like test piece, the mass of the peeled fiber is measured, and the average value is the mass per 1 m ² ( g / m ² ) was divided by the value of the thickness of the raised layer to determine the fiber density of the raised layer. The number of n was 5, and the average value was obtained.
(7) Fiber density of base material layer From the above test piece of 20 cm × 20 cm sheet-like material, the mass of the test piece after the fibers constituting the napped layer were peeled off, and the average value per 1 m ^{2 was} measured. The mass density (g / m ² ) was divided by the thickness value of the base material layer to determine the fiber density of the base material layer. The number of n was 5, and the average value was obtained.

(8) Thermal insulation The thermal insulation tester (constant temperature method) used in the thermal insulation A method (constant temperature method) described in JIS L1096 (1999) is used. Set to temperature. Set the environmental conditions to a temperature of 25 ° C. and a humidity of 40% RH, and heat insulation tester (constant temperature method) so that the lining side is in contact with the heat insulation tester (constant temperature method). ) And set the surface temperature of the sample after 10 minutes to T1. Next, the environmental conditions are changed to a temperature of 27 ° C. and a humidity of 80% RH. Similarly, only the back body part of the sample is placed so that the lining becomes a heat insulation tester (constant temperature method), and the sample surface after 10 minutes. The surface temperature is T2. The temperature difference T2-T1 at that time was used as the value of the temperature and humidity control effect. When the temperature difference between T2 and T1 was 1 or more, it was determined that a large amount of heat on the lining side was radiated to the surface side, that is, there was heat retention.

<Example 1>
Polyethylene terephthalate having an intrinsic viscosity (IV) of 1.28 and polyethylene terephthalate having an intrinsic viscosity (IV) of 0.81 are used separately as island components, and 8 mol% of sodium 5-sulfoisophthalate is used as a sea component. Using a copolymerized polyethylene terephthalate and a sea-island type compound base with 36 islands, a fiber that has been melt-spun at an island / sea mass ratio of 60/40 is drawn and crimped under normal conditions using a roller plate method. After processing, the fiber was cut into a length of 51 mm to obtain a raw material of sea-island type composite fiber having an average single fiber diameter of 26 μm.

Using this sea-island type composite fiber raw material, a laminated fiber web is formed through a card and cross wrapping process, needle punched at a punch number of 600 / cm ² , and then needle punched at a punch number of 3000 / cm ^2. To give a sheet.

  The sheet was treated with hot water at a temperature of 96 ° C. and contracted, and then dried with hot air at a drying temperature of 100 ° C. for 5 minutes. Next, impregnation with an aqueous dispersion type polyurethane liquid (ether type) having a polyurethane solid content concentration of 10% by mass and drying with hot air at a drying temperature of 100 ° C. for 10 minutes, the polyurethane mass relative to the mass of the island component of the sheet-like material is 47. A sheet-like material to which water-dispersed polyurethane was added so as to be mass% was obtained.

  Next, the sheet-like material thus obtained is immersed in a 15 g / L sodium hydroxide aqueous solution heated to a temperature of 80 ° C. and treated for 30 minutes to remove sea components of the sea-island fiber. Thus, a leather-like sheet made of ultrafine fibers and water-dispersed polyurethane was obtained. It was confirmed by scanning electron microscope (SEM) observation of the surface of the obtained leather-like sheet that the average single fiber diameter was 0.4 μm and the fiber diameter CV was 7.5%.

  Then, the leather-like sheet-like material was cut in half in the thickness direction, and the raised surface was formed by grinding the half-cut surface using an endless sandpaper having a sandpaper count of 240.

  The sheet-like material thus obtained was subjected to crimping treatment and dyeing simultaneously at a temperature of 133 ° C. using a liquid dyeing machine, and then dried using a dryer to give a leather-like A sheet was obtained.

  As a result of observing the raised layer portion of the leather-like sheet-like material, it was confirmed that crimps were expressed in the ultrafine fibers constituting the raised layer. Moreover, as a result of measuring the ratio of the fiber density of the base material layer of the obtained sheet | seat, and the fiber density of a napped layer, it was napped layer fiber density / base material layer fiber density = 1.779. Moreover, the temperature difference of T2-T1 was 2.8, and it was favorable heat retention. The results are shown in Table 1.

<Example 2>
Polyethylene terephthalate having an intrinsic viscosity (IV) of 0.78 and polyethylene terephthalate having an intrinsic viscosity (IV) of 0.51 are used separately as island components, and 8 mol% of sodium 5-sulfoisophthalate is used as a sea component. Using a copolymerized polyethylene terephthalate and a sea-island type compound base with 36 islands, a fiber that has been melt-spun at an island / sea mass ratio of 60/40 is drawn and crimped under normal conditions using a roller plate method. After processing, the fiber was cut into a length of 51 mm to obtain a raw material of sea-island type composite fiber having an average single fiber diameter of 26 μm.

Using this sea-island type composite fiber raw material, a laminated fiber web is formed through a card and cross wrapping process, needle punched at a punch number of 600 / cm ² , and then needle punched at a punch number of 3000 / cm ^2. To give a sheet.

  The sheet was treated with hot water at a temperature of 96 ° C. and contracted, and then dried with hot air at a drying temperature of 100 ° C. for 5 minutes. Next, impregnation with an aqueous dispersion type polyurethane liquid (ether type) having a polyurethane solid content concentration of 10% by mass and drying with hot air at a drying temperature of 100 ° C. for 10 minutes, the polyurethane mass relative to the mass of the island component of the sheet-like material is 47. A sheet-like material to which water-dispersed polyurethane was added so as to be mass% was obtained.

  Next, the sheet-like material thus obtained is immersed in a 15 g / L sodium hydroxide aqueous solution heated to a temperature of 80 ° C. and treated for 30 minutes to remove sea components of the sea-island fiber. Thus, a leather-like sheet made of ultrafine fibers and water-dispersed polyurethane was obtained. By observation with a scanning electron microscope (SEM) on the surface of the obtained leather-like sheet material, it was confirmed that the average single fiber diameter was 2.1 μm and the fiber diameter CV was 7.5%.

  Then, the leather-like sheet-like material was cut in half in the thickness direction, and the raised surface was formed by grinding the half-cut surface using an endless sandpaper having a sandpaper count of 240.

  The sheet-like material thus obtained is subjected to crimping treatment and dyeing at the same time under a temperature condition of 130 ° C. using a liquid dyeing machine, followed by drying using a dryer, and leather-like A sheet was obtained.

  As a result of observing the raised layer portion of the leather-like sheet-like material, it was confirmed that crimps were expressed in the ultrafine fibers constituting the raised layer. Moreover, as a result of measuring the ratio of the fiber density of the base material layer of the obtained sheet | seat, and the fiber density of a napped layer, it was napped layer fiber density / base material layer fiber density = 0.750. Moreover, the temperature difference of T2-T1 was 2.4, and it was favorable heat retention. The results are shown in Table 1.

<Example 3>
Polyethylene terephthalate having an intrinsic viscosity (IV) of 0.78 and polyethylene terephthalate having an intrinsic viscosity (IV) of 0.51 are used separately as island components, and 8 mol% of sodium 5-sulfoisophthalate is used as a sea component. Using copolymerized polyethylene terephthalate and melt-spinning at an island / sea mass ratio of 75/25 using a sea-island type compound base having 16 islands, the resulting fiber is rolled in a roller plate system under normal conditions. After drawing and crimping, it was cut into 51 mm to obtain a raw material of sea-island type composite fiber having an average single fiber diameter of 14 μm.

Using this sea-island type composite fiber, a laminated fiber web is formed through a card and cross wrapping process, needle punched at a punch number of 300 / cm ² , and then needle punched at a punch number of 3400 / cm ^2. To give a sheet.

  The sheet was treated with hot water at a temperature of 96 ° C. and contracted, and then dried with hot air at a drying temperature of 110 ° C. for 5 minutes. Next, impregnation with a water-dispersed polyurethane liquid (ether type) having a polyurethane solid content concentration of 10% by mass, followed by hot-air drying at a drying temperature of 120 ° C. for 10 minutes, the polyurethane mass relative to the mass of the island component of the sheet-like material is 43. A sheet-like material to which water-dispersed polyurethane was added so as to be mass% was obtained.

  Next, this sheet-like material is immersed in an aqueous solution of sodium hydroxide having a concentration of 15 g / L heated to a temperature of 80 ° C. and treated for 30 minutes to remove the sea components of the sea-island fibers, and consists of ultrafine fibers and polyurethane. A leather-like sheet was obtained. By observation with a scanning electron microscope (SEM) on the surface of the obtained leather-like sheet-like material, it was confirmed that the average single fiber diameter was 2.3 μm and the fiber diameter CV was 7.5%.

  Then, the leather-like sheet-like material was cut in half in the thickness direction, and the raised surface was formed by grinding the half-cut surface using an endless sandpaper having a sandpaper count of 240.

  The napkin-like leather-like sheet thus obtained is subjected to simultaneous crimping and dyeing using a liquid dyeing machine at a temperature of 112 ° C., and then dried with a dryer. And a leather-like sheet was obtained.

  As a result of observing the raised layer portion of the leather-like sheet-like material, it was confirmed that crimps were expressed in the ultrafine fibers constituting the raised layer. Moreover, as a result of measuring the ratio of the fiber density of the base material layer of the obtained sheet | seat, and the fiber density of a napped layer, it was napped layer fiber density / base material layer fiber density = 0.550. Moreover, the temperature difference of T2-T1 was 1.5, and there was favorable heat retention. The results are shown in Table 1.

<Example 4>
Polyethylene terephthalate having an intrinsic viscosity (IV) of 0.78 and polyethylene terephthalate having an intrinsic viscosity (IV) of 0.51 are used separately as island components, and 8 mol% of sodium 5-sulfoisophthalate is used as a sea component. Using copolymerized polyethylene terephthalate and melt-spinning at an island / sea mass ratio of 75/25 using a sea-island type compound base having 16 islands, the resulting fiber is rolled in a roller plate system under normal conditions. After drawing and crimping, it was cut into 51 mm to obtain a raw material of sea-island type composite fiber having an average single fiber diameter of 14 μm.

Using this raw material of sea-island type composite fiber, a laminated fiber web is formed through a card and cross wrapping process, and the number of punches is 100 / cm ^{2 in} order to suppress fabric wrinkles due to a sudden width change after fabric bonding. Needle punched. Thereafter, the single yarn diameter of the twisted yarn is 140 μm (110 dtex-288 filament), the twist number is 2000 T / m, the weave density is 80 × 66 (vertical × horizontal) per inch, and the dry heat shrinkage is 8.8%. The plain weave fabric was inserted above and below the laminated fiber web. Thereafter, needle punching was performed at a punch number of 3000 / cm ² to obtain a sheet.

  The sheet was treated with hot water at a temperature of 96 ° C. and contracted, and then dried with hot air at a drying temperature of 110 ° C. for 5 minutes. Next, impregnation with a water-dispersed polyurethane liquid (ether type) having a polyurethane solid content concentration of 10% by mass, followed by hot-air drying at a drying temperature of 120 ° C. for 10 minutes, the polyurethane mass relative to the mass of the island component of the sheet-like material is 43. A sheet-like material to which water-dispersed polyurethane was added so as to be mass% was obtained.

  Next, this sheet-like material is immersed in an aqueous solution of sodium hydroxide having a concentration of 15 g / L heated to a temperature of 80 ° C. and treated for 30 minutes to remove the sea components of the sea-island fibers, and consists of ultrafine fibers and polyurethane. A leather-like sheet was obtained. By observation with a scanning electron microscope (SEM) on the surface of the obtained leather-like sheet-like material, it was confirmed that the average single fiber diameter was 2.3 μm and the fiber diameter CV was 7.5%.

  Then, the leather-like sheet was cut in half in the thickness direction at the position of the laminated fiber web, and the raised surface was formed by grinding the half-cut surface using an endless sandpaper having a sandpaper count of 240. The napkin-like leather-like sheet thus obtained is subjected to simultaneous crimping and dyeing using a liquid dyeing machine at a temperature of 112 ° C., and then dried with a dryer. And a leather-like sheet was obtained.

  As a result of observing the raised layer portion of the leather-like sheet-like material, it was confirmed that crimps were expressed in the ultrafine fibers constituting the raised layer. Moreover, as a result of measuring the ratio of the fiber density of the base material layer of the obtained sheet | seat, and the fiber density of a napped layer, it was napped layer fiber density / base material layer fiber density = 0.575. Moreover, the temperature difference of T2-T1 was 1.6, and there was favorable heat retention. The results are shown in Table 1.

<Comparative Example 1>
Using a liquid dyeing machine, the same treatment as in Example 1 was performed except that the crimping treatment and the dyeing were simultaneously performed under the condition of a temperature of 100 ° C., followed by drying with a dryer. A sheet was obtained.

  As a result of observing the raised layer portion of this leather-like sheet-like product, it was confirmed that the ultrafine fibers constituting the raised layer hardly developed crimps. Moreover, as a result of measuring the ratio of the fiber density of the base material layer of the obtained sheet and the fiber density of the napped layer, the napped layer fiber density / base material layer fiber density = 0.386, and the temperature of T2-T1. The difference was 0.7, and the heat retention was poor. The results are shown in Table 1.

<Comparative example 2>
A sea-island composite with 36 islands using PET with an intrinsic viscosity (IV) of 0.65 as the island component and polyethylene terephthalate copolymerized with 8 mol% of sodium 5-sulfoisophthalate as the sea component. A fiber that has been melt-spun at an island / sea mass ratio of 60/40 using a metal base is drawn by a roller plate method under normal conditions and crimped, and then the fiber is cut into 51 mm, with an average single fiber diameter of 26 μm A raw cotton of type composite fiber was obtained.

Using this sea-island type composite fiber raw material, a laminated fiber web is formed through a card and cross wrapping process, needle punched at a punch number of 600 / cm ² , and then needle punched at a punch number of 3000 / cm ^2. To give a sheet.

  The sheet was treated with hot water at a temperature of 96 ° C. and contracted, and then dried with hot air at a drying temperature of 100 ° C. for 5 minutes. Next, impregnation with an aqueous dispersion type polyurethane liquid (ether type) having a polyurethane solid content concentration of 10% by mass and drying with hot air at a drying temperature of 100 ° C. for 10 minutes, the polyurethane mass relative to the mass of the island component of the sheet-like material is 47. A sheet-like material to which water-dispersed polyurethane was added so as to be mass% was obtained.

  Next, the sheet-like material thus obtained is immersed in a 15 g / L sodium hydroxide aqueous solution heated to a temperature of 80 ° C. and treated for 30 minutes to remove sea components of the sea-island fiber. Thus, a leather-like sheet made of ultrafine fibers and water-dispersed polyurethane was obtained. By observation with a scanning electron microscope (SEM) on the surface of the obtained leather-like sheet material, it was confirmed that the average single fiber diameter was 2.1 μm and the fiber diameter CV was 7.5%.

  Then, the leather-like sheet-like material was cut in half in the thickness direction, and the raised surface was formed by grinding the half-cut surface using an endless sandpaper having a sandpaper count of 240.

  The sheet thus obtained was subjected to simultaneous crimping treatment and dyeing under a temperature condition of 130 ° C. using a liquid dyeing machine, and then dried using a drier to form a leather-like sheet. I got a thing.

  As a result of observing the raised layer portion of this leather-like sheet-like product, it was confirmed that the ultrafine fibers constituting the raised layer did not develop crimps. Moreover, as a result of measuring the ratio of the base material layer fiber density and the napped layer fiber density of the obtained sheet, the napped layer fiber density / the base layer fiber density = 0.450, and the temperature difference of T2-T1 is It was 0.5 and the heat retention was poor. The results are shown in Table 1.

Claims (6)

A non-woven fabric composed of ultrafine fibers having an average single fiber diameter of 0.3 μm or more and 7 μm or less, and a sheet-like material containing water-dispersible polyurethane therein, wherein the sheet-like material comprises a base material layer and a raised layer A leather-like sheet-like product characterized in that the fiber density of the ultrafine fibers constituting each layer satisfies the following relational expression.
2> Napped layer fiber density / Base layer fiber density> 0.5   The ultrafine fiber is a composite fiber in which two or more types of polyethylene terephthalate polymers having a difference in intrinsic viscosity are bonded side by side along the fiber length direction, and / or two or more types of polyethylene having a difference in intrinsic viscosity. The leather-like sheet-like product according to claim 1, wherein the terephthalate polymer is an eccentric core-sheath conjugate fiber forming an eccentric core-sheath structure.   The leather-like sheet-like material according to claim 1 or 2, wherein the raised hair of the raised layer has crimps. Two or more types of polyethylene terephthalate polymers with different intrinsic viscosities obtained from ultrafine fiber-expressing fibers are bonded side by side along the fiber length direction and / or an eccentric core-sheath structure A non-woven fabric having a base layer composed of fibers and a raised layer, and a method for producing a sheet-like material containing water-dispersed polyurethane therein, including the following steps (1) and (2) in this order: A method for producing a leather-like sheet.
(1) a step of expressing ultrafine fibers from a nonwoven fabric composed of ultrafine fiber-expressing fibers,
(2) A step of causing crimps in the ultrafine fibers by performing a heat treatment on the nonwoven fabric made of the ultrafine fibers at a temperature of 110 ° C. or higher and 150 ° C. or lower.   5. The method for producing a leather-like sheet material according to claim 4, wherein the ultrafine fiber-expressing fiber is a sea-island type composite fiber.   6. The method for producing a leather-like sheet material according to claim 4, wherein the nonwoven fabric is a nonwoven fabric made of short fibers.