Artificial leather and its manufacturing method

Abstract

Provided is artificial leather which has excellent flexible texture, wear resistance, and nubuck outer surface having a dense feeling. The present invention relates to napped artificial leather containing an entangled sheet, and a polymer elastomer filled into the entangled sheet, the napped artificial leather being characterized in that: the entangled sheet has a structure of two or more layers formed from a fiber layer (A) on the front surface side of the napped artificial leather, and a scrim in contact with the fiber layer (A); the average diameter of the fibers constituting the fiber layer (A) is 2.0-7.0 μm; and when measuring porosity in the thickness direction and defining the minimum porosity in the fiber layer (A) as εAmin(%), the minimum porosity in the scrim as εSmin(%), and the maximum porosity from the position of the εAmin(%) to the position of the εSmin(%) as εA-Smax(%), 40≤εAmin≤70, 70≤εA-Smax≤90, and εSmin(%)<εA-Smax(%) are satisfied. The present invention also relates to a method for manufacturing the same.

Description

Technical Field

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

Background Art

[0002] Artificial leather composed mainly of a non-woven fabric formed by entangling fibers and a polymer elastomer has excellent characteristics such as easy care, functionality, and uniformity, which are difficult to achieve with natural leather. It is suitably used for clothing, shoes, bags, and further, as surface materials and interior materials for seats for interior use, automobiles, airplanes, railway vehicles, etc., clothing materials such as ribbons and emblem bases, and the like.

[0003] Among artificial leathers, suede-like artificial leather with a napped outer surface is known for its high-class appearance and touch. Furthermore, compared with general suede-like artificial leather, those with denser, shorter, and more uniform nap are called nubuck-like artificial leather from their appearance and are more preferred. In the following Patent Document 1, a woven scrim made of a heat-shrinkable polymer is used as a scrim inserted into artificial leather for the purpose of reinforcing mechanical strength. By passing through a heat-shrinking process in the manufacturing process, not only does it have a dense and high-class surface appearance, but also a method for obtaining artificial leather excellent in mechanical physical properties and morphological stability is described. In the following Patent Document 2, a method for obtaining a dense artificial leather without generating a pattern on the surface by integrating a low basis weight fiber web composed of ultrafine fibers and a knitted scrim with high heat shrinkability by multiple water flow entanglements is described. In the following Patent Document 3, a method for obtaining nubuck-like artificial leather having both a nubuck-like hairy feeling and a fine wrinkle feeling like natural leather by integrating a laminate in which fiber webs composed of ultrafine fibers with a single fiber fineness of 0.0001 to 0.004 dtex are laminated by entanglement is described.

Prior Art Documents

Patent Documents

[0004] Patent Document 1 Japanese Patent Application Laid-Open No. 2019-112744 Patent Document 2 Japanese Patent Application Laid-Open No. 2009-185430 Patent Document 3 Japanese Patent Application Laid-Open No. 2007-204863 Summary of the Invention Problems to be Solved by the Invention

[0005] However, artificial leather is also required to have a soft texture. Since the softer the texture tends to be obtained as the fiber density of artificial leather is made sparser, if the fiber density is made excessively dense in order to obtain the appearance and touch similar to those of nubuck, the texture tends to become hard, which is not preferable. In addition, artificial leather is also required to have abrasion resistance. In order to obtain the appearance and touch similar to those of nubuck, it is conceivable to reduce the diameter of the fibers constituting the non-woven fabric and make the fiber density dense. However, in order to have high abrasion resistance, it is desirable that the diameter of the fibers constituting the non-woven fabric is large. In Patent Document 1, by thermally shrinking a complex sheet including a fabric scrim made of a heat-shrinkable polymer, artificial leather with a dense whole including the outer surface is obtained. However, since the whole has a dense structure, it has a paper-like or hard texture and cannot satisfy the soft texture required for artificial leather. In Patent Document 2, by thermally shrinking a complex sheet including a knitted scrim with high heat shrinkability, artificial leather with a dense outer surface is obtained. However, since the whole has a dense structure, it has a paper-like or hard texture and cannot satisfy the soft texture required for artificial leather. In addition, since the basis weight of the fiber web is as extremely small as 10 to 25 g / m 2 it is not sufficient in abrasion resistance. In Patent Document 3, by making artificial leather a laminate including a fiber web composed of ultrafine fibers, artificial leather with a dense outer surface is obtained. However, since ultrafine fibers of 0.0001 to 0.004 dtex are used, the abrasion resistance is not sufficient.

[0006] In view of these problems of the prior art, the problem to be solved by the present invention is to provide artificial leather that is excellent in all of a dense nubuck-like outer surface, a soft texture, and abrasion resistance.

Means for Solving the Problem

[0007] As a result of intensive research and repeated experiments by the present inventors to solve the above problems, it was unexpectedly found that artificial leather having the following characteristics can solve the problem, and the present invention has been completed.

[0008] That is, the present invention is as follows. [1] A napped artificial leather comprising a complex sheet and a polymer elastomer filled in the complex sheet, wherein the complex sheet has a structure of two or more layers composed of a fiber layer (A) on the surface side of the napped artificial leather and a scrim in contact with the fiber layer (A), the average diameter of the fibers constituting the fiber layer (A) is 2.0 μm or more and 7.0 μm or less, and when measuring the porosity in the thickness direction from the surface side to the back side, the minimum porosity in the fiber layer (A) is ε Amin (%), the minimum porosity in the scrim is ε Smin (%), and the maximum porosity existing from the position of the ε Amin (%) to the position of the ε Smin (%) is ε A-Smax (%), then the following formulas (1) to (3): 40 ≦ ε Amin ≦ 70... Formula (1) 70 ≦ ε A-Smax ≦ 90... Formula (2) ε Smin < ε A-Smax ... Formula (3) The napped artificial leather is characterized by satisfying the above. [2] The artificial leather according to [1], wherein the k-nearest neighbor distance ratio value of the fiber layer (A) is 10% or more and 80% or less. [3] In the thickness direction of the fiber layer (A), when the relative position of the surface of the fiber layer (A) is 0% and the relative position of the boundary between the fiber layer (A) and the scrim is 100%, ε which is the minimum porosity in the fiber layer (A). Amin The artificial leather according to [1] or [2] above, wherein the relative position of Amin is in the range of 20% or more and 95% or less. [4] The artificial leather according to any one of [1] to [3] above, wherein the polymer elastomer is a water-dispersed polyurethane. [5] The artificial leather according to any one of [1] to [4] above, wherein the complex sheet is composed of polyester fibers. [6] The artificial leather according to any one of [1] to [5] above, wherein the complex sheet has a three-layer structure composed of a fiber layer (A), a scrim in contact with the fiber layer (A), and a fiber layer (B) in contact with the scrim. [7] The following steps: (1) A step of forming a fiber web (A') from fibers having an average diameter of 2.0 μm or more and 7.0 μm or less; (2) A step of subjecting the obtained fiber web (A') to preliminary water jet entanglement to obtain a fiber sheet (A"); (3) A step of laminating at least the fiber sheet (A") and a scrim and integrating them by main water jet entanglement to obtain a complex sheet; (4) Optionally, a step of raising the outer surface of the obtained fiber sheet; (5) A step of filling the obtained complex sheet with a polymer elastomer to obtain a sheet-like material; (6) When the step (4) is not carried out, a step of raising the outer surface of the sheet-like material obtained in the step (5), or when the step (4) is carried out, a step of further raising the outer surface of the sheet-like material; and (7) A step of dyeing the obtained sheet-like material. The method for manufacturing a raised artificial leather according to any one of [1] to [6] above, including the above steps. [8] The method according to [7] above, wherein the water pressure of the preliminary water jet entanglement in the step (2) is 2 MPa or more and 4.5 MPa or less.

Advantages of the Invention

[0009] According to the present invention, artificial leather with a dense nubuck-like outer surface, a soft texture, and excellent abrasion resistance can be produced.

Brief Description of the Drawings

[0010]

Figure 1

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Embodiments for Carrying Out the Invention

[0011] Hereinafter, embodiments of the present invention will be described in detail, but the present invention is not limited to the embodiments. Also, it is understood by those skilled in the art that various values disclosed herein are values obtained by the methods described in the sections of the examples of the present disclosure or methods equivalent thereto unless otherwise specified.

[0012] <Artificial Leather> One embodiment of the present invention is a napped artificial leather including a complex sheet and a polymer elastomer filled in the complex sheet, wherein the complex sheet has a structure of two or more layers composed of a fiber layer (A) on the surface side of the napped artificial leather and a scrim in contact with the fiber layer (A). The average diameter of the fibers constituting the fiber layer (A) is 2.0 μm or more and 7.0 μm or less, and when measuring the porosity in the thickness direction from the front surface side to the back surface side, the minimum porosity in the fiber layer (A) is ε Amin (%), the minimum porosity in the scrim is ε Smin (%), and when the maximum porosity existing from the position of the ε Amin (%) to the position of the ε Smin (%) is ε A-Smax (%), the following formulas (1) to (3): 40 ≦ ε Amin ≦ 70... Formula (1) 70 ≦ ε A-Smax ≦ 90... Formula (2) ε Smin < ε A-Smax ... Formula (3) It is characterized by satisfying the above, and it is a raised artificial leather.

[0013] In this specification, "artificial leather" means, in accordance with the Household Goods Quality Labeling Law, "using a special non-woven fabric (mainly composed of a fiber layer having a random three-dimensional structure and impregnated with a polyurethane (PU) resin or a similar flexible polymer elastomer) on a base material". Also, according to the definition of JIS-6601, artificial leather is classified into "smooth" with a silver surface-like appearance of leather and "nap" with an appearance such as nubuck, suede, or velour of leather depending on its appearance. However, the artificial leather of this embodiment relates to the one classified as "nap" (that is, a raised artificial leather having a raised appearance). The raised appearance can be formed by buffing (raising treatment) the outer surface (also referred to as the front (omote) surface) of the fiber layer (A) with sandpaper or the like. Note that in this specification, the outer surface of the artificial leather, the outer surface of the fiber layer (A), the outer surface of the fiber sheet, and the outer surface of the laminated sheet are the surfaces that are exposed to the outside when used as artificial leather (for example, in the case of chair use, the surface that comes into contact with the human body). In one aspect, in the case of the raised artificial leather, the outer surface of the fiber layer (A) is raised or fluffed by buffing or the like.

[0014] Artificial leather has at least a two-layer or more structure composed of a fiber layer (A) and a scrim in contact with the fiber layer (A). By having a two-layer or more structure including a scrim, the mechanical properties of the artificial leather, particularly the tear strength and tensile strength, can be enhanced. The artificial leather may, for example, be composed of three layers including a fiber layer (B) constituting the back surface in addition to the fiber layer (A) and the scrim. If it has a three-layer structure of the fiber layer (A), the fiber layer (B), and the scrim sandwiched therebetween, the fiber layer (A) and the fiber layer (B) can be designed individually, so the diameter, type, etc. of the fibers constituting these layers can be freely customized according to the functions and uses required for the artificial leather using an entangled sheet, which is preferable. For example, if ultrafine fibers are used for the fiber layer (A) and flame-retardant fibers are used for the fiber layer (B) respectively, excellent surface quality and high flame retardancy can be achieved simultaneously. Also, making it a three-layer structure of the fiber layer (A), the fiber layer (B), and the scrim sandwiched therebetween is also preferable in that the entanglement strength between the fiber layer (A) and the scrim tends to be high.

[0015] [Minimum porosity ε in the scrim Smin As shown in FIG. 2, the minimum porosity ε in the scrim Smin is the porosity of the maximum concave peak within the scrim structure range in the porosity distribution of the artificial leather. The porosity distribution of the artificial leather is calculated by analysis using CT scan (described later). The scrim structure range of the artificial leather is determined from the SEM image of the cross-section in the thickness direction of the artificial leather (described later). The minimum porosity ε in the scrim Smin (%) is less than ε A-Smax (%). ε Smin +5 ≤ ε A-Smax is preferable, and more preferably ε Smin +10 ≤ ε A-Smax .

[0016] [Minimum porosity ε in the fiber layer (A) Amin The minimum porosity ε in the thickness direction of the fiber layer (A) Amin is 40% or more and 70% or less. ε Amin means, as shown in FIG. 2, the minimum porosity ε in the scrim Smin ​​is the porosity of the maximum concave peak in the range from the peak to the outer surface on the side of the fiber layer (A). The presence of the concave peak enables sufficient entanglement of the fibers within the fiber layer (A), thereby improving the abrasion resistance. Furthermore, when Amin ε is 40% or more, appropriate voids are formed between the fibers constituting the fiber layer (A), and the artificial leather has a soft texture. Also, when Amin ε is 70% or less, the fiber layer (A) becomes dense, and the texture when touched has a dense feeling like that of nubuck. ε Amin is preferably 50% or more and 70% or less, more preferably 60% or more and 70% or less.

[0017] [Minimum porosity ε in the fiber layer (A) Amin Relative position] In the thickness direction of the fiber layer (A), when the relative position of the surface of the fiber layer (A) is 0% and the relative position of the boundary between the fiber layer (A) and the scrim is 100%, the relative position of the minimum porosity ε Amin in the fiber layer (A) is preferably in the range of 20% or more and 95% or less. The relative position of ε Amin in the fiber layer (A) of the artificial leather is determined from the cross-sectional SEM image and three-dimensional image of the artificial leather (described later). The relative position can be adjusted by the energy (water pressure) applied as water flow to the fiber web (A′) or the laminated sheet in the water entanglement process. When the relative position is 20% or more, the fiber layer and the scrim are more integrally entangled, and peeling between the fiber layer (A) and the scrim is less likely to occur. Also, when the relative position is 95% or less, the texture of the artificial leather is likely to become soft. The relative position is more preferably 35% or more and 90% or less, even more preferably 50% or more and 85% or less.

[0018] [Maximum porosity ε Smin existing from ε Amin to ε A-Smax ε Smin from ε Amin to ε A-Smax (ε Amin (%) position to ε Smin(%) The maximum porosity (%) existing up to the position of (%) is the porosity of the maximum convex peak existing from ε within the scrim structure range to ε within the fiber layer (A) in the porosity distribution of the artificial leather. The ε Smin to ε within the fiber layer (A) Amin is the porosity of the maximum convex peak existing up to. The ε A-Smax is 70% or more and 90% or less. Since the ε A-Smax is 70% or more, an appropriate gap is formed between the fiber layer (A) and the scrim, and the artificial leather has a soft texture. Also, since the ε A-Smax is 90% or less, there is a sufficient amount of fibers that grip the fiber layer (A) and the scrim, and the artificial leather has sufficient abrasion resistance for use as a skin material for automotive interior materials and the like. The ε A-Smax is preferably 70% or more and 85% or less, more preferably 70% or more and 80% or less.

[0019] [Fibers constituting the fiber layer] As the fibers constituting the fiber layer (fiber layer (A) and fiber layer (B) and additional layers as optional layers) constituting the artificial leather, polyester fibers such as polyethylene terephthalate, polybutylene terephthalate, and polytrimethylene terephthalate; polyamide fibers such as nylon 6, nylon 66, and nylon 12; and the like are suitable synthetic fibers. Among them, considering applications that require durability such as the car seat field, polyethylene terephthalate is preferable in that the fiber itself does not turn yellow or the like even when exposed to direct sunlight for a long time and has excellent color fastness. Also, from the viewpoint of reducing the environmental load, polyethylene terephthalate that has been chemically recycled or material recycled, or polyethylene terephthalate using plant-derived raw materials is even more preferable.

[0020] The average diameter of the fibers constituting the fiber layer (A) of the artificial leather is 2.0 μm or more and 7.0 μm or less. Since an appropriate gap is formed between the fibers constituting the fiber layer (A) of the artificial leather when the average diameter is 2.0 μm or more, the ε Amin tends to be 60% or more. In addition, since an appropriate gap is formed between the fibers constituting the fiber layer (A) and the scrim through the present water flow entanglement process (described later), the ε A-Smaxis likely to be 70% or more. Also, since the average diameter is 7.0 μm or less, the fibers constituting the fiber layer (A) of the artificial leather are more densely intertwined, so ε Amin is likely to be 70% or less. In addition, since the fibers and the scrim constituting the fiber layer (A) are more densely intertwined through the present water flow intertwining step (described later), ε A-Smax is likely to be 80% or less. The average diameter of the fibers constituting the fiber layer (A) of the artificial leather is preferably 3.0 μm or more and 6.0 μm or less, more preferably 3.0 μm or more and 5.0 μm or less.

[0021] As the fibers serving as the raw material of the fiber web constituting the fiber layer (fiber layer (A), any fiber layer (B), additional fiber layer, etc.) of the artificial leather, directly spun fibers and ultrafine fibers taken out from ultrafine fiber-expressing fibers are preferable. By using directly spun fibers and ultrafine fibers taken out from ultrafine fiber-expressing fibers, the fibers in the fiber layer constituting the artificial leather are likely to be single fiber-dispersed.

[0022] At least in the fiber layer (A), it is preferable that the fibers are single fiber-dispersed. For example, fibers obtained by using ultrafine fiber-expressing fibers such as sea-island type composite fibers (for example, those using copolymerized polyester as the sea component and regular polyester as the island component) and performing fibrillation treatment (removing the sea component of the sea-island type composite fiber by dissolution, decomposition, etc.) after forming a complex sheet with the scrim will exist as fiber bundles in the fiber layer (A) and are not single fiber-dispersed. As an example, a sea-island type composite short fiber with an island component equivalent to a single fiber fineness of 0.2 dtex and 24 islands / 1f is produced, the fiber layer (A) is formed with the sea-island type composite short fiber, a complex sheet with the scrim is formed by needle punching treatment or the like, the three-dimensional complex is filled with a PU resin, and then the sea component is dissolved or decomposed to obtain fibers with a single fiber fineness equivalent to 0.2 dtex. In this case, it will exist in the fiber layer (A) in a state of a fiber bundle in which 24 single fibers are converged (in the converged state, it is equivalent to 4.8 dtex).

[0023] In this specification, when fibers are "dispersed as single fibers", it means that the fibers do not form a fiber bundle obtained, for example, by removing the sea component of a sea-island type composite fiber by dissolution, decomposition, or the like. When the fiber layer (A) is composed of fibers dispersed as single fibers, it has excellent surface smoothness. For example, when the outer surface of the fiber layer (A) is raised by buffing or the like, uniform raising is easily obtained, and even when the adhesion rate of the PU resin is relatively low, it is difficult to generate a fuzz-like appearance called pilling due to friction. Therefore, an artificial leather having better surface quality and wear resistance can be obtained. Further, when the fibers are dispersed as single fibers, since the fiber intervals are likely to be narrow and uniform, good wear resistance can be obtained even if the PU resin adheres in a fine form. Examples of the method for dispersing the fibers as single fibers include a method of forming a fiber web from ultrafine fibers produced by the direct spinning method by means of a papermaking method, and a method of promoting the fibrillation of a fiber bundle by subjecting the sea component of a fiber sheet or a complex sheet made of a sea-island type composite fiber to dissolution or decomposition to generate an ultrafine fiber bundle and then performing a water flow dispersion treatment on the fiber bundle surface. Among the fiber layers constituting the complex sheet, in the fiber layers other than the fiber layer (A), the fibers may or may not be dispersed as single fibers, but in a preferred embodiment, the layers other than the fiber layer (A) are also composed of fibers dispersed as single fibers. From the viewpoint of making the thickness of the artificial leather using the complex sheet uniform, improving the processing accuracy, and stabilizing the quality, it is preferable that the fibers constituting the layers other than the fiber layer (A) are dispersed as single fibers.

[0024] When the complex sheet is composed of two layers, namely, the fiber layer (A) and a scrim, the basis weight of the fiber web (A') constituting the fiber layer (A) is preferably 10 g / m 2 or more and 200 g / m 2 or less, more preferably 30 g / m 2 or more and 170 g / m 2 or less, and even more preferably 60 g / m 2 or more and 170 g / m 2 or less, from the viewpoint of mechanical strength such as wear resistance. The basis weight of the scrim is preferably 20 g / m 2 or more and 150 g / m2 More preferably, it is 20 g / m or more 2 and 130 g / m or less 2 More preferably, it is 30 g / m or more 2 and 110 g / m or less 2 The basis weight of the artificial leather impregnated with the PU resin in the complex sheet composed of the fiber layer (A) and the scrim is preferably 50 g / m or more 2 and 550 g / m or less 2 More preferably, it is 60 g / m or more 2 and 400 g / m or less 2 More preferably, it is 70 g / m or more 2 and 350 g / m or less 2 and is as follows.

[0025] When the complex sheet is composed of a three-layer structure of a fiber layer (A), a scrim, and a fiber layer (B), the basis weight of the fiber web (A') constituting the fiber layer (A) is preferably 10 g / m or more from the viewpoint of mechanical strength such as abrasion resistance 2 and 200 g / m or less 2 More preferably, it is 30 g / m or more 2 and 170 g / m or less 2 More preferably, it is 60 g / m or more 2 and 170 g / m or less 2 and is as follows. Also, the basis weight of the fiber web (B') constituting the fiber layer (B) is preferably 10 g / m or more from the viewpoints of cost and ease of manufacture 2 and 200 g / m or less 2 More preferably, it is 20 g / m or more 2 and 170 g / m or less 2 and can be 43 or less. The basis weight of the scrim is preferably 20 g / m or more from the viewpoints of mechanical strength and entanglement between the fiber layer and the scrim 2 and 150 g / m or less 2 More preferably, it is 20 g / m or more 2 and 130 g / m or less 2 More preferably, it is 30 g / m or more 2 and 110 g / m or less 2 and is as follows. The basis weight of the artificial leather impregnated with the PU resin in the complex sheet composed of the fiber layer (A), the scrim, and the fiber layer (B) is preferably 60 g / m or more 2 and 750 g / m or less2 Hereinafter, more preferably 80 g / m 2 or more and 570 g / m 2 or less, even more preferably 70 g / m 2 or more and 520 g / m 2 or less.

[0026] [k-nearest neighbor distance ratio value] The k-nearest neighbor distance ratio value (k = 9, radius r = 20 μm) between the single fiber cross-sections constituting the fiber layer (A) in the thickness direction cross-section of the artificial leather is preferably 10% or more and 80% or less. The k-nearest neighbor distance ratio value (k = 9, radius r = 20 μm) indicates the degree of denseness of the single fibers. The measurement method will be described later. The k-nearest neighbor method is a method of picking up k single fiber cross-sections close to any one single fiber cross-section and determining the radius of the k-th nearest one in the Euclidean distance as the determination boundary. In this embodiment, an SEM image is taken, and it is determined whether there is a single fiber cross-section that is the 9th nearest within a distance of 20 μm from the approximate center of any one single fiber cross-section. For all single fiber cross-sections in one SEM image, the presence or absence of such is determined, and the single fiber cross-section k = 9 nearest neighbor distance ratio value (%) is obtained by the following formula: Single fiber cross-section (k = 9) nearest neighbor distance ratio value (%) = {(Number of single fiber cross-sections where there is a single fiber cross-section that is the 9th nearest within a distance of 20 μm from the approximate center of the single fiber cross-section) / (Total number of single fiber cross-sections in one SEM image)} × 100. If the k-nearest neighbor distance ratio value (k = 9, radius r = 20 μm) between the single fiber cross-sections constituting the fiber layer (A) in the thickness direction cross-section of the artificial leather is 10% or more, the single fibers exist in a state of being moderately aggregated, the fibers on the outer surface of the artificial leather become dense, and it is easy to obtain artificial leather with a nubuck-like appearance. On the other hand, if the k-nearest neighbor distance ratio value (k = 9, radius r = 20 μm) is 80% or less, the single fibers are moderately dispersed and the fibers are sufficiently intertwined, so it is easy to obtain sufficient abrasion resistance. The k-nearest neighbor distance ratio value (k = 9, radius r = 20 μm) is more preferably 20% or more and 70% or less, and even more preferably 30% or more and 60% or less.

[0027] [Scrim] The scrim can be, for example, a knitted or woven fabric, and from the viewpoint of color uniformity by dyeing, it is preferably composed of fibers of the same polymer system as the fibers constituting the fiber layer (A). For example, if the fibers constituting the fiber layer (A) are polyester-based, the fibers constituting the scrim are also preferably polyester-based. If the fibers constituting the fiber layer (A) are polyamide-based, the fibers constituting the scrim are also preferably polyamide-based. In the case of a knitted scrim, a single knit knitted at 22 gauge or more and 28 gauge or less is preferred. When the scrim is a woven fabric, higher dimensional stability and strength than those of a knitted fabric can be achieved. The weave of the woven fabric may be plain weave, twill weave, damask weave, etc., but plain weave is preferred from the viewpoints of cost and process aspects such as entangling property. The yarns constituting the woven fabric may be monofilaments or multifilaments. The single fiber fineness of the yarns is preferably 5.5 dtex or less in terms of easily obtaining a flexible artificial leather using an entangling sheet. As the form of the yarns constituting the woven fabric, raw multifilament yarns such as polyester and polyamide, or processed yarns subjected to false twisting are preferably twisted at a twist number of 0 to 3000 T / m. The multifilament may be a normal one. For example, 33 dtex / 6f, 55 dtex / 24f, 83 dtex / 36f, 83 dtex / 72f, 110 dtex / 36f, 110 dtex / 48f, 167 dtex / 36f, 166 dtex / 48f, etc. of polyester, polyamide, etc. are preferably used. The yarns constituting the woven fabric may be multifilament long fibers. The fabric density of the yarns in the woven fabric is preferably 30 threads / inch or more and 150 threads / inch or less, more preferably 40 threads / inch or more and 100 threads / inch or less, in terms of obtaining a flexible and mechanically strong artificial leather. 2 or more and 150 g / m 2 or less. Incidentally, the presence or absence of false twisting, the twist number, the single fiber fineness of the multifilament, the fabric density, etc. in the woven fabric contribute not only to the entangling property with the constituent fibers of the fiber layer (A) and the flexibility of the artificial leather, but also to the mechanical properties such as seam strength, tear strength, tensile strength and elongation, and stretchability. Therefore, they may be appropriately selected according to the target physical properties and uses.

[0028] [Polymer elastomer] The polymer elastomer constituting the artificial leather is preferably a polyurethane (PU) resin. Also, the PU resin can be used in the form of a solvent-type PU resin obtained by dissolving the PU resin in an organic solvent such as N,N-dimethylformamide, or a water-dispersed PU resin obtained by emulsifying the PU resin with an emulsifier and dispersing it in water. However, in this embodiment, the water-dispersed PU resin is preferred because it is easy to fill the complex sheet in a fine form, and it is easy to obtain the required performance as artificial leather such as texture and mechanical properties even with a small amount of adhesion, and there is no need to use an organic solvent, thus reducing the environmental load. That is, since the water-dispersed PU resin can be impregnated into the complex sheet in the form of a dispersion in which the PU resin is dispersed with a desired particle size, the filling form of the PU resin in the complex sheet can be well controlled by controlling the particle size. As the water-dispersed PU resin, a self-emulsifying type PU resin containing a hydrophilic group in the PU molecule, a forced emulsifying type PU resin obtained by emulsifying the PU resin with an external emulsifier, etc. can be used. A crosslinking agent can be used in combination with the water-dispersed PU resin for the purpose of improving durability such as wet heat resistance, abrasion resistance, and hydrolysis resistance. In order to improve the durability during liquid flow dyeing processing, suppress the shedding of fibers, and obtain excellent surface quality, it is preferable to add a crosslinking agent. The crosslinking agent may be an external crosslinking agent added as an additive component to the PU resin, or an internal crosslinking agent that introduces a reactive group capable of adopting a crosslinked structure in advance in the PU resin structure. The water-dispersed PU resin used for artificial leather generally has a crosslinked structure to provide dyeing processing resistance, and thus tends to be insoluble in organic solvents such as N,N-dimethylformamide. Therefore, for example, when the artificial leather is immersed in N,N-dimethylformamide at room temperature for 12 hours for dissolution treatment of the PU resin, and then the cross section is observed with an electron microscope or the like, if a resinous substance having no fiber shape remains, it can be determined that the resinous substance is a water-dispersed PU resin.

[0029] From the viewpoints of flexibility and uniformity required for artificial leather, it is preferable to fill the PU resin using a PU resin dispersion liquid, and in this case, the average primary particle diameter of the PU resin in the dispersion liquid is preferably 0.1 μm or more and 0.8 μm or less. The average primary particle diameter is a value obtained by measurement using a laser diffraction particle size distribution measuring device ("LA-920" manufactured by HORIBA) for the PU resin dispersion liquid. By setting the average primary particle diameter of the PU resin to 0.1 μm or more, the force (i.e., binder force) for gripping the fibers in the complex sheet by the PU resin can be improved, and an artificial leather having excellent mechanical strength can be obtained. Also, by setting the average primary particle diameter of the PU resin to 0.8 μm or less, it is advantageous in that aggregation or coarsening of the PU resin can be suppressed and the standard deviation of the cross-sectional PU resin area ratio can be controlled to 25 or less. By setting the average primary particle diameter of the PU resin in the PU resin dispersion liquid to 0.1 μm or more and 0.8 μm or less, there are more points where the fibers constituting the artificial leather (especially its surface layer) are gripped, and a soft texture (rigidity-flexibility value) and excellent mechanical strength (such as abrasion resistance) can be obtained. The average primary particle diameter of the PU resin is preferably 0.1 μm or more and 0.6 μm or less, and more preferably 0.2 μm or more and 0.5 μm or less.

[0030] [Solid content concentration of PU resin dispersion liquid] As described above, the PU resin is impregnated in the form of an impregnating liquid such as a solution (for example, in the case of a solvent-dissolved type) or a dispersion liquid (for example, in the case of a water-dispersed type). For example, the solid content concentration of the water-dispersed PU resin dispersion liquid can be 3% by weight or more and 35% by weight or less, more preferably 4% by mass or more and 30% by mass or less, and even more preferably 5% by mass or more and 25% by mass or less. In one aspect, the impregnating liquid is prepared and the complex sheet is impregnated so that the ratio of the PU resin to 100% by mass of the complex sheet is 5% by weight or more and 50% by weight or less.

[0031] As the PU resin, those obtained by the reaction of a polymer diol, an organic diisocyanate, and a chain extender are preferable. As the polymer diol, for example, diols such as polycarbonate-based, polyester-based, polyether-based, silicone-based, and fluorine-based can be adopted, and copolymers combining two or more of these may also be used. From the viewpoint of hydrolysis resistance, polycarbonate-based or polyether-based diols or a combination thereof are preferably used. Further, from the viewpoints of light resistance and heat resistance, polycarbonate-based, polyester-based, or a combination thereof diols are preferably used. Furthermore, from the viewpoint of cost competitiveness, polyether-based, polyester-based, or a combination thereof diols are preferably used. The polycarbonate-based diol can be produced by a transesterification reaction between an alkylene glycol and a carbonate ester, a reaction between phosgene or a chloroformate and an alkylene glycol, or the like.

[0032] Examples of the alkylene glycol include linear alkylene glycols such as ethylene glycol, propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,9-nonanediol, and 1,10-decanediol; branched alkylene glycols such as neopentyl glycol, 3-methyl-1,5-pentanediol, 2,4-diethyl-1,5-pentanediol, and 2-methyl-1,8-octanediol; alicyclic diols such as 1,4-cyclohexanediol; aromatic diols such as bisphenol A; and the like. These can be used alone or in combination of two or more. Examples of the polyester-based diol include polyester diols obtained by condensing various low molecular weight polyols and polybasic acids. As the low molecular weight polyol, for example, one or more selected from ethylene glycol, 1,2 - propylene glycol, 1,3 - propylene glycol, 1,3 - butanediol, 1,4 - butanediol, 2,2 - dimethyl - 1,3 - propanediol, 1,6 - hexanediol, 3 - methyl - 1,5 - pentanediol, 1,8 - octanediol, diethylene glycol, triethylene glycol, dipropylene glycol, tripropylene glycol, cyclohexane - 1,4 - diol, cyclohexane - 1,4 - dimethanol can be used. Also, an adduct obtained by adding various alkylene oxides to bisphenol A can be used. As the polybasic acid, for example, 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, dodecanedicarboxylic acid, phthalic acid, isophthalic acid, terephthalic acid, and hexahydroisophthalic acid can be mentioned.

[0033] Examples of the polyether - type diol include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, or a copolymer diol obtained by combining them. The number - average molecular weight of the polymer diol is preferably from 500 to 4000. By setting the number - average molecular weight to 500 or more, more preferably 1500 or more, it is possible to prevent the texture from becoming hard. Also, by setting the number - average molecular weight to 4000 or less, more preferably 3000 or less, the strength of the PU resin can be maintained well. Examples of the organic diisocyanate include aliphatic diisocyanates such as hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, isophorone diisocyanate, and xylylene diisocyanate; aromatic diisocyanates such as diphenylmethane diisocyanate and tolylene diisocyanate; and these may be used in combination. Among them, from the viewpoint of light resistance, aliphatic diisocyanates such as hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, and isophorone diisocyanate are preferably used. As the chain extender, an amine-based chain extender such as ethylenediamine and methylene bisaniline, or a diol-based chain extender such as ethylene glycol can be used. Further, a polyamine obtained by reacting a polyisocyanate with water can also be used as the chain extender.

[0034] Additives such as a stabilizer (e.g., ultraviolet absorber, antioxidant), flame retardant, antistatic agent, and pigment (e.g., carbon black) may be added to the impregnating liquid containing the PU resin (e.g., water-dispersible PU resin) as necessary. The total amount of these additives present in the artificial leather may be, for example, 0.1 to 10.0 parts by mass, or 0.2 to 8.0 parts by mass, or 0.3 to 6.0 parts by mass with respect to 100 parts by mass of the PU resin. Note that such additives will be distributed in the PU resin of the artificial leather. In the present disclosure, the values when referring to the size of the PU resin and the mass ratio to the complex sheet are intended to be the values including the additives (when used).

[0035] <Method for manufacturing artificial leather> Hereinafter, an example of the method for manufacturing the artificial leather of the present embodiment will be described. An example of the method for manufacturing the artificial leather of the present embodiment includes the following steps: (1) A step of forming a fiber web (A') from fibers having an average diameter of 2.0 μm or more and 7.0 μm or less; (2) A step of subjecting the obtained fiber web (A') to preliminary water stream entanglement to obtain a fiber sheet (A"); (3) At least laminate the fiber sheet (A″) and the scrim, and integrate them by the present water flow entanglement to obtain an entangled sheet; (4) Optionally, raise the outer surface of the obtained fiber sheet; (5) Fill the obtained entangled sheet with a polymer elastomer to obtain a sheet-like material; (6) When the step (4) is not carried out, raise the outer surface of the sheet-like material obtained in the step (5), or carry out the step (4) and further raise the outer surface of the sheet-like material; and (7) Dye the obtained sheet-like material; It can be the manufacturing method of the raised artificial leather including the above. As an example of the manufacturing method of artificial leather, the processes are carried out in the above order. Hereinafter, each step will be described in order. In addition, in this specification, what is formed into a sheet shape in the fiber web forming step is a fiber web, what is water flow entangled in the preliminary water flow entanglement step is a fiber sheet, and what is laminated with the scrim and optionally added fiber web or fiber sheet is a laminated sheet, what is water flow entangled in the present water flow entanglement step is an entangled sheet, what is filled with a polymer elastomer in the polymer elastomer filling step of the entangled sheet is a sheet-like material, and what is colored and processed is distinguished from artificial leather. In addition, the fiber layer constituting the artificial leather is not limited to being single. For example, an artificial leather obtained by using an entangled sheet having a three-layer structure composed of a fiber layer (A), a scrim in contact with the fiber layer (A), and a fiber layer (B) in contact with the scrim is composed of two fiber layers separated by a scrim. Further, when the artificial leather includes two or more fiber layers, their configurations are not limited to being the same. For example, by forming the fiber layer on the outer surface side with ultra-fine fibers that are likely to obtain a smooth touch and forming the fiber layer on the reverse side of the outer surface with flame-retardant fibers having a thick diameter and difficult to obtain a smooth touch, an artificial leather having flame retardancy while maintaining the smooth touch of the outer surface can be obtained.

[0036] [Fiber Web Forming Step] As methods for manufacturing the fiber webs (fiber web (A'), any fiber web (B'), additional fiber webs, etc.) that constitute each fiber layer (fiber layer (A), any fiber layer (B), additional fiber layers, etc.) that make up artificial leather, there are direct spinning methods (for example, the spunbond method and the meltblown method), or methods of forming a fiber web using staple fibers (for example, dry methods such as the carding method and the airlaid method, and wet methods such as the papermaking method), and any of them can be preferably used. In particular, fiber webs manufactured using staple fibers are suitable in terms of improving the surface quality of artificial leather because they have small basis weight unevenness, excellent uniformity, and are easily obtained with uniform fluffs.

[0037] As the fibers that are the raw materials for the fiber webs that constitute the fiber layers (fiber layer (A), any fiber layer (B), additional fiber layers, etc.) that make up artificial leather, directly spun fibers and ultrafine fibers taken out from ultrafine fiber-forming fibers are preferable. By using directly spun fibers and ultrafine fibers taken out from ultrafine fiber-forming fibers, the fibers in the fiber layers that make up artificial leather are easily dispersed as single fibers.

[0038] When using sea-island (SIF) staple fibers as the staple fibers, it is preferable to use ultrafine fiber-forming fibers as the means for forming the fibers of the fiber web. By using ultrafine fiber-forming fibers, a form in which fiber bundles are entangled can be stably obtained. As ultrafine fiber-forming fibers, sea-island type fibers in which two components of thermoplastic resins with different solvent solubilities are used as the sea component and the island component, and the sea component is dissolved and removed using a solvent or the like to make the island component into ultrafine fibers, or peeling type composite fibers in which two components of thermoplastic resins are alternately arranged radially or in multiple layers in the fiber cross-section and each component is peeled and split to split into ultrafine fibers can be adopted. Among them, sea-island type fibers are preferably used also from the viewpoints of the flexibility and texture of the sheet-like material because appropriate voids can be imparted between the island components, that is, between the fibers, by removing the sea component. For sea-island type fibers, there are sea-island type composite fibers spun by mutually arranging two components, namely a sea component and an island component, using a sea-island type composite spinneret, and mixed spun fibers spun by mixing the two components of the sea component and the island component. From the viewpoints of obtaining fibers with a uniform fineness and obtaining fibers of sufficient length that contribute to the strength of the sheet-like material, sea-island type composite fibers are preferably used. As the sea component of the sea-island type fiber, polyethylene, polypropylene, polystyrene, copolyester copolymerized with sodium sulfoisophthalic acid, polyethylene glycol, etc., and polylactic acid can be used. Among them, from the viewpoint of environmental consideration, copolyesters copolymerized with alkali-decomposable sodium sulfoisophthalic acid, polyethylene glycol, etc. that can be decomposed without using an organic solvent, and polylactic acid are preferable. When performing the sea-removing treatment using sea-island type fibers, it is preferably before the polymer elastomer filling step. If the sea-removing treatment is performed before the polymer elastomer filling step, since the polymer elastomer adheres directly to the fibers to form a structure that can strongly grip the fibers, the wear resistance of the sheet-like material becomes good.

[0039] When selecting a method using short fibers (staples), the short fiber length is preferably 13 mm or more and 102 mm or less, more preferably 25 mm or more and 76 mm or less, still more preferably 38 mm or more and 76 mm or less in the dry method (carding method, airlaid method, etc.), and preferably 1 mm or more and 30 mm or less, more preferably 2 mm or more and 25 mm or less, still more preferably 3 mm or more and 20 mm or less in the wet method (papermaking method, etc.). For example, the aspect ratio (L / D), which is the ratio of the length (L) to the diameter (D) of the short fibers used in the wet method (papermaking method, etc.), is preferably 500 or more and 2000 or less, more preferably 700 to 1500. Such an aspect ratio is preferable because the dispersibility and fibrillation property of the short fibers in the slurry when preparing the slurry by dispersing the short fibers in water are good, the fiber layer strength is good, and since the fiber length is shorter and the single fibers are easier to disperse compared to the dry method, it is difficult to form a hairy ball-like appearance called pilling due to friction. For example, the fiber length of short fibers with a diameter of 4 μm is preferably 2 mm or more and 8 mm or less, more preferably 3 mm or more and 6 mm or less.

[0040] [Water flow entanglement process] In the water flow entanglement process in the artificial leather manufacturing process, a preliminary water flow entanglement process of obtaining a fiber sheet (A″) by water flow entanglement only of the fiber web (A′) constituting the fiber layer (A) of the artificial leather obtained in the web forming process, and at least two layers of the fiber sheet (A″) subjected to the preliminary water flow entanglement treatment and a scrim are laminated, and it is preferable to include this water flow entanglement process of integrating the laminated at least two layers by water flow entanglement to obtain a complex sheet. By water flow entanglement only of the fiber web (A′) constituting the fiber layer (A) of the artificial leather, a sufficiently dense fiber sheet (A″) can be obtained, and the minimum porosity ε Amin in the fiber layer (A) can be adjusted to 70% or less. Further, this water flow entanglement process of laminating at least two layers of the fiber sheet (A″) subjected to the water flow entanglement treatment and a scrim and integrating the laminated at least two layers by water flow entanglement to obtain a complex sheet does not require an excessive water pressure for densifying the outer surface of the artificial leather, so the fiber density near the boundary between the fiber layer (A) and the scrim does not become over-dense, and the maximum porosity ε Smin from ε Amin to ε A-Smax existing up to can be adjusted to 70% or more and 80% or less. In addition, when the complex sheet has a three-layer structure composed of a fiber layer (A), a scrim in contact with the fiber layer (A), and a fiber layer (B) in contact with the scrim, the fiber layer (B) laminated as the laminated sheet is in the state of a fiber sheet (B″) obtained by water flow entanglement only of the fiber web (B′), or in the state of the fiber web (B′) not subjected to preliminary water flow entanglement. That is, the fiber layer (B) laminated as the laminated sheet may be laminated in any state, either in the state of the fiber sheet (B″) obtained by water flow entanglement only of the fiber web (B′) or in the state of the fiber web (B′) not subjected to preliminary water flow entanglement. Further, in the case of a multilayer structure having a fiber layer (C) or more on the fiber layer (B) side in addition to the fiber layer (B), the multilayer portion composed of the fiber layer (B) and the fiber layer (C) or more may be laminated in the same way as the fiber layer (B).

[0041] As a method of entanglement, a method can be adopted in which sea-island type fibers are cut into a predetermined fiber length to form staples, and a fiber web formed through a card and a cross lapper is entangled by a needle punching method. However, in one aspect, a water jet entanglement treatment is preferred.

[0042] The water pressure on the inflow side of the nozzle hole used in the water jet entanglement treatment is preferably 1 MPa or more and 10 MPa or less. By setting the water pressure to 1 MPa or more, it is easy to sufficiently entangle the fibers. On the other hand, by setting the water pressure to 10 MPa or less, it is easy to make the water flow marks remaining on the entanglement surface of the entangled body after treatment less noticeable. The water pressure is more preferably 1.5 MPa or more and 7.5 MPa or less, and even more preferably 2 MPa or more and 4.5 MPa or less.

[0043] The discharge port hole diameter of the nozzle used in the water jet entanglement process is preferably 0.15 mm or more and 0.30 mm or less. By setting the discharge port hole diameter to 0.15 mm or more, it is possible to discharge a sufficient amount of water for sufficiently entangling the fibers. Also, by setting the discharge port hole diameter to 0.30 mm or less, it is possible to make the water flow marks remaining on the entanglement surface of the entangled body after treatment less noticeable. The discharge port hole diameter is more preferably 0.15 mm or more and 0.25 mm or less, and even more preferably 0.15 mm or more and 0.22 mm or less.

[0044] In the water jet entanglement process, rotating the nozzle in a circular motion or reciprocating it at a right angle to the process progress direction is preferable in that the fibers can be entangled evenly, and the water flow marks parallel to the process progress direction are reduced, improving the surface quality.

[0045] [Raising treatment process] In order to form raised hairs on the surface of the complex sheet or sheet-like material, a raising treatment can be performed. The raising treatment can be carried out by a method such as grinding using sandpaper or a roll sander. Also, applying silicone or the like as a lubricant before the raising treatment enables the raising treatment by surface grinding to be easily performed, and the surface quality becomes very good.

[0046] [Polymer elastomer filling process] In this step, after impregnating the complex sheet with the polymer elastomer and then drying it, the polymer elastomer is filled. In one aspect, as the polymer elastomer, a water-dispersible polyurethane (PU) resin is preferred. The water-dispersible PU resin is impregnated in the form of an impregnating liquid such as a dispersion. The concentration of the water-dispersible PU resin in the impregnating liquid can be, for example, 3 to 35% by mass. In one aspect, the impregnating liquid is prepared and the complex sheet is impregnated so that the ratio of the PU resin to 100% by mass of the complex sheet is 5 to 50% by mass.

[0047] The water-dispersible PU resin is classified into a forced emulsification type PU resin that is forcibly dispersed and stabilized using a surfactant, and a self-emulsification type PU resin that has a hydrophilic structure in the PU molecular structure and is dispersed and stabilized in water even without the presence of a surfactant. Although either can be used in this embodiment, from the viewpoint of imparting thermosetting properties described later, it is preferable to use a forced emulsification type PU resin. The concentration of the water-dispersible PU resin (content of the PU resin in the water-dispersible PU resin dispersion) is preferably 3% by mass or more and 35% by mass or less, more preferably 4% by mass or more and 30% by mass or less, and even more preferably 5% by mass or more and 30% by mass or less, from the point of controlling the adhesion amount of the water-dispersible PU resin and the point that aggregation of the PU resin is promoted at high concentrations. Also, as the water-dispersible PU resin dispersion, those having thermosetting properties are preferred. By using a water-dispersible PU resin dispersion having thermosetting properties, the PU resin can be uniformly applied in the thickness direction of the complex sheet. Thermosetting properties refer to the property that when the PU resin dispersion is heated, when it reaches a certain temperature (thermosetting temperature), the fluidity of the PU resin dispersion decreases and it solidifies. In the production of a sheet-like material filled with the PU resin, after applying the PU resin dispersion to the complex sheet, it is solidified by dry heat curing, wet heat curing, hot water curing, or a combination thereof, and then dried to apply the PU resin to the complex sheet. As a method of solidifying a water-dispersible PU resin dispersion that does not exhibit thermosetting properties, dry solidification is realistic in industrial production. In that case, a migration phenomenon occurs in which the PU resin concentrates on the surface layer of the sheet-like material, and the texture of the sheet-like material filled with the PU resin tends to be fixed. The thermosetting temperature of the water-dispersible PU resin dispersion is preferably 40°C or higher and 90°C or lower. By setting the thermosetting temperature to 40°C or higher, the stability of the PU resin dispersion during storage becomes good, and adhesion of the PU resin to the machine during operation can be suppressed. Further, by setting the thermosetting temperature to 90°C or lower, the migration phenomenon of the PU resin in the complex sheet can be suppressed. In order to make the thermosetting temperature as described above, a thermosetting agent may be appropriately added. Examples of the thermosetting agent include inorganic salts such as sodium sulfate, magnesium sulfate, calcium sulfate, calcium chloride, and radical reaction initiators such as sodium persulfate, potassium persulfate, ammonium persulfate, azobisisobutyronitrile, and benzoyl peroxide.

[0048] The water-dispersible PU resin dispersion can be impregnated or coated on the complex sheet, and the PU resin can be solidified by dry heat curing, wet heat curing, hot water curing, or a combination thereof. The temperature of wet heat curing is preferably equal to or higher than the thermosetting temperature of the PU resin and is 40°C or higher and 200°C or lower. By setting the temperature of wet heat curing to 40°C or higher, more preferably 80°C or higher, the time until the PU resin is solidified can be shortened and the migration phenomenon can be more suppressed. On the other hand, by setting the temperature of wet heat curing to 200°C or lower, more preferably 160°C or lower, thermal degradation of the PU resin and PVA resin can be prevented. The temperature of hot water curing is preferably equal to or higher than the thermosetting temperature of the PU resin and is 40 or higher and 100°C or lower. By setting the temperature of hot water curing in hot water to 40°C or higher, more preferably 80°C or higher, the time until the PU resin is solidified can be shortened and the migration phenomenon can be more suppressed. The dry curing temperature and the drying temperature are preferably 80 or higher and 180°C or lower. By setting the dry curing temperature and the drying temperature to 80°C or higher, more preferably 90°C or higher, the productivity is excellent. On the other hand, by setting the dry curing temperature and the drying temperature to 180°C or lower, more preferably 160°C or lower, thermal degradation of the PU resin and PVA resin can be prevented.

[0049] [Dyeing process] Artificial leather is preferably dyed for the purpose of enhancing the value in terms of sensibility (i.e., visual effect). The dye may be selected according to the type of fiber constituting the complex sheet. For example, disperse dyes can be used for polyester-based fibers, acid dyes or metal-containing dyes can be used for polyamide-based fibers, and combinations thereof can also be used. When dyed with disperse dyes, reduction washing may be performed after dyeing. As the dyeing method, a usual method well-known to dyeing processors can be used. Since the sheet-like material can be softened by giving a rubbing effect while dyeing the sheet-like material, it is preferable to use a jet dyeing machine. The dyeing temperature preferably ranges from 80°C to 150°C, although it depends on the type of fiber. By setting the dyeing temperature to 80°C or higher, more preferably 110°C or higher, the dyeing on the fiber can be efficiently performed. On the other hand, by setting the dyeing temperature to 150°C or lower, more preferably 130°C or lower, the deterioration of the PU resin can be prevented. It is preferable to perform soaping and, if necessary, reduction washing (i.e., washing in the presence of a chemical reducing agent) on the thus-dyed artificial leather to remove excess dye. It is also a preferred embodiment to use a dyeing assistant during dyeing. By using a dyeing assistant, the uniformity and reproducibility of dyeing can be improved. Further, after dyeing or in the same bath as dyeing, a finishing agent treatment using a softening agent such as silicone, an antistatic agent, a water repellent, a flame retardant, a light fastness agent, an antibacterial agent, etc. can be performed.

[0050] The artificial leather of this embodiment has a very elegant appearance as an interior material for furniture, chairs, wall materials, seats, ceilings, interiors, etc. in vehicle interiors such as automobiles, trains, and airplanes, as well as for upper parts of shoes such as shirts, jackets, casual shoes, sports shoes, men's shoes, and women's shoes, trims, etc., bags, belts, wallets, etc., clothing materials used for parts thereof, and industrial materials such as wiping cloths, abrasive cloths, and CD curtains, and can be suitably used.

Example

[0051] Hereinafter, the present invention will be specifically described based on examples and comparative examples. However, the examples do not limit the scope of the present invention. For artificial leather samples according to the examples and comparative examples, each physical property, quality, etc. were evaluated by the following procedures and methods.

[0052] (1-0) Sampling location of the sample The sampling location of the sample is shown in FIG. 6. First, two locations (sampling regions 1 and 2) in the machine direction (MD) of the fiber layer (A) or the artificial leather containing the fiber layer (A) are cut out in a strip shape (indicated by a dotted line). In each sampling region, a cross-section in the thickness (t) direction is prepared. In this cross-section, five locations that are substantially uniform in the CD direction orthogonal to the MD direction are selected, and the average diameter (μm) of the single fibers constituting the fiber layer (A), the ratio value (%) of the distance near the cross-section k of the single fiber, and the scrim structure range are determined by the method described later. Ten images are prepared respectively for obtaining the average diameter (μm) of the single fibers constituting the fiber layer (A), the ratio value (%) of the distance near the cross-section k of the single fiber, and the scrim structure range.

[0053] (1-1) Average diameter (μm) of the single fibers constituting the fiber layer (A) The average diameter of the fibers constituting the fiber layer (A) is obtained by photographing one of the cross-sections of the fiber layer (A) of the artificial leather selected in (1-0) at a magnification of 1500 times using a scanning electron microscope (SEM, "JSM-5610" manufactured by JEOL), randomly selecting 10 fibers forming the cross-section of the fiber layer (A) of the artificial leather, and measuring the diameter of the cross-section of the single fiber. The same measurement is performed for all 10 cross-sections selected in (1-0), and the arithmetic mean value of the measurement values of 100 fibers is taken as the average diameter of the single fiber. When the observed shape of the cross-section of the single fiber is not circular, the outer peripheral distance on the straight line orthogonal to the midpoint of the longest diameter of the single fiber cross-section is taken as the fiber diameter. FIG. 3 is a conceptual diagram for explaining how to obtain the fiber diameter. For example, when the cross-section A of the fiber is elliptical as shown in FIG. 3, the outer peripheral distance c on the straight line b orthogonal to the midpoint p of the longest diameter a of the cross-section A in the observed image is taken as the fiber diameter.

[0054] (1-2) Ratio value (%) of the distance near the cross-section k of the single fiber The k-nearest neighbor method is a technique that selects k single fiber cross-sections close to any one single fiber cross-section and determines the radius of the k-th nearest neighbor in terms of Euclidean distance as the determination boundary. In this embodiment, in one SEM image, an area of about 250 μm × about 186 μm is photographed at 640 × 480 pixels by the image capture below the image (in this case, 1 pixel corresponds to about 0.40 μm × about 0.40 μm), and it is determined whether there is a single fiber cross-section that is the 9th nearest within a distance of 20 μm from the approximate center of any one single fiber cross-section. For all single fiber cross-sections in one SEM image, the presence or absence is determined, and the single fiber cross-section k = 9 nearest neighbor distance ratio value (%) is obtained by the following formula: Single fiber cross-section (k = 9) nearest neighbor distance ratio value (%) = {(number of single fiber cross-sections with the 9th nearest single fiber cross-section within a distance of 20 μm from the approximate center of the single fiber cross-section) / (total number of single fiber cross-sections in one SEM image)} × 100. The single fiber cross-section k = 9 nearest neighbor distance ratio value is obtained as the arithmetic mean value of the measured values of 10 SEM images at 10 locations selected from (1 - 0). In addition, when the sample has a scrim, the deepest part of the fiber layer (A) on the cut surface of the conductive-treated sample (i.e., the part closest to the scrim) is taken as the observation region, and the fibers constituting the scrim are excluded from the observation target, and it is observed with a scanning electron microscope (SEM, "JSM-5610" manufactured by JEOL). When the sample does not have a scrim, the center part in the artificial leather thickness direction on the cut surface of the conductive-treated sample is taken as the center point of the observation region, and it is observed with the above SEM. As shown in FIG. 4, the single fiber cross-sections in the SEM image can be identified by being marked manually by a person. The specific procedure is as follows: [Procedure 1] In the SEM image (gray), after attaching red (R) round dots to the fiber cross-sections, the coordinates of the cross-sections of the fibers are calculated. <Detailed method> (i) Read the image using OpenCV (cv2 module for Python). (ii) Extract pixels where R of RGB is 220 or more, and G and B are 100 or less. (iii) For noise processing, perform dilation processing (cv2.dilate with iteration = 2) and erosion processing (cv2.erode with iteration = 2) on the detected round points. (iv) Process the noise-processed image with cv2.connectedComponentsWithStats to obtain the centroid coordinates of the detected round points, which is the third result among the four obtained results. (v) Use the above centroid coordinates as the fiber cross-section position. (vi) Further, calculate the distance between specific positions on the coordinates. When the coordinates of fiber cross-section A and fiber cross-section B are (Ax, Ay) and (Bx, By), the two distances R are 2 R = √((Ax - Bx) 2 +(Ay - By) [Step 2] For all fiber cross-sections, calculate the Euclidean distance (k-nearest neighbor distance: matrix distance) to the k-th nearest fiber cross-section. [Detailed method] (i) Calculate the distance between the coordinates of fiber cross-section A and other cross-sections. (ii) Arrange the calculated distances in ascending order. (iii) Take the k-th distance in the arranged distances as the k-nearest neighbor distance. [Step 3] Divide the number of cross-sections with a k-nearest neighbor distance less than or equal to R by the total number of fiber cross-sections to obtain the k-nearest neighbor distance ratio value in the SEM image. When there are a large number of SEM images, images including teacher data (correct labels) with red (R) round dots attached to the fiber cross-section can be used as learning data, and semantic segmentation using the FCN (Fully Convolutional Networks) method (Jonathan Long, Evan Shelhamer, and Trevor Darrel (2015): Fully Convolutional Networks for Semantic Segmentation. In The IEEE Conference on Computer Vision and Pattern Recognition (CVPR)), which is a network composed entirely of convolutional layers, can be used for machine learning (deep learning) for classifying pixels at the pixel level by semantic segmentation to identify the position of the fiber cross-section instead of manual marking by humans.

[0055] (1 - 3) Determination of the scrim structure range The scrim structure range in the thickness direction of artificial leather is obtained by the following method. (i) The cross-section obtained by cutting artificial leather in the thickness direction is photographed at a magnification of 50 times using a scanning electron microscope (SEM, "JSM - 5610" manufactured by JEOL) to obtain an SEM image. (ii) Draw a line segment A along the outer surface on the fiber layer (A) side and parallel to the plane direction of the artificial leather. (iii) Draw a line segment D along the surface on the side opposite to the fiber layer (A) and parallel to the plane direction of the artificial leather. (iv) Draw two line segments that are in contact with the yarn bundle constituting the scrim, parallel to the plane direction of the artificial leather, and have the farthest distance between the two line segments. Of the two line segments, the one closer to line segment A is line segment B, and the other is line segment C. At the distance between line segment A and line segment D, when line segment A is 0[%] and line segment D is 100[%], the relative positions of line segment C and line segment D are B[%] and C[%] respectively. (v) The relative positions B[%] and C[%] are respectively obtained as the arithmetic mean values of the measured values of 10 SEM images at 10 locations selected by (1 - 0). (vi) The scrim structure range is the range occupied by the scrim with respect to the thickness of the artificial leather. Therefore, the range of relative position B~C [%] is the scrim structure range.

[0056] [Porosity distribution of artificial leather] The porosity distribution of the artificial leather is determined by the following procedure. Prior to this, three arbitrary locations on the artificial leather that are more than 5 cm apart from each other are each cut into a size of 10 mm × 10 mm and used as measurement samples. (i) Take a three-dimensional image of the artificial leather by X-ray CT. Device: "High-resolution 3D X-ray microscope nano3DX" manufactured by Rigaku X-ray target: Cu X-ray tube voltage / tube current: 40 kV / 30 mA Exposure time: 12 seconds per image Spatial resolution: 1.08 μm / pix Observation area: The range shall be such that the entire thickness in the cross-section in the thickness direction of the sample is included. The center point thereof shall be the central part of the thickness in the cross-section in the thickness direction. (ii) Rotate the taken cylindrical three-dimensional image so that the plane composed of the x-axis and the z-axis is parallel to the cross-section in the thickness direction and the plane composed of the x-axis and the z-axis is parallel to the plane direction. Next, trim the range of a rectangular parallelepiped of the following size including the artificial leather from the rotated three-dimensional image. Side parallel to the x-axis: 1.25 mm Side parallel to the y-axis: 1.25 mm Side parallel to the z-axis: 1.35 mm (iii) Apply a median filter to the three-dimensional image of the trimmed rectangular parallelepiped under the condition of a radius of 2 pix. (iv) Apply the Otsu method to the three-dimensional image after applying the median filter to divide the region. Set the luminance value of the pixel so that the air (inter-fiber void part) is 0 and the fibers and polyurethane constituting the artificial leather are 255. (v) Among the three-dimensional images with the region divided, for the pixels with a luminance value of 255, perform segmentation of the image processing method, and remove the structures with the number of pixels (pix) of the part with a continuous luminance value of 255 being 10,000 or less as noise. (vi) Remove the noise from the three-dimensional image, cut it out every 1 pixel in the thickness direction (y-axis), and capture a two-dimensional image parallel to the plane composed of the x-axis and the z-axis each time. Calculate the porosity of the captured two-dimensional image using the following formula. Porosity (%) = (Number of pixels with luminance value 0 / Total number of pixels) × 100 (vii) Perform the above (vi) for all the two-dimensional images to obtain the porosity distribution. In addition, from the porosity distribution obtained from the three-dimensional image of artificial leather by X-ray CT, each related value is obtained by the following method. (i) Assume that the artificial leather occupies the position between two points with a porosity of 95% in the porosity distribution (that is, the distance between the two points is the thickness of the artificial leather). (ii) Among the two points, take the point on the fiber layer (A) side as the line segment A described in (1 - 3), and the other point as the line segment D. Determine the scrim structure range in the porosity distribution from the scrim structure range B - C [%] calculated from the cross-sectional SEM image. (iii) Take the minimum porosity at the maximum concave peak within the scrim structure range in the porosity distribution of the artificial leather as the minimum porosity ε Smin of the scrim. (iv) Take the porosity of the maximum concave peak in the range from the peak at the minimum porosity ε Smin of the scrim to the outer surface as the minimum porosity ε Amin of the fiber layer (A) of the artificial leather. Also, taking the line segment A as 0% and the lower limit B of the scrim structure range as 100%, take the relative position [%] of ε Amin between A - B as the relative position of ε Amin in the fiber layer (A). (v) Take the maximum porosity existing from ε Smin to ε Amin as ε A-Smax . (vi) The lower limit B [%] of the scrim structure range, the upper limit C [%] of the scrim structure range, ε Smin , ε Amin , the relative position of ε Amin in the fiber layer (A), and ε A-SmaxIt is obtained as the arithmetic mean value (rounded to the first decimal place) of the measured values of three three-dimensional images at any three locations of the sample.

[0057] [Texture] Cut out any one part of the artificial leather to a size of 200 mm × 200 mm and use it as a measurement sample. For the outer surface of the said sample, a total of 10 people, 5 adult men and 5 adult women in good health, were used as evaluators, and visually and by sensory evaluation, a five-level evaluation was carried out according to the following evaluation criteria. The average value of the evaluations of the 10 evaluators (rounded to the first decimal place) is taken as the grade of texture. For texture, grades 3 to 5 are considered good (qualified). [Evaluation Criteria] Grade 5: The fluff is very dense and the appearance is very good. Grade 4: An evaluation between Grade 5 and Grade 3. Grade 3: There is a generally uniform fluff and it has the appearance of leather. Grade 2: An evaluation between Grade 3 and Grade 1. Grade 1: The fluff is uneven and the appearance is rough.

[0058] [Calculation of Texture (Rigidity and Softness Value)] Cut out any one part of the artificial leather to a size of 200 mm × 200 mm and use it as a measurement sample. Place the said measurement sample on a horizontal plane. Taking the vertices of the square as A, B, C, and D, superpose the diagonally facing vertices A and C. Place vertex A on the horizontal plane and superpose vertex C on vertex A. Then, with vertex C in contact with the measurement sample, gradually move it away from vertex A along the diagonal AC. The point where vertex C leaves the measurement sample surface is designated as point E, and the distance between point E and vertex C is taken as softness value 1. Replace vertex A with vertex B and vertex C with vertex D, and measure softness value 2 in the same procedure as above. The same measurement is carried out for 5 samples, and the arithmetic mean value (rounded to the first decimal place) of a total of 10 values is taken as the texture (rigidity and softness value) of the sample. For the texture (rigidity and softness value), 26 cm or less is considered good (qualified).

[0059] [Evaluation of Abrasion Resistance] In accordance with the method described in JIS L1096 "Test Methods for Fabrics and Knitted Fabrics - 8.19.5 Method E (Martindale Method)", conduct a Martindale test (abrasive cloth: "ABRASIVECLOTH1575W" manufactured by James H. Heal). The conditions for the Martindale test are as follows. Areal density 250 g / m2 or more: Number of friction cycles 50,000, load 12 kPa Areal density less than 250 g / m2: Number of friction cycles 20,000, load 9 kPa. Next, regarding the worn surface of the sample after the test, using 5 healthy adults as evaluators, visually evaluate and determine it in 5 grades according to the following evaluation criteria. [Evaluation Criteria] Grade 5: The scrim is not exposed on the worn surface, and no pilling is observed. Grade 4: An evaluation between Grade 5 and Grade 3. Grade 3: The scrim is not exposed on the worn surface, but the fiber layer is worn. Grade 2: An evaluation between Grade 3 and Grade 1. Grade 1: The scrim is exposed on the worn surface. In addition, take the average value (rounded to the first decimal place) of the 15 points, which is the evaluation result of the above 5 evaluators for 3 samples, as the abrasion resistance. The abrasion resistance is considered good (qualified) for Grades 3 to 5.

[0060] [Example 1] Polyethylene terephthalate fibers with an average single fiber diameter of 2.5 μm were produced by the melt spinning method and cut into lengths of 5 mm (hereinafter, the polyethylene terephthalate fibers with a length of 5 mm after cutting are also referred to as "PET ultra-fine short fibers"). The PET ultra-fine short fibers were dispersed in water and a fiber web (A′) with an areal density of 140 g / m 2 was produced by the papermaking method. For the obtained fiber web (A′), a high-speed water flow using a straight-through flow injection nozzle was sprayed from the outer surface side at a pressure of 4 MPa, and dried at 100 °C using an air-through type pin tenter dryer to obtain a fiber sheet (A″). In the same manner, the PET ultra-fine short fibers were dispersed in water and a fiber web with an areal density of 80 g / m 2A fiber web (B′) was produced and used as the fiber layer (B) on the reverse side of the outer surface of the artificial leather. A scrim (plain weave) with a basis weight of 95 g / m made of 166 dtex / 48f polyethylene terephthalate fibers was inserted between the fiber sheet (A″) and the fiber web (B′) to form a laminated sheet having a three-layer structure. 2 Subsequently, a high-speed water stream using a straight-through flow injection nozzle was sprayed onto the laminated sheet from the outer surface side at a pressure of 4 MPa and from the reverse side of the outer surface at a pressure of 3 MPa. After the fiber layer was entangled with the scrim and entangled and integrated, it was dried at 100 °C using an air-through type pin tenter dryer to obtain a complex sheet having a three-layer structure. Next, the outer surface of the complex sheet was raised using #400 emery paper. Subsequently, the complex sheet was impregnated with an aqueous dispersion type polyurethane resin impregnating solution having the composition shown in Table 1 below, and then heated and dried at 130 °C using a pin tenter dryer. After that, it was rubbed in a state of being immersed in hot water heated to 90 °C, and then dried to extract and remove anhydrous sodium sulfate, thereby obtaining a sheet-like material filled with an aqueous dispersion type polyurethane resin. The ratio of the aqueous dispersion type PU resin to the total fiber mass of this sheet-like material was 10% by mass. Next, the sheet-like material was dyed at 130 °C for 15 minutes using a liquid flow dyeing machine with a blue disperse dye having a dye concentration of 5.0% owf (Sumitomo Chemical Co., Ltd.'s "Blue FBL"), and reduction washing was performed. Then, it was dried at 100 °C for 5 minutes using a pin tenter dryer to obtain artificial leather having a three-layer structure.

[0061]

Table 1

[0062] [Example 2] An artificial leather having a three-layer structure was obtained according to the method of Example 1, except that the average diameter of the single fiber of the polyethylene terephthalate fiber used for the fiber web (A′) was 3.2 μm.

[0063] [Example 3] An artificial leather having a three-layer structure was obtained according to the method of Example 1, except that the average diameter of the single fibers of the polyethylene terephthalate fibers used in the fiber web (A′) was 4.5 μm.

[0064] [Example 4] An artificial leather having a three-layer structure was obtained according to the method of Example 1, except that the average diameter of the single fibers of the polyethylene terephthalate fibers used in the fiber web (A′) was 5.5 μm.

[0065] [Example 5] An artificial leather having a three-layer structure was obtained according to the method of Example 1, except that the average diameter of the single fibers of the polyethylene terephthalate fibers used in the fiber web (A′) was 6.4 μm.

[0066] [Example 6] An artificial leather having a two-layer structure was obtained according to the method of Example 1, except that the average diameter of the single fibers of the polyethylene terephthalate fibers used in the fiber web (A′) was 4.5 μm and a laminated sheet having a two-layer structure was formed without using the fiber web (B′).

[0067] [Example 7] As the sea component, polyethylene terephthalate copolymerized with 8 mol% of sodium 5-sulfoisophthalate was used, and as the island component, polyethylene terephthalate was used. A sea-island composite fiber having a composite ratio of 20% by mass of the sea component and 80% by mass of the island component, 16 islands / 1f of the number of islands, and an average fiber diameter of 18 μm was obtained. The obtained sea-island composite fiber was cut into a fiber length of 51 mm to form staples, and a fiber web (A′) was produced through a card and a cross lapper. A high-speed water flow using a straight-through flow injection nozzle was injected onto the obtained fiber web (A′) from the surface side at a pressure of 4 MPa, and dried at 100 °C using an air-through type pin tenter dryer. Then, it was immersed in an aqueous sodium hydroxide solution having a concentration of 10 g / L heated to a temperature of 95 °C and treated for 25 minutes to obtain a fiber sheet (A″) from which the sea component of the sea-island composite fiber was removed. The average diameter of the single fibers of the fibers constituting the fiber sheet (A″) was 4.0 μm. Polyethylene terephthalate fibers with an average single fiber diameter of 2.5 μm were produced by the melt spinning method and cut into lengths of 5 mm. The PET ultra-fine short fibers were dispersed in water and a fiber web (B′) with a basis weight of 80 g / m 2 was produced by the papermaking method. Between the fiber sheet (A″) and the fiber web (B′), a scrim (plain weave) with a basis weight of 95 g / m 2 made of 166 dtex / 48f polyethylene terephthalate fibers was inserted to form a laminated sheet with a three-layer structure. In the steps after the laminated sheet, an artificial leather with a three-layer structure was obtained according to the method of Example 1.

[0068] [Example 8] An artificial leather with a three-layer structure was obtained according to the method of Example 3, except that a high-speed water stream was sprayed onto the surface of the fiber web (A′) from the surface side at a pressure of 6 MPa.

[0069] [Comparative Example 1] An artificial leather with a three-layer structure was obtained according to the method of Example 1, except that the average single fiber diameter of the polyethylene terephthalate fibers used in the fiber web (A′) was 1.0 μm.

[0070] [Comparative Example 2] An artificial leather with a three-layer structure was obtained according to the method of Example 1, except that the average single fiber diameter of the polyethylene terephthalate fibers used in the fiber web (A′) was 7.2 μm.

[0071] [Comparative Example 3] An artificial leather with a three-layer structure was obtained according to the method of Example 3, except that high-speed water flow and drying using a straight-through flow injection nozzle for the fiber web (A′) were not performed, that is, a laminated sheet with a three-layer structure including the fiber web (A′) instead of the fiber sheet (A″) was used.

[0072] [Comparative Example 4] Polyethylene was used as the sea component, nylon-6 was used as the island component, and a sea-island composite fiber was obtained at a composite ratio of 50% by mass of the sea component and 50% by mass of the island component. The obtained sea-island composite fiber was cut into a staple length of 51 mm to form a staple with an average fineness of 4 dtex, and a fiber web was formed through a card and a cross lapper, and a fiber sheet was obtained by needle punching treatment. Next, the fiber sheet was impregnated with the aqueous dispersion type polyurethane resin impregnating liquid shown in Table 2 below, wet heat coagulated at 100 °C for 5 minutes, and hot air dried at 130 °C to 150 °C for 2 to 6 minutes using a pin tenter dryer to obtain a sheet-like material. The ratio of the aqueous dispersion type PU resin to the total fiber mass of this sheet-like material was 30% by mass. The obtained sheet-like material was immersed in toluene heated to a temperature of 85 °C for treatment to perform a de-sea treatment for removing polyethylene, which is the sea component of the sea-island composite fiber. The average diameter of the single fiber of the fiber constituting the sheet-like material after de-sea was 0.2 μm. Next, the outer surface of the sheet-like material was raised using #400 emery paper to obtain a sheet-like material with a basis weight of 300 g / m2 having the raised surface. Next, the sheet-like material was dyed with a gold-containing dye at 60 °C for 100 minutes using a Wins dyeing machine. Then, it was dried at 100 °C for 5 minutes using a pin tenter dryer to obtain a single-layer artificial leather.

[0073]

Table 2

[0074] [Comparative Example 5] An artificial leather with a single-layer structure was obtained according to the method of Comparative Example 4, except that the average diameter of the single fiber of the fiber constituting the sheet-like material after de-sea was adjusted to 2.6 μm.

[0075] Various physical properties, etc. of the artificial leathers obtained in Examples 1 to 8 and Comparative Examples 1 to 5 are shown in Table 3 below.

[0076]

Table 3

Industrial Applicability

[0077] The artificial leather according to the present invention is excellent in all of a dense outer surface, a soft texture, and abrasion resistance, and thus can be suitably used for the surface material or interior material of seats for interiors, automobiles, airplanes, railway vehicles, etc., clothing products, etc. Specifically, the artificial leather according to the present invention has a very elegant appearance as a surface material for seats, ceilings, interiors, etc. in vehicle interiors such as furniture, chairs, wall materials, automobiles, trains, airplanes, etc., the upper parts of shoes such as shirts, jackets, casual shoes, sports shoes, men's shoes, women's shoes, trims, etc., bags, belts, wallets, etc., clothing materials used for a part of them, industrial materials such as wiping cloths, abrasive cloths, CD curtains, etc. and can be suitably used.

Explanation of Reference Numerals

[0078] MD Process Progress Direction (Machine Direction) CD Width (Cross) Direction 11 Complex Sheet 12 Scrim 13 Fiber Layer (A) 14 Fiber Layer (B)

Claims

1. A napped artificial leather comprising a complex sheet and a polymer elastomer filled in the complex sheet, wherein the complex sheet has a structure of two or more layers composed of a fiber layer (A) on the surface side of the napped artificial leather and a scrim which is a fabric in contact with the fiber layer (A), The average diameter of the fibers constituting the fiber layer (A) is 2.0 μm or more and 7.0 μm or less, and when measuring the porosity in the thickness direction from the front side to the back side, the minimum porosity in the fiber layer (A) is ε Amin (%), the minimum porosity in the scrim is ε Smin (%), and the maximum porosity existing from the position of the ε Amin (%) to the position of the ε Smin (%) is ε A-Smax (%), then the following formulas (1) to (3): 40 ≤ ε Amin ≤ 70 ... Formula (1) 70 ≤ ε A-Smax ≤ 90 ... Formula (2) ε Smin <ε A-Smax ... Formula (3) The napped artificial leather is characterized by satisfying the following.

2. The artificial leather according to Claim 1, wherein the k-nearest neighbor distance ratio value of the fiber layer (A) is 10% or more and 80% or less.

3. When the relative position of the surface of the fiber layer (A) is 0% and the relative position of the boundary between the fiber layer (A) and the scrim is 100% in the thickness direction of the fiber layer (A), ε which is the minimum porosity in the fiber layer (A) Amin The artificial leather according to claim 1 or 2, wherein the relative position of is in the range of 20% or more and 95% or less.

4. The artificial leather according to Claim 1 or 2, wherein the polymer elastomer is a water-dispersed polyurethane.

5. The artificial leather according to Claim 1 or 2, wherein the complex sheet is composed of polyester fibers.

6. The artificial leather according to Claim 1 or 2, wherein the complex sheet has a three-layer structure composed of a fiber layer (A), a scrim in contact with the fiber layer (A), and a fiber layer (B) in contact with the scrim.

7. The following steps: (1) A step of forming a fiber web (A') from fibers having an average diameter of 2.0 μm or more and 7.0 μm or less; (2) A step of subjecting the obtained fiber web (A') to preliminary water entanglement to obtain a fiber sheet (A"); (3) A step of laminating at least the fiber sheet (A") and a scrim which is a fabric and integrating them by main water entanglement to obtain a complex sheet; (4) Optionally, a step of raising the outer surface of the obtained fiber sheet; (5) A step of filling the obtained complex sheet with a polymer elastomer to obtain a sheet-like material; (6) When the step (4) is not carried out, a step of raising the outer surface of the sheet-like material obtained in the step (5), or a step of carrying out the step (4) and further raising the outer surface of the sheet-like material; and (7) A step of dyeing the obtained sheet-like material; The method for manufacturing the napped artificial leather according to Claim 1 or 2, which includes the above steps.

8. The method according to Claim 7, wherein the water pressure of the preliminary water entanglement in the step (2) is 2 MPa or more and 4.5 MPa or less.

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