JP2022101943A - Artificial leather - Google Patents

Abstract

To provide an artificial leather achieving soft feeling and excellent durability and a manufacturing method thereof.SOLUTION: An artificial leather contains fibrous base material formed of ultrafine fibers having an average single fiber diameter of 0.1 μm or more and 10 μm or less and elastomer. The elastomer contains polyurethane having hydrophilic group and a compound having isocyanate group. Ratio of the isocyanate group to urethane bond in the polyurethane is 0.01% or more and 1% or less.SELECTED DRAWING: None

Description

The present invention relates to artificial leather having excellent long-term durability.

Artificial leather, which is mainly composed of a fibrous base material such as non-woven fabric and polyurethane, has excellent characteristics not found in natural leather, and its use has been expanding year by year for clothing, chair upholstery, automobile interior materials, and the like. In producing such artificial leather, the fibrous base material is impregnated with an organic solvent solution of polyurethane, and then the obtained fibrous base material is immersed in water or an aqueous solution of an organic solvent which is a non-solvent of polyurethane. A combination of steps of wet coagulation of polyurethane is generally adopted. However, since organic solvents are generally highly harmful to the human body and the environment, there is a strong demand for a method that does not use organic solvents in the production of artificial leather.

As a specific solution, a method of using a water-dispersed polyurethane in which a polyurethane resin is dispersed in water is being studied instead of the conventional organic solvent-based polyurethane.

However, artificial leather obtained by impregnating a fibrous base material with a water-dispersible polyurethane liquid and coagulating the polyurethane has a problem that its physical properties tend to deteriorate when wet, and by imparting a crosslinked structure to the polyurethane, the water-dispersible polyurethane It has been proposed to suppress deterioration of physical properties due to application (see Patent Documents 1 and 2).

International Publication No. 2015/115290 International Publication No. 2019/025964

In the methods disclosed in Patent Documents 1 and 2, it is possible to improve the strength required for artificial leather to some extent by imparting a crosslinked structure to polyurethane. However, the long-term moisture resistance is insufficient, and further improvement is required.

Therefore, an object of the present invention is to provide artificial leather having excellent long-term durability in view of the background of the above-mentioned prior art.

As a result of repeated studies by the present inventors to achieve the above object, by containing a specific amount of a compound having an isocyanate group in the polymer elastic body, artificial leather can be produced by a simple and environmentally friendly process. We have found that an artificial leather having excellent long-term moisture resistance can be obtained without any problems, and have reached the present invention.

That is, the present invention is to solve the above-mentioned problems, and the artificial leather of the present invention is a fibrous base material made of ultrafine fibers having an average single fiber diameter of 0.1 μm or more and 10 μm or less, and a polymer elastic body. In the artificial leather containing the above, the polymer elastic body contains a polyurethane having a hydrophilic group and a compound having an isocyanate group, and the ratio of the isocyanate group to the urethane bond in the polyurethane is , 0.01% or more and 1% or less.

According to a preferred embodiment of the artificial leather of the present invention, the dissolution ratio to N, N-dimethylformamide at 25 ° C. is 20% by mass or less.

According to a preferred embodiment of the artificial leather of the present invention, the polyurethane contains a polyether diol and / or a polycarbonate diol as a constituent.

According to a preferred embodiment of the artificial leather of the present invention, the above-mentioned compound having an isocyanate group is a triisocyanate compound.

According to the present invention, artificial leather having both a soft texture and excellent moisture resistance can be obtained.

The artificial leather of the present invention is an artificial leather containing a fibrous base material made of ultrafine fibers having an average single fiber diameter of 0.1 μm or more and 10 μm or less and a polymer elastic body, and the polymer elastic body is described as described above. It contains a polyurethane having a hydrophilic group and a compound having an isocyanate group, and the ratio of the isocyanate group to the urethane bond in the polyurethane is 0.01% or more and 1% or less.

This component will be described in detail below, but the present invention is not limited to the scope described below as long as the gist thereof is not exceeded.

[Ultrafine fiber]
Examples of the resin that can be used for the ultrafine fibers used in the present invention include polyester-based resins and polyamide-based resins from the viewpoint of excellent durability, particularly mechanical strength, heat resistance, and light resistance. Specific examples of the polyester resin include polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate and the like. The polyester resin can be obtained from, for example, a dicarboxylic acid and / or an ester-forming derivative thereof and a diol.

Examples of the dicarboxylic acid and / or its ester-forming derivative used in the polyester resin include terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, diphenyl-4,4'-dicarboxylic acid and its ester-forming derivative. And so on. The ester-forming derivative referred to in the present invention is a lower alkyl ester of a dicarboxylic acid, an acid anhydride, an acyl chloride or the like. Specifically, methyl ester, ethyl ester, hydroxy ethyl ester and the like are preferably used. A more preferred embodiment of the dicarboxylic acid and / or an ester-forming derivative thereof used in the present invention is terephthalic acid and / or a dimethyl ester thereof.

Examples of the diol used in the polyester resin include ethylene glycol, 1,3-propanediol, 1,4-butanediol, cyclohexanedimethanol and the like. Of these, ethylene glycol is preferably used.

When a polyamide-based resin is used as the resin used for the ultrafine fibers, polyamide 6, polyamide 66, polyamide 56, polyamide 610, polyamide 11, polyamide 12, copolymerized polyamide and the like can be used.

The resin used for the ultrafine fiber contains inorganic particles such as titanium oxide particles, a lubricant, a pigment, a heat stabilizer, an ultraviolet absorber, a conductive agent, a heat storage agent, an antibacterial agent, and the like, depending on various purposes. Can be done.

As the cross-sectional shape of the ultrafine fiber, either a round cross section or a deformed cross section can be adopted. Specific examples of the irregular cross section include polygons such as ellipses, flats, and triangles, sectors, and crosses.

In the present invention, it is important that the average single fiber diameter of the ultrafine fibers is 0.1 μm or more and 10 μm or less. When the average single fiber diameter of the ultrafine fibers is 10 μm or less, preferably 7 μm or less, more preferably 5 μm or less, the artificial leather can be made more flexible. In addition, the quality of standing hair can be improved. On the other hand, the average single fiber diameter of the ultrafine fibers is 0.1 μm or more, preferably 0.3 μm or more, more preferably 0.7 μm or more, so that the artificial leather has excellent color development after dyeing when dyeing. can do. In addition, when the brushing treatment by buffing is performed, it is possible to improve the ease of dispersal and the ease of handling of the ultrafine fibers existing in a bundle.

The average single fiber diameter referred to in the present invention is measured by the following method. That is,
(1) The cross section of the obtained artificial leather cut in the thickness direction is observed with a scanning electron microscope (SEM).
(2) The fiber diameters of any 50 ultrafine fibers in the observation surface are measured in three directions in each ultrafine fiber cross section. However, when an ultrafine fiber having a modified cross section is adopted, the cross-sectional area of the single fiber is first measured, and the diameter of the circle having the cross-sectional area is calculated by the following formula. The diameter obtained from this is taken as the single fiber diameter of the single fiber. Single fiber diameter (μm) = (4 × (cross-sectional area of single fiber (μm ² )) / π) ^1/2
(3) Calculate the arithmetic mean value (μm) of the total of 150 points obtained, and round off to the second decimal place.

[Fibrous base material]
The fibrous base material used in the present invention comprises the above-mentioned ultrafine fibers. It is permissible for the fibrous base material to be a mixture of ultrafine fibers made of different raw materials.

As a specific form of the fibrous base material, a non-woven fabric in which each of the above-mentioned ultrafine fibers is entangled or a non-woven fabric in which fiber bundles of the ultrafine fibers are entangled can be used. Among them, a non-woven fabric formed by entwining fiber bundles of ultrafine fibers is preferably used from the viewpoint of the strength and texture of artificial leather. From the viewpoint of flexibility and texture, a non-woven fabric in which the ultrafine fibers constituting the fiber bundle of the ultrafine fibers are appropriately separated from each other and have voids is preferably used. As described above, the nonwoven fabric in which the fiber bundles of the ultrafine fibers are entangled can be obtained, for example, by entwining the ultrafine fiber-expressing fibers in advance and then expressing the ultrafine fibers. Further, the non-woven fabric in which the ultrafine fibers constituting the fiber bundle of the ultrafine fibers are appropriately separated from each other and have voids is, for example, a sea-island type composite fiber capable of forming voids between the island components by removing the sea component. It can be obtained by using it.

The non-woven fabric may be either a short-fiber non-woven fabric or a long-fiber non-woven fabric, but a short-fiber non-woven fabric is more preferably used from the viewpoint of the texture and quality of artificial leather.

When the staple fiber non-woven fabric is used, the fiber length of the staple fibers is preferably in the range of 25 mm or more and 90 mm or less. By setting the fiber length to 25 mm or more, more preferably 35 mm or more, still more preferably 40 mm or more, artificial leather having excellent wear resistance can be easily obtained by entanglement. Further, by setting the fiber length to 90 mm or less, more preferably 80 mm or less, still more preferably 70 mm or less, artificial leather having more excellent texture and quality can be obtained.

In the present invention, when a non-woven fabric is used as a fibrous base material, the woven fabric or knitted fabric may be inserted, laminated, or lined inside the non-woven fabric for the purpose of improving the strength. The average single fiber diameter of the fibers constituting such a woven fabric or knitted fabric is more preferably 0.3 μm or more and 10 μm or less because damage during needle punching can be suppressed and strength can be maintained.

As the fibers constituting the above-mentioned woven fabric or knitted fabric, polyesters such as polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate and polylactic acid, synthetic fibers such as polyamide 6 and polyamide 66, and recycled cellulose-based polymers are used. Fibers, natural fibers such as cotton and linen can be used.

[Polymer elastic body]
Next, the artificial leather of the present invention has a polymer elastic body. This polymer elastic body includes "polyurethane having a hydrophilic group" formed by solidification of a polymer elastic precursor having a hydrophilic group as described later, and a compound having an isocyanate group described later. It is a waste. Hereinafter, this detail will be further described.

(1) Polymer elastic precursor First, the polymer elastic precursor according to the present invention has a hydrophilic group. In the present invention, "having a hydrophilic group" means "having a group having active hydrogen" itself. Specific examples of the group having active hydrogen include a hydroxyl group, a carboxyl group, a sulfonic acid group, an amino group and the like.

As the polymer elastic precursor, a polymer polyol described later, an organic diisocyanate, and an active hydrogen component-containing compound having a hydrophilic group are reacted to form a hydrophilic prepolymer, and then a chain extender is used. A water-dispersible polyurethane resin prepared by addition and reaction is more preferably used. The details of these will be described below.

(1-1) Polymer Polyol Examples of the polymer polyol preferably used in the present invention include polyether-based polyols, polyester-based polyols, polycarbonate-based polyols and the like.

First, as the polyether-based polyol, a polyol obtained by adding and polymerizing a monomer such as ethylene oxide, propylene oxide, butylene oxide, styrene oxide, tetrahydrofuran, epichlorohydrin and cyclohexylene with a polyhydric alcohol or polyamine as an initiator, and a polyol. Examples thereof include a polyol obtained by ring-opening polymerization of the above-mentioned monomer using a protonic acid, a Lewis acid, a cation catalyst or the like as a catalyst. Specific examples thereof include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and a copolymerized polyol obtained by combining these.

Next, examples of the polyester-based polyol include a polyester polyol obtained by condensing various low molecular weight polyols with a polybasic acid, a polyol obtained by demultiplexing a lactone, and the like.

Examples of the low molecular weight polyol used for the polyester-based polyol include "ethylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-". Linear alkylene glycols such as "heptanediol, 1.8-octanediol, 1,9-nonanediol, 1,10-decanediol" and "neopentyl glycol, 3-methyl-1,5-pentanediol, 2, Branched alkylene glycols such as 4-diethyl-1,5-pentanediol, 2-methyl-1,8-octanediol, alicyclic diols such as 1,4-cyclohexanediol, and 1,4-bis (β-). One or more selected from aromatic dihydric alcohols such as hydroxyethoxy) benzene, and the like can be mentioned. Further, an adduct obtained by adding various alkylene oxides to bisphenol A can also be used as a low molecular weight polyol.

On the other hand, examples of the polybasic acid used for the polyester-based polyol include succinic acid, maleic acid, adipic acid, glutaric acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, dodecanecarboxylic acid, phthalic acid, and isophthalic acid. One or more selected from the group consisting of terephthalic acid, hexahydroisophthalic acid and the like can be mentioned.

Examples of the polycarbonate-based polyol include compounds obtained by reacting a polyol with a carbonate compound, such as a polyol and a dialkyl carbonate, or a polyol and a diallyl carbonate.

As the polyol used for the polycarbonate-based polyol, the low molecular weight polyol used for the polyester-based polyol can be used. On the other hand, as the dialkyl carbonate, dimethyl carbonate, diethyl carbonate or the like can be used, and as the diaryl carbonate, diphenyl carbonate or the like can be used.

The number average molecular weight of the polymer polyol preferably used in the present invention is preferably 500 or more and 5000 or less. By setting the number average molecular weight of the polymer polyol to 500 or more, more preferably 1500 or more, it is possible to easily prevent the texture of the artificial leather from becoming hard. Further, by setting the number average molecular weight to 5000 or less, more preferably 4000 or less, it is possible to easily maintain the strength of polyurethane as a binder.

(1-2) Organic diisocyanate The organic diisocyanate used in the present invention includes an aromatic diisocyanate having 6 or more and 20 or less carbon atoms (excluding carbon in the NCO group, the same applies hereinafter) and 2 or more and 18 or less carbon atoms. An aliphatic diisocyanate, an alicyclic diisocyanate having 4 or more and 15 carbon atoms, an aromatic aliphatic diisocyanate having 8 or more and 15 carbon atoms, modified products of these diisocyanates (carbodiimide modified product, urethane modified product, uretdione modified product, etc.). ) And a mixture of two or more of these.

Specific examples of the aromatic diisocyanate having 6 or more and 20 or less carbon atoms include 1,3- and / or 1,4-phenylenediocyanate, 2,4- and / 2,6-tolylene diisocyanate, 2,4. '-And / or 4,4'-diphenylmethane diisocyanate (hereinafter abbreviated as MDI), 4,4'-diisocyanatobiphenyl, 3,3'-dimethyl-4,4'-diisocyanatobiphenyl, 3,3' -Dimethyl-4,4'-diisocyanatodiphenylmethane, 1,5-naphthylene diisocyanate and the like can be mentioned.

Specific examples of the aliphatic diisocyanate having 2 or more and 18 or less carbon atoms include ethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, dodecamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, lysine diisocyanate, 2, 6-Diisocyanatomethyl caproate, bis (2-isocyanatoethyl) carbonate, 2-isocyanatoethyl-2,6-diisocyanatohexaate and the like can be mentioned.

Specific examples of the alicyclic diisocyanate having 4 or more and 15 or less carbon atoms include isophorone diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, cyclohexylene diisocyanate, methylcyclohexylene diisocyanate, and bis (2-isocyanatoethyl). Examples include -4-cyclohexylene-1,2-dicarboxylate, and 2,5- and / or 2,6-norbornane diisocyanate.

Specific examples of the aromatic aliphatic diisocyanate having 8 or more and 15 or less carbon atoms include m- and / or p-xylylene diisocyanate, α, α, α', and α'-tetramethylxylylene diisocyanate. Will be.

Of these, the preferred organic diisocyanate is an alicyclic diisocyanate. Further, a particularly preferable organic diisocyanate is dicyclohexylmethane-4,4'-diisocyanate.

(1-3) Active hydrogen component-containing compound having a hydrophilic group Examples of the active hydrogen component-containing compound having a hydrophilic group preferably used in the present invention include a nonionic group and / or an anionic group and / or a cationic group. Examples thereof include compounds containing active hydrogen. These active hydrogen component-containing compounds can also be used in the form of salts neutralized with a neutralizing agent. By using this active hydrogen component-containing compound having a hydrophilic group, the stability of the aqueous dispersion used in the method for producing artificial leather can be enhanced.

Examples of the compound having a nonionic group and active hydrogen include a compound having two or more active hydrogen components or two or more isocyanate groups and having a polyoxyethylene glycol group having a molecular weight of 250 to 9000 in the side chain. Examples thereof include triols such as trimethylolpropane and trimethylolbutane.

Examples of the compound having an anionic group and active hydrogen include carboxyl group-containing compounds such as 2,2-dimethylolpropionic acid, 2,2-dimethylolbutanoic acid, and 2,2-dimethylolvaleric acid and derivatives thereof, and 1 , 3-Phenylenediamine-4,6-disulfonic acid, 3- (2,3-dihydroxypropoxy) -1-propanesulfonic acid and other sulfonic acid group-containing compounds and derivatives thereof, and neutralizing these compounds. Examples include salts neutralized with the agent.

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

(1-4) Chain Elongator Examples of the chain extender used in the present invention include water, "ethylene glycol, propylene glycol, 1,3-butylene glycol, 1,4-butanediol, 1,6-hexanediol, and diethylene glycol". And low molecular weight diols such as neopentyl glycol, alicyclic diols such as 1,4-bis (hydroxymethyl) cyclohexane, aromatic diols such as 1,4-bis (hydroxyethyl) benzene, and ethylenediamine. "Aromatic diamines such as", alicyclic diamines such as "isophoronediamine", aromatic diamines such as "4,4-diaminodiphenylmethane", aromatic aliphatic diamines such as "xylenidamine", and alkanols such as "ethanolamine". Examples thereof include amines, hydrazines, dihydrazides such as "adipic acid dihydrazide", and mixtures of two or more thereof.

Of these, preferred chain extenders are water, low molecular weight diols, aromatic diamines, more preferably water, ethylene glycol, 1,4-butanediol, 4,4'-diaminodiphenylmethane and two or more of these. Examples include mixtures.

(1-5) Structure of Water-Dispersed Polyurethane Resin As described above, the water-dispersed polyurethane resin preferably used in the present invention is the above-mentioned polymer polyol, organic diisocyanate, and an active hydrogen component-containing compound having a hydrophilic group. It is prepared by reacting with and to form a hydrophilic prepolymer, and then adding and reacting with a chain extender.

(1-6) Composition of Polymer Elastic Precursor The polymer elastic precursor preferably contains a polyether diol and / or a polycarbonate diol as a constituent component from the viewpoint of hydrolysis resistance. Since the polymer elastic precursor contains this polyether diol as a constituent component, the degree of freedom of its ether bond is high, the glass transition temperature is low, and the cohesive force is weak, so that the polymer elastic body has excellent flexibility. Can be. On the other hand, by containing the polycarbonate diol as a constituent component, a polymer elastic body having excellent water resistance, heat resistance, weather resistance, and mechanical characteristics can be obtained due to the high cohesive force of the carbonate group.

The number average molecular weight of the polymer elastic precursor used in the present invention is preferably 20,000 or more and 500,000 or less. The strength of the polymer elastic body can be increased by 20,000 or more, more preferably 30,000 or more. On the other hand, when it is 500,000 or less, more preferably 150,000 or less, the stability of the viscosity can be improved and the workability can be improved.

The number average molecular weight of the polymer elastic precursor can be determined by gel permeation chromatography (GPC), and is measured, for example, under the following conditions.
・ Equipment: "HLC-8220" manufactured by Tosoh Corporation
-Column: "TSKgel α-M" manufactured by Tosoh Corporation
-Solvent: N, N-dimethylformamide (DMF)
・ Temperature: 40 ℃
-Calibration: Polystyrene.

(2) Additives When producing the artificial leather of the present invention, it is important to add a compound having an isocyanate group as described later to the solution for forming the polymer elastic body. In addition, if necessary, colorants (titanium oxide, carbon black, etc.), ultraviolet absorbers (benzophenone-based, benzotriazole-based, etc.) and antioxidants [4,5-butylidene-bis (3-methyl-6-1-). Hindered phenols such as butylphenol); various stabilizers such as triphenylphosphite, organic phosphite such as trichlorethylphosphite], inorganic fillers (calcium carbonate, etc.), thickeners (urethane-modified polyethers and acrylics) Polymers, etc.) can be contained in the solution for forming the polymer elastic body. The compound having an isocyanate group will be described in detail below.

(2-1) Compound having an isocyanate group The artificial leather of the present invention contains the above-mentioned polyurethane having a hydrophilic group and a compound having an isocyanate group in the polymer elastic body. By doing so, the compound having an isocyanate group can selectively adsorb the moisture in the air and suppress the deterioration of the polymer elastic body which deteriorates over time in actual use, and is excellent in long-term moisture resistance. It can be artificial leather.

In particular, in the present invention, the compound having an isocyanate group is preferably a compound having a plurality of isocyanate groups, and more preferably a triisocyanate compound. When a plurality of polyisocyanate groups are provided, the effect of suppressing the deterioration of the polymer elastic body, which will be described later, can be exhibited even with a small amount of addition, and the deterioration of the physical properties of the polymer elastic body can be further suppressed.

As the triisocyanate compound, for example, lysine triisocyanate, 1,3,5-tris (isocyanatohexamethylene) isocyanurate and the like can be used.

(3) Polymer elastic material The polymer elastic material constituting the artificial leather of the present invention preferably contains a polyether diol and / or a polycarbonate diol as a constituent component.

Since the polymer elastic body according to the present invention contains this polyether diol as a constituent component, the degree of freedom of its ether bond is high, the glass transition temperature is low, and the cohesive force is weak, so that the polymer is excellent in flexibility. It can be an elastic body. On the other hand, by containing the polycarbonate diol as a constituent component, it is possible to obtain a polymer elastic body having excellent durability such as water resistance, heat resistance and weather resistance due to the high cohesive force of the carbonate group.

The polymer elastic body having a hydrophilic group used in the present invention appropriately grips the fibers in the artificial leather, and preferably the inside of the fibrous base material from the viewpoint of having fluff on at least one side of the artificial leather. It is a preferable embodiment that it is present in.

[Artificial leather]
In the artificial leather of the present invention, the polymer elastic body in the artificial leather contains a polyurethane having a hydrophilic group and a compound having an isocyanate group, and the ratio of the isocyanate group to the urethane bond in the polyurethane is 0. It is 01% or more and 1% or less. When the ratio of the isocyanate group to the urethane bond in the polyurethane is 0.01% or more, preferably 0.05% or more, more preferably 0.1% or more, the compound having an isocyanate group is artificial. It is sufficiently and uniformly present in the leather, and it is possible to suppress the deterioration of the polymer elastic body which deteriorates over time in actual use. On the other hand, when the ratio of the isocyanate group to the urethane bond in the polyurethane is 1% or less, preferably 0.8% or less, the compound having an isocyanate group has good compatibility with the polymer elastic precursor. It exists and can suppress the inhibition of solidification of the polymer elastic body and can also suppress the deterioration of the physical properties of the polymer elastic body.

In the present invention, the ratio of the isocyanate group to the urethane bond in the polyurethane shall be a value measured and calculated by the following method. That is, first, only the ultrafine fibers are eluted from the artificial leather, and the polymer elastic body is extracted. Subsequently, the obtained polymer elastic body is pressed to form a film-like sheet having a thickness of 1 mm. Then, IR measurement is performed on this film-like sheet by the ATR method. From the obtained spectrum, the absorbance of the peak derived from the expansion and contraction vibration of the isocyanate group observed near 2260 cm ^-1 is derived from the isocyanate group, and the peak derived from the urethane bond observed near 1720 cm ^-1 is derived from the urethane bond. The value (%) obtained by multiplying the absorbance derived from the isocyanate group by the absorbance derived from the urethane bond (without unit) by 100 and then rounding to the second place after the decimal point is the polyurethane. It is the ratio of the above-mentioned isocyanate groups to the urethane bond in.

Further, in the artificial leather of the present invention, the ratio of the artificial leather to be dissolved in N, N-dimethylformamide at 25 ° C. (hereinafter, may be simply abbreviated as the dissolution ratio) is preferably 20% by mass or less. When the dissolution ratio is 20% by mass or less, more preferably 15% by mass or less, still more preferably 12% by mass or less, the solvent resistance in actual use is high and excellent durability is obtained.

For this dissolution ratio, the values measured and calculated as follows shall be adopted.
(1) Three 10 cm square samples are cut from artificial leather, and this mass (mg) is measured to the second decimal place. This mass is referred to as "mass before immersion (mg)".
(2) The artificial leather whose mass was measured in (1) is immersed in N, N-dimethylformamide at 25 ° C. and left at an atmospheric temperature of 25 ° C. for 24 hours.
(3) The sample of (2) is washed 3 times with N, N-dimethylformamide at 25 ° C., dried at 80 ° C. for 60 minutes, and then this mass (mg) is measured to the second decimal place. .. This mass is referred to as "mass after immersion (mg)".
(4) Round off the value obtained by the following formula to the second decimal place to calculate the dissolution ratio (mass%) = (mass before immersion (mg) -mass after immersion (mg)) / Mass before immersion (mg) x 100
(5) The value obtained by rounding off the arithmetic mean value (mass%) of the above three samples to the second decimal place is defined as the dissolution ratio of the artificial leather.

In order to keep the dissolution ratio within the above range, the polymer elastic body may be reacted with a compound having a functional group that reacts with the hydrophilic group of the polymer elastic body, such as a carbodiimide group or an isocyanate group, to increase the number of 3 For example, increasing the number average molecular weight of the polymer elastic body by imparting a dimensional network structure.

The artificial leather of the present invention preferably has a bending length of 40 mm or more and 150 mm or less in the vertical direction defined by the "41.5 ° cantilever method" described in JIS L1913: 2010 "General non-woven fabric test method". By setting the bending length within the above range, it is possible to have appropriate flexibility and resilience. The bending length is preferably 50 mm or more, more preferably 55 mm or more from the viewpoint of obtaining a repulsive artificial leather, and preferably 120 mm or less from the viewpoint of obtaining a flexible artificial leather. It is preferably 110 mm or less.

The vertical direction in the artificial leather of the present invention means the direction in which the artificial leather is brushed. As a method of searching for the direction in which the brushing treatment is performed, it can be appropriately adopted depending on the constituent components of the artificial leather, such as visual confirmation when tracing with a finger and SEM photography. That is, when traced with a finger, the direction in which the fluffy fibers can be laid down or erected is the vertical direction. In addition, by taking an SEM image of the surface of the artificial leather traced with a finger, the direction in which the sleeping nap fibers are most oriented becomes the vertical direction. On the other hand, the horizontal direction in the artificial leather of the present invention is the direction perpendicular to the vertical direction, which is called the horizontal direction.

The artificial leather of the present invention is JIS L1096: 2005 "Fabric test method for woven fabrics and knitted fabrics" after an accelerated deterioration test (jungle test, 70 ° C., left in a space with a relative humidity of 95% for 2 weeks) in a high temperature and high humidity environment. The wear loss in the Martindale wear test 50,000 times specified in the above is preferably 30 mg or less. By setting the wear weight loss after the accelerated deterioration test (jungle test) within the above range, deterioration of the polymer elastic body can be suppressed even after long-term use, and the appearance of the artificial leather can be maintained. The wear weight loss is preferably 25 mg or less, more preferably 20 mg or less, from the viewpoint of suppressing deterioration of the appearance of the artificial leather.

[Manufacturing method of artificial leather]
Next, a method for producing the artificial leather of the present invention will be described.

<Fiber substrate forming process>
In the present invention, as a means for obtaining ultrafine fibers, it is preferable to use ultrafine fiber-expressing fibers. By entwining the ultrafine fiber-expressing type fibers in advance to form a nonwoven fabric and then performing ultrafineness of the fibers, a nonwoven fabric in which the ultrafine fiber bundles are entangled can be obtained.

As the ultrafine fiber-expressing fiber, a thermoplastic resin having two components (two or three components when the island fiber is a core-sheath composite fiber) having different solvent solubility is used as a sea component and an island component, and the above sea component is used as a solvent. By using a sea-island type composite fiber in which the island component is made into ultrafine fibers by dissolving and removing the sea component, an appropriate void is provided between the island components, that is, between the ultrafine fibers inside the fiber bundle when the sea component is removed. Therefore, it is preferable from the viewpoint of the texture and surface quality of the artificial leather substrate.

As the sea-island type composite fiber, a polymer mutual arrangement in which two components of the sea component and the island component (three components when the island fiber is a core-sheath composite fiber) are mutually arranged and spun using a sea-island type composite base is used. The method used is preferable from the viewpoint of obtaining ultrafine fibers having a uniform single fiber diameter.

As the sea component of the sea-island type composite fiber, polyethylene, polypropylene, polystyrene, a copolymerized polyester obtained by copolymerizing sodium sulfoisophthalic acid, polyethylene glycol, or the like, polylactic acid, or the like can be used. From the viewpoint of the above, polystyrene and copolymerized polyester are preferably used.

It is preferable that the sea component is dissolved and removed after the polymer elastic precursor is applied. As will be described later.

The mass ratio of the sea component to the island component in the sea-island type composite fiber used in the present invention is preferably in the range of sea component: island component = 10: 90 to 80:20. When the mass ratio of the sea component is 10% by mass or more, the island component is likely to be sufficiently refined. Further, when the mass ratio of the sea component is 80% by mass or less, the ratio of the eluted component is small, so that the productivity is improved. The mass ratio of the sea component and the island component is more preferably in the range of sea component: island component = 20:80 to 70:30.

Further, the fiber entanglement preferably takes the form of a non-woven fabric, and as described above, either a short-fiber non-woven fabric or a long-fiber non-woven fabric can be used. It is preferable because the amount of the material is larger than that of the long fiber non-woven fabric and a high degree of fineness can be obtained on the surface of the artificial leather when raised.

When a short fiber non-woven fabric is used as the fiber entanglement, the obtained ultrafine fiber-expressing fiber is preferably crimped and cut to a predetermined length to obtain raw cotton. A known method can be used for the crimping process and the cutting process.

Next, the obtained raw cotton is used as a fiber web with a cloth wrapper or the like and entangled to obtain a staple fiber non-woven fabric. As a method of entwining the fiber webs to obtain a short fiber non-woven fabric, a needle punching process, a water jet punching process, or the like can be used.

Further, the obtained short fiber non-woven fabric and the woven fabric are laminated and entangled and integrated. To entangle and integrate the short fiber non-woven fabric and the fabric, either stack the fabric on one or both sides of the short fiber non-woven fabric, or sandwich the fabric between multiple short fiber non-woven fabric webs, and then perform needle punching or water jet. The short fiber non-woven fabric and the fibers of the woven fabric can be entangled with each other by punching or the like.

The apparent density of the short fiber non-woven fabric made of composite fibers (ultrafine fiber-expressing fibers) after the needle punching treatment or the water jet punching treatment is preferably 0.15 g / cm ³ or more and 0.45 g / cm ³ or less. By setting the apparent density to preferably 0.15 g / cm ³ or more, sufficient morphological stability and dimensional stability can be obtained for the fibrous substrate. On the other hand, by setting the apparent density to preferably 0.45 g / cm ³ or less, it is possible to maintain a sufficient space for imparting the polymer elastic precursor.

From the viewpoint of densification, the nonwoven fabric thus obtained is preferably shrunk by dry heat, wet heat, or both to further increase the density. Further, the nonwoven fabric can be compressed in the thickness direction by calendar processing or the like.

When a sea-island type composite fiber is used, the desealing treatment for removing the sea component of the fiber is performed before the application of the aqueous dispersion containing the polymer elastic precursor having a hydrophilic group to the fibrous substrate or before the application. / And can be done after grant. If the desealing treatment is performed before the water dispersion is applied, the polymer elastic body tends to be in direct contact with the ultrafine fibers, and the ultrafine fibers can be strongly gripped, so that the wear resistance of the artificial leather tends to be good.

When a sea-island type composite fiber is used as the ultra-fine fiber-expressing type fiber, the fiber ultrafine treatment (desealing treatment) can be performed, for example, by immersing the sea-island type composite fiber in a solvent and squeezing the liquid. As the solvent for dissolving the sea component, an alkaline aqueous solution such as sodium hydroxide or hot water can be used.

In the process of expressing ultrafine fibers, devices such as a continuous dyeing machine, a vibro washer type sea removal machine, a liquid flow dyeing machine, a Wins dyeing machine and a Jigger dyeing machine can be used.

On the other hand, by applying the aqueous dispersion after adding an inhibitor such as a cellulose derivative or polyvinyl alcohol (hereinafter, may be abbreviated as PVA) to the ultrafine fiber before the addition of the aqueous dispersion, the ultrafine fiber can be obtained. The adhesion of the polymer elastic body can be lowered, and a more flexible texture can be achieved.

The above-mentioned inhibitor application can be performed either before or after the desealing treatment of the fibers of the sea island structure. By adding an inhibitor before the desealing treatment, the morphological holding power of the fibrous base material can be enhanced even when the basis weight of the fibers is lowered and the tensile strength of the sheet is lowered. Therefore, in addition to being able to stably process thin sheets, it is possible to increase the thickness retention rate of the fibrous base material in the desealing treatment step, and it is possible to suppress the increase in density of the fibrous base material. On the other hand, since it is possible to realize a high density of the fibrous base material by applying the inhibitor after the desealing treatment, it is a preferable embodiment to appropriately adjust the fiber base material according to the purpose.

As the inhibitor, PVA is preferably used because it has a high reinforcing effect on the fibrous base material and is difficult to elute in water. Among PVAs, from the viewpoint that the inhibitor can be less likely to elute when an aqueous dispersion containing a polymer elastic precursor having a hydrophilic group is applied, and the adhesion between the ultrafine fibers and the polymer elastic can be inhibited. It is a more preferable embodiment to apply a high degree of saponification PVA which is sparingly soluble in water.

The high saponification degree PVA preferably has a saponification degree of 95% or more and 100% or less, and more preferably 98% or more and 100% or less. By setting the saponification degree to 95% or more, it is possible to suppress elution at the time of applying the polymer elastic precursor dispersion liquid having a hydrophilic group.

The degree of polymerization of PVA is preferably 500 or more and 3500 or less, and more preferably 500 or more and 2000 or less. By setting the degree of polymerization of PVA to 500 or more, it is possible to suppress the elution of PVA having a high degree of saponification when the polymer elastic precursor precursor dispersion liquid is applied. Further, by setting the degree of polymerization of PVA to 3500 or less, the viscosity of the high saponification PVA liquid does not become too high, and the high saponification PVA can be stably imparted to the fibrous substrate.

The amount of PVA applied to the fibrous base material is 0.1% by mass or more and 50% by mass or less, preferably 1% by mass or more and 45% by mass or less, based on the fiber mass of the fibrous base material. By setting the amount of PVA applied to 0.1% by mass or more, artificial leather with good flexibility and texture can be obtained, and by setting the amount of PVA applied to 50% by mass or less, workability is good and abrasion resistance is good. Artificial leather with better physical characteristics such as sex can be obtained.

<Polymer elastic body imparting process>
In the present invention, when a nonwoven fabric is used as the fibrous substrate, the polymer elastic precursor can be applied to either the nonwoven fabric made of composite fibers or the nonwoven fabric made into ultrafine fibers.

For coagulation after imparting the polymer elastic body, a coagulation method usually used in the art such as a dry heat coagulation method or a liquid coagulation method can be applied. When the dry heat coagulation method is used, the aqueous dispersion is applied to the fibrous base material, then heat-treated at a temperature of 120 ° C. or higher and 180 ° C. or lower, and then dry heat coagulated to form a polymer elastic precursor on the fibrous base material. It is preferable to give the body. As the in-liquid coagulation, an acid coagulation method in which a coagulation treatment is performed with a coagulation solvent having a pH of 1 or more and 3 or less, a hot water coagulation method in which a coagulation treatment is performed with hot water at 80 ° C. or more and 100 ° C. or less can be used. ..

The concentration of the polymer elastic precursor in the aqueous dispersion (content of the polymer elastic precursor in 100% by mass of the aqueous dispersion) is 10% by mass or more and 50 from the viewpoint of storage stability of the aqueous dispersion. It is preferably 5% by mass or less, more preferably 15% by mass or more and 40% by mass or less.

The aqueous dispersion used in the present invention may contain a water-soluble organic solvent in an amount of 40% by mass or less in 100% by mass of the aqueous dispersion in order to improve storage stability and film-forming property. From the viewpoint of maintenance and the like, the content of the organic solvent is preferably 1% by mass or less.

In the method for producing artificial leather of the present invention, an inorganic salt can be contained in the aqueous dispersion. By containing an inorganic salt, it is possible to impart heat-sensitive coagulation to the aqueous dispersion. In the present invention, the heat-sensitive coagulation property refers to the property that when the water dispersion is heated, the fluidity of the water dispersion decreases and solidifies when a certain temperature (heat-sensitive coagulation temperature) is reached.

When the polymer elastic precursor does not have heat-sensitive coagulation property, a migration phenomenon occurs in which the polymer elastic precursor is transferred to the sheet surface as the water evaporates. Further, since the solidification proceeds in a state where the polymer elastic precursor is unevenly distributed around the fiber as the water evaporates, the polymer elastic material covers the fiber and the movement is strongly restrained. As a result, the texture of artificial leather is significantly hardened.

The heat-sensitive coagulation temperature of the aqueous dispersion is preferably 55 ° C. or higher and 80 ° C. or lower. It is more preferable that the heat-sensitive temperature is 60 ° C. or higher because the stability of the aqueous dispersion during storage is improved and the adhesion of the polymer elastic precursor to the machine during operation can be suppressed. It is possible to suppress the migration phenomenon of the polymer elastic precursor to the surface layer of the fibrous substrate, and further, the solidification of the polymer elastic precursor progresses before the water evaporates from the fibrous substrate, so that the solvent is used. It is possible to form a structure similar to that obtained by wet-solidifying a polymer elastic body, that is, a structure in which the polymer elastic body strongly does not restrain fibers, and it is possible to achieve good flexibility and a feeling of repulsion. Therefore, it is more preferable that the heat-sensitive solidification temperature is 70 ° C. or lower.

In the present invention, it is preferable to use a monovalent cation-containing inorganic salt as the inorganic salt used as the heat-sensitive coagulant. The monovalent cation-containing inorganic salt is preferably sodium chloride and / or sodium sulfate. The monovalent cation-containing inorganic salt having a small ionic valence has a small effect on the stability of the aqueous dispersion, and the heat-sensitive coagulation temperature can be adjusted while ensuring the stability of the aqueous dispersion by adjusting the addition amount. It can be strictly controlled.

Further, in the present invention, the content of the monovalent cation-containing inorganic salt in the aqueous dispersion is preferably 10 parts by mass or more and 50 parts by mass or less with respect to 100 parts by mass of the polymer elastic precursor. By setting the content to 10 parts by mass or more, a large amount of ions present in the aqueous dispersion act uniformly on the polymer elastic precursor particles, so that solidification is completed promptly at a specific heat-sensitive coagulation temperature. Can be made to. As a result, a more remarkable effect can be obtained in advancing the coagulation of the polymer elastic precursor precursor in a state where a large amount of water is contained in the fibrous base material as described above. As a result, it is possible to form a structure very similar to that obtained by wet-coagulating a solvent-based polymer elastic body, and to achieve good flexibility and a feeling of repulsion. Furthermore, by setting the addition amount as described above, the inorganic salt acts as an inhibitor in the fusion of the polymer elastic precursor particles, and the curing of the polymer elastic due to the formation of a continuous film can be suppressed. On the other hand, when the content is 50% by mass or less, an appropriate continuous coating structure of the polymer elastic body can be left, and deterioration of physical properties can be suppressed. In addition, the stability of the aqueous dispersion can be maintained.

In the present invention, it is preferable that the aqueous dispersion contains a compound having an isocyanate group or an isocyanate group derivative. By using a compound having an isocyanate group or an isocyanate group derivative, a three-dimensional network structure can be introduced into the polymer elastic body, and physical properties such as wear resistance can be improved.

The compound having an isocyanate group derivative as used herein refers to a compound such as a blocked isocyanate compound that produces an "compound having an isocyanate group" by a thermal reaction or a chemical reaction.

The concentration of the compound having an isocyanate group or an isocyanate group derivative in the aqueous dispersion is increased by 1 part by mass or more, more preferably 2 parts by mass or more with respect to 100 parts by mass of the polymer elastic precursor. A larger number of three-dimensional network structures can be introduced into the molecular elastic body, and artificial leather having excellent wear resistance and the like can be obtained. Further, the polymer elastic body is formed by setting the concentration of the compound having an isocyanate group or the isocyanate group derivative to 10 parts by mass or less, more preferably 7 parts by mass or less, with respect to 100 parts by mass of the polymer elastic precursor. When this is done, it is possible to prevent the compound having an excess isocyanate group or an isocyanate group derivative from inhibiting the coagulation of the polymer elastic precursor, and at the same time, suppress the excess isocyanate group or the isocyanate group derivative in the polymer elastic body. It is easy to prevent the compound having the above from remaining and to suppress the deterioration of physical properties such as abrasion resistance.

Thickeners can also be used in the present invention. The "thickener" can have the viscosity of the aqueous dispersion within the above range by being contained in the aqueous dispersion, and such thickeners are nonionic or anionic. , Cationic and amphoteric thickeners can be applied.

The type of thickener as described above can be selected from an association type thickener and a water-soluble polymer type thickener.

As the association type thickener, urethane-modified compounds, acrylic-modified compounds, copolymer compounds thereof and the like can be applied.

Examples of the water-soluble polymer-type thickener include natural polymer compounds, semi-synthetic polymer compounds, and synthetic polymer compounds.

Natural polymer compounds include nonionic compounds such as tamarind gum, guar gum, roast bean gum, tragant gum, starch, dextrin, gelatin, agarose, casein and curdran, and xanthan gum, carrageenan, arabic gum, pectin, collagen and chondroitin. Examples thereof include anionic ones such as sodium sulfate, sodium hyaluronate, carboxymethyl starch and phosphate starch, and cationic ones such as cationic starch and chitosan.

Examples of the semi-synthetic polymer include nonionic polymers such as methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, ethyl hydroxyethyl cellulose, methyl hydroxypropyl cellulose, soluble starch and methyl starch, and anionic ones such as carboxymethyl cellulose, carboxymethyl starch and arginate. Compounds include.

Examples of the synthetic polymer compound include nonionic compounds such as polyvinyl alcohol, polyacrylamide, polyvinylpyrrolidone, polymethylvinyl ether, polyethylene glycol and polyisopropylacrylamide, and anions such as carboxyvinyl polymer, sodium polyacrylate and sodium polystyrene sulfonate. Examples thereof include sexual compounds and cationic compounds such as dimethylaminoethyl (meth) acrylate quaternary salt, dimethyldialyl ammonium chloride, polyamidine, polyvinyl imidazoline, and polyethyleneimine.

In the present invention, it is preferable to apply the polymer elastic precursor to the fibrous substrate and solidify it, and then carry out the cure treatment of the polymer elastic. The heating temperature in the curing treatment by drying is 120 ° C. or higher and 180 ° C. or lower. By setting the heating temperature to 120 ° C. or higher, more preferably 140 ° C. or higher, still more preferably 145 ° C. or higher, the effect of the cure treatment can be enhanced and the physical properties such as durability and wear resistance can be further enhanced. .. On the other hand, by setting the heating temperature to 180 ° C. or lower, more preferably 175 ° C. or lower, still more preferably 170 ° C. or lower, thermal deterioration of the polymer elastic body can be suppressed.

When the curing treatment is carried out after the polymer elastic precursor is applied to the fibrous substrate and solidified, the heating time in the curing treatment is preferably 1 minute or more and 60 minutes or less. By heating for 1 minute or more, more preferably 5 minutes or more, it becomes possible to sufficiently form a three-dimensional network structure. By setting the heating time to 60 minutes or less, preferably 30 minutes or less, deterioration of the polymer elastic body due to overheating can be prevented.

Further, in the method for producing artificial leather of the present invention, it is preferable to cool the sheet with an aqueous solution of 10 ° C. or higher and 40 ° C. or lower immediately after heating in the curing treatment. The type of the aqueous solution is not particularly limited, but an acidic solution or a basic solution may deteriorate the polymer elastic body. Therefore, a neutral solution is preferable, and water is preferably used because it is easy to handle.

When the sheet is cooled with an aqueous solution of 10 ° C. or higher and 40 ° C. or lower, the cooling time is preferably 10 minutes or less, preferably 5 minutes or less, from the viewpoint of production efficiency.

<Finishing process>
The method for producing artificial leather of the present invention preferably includes a dyeing step of dyeing artificial leather. As this dyeing treatment, various methods usually used in the art can be adopted, for example, a liquid flow dyeing treatment using a jigger dyeing machine or a liquid flow dyeing machine, a thermosol dyeing treatment using a continuous dyeing machine, and the like. Dyeing treatment, roller printing, screen printing, inkjet printing, sublimation printing, vacuum sublimation printing, or the like can be used. Above all, it is preferable to use a liquid flow dyeing machine because it is possible to soften the unbrushed artificial leather or the artificial leather by giving a kneading effect at the same time as dyeing the unbrushed artificial leather or the artificial leather. Further, if necessary, various resin finishing processes can be applied after dyeing.

The dye used in the present invention may be selected according to the type of fiber constituting the fibrous base material and is not particularly limited. For example, if it is a polyester fiber, a disperse dye can be used, and the polyamide fiber can be used. If so, acid dyes and gold-containing dyes can be used, and combinations thereof can be used. When dyed with a disperse dye, reduction washing may be performed after dyeing.

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. In addition, a finishing agent treatment using, for example, a softener such as silicone, an antistatic agent, a water repellent agent, a flame retardant, a light resistant agent, an antibacterial agent, or the like can be applied in the same bath or after dyeing.

In the present invention, it is also a preferable aspect to cut in half in the thickness direction from the viewpoint of production efficiency regardless of before and after the dyeing step.

It is also preferable that the method for producing artificial leather of the present invention includes a raising step before and after the dyeing step. The method for forming fluff is not particularly limited, and various methods usually used in the art such as buffing with sandpaper or the like can be used. If the fluff length is too short, it is difficult to obtain an elegant appearance, and if it is too long, pilling tends to occur. Therefore, the fluff length is preferably 0.2 mm or more and 1.0 mm or less.

When the raising treatment is applied, a lubricant such as a silicone emulsion can be applied to the surface of the artificial leather before the raising treatment. Further, by applying an antistatic agent before the raising treatment, the grinding powder generated from the artificial leather by grinding is less likely to be deposited on the sandpaper. In this way, artificial leather is formed.

Further, in one aspect of the present invention, the surface thereof can be designed as needed. For example, post-processing such as perforation and other drilling, embossing, laser processing, pinsonic processing, and printing can be performed.

Next, the artificial leather of the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.

[Evaluation method]
(1) Accelerated deterioration test of artificial leather As an accelerated deterioration test, an accelerated deterioration test in which 10 cm square artificial leather is allowed to stand in a space at 70 ° C and 95% relative humidity for 2 weeks using "PR-2J" manufactured by Espec Co., Ltd. (Jungle test) was performed.

(2) Wear evaluation of artificial leather A wear evaluation was performed based on JIS L1096: 2010. As a Martindale wear tester, James H. Heal & Co. The company's "Model 406" was used, and the company's "ABRASTIVE CLOTH SM25" was used as the standard friction cloth. A load of 12 kPa was applied to the artificial leather after the above-mentioned accelerated deterioration test, and the number of times of wear was 50,000 times. Using the mass of artificial leather before and after wear, the wear loss was calculated by the following formula.

Wear loss (mg) = mass before wear (mg) -mass after wear (mg)
For the wear reduction, the value rounded off to the first decimal place was taken as the wear reduction.

(3) Ratio of isocyanate groups to urethane bonds in polyurethane The ratio of isocyanate groups to urethane bonds in polyurethane was measured and calculated by the above method. The measuring device and measuring conditions when IR measurement is performed by the ATR method are as follows.
Equipment: TENSOR II (manufactured by Bruker)
Light source: Glover detector: Deuterated L-alanine-doped triglycine sulfate purge: Nitrogen gas resolution: 4 cm ^-1
Cumulative number: 256 times ATR crystal: Ge
Incident angle: 45 °
Polarization: None.

(4) Ratio of artificial leather to dissolve in N, N-dimethylformamide at 25 ° C (dissolution ratio)
According to the above method, the dissolution ratio of artificial leather was measured and calculated.

[Manufacturing method of nonwoven fabric A for fibrous substrate]
Using 8 mol% copolymerized polyester of SSIA (sodium 5-sulfoisophthalate) as the sea component and polyethylene terephthalate as the island component, the number of islands is 43% by mass of the sea component and 57% by mass of the island component. A sea-island type composite fiber having 16 islands / 1 filament and an average single fiber diameter of 20 μm was obtained. The obtained sea-island type composite fiber is cut into a fiber length of 51 mm to form a staple, a fiber web is formed through a curd and a cloth wrapper, and a non-woven fabric having a basis weight of 550 g / m ² and a thickness of 3.0 mm is formed by needle punching. Manufactured. The nonwoven fabric thus obtained was immersed in hot 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 nonwoven fabric A for a fibrous substrate.

[Method for producing polymer elastic precursor A]
Polyhexamethylene carbonate having a number average molecular weight (Mn) of 2000 as a high molecular weight polyol, hydrogenated MDI as an organic diisocyanate, a diol compound having polyethylene glycol in the side chain as an active hydrogen component-containing compound having a hydrophilic group, and 2,2. -A prepolymer was prepared in an acetone solvent using dimethylol propionic acid. Ethylene glycol, ethylenediamine and water were added as chain extenders and stirred. Acetone was removed by reducing the pressure to obtain an aqueous dispersion of the polymer elastic precursor A.

[Example 1]
(Fibrous substrate forming process)
Nonwoven fabric A for fibrous base material is impregnated with a 10% by mass aqueous solution of PVA (“NM-14” manufactured by Nippon Synthetic Chemical Co., Ltd.) having a saponification degree of 99% and a polymerization degree of 1400, and 10 at a temperature of 140 ° C. After heating and drying for 1 minute, a PVA-imparting sheet in which the amount of PVA adhered to the fiber mass of the non-woven fabric for a fibrous substrate was 30% by mass was obtained.

The obtained PVA-imparting sheet was immersed in a sodium hydroxide aqueous solution having a concentration of 8 g / L heated to a temperature of 95 ° C. and treated for 30 minutes to remove the sea component of the sea-island type composite fiber. PVA-imparted ultrafine fiber non-woven fabric) was obtained.

(Polymer elastic body imparting process)
With respect to 100 parts by mass of the solid content of the polymer elastic precursor A, the solid content of the blocked isocyanate compound A (“IMPRAFIX2794” manufactured by Covetro) as a compound having an isocyanate group derivative is increased by 3 parts by mass, based on acrylic. Add the viscous agent so that the solid content is 3 parts by mass, adjust the solid content to 19% by mass with water, and add 2000 mPa · s viscosity water containing the polymer elastic precursor. A dispersion was obtained. Immediately after the PVA-imparted ultrafine fiber non-woven fabric was immersed in the aqueous dispersion and then dried with hot air at a temperature of 160 ° C. for 15 minutes, it was immersed in water at 20 ° C. for 5 minutes with respect to 100 parts by mass of the ultrafine fibers. An ultrafine fibrous nonwoven fabric having a thickness of 2.00 mm and having 50 parts by mass of a polymer elastic body was obtained.

The obtained ultrafine fiber non-woven fabric imparted with a polymer elastic body was immersed in water heated to 95 ° C. and treated for 10 minutes, and the imparted PVA was removed to obtain artificial leather.

(Finishing process)
The obtained artificial leather was cut in half vertically in the thickness direction, and the opposite side of the half-cut surface was ground with sandpaper count 180 endless sandpaper to obtain an artificial leather having fluff with a thickness of 0.75 mm. ..

The obtained artificial leather having fluff was dyed black with a disperse dye under a temperature condition of 120 ° C. using a liquid flow dyeing machine. Then, it was dried with a drier to obtain an artificial leather having an average single fiber diameter of 3.8 μm. The wear weight loss of the obtained artificial leather after the accelerated deterioration test (jungle test) was 15 mg, and it had excellent durability. The ratio of isocyanate groups to urethane bonds in polyurethane was 0.6%, and the ratio (dissolution ratio) of artificial leather to dissolve in N, N-dimethylformamide at 25 ° C. was 12% by mass. The results are shown in Table 1.

[Example 2]
The same procedure as in Example 1 was carried out except that the solid content of the blocked isocyanate compound A (“IMPRAFIX2794” manufactured by Covestro) was changed from 3 parts by mass to 5 parts by mass.

The wear weight loss of the obtained artificial leather after the accelerated deterioration test (jungle test) was 18 mg, and it had excellent durability. The ratio of isocyanate groups to urethane bonds in polyurethane was 0.9%, and the ratio (dissolution ratio) of artificial leather to dissolve in N, N-dimethylformamide at 25 ° C. was 8% by mass. The results are shown in Table 1.

[Example 3]
Example 1 except that the immersion time in water at 20 ° C. was changed from 5 minutes to 3 minutes immediately after the PVA-imparted ultrafine fibrous nonwoven fabric was immersed in an aqueous dispersion and then dried with hot air at a temperature of 160 ° C. for 15 minutes. It was carried out in the same manner as.

The wear weight loss of the obtained artificial leather after the accelerated deterioration test (jungle test) was 16 mg, and it had excellent durability. The ratio of isocyanate groups to urethane bonds in polyurethane was 0.2%, and the ratio (dissolution ratio) of artificial leather to dissolve in N, N-dimethylformamide at 25 ° C. was 10% by mass. The results are shown in Table 1.

[Example 4]
The PVA-imparted ultrafine fibrous nonwoven fabric was immersed in an aqueous dispersion, and then the drying time with hot air at a temperature of 160 ° C. was changed from 15 minutes to 30 minutes, and the same procedure as in Example 1 was carried out.

The wear weight loss of the obtained artificial leather after the accelerated deterioration test (jungle test) was 23 mg, and it had excellent durability. The ratio of isocyanate groups to urethane bonds in polyurethane was 0.05% by mass, and the ratio (dissolution ratio) of artificial leather to dissolve in N, N-dimethylformamide at 25 ° C. was 6% by mass. The results are shown in Table 1.

[Example 5]
The same procedure as in Example 1 was carried out except that the blocked isocyanate compound A was changed to the blocked isocyanate compound B (“Elastron” (registered trademark) BN-77 ”manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) as the compound having an isocyanate group derivative. did.

The wear weight loss of the obtained artificial leather after the accelerated deterioration test (jungle test) was 25 mg, and it had excellent durability. The ratio of isocyanate groups to urethane bonds in polyurethane was 0.1% by mass, and the ratio (dissolution ratio) of artificial leather to dissolve in N, N-dimethylformamide at 25 ° C. was 18% by mass. The results are shown in Table 1.

[Comparative Example 1]
The PVA-imparted ultrafine fiber non-woven fabric was immersed in an aqueous dispersion, then dried with hot air at a temperature of 160 ° C. for 15 minutes, and immediately after being immersed in water at 20 ° C. for 5 minutes, it was not immersed in water (0). It was carried out in the same manner as in Example 1 except that the immersion was changed to a minute.

The wear weight loss of the obtained artificial leather after the accelerated deterioration test (jungle test) was 35 mg, and the durability was inferior. In addition, no compound having an isocyanate group was observed in the polymer elastic body (the ratio of the isocyanate group to the urethane bond in polyurethane was 0.0%), and it was dissolved in N, N-dimethylformamide at 25 ° C. of artificial leather. The ratio (dissolution ratio) was 5% by mass. The results are shown in Table 2.

[Comparative Example 2]
The same procedure as in Example 1 was carried out except that the solid content of the blocked isocyanate compound A (“IMPRAFIX2794” manufactured by Covestro) was changed from 3 parts by mass to 10 parts by mass.

The wear weight loss of the obtained artificial leather after the accelerated deterioration test (jungle test) was 40 mg, and the durability was inferior. The ratio of isocyanate groups to urethane bonds in polyurethane was 3.0%, and the ratio (dissolution ratio) of artificial leather to dissolve in N, N-dimethylformamide at 25 ° C. was 5% by mass. The results are shown in Table 2.

[Comparative Example 3]
The procedure was carried out in the same manner as in Example 1 except that the blocked isocyanate compound A was not added.

The wear weight loss of the obtained artificial leather after the accelerated deterioration test (jungle test) was 50 mg, and the durability was inferior. In addition, no compound having an isocyanate group was observed (the ratio of the above-mentioned isocyanate group to the urethane bond in polyurethane is 0.0%), and the ratio of dissolution in N, N-dimethylformamide at 25 ° C. of artificial leather (dissolution ratio). ) Was 30% by mass. The results are shown in Table 2.

The artificial leather obtained by the present invention has a very graceful appearance as furniture, chairs and wall materials, and interior materials such as seats, ceilings and interiors in vehicle interiors such as automobiles, trains and aircraft, shirts and jackets. , Casual shoes, sports shoes, men's shoes, women's shoes and other shoe uppers, trims, bags, belts, wallets, etc., and clothing materials used for some of them, wiping cloth, polishing cloth, CD curtains, etc. It can be suitably used as an industrial material.

Claims (4)

An artificial leather containing a fibrous base material made of ultrafine fibers having an average single fiber diameter of 0.1 μm or more and 10 μm or less and a polymer elastic body, wherein the polymer elastic body is polyurethane having a hydrophilic group. An artificial leather containing a compound having an isocyanate group and having the ratio of the isocyanate group to the urethane bond in the polyurethane of 0.01% or more and 1% or less. The artificial leather according to claim 1, wherein the dissolution ratio to N, N-dimethylformamide at 25 ° C. is 20% by mass or less. The artificial leather according to claim 1 or 2, wherein the polyurethane contains a polyether diol and / or a polycarbonate diol as a constituent. The artificial leather according to any one of claims 1 to 3, wherein the compound having an isocyanate group is a triisocyanate compound.