Artificial leather, vehicle interior material, seat

Abstract

To provide an artificial leather that has high-quality appearance, and is thin, highly strong and capable of being easily formed along a shape.SOLUTION: An artificial leather contains, as main constituents, polyester fibers having average single fiber diameter of 2.0 μm or more and 7.0 μm or less and thermoplastic elastomer resin. The polyester fibers are long fibers and dispersed as single fibers. At least some of the polyester fibers are bonded by the thermoplastic elastomer resin.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to an artificial leather which is easy to produce, has a luxurious appearance, is thin, has high strength and can be easily formed into any shape, and to an interior material and a seat for a vehicle which use the artificial leather. [Background technology]

[0002] Artificial leather, the surface of which is covered with nap made of ultrafine fibers, has an elegant appearance and is therefore used in a wide range of fields, including clothing, furniture, and automobile interior materials. This type of artificial leather is made into a uniform sheet by laminating webs made of ultrafine fiber-generating staples in a cross-layer, achieving a high level of appearance and physical properties.

[0003] However, in recent years, there has been an increasing demand for higher levels of appearance and physical properties, and a growing trend toward environmental considerations has created a demand for process simplification.

[0004] For example, Patent Document 1 proposes an artificial leather characterized in that a long-fiber nonwoven fabric made of sea-island fibers having an island component of a thermoplastic polyester elastomer of 0.5 dtex or less and an island component of a water-soluble thermoplastic resin is entangled by needle punching, and then the fabric is impregnated with a water-based polyurethane and the sea component is removed.

[0005] In addition, an artificial leather has been proposed, which is characterized in that a wet-laid nonwoven fabric is produced using main fibers of 0.01 to 0.5 decitex and short fibers of a thermoplastic resin having a specific elasticity range, which are then entangled by hydroentangling or needle punching, and then heat-treated at a temperature equal to or higher than the melting point of the thermoplastic resin to bond the main fibers. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2014-25153 A [Patent Document 2] Patent Publication No. 2022-179201 Summary of the Invention [Problem to be solved by the invention]

[0007] If the technology disclosed in Patent Document 1 were used as a base material for artificial leather, it would be possible to omit the steps of cutting into staple fibers after crimping and of creating a web by carding and cross-wrapping, which are generally used in the manufacture of artificial leather, and therefore it is believed that the process could be simplified more easily than that of conventional artificial leathers using staple fibers. However, the technology disclosed in Patent Document 1 requires a step of removing the sea component to generate ultrafine fibers, and ultrafine fibers generated from the same sea-island fiber tend to gather together to form fiber bundles, making it difficult to obtain a sheet with a uniform appearance in which each fiber is dispersed separately. In addition, it is difficult to increase the line speed with needle punching, making it difficult to increase productivity.

[0008] In addition, when artificial leather is obtained by a process of making ultrafine fibers as disclosed in Patent Document 2, it is considered that the process can be simplified more easily than conventional artificial leathers in that the process of generating ultrafine fibers is unnecessary and the addition of polyurethane is unnecessary. On the other hand, in order to uniformly disperse the fibers in water, the fiber length needs to be short, making it difficult to obtain artificial leather with an elegant and luxurious appearance and high physical properties. In addition, the fibers need to be rigid so that they do not become entangled in water. Therefore, it is difficult to soften the touch of the nap.

[0009] Therefore, an object of the present invention is to provide an artificial leather which combines, at a high level, an elegant and luxurious appearance with mechanical properties which are thin, high strength, and easy to conform to a shape, and to provide a method for producing an artificial leather which can further reduce the environmental load while improving productivity. [Means for solving the problem]

[0010] In order to solve the above problems, the present invention has the following configuration.

[0011] [1] An artificial leather comprising, as main components, polyester-based fibers having an average single fiber diameter of 2.0 μm or more and 7.0 μm or less and a thermoplastic elastomer resin, wherein the polyester-based fibers are long fibers and dispersed as single fibers, and at least a portion of the polyester-based fibers are bonded with a thermoplastic elastomer resin.

[0012] [2] The artificial leather according to [1] above, characterized in that at least one surface has raised nap, and the number of fiber ends observed from a 200 μm square field of view on the surface having raised nap is 4 or more.

[0013] [3] The artificial leather according to [1] or [2] above, characterized in that at least one surface of the artificial leather is provided with a resin layer on at least a part of the surface.

[0014] [4] X-ray diffraction intensity I of the (-105) plane measured with wide-angle X-rays, calculated by the following formula (1): (-105) and the X-ray diffraction intensity I of the (100) plane (100) The artificial leather according to any one of the above [1] to [3], characterized in that the diffraction intensity ratio Z is 0.002 or more and 0.015 or less.

[0015] Z=I (-105) / I (100) (1) [5] The artificial leather according to any one of [1] to [4], wherein the thermoplastic elastomer has an elastic modulus of 15 MPa or more and 250 MPa or less as measured by an atomic force microscope.

[0016] [6] A vehicle interior material, characterized in that it is made using the artificial leather according to any one of [1] to [5] above.

[0017] [7] A seat, characterized by using the artificial leather described in any one of [1] to [5] above. Effect of the Invention

[0018] According to the present invention, it is possible to obtain an artificial leather which is highly productive, has an elegant and luxurious appearance, is thin, has high strength, and is easily molded to a shape. Due to the excellent properties of this artificial leather, it can be suitably used in particular for interior materials or seats for vehicles. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] The artificial leather of the present invention is an artificial leather containing polyester fibers having an average single fiber diameter of 2.0 μm to 7.0 μm and a thermoplastic elastomer resin as main components, the polyester fibers being long fibers dispersed as single fibers, and at least a part of the polyester fibers being bonded with a thermoplastic elastomer resin (hereinafter sometimes referred to as TPE). The components are described in detail below, but the present invention is not limited to the scope described below as long as it does not deviate from the gist of the present invention, and various modifications are possible within the scope of the present invention.

[0020] Here, in the present invention, "containing polyester-based fibers and thermoplastic elastomer resin as main components" means that the mass ratio of the fibers is 50 mass% or more in the part excluding the layer attached to the back surface of the artificial leather described below and polyurethane.

[0021] In the present invention, the term "long fiber" means a substantially continuous fiber having a fiber length of 100 mm or more, which is not a short fiber intentionally cut after spinning. More specifically, it means a fiber that is not a short fiber intentionally cut to a fiber length of about 3 mm to 80 mm. However, in the process of producing artificial leather, after the polyester resin and the thermoplastic elastomer resin are spun into a sheet, the fiber is cut in a portion, for example, the fiber at the end formed by slitting the sheet, or the fiber on the surface formed by nap formation on the surface of the sheet, and the like, even if the fiber is cut to a certain length, the fiber is considered to be a long fiber.

[0022] In the present invention, the term "dispersed as single fibers" refers to a state in which there are no fiber bundles on the surface in which many fibers are gathered together to form thick fibers. This state can be confirmed by observation with a stereomicroscope or electron microscope, and specifically, a randomly selected area of ​​1 cm x 1 cm is observed, and the number of fiber bundles in which 10 or more fibers are gathered together and continue for a length of 1 mm or more is counted. The number of fiber bundles is similarly counted in 10 areas, and if the average value is 3 or less, the fiber is determined to be "dispersed as single fibers."

[0023] [Polyester fiber] The artificial leather of the present invention contains, as main components, fibers made of polyester resin and a thermoplastic elastomer resin, and at least a part of the polyester fiber is bonded with the thermoplastic elastomer resin. By doing so, it is possible to obtain an artificial leather that has a luxurious appearance, is thin, has high strength, and is easy to conform to a shape.

[0024] Examples of the polyester resin include polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, polylactic acid, polyester elastomer, etc. Among these, from the viewpoint of the feel and practical performance of the processed product, polyethylene terephthalate and polybutylene terephthalate are more preferable, and polyethylene terephthalate is particularly preferably used.

[0025] In the present invention, the polyester resin refers to each polyester resin such as the above-mentioned polyethylene terephthalate, their mixtures, copolymers, and these resins to which additives have been added. The additives are added or contained in accordance with various purposes within a range that does not impair the purpose of the present invention, and specific examples of the additives include inorganic particles such as titanium oxide particles, lubricants, pigments, heat stabilizers, ultraviolet absorbers, conductive agents, heat storage agents, antibacterial agents, etc.

[0026] In the artificial leather of the present invention, the polyester-based fiber has an average single fiber diameter of 2.0 μm or more and 7.0 μm or less. This range provides a soft and smooth touch, stabilizes the shape of the nonwoven fabric, and improves handleability. By setting the lower limit of the range of the average single fiber diameter to 2.0 μm or more, preferably 2.5 μm or more, and more preferably 3.0 μm or more, the shape stability of the artificial leather is improved. On the other hand, by setting the upper limit of the range of the average single fiber diameter to 7.0 μm or less, preferably 6.0 μm or less, and more preferably 5.0 μm or less, the artificial leather becomes more flexible.

[0027] In the artificial leather of the present invention, the average single fiber diameter (μm) is determined as follows. (1) Cut out five test pieces measuring 2 cm x 2 cm. (2) The cross section of the test piece is photographed using a scanning electron microscope (for example, the "VHX-D510" model manufactured by Keyence Corporation). (3) Randomly select 20 circular or nearly circular elliptical fibers. (4) Measure the diameters of 20 single fibers. (5) (2) to (4) are carried out for all test pieces, and the arithmetic mean value (μm) of the obtained single fiber diameters is rounded off to two decimal places.

[0028] Furthermore, in the artificial leather of the present invention, the fibers are long fibers. This is because using long fibers not only makes it easier to obtain high strength, but also makes it difficult for the fibers to come off the artificial leather, resulting in good abrasion resistance.

[0029] In the artificial leather of the present invention, the fibers are dispersed as single fibers. Since the fibers constituting the artificial leather are dispersed separately, the artificial leather has a uniform structure as a whole, and an appearance with a high-class feel can be obtained.

[0030] In general, in artificial leather using ultrafine fiber-generating fibers, the ultrafine fibers are subjected to structure formation such as entanglement as ultrafine fiber-generating fibers, and the multiple ultrafine fibers that were in the ultrafine fiber-generating fibers during the ultrafine fiber generation process form fiber bundles. When such a structure is formed with fiber bundles, the size of the fiber bundles tends to form entangled parts and surfaces, making it difficult to easily obtain a uniform structure as expected in the present invention. Furthermore, in some cases, the direction of the hairs changes when stroked with a finger, the color appears to have changed, and lighting effects cannot be obtained, resulting in a product of inferior quality.

[0031] In addition, even if a structure in which fibers are entangled in a state of bundles is contained as part of the artificial leather due to manufacturing constraints, etc., this is permissible as long as the content ratio is within a range that does not impair the effects of the present invention. However, care should be taken because the effects of the present invention may not be fully obtained.

[0032] In the artificial leather of the present invention, the polyester fiber is preferably 50% by mass or more and 80% by mass or less in the weight ratio of the base material. By making the weight ratio of the polyester fiber 50% by mass or more, more preferably 60% by mass or more, and even more preferably 70% by mass or more, the nap density on the surface of the artificial leather can be improved and a lighting effect can be obtained. On the other hand, by making the weight ratio of the polyester fiber 80% by mass, a decrease in the elongation rate at low load can be prevented, and an artificial leather that is easy to mold according to the desired shape of the present invention can be obtained.

[0033] In the artificial leather of the present invention, the fiber preferably has a cross-sectional irregularity of 1.00 or more and 1.15 or less. When the irregularity is at the lower limit of 1.00, the cross-section of the fiber is a perfect circle, and as the irregularity increases, the cross-section of the fiber is deformed in a direction different from the perfect circle. By setting the upper limit of the irregularity range to preferably 1.15 or less, more preferably 1.10 or less, and even more preferably 1.05 or less, anisotropy is suppressed when the fiber is bent, so that when nap is formed on the surface of the artificial leather, the nap formed on the surface of the artificial leather is easily aligned, and an artificial leather full of luxury can be obtained.

[0034] In the artificial leather of the present invention, the irregularity is determined as follows. (1) Cut out five test pieces measuring 2 cm x 2 cm. When cutting test pieces from a product that uses artificial leather, take pieces at random from the product, excluding seams and embossed areas. (2) The cross section of the test piece is photographed using a scanning electron microscope (for example, the VHX-D510 model manufactured by Keyence Corporation). (3) Ten fibers are randomly selected, and in order to observe the exact shape of each fiber cross-section, images are taken by adjusting the direction so that the side surface of the fiber is not reflected at all or is minimally reflected. (4) For the cross section of the selected fiber, the diameter (μm) of the smallest circumscribing circle of the cross section is divided by the diameter (μm) of the largest inscribing circle of the cross section to determine the degree of irregularity (unitless) of the fiber. (5) (2) to (4) are carried out on all test pieces, and the obtained arithmetic mean value (unitless) of the irregularity is rounded off to the third decimal place.

[0035] [Thermoplastic elastomer resin] Examples of the thermoplastic elastomer resin include melt-spinnable polyurethane elastomers, polyester-based elastomers obtained by copolymerizing various aliphatic polyols with polybutylene terephthalate, polyamide-based elastomers obtained by copolymerizing various polyamides with various aliphatic polyols, polystyrene-based elastomers and olefin-based elastomers, etc. Among these, from the viewpoints of the feel, tensile strength and tensile elongation of the artificial leather, block copolymers having a hard segment of polybutylene terephthalate and a soft segment of polyether are preferably used.

[0036] Furthermore, depending on various purposes, inorganic particles such as titanium oxide particles, lubricants, pigments, heat stabilizers, ultraviolet absorbers, conductive agents, heat storage agents, antibacterial agents, etc. may be added to the thermoplastic elastomer resin within a range that does not impair the object of the present invention.

[0037] In the present invention, at least a part of the polyester-based fiber is bonded with a thermoplastic elastomer resin. Bonding with a thermoplastic elastomer resin means that at least a part of the surface of the polyester-based fiber is coated with a thermoplastic elastomer resin. By coating the polyester-based fiber with a thermoplastic elastomer resin, when it is made into artificial leather, high strength can be obtained even in a thin fabric, and a resilience feeling when gripped and appropriate stretch are exhibited, so that the sheet can be easily fitted to the shape of the interior material of the vehicle.

[0038] In the artificial leather of the present invention, whether the polyester fiber is covered with the thermoplastic elastomer resin or not is determined by the following measurement. (1) Cut out five test pieces measuring 2 cm x 2 cm. (2) The cross section of the test piece is photographed using a scanning electron microscope (for example, the "VHX-D510" model manufactured by Keyence Corporation). (3) Randomly select 20 circular or nearly circular elliptical fibers. (4) Of the 20 fibers, count the number of fibers that have resin directly attached to their surface. (5) (2) to (4) are carried out on all test pieces, and if resin is found to be adhering to the fiber surface in 65 or more of 100 pieces observed, it is deemed that at least a portion of the surface of the polyester-based fiber is bonded with a thermoplastic elastomer resin.

[0039] The greater the number of fibers with resin attached to their surfaces, the greater the strength and the improved rebound feel when gripped, so it is preferable that the number of fibers with resin attached to their surfaces be 75 or more out of 100, and more preferably 85 or more.

[0040] The thermoplastic resin has a melting point of 140° C. or higher so that the adhesive state does not change during dyeing, and from the viewpoint of facilitating temperature control when adhering to the polyester fiber, the melting point is preferably 20° C. or higher lower than that of the polyester fiber. Therefore, the melting point of the thermoplastic resin is preferably 140° C. or higher and 240° C. or lower, more preferably 150° C. or higher and 230° C. or lower, and even more preferably 160° C. or higher and 220° C. or lower.

[0041] The elastic modulus of the thermoplastic elastomer resin measured by an atomic force microscope is preferably 15 MPa or more and 250 MPa or less. If the elastic modulus of the thermoplastic elastomer resin measured by an atomic force microscope is preferably 15 MPa or more and 250 MPa or less, more preferably 15 MPa or more and 200 MPa or less, and even more preferably 15 MPa or more and 150 MPa or less, an artificial leather having a soft feel and resilience, and suitable stretch to conform to any shape can be obtained.

[0042] In the artificial leather of the present invention, the elastic modulus of the thermoplastic elastomer resin measured with an atomic force microscope is determined by the following measurement. (1) Measurement pretreatment The artificial leather is cut into a sheet sample with a width of 5 mm and a length of 10 mm. This sheet is then used with a cryomicrotome (Leica Ultracut-UCT) to create a precise cross section of the sample. (2) Force volume measurement The elastic modulus of a thermoplastic resin can be measured using the force volume mode of an atomic force microscope. The cantilever of the atomic force microscope is pressed against the cross section of a sample prepared using a cryomicrotome in a direction perpendicular to the sample and then released to obtain a force curve.

[0043] As the atomic force microscope, a probe microscope NanoScope V Dimension Icon (manufactured by Bruker Japan Co., Ltd.) is used, and as the probe, a RTESPA type silicon probe (manufactured by Bruker Japan Co., Ltd.) is used.

[0044] The probe is calibrated before the measurement. First, the cantilever's warpage sensitivity is measured on a sapphire plate. Next, the spring constant of the cantilever is measured by the thermal vibration method, and calibration is performed to enable quantification of the tip-sample distance and load, and AFM images of the sample cross section prepared by a cryomicrotome are measured. The cross section of the polyester fiber is observed as a fixed shape such as a circle or ellipse, while the thermoplastic resin component is observed as an indefinite shape, so the position of the thermoplastic resin is identified from the shape characteristics, and the elastic modulus is measured in a 5 μm square range including the thermoplastic elastomer resin. The elastic modulus is measured in three fields of view in the same manner, and the average value of the obtained elastic modulus is rounded off to the first decimal place to determine the elastic modulus of the thermoplastic elastomer resin.

[0045] In the artificial leather of the present invention, it is also preferable to use a side-by-side type conjugate fiber in which a polyester fiber and a thermoplastic elastomer resin are bonded together, and the fiber has crimping properties. When such a fiber having crimping properties is used, the elongation is improved, and the sheet can be easily fitted to the shape of the interior material of the vehicle.

[0046] [Artificial leather] In a first preferred embodiment, the artificial leather of the present invention has nap on at least one surface, and the number of fiber ends observed from a 200 μm square field of view on the nap-covered surface is preferably 4 or more. In the present invention, a "napped" surface refers to a surface having a nap-covered layer of ultrafine fibers with length and directional flexibility to the extent that a so-called writing effect is produced by tracing the surface with a finger. The more fiber ends present on the surface, the more naps there are. The number of fiber ends observed from a 200 μm square field of nap is preferably 4 or more, more preferably 7 or more, and even more preferably 10 or more, so that the artificial leather can be used as an artificial leather with an elegant appearance with a suede or nubuck texture.

[0047] In the artificial leather of the present invention, the number of fiber ends observed in a 200 μm square field of view is determined by the following measurement. (1) Cut out five test pieces measuring 2 cm x 2 cm. (2) The cross section of the test piece is photographed at three locations at a magnification of 500 times using a scanning electron microscope (for example, the "VHX-D510" model manufactured by Keyence Corporation). (3) A 200 μm square field of view is randomly selected from the captured image, and the number of fiber ends is counted. (4) Calculate the arithmetic mean (number) of fiber ends obtained from all captured images and round off to the first decimal place.

[0048] In addition, as a second preferred embodiment, the artificial leather of the present invention is preferably provided with a resin layer on at least one surface of the artificial leather. The resin layer is not particularly limited, but it is also preferable to provide a resin layer made of a polymeric elastomer such as polyurethane and having a pattern such as a grain similar to natural leather on the surface of the artificial leather to make a so-called grain-finished artificial leather. The resin layer formed on the surface has a uniform and high-quality appearance, but if the base material is deformed and wrinkled when molded into a seat shape or when sitting on it, the surface appearance will be impaired. In the present invention, at least a part of the polyester-based fiber is bonded with a thermoplastic elastomer resin, so that the base material is less likely to wrinkle when deformed, and a high-quality surface appearance can be maintained.

[0049] The polyurethane resin that can be used in the present invention is not particularly limited, and examples of the polyurethane resin include polyether polyurethane resin, polyester polyurethane resin, polycarbonate polyurethane resin, acrylic polyurethane resin, etc., which can be used alone or in combination of two or more. The polyurethane resin may be any of a solventless type, a hot melt type, a solvent type, or a water type, and may be any of a one-component type or a two-component curing type.

[0050] Examples of methods for forming a resin layer on the surface of artificial leather using a polymeric elastomer such as polyurethane include a method of applying a resin liquid containing a polymeric elastomer to the surface of artificial leather and curing it, and a method of forming a resin layer containing a polymeric elastomer on a support substrate such as release paper, applying an adhesive to the surface of the resin layer, and bonding it to the surface of the artificial leather. The thickness of the resin layer is not particularly limited, but is preferably 30 μm to 200 μm because it tends to easily achieve both the texture and abrasion resistance of the artificial leather, more preferably 30 μm to 180 μm, and even more preferably 50 μm to 150 μm.

[0051] In the present invention, the thickness of the resin layer is calculated by taking a scanning electron microscope (SEM) photograph of the cross section of the artificial leather, measuring the thickness of the resin layer at 10 random locations, calculating the arithmetic average value (μm), and rounding off to the first decimal place.

[0052] Here, an embodiment in which the first preferred embodiment and the second preferred embodiment are simultaneously implemented is also preferred. Specifically, a so-called semi-silver-tone artificial leather, that is, an artificial leather in which a resin layer is provided discretely on a surface having nap, is exemplified. Here, "discretely provided with a resin layer" refers to a form in which the resin layer is arranged in a lattice shape, a staggered shape, a twill weave shape, a satin weave shape, a random shape, or the like, as described below. In addition, as the shape of the resin layer, various shapes can be used depending on the application, such as a circle, a star shape, a heart shape, or a polygonal shape such as a triangle, a square, a hexagon, or an octagon. Of course, in the present invention, the arrangement form and shape when the resin layer is provided discretely are not particularly limited. In addition, as a method for providing a resin layer discretely, a method of applying a polymer elastomer such as polyurethane in a desired pattern to the surface of the artificial leather and curing it, a method of forming a resin layer on a support substrate such as release paper, applying an adhesive to the surface of the resin layer, and bonding it to the surface of the artificial leather, etc. can be mentioned.

[0053] Generally, when manufacturing the base material of artificial leather, the fibers are oriented in the thickness direction of the base material by such methods as needle punching and high-pressure water jet treatment, but the more the orientation in the thickness direction is increased by these methods, the lower the production speed, the more energy is consumed, and the greater the environmental impact. On the other hand, by arranging the fibers more in the planar direction than in the thickness direction, the tensile strength is higher even with the same basis weight, so it is possible to produce a thin and strong artificial leather.

[0054] Therefore, in the artificial leather of the present invention, the X-ray diffraction intensity I of the (-105) plane measured with wide-angle X-rays is calculated by the following formula (1). (-105) and the X-ray intensity of the (100) plane I (100) It is preferable that the diffraction intensity ratio Z is 0.002 or more and 0.015 or less. Z=I (-105) / I (100) (1) Here, the X-ray diffraction intensity I (-105) means the fiber orientation ratio in the thickness direction, and the X-ray diffraction intensity I (100) means the fiber orientation ratio in the planar direction.

[0055] By setting the lower limit of the diffraction intensity ratio Z to 0.002 or more, preferably 0.004 or more, more preferably 0.005 or more, the morphology stability of the substrate is improved and the processability is high. On the other hand, by setting the upper limit of the diffraction intensity ratio Z to 0.015 or less, preferably 0.012 or less, more preferably 0.010 or less, the tensile strength is higher.

[0056] In the artificial leather of the present invention, the X-ray diffraction intensity I (-105) X-ray diffraction intensity of the (100) plane I (100) The diffraction intensity ratio Z is calculated by the following measurement. (1) Cut out a test piece measuring 1.5 cm x 1.5 cm and place it on a silicon anti-reflection plate. (2) Use CuKα radiation as the X-ray source, and perform 2θ-θ continuous scanning (2θ = 5° to 60°, step width 0.01711°, scan speed 0.5 s / step) with an output of 40 kV, 40 mA, and a slit system DS = 0.3°. (3) Calculate the crystal size L from the diffraction peak using the following formula: Crystallite size L [nm] = Kλ / ((β e 2 -β0 2 ) 1 / 2 ×COSθ) λ: X-ray wavelength (0.15418nm), β e : half-width of diffraction peak, β0: half-width correction value (0.13°), K: Scherrer constant (0.9). (4) X-ray diffraction intensity of the (-105) plane obtained from the diffraction peak I (-105) , X-ray diffraction intensity of (100) plane I (100) Calculate the diffraction intensity ratio Z from the following formula (1) and round off to the fourth decimal place. Diffraction intensity ratio Z=I (-105) / I (100) ···(1).

[0057] In addition, since the artificial leather of the present invention is composed of long fibers, it is characterized by relatively high strength characteristics. In order to obtain even higher strength characteristics, it is also preferable to make the artificial leather further include, as a component, a layer made of reinforcing fibers having an average single fiber diameter of 5.0 μm or more and 25.0 μm or less.

[0058] In the present invention, the average single fiber diameter of the reinforcing fibers is calculated by taking a scanning electron microscope (SEM) photograph of the cross section of the artificial leather, randomly selecting 10 reinforcing fibers that compose the layer made of reinforcing fibers, measuring the single fiber diameter of the fibers, calculating the arithmetic average value (μm) of the 10 fibers, and rounding off to the first decimal place. However, when a fiber with a modified cross section is used, the cross-sectional area (μm) of the fiber is first calculated in the same manner as in the case of measuring and calculating the average single fiber diameter of the fibers that compose the artificial leather. 2 ) is measured, and the diameter when the cross section is regarded as a circle, that is, the equivalent circle diameter is calculated to obtain the fiber diameter (μm). In addition, when the reinforcing fiber is a multifilament as described below, the diameter of the single fiber constituting the multifilament is regarded as the average single fiber diameter of the reinforcing fiber.

[0059] In order to adjust the texture and physical properties of the artificial leather of the present invention, it is also preferable to make the artificial leather further contain polyurethane as a constituent element. As the polyurethane, a polyurethane obtained by reacting a polymer diol, an organic diisocyanate, and a chain extender is preferably used.

[0060] The polymer diol used in the polyurethane according to the present invention can be at least one type of polymer diol selected from polymer diols such as polyester diols, polyether diols, polycarbonate diols, and polyester polyether diols, each having an average molecular weight of 500 or more and 3,000 or less. It is preferable that the polyurethane contains a polyether diol or polycarbonate diol that has excellent hydrolysis resistance and is less likely to lose its function as a binder after repeated washing.

[0061] In addition, the polyurethane according to the present invention may contain various additives depending on the purpose, for example, pigments such as carbon black; phosphorus-based, halogen-based and inorganic flame retardants; phenol-based, sulfur-based and phosphorus-based antioxidants; benzotriazole-based, benzophenone-based, salicylate-based, cyanoacrylate-based and oxalic acid anilide-based ultraviolet absorbers; hindered amine-based and benzoate-based light stabilizers; hydrolysis-resistant stabilizers such as polycarbodiimide; plasticizers, antistatic agents, surfactants, coagulation adjusters and dyes.

[0062] In general, the content of polyurethane in artificial leather can be appropriately adjusted taking into consideration the type of polyurethane used, the method for producing polyurethane, and the desired texture and physical properties of the artificial leather, but in the artificial leather of the present invention, the content of polyurethane is preferably 5% by mass or more and 20% by mass or less. By setting the lower limit of the range of the content of polyurethane to 5% by mass or more, more preferably 8% by mass or more, the abrasion resistance of the artificial leather can be improved. On the other hand, by setting the upper limit of the range of the content of polyurethane to 20% by mass or less, more preferably 15% by mass or less, and even more preferably 12% by mass or less, the artificial leather can be made more flexible.

[0063] In the present invention, the content of polyurethane in the artificial leather refers to a value measured and calculated by the following method. (1) Five test pieces measuring 2 cm x 2 cm are cut out and the mass of each test piece is measured. When cutting test pieces from a product that uses artificial leather, they are taken randomly from the product, excluding seams and embossed areas, and are used after adjusting to standard conditions of 20±2°C temperature and 65±4% relative humidity. (2) The artificial leather is immersed in a solvent that dissolves ultrafine fibers and reinforcing fibers, or in a solvent that dissolves polyurethane, and the polyurethane content (g) is calculated from the change in mass before and after dissolution. For example, in the case of artificial leather that contains organic solvent-based polyurethane, the artificial leather is often immersed in N,N'-dimethylformamide to dissolve and remove the polyurethane, and then the polyurethane content (g) is calculated by measuring the mass of the remaining ultrafine fibers and reinforcing fibers. (3) The polyurethane content obtained in (2) is divided by the mass (g) of the test piece obtained in (1) to calculate the polyurethane content (mass%). (4) (2) to (3) are carried out for all test pieces, the arithmetic mean value (mass%) of the obtained polyurethane content (mass%) is calculated, and the value is rounded off to the first decimal place.

[0064] [Manufacturing method of artificial leather] The method for producing an artificial leather of the present invention preferably includes the steps of melting a molten polyester resin and a molten thermoplastic elastomer resin in separate extruders, extruding them from separate nozzles arranged in a die at a single-hole throughput rate of 0.05 g / min or more and 0.30 g / min or less, blowing a gas at a temperature of -15°C or more and 50°C or less onto the melted polyester resin and the thermoplastic elastomer resin so as to form yarns, the gas being -15°C or more and 50°C or less so as to include at least a part of a region within 200 mm from the nozzles, and drawing the yarns with a gas at a temperature of -15°C or more and 50°C or less at least at an inlet so as to give a spinning speed of 3,000 m / min or more and 7,000 m / min or less, to obtain a mixed fiber web composed of polyester fibers and thermoplastic elastomer resin fibers having an average single fiber diameter of 2.0 μm or more and 7.0 μm or less.

[0065] In another embodiment, the method includes the steps of melting a polyester resin and a thermoplastic elastomer resin having different viscosities or shrinkage rates in separate extruders, joining the resins in a die so that the resins can be discharged from the same nozzle in a side-by-side bonded form at a single-hole discharge rate of 0.025 g / min to 0.15 g / min, discharging the polymers, and then blowing a gas at a temperature of -15°C to 50°C onto the polymer so as to include at least a portion of a region within 200 mm from the nozzle to form threads, and drawing the threads with a gas at a temperature of -15°C to 50°C at least at an inlet so that the spinning speed is 3,000 m / min to 7,000 m / min to obtain a web composed of side-by-side conjugate fibers of a polyester fiber and a thermoplastic elastomer resin having an average single fiber diameter of 2.0 μm to 7.0 μm.

[0066] Here, in the present invention, the "inlet" refers to the location where the wind speed of the pulling gas is the highest from the discharge hole to the web, and generally refers to the location where the cross-sectional area of ​​the passage through which the resin discharged from the discharge hole passes as threads is the smallest from the discharge hole to the web. Hereinafter, the details of this manufacturing method will be described. Of course, even in this respect, the present invention is not limited in any way to the scope described below as long as it does not deviate from the gist of the present invention, and it goes without saying that various modifications are possible without departing from the gist of the present invention.

[0067] First, in the method for producing an artificial leather of the present invention, it is preferable to extrude each of the molten polyester resin and the thermoplastic elastomer resin from different nozzles of the die at a single-hole throughput of 0.05 g / min to 0.30 g / min. In the present invention, the single-hole throughput (g / min) refers to the amount of resin (g) extruded from one nozzle (single hole) of the die per unit time (min). By setting the lower limit of the single-hole throughput range to preferably 0.05 g / min or more, more preferably 0.07 g / min or more, and even more preferably 0.09 g / min or more, stable spinnability can be obtained within the spinning speed range described below. On the other hand, by setting the upper limit of the single-hole throughput range to preferably 0.30 g / min or less, more preferably 0.25 g / min or less, and even more preferably 0.20 g / min or less, it is possible to easily obtain fibers having an average single fiber diameter of 7.0 μm or less, which can provide artificial leather with an elegant appearance within the spinning speed range described below.

[0068] At this time, the hole diameter of the discharge hole is preferably 0.05 mm or more and 0.30 mm or less. By setting the lower limit of the hole diameter range to preferably 0.05 mm or more, more preferably 0.07 mm or more, and even more preferably 0.09 mm or more, it is possible to suppress the deterioration of spinnability over time due to the adhesion of dirt, etc. On the other hand, by setting the upper limit of the hole diameter range to preferably 0.30 mm or less, more preferably 0.25 mm or less, and even more preferably 0.20 mm or less, it is possible to easily obtain a stable spinning state. In the present invention, when the discharge hole is not a perfect circle, the diameter of a perfect circle (circle equivalent diameter) with the same hole area is referred to as the hole diameter.

[0069] The ratio of the number of the discharge holes of the polyester resin and the thermoplastic elastomer resin may be different, but it is preferable that the ratio of the number of the discharge holes of the polyester resin as the main fiber is the same or more. By setting the ratio of the number of the discharge holes of the polyester resin / the number of the discharge holes of the thermoplastic elastomer resin to be preferably 50 / 50 or more and 80 / 20 or less, more preferably 55 / 45 to 75 / 35, and further preferably 60 / 40 to 70 / 30, an artificial leather with an elegant appearance and a good touch can be obtained.

[0070] In the method for producing an artificial leather of the present invention, it is preferable that after the molten polyester resin and thermoplastic elastomer resin are discharged from the discharge hole of the spinneret, a gas having a temperature of -15°C or higher and 50°C or lower is blown onto the melted polyester resin and the melted thermoplastic elastomer resin so as to include at least a part of the region within 200 mm from the discharge hole to form yarn. Generally, it is common to avoid blowing gas close to the discharge hole because this tends to affect the temperature of the discharge hole and destabilize the spinning. However, as a result of studies by the present inventors, it has been found that in spinning to obtain ultrafine fibers, the spinning can be stabilized by blowing gas close to the discharge hole.

[0071] By setting the lower limit of the temperature range of the gas to preferably -15°C or higher, more preferably -10°C or higher, and even more preferably -5°C or higher, it is possible to prevent the temperature in the vicinity of the discharge hole from being excessively lowered. On the other hand, by setting the upper limit of the temperature range of the gas to preferably 50°C or lower, more preferably 40°C or lower, and even more preferably 30°C or lower, it is possible to sufficiently cool the discharged polyester resin and thermoplastic elastomer resin.

[0072] The region onto which the gas is blown preferably includes at least a part of the region within 200 mm from the discharge hole, more preferably includes at least a part of the region within 150 mm from the discharge hole, and even more preferably includes at least a part of the region within 100 mm from the discharge hole. By doing so, it becomes easier to obtain fibers of 7.0 μm or less, which are usually difficult to obtain, and an artificial leather with an elegant appearance can be obtained.

[0073] The gas supply means used for blowing the gas may be a method of supplying gas from one or more directions of the polyester resin and the thermoplastic elastomer resin through a slit nozzle or a flow straightening unit using a blower.

[0074] In the method for producing an artificial leather of the present invention, the distance between the discharge hole and the inlet is preferably 100 mm or more and 3,000 mm or less. By setting the lower limit of the range of the distance between the discharge hole and the inlet to preferably 100 mm or more, more preferably 200 mm or more, and even more preferably 300 mm or more, fiberization of the molten polyester resin and thermoplastic elastomer resin can be sufficiently promoted, and stable spinning can be more easily performed. On the other hand, by setting the upper limit of the range of the distance between the discharge hole and the inlet to preferably 3,000 mm or less, more preferably 2,000 mm or less, and even more preferably 1,000 mm or less, the yarn made of the polyester resin and thermoplastic elastomer resin discharged from the multiple discharge holes can be stably introduced to the inlet.

[0075] Furthermore, in the method for producing an artificial leather of the present invention, it is preferable that the yarn is spun at a spinning speed Vs (m / min) of 3,000 m / min or more and 7,000 m / min or less at least at the inlet. By setting the lower limit of the spinning speed Vs (m / min) to preferably 3,000 m / min or more, more preferably 3,500 m / min or more, and even more preferably 4,000 m / min or more, the molecular orientation of the polyester resin fiber is sufficient, resulting in a moderately stiff touch, and an artificial leather having excellent mechanical properties and shape stability can be obtained. On the other hand, by setting the upper limit of the spinning speed Vs (m / min) to preferably 7,000 m / min or less, more preferably 6,500 m / min or less, and even more preferably 6,000 m / min or less, the yarn to which the gas is blown can be pulled more stably.

[0076] In the present invention, the spinning speed Vs (m / min) at the inlet refers to a value measured and calculated by the following method. (1) After the yarn is pulled and stretched, 10 small samples are randomly taken from the web collected on a net, and surface photographs are taken at 500 to 1,000 times magnification using a microscope. The widths of 10 fibers made of polyester resin from each sample are measured, for a total of 100 fibers, and the single fiber diameter (μm) is calculated from the arithmetic average value. (2) The single fiber fineness (dtex) is calculated from the single fiber diameter and the density of the resin used at 20°C by rounding off to one decimal place to obtain the mass per 10,000 m of length. (3) Calculate the spinning speed based on the single fiber fineness (dtex) in (2) and the single hole output rate (g / min) set under each condition based on the following formula, and round off to the first decimal place. Spinning speed (m / min) = (10,000 × single hole output (g / min)) / single fiber fineness (dtex).

[0077] Furthermore, the yarn can be uniformly cooled by setting the lower limit of the temperature range of the gas used when pulling the yarn to preferably -15°C or higher, more preferably -10°C or higher, and even more preferably -5°C or higher. On the other hand, the yarn can be sufficiently cooled by setting the upper limit of the gas temperature range to preferably 50°C or lower, more preferably 40°C or lower, and even more preferably 30°C or lower.

[0078] Furthermore, in the method for producing artificial leather of the present invention, the ratio Vq / Vs of the flow velocity Vq (m / min) of the gas when blowing the gas to the spinning speed Vs (m / min) is 3×10 -3 More than 30×10 -3 The lower limit of the Vq / Vs range is preferably 3×10-3 or more, and more preferably 4×10 -3 More preferably, 5×10 -3 By setting the Vq / Vs ratio at 30×10 or more, the yarn can be cooled sufficiently. -3 Less than or equal to 20×10 -3 Less than 10×10, more preferably -3 By setting the above, the yarn can be pulled more stably.

[0079] By the above-mentioned method, a web made of fibers having an average single fiber diameter of 2.0 μm or more and 7.0 μm or less can be obtained. Furthermore, in the method for producing the artificial leather of the present invention, it is preferable to produce the artificial leather by carrying out at least one of the following steps, for example. (1) A step of obtaining a sheet substrate by entangling the fibers of the web. (2) A step of subjecting the web or sheet substrate to a dry heat treatment at a temperature below the melting point of the polyester fiber and above the melting point of the thermoplastic elastomer resin to obtain a heat-treated sheet substrate in which at least a portion of the polyester fiber is bonded with the thermoplastic elastomer resin. (3) A step of applying polyurethane to the heat-treated sheet substrate to obtain a polyurethane-coated sheet substrate. (4) A step of subjecting at least one surface of either the heat-treated sheet substrate or the polyurethane-attached sheet substrate to a nap-raising treatment to form naps on the surface, thereby forming a napped sheet. (5) A step of providing a resin layer made of polyurethane on at least a portion of at least one surface of the heat treatment sheet substrate, the polyurethane-coated sheet substrate, or the napped sheet to form a resin layer-formed sheet. (6) A step of performing post-processing on either the napped sheet or the resin layer-formed sheet.

[0080] When steps (2) and (4) or steps (2) to (4) are carried out, the raised nap sheet becomes artificial leather. When steps (2) and (5) or steps (2) to (3) and (5) or steps (2) to (5) are carried out, the resin layer-formed sheet becomes artificial leather. Needless to say, the product obtained through step (6) also becomes artificial leather. Details of each step are described below.

[0081] First, in the process of obtaining the sheet substrate, a single layer of web or multiple layers are laminated to a desired basis weight, and then needle punching or water jet punching can be carried out to entangle the fibers.

[0082] Next, in the process of obtaining the heat-treated sheet substrate, the dry heat treatment means may be a method of pressing the web in multiple stages with a plurality of flat rolls having different temperatures, or of blowing hot air having a temperature below the melting point of the polyester fiber and above the melting point of the thermoplastic elastomer resin before or after pressing with the flat rolls.

[0083] Next, in the step of obtaining the sheet substrate with polyurethane, a method (solvent method) of dissolving polyurethane or its precursor in a solvent such as N,N'-dimethylformamide or dimethylsulfoxide is preferably used, but a method (water dispersion method) of using a water-dispersed polyurethane liquid in which polyurethane or its precursor, that is, a mixture containing at least a polymer diol, an organic diisocyanate, and a chain extender, is dispersed as an emulsion in water is also preferably used. In the case of the former solvent method, for example, a method of immersing the heat-treatment sheet substrate in the polyurethane solution and then drying to substantially coagulate and solidify the polyurethane precursor, or a method of immersing the heat-treatment sheet substrate in the polyurethane solution and then immersing it in another solvent in which polyurethane is insoluble to coagulate it can be used. On the other hand, in the case of the latter water dispersion method, for example, the heat-treatment sheet substrate can be immersed in the water-dispersed polyurethane liquid and then coagulated by a dry coagulation method in which the heat-treatment sheet substrate is immersed in the water-dispersed polyurethane liquid and then dried. In drying, the heat treatment sheet substrate or the polyurethane-coated sheet substrate can be heated at a temperature that does not impair the performance of the substrate.

[0084] In the step of forming the nap sheet, the nap raising treatment performed on at least one surface of the heat treatment sheet substrate can be performed using sandpaper or a roll sander. Among them, sandpaper can be used to form uniform and dense nap. In particular, in order to form uniform nap on the surface of the web, it is preferable to reduce the grinding load in the nap raising treatment. As a specific means for reducing the grinding load, for example, a multi-stage buffing with three or more buff stages is used, and the grit size of the sandpaper used in each stage is in the range of 120 (P120) to 600 (P600) as specified in JIS R 6010:2000 "Grain size of abrasives for coated abrasives".

[0085] In the process of producing a resin layer-forming sheet, a pigmented one-component polyurethane resin is coated onto embossed release paper, which is then dried in an oven, and then a two-component polyurethane resin is coated as an adhesive and dried again in an oven to form a resin layer, which is then laminated to the heat-treatment sheet substrate or the like, and the release paper is peeled off after the reaction is completed. Alternatively, a polyurethane dissolved in a solvent such as N,N'-dimethylformamide or dimethyl sulfoxide is directly coated onto the surface of the heat-treatment sheet substrate or the like, which is then immersed in another solvent in which polyurethane is insoluble to coagulate, followed by washing with water, drying, and then laminating the resin layer formed on the release paper described above.

[0086] Finally, in the post-processing step, functional agents such as dyes, pigments, softeners, anti-pilling agents, antibacterial agents, deodorants, water repellents, light resistance agents, and weather resistance agents can be added to the web or the like.

[0087] For example, the heat treatment sheet substrate can be dyed. The specific means for dyeing is not particularly limited, but a liquid flow dyeing machine is preferably used as in the case of conventional dyeing of artificial leather, since the heat treatment sheet substrate can be dyed and softened by applying a kneading effect at the same time. In order to dye polyester fibers, the temperature of the dyeing solution during dyeing is preferably 100°C or higher and 150°C or lower. As the dye, acid dyes, metal-containing dyes, reactive dyes, etc. are preferably used. Reduction washing can also be performed after dyeing.

[0088] In order to improve the uniformity of the dyeing, it is also preferable to use a dyeing assistant when dyeing. Furthermore, finishing treatments such as softeners such as silicone, antistatic agents, water repellents, flame retardants, and light fasteners can be performed. This finishing treatment can be performed after dyeing or in the same bath as dyeing.

[0089] Alternatively, various post-processing steps such as perforation, embossing, stitching, foiling, resin printing, inkjet printing, laser etching, and laminating knits, woven fabrics, films, polyurethane foam, etc. to the backside of the base material to improve strength and one-piece moldability can also be performed.

[0090] [Vehicle interior materials, seats] The artificial leather of the present invention is thin, has high strength, and is easily conformable to various shapes, and therefore has high strength and excellent shape stability, and is therefore suitable for a wide range of applications, including industrial materials such as clothing, miscellaneous goods, shoe and bag applications, vehicle interior materials, seats, CD curtains, DVD curtains, substrates for polishing pads, various polishing cloths, and wiping cloths.

[0091] Among them, vehicle interior materials using the artificial leather are preferred because they can take advantage of the characteristics of an elegant and luxurious appearance, a thin fabric, high strength, and easy conformability to shapes. As such vehicle interior materials, for example, at least a part of steering wheels, horn switches, shift knobs, dashboards, instrument panels, glove boxes, floor carpets, floor mats, ceiling linings, sun visors, assist grips, etc. of automobiles is more preferably made of the artificial leather. In addition, the term "vehicle" in the present invention includes automobiles, aircraft, railway vehicles, ships, carriages, cages, rickshaws, and other vehicles, as well as some industrial, construction, and agricultural machines that can carry humans or animals, such as excavators, cranes, tractors, and combines.

[0092] Alternatively, seats made of the above-mentioned artificial leather are also preferred because they can take advantage of the characteristics of a particularly elegant and luxurious appearance, a thin material, high strength, and ease of conforming to a shape. For such seats, it is more preferred that at least a part of the covering material of the headrest, seat surface, armrest, footrest, etc., for example, the part that comes into direct contact with the seated person, is made of the above-mentioned artificial leather. Of course, the seat of the present invention can be used not only for vehicles such as automobiles, aircraft, railway vehicles, and ships, but also for homes, offices, and stores. Note that the "seat" referred to in the present invention also includes chairs, benches, sofas, couches, stools, and chairs. EXAMPLES

[0093] Next, the present invention will be specifically described based on examples. However, the present invention is not limited to these examples. In addition, in the measurement of each physical property, unless otherwise specified, the measurement was performed based on the above-mentioned method.

[0094] [Measurement method] (1) Average single fiber diameter of polyester fibers (μm) The average fiber diameter (μm) of the polyester fibers contained as the main component of the artificial leather was measured and calculated using a scanning electron microscope (VHX-D510 model, manufactured by Keyence Corporation) according to the above-mentioned method.

[0095] (2) Dispersion of fibers in artificial leather To evaluate whether the fibers in the artificial leather were dispersed as single fibers, a 1 cm x 1 cm area was randomly selected on the surface of the artificial leather, and the area was evaluated using the scanning electron microscope "VHX-D510" and the method described above.

[0096] (3) Degree of irregularity of the cross section of polyester fiber (no unit) The degree of deformation of the polyester fiber contained as a main component of the artificial leather was measured and calculated by the above-mentioned method using the above-mentioned scanning electron microscope "VHX-D510 type."

[0097] (4) Polyester fiber coated with thermoplastic elastomer resin The state of coating of the polyester fiber, which is a main component of the artificial leather, with the thermoplastic elastomer resin was evaluated using the above-mentioned scanning electron microscope "VHX-D510" by the above-mentioned method.

[0098] (5) Elastic modulus of thermoplastic elastomer resin The elastic modulus of the thermoplastic elastomer resin contained as a main component of the artificial leather was evaluated by the above-mentioned method using an atomic force microscope, "NanoScope V Dimension Icon" manufactured by Bruker Japan Ltd.

[0099] (6) Diffraction intensity ratio Z The diffraction intensity ratio Z of the artificial leather was measured and calculated by the above-mentioned method using a "D8ADVANCE" X-ray diffractometer manufactured by Bruker Japan Ltd.

[0100] (7) Determination of surface hairiness The nap on the surface of the artificial leather was evaluated using the above-mentioned scanning electron microscope "VHX-D510" according to the above-mentioned method.

[0101] (8) Identification of the resin layer on the surface The resin layer on the surface of the artificial leather was evaluated using the above-mentioned scanning electron microscope "VHX-D510" by the above-mentioned method.

[0102] (9) Weight, thickness The basis weight was measured according to the method described in JIS L 1096 8.3.2 (2020). The thickness was measured using a dial thickness gauge (manufactured by Ozaki Seisakusho Co., Ltd., product name "Peacock H").

[0103] (10) Appearance evaluation For the artificial leather with raised nap on the surface, a 10 cm x 10 cm cut artificial leather sample was placed with the raised nap side facing up, and the lighting effect, in which the direction of the hair changes and the color appears to change when the five panelists stroked the surface with their fingers, and the degree of suppleness when the surface was stroked with their fingers were evaluated on the following five-level scale, and the average score was calculated to the first decimal place to determine the evaluation score. Next, the sum of the evaluation score for the lighting effect and the evaluation score for the suppleness was determined as the appearance evaluation score of the artificial leather, and a score of 6.0 or more was determined as a pass. The appearance evaluation of the artificial leather is preferably 7.0 points or more, more preferably 8.0 points or more. [Evaluation of lighting effects] 5 points: Finger marks are clearly visible 4 points: Finger marks are visible (between 3 and 5 points) 3 points: Finger marks are slightly faint but visible 2 points: Finger marks are not visible unless you pay attention (between 1 and 3 points) 1 point: No visible finger marks [Evaluation of flexibility] 5 points: Moist and comfortable texture 4 points: Smooth to the touch (between 3 and 5 points) 3 points: smooth texture 2 points: Slightly rough texture (between 1 and 3 points) 1 point: Feels rough For the artificial leather having a resin layer formed on at least a part of the surface, a 10 cm x 10 cm cut artificial leather sample was placed with the napped surface facing up and folded in half. A 6 cm x 6 cm flat plate was placed on the entire surface of the folded sample, and a load was applied so that the total weight of the flat plate and the weight was 4 kg. After applying the load for 30 seconds, the flat plate and the weight were removed, and after 10 seconds, five panelists evaluated the state of wrinkles in the bent part according to the following five-level criteria, and the average score was calculated to the first decimal place and used as the evaluation score. Next, the average score judged by each panelist was used as the evaluation score, and 2.6 points or more was considered to be a pass. The evaluation score is preferably 3.0 points or more, more preferably 3.6 points or more. [Folded crease condition] 4 points: No visible wrinkles in bent areas 3 points: Wrinkles are visible when you look closely at the bent part. 2 points: Slight marks are visible on the bent parts 1 point: Deep wrinkles are visible in the bent area.

[0104] (11) Elongation at a load of 5N / cm, breaking strength per unit area As an index of the formability of artificial leather, the elongation was measured in the MD direction at a load of 5 N / cm with a test piece width of 25 mm, grip interval of 100 mm, and a tensile speed of 100 mm / min in accordance with JIS L 1096 8.14.1 (2020) "Tensile strength and elongation" (Method A: strip method). In addition, the breaking strength was measured as it was, and the breaking strength (N) was calculated as the basis weight (g / m2) of the artificial leather. 2 ) and rounding to the third decimal place to obtain the breaking strength normalized per unit area (N / (g / m 2 )) was sought.

[0105] [Example 1] (Web Formation) Molten polyethylene terephthalate (homopolymer, intrinsic viscosity: 0.65; hereinafter and in Table 1, referred to as PET) and molten "Hytrel" (registered trademark) 4057N (manufactured by Toray Celanese Co., Ltd., polyester-based thermoplastic elastomer; referred to as TPE1 in Table 1) as a thermoplastic elastomer resin were extruded from separate nozzles of the nozzle, each of which had a hole diameter of 0.10 mm and was a perfect circle, at a single-hole extrusion rate of 0.10 g / min. At this time, the mass ratio of polyethylene terephthalate to thermoplastic elastomer resin in the total extrusion rate was 50 / 50. Thereafter, in the region 50 mm to 500 mm from the extrusion hole, 15°C air was blown at a flow rate of 30.0 m / min as cooling air to form a thread, and in the region below the inlet, the thread was pulled with 15°C air so that the spinning speed was 4,600 m / min. The distance between the extrusion hole and the inlet was 700 mm. The pulled polyethylene terephthalate fibers and thermoplastic elastomer resin fibers were collected on a net conveyor under suction to obtain a web consisting of polyethylene terephthalate fibers and thermoplastic elastomer resin fibers having an average single fiber diameter of 4.0 μm and a cross-sectional irregularity of 1.00. The fibers were in a dispersed state as single fibers.

[0106] (Formation of sheet base) Two of the obtained webs were stacked and treated alternately on the front and back sides twice each with a water jet punch (hereinafter and in Table 1 referred to as WJP) at pressures of 10 MPa and 15 MPa, and then dried with hot air at 100°C to obtain a sheet substrate.

[0107] (Formation of heat-treated sheet substrate) The sheet substrate was subjected to a hot air treatment at 200° C. to melt the thermoplastic elastomer resin, thereby obtaining a heat-treated sheet substrate in which the polyethylene terephthalate and the thermoplastic elastomer resin were bonded together.

[0108] (Formation of napped sheets and post-processing process) One surface of the heat-treated sheet substrate was ground with sandpaper to form nap on the surface, and a napped sheet was formed. After that, as a post-processing step, the sheet was dyed at 130°C using a disperse dye in a jet dyeing machine to obtain an artificial leather. The results are shown in Table 1.

[0109] [Table 1]

[0110] [Example 2] An artificial leather was obtained in the same manner as in Example 1 (web formation), except that die sets different only in the number of nozzle holes for polyethylene terephthalate and thermoplastic elastomer were used, and the mass ratio of polyethylene terephthalate to thermoplastic elastomer resin in the total discharge amount was set to 70 / 30. The results are also shown in Table 1.

[0111] [Example 3] An artificial leather was obtained in the same manner as in Example 1 (web formation), except that molten "Hytrel" (registered trademark) SC753 (a polyester-based thermoplastic elastomer manufactured by Toray Celanese Co., Ltd.; indicated as TPE2 in Table 1) was used as the thermoplastic elastomer resin. The results are also shown in Table 1.

[0112] [Example 4] An artificial leather was obtained in the same manner as in Example 1 (web formation), except that molten "Hytrel" (registered trademark) 5557M (polyester-based thermoplastic elastomer, manufactured by Toray Celanese Co., Ltd.; indicated as TPE3 in Table 1) was used as the thermoplastic elastomer resin, die sets differing only in the number of nozzle holes for the polyethylene terephthalate and thermoplastic elastomer were used, and the mass ratio of polyethylene terephthalate to thermoplastic elastomer resin in the total amount discharged was 60 / 40. The results are also shown in Table 1.

[0113] [Example 5] (Web Formation) The melted PET and the molten "Hytrel" (registered trademark) 5557 (manufactured by Toray Celanese Co., Ltd., polyester-based thermoplastic elastomer; indicated as TPE4 in Table 1) were merged in the die so as to be pasted side-by-side, and discharged from the same circular discharge hole with a diameter of 0.20 mm at a single-hole discharge rate of 0.16 g / min. At this time, the mass ratio of polyethylene terephthalate and thermoplastic elastomer resin in the total discharge rate was 59 / 41. After that, in the region 50 mm to 500 mm from the discharge hole, 15°C air was blown at a flow rate of 30.0 m / min as cooling air to form a thread, and in the region below the inlet, the thread was drawn with 15°C air so that the spinning speed was 4,500 m / min. The distance between the discharge hole and the inlet was 700 mm. The pulled polyethylene terephthalate fiber and the thermoplastic elastomer resin fiber were collected on a net conveyor under suction to obtain a latent crimped web consisting of bimetal fibers of polyethylene terephthalate fiber and thermoplastic elastomer resin, with an average single fiber diameter of 5.7 μm and a cross-sectional irregularity of 1.00. The fibers were dispersed as single fibers.

[0114] (Formation of sheet base) Two of the obtained webs were stacked and treated alternately on the front and back sides twice each with a water jet punch (hereinafter and in Table 1, referred to as WJP) at pressures of 10 MPa and 15 MPa. The webs were then dried with hot air at 100°C and then shrunk with hot air at 170°C to obtain a sheet substrate made of crimped fibers.

[0115] (Formation of heat-treated sheet substrate) The sheet substrate was subjected to a hot air treatment at 210° C. to melt the thermoplastic elastomer resin, thereby obtaining a heat-treated sheet substrate in which the polyethylene terephthalate and the thermoplastic elastomer resin were bonded together.

[0116] (Formation of napped sheets and post-processing process) One surface of the heat-treated sheet substrate was ground with sandpaper to form nap on the surface, and a napped sheet was formed. After that, as a post-processing step, the sheet was dyed at 130°C using a disperse dye in a jet dyeing machine to obtain an artificial leather. The results are shown in Table 1.

[0117] [Comparative Example 1] (Web Formation) The molten PET was discharged from each of the nozzles, each of which had a hole diameter of 0.10 mm and was a perfect circle, at a single-hole discharge rate of 0.10 g / min. Then, in the region 50 mm to 500 mm from the above-mentioned discharge hole, 15°C air was blown at a flow rate of 30.0 m / min as cooling air to form a yarn, and in the region below the inlet, the above-mentioned yarn was drawn with 15°C air so that the spinning speed was 4600 m / min. The distance between the outlet and the inlet was 700 mm. Then, the drawn polyethylene terephthalate yarn was collected on a net conveyor under suction to obtain a web consisting of polyethylene terephthalate fibers with an average single fiber diameter of 4.0 μm and a cross-sectional irregularity of 1.00 and fibers of a thermoplastic elastomer resin. The fibers were in a state of being dispersed as single fibers.

[0118] (Formation of sheet base) Two of the obtained webs were stacked and treated alternately on the front and back sides twice each with a WJP at pressures of 10 MPa and 15 MPa, and then dried with hot air at 100° C. to obtain a sheet substrate.

[0119] (Formation of polyurethane-coated sheet substrate) A water-dispersed polyurethane liquid consisting of polyether diol and diisocyanate was prepared, and the substrate was immersed in the water-dispersed polyurethane liquid. After that, polyurethane was applied by the dip / nip method, and a polyurethane-coated sheet substrate with a polyurethane resin content of 40% by mass was obtained by a dry coagulation method in which the substrate was dried at 120°C.

[0120] (Formation of napped sheets and post-processing process) One surface of the heat-treated sheet substrate was ground with sandpaper to form nap on the surface, and a napped sheet was formed. After that, as a post-processing step, the sheet was dyed at 130°C using a disperse dye in a jet dyeing machine to obtain an artificial leather. The results are shown in Table 1.

[0121] [Comparative Example 2] (Web Formation) PET as the island component and polystyrene (indicated as PS in Table 1) as the sea component were melted in an extruder, and the mass ratio of the island component to the sea component was measured to be 80:20. Island-in-sea composite fibers were extruded from the nozzle of a spinneret capable of forming a cross section in which 16 island components with uniform cross-sectional areas are distributed in the sea component at a single-hole throughput rate of 2.00 g / min. Thereafter, air at 15°C or lower was blown at a speed of 30.0 m / min onto the molten island component and sea component in an area 100 to 500 mm from the nozzle, and the fibers were drawn with the air at 15°C so that the spinning speed was 4,600 m / min. The distance between the nozzle and the inlet was 700 mm. The drawn composite fibers were collected on a net conveyor under suction to obtain a sea-island composite fiber web.

[0122] (Formation of sheet base, formation of sea-free sheet) Two of the obtained composite fiber webs were stacked and subjected to needle punching treatment (denoted as NP in Table 1) to obtain a sheet substrate. The obtained sheet substrate was immersed in trichloroethylene to dissolve and remove the sea component, and a sea-free sheet was obtained in which nonwoven fabrics made of fibers with an average single fiber diameter of 4.0 μm and a cross-sectional irregularity degree of 1.00 were entangled. Note that after the sea component was removed, the fibers were not dispersed as single fibers, and many bundled fibers were observed.

[0123] (Formation of polyurethane-coated sheet substrate) The obtained sea-free sheet was immersed in the water-dispersed polyurethane liquid used in Comparative Example 1, and then polyurethane was applied by the dip / nip method. A polyurethane-coated sheet base having a polyurethane resin content of 40% by mass was obtained by a dry coagulation method in which the sheet was dried at 120°C.

[0124] (Formation of napped sheets and post-processing process) An artificial leather was obtained by carrying out the nap raising treatment and post-processing (dyeing) in the same manner as in Example 1. The results are also shown in Table 1.

[0125] [Example 6] (Formation of resin layer forming sheet) A water-dispersed polyurethane liquid consisting of polyether diol and diisocyanate, and a carbon black-based black pigment were mixed in a mixer to prepare a resin liquid for forming a resin layer. This resin liquid was applied in the form of a sheet to a release paper having a grained uneven pattern using a comma coater, and treated in a dryer at 100°C for 3 minutes to form a non-porous resin film with a thickness of 70 μm. Next, a polycarbonate-based polyurethane resin was applied as an adhesive to the surface of the resin film using a comma coater, and heated in a dryer at 100°C for 1 minute. The surface to which the adhesive was applied was placed on the surface of the artificial leather produced in Example 1, and pressed to bond it. Thereafter, the release paper was peeled off to obtain an artificial leather having a resin layer formed on the surface. The results are shown in Table 2.

[0126] [Table 2]

[0127] [Example 7] In Example 6 (formation of resin layer-forming sheet), except that the thickness of the nonporous resin film was 150 μm, an artificial leather having a resin layer formed on the surface was obtained in the same manner as in Example 6. The results are also shown in Table 2.

[0128] [Comparative Example 3] In Example 6 (formation of resin layer-forming sheet), a resin layer was formed on the surface of the artificial leather produced in Comparative Example 2, and an artificial leather having a resin layer formed on the surface was obtained in the same manner as in Example 6, except that the thickness of the nonporous resin film was set to 150 μm. The results are also shown in Table 2.

[0129] As shown in Table 1, the artificial leathers having nap on the surface of Examples 1 to 5 have excellent surface appearance and touch, and high elongation at a load of 5 N / cm and breaking strength per unit area, which are used as indicators of moldability, and therefore have both moldability and base material strength at a high level. On the other hand, Comparative Examples 1 and 2 have good appearance and touch, but are poor in either elongation at a constant load or breaking strength.

[0130] As shown in Table 2, the artificial leathers of Examples 6 and 7, each having a resin layer on its surface, did not show any wrinkles when folded, and therefore did not show any change in appearance due to deformation, and had high elongation at a load of 5 N / cm and high breaking strength per unit area, so that they had both high moldability and high base material strength. On the other hand, Comparative Example 3 did not show any change in appearance due to deformation, but had poor strength per unit area.

Claims

1. An artificial leather containing polyester fibers having an average single fiber diameter of 2.0 μm or more and 7.0 μm or less and a thermoplastic elastomer resin as main components, the polyester fibers being long fibers dispersed as single fibers, and at least a part of the polyester fibers being bonded with the thermoplastic elastomer resin.

2. 2. The artificial leather according to claim 1, characterized in that at least one surface has nap, and the number of fiber ends observed in a 200 μm square field on the napped surface is 4 or more.

3. 3. The artificial leather according to claim 1, wherein at least one surface of the artificial leather is provided with a resin layer on at least a part of the surface.

4. The X-ray diffraction intensity I of the (−105) plane measured with wide-angle X-rays is calculated by the following formula (1): （－１０５） and the X-ray diffraction intensity I （１００） 3. The artificial leather according to claim 1, wherein the diffraction intensity ratio Z is 0.002 or more and 0.015 or less. Z=I （－１０５） / I （１００） ・・・(1)

5. 5. The artificial leather according to claim 4, wherein the thermoplastic elastomer resin has an elastic modulus of 15 MPa or more and 250 MPa or less as measured by an atomic force microscope.

6. 3. A vehicle interior material comprising the artificial leather according to claim 1 or 2.

7. A seat made of the artificial leather according to claim 1 or 2.

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