Artificial leather and method for manufacturing same

Abstract

In order to provide an artificial leather with nap which, when used as the surface leather of miscellaneous goods such as vehicle interior materials or furniture, has excellent surface quality while having deformability that allows following a complex form, this artificial leather comprises an entangled fiber body that includes, as constituent elements, nonwoven fabric consisting of extremely fine fibers with an average single fiber diameter of 1.0-10.0μm, and a polymer elastic body, wherein the artificial leather includes a nap layer and a base layer, the surface exposure ratio of the base layer is 0.0%-10.0%, and the transmitted light average brightness of the base layer of the artificial leather in cross section is 80-150.

Description

Artificial leather and its manufacturing method

[0001] The present invention relates to an artificial leather and a method for producing the same.

[0002] Artificial leather with raised nap has superior characteristics compared to natural leather, such as high durability and uniform quality, and is used in a variety of fields, including vehicle interior materials, furniture, miscellaneous goods, and clothing. In particular, when artificial leather is used as the surface of vehicle interior materials, furniture, miscellaneous goods, etc., it is required to be able to be processed into complex shapes and to be able to conform to those shapes.

[0003] However, when artificial leather is processed to fit complex shapes, a strong tension is applied to the artificial leather, causing the napped surface to crack, exposing the base layer and reducing quality. To address this issue, there has long been a need for a method for achieving both the ability to fit complex shapes and surface quality after processing for artificial leather using ultrafine fibers.

[0004] For example, Patent Document 1 discloses a method for producing a napped portion made of ultrafine fibers and an exposed portion of a polymeric elastomer on the surface of an artificial leather in advance by reducing the amount of grinding in the nap-raising process of the artificial leather. Patent Document 2 discloses a method for holding a napped surface made of densely arranged ultrafine fibers at the nanofiber level with a polymeric elastomer. Patent Document 3 proposes a manufacturing method for adjusting the thickness and fluff length of an artificial leather.

[0005] JP 2013-44073 A JP 2015-209594 A JP 2015-509149 A

[0006] However, in the techniques disclosed in Patent Documents 1 to 3, the density of the artificial leather is adjusted by needle punching, which reduces the voids inside the artificial leather. Therefore, when the artificial leather is used as the surface of a vehicle interior or furniture or other miscellaneous item having a complex shape, it may not be able to deform sufficiently to fit the complex shape, i.e., it may not be able to easily follow the shape.

[0007] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an artificial leather having raised nap that has the deformability to conform to complex shapes when used as the surface of vehicle interior materials, furniture, and other miscellaneous goods, while also having excellent surface quality, and a method for producing the same.

[0008] As a result of extensive research conducted by the inventors in order to achieve the above object, it was found that by setting the average brightness of transmitted light of the base layer in the cross section of the artificial leather, which is an index of the proportion of voids in the artificial leather, and the area exposure rate of the base layer, which is the proportion of the part of the base layer that is not covered by the raised nap layer, within specific ranges, it is possible to produce artificial leather that has the deformability to follow complex shapes and also has excellent surface quality.

[0009] The present invention has been completed based on these findings, and provides the following inventions.

[0010] That is, the artificial leather of the present invention has the following configuration. [1] An artificial leather comprising a fiber-entangled body containing, as a component, a nonwoven fabric made of ultrafine fibers having an average single fiber diameter of 1.0 μm to 10.0 μm, and a polymeric elastomer, the artificial leather comprising two layers: a napped layer and a base layer, the area exposure rate of the base layer being 0.0% to 10.0%, and the average brightness of transmitted light of the base layer in the cross section of the artificial leather being 80 to 150. [2] The artificial leather according to [1] above, wherein the average brightness of transmitted light of the base layer in the cross section of the artificial leather is 85 to 145. [3] The apparent density of the artificial leather is 0.20 g / cm ３ 0.50g / cm or more ３ [4] The artificial leather according to any one of [1] to [3], wherein the thickness of the artificial leather when compressed at 4.9 kPa is 0.8 mm or more and 1.2 mm or less, the thickness of the artificial leather when compressed at 29.4 kPa is 0.7 mm or more and 1.0 mm or less, and the compressibility of the artificial leather is 10% or more and 30% or less. [5] The artificial leather according to any one of [1] to [4], wherein the artificial leather satisfies the following formulas (1) to (3):

[0011] 200≦S1≦400 (1) 100≦S2≦300 (2) 1.0≦S1 / S2≦2.5 (3) Here, S1 is the value (S ０° , S ３０° , S ６０° , S ９０° ) and S2 is the maximum value (N / 5cm) of the tensile stress at 40% elongation in a direction perpendicular to the direction in which S1 was measured (N / 5cm). [6] A method for producing an artificial leather according to any one of [1] to [5] above, wherein a sheet-like material made of a fiber-entangled body containing, as a component, a nonwoven fabric made of ultrafine fibers having an average single fiber diameter of 1.0 μm to 10.0 μm and a polymeric elastomer is ground to form a napped sheet, and in a finishing step of the napped sheet, the napped sheet is shrunk by 1% to 20% in the width direction.

[0012] According to the present invention, it is possible to obtain artificial leather that has sufficient deformability to conform to complex shapes and also has excellent surface quality.

[0013] Fig. 1 is a photograph of the surface of the napped layer side of the artificial leather according to the present invention taken with a scanning electron microscope (SEM). Fig. 2 is an image obtained by binarizing the SEM photograph of Fig. 1. Fig. 3 is a photograph of the cross section of the artificial leather according to the present invention taken with an SEM.

[0014] The artificial leather of the present invention is an artificial leather comprising a fiber-entangled body containing, as a constituent element, a nonwoven fabric made of ultrafine fibers having an average single fiber diameter of 1.0 μm to 10.0 μm, and a polymeric elastomer, the artificial leather comprising two layers: a napped layer and a base layer, the area exposure rate of the base layer being 0.0% to 10.0%, and the average brightness of transmitted light of the base layer in the cross section of the artificial leather being 80 to 150. The constituent elements will be described in detail below, but the present invention is not limited in any way to the scope described below as long as it does not depart from the gist of the invention.

[0015] [Fiber-entangled body] The artificial leather of the present invention comprises, as a constituent element, a fiber-entangled body containing, as a constituent element, a nonwoven fabric made of ultrafine fibers having an average single fiber diameter of 1.0 μm or more and 10.0 μm or less.

[0016] The ultrafine fibers according to the present invention are preferably made of a polyester resin from the viewpoint of durability, particularly mechanical strength and heat resistance.

[0017] Examples of the polyester resin include polyethylene terephthalate, polytrimethylene terephthalate, polytetramethylene terephthalate, polycyclohexylene dimethylene terephthalate, polyethylene-2,6-naphthalenedicarboxylate, and polyethylene-1,2-bis(2-chlorophenoxy)ethane-4,4'-dicarboxylate. Among these, polyethylene terephthalate, which is the most widely used, or a polyester copolymer containing mainly ethylene terephthalate units is preferably used.

[0018] Furthermore, as the polyester-based resin, a single polyester or two or more different polyesters may be used. When two or more different polyesters are used, the difference in intrinsic viscosity (IV value) of the polyesters used is preferably 0.50 or less, and more preferably 0.30 or less, from the viewpoint of compatibility between the two or more components.

[0019] In the present invention, the intrinsic viscosity is calculated by the following method: (1) 0.8 g of a sample polymer is dissolved in 10 mL of orthochlorophenol. (2) Using an Ostwald viscometer at a temperature of 25°C, the relative viscosity ηr is calculated using the following formula, and the result is rounded to two decimal places: η ｒ = η / η ０ = (t × d) / (t ０ ×d ０ ) Intrinsic viscosity (IV value) = 0.0242η ｒ +0.2634 (where η is the viscosity of the polymer solution, η ０ is the viscosity of orthochlorophenol, t is the solution drop time (seconds), and d is the solution density (g / cm ３ ), t ０is the fall time of orthochlorophenol (seconds), d ０ is the density of orthochlorophenol (g / cm ３ ) and ).

[0020] From the viewpoint of processing operability, the cross-sectional shape of the ultrafine fibers is preferably a round cross-section, but cross-sectional shapes of irregular cross-sections such as an oval, a polygonal shape such as a flat or triangular shape, a sector shape, a cross shape, a hollow shape, a Y-shape, a T-shape, and a U-shape can also be used.

[0021] The polyester resin constituting the ultrafine fibers may contain inorganic particles such as titanium oxide particles, lubricants, heat stabilizers, ultraviolet absorbers, conductive agents, heat storage agents, antibacterial agents, etc., depending on the purpose.

[0022] The average single fiber diameter of the ultrafine fibers is 1.0 μm or more and 10.0 μm or less. By making the average single fiber diameter of the ultrafine fibers 1.0 μm or more, preferably 1.5 μm or more, excellent effects are achieved in color development after dyeing, light fastness and friction fastness, and stability during spinning. On the other hand, by making the average single fiber diameter 10.0 μm or less, preferably 6.0 μm or less, more preferably 4.5 μm or less, an artificial leather with excellent surface quality that is dense and soft to the touch can be obtained.

[0023] In the present invention, the average single fiber diameter of ultrafine fibers is calculated by taking a scanning electron microscope (SEM) photograph of the cross section of the artificial leather, randomly selecting 10 ultrafine fibers that are circular or elliptical and close to circular, measuring the single fiber diameters, calculating the arithmetic average of the 10 fibers, and rounding off to one decimal place. However, when ultrafine fibers with a modified cross section are used, the diameter of the single fiber is determined by first measuring the cross-sectional area of ​​the single fiber and calculating the diameter when the cross section is considered to be circular.

[0024] In addition, inorganic particles such as titanium oxide particles, lubricants, heat stabilizers, ultraviolet absorbers, conductive agents, heat storage agents, antibacterial agents, etc. may be added to the polyester forming the ultrafine fibers according to various purposes, within the range that does not impair the object of the present invention.

[0025] The fiber-entangled body according to the present invention contains the nonwoven fabric made of the ultrafine fibers as a constituent element. By including the nonwoven fabric as a constituent element, it is possible to obtain a uniform and elegant appearance and texture when the surface is raised.

[0026] Nonwoven fabrics come in two forms: long-fiber nonwoven fabrics composed mainly of filaments, and short-fiber nonwoven fabrics composed mainly of fibers 100 mm or less. Long-fiber nonwoven fabrics are preferred because they produce artificial leathers with excellent strength. Short-fiber nonwoven fabrics, on the other hand, can increase the amount of fibers oriented in the thickness direction of the artificial leather compared to long-fiber nonwoven fabrics, allowing the artificial leather to have a denser surface when raised.

[0027] When using a short-fiber nonwoven fabric, the average fiber length of the ultrafine fibers is preferably 25 mm or more and 90 mm or less. By setting the average fiber length to 90 mm or less, more preferably 80 mm or less, and even more preferably 70 mm or less, good quality and texture can be achieved. On the other hand, by setting the average fiber length to 25 mm or more, more preferably 35 mm or more, and even more preferably 40 mm or more, artificial leather with excellent abrasion resistance can be obtained.

[0028] The basis weight of the nonwoven fabric constituting the artificial leather according to the present invention is measured according to "6.2 Mass per unit area (ISO method)" of JIS L1913:2010 "General nonwoven fabric testing method", and is 50 g / m ２ More than 400g / m ２ The weight of the nonwoven fabric is preferably in the range of 50 g / m ２ More preferably, 80 g / m ２ By setting the weight to 400 g / m or more, it is possible to obtain an artificial leather that has a rich feel and an excellent texture. ２ or less, more preferably 300 g / m ２ By doing as follows, it is possible to obtain a flexible artificial leather with excellent moldability.

[0029] In the artificial leather of the present invention, from the viewpoint of imparting to the artificial leather the deformability and flexibility that enable it to conform to even complex shapes, it is preferable that the artificial leather be composed only of a fiber-entangled body containing a nonwoven fabric made of ultrafine fibers as a component, and a polymeric elastomer.

[0030] [Elastomer] The artificial leather of the present invention comprises the fiber-entangled body and an elastomer. This elastomer acts as a binder that holds the ultrafine fibers that make up the artificial leather. Therefore, in consideration of the soft texture of the artificial leather of the present invention, it is preferable that the elastomer used be polyurethane.

[0031] The polyurethane may be an organic solvent-based polyurethane, which is used in a state of being dissolved in an organic solvent, or a water-dispersed polyurethane, which is used in a state of being dispersed in water, and either of these may be employed. Furthermore, the polyurethane used in the present invention is preferably a polyurethane obtained by reacting a polymer diol, an organic diisocyanate, and a chain extender.

[0032] As the polymer diol, for example, polycarbonate-based diols, polyester-based diols, polyether-based diols, silicone-based diols, and fluorine-based diols can be used, and copolymers of these can also be used. Among these, from the viewpoints of hydrolysis resistance and abrasion resistance, it is preferable to use polycarbonate-based diols.

[0033] The polycarbonate diol can be produced by the transesterification reaction of alkylene glycol with a carbonate ester, or by the reaction of phosgene or a chloroformate with an alkylene glycol.

[0034] Examples of alkylene glycols include linear alkylene glycols such as ethylene glycol, propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,9-nonanediol, and 1,10-decanediol, branched alkylene glycols such as neopentyl glycol, 3-methyl-1,5-pentanediol, 2,4-diethyl-1,5-pentanediol, and 2-methyl-1,8-octanediol, alicyclic diols such as 1,4-cyclohexanediol, aromatic diols such as bisphenol A, glycerin, trimethylolpropane, and pentaerythritol. In the present invention, either a polycarbonate-based diol obtained from a single alkylene glycol or a copolymer polycarbonate-based diol obtained from two or more alkylene glycols can be used.

[0035] Examples of polyester diols include polyester diols obtained by condensing various low molecular weight polyols with polybasic acids.

[0036] Examples of low molecular weight polyols that can be used include one or more selected from ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,3-butanediol, 1,4-butanediol, 2,2-dimethyl-1,3-propanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 1,8-octanediol, diethylene glycol, triethylene glycol, dipropylene glycol, tripropylene glycol, cyclohexane-1,4-diol, and cyclohexane-1,4-dimethanol.

[0037] Also usable are adducts of bisphenol A with various alkylene oxides.

[0038] Examples of polybasic acids include one or more selected from succinic acid, maleic acid, adipic acid, glutaric acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, phthalic acid, isophthalic acid, terephthalic acid, and hexahydroisophthalic acid.

[0039] Examples of the polyether diols used in the present invention include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and copolymer diols obtained by combining these.

[0040] When the molecular weight of the polyurethane elastomer is constant, the number-average molecular weight of the polymer diol is preferably in the range of 500 to 4000. By setting the number-average molecular weight to preferably 500 or more, more preferably 1500 or more, it is possible to prevent the artificial leather from becoming hard. Furthermore, by setting the number-average molecular weight to 4000 or less, more preferably 3000 or less, it is possible to maintain the strength of the polyurethane.

[0041] Examples of the organic diisocyanate used in the present invention include aliphatic diisocyanates such as hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, isophorone diisocyanate, and xylylene diisocyanate, and aromatic diisocyanates such as diphenylmethane diisocyanate and tolylene diisocyanate, and these can also be used in combination.

[0042] As the chain extender, an amine-based chain extender such as ethylenediamine or methylenebisaniline, or a diol-based chain extender such as ethylene glycol can be preferably used. Also, a polyamine obtained by reacting polyisocyanate with water can be used as the chain extender.

[0043] The polyurethane may be used in combination with a crosslinking agent for the purpose of improving water resistance, abrasion resistance, hydrolysis resistance, etc. The crosslinking agent may be an external crosslinking agent added to the polyurethane as a third component, or an internal crosslinking agent that preliminarily introduces reactive points that form a crosslinked structure into the polyurethane molecular structure. From the viewpoint of being able to form crosslinking points more uniformly within the polyurethane molecular structure and reducing a decrease in flexibility, it is preferable to use an internal crosslinking agent.

[0044] As the crosslinking agent, a compound having an isocyanate group, an oxazoline group, a carbodiimide group, an epoxy group, a melamine resin, a silanol group, or the like can be used.

[0045] The polymeric elastomer may contain various additives depending on the purpose, such as flame retardants such as "phosphorus-based, halogen-based, and inorganic" antioxidants, "phenol-based, sulfur-based, and phosphorus-based" antioxidants, ultraviolet absorbers such as "benzotriazole-based, benzophenone-based, salicylate-based, cyanoacrylate-based, and oxalic acid anilide-based" ultraviolet absorbers, light stabilizers such as "hindered amine-based and benzoate-based" stabilizers, hydrolysis-resistant stabilizers such as polycarbodiimide, plasticizers, antistatic agents, surfactants, coagulation adjusters, and dyes.

[0046] In general, the content of the polymer elastomer in the artificial leather can be adjusted appropriately taking into consideration the type of polymer elastomer used, the manufacturing method of the polymer elastomer, and the feel and physical properties, but in the present invention, the content of the polymer elastomer is preferably 10% by mass or more and 60% by mass or less relative to the mass of the fiber-entangled material. By setting the content of the polymer elastomer to 10% by mass or more, more preferably 15% by mass or more, and even more preferably 20% by mass or more, the bonding between the fibers by the polymer elastomer can be strengthened, and the abrasion resistance of the artificial leather can be improved. On the other hand, by setting the content of the polymer elastomer to 60% by mass or less, more preferably 45% by mass or less, and even more preferably 40% by mass or less, the artificial leather can be made more flexible.

[0047] [Artificial Leather] The artificial leather of the present invention comprises the above-mentioned fiber-entangled body and the above-mentioned polymeric elastomer, and further comprises two layers, a napped layer and a substrate layer.

[0048] Of these, the napped layer is a layer consisting of naps present on at least one surface of the artificial leather, and the napped layer referred to in the present invention refers to a portion of the surface consisting of only ultrafine fibers, which is formed by grinding the fibers and polyurethane on the surface of the sheet to which the polymeric elastomer has been applied in the grinding step of the artificial leather manufacturing method described below. From the viewpoint of design effect, it is preferable that the form of this napped layer has such a nap length and directional flexibility that when the user traces the surface with a finger, the direction of the napped layer changes, leaving a mark, that is, a so-called finger mark.

[0049] More specifically, the nap length on the surface is preferably 200 μm or more and 500 μm or less, and more preferably 250 μm or more and 450 μm or less. By setting the nap length to 200 μm or more, the nap on the surface covers the polymeric elastomer, suppressing exposure of the polymeric elastomer on the surface of the artificial leather, thereby making it possible to obtain an artificial leather with uniform color development. On the other hand, by setting the nap length to 500 μm or less, it is possible to obtain an artificial leather with excellent design effect and wear resistance.

[0050] In the present invention, the nap length of an artificial leather is calculated by the following method. (1) Using a lint brush or the like, the nap of the artificial leather is raised, and a thin section having a thickness of 1 mm is prepared in the cross-sectional direction perpendicular to the longitudinal direction of the artificial leather. (2) The cross-section of the artificial leather is observed at 90x magnification using a scanning electron microscope (SEM). (3) In the SEM image, the height of the napped portion (layer consisting only of ultrafine fibers) is measured at 10 points at 200 μm intervals in the width direction of the cross-section of the artificial leather. (4) The average (arithmetic mean) of the heights of the napped portion (layer consisting only of ultrafine fibers) measured at the 10 points is calculated.

[0051] The "raised layer" of the artificial leather according to the present invention refers to a portion of ultrafine fibers that are present near the surface of the artificial leather and do not contain elastomer, in which the fibers are not entangled with each other and are present in an image of a cross section of the artificial leather observed at a magnification of 300 times using a scanning electron microscope (SEM, for example, "VHX-D500" manufactured by Keyence Corporation). On the other hand, the "base layer" refers to a layer other than the raised layer, in which the fibers are entangled with each other and contain elastomer.

[0052] In the artificial leather of the present invention, the exposed area ratio of the base layer, which is the ratio of the portion of the base layer not covered by the raised nap layer, is 0.0% or more and 10.0% or less. By setting the exposed area ratio to 0.0% or more, more preferably 0.3% or more, and even more preferably 0.5% or more, the density of the artificial leather can be prevented from becoming too high, and the flexibility required for conforming to the shape when used as the surface of vehicle interior materials, furniture, miscellaneous goods, etc. can be imparted. By setting the exposed area ratio to 10.0% or less, more preferably 9.5% or less, and even more preferably 9.0% or less, the polymeric elastomer of the base layer is not exposed on the surface of the artificial leather, resulting in an artificial leather with uniform color development and preventing the polymeric elastomer of the base layer from being exposed when used as the surface of complex-shaped vehicle interior materials, furniture, miscellaneous goods, etc.

[0053] In the present invention, the area exposure rate of the substrate layer can be determined by the following method. (i) Ten measurement samples measuring 1 cm x 1 cm in length x width are taken from any location on the artificial leather. However, if the artificial leather is used as the surface or molded article for vehicle interior materials, furniture, miscellaneous goods, etc., the samples should be taken from a curved surface (a curved surface with a curvature radius of 100 mm or more) that can be considered flat, or from a flat surface. (ii) Using a scanning electron microscope (SEM, for example, the "VHX-D500" manufactured by Keyence Corporation), the surface of the measurement sample is observed at 100x magnification. Then, ten photographs of the surface of the artificial leather, such as those shown in Figure 1, are taken, one for each measurement sample, and saved in JPEG format. (iii) Each image is binarized using image processing software. As image processing software, for example, Keyence Corporation's "VW-9000 Album" can be used. In this case, the brightness range is set to 60 or more and 255 or less (195 levels: black: 60 to gray to white: 255), and the threshold is set to 158 (157 or less is black, 158 or more is white), and then the brightness is extracted and binarized. (iv) For the binarized image, black areas of 200 pixels or less are filled in to obtain an image as shown in Figure 2. Figure 2 is an image obtained by binarizing the SEM photograph of Figure 1. In Figure 2, 21 indicates the black areas on the artificial leather surface after binarization, and 22 indicates the white areas on the artificial leather surface after binarization. (v) For each image, the area measurement function of the image processing software is used to calculate the area (S ｂ ) and the area of ​​the white part (22) (S ｗ ) and calculate the area exposure rate (e) using the following formula: e = S ｂ / (S ｗ +S ｂ (vi) The average value of the area exposure rate for each point calculated in the preceding paragraph shall be rounded to the nearest whole number to obtain the area exposure rate (%).

[0054] In the artificial leather of the present invention, the average transmitted light luminance of the base layer in the cross section of the artificial leather is 80 to 150. By setting the average transmitted light luminance of this base layer to 80 or more, more preferably 83 or more, and even more preferably 85 or more, it is possible to suppress local deformation of the artificial leather during processing, prevent the occurrence of holes due to tearing, and maintain surface quality even after processing. On the other hand, by setting the average transmitted light luminance of the base layer to 150 or less, more preferably 148 or less, and even more preferably 145 or less, it is possible to achieve excellent shape-conforming ability even for complex shapes. Of these, from the viewpoint of achieving both suppression of local deformation during processing and shape-conforming ability, a preferred embodiment is one in which the average transmitted light luminance of the base layer in the cross section of the artificial leather is 85 to 145.

[0055] In the present invention, the average transmitted light luminance of the substrate layer in the cross section of the artificial leather can be determined by the following method. (i) Ten measurement samples measuring 1 cm x 1 cm in length x width are taken from any location on the artificial leather. However, if the artificial leather is used as the surface or molded article for vehicle interior materials, furniture, miscellaneous goods, etc., the samples should be taken from a curved surface (a curved surface with a curvature radius of 100 mm or more) that can be considered flat, or from a flat surface. (ii) Using a scanning electron microscope (SEM, for example, the "VHX-D500" manufactured by Keyence Corporation), the surface of the measurement sample is observed at 500x magnification. Then, ten cross-sectional photographs of the artificial leather, such as the one shown in Figure 3, are taken, one for each measurement sample, and saved in JPEG format. (iii) A 500 μm x 500 μm image is cut out from each image. (iv) For each of the cut-out images, the transmitted light luminance defined in the YUV color space is measured for each pixel using the following formula, and the average value (average transmitted light luminance) is calculated: (luminance of each pixel) = 0.29891 x R + 0.58661 x G + 0.11448 x B where R, G, and B represent the luminance of red, green, and blue in the RGB color model, respectively. (v) The average transmitted light luminance is determined by rounding the average transmitted light luminance of each pixel calculated in the previous section to one decimal place.

[0056] The artificial leather of the present invention preferably has a thickness of 0.8 mm to 1.2 mm when compressed at 4.9 kPa, a thickness of 0.7 mm to 1.0 mm when compressed at 29.4 kPa, and a compressibility of 10% to 30%. By setting the thickness of the artificial leather when compressed at 4.9 kPa to 0.8 mm or more, more preferably 0.9 mm or more, it can have excellent cushioning properties and texture. On the other hand, by setting the thickness of the artificial leather when compressed at 4.9 kPa to 1.2 mm or less, more preferably 1.1 mm or less, it can be made into a flexible artificial leather that can conform to complex shapes when used as the surface of miscellaneous goods such as vehicle interior materials and furniture. By setting the thickness of the artificial leather when compressed at 29.4 kPa to 0.7 mm or more, more preferably 0.8 mm or more, it can have excellent deformability when used in complex shapes. On the other hand, by making the thickness of the artificial leather when compressed at 29.4 kPa 1.0 mm or less, more preferably 0.9 mm or less, it is possible to suppress local deformation of the artificial leather during processing and to suppress deterioration of quality due to cracks in the raised nap layer on the surface of the artificial leather.

[0057] The artificial leather of the present invention preferably has a compressibility of 10% or more and 30% or less, calculated from the thickness when compressed at 4.9 kPa and the thickness when compressed at 24.9 kPa. By setting the compressibility of the artificial leather to 10% or more, more preferably 11% or more, and even more preferably 12% or more, it can have excellent deformability for complex shapes. On the other hand, by setting the compressibility of the artificial leather to 30% or less, more preferably 29% or less, and even more preferably 28% or less, it is possible to suppress local deformation of the artificial leather during processing and to suppress deterioration of quality due to cracking of the napped portion on the artificial leather surface.

[0058] In the present invention, the compressibility of the artificial leather is determined by the following method: (i) 2500 mm ２A thickness gauge (e.g., the "SE-15" compressibility and compression modulus measuring device manufactured by Intec Co., Ltd.) with a circular horizontal plate having an area of ​​1.75 times or more the diameter of the circular horizontal plate of the thickness gauge is prepared. (ii) Ten measurement samples each having a diameter of 1.75 times or more the diameter of the circular horizontal plate of the thickness gauge are taken from any location on the artificial leather. However, if the artificial leather is processed as the surface or molded body of vehicle interior materials, furniture, miscellaneous goods, etc., samples should be taken from a curved surface (a curved surface with a radius of curvature of 100 mm or more) or a flat surface that can be considered flat. (iii) Using the thickness gauge, the measurement sample is compressed at a load of 4.9 kPa for 1 minute, and then the thickness is measured. This is the thickness at 4.9 kPa compression. (iv) Using the thickness gauge, the measurement sample is further compressed at a load of 24.9 kPa for 1 minute at the location where the thickness at 4.9 kPa compression of the measurement sample was measured, and then the thickness is measured. This is the thickness at 24.9 kPa compression. (v) From the measured thickness when compressed at 4.9 kPa and the measured thickness when compressed at 24.9 kPa, the compression rate (%) is calculated using the following formula: Compression rate (%) = (thickness (mm) when compressed at 4.9 kPa - thickness (mm) when compressed at 24.9 kPa) / (thickness (mm) when compressed at 4.9 kPa).

[0059] The artificial leather of the present invention has an apparent density of 0.20 g / cm ３ 0.50g / cm or more ３ The apparent density of the artificial leather is preferably in the range of 0.20 g / cm. ３ More preferably, 0.23 g / cm ３ More preferably, 0.25 g / cm ３ By setting the apparent density of the artificial leather to 0.50 g / cm or more, not only the processability during production but also the cushioning property and the texture are excellent. ３ or less, more preferably 0.48 g / cm ３ More preferably, 0.45 g / cm ３ By doing as follows, it is possible to obtain a flexible artificial leather that is easy to process.

[0060] In the present invention, the apparent density of the artificial leather is determined by the thickness (mm) of the artificial leather when compressed at 4.9 kPa, the weight (g / m ２" [2] Apparent density of artificial leather (g / cm ３ [1] The weight of the artificial leather (g / m ２ (i) Measure the mass of a 15 cm square piece of nonwoven fabric taken from any location on the artificial leather at three points. (ii) Multiply the measured values ​​by 1 m ２ The arithmetic mean value (g / m ２ [2] Apparent density (g / cm) of artificial leather ３ ) The thickness of the artificial leather when compressed at 4.9 kPa, "[1] the basis weight of the artificial leather (g / m ２ The apparent density (g / cm) of the artificial leather is calculated using the following formula. ３ ) = basis weight of artificial leather (g / m ２ ) / thickness (mm) of artificial leather when compressed at 4.9 kPa×1000 It is preferable that the artificial leather of the present invention satisfies the following formulas (1) to (3): 200≦S1≦400 (1) 100≦S2≦300 (2) 1.0≦S1 / S2≦2.5 (3) Here, S1 is the value (S ０° , S ３０° , S ６０° , S ９０° ) and S2 is the value of the tensile stress (N / 5 cm) at 40% elongation in the direction perpendicular to the direction in which S1 was measured.

[0061] By setting S1 to preferably 200 (N / 5cm) or more, more preferably 210 (N / 5cm) or more, and even more preferably 220 (N / 5cm) or more, it is possible to suppress deterioration in quality due to local deformation or tearing, even for complex shapes. Furthermore, by setting S2 to preferably 100 (N / 5cm) or more, more preferably 110 (N / 5cm) or more, and even more preferably 120 (N / 5cm) or more, it is possible to suppress deterioration in quality due to local deformation or tearing, even for complex shapes. On the other hand, by setting S1 to preferably 400 (N / 5cm) or less, more preferably 395 (N / 5cm) or less, and even more preferably 390 (N / 5cm) or less, it is possible to provide deformability that can follow complex shapes when used as a surface for vehicle interior materials, furniture, and other miscellaneous goods. Furthermore, when S2 is preferably 300 (N / 5cm) or less, more preferably 295 (N / 5cm) or less, and even more preferably 290 (N / 5cm) or less, the deformability can be such that the sheet can conform to complex shapes when used as a surface for vehicle interior materials, furniture, and other miscellaneous goods. Furthermore, when the value of S1 / S2 is preferably 1.0 or more, more preferably 1.1 or more, and even more preferably 1.2 or more, the sheet can have excellent deformability such that the sheet can conform to anisotropic shapes. On the other hand, when the value of S1 / S2 is preferably 2.5 or less, more preferably 2.4 or less, and even more preferably 2.3 or less, when the sheet is made to conform to a columnar shape such as a regular polygonal columnar shape (e.g., a cylindrical shape or a square), the sheet can conform to the shape and deform only in the vertical direction, but cannot conform to the shape in the horizontal direction, resulting in wrinkles. This can suppress deterioration in quality due to deformation in only one direction.

[0062] In the present invention, the values ​​of S1 and S2 obtained by the following method are used. (i) Within the plane of the artificial leather, 10 samples of 50 mm width x 200 mm length are taken from any direction up to 90° at 30° intervals in each of the directions of 0°, 30°, 60°, and 90°. However, when the artificial leather is processed as a surface or molded article for vehicle interior materials, furniture, miscellaneous goods, etc., the samples should be taken from a curved surface that can be regarded as a flat surface (a curved surface with a curvature radius of 100 mm or more) or a flat surface. (ii) For example, using a tensile tester "RTG-1250" manufactured by Baldwin Co., Ltd., the test is carried out with a chuck distance of 100 mm and a tensile speed of 100 mm / min, and the stress at 40% elongation is measured. (iii) The obtained stress at 40% elongation (S ０° , S ３０° , S ６０° , S ９０° ), the highest value (maximum value) is defined as S1 (N / 5 cm), and the value in the direction perpendicular to the direction in which S1 was measured is defined as S2 (N / 5 cm).

[0063] [Method for producing artificial leather] In the method for producing the artificial leather of the present invention, a sheet-like material comprising a fiber-entangled body containing, as a component, a nonwoven fabric made of ultrafine fibers having an average single fiber diameter of 1.0 μm to 10.0 μm and a polymeric elastomer is ground to form a napped sheet, and in a finishing step of the napped sheet, the napped sheet is shrunk by 1% to 20% in the width direction. Each of these steps will be described in detail below in terms of preferred embodiments.

[0064] <Step of forming a sheet-like product> First, with regard to the nonwoven fabric contained as a component of the fiber-entangled body, examples include a method of directly forming a nonwoven fabric made of ultrafine fibers having an average single fiber diameter within the above-mentioned range by a known method, and a method of forming a nonwoven fabric using composite fibers made of two or more types of thermoplastic resins having different solubilities in solvents, so-called "ultrafine fiber-producing fibers."

[0065] Among these, it is preferable to use islands-in-sea type composite fibers as the composite fibers (ultrafine fiber-forming fibers). By using such islands-in-sea type composite fibers, in which a hardly soluble thermoplastic resin that will later become ultrafine fibers is arranged in the island component fibers and a readily soluble thermoplastic resin is arranged in the sea component fibers, when the sea component fibers are dissolved and removed using a solvent or the like described below, the removed sea component fibers can easily provide appropriate gaps between the island component fibers, i.e., between the ultrafine fibers. As a result, the texture and surface quality of the artificial leather can be further improved.

[0066] As a method for spinning ultrafine fiber-producing fibers having an islands-in-sea composite structure, a method using a polymer mutual alignment body in which the sea part and island part fibers are mutually aligned and spun using an islands-in-sea composite spinneret is preferred from the viewpoint of obtaining ultrafine fibers with a uniform single fiber fineness.

[0067] Examples of the readily soluble thermoplastic resin used for the sea component include polyethylene, polypropylene, polystyrene, copolymer polyesters copolymerized with sodium sulfoisophthalic acid, polyethylene glycol, etc., polylactic acid, etc., and also water-soluble thermoplastic polyvinyl alcohol-based resins. Among these, polystyrene and copolymer polyesters are preferably used from the viewpoints of spinnability and ease of elution into solvents.

[0068] In the method for producing an artificial leather of the present invention, when an islands-in-sea type composite fiber is used, it is preferable to use an islands-in-sea type composite fiber in which the strength of the parts consisting of island components (hereinafter sometimes simply referred to as island parts) is 2.5 cN / dtex or more. By making the strength of the island parts 2.5 cN / dtex or more, more preferably 2.8 cN / dtex or more, and even more preferably 3.0 cN / dtex or more, the abrasion resistance of the artificial leather can be improved.

[0069] When an islands-in-sea type composite fiber is used in the present invention, the fineness of the island portions of the islands-in-sea type composite fiber is calculated by the following method. (1) Twenty islands-in-sea type composite fibers, each 90 cm long, are bundled together. (2) The sea component is dissolved and removed from the sample of (1), and then air-dried. (3) The mass W (g) of the sample is measured using "8.3.1 Corrected fineness b) Method B (simplified method)" of "8.3 Fineness" in JIS L1013:2010 "Testing methods for chemical fiber filament yarns," and the corrected fineness is calculated using the following formula. The arithmetic mean value of two measurements is rounded to one decimal place, and the resulting value is defined as the fineness of the island portions of the islands-in-sea type composite fiber. Fineness (dtex) = 10,000 × W / (0.9 × 20) When an islands-in-sea type composite fiber is used in the present invention, the strength of the island portions of the islands-in-sea type composite fiber is calculated by the following method. (1) Ten islands-in-sea type composite fibers, each 20 cm long, are bundled together. (2) The sea part is dissolved and removed from the sample of (1), and then the sample is air-dried. (3) According to "8.5.1 Standard Time Test" of "8.5 Tensile Strength and Elongation" of JIS L1013:2010 "Testing Methods for Chemical Fiber Filament Yarns," the test is conducted 10 times under the conditions of a grip length of 5 cm, a pulling speed of 5 cm / min, and a load of 2 N (N=10). (4) The arithmetic mean value (cN) of the test results (stress at break) obtained in (3) is divided by the fineness of the island portions of the islands-in-sea type composite fiber, and the value obtained by rounding to one decimal place (cN / dtex) is defined as the strength of the island portions of the islands-in-sea type composite fiber.

[0070] When ultrafine fiber-developing fibers are used, the ultrafine fiber-developing fibers are opened and then formed into a fiber web using a cross wrapper or the like, and the web is entangled to obtain a nonwoven fabric. Methods for entangling the fiber web to obtain a nonwoven fabric include needle punching and water jet punching.

[0071] As for the form of the nonwoven fabric, either a short fiber nonwoven fabric or a long fiber nonwoven fabric can be used as described above. However, in the case of a short fiber nonwoven fabric, the number of fibers oriented in the thickness direction of the artificial leather is greater than in the case of a long fiber nonwoven fabric, and therefore a high degree of density can be obtained on the surface of the artificial leather having a raised nap layer.

[0072] When a staple fiber nonwoven fabric is used as the nonwoven fabric, the ultrafine fiber-developing fibers are preferably subjected to crimping processing, and then cut to a predetermined length to obtain raw cotton, which is then opened, laminated, and entangled to obtain a staple fiber nonwoven fabric. Known methods can be used for crimping and cutting.

[0073] As described above, the fiber-entangled body of the present invention is sufficient as long as it contains the nonwoven fabric as a constituent element, and may further contain other constituent elements as long as the ranges specified in the present invention are satisfied. Generally, for the purpose of improving the strength and shape stability of artificial leather, the woven or knitted fabric is laminated inside or on one side of the nonwoven fabric and entangled to form a fiber-entangled body. However, due to the shape stability of the woven or knitted fabric, the average brightness of transmitted light in the cross section of the base layer of the artificial leather tends to decrease, and shape conformability tends to be impaired, so this is not preferred. Even stretchable woven or knitted fabrics are prone to wrinkles due to stretch-back, and so shape conformability also tends to be poor.

[0074] Before the polymeric elastomer is applied to the fiber-entangled body, the fiber-entangled body may be impregnated with an aqueous solution of a water-soluble resin and dried at 110° C. or higher to apply the water-soluble resin.

[0075] As the water-soluble resin, polyvinyl alcohol is preferably used from the viewpoint of ease of removal in a subsequent step, and polyvinyl alcohol with a saponification degree of 80% or more is more preferably used from the viewpoint of processing stability.

[0076] When the water-soluble resin is added, in order to make the artificial leather denser, it is preferable to shrink the nonwoven fabric by dry heat, wet heat, or both, thereby further increasing the density. The short-fiber nonwoven fabric to which the water-soluble resin has been added can also be compressed in the thickness direction by post-processing such as calendering.

[0077] The water-soluble resin may be applied to the nonwoven fabric by impregnating the nonwoven fabric with an aqueous solution of the water-soluble resin and drying it. The concentration of the aqueous solution of the water-soluble resin is preferably 1% or more and 20% or less.

[0078] By adding a water-soluble resin to the nonwoven fabric, not only is the fiber fixed and dimensional stability improved, but the water-soluble resin also migrates during drying and becomes unevenly distributed on both surface layer sides of the nonwoven fabric.

[0079] The amount of water-soluble resin applied is preferably 10% by mass or more and 60% by mass or less, based on the nonwoven fabric immediately before application. By applying an amount of 10% by mass or more, preferably 15% by mass or more, and more preferably 20% by mass or more, the water-soluble resin is unevenly distributed in the surface layer, thereby reducing the adhesion area between the ultrafine fibers and the polymeric elastomer. Furthermore, by applying an amount of 60% by mass or less, preferably 50% by mass or less, and more preferably 40% by mass or less, an artificial leather having good processability and good physical properties such as abrasion resistance can be obtained.

[0080] The drying temperature of the water-soluble resin is 110° C. or higher, preferably 120° C. or higher. By setting the temperature to 110° C. or higher, the water-soluble resin can be sufficiently migrated.

[0081] <Step of applying polymeric elastomer> Then, a polymeric elastomer is applied to the fiber-entangled body described above, or to a fiber-entangled body obtained after ultrafine fibers are produced from the ultrafine fiber-producing fibers described above. The following description will be given taking the latter as an example.

[0082] First, a fiber-entangled body containing a nonwoven fabric made of the above-mentioned ultrafine fiber-developing fibers as a component is treated with a solvent to develop ultrafine fibers having an average single fiber diameter of 1.0 μm or more and 10.0 μm or less from the ultrafine fiber-developing fibers. When the ultrafine fiber-developing fibers are islands-in-sea composite fibers, the solvent for dissolving and removing the sea component can be an organic solvent such as toluene or trichloroethylene when the sea component is polyethylene, polypropylene, or polystyrene. When the sea component is a copolymer polyester or polylactic acid, an alkaline aqueous solution such as sodium hydroxide can be used. When the sea component is a water-soluble thermoplastic polyvinyl alcohol resin, hot water can be used.

[0083] Thereafter, a polymeric elastomer is applied. For example, when the polymeric elastomer is polyurethane, the method of applying the polymeric elastomer includes a method of impregnating the fiber-entangled body with a solution of the polymer diol, organic diisocyanate, chain extender, etc., followed by wet coagulation or dry coagulation, and these methods can be appropriately selected depending on the type of polymeric elastomer used.

[0084] When the polymeric elastomer is polyurethane, the solvent preferably used is N,N'-dimethylformamide, dimethyl sulfoxide, etc. Alternatively, a method of dispersing polyurethane in water as an emulsion may be used.

[0085] When a water-soluble resin is applied to the nonwoven fabric, the water-soluble resin is unevenly distributed on both surface layer sides of the fiber-entangled body before the polymer elastomer is applied, as described above, and therefore the polymer elastomer is unevenly distributed and solidified in the inner layer side of the sheet. Furthermore, on the inner layer side of the nonwoven fabric with a small amount of water-soluble resin, the ultrafine fibers and the polymer elastomer are strongly bonded. On the other hand, on both surface layer sides of the nonwoven fabric with a large amount of water-soluble resin, the polymer elastomer adheres to the ultrafine fibers from above the water-soluble resin, and therefore the adhesion between the ultrafine fibers and the polymer elastomer is weak.

[0086] Through the above steps, a sheet-like material according to the present invention can be obtained, which is made of a fiber-entangled body containing, as a component, a nonwoven fabric made of ultrafine fibers having an average single fiber diameter of 1.0 μm or more and 10.0 μm or less, and an elastomer.

[0087] <Step of grinding to form a napped sheet> Next, the sheet-like material is ground to form a napped sheet.

[0088] Grinding can be carried out by a method using sandpaper, a roll sander, etc. Grinding can be carried out on only one surface of the artificial leather or on both surfaces, but at least one surface is ground.

[0089] Grinding is preferably carried out so that the thickness of the napped sheet after grinding is preferably 70% or less of the thickness of the sheet-like material before grinding. By making the thickness of the napped sheet after grinding preferably 70% or less, more preferably 65% ​​or less, and even more preferably 60% or less, many surfaces where the ultrafine fibers and the polymeric elastomer are firmly bonded can be ground, and not only can the napped sheet be softened, but unevenness during grinding can be suppressed, and the nap on the surface of the artificial leather becomes uniform, resulting in an elegant appearance.

[0090] Before grinding, the sheet-like material can be cut in half to divide its thickness into two equal parts, from the viewpoint of adjusting the thickness of the sheet-like material and improving productivity. A lubricant such as silicone emulsion can also be applied to the surface of the sheet. Furthermore, applying an antistatic agent such as guanidine hydrochloride before grinding is preferable, as this prevents grinding dust generated from the sheet-like material during grinding from accumulating on the sandpaper.

[0091] <Finishing Step> Finally, the napped sheet is subjected to a finishing step, in which post-processing such as dyeing, shrinking, perforation, embossing, laser processing, pinsonic processing, and printing can be carried out depending on the properties required of the artificial leather.

[0092] In particular, it is preferable to shrink the piled sheet by 1% or more and 20% or less in the width direction at the end of the dyeing process or independently. By shrinking the width direction preferably by 1% or more, more preferably by 3% or more, the density of the artificial leather increases, and deterioration of quality due to breakage during molding can be suppressed even for complex shapes. On the other hand, by shrinking the width direction to 20% or less, more preferably 19% or less, and even more preferably 18% or less, the artificial leather can have deformability that can follow complex shapes when used as a surface for vehicle interior materials, furniture, and other miscellaneous goods.

[0093] In addition, as the method of shrinking said napped sheet in the width direction, for example, when performing at the end of dyeing process, when performing hot air treatment after dyeing, preferably use pin tenter method, which fixes napped sheet in the width direction and conveys, or clip tenter method, which fixes napped sheet with clip.When performing independently, similarly, after wetting napped sheet, can use pin tenter method or clip tenter method to perform hot air treatment.

[0094] In the method for producing the artificial leather of the present invention, it is more preferable to carry out a dyeing treatment. Examples of dyeing treatments that can be used include jet dyeing using a jigger dyeing machine or jet dyeing machine, dip dyeing such as thermosol dyeing using a continuous dyeing machine, or printing treatments on the napped surface using roller printing, screen printing, inkjet printing, sublimation printing, and vacuum sublimation printing. Among these, jet dyeing machines are preferred in terms of quality and grade, since they provide a soft texture. Furthermore, as mentioned above, at the end of the dyeing treatment, it is preferable to shrink the napped sheet in its width direction within the above-mentioned range, and various resin finishing processes, such as coating, can be further carried out as necessary.

[0095] Next, the artificial leather of the present invention will be described in more detail using examples, but the present invention is not limited to these examples. Next, the evaluation methods and measurement conditions used in the examples will be described. However, in measuring each physical property, unless otherwise specified, the measurement was carried out based on the above-mentioned method.

[0096] [Measurement Method] (1) Average Single Fiber Diameter (μm) of Ultrafine Fibers The average single fiber diameter of ultrafine fibers was measured using a scanning electron microscope "VHX-D510" manufactured by Keyence Corporation, and was measured and calculated according to the method described above.

[0097] (2) Area exposure rate (%) of base layer The area exposure rate of the base layer was measured using a scanning electron microscope "VHX-D510" manufactured by Keyence Corporation and image processing software "VW-9000 Album" manufactured by Keyence Corporation, and the brightness was set to a range of 60 to 255 (195 levels: black: 60 to gray to white: 255) and a threshold value of 158 (157 or less is black, 158 or more is white), and then the brightness was extracted and binarized. The other parts were measured and calculated using the method described above.

[0098] (3) Average transmitted light luminance of the base layer in the cross section of the artificial leather The average transmitted light luminance of the base layer in the cross section of the artificial leather was measured using a scanning electron microscope "VHX-D510" manufactured by Keyence Corporation, and was measured and calculated by the above-mentioned method.

[0099] (4) Apparent density of artificial leather (g / cm ３ ), thickness (mm) of the artificial leather when compressed to 4.9 kPa and 24.9 kPa, and compressibility (%) of the artificial leather. The apparent density of the artificial leather, the thickness of the artificial leather when compressed to 4.9 kPa and 24.9 kPa, and the compressibility of the artificial leather were measured using a compressibility and compressive elastic modulus measuring device "SE-15" manufactured by Intec Co., Ltd. as a thickness measuring device, and measurements and calculations were made according to the above-mentioned methods.

[0100] (5) Stresses S1 and S2 (N / 5 cm) of Artificial Leather at 40% Elongation S1 and S2 of the artificial leather at 40% elongation were measured using a tensile tester "RTG-1250" manufactured by Baldwin Co., Ltd., and were measured and calculated according to the method described above.

[0101] (6) CV value (%) of area change rate of artificial leather As an index of surface quality after processing when used as the surface of artificial leather, the variation in area change rate before and after molding processing was evaluated by the following method. A smaller value indicates that the entire surface is deformed uniformly, and artificial leather with a CV value of area change rate of 30% or less was evaluated as artificial leather with excellent uniform deformability and good surface quality. (i) Ten evaluation samples of A4 size (210 mm x 297 mm) were taken from any position on the artificial leather. (ii) A 5 mm x 5 mm grid was drawn on the surface of the raised layer side of the taken evaluation sample. (iii) A 500 μm thick high-density polyethylene (PE) film was applied to the surface opposite to the raised layer side with the grid drawn, and a film-like olefin-based hot melt resin (thickness 50 μm, basis weight 20 g / m) was applied. ２ ) and laminated together. (iv) The evaluation sample laminated with the film was placed on a concave cylindrical mold having a diameter of 50 mm, a height of 14 mm, and an area development ratio of 212%, with the napped layer facing the mold, and vacuum molding was carried out at room temperature. (v) The area of ​​the squares marked on the napped surface side of the evaluation sample obtained by vacuum molding was measured using a digital microscope "VHX-5000" manufactured by Keyence Corporation, adjusting the magnification to 20 times. (vi) The area of ​​the measured squares was divided by the original area before molding to calculate the area change rate (%). (vii) The arithmetic mean value (C ａｖｅ ) and standard deviation (C ｓｄｖ (viii) The CV value (%) of the area change rate was calculated from the value calculated in (vii) using the following formula, and the value obtained was rounded off to the first decimal place to calculate the area change rate CV value (%) = C ａｖｅ / C ｓｄｖ × 100 (7) Exposed area of ​​the substrate layer after processing (mm ２ As an index of the surface quality after processing when used as the surface of artificial leather, the exposed area of ​​the substrate layer after molding processing was evaluated by the following method. The smaller the value, the less substrate layer is exposed on the surface of the artificial leather. When the exposed area of ​​the substrate layer after processing is 1.00 mm ２The following artificial leather was evaluated as an artificial leather with good surface quality, in which deterioration of surface quality due to exposure of the base layer could be suppressed even after processing as a skin. (i) Of the squares drawn on the surface of the napped layer side of the molded product obtained with the area change rate (%) in (6), squares with an area change rate in the range of 145% to 155% were sampled. (ii) The surface of the sampled squares was photographed using a scanning electron microscope "VHX-D500" manufactured by Keyence Corporation, with the magnification adjusted to 50 times. (iii) From the photographed image, the area of ​​the base layer exposed due to cracks in the napped layer of the artificial leather was measured. (iv) The sum of the measured areas was calculated as the exposed area (mm) of the base layer after processing. ２ )

[0102] (8) Appearance Evaluation (Points) After Processing: Evaluation was performed using evaluation samples after processing into a cylindrical shape as described in "(6) CV Value (%) of Area Change Rate of Artificial Leather" above. Vacuum molding was performed, and 20 panelists judged the appearance of the artificial leather surface after processing on a 5-point scale according to the following criteria. The appearance of the artificial leather after processing was evaluated based on the total score of the scores judged by each panelist. Therefore, the total score ranged from a minimum of 20 points to a maximum of 100 points, with a score of 80 points or more being considered acceptable. 5 points: Very good (the artificial leather is formed into a cylindrical shape, and there is no deterioration in quality due to exposure of the base layer caused by partial cracks in the napped layer on the surface of the artificial leather after processing.) 4 points: Good (between 5 and 3 points) 3 points: Fair (the artificial leather is not formed into a cylindrical shape, or there is deterioration in quality due to partial cracks in the napped layer on the surface of the artificial leather after processing.) 2 points: Poor (between 3 and 1 point) 1 point: Very poor (the artificial leather is not formed into a cylindrical shape, and there is large cracks in the napped layer on the surface of the artificial leather after processing, resulting in a significant deterioration in quality.) [Example 1] (Nonwoven fabric for fibrous substrate) The sea component was made of polyethylene terephthalate copolymerized with 8 mol % of sodium 5-sulfoisophthalate, and the island component was made of polyethylene terephthalate, with a conjugation ratio of 45 mass % of the sea component and 55 mass % of the island component, to obtain an islands-in-sea type composite fiber having an island number of 36 islands / filament and an average single fiber diameter of 17 μm. The obtained islands-in-sea type composite fiber was cut into a fiber length of 51 mm to form staples, which were passed through a card and a cross wrapper to form a fiber laminate web with a density of 2500 fibers / cm２ The fabric was needle punched with a number of punches of 680 g / m ２ Thus, a nonwoven fabric having a thickness of 3.5 mm was obtained.

[0103] (Water-soluble resin) The nonwoven fabric obtained as described above was shrunk with hot water at a temperature of 96°C, and then impregnated with a 5% by mass aqueous solution of polyvinyl alcohol (hereinafter sometimes abbreviated as PVA) having a saponification degree of 88%, and then squeezed with a roll. The nonwoven fabric was dried with hot air at a temperature of 120°C for 10 minutes while causing migration of the PVA, thereby obtaining a sheet with PVA in which the ratio of the PVA mass to the mass of the nonwoven fabric was 27% by mass.

[0104] (Polymer elastomer) The PVA-attached sheet obtained as described above was immersed in trichloroethylene and squeezed and compressed 10 times with a mangle to dissolve and remove the sea component and compress the PVA-attached sheet, thereby obtaining a sea-removed PVA-attached sheet consisting of an ultrafine fiber nonwoven fabric and PVA. This sea-removed PVA-attached sheet was immersed in a DMF (dimethylformamide) solution of polyurethane, the polymer diol of which was a polycarbonate diol, adjusted to a solids concentration of 12.0%, and then squeezed with a roll. The polyurethane was then coagulated in an aqueous solution of DMF at a concentration of 30%. The PVA and DMF were then removed with hot water, and the sheet was dried with hot air at a temperature of 110 ° C for 10 minutes to obtain a polyurethane-attached sheet with a thickness of 2.4 mm and a polyurethane mass of 30% by mass relative to the mass of the nonwoven fabric.

[0105] (Grinding) The polyurethane-coated sheet obtained as described above was cut in half so as to divide the thickness into two equal halves, to obtain half-cut sheets with a thickness of 1.2 mm.

[0106] The surface of the half-cut sheet formed in half was ground by 0.3 mm from the surface layer with endless sandpaper of sandpaper count 180 to form a napped layer, thereby obtaining a napped sheet having a thickness of 0.9 mm.

[0107] (Finishing step) The napped sheet obtained as described above was dyed with a black dye using a jet dyeing machine at a temperature of 120°C, and then reduced and washed. After that, the napped sheet was shrunk by 10% in the width direction in a drying step using a pin tenter system to obtain an artificial leather. The obtained artificial leather had an average single fiber diameter of 4.4 μm of ultrafine fibers, a thickness of 1.0 mm when compressed at 4.9 kPa, and a basis weight of 340 g / m. ２ The area exposure rate of the substrate layer was 1.0%, and the average brightness of transmitted light of the substrate layer in the cross section of the artificial leather was 104. The results are shown in Table 1.

[0108] [Example 2] In the (finishing step), the napped sheet was shrunk by 19% in the width direction in the drying step, whereas in Example 1 the napped sheet was shrunk by 10% in the width direction. An artificial leather was obtained in the same manner as in Example 1. The obtained artificial leather had an average single fiber diameter of ultrafine fibers of 4.4 μm, a thickness of 1.1 mm when compressed at 4.9 kPa, and a basis weight of 378 g / m ２ The area exposure rate of the substrate layer was 0.4%, and the average brightness of transmitted light of the substrate layer in the cross section of the artificial leather was 142. The results are shown in Table 1.

[0109] [Example 3] In the (finishing step), the napped sheet was shrunk by 3% in the width direction in the drying step, whereas in Example 1 the napped sheet was shrunk by 10% in the width direction. An artificial leather was obtained in the same manner as in Example 1. The obtained artificial leather had an average single fiber diameter of ultrafine fibers of 4.4 μm, a thickness of 0.9 mm when compressed at 4.9 kPa, and a basis weight of 315 g / m ２ The area exposure rate of the substrate layer was 1.4%, and the average brightness of transmitted light of the substrate layer in the cross section of the artificial leather was 96. The results are shown in Table 1.

[0110] [Example 4] (Nonwoven fabric for fibrous substrate) In Example 1, a fiber laminated web was formed through a card and a cross wrapper, and the number of fibers / cm was 2500. ２ The number of needle punches was adjusted to 2000 / cm. ２ The fabric was needle punched with a number of punches of 600 g / m ２An artificial leather was obtained in the same manner as in Example 1, except that a nonwoven fabric having a thickness of 3.0 mm was obtained by using ultrafine fibers having an average single fiber diameter of 4.4 μm, a thickness of 0.8 mm when compressed at 4.9 kPa, and a basis weight of 300 g / m. ２ The area exposure rate of the substrate layer was 9.0%, and the average brightness of transmitted light of the substrate layer in the cross section of the artificial leather was 104. The results are shown in Table 1.

[0111] [Example 5] (Nonwoven fabric for fibrous substrate) In Example 1, a fiber laminated web was formed through a card and a cross wrapper, and the number of fibers / cm was 2500. ２ The number of needle punches was adjusted to 3000 / cm. ２ The fabric was needle punched with a number of punches of 720 g / m ２ An artificial leather was obtained in the same manner as in Example 1, except that a nonwoven fabric having a thickness of 4.0 mm was obtained. The obtained artificial leather had an average single fiber diameter of the ultrafine fibers of 4.4 μm, a thickness of 1.2 mm when compressed at 4.9 kPa, and a basis weight of 408 g / m ２ The area exposure rate of the substrate layer was 1.2%, and the average brightness of transmitted light of the substrate layer in the cross section of the artificial leather was 131. The results are shown in Table 1.

[0112] [Example 6] In Example 1 (nonwoven fabric for fibrous substrate), islands-in-sea type composite fibers were obtained with a conjugation ratio of 45% by mass of sea part and 55% by mass of island part, with 36 islands per filament and an average single fiber diameter of 17 μm. However, the spinneret for obtaining the islands-in-sea type composite fibers was changed to obtain islands-in-sea type composite fibers with a conjugation ratio of 65% by mass of sea part and 35% by mass of island part, with 48 islands per filament and an average single fiber diameter of 5 μm. An artificial leather was obtained in the same manner as in Example 1. The obtained artificial leather had an average single fiber diameter of 1.3 μm for ultrafine fibers, a thickness of 0.9 mm when compressed at 4.9 kPa, and a basis weight of 340 g / m ２ The area exposure rate of the substrate layer was 3.2%, and the average brightness of transmitted light of the substrate layer in the cross section of the artificial leather was 83. The results are shown in Table 1.

[0113] [Example 7] In Example 1 (nonwoven fabric for fibrous substrate), islands-in-sea type composite fibers were obtained with a conjugation ratio of 45% by mass of sea component and 55% by mass of island component, with 36 islands per filament and an average single fiber diameter of 17 μm. However, the spinneret for obtaining the islands-in-sea type composite fibers was changed to obtain islands-in-sea type composite fibers with a conjugation ratio of 45% by mass of sea component and 55% by mass of island component, with 18 islands per filament and an average single fiber diameter of 37 μm. An artificial leather was obtained in the same manner as in Example 1. The obtained artificial leather had an average single fiber diameter of 9.6 μm for ultrafine fibers, a thickness of 1.1 mm when compressed at 4.9 kPa, and a basis weight of 340 g / m ２ The area exposure rate of the substrate layer was 8.9%, and the average brightness of the substrate layer in the cross section of the artificial leather was 87. The results are shown in Table 1.

[0114] Example 8 (Nonwoven Fabric for Fibrous Substrate) In Example 1, polyethylene terephthalate copolymerized with 8 mol % of 5-sodium sulfoisophthalate was used as the sea component and polyethylene terephthalate was used as the island component, and islands-in-sea composite fibers were obtained with a conjugation ratio of 45 mass % of the sea component and 55 mass % of the island component, with 36 islands per filament and an average single fiber diameter of 17 μm. However, in this example, polystyrene was used as the sea component, and islands-in-sea composite fibers were obtained with a conjugation ratio of 20 mass % of the sea component and 80 mass % of the island component, with 16 islands per filament and an average single fiber diameter of 17 μm. An artificial leather was obtained in the same manner as in Example 1, except that a nonwoven fabric for a fibrous substrate was obtained. The obtained artificial leather had an average single fiber diameter of 4.4 μm for ultrafine fibers, a thickness of 1.0 mm when compressed at 4.9 kPa, and a basis weight of 340 g / m. ２ The exposed area ratio of the substrate layer was 1.0%, and the average brightness of transmitted light of the substrate layer in the cross section of the artificial leather was 104.

[0115]

[0116] [Comparative Example 1] In the (finishing step), the napped sheet was expanded in the width direction by 20% in the drying step, whereas in Example 1 the napped sheet was shrunk in the width direction by 10%. The artificial leather obtained had an average single fiber diameter of 4.4 μm for the ultrafine fibers, a thickness of 0.7 mm when compressed at 4.9 kPa, and a basis weight of 320 g / m.２ The area exposure rate of the substrate layer was 3.5%, and the average brightness of transmitted light of the substrate layer in the cross section of the artificial leather was 78. The results are shown in Table 2.

[0117] [Comparative Example 2] In (nonwoven fabric for fibrous substrate), islands-in-sea type composite fibers having an average single fiber diameter of 5 μm were obtained in Example 6, but the extrusion rate was adjusted to obtain islands-in-sea type composite fibers having an average single fiber diameter of 3.1 μm, and further, in (finishing process), the napped sheet was expanded in the width direction by 20% in the drying process, whereas the napped sheet was shrunk in the width direction by 10% in Example 6. An artificial leather was obtained in the same manner as in Example 6. The obtained artificial leather had an average single fiber diameter of 0.8 μm for the ultrafine fibers, a thickness of 0.8 mm when compressed at 4.9 kPa, and a basis weight of 320 g / m ２ The area exposure rate of the substrate layer was 3.3%, and the average brightness of the substrate layer in the cross section of the artificial leather was 77. The results are shown in Table 2.

[0118] [Comparative Example 3] In Example 7 (nonwoven fabric for fibrous substrate), an islands-in-sea type composite fiber was obtained with a composite ratio of 45% by mass of sea component and 55% by mass of island component, with an island count of 18 islands / filament and an average single fiber diameter of 17 μm. This was further passed through a card and a cross wrapper to form a fiber laminate web with a density of 2500 fibers / cm ２ The number of punches was adjusted to 2000 / cm, and the sea-island composite fiber with an average single fiber diameter of 46.9 μm was obtained. ２ The fabric was needle punched with a number of punches of 640 g / m ２ The artificial leather was obtained in the same manner as in Example 7, except that a nonwoven fabric having a thickness of 4 mm was obtained, and that in the finishing step, the napped sheet was expanded in the width direction by 20% in the drying step, whereas in Example 7 the napped sheet was shrunk in the width direction by 10%. The obtained artificial leather had an average single fiber diameter of 12.1 μm for the ultrafine fibers, a thickness of 1.3 mm when compressed at 4.9 kPa, and a basis weight of 320 g / m ２ The area exposure rate of the substrate layer was 11.0%, and the average brightness of the substrate layer in the cross section of the artificial leather was 76. The results are shown in Table 2.

[0119] [Comparative Example 4] (Nonwoven fabric for fibrous substrate) In Example 1, a fiber laminated web was formed through a card and a cross wrapper, and the number of fibers / cm was 2,500. ２ The number of punches was adjusted to 4000 / cm. ２ The fabric was needle punched with a number of punches of 850g / m ２ An artificial leather was obtained in the same manner as in Example 1, except that a nonwoven fabric with a thickness of 3.6 mm was obtained. The obtained artificial leather had an average single fiber diameter of 4.4 μm of ultrafine fibers, a thickness of 1.2 mm when compressed at 4.9 kPa, and a basis weight of 408 g / m. ２ The area exposure rate of the substrate layer was 7%, and the average brightness of transmitted light of the substrate layer in the cross section of the artificial leather was 174. The results are shown in Table 2.

[0120] Comparative Example 5 (Nonwoven fabric for fibrous substrate) In Example 1, polyethylene terephthalate copolymerized with 8 mol % of 5-sodium sulfoisophthalate was used as the sea part, and polyethylene terephthalate was used as the island part, and an islands-in-sea type composite fiber was obtained with a conjugation ratio of 45 mass % of the sea part and 55 mass % of the island part, with 36 islands per filament and an average single fiber diameter of 17 μm. In this example, polystyrene was used as the sea part, and an islands-in-sea type composite fiber was obtained with a conjugation ratio of 20 mass % of the sea part and 80 mass % of the island part, with 16 islands per filament and an average single fiber diameter of 17 μm. In addition, in the finishing step, the napped sheet was shrunk by 10% in the width direction in the drying step in Example 1, but the napped sheet was expanded by 20% in the width direction. An artificial leather was obtained in the same manner as in Example 1, except that The resulting artificial leather had an average single fiber diameter of 4.4 μm, a thickness of 0.7 mm when compressed at 4.9 kPa, and a basis weight of 320 g / m ２ The area exposure rate of the substrate layer was 3.5%, and the average brightness of transmitted light of the substrate layer in the cross section of the artificial leather was 78. The results are shown in Table 2.

[0121]

[0122] The properties of the obtained artificial leathers are shown in Tables 1 and 2. In particular, the artificial leathers of Examples 1 to 7 all had a CV value of 27% or less, which means that the entire artificial leather could be deformed uniformly. ２ The appearance after processing was good, scoring 88 points or more.

[0123] On the other hand, in the artificial leathers of Comparative Examples 1 to 3 and 5, the average brightness of transmitted light of the base layer in the cross section of the artificial leather was small, and there was a direction in which the stress at 40% elongation was low, resulting in a large ratio of the stress S1 at 40% elongation to S2 (S1 / S2), which resulted in anisotropy in deformation, and an increase in the CV value of the area change rate and the exposed area of ​​the base layer after processing, resulting in poor appearance.Furthermore, in the artificial leather of Comparative Example 4, the average brightness of transmitted light of the base layer in the cross section of the artificial leather and the stress at 40% elongation were extremely high, and the compressibility was low, resulting in poor shape conformability and poor appearance of the artificial leather after processing.

[0124] The artificial leather of the present invention comprises a fiber-entangled body of ultrafine fibers and a polymeric elastomer, and can be processed into complex shapes such as those for vehicle interior materials, furniture, and miscellaneous goods, and can easily conform to these shapes. Furthermore, the surface quality after processing is excellent, making it suitable for use in these applications.

[0125] 21: Black part of the artificial leather surface after binarization processing 22: White part of the artificial leather surface after binarization processing

Claims

1. An artificial leather comprising a fiber complex body including, as a component, a non-woven fabric made of ultrafine fibers having an average single fiber diameter of 1.0 μm or more and 10.0 μm or less, and a polymer elastic body, wherein the artificial leather includes two layers, a cutis layer and a substrate layer, the area exposure rate of the substrate layer is 0.0% or more and 10.0% or less, and the average luminance of transmitted light of the substrate layer in the cross-section of the artificial leather is 80 or more and 150 or less.

2. The artificial leather according to claim 1, wherein the average luminance of transmitted light of the substrate layer in the cross-section of the artificial leather is 85 or more and 145 or less.

3. The apparent density of the artificial leather is 0.20 g / cm ３ or more and 0.50 g / cm ３ or less. The artificial leather according to claim 1.

4. The artificial leather according to any one of claims 1 to 3, wherein the thickness of the artificial leather under a compression of 4.9 kPa is 0.8 mm or more and 1.2 mm or less, the thickness of the artificial leather under a compression of 29.4 kPa is 0.7 mm or more and 1.0 mm or less, and further, the compression rate of the artificial leather is 10% or more and 30% or less.

5. The artificial leather according to any one of claims 1 to 3, wherein the artificial leather satisfies the following formulas (1) to (3). 200 ≦ S1 ≦ 400... (1) 100 ≦ S2 ≦ 300... (2) 1.0 ≦ S1 / S2 ≦ 2.5... (3) Here, S1 is the value measured for the tensile stress at 40% elongation from 30° in any direction up to 90° within the plane of the artificial leather (S ０° , S ３０° , S ６０° , S ９０° ), which is the maximum value (N / 5 cm) among them, and S2 is the value of the tensile stress at 40% elongation in the direction orthogonal to the direction in which S1 is measured (N / 5 cm).

6. A method for manufacturing the artificial leather according to any one of claims 1 to 3, comprising grinding a sheet-like material composed of a fiber complex body including, as a component, a non-woven fabric made of ultrafine fibers having an average single fiber diameter of 1.0 μm or more and 10.0 μm or less, and a polymer elastic body to form a cutis sheet, and in the finishing process of the cutis sheet, shrinking it by 1% or more and 20% or less in the width direction.