Artificial leather, manufacturing method thereof, automotive interior material, automotive component and clothing

Abstract

The present invention addresses the problem of providing an artificial leather having a compact and beautiful surface quality and simultaneously achieving good texture and wear resistance despite a process in which a copolyester is applied to a readily soluble polymer constituting an ultrafine-fiber-appearing fiber, and a method for manufacturing the same. The present invention pertains to an artificial leather comprising, as constituent elements, a fiber entangled body comprising ultrafine fibers that contain a thermoplastic resin and have an average single fiber diameter of 0.1 [mu] m to 10.0 [mu] m (inclusive), the degree of molecular orientation in the ultrafine fibers being 6.5 to 9.0 (inclusive), and a polymeric elastomer.

Description

Technical Field

[0001] The present invention relates to artificial leather, a method for producing the same, automobile interior materials, automobile components and clothing. Background Art

[0002] Artificial leather, which mimics natural leather and consists of a polymeric elastomer and a fiber entanglement primarily composed of ultrafine fibers, boasts superior durability and quality uniformity compared to natural leather. Consequently, it is used in a wide range of applications, including automotive interior materials, interior decoration, consumer electronics, and clothing, and its scope of use is expanding year by year. Artificial leather for automotive interior materials and interior decoration, among other applications, requires not only excellent surface quality but also a pleasant feel and high wear resistance to withstand actual use.

[0003] In addition, due to the recent rise in environmental awareness, environmentally friendly manufacturing processes that reduce the use of organic solvents in the production of artificial leather have attracted much attention. For example, various studies have been conducted on ultrafine fiber-forming fibers using copolyester polymers that are easily dissolved by alkali treatment during ultrafine fiber development.

[0004] For example, Patent Document 1 proposes a method for producing artificial leather. The method involves removing a specific copolyester as a sea component polymer from a fiber entanglement comprising sea-island composite fibers to reveal ultrafine fibers having a specific average single fiber diameter. The method also describes a method in which at least a portion of the ultrafine fibers have specific grooves disposed on their surfaces. The method also describes a method for producing artificial leather having high strength, excellent abrasion resistance, and a good feel.

[0005] Patent Document 2 proposes a method for producing ultrafine fiber-generating fibers, wherein polyalkylene glycol is added to the sea component polymer during melt spinning of sea-island composite fibers composed of a sea component polymer and an island component polymer. The method also discloses that the ultrafine fibers obtained can produce artificial leather with excellent surface quality and abrasion resistance.

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application Laid-Open No. 2021-155885

[0009] Patent Document 2: Japanese Patent Application Laid-Open No. 2014-231650 Summary of the Invention

[0010] Problems to be solved by the invention

[0011] In the technology disclosed in Patent Document 1, grooves are formed on the fiber surface of at least a portion of the ultrafine fibers that make up the artificial leather. This allows the ultrafine fibers to easily grip the polymer elastomer, thereby achieving a soft feel and excellent abrasion resistance. However, the presence of grooves in the ultrafine fibers leaves room for improvement in terms of surface quality and tactile feel.

[0012] The technology disclosed in Patent Document 2 adds polyalkylene glycol to the sea component polymer during melt spinning of island-in-the-sea composite fibers. This results in highly rigid, ultrafine fibers with a specific range of crystallinity and movable amorphous content. This improves entanglement efficiency, resulting in good surface quality and excellent abrasion resistance. However, the addition of a polyalkylene glycol with a high number-average molecular weight during spinning tends to result in insufficient dispersion of the polyalkylene glycol in the sea component polymer, making it difficult to achieve uniform and sufficient sea removal during alkali treatment. Consequently, the surface quality and feel of the fibers leave room for improvement.

[0013] Therefore, the present invention has been made in view of the above-mentioned circumstances, and its object is to provide an artificial leather and a method for manufacturing the same, which has a dense and beautiful surface quality while achieving good touch and wear resistance despite the manufacturing process of applying copolyester to the easily soluble polymer constituting the ultrafine fiber-forming fiber.

[0014] Means for solving problems

[0015] To achieve the above-mentioned objectives, the inventors of the present application have conducted extensive research and have determined that by stretching ultrafine fiber-developing fibers comprising a polyalkylene glycol having a specific number-average molecular weight copolymerized with a readily soluble polymer, and then heating the ultrafine fiber-developing fibers at a specific temperature to crimp them, the degree of molecular orientation in the ultrafine fibers constituting artificial leather obtained through subsequent steps can be brought within a specific range. Furthermore, the inventors have discovered that within this range of molecular orientation, the ultrafine fiber-developing fibers can exhibit good shrinkage and excellent strength. This ultimately allows for the production of artificial leather with a dense and beautiful surface quality while also achieving excellent tactile feel and abrasion resistance. This has led to the completion of the present invention.

[0016] The present invention has been accomplished based on the above findings, and according to the present invention, the following inventions are provided.

[0017] [1] Artificial leather comprising a fiber entanglement and a polymer elastomer as components, wherein the fiber entanglement is composed of ultrafine fibers containing a thermoplastic resin and having an average single fiber diameter of 0.1 μm to 10.0 μm, and the molecular orientation degree in the ultrafine fibers is 6.5 to 9.0.

[0018] [2] The artificial leather as described in [1] above, wherein the thermoplastic resin is a polyester resin, and the crystal orientation degree of the (010) plane and the crystal orientation degree of the (100) plane in the fiber structure are 0.80 or more and 0.95 or less.

[0019] [3] The artificial leather as described in [1] or [2] above, wherein the thermoplastic resin is a polyester resin, the crystallite size of the (010) plane in the fiber structure is greater than 2.0 nm and less than 5.0 nm, and the crystallite size of the (100) plane is greater than 1.0 nm and less than 4.0 nm.

[0020] [4] The artificial leather according to any one of [1] to [3], wherein at least one surface of the artificial leather has a pile, and the pile length of the surface is 200 μm to 500 μm.

[0021] [5] The method for producing artificial leather according to any one of [1] to [4], comprising:

[0022] A process for obtaining a stretched composite fiber by stretching an ultrafine fiber-emerging fiber formed by an easily soluble polymer and a poorly soluble polymer, wherein the easily soluble polymer is a copolyester copolymerized with a polyalkylene glycol having a number average molecular weight of 500 to 3500; a process for obtaining a curled composite fiber by heating the stretched composite fiber under conditions where the surface temperature of the stretched composite fiber is 40°C to 80°C; a process for forming a fiber web from the curled composite fiber and entangling the fiber web to form a composite fiber entanglement; a process for forming a fiber entanglement by allowing ultrafine fibers having an average single fiber diameter of 0.1 μm to 10.0 μm to emerge from the composite fiber entanglement; and a process for imparting a polymer elastomer to the composite fiber entanglement or the fiber entanglement.

[0023] [6] An automotive interior material comprising the artificial leather according to any one of [1] to [4] above.

[0024] [7] An automobile part comprising the artificial leather according to any one of [1] to [4] above.

[0025] [8] Clothing comprising the artificial leather according to any one of [1] to [4] above.

[0026] Effects of the Invention

[0027] According to the present invention, despite using a manufacturing process that utilizes a copolyester as a readily soluble polymer constituting ultrafine fiber-developing fibers, an artificial leather having a dense and beautiful surface quality while also achieving excellent tactile feel and abrasion resistance can be obtained. The artificial leather of the present invention can be used in a wide range of applications, including automotive interior materials, automotive parts, interior decoration, consumer electronics, and clothing. As described above, due to its dense and beautiful surface quality while achieving excellent tactile feel and abrasion resistance, it is particularly suitable for use in automotive interior materials, automotive parts, and interior decoration. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] [ Figure 1 ] Figure 1 This is a conceptual cross-sectional view for explaining a method for measuring the average pile length of the artificial leather of the present invention. DETAILED DESCRIPTION

[0029] The artificial leather of the present invention comprises, as components, an entangled fiber body composed of ultrafine fibers containing a thermoplastic resin and having an average single fiber diameter of 0.1 μm to 10.0 μm, and an elastic polymer. The ultrafine fibers have a molecular orientation degree of 6.5 to 9.0. The components are described in detail below, but the present invention is not limited to the following description in any way, and various modifications are possible without departing from the spirit of the present invention.

[0030] [Fiber entanglement]

[0031] In the case of an embodiment of the present invention (hereinafter also referred to as "this embodiment"), the artificial leather includes, as a constituent element, a fiber entanglement composed of ultrafine fibers containing a thermoplastic resin. Examples of the so-called thermoplastic resin include polyester resins, polyamide resins, polyolefin resins, acrylic resins, and polyphenylene sulfide resins. Examples of polyester resins include polyethylene terephthalate, polybutylene terephthalate, polypropylene terephthalate, polylactic acid, and mixtures and copolymers of these polyester resins. Examples of polyamide resins include polyamide 6, polyamide 66, polyamide 610, polyamide 12, and mixtures and copolymers of these polyamide resins. Examples of polyolefin resins include polyethylene, polypropylene, and mixtures and copolymers of these polyolefin resins. Among them, from the viewpoints of strength, dimensional stability, and heat resistance, polyester resins can be preferably used.

[0032] In this embodiment, examples of dicarboxylic acids and / or ester-forming derivatives thereof used in the polyester resin include terephthalic acid, isophthalic acid, 2,6-naphthalene dicarboxylic acid, biphenyl-4,4'-dicarboxylic acid, and ester-forming derivatives thereof. The ester-forming derivatives referred to in this embodiment include lower alkyl esters, anhydrides, and acid chlorides of these dicarboxylic acids. Specifically, methyl esters, ethyl esters, and hydroxyethyl esters are preferably used. A more preferred embodiment of the dicarboxylic acid and / or ester-forming derivative used in this embodiment is terephthalic acid and / or its dimethyl ester.

[0033] In the present embodiment, examples of the diol used in the polyester resin include ethylene glycol, 1,3-propylene glycol, 1,4-butanediol, and cyclohexanedimethanol. Among them, ethylene glycol is preferably used.

[0034] The aforementioned thermoplastic resin may contain inorganic particles such as titanium oxide particles, lubricants, pigments, heat stabilizers, ultraviolet absorbers, conductive agents, heat storage agents, antimicrobial agents, etc., depending on the purpose, within the range not impairing the purpose of the present invention.

[0035] The cross-sectional shape of the ultrafine fibers may be a circular cross-section or a special cross-section. Specific examples of special cross-sectional shapes include elliptical, flat, and triangular polygons, fan-shaped, cross-shaped, hollow, Y-shaped, T-shaped, and U-shaped.

[0036] In this embodiment, the average single fiber diameter of the ultrafine fibers is 0.1 μm or more and 10.0 μm or less. By setting the average single fiber diameter of the ultrafine fibers to 0.1 μm or more, preferably 0.2 μm or more, and more preferably 0.5 μm or more, the resulting artificial leather exhibits excellent color development and light resistance after dyeing. On the other hand, by setting the average single fiber diameter of the ultrafine fibers to 10.0 μm or less, preferably 8.0 μm or less, and more preferably 6.0 μm or less, the resulting artificial leather exhibits a dense surface quality and excellent tactile feel.

[0037] In addition, the average single fiber diameter of the ultrafine fibers was calculated by the following method.

[0038] (1) A cross section of the artificial leather cut in the thickness direction is observed using a scanning electron microscope (SEM, for example, "VHX-D500 / D510" manufactured by KEYENCE CORPORATION).

[0039] (2) Randomly select 30 ultrafine fibers within the observation area and measure the single fiber diameter based on the cross section of each ultrafine fiber. However, when using polyester ultrafine fibers with a non-uniform cross section, first measure the cross-sectional area of ​​the single fiber and calculate the diameter if the cross section were considered circular using the following formula to determine the single fiber diameter.

[0040] Single fiber diameter (μm) = (4 × (single fiber cross-sectional area (μm) 2 )) / π) 1 / 2

[0041] (3) The arithmetic mean value (μm) of the obtained 30 fibers is calculated, and the value is rounded off to the second decimal place. The obtained value is defined as the average single fiber diameter (μm) of the ultrafine fibers.

[0042] In the artificial leather of this embodiment, the molecular orientation degree of the ultrafine fibers is 6.5 or more and 9.0 or less. By setting the molecular orientation degree of the ultrafine fibers to 6.5 or more, preferably 6.7 or more, and more preferably 7.0 or more, the ultrafine fibers have sufficient strength, resulting in an artificial leather with high strength and excellent wear resistance. On the other hand, by setting the molecular orientation degree of the ultrafine fibers to 9.0 or less, preferably 8.8 or less, and more preferably 8.5 or less, the ultrafine fibers are not too rigid, improving processability during artificial leather production and providing excellent moldability and tactile feel.

[0043] It should be noted that, in this embodiment, the molecular orientation in the ultrafine fiber is measured using laser Raman spectroscopy and calculated by the following method. Here, Raman scattering is strongly obtained when the vibration direction of the molecular chain is consistent with the polarization direction of the incident light. Therefore, the scattering intensity of the Raman band belonging to the vibration mode parallel to the molecular chain varies with the orientation. Therefore, the polarization direction parallel to the fiber axis and the polarization direction orthogonal to the fiber axis are measured, and the intensity ratio is calculated as a parameter related to the orientation degree in the fiber axis (molecular orientation degree). The higher the molecular orientation degree, the larger the value of this parameter becomes, and it becomes 1 when there is no orientation.

[0044] (1) Ten ultrafine fibers were collected from artificial leather and irradiated with laser light on the fiber surface using a laser Raman spectrometer (e.g., "Ramanor T64000" manufactured by Jobin Yvon). The degree of orientation was measured under polarized light conditions.

[0045] (2) The polarization direction is considered to be parallel to the fiber axis, and the polarization direction is considered to be perpendicular to the fiber axis. The orientation degree is calculated using the following formula based on the ratio of the respective Raman band intensities. The value obtained by rounding off to the second decimal place is used as the molecular orientation degree in the ultrafine fiber.

[0046] Molecular orientation degree = I 平行 / I 垂直

[0047] I 平行 : The intensity of the Raman band assigned to the vibration mode parallel to the molecular chain in the case of a biased configuration parallel to the fiber axis

[0048] I 垂直 : The intensity of the Raman band assigned to the vibration mode parallel to the molecular chain in a biased configuration perpendicular to the fiber axis.

[0049] Furthermore, the molecular orientation degree in the ultrafine fibers can be adjusted to fall within the above-mentioned range by adjusting, for example, the spinning speed, the stretching ratio, the stretching temperature, the heat treatment temperature, and the like.

[0050] In this embodiment, the thermoplastic resin is preferably a polyester resin, and the crystal orientation of the (010) plane and the crystal orientation of the (100) plane in the fiber structure are preferably 0.80 or more and 0.95 or less. By setting the crystal orientation of the (010) plane and the crystal orientation of the (100) plane in the fiber structure of the ultrafine fibers to preferably 0.80 or more, more preferably 0.82 or more, an artificial leather having high strength and excellent wear resistance can be obtained. On the other hand, by setting the crystal orientation of the (010) plane and the crystal orientation of the (100) plane in the fiber structure of the ultrafine fibers to preferably 0.95 or less, more preferably 0.90 or less, an artificial leather having excellent moldability and tactile feel can be obtained.

[0051] In the present embodiment, the crystal orientation degrees of the (010) plane and the (100) plane in the fiber structure of the ultrafine fiber refer to values ​​measured and calculated by the following method using wide-angle X-ray diffraction.

[0052] (1) Ultrafine fibers are collected from artificial leather and continuously scanned using an X-ray diffraction device (e.g., the "SmartLab" X-ray generator manufactured by Rigaku Co., Ltd.) within a diffraction angle 2θ range of 5° to 60° to plot a diffraction intensity curve.

[0053] (2) In the aforementioned diffraction intensity curve, the crystal diffraction peaks (reflection planes) detected at 2θ = approximately 17° and 2θ = approximately 25° are respectively designated as the (010) plane and the (100) plane, and each reflection plane is continuously scanned from 90° to 270° along the azimuth (circumferential) direction, and the half-width of the diffraction peak of the resulting diffraction intensity curve is calculated.

[0054] (3) Based on the aforementioned half-peak width, the crystal orientation degrees of the (010) plane and the (100) plane are calculated by the following formula, and the second decimal place is rounded off. The obtained value is used as the crystal orientation degree of the (010) plane and the (100) plane in the fiber structure of the ultrafine fiber:

[0055] Crystal orientation degree = (180-half-maximum width) / 180.

[0056] Furthermore, the crystal orientation degrees of the (010) and (100) planes in the fiber structure of the ultrafine fibers can be adjusted to fall within the above range by adjusting, for example, the spinning speed, stretching ratio, stretching temperature, and heat treatment temperature.

[0057] In this embodiment, the thermoplastic resin is preferably a polyester resin, and the crystallite size of the (010) plane in the fiber structure is preferably 2.0 nm or more and 5.0 nm or less, and the crystallite size of the (100) plane is preferably 1.0 nm or more and 4.0 nm or less. By preferably setting the crystallite size of the (010) plane in the fiber structure of the ultrafine fiber to be 2.0 nm or more, more preferably 2.5 nm or more, or setting the crystallite size of the (100) plane to be 1.0 nm or more, more preferably 1.5 nm or more, an artificial leather having excellent wear resistance can be obtained. On the other hand, by preferably setting the crystallite size of the (010) plane in the fiber structure of the ultrafine fiber to be 5.0 nm or less, more preferably 4.5 nm or less, or setting the crystallite size of the (100) plane to be 4.0 nm or less, more preferably 3.5 nm or less, the ultrafine fiber can exhibit good shrinkage, resulting in an artificial leather having a dense and high-quality surface.

[0058] In the present invention, the crystallite sizes of the (010) plane and the (100) plane in the fiber structure of the ultrafine fiber refer to values ​​measured and calculated by the following method using wide-angle X-ray diffraction.

[0059] (1) Ultrafine fibers are collected from artificial leather and continuously scanned using an X-ray diffraction device (e.g., the "SmartLab" X-ray generator manufactured by Rigaku Co., Ltd.) within a diffraction angle 2θ range of 5° to 60° to plot a diffraction intensity curve.

[0060] (2) In the aforementioned diffraction intensity curve, the crystal diffraction peaks (reflection planes) detected at 2θ = approximately 17° and 2θ = approximately 25° are set as the (010) plane and the (100) plane, respectively, and the half-width of the diffraction peak of each reflection plane is calculated.

[0061] (3) Based on the aforementioned half-peak width, the crystallite size of the (010) plane and the (100) plane is calculated using the following formula, and the second decimal place is rounded off. The obtained value is used as the crystallite size (nm) of the (010) plane and the (100) plane in the fiber structure of the ultrafine fiber.

[0062] Crystallite size (nm) = 0.9 × λ / (β × cosθ)

[0063] β=(β e 2 -β0 2 ) 1 / 2

[0064] Where, λ: wavelength of X-ray (nm), θ: Bragg angle, β e : half-value width of the diffraction peak, β0: half-value width correction value (in the present invention, 0.46°).

[0065] It should be noted that the crystallite sizes of the (010) and (100) planes in the fiber structure of the ultrafine fibers can be adjusted to fall within the above ranges by adjusting, for example, the spinning speed, stretching ratio, stretching temperature, and heat treatment temperature.

[0066] The artificial leather of this embodiment exhibits the form of a fiber entanglement obtained from the aforementioned ultrafine fibers. This allows for a dense, elegant surface quality and a soft feel when the surface is raised using the method described below. It should be noted that, as described below, this fiber entanglement is formed from a composite fiber entanglement as its precursor. Examples of the composite fiber entanglement include: a short fiber entanglement obtained by forming a laminated fiber web from short fibers using a carding machine or a cross-lapper and then subjecting it to needle punching or hydroentangling; a long fiber entanglement obtained by spunbonding, meltblowing, or other methods; and a entanglement obtained by papermaking. Furthermore, the fiber entanglement can be formed by developing ultrafine fibers from the ultrafine fiber-developing fibers that comprise the composite fiber entanglement. In particular, when the composite fiber entanglement is a short fiber entanglement, compared to other entanglements, more fibers can be oriented in the thickness direction of the artificial leather, resulting in an artificial leather with a high density and a good feel when raised. Furthermore, the artificial leather exhibits excellent thickness uniformity.

[0067] When using a short fiber entanglement, the ultrafine fibers constituting the short fiber entanglement preferably have a fiber length of 25 mm or more and 90 mm or less. By setting the ultrafine fiber length to preferably 25 mm or more, more preferably 35 mm or more, and even more preferably 40 mm or more, the entanglement results in an artificial leather having excellent abrasion resistance. Furthermore, by setting the ultrafine fiber length to preferably 90 mm or less, more preferably 80 mm or less, and even more preferably 70 mm or less, the artificial leather has excellent surface quality and feel.

[0068] In the present embodiment, the ultrafine fibers constituting the short fiber entanglement may contain various additives and the like depending on the purpose.

[0069] In the artificial leather of the present embodiment, a woven fabric or a knitted fabric may be inserted into, layered on, or lined with the conjugate fiber entangled body for the purpose of improving its strength, morphological stability, and the like.

[0070] [Polymer elastomer]

[0071] The artificial leather of this embodiment includes a polymeric elastic body as a component. Due to the adhesive effect of the polymeric elastic body, it is possible to prevent the ultrafine fibers from falling out of the artificial leather and also to impart a moderate sense of resilience.

[0072] Examples of the high molecular weight elastic body include polyurethane, polyurea, and polyacrylic acid. Polyurethane is preferably used from the viewpoint of durability and flexibility.

[0073] In this embodiment, when polyurethane is used as the polymer elastomer, both organic solvent-based polyurethane used in a state of being dissolved in an organic solvent and water-dispersible polyurethane used in a state of being dispersed in water can be used. From the viewpoint of environmental protection, water-dispersible polyurethane can be preferably used.

[0074] When using a water-dispersible polyurethane, it is more preferable to use a water-dispersible polyurethane obtained by reacting a high molecular weight polyol (described below), an organic diisocyanate, and a compound containing an active hydrogen component having a hydrophilic group to form a hydrophilic prepolymer, then adding a chain extender and reacting them to obtain a polyurethane precursor, and then reacting the polyurethane precursor with a crosslinking agent. These are described in detail below.

[0075] (a) Polyols

[0076] Examples of the polymer polyol that can be preferably used in the present embodiment include polyether polyol, polyester polyol, and polycarbonate polyol.

[0077] First, examples of polyether polyols include those obtained by addition polymerization of monomers such as ethylene oxide, propylene oxide, butylene oxide, styrene oxide, tetrahydrofuran, epichlorohydrin, and cyclohexene using polyols and polyamines as initiators, and those obtained by ring-opening polymerization of the aforementioned monomers using protonic acids, Lewis acids, and cationic catalysts as catalysts. Specifically, examples include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and the like, as well as copolyols obtained by combining these.

[0078] Next, examples of the polyester polyol include polyester polyols obtained by condensing various low-molecular-weight polyols with polybasic acids and polyols obtained by polyopening of lactones.

[0079] Examples of low-molecular-weight polyols used in polyester polyols include one or more selected from linear alkylene glycols such as ethylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, and 1,10-decanediol; branched alkylene glycols such as neopentyl glycol, 3-methyl-1,5-pentanediol, 2,4-diethyl-1,5-pentanediol, and 2-methyl-1,8-octanediol; alicyclic diols such as 1,4-cyclohexanediol; and aromatic diols such as 1,4-bis(β-hydroxyethoxy)benzene. Furthermore, adducts obtained by adding various alkylene oxides to bisphenol A can also be used as low-molecular-weight polyols.

[0080] On the other hand, examples of the polyacid used in the polyester polyol include one or more selected from the group consisting of succinic acid, maleic acid, adipic acid, glutaric acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, dodecanedioic acid, phthalic acid, isophthalic acid, terephthalic acid, and hexahydroisophthalic acid.

[0081] Examples of the polycarbonate polyol include compounds obtained by reaction of a polyol with a dialkyl carbonate, a polyol with a diaryl carbonate, or the like, or a polyol with a carbonate compound.

[0082] As the polyol used in the polycarbonate polyol, a low molecular weight polyol used in the polyester polyol can be used. On the other hand, as the dialkyl carbonate, dimethyl carbonate, diethyl carbonate, etc. can be used, and as the diaryl carbonate, diphenyl carbonate, etc. can be used.

[0083] It should be noted that the number average molecular weight of the polymer polyol that can be preferably used in this embodiment is preferably 500 to 5000. By making the number average molecular weight of the polymer polyol preferably 500 or more, more preferably 1500 or more, it is easy to prevent the feel of the artificial leather from becoming hard. On the other hand, by making the number average molecular weight preferably 5000 or less, more preferably 4000 or less, it is easy to maintain the strength of the water-dispersible polyurethane used as a binder.

[0084] (b) Organic diisocyanates

[0085] Organic diisocyanates that can be preferably used in this embodiment include aromatic diisocyanates having a carbon number of 6 or more and a carbon number of 20 or less (excluding the carbon in the isocyanate (NCO) group, the same applies hereinafter), aliphatic diisocyanates having a carbon number of 2 or more and a carbon number of 18 or less, alicyclic diisocyanates having a carbon number of 4 or more and a carbon number of 15 or less, aromatic aliphatic diisocyanates having a carbon number of 8 or more and a carbon number of 15 or less, modified products of these diisocyanates (carbodiimide modified products, urethane modified products, uretdione modified products, etc.), and mixtures of two or more of these.

[0086] Specific examples of the aromatic diisocyanate having 6 to 20 carbon atoms include 1,3-phenylene diisocyanate and / or 1,4-phenylene diisocyanate, 2,4- and / or 2,6-toluene diisocyanate, 2,4'-diphenylmethane diisocyanate and / or 4,4'-diphenylmethane diisocyanate (hereinafter abbreviated as MDI), 4,4'-biphenyl diisocyanate, 3,3'-dimethyl-4,4'-biphenyl diisocyanate, 3,3'-dimethyl-4,4'-diphenylmethane diisocyanate, and 1,5-naphthalene diisocyanate. Among them, MDI is preferably used because it exhibits excellent flexibility when formed into a water-dispersible polyurethane.

[0087] Specific examples of the aliphatic diisocyanate having 2 to 18 carbon atoms include ethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, dodecamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, lysine diisocyanate, 2,6-diisocyanatomethylhexanoate, bis(2-isocyanatoethyl)carbonate, and 2-isocyanatoethyl-2,6-diisocyanatohexanoate.

[0088] Specific examples of the aforementioned alicyclic diisocyanate having 4 to 15 carbon atoms include isophorone diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, cyclohexylene diisocyanate, methylcyclohexylene diisocyanate, bis(2-isocyanatoethyl)-4-cyclohexylene-1,2-dicarboxylate, and 2,5-norbornane diisocyanate and / or 2,6-norbornane diisocyanate. Among them, dicyclohexylmethane-4,4'-diisocyanate is preferably used because it exhibits excellent durability when formed into a water-dispersible polyurethane.

[0089] Specific examples of the aromatic aliphatic diisocyanate having 8 to 15 carbon atoms include m-xylylenediisocyanate and / or p-xylylenediisocyanate, and α,α,α′,α′-tetramethylxylylenediisocyanate.

[0090] (c) Compounds containing an active hydrogen component having a hydrophilic group

[0091] Examples of compounds containing active hydrogen components having a hydrophilic group that can be preferably used in this embodiment include compounds containing active hydrogen and one or more groups selected from the group consisting of nonionic groups, anionic groups, and cationic groups. These compounds containing active hydrogen components can also be used in the form of salts obtained by neutralization with a neutralizing agent. By using these compounds containing active hydrogen components having a hydrophilic group, the stability of the aqueous dispersion used in the method for producing artificial leather can be improved.

[0092] Examples of the compound having a nonionic group and active hydrogen include compounds containing two or more active hydrogen components or two or more isocyanate groups and having a polyoxyethylene glycol group having a molecular weight of 250 to 9000 on the side chain, and triols such as trimethylolpropane and trimethylolbutane.

[0093] Examples of the compound having an anionic group and active hydrogen include carboxyl group-containing compounds such as 2,2-dimethylolpropionic acid, 2,2-dimethylolbutanoic acid, and 2,2-dimethylolvaleric acid, and their derivatives; sulfonic acid group-containing compounds such as 1,3-phenylenediamine-4,6-disulfonic acid and 3-(2,3-dihydroxypropoxy)-1-propanesulfonic acid, and their derivatives; and salts obtained by neutralizing these compounds with a neutralizing agent.

[0094] Examples of the compound containing a cationic group and active hydrogen include tertiary amino group-containing compounds such as 3-dimethylaminopropanol, N-methyldiethanolamine, and N-propyldiethanolamine, and derivatives thereof.

[0095] (d) Chain extender

[0096] Examples of the chain extender that can be preferably used in the present embodiment include water, low molecular weight diols such as ethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol, 1,6-hexanediol, diethylene glycol, and neopentyl glycol, alicyclic diols such as 1,4-bis(hydroxymethyl)cyclohexane, aromatic diols such as 1,4-bis(hydroxyethyl)benzene, aliphatic diamines such as ethylenediamine, alicyclic diamines such as isophoronediamine, aromatic diamines such as 4,4′-diaminodiphenylmethane, aromatic aliphatic diamines such as xylylenediamine, alkanolamines such as ethanolamine, hydrazine, dihydrazides such as adipic acid dihydrazide, and mixtures of two or more thereof.

[0097] Among these, preferred chain extenders are water, low molecular weight diols, and aromatic diamines, and more preferred examples include water, ethylene glycol, 1,4-butanediol, 4,4′-diaminodiphenylmethane, and mixtures of two or more thereof.

[0098] (e) Composition of polyurethane precursor

[0099] As described above, the polyurethane precursor preferably used in this embodiment is prepared by reacting the aforementioned high molecular weight polyol, organic diisocyanate, and a compound containing an active hydrogen component having a hydrophilic group to form a hydrophilic prepolymer, and then adding a chain extender and reacting them.

[0100] (f) Cross-linking agent

[0101] As the cross-linking agent used in this embodiment, a cross-linking agent having two or more reactive groups in the molecule that can react with the reactive group introduced into the polyurethane precursor can be used, and specifically, polyisocyanate cross-linking agents such as water-soluble isocyanate compounds and blocked isocyanate compounds, melamine cross-linking agents, oxazoline cross-linking agents, carbodiimide cross-linking agents, etc. can be mentioned. The cross-linking agents can be used alone or in combination of two or more.

[0102] The water-soluble isocyanate compound is a compound having two or more isocyanate groups in the molecule, and examples thereof include compounds contained in the aforementioned organic polyisocyanate.

[0103] Blocked isocyanate compounds are compounds with two or more blocked isocyanate groups in their molecules. Blocked isocyanate groups are formed by blocking the aforementioned organic polyisocyanate compounds with blocking agents such as amines, phenols, imines, thiols, pyrazoles, oximes, and active methylene groups.

[0104] Examples of the oxazoline-based cross-linking agent include compounds having two or more oxazoline groups (oxazoline skeleton) in the molecule.

[0105] Examples of the carbodiimide-based crosslinking agent include compounds having two or more carbodiimide groups in the molecule.

[0106] Among these, it is preferable to use a carbodiimide compound because the water-dispersible polyurethane obtained after the reaction has particularly excellent durability and flexibility.

[0107] (g) Composition of water-dispersible polyurethane

[0108] From the perspectives of flexibility and durability, the water-dispersible polyurethane preferably used in this embodiment preferably contains components derived from polyether polyols and / or polycarbonate polyols. By including components derived from polyether polyols in the water-dispersible polyurethane, the high degree of freedom of the ether bonds results in a low glass transition temperature and weak cohesion, thereby forming a water-dispersible polyurethane with excellent flexibility. Furthermore, by including components derived from polycarbonate polyols in the water-dispersible polyurethane, the high cohesion of the carbonate groups results in a water-dispersible polyurethane with excellent water resistance, heat resistance, weather resistance, and mechanical properties.

[0109] It should be noted that as a method for confirming the constituent components of the water-dispersible polyurethane (confirming whether the water-dispersible polyurethane contains constituent components derived from polyester polyol and / or the water-dispersible polyurethane contains constituent components derived from polycarbonate polyol), the polyester constituting the artificial leather is dissolved, and the insoluble matter (water-dispersible polyurethane) is subjected to infrared spectroscopy analysis (analytical equipment such as the "FT / IR 4000 series" manufactured by JASCO Corporation) or thermal decomposition GC / MS analysis (analytical equipment such as the "GCMS-QP5050A" manufactured by Shimadzu Corporation) for analysis. It should be noted that as a solvent capable of dissolving the polyester constituting the artificial leather, m-cresol or hexafluoroisopropanol can be used, and hexafluoroisopropanol, which can be used at room temperature, is preferably used.

[0110] The water-dispersible polyurethane used in this embodiment preferably has N-acylurea bonds and / or isourea bonds. These bonds are formed by the reaction of the cross-linking agent having the hydrophilic group and the carbodiimide group, and by forming a cross-linked structure in the water-dispersible polyurethane, the durability of the water-dispersible polyurethane can be improved.

[0111] It should be noted that when the above-mentioned N-acylurea groups and isourea groups are present in the water-dispersible polyurethane, analysis can be performed by subjecting the cross section of the artificial leather to mapping treatment such as time-of-flight secondary ion mass spectrometry (TOF-SIMS analysis) (as an analytical instrument, for example, the "TOF.SIMS 5" manufactured by ION-TOF Corporation) or infrared spectroscopy (as an analytical instrument, for example, the "FT / IR 4000 series" manufactured by JASCO Corporation).

[0112] Generally, the content of the polymeric elastomer in artificial leather can be appropriately adjusted based on the type of polymeric elastomer used, the production method of the polymeric elastomer, and its feel and physical properties. In this embodiment, the polymeric elastomer content is preferably set to 10% by mass or more and 50% by mass or less relative to the mass of the artificial leather. By setting the polymeric elastomer content to preferably 10% by mass or more, and more preferably 15% by mass or more, artificial leather with excellent wear resistance can be produced. On the other hand, by setting the polymeric elastomer content to preferably 50% by mass or less, and more preferably 35% by mass or less, artificial leather with a soft feel can be produced.

[0113] In addition, the polymer elastomer may contain various additives depending on the purpose, for example, pigments such as "inorganic and oxide-based", flame retardants such as "phosphorus-based, halogen-based and inorganic-based", antioxidants such as "phenol-based, sulfur-based and phosphorus-based", ultraviolet absorbers such as "benzotriazole-based, benzophenone-based, salicylate-based, cyanoacrylate-based and oxalanilide-based", light stabilizers such as "hindered amine-based and benzoate-based", hydrolysis stabilizers such as polycarbodiimide, plasticizers, antistatic agents, surfactants, coagulation regulators and dyes.

[0114] [Artificial leather]

[0115] The artificial leather of this embodiment includes the aforementioned fiber entanglement and polymer elastomer as components. Furthermore, in the artificial leather of this embodiment, preferably, at least one surface has a pile surface. Depending on the intended purpose, the artificial leather may have a pile surface on only one side, or both sides may have pile surfaces. From the perspective of design effectiveness, the pile shape when the surface has pile preferably has a pile length and directional softness sufficient to produce a finger mark due to the change in pile direction when swiping across it.

[0116] More specifically, the length of the pile on the surface, i.e., the pile length, is preferably 200 μm or more and 500 μm or less. A pile length of 200 μm or more, more preferably 220 μm or more, allows for the formation of artificial leather with a suede-like, elegant surface quality and excellent tactile feel. On the other hand, a pile length of 500 μm or less, more preferably 450 μm or less, allows for the formation of artificial leather with excellent abrasion resistance and suppresses degradation of surface quality associated with entanglement of ultrafine fibers.

[0117] When at least one surface of the artificial leather is the surface having pile as described above, the pile length of the surface is a value measured and calculated by the following method.

[0118] (1) Using a lint brush or the like, with the pile of the artificial leather in an inverted state, a scanning electron microscope (SEM, e.g., "VHX-D500 / D510" manufactured by KEYENCE CO., LTD.) is used to photograph a cross section perpendicular to the longitudinal direction of the artificial leather at a magnification of 50 to 120 times.

[0119] (2) In the SEM images taken, according to Figure 1 The schematic diagram of the cross section of the artificial leather shown is shown in FIG. Figure 1 In, L B ) parallel lines( Figure 1 In, L A ) with 10 lines drawn at 200 μm intervals relative to the bottom surface ( Figure 1 In, L B ) of the perpendicular line (A1~A 10 ).

[0120] (3) perpendicular lines A1 to A 10 Points P1 to P2 intersect with the following boundary line (L0) 10 Marking, the boundary line (L0) is the pile head ( Figure 1 1) and the base portion ( Figure 1 In the figure, it is the boundary line of 2).

[0121] (4) perpendicular lines A1 to A 10 Points Q1 to Q2 intersecting with the front end of the pile portion 1 10 Mark.

[0122] (5) Set the distance between point P1 and point Q1 to R1, and set point P n and dot Q n The distance is set to R n , similarly find out to R 10 , calculate its average value (arithmetic mean).

[0123] The apparent density of the artificial leather of this embodiment is preferably 0.30 g / cm 3 Above 0.50g / cm 3 By making the apparent density of artificial leather preferably 0.30 g / cm 3 More preferably, 0.32 g / cm 3 On the other hand, the apparent density of the artificial leather is preferably 0.50 g / cm 3 Below, more preferably 0.45g / cm 3 The following makes it a soft-touch artificial leather.

[0124] The artificial leather of this embodiment preferably has a thickness of 0.2 mm or greater and 1.5 mm or less, as measured by "6.1 Thickness (ISO Method)" in JIS L1913:2010 "Test Methods for General Nonwoven Fabrics," 6.1.1A Method. By setting the thickness of the artificial leather to preferably 0.2 mm or greater, and more preferably 0.3 mm or greater, the artificial leather not only has excellent processability during production but also has a substantial feel and excellent hand feel. On the other hand, by setting the thickness of the artificial leather to preferably 1.5 mm or less, and more preferably 1.2 mm or less, the artificial leather has excellent formability and is soft.

[0125] Furthermore, in an abrasion resistance test measured using the "8.19.5E method (Martindale method)" in "8.19 Abrasion strength and frictional discoloration" of JIS L1096:2010 "Test Methods for Fabrics of Woven and Knitted Fabrics," the artificial leather of this embodiment exhibits a weight loss of preferably 30 mg or less, more preferably 27 mg or less, and even more preferably 25 mg or less, after 50,000 abrasions at a pressing load of 12.0 kPa. By achieving a weight loss of 30 mg or less, the artificial leather can be prevented from staining and deteriorating the appearance of the artificial leather due to shedding during actual use.

[0126] [Manufacturing method of artificial leather]

[0127] The method for producing artificial leather of the present embodiment preferably includes the following steps:

[0128] A step of drawing an ultrafine fiber-developing fiber composed of a highly soluble polymer and a poorly soluble polymer to obtain a drawn conjugate fiber, wherein the highly soluble polymer is a copolyester copolymerized with a polyalkylene glycol having a number average molecular weight of 500 to 3500.

[0129] The step of heating the drawn conjugated fiber under conditions where the surface temperature of the drawn conjugated fiber is 40° C. or higher and 80° C. or lower, and then imparting crimps to the drawn conjugated fiber to obtain a crimped conjugated fiber;

[0130] The process of forming a fiber web from the crimped conjugate fibers and entangling the fiber web to form an entangled conjugate fiber body;

[0131] a step of allowing ultrafine fibers having an average single fiber diameter of 0.1 μm to 10.0 μm to emerge from the composite fiber entanglement to form a fiber entanglement; and

[0132] A step of adding a polymer elastic body to the composite fiber entangled body or the fiber entangled body.

[0133] The preferred embodiment will be described below in detail. However, the present invention is not limited to the following description and various modifications can be made without departing from the spirit of the present invention.

[0134] <Step of Obtaining a Drawn Conjugated Fiber>

[0135] In this process, ultrafine fiber-developing fibers composed of a highly soluble polymer, which is a copolyester copolymerized with a polyalkylene glycol having a number average molecular weight of 500 to 3500, and a poorly soluble polymer are first stretched to produce stretched composite fibers. In this embodiment, the ultrafine fiber-developing fibers refer to fibers such as island-in-the-sea composite fibers and core-sheath composite fibers, in which the highly soluble polymer is removed, resulting in the remaining poorly soluble polymer forming ultrafine fibers. Furthermore, the highly soluble polymer refers to a resin (described later) that dissolves within 5 minutes when immersed in a solution such as an alkaline aqueous solution used to remove the highly soluble polymer from the ultrafine fiber-developing fibers. Conversely, the poorly soluble polymer refers to a resin (described later) that does not dissolve in the aforementioned solution for more than 10 minutes.

[0136] (1) Soluble polymers

[0137] Examples of the easily soluble polymer for the ultrafine fiber-forming fibers include polylactic acid and copolyesters. Copolyesters are preferably used from the viewpoints of yarn-forming properties and ease of dissolution by alkali treatment.

[0138] When using a copolyester, a copolyester obtained by copolymerizing 3 mol% to 15 mol% of 5-sodium sulfoisophthalate as a copolymer component is preferred. By preferably copolymerizing the 5-sodium sulfoisophthalate component in an amount of 3 mol% or more, more preferably 5 mol% or more, sufficient alkali solubility can be achieved. On the other hand, by preferably copolymerizing the 5-sodium sulfoisophthalate component in an amount of 15 mol% or less, more preferably 13 mol% or less, the thickening of the polyester is suppressed, thereby reducing the occurrence of fiber breakage during the spinning of ultrafine fiber-forming fibers.

[0139] Furthermore, the aforementioned copolyester preferably comprises a polyalkylene glycol having a number average molecular weight of 500 to 3500, more preferably 700 to 3000. By setting the number average molecular weight of the polyalkylene glycol within this range, the dispersibility of the polyalkylene glycol in the readily soluble polymer is improved, resulting in excellent spinning properties and alkali dissolution properties of the ultrafine fiber-forming fibers, and enabling uniform and sufficient sea-removal during alkali treatment.

[0140] The copolymerization amount of the polyalkylene glycol in the readily soluble polymer is preferably from 0.1% to 15% by mass. By setting the copolymerization amount of the polyalkylene glycol to preferably from 0.1% to 1.5% by mass, alkali solubility is improved. On the other hand, by setting the copolymerization amount of the polyalkylene glycol to preferably from 15% to 12% by mass, filament breakage is less likely to occur during the spinning of ultrafine fiber-forming fibers.

[0141] Examples of the polyalkylene glycol include polyethylene glycol, polypropylene glycol, and polybutylene glycol. Polyethylene glycol is preferably used in view of ease of use and weight reduction in alkaline aqueous solutions.

[0142] Furthermore, the readily soluble polymer constituting the ultrafine fiber-forming fibers is preferably a polyethylene terephthalate-based polyester containing ethylene terephthalate units as the main repeating unit in one component. Alternatively, a polyester obtained by replacing a portion of the terephthalic acid component with another difunctional carboxylic acid component may be used. Similarly, a polyester obtained by replacing a portion of the ethylene glycol component with another polyol component may be used.

[0143] As difunctional carboxylic acids other than terephthalic acid used in this embodiment, for example, aromatic, aliphatic, and alicyclic difunctional carboxylic acids such as isophthalic acid, naphthalene dicarboxylic acid, biphenyl dicarboxylic acid, adipic acid, sebacic acid, and 1,4-cyclohexane dicarboxylic acid can be preferably used. Furthermore, as polyol compounds other than ethylene glycol, for example, aliphatic, alicyclic, and aromatic polyol compounds such as tetramethylene glycol, hexamethylene glycol, cyclohexane-1,4-dimethanol, neopentyl glycol, bisphenol A, and bisphenol S can be preferably used.

[0144] In addition, the easily soluble polymer constituting the ultrafine fiber-developing fiber and the poorly soluble polymer described later may contain inorganic particles such as titanium oxide particles, lubricants, pigments, heat stabilizers, ultraviolet absorbers, conductive agents, heat storage agents, antibacterial agents, etc., depending on various purposes and within the scope that does not impair the purpose of the present invention.

[0145] (2) Poorly soluble polymers

[0146] As the insoluble polymer of the ultrafine fiber-forming fiber, polyester resin, polyamide resin, polyolefin resin, acrylic resin, polyphenylene sulfide resin, etc., which are listed as the thermoplastic resins constituting the ultrafine fibers, can be cited. As polyester resins, polyethylene terephthalate, polybutylene terephthalate, polypropylene terephthalate, polylactic acid, and mixtures and copolymers of these polyester resins can be cited. In addition, as polyamide resins, polyamide 6, polyamide 66, polyamide 610, polyamide 12, and mixtures and copolymers of these polyamide resins can be cited. In addition, as polyolefin resins, polyethylene, polypropylene, and mixtures and copolymers of these polyolefin resins can be cited. Among them, from the viewpoints of strength, dimensional stability, and heat resistance, polyester resin can be preferably used. In addition, the insoluble polymer can contain inorganic particles such as titanium oxide particles, lubricants, pigments, heat stabilizers, ultraviolet absorbers, conductive agents, heat storage agents, antibacterial agents, etc., according to various purposes.

[0147] (3) Ultrafine fiber-forming fibers

[0148] For ultrafine fiber-forming fibers, there are methods using an island-type composite spinneret or a core-sheath-type composite spinneret to alternately arrange and spin two components, a readily soluble polymer and a poorly soluble polymer, using a polymer alternating arrangement body, and a mixed spinning method in which the two components, a readily soluble polymer and a poorly soluble polymer, are mixed and spun. From the perspective of obtaining ultrafine fibers with uniform single fiber fineness, island-type composite fibers or core-sheath-type composite fibers based on the method using a polymer alternating arrangement body are preferred.

[0149] The ultrafine fiber-developing type fiber used in the artificial leather of this embodiment can be obtained by using a conventional composite spinneret equipped with a pipe group, such as a composite spinning spinneret described in Japanese Patent Gazette No. 2011-174215, which is capable of forming various cross-sectional shapes by combining a metering plate having multiple metering holes (which meters the polymer flow of each component) and a distribution plate having multiple distribution holes in a confluence groove (which allows the ejected polymer flows from multiple metering holes to merge).

[0150] The ratio of the readily soluble polymer to the poorly soluble polymer in the ultrafine fiber-developing fiber is preferably 20% or more and 95% or less, based on the mass ratio of the poorly soluble polymer to the ultrafine fiber-developing fiber. By setting the mass ratio of the poorly soluble polymer to preferably 20% or more, and more preferably 30% or more, the removal rate of the readily soluble polymer can be reduced, further improving productivity. On the other hand, by setting the mass ratio of the poorly soluble polymer to preferably 95% or less, and more preferably 90% or less, the confluence of the poorly soluble polymer can be prevented, thereby suppressing degradation of surface quality.

[0151] The spinning speed for obtaining ultrafine fiber-forming fibers is preferably 500 m / min to 3000 m / min. By setting the spinning speed to preferably 500 m / min or higher, and more preferably 800 m / min or higher, the average single fiber diameter of the ultrafine fibers can be easily reduced to 10.0 μm or lower, enabling the formation of dense artificial leather with excellent surface quality and tactile feel. Furthermore, by setting the spinning speed to preferably 3000 m / min or lower, and more preferably 2000 m / min or lower, the frequency of fiber breakage is reduced, further improving productivity.

[0152] (4) Stretching of ultrafine fiber-forming fibers

[0153] At the end of this process, the aforementioned ultrafine fiber-developing fiber is stretched to produce a stretched conjugate fiber. The stretch ratio is preferably 2.0 times or more and 4.5 times or less. By setting the stretch ratio to 2.0 times or more, and more preferably 2.3 times or more, an ultrafine fiber-developing fiber with sufficient strength can be obtained. On the other hand, by setting the stretch ratio to 4.5 times or less, and more preferably 4.2 times or less, excellent stability during the stretching process can be achieved.

[0154] The stretching temperature during the above-mentioned stretching is preferably 50°C or higher and 80°C or lower. Here, the stretching temperature refers to the temperature of the heat source with which the ultrafine fiber-developing fibers come into contact during the stretching process. Specifically, in the case of roller stretching, it refers to the surface temperature of the roller; in the case of liquid bath stretching, it refers to the liquid temperature of the liquid bath; in the case of steam stretching, it refers to the temperature of the atmosphere within the steam box. By setting the stretching temperature preferably at 50°C or higher, ultrafine fiber-developing fibers with minimal orientation unevenness can be obtained. On the other hand, by setting the stretching temperature preferably at 80°C or lower, the dissolution of the readily soluble polymer during the stretching process can be suppressed.

[0155] <Step of Obtaining Crimped Conjugated Fiber>

[0156] In this step, the stretched conjugated fiber is heated to a surface temperature of 40°C to 80°C, and then crimped to obtain a crimped conjugated fiber. In addition to adjusting the aforementioned conditions such as the stretch ratio and stretching temperature, this heat treatment allows for control of the molecular orientation of the ultrafine fibers constituting the artificial leather, thereby achieving the desired artificial leather, which exhibits a dense and elegant surface quality while also achieving excellent tactile feel and abrasion resistance, as is the objective of the present invention.

[0157] In this embodiment, the surface temperature of the drawn conjugated fiber during heating is preferably 40°C to 80°C, and more preferably 45°C to 70°C. By keeping the heating temperature within this range, the dissolution of the readily soluble polymer can be suppressed, and the ultrafine fiber-developing fiber can have appropriate elongation and shrinkage, resulting in excellent processability in subsequent steps. Furthermore, the molecular orientation degree in the ultrafine fibers, a characteristic feature of this embodiment, can be maintained within a specific range.

[0158] It should be noted that in the method for producing artificial leather of this embodiment, the tensile strength of the insoluble polymer portion of the stretched conjugate fiber or crimped conjugate fiber is preferably 3.0 cN / dtex or greater. By setting the tensile strength of the insoluble polymer portion to preferably 3.0 cN / dtex or greater, and more preferably 3.2 cN / dtex or greater, the abrasion resistance of the artificial leather can be improved, and the reduction in friction fastness associated with fiber shedding can be suppressed.

[0159] In the present embodiment, the tensile strength of the poorly soluble polymer portion of the stretched conjugated fiber or the crimped conjugated fiber is calculated by the following method.

[0160] (1) Ten stretched composite fibers or crimped composite fibers with a length of 20 cm are bundled.

[0161] (2) The readily soluble polymer is dissolved and removed from the sample of (1), and then air-dried.

[0162] (3) According to "8.5 Tensile strength and elongation" and "8.5.1 Standard time test" of JIS L1013:2010 "Test methods for chemical fiber filaments", 10 tests were performed under the conditions of a clamping length of 5 cm, a tensile speed of 5 cm / min, and a load of 2 N.

[0163] (4) The arithmetic mean value (cN / dtex) of the test results obtained in (3) is rounded off to the second decimal place, and the resulting value is used as the tensile strength of the poorly soluble polymer portion constituting the drawn conjugated fiber or crimped conjugated fiber.

[0164] <Step of Forming a Composite Fiber Entangled Body>

[0165] In this step, a fiber web is formed from the crimped conjugate fibers, and the fiber web is entangled to form a conjugate fiber entanglement. More specifically, the crimped conjugate fibers are opened, formed into a fiber web using a cross-lapper, etc., and the fiber web is entangled to form a conjugate fiber entanglement.

[0166] As a method for forming a fiber web and entangling the fiber web to obtain a composite fiber entangled body, needle punching, hydroentanglement, etc. can be used. Among them, needle punching is preferred because of its high entangling efficiency.

[0167] As the form of the composite fiber entanglement, both the short fiber entanglement and the long fiber entanglement as described above can be used. If it is a short fiber entanglement, compared with the long fiber entanglement, the fibers oriented in the thickness direction of the artificial leather will be more, and the surface of the artificial leather can obtain a high density when raised.

[0168] When forming a short fiber entanglement, the obtained crimped conjugate fibers are cut into a predetermined length, and then opened, stacked, and entangled to obtain a short fiber entanglement.

[0169] The needles used in the needling treatment preferably have a barb (notch) number of 1 or more and a barb number of 9 or less. By having 1 or more barbs, efficient fiber entanglement can be achieved. On the other hand, by having 9 or fewer barbs, fiber damage can be suppressed.

[0170] The number of ultrafine fiber-forming fibers attached to the barbs is determined by the shape of the barbs and the diameter of the ultrafine fiber-forming fibers. Therefore, the barbs of the needles used in the needling process preferably have an upturn of 0 μm to 50 μm, a chamfer angle of 0° to 40°, a throat depth of 40 μm to 80 μm, and a throat length of 0.5 mm to 1.0 mm.

[0171] The number of needles in the needling treatment is preferably 1000 / cm 2 More than 8000 pieces / cm 2 By making the number of needle punches preferably 1000 / cm 2 In addition, the number of needle punches is preferably 8000 / cm 2 Below, it is possible to prevent deterioration of processability, fiber damage, and strength reduction.

[0172] Furthermore, when performing hydroentanglement, it is preferable to perform the treatment with water in a columnar flow state. Specifically, it is preferable to spray water from a nozzle having a diameter of 0.05 mm to 1.0 mm at a pressure of 2 MPa to 60 MPa.

[0173] It is preferred that the apparent density of the composite fiber entanglement formed of the ultrafine fiber-developing type fibers after needle punching or hydroentanglement is 0.15 g / cm 3 Above 0.40g / cm 3 By making the apparent density of the composite fiber entangled body preferably 0.15 g / cm 3 More preferably, 0.20 g / cm 3 On the other hand, the apparent density of the composite fiber entangled body is preferably 0.40 g / cm 3 Below, more preferably 0.35g / cm 3 As a result, the space for applying the polymeric elastic body can be maintained, and thus the polymeric elastic body can be applied uniformly, thereby forming an artificial leather having an excellent resilience.

[0174] In addition, it is preferred that the weight per unit area of ​​the composite fiber entangled body be 200 g / m 2 Above 900g / m 2 By making the unit area weight of the composite fiber entangled body preferably 200 g / m 2 More than 250g / m 2 On the other hand, by making the unit area weight of the composite fiber entangled body preferably 900 g / m 2 Below, more preferably 800g / m 2 Hereinafter, a soft artificial leather having excellent moldability can be formed.

[0175] In order to increase the density of the fibers, it is also preferable to subject the aforementioned conjugate fiber entangled body to a heat shrinkage treatment using warm water or steam.

[0176] Then, the conjugated fiber entangled body may be impregnated with an aqueous solution of a water-soluble resin and dried to impart a water-soluble resin. By imparting a water-soluble resin to the conjugated fiber entangled body, the fibers are fixed and the dimensional stability is improved.

[0177] <Step of Forming a Fiber Entanglement by Revealing Ultrafine Fibers>

[0178] Then, in this step, ultrafine fibers having an average single fiber diameter of 0.1 μm or more and 10.0 μm or less are emerged from the aforementioned composite fiber entanglement to form a fiber entanglement.

[0179] In this embodiment, the ultrafine fibers used in the development treatment do not require the use of an organic solvent. More specifically, if the readily soluble polymer is polylactic acid or a copolyester, this can be achieved by immersing the composite fiber entanglement obtained from the ultrafine fiber-developing fibers in an alkaline aqueous solution to dissolve and remove the readily soluble polymer of the ultrafine fiber-developing fibers. A sodium hydroxide aqueous solution is preferably used as the alkaline aqueous solution because it facilitates the treatment of salts generated by neutralization during wastewater treatment.

[0180] <Step of Imparting a Polymer Elastomer>

[0181] Furthermore, in this step, a polymeric elastic body is provided to the composite fiber entangled body or the fiber entangled body. Specifically, a step of providing the polymeric elastic body by impregnating the composite fiber entangled body or the fiber entangled body with a solution of the polymeric elastic body and curing the solution is more preferred.

[0182] As methods for fixing the polymer elastomer to the composite fiber entanglement or fiber entanglement, there are wet coagulation methods in which a solution of the polymer elastomer is impregnated into the fiber entanglement and then immersed in a coagulation bath for fixing, or dry coagulation methods in which the fiber entanglement is dried and fixed. These methods can be appropriately selected according to the type of polymer elastomer to be applied.

[0183] Preferred solvents for imparting polyurethane as a polymeric elastic body include N,N'-dimethylformamide, dimethyl sulfoxide, and aqueous polyurethane dispersions prepared by dispersing polyurethane in water as an emulsion. Among these, aqueous polyurethane dispersions are preferred from an environmental perspective.

[0184] It should be noted that, here, the process of imparting a polymer elastomer to the aforementioned fiber entanglement is described after the process of making the aforementioned ultrafine fibers appear and forming a fiber entanglement, but the polymer elastomer can also be imparted to the aforementioned composite fiber entanglement after the process of forming the aforementioned composite fiber entanglement and before making the ultrafine fibers appear.

[0185] <Other finishing processes>

[0186] In the method for producing artificial leather of the present embodiment, it is also preferable to perform various finishing steps similarly to ordinary artificial leather.

[0187] First, the manufacture method of the artificial leather of the present embodiment preferably comprises a dyeing process in which the artificial leather is dyed. As this dyeing process, the various methods commonly used in the art can be adopted, for example, an immersion process such as a liquid flow dyeing process using a jigger or a liquid flow dyeing machine, a thermosol dyeing process using a continuous dyeing machine, or a printing process such as a drum printing and dyeing process, a screen printing and dyeing process, an inkjet printing and dyeing process, a sublimation printing and dyeing process, and a vacuum sublimation printing and dyeing process on the pile surface can be used. Wherein, because it is possible to impart a rubbing effect while dyeing the unhaired artificial leather or artificial leather and soften the unhaired artificial leather or artificial leather, a liquid flow dyeing machine is preferably used. In addition, as required, various resin finishing processes can be implemented after dyeing.

[0188] Furthermore, a finishing treatment can be applied in the same bath as dyeing or after dyeing. For example, a softener such as silicone, an antistatic agent, a water repellent, a flame retardant, a light stabilizer, an antibacterial agent, and the like can be used in the finishing treatment.

[0189] In this embodiment, from the viewpoint of production efficiency, half-cutting in the thickness direction is also a preferred embodiment regardless of whether it is before or after the dyeing step.

[0190] The method for producing artificial leather of this embodiment preferably includes a raising step, either before or after the dyeing step. The method for forming the pile is not particularly limited, and various methods commonly used in the art, such as polishing with sandpaper, etc., can be used. The raising treatment may be applied to only one side of the artificial leather or to both sides.

[0191] When performing a napping treatment, a lubricant such as a silicone emulsion can be applied to the surface of the artificial leather before the napping treatment. Furthermore, by applying an antistatic agent before the napping treatment, grinding dust generated from the artificial leather during grinding is less likely to accumulate on the sandpaper. This is how artificial leather is formed.

[0192] Furthermore, in the method for producing artificial leather of the present embodiment, the artificial leather may be subjected to post-processing such as perforation or other hole-forming processing, embossing, laser processing, ultrasonic thermal bonding, and printing, as needed.

[0193] The artificial leather of this embodiment obtained by the manufacturing method exemplified above has a dense and beautiful surface quality, excellent moldability and wear resistance, and can therefore be used in a wide range of applications such as automotive interior materials, interior decoration, consumer electronics, clothing, and bags.

[0194] For example, an automotive interior material comprising the aforementioned artificial leather has a dense and beautiful surface quality, and can exhibit excellent properties such as moldability and wear resistance, and is therefore preferred. Such automotive interior materials are preferably used in automotive parts such as steering wheels, horn switches, shift knobs, dashboards, instrument panels, glove boxes, floor carpets, floor mats, roof linings, sun visors, and auxiliary handles, and more preferably, at least a portion of these automotive parts is the aforementioned artificial leather. It should be noted that the "automobile" in this embodiment is not limited to so-called conventional passenger cars, but also includes industrial machinery, construction machinery, and agricultural machinery that can carry people and animals and move, such as excavators, cranes, tractors, and combine harvesters.

[0195] In addition, clothing materials containing the above-mentioned artificial leather also have a dense and beautiful surface quality, and can demonstrate excellent properties such as moldability and wear resistance, and are therefore also preferred. Such clothing materials can be preferably used for clothing materials such as T-shirts, polo shirts, shirts, blouses, cashmere sweaters, cut-and-sew clothing, sweaters, vests, hoodies, sweatshirts, turtlenecks, cardigans, camisoles, and tube tops, coats, blazers, jackets, windbreakers, capes, cloaks, aprons, and sleeveless coats, trousers such as casual pants, jeans, and shorts, skirts, formal dresses such as cocktail dresses, dresses, and robes, ceremonial clothing, suits, uniforms, underwear, and accessories such as hats, belts, scarves, and ties, as well as clothing materials such as buttons and pockets, accessories, and linings of the above-mentioned clothing products.

[0196] Example

[0197] Next, the artificial leather of the present invention will be described in more detail using examples, but the present invention is not limited to these examples.

[0198] [Measurement method]

[0199] The evaluation methods and measurement conditions used in the examples are described below. However, unless otherwise specified, the measurements of various physical properties were performed according to the above-described methods.

[0200] A. Average single fiber diameter of ultrafine fibers:

[0201] In the measurement of the average single fiber diameter of the ultrafine fibers, the ultrafine fibers were observed using a digital microscope "VHX-D500 / D510" manufactured by KEYENCE CORPORATION, and the average single fiber diameter was calculated.

[0202] B. Molecular orientation in ultrafine fibers

[0203] The molecular orientation degree in the ultrafine fibers was measured using a laser Raman spectrometer "Ramanor T64000" manufactured by Jobin Yvon under the following conditions.

[0204] ·Measurement mode: Micro Raman

[0205] Objective lens: ×100

[0206] Beam spot diameter: 1μm

[0207] Light source: Ar+ laser / 514.5nm

[0208] Laser power: 50mW

[0209] Diffraction grating: Spectrograph 1800gr / mm

[0210] Slit: 100μm

[0211] Detector: CCD (Jobin Yvon) 1024×256

[0212] C. Crystallization orientation of ultrafine fibers:

[0213] The crystal orientation degree of the ultrafine fibers was measured using an X-ray generator "SmartLab" manufactured by Rigaku Corporation under the following conditions.

[0214] X-ray generator: SmartLab (sealed tube type)

[0215] X-ray source: CuKα line (using Ni filter)

[0216] Output power: 40kV 50mA

[0217] Detector: D / teX one-dimensional detector

[0218] ·Receiving slit: 2.5°

[0219] Scanning mode: β continuous scanning

[0220] Entrance slit: 0.5mmh×0.55mmw

[0221] Light receiving slit: 5mm-5mm

[0222] Measuring range (β): 90°~270°

[0223] ·Measurement step (β): 0.5°

[0224] Scanning speed: 15° / min

[0225] Diffraction peaks: (010) plane 2θ = about 17°, (100) plane 2θ = about 25°

[0226] D. Crystallite size of ultrafine fibers:

[0227] The crystallite size of the ultrafine fibers was measured using an X-ray generator "SmartLab" manufactured by Rigaku Corporation under the following conditions.

[0228] X-ray generator: SmartLab (sealed tube type)

[0229] X-ray source: CuKα ray (using Ni filter)

[0230] Output power: 40kV 50mA

[0231] Detector: D / teX one-dimensional detector

[0232] ·Receiving slit: 2.5°

[0233] Scanning mode: 2θ-θ continuous scanning

[0234] Entrance slit: 0.5mmh×0.55mmw

[0235] Light receiving slit: 15mm-20mm

[0236] Measuring range (2θ): 5°~60°

[0237] ·Measurement step (2θ): 0.02°

[0238] Scanning speed: 1.5° / min

[0239] Measurement direction: Equator

[0240] E. Wear loss of artificial leather (wear resistance):

[0241] A Martindale abrasion tester, Model 406 manufactured by James H. Heal & Co., was used, and the company's Abrasive Cloth SM25 was used as the standard rubbing cloth. A load of 12.0 kPa was applied to the artificial leather, and the number of abrasions was set to 50,000. The weight loss from abrasion was calculated using the following formula using the weights of the artificial leather before and after abrasion:

[0242] Wear loss (mg) = mass before wear (mg) - mass after wear (mg)

[0243] The wear loss (mg) is obtained by rounding off the first decimal place, and artificial leather having a wear loss of 30 mg or less is considered acceptable.

[0244] F. The touch of artificial leather:

[0245] Ten healthy adult males and ten healthy adult females, for a total of 20 evaluators, were used to evaluate the following evaluations using their sense of touch. The highest number of evaluations was used as the feel of the artificial leather. It should be noted that if the number of evaluations was the same, the higher number was used as the feel of the artificial leather. In this embodiment, a good level was "A or B."

[0246] A: Very smooth touch.

[0247] B: Smooth touch.

[0248] C: Rough touch.

[0249] D: Very rough touch.

[0250] G. Surface quality of artificial leather:

[0251] Ten healthy adult males and ten healthy adult females, for a total of 20 evaluators, were used to visually evaluate the following evaluations. The highest number of evaluations was used as the surface quality of the artificial leather. It should be noted that if the number of evaluations was the same, the higher number was used as the surface quality of the artificial leather. In this embodiment, a good level is "A or B."

[0252] A: Dense and very good surface quality

[0253] B: dense and good surface quality

[0254] C: Lack of density, poor surface quality

[0255] D: Lack of density, very poor surface quality.

[0256] [Copolyester]

[0257] The copolyesters used in Examples and Comparative Examples are as follows.

[0258] Copolymerized PET-A: A copolyester obtained by copolymerizing 8 mol% of 5-sodium sulfoisophthalate and 9 mass% of polyethylene glycol having a number average molecular weight of 1000.

[0259] Copolymer PET-B: A copolyester obtained by copolymerizing 8 mol% of 5-sodium sulfoisophthalate and 9 mass% of polyethylene glycol having a number average molecular weight of 3,000.

[0260] Copolymerized PET-C: A copolyester obtained by copolymerizing 6 mol% of 5-sodium sulfoisophthalate and 9 mass% of polyethylene glycol having a number average molecular weight of 2000.

[0261] Copolymerized PET-D: a copolyester copolymerized with 8 mol % of 5-sodium sulfoisophthalate (a copolyester not copolymerized with polyethylene glycol).

[0262] Copolymerized PET-E: A copolyester obtained by copolymerizing 8 mol% of 5-sodium sulfoisophthalate and 9 mass% of polyethylene glycol having a number average molecular weight of 10,000.

[0263] [Example 1]

[0264] (Step of Obtaining a Stretched Composite Fiber)

[0265] As the poorly soluble polymer (island component), polyethylene terephthalate (abbreviated as "PET" in Tables 1 and 2) with an intrinsic viscosity of 0.73 was used, and as the readily soluble polymer (sea component), a copolyester copolymer "PET-A" was used. Using a sea-island type composite spinneret with 16 islands / hole, melt spinning was performed at a spinning temperature of 285°C, a poorly soluble polymer / readily soluble polymer mass ratio of 80 / 20, a discharge rate of 1.6 g / min / hole, and a spinning speed of 1100 m / min. The fibers were then stretched to 3.8 times in an oil bath at 65°C to produce stretched composite fibers.

[0266] (Step of Obtaining Crimped Conjugated Fiber)

[0267] The stretched conjugated fiber was heated so that its surface temperature reached 45° C. Then, the stretched conjugated fiber after the heat treatment was crimped using a press-type crimper to obtain a crimped conjugated fiber.

[0268] (Step of forming a composite fiber entanglement)

[0269] The crimped composite fiber was cut into 51 mm lengths to obtain raw cotton of island-in-sea composite fiber (crimped composite fiber) with a single fiber fineness of 4.4 dtex. Next, the raw cotton was used to form a fiber web through carding and cross-lapping, and then 3500 fibers / cm 2 The fiber web was needle-punched with a number of needle punches to entangle it, thereby obtaining a fiber web having a weight per unit area of ​​650 g / m 2 , and the thickness is 2.5mm, the apparent density is 0.26g / cm 3 Composite fiber entanglement.

[0270] The composite fiber entangled body obtained as described above was immersed in hot water at a temperature of 98° C. for 2 minutes to perform a shrinkage treatment.

[0271] (Step of imparting a polymer elastic body)

[0272] An aqueous dispersion was prepared consisting of 11 parts by mass of a polyurethane precursor (composed of polytetramethylene glycol as a high molecular weight polyol, MDI as an organic diisocyanate, 2,2-dimethylolpropionic acid as a compound containing a hydrophilic group and an active hydrogen component, and ethylene glycol as a chain extender), 1 part by mass of a carbodiimide-based crosslinking agent, 5 parts by mass of sodium sulfate, and 83 parts by mass of water. This aqueous dispersion was then impregnated into the aforementioned shrunk composite fiber entanglement, squeezed with a nip roll, and dried with hot air at 120°C for 20 minutes to coagulate the polyurethane precursor and cure the polyurethane, thereby obtaining a polyurethane sheet having a crosslinked structure composed of N-acylurea bonds and / or isourea bonds.

[0273] (Step of developing ultrafine fibers to form a fiber entanglement)

[0274] The polyurethane-coated sheet was immersed in a 5% sodium hydroxide aqueous solution and then heat-treated with 95°C steam for 10 minutes to alkali-decompose the sea component of the island-in-the-sea composite fibers. The remaining sodium hydroxide and sodium sulfate were then washed with water and dried in a drier at 160°C for 10 minutes to obtain a fiber entanglement comprising ultrafine fibers coated with polyurethane.

[0275] (Other finishing processes)

[0276] The fiber entanglement obtained from the above-mentioned ultrafine fibers endowed with polyurethane is half-cut in a direction perpendicular to the thickness direction, and then the surface opposite to the half-cut surface (non-half-cut surface) is ground and raised with circular sandpaper of sandpaper model No. 120 to obtain a velvet sheet with a thickness of 0.70 mm.

[0277] The pile sheet obtained in the above manner was dyed using a liquid jet dyeing machine at a temperature of 120°C and then dried in a dryer to obtain artificial leather. The results are shown in Table 1. The obtained artificial leather had a dense and beautiful surface quality, good touch, and excellent abrasion resistance.

[0278] [Example 2]

[0279] Artificial leather was obtained in the same manner as in Example 1, except that the stretched conjugated fiber was heated at 70°C, instead of heating at 45°C in the aforementioned step (obtaining crimped conjugated fibers). The results are shown in Table 1. The obtained artificial leather had a dense and beautiful surface quality, a good feel, and excellent abrasion resistance.

[0280] [Example 3]

[0281] Artificial leather was obtained in the same manner as in Example 1, except that "copolymerized PET-B" was used instead of "copolymerized PET-A" as the sea component in the aforementioned step (obtaining the drawn conjugated fiber). The results are shown in Table 1. The obtained artificial leather had a dense and beautiful surface quality, a good touch, and excellent abrasion resistance.

[0282] [Example 4]

[0283] Artificial leather was obtained in the same manner as in Example 3, except that the stretched conjugated fiber was heated at 70°C, instead of heating at 45°C in the aforementioned step (obtaining crimped conjugated fibers). The results are shown in Table 1. The obtained artificial leather had a dense and elegant surface quality, a good feel, and excellent abrasion resistance.

[0284] [Example 5]

[0285] Artificial leather was obtained in the same manner as in Example 1, except that "co-PET-C" was used instead of "co-PET-A" as the sea component in the aforementioned step (obtaining the drawn conjugate fiber). The results are shown in Table 1. The obtained artificial leather had a dense and beautiful surface quality, a good touch, and excellent abrasion resistance.

[0286] [Example 6]

[0287] Artificial leather was obtained in the same manner as in Example 5, except that in the aforementioned (step of obtaining a drawn conjugated fiber), the drawing temperature was changed from 65°C to 75°C, and in the aforementioned (step of obtaining a crimped conjugated fiber), the heating of the drawn conjugated fiber at a surface temperature of 45°C was changed to 70°C. The results are shown in Table 1. The obtained artificial leather had a dense and beautiful surface quality, good tactility, and excellent abrasion resistance.

[0288] [Example 7]

[0289] Artificial leather was obtained in the same manner as in Example 1, except that the stretching was performed at a draw ratio of 2.1 times, rather than at a draw ratio of 3.8 times in the aforementioned step (obtaining a drawn conjugated fiber). The results are shown in Table 1. Although the obtained artificial leather had slightly inferior abrasion resistance to the artificial leather in Example 1, it had a dense and beautiful surface quality and a good feel.

[0290] [Example 8]

[0291] Artificial leather was obtained in the same manner as in Example 1, except that the spinning speed in the aforementioned (step of obtaining a drawn conjugated fiber) was changed from 1100 m / min to 3000 m / min, the stretching temperature was changed from 65°C to 80°C, and the surface temperature of the drawn conjugated fiber was heated at 80°C instead of 45°C in the aforementioned (step of obtaining a crimped conjugated fiber). The results are shown in Table 1. The obtained artificial leather had superior abrasion resistance, although its surface quality and feel were slightly inferior to those of the artificial leather in Example 1.

[0292] [Example 9]

[0293] Artificial leather was obtained in the same manner as in Example 1, except that the sandpaper used in the aforementioned (other finishing steps) was changed from No. 120 to No. 180. The results are shown in Table 1. Although the obtained artificial leather had a slightly inferior feel to the artificial leather in Example 1, it had a dense and beautiful surface quality and excellent abrasion resistance.

[0294] [Table 1]

[0295]

[0296] [Comparative Example 1]

[0297] Artificial leather was obtained in the same manner as in Example 1, except that "co-PET-D" was used instead of "co-PET-A" as the sea component in the aforementioned step (obtaining the drawn conjugate fiber). The results are shown in Table 2. The obtained artificial leather had a dense and beautiful surface quality and a good feel, but its abrasion resistance was inferior to that of the artificial leather in Example 1.

[0298] [Comparative Example 2]

[0299] Artificial leather was obtained in the same manner as in Example 1, except that "co-PET-E" was used instead of "co-PET-A" as the sea component in the aforementioned step (obtaining a drawn conjugated fiber). The results are shown in Table 2. While the obtained artificial leather had a dense and beautiful surface quality and excellent abrasion resistance, it had a poorer feel than the artificial leather of Example 1.

[0300] [Comparative Example 3]

[0301] Artificial leather was obtained in the same manner as in Example 1, except that the stretching temperature in the aforementioned (step of obtaining a drawn conjugated fiber) was changed from 65°C to 90°C, and that the surface temperature of the drawn conjugated fiber was changed from 45°C to 90°C in the aforementioned (step of obtaining a crimped conjugated fiber). However, when the drawn conjugated fiber that had undergone the (step of obtaining a drawn conjugated fiber) was attempted to be subjected to the (step of obtaining a crimped conjugated fiber), the crimping process using a press-type crimper was impossible due to the elution of the sea component, preventing the subsequent steps from proceeding. The results are shown in Table 2.

[0302] [Comparative Example 4]

[0303] Artificial leather was obtained in the same manner as in Example 1, except that, in the aforementioned step (of obtaining crimped conjugated fibers), heating was performed at a surface temperature of 45°C instead of heating the drawn conjugated fibers. Furthermore, the unheated drawn conjugated fibers were crimped directly using a press-type crimper. However, no crimping was observed in the drawn conjugated fibers, and the cut raw fibers became entangled with the drum during the carding step, preventing the subsequent steps (the step of forming a tangled conjugated fiber mass). The results are shown in Table 2.

[0304] [Table 2]

[0305]

[0306] The present invention is described in detail with reference to a specific embodiment, but those skilled in the art will appreciate that various changes and modifications may be made without departing from the spirit and scope of the present invention. It should be noted that this application is based on Japanese patent application (Japanese Patent Application No. 2023-016558) filed on February 7, 2023, which is incorporated herein by reference in its entirety. In addition, all references cited herein are incorporated as a whole.

[0307] Description of Reference Numerals

[0308] 1: Pile head

[0309] 2: Base part

[0310] L A :With bottom surface L B Parallel lines

[0311] L B :Bottom

[0312] L0: Boundary line between pile portion 1 and base portion 2

[0313] A n (n is an integer from 1 to 10): relative to the bottom surface L B perpendicular line

[0314] P n (n is an integer from 1 to 10): vertical line A n Points intersecting with boundary line L0

[0315] Q n (n is an integer from 1 to 10): vertical line A n The point where the pile portion 1 intersects with the front end

[0316] R n (n is an integer from 1 to 10): Point P n and dot Q n distance

Claims

1. Artificial leather comprising a fiber entanglement and a polymer elastomer as components, wherein the fiber entanglement is composed of ultrafine fibers containing a thermoplastic resin and having an average single fiber diameter of 0.1 μm to 10.0 μm, and the molecular orientation degree in the ultrafine fibers is 6.5 to 9.

0.

2. The artificial leather according to claim 1, wherein The thermoplastic resin is a polyester resin, and the crystal orientation degrees of the (010) plane and the (100) plane in the fiber structure are 0.80 or more and 0.95 or less.

3. The artificial leather according to claim 1 or 2, wherein The thermoplastic resin is a polyester resin, and the crystallite size of the (010) plane in the fiber structure is 2.0 nm to 5.0 nm, and the crystallite size of the (100) plane is 1.0 nm to 4.0 nm.

4. The artificial leather according to claim 1 or 2, wherein At least one surface of the artificial leather is a surface having pile, and the pile length of the surface is 200 μm or more and 500 μm or less.

5. The method for producing artificial leather according to claim 1 or 2, comprising: A step of drawing an ultrafine fiber-developing fiber composed of a highly soluble polymer and a poorly soluble polymer to obtain a drawn conjugate fiber, wherein the highly soluble polymer is a copolyester copolymerized with a polyalkylene glycol having a number average molecular weight of 500 to 3500. The step of heating the drawn conjugated fiber under conditions where the surface temperature of the drawn conjugated fiber is 40° C. or higher and 80° C. or lower, and then imparting crimps to obtain crimped conjugated fibers; a step of forming a fiber web from the crimped conjugated fibers and entangling the fiber web to form an entangled conjugated fiber body; a step of allowing ultrafine fibers having an average single fiber diameter of 0.1 μm to 10.0 μm to emerge from the composite fiber entanglement to form a fiber entanglement; and A step of adding a polymer elastic body to the composite fiber-entangled body or the fiber-entangled body.

6. An automobile interior material comprising the artificial leather according to claim 1 or 2.

7. An automobile part comprising the artificial leather according to claim 1 or 2.

8. Clothing comprising the artificial leather according to claim 1 or 2.

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