Wool-standing artificial leather and manufacturing method thereof

Abstract

A suede artificial leather comprising a non-woven fabric and having a suede surface, the non-woven fabric containing ultrafine fibers and a polymeric elastomer, the content of the polymeric elastomer being 15-35 mass%, the area ratio of the polymeric elastomer present on the suede surface being 17% or less, and the suede fiber length being 250 [mu] m or less.

Description

Technical Field

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

[0002] The napped artificial leather having a suede-like appearance used as a surface material for clothing, shoes, furniture, car seats, sundry products, etc. has a napped surface formed by raising ultrafine fibers to raise the nap. Such a napped artificial leather is usually used by coloring, and dyeing using dyes that can be colored in a wide range of colors from light to dark has been widely performed.

[0003] In the conventional napped artificial leather, the napped artificial leather using polyester fiber as the ultrafine fiber and polyurethane resin as the polymer elastic body is dyed with disperse dyes and then reduction-cleaned. In this case, there is a problem that the napped artificial leather has uneven color and poor appearance.

[0004] In response to such a problem, for example, Patent Document 1 proposes an artificial leather, in which, in a cross section when the artificial leather is cut perpendicularly to the surface direction, the number of blocks of polymer elastomer having a size of 100 μm or more in the thickness direction within 200 μm in the thickness direction from the surface excluding the napped portion of the above-mentioned artificial leather is 0.1 to 2.5 pieces / mm per unit cross-sectional length in the surface direction.

[0005] Patent Document 2 proposes an artificial leather substrate in which the average area of ​​the polymer elastic body exposed on the surface of the sheet is 0.1 mm 2 the following.

[0006] In addition, conventional napped artificial leather has limited color tone and color depth, and has a problem of being difficult to color in a wide range of color tone and color depth.

[0007] To address such a problem, Patent Document 3 proposes a suede-like artificial leather using fibers colored with a pigment and a polymer elastic body colored with a pigment, and having an average nap length of 10 to 200 μm.

[0008] In addition, the raised nap artificial leather is required to have excellent density, softness, etc., and a good touch, close to the texture of natural leather.

[0009] In response to such a requirement, for example, Patent Document 4 proposes a nubuck-like leather-like sheet material, which is made of a single fiber with a fineness of 0.0001 to 0.5 dtex and an apparent density of 0.300 to 0.700 g / cm 3 The nonwoven fabric is formed of short fibers with a nap length of 5 to 500 μm and no membrane formed by an elastic polymer.

[0010] Patent Document 5 proposes an artificial leather in which the average fiber length of the ultrafine fibers in the nap layer is 250 μm to 500 μm, and the surface coverage of the ultrafine fibers in the nap layer exceeds 60% and is 100% or less.

[0011] In addition, Patent Document 6 proposes a leather-like fabric having a resin layer intermittently formed on the napped surface, wherein the resin portion occupies 10 to 90% of the surface area of ​​the fabric, and the resin layer is composed of two or more layers.

[0012] Prior art literature

[0013] Patent Literature

[0014] Patent Document 1: Japanese Patent Application Publication No. 2016-69790

[0015] Patent Document 2: Japanese Patent Application Publication No. 2016-11477

[0016] Patent Document 3: Japanese Patent Application Publication No. 2004-143654

[0017] Patent Document 4: Japanese Patent Application Publication No. 2006-241620

[0018] Patent Document 5: International Publication No. 2020 / 003866

[0019] Patent Document 6: International Publication No. 2017 / 22387 Summary of the invention

[0020] Problems to be solved by the invention

[0021] The artificial leathers described in Citations 1 and 2 can suppress the occurrence of color unevenness, but are insufficient in terms of friction and wear resistance and mechanical strength such as tensile strength, and thus there is room for improvement.

[0022] Furthermore, the mechanical strength such as tensile strength of the artificial leathers described in Patent Documents 3, 4, and 6 is also insufficient, and there is room for improvement.

[0023] Furthermore, the touch of the leather described in Patent Document 5 is not satisfactory, that is, the touch is rough, and there is room for improvement.

[0024] On the other hand, as a method for suppressing uneven dyeing different from the methods described in References 1 and 2, a method of concealing uneven color by increasing the length of the napped fibers has also been studied. However, in this case, there are problems of poor touch and reduced density. In addition, in applications where people come into contact with furniture and car seats, there is a problem of excessive gloss and uneven appearance.

[0025] In addition, in order to further improve the mechanical strength of napped artificial leather, the use of long fibers in napped artificial leather has been studied in the past. However, if long fibers are used, although the mechanical strength such as tensile strength is improved, there is a problem of color unevenness compared to napped artificial leather formed by short fibers.

[0026] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a napped artificial leather which can suppress the occurrence of color unevenness and has both high mechanical strength and excellent texture.

[0027] In addition, in this specification, "excellent texture" means the texture close to that of natural leather, such as excellent density, softness, and good touch.

[0028] Solutions to the problem

[0029] The present invention is based on the following insight: by setting the content of a polymer elastic body imparted to a nonwoven fabric, the area ratio of the polymer elastic body present on the napped surface, and the napped fiber length to given values, a napped artificial leather can be obtained which can suppress the occurrence of color unevenness and has both high mechanical strength and excellent hand feel.

[0030] The present invention provides the following aspects.

[0031] [1] A napped artificial leather comprising a nonwoven fabric and having a napped surface, wherein the nonwoven fabric contains ultrafine fibers and a polymer elastomer, the content of the polymer elastomer is 15 to 35% by weight, the area ratio of the polymer elastomer present on the napped surface is 17% or less, and the napped fiber length is 250 μm or less.

[0032] [2] The napped artificial leather according to [1] above, wherein:

[0033] The ultrafine fibers are polyester fibers.

[0034] [3] The napped artificial leather according to [1] or [2], wherein:

[0035] The average fineness of the ultrafine fibers is 0.01 to 1.0 dtex.

[0036] [4] The napped artificial leather according to any one of [1] to [3], wherein:

[0037] The nonwoven fabric is a spunbonded nonwoven fabric.

[0038] [5] A method for producing a napped artificial leather, which is the method for producing a napped artificial leather according to any one of [1] to [4] above, the method comprising:

[0039] A step of removing a sea component from the entangled web containing the above-mentioned high molecular weight elastic body to obtain a nonwoven fabric containing the above-mentioned high molecular weight elastic body.

[0040] [6] The method for producing the napped artificial leather according to [5], the method comprising:

[0041] A step of melt-spinning sea-island type composite fibers to obtain a web.

[0042] [7] The method for producing napped artificial leather according to [6] above, wherein:

[0043] In the step of obtaining the nonwoven fabric containing the elastic polymer, the sea component is dissolved and removed using an organic solvent.

[0044] [8] The method for producing the napped artificial leather according to any one of [5] to [7] above, comprising:

[0045] A step of obtaining an entangled web containing the above-mentioned high molecular weight elastic body using a solvent-based polyurethane.

[0046] Effects of the Invention

[0047] According to the present invention, it is possible to provide a napped artificial leather which can suppress the occurrence of color unevenness and has both high mechanical strength and excellent texture, and a method for producing the same. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 This is an image obtained by photographing the napped surface of the napped artificial leather of the present invention at a magnification of 50 times using a scanning electron microscope (SEM) in order to measure the area ratio of the polymer elastic body present on the napped surface.

[0049] Figure 2 In order to measure the area ratio of the polymer elastic body present on the napped surface of the napped artificial leather of the present invention, Figure 1 An image obtained by painting the polymer elastic body, that is, the polyurethane part of the image black and transferring it to an OHP sheet.

[0050] Figure 3 This is a conceptual diagram for explaining a method for measuring the nap fiber length of the napped artificial leather of the present invention. DETAILED DESCRIPTION

[0051] Hereinafter, description will be given based on an example of an embodiment of the present invention (hereinafter sometimes referred to as "this embodiment"). However, the embodiment shown below is an example for actualizing the technical idea of ​​the present invention, and the present invention is not limited to the following description.

[0052] In this specification, preferred embodiments are shown, and a combination of two or more preferred embodiments is also a preferred embodiment. Regarding items represented by numerical ranges, when there are several numerical ranges, their lower limits and upper limits can be selectively combined as a preferred embodiment.

[0053] In addition, in this specification, when there is a description of a numerical range of "XX to YY", it means "XX or more and YY or less".

[0054] [Raised nap artificial leather]

[0055] The napped artificial leather of this embodiment comprises a nonwoven fabric and has a napped surface, wherein the nonwoven fabric contains ultrafine fibers and a polymer elastomer, wherein the content of the polymer elastomer is 15 to 35% by weight, the area ratio of the polymer elastomer present on the napped surface is less than 17%, and the napped fiber length is less than 250 μm.

[0056] The napped artificial leather of the present embodiment can suppress the occurrence of color unevenness and has both high mechanical strength and excellent texture.

[0057] In the present specification, nap fiber length refers to the length of nap fibers present on the nap surface of nap artificial leather, and color unevenness refers to color unevenness that occurs when the nap artificial leather is colored.

[0058] The reason why the napped artificial leather of the present embodiment exhibits the above-mentioned effects by having the above-mentioned configuration is not yet determined, but is considered to be as follows.

[0059] Generally speaking, in napped artificial leather, different components are used for the fibers and polymer elastic body constituting the nonwoven fabric. For example, polyester fibers are sometimes used as fibers, and polyurethane resins are used as polymer elastic bodies. If such napped artificial leather is colored using a colorant such as a disperse dye, the coloring properties of the fibers and the polymer elastic body are different, so the hue and depth of the color of the fibers and the polymer elastic body may sometimes differ. In particular, it can be considered that if the hue and depth of the color between the polymer elastic body exposed on the napped surface and the fibers present on the napped surface differ, the difference can be confirmed as color unevenness.

[0060] It can be considered that, for the napped artificial leather of the present invention, by setting the content of the polymer elastomer to 15 to 35% by mass and the area ratio of the polymer elastomer present on the napped surface to 17% or less, it is possible to suppress exposure of the polymer elastomer on the napped surface, resulting in suppression of color unevenness.

[0061] The napped artificial leather of this embodiment has a content of the polymer elastic body of 15 to 35% by mass, which not only suppresses color unevenness, but also has excellent density and softness, and has a good touch, similar to that of natural leather.

[0062] From the viewpoint of obtaining a napped artificial leather having a better hand feel, the content of the polymer elastic body is preferably 16 to 34% by mass, more preferably 16.5 to 33.5% by mass, and even more preferably 17 to 33% by mass.

[0063] For the napped artificial leather of the present embodiment, the area ratio of the above-mentioned polymer elastic body present on the napped surface is 17% or less. By setting the area ratio of the polymer elastic body to 17% or less, it is possible to suppress the polymer elastic body from being exposed from the napped surface, and no or only a very small amount of the polymer elastic body is visually recognized, and color unevenness can be suppressed. From the viewpoint of further suppressing uneven dyeing, the area ratio of the polymer elastic body is preferably 15% or less, more preferably 14% or less, and further preferably 13% or less. Moreover, from the viewpoint of obtaining a napped artificial leather having better softness and elasticity, the area ratio of the polymer elastic body is preferably 5% or more, more preferably 6% or more, and further preferably 7% or more.

[0064] In addition, in this specification, "the area ratio of the polymer elastic body existing on the napped surface" is measured and calculated by the following method.

[0065] Using a scanning electron microscope (SEM), the napped surface of the napped artificial leather was photographed at three different locations at a magnification of 50. The total area of ​​the region where the polymer elastic body existed was obtained from each image using an image processing device, and the area ratio of the polymer elastic body was calculated using the following formula based on the obtained total area and the total area of ​​all image regions.

[0066] Area ratio of polymer elastic body = total area of ​​the region where the polymer elastic body exists / total area of ​​the entire image region × 100 (%)

[0067] Specifically, the measurement and calculation were performed by the method described in the Examples described later.

[0068] The napped fiber length of the napped artificial leather of the present embodiment is 250 μm or less. By making the napped fiber length 250 μm or less, the napped fibers can have a uniform length in a finely dispersed state, and a napped surface with excellent softness and smooth touch can be formed. From the viewpoint of forming a napped surface with better softness and smooth touch, the napped fiber length is preferably 150 μm or less, more preferably 120 μm or less, and further preferably 100 μm or less. Moreover, from the viewpoint of preventing the exposure of the polymer elastic body at the bottom of the napped fibers, which is the main cause of the deterioration of the appearance, and maintaining the soft touch of the ultrafine fibers, the napped fiber length is preferably 40 μm or more, more preferably 50 μm or more, and further preferably 60 μm or more.

[0069] The thickness of the napped artificial leather of the present embodiment is not particularly limited, but is preferably 0.1 to 1.5 mm, more preferably 0.3 to 1.0 mm, from the viewpoint of obtaining a napped artificial leather having both high mechanical strength and excellent hand feel.

[0070] The weight per unit area of ​​the napped artificial leather is not particularly limited, but is preferably 100 to 1000 g / m from the viewpoint of obtaining a napped artificial leather having both high mechanical strength and excellent hand feel. 2 , more preferably 150~800 / m 2 .

[0071] The apparent density of the napped artificial leather of the present embodiment is preferably 0.35 g / cm 3 More preferably, 0.37 g / cm 3 More preferably, 0.38 g / cm 3 Above, preferably 0.70 g / cm 3 Below, more preferably 0.50 g / cm 3 Below, more preferably 0.48 g / cm 3 By making the apparent density 0.35 g / cm 3 The above can make the elasticity excellent, and can also prevent the fibers from being dragged out when the napped surface is rubbed, so that a beautiful napped appearance can be easily obtained. 3 The following results show that the flexibility is excellent.

[0072] <Nonwoven fabric>

[0073] The nonwoven fabric of this embodiment contains ultrafine fibers and a high molecular weight elastic body. From the viewpoint of having a feel close to that of natural leather and obtaining high mechanical strength, the nonwoven fabric preferably has a structure in which a plurality of ultrafine fibers form fiber bundles entangled with each other (three-dimensional entangled body).

[0074] In addition, from the viewpoint of easily obtaining high mechanical strength and simplifying the production process, the nonwoven fabric is preferably a spunbonded nonwoven fabric, and more preferably a spunbonded nonwoven fabric containing ultrafine long fibers.

[0075] It should be noted that the long fibers do not refer to short fibers that are intentionally cut after spinning, but refer to continuous fibers. Specifically, they refer to filaments or continuous fibers that are not intentionally cut into short fibers of about 3 to 80 mm in length.

[0076] The nonwoven fabric is preferably obtained by spinning sea-island type (matrix-domain type) composite fibers to obtain a web, subjecting the web to an entanglement treatment, and further subjecting the web to an ultrafine fiber treatment.

[0077] (Ultrafine fiber)

[0078] The ultrafine fibers of the present invention refer to fibers that have been ultrafinely refined by extracting and removing at least one polymer at an appropriate stage before or after impregnating a multi-component fiber (composite fiber) composed of at least two or more spinnable polymers with different chemical or physical properties with a high molecular weight elastomer. The multi-component fiber that produces the ultrafine fiber is an ultrafine fiber-generating fiber. Representative examples thereof include sea-island type composite fibers, multi-layer laminated composite fibers, radial laminated composite fibers, etc., obtained by sheet mixing (mixed spinning) methods, composite spinning methods, etc. Among them, sea-island type composite fibers are preferred from the perspective of less fiber damage during entangling treatment by needle punching, etc., and uniformity of the average fineness of the ultrafine fibers.

[0079] Examples of the resin constituting the ultrafine fibers contained in the nonwoven fabric of the present embodiment include: aromatic polyesters such as polyethylene terephthalate (hereinafter sometimes referred to as "PET"), modified PET such as isophthalic acid-modified PET, sulfonyl isophthalic acid-modified PET, and cationic dye-dyeable PET; aliphatic polyesters such as polylactic acid, polyethylene succinate, polybutylene succinate, polybutylene succinate adipate, and polyhydroxybutyrate-polyhydroxyvalerate resins; nylons such as nylon 6, nylon 66, nylon 10, nylon 11, nylon 12, and nylon 6-12; and fibers of polypropylene, polyethylene, polybutene, polymethylpentene, and chlorinated polyolefins. It should be noted that modified PET is PET obtained by replacing at least a part of the ester-forming dicarboxylic acid monomer units or diol monomer units of unmodified PET with substitutable monomer units. Specific examples of modified monomer units replacing dicarboxylic acid monomer units include units derived from isophthalic acid, sodium sulfoisophthalic acid, sodium sulfonaphthalene dicarboxylic acid, adipic acid, etc., which replace terephthalic acid units. In addition, specific examples of modified monomer units replacing diol monomer units include units derived from diols such as butanediol and hexanediol, which replace ethylene glycol units.

[0080] Among them, from the viewpoint of obtaining a napped artificial leather having both colorability, high mechanical strength and excellent hand feel, polyester resins such as aromatic polyesters and aliphatic polyesters are preferred. In addition, from the viewpoint of productivity and mechanical strength during spinning, modified PET such as polyethylene terephthalate (PET), isophthalic acid-modified PET, sulfonic acid isophthalic acid-modified PET, cationic dye-dyeable PET, polybutylene terephthalate, polyhexylene terephthalate, etc.; aliphatic polyesters such as polylactic acid, polyethylene succinate, polybutylene succinate, polybutylene succinate adipate, polyhydroxybutyrate-polyhydroxyvalerate resin, etc.; nylons such as nylon 6, nylon 66, nylon 10, nylon 11, nylon 12, nylon 6-12, etc.; polyolefins such as polypropylene, polyethylene, polybutene, polymethylpentene, chlorinated polyolefins, etc. are preferred.

[0081] From the viewpoint of obtaining a napped artificial leather having excellent density of the napped surface, softness and elasticity, the average fineness (average fiber diameter) of the ultrafine fibers is preferably 0.01 to 1.0 dtex, more preferably 0.05 to 0.7 dtex, and further preferably 0.1 to 0.5 dtex.

[0082] The resin constituting the ultrafine fiber of the present embodiment may contain various additives within the range not impairing the effects of the present invention. Examples of the additives include catalysts, colorants, heat-resistant agents, flame retardants, lubricants, antifouling agents, fluorescent whitening agents, matting agents, gloss improvers, antistatic agents, fragrances, deodorants, antibacterial agents, tick repellents, inorganic fine particles, and the like.

[0083] <Polymer elastomer>

[0084] As the high molecular weight elastic body contained in the nonwoven fabric of the present embodiment, for example, polyurethane resin, acrylonitrile elastomer, olefin elastomer, polyester elastomer, polyamide elastomer, acrylic elastomer, their modified products, copolymers, mixtures, etc. Among them, polyurethane resin is preferred from the viewpoint of obtaining a napped artificial leather having excellent softness and elasticity.

[0085] Examples of the polyurethane resin include various polyurethane resins obtained by reacting a high molecular weight polyol having a weight average molecular weight of 200 to 6000, an organic polyisocyanate, and, if necessary, a chain extender at a predetermined molar ratio.

[0086] Specific examples of polymer polyols include: polyether polyols and copolymers thereof such as polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and poly(methyltetramethylene glycol); polyester polyols and copolymers thereof such as polybutylene adipate diol, polybutylene sebacate diol, polyhexamethylene adipate diol, poly(3-methyl-1,5-pentanediol adipate) diol, poly(3-methyl-1,5-pentanediol sebacate) diol, and polycaprolactone diol; polycarbonate polyols and copolymers thereof such as polyhexamethylene carbonate diol, poly(3-methyl-1,5-pentane carbonate) diol, polypentamethylene carbonate diol, and polytetramethylene carbonate diol; polyester carbonate polyols, etc. In addition, as required, polyfunctional alcohols such as trifunctional alcohols and tetrafunctional alcohols, or short-chain alcohols such as ethylene glycol can be used in combination. They can be used alone or in combination of two or more.

[0087] As a specific example of organic polyisocyanate, for example, non-yellowing diisocyanates such as aliphatic or alicyclic diisocyanates such as hexamethylene diisocyanate, isophorone diisocyanate, norbornene diisocyanate, and 4,4'-dicyclohexylmethane diisocyanate; aromatic diisocyanates such as 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 4,4'-diphenylmethane diisocyanate, and xylylene diisocyanate polyurethane, etc. In addition, as required, polyfunctional isocyanates such as trifunctional isocyanates and tetrafunctional isocyanates can be used in combination. They can be used alone or in combination of two or more.

[0088] Specific examples of chain extenders include: diamines such as hydrazine, ethylenediamine, propylenediamine, hexamethylenediamine, nonamethylenediamine, xylylenediamine, isophoronediamine, piperazine and its derivatives, adipic acid dihydrazide, isophthalic acid dihydrazide; triamines such as diethylenetriamine; tetraamines such as triethylenetetramine; diols such as ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, 1,4-bis(β-hydroxyethoxy)benzene, 1,4-cyclohexanediol; triols such as trimethylolpropane; amyl alcohols such as pentaerythritol; amino alcohols such as aminoethanol and aminopropanol, etc. These may be used alone or in combination of two or more. In addition, monoamines such as ethylamine, propylamine, and butylamine, carboxyl group-containing monoamine compounds such as 4-aminobutyric acid and 6-aminocaproic acid, and monoalcohols such as methanol, ethanol, propanol, and butanol may be used in combination with a chain extender during the chain extension reaction.

[0089] Specific examples of polyurethane resins include polycarbonate urethane, polyether urethane, polyester urethane, polyether ester urethane, polyether carbonate urethane, polyester carbonate urethane, etc. Among them, polycarbonate urethane is preferred from the viewpoint of obtaining napped artificial leather having excellent softness and elasticity.

[0090] The polymer elastic body may further contain additives such as pigments such as carbon black, colorants such as dyes, coagulation regulators, antioxidants, ultraviolet absorbers, fluorescent agents, mildew-proofing agents, penetrants, defoaming agents, lubricants, waterproofing agents, oil-proofing agents, thickeners, extenders, curing accelerators, foaming agents, water-soluble polymer compounds such as polyvinyl alcohol and carboxymethyl cellulose, inorganic fine particles, and conductive agents, within the range that does not impair the effects of the present invention. In particular, in the case of requiring the production of a small amount and a variety of napped artificial leathers, the polymer elastic body preferably does not contain colorants such as pigments and dyes from the viewpoint of suppressing contamination of the process caused by contamination of the pigments and dyes contained in the polymer elastic body and improving productivity.

[0091] [Method for producing napped artificial leather]

[0092] From the viewpoint of obtaining a napped artificial leather having both high mechanical strength and excellent hand feel while suppressing the occurrence of color unevenness, the method for producing the napped artificial leather of the present embodiment preferably includes the following steps 1 to 5.

[0093] Process 1: Process of obtaining the net

[0094] Process 2: Process of performing a mesh bonding treatment to obtain a mesh bonding process

[0095] Step 3: Step of obtaining an entangled network containing a polymer elastic body

[0096] Step 4: Step of removing the sea component from the entangled network containing the polymer elastic body

[0097] Process 5: Polishing process

[0098] <Process 1>

[0099] Step 1 is a step of obtaining a web.

[0100] In the present embodiment, from the viewpoint of obtaining a napped artificial leather having both high mechanical strength and excellent hand feel while suppressing the occurrence of color unevenness, the step of obtaining a web is preferably to obtain a web by melt spinning the sea-island type composite fibers.

[0101] As methods for obtaining a web by melt-spinning the island-in-sea type composite fibers, there are mentioned: a method of obtaining a web of long fibers by spinning by a spunbond method and capturing the island-in-sea type composite fibers on a web without cutting them; a method of obtaining a web of short fibers by crimping and cutting the melt-spun island-in-sea type composite fibers and carding the short fibers of the obtained island-in-sea type composite fibers, etc. Among them, from the viewpoints of mechanical strength, ease of adjustment of the entangled state, softness, elasticity, etc., a method of forming a web of long fibers by spinning by a spunbond method and capturing the island-in-sea type composite fibers on a web without cutting them (hereinafter sometimes referred to as "a method of forming a web of long fibers") is preferred.

[0102] It should be noted that, in this specification, the spunbonding method refers to a method in which a molten strand of sea-island type composite fibers is continuously ejected from the spinning nozzle at a given ejection speed using a composite spinning nozzle having a plurality of nozzle holes arranged in a given pattern, and the molten strand is stretched while being cooled using a high-speed airflow and deposited on a conveyor-like moving net.

[0103] The web of long fibers formed by the spunbond method may be subjected to a melt-bonding treatment in order to impart morphological stability. The method of forming the web of long fibers will be described in detail below.

[0104] In order to form a long fiber web, the fiber length of the sea-island type composite fiber before melt spinning and before ultrafine fiberization is preferably 100 mm or more, and may be several meters, hundreds of meters, several kilometers or more as long as it is technically possible to manufacture and will not be inevitably cut in the manufacturing process. It should be noted that in the subsequent process, i.e., the needle punching and grinding process during the entanglement treatment, part of the long fibers may be inevitably cut into short fibers.

[0105] Examples of the resin of the island component that will later become the ultrafine fiber contained in the sea-island type composite fiber include the same resin as the resin constituting the ultrafine fiber in the above-mentioned "ultrafine fiber".

[0106] As the resin of the sea component contained in the island-in-sea composite fiber and removed by extraction, decomposition, etc., it is preferred to use a resin that has different solubility or decomposability from the resin of the island component and has low compatibility. Such a resin is preferably appropriately selected according to the type and production method of the resin of the island component.

[0107] Examples of the sea component resin include olefin resins such as polyethylene, polypropylene, ethylene-propylene copolymers, and ethylene-vinyl acetate copolymers, resins that are soluble in organic solvents and can be dissolved and removed by organic solvents such as polystyrene, styrene-acrylic acid copolymers, and styrene-ethylene copolymers, and water-soluble resins such as water-soluble polyvinyl alcohol. Among them, from the viewpoint of being able to melt-spin the island component resin with a high intrinsic viscosity, a resin that can be dissolved and removed by an organic solvent is preferred, and polyethylene is more preferred.

[0108] From the viewpoint of mechanical strength, the mass ratio of the sea component to the island component (sea component / island component) contained in the sea-island type composite fiber is preferably 10 / 90 to 60 / 40, more preferably 20 / 80 to 50 / 50.

[0109] From the viewpoint of forming a fiber bundle of ultrafine fibers having appropriate voids, the number of island components that later become ultrafine fibers in the cross section of the sea-island type composite fiber during melt spinning is preferably 5 to 200, more preferably 10 to 50, and even more preferably 10 to 30.

[0110] As needed, the island-type composite fiber may contain dark pigments such as carbon black, white pigments such as zinc white, lead white, zinc lithopone, titanium dioxide, precipitated barium sulfate and barite powder, weathering agents, mildew inhibitors, anti-hydrolysis agents, lubricants, microparticles, friction resistance adjusters, etc., within the range that does not impair the effects of the present invention.

[0111] The web obtained by melt-spinning the sea-island type composite fibers can be subjected to a shrinkage treatment by immersing the web in warm water at about 60 to 150° C. to make the web dense in the entangled state.

[0112] <Process 2>

[0113] Step 2 is a step of subjecting the web to an enmeshing treatment to obtain an enmeshed web.

[0114] Step 2 is a step of laminating the webs obtained in step 1 and subjecting them to an entanglement treatment such as needle punching or water jet entanglement treatment to obtain an entangled web in which the long fibers are entangled in the thickness direction. The number of layers of the superimposed web is not particularly limited, but is preferably 4 or more layers, more preferably 8 or more layers, from the viewpoint of mechanical strength, and is preferably 20 or less layers, more preferably 16 or less layers, from the viewpoint of ease of production.

[0115] When needle punching is used as the entanglement treatment, the type of felt needle used is not particularly limited. From the viewpoint of sufficiently improving the entanglement of the fibers in the thickness direction and obtaining an artificial leather having excellent mechanical strength, it is preferred to use a thin felt needle, a single hook needle, or a felt needle with a small number of hooks. From the viewpoint of suppressing the cutting of the fibers, the number of hooks of the felt needle is preferably 3 or more, more preferably 5 or more, and even more preferably 6.

[0116] The number of felt needles per unit area used in the needle punching is not particularly limited, but is preferably 200 to 5500 / cm 2 In particular, from the perspective of improving mechanical strength, aligning the fibers on the surface in the longitudinal direction, and reducing the surface area ratio of the high molecular weight elastic body to the given range of the present invention, 1500 to 5000 fibers / cm are preferred. 2 .

[0117] In any stage from the spinning of the sea-island type composite fibers to the entanglement treatment, an oil agent or an antistatic agent may be applied to the web or the entangled web.

[0118] The weight per unit area of ​​the entangled web is preferably 100 to 2000 g / m from the viewpoint of obtaining a napped artificial leather having both high mechanical strength and excellent hand feel. 2 .

[0119] In addition, from the viewpoint of further increasing the fiber density and degree of entanglement of the entangled web, a heat shrinkage treatment may be performed.

[0120] In order to further densify the entangled web densified by heat shrinkage treatment, fix the morphology of the entangled web, make the surface smoother, etc., for example, the web may be pressed with a hot roll having a surface temperature of 100 to 150° C., or may be pressed with a cooling roll having a surface temperature below the softening point of the resin heated to a temperature above the softening point of the resin constituting the fibers (island components) in the entangled web. In particular, from the viewpoint of making the surface smoother, the surface temperature of the cooling roll is preferably 30° C. or more lower than the softening point of the resin.

[0121] <Process 3>

[0122] Step 3 is a step of impregnating the entangled web with a polymer elastic body to obtain an entangled web containing the polymer elastic body.

[0123] In the method for producing napped artificial leather of the present embodiment, it is preferred to impregnate the leather with a polymer elastic body before removing the sea component from the viewpoint of obtaining a napped artificial leather having excellent form stability, flexibility and elasticity.

[0124] Thus, by impregnating the high molecular weight elastic body before removing the sea component, the sea component can be removed and gaps can be formed between the ultrafine fibers forming the fiber bundle after the sea component is removed. As a result, the ultrafine fibers inside the fiber bundle are not easily constrained by the high molecular weight elastic body, that is, the ultrafine fibers are not easily affected by the high molecular weight elastic body, and a napped artificial leather with excellent softness can be obtained.

[0125] In step 3, the entangled web is impregnated with the polymeric elastic body using an emulsion or solution containing the polymeric elastic body, and then the polymeric elastic body is coagulated to obtain the entangled web containing the polymeric elastic body. By coagulating the polymeric elastic body, the polymeric elastic body can be provided to the gaps between the fibers of the entangled web.

[0126] The method of impregnating the entangled web with the polymeric elastic body using an emulsion or a solution containing the polymeric elastic body is not particularly limited, but a method of impregnating the entangled web by a dipping and sandwiching method is preferred.

[0127] Examples of the polymer elastic body include the polymer elastic bodies described in the above-mentioned <Polymer elastic body>, and polyurethane-based resins are preferred.

[0128] In addition, when impregnating the polymer elastomer, it is preferred to use a solution containing the polymer elastomer, and it is more preferred to use a solvent-based polyurethane obtained by dissolving a polyurethane resin in a solvent such as N,N-dimethylformamide (DMF) to obtain an entangled web containing the polymer elastomer. In this way, by using a solution containing the polymer elastomer, especially a solvent-based polyurethane, it is easy to appropriately release the polyurethane as the polymer elastomer and the ultrafine fibers to obtain a napped artificial leather with a soft feel.

[0129] In order to make the area ratio of the polymer elastic body present on the napped surface 17% or less, the entangled web may be pretreated before being impregnated with the polymer elastic body, or the polymer elastic body may be selectively removed from the entangled web after being impregnated with the polymer elastic body.

[0130] Examples of pretreatment of the entangled web include: a method of coating or impregnating the entangled web with a thermoplastic resin such as polyvinyl alcohol; a method of making the thermoplastic resin present on the surface of the entangled web or in the entangled web by a gravure coating method, a knife coating method, a pipe coating method, a comma coater method, or the like.

[0131] Examples of a method for selectively removing the polymer elastic body include a method of removing the polymer elastic body by applying contact pressure to the surface of the entangled web using a nip roll, a squeeze bar, a doctor blade, or the like.

[0132] In the present embodiment, it is preferred to impregnate the polymer elastomer into the intermeshing web in such a manner that the content of the polymer elastomer in the napped artificial leather reaches 15 to 35% by mass, and after obtaining the intermeshing web containing the polymer elastomer, the polymer elastomer is selectively removed from the intermeshing web in such a manner that the area ratio of the above-mentioned polymer elastomer present on the napped surface reaches less than 17%.

[0133] Examples of a method for coagulating the elastic polymer include a method of coagulating by removing water contained in an emulsion or a solution by drying, and a method of performing wet coagulation.

[0134] Examples of methods for drying and removing to solidify include a method of heat treating in a drying device at 50 to 200° C., a method of heat treating in a dryer after infrared heating, a method of heat treating in a dryer after steam treatment, or a method of heat treating in a dryer after ultrasonic heating, as well as a method combining these methods.

[0135] As a method for wet coagulation, the entangled body network containing the polymer elastic body is immersed in a treatment bath containing a poor solvent for the polymer elastic body, so that the polymer elastic body is coagulated into a porous state. It is preferable to use water as the poor solvent for the polymer elastic body. For example, when a polyurethane resin is used as the polymer elastic body, if a treatment bath in which a good solvent for the polymer elastic body such as dimethylformamide (DMF) is mixed with water, the coagulation state, that is, the size, number, shape, etc. of the large number of pores formed can be controlled by appropriately setting the mixing ratio, which is preferred.

[0136] When the polymer elastic body is provided using an emulsion containing the polymer elastic body, if a thermosensitive gelling agent is added in advance, more uniform solidification in the thickness direction can be achieved by a dry method or by combining a method such as steam heating or far infrared heating with a dry method.

[0137] In addition, when a solution containing an organic solvent and a polymer elastic body is used to impart a polymer elastic body, more uniform pores can be obtained by using a coagulation adjusting agent in combination. In addition, examples of the above-mentioned organic solvent include dimethylformamide, dimethylacetamide, dimethyl sulfoxide, etc. By coagulating the polymer elastic body contained in the entangled network into a porous state, a feel similar to that of natural leather can be obtained.

[0138] Among these, a method of wet coagulation is preferred, and a method of immersing the entangled web in a treatment solution obtained by mixing dimethylformamide as an organic solvent with water to coagulate the web is more preferred.

[0139] <Step 4>

[0140] Step 4 is a step of removing the sea component from the entangled web containing the polymer elastic body. By removing the sea component, the fibers that can be micronized can be converted into fiber bundles of microfibers. That is, the fibers in the entangled web are microfiberized to obtain a nonwoven fabric containing microfibers and a polymer elastic body (hereinafter sometimes referred to as a nonwoven fabric containing a polymer elastic body).

[0141] As a method of removing the resin of the sea component, for example, there is a method of removing using a solvent or a decomposing agent that can selectively remove only the resin of the sea component.

[0142] In the present embodiment, polyethylene is preferably used from the viewpoint of being able to melt-spin the island component resin having a high intrinsic viscosity. From this point of view, it is preferred to dissolve and remove the sea component with an organic solvent.

[0143] When the resin of the island component is a polyamide resin or a polyester resin and the resin of the sea component is polyethylene, examples of the organic solvent for dissolving and removing the sea component include toluene, trichloroethylene, tetrachloroethylene and the like.

[0144] When removing the sea component, it is preferable to simultaneously perform an immersion and clamping treatment.

[0145] In addition, the fibers may be densified by subjecting the sea-island type composite fibers to a heat shrinkage treatment (fiber shrinkage treatment) using steam, hot water, dry heat, or the like during the period from melt spinning to obtaining a web to removing the sea component.

[0146] For nonwoven fabrics containing a high molecular weight elastic body, it is preferred to dry the fabric after removing the sea component resin. Examples of the method include a method of heat treating in a drying device at 50 to 200°C, a method of heat treating in a dryer after infrared heating, a method of heat treating in a dryer after steam treatment, or a method of heat treating in a dryer after ultrasonic heating, and a method of combining these methods.

[0147] Furthermore, the nonwoven fabric containing the polymer elastic body can be cut into a predetermined thickness as required.

[0148] In addition, from the viewpoint of mechanical strength, the weight per unit area of ​​the nonwoven fabric containing the polymer elastic body is preferably 140 to 3000 g / m 2 , more preferably 200 to 2000 g / m 2 .

[0149] <Step 5>

[0150] Step 5 is a step of subjecting the nonwoven fabric containing the high molecular weight elastic body obtained in step 4 to a grinding treatment.

[0151] By grinding one or both sides of a non-woven fabric containing a polymer elastomer, the fibers on the surface of the non-woven fabric stand up, and a napped artificial leather with a napped surface can be obtained. The grinding treatment is preferably performed using sandpaper or corundum paper with a grit number of 120 to 600, and more preferably using sandpaper or corundum paper with a grit number of 320 to 600. In this way, a napped artificial leather with a napped surface on one or both sides can be obtained. The length of the napped fibers can be adjusted by appropriately adjusting the sandpaper grit number, corundum paper grit number, paper rotation speed, contact length, contact pressure, etc. When the paper rotation speed, contact length, and contact pressure are increased, the length of the napped fibers can be shortened.

[0152] For raised nap artificial leather, in order to further improve the feel, finishing treatments such as shrinkage processing to impart softness, kneading softening treatment, reverse sealing brushing treatment, anti-fouling treatment, hydrophilization treatment, lubricant treatment, softener treatment, antioxidant treatment, ultraviolet absorber treatment, fluorescent agent treatment, flame retardant treatment, etc. can be implemented.

[0153] The napped artificial leather of this embodiment can be colored, preferably using dyes or pigments. In order to fix, it needs to be used in combination with resins, etc. Compared with pigments that tend to harden, it is preferred to use dyes for dyeing because it is not necessary to use resins in combination in order to enter the fibers, there are fewer risks of reduced feel, and it is easy to adjust the type and concentration of the dye and simply color it into various colors.

[0154] As dye, for example, when the ultrafine fiber is formed by polyester resin, it is preferably dyed with disperse dyes and cationic dyes. As specific examples of disperse dyes, for example: phenylazo dyes (monoazo, disazo, etc.), heterocyclic azo dyes (thiazolylazo, benzothiazoleazo, quinolineazo, pyridineazo, imidazoleazo, thiopheneazo, etc.), anthraquinone dyes, condensation dyes (quinophthalone, styryl, coumarin, etc.), etc. These dyes are commercially available as dyes with a "Disperse" prefix, for example. They can be used alone or in combination of two or more. In addition, as a dyeing method, a high-pressure liquid flow dyeing method, a jigger dyeing method, a hot melt adhesive continuous dyeing machine method, a dyeing method using a sublimation printing method, etc. can be used.

[0155] Example

[0156] Hereinafter, the present invention will be described in more detail using Examples and Comparative Examples, but the present invention is not limited to the following Examples.

[0157] [evaluate]

[0158] <Average fineness>

[0159] The napped artificial leather was cut along the thickness direction, and the cross section was photographed at 3000 times using a scanning electron microscope (SEM) (S-3000N manufactured by Hitachi, Ltd.). 15 ultrafine fibers were randomly selected from the obtained image, and their cross-sectional areas were measured. Then, the average value of the cross-sectional areas (the average value of 15) was calculated, and the average fineness was calculated from the average value of the cross-sectional areas and the density of the resin constituting the ultrafine fibers.

[0160] <Length of standing fiber>

[0161] After arranging the napped fibers on the napped surface of the napped artificial leather into reverse naps along the thickness direction using a brush, the cross section of the napped artificial leather is photographed at a magnification of 40 times using a scanning electron microscope (SEM). In the obtained image, a line L1 is drawn at the root of the ultrafine fibers in the nonwoven fabric or at the upper limit of the existence of the polymer elastic film when the polymer elastic film is formed, and a line L2 is drawn at the upper limit of the fiber nap closest to the observation surface. Furthermore, a plurality of lines L3 are drawn at intervals of 200 μm in a direction perpendicular to the surface of the napped artificial leather.

[0162] Ten lengths of line L3 from line L1 to line L2 were measured, and their arithmetic mean was calculated.

[0163] The above operation was performed at 10 randomly selected locations of the napped artificial leather, and the arithmetic mean values ​​of the 10 locations were calculated and rounded off to the first decimal place, and the obtained value was defined as the napped fiber length (μm).

[0164] A conceptual diagram for explaining a method for measuring the nap fiber length of napped artificial leather is shown in Figure 3 .

[0165] <Content of polymer elastomer>

[0166] A small piece was cut from the napped artificial leather, and its weight (W1) was measured. The small piece was immersed in dimethylformamide for 12 hours, pressed, and then immersed in dimethylformamide for 5 minutes, pressed, and the above action was repeated 5 times to extract the polymer elastomer. Then, the non-woven fabric after the polymer elastomer was extracted was dried, and the weight (W2) of the dried non-woven fabric was measured. Then, the content (B) of the polymer elastomer was calculated according to the following formula.

[0167] (B) = (W1-W2) / W1×100 (mass%)

[0168] <Area ratio of polymer elastic body>

[0169] For the napped surface of the napped artificial leather, three images were taken at different locations using a scanning electron microscope (SEM) at a magnification of 50 times, and each image was printed on an A4-sized paper. The printed paper was then overlapped on an OHP (Overhead Projector) sheet, and the polymer elastic body portion was painted black and transferred to the OHP sheet. The pattern of the OHP sheet after the polymer elastic body portion was painted black was formed into an acquired image using a scanner.

[0170] Next, the total area of ​​the region where the polymer elastic body exists in the obtained image was calculated using the image processing software Image-Pro Premier 9.2 (image-pro plus, manufactured by MediaCybernetics). The area ratio of the polymer elastic body was calculated by the following formula based on the calculated total area and the total area of ​​all regions in the image.

[0171] Area ratio of polymer elastic body = total area of ​​the region where the polymer elastic body exists / total area of ​​the entire image region × 100 (%)

[0172] exist Figure 1 The image obtained by scanning electron microscope (SEM) at a magnification of 50 times the vertical hair surface is shown in FIG. Figure 2 It is shown in Figure 1 An image obtained by painting a polyurethane portion of the image, which is a high molecular weight elastic body, black and transferring the polyurethane portion to an OHP sheet.

[0173] <Apparent density>

[0174] According to JIS L 1096:2010, thickness (mm) and unit area weight (g / cm 2 ) were measured and the apparent density (g / cm 3 ).

[0175] <Tensile Strength>

[0176] Using a test piece of 2.5 cm×16 cm cut out from the napped artificial leather, a stress-strain curve was obtained in accordance with JIS L1096:2010 8.14.1 “Tensile strength test”.

[0177] As the test pieces, three test pieces cut along the long side direction in the longitudinal direction of the napped artificial leather and three test pieces cut along the long side direction in the transverse direction were used.

[0178] Based on the stress-strain curve obtained using each test piece, the stress at the time of fracture was read, and the average value of the stress of 3 test pieces cut along the long side in the longitudinal direction and the average value of the stress of 3 test pieces cut along the long side in the transverse direction were calculated, and the lower value (average value) was taken as the tensile strength.

[0179] <Appearance>

[0180] The appearance of the napped artificial leather was evaluated according to the following criteria.

[0181] A: No or only a very small amount of the polymer elastic body present on the napped surface is visually recognized, color unevenness is suppressed, and color development is excellent.

[0182] B: The polymer elastic body present on the napped surface was visually recognized in an uneven state, and color unevenness occurred.

[0183] <Density>

[0184] The density of the raised nap artificial leather was evaluated by visual observation and touch according to the following criteria.

[0185] A: The erect hairs are finely dispersed, have uniform length, and feel smooth.

[0186] B: The erect hairs are roughly scattered, have uneven lengths, feel rough, and have no luster.

[0187] <Feel>

[0188] The texture of the napped artificial leather when folded was evaluated by visual observation and touch according to the following criteria.

[0189] A: Excellent in softness, elasticity, etc.

[0190] B: At least one of the flexibility and elasticity is poor.

[0191] (Example 1)

[0192] Polyethylene terephthalate (PET) was prepared as the island component, and polyethylene was prepared as the sea component. A melt composite nozzle with 12 islands was used, and the pressure was adjusted so that the mass ratio of the sea component / island component reached 35 / 65. The nozzle temperature was set to 280°C and the single-hole ejection was 1.2 g / min. Sea-island type composite fibers with a fineness of 3dtex were spun at a spinning speed of 4000 m / min.

[0193] The obtained sea-island composite fibers were continuously deposited on a movable net and gently pressed with a heated metal roll to suppress the fluff on the surface from rising. Then, the sea-island composite fibers were peeled off from the net and passed between the heated metal roll and the back roll under pressure to produce a 40 g / m2 2 A web of long fibers.

[0194] Twelve sheets of the obtained nets were stacked to form a stacked net. Then, a 6-hook needle was used at 2050 needles / cm 2 The laminated web was needle punched at a needle punching density of 600 g / m 2 The obtained entangled web was shrunk in hot water at 90°C, dried and hot pressed to obtain a web with a unit area weight of 800 g / m 2 Heat-shrinkable mesh.

[0195] Next, the heat-shrinked entangled web was impregnated with a DMF solution (solid content 15% by mass) of a polycarbonate polyurethane having a 100% modulus of 4.5 MPa as a polymer elastic body so that the content of the polymer elastic body in the napped artificial leather reached 18% by mass. After the impregnation, a contact pressure was applied so that the area ratio of the polycarbonate polyurethane present on the napped surface reached 5% to selectively remove the polycarbonate polyurethane present on the surface of the entangled web, and then, the polycarbonate polyurethane was coagulated by immersing it in a DMF aqueous solution having a mass ratio of water to DMF of 70:30, thereby imparting a polycarbonate polyurethane (polyurethane resin) to the entangled web.

[0196] Next, the entangled web with the polyurethane resin applied was immersed in toluene at 85°C while being clamped to dissolve and remove the polyethylene as the sea component, and then dried to obtain a nonwoven fabric containing ultrafine polyester fibers and with the polyurethane resin applied as a high molecular weight elastic body. The nonwoven fabric obtained had a unit weight of 600 g / m 2 .

[0197] In order to make an artificial leather fabric, the obtained nonwoven fabric was half-cut in the thickness direction, and the half-cut side was polished with sandpaper of ♯180 and ♯240. Then, for the non-half-cut surface, the ground side was polished with sandpaper of ♯320 and ♯600, thereby obtaining a raised-hair artificial leather with a raised-hair surface.

[0198] Next, the disperse dye was adjusted to a dye concentration of 6% owf, and the obtained napped artificial leather was subjected to high pressure dyeing at 130° C. using a circular dyeing machine, followed by reduction washing, oxidation treatment, and water washing to obtain a colored napped artificial leather. The evaluation results of the colored napped artificial leather are shown in Table 1.

[0199] (Example 2)

[0200] In Example 1, the polycarbonate polyurethane on the napped surface was selectively removed by applying contact pressure so that the area ratio of the polycarbonate polyurethane on the napped surface reached 9.3%, instead of selectively removing the polycarbonate polyurethane on the napped surface by applying contact pressure so that the area ratio of the polycarbonate polyurethane on the napped surface reached 5%. A colored napped artificial leather was obtained in the same manner. The evaluation results are shown in Table 1.

[0201] (Example 3)

[0202] In Example 1, except that the polishing treatment was performed to obtain a napped artificial leather having a thickness of 0.4 mm, a colored napped artificial leather was obtained in the same manner. The evaluation results are shown in Table 1.

[0203] (Example 4)

[0204] In Example 1, the heat-shrinked entangled web was impregnated with a DMF solution (solid content 18.5%) of a polycarbonate polyurethane with a 100% modulus of 4.5 MPa as the polymer elastomer so that the content of the polymer elastomer in the fuzzy artificial leather reached 32% by mass, instead of impregnating the heat-shrinked entangled web with a DMF solution (solid content 15%) of a polycarbonate polyurethane with a 100% modulus of 4.5 MPa as the polymer elastomer so that the content of the polymer elastomer in the fuzzy artificial leather reached 18% by mass, and a colored fuzzy artificial leather was obtained in the same manner. The evaluation results are shown in Table 1.

[0205] (Example 5)

[0206] In Example 1, the obtained nonwoven fabric was polished on one side with sandpaper of ♯180 and ♯240 to make an artificial leather fabric, and then the ground side was polished with sandpaper of ♯320 and ♯600 on the non-treated side to obtain a napped artificial leather having a thickness of 1.0 mm and having a napped surface. In addition, a colored napped artificial leather was obtained in the same manner. The evaluation results are shown in Table 1.

[0207] (Example 6)

[0208] Polyethylene terephthalate (PET) was prepared as the island component, and polyethylene was prepared as the sea component. A melt composite nozzle with 16 islands was used to adjust the pressure so that the mass ratio of the sea component / island component reached 35 / 65. The nozzle temperature was set to 280°C and the single-hole ejection was 1.2 g / min. After spinning at a spinning speed of 820 m / min, the fibers were stretched and curled to obtain sea-island type composite fibers of short fibers with a fineness of 4.0 dtex.

[0209] Next, the sea-island type composite fibers were passed through a carding machine to produce a web of short fibers.

[0210] A plurality of the obtained nets were stacked to form a stacked net. Then, a single hook needle was used to cut the net at 2050 needles / cm. 2 The laminated web is needle punched with a needle punching density of 600 g / m 2 The obtained entangled web was shrunk by hot water at 90°C, dried and hot pressed to obtain a web with a unit area weight of 800 g / m 2 Heat-shrinkable mesh.

[0211] Next, the heat-shrinked entangled web was impregnated with a DMF solution (solid content 15% by mass) of a polycarbonate polyurethane having a 100% modulus of 4.5 MPa as a polymer elastic body so that the content of the polymer elastic body in the napped artificial leather reached 18% by mass. After the impregnation, a contact pressure was applied so that the area ratio of the polycarbonate polyurethane present on the napped surface reached 5% to selectively remove the polycarbonate polyurethane present on the surface of the entangled web, and then the web was immersed in a DMF aqueous solution having a mass ratio of water:DMF of 70:30 to solidify the polycarbonate polyurethane, thereby imparting the polycarbonate polyurethane (polyurethane resin) to the entangled web.

[0212] Next, the entangled web with the polyurethane resin was immersed in toluene at 85°C while being clamped to dissolve and remove the polyethylene as the sea component, and then dried to obtain a nonwoven fabric containing ultrafine polyester fibers and with the polyurethane resin as the high molecular weight elastic body. The nonwoven fabric had a unit weight of 820 g / m 2 .

[0213] (Comparative Example 1)

[0214] In Example 1, the polycarbonate polyurethane on the napped surface was selectively removed by applying contact pressure so that the area ratio of the polycarbonate polyurethane on the napped surface reached 17.6%, instead of selectively removing the polycarbonate polyurethane on the napped surface by applying contact pressure so that the area ratio of the polycarbonate polyurethane on the napped surface reached 5%. A colored napped artificial leather was obtained in the same manner. The evaluation results are shown in Table 1.

[0215] (Comparative Example 2)

[0216] In Example 1, the polycarbonate polyurethane on the napped surface was selectively removed by applying contact pressure so that the area ratio of the polycarbonate polyurethane on the napped surface reached 14.8%, instead of selectively removing the polycarbonate polyurethane on the napped surface by applying contact pressure so that the area ratio of the polycarbonate polyurethane on the napped surface reached 5%, and the napped fiber length was adjusted to 250 μm during the polishing process, and a colored napped artificial leather was obtained in the same manner. The evaluation results are shown in Table 1.

[0217] (Comparative Example 3)

[0218] In Example 1, a DMF solution (solid content 15%) of a polycarbonate polyurethane with a modulus of 4.5 MPa, to which carbon black was added and colored in such a manner that the content reached 1.0 mass%, was used instead of a DMF solution (solid content 15%) of a polycarbonate polyurethane with a modulus of 4.5 MPa, and in addition, contact pressure was applied in such a manner that the area ratio of the polycarbonate polyurethane present on the napped surface reached 18.4% to selectively remove the polycarbonate polyurethane present on the entangled web, instead of selectively removing the polycarbonate polyurethane present on the nonwoven surface by applying contact pressure in such a manner that the area ratio of the polycarbonate polyurethane present on the napped surface reached 5%, and a colored napped artificial leather was obtained in the same manner. The evaluation results are shown in Table 1.

[0219] (Comparative Example 4)

[0220] In Example 1, polyvinyl alcohol was used as a sea component instead of polyethylene, and the polyethylene as a sea component was dissolved and removed by immersion in hot water instead of immersion in toluene to dissolve and remove the polyethylene, so that the content of the polymer elastic body in the napped artificial leather reached 10% by mass, and the heat-shrinked entangled web was impregnated with 100% of a self-emulsifying amorphous polycarbonate polyurethane emulsion solution (solid content 15% by mass) with a modulus of 3.0 MPa, instead of impregnating the heat-shrinked non-woven fabric with 100% of a DMF solution (solid content 15%) of a polycarbonate polyurethane with a modulus of 4.5 MPa in a manner to reach 18% by mass. The colored napped artificial leather was obtained in the same manner. The evaluation results are shown in Table 1.

[0221] (Comparative Example 5)

[0222] Polyethylene terephthalate (PET) was prepared as the island component, and polyethylene was prepared as the sea component. A melt composite nozzle with 16 islands was used to adjust the pressure so that the mass ratio of the sea component / island component reached 35 / 65. The nozzle temperature was set to 280°C and the single-hole ejection was 1.2 g / min. After spinning at a spinning speed of 820 m / min, the fibers were stretched and curled to obtain sea-island type composite fibers of short fibers with a fineness of 3.6 dtex.

[0223] The obtained sea-island type composite fibers were passed through a carding machine to produce a web of short fibers.

[0224] A plurality of the obtained nets were stacked to form a stacked net. Then, a single hook needle was used to cut the net at 2050 needles / cm. 2 The laminated web is needle punched with a needle punching density of 600 g / m 2 The obtained entangled web was shrunk by hot water at 90°C, dried and hot pressed to obtain a web with a unit area weight of 800 g / m 2 Heat-shrinkable mesh.

[0225] Next, the heat-shrinked entangled web was impregnated with a DMF solution (solid content 15% by mass) of a polycarbonate polyurethane having a 100% modulus of 4.5 MPa as a polymer elastic body so that the content of the polymer elastic body in the napped artificial leather reached 40% by mass. After the impregnation, a contact pressure was applied so that the area ratio of the polycarbonate polyurethane present on the napped surface reached 5% to selectively remove the polycarbonate polyurethane present on the surface of the entangled web, and then the web was immersed in a DMF aqueous solution having a water:DMF mass ratio of 70:30 to solidify the polycarbonate polyurethane, thereby imparting the polycarbonate polyurethane (polyurethane resin) to the entangled web.

[0226] Next, the entangled web with the polyurethane resin was immersed in toluene at 85°C while being clamped to dissolve and remove the polyethylene as the sea component, and then dried to obtain a nonwoven fabric containing ultrafine polyester fibers and with the polyurethane resin as the high molecular weight elastic body. The nonwoven fabric had a unit weight of 654 g / m 2 .

[0227] In order to prepare an artificial leather fabric, the obtained nonwoven fabric was cut in half in the thickness direction, and the half-cut side was polished with sandpaper of ♯180 and ♯240. Then, for the non-half-cut side, the ground side was polished with sandpaper of ♯320 and ♯600, thereby obtaining a raised-hair artificial leather with a raised-hair side.

[0228] Next, the disperse dye was adjusted to a dye concentration of 6% owf, and the obtained napped artificial leather was subjected to high pressure dyeing at 130° C. using a circular dyeing machine, followed by reduction washing, oxidation treatment, and water washing to obtain a colored napped artificial leather. The evaluation results of the colored napped artificial leather are shown in Table 1.

[0229]

[0230] In the napped artificial leathers obtained in Examples 1 to 6, no or only a very small amount of the high molecular weight elastic body (polyurethane resin) was visually recognized from the napped surface, and uneven dyeing was suppressed, and the color development was excellent. In addition, the napped hairs were finely dispersed, had uniform length, and had a smooth touch.

[0231] On the other hand, the content of the polymer elastomer in the napped artificial leather obtained in Comparative Example 1 is in the range of 15 to 35% by mass, and the napped fiber length is less than 250 μm, but the area ratio of the polymer elastomer present on the napped surface exceeds 17%, and the polymer elastomer (polyurethane resin) is visually recognized in an uneven state from the napped surface, resulting in uneven dyeing.

[0232] The content of the polymer elastomer in the napped artificial leather obtained in Comparative Example 2 is in the range of 15 to 35% by mass, and the area ratio of the polymer elastomer present on the napped surface is less than 17%, but the napped fiber length exceeds 250 μm, and the napped fibers are rough and loose with uneven length, rough to the touch, and lack luster.

[0233] The content of the polymer elastic body in the napped artificial leather obtained in Comparative Example 3 was in the range of 15 to 35% by mass, and the napped fiber length was 250 μm or less, but the area ratio of the polymer elastic body present on the napped surface exceeded 17%. Since the polymer elastic body contained carbon black, the uneven dyeing was slightly suppressed, but the uneven dyeing still occurred to a degree that could be visually recognized.

[0234] The area ratio of the polymer elastomer present on the nap surface of the napped artificial leather obtained in Comparative Example 4 is less than 17%, and the nap fiber length is less than 250 μm, but the polymer elastomer imparted to the non-woven fabric does not meet the lower limit of the range of 15 to 35% by mass. The napped artificial leather is a napped artificial leather with poor softness and elasticity and a hard feel.

[0235] The napped artificial leather obtained in Comparative Example 5 is a 0.4 mm thick napped artificial leather using short fibers, and the napped fiber length is less than 250 μm. However, the content of the polymer elastomer imparted to the non-woven fabric exceeds the upper limit of the range of 15 to 35% by mass, and the area ratio of the polymer elastomer present on the napped surface also exceeds 17%. The polymer elastomer (polyurethane resin) is visually recognized from the napped surface in an uneven state, uneven dyeing occurs, and it does not have sufficient mechanical strength.

Claims

1. A napped artificial leather comprising a nonwoven fabric and having a napped surface, wherein the nonwoven fabric contains ultrafine fibers and a high molecular weight elastic body, The content of the polymer elastomer is 15-35% by mass. The area ratio of the polymer elastic body present on the napped surface is 17% or less, The napped fibers have a length of 250 μm or less.

2. The napped artificial leather according to claim 1, wherein: The ultrafine fibers are polyester fibers.

3. The napped artificial leather according to claim 1 or 2, wherein: The average fineness of the ultrafine fibers is 0.01-1.0 dtex.

4. The napped artificial leather according to any one of claims 1 to 3, wherein The nonwoven fabric is a spunbonded nonwoven fabric.

5. A method for producing a napped artificial leather, which is the method for producing the napped artificial leather according to any one of claims 1 to 4, the method comprising: A step of removing a sea component from the entangled web containing the polymer elastic body to obtain a nonwoven fabric containing the polymer elastic body.

6. The method for manufacturing the napped artificial leather according to claim 5, comprising: A step of melt-spinning sea-island type composite fibers to obtain a web.

7. The method for producing napped artificial leather according to claim 6, wherein: In the step of obtaining the nonwoven fabric containing the polymer elastic body, the sea component is dissolved and removed using an organic solvent.

8. The method for producing a napped artificial leather according to any one of claims 5 to 7, comprising: A step of obtaining an entangled network containing the polymer elastic body using a solvent-based polyurethane.

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