JP2024025722A - Artificial leather - Google Patents

Abstract

[Problem] To provide artificial leather that has a low environmental impact because no organic solvent is used in the manufacturing process and has an excellent clarity of embossed pattern. [Solution] An artificial leather made of a nonwoven fabric made of ultrafine fibers with an average single fiber diameter of 0.3 μm or more and 7 μm or less, and water-dispersed polyurethane. When the free induction decay signal (FID) at 50°C is fitted for two components, the S component (Gaussian component) and the L component (Lorentzian component), the spin-spin relaxation time Tl of the L component is 500 μs or more and 800 μs or less. An artificial leather characterized in that the fraction Cl of the L component is 25% or more and less than 55%. [Selection diagram] None

Description

The present invention relates to artificial leather that has a low environmental impact because no organic solvent is used in the manufacturing process, and has an excellent embossed pattern clarity.

Artificial leather, which is mainly composed of fiber sheets such as nonwoven fabric (fibrous base material) and polyurethane (hereinafter also referred to as PU) resin, has easy care, functionality, and homogeneity that are difficult to achieve with natural leather. It has excellent characteristics and can be used for clothing, shoes, bags, interior materials, interior materials for seats such as automobiles, aircraft, and railway vehicles, and clothing materials such as ribbons and patch base materials. It is suitably used for. In these fields, the design can be further enhanced by embossing the surface of artificial leather. However, there is a problem in that the heat during embossing causes thermal decomposition and thermal contraction of the binder, making the embossed pattern unclear.

In order to solve this problem, a highly heat-resistant polycarbonate polyol is used as a raw material for the polyurethane resin that is impregnated into the fibrous base material in the leather-like sheet material.

In addition, conventional methods for manufacturing artificial leather include impregnating a fiber sheet with an organic solvent solution of PU resin, and then immersing it in a non-solvent of the PU resin (for example, water or an organic solvent) to wet the PU resin. A method of coagulation is generally employed. In this case, a water-miscible organic solvent such as N,N-dimethylformamide is used as the organic solvent for the polyurethane resin, but since organic solvents are highly harmful to the human body and the environment, artificial leather Regarding manufacturing, there is a strong demand for methods that do not use organic solvents.

Patent Document 1 below discloses a diol having two hydroxyl groups at one end and a polysiloxane side chain, two types of copolymerized polycarbonate diol, an organic diisocyanate, and a chain extender, mainly for the purpose of improving the texture of synthetic leather. Various polycarbonate-based PUs obtained by reaction with However, these polycarbonate polyurethanes are dissolved in N,N-dimethylformamide, and because they use organic solvents in the production of artificial leather, they have a high environmental impact and are highly harmful to the human body.

Patent Document 2 below describes a polyol obtained by transesterifying polycarbonate diol or polyester diol, a polyol having hydroxyl groups at both ends, an organic diisocyanate, and a chain. PU resins obtained by reaction with extenders have been proposed. However, because these PU resins contain a high proportion of cohesive groups such as urethane bonds and urea bonds, when the artificial leather obtained by attaching it to a fiber sheet is embossed, heat shrinkage occurs, resulting in a distinct It is difficult to provide an embossed pattern.

In addition, conventionally, it has been common practice to identify the structure of urethane resin by local structural analysis of the urethane resin itself (constituent isocyanate, chain extender, polyol monomer) using NMR, but this is not the case in the technical field of artificial leather. However, there was no known technology (method) that could evaluate the mobility of urethane resin in a solid state and non-destructively by attaching urethane resin to a polyester fiber sheet. Therefore, in the prior art, the relationship between the clarity of the embossed pattern of artificial leather and the mobility of the urethane resin contained as a binder in the artificial leather was not known.

At the level of such conventional technology, artificial leather obtained by impregnating a non-woven fabric using ultrafine fibers with PU resin has a low environmental impact as no organic solvent is used in the manufacturing process, and the embossed pattern has excellent clarity. Artificial leather is not yet available.

Patent No. 4506754 Patent No. 6582992

In view of the problems of the prior art described above, the problem to be solved by the present invention is to provide artificial leather that has a low environmental impact because no organic solvent is used in the manufacturing process, and has an excellent embossed pattern clarity. be.

As a result of intensive research and repeated experiments in order to solve the above-mentioned problem, the present inventors unexpectedly discovered that the problem could be solved by using artificial leather having the following characteristics, and thus completed the present invention. It is something that
That is, the present invention is as follows.
[1] Artificial leather made of a nonwoven fabric made of ultrafine fibers with an average single fiber diameter of 0.3 μm or more and 7 μm or less, and water-dispersed polyurethane, the artificial leather being subjected to pulse NMR measurement (Solid Echo method, proton observation, measurement temperature 50 When the free induction decay signal (FID) at ℃) is fitted for two components, the S component (Gaussian component) and the L component (Lorentzian component), the spin-spin relaxation time Tl of the L component is 500 μs or more and 800 μs or less. , an artificial leather characterized in that the fraction Cl of the L component is 25% or more and less than 55%.
[2] The artificial leather according to [1] above, wherein the ultrafine fiber is a polyester fiber.
[3] The artificial leather according to [1] or [2], wherein the nonwoven fabric is intertwined and integrated with a scrim layer that is a textile.
[4] The artificial leather according to [3] above, wherein the scrim layer is a woven fabric of polyester fibers.
[5] The water-dispersed polyurethane consists of a methyl methacrylate macromonomer having two hydroxyl groups at one end, a polymer polyol having hydroxyl groups at both ends, a short chain diol having hydroxyl groups at both ends, and a hydrophilized polyurethane. The artificial leather according to any one of [1] to [4] above, which is obtained by a reaction between an organic diisocyanate, an organic diisocyanate, and a chain extender.
[6] The artificial leather according to [5] above, wherein the polymer polyol is polycarbonate diol and/or polyether diol.
[7] The artificial leather according to [6], wherein the polycarbonate diol is a copolymerized polycarbonate diol obtained by copolymerizing two or more types of polyhydric alcohols.
[8] The above [5] to [7], wherein the ratio of the methyl methacrylate macromonomer having two hydroxyl groups at one end to the organic diisocyanate is 0.1 mol% or more and 7.0 mol% or less. Artificial leather according to any of the above.

The artificial leather according to the present invention has a low environmental impact because no organic solvent is used in the manufacturing process, and the embossed pattern is excellent in clarity, so it can be used as a surface material for seats for interiors, automobiles, aircraft, railway vehicles, etc. It can be suitably used for materials, interior materials, clothing products, etc.

FIG. 2 is an explanatory diagram of a cross-sectional structure of artificial leather. FIG. 3 is an explanatory diagram of how to determine the average diameter of single fibers constituting the fiber layer (A). It is an explanatory view showing the structure of artificial leather. FIG. 1 is a schematic explanatory diagram of synthesis of a water-dispersed polyurethane resin. It is a functional explanatory diagram of a macromonomer. FIG. 2 is an explanatory diagram of a methyl methacrylate macromonomer having two hydroxyl groups at one end. FIG. 2 is an explanatory diagram of a polysiloxane-based macromonomer having two hydroxyl groups at one end.

Hereinafter, embodiments of the present invention will be described in detail, but the present invention is not limited to the embodiments. Further, unless otherwise specified, various values of the present disclosure are values obtained by the method described in the [Examples] section of the present disclosure or a method understood by those skilled in the art to be equivalent thereto.

<Artificial leather>
One embodiment of the present invention is an artificial leather made of a nonwoven fabric made of ultrafine fibers with an average single fiber diameter of 0.3 μm or more and 7 μm or less, and water-dispersed polyurethane. When the free induction decay signal (FID) at proton observation (measurement temperature 50°C) is fitted to two components, S component (Gaussian component) and L component (Lorentz component), the spin-spin relaxation time Tl of the L component is 500 μs. The artificial leather is characterized in that the time is 800 μsec or less, and the fraction Cl of the L component is 25% or more and less than 55%.

In this specification, "artificial leather" refers to "artificial leather" as defined in the Household Goods Quality Labeling Act. (impregnated with molecular elastomer)". In addition, according to the definition of JIS-6601, artificial leather is classified according to its appearance into "smooth", which has the appearance of leather like silver, and "nap", which has the appearance of suede, velor, etc. The artificial leather of the embodiment relates to one classified as "nap" (that is, suede-like artificial leather having a raised appearance). The suede-like appearance can be formed by buffing (raising) the outer surface of the fiber layer (A) (that is, the first outer surface of the artificial leather) with sandpaper or the like. In this specification, the outer surface of artificial leather is the surface that is exposed to the outside when the artificial leather is used (for example, the surface that comes into contact with the human body in the case of a chair application) (Fig. 1, Fiber layer (A) (see reference numeral 1). In one embodiment, in the case of suede-like artificial leather, the outer surface of the fiber layer (A) is raised or raised by buffing or the like.
In this specification, unless otherwise specified, the term "fibrous web" refers to the state of short fibers before they are entangled, and the term "fiber sheet" refers to the state after entangling and before filling with PU resin. The term "artificial leather" refers to the state of the product after filling with PU resin and before dyeing and finishing, and the term "artificial leather" refers to the state of the product after dyeing and finishing. In addition, the term "nonwoven fabric" includes "fiber web,""fibersheet,""sheet-likematerial," and "artificial leather," and the term "fibrous base material" includes the term "nonwoven fabric." In addition, it also includes woven and knitted fabrics.

As illustrated in FIG. 3, the fiber sheet (A) shown by reference numeral 1 in FIG. are doing. Such (poly)urethane resins generally have an amorphous component (soft segment due to van der Waals force) made of polyol as a main component, and have flexibility, pliability, flexibility, cold resistance, affinity, and resistance to urethane resin. While imparting chemical properties, it also imparts toughness, heat resistance, solvent resistance, elasticity, etc. due to hard segments in which urethane (urea) bonds are aggregated by hydrogen bonds.
However, as mentioned above, at the level of the prior art, it was not known to those skilled in the art what kind of polyol should be used and in what amount to achieve what kind of effect and to what extent with respect to the soft segment of urethane resin. . This is even more so in the case of artificial leather in which the urethane resin is attached as a binder to a polyester fiber sheet rather than the urethane resin itself.

[L component spin-spin relaxation time Tl and L component fraction Cl]
In the artificial leather of this embodiment, the free induction decay signal (FID) in pulsed NMR measurement (Solid Echo method, proton observation, measurement temperature 50°C) is divided into two components: S component (Gaussian component) and L component (Lorentzian component). In the case of fitting, the spin-spin relaxation time Tl of the L component is 500 μs or more and 800 μs or less, and the fraction Cl of the L component is 25% or more and less than 55%.
As will be described later, information on both components with low molecular mobility and components with high molecular mobility could be obtained by pulse NMR measurement (Solid Echo method) of artificial leather.
In an artificial leather made of a polyester fiber sheet and a polyurethane resin, the component with low molecular mobility is considered to be the polyester fiber, while the component with high molecular mobility is considered to be the polyurethane resin.
In pulsed NMR, the FID (free induction decay) attenuation curve is generally expressed by a Gaussian, Lorentzian, or Weibull type function intermediate thereto, depending on the activity of molecular motion in the sample. There are multiple classifications of the relaxation time of nuclear spin, and in some cases efficient relaxation occurs due to the motion of molecular chains at a speed similar to the Larmor frequency. However, when measuring artificial leather, the transverse relaxation time is the subject of evaluation. In the case of T ₂ , it is sensitive to slow molecular motion at low frequencies, and the slower the molecular motion and the longer the correlation time, the more efficiently the nuclear spin relaxes and the relaxation time becomes shorter. In other words, it can be determined that the longer the relaxation time of a component, the higher the molecular mobility of the component. For components with low molecular mobility such as crystalline phases (e.g., polyester fibers), the magnetization decay curve exhibits a Gaussian decay, whereas for components with high molecular mobility (e.g., soft segments of urethane resin), the magnetization decay curve exhibits a Gaussian decay. ), the damping curve exhibits Lorentzian damping.
Therefore, in the example, as will be described later, the free induction decay curve of spin-spin relaxation of ^1H obtained in measurement using a pulsed NMR device (solid echo method) is converted into a low-mobility Gaussian component (S component). Assuming two curves derived from two components: and a highly mobile Lorentzian component (L component), the following equation 1:
M(t)=Cs*exp((-1/2)*(t/Ts) ² )+Cl*exp(-t/Tl)...Formula 1
{where M(t) is the signal strength at a certain time t, Cs is the fraction of the low-mobility component, Cl is the fraction of the high-mobility component, and Ts is the fraction of the low-mobility component is the T ₂ relaxation time of the active component, and Tl is the T ₂ relaxation time of the highly active component. } was used for fitting.
As a result of the above measurements, the inventors of the present application found that if the spin-spin relaxation time Tl of the L component is 500 μs or more and 800 μs or less, and the fraction Cl of the L component is 25% or more and 54% or less, then during embossing, It was discovered for the first time that the heat shrinkage of polyurethane resin was suppressed and the embossed pattern became sufficiently clear in the resulting artificial leather, and based on this discovery, the present invention was completed.
In addition, the inventors of the present application found that the fraction Cl of the high-mobility component and the ratio of the PU resin to the total mass of the sheet-like material described below are strongly correlated, and that the spin- It has been confirmed that there is no publicly practiced artificial leather product with a spin relaxation time Tl of 500 μs or more and 800 μs or less.

[Adhesion rate of PU resin to total fiber mass of sheet material]
In the artificial leather of this embodiment, the adhesion rate of the PU resin to the total fiber mass of the sheet-like material is preferably 15% by mass or more and 50% by mass or less, more preferably 22% by mass or more and 45% by mass or less, More preferably, it is 26% by mass or more and 40% by mass or less. The ratio of the PU resin to the total fiber mass of the sheet material affects the heat shrinkability of the polyurethane resin and the resulting clarity of the embossed pattern. In addition, if the ratio of PU resin to the total fiber mass of the sheet-like product is 15% by mass or more, the fibers are held well by the PU resin, and mechanical strength such as abrasion resistance that satisfies market needs is easily obtained. . On the other hand, if the ratio of the PU resin to the total fiber mass of the sheet-like material is 50% by mass or less, it is easy to obtain artificial leather with a soft texture and a dense feel.

[Polyurethane (PU) resin]
The PU resin is preferably one obtained by reacting a polymer polyol, an organic diisocyanate, and a chain extender.

[High molecular polyol]
As the polymer diol, for example, polycarbonate-based, polyester-based, polyether-based, silicone-based, fluorine-based diols, etc. can be employed, and a copolymer of two or more of these may be used. However, in the PU resin contained in the artificial leather of this embodiment, as described below, an appropriately selected macromonomer-derived component (having a side chain) is used as a polymeric prepolymer component or a short chain diol as a chain extender. By including it as part of the component, the spin-spin relaxation time Tl of the L component is set to 500 μs or more and 800 μs or less.

From the viewpoint of hydrolysis resistance, polycarbonate-based diols, polyether-based diols, or a combination thereof are preferably used. Moreover, from the viewpoint of light resistance and heat resistance, polycarbonate-based, polyester-based diols, or a combination thereof are preferably used. Furthermore, from the viewpoint of cost competitiveness, polyether diols, polyester diols, or a combination thereof are preferably used.

Polycarbonate diols can be produced by transesterification of alkylene glycol and carbonate, reaction of phosgene or chloroformate, and alkylene glycol, and the like. Examples of alkylene glycols include ethylene glycol, propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,9-nonanediol, and 1,10-decanediol. Chain alkylene glycol; branched alkylene glycol such as neopentyl glycol, 3-methyl-1,5-pentanediol, 2,4-diethyl-1,5-pentanediol, 2-methyl-1,8-octanediol; 1, Alicyclic diols such as 4-cyclohexanediol; aromatic diols such as bisphenol A; etc., and these can be used alone or in combination of two or more.

Examples of polyester diols include polyester diols obtained by condensing various low molecular weight polyols and polybasic acids. Examples of low molecular weight polyols include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,3-butanediol, 1,4-butanediol, 2,2-dimethyl-1,3-propane. Diol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 1,8-octanediol, diethylene glycol, triethylene glycol, dipropylene glycol, tripropylene glycol, cyclohexane-1,4-diol, cyclohexane One or more types selected from -1,4-dimethanol can be used. Further, adducts obtained by adding various alkylene oxides to bisphenol A can also be used. Examples of polybasic acids include 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 hexahydrocarbonic acid. One or more types selected from the group consisting of isophthalic acid can be mentioned.

Examples of the polyether diol include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and copolymer diols that are a combination thereof.

The number average molecular weight of the polymer polyol (polymer diol) is preferably 500 to 7,000. 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. Further, by setting the number average molecular weight to 7000 or less, the strength of the PU resin can be maintained well.

[Macromonomer]
Figures 5 to 7 illustrate examples of macromonomers.
As illustrated in FIG. 5, a macromonomer is generally a monomer that introduces an arbitrary side chain into the main chain of a polymer, and the introduction of the side chain can prevent the main chains from associating with each other. The right-hand side of FIG. 5 shows a state in which the side chains form a microphase-separated structure to avoid association of the main chains. However, it should be noted that in FIG. 5, the main chain is copolymerized with methyl methacrylate, and is not a macromonomer having two hydroxyl groups at one end used in the present example and comparative example.
FIG. 6 shows an example of a methyl methacrylate-based macromonomer having two hydroxyl groups (dihydrokyl groups) at one end and whose side chain is a polymer of methyl methacrylate. An example of such a methyl methacrylate macromonomer is "AA-6" manufactured by Toagosei Co., Ltd., which has an Mn of 6,000.
FIG. 7 shows an example of a polydimethylsiloxane-based macromonomer having two hydroxyl groups (dihydrokyl groups) at one end and whose side chain is polydimethylsiloxane. Such polydimethylsiloxane macromonomers include "X-22-176DX" manufactured by Shin-Etsu Chemical Co., Ltd. with a molecular weight of 3,000, "X-22-177GX-A" manufactured by Shin-Etsu Chemical Co., Ltd. with a molecular weight of 14,000, etc. can be mentioned.
Although we do not wish to be bound by any particular theory, the desired effect achieved when using PMMA compared to siloxane is that the solubility parameter (SP value) of the resin is 10.0 compared to polyurethane. , polydimethylsiloxane, 7.3 to 7.6, and polymethyl methacrylate, 9.3. This is presumably due to the fact that polymethyl methacrylate has a higher affinity with polyurethane.

[Organic diisocyanate]
Examples of organic diisocyanates include aliphatic diisocyanates such as hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, isophorone diisocyanate, and xylylene diisocyanate; aromatic diisocyanates such as diphenylmethane diisocyanate and tolylene diisocyanate; and combinations thereof. May be used. Among them, from the viewpoint of light resistance, aliphatic diisocyanates such as hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, and isophorone diisocyanate are preferably used.

[Hydrophilic agent]
Examples of the hydrophilizing agent include dialkylolalkanoic acids such as 2,2-dimethylolpropionic acid, 2,2-dimethylolbutanoic acid, 2,2-dimethylolheptanoic acid, and 2,2-dimethyloloctanoic acid. ; Amino acids such as glycine, alanine, and valine; Compounds with carboxyl groups such as tartaric acid; Compounds with sulfo groups such as 3-(2,3-dihydroxypropoxy)-1-propanesulfonic acid and sulfoisophthalic acid di(ethylene glycol) ester Compounds having a sulfamic acid group such as N,N-bis(2-hydroxylethyl)sulfamic acid; or salts of these compounds neutralized with the neutralizing agent described below may be used. . Among them, 2,2-dimethylolpropionic acid or 2,2-dimethylolbutanoic acid is preferably used.

[Neutralizer]
Examples of neutralizing agents include primary amines such as monomethylamine, monoethylamine, monobutylamine, monoethanolamine, and 2-amino-2-methyl-1-propanol; dimethylamine, diethylamine, dibutylamine, diethanolamine, N- Examples include secondary amines such as methyldiethanolamine; tertiary amines such as trimethylamine, triethylamine, dimethylethylamine, and triethanolamine. Among them, triethylamine, monoethanolamine, diethanolamine, and N-methyldiethanolamine are preferably used from the viewpoint of odor of the aqueous dispersion.

[Chain extender]
As the chain extender, an amine chain extender such as ethylenediamine and methylenebisaniline, or a diol chain extender such as ethylene glycol can be used. Moreover, a polyamine obtained by reacting polyisocyanate and water can also be used as a chain extender.

[Water-dispersed PU resin]
In the production of the artificial leather of this embodiment, it is preferable to use a water-dispersed PU resin as the PU resin to be contained, since it is not necessary to use an organic solvent and the environmental load can be reduced.
FIG. 4 illustrates a method for producing a water-dispersed polyurethane resin.
In FIG. 4, in the first step, a polymer polyol, a short chain diol, a hydrophilizing agent, and an isocyanate are reacted in a ketone solvent to synthesize a prepolymer, and in the second step, the obtained prepolymer is The prepolymer is emulsified in water using a neutralizing agent, and in the third step, the prepolymer is reacted with a diamine, which is a chain extender, and the ketone solvent is removed to produce a water-dispersed polyurethane.
In the production of the artificial leather of this embodiment, as described above, an appropriately selected macromonomer-derived component (having a side chain) is used in the synthesis of the prepolymer in the first step.
However, the method for producing water-dispersed PU resin is not limited to that shown in FIG. 4.

As the water-dispersed PU resin, a self-emulsifying PU resin containing a hydrophilic group in the PU molecule, a forced emulsifying PU resin in which the PU resin is emulsified 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 heat and humidity resistance, abrasion resistance, and hydrolysis resistance. It is preferable to add a crosslinking agent in order to improve durability during jet dyeing, suppress fiber shedding, and obtain excellent surface quality. The crosslinking agent may be an external crosslinking agent that is added to the PU resin as an additive component, or an internal crosslinking agent that introduces a reactive group that can form a crosslinked structure into the PU resin structure in advance.
Water-dispersible PU resins used for artificial leather generally have a crosslinked structure to provide resistance to dyeing processes, so they tend to be difficult to dissolve in organic solvents such as N,N-dimethylformamide. . Therefore, for example, when artificial leather is immersed in N,N-dimethylformamide at room temperature for 12 hours to dissolve the PU resin, when the cross section is observed with an electron microscope, it is found that the resin does not have a fiber shape. If any substance remains, it can be determined that the resinous substance is a water-dispersed PU resin.

The average primary particle diameter of the polyurethane resin is a value obtained by measuring a PU resin dispersion using a laser diffraction particle size distribution analyzer ("LA-920" manufactured by Horiba, Ltd.). Artificial leather that has excellent mechanical strength by making the average primary particle size of the PU resin 0.1 μm or more and improving the force of gripping the fibers in the fiber sheet (i.e., the binder force) with the PU resin. is obtained. Furthermore, setting the average primary particle size of the PU resin to 0.8 μm or less is advantageous in that it suppresses the PU resin from agglomerating or coarsening, and the standard deviation of the surface PU resin area ratio can be controlled to 20% or less. It is. By setting the average primary particle size of the PU resin in the PU resin dispersion to 0.1 μm or more and 0.8 μm or less, the fibers that make up the artificial leather (especially its surface layer) are gripped to each other more often, for example, A flexible texture (flexibility value) and excellent mechanical strength (abrasion resistance, etc.) can be obtained.

[Solid content concentration of PU resin dispersion]
As described below, in typical embodiments, the PU resin is impregnated in the form of an impregnating liquid such as a solution (for example, in the case of a solvent-dispersed type) or a dispersion (for example, in the case of a water-dispersed type). For example, the solid content concentration of the water-dispersed PU resin dispersion can be from 10% by weight to 35% by weight, more preferably from 15 to 30% by weight, and even more preferably from 15 to 25% by weight. In one embodiment, the impregnation liquid is prepared and impregnated into the fiber sheet so that the adhesion rate of the PU resin to 100 mass% of the fiber sheet is 15% by mass or more and 50% by mass or less.
The impregnating liquid containing PU resin (for example, water-dispersed PU resin) may contain stabilizers (ultraviolet absorbers, antioxidants, etc.), flame retardants, antistatic agents, pigments (carbon black, etc.) as necessary. Additives may be added. The total amount of these additives present in the artificial leather is, for example, 0.1 to 10.0 parts by weight, or 0.2 to 8.0 parts by weight, or 0.3 to 100 parts by weight, based on 100 parts by weight of the PU resin. It may be 6.0 parts by mass. Note that such additives will be distributed in the PU resin of the artificial leather. In this disclosure, when referring to the size and mass ratio of the PU resin to the fiber sheet, the values are intended to include additives (if used).

[Hot water soluble resin]
When a fiber sheet is impregnated with a water-dispersed PU resin dispersion, and then the PU resin is fixed by heating to obtain a sheet-like article filled with PU resin, the fiber sheet is impregnated with a water-dispersed PU resin dispersion. It is also possible to perform a step of attaching a hot water-soluble resin to the fiber sheet before impregnation. The hot water soluble resin (for example, PVA resin) can be attached by a method such as preparing an aqueous solution of the hot water soluble resin, impregnating the fiber sheet with the aqueous solution, and then drying it. In the post-process or dyeing process, the hot water-soluble resin is removed from the obtained fiber sheet using hot water, thereby preventing the adhesion between the fibers and the PU resin or removing part of the continuous layer of the PU resin. Since it has the effect of dividing and making it porous and making the state of adhesion of the PU resin finer, the feel of the artificial leather can be easily improved.
Examples of the hot water-soluble resin include partially saponified PVA resin, completely saponified PVA resin, and the like. Since fully saponified PVA resin tends to be less eluted in water at room temperature (20° C.) than partially saponified PVA resin, it is preferable to use fully saponified PVA resin as the hot water-soluble resin. From the viewpoint of being difficult to elute in water at room temperature (20° C.), the degree of saponification of the fully saponified PVA resin is preferably 95 mol% or more, more preferably 98 mol% or more. Further, in order to increase the permeability of the hot water-soluble resin aqueous solution during impregnation, the degree of polymerization is preferably 1000 or less, more preferably 700 or less.

[Fiber sheet]
As shown in FIG. 1, the fiber sheet 1 includes at least a fiber layer (A) 12, and the scrim 11 and the fiber layer (B) 13 are optional and not essential elements. Therefore, in the case of a single layer of the fiber layer (A), in the case of two layers of the fiber layer (A) and the scrim or the fiber layer (B), the artificial leather of the present embodiment includes the fiber layer (A), the scrim and the fiber layer. There may be three layers (layer (B)).
When the scrim 11 and/or the fiber layer (B) 13 is not included, the fiber layer (A) may be a single-layer fiber sheet filled with PU resin cut in half, as described later. In one aspect, the fibrous sheet is a single layer structure that does not include a scrim. This is because cutting in half increases productivity.
In other embodiments, the fibrous sheet has a three layer structure and the scrim is the middle layer. For example, a scrim 11 that is a woven or knitted fabric is placed between the fiber layer (A) 12 that constitutes the first outer surface of the artificial leather and the fiber layer (B) 13 that constitutes the second outer surface of the artificial leather. A three-layer structure in which the fibers are sandwiched and intertwined between these layers is preferable in terms of dimensional stability, tensile strength, tear strength, and the like. Moreover, according to the three-layer structure of the fiber layer (A), the fiber layer (B), and the scrim sandwiched between them, the fiber layer (A) and the fiber layer (B) can be designed individually. This is preferable in that the diameter, type, etc. of the fibers constituting these layers can be freely customized according to the functions and uses required of the artificial leather. For example, if ultrafine fibers are used in the fiber layer (A) and flame-retardant fibers are used in the fiber layer (B), both excellent surface quality and high flame retardance can be achieved.

When the fiber sheet includes a scrim, the scrim, which is a woven or knitted fabric, is preferably made of the same polymer type as the fibers constituting the fiber layer (A) from the viewpoint of the same color property when dyed. For example, if the fibers constituting the fiber layer (A) are polyester-based, the fibers constituting the scrim are preferably polyester-based, and if the fibers constituting the fiber layer (A) are polyamide-based, the scrim is preferably polyester-based. It is preferable that the constituent fibers are also polyamide-based. In the case of a knitted fabric, the scrim is preferably a single knit knitted with a gauge of 22 or more and 28 or less. When the scrim is woven, greater dimensional stability and strength can be achieved than when knitted. The structure of the woven fabric may be plain weave, twill weave, satin weave, etc., but plain weave is preferred from the viewpoint of cost and process aspects such as interlacing properties.
The yarn constituting the fabric may be monofilament or multifilament. The single fiber fineness of the yarn is preferably 5.5 dtex or less, since flexible artificial leather can be easily obtained. As for the form of the yarn constituting the woven fabric, it is preferable to use multifilament raw silk of polyester, polyamide, etc., or textured yarn subjected to false twisting, twisted at a twist number of 0 to 3000 T/m. The multifilament may be a normal one, for example, 33dtex/6f, 55dtex/24f, 83dtex/36f, 83dtex/72f, 110dtex/36f, 110dtex/48f, 167dtex/36f, 166dtex/48f, etc. made of polyester, polyamide, etc. Preferably used. The threads constituting the fabric may be multifilament long fibers. The weaving density of the threads in the fabric is preferably 30 to 150 threads/inch, more preferably 40 to 100 threads/inch, in order to obtain artificial leather that is flexible and has excellent mechanical strength. In order to have good mechanical strength and appropriate texture, the basis weight of the fabric is preferably 20 to 150 g/m ² . In addition, the presence or absence of false twisting in the woven fabric, the number of twists, the single fiber fineness of the multifilament, the weaving density, etc. are determined by the entanglement with the fibers constituting the fiber layer (A) and the optional layer (B), In addition to the flexibility of the artificial leather, it also contributes to mechanical properties such as seam strength, tear strength, tensile strength and elongation, and elasticity, so it may be selected appropriately depending on the target physical properties and use.

From the viewpoint of obtaining artificial leather that has higher levels of wear resistance, dyeability, and surface quality, in the artificial leather of this embodiment, the fiber layer (A) is made of ultrafine fibers with an average diameter of 0.3 μm or more and 7 μm or less. The diameter is preferably 2 μm or more and 6 μm or less, more preferably 2 μm or more and 5 μm or less. If the average diameter of the fibers is 1 μm or more, the abrasion resistance, color development by dyeing, and light fastness will be good. On the other hand, if the average diameter of the fibers is 8 μm or less, the number density of the fibers is high, so that it is easy to obtain artificial leather with a high density, smooth surface feel, and better surface quality.

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

When the artificial leather is composed only of the fiber layer (A), the basis weight of the fibers constituting the fiber layer (A) is preferably 40 g/m ² or more and 500 g/m ² from the viewpoint of mechanical strength such as abrasion resistance. Below, it is more preferably 50 g/m ² or more and 370 g/m ² or less, and still more preferably 60 g/m ² or more and 320 g/m ² or less.
When artificial leather is composed of a three-layer structure of a fiber layer (A), a scrim, and a fiber layer (B), the basis weight of the fibers constituting the fiber layer (A) is determined from the viewpoint of mechanical strength such as abrasion resistance. Preferably it is 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. In addition, from the viewpoint of cost and ease of production, the basis weight of the fibers constituting the fiber layer (B) is preferably 10 g/m ² or more and 200 g/m ² or less, more preferably 20 g/m 2 or more and 170 g/m ² or less. It can be less than or equal to ² . The basis weight of the scrim is preferably 20 g/m ² or more and 150 g/m 2 or less, more preferably 20 g/m 2 or more and 130 g/m ^{2 or} less, and even more preferably from the viewpoint of mechanical strength and entanglement between ^{the fiber layer} and the scrim. is 30 g/m ² or more and 110 g/m ² or less.
The basis weight of the artificial leather filled with PU resin is preferably 50 g/m ² or more and 550 g/m ² or less, more preferably 60 g/m ² or more and 400 g/m ² or less, and even more preferably 70 g/m ² or more and 350 g/m 2 or less. ² or less.

<Manufacturing method of artificial leather>
An example of the method for manufacturing artificial leather of this embodiment will be described below.
An example of the method for manufacturing artificial leather of this embodiment includes the following steps:
A step of forming a fiber web with sea-island short fibers, and then de-sea-removing the fiber sheet obtained by needle punching to obtain a fiber sheet in which the single fibers of the island component are exposed; and, optionally, the obtained fiber sheet. a step of applying a hot water-soluble resin to;
The following steps may include:
Impregnating the fiber sheet in which the single fibers are dispersed with a water-dispersed PU resin dispersion, and then fixing the PU resin by heating to obtain a sheet-like article filled with the PU resin; and a step of removing the hot water-soluble resin from the sheet-like material using hot water;
may further include.
Each step will be explained below in order.

[Step of forming a fiber web with sea-island short fibers, and then de-sea-removing the fiber sheet obtained by needle punching to obtain a fiber sheet in which the single fibers of the island component are exposed]
The manufacturing method for each fiber layer (fiber layer (A), arbitrary fiber layer (B), etc.) constituting the fiber sheet of artificial leather includes a direct spinning method (for example, spunbond method and melt-blown method), or , a method of forming a fiber sheet using short fibers (for example, a dry method such as a carding method or an air-laid method, and a wet method such as a papermaking method). In embodiments, island-in-the-sea (SIF) staple fibers are used as the raw material. A fiber sheet manufactured using short fibers has small density spots and excellent uniformity, and is easy to obtain uniform napping, so it is suitable for improving the surface quality of artificial leather.

As a means for forming the ultrafine fibers of the fiber sheet, ultrafine fiber expression type fibers can be used. By using ultrafine fiber expression type fibers, a form in which ultrafine fiber bundles are entangled can be stably obtained.
The ultrafine fiber developing type fiber is a sea-island type fiber in which two thermoplastic resin components with different solvent solubility are used as a sea component and an island component, and the island component is made into ultrafine fiber by dissolving and removing the sea component using a solvent or the like. It is possible to employ peelable composite fibers in which fibers or two-component thermoplastic resins are arranged alternately in a radial or multilayered manner on the cross section of the fibers, and each component is peeled and split into ultrafine fibers. Among these, sea-island type fibers are preferably used from the viewpoint of the flexibility and texture of sheet-like products because by removing the sea component, it is possible to create appropriate voids between the island components, that is, between the ultrafine fibers. .
Sea-island composite fibers include sea-island composite fibers, which are spun using a sea-island composite spinneret by arranging two components, a sea component and an island component, and a sea-island composite fiber, which is spun by mixing two components, a sea component and an island component. There are mixed type fibers. Sea-island composite fibers are preferably used because they yield ultrafine fibers of uniform fineness and have sufficient length, contributing to the strength of the sheet-like product.
As the sea component of the sea-island type fiber, polyethylene, polypropylene, polystyrene, copolymerized polyester obtained by copolymerizing sodium sulfoisophthalic acid, polyethylene glycol, etc., and polylactic acid can be used. Among these, from the viewpoint of environmental consideration, copolymerized polyesters and polylactic acid, which are copolymerized with alkali-decomposable sodium sulfoisophthalic acid, polyethylene glycol, and the like, which can be decomposed without using an organic solvent, are preferable.
When sea-island type fibers are used, the sea removal treatment is preferably performed before applying the PU resin to the fiber sheet. If the sea removal treatment is performed before applying the PU resin, the structure will be such that the PU resin will adhere directly to the ultrafine fibers, and the ultrafine fibers can be strongly gripped, so that the abrasion resistance of the sheet-like material will be improved.

Methods for intertwining the fibers or fiber bundles of the fibrous web include cutting sea-island fibers to a predetermined fiber length to form staples, forming a fibrous web through cards and cross wrappers, needle punching, and optional water flow called spunlace method. A method of interlacing by interlacing treatment can be adopted.
In the needle punch method, the number of needle barbs used is preferably 1 to 9. By setting the number of barbs to one or more, a confounding effect can be obtained and damage to the fibers can be suppressed. By setting the number of barbs to 9 or less, damage to the fibers can be reduced, and needle marks left on the artificial leather can be reduced, so that the appearance of the product can be improved.
Considering the entanglement of the fibers and the influence on the product appearance, the total depth of the barb (the length from the tip of the barb to the bottom of the barb) is preferably 0.05 mm or more and 0.10 mm or less. When the total depth of the barbs is 0.05 mm or more, good hooking on the fibers can be obtained, so that efficient fiber entanglement can be achieved. In addition, since the total depth of the barbs is 0.10 mm or less, needle marks left on the artificial leather are reduced and the quality is improved. Considering the balance between the strength of the barb portion and fiber entanglement, the total depth of the barb is more preferably 0.06 mm or more and 0.08 mm or less.
When fibers are entangled by ^the needle punch method, the punch density range is preferably 300 to 6000 fibers/cm ² , and 1000 to 6000 fibers/cm ^{2 .} is more preferable.
The fiber sheet obtained by needle punching can be immersed in water at a temperature of 98° C. for 2 minutes to shrink, and dried at a temperature of 100° C. for 5 minutes to obtain a fiber sheet before sea removal. .
The sea-removal treatment can be performed by immersing the sea-island type fibers in a solvent and draining the fibers. As the solvent for dissolving the sea component, when the sea component is copolymerized polyester or polylactic acid, an alkaline aqueous solution such as sodium hydroxide can be used. From the viewpoint of environmental considerations in the process, desalination treatment with an alkaline aqueous solution such as sodium hydroxide is preferred.

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, and even more preferably It is 38 mm or more and 76 mm or less, and preferably 1 mm or more and 30 mm or less, more preferably 2 mm or more and 25 mm or less, and still more preferably 3 mm or more and 20 mm or less, by a wet method (paper making method, etc.). For example, the aspect ratio (L/D), which is the ratio of length (L) to diameter (D), of short fibers used in a wet method (paper-making method, etc.) is preferably 500 or more and 2000 or less, more preferably It is 700-1500. Such an aspect ratio is such that the short fibers have good dispersibility and spreadability in the slurry when the short fibers are dispersed in water to prepare the slurry, the fiber layer strength is good, Compared to the dry method, the fiber length is shorter and the single fibers are easily dispersed, so it is less likely to cause a pill-like appearance called pilling due to friction, which is preferable. For example, the fiber length of short fibers having 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.

[Step of adding hot water-soluble resin to the obtained fiber sheet]
Before impregnating the obtained fiber sheet with the water-dispersed PU resin dispersion, the above-mentioned hot water-soluble resin is attached, and in the post-process or dyeing process, the obtained fiber sheet is dyed using hot water. By removing the hot water-soluble resin, it is possible to inhibit the adhesion between the fibers and the PU resin, divide a part of the continuous layer of the PU resin, make it porous, and make the adhesion state of the PU resin finer. , the texture of artificial leather can be easily improved.

[Step of impregnating the fiber sheet in which the single fibers are dispersed with a water-dispersed PU resin dispersion, and then fixing the PU resin by heating to obtain a sheet-like article filled with PU resin]
In this step, the fiber sheet is impregnated with a water-dispersed PU resin dispersion, and then the PU resin is fixed by heating to fill the fiber sheet with the PU resin. In typical embodiments, the PU resin is impregnated in the form of an impregnating liquid, such as a dispersion (eg, in the case of an aqueous dispersion). The concentration of PU resin in the impregnating liquid can be, for example, 10 to 35% by weight. In one embodiment, the impregnation liquid is prepared and the fiber sheet is impregnated so that the ratio of the PU resin to 100 mass% of the fiber sheet is 15 to 50 mass%.

Water-dispersed PU resins are forcibly dispersed and stabilized using surfactants, and forced emulsification-type PU resins, which have a hydrophilic structure in the PU molecular structure and can be used in water even in the absence of surfactants. It is classified as a self-emulsifying PU resin that is dispersed and stabilized. Either one may be used in this embodiment.

A fiber sheet can be impregnated or coated with a water-dispersed PU resin dispersion, and the PU resin can be coagulated by dry heat coagulation, moist heat coagulation, hot water coagulation, or a combination thereof. The temperature of the wet heat coagulation is set to be higher than the heat-sensitive coagulation temperature of the PU resin, and is preferably 40 to 200°C. By setting the temperature of wet heat coagulation to 40° C. or higher, more preferably 80° C. or higher, it is possible to shorten the time until solidification of the PU resin and further suppress the migration phenomenon. On the other hand, by setting the wet heat coagulation temperature to 200° C. or lower, more preferably 160° C. or lower, thermal deterioration of the PU resin or PVA resin can be prevented. The temperature of hot water coagulation is preferably higher than the heat-sensitive coagulation temperature of the PU resin, and is preferably 40 to 100°C. By setting the temperature of hot water coagulation in hot water to 40° C. or higher, more preferably 80° C. or higher, it is possible to shorten the time until solidification of the PU resin and further suppress the migration phenomenon. The dry coagulation temperature and drying temperature are preferably 80 to 180°C. Productivity is excellent by setting the dry coagulation temperature and drying temperature to 80°C or higher, more preferably 90°C or higher. On the other hand, thermal deterioration of PU resin and PVA resin can be prevented by setting the dry coagulation temperature and drying temperature to 180° C. or lower, more preferably 160° C. or lower.

[Step of removing the hot water-soluble resin from the obtained sheet-like material using hot water]
Examples of methods for removing the hot water-soluble resin from the sheet-like material include immersion in hot water of 60°C or higher, preferably 80°C or higher, or immersion in hot water of 80°C or higher before dyeing in a jet dyeing machine. Examples include a method of removing hot water-soluble resin while circulating hot water. In particular, the method of removing the hot water-soluble resin in a jet dyeing machine is preferable because it can eliminate the process of drying and winding up the sheet material after removing the hot water-soluble resin, and can increase production efficiency. . In this embodiment, a flexible sheet-like product is obtained by removing the hot water-soluble resin from the sheet-like product after applying the PU resin. The method for removing the hot water-soluble resin is not particularly limited, but for example, it is preferable to dissolve and remove it by immersing the sheet in hot water at 60 to 100°C and, if necessary, squeezing the liquid with a mangle or the like. It is.

[Post-process]
After filling the fiber sheet with PU resin and removing the hot water-soluble resin, if no scrim is included, the sheet-like material filled with PU resin can be cut in half in the sheet thickness direction. Thereby, production efficiency can be improved.
Furthermore, a lubricant such as a silicone dispersion may be applied to the sheet-like material filled with the PU resin before the raising treatment described below. Furthermore, applying an antistatic agent before the napping treatment is a preferred embodiment in order to prevent grinding powder generated from the sheet material during grinding from being deposited on the sandpaper.
A napping treatment can be performed to form naps on the surface of the sheet-like article. The raising treatment can be performed by grinding using sandpaper, a roll sander, or the like. Further, by applying silicone or the like as a lubricant before the napping treatment, it becomes possible to easily raise the nap by surface grinding, and the surface quality becomes very good.
The artificial leather is preferably dyed for the purpose of increasing its sensory value (ie, visual effect). The dye may be selected according to the type of fibers constituting the fiber sheet; for example, disperse dyes can be used for polyester fibers, and acid dyes or metal-containing dyes can be used for polyamide fibers. can be used, and combinations thereof can also be used. When dyeing with a disperse dye, reduction washing may be performed after dyeing. As a dyeing method, a conventional method well known to dyeing processors can be used. As the dyeing method, it is preferable to use a jet dyeing machine because it is possible to dye the sheet-like material and at the same time impart a rolling effect to soften the sheet-like material. The dyeing temperature is preferably 80 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 fibers can be dyed efficiently. On the other hand, by setting the dyeing temperature to 150°C or lower, more preferably 130°C or lower, deterioration of the PU resin can be prevented.
The artificial leather dyed in this manner is preferably subjected to soaping and, if necessary, reduction washing (that is, washing in the presence of a chemical reducing agent) to remove excess dye. It is also a preferred embodiment to use a dyeing aid during dyeing. By using a dyeing aid, the uniformity and reproducibility of dyeing can be improved. Further, in the same bath as dyeing or after dyeing, a finishing agent treatment using a softener such as silicone, an antistatic agent, a water repellent, a flame retardant, a light stabilizer, an antibacterial agent, etc. can be performed.

The artificial leather of this embodiment can be used as an interior material with a very elegant appearance as a surface material for furniture, chairs, wall materials, seats in the interior of vehicles such as automobiles, trains, and airplanes, ceilings, and interiors, shirts, jackets, and casual wear. Uppers and trims of shoes, sports shoes, men's shoes, women's shoes, etc., bags, belts, wallets, etc., clothing materials used in some of them, industrial materials such as wiping cloths, polishing cloths, CD curtains, etc. It can also be suitably used as

Hereinafter, the present invention will be specifically explained based on Examples and Comparative Examples, but the Examples do not limit the scope of the present invention. Each physical property, quality, etc. of the artificial leather samples according to Examples and Comparative Examples were evaluated using the following procedures and methods.

(1) _T2 relaxation time Tl (μ seconds) of L component (Lorentz component) and fraction Cl (%) of L component
- Pretreatment The artificial leather sample cut with scissors was packed into a glass tube for pulsed NMR measurement with a diameter of 1 cm to a height of about 1.0 cm to 1.5 cm, and used for measurement.
-Measurement Observation was made using a pulse NMR device ("Minispec MQ20" manufactured by Bruker Japan). The observation conditions were as follows.
Measuring nucleus: ^1H
Measurement method: Solid echo method Number of integration: 256 times Repetition time: 3s
Measurement temperature: 50℃
・Analysis The obtained free induction decay curve of spin-spin relaxation of ^1H is divided into two curves derived from two components: a low-mobility Gaussian component (S component) and a high-mobility Lorentz component (L component). Assuming the following equation 1:
M(t)=Cs*exp((-1/2)*(t/Ts) ² )+Cl*exp(-t/Tl)...Formula 1
{where M(t) is the signal strength at a certain time t, Cs is the fraction of the low-mobility component, Cl is the fraction of the high-mobility component, and Ts is the fraction of the low-mobility component is the T ₂ relaxation time of the active component, and Tl is the T ₂ relaxation time of the highly active component. } was used for fitting. Incidentally, during the fitting, all variables (Cs, Cl, Ts, Tl) were used as variable parameters. The fitting range was 0ms to 0.6ms.

(2) Emboss rate (%)
The embossing rate is determined by the following formula based on the area (S1) of the convex portion in the area (S0) of the embossing roll:
Emboss rate (%) = S1/S0 x 100
Calculated by.

(3) Clarity of emboss (grade)
・Pre-treatment: Insert the sample at a speed of 2.0 m/min between an embossing roll with a convex height of 300 μm and an embossing rate of 40% heated to 200°C and a presser roll, and embossing at a linear pressure of 60 kg/cm. A sample with a concave design was obtained.
・Evaluation The clarity of the embossing is determined by measuring the cross section of the obtained sample at a total of 20 points using a caliper, and calculating the average value (d) of the depth of the concave part of the cross section using the height (D) of the convex part of the presser roll. , the following formula:
Emboss clarity A (%) = d/D x 100
Calculated by.
The clarity of the resulting embossing was judged according to the following series evaluation criteria:
Grade 5: 30%≦A, the concave design is clear;
Grade 4: 25%≦A<30%, and the concave design is partially unclear;
Grade 3: 20%≦A<25%, half of the concave design is unclear;
Grade 2: 15%≦A<20%, and most of the concave design is unclear;
Grade 1: 15%>A, the concave design is unclear.

(4) Ratio of PU resin to the total fiber mass of the sheet-like product and ratio of PU resin to the fiber sheet filled with PU resin The ratio of PU resin to the total fiber mass of the sheet-like product was measured using the following method. .
Let A (g) be the mass of the fiber sheet before impregnation with PU resin. A fiber sheet is impregnated with the PU resin dispersion, then heated and dried at 130°C using a pin tenter dryer, then soaked in hot water heated to 90°C and made into a soft cloth, and then dried to remove the PU resin. A filled fiber sheet (hereinafter also referred to as "resin-filled fiber sheet") is obtained. Let the mass of the resin-filled fiber sheet (sheet-like material) be B1 (g). The ratio of PU resin to the total fiber mass of the sheet material (C1) and the ratio of PU resin to the resin-filled fiber sheet (D1) are calculated using the following formula:
C1=(B1-A)/A×100(wt%)
D1=(B1-A)/B1×100(wt%)
Calculated by

(5) Average diameter of single fibers in fiber sheet (μm)
The average diameter of the fibers constituting the fiber sheet is determined by photographing the first outer surface of the artificial leather at a magnification of 1500 times using a scanning electron microscope (SEM, "JSM-5610" manufactured by JEOL). Randomly select 100 fibers forming the outer surface of 1, measure the diameter of the cross section of the single fiber, and obtain the arithmetic mean value of the 100 measured values.
If the observed shape of the cross section of a single fiber is not circular, the distance between the outer circumferences on a straight line perpendicular to the midpoint of the longest diameter of the cross section of the single fiber is defined as the fiber diameter.
FIG. 2 is a conceptual diagram illustrating how to determine the fiber diameter. For example, when the cross section A of the fiber is elliptical as shown in FIG. 2, the fiber diameter is defined as the distance c between the outer circumferences on a straight line b perpendicular to the midpoint p of the longest diameter a of the cross section A in the observed image.

(6) Average primary particle size of PU resin in PU resin dispersion Measured using a laser diffraction particle size distribution analyzer (“LA-920” manufactured by Horiba, Ltd.) according to the device measurement manual, and the median diameter was determined. It was defined as the average primary particle diameter.

(7) Degree of saponification of hot water-soluble resin Measured according to JIS K 6726 (1994) 3.5.

(8) Degree of polymerization of hot water soluble resin (PVA) Measured according to JIS K 6726 (1994) 3.7.

[Preparation method of water-dispersed polyurethane resin]
[Synthesis Example 1: Preparation of water-dispersed polyurethane resin A]
1,6-hexanediol polycarbonate polyol (manufactured by Asahi Kasei Corp., "Duranol") with an Mn of 2,000 was added as a polymer polyol to a pressurizable reaction apparatus equipped with a stirrer, a thermometer, and a heating device under a nitrogen stream. T6002", hereinafter abbreviated as PC-1) 154.0 parts by mass (molar part 0.0770), a polymethyl methacrylate macromonomer with Mn of 6,000 ("AA" manufactured by Toagosei Co., Ltd.) as a macromonomer -6", hereinafter abbreviated as M-1) 23.1 parts by mass (mol part 0.00385), 1.2 parts by mass of 1,4-butanediol (molecular weight 30.12, mole part) as short chain diol 0.014), 5.2 parts by mass of 2,2-dimethylolpropionic acid (molecular weight 134.13, molar part 0.039) as a hydrophilic agent, and 96.3 parts by mass of methyl ethyl ketone (molecular weight 72.11, molar part) as a solvent. 1.34) and mixed uniformly, 40.4 parts by mass of dicyclohexylmethane diisocyanate (molecular weight 262.35, molar part 0.154) was added as an isocyanate, and then 0.01 part by mass of dibutyltin dilaurate as a catalyst. was added and reacted for 400 minutes at 75° C. in a dry nitrogen atmosphere to obtain a methyl ethyl ketone solution of a urethane prepolymer having isocyanate groups at the molecular ends and having a free isocyanate group content of 2.4% by mass based on the solid content. After cooling this solution to 30 ° C. or lower, 3.9 parts by mass of triethylamine (molecular weight 101.19, molar part 0.039) was added as a neutralizing agent to neutralize the carboxyl groups in the urethane prepolymer. Add 360.7 parts by mass of water (molecular weight 18.015, mol parts 20.0), and then add 2.1 parts by mass (molecular weight 60.1, mol parts) of ethylenediamine (hereinafter abbreviated as EDA) as a chain extender. 0.035) was added and reacted. After the reaction was completed, methyl ethyl ketone was distilled off under reduced pressure to obtain an aqueous urethane resin composition (hereinafter referred to as resin A) (nonvolatile content: 40% by mass, average primary particle size: 0.34 μm).

[Synthesis Example 2: Preparation of water-dispersed polyurethane resin B]
In a pressurizable reaction apparatus equipped with a stirrer, a thermometer, and a heating device, 77.0 parts by mass of polycarbonate diol PC-1 (molecular weight 2000, molar part 0.0385) was added as a polymer polyol under a nitrogen stream. and polycarbonate diol with Mn of 2,000 (manufactured by Asahi Kasei Corp. "Duranol T5652", hereinafter abbreviated as PC-2), 77.0 parts by mass (mol part 0.0385), polymethyl methacrylate type as a macromonomer Macromonomer M-1 4.6 parts by mass (molecular weight 6000, molar part 0.00077), ethylene glycol 1.0 parts by mass (molecular weight 62.07, 0.015) as a short chain diol, 2,2- as a hydrophilic agent 5.2 parts by mass of dimethylolpropionic acid (molecular weight 134.13, molar part 0.039) and 94.4 parts by mass of methyl ethyl ketone (molecular weight 72.11, molar part 1.31) as a solvent were charged and mixed uniformly. , 40.4 parts by mass of dicyclohexylmethane diisocyanate (molecular weight 262.35, molar part 0.154) was added as an isocyanate, then 0.01 part by mass of dibutyltin dilaurate was added as a catalyst, and the mixture was heated at 75°C for 400 minutes under a dry nitrogen atmosphere. The reaction was carried out to obtain a methyl ethyl ketone solution of a urethane prepolymer having an isocyanate group at the molecular end and having a free isocyanate group content of 2.8% by mass based on the solid content. After cooling this solution to 30 ° C. or lower, 3.9 parts by mass of triethylamine (molecular weight 101.19, molar part 0.039) was added as a neutralizing agent to neutralize the carboxyl groups in the urethane prepolymer. 346.8 parts by mass of water (molecular weight 18.015, molar part 19.3) was added, and then 3.6 parts by mass of piperazine (molecular weight 86.14, molar part 0.042) was added as a chain extender and reacted. . After the reaction was completed, methyl ethyl ketone was distilled off under reduced pressure to obtain an aqueous urethane resin composition (hereinafter referred to as resin B) (non-volatile content: 40% by mass, average primary particle size: 0.53 μm).

[Synthesis Example 3: Preparation of water-dispersed polyurethane resin C]
101.6 parts by mass of polycarbonate diol PC-2 (molecular weight 20,000, molar part 0.0508) as a polymer polyol was added to a pressurizable reaction apparatus equipped with a stirrer, a thermometer, and a heating device under a nitrogen stream. 78.5 parts by mass (mol part 0.0262) of polyether diol with Mn of 3,000 ("PTMG3000" manufactured by Mitsubishi Chemical Corporation, hereinafter abbreviated as PTMG), polymethyl methacrylate-based macromonomer as a macromonomer M-1 13.9 parts by mass (molecular weight 6000, molar part 0.00231), 1.1 parts by mass of 1,4-butanediol as short chain diol (molecular weight 90.12, molar part 0.012), hydrophilic agent 5.2 parts by mass of 2,2-dimethylolpropionic acid (molecular weight 134.13, molar part 0.039) and 103.3 parts by mass of methyl ethyl ketone (molecular weight 72.11, molar part 1.43) were charged as a solvent. After uniformly mixing, 34.2 parts by mass of isophorone diisocyanate (molecular weight 222.3, molar part 0.154) was added as an isocyanate, then 0.01 part by mass of dibutyltin dilaurate was added as a catalyst, and 75 parts by mass of dibutyltin dilaurate was added as an isocyanate. The reaction was carried out at ℃ for 400 minutes to obtain a methyl ethyl ketone solution of a urethane prepolymer having an isocyanate group at the molecular end and having a free isocyanate group content of 2.2% by mass based on the solid content. After cooling this solution to 30 ° C. or lower, 3.9 parts by mass of triethylamine (molecular weight 101.19, molar part 0.039) was added as a neutralizing agent to neutralize the carboxyl groups in the urethane prepolymer. 327.1 parts by mass of water (molecular weight 18.015, molar part 18.2) was added, and then 2.1 parts by mass of EDA (molecular weight 60.1, molar part 0.035) was added as a chain extender to cause a reaction. After the reaction was completed, methyl ethyl ketone was distilled off under reduced pressure to obtain an aqueous urethane resin composition (hereinafter referred to as resin C) (non-volatile content: 40% by mass, average primary particle size: 0.19 μm).

[Synthesis Example 4: Preparation of water-dispersed polyurethane resin D]
In a pressurizable reaction apparatus equipped with a stirrer, a thermometer, and a heating device, 61.6 parts by mass of polycarbonate diol PC-2 (molecular weight 2000, molar part 0.0308) was added as a polymer polyol under a nitrogen stream. 138.6 parts by mass of polyether diol PTMG (molecular weight 3000, molar part 0.0462), 32.3 parts by mass of polymethyl methacrylate macromonomer M-1 (molecular weight 6000, molar part 0.00539) as a macromonomer, short chain 1.0 parts by mass of ethylene glycol (molecular weight 62.07, molar part 0.015) as a diol, 5.2 parts by mass of 2,2-dimethylolpropionic acid (molecular weight 134.13, molar part 0.039) as a hydrophilic agent. ), 97.7 parts by mass of methyl ethyl ketone (molecular weight 72.11, molar part 1.36) was charged as a solvent and mixed uniformly. .154) was added, and then 0.01 part by mass of dibutyltin dilaurate was added as a catalyst, and the reaction was carried out at 75°C for 400 minutes in a dry nitrogen atmosphere to form a molecular terminal with a free isocyanate group content of 1.6% by mass based on the solid content. A methyl ethyl ketone solution of a urethane prepolymer having isocyanate groups was obtained. After cooling this solution to 30 ° C. or lower, 3.9 parts by mass of triethylamine (molecular weight 101.19, molar part 0.039) was added as a neutralizing agent to neutralize the carboxyl groups in the urethane prepolymer. 342.8 parts by mass of water (molecular weight 18.015, molar part 19.0) was added, and then 3.8 parts by mass of piperazine (molecular weight 86.14, molar part 0.045) was added as a chain extender and reacted. . After the reaction was completed, methyl ethyl ketone was distilled off under reduced pressure to obtain an aqueous urethane resin composition (hereinafter referred to as resin D) (nonvolatile content: 40% by mass, average primary particle size: 0.28 μm).

[Synthesis Example 5: Preparation of water-dispersed polyurethane resin E]
154.0 parts by mass of polycarbonate diol PC-2 (molecular weight 2000, molar part 0.0770) as a polymer polyol was added to a pressurizable reaction apparatus equipped with a stirrer, a thermometer, and a heating device under a nitrogen stream. 69.3 parts by mass of polymethyl methacrylate macromonomer M-1 (molecular weight 6000, molar part 0.00770) as a monomer, 1.2 parts by mass of 1,4-butanediol (molecular weight 90.12, molar part) as a short chain diol. 0.01386), 5.2 parts by mass of 2,2-dimethylolpropionic acid (molecular weight 134.13, molar part 0.039) as a hydrophilizing agent, and 88.0 parts by mass of methyl ethyl ketone (molecular weight 72.11, molar part) as a solvent. 1.22) and mixed uniformly, 34.2 parts by mass of isophorone diisocyanate (molecular weight 222.3, molar part 0.154) was added as an isocyanate, and then 0.01 part by mass of dibutyltin dilaurate was added as a catalyst. In addition, a reaction was carried out at 75° C. for 400 minutes in a dry nitrogen atmosphere to obtain a methyl ethyl ketone solution of a urethane prepolymer having isocyanate groups at the molecular ends and having a free isocyanate group content of 1.5% by mass based on the solid content. After cooling this solution to 30 ° C. or lower, 3.9 parts by mass of triethylamine (molecular weight 101.19, molar part 0.039) was added as a neutralizing agent to neutralize the carboxyl groups in the urethane prepolymer. 389.1 parts by mass of water (molecular weight 18.015, molar part 21.6) was added, and then 3.3 parts by mass of diethylenetriamine (molecular weight 103.17, molar part 0.032) was added as a chain extender and reacted. . After the reaction was completed, methyl ethyl ketone was distilled off under reduced pressure to obtain an aqueous urethane resin composition (hereinafter referred to as resin E) (nonvolatile content: 40% by mass, average primary particle size: 0.39 μm).

[Synthesis Example 6: Preparation of water-dispersed polyurethane resin F]
154.0 parts by mass of polycarbonate diol PC-2 (molecular weight 2000, molar part 0.0770) as a polymer polyol was added to a pressurizable reaction apparatus equipped with a stirrer, a thermometer, and a heating device under a nitrogen stream. 69.3 parts by mass of polymethyl methacrylate macromonomer M-1 (molecular weight 6000, molar part 0.0116) as a monomer, 0.80 parts by mass of ethylene glycol (molecular weight 62.07, molar part 0.012) as a short chain diol. , 5.2 parts by mass of 2,2-dimethylolpropionic acid (molecular weight 134.13, molar part 0.039) as a hydrophilic agent, 81.0 parts by mass of methyl ethyl ketone (molecular weight 72.11, molar part 1.12) as a solvent. ) and mixed uniformly, 34.2 parts by mass of isophorone diisocyanate (molecular weight 222.3, molar part 0.154) was added as an isocyanate, then 0.01 part by mass of dibutyltin dilaurate was added as a catalyst, and the mixture was heated with dry nitrogen. The reaction was carried out in an atmosphere at 75° C. for 400 minutes to obtain a methyl ethyl ketone solution of a urethane prepolymer having an isocyanate group at the molecular end and having a free isocyanate group content of 2.3% by mass based on the solid content. After cooling this solution to 30 ° C. or lower, 3.9 parts by mass of triethylamine (molecular weight 101.19, molar part 0.039) was added as a neutralizing agent to neutralize the carboxyl groups in the urethane prepolymer. 433.6 parts by mass of water (molecular weight 18.015, molar part 24.1) was added, and then 6.3 parts by mass of isophoronediamine (molecular weight 170.3, molar part 0.037) was added as a chain extender and reacted. Ta. After the reaction was completed, methyl ethyl ketone was distilled off under reduced pressure to obtain an aqueous urethane resin composition (hereinafter referred to as resin F) (nonvolatile content: 40% by mass, average primary particle size: 0.52 μm).

[Synthesis Example 7: Preparation of water-dispersed polyurethane resin G]
In a pressurizable reaction apparatus equipped with a stirrer, a thermometer, and a heating device, 154.0 parts by mass of child polycarbonate diol PC-2 (molecular weight 2000, molar part 0.0770) as a polymer polyol was added under a nitrogen stream. 0.80 parts by mass of ethylene glycol (molecular weight 62.07, molar part 0.012) as a short chain diol, 5.2 parts by mass of 2,2-dimethylolpropionic acid (molecular weight 134.13, molar part 0) as a hydrophilic agent. .039), 97.2 parts by mass of methyl ethyl ketone (molecular weight 72.11, mol parts 1.35) was charged as a solvent, and after uniformly mixing, 25.9 parts by mass of hexamethylene diisocyanate (molecular weight 168.2, mol parts) was added as an isocyanate. 0.154 parts) and then 0.01 parts by mass of dibutyltin dilaurate as a catalyst, and the reaction was carried out at 75°C for 400 minutes in a dry nitrogen atmosphere to give a free isocyanate group content of 2.3% by mass based on the solid content. A methyl ethyl ketone solution of a urethane prepolymer having isocyanate groups at the molecular ends was obtained. After cooling this solution to 30 ° C. or lower, 3.9 parts by mass of triethylamine (molecular weight 101.19, molar part 0.039) was added as a neutralizing agent to neutralize the carboxyl groups in the urethane prepolymer. 485.2 parts by mass of water (molecular weight 18.015, molar part 26.9) was added, and then 2.6 parts by mass of ethylenediamine (molecular weight 60.1, molar part 0.034) was added as a chain extender and reacted. . After the reaction was completed, methyl ethyl ketone was distilled off under reduced pressure to obtain an aqueous urethane resin composition (hereinafter referred to as resin G) (non-volatile content: 40% by mass, average primary particle size: 0.40 μm).

[Synthesis Example 8: Preparation of water-dispersed polyurethane resin H]
154.0 parts by mass of polycarbonate diol PC-2 (molecular weight 2000, molar part 0.0770) as a polymer polyol was added to a pressurizable reaction apparatus equipped with a stirrer, a thermometer, and a heating device under a nitrogen stream. As a monomer, 4.6 parts by mass of polydimethylsiloxane macromonomer ("X-22-176DX" manufactured by Shin-Etsu Chemical Co., Ltd., hereinafter abbreviated as M-2) (molecular weight 3000, molar part 0.015), 1.2 parts by mass of 1,4-butanediol (molecular weight 90.12, molar part 0.014) as a short chain diol, 5.2 parts by mass of 2,2-dimethylolpropionic acid (molecular weight 134.13) as a hydrophilic agent. , molar part 0.039) and 98.6 parts by mass of methyl ethyl ketone (molecular weight 72.11, molar part 1.37) as a solvent and mixed uniformly. .35, molar part 0.154), then 0.01 part by mass of dibutyltin dilaurate was added as a catalyst, and the reaction was carried out at 75°C for 400 minutes in a dry nitrogen atmosphere until the free isocyanate group content relative to the solid content was 2. A methyl ethyl ketone solution of 9% by mass of a urethane prepolymer having isocyanate groups at the molecular ends was obtained. After cooling this solution to 30 ° C. or lower, 3.9 parts by mass of triethylamine (molecular weight 101.19, molar part 0.039) was added as a neutralizing agent to neutralize the carboxyl groups in the urethane prepolymer. 411.5 parts by mass of water (molecular weight 18.015, molar part 22.8) was added, and then 2.6 parts by mass of ethylenediamine (molecular weight 60.1, molar part 0.043) was added as a chain extender and reacted. . After the reaction was completed, methyl ethyl ketone was distilled off under reduced pressure to obtain an aqueous urethane resin composition (hereinafter referred to as Resin H) (non-volatile content: 40% by mass, average primary particle size: 0.38 μm).

[Synthesis Example 9: Preparation of water-dispersed polyurethane resin I]
In a pressurizable reaction apparatus equipped with a stirrer, a thermometer, and a heating device, 154.0 parts by mass of polycarbonate diol PC-2 (molecular weight 2000, molar part 0.077) as a polymeric polyol was added under a nitrogen stream. As a monomer, 21.6 parts by mass of polydimethylsiloxane macromonomer ("X-22-177GX-A" manufactured by Shin-Etsu Chemical Co., Ltd., hereinafter abbreviated as M-3) (molecular weight 14000, molar part 0.00154) ), 1.4 parts by mass of 1,4-butanediol (molecular weight 90.12, molar part 0.015) as a short chain diol, 5.2 parts by mass of 2,2-dimethylolpropionic acid (molecular weight 134) as a hydrophilic agent. .13, molar part 0.039), 87.7 parts by mass of methyl ethyl ketone (molecular weight 72.11, molar part 1.22) as a solvent and mixed uniformly, and 34.2 parts by mass of isophorone diisocyanate (mole part 222.3, molar part 0.154), then 0.01 part by mass of dibutyltin dilaurate was added as a catalyst, and the reaction was carried out at 75°C for 400 minutes in a dry nitrogen atmosphere until the free isocyanate group content relative to the solid content was 2. A methyl ethyl ketone solution of a urethane prepolymer having an isocyanate group at the molecular end of .2% by mass was obtained. After cooling this solution to 30 ° C. or lower, 3.9 parts by mass of triethylamine (molecular weight 101.19, molar part 0.039) was added as a neutralizing agent to neutralize the carboxyl groups in the urethane prepolymer. 458.9 parts by mass of water (molecular weight 18.015, molar part 25.5) was added, and then 2.3 parts by mass of ethylenediamine (molecular weight 60.1, molar part 0.039) was added as a chain extender and reacted. . After the reaction was completed, methyl ethyl ketone was distilled off under reduced pressure to obtain an aqueous urethane resin composition (hereinafter referred to as Resin I) (non-volatile content: 40% by mass, average primary particle size: 0.20 μm).

[Manufacture of artificial leather]
[Example 1]
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, with a composite ratio of 20% by mass of the sea component and 80% by mass of the island component. A sea-island composite fiber having several 16 islands/1f and an average fiber diameter of 18 μm was obtained. The obtained sea-island type composite fibers were cut into staples with a fiber length of 51 mm, passed through a card and a cross wrapper to form a fiber web, and after laminating the obtained fiber webs, a fiber sheet was obtained by needle punching. The obtained fiber sheet was immersed in 95° C. hot water to shrink and dried at 100° C. for 5 minutes using a pin tenter dryer to obtain a single-layer fiber sheet with a basis weight of 600 g/m ² .
The obtained fiber sheet was immersed in an aqueous sodium hydroxide solution with a concentration of 10 g/L heated to a temperature of 95° C. and treated for 25 minutes to perform a sea-removal treatment to remove the sea component of the sea-island composite fiber. The average diameter of the single fibers constituting the fiber sheet after sea removal was 4 μm.
Next, PVA (N-300 manufactured by Nippon Gosei Kagaku Co., Ltd.) with a degree of saponification of 98 to 99% and a degree of polymerization of 1200 was added to water at a temperature of 25°C, and after raising the temperature to 90°C, The temperature was maintained at 90° C. while stirring for 2 hours to prepare an aqueous solution with a solid content of 10% by mass to obtain a PVA aqueous solution. The above sea-removed fiber sheet was impregnated with the above PVA aqueous solution and heated and dried at a temperature of 140°C for 10 minutes to obtain a PVA-applied sheet with a PVA adhesion amount of 15% by mass based on the fiber mass of the fiber sheet. Ta.
Thereafter, the amount of the water-dispersed polyurethane resin A obtained in Synthesis Example 1 in the impregnating liquid was 25.0% (as solid content mass %), and the amount of anhydrous sodium sulfate (sodium sulfate) in the impregnating liquid was added as an impregnation aid. The above PVA-applied sheet was impregnated with an impregnating solution containing 3.0% by weight (in terms of mass% of solid content), then coagulated under wet heat at 100°C for 5 minutes, and dried with hot air for 5 minutes at 130°C using a hot air dryer. I let it happen.
Thereafter, it was immersed in hot water heated to 95° C. to remove the impregnated anhydrous sodium sulfate, thereby obtaining a sheet filled with water-dispersed PU resin. The ratio of the water-dispersed PU resin to the total fiber mass of this sheet-like material was 29% by mass.
Thereafter, the sheet-like material was cut in half perpendicular to the thickness direction using a half-cutting machine with an endless band knife, and the uncut side was brushed with #400 emery paper, and the dye concentration was 5. It was dyed with .0% owf blue disperse dye ("BlueFBL" manufactured by Sumitomo Chemical Co., Ltd.) using a jet dyeing machine at 130° C. for 15 minutes, and then subjected to reduction cleaning. Thereafter, it was dried at 100° C. for 5 minutes using a hot air dryer to obtain a single layer of artificial leather.

[Example 2]
Artificial leather was obtained in the same manner as in Example 1, except that the fiber sheet was impregnated with the water-dispersed polyurethane resin B obtained in Synthesis Example 2, and the ratio of the PU resin to the fiber sheet was 27% by mass.

[Example 3]
Artificial leather was obtained in the same manner as in Example 1, except that the fiber sheet was impregnated with the water-dispersed polyurethane resin C obtained in Synthesis Example 3, and the ratio of the PU resin to the fiber sheet was 28% by mass.

[Example 4]
Artificial leather was obtained in the same manner as in Example 1, except that the fiber sheet was impregnated with the water-dispersed polyurethane resin D obtained in Synthesis Example 4, and the ratio of PU resin to the fiber sheet was 27% by mass.

[Example 5]
The staple of Example 1 was passed through a card and a cross wrapper to produce a fibrous web having a basis weight of 128 g/m ² and used as the fibrous layer (A). In addition, a fibrous web with a basis weight of 60 g/m ² was produced in the same manner and used as the fibrous layer (B).
A scrim (plain fabric) with a basis weight of 95 g/m ² made of polyethylene terephthalate fibers of 166 dtex/48 f is inserted between the fiber layer (A) and the fiber layer (B) to form a three-layer laminate, and then needle punched. This resulted in a fiber sheet with a three-layer structure.
The sheet-like material was immersed in hot water at a temperature of 97°C to shrink it, dried for 5 minutes at 100°C using a pin tenter dryer, and then heated to a temperature of 95°C in an aqueous sodium hydroxide solution with a concentration of 10 g/L. The fibers were immersed in water and treated for 25 minutes to perform sea-removal treatment to remove the sea components of the sea-island type composite fibers. The average diameter of the single fibers constituting the fiber sheet after sea removal was 4 μm.
Next, PVA (N-300 manufactured by Nippon Gosei Kagaku Co., Ltd.) with a degree of saponification of 98 to 99% and a degree of polymerization of 1200 was added to water at a temperature of 25°C, and after raising the temperature to 90°C, The temperature was maintained at 90° C. while stirring for 2 hours to prepare an aqueous solution with a solid content of 10% by mass to obtain a PVA aqueous solution. The above sea-removed fiber sheet was impregnated with the above PVA aqueous solution and heated and dried at a temperature of 140°C for 10 minutes to obtain a PVA-applied sheet with a PVA adhesion amount of 15% by mass based on the fiber mass of the fiber sheet. Ta.
Thereafter, the amount of the water-dispersed polyurethane resin E obtained in Synthesis Example 5 in the impregnating liquid (in terms of mass % of solid content) was 25.0%, and the amount of anhydrous sodium sulfate in the impregnating liquid (in terms of solid content) was added as an impregnation aid. The PVA-applied sheet was impregnated with an impregnating solution containing 3.0% by weight (in terms of mass%), and then coagulated under wet heat at 100°C for 5 minutes, and dried with hot air at 130°C for 5 minutes using a hot air dryer.
Thereafter, it was immersed in hot water heated to 95° C. to remove the impregnated anhydrous sodium sulfate, thereby obtaining a sheet filled with water-dispersed PU resin. The ratio of the water-dispersed PU resin to the total fiber mass of this sheet-like material was 28% by mass.
The outer surface of the fiber layer (A) of the sheet-like product was brushed using #400 emery paper, and then treated with a blue disperse dye ("BlueFBL" manufactured by Sumitomo Chemical Co., Ltd.) with a dye concentration of 5.0% owf. It was dyed at 130° C. for 15 minutes using a jet dyeing machine, and then subjected to reduction washing. Thereafter, it was dried at 100° C. for 5 minutes using a hot air dryer to obtain artificial leather having a three-layer structure.

[Example 6]
Artificial leather was obtained in the same manner as in Example 3, except that the ratio of PU resin to the fiber sheet was 37% by mass.

[Example 7]
Artificial leather was obtained in the same manner as in Example 3, except that the ratio of PU resin to the fiber sheet was 18% by mass.

[Example 8]
Artificial leather was obtained in the same manner as in Example 4, except that the ratio of PU resin to the fiber sheet was 37% by mass.

[Example 9]
Artificial leather was obtained in the same manner as in Example 4, except that the ratio of PU resin to the fiber sheet was 18% by mass.

[Example 10]
Artificial leather was obtained in the same manner as in Example 5, except that the ratio of PU resin to the fiber sheet was 37% by mass.

[Example 11]
Artificial leather was obtained in the same manner as in Example 5, except that the ratio of PU resin to the fiber sheet was 18% by mass.

[Comparative example 1]
Artificial leather was obtained in the same manner as in Example 4, except that the ratio of PU resin to the fiber sheet was 12% by mass.

[Comparative example 2]
Artificial leather was obtained in the same manner as in Example 4, except that the ratio of PU resin to the fiber sheet was 51% by mass.

[Comparative example 3]
Artificial leather was obtained in the same manner as in Example 1, except that the fiber sheet was impregnated with the water-dispersed polyurethane resin F obtained in Synthesis Example 6, and the ratio of PU resin to the fiber sheet was 12% by mass.

[Comparative example 4]
Artificial leather was obtained in the same manner as in Example 1, except that the fiber sheet was impregnated with the water-dispersed polyurethane resin G obtained in Synthesis Example 7, and the ratio of PU resin to the fiber sheet was 12% by mass.

[Comparative example 5]
Artificial leather was obtained in the same manner as in Example 1, except that the fiber sheet was impregnated with the water-dispersed polyurethane resin H obtained in Synthesis Example 8, and the ratio of PU resin to the fiber sheet was 30% by mass.

[Comparative example 6]
Artificial leather was obtained in the same manner as in Example 1, except that the fiber sheet was impregnated with the water-dispersed polyurethane resin I obtained in Synthesis Example 9, and the ratio of the PU resin to the fiber sheet was 30% by mass.

[Comparative Example 7]
Artificial leather was obtained in the same manner as in Example 1, except that the fiber sheet was impregnated with the water-dispersed polyurethane resin H obtained in Synthesis Example 8, and the ratio of PU resin to the fiber sheet was 47% by mass.

[Comparative example 8]
Artificial leather was obtained in the same manner as in Example 1, except that the fiber sheet was impregnated with the water-dispersed polyurethane resin I obtained in Synthesis Example 9, and the ratio of the PU resin to the fiber sheet was 50% by mass.

For the artificial leathers obtained in Examples 1 to 11 and Comparative Examples 1 to 8, the values of the spin-spin relaxation time Tl of the L component and the fraction Cl of the L component were determined by pulsed NMR (Solid Echo method) measurement, and , the clarity of the embossing was evaluated. The results are shown in Table 1 below.

From these results, when the free induction decay signal (FID) in pulsed NMR measurement (Solid Echo method, proton observation, measurement temperature 50°C) is fitted with two components: S component (Gaussian component) and L component (Lorentz component). In Examples 1 to 11, in which the spin-spin relaxation time Tl of the L component is 500 μs or more and 800 μs or less, and the fraction Cl of the L component is 25% or more and less than 55%, these values are outside the range. It can be seen that the clarity of the embossing is better than in Comparative Examples 1 to 8.

The artificial leather according to the present invention has a low environmental impact and has excellent embossment clarity, so it can be used as a surface material or interior material for seats for interiors, automobiles, aircraft, railway vehicles, etc., clothing products, etc. It can be suitably used. Specifically, the artificial leather of the present invention can be used as a surface material for furniture, chairs, wall materials, seats in vehicle interiors such as automobiles, trains, and airplanes, ceilings, and interior materials that have a very elegant appearance, and for shirts. , uppers and trims of shoes such as jackets, casual shoes, sports shoes, men's shoes, and women's shoes, bags, belts, wallets, etc., clothing materials used for some of them, wiping cloths, polishing cloths, CD curtains, etc. It can be suitably used as an industrial material.

1 Fiber sheet 11 Scrim (optional)
12 Fiber layer (A)
13 Fiber layer (B)
A Cross section a of the fiber when the cross section is elliptical Longest diameter b of cross section A Straight line c passing through the midpoint p of longest diameter a and orthogonal to longest diameter a Distance between outer circumferences p on straight line b Midpoint of longest diameter a

Claims (8)

An artificial leather made of a nonwoven fabric made of ultrafine fibers with an average single fiber diameter of 0.3 μm or more and 7 μm or less, and water-dispersed polyurethane, and the artificial leather has a When the free induction decay signal (FID) is fitted for two components, the S component (Gaussian component) and the L component (Lorentzian component), the spin-spin relaxation time Tl of the L component is 500 μs or more and 800 μs or less, and the L component An artificial leather having a Cl fraction of 25% or more and less than 55%. The artificial leather according to claim 1, wherein the ultrafine fiber is a polyester fiber. The artificial leather according to claim 1 or 2, wherein the nonwoven fabric is intertwined and integrated with a scrim layer that is a woven fabric. The artificial leather according to claim 3, wherein the scrim layer is a woven fabric of polyester fibers. The water-dispersed polyurethane comprises a methyl methacrylate macromonomer having two hydroxyl groups at one end, a polymer polyol having hydroxyl groups at both ends, a short chain diol having hydroxyl groups at both ends, and a hydrophilic agent. The artificial leather according to claim 1 or 2, which is obtained by a reaction between an organic diisocyanate and a chain extender. The artificial leather according to claim 5, wherein the polymer polyol is a polycarbonate diol and/or a polyether diol. The artificial leather according to claim 6, wherein the polycarbonate diol is a copolymerized polycarbonate diol obtained by copolymerizing two or more types of polyhydric alcohols. The artificial leather according to claim 5, wherein the ratio of the methyl methacrylate macromonomer having two hydroxyl groups at one end to the organic diisocyanate is 0.1 mol% or more and 7.0 mol% or less.

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