Artificial leather and manufacturing method thereof, vehicle interior material, vehicle component, grocery and furniture

Abstract

The present invention addresses the problem of providing an artificial leather which has excellent formability such that the artificial leather can easily follow a complicated shape, and which has excellent surface quality after molding. The present invention pertains to an artificial leather having a base material part comprising a fiber complex of a non-woven fabric formed from ultra-fine fibers having an average single fiber diameter of 0.01 [mu] m to 10.00 [mu] m (inclusive), and having a pile part on at least one surface of the base material part; and a polymeric elastomer, the mass ratio of the polymeric elastomer in the artificial leather being from 15% by mass to 40% by mass (inclusive), and the area ratio of the polymeric elastomer in the surface of the artificial leather on the side having the nap portion being from 0.01% to 3.00% (inclusive). The area ratio of the polymeric elastomer in the cross section of the artificial leather is 5% or more but less than 15%.

Description

Technical Field

[0001] This invention relates to artificial leather and its manufacturing method, vehicle interior materials, vehicle components, groceries, and furniture. Background Technology

[0002] Artificial leather, containing fiber complexes and polymer elastomers such as polyurethane, exhibits superior properties compared to natural leather in terms of durability and uniformity of quality. Therefore, it is used in various fields, including interior materials for automobiles, aircraft, and railway vehicles; furniture interiors; clothing; and everyday items such as shoes and bags. In particular, when artificial leather is used as the outer layer of interior materials for vehicles, there is a requirement for its ability to easily conform to complex shapes, leading to the development of various artificial leather products.

[0003] For example, Patent Document 1 discloses a method for manufacturing stretchable artificial leather, wherein in an artificial leather composed of a fiber complex (mainly comprising extremely fine fibers with a monofilament fineness of 1.1 decibels or less) and polyurethane, after applying a softener to the artificial leather, or simultaneously applying the softener, it is stretched along the length direction under heating, causing it to shrink in the width direction. According to this method, artificial leather with excellent stretchability and softness in the width direction can be provided inexpensively and easily.

[0004] Furthermore, Patent Document 2 discloses an artificial leather comprising a fiber sheet and polyurethane resin, wherein the cross-sectional area ratio of the polyurethane resin in the thickness direction section of the fiber layer (A) constituting the first outer surface of the artificial leather, and the standard deviation of the cross-sectional area ratio of the polyurethane resin, are within a specific range. According to this design, the artificial leather exhibits excellent texture (stiffness) and wrinkle resistance, making it suitable for use as a seat cover or interior material for interior decoration, automotive, aircraft, and railway vehicles, as well as in clothing and other similar products.

[0005] Existing technical documents Patent documents Patent Document 1: Japanese Patent Application Publication No. 2005-76151 Patent Document 2: Japanese Patent Application Publication No. 2021-70904 Summary of the Invention

[0006] The problem that the invention aims to solve In the technology disclosed in Patent Document 1, the artificial leather exhibits elasticity in the width direction. This allows the artificial leather to be molded and processed to a certain extent while conforming to the complex shapes of vehicle interior materials and trim in the width direction. However, it is not possible to make the artificial leather fully conform to complex shapes in the length direction. That is, the resulting artificial leather tends to be anisotropic, which easily leads to cracking of the napped edges on the surface of the artificial leather, exposing the polymer elastomer and causing a decrease in surface quality.

[0007] Furthermore, in the technology disclosed in Patent Document 2, the cross-sectional area ratio of the polyurethane resin in the thickness direction of the fiber layer constituting the outer surface of the artificial leather and its standard deviation are within a specified range. This results in a higher density of the polyurethane forming a film structure, achieving a certain level of texture and wrinkle resistance even when using a water-dispersible polyurethane resin that readily forms a non-porous film. However, when the cross-sectional area ratio of the polyurethane resin is between 15% and 30%, there is a tendency for localized elongation and breakage of the artificial leather when molding complex shapes. Consequently, the polyurethane may be exposed from the cracked areas of the velour on the surface of the artificial leather, still potentially leading to a decrease in surface quality.

[0008] Therefore, the present invention was made in view of the above circumstances, and its object is to provide artificial leather with formability that can be easily followed even for complex shapes, and thus with excellent surface quality after molding.

[0009] Methods for solving problems To achieve the above objectives, the inventors of this application conducted repeated research and discovered that by keeping the mass ratio of polymer elastomer in artificial leather and the area ratio of polymer elastomer in the surface and cross-section of artificial leather within a specific range, it is possible to obtain artificial leather with good formability that can follow even complex shapes and maintain a dense and smooth surface quality after molding and processing, thus completing the present invention.

[0010] The present invention is based on the above insights, and the following invention is provided according to the present invention.

[0011] [1] Artificial leather having a substrate portion and a napped head on at least one surface, The aforementioned substrate portion includes: a fiber complex comprising a nonwoven fabric formed from extremely fine fibers with an average single fiber diameter of 0.01 μm to 10.00 μm; and a polymeric elastomer. The aforementioned polymeric elastomer accounts for more than 15% by mass and less than 40% by mass in the aforementioned artificial leather. The area ratio of polymeric elastomer in the surface of at least one of the aforementioned artificial leathers, on the side having the aforementioned napped head, is more than 0.01% and less than 3.00%. The area ratio of polymer elastomer in the cross-section of the aforementioned artificial leather is more than 5% and less than 15%.

[0012] [2] The artificial leather as described in [1] above, wherein the standard deviation of the area ratio of the polymeric elastomer in the surface of at least one of the artificial leathers having the aforementioned nap is less than 25%.

[0013] [3] The artificial leather as described in [1] or [2] above, wherein the standard deviation of the area ratio of the polymer elastomer in the cross section of the aforementioned artificial leather is less than 25%.

[0014] [4] The artificial leather as described in any one of [1] to [3] above, wherein the thickness t of the aforementioned substrate portion A The thickness is 250μm to 800μm, and the thickness t of the substrate portion is... A With the thickness t of the pile head B The ratio of t A / t B It is between 0.5 and 2.5.

[0015] [5] As described above [4], the artificial leather, wherein the thickness t of the aforementioned substrate portion A The coefficient of variation is below 50%.

[0016] [6] The artificial leather as described in any one of [1] to [5] above, wherein the aforementioned fine fibers contain black pigment.

[0017] [7] A method for manufacturing artificial leather, wherein the aforementioned manufacturing method comprises: A process of imparting polyvinyl alcohol to a fiber complex containing a nonwoven fabric mainly composed of ultrafine fiber visible fibers in an amount of 4% to 40% by mass relative to the mass of ultrafine fiber visible fibers, thereby forming a sheet imparted with polyvinyl alcohol. The process of forming a nonwoven sheet by making extremely fine fibers with an average single fiber diameter of 0.01 μm to 10.00 μm appear from the aforementioned extremely fine fiber-displaying fibers of the polyvinyl alcohol-treated sheet. The process of widening the nonwoven sheet by 2% to 10% is called widening the sheet. A process of applying a polymeric elastomer to the aforementioned broadened sheet in an amount of 12% to 64% by mass relative to the mass of the broadened sheet, thereby forming a sheet with the polymeric elastomer applied. The process of removing the aforementioned polyvinyl alcohol from the sheet with the aforementioned polymer elastomer to form a matrix sheet; and A process of grinding at least one surface of the aforementioned substrate sheet.

[0018] [8] A method for manufacturing artificial leather, wherein the aforementioned manufacturing method comprises: A process of imparting polyvinyl alcohol to a fiber complex containing a nonwoven fabric mainly composed of ultrafine fiber visible fibers in an amount of 4% to 40% by mass relative to the mass of ultrafine fiber visible fibers, thereby forming a sheet imparted with polyvinyl alcohol. The process of widening the sheet by increasing the width of the aforementioned polyvinyl alcohol-treated sheet by more than 2% and less than 10% is formed. The process of making extremely fine fibers with an average single fiber diameter of 0.01μm to 10.00μm appear from the aforementioned extremely fine fiber-visible fibers of the broadened sheet to form a nonwoven sheet; A process of applying a polymeric elastomer at a mass ratio of 12% to 64% relative to the mass of the aforementioned nonwoven sheet to form a sheet with the polymeric elastomer applied. The process of removing the aforementioned polyvinyl alcohol from the sheet with the aforementioned polymer elastomer to form a matrix sheet; and A process of grinding at least one surface of the aforementioned substrate sheet.

[0019] [9] The method for manufacturing artificial leather as described in [7] or [8] above, wherein in the aforementioned process of forming a sheet of polyvinyl alcohol, the amount of polyethylene glycol is 0.01% by mass or more and 0.5% by mass or less relative to the mass of the aforementioned polyvinyl alcohol.

[0020]

[10] Interior materials for vehicles, including any one of the preceding [1] to [6] artificial leather.

[0021]

[11] A vehicle component comprising any one of the artificial leather described in any one of [1] to [6].

[0022]

[12] Groceries containing any of the artificial leather described in any one of [1] to [6] above.

[0023]

[13] Furniture comprising any one of the artificial leather described in any one of [1] to [6] above.

[0024] Invention Effects According to the present invention, artificial leather with excellent formability, capable of easily conforming to even complex shapes, and thus exhibiting superior surface quality after molding, can be obtained. Furthermore, the artificial leather of the present invention can be used in a wide range of applications, including vehicle interior materials, vehicle parts, general merchandise, furniture, and clothing. As described above, based on its formability, capable of easily conforming to even complex shapes, and thus exhibiting superior surface quality after molding, it is particularly suitable for applications such as vehicle interior materials, vehicle parts, general merchandise, and furniture. Attached Figure Description

[0025] [ Figure 1 ] Figure 1 This is a cross-sectional conceptual diagram of the artificial leather involved in this invention.

[0026] [ Figure 2 ] Figure 2 The thickness t of the substrate portion involved in the artificial leather of the present invention A Thickness t of the nap head B A cross-sectional conceptual diagram illustrating the method for determining its coefficient of variation. Detailed Implementation

[0027] The artificial leather of the present invention has a substrate portion and a pile head on at least one surface. The substrate portion comprises a fiber complex of a nonwoven fabric formed from extremely fine fibers with an average single fiber diameter of 0.01 μm to 10.00 μm and a polymeric elastomer. The polymeric elastomer accounts for 15% to 40% by mass of the artificial leather, the area proportion of the polymeric elastomer on the surface of at least one side of the artificial leather having the pile head is 0.01% to 3.00%, and the area proportion of the polymeric elastomer in the cross-section of the artificial leather is 5% to 15%. These constituent elements are described in detail below, but for the purposes of this invention, they are not limited to the scope of the following description as long as they do not depart from the spirit of the invention, and various modifications can be made without departing from the spirit of the invention.

[0028] [Fiber complex] Regarding the substrate portion of the artificial leather according to one embodiment of the present invention (hereinafter also referred to as "this embodiment"), firstly, the fiber complex includes a nonwoven fabric formed from extremely fine fibers with an average single fiber diameter of 0.01 μm or more and 10.00 μm or less.

[0029] The ultrafine fibers involved in this nonwoven fabric are preferably composed primarily of thermoplastic resins capable of melt spinning. Examples of such thermoplastic resins include polyesters such as polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, and polylactic acid; polyamides such as polyamide 6, polyamide 66, and polyamide 12; acrylic resins; polyolefins such as polyethylene and polypropylene; polyphenylene sulfide (PPS); and thermoplastic cellulose. From the viewpoints of strength, dimensional stability, and lightfastness, polyester-based resins are preferred. It should be noted that in this embodiment, the term "main component" refers to a component whose content accounts for 50% or more by mass of its constituent elements. For example, "the main component of the ultrafine fiber is polyethylene terephthalate" means that 50% or more by mass of the ultrafine fiber is polyethylene terephthalate.

[0030] Examples of the aforementioned polyester resins include, in addition to polyethylene terephthalate, polyethylene terephthalate, and polyethylene butylene terephthalate, polyethylene cyclohexanediol terephthalate, polyethylene 2,6-naphthalenedicarboxylate, and polyethylene 1,2-bis(2-chlorophenoxy)ethane-4,4'-dicarboxylate. Among these, polyethylene terephthalate or polyester copolymers primarily containing polyethylene terephthalate units are preferred. It should be noted that, in this embodiment, "polyester copolymers primarily containing polyethylene terephthalate units" refers to polyester copolymers with isophthalic acid or bisphenol A as the copolymer component and polyethylene terephthalate units comprising 80 mol% or more.

[0031] Furthermore, as the aforementioned polyester resin, a single polyester can be used, or two or more different polyesters can be blended and used. However, when two or more different polyesters are blended and used, from the viewpoint of the compatibility of the two or more components, the difference in intrinsic viscosity (IV value) of the polyester used is preferably 0.50 or less, and more preferably 0.30 or less.

[0032] In this invention, the intrinsic viscosity is calculated by the following method.

[0033] (1) Dissolve 0.8g of the sample polymer in 10mL of o-chlorophenol.

[0034] (2) At a temperature of 25°C, the relative viscosity is calculated using an Orthocrites viscometer using the following formula. η r Round to the nearest three decimal places.

[0035] η r = η / η 0 = (t × d) / (t0 × d0) ... (Equation) Intrinsic viscosity (IV value) = 0.0242 η r +0.2634··· (formula) (In which, respectively, η Indicates the viscosity of the polymer solution, η 0 represents the viscosity of o-chlorophenol, t represents the drop time of the solution (seconds), and d represents the density of the solution (g / cm³). 3 ), t0 represents the falling time of o-chlorophenol (seconds), and d0 represents the density of o-chlorophenol (g / cm³). 3 )).

[0036] From a processing operability point of view, the cross-sectional shape of the ultrafine fiber is preferably a circular cross-section (the cross-sectional shape is a perfect circle), but other shapes can also be adopted according to the desired characteristics, such as elliptical, capsule-shaped, triangular and other polygonal shapes (including those with rounded corners), as well as sector-shaped, cross-shaped, hollow, Y-shaped, T-shaped and U-shaped cross-sectional shapes.

[0037] In this embodiment, the average single fiber diameter of the ultrafine fibers is 0.01 μm or more and 10.00 μm or less. By making the average single fiber diameter of the ultrafine fibers 0.01 μm or more, preferably 1.00 μm or more, artificial leather exhibits excellent color development after dyeing, light and rubbing fastness, and stability during spinning. On the other hand, by making the average single fiber diameter of the ultrafine fibers 10.00 μm or less, preferably 5.00 μm or less, artificial leather with a smooth touch and dense surface quality is obtained.

[0038] It should be noted that, in this embodiment, the average single fiber diameter of the so-called ultrafine fiber is calculated as follows: For the cross-section of the artificial leather, an SEM image is captured using a scanning electron microscope (SEM, for example, the "VHX-D500 / D510" type manufactured by KEYENCE Co., Ltd. Hereinafter, if a measuring device is illustrated in the description of the measurement method, it means that the illustrated device or a device with equivalent performance can be used for measurement). Ten circular or nearly circular elliptical ultrafine fibers are randomly selected, and the single fiber diameter is measured. The arithmetic mean of the ten fibers is calculated and rounded to two decimal places. In the case of using ultrafine fibers with irregular cross-sections, the cross-sectional area of ​​the single fiber is first measured, and the diameter is calculated if the cross-section is considered circular, thereby determining the single fiber diameter.

[0039] Depending on the purpose, without prejudice to the purpose of the present invention, the following can be added to the resin forming the ultrafine fibers: black pigments (described later), colored particulate oxide pigments such as "iron hydroxyl oxide and cobalt aluminate", inorganic particles such as titanium oxide particles, lubricants, heat stabilizers, ultraviolet absorbers, conductive agents, heat storage agents, and antibacterial agents.

[0040] In particular, in this embodiment, in order to simultaneously achieve both a deep and uniform color rendering, the aforementioned ultrafine fibers preferably contain a black pigment. As this black pigment, carbon-based black pigments such as carbon black and graphite, and oxide-based black pigments such as a composite oxide of iron(III) oxide, copper, and chromium can be used. In particular, considering the ease of obtaining a black pigment with a fine particle size and excellent dispersibility in polymers, carbon black is more preferred.

[0041] When the ultrafine fiber contains black pigment, the average particle size of the aforementioned black pigment is preferably 0.05 μm or more and 0.20 μm or less. It should be noted that the average particle size of the black pigment referred to here refers to the average particle size of the black pigment in the state of existing in the ultrafine fiber, generally referred to as the secondary particle size, that is, the average particle size in the aggregated state.

[0042] By making the average particle size of the black pigment preferably 0.05 μm or more, more preferably 0.07 μm or more, the black pigment is retained inside the ultrafine fibers, thus suppressing the shedding of pigment from the ultrafine fibers. Therefore, it becomes an artificial leather with excellent rubbing resistance. Furthermore, by making the average particle size of the black pigment preferably 0.20 μm or less, more preferably 0.18 μm or less, and even more preferably 0.16 μm or less, it is possible to suppress pigment exposure to the surface of the ultrafine fibers, and the stability and fiber strength during spinning are excellent, thus becoming an artificial leather with excellent abrasion resistance and strength.

[0043] Furthermore, when the ultrafine fiber contains a black pigment, the coefficient of variation (CV) of the particle size of the aforementioned black pigment is preferably 75% or less. When the coefficient of variation (CV) of the particle size of the black pigment is 75% or less, preferably 65% ​​or less, more preferably 60% or less, further preferably 55% or less, and most preferably 50% or less, the particle size distribution becomes smaller, which can suppress: pigment exposure to the surface of the ultrafine fiber, small particles falling off the surface, poor spinning caused by significantly aggregated particles, and a significant reduction in fiber strength. It should be noted that the lower limit of the coefficient of variation of particle size in this embodiment is not particularly limited, but from the viewpoint of spinning operability and manufacturing cost, it is preferably 0.1% or more.

[0044] In this embodiment, the average particle size and coefficient of variation (CV) of the black pigment are calculated using the following method.

[0045] (1) Prepare ultrathin sections with a thickness of 5μm to 10μm along the cross-sectional direction of the plane perpendicular to the length direction of the ultrafine fibers. It should be noted that, for example, a Sorvall MT6000 ultramicrotome can be used to prepare these ultrathin sections.

[0046] (2) The fiber cross section in the ultrathin section was observed at 10,000 magnification using a transmission electron microscope (TEM, such as the "H7700" manufactured by Hitachi High Technology Co., Ltd.).

[0047] (3) Using image analysis software (such as "WinROOF" manufactured by Mitani Corporation), the equivalent circle diameter of the black pigment particles contained in the 2.3μm×2.3μm field of view of 20 observed images was measured. If there were fewer than 20 black pigment particles in the 2.3μm×2.3μm field of view, the equivalent circle diameter of all existing black pigment particles was measured.

[0048] (4) For the particle size measured at 20 locations, calculate the average value (arithmetic mean) and coefficient of variation (CV). It should be noted that in this embodiment, the coefficient of variation is calculated using the following formula: The coefficient of variation of particle size (%) = (standard deviation of particle size) / (arithmetic mean of particle size) × 100 ··· (formula).

[0049] Furthermore, when the microfiber contains black pigment, the content of black pigment in the resin forming the microfiber is preferably 0.1% by mass or more and 5.0% by mass or less, more preferably 2.0% by mass or more and 5.0% by mass or less, relative to the mass of the microfiber. By making the pigment proportion 0.1% by mass or more, preferably 1.0% by mass or more, more preferably 2.0% by mass or more, more preferably 2.5% by mass or more, and most preferably 3.0% by mass or more, a dark-colored artificial leather with excellent color rendering is obtained. By making the pigment proportion 5.0% by mass or less, preferably 4.5% by mass or less, more preferably 4.0% by mass or less, an artificial leather with high physical properties such as strength and elongation can be produced.

[0050] It should be noted that, in this embodiment, the content of black pigment in the resin forming the ultrafine fibers is calculated by the following method.

[0051] (1) Immerse the artificial leather in a solution containing dimethylformamide, etc., to remove the polymer elastomer and collect the fine fibers.

[0052] (2) For the collected ultrafine fibers, a mixture of phenol and tetrachloroethane was used to dissolve the resin and extract only the black pigment.

[0053] (3) For the extracted black pigment, perform gas analysis and generate a calibration curve for the gas generated from the black pigment.

[0054] (4) After the artificial leather is treated to remove dye, the polymer elastomer is extracted using dimethylformamide and other methods, leaving only the fine fibers, and then the fine fibers are collected.

[0055] (5) For the collected ultrafine fibers, perform gas generation analysis, and calculate the proportion of black pigment contained in the ultrafine fibers based on the detection intensity of the gas generation originating from the black pigment and the calibration curve prepared in (3).

[0056] Furthermore, the fiber complex involved in the artificial leather of this embodiment comprises a nonwoven fabric formed from the aforementioned ultrafine fibers.

[0057] In this embodiment, the term "fiber complex containing nonwoven fabric" means: the fiber complex is in the form of nonwoven fabric; or, as described later, the fiber complex is in the form of nonwoven fabric and woven fabric integrated together; and the fiber complex is in the form of nonwoven fabric and substrate other than woven fabric integrated together, etc.

[0058] By creating a fiber complex containing nonwoven fabric, a uniform and beautiful appearance and texture can be obtained when napping the surface.

[0059] As forms of this nonwoven fabric, there are long-fiber nonwoven fabrics mainly composed of filaments and short-fiber nonwoven fabrics mainly composed of fibers less than 100mm. Compared with the case of using long-fiber nonwoven fabrics, the case of using short-fiber nonwoven fabrics can increase the number of fibers oriented in the thickness direction of the artificial leather. Furthermore, it can make the surface of the artificial leather with napping have a high density and a good tactile feel.

[0060] When using short-fiber nonwoven fabric, the fiber length of the ultrafine fibers is preferably 25 mm or more and 95 mm or less. By making the fiber length preferably 95 mm or less, more preferably 85 mm or less, and even more preferably 75 mm or less, a synthetic leather with excellent texture and a dense and smooth surface quality is obtained. On the other hand, by making the fiber length preferably 25 mm or more, more preferably 35 mm or more, and even more preferably 40 mm or more, a synthetic leather with excellent abrasion resistance is obtained.

[0061] In the artificial leather of this embodiment, the fabric can be laminated inside or on one side of the aforementioned nonwoven fabric and integrated to improve its strength and morphological stability.

[0062] When using fibers that constitute the fabric in the case of integrating the aforementioned fabrics, filament yarns, staple yarns, and blended composite yarns of filament yarns and staple yarns are preferred. Among these, multifilament yarns with polyester resins or polyamide resins as the main components are more preferred from the viewpoints of durability and, in particular, mechanical strength.

[0063] The average single fiber diameter of the fibers constituting the aforementioned fabric is preferably 1.0 μm or more and 50.0 μm or less. By making the average single fiber diameter of the fibers constituting the fabric preferably 50.0 μm or less, more preferably 15.0 μm or less, and even more preferably 13.0 μm or less, artificial leather with excellent softness can be obtained. Moreover, even when the fibers of the fabric are exposed on the surface of the artificial leather, since the hue difference with the dyed, pigment-containing, ultrafine fibers is small, it becomes artificial leather that does not impair the uniformity of the surface hue. On the other hand, by making the average single fiber diameter of the fibers constituting the fabric preferably 1.0 μm or more, more preferably 8.0 μm or more, and even more preferably 9.0 μm or more, it is possible to obtain artificial leather with higher morphological stability of the product.

[0064] In this embodiment, the average single fiber diameter of the fibers constituting the fabric is calculated as follows: For the cross-section of the artificial leather, a scanning electron microscope (SEM, such as the "VHX-D500 / D510" type manufactured by KEYENCE Co., Ltd.) is used to take SEM images, 10 fibers constituting the fabric are randomly selected, the single fiber diameter of the fiber is measured, the arithmetic mean of the 10 fibers is calculated, and the result is rounded to two decimal places.

[0065] When the fibers constituting the aforementioned fabric are multifilaments, the total fineness of the multifilaments is determined by JIS L1013:2010 "Test Methods for Chemical Fiber Filaments" "8.3 Fineness" "8.3.1 Standard Fineness b) Method B (Simplified Method)", preferably 30 dtex or more and 170 dtex or less.

[0066] By making the total fineness of the yarns constituting the fabric below 170 dtex, a synthetic leather with excellent softness is achieved. On the other hand, by making the total fineness above 30 dtex, a synthetic leather with higher morphological stability is achieved. Furthermore, when the nonwoven fabric and the woven fabric are bonded together by means of needle punching, the fibers constituting the woven fabric are less likely to be exposed on the surface of the synthetic leather, thus resulting in a synthetic leather with high surface quality. In this case, the total fineness of the warp and weft multifilaments is preferably the same.

[0067] Furthermore, the twist of the aforementioned filaments constituting the fabric is preferably 1000 T / m or more and 4000 T / m or less. By preferably having a twist of 4000 T / m or less, more preferably 3500 T / m or less, and even more preferably 3000 T / m or less, a synthetic leather with excellent softness is obtained. On the other hand, by preferably having a twist of 1000 T / m or more, more preferably 1500 T / m or more, and even more preferably 2000 T / m or more, damage to the fibers constituting the fabric can be prevented when the nonwoven fabric and the woven fabric are bonded together by needle punching or other methods, thus resulting in a synthetic leather with excellent mechanical strength.

[0068] [Polymer Elastomers] The substrate portion of the artificial leather in this embodiment also includes a polymer elastomer.

[0069] Examples of the aforementioned polymeric elastomers include polyurethane, polyurea, polyurethane-polyurea, and polyacrylic acid. These polymeric elastomers act as adhesives to hold the extremely fine fibers contained in the artificial leather. Therefore, considering the soft texture of the artificial leather in this embodiment, polyurethane is preferably used as the polymeric elastomer.

[0070] This polyurethane is obtained by reacting a polymeric diol with an organic diisocyanate and a chain extender. Furthermore, both organic solvent-based polyurethanes used in a dissolved organic solvent state and water-dispersible polyurethanes used in a dispersed water state can be employed.

[0071] When the polymeric elastomer is polyurethane, the polymeric diol can be, for example, polycarbonate diols, polyester diols, polyether diols, silicone diols, and fluorinated diols. Furthermore, copolymers combining these can also be used. Among these, the use of polycarbonate diols is preferred from the viewpoint of hydrolysis resistance and abrasion resistance.

[0072] First, examples of polycarbonate-based diols include those obtained through transesterification of alkylene diols with carbonates, or through the reaction of alkylene diols with carbonyl chlorides or chloroformates.

[0073] Examples of alkylene glycols used in this polycarbonate diol 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 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; glycerol; trimethylolpropane; and pentaerythritol. In this embodiment, polycarbonate diols obtained from individual alkylene glycols or copolymerized polycarbonate diols obtained from two or more alkylene glycols can be used.

[0074] Furthermore, as a polyester diol, diols obtained by condensing various low molecular weight polyols with polyacids can be cited.

[0075] The low molecular weight polyol used as the polyester diol can be, for example, one or more of the following groups: ethylene glycol, 1,2-propanediol, 1,3-propanediol, 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, cyclohexane-1,4-diethanol, and adducts obtained by adding various epoxides to bisphenol A.

[0076] In addition, the polyacids used in the polyester diol can be, for example, one or more selected from the group consisting of succinic acid, maleic acid, adipic acid, glutaric acid, pimelic acid, octanoic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, phthalic acid, isophthalic acid, terephthalic acid, and hexahydroisophthalic acid.

[0077] In addition, examples of polyether diols include polyethylene glycol, polypropylene glycol, polybutane glycol, and copolydiols composed of these.

[0078] When the polymeric elastomer is polyurethane, and given a fixed molecular weight of the polyurethane elastomer, the number-average molecular weight of the polymeric diol is preferably in the range of 500 to 4000. By preferably having a number-average molecular weight of 500 or more, and more preferably 1500 or more, it is possible to prevent the artificial leather from hardening, resulting in a softer artificial leather. Furthermore, by preferably having a number-average molecular weight of 4000 or less, and more preferably 3000 or less, it is possible to maintain the strength of polyurethane, resulting in a stronger artificial leather.

[0079] Next, when the polymeric elastomer is polyurethane, examples of organic diisocyanates include aliphatic diisocyanates such as hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, isophorone diisocyanate, and phenyl diisocyanate, as well as aromatic diisocyanates such as diphenylmethane diisocyanate and toluene diisocyanate. In addition, they can also be used in combination.

[0080] Furthermore, when the polymeric elastomer is polyurethane, amine-based chain extenders such as ethylenediamine and methylenebisphenylamine, and diol-based chain extenders such as ethylene glycol, are preferably used as chain extenders. Alternatively, polyamines obtained by reacting polyisocyanates with water can also be used as chain extenders.

[0081] Furthermore, when the polymeric elastomer is polyurethane, a crosslinking agent can be used in conjunction to improve water resistance, abrasion resistance, and hydrolysis resistance. The crosslinking agent can be an external crosslinking agent added as a third component relative to the polyurethane, or an internal crosslinking agent that is pre-introduced into the polyurethane molecular structure as reaction sites for crosslinking. From the viewpoint of enabling more uniform formation of crosslinking sites within the polyurethane molecular structure and mitigating the reduction in flexibility, an internal crosslinking agent is preferred.

[0082] Compounds having isocyanate groups, oxazoline groups, carbodiimide groups, epoxy groups, melamine resin groups, and silanol groups can be used as crosslinking agents.

[0083] In this embodiment, the mass percentage of the polymeric elastomer in the artificial leather is 15% to 40% by mass. By making the mass percentage of the aforementioned polymeric elastomer 15% by mass or more, preferably 18% by mass or more, and more preferably 21% by mass or more, the bonding between fibers based on the polymeric elastomer can be enhanced. This results in artificial leather with high abrasion resistance. On the other hand, by making the mass percentage of the aforementioned polymeric elastomer 40% by mass or less, preferably 37% by mass or less, and more preferably 34% by mass or less, artificial leather that can easily conform to complex shapes and has excellent formability is obtained.

[0084] It should be noted that the mass ratio of polymeric elastomers in artificial leather is determined and calculated using the following method.

[0085] (1) Three test pieces with a length of 20cm and a width of 20cm were randomly collected from the artificial leather, and the mass of each test piece was measured.

[0086] (2) The test piece is immersed in a solution in which the polymer elastomer is soluble (for example, dimethylformamide can be used when the polymer elastomer is polyurethane) to remove the polymer elastomer and collect the ultrafine fibers.

[0087] (3) Determine the mass of the collected ultrafine fibers and calculate the mass ratio of the polymer elastomer in the test piece using the following formula. The mass percentage (%) of polymeric elastomer in the test piece = {(mass of the test piece) - (mass of the ultrafine fibers)} / (mass of the test piece) × 100 ··· (Equation) (4) For the three test pieces, calculate the mass percentage (%) of the polymer elastomer in each test piece, and round their arithmetic mean (%) to the first decimal place.

[0088] In addition, various additives can be included in polymer elastomers depending on the purpose, such as pigments such as "inorganic and oxide-based", flame retardants such as "phosphorus, halogen, and inorganic", antioxidants such as "phenolic, sulfur, and phosphorus", ultraviolet absorbers such as "benzotriazole, benzophenone, salicylate, cyanoacrylate, and oxalic acid aniline", light stabilizers such as "hindered amine and benzoate", hydrolysis-resistant stabilizers such as polycarbodiimide, plasticizers, antistatic agents, surfactants, coagulation modifiers, and dyes.

[0089] In the artificial leather of this embodiment, for example, in order to simultaneously achieve a dark and uniform color development, the aforementioned polymeric elastomer preferably also includes a black pigment. As this black pigment, carbon-based black pigments such as carbon black and graphite, and oxide-based black pigments such as a composite oxide of iron oxide, copper, and chromium can be used. In particular, considering the ease of obtaining a black pigment with a fine particle size and its excellent dispersibility in the polymer, carbon black is more preferred as the black pigment.

[0090] When the polymeric elastomer contains a black pigment, the average particle size of the aforementioned black pigment is more preferably 0.05 μm or more and 0.20 μm or less. It should be noted that the average particle size of the black pigment referred to here refers to the average particle size of the black pigment in the state where it exists in the polymeric elastomer, generally referred to as the secondary particle size, that is, the average particle size in the aggregated state.

[0091] By preferably having an average particle size of 0.05 μm or more, and more preferably 0.07 μm or more, the black pigment is retained within the polymer elastomer, thus suppressing pigment detachment from the polymer elastomer. This results in artificial leather with excellent rubbing resistance. Furthermore, by preferably having an average particle size of 0.20 μm or less, preferably 0.18 μm or less, and more preferably 0.16 μm or less, the black pigment exhibits excellent dispersibility when impregnated and applied to the polymer elastomer, resulting in artificial leather with minimal hue unevenness.

[0092] Furthermore, when the polymeric elastomer contains a black pigment, the coefficient of variation (CV) of the black pigment particle size is preferably 75% or less.

[0093] When the coefficient of variation (CV) of the black pigment particle size is 75% or less, preferably 65% ​​or less, more preferably 60% or less, further preferably 55% or less, and most preferably 50% or less, the particle size distribution becomes smaller, which can suppress the shedding of small particles from the surface of the polymer elastomer and the precipitation of significantly aggregated particles in the impregnation tank. It should be noted that the lower limit of the coefficient of variation of particle size in this embodiment is not particularly limited, but from the viewpoint of operability when impregnating and imparting to the polymer elastomer, it is preferably 0.1% or more.

[0094] In this embodiment, the average particle size and coefficient of variation (CV) of the black pigment contained in the polymer elastomer are calculated by the following method.

[0095] (1) Prepare ultrathin slices with a thickness of 5μm to 10μm along the cross-sectional direction of the surface of the artificial leather perpendicular to the length direction.

[0096] (2) The cross section of the polymer elastomer in the ultrathin section was observed at 10,000 magnification using a transmission electron microscope (TEM, such as the "H7700" manufactured by Hitachi High Technology Co., Ltd.).

[0097] (3) Using image analysis software (such as "WinROOF" manufactured by Mitani Corporation), the equivalent circle diameter of the black pigment particles contained in the 2.3μm×2.3μm field of view of 20 observed images was measured. If there were fewer than 20 black pigment particles in the 2.3μm×2.3μm field of view, the equivalent circle diameter of all existing black pigment particles was measured.

[0098] (4) For the particle size measured at 20 locations, calculate the average value (arithmetic mean) and coefficient of variation (CV). It should be noted that in this embodiment, the coefficient of variation is calculated using the following formula: The coefficient of variation of particle size (%) = (standard deviation of particle size) / (arithmetic mean of particle size) × 100 ··· (formula).

[0099] Furthermore, when the polymer elastomer contains black pigment, the content of black pigment in the polymer elastomer is preferably 0.01% by mass or more and 5.0% by mass or less relative to the mass of the polymer elastomer. By making the mass ratio of pigment preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and even more preferably 1.0% by mass or more, a dark-colored artificial leather with excellent color rendering is obtained. On the other hand, by making the mass ratio of pigment 5.0% by mass or less, preferably 4.5% by mass or less, and more preferably 4.0% by mass or less, an artificial leather with high physical properties such as strength is obtained.

[0100] It should be noted that, in this embodiment, the content of black pigment contained in the polymer elastomer is calculated by the following method.

[0101] (1) The artificial leather is immersed in a mixture of phenol and tetrachloroethane to dissolve the fine fibers and collect the polymer elastomer.

[0102] (2) Dimethylformamide and other substances were used to solubilize the collected polymer elastomers and extract only the black pigment.

[0103] (3) For the extracted black pigment, perform gas analysis and generate a calibration curve for the gas generated from the black pigment.

[0104] (4) After using dimethylformamide and other substances to solubilize the polymer elastomer contained in the artificial leather, the dimethylformamide and other substances are removed, thereby solidifying the polymer elastomer again.

[0105] (5) For the polymer elastomer obtained in (4), perform gas generation analysis, and calculate the content of black pigment contained in the polymer elastomer constituting the artificial leather based on the detection intensity of the gas generation originating from the black pigment and the calibration curve made in (3).

[0106] [Artificial Leather] The artificial leather of this embodiment has a substrate portion comprising the aforementioned fiber complex and the aforementioned polymeric elastomer, and has a napped head on at least one of its surfaces. Here, the substrate portion refers to the portion comprising the aforementioned fiber complex and the aforementioned polymeric elastomer, corresponding to the portion of the "base sheet" described later in the artificial leather manufacturing method that is not sanded when viewed in the thickness direction. Furthermore, the napped head refers to the portion where the aforementioned extremely fine fibers are dispersed without being held by the aforementioned polymeric elastomer, corresponding to the portion of the "base sheet" described later in the artificial leather manufacturing method that is sanded when viewed in the thickness direction.

[0107] like Figure 1 As illustrated, the artificial leather of this embodiment has a nap on at least one surface. It may also have nap on both surfaces. Regarding the morphology of the nap on the napped surface, in order to achieve good surface quality after molding, and also from a design perspective, it is preferable to have a nap length and directional softness sufficient to produce a so-called finger mark, where the nap direction changes when a finger is run across it.

[0108] First, in the artificial leather of this embodiment, the area ratio of polymeric elastomer in at least one of the surfaces of the artificial leather having a napped head is 0.01% to 3.00%. That is, in the case where both surfaces have napped heads, it is sufficient for at least one surface to meet this range.

[0109] The area ratio of polymeric elastomer in the surface of at least one of the aforementioned artificial leathers, on the side with the napped head (hereinafter sometimes simply referred to as "the area ratio of polymeric elastomer in the surface") is 0.01% or more, preferably 0.05% or more, and more preferably 0.10% or more. This ensures that the extremely fine fibers present in the napped head are adequately held by the polymeric elastomer at the boundary between the napped head and the substrate, resulting in artificial leather with excellent abrasion resistance. On the other hand, the area ratio of polymeric elastomer in the aforementioned surface is 3.00% or less, preferably 2.00% or less, and more preferably 1.00% or less, resulting in artificial leather that maintains a dense and smooth surface quality and a good tactile feel even after molding and processing.

[0110] To ensure that the area ratio of the polymer elastomer in the surface of the artificial leather is within a specified range, this can be achieved by adjusting the width extension ratio of the polyvinyl alcohol-treated sheet, the apparent density of the polyvinyl alcohol contained in the nonwoven sheet, the grinding conditions of the matrix sheet surface, and the thickness t of the artificial leather substrate portion. A With the thickness t of the pile head B The ratio of t A / t B This can be achieved through adjustments, etc.

[0111] Furthermore, the standard deviation of the area ratio of polymeric elastomers in the surface of at least one of the aforementioned artificial leathers with a napped head (hereinafter, sometimes simply referred to as the "standard deviation of the area ratio of polymeric elastomers in the surface") is preferably 25% or less. That is, in the case where both surfaces have a napped head, at least one surface only needs to meet this range. When the standard deviation of the area ratio of polymeric elastomers in the surface of at least one of the artificial leathers is preferably 25% or less, more preferably 23% or less, and even more preferably 20% or less, it results in artificial leather that maintains a dense and smooth surface quality in all parts of the artificial leather after molding. It should be noted that the lower limit of the standard deviation of the area ratio of polymeric elastomers in the cross-section of this embodiment is not particularly limited. However, it is preferably 1% or more.

[0112] To ensure that the standard deviation of the area ratio of the polymer elastomer in the surface of the artificial leather is within a specified range, this can be achieved by adjusting the width extension rate of the polyvinyl alcohol-treated sheet, the apparent density of the polyvinyl alcohol contained in the nonwoven sheet, and the grinding conditions of the base sheet surface.

[0113] In this embodiment, the area ratio of polymeric elastomers in the surface of artificial leather and the standard deviation of the area ratio of polymeric elastomers in the surface are calculated by the following method.

[0114] (1) Test pieces measuring 0.5 cm in length and 0.5 cm in width were randomly collected from artificial leather and left to stand in saturated ruthenium tetroxide vapor for 4 hours. As a result, the polyurethane exposed on the surface of the artificial leather was electronically stained.

[0115] (2) Coating the surface of artificial leather with 1 nm of osmium atoms to perform conductive treatment.

[0116] (3) Use a field emission scanning electron microscope (e.g., JSM-7800FPrime manufactured by Nippon Electron Co., Ltd.) to observe the surface of artificial leather at 100x magnification.

[0117] (4) For the obtained SEM image, for example, using image analysis software such as "ImageJ", the image is binarized using the following method to calculate the area ratio of polymer elastomers on the surface of artificial leather: (i) Filter the SEM image. If the image is "ImageJ", the processing conditions are as follows: Bilateral Filter (Fiji plugin) Spatial radius: 3 Range radius: 50 Number of filtering processes: 5 (ii) Binarization is performed using the MaxEntropy method, and the black portion in the binarized SEM image is set as a polymer elastomer. (iii) Divide the obtained binarized image (2560×1920 pixels) into 32×32 pixel partitions (4800 partitions in this case). Furthermore, if using "ImageJ", use its Analyze Particle function (which measures particle size and area. For "ImageJ", the conditions are set as follows: Size=0-infinity, Circularity=0.00-1.00). Divide the total area of ​​each polymer elastomer distributed within each partition by the area of ​​each partition to obtain the percentage of polymer elastomer area exposed on the surface of each partition. (iv) Read the number of pixels on the x and y axes of the object image, specify the partition size according to the pixel size, calculate the number of partitions on the x and y axes, and calculate the area ratio of polymer elastomers in each partition region. The area ratio (%) of polymer elastomers on the surface of artificial leather is the value obtained by averaging the area ratio (%) of polymer elastomers in all partitions, and its standard deviation is an indicator of the dispersion of the average value relative to all partitions.

[0118] While the standard deviation is calculated based on all partitions obtained by dividing one image into partitions, in the case of preparing 100 images, the average value and standard deviation of the area ratio (%) of polymer elastomers on the surface are obtained for all the calculation results of all partitions of each of the 100 images (in the case of the above, it is (100 images) × (4800 partitions) = 480000).

[0119] The image analysis software "ImageJ" is cited as an example, but it is not limited to any image analysis software that includes image processing software capable of calculating the area ratio of specified pixels. It should be noted that the image analysis software "ImageJ" is general-purpose software developed by the National Institutes of Health (NIH). Furthermore, this image processing software "ImageJ" has the function of identifying necessary regions and performing pixel analysis on the introduced image.

[0120] Secondly, in this embodiment, the area ratio of the polymer elastomer in the cross-section of the aforementioned artificial leather is 5% or more and less than 15%. When the area ratio of the polymer elastomer in the cross-section of the aforementioned artificial leather (hereinafter sometimes simply referred to as "the area ratio of the polymer elastomer in the cross-section") is 5% or more, more preferably 7% or more, and even more preferably 9% or more, the polymer elastomer effectively binds the fibers together, thus suppressing breakage of the artificial leather during molding and processing, resulting in artificial leather with good strength and wear resistance. On the other hand, when the area ratio of the polymer elastomer in the aforementioned cross-section is less than 15%, more preferably 14% or less, and even more preferably 13% or less, it results in artificial leather with excellent formability that can easily be shaped into complex forms.

[0121] Furthermore, the standard deviation of the area ratio of the polymer elastomer in the cross-section of the aforementioned artificial leather is preferably 25% or less. When the standard deviation of the area ratio of the polymer elastomer in the cross-section of the artificial leather is preferably 25% or less, more preferably 23% or less, and even more preferably 20% or less, all parts of the artificial leather can uniformly follow complex shapes during molding and processing, resulting in artificial leather that not only has excellent formability but also maintains a dense and smooth surface quality. It should be noted that the lower limit of the standard deviation of the area ratio of the polymer elastomer in the cross-section in this embodiment is not particularly limited. Preferably, it is 1% or more.

[0122] In this embodiment, the area ratio of polymer elastomers in the cross-section of the artificial leather and the standard deviation of the area ratio of polymer elastomers in the cross-section are calculated by the following method.

[0123] (1) Randomly collect test pieces with a length of 0.5cm and a width of 1.0cm from artificial leather and encapsulate the internal space with epoxy resin.

[0124] (2) Use a slicer to cut the resin-embedded test piece in a manner parallel to the thickness direction.

[0125] (3) The cut test piece was left to stand in saturated ruthenium tetroxide vapor for 4 hours. As a result, the polymer elastomer in the cross section of the artificial leather was electron-stained.

[0126] (4) Coating the cross section of the artificial leather with 1 nm of osmium atoms to perform conductive treatment.

[0127] (5) Using a field emission scanning electron microscope (e.g., JSM-7800FPrime manufactured by Nippon Electron Co., Ltd.), the cross section of the artificial leather was observed at 500x magnification.

[0128] (6) For the obtained SEM image, for example, using image analysis software such as "ImageJ", the image is binarized by the following method to calculate the area ratio (%) of polymer elastomer in the cross section of artificial leather. (i) Filter the SEM image. If the image is "ImageJ", the processing conditions are as follows: "Bandpass filtering" (processing to remove high and low spatial frequency components) Filter large structures down to 40 pixels Filter small structures up to 3 pixels Suppress stipes: None Direction tolerance: 5% Autoscale after filtering: Yes Saturate the image during autoscaling: Yes Number of filtering processes: 1 Median filtering (a process that reduces image noise by replacing each pixel value with the median of its neighboring pixel values). Radius: 4.0 Number of filtering processes: 1 (ii) Binarization is performed using the MaxEntropy method, and the black portion in the binarized SEM image is set as a polymer elastomer. (iii) Divide the obtained binarized image (1280×960 pixels) into 32×32 pixel partitions (in this case, 1200 partitions). Furthermore, if using "ImageJ", use its Analyze Particle function (which measures particle size and area. For "ImageJ", the conditions are set as follows: Size=0-infinity, Circularity=0.00-1.00). Divide the total area of ​​each polymer elastomer distributed within each partition by the area of ​​each partition to obtain the percentage of polymer elastomer area exposed in the cross-section of each partition. (iv) Read the number of pixels on the x and y axes of the object image, specify the partition size according to the pixel size, calculate the number of partitions on the x and y axes, and calculate the area ratio of polymer elastomers in each partition region. The area ratio (%) of polymer elastomers in the cross-section of artificial leather is the value obtained by averaging the area ratio (%) of polymer elastomers in all partitions, and its standard deviation is an indicator of the dispersion of the average value relative to all partitions.

[0129] While the standard deviation is calculated based on all partitions obtained by dividing one image into sections, when 100 images are prepared, the average value and standard deviation of the area ratio (%) of polymer elastomers in the cross section are obtained for all the calculation results of all partitions of each of the 100 images (in the case of the above, it would be (100 images) × (1200 sections) = 120000).

[0130] Furthermore, the thickness t of the aforementioned substrate portion A The thickness is 250μm to 800μm, and the thickness t of the substrate portion is... A With the thickness t of the pile head B The ratio of t A / t B A value between 0.5 and 2.5 is preferred. By satisfying these two requirements, it becomes an artificial leather that suppresses localized damage during molding and processing, and exhibits excellent abrasion resistance while maintaining a dense and smooth surface quality.

[0131] First, the thickness t of the aforementioned substrate portion A Preferably, the thickness is 250 μm or more and 800 μm or less. This is achieved by adjusting the thickness t of the substrate portion. A Preferably, the thickness is 250 μm or more, more preferably 300 μm or more, thereby creating artificial leather that suppresses localized damage during molding and processing while maintaining a dense and smooth surface quality. On the other hand, by increasing the thickness t of the substrate portion... A Preferably, the micrometer is 800 μm or less, more preferably 700 μm or less, so that it becomes a synthetic leather that can uniformly follow complex shapes during molding and processing.

[0132] Secondly, the thickness t of the aforementioned artificial leather substrate A With the thickness t of the pile head B The ratio of t A / t B Preferably, the ratio is 0.5 to 2.5. This is achieved by adjusting the aforementioned ratio t... A / t B Preferably, the ratio is 0.5 or higher, more preferably 0.7 or higher, thereby producing artificial leather that maintains a uniform and dense surface quality and has excellent abrasion resistance. On the other hand, by making the aforementioned ratio t...A / t B Preferably, the value is 2.5 or less, more preferably 2.2 or less, thereby enabling the artificial leather to have a smooth touch and reducing the area ratio of polyurethane exposed on the surface of the artificial leather.

[0133] The thickness t of the aforementioned substrate portion A The coefficient of variation is preferably 50% or less. When the thickness t of the substrate portion... A When the coefficient of variation is preferably 50% or less, more preferably 25% or less, and even more preferably 10% or less, it becomes an artificial leather that can suppress localized damage to the artificial leather during molding and processing, and can uniformly follow complex shapes while maintaining a dense and smooth surface quality. It should be noted that the thickness t of the substrate portion in this embodiment... A There is no particular limit to the lower limit of the coefficient of variation.

[0134] In addition, the thickness t of the nap head B Preferably, the nap length is 300 μm or more and 500 μm or less. By making the average length of the nap preferably 300 μm or more, and more preferably 350 μm or more, the artificial leather can be made smooth to the touch, and the area ratio of the polymer elastomer exposed on the surface of the artificial leather can be reduced. On the other hand, by making the thickness t of the nap... B Preferably, the surface area is 500 μm or less, more preferably 450 μm or less, thereby creating artificial leather that maintains a uniform and dense surface quality and has excellent wear resistance.

[0135] Furthermore, the thickness t of the aforementioned nap head B The coefficient of variation is preferably below 50%. When the thickness t of the pile head... B When the coefficient of variation is preferably 50% or less, more preferably 40% or less, and even more preferably 30% or less, the area ratio of the polymer elastomer exposed on the surface of the aforementioned artificial leather decreases, making it easier to fall within the aforementioned range, thus achieving artificial leather that simultaneously achieves a uniform and dense surface quality and a smooth touch. It should be noted that the thickness t of the nap in this embodiment... B There is no particular limitation on the lower limit of the coefficient of variation. However, it is preferably 1% or higher.

[0136] In this embodiment, the thickness t of the aforementioned substrate portion A And its standard deviation, the thickness t of the pile head B Its standard deviation is determined and calculated using the following methods.

[0137] (1) Using a lint brush or similar tool to make the nap of the artificial leather stand up, make a thin slice with a thickness of 1 mm along the cross-sectional direction of the surface of the artificial leather perpendicular to the length direction.

[0138] (2) Use a scanning electron microscope (SEM, such as KEYENCE VHX-D500 / D510) to photograph the cross section of the artificial leather at 90x magnification.

[0139] (3) In the captured SEM images, according to Figure 2 The diagram shows a cross-section of the artificial leather, with the bottom surface of the artificial leather ( Figure 2 L in B Parallel lines Figure 2 L in A Draw vertical lines at 200μm intervals on the top.

[0140] (4) At the nape head ( Figure 2 2) and the substrate ( Figure 2 The boundary line of (3) in the middle ( Figure 2 Points P1 to P1 are marked on L0. 10 .

[0141] (5) From point P1 to P 10 Draw perpendicular lines along the direction of the pile head and the direction of the substrate, respectively. Figure 2 (The single-dotted line in the text) marks the points Q1 to Q1 that intersect with the end of the pile head. 10 Points S1 to S2 intersecting with the end of the substrate portion 10 .

[0142] (6) Let the distance between point P1 and S1 be T1, and similarly find the distance to T. 10 The average value (arithmetic mean) (μm) is rounded to one decimal place and taken as the thickness t of the substrate. A (μm). Furthermore, the thickness t of the substrate portion is calculated using the following formula. A Coefficient of variation (%) The thickness t of the substrate A Coefficient of variation (%) = (thickness t of the substrate) A (Distance T1 ~ Distance T) 10 (Standard deviation of ) (μm) / (Thickness of substrate t) A (Distance T1 ~ Distance T) 10 The arithmetic mean of (μm) × 100 ··· (formula).

[0143] (7) Let the distance between point P1 and Q1 be R1. Similarly, find the distance to R. 10 The average value (arithmetic mean) (μm) is rounded to one decimal place, and the resulting value is taken as the thickness t of the pile head. B (μm). Furthermore, the thickness t of the pile head is calculated using the following formula. B Coefficient of variation (%) The thickness t of the nap head B Coefficient of variation (%) = (thickness t of the pile head) B (Distance R1 ~ Distance R) 10 (Standard deviation of ) (μm) / (thickness t of the nap head) B (Distance R1 ~ Distance R) 10 The arithmetic mean of (μm) × 100 ··· (formula).

[0144] In this embodiment, the preferred unit area mass of the artificial leather is 150 g / m². 2 Above 450g / m 2 The following is an example of how the preferred unit area mass of the aforementioned artificial leather is 150 g / m². 2 The above, and more preferably 175g / m 2 The above results in a synthetic leather that exhibits excellent strength and wear resistance while suppressing breakage during molding and processing. Furthermore, the preferred unit area mass of the aforementioned synthetic leather is 450 g / m². 2 The following, or more preferably, is 400g / m 2 This results in artificial leather that can uniformly follow complex shapes during molding and processing.

[0145] It should be noted that the unit area mass of the artificial leather in this embodiment is determined according to "6.2 Mass per unit area (ISO method)" of JIS L1913:2010 "General nonwoven fabrics test method". Specifically, it is measured / calculated as follows.

[0146] (1) Collect 3 test pieces with a length of 30cm × width from artificial leather.

[0147] (2) Determine the mass of the test piece from (1).

[0148] (3) Calculate the mass per unit area of ​​each test piece using the following formula. Mass per unit area (g / m²) 2 = Mass of the test piece (g) / Area of ​​the test piece (m²) 2 ) ···(Mode).

[0149] (4) The arithmetic mean of the mass per unit area obtained from (3) (g / m²) 2 The decimal point is discarded, and the resulting value is taken as the mass per unit area of ​​the artificial leather.

[0150] In this embodiment of the artificial leather, the thickness measured according to "6.1.1 A method" of "6.1 Thickness (ISO method)" in JIS L1913:2010 "General Nonwoven Fabrics Test Methods" is preferably 0.5 mm or more and 1.2 mm or less. By making the thickness of the artificial leather preferably 0.5 mm or more, more preferably 0.6 mm or more, it becomes an artificial leather that suppresses local damage during molding and processing, while exhibiting excellent strength and abrasion resistance. On the other hand, by making the thickness of the artificial leather preferably 1.2 mm or less, more preferably 1.0 mm or less, it becomes an artificial leather that can uniformly follow complex shapes during molding and processing.

[0151] Furthermore, the artificial leather in this embodiment preferably exhibits a rubbing fastness measured by the "9.1 Clock-meter Method" of JIS L0849:2013 "Test Method for Color Fastness to Rubbing" and a lightfastness measured by the "7.2 Exposure Method a) First Exposure Method" of JIS L0843:2006 "Test Method for Color Fastness to Xenon Arc Light" with a lightfastness of grade 3 or higher. By achieving a rubbing fastness and lightfastness grade of 3 or higher, the artificial leather is designed to resist fading and staining of clothing during actual use. It should be noted that, in the determination of each grade, the rubbing fastness of the artificial leather is determined using the grayscale scale for staining specified in JIS L0805:2005 "Grayscale Scale for Staining," and the lightfastness of the artificial leather is determined using the grayscale scale for fading specified in JIS L0804:2004 "Grayscale Scale for Fading."

[0152] Regarding the friction resistance of the artificial leather, it is believed that the area ratio of the polymer elastomer exposed on the surface of the artificial leather and the thickness t of the nap on the surface of the artificial leather are used to determine its friction resistance. B By adjusting its coefficient of variation to a specific range, the friction between the pile is reduced, which can inhibit the shedding of the pile and improve the friction fastness.

[0153] Furthermore, in the abrasion resistance test conducted according to JIS L1096:2010 "Test Methods for Woven and Knitted Fabrics" under "8.19 Abrasion Strength and Color Change Due to Friction" and "8.19.5 Method E (Martindale Method)," the mass reduction of the artificial leather after 20,000 abrasion cycles with a pressing load of 12.0 kPa is preferably 10 mg or less, more preferably 8 mg or less, and even more preferably 6 mg or less. By reducing the mass to 10 mg or less, contamination caused by lint shedding during actual use can be prevented.

[0154] Regarding the abrasion resistance of the artificial leather, in order to set the mass reduction of the artificial leather after a pressing load of 12.0 kPa and 20,000 abrasion cycles within a specified range, it is considered that the area ratio of the polymer elastomer in the surface of the aforementioned artificial leather and the thickness t of the nap on the surface of the artificial leather are considered. B By adjusting its coefficient of variation to a specific range, the friction between the pile heads is reduced, which can suppress the aforementioned mass reduction.

[0155] In addition, the artificial leather of this embodiment preferably has a tensile strength of 25 N / cm or more and 100 N / cm or less in any test direction, as measured by JIS L1913:2010 "General Nonwoven Fabrics Test Methods" "6.3.1 Tensile Strength and Elongation (ISO Method)".

[0156] When the tensile strength is preferably 20 N / cm or more, more preferably 30 N / cm or more, it becomes a synthetic leather with excellent shape stability and durability. In addition, when the tensile strength is preferably 90 N / cm or less, more preferably 80 N / cm or less, it becomes a synthetic leather that can uniformly follow complex shapes and has good texture during molding and processing.

[0157] [Manufacturing methods for artificial leather] The artificial leather in this embodiment is preferably manufactured by either the first manufacturing method or the second manufacturing method described below.

[0158] That is, one of the preferred methods is <the first manufacturing method>, which has the following characteristics: A process of imparting polyvinyl alcohol (PVA) at a mass of 4% to 40% by mass relative to the mass of the PVA to a fiber complex comprising a nonwoven fabric mainly composed of ultrafine fiber visible fibers, thereby forming a sheet of PVA-impregnated material. The process of forming a nonwoven sheet by making extremely fine fibers with an average single fiber diameter of 0.01 μm to 10.00 μm appear from the aforementioned extremely fine fiber-displaying fibers of the polyvinyl alcohol-treated sheet. The process of widening the nonwoven sheet by 2% to 10% is called widening the sheet. A process of applying a polymeric elastomer to the aforementioned broadened sheet in an amount of 12% to 64% by mass relative to the mass of the broadened sheet, thereby forming a sheet with the polymeric elastomer applied. The process of removing the aforementioned polyvinyl alcohol from the sheet with the aforementioned polymer elastomer to form a matrix sheet; and A process of grinding at least one surface of the aforementioned substrate sheet.

[0159] Alternatively, another preferred method is <the second manufacturing method>, which has the following characteristics: A process of imparting polyvinyl alcohol to a fiber complex containing a nonwoven fabric mainly composed of ultrafine fiber visible fibers in an amount of 4% to 40% by mass relative to the mass of ultrafine fiber visible fibers, thereby forming a sheet imparted with polyvinyl alcohol. The process of widening the sheet by increasing the width of the aforementioned polyvinyl alcohol-treated sheet by more than 2% and less than 10% is formed. The process of making extremely fine fibers with an average single fiber diameter of 0.01μm to 10.00μm appear from the aforementioned extremely fine fiber-visible fibers of the broadened sheet to form a nonwoven sheet; A process of applying a polymeric elastomer at a mass ratio of 12% to 64% relative to the mass of the aforementioned nonwoven sheet to form a sheet with the polymeric elastomer applied. The process of removing the aforementioned polyvinyl alcohol from the sheet with the aforementioned polymer elastomer to form a matrix sheet; and A process of grinding at least one surface of the aforementioned substrate sheet.

[0160] The difference between the first manufacturing method and the second manufacturing method lies in the timing at which the ultrafine fibers are revealed, which will be explained in detail for each.

[0161] <Manufacturing Method 1> In this <First Manufacturing Method>, after forming the polyvinyl alcohol-treated sheet (described later), the extremely fine fibers are made visible before the sheet is widened. This allows for a more uniform widening of the sheet along its width direction while further reducing the equipment load for widening the sheet, resulting in artificial leather with excellent formability, easily tracing complex shapes, and superior surface quality and abrasion resistance after molding.

[0162] <Process for forming sheets endowed with polyvinyl alcohol> In this process, a sheet is formed by applying polyvinyl alcohol to a fiber complex containing a nonwoven fabric mainly composed of ultrafine fiber visible fibers at a mass ratio of 4% to 40% relative to the mass of the ultrafine fiber visible fibers.

[0163] Here, "microfiber-displaying fiber" refers to a fiber that can be made into microfibers by the methods described later. Specifically, examples include: island-type composite fibers, which use thermoplastic resins with different solvent solubility as the sea portion (easily soluble polymer) and the island portion (difficult-to-soluble polymer), and produce microfibers from the island portion by dissolving and removing the sea portion using a solvent; or, peel-type composite fibers, which alternately arrange two thermoplastic resins with different solvent solubility in a radial or multilayered manner on the fiber cross-section, and cut into microfibers by peeling and separating each component. From the viewpoint of the texture and surface quality of artificial leather, island-type composite fibers are more preferred because removing the sea portion can create appropriate gaps between the island portions, i.e., between the microfibers within the fiber bundle. It should be noted that the manufactured microfiber-displaying fiber is sometimes generally referred to as raw cotton.

[0164] As a method for spinning ultrafine fibers with a sea-island composite structure, from the viewpoint of obtaining ultrafine fibers with uniform single fiber diameter, it is preferable to use a polymer alternating arrangement method in which sea-island composite fiber spinnerets are used to spin an alternating arrangement of sea and island parts.

[0165] In this embodiment, to further achieve both deep and uniform color development, the portion of the ultrafine fiber (or the portion corresponding to the island in the case of an island-type composite fiber) may contain black pigment. As a method, any of the following methods can be employed: spinning using thermoplastic resin fragments, wherein the thermoplastic resin fragments are pre-mixed with black pigment in a range of, for example, 0.1% to 5.0% by mass relative to the mass of the thermoplastic resin; or, spinning by mixing masterbatch and thermoplastic resin fragments, wherein the masterbatch is mixed with black pigment in a range of, for example, 10.0% to 40.0% by mass relative to the mass of the thermoplastic resin. The method of using masterbatch and mixing with thermoplastic resin fragments allows for appropriate adjustment of the amount of pigment contained in the ultrafine fiber, and is therefore preferred.

[0166] When using masterbatch and mixing it with fragments of thermoplastic resin, it is preferable to use masterbatch in which the number of primary particle sizes of the black pigment contained in the masterbatch is on average 0.01 μm to 0.05 μm and the coefficient of variation (CV) is 0.1% to 30.0%. By using masterbatch with primary particle sizes within the above range, it is possible to keep the particle size (secondary particle size) and coefficient of variation (CV) in the ultrafine fibers within appropriate ranges.

[0167] As a sea-island type composite fiber, the sea can use polyethylene, polypropylene, polystyrene, copolyesters copolymerized with sodium isophthalate sulfonate and / or polyethylene glycol, and polylactic acid, etc. From the viewpoints of yarn production and easy dissolution, polystyrene and copolyesters are preferred.

[0168] When the microfiber manifested fiber is an island-type composite fiber, it is preferable to use an island-type composite fiber whose island tensile strength (tensile strength of the microfiber) is 2.2 cN / dtex or higher. By making the island tensile strength preferably 2.2 cN / dtex or higher, more preferably 3.0 cN / dtex or higher, and even more preferably 4.0 cN / dtex or higher, the abrasion resistance of the artificial leather can be improved, and the reduction in friction fastness associated with fiber shedding can be suppressed.

[0169] In this embodiment, the tensile strength of the island portion of the island-type composite fiber (tensile strength of the ultrafine fiber) is calculated by the following method.

[0170] (1) Bundle 10 island-type composite fibers, each 20cm long.

[0171] (2) After the sea part is dissolved and removed from the sample in (1), it is air-dried.

[0172] (3) The test was conducted 10 times under the conditions of clamping length of 5cm, stretching speed of 5cm / min and load of 2N in JIS L 1013:2010 "Test Methods for Chemical Fiber Filament Yarns" "8.5 Tensile Strength and Elongation" "8.5.1 Standard Time Test".

[0173] (4) Round the second decimal place of the arithmetic mean (cN / dtex) of the test results obtained from (3), and use the resulting value as the tensile strength of the island part of the island-type composite fiber, that is, the tensile strength of the ultrafine fiber.

[0174] In addition, in this process, after the aforementioned ultrafine visible fibers are opened, they are made into a fiber web using a cross-laying machine or the like, and then nonwoven fabric is obtained by complexing them. Methods for obtaining nonwoven fabric by complexing the fiber web include needle punching and hydroentangling.

[0175] As described above, both short-fiber and long-fiber nonwoven fabrics can be used as the form of nonwoven fabric. Among them, when using short-fiber nonwoven fabric, there are more fibers in the thickness direction of the artificial leather compared to long-fiber nonwoven fabric, which can achieve a high density on the surface of the artificial leather during napping.

[0176] When short-fiber nonwoven fabric is selected as the nonwoven fabric, the obtained ultra-fine fiber manifest type fibers are preferably crimped and cut to a specified length to obtain raw cotton. Then, the fibers are opened, layered, and complexed to obtain short-fiber nonwoven fabric. The crimping and cutting processes can be carried out using known methods.

[0177] Furthermore, in cases where the fiber complex involved in artificial leather includes a fabric, the resulting nonwoven fabric is laminated with the fabric and then integrated into a single unit. For the integration of nonwoven fabric and fabric, the fabric can be laminated on one or both sides of the nonwoven fabric, or the fabric can be sandwiched between multiple nonwoven fabric webs and then the fibers of the nonwoven fabric and fabric can be interwoven through needle punching, hydroentangling, or other treatments.

[0178] The apparent density of nonwoven fabrics containing needle-punched or hydroentangled ultrafine fibers is preferably 0.15 g / cm³. 3 Above 0.35g / cm 3 The following is an example of achieving an apparent density of 0.15 g / cm³. 3 The above, and more preferably, is 0.20 g / cm³. 3 In this way, artificial leather can achieve sufficient morphological and dimensional stability, and can suppress localized damage during molding and processing. On the other hand, by preferably setting the apparent density to 0.35 g / cm³... 3 The following, or more preferably, is 0.30 g / cm³ 3 This allows for maintaining sufficient space for imparting the polymer elastomer, ensuring that the area ratio of the polymer elastomer in the cross-section of the artificial leather is within a specified range.

[0179] For the aforementioned nonwoven fabrics, heat shrinkage treatment using warm water or steam is also a preferred method to improve the density of the fibers.

[0180] Next, polyvinyl alcohol (PVA) is applied to the aforementioned fiber complex at a concentration of 4% to 40% by mass relative to the mass of the ultrafine fiber-like fibers, forming a sheet coated with PVA. By applying PVA, the area ratio of polymeric elastomers in the cross-section of the final artificial leather is kept within a specified range, resulting in artificial leather with excellent formability, dense and uniform surface quality, abrasion resistance, and texture, allowing for easy shaping of complex forms. It should be noted that one method of applying PVA is to impregnate an aqueous solution of PVA and then dry it.

[0181] In this embodiment, polyvinyl alcohol is preferably applied at a rate of 4% to 40% by mass relative to the mass of the ultrafine fiber-like fibers to form a sheet coated with polyvinyl alcohol. By preferably applying 4% by mass or more, more preferably 8% by mass or more, and even more preferably 16% by mass or more, the dimensional stability is improved during the process of forming the sheet coated with the polymer elastomer because the polyvinyl alcohol fixes the fibers, thus allowing for a reduction in the thickness t of the final artificial leather substrate portion. A The coefficient of variation is within a specified range. On the other hand, by making the amount of polyvinyl alcohol preferably 40% by mass or less, more preferably 32% by mass or less, and even more preferably 24% by mass or less, the presence of polyvinyl alcohol in the process of imparting the polymer elastomer can moderately mitigate the adhesion between the fiber and the polymer elastomer, and make the area ratio of the polymer elastomer in the cross section of the artificial leather within a specified range, so that it can uniformly follow complex shapes during molding and processing, and can produce artificial leather with good texture.

[0182] In this process, it is preferable to include polyethylene glycol at a content of 0.01% to 0.5% by mass relative to the aforementioned polyvinyl alcohol. By preferably including 0.01% by mass or more, and more preferably 0.1% by mass or more, foaming of the water-soluble resin can be suppressed and the mixing time shortened during the mixing of the aqueous solution of the water-soluble resin. On the other hand, by preferably including 0.5% by mass or less, and more preferably 0.3% by mass or less, polyvinyl alcohol can be imparted to the aforementioned fiber complex in a uniform size, ensuring that the area ratio of the polymeric elastomer in the cross-section of the final artificial leather is within a specified range.

[0183] <Processes for forming nonwoven sheets> In this process, extremely fine fibers with an average single fiber diameter of 0.01 μm to 10.00 μm are made to appear from the extremely fine fiber-displaying fibers of the aforementioned polyvinyl alcohol-treated sheet, thereby forming a nonwoven sheet.

[0184] To make ultrafine fibers with an average single fiber diameter within the aforementioned range visible from the ultrafine fiber-visible fibers of the aforementioned polyvinyl alcohol-treated sheet, this can be achieved by impregnating the aforementioned polyvinyl alcohol-treated sheet in a solvent, etc. In the case where the ultrafine fiber-visible fiber is a sea-island type composite fiber, this can be achieved by dissolving and removing its sea-like portion, etc.

[0185] When the ultrafine fiber manifested as a sea-island type composite fiber, organic solvents such as toluene and trichloroethylene can be used as solvents to dissolve and remove its sea portion, provided the sea portion is made of polyethylene, polypropylene, or polystyrene. Alternatively, alkaline aqueous solutions such as sodium hydroxide can be used when the sea portion is made of copolyester or polylactic acid. Furthermore, hot water (water at 70°C to 99°C) can be used when the sea portion is made of water-soluble thermoplastic polyvinyl alcohol resin.

[0186] In addition, by repeatedly impregnating the polyvinyl alcohol-impregnated sheet in a solvent and squeezing and compressing it using a rolling mill, ultrafine fibers can be efficiently revealed from ultrafine fiber-revealing fibers.

[0187] Furthermore, as a treatment to disperse the exposed ultrafine fibers, it is preferable to pass water through the interior of the nonwoven sheet in a liquid. This water flow applies mechanical impact to the bundled ultrafine fibers, thus dispersing them. Specifically, a vibratory washing machine or similar device can be used. This vibratory washing machine is preferred from the perspective of being able to uniformly disperse the fibers across the entire surface of the nonwoven sheet.

[0188] <Processes for forming widened sheets> In this process, the width of the aforementioned nonwoven sheet is increased by more than 2% and less than 10% to form an expanded sheet.

[0189] By preferably increasing the width of the aforementioned nonwoven sheet by 2% or more, and more preferably by 3% or more, the adhesion between the ultrafine fibers and polyvinyl alcohol is mitigated. This allows for adjustment of the adhesion between the ultrafine fibers and the polymeric elastomer during the subsequent process of forming the sheet with the polymeric elastomer. As a result, artificial leather that can uniformly follow complex shapes during molding is produced. On the other hand, by preferably increasing the width of the nonwoven sheet by 10% or less, and more preferably by 8% or less, the equipment load can be reduced, and the widening can be uniform along the width direction of the nonwoven sheet. Furthermore, the apparent density of the polyvinyl alcohol contained in the aforementioned nonwoven sheet can be appropriately reduced, and the area ratio of the polymeric elastomer in the cross-section and surface of the final artificial leather can be kept within a specified range.

[0190] <Process for forming sheets endowed with polymer elastomers> In this process, a polymeric elastomer is applied to the aforementioned broadened sheet at a concentration of 12% to 64% relative to the mass of the broadened sheet, forming a sheet with the polymeric elastomer. More specifically, it is preferable to impregnate the aforementioned broadened sheet with a solution of a polymeric elastomer precursor at a concentration of 12% to 64% relative to the mass of the broadened sheet, and then cure it to form a sheet with the polymeric elastomer. Here, the polymeric elastomer precursor refers to a precursor that becomes a polymeric elastomer through means such as coagulation and curing described later (hereinafter, it is sometimes simply referred to as "precursor"). For example, if the polymeric elastomer is polyurethane, the mixture of the various reactive components of polyurethane, namely polymeric diol, organic diisocyanate, chain extender, etc., is the polyurethane precursor.

[0191] In this embodiment, to further achieve both deep and uniform color rendering, a polymeric elastomer containing black pigment can be applied to the aforementioned broadened sheet. One method is to include a black pigment in the precursor of the polymeric elastomer. Preferably, the black pigment used has an average primary particle size of 0.01 μm to 0.05 μm and a coefficient of variation (CV) of 0.1% to 30.0%. By using a black pigment with a primary particle size within the above range, the particle size (secondary particle size) and coefficient of variation (CV) in the polymeric elastomer can be kept within appropriate ranges.

[0192] As a solvent used to impart polymeric elastomers to fiber complexes, N,N'-dimethylformamide, dimethyl sulfoxide, etc., are preferred. Alternatively, an aqueous dispersion prepared by dispersing the polymeric elastomer in water in the form of an emulsion can also be used.

[0193] <Processes for forming the substrate sheet> In this process, the polyvinyl alcohol is removed from the aforementioned sheet with the polymer elastomer to form a base sheet. One method is to immerse the aforementioned sheet with the polymer elastomer in water heated to 65°C to 95°C (hot water) and then dry the sheet.

[0194] It should be noted that the process of forming the matrix sheet can also be performed simultaneously with the aforementioned process of forming a sheet with a polymer elastomer. That is, the polyvinyl alcohol can be removed simultaneously by immersion in hot water, in conjunction with the process of removing solvents such as N,N'-dimethylformamide and dimethyl sulfoxide used when imparting the polymer elastomer to the fiber complex. In this embodiment, under such circumstances, both the process of forming a sheet with a polymer elastomer and the process of forming the matrix sheet are considered to have been performed.

[0195] In this process, at least one surface of the aforementioned substrate sheet is ground. This gives the surface a napped texture, forming a napped surface. For this grinding, sandpaper, a roll sander, or similar grinding method is preferably used. Furthermore, from a manufacturing efficiency perspective, it is preferable to cut the aforementioned substrate sheet in half along its thickness direction to produce two sheets before this grinding. It should be noted that this grinding can be performed on only one side of the aforementioned sheet or on both sides, but when grinding two sheets made by cutting them in half along their thickness direction, it is preferable to grind the newly formed surface (half-cut surface) after cutting in half.

[0196] In the grinding of the substrate sheet, in order to produce artificial leather that maintains excellent surface quality even after molding, the number of grinding operations performed by the grinding means is preferably two or more times, more preferably three or more times, in multiple stages. Furthermore, it is even more preferable that the sandpaper and pressure roller grinding machine used in each stage are progressively finer, or at least the same.

[0197] The grit size of the sandpaper and roller abrasive used to grind the surface of the aforementioned substrate sheet (equivalent to the surface of artificial leather) is preferably set to the range of 100 grit to 320 grit as specified in JIS R6610:2000 "Grit Size of Abrasive Material for Abrasive Cloth". By preferably using a grit size of 100 grit or higher, and more preferably 120 grit or higher, the thickness t of the pile head can be reduced. B Within a specified range, artificial leather with an excellent tactile feel can be produced. On the other hand, by preferably using sandpaper or a grinding roller with a grit size of 320 or less, and more preferably 240 or less, artificial leather with a dense feel and a uniform and beautiful surface quality can be produced.

[0198] When at least one surface of the aforementioned substrate sheet is repeatedly ground by grinding, it is preferable to set the transport speed of the substrate sheet to 10 m / min or more and 20 m / min or less. By setting the transport speed of the substrate sheet to preferably 10 m / min or more, and more preferably 13 m / min or more, it is possible to achieve good productivity while reducing the thickness t of the pile head. B Within the specified range. On the other hand, by making the transport speed of the base sheet preferably 20 m / min or less, more preferably 17 m / min or more, it is possible to suppress the equipment load and keep the area ratio of the polymer elastomer in the surface of the artificial leather within the specified range, so that a dense and uniform surface quality can be achieved even after molding and processing. It should be noted that the transport speed of the base sheet referred to here refers to the speed at which the sheet is supplied by the roller or pressure roller grinding machine that makes the sandpaper rotate at high speed.

[0199] Furthermore, the grinding speed is preferably set to 200 m / min or more and 1000 m / min or less. By setting the grinding speed to preferably 200 m / min or more, and more preferably 300 m / min or more, it is possible to suppress the equipment load and reduce the thickness t of the felt head. B Within a specified range, artificial leather with an excellent tactile feel can be produced. Furthermore, by preferably using a grinding speed of 1000 m / min or less, and more preferably 900 m / min or less, the area ratio of the polymer elastomer in the surface of the artificial leather can be kept within a specified range, achieving a dense and uniform surface quality even after molding. The grinding speed referred to here is the circumferential speed calculated from the rotational speed and circumference of the sandpaper or roller grinder, and specifically, it can be calculated using the following formula: Grinding speed (m / min) = {rotational speed of sandpaper or pressure roller grinder (rpm / min)} × {circumference of sandpaper or pressure roller grinder (m / rpm)} ··· (formula).

[0200] Prior to the grinding process, a lubricant such as a silicone emulsion can be applied to the surface of the aforementioned substrate sheet. Furthermore, by applying an antistatic agent before grinding, grinding powder generated from the artificial leather during grinding is less likely to accumulate on the sandpaper.

[0201] Here, the unit area mass of the ground sheet obtained after the aforementioned grinding is preferably set to 150 g / m². 2 Above 450g / m 2 The following is an example. The preferred unit area mass of the sheet obtained after grinding is 150 g / m². 2 The above, and more preferably 175g / m 2 This results in the production of artificial leather that not only suppresses breakage of the sheet material during this process but also inhibits damage during molding, and exhibits excellent strength and abrasion resistance. Furthermore, the preferred unit area mass of the sheet material is 450 g / m². 2 The following, or more preferably, is 400g / m 2 This allows for the production of artificial leather that can uniformly follow complex shapes during the molding process.

[0202] <Second Manufacturing Method> In this <Second Manufacturing Method>, after forming the polyvinyl alcohol-treated sheet (described later), the sheet is widened to reveal the extremely fine fibers. This results in artificial leather that possesses excellent formability, allowing for easy adaptation to more complex shapes, superior surface quality after molding, and a soft texture.

[0203] <Process for forming sheets endowed with polyvinyl alcohol> This process is exactly the same as the first manufacturing method.

[0204] <Processes for forming widened sheets> This process is basically the same as the "Process of Forming Widened Sheets" in the "First Manufacturing Method," but the difference lies in the method used. In the "Process of Forming Widened Sheets" of the "First Manufacturing Method," the ultrafine fibers are widened through the exposed nonwoven sheet, while in this process, the width of the aforementioned polyvinyl alcohol-treated sheet is widened by 2% to 10% to form a widened sheet. For details, in the "Process of Forming Widened Sheets" of the "First Manufacturing Method," the phrase "nonwoven sheet" will be replaced with "polyvinyl alcohol-treated sheet" for explanation.

[0205] <Processes for forming nonwoven sheets> This process is basically the same as the "Process for Forming Nonwoven Sheets" in the "First Manufacturing Method". However, in the "Process for Forming Nonwoven Sheets" of the "First Manufacturing Method", the sheet coated with polyvinyl alcohol before the ultrafine fibers are revealed is expanded. In this process, ultrafine fibers with an average single fiber diameter of 0.01 μm to 10.00 μm are revealed from the aforementioned ultrafine fiber revealing type of the expanded sheet to form a nonwoven sheet. This part is different. For details, in the "Process for Forming Nonwoven Sheets" of the "First Manufacturing Method", the phrase "sheet coated with polyvinyl alcohol" will be replaced with "expanded sheet" for explanation.

[0206] <Process for forming sheets endowed with polymer elastomers> This process is basically the same as the "Process of Forming a Sheet Tonified with a Polymer Elastomer" in the "First Manufacturing Method". However, in the "Process of Forming a Sheet Tonified with a Polymer Elastomer" in the "First Manufacturing Method", a polymer elastomer is tonified onto a broadened sheet, while in this process, a polymer elastomer is tonified onto the aforementioned nonwoven sheet in an amount of 12% to 64% relative to the mass of the nonwoven sheet to form a sheet tonified with a polymer elastomer. This part is different. For details, in the "Process of Forming a Sheet Tonified with a Polymer Elastomer" in the "First Manufacturing Method", the phrase "broadened sheet" will be replaced with "nonwoven sheet" for explanation.

[0207] <Processes for forming the substrate sheet> This process is exactly the same as the first manufacturing method.

[0208] This process is exactly the same as the first manufacturing method.

[0209] <Subsequent processes of Manufacturing Method 1 and Manufacturing Method 2> Furthermore, the sheet obtained by grinding at least one surface of the aforementioned substrate sheet can also be dyed using either the first manufacturing method or the second manufacturing method.

[0210] As for dyeing methods, the following dyeing treatments can be used: liquid dyeing using a roll dyeing machine or a liquid dyeing machine; immersion dyeing using a continuous dyeing machine or hot melt dyeing; or dyeing treatment of the napped surface based on roller dyeing, screen dyeing, inkjet dyeing, sublimation dyeing, and vacuum sublimation dyeing; etc. Among these, liquid dyeing machines are preferred from the perspective of quality and taste because they can produce a soft texture. In addition, various resin finishing processes can be performed after dyeing as needed.

[0211] Furthermore, the sheets obtained through the above methods can be used directly as artificial leather. Moreover, their surface can be further processed as needed to create artificial leather with superior design capabilities. For example, post-processing treatments such as perforation, embossing, laser processing, Pinsonic processing, and printing can be performed. In addition, various resin finishing processes can be implemented.

[0212] [Vehicle interior materials, vehicle parts, groceries, furniture] The artificial leather of this embodiment, obtained through the manufacturing method illustrated above, achieves both excellent formability, capable of following complex shapes during molding, and a dense and smooth surface quality after molding. Therefore, it is particularly suitable as a material for applications such as vehicle interior materials and interior decoration.

[0213] First, vehicle interior materials incorporating the aforementioned artificial leather are preferred because they exhibit characteristics such as ease of conforming to complex shapes during molding and a dense, smooth surface finish after molding. Such vehicle interior materials are preferably used in vehicle components such as steering wheels, horn switches, gear shift knobs, dashboards, instrument panels, glove boxes, floor mats, floor carpets, headliners, sun visors, and auxiliary handles in automobiles; more preferably, these vehicle components include the aforementioned artificial leather. It should be noted that in this embodiment, "vehicle" refers to vehicles such as automobiles, aircraft, railway vehicles, and ships; horse-drawn carriages, sedan chairs, and rickshaws; and some industrial, construction, and agricultural machinery capable of carrying people or animals, such as excavators, cranes, tractors, and combine harvesters.

[0214] Alternatively, goods containing the aforementioned artificial leather are also a preferred embodiment. Examples of such goods include clothing accessories such as shoes, hats, bags, belts, scarves, ties, and wallets, as well as interior decoration items such as cushions, armrests, and neck pillows.

[0215] Examples of such shoes include athletic shoes, low-cut shoes, loafers, boots, sandals, slippers, and spiked shoes. Furthermore, at least a portion of the upper, lining, midsole, and laces of such shoes is preferably made of the aforementioned synthetic leather.

[0216] Examples of such bags include handbags, tote bags, shoulder bags, Boston bags, waist bags, briefcases, briefcases, and backpacks. Furthermore, at least a portion of the handles, inner pockets, connecting leather, sides, and bottom of such bags is preferably made of the aforementioned synthetic leather.

[0217] Furthermore, furniture incorporating the aforementioned artificial leather is also a preferred option. Examples of such furniture include chairs, sofas, and stools. Moreover, at least a portion of the seat, backrest, etc., of such furniture is preferably made of the aforementioned artificial leather.

[0218] Example The artificial leather of this embodiment will be further described in detail below using examples, but this embodiment is not limited to these examples.

[0219] [Determination methods and processing methods for evaluation] Next, the evaluation methods and measurement conditions used in the examples will be described. Unless otherwise specified, the determination of each physical property is based on the aforementioned methods.

[0220] (1) Average single fiber diameter (μm) of ultrafine fibers: In determining the average single fiber diameter of ultrafine fibers, a scanning electron microscope (SEM) of the "VHX-D500 / D510" type manufactured by KEYENCE Co., Ltd. was used to observe the ultrafine fibers and calculate the average single fiber diameter.

[0221] (2) Tensile strength of ultrafine fibers (cN / dtex): In the determination of the tensile strength of ultrafine fibers, the Tensilon universal testing machine "RTC-1350A" manufactured by A&D Corporation was used, and the results were determined and calculated using the aforementioned method.

[0222] (3) The thickness t of the base material of the artificial leather A (μm) and its coefficient of variation (%): The thickness t of the base material of artificial leather AIn the measurement, a scanning electron microscope (SEM) manufactured by KEYENCE Co., Ltd., "VHX-D500 / D510", was used to observe the cross-section of the artificial leather, and the thickness t of the substrate portion of the artificial leather was calculated. A and its coefficient of variation.

[0223] (4) The thickness t of the napped head of the artificial leather B (μm) and its coefficient of variation (%): The thickness t of the suede head of artificial leather B In the measurement, a scanning electron microscope (SEM) manufactured by KEYENCE Co., Ltd., "VHX-D500 / D510", was used to observe the cross-section of the artificial leather, and the thickness t of the artificial leather's nap was calculated. B and its coefficient of variation.

[0224] (5) Mass per unit area of ​​artificial leather (g / m²) 2 ): The mass per unit area of ​​artificial leather is determined and calculated using the methods described above.

[0225] (6) Thickness of artificial leather (mm): In measuring the thickness of artificial leather, the thickness was measured and calculated using the "Peacock Dial Thickness Gauge H" manufactured by Ozaki Manufacturing Co., Ltd.

[0226] (7) Mass percentage of polymeric elastomer (mass%): In determining the mass ratio of polymeric elastomers, dimethylformamide is used as a solvent for measurement and calculation.

[0227] (8) The area ratio (%) and standard deviation (%) of polymeric elastomer in the surface of the artificial leather with the napped head: In the above measurements, a field emission scanning electron microscope was used, manufactured by JEOL Ltd., and "ImageJ" was used as the image analysis software for measurement and calculation.

[0228] (9) The area ratio (%) and standard deviation (%) of polymer elastomer in the cross-section of artificial leather: In the above measurements, a field emission scanning electron microscope was used, manufactured by JEOL Ltd., and "ImageJ" was used as the image analysis software for measurement and calculation.

[0229] (10) Tensile strength of artificial leather (N / cm): For any direction of artificial leather, collect 2 test pieces of 2 cm × 20 cm, and measure the tensile strength (N / cm) specified in "6.3.1 Tensile Strength and Elongation at Break (ISO Method)" of JIS L1913:2010 "General Test Methods for Nonwoven Fabrics". During the measurement, take the average of the 2 test pieces as the tensile strength of the artificial leather. It should be noted that during the measurement, use the Instron Single Column Tabletop Tester "3343" manufactured by Instron Corporation.

[0230] (11) Rub fastness of artificial leather (grade): Judge the degree of contamination of the sample after the friction test with the aforementioned contamination gray scale, and set 4 or more levels (based on color difference of the color system being 4.5 ± 0.3 or less) as qualified.

[0231] (12) Light fastness of artificial leather (grade): Judge the degree of color change and fading of the sample after xenon arc lamp irradiation with the aforementioned color change and fading gray scale, and set 4 or more levels (based on color difference of the color system being 1.7 ± 0.3 or less) as qualified.

[0232] (13) Lightness of artificial leather ( value, unitless): Use a spectrocolorimeter to measure the L value specified in "3.3 CIE1976 Lightness Index" of JIS Z8781-4:2013 "Colorimetry - Part 4: Color Space". During the measurement, conduct 10 measurements through "CM-M6" manufactured by Konica Minolta, Inc., and take the average value as the value of the artificial leather.

[0233] (14) Abrasion resistance of artificial leather (mg): Use "Model 406" manufactured by James H. Heal & Co., Ltd. as the abrasion tester, and use "Abrasive CLOTH SM25" manufactured by James H. Heal & Co., Ltd. as the standard friction cloth to conduct the aforementioned abrasion resistance test (which is an abrasion resistance test determined according to "8.19 Abrasion Strength and Friction Color Change" of JIS L1096:2010 "Test Methods for Woven and Knitted Fabrics", "8.19.5 Method E (Martindale Method)"), where the pressing load is set to 12.0 kPa and the number of abrasion times is 20,000 times). Set the artificial leather with a wear reduction of 10 mg or less as qualified.

[0234] (15) The tactile feel of artificial leather: The tactile feel of the artificial leather is assessed using the sensory evaluation method described below. Specifically, 20 evaluators (10 healthy adult men and 10 healthy adult women) are selected to evaluate the velvety surface of the artificial leather according to the evaluation criteria below. The highest number of evaluations is taken as the tactile feel rating of the artificial leather. In the case of identical evaluations, the higher evaluation is taken as the tactile feel rating of the artificial leather. In this embodiment, a level of "good" is designated as A or B.

[0235] • A: Even when you touch the surface, you can't feel the very smooth texture of hooks.

[0236] •B: The surface has a smooth, slightly hooking feel when touched.

[0237] • C: When touching the surface, you feel a rough, hooking sensation.

[0238] • D: When touching the surface, you can feel a very rough texture with a noticeable hooking sensation.

[0239] (16) Surface quality of artificial leather: The surface quality of the artificial leather is evaluated using the sensory evaluation method described below. Specifically, 20 people (10 healthy adult men and 10 healthy adult women, totaling 20) are used as evaluators. They visually identify the following evaluation criteria, and the highest number of evaluations is taken as the surface quality rating of the artificial leather. In the case of equal numbers of evaluations, the higher evaluation is taken as the surface quality rating of the artificial leather. In this embodiment, a "good" level is defined as either A or B.

[0240] • A: A very dense and uniform surface quality.

[0241] • B: A dense and uniform surface quality.

[0242] • C: Surface quality that lacks density and is uneven.

[0243] • D: Surface quality is very lacking in density and uneven.

[0244] (17) Coefficient of variation (%) of the area change rate of artificial leather before and after molding and processing: As an indicator of the surface quality after molding when using artificial leather as an outer layer, the coefficient of variation of the area change rate before and after molding is evaluated using the methods shown in (i) to (viii) below. The smaller the value, the more uniform the deformation. Artificial leather with a coefficient of variation of area change rate of less than 30% is evaluated as artificial leather with excellent uniform deformability and good surface quality.

[0245] (i) Ten A4-sized (210 mm × 297 mm) evaluation samples were randomly collected from artificial leather.

[0246] (ii) Mark a 5mm × 5mm grid (square lines) on the surface of the velvet layer side of the collected evaluation sample.

[0247] (iii) On the surface opposite to the surface of the velvet layer with the grid markings, a film-like olefin-based hot melt resin (thickness 50 μm, mass per unit area 20 g / m²) is applied. 2 It is used to laminate high-density polyethylene (PE) with a thickness of 500μm to form a film.

[0248] (iv) An evaluation sample was prepared by bonding the film to a concave cylindrical mold with an area unfolding ratio of 212% (50 mm in diameter × 14 mm in height), with the surface of the velvet layer as the mold side, and vacuum forming was performed at room temperature.

[0249] (v) The area of ​​the grid marked on the napped side of the evaluation sample obtained in the vacuum forming process was measured. In the measurement, a KEYENCE VHX-5000 digital microscope was used, and the magnification was adjusted to 20x to measure the above area.

[0250] (vi) The area of ​​the measured grid (mm²) 2 Divide by the original area before molding (5mm × 5mm = 25mm) 2 ), as a percentage, calculate the area change rate (%).

[0251] (vii) Calculate the arithmetic mean and standard deviation of the area change rate (%) for each grid.

[0252] (viii) Using the value calculated in (vii), calculate the coefficient of variation (%) of the area change rate using the following formula, and round the first decimal place. The coefficient of variation (%) of the area change rate = standard deviation of the area change rate / arithmetic mean of the area change rate × 100 ··· (formula).

[0253] (18) The area ratio (%) of polymeric elastomer in the surface of the side with the napped head of the molded artificial leather: As an indicator of the surface quality after molding when using artificial leather as an outer layer, the area ratio of polymeric elastomers in the surface of the molded artificial leather with the napped side is evaluated. Artificial leather with an area ratio of polymeric elastomers of 3.00% or less in the surface of the molded artificial leather with the napped side, when processed into an outer layer, can suppress the decrease in surface quality caused by increased exposure of polymeric elastomers, and is thus evaluated as having good surface quality.

[0254] (i) Collect grids on the surface of the pile head side of the molded article obtained from the area change rate (%) recorded in (17), where the area change rate is in the range of 145% to 155%. It should be noted that if there are no grids in the range of 145% to 155%, collect grids that exist in the range of 135% to 144% or 156% to 165%.

[0255] (ii) Using the collected grid, the area ratio (%) of polymeric elastomers in the surface of the artificial leather with the napped head was determined in the same manner as in the aforementioned “(8) Area ratio (%) of polymeric elastomers in the surface of the artificial leather with the napped head.”

[0256] (19) Surface quality of artificial leather after molding and processing (points): The evaluation samples processed into cylindrical shapes were used in the aforementioned "(17) Coefficient of variation (%) of the area change rate of artificial leather". For the molded products obtained by vacuum forming, 10 healthy adult males and 10 adult females, a total of 20 people, were used as evaluators to judge the surface quality of the processed artificial leather according to the following 5-level evaluation criteria. The surface quality of the processed artificial leather was evaluated by the total score of the scores judged by each evaluator. Therefore, the total score ranged from a minimum of 20 points to a maximum of 100 points, and a score of 80 points or above was judged as qualified.

[0257] · 5 stars, excellent (the artificial leather is shaped into a cylindrical form without any quality degradation caused by increased exposure of polymer elastomers on the surface of the processed artificial leather) 4 points is good (between 5 and 3 points) • 3 points (Ordinary) (Artificial leather cannot be shaped into a cylindrical shape, or the exposure of polymer elastomers on the surface of the processed artificial leather increases, indicating a decrease in quality. • 2-point difference (between 3 and 1 points) • 1 point Very poor (artificial leather cannot be shaped into a cylindrical shape, and the exposure of polymer elastomers on the surface of the processed artificial leather increases significantly, resulting in a significant reduction in quality).

[0258] [Example 1] <Process for forming sheets endowed with polyvinyl alcohol> Ultrafine fiber manifested fiber with island-type composite structure formed from island and sea components is melt-spun under the following conditions.

[0259] • Island component: Polyethylene terephthalate with an intrinsic viscosity (IV value) of 0.73 • Sea composition: Polystyrene with an MFR (melt flow rate, determined by the test method specified in ISO 1133:1997, hereinafter the same) of 65 g / 10 min. • Spinneret: Island-type spinneret for composite fibers with 16 islands / hole • Spinning temperature: 285℃ • Island / Sea mass ratio: 80 / 20 • Discharge rate: 1.2g / (min·hole) Spinning speed: 1100m / min.

[0260] Next, the ultrafine fiber manifestation type was stretched to 2.7 times its original length in a spinning oil bath set at 90°C. Then, after crimping using a crimping machine, it was cut into 51mm lengths to obtain raw cotton of island-of-the-sea composite fiber with a single fiber fineness of 4.2 dtex. The ultrafine fiber obtained from this island-of-the-sea composite fiber has an average single fiber diameter of 4.40 μm and an ultrafine fiber strength of 3.7 cN / dtex.

[0261] In addition, the raw cotton obtained in the above manner is used to form a multilayered web through a carding and cross-laying machine process. Then, at a density of 2500 threads / cm 2 The number of needles was used for acupuncture treatment, and the mass per unit area was 470 g / m². 2 A fiber complex containing nonwoven fabric formed from ultrafine fiber manifest fibers, with a width of 183cm and a thickness of 2.1mm.

[0262] The fiber complex obtained in the above manner is shrunk using hot water at 96°C. Then, a polyvinyl alcohol aqueous solution with a saponification degree of 88% (prepared at a concentration of 12% by mass, containing 0.13% by mass polyethylene glycol relative to the mass of polyvinyl alcohol (hereinafter, sometimes simply referred to as PVA)) is impregnated onto the nonwoven fabric that has undergone the hot water shrinkage treatment. Further, it is rolled and dried with hot air at 120°C for 10 minutes, thereby forming a sheet of polyvinyl alcohol-constituted polyvinyl alcohol with a PVA mass of 23% by mass relative to the mass of the nonwoven fabric formed from the ultrafine fiber manifestation type fibers.

[0263] <Processes for forming nonwoven sheets> The obtained polyvinyl alcohol-impregnated sheet is impregnated with trichloroethylene, and then subjected to a squeezing and compression process using a rolling mill 10 times. This process dissolves and removes the capillaries of the ultrafine fibers and compresses the sheet, resulting in a nonwoven sheet with an average single fiber diameter of 4.40 μm and a width of 158 cm after the ultrafine fibers are developed.

[0264] <Processes for forming widened sheets> Furthermore, the nonwoven sheet is widened to 163cm using a tenter frame, that is, the width of the nonwoven sheet is increased by 3%, forming a widened sheet.

[0265] <Processes for forming sheets with polymer elastomers and processes for forming matrix sheets> The widened sheet obtained in the above manner was impregnated with a DMF (dimethylformamide) solution of polyurethane, prepared with a solid component concentration of 13.0% as the main component of the polyurethane elastomer and a polymer glycol of polycarbonate diol. Then, the widened sheet impregnated with the polyurethane DMF solution was rolled using rollers. Next, the sheet was impregnated in a 30% by mass DMF aqueous solution to allow the polyurethane to solidify. At this point, the amount of the polymer elastomer relative to the mass of the widened sheet was 27% by mass. Then, the PVA and DMF were removed with hot water at 95°C, and the sheet was dried with hot air at 100°C for 10 minutes. This yielded a matrix sheet with a width of 153 cm, a thickness of 1.7 mm, and a polyurethane mass relative to the mass of the microfiber of 35% by mass.

[0266] The substrate sheet obtained in the above manner was cut in half, with each half being 1 / 2 of its thickness. Next, the sheet was transported at a speed of 13 m / min, and the surface layer of the non-half-cut side was ground to a finer degree of napping (0.30 mm). The grinding speed was 900 m / min for the first stage and 700 m / min for the second stage, using ring-shaped sandpaper of grit 120 (referred to as "#120" in Tables 1 and 2; the same applies to other grits). The result was an extremely fine fiber with an average single fiber diameter of 4.40 μm, a width of 153 cm, and a unit area mass of 200 g / m². 2 A ground sheet with a thickness of 0.55mm.

[0267] <The process of dyeing ground sheet> The aforementioned ground sheet was dyed using a liquid flow dyeing machine, followed by reduction cleaning to obtain a dyed sheet. During the dyeing process, black dye was used, and the dyed sheet was then... The formula was prepared with a value of 22, and the temperature of the dyeing solution was set to 120°C. Then, it was dried at 100°C for 7 minutes using a tenter frame to obtain artificial leather with a thickness of 0.65 mm and a polymer elastomer content of 26% by mass.

[0268] The resulting artificial leather is highly dense, with a uniform surface quality, resulting in a very smooth feel and excellent wear resistance. Furthermore, the artificial leather, after molding, is shaped into a cylindrical form without any reduction in surface quality before or after molding. The results are shown in Tables 1 and 2.

[0269] [Example 2] In the <Process of Forming Widened Sheet>, as shown in Table 1, the nonwoven sheet with a width of 158cm is widened to 161.5cm, that is, the width of the nonwoven sheet is widened by 2%. Otherwise, the same procedure as in Example 1 is followed to obtain artificial leather.

[0270] The resulting artificial leather has a dense texture, uniform surface quality, a very smooth feel, and excellent abrasion resistance. Furthermore, regarding the molded artificial leather, it achieves a cylindrical shape without any reduction in surface quality before or after molding. The results are shown in Tables 1 and 2.

[0271] [Example 3] In the <Process of Forming Widened Sheet>, as shown in Table 1, the nonwoven sheet with a width of 158cm is widened to 172cm, that is, the width of the nonwoven sheet is widened by 9%. Otherwise, the same operation as in Example 1 is performed to obtain artificial leather.

[0272] The resulting artificial leather is very dense, with a uniform surface quality and a smooth feel. Furthermore, regarding the shaped artificial leather, it achieves a cylindrical shape without any reduction in surface quality before or after the shaped process. The results are shown in Tables 1 and 2.

[0273] [Example 4] In the process of forming a sheet of polyvinyl alcohol, the ultrafine fiber manifested fiber having an island-type composite structure formed from island and sea components is melt-spun under the following conditions, otherwise the operation is the same as in Example 1 to obtain artificial leather.

[0274] • Island composition: The following components P1 and P2 are mixed in a mass ratio of 95:5. P1 Polyethylene terephthalate with an intrinsic viscosity (IV value) of 0.73 P2 contains 20% by mass of carbon black (average particle size: 0.02 μm, coefficient of variation (CV): 20%) relative to the masterbatch in the above polyethylene terephthalate A as a masterbatch for black pigment. • Sea composition: Polystyrene with an MFR (melt flow rate, determined by the test method specified in ISO 1133:1997) of 65 g / 10 min. • Spinneret: Island-type spinneret for composite fibers with 16 islands / hole Spinning temperature: 285℃ • Island / Sea mass ratio: 80 / 20 • Discharge rate: 1.2g / (min·hole) Spinning speed: 1100m / minute.

[0275] The resulting artificial leather is highly dense, with a uniform surface quality, a very smooth feel, and excellent abrasion resistance. Furthermore, regarding the molded artificial leather, it achieves a cylindrical shape without any reduction in surface quality before or after molding. The results are shown in Tables 1 and 2.

[0276] [Table 1] [Table 2] [Example 5] In the process of forming a sheet of polyvinyl alcohol, as shown in Table 3, 4% by mass of PVA is applied relative to the mass of the nonwoven fabric formed from the microfiber-like fibers. Otherwise, the process is the same as in Example 1 to obtain artificial leather.

[0277] The resulting artificial leather has a dense texture, uniform surface quality, a smooth feel, and excellent abrasion resistance. Furthermore, regarding the molded artificial leather, it achieves a cylindrical shape without any reduction in surface quality before or after molding. The results are shown in Tables 3 and 4.

[0278] [Example 6] In the process of forming a sheet of polyvinyl alcohol, as shown in Table 3, 40% by mass of PVA is applied relative to the mass of the nonwoven fabric formed from the microfiber-like fibers. Otherwise, the process is the same as in Example 1 to obtain artificial leather.

[0279] The resulting artificial leather is very dense, with a uniform surface quality and a smooth feel. Furthermore, regarding the molded artificial leather, it was shaped into a cylindrical form, and there was no reduction in surface quality before or after the molding process. The results are shown in Tables 3 and 4.

[0280] [Example 7] In the process of forming a sheet of polyvinyl alcohol, as shown in Table 3, 48% by mass of PVA is imparted relative to the mass of the nonwoven fabric formed from the microfiber-like fibers. Otherwise, the process is the same as in Example 1 to obtain artificial leather.

[0281] The resulting artificial leather has a dense texture, uniform surface quality, and a smooth feel. Furthermore, regarding the molded artificial leather, it was shaped into a cylindrical form, and there was no reduction in surface quality before or after the molding process. The results are shown in Tables 3 and 4.

[0282] [Example 8] In the process of forming a sheet of polyvinyl alcohol, as shown in Table 3, a PVA aqueous solution with a saponification degree of 88% (containing 0.60% polyethylene glycol relative to the mass of PVA) prepared at a concentration of 12% by mass was impregnated into a nonwoven fabric that had been shrunk by hot water. Otherwise, the process was the same as in Example 1 to obtain artificial leather.

[0283] The resulting artificial leather has a dense texture, uniform surface quality, and a smooth feel. Furthermore, regarding the molded artificial leather, it was shaped into a cylindrical form, and there was no reduction in surface quality before or after the molding process. The results are shown in Tables 3 and 4.

[0284] [Table 3] [Table 4] [Comparative Example 1] In the <Process of Forming Widened Sheet>, as shown in Table 3, the 158cm wide nonwoven sheet was not widened but instead given a polymer elastomer. Otherwise, the process was the same as in Example 1 to obtain artificial leather.

[0285] Although the resulting artificial leather has a smooth feel, its surface has a high area ratio of polymer elastomers, lacking density and exhibiting uneven surface quality. Furthermore, the coefficient of variation of the area change rate in the molded artificial leather is large, indicating increased exposure of polymer elastomers on the surface and a decrease in quality. The results are shown in Tables 5 and 6.

[0286] [Comparative Example 2] In the <Process of Forming the Widened Sheet>, as shown in Table 3, the nonwoven sheet with a width of 158 cm was widened to 175 cm, that is, the width of the nonwoven sheet was widened by 11%. Otherwise, the process was the same as in Example 1 to obtain artificial leather. While the obtained artificial leather had a smooth feel, it lacked density and exhibited uneven surface quality. Furthermore, localized damage occurred during the molding process, making it impossible to evaluate the coefficient of variation of the area change rate of the artificial leather or the area ratio of the polymer elastomers on the surface of the artificial leather. The results are shown in Tables 5 and 6.

[0287] [Comparative Example 3] In the <Process of Forming Nonwoven Sheet>, a 158cm wide nonwoven sheet is treated with a vibrating washing machine. In water, water is allowed to flow through the interior of the nonwoven sheet to disperse the extremely fine fibers. In the <Process of Forming Widened Sheet>, as shown in Table 3, the 158cm wide nonwoven sheet is not widened but instead given a polymer elastomer. Otherwise, the process is the same as in Example 1 to obtain artificial leather.

[0288] Although the resulting artificial leather has a smooth feel, its surface has a high area ratio of polymer elastomers, lacking density and exhibiting uneven surface quality. Furthermore, the coefficient of variation of the area change rate in the molded artificial leather is large, indicating increased exposure of polymer elastomers on the surface and a decrease in quality. The results are shown in Tables 5 and 6.

[0289] [Table 5] [Table 6] As shown in Tables 1-4, in the process of forming the widened sheet, the nonwoven sheet to which PVA is applied in a specified ratio is widened within a specified range. After the adhesion between the ultrafine fibers and PVA is moderately eased, a polymer elastomer is applied, and the sheet is ground. This makes the area ratio of the polymer elastomer in the surface and cross-section of the artificial leather within a specific range, thereby achieving good formability that can follow complex shapes and a dense and smooth surface quality after molding.

[0290] On the other hand, as shown in Tables 5 and 6, in the case of the artificial leather of Comparative Example 1, if the aforementioned widening is not implemented in the process of forming the widened sheet, the area ratio of polymer elastomers in the surface and cross-section of the artificial leather is outside the specified range, and it is impossible to simultaneously achieve the ability to follow complex shapes and the dense and smooth surface quality after molding.

[0291] In addition, as with the artificial leather in Comparative Example 2, if the nonwoven sheet is widened by more than 10% during the process of forming the widened sheet, the area ratio of the polymer elastomer in the cross section of the artificial leather is outside the specified range, making it impossible to simultaneously achieve the ability to follow complex shapes and the dense and smooth surface quality after molding.

[0292] Furthermore, as with the artificial leather in Comparative Example 3, if the ultrafine fibers are dispersed using a vibrating washing machine during the process of forming the nonwoven sheet, and if the aforementioned widening is not performed during the process of forming the widened sheet, the area ratio of polymer elastomers in the surface and cross-section of the artificial leather is outside the specified range, making it impossible to simultaneously achieve the ability to follow complex shapes and the dense and smooth surface quality after molding.

[0293] The invention has been described in detail with reference to specific methods, but those skilled in the art will recognize that various changes and modifications can be made without departing from the spirit and scope of the invention. It should be noted that this application is based on Japanese Patent Application No. 2023-169362, filed on September 29, 2023, which is incorporated herein by reference in its entirety. Furthermore, all references cited herein are incorporated herein by reference in their entirety.

[0294] Explanation of reference numerals in the attached figures 1: Artificial leather 2: Pile head 3: Substrate section 4: The surface with the napped head 5: The surface opposite to the side with the pile head (bottom surface) L A Line parallel to the base L B :Bottom L0: Boundary line between the pile head and the substrate P1~P 10 Points on the boundary line between the pile head and the substrate. Q1~Q 10 The point where the perpendicular line intersects the end of the pile head. R1~R 10 The distance between a point on the boundary line between the pile head and the substrate and the point where the perpendicular line intersects with the end of the pile head. S1~S 10 The point where the perpendicular line intersects with the end of the substrate. T1~T 10 The distance between the point where the perpendicular line intersects the end of the pile head and the point where the perpendicular line intersects the end of the substrate.

Claims

1. Artificial leather, having a substrate portion and a napped head on at least one surface, The substrate portion comprises: a fiber complex comprising a nonwoven fabric formed from extremely fine fibers with an average single fiber diameter of 0.01 μm to 10.00 μm; and a polymer elastomer. The polymeric elastomer constitutes a mass percentage of more than 15% and less than 40% in the artificial leather. The area ratio of polymeric elastomer in the surface of at least one of the artificial leathers, on the side having the napped head, is more than 0.01% and less than 3.00%. The area ratio of polymer elastomer in the cross-section of the artificial leather is more than 5% and less than 15%.

2. The artificial leather as described in claim 1, wherein, The standard deviation of the area ratio of polymeric elastomer in the surface of at least one of the artificial leathers, on the side having the napped head, is less than 25%.

3. The artificial leather as described in claim 1 or 2, wherein, The standard deviation of the area ratio of polymeric elastomers in the cross-section of the artificial leather is less than 25%.

4. The artificial leather as described in claim 1 or 2, wherein, The thickness t of the substrate portion A The thickness is 250μm to 800μm, and the thickness t of the substrate portion is... A With the thickness t of the pile head B The ratio of t A / t B It is between 0.5 and 2.

5.

5. The artificial leather as described in claim 4, wherein, The thickness t of the substrate portion A The coefficient of variation is below 50%.

6. The artificial leather as described in claim 1 or 2, wherein, The ultrafine fibers contain black pigment.

7. A method for manufacturing artificial leather, the method comprising: A process of imparting polyvinyl alcohol (PVA) at a mass of 4% to 40% by mass relative to the mass of the PVA to a fiber complex comprising a nonwoven fabric mainly composed of ultrafine fiber visible fibers, thereby forming a sheet of PVA-impregnated material. The process of making extremely fine fibers with an average single fiber diameter of 0.01 μm to 10.00 μm appear from the extremely fine fiber-displaying fibers of the sheet imparted with polyvinyl alcohol to form a nonwoven sheet. The process of widening the nonwoven sheet by 2% to 10% is called widening the sheet. A process of applying a polymeric elastomer to the broadened sheet in an amount of 12% to 64% by mass relative to the mass of the broadened sheet, thereby forming a sheet with the polymeric elastomer applied. The process of removing the polyvinyl alcohol from the sheet with the polymer elastomer to form a matrix sheet; and A process of grinding at least one surface of the substrate sheet.

8. A method for manufacturing artificial leather, the method comprising: A process of imparting polyvinyl alcohol (PVA) at a mass of 4% to 40% by mass relative to the mass of the PVA to a fiber complex comprising a nonwoven fabric mainly composed of ultrafine fiber visible fibers, thereby forming a sheet of PVA-impregnated material. The process of widening the sheet by increasing the width of the polyvinyl alcohol-treated sheet by more than 2% and less than 10% is formed. The process of making extremely fine fibers with an average single fiber diameter of 0.01 μm to 10.00 μm appear from the extremely fine fiber manifestation type fibers of the broadened sheet to form a nonwoven sheet; A process of applying a polymeric elastomer to the nonwoven sheet in an amount of 12% to 64% by mass relative to the mass of the nonwoven sheet, thereby forming a sheet with the polymeric elastomer applied. The process of removing the polyvinyl alcohol from the sheet with the polymer elastomer to form a matrix sheet; and A process of grinding at least one surface of the substrate sheet.

9. The method for manufacturing artificial leather as described in claim 7 or 8, wherein, In the process of forming a sheet incorporating polyvinyl alcohol, polyethylene glycol is present in an amount of 0.01% to 0.5% by mass relative to the mass of the polyvinyl alcohol.

10. Interior material for a vehicle, comprising the artificial leather as described in claim 1 or 2.

11. A vehicle component comprising the artificial leather as described in claim 1 or 2.

12. Groceries comprising the artificial leather as described in claim 1 or 2.

13. Furniture comprising the artificial leather as described in claim 1 or 2.

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