JP2003328276A - Artificial leather comprising ultrafine filament nonwoven fabric and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To treat a filament nonwoven fabric with water without a chemical to stably provide an artificial leather comprising the ultrafine filament nonwoven fabric. <P>SOLUTION: This artificial leather is characterized by impregnating a filament nonwoven fabric (A) simultaneously satisfying the following conditions (a) and (b) with an elastic polymer (B). (a) The filament nonwoven fabric (A) is a nonwoven fabric which comprises the ultrafine filaments of a thermoplastic polymer (D) and is obtained by treating with water a filament nonwoven fabric formed from splittable conjugated filaments comprising water-soluble thermoplastic polyvinyl alcohol (C) having a degree of saponification of 90 to 99.99 mol.% and the thermoplastic polymer (D) to dissolve the water-soluble thermoplastic polyvinyl alcohol (C) constituting the splittable conjugate filaments. (b) The single filament fineness of the ultrafine filaments comprising the thermoplastic polymer (D) is 0.0005 to 0.5 dtex. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an artificial leather based on an ultrafine long fiber non-woven fabric obtained by treating a composite long fiber non-woven fabric composed of a water-soluble thermoplastic polyvinyl alcohol and another thermoplastic polymer with water, and the same. It relates to a manufacturing method.

[0002]

2. Description of the Related Art In recent years, artificial leather has been recognized by consumers for its characteristics such as lightness and ease of handling, and has come to be widely used in clothing, general materials, sports fields and the like. In particular, when the base material is a long fiber non-woven fabric, a series of large equipment such as a raw cotton feeding device, a fiber opening device, a card machine and a crosslay machine is not required as a manufacturing method as compared with a non-woven fabric composed of short fibers. Moreover, since it is made of long fibers, it has an advantage that its strength is greater than that of the short fiber non-woven fabric. On the other hand, in the field of such artificial leather,
There is a demand for higher quality, and high quality products that satisfy all of the aesthetic aspects such as appearance and feel, and physical properties such as dimensional stability are required. Specifically, in order to obtain an artificial leather excellent in appearance, texture, etc., a method of making the fibers constituting the artificial leather ultrafine is generally used. As a method for producing an ultrafine long-fiber nonwoven fabric, a method of dividing a composite long-fiber nonwoven fabric having two or more components in the length direction is mainly applied. However, in this case, two or more kinds of fiber components are present in the non-woven fabric, and in order to obtain an ultrafine long-fiber non-woven fabric consisting of only one component, it is necessary to use chemicals to remove one component. I didn't get it. For example, caustic soda or the like is used as a chemical for removing polyester, formic acid or the like is used in the case of polyamide, and trichlorethylene or the like is used in the case of polystyrene. Such a method requires special equipment in terms of danger of handling chemicals and environmental pollution, and is not sufficiently satisfactory in terms of worker safety and hygiene and manufacturing cost. In addition, since a component other than the component to be removed is unfavorably affected, the combination of components constituting the composite fiber is limited, or the component to be removed cannot be removed sufficiently and must be used without being satisfied. In some cases, non-woven fabrics and artificial leathers of some quality could not be obtained.

On the other hand, polyvinyl alcohol (hereinafter, PV
It is known that (A, which may be abbreviated as A) is a water-soluble polymer, and the degree of water solubility can be changed by its basic skeleton, molecular structure, morphology, and various modifications.
It has also been confirmed that PVA is biodegradable.
At the present time, how to harmonize synthetic materials with the natural world has become a major issue in terms of the global environment, and PVA and PVA-based fibers having such basic performance have attracted much attention.

[0004]

The object of the present invention is to enable the production of ultrafine long-fiber nonwoven fabrics by treating with water without using chemicals, stabilize the production of ultrafine long-fibers, and An object of the present invention is to provide an artificial leather excellent in appearance, texture, etc. by improving the quality of the nonwoven fabric as a material.

[0005]

The present invention uses chemicals and the like by using a melt-spun composite long-fiber nonwoven fabric (so-called spunbonded nonwoven fabric) composed of water-soluble thermoplastic polyvinyl alcohol and a thermoplastic polymer. It is possible to provide an ultrafine long-fiber non-woven fabric as an artificial leather base material by simply treating with water without any treatment. That is, the present invention provides the following (a) and (b)
Condition, (a) long fiber non-woven fabric (A), saponification degree 90 ~
A long-fiber non-woven fabric composed of split-type composite long fibers consisting of 99.99 mol% of a water-soluble thermoplastic polyvinyl alcohol (C) and a thermoplastic polymer (D) is treated with water to obtain the split-type composite fibers. It is a nonwoven fabric composed of ultrafine long fibers of a thermoplastic polymer (D) obtained by dissolving and removing the water-soluble thermoplastic polyvinyl alcohol (C) constituting the composition, and (b) ultrafine long film composed of the thermoplastic polymer (D). Single fiber fineness of fiber is 0.0005 to 0.5
The artificial leather is characterized in that the elastic polymer (B) is impregnated inside the long fiber non-woven fabric (A) which simultaneously satisfies dtex. The present invention also provides a water-soluble thermoplastic polyvinyl alcohol having a saponification degree of 90 to 99.99 mol% when producing artificial leather made of an elastic polymer (B) impregnated in a long fiber nonwoven fabric (A). A step of producing a continuous fiber nonwoven fabric composed of splittable conjugate continuous fibers composed of (C) and a thermoplastic polymer (D); a step of impregnating the elastic polymer (B) inside the continuous fiber nonwoven fabric; Single filament fineness of composite long fibers is 0.0005-
The method for producing artificial leather is characterized in that the step of converting to 0.5 dtex ultrafine long fibers is performed in the order of or.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The artificial leather of the present invention comprises a water-soluble thermoplastic P having a saponification degree of 90 to 99.99 mol%.
A splittable composite long fiber nonwoven fabric (A) is prepared from VA (C) and a thermoplastic polymer (D). The non-woven fabric can be efficiently produced by a so-called spun-bonded non-woven fabric manufacturing method directly connected to melt spinning. This non-woven fabric is treated with water to dissolve or remove the water-soluble thermoplastic PVA (C) that constitutes the splittable composite long fibers to form ultrafine long fibers made of the thermoplastic polymer (D), before or after the long fibers. A nonwoven fabric is impregnated with a treatment agent mainly composed of an elastic polymer (B) and solidified. By such a method, it is possible to manufacture artificial leather composed of an ultrafine long-fiber nonwoven fabric and an elastic polymer.

The artificial leather obtained in this way becomes a suede-like artificial leather by raising and dyeing the surface. It is also possible to manufacture a silver-finished artificial leather by coating the surface of the artificial leather with a pigment-added elastic polymer for finishing to form a silver surface coating layer.

First, the saponification degree is 90 to 99.99 mol%.
The process for producing a continuous fiber nonwoven fabric composed of splittable conjugate continuous fibers composed of the water-soluble thermoplastic polyvinyl alcohol (C) and the thermoplastic polymer (D) will be described below. PVA (C) in the present invention means PV
Not only the homopolymer of A, but also, for example, modified PVA having a functional group introduced by copolymerization, terminal modification, and post-modification.
Is also included.

The PVA used in the present invention has a viscosity average degree of polymerization (hereinafter, simply referred to as a degree of polymerization) of preferably 200 to 800, more preferably 230 to 600, and even more preferably 250 to 5
00 is particularly preferred. If the degree of polymerization is less than 200, sufficient spinnability may not be obtained during spinning, and as a result, a satisfactory artificial leather may not be obtained. on the other hand,
If the degree of polymerization exceeds 800, the melt viscosity may be too high to discharge the polymer from the spinning nozzle.

The degree of polymerization (P) of PVA is JIS-K67.
It is measured according to 26. That is, it is obtained by the following formula from the intrinsic viscosity [η] (dl / g) measured in water at 30 ° C. after completely re-saponifying and purifying PVA. P = ([η] × 10 ³ /8.29) ^{(1 / 0.62)}

Water-soluble thermoplastic PVA used in the present invention
The saponification degree of (C) is 90 to 99.99 mol%, and 9
2 to 99.98 mol% is preferable, 94 to 99.96 mol% is more preferable, and 95 to 99.95 mol% is particularly preferable. When the saponification degree is less than 90 mol%, PVA
The heat stability is poor and the composite melt spinning cannot be performed satisfactorily due to thermal decomposition and gelation, and the composite continuous fiber nonwoven fabric of the present invention directly connected to the melt spinning cannot be performed. On the other hand, the saponification degree is 9
PVA larger than 9.99 mol% is difficult to stably produce.

PVA can be obtained by saponifying vinyl ester units of a vinyl ester polymer. As the vinyl compound monomer for forming the vinyl ester unit, vinyl formate, vinyl acetate, vinyl propionate, vinyl valerate, vinyl caprate, vinyl laurate, vinyl stearate, vinyl benzoate, vinyl pivalate and Examples thereof include vinyl versatate, and of these, vinyl acetate is preferable from the viewpoint of obtaining the PVA of the present invention.

PVA, which is one component of the composite long-fiber nonwoven fabric of the present invention, may be a homopolymer or a modified PVA in which a copolymerized unit is introduced, but the composite melt spinnability, hydrophilicity, fiber From the viewpoint of the physical properties of the non-woven fabric, it is preferable to use the modified PVA having a copolymerized unit introduced therein.
Examples of the type of copolymerization monomer include α such as ethylene, propylene, 1-butene, isobutene, and 1-hexene.
-Olefins, acrylic acid and salts thereof, methyl acrylate, ethyl acrylate, n-propyl acrylate,
Acrylic acid esters such as i-propyl acrylate, methacrylic acid and salts thereof, methacrylic acid esters such as methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, i-propyl methacrylate, acrylamide, N-methyl acrylamide , Acrylamide derivatives such as N-ethyl acrylamide, methacrylamide, N-methyl methacrylamide, methacrylamide derivatives such as N-ethyl methacrylamide, methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, i-propyl vinyl ether, n-butyl vinyl ether And other vinyl ethers, ethylene glycol vinyl ether, 1,3-propanediol vinyl ether, 1,4-butanediol vinyl ether and other hydroxy group-containing vinyls Ether compounds, allyl acetate,
Allyl ethers such as propyl allyl ether, butyl allyl ether and hexyl allyl ether, monomers having an oxyalkylene group, vinylsilyls such as vinyltrimethoxysilane, isopropenyl acetate, 3-butene-
Hydroxy such as 1-ol, 4-penten-1-ol, 5-hexen-1-ol, 7-octen-1-ol, 9-decen-1-ol, 3-methyl-3-buten-1-ol Group-containing α-olefins, N-vinylformamide, N-vinylacetamide, N-vinylamides such as N-vinylpyrrolidone, fumaric acid, maleic acid, itaconic acid, maleic anhydride, phthalic anhydride, trimellitic anhydride Or a monomer having a carboxyl group derived from itaconic anhydride or the like; a unit amount having a sulfonic acid group derived from ethylene sulfonic acid, allyl sulfonic acid, methallyl sulfonic acid, 2-acrylamido-2-methylpropane sulfonic acid or the like Body; vinyloxyethyl trimethyl ammonium chloride, vinyloxy butyl trimethyl ammonium chloride Ride, vinyloxy ethyl dimethylamine, vinyloxy methyldiethylamine, N- acrylamidomethyl trimethylammonium chloride, N
Examples include monomers having a cationic group derived from acrylamidoethyltrimethylammonium chloride, N-acrylamidodimethylamine, allyltrimethylammonium chloride, methallyltrimethylammonium chloride, dimethylallylamine, allylethylamine and the like. The content of these monomers is usually 20 mol% or less.

Among these monomers, α-olefins such as ethylene, propylene, 1-butene, isobutene, and 1-hexene, methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, Vinyl ethers such as i-propyl vinyl ether and n-butyl vinyl ether, hydroxy group-containing vinyl ethers such as ethylene glycol vinyl ether, 1,3-propanediol vinyl ether and 1,4-butanediol vinyl ether, allyl acetate, propyl allyl ether, butyl Allyl ether,
Allyl ethers such as hexyl allyl ether, N-vinylformamide, N-vinylacetamide, N-vinylamides such as N-vinylpyrrolidone, monomers having an oxyalkylene group, 3-buten-1-ol, 4-
Penten-1-ol, 5-hexen-1-ol, 7
-Octen-1-ol, 9-decen-1-ol, 3
Monomers derived from hydroxy group-containing α-olefins such as -methyl-3-buten-1-ol are preferred.

Particularly, from the viewpoints of copolymerizability, melt spinning property and fiber physical properties, ethylene, propylene, 1-butene, isobutene having α-olefins having 4 or less carbon atoms, methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, Vinyl ethers such as i-propyl vinyl ether and n-butyl vinyl ether are more preferable.
The unit derived from α-olefins and / or vinyl ethers having 4 or less carbon atoms is 0.1 to 15 in PVA.
It is preferably present in an amount of mol%, more preferably 2 to 13 mol%. Furthermore, since the physical properties of the fiber become high,
Modified PVA with ethylene introduced as α-olefin
Is particularly preferably used. The content of the ethylene unit is preferably 3 to 15 mol%, more preferably 5 to 13 mol%.

The PVA used in the present invention is a bulk polymerization method,
Known methods such as a solution polymerization method, a suspension polymerization method and an emulsion polymerization method can be mentioned. Among them, a bulk polymerization method or a solution polymerization method in which polymerization is carried out without solvent or in a solvent such as alcohol is usually adopted. The alcohol used as a solvent during the solution polymerization, methyl alcohol, ethyl alcohol,
Lower alcohols such as propyl alcohol may be mentioned. As the initiator used for the copolymerization, α, α′-azobisisobutyronitrile, 2,2′-azobis (2,4
-Dimethyl-valeronitrile), benzoyl peroxide, n
-A known initiator such as an azo-based initiator such as propyl peroxycarbonate or a peroxide-based initiator may be mentioned. The polymerization temperature is not particularly limited, but it is 0 ° C to 20 ° C.
A range of 0 ° C is suitable.

The content ratio of the alkali metal ion (E) in the PVA (C) used in the present invention is PVA (C) 1
0.000 in terms of sodium ion with respect to 00 parts by mass
1 to 0.05 parts by mass is preferable, and 0.0001 to 0.0
3 parts by mass is more preferable, and 0.0002 to 0.01 parts by mass is particularly preferable. When the content ratio of the alkali metal ions is less than 0.0001 part by mass, industrial production tends to be difficult. The content of alkali metal ions is 0.0
If the amount is more than 5 parts by mass, decomposition, gelation and yarn breakage during composite melt spinning are likely to occur, and stable fiberization may not be possible in some cases. Examples of alkali metal ions include potassium ion and sodium ion.

In the present invention, the method of incorporating a specific amount of alkali metal ion (E) into PVA is not particularly limited, and a method of polymerizing PVA and then adding an alkali metal ion-containing compound, a polymer of vinyl ester. In the saponification of PVA in a solvent, by using an alkaline substance containing an alkali ion as a saponification catalyst, an alkali metal ion is added to PVA, and the PVA obtained by saponification is washed with a washing liquid Although the method of controlling the content of the alkali metal ion contained in 1) and the like can be mentioned, the latter is preferable because the step of saponification and the step of incorporating the metal ion can be carried out at the same time.
The content of alkali metal ions can be determined by the atomic absorption method.

Examples of the alkaline substance used as the saponification catalyst include potassium hydroxide and sodium hydroxide. The molar ratio of the alkaline substance used in the saponification catalyst is preferably 0.004 to 0.5, and particularly preferably 0.005 to 0.05, based on the vinyl acetate unit. The saponification catalyst may be added all at once at the beginning of the saponification reaction or may be additionally added during the saponification reaction. Examples of the solvent for the saponification reaction include methanol, methyl acetate, dimethyl sulfoxide, dimethylformamide and the like. Among these solvents, methanol is preferable and its water content is 0.
More preferably, the methanol controlled to 001 to 1 mass% is more preferable, the water content controlled to 0.003 to 0.9 mass% is more preferable, and the water content controlled to 0.005 to 0.8 mass% is methanol. Particularly preferred. Examples of the washing liquid include methanol, acetone, methyl acetate, ethyl acetate, hexane, water and the like, and among them, methanol, methyl acetate, water alone or a mixed liquid is more preferable. The amount of cleaning liquid is alkali metal ion (E)
Is set to satisfy the content ratio of
300-10000 mass parts is preferable with respect to A100 mass parts, and 500-5000 mass parts is more preferable. The washing temperature is preferably 5 to 80 ° C, 20 to 70 ° C
Is more preferable. The washing time is preferably 20 minutes to 100 hours, more preferably 1 hour to 50 hours.

2 in PVA (C) used in the present invention
The content ratio of the acid (F) having an acid group having a pKa of 5.0 or less at 5 ° C. is preferably α of 0.01 to 1 shown below, more preferably 0.03 to 0.8,
0.05 to 0.6 is particularly preferable. In the present invention, the content of the acid (F) in the formula of α shown below means the value obtained by the neutralization titration method converted to acetic acid. pKa is defined by pKa = -logKa, where Ka is the acid dissociation constant. When an acid having an acid group with a pKa of more than 5.0 is used and when the acid (F) content is out of 0.01 to 1 in α shown below, PVA during composite melt spinning. The decomposition, gelation and yarn breakage of the above may occur, and it may not be possible to stably form fibers. Examples of the acid (F) having an acid group having a pKa at 25 ° C. of 5.0 or less include acetic acid, phosphoric acid, sodium monophosphate and the like. α = {acid (F) content in polyvinyl alcohol (mass%)} / {alkali metal ion (E) content in polyvinyl alcohol (mass%)}

In the present invention, the method of incorporating a specific amount of the acid (F) having an acid group having a pKa at 25 ° C. of 5.0 or less in PVA is not particularly limited, and a vinyl ester polymer is saponified in a solvent. And then the pKa is 5.0
A method of controlling the acid content contained in PVA by blending the acid in PVA by using an acid having the following acid group, washing the PVA obtained by saponification with a washing liquid, and drying. Examples thereof include a method of treating the above-mentioned PVA with a solvent containing an acid to contain a specific amount of the acid, a method of adding a specific amount of the acid when producing PVA pellets, and the like. The acid content can be determined by neutralization titration of the methanol extract from PVA with an aqueous sodium hydroxide solution.

Further, a plasticizer may be added to PVA for the purpose of adjusting the melting point and melt viscosity, etc. within the range that does not impair the objects and effects of the present invention. As the plasticizer, all conventionally known ones can be used, but diglycerin, polyglycerin alkyl monocarboxylic acid esters, glycols to which ethylene oxide and propylene oxide are added are preferably used. Among the,
1 to 1 mol of ethylene oxide for 1 mol of sorbitol
A compound added with 30 mol% is preferable.

The PVA used in the present invention has biodegradability and is decomposed into water and carbon dioxide when treated with activated sludge or buried in soil. The activated sludge method is preferable for treating the waste liquid after the PVA is dissolved. When the aqueous PVA solution is continuously treated with activated sludge, it is decomposed in 2 days to 1 month. Further, since PVA used in the present invention has a low combustion heat and a small load on the incinerator, the waste water in which PVA is dissolved may be dried to incinerate PVA.

The thermoplastic polymer (D) used in the present invention is, for example, an aromatic polyester such as polyethylene terephthalate, polybutylene terephthalate, polyhexamethylene terephthalate, polylactic acid, polyethylene succinate, polybutylene succinate, polybutylene. Aliphatic polyesters and their copolymers such as succinate adipate, polyhydroxybutyrate-polyhydroxyvalerate copolymer, polycaprolactone and the like, nylon 6, nylon 66, nylon 10, nylon 1
2, aliphatic polyamides such as nylon 6-12 and copolymers thereof, polyolefins such as polypropylene, polyethylene, polybutene and polymethylpentene and copolymers thereof, ethylene-vinyl containing 20 to 70 mol% of ethylene units. Alcohol-based copolymer, polystyrene-based, polydiene-based, chlorine-based, polyolefin-based,
At least one kind can be selected and used from polyester-based, polyurethane-based, polyamide-based, and fluorine-based elastomers. PV used in the present invention
From the viewpoint of good composite spinnability with A and excellent performance as a nonwoven fabric and artificial leather, polyethylene terephthalate, polylactic acid,
It is preferable to use nylon 6, nylon 66, polypropylene, polyethylene, and an ethylene-vinyl alcohol copolymer containing 20 to 70 mol% of ethylene units.

The mass ratio of (C) and (D) of the composite long-fiber nonwoven fabric composed of PVA (C) and thermoplastic polymer (D) used in the present invention is 5/95 to 95/5, which is 10/9.
0 to 90/10 is more preferable. If it is out of the preferable range, the combined effect may not be exhibited.

In the range not impairing the objects and effects of the present invention, the thermoplastic PVA and the thermoplastic polymer may optionally contain stabilizers such as copper compounds, colorants, UV absorbers, light stabilizers, and oxidants. An inhibitor, an antistatic agent, a flame retardant, a plasticizer, a lubricant and a crystallization rate retarder can be added during the polymerization reaction or in the subsequent step. In particular, the addition of organic stabilizers such as hindered phenols, copper halide compounds such as copper iodide, and alkali metal halide compounds such as potassium iodide as heat stabilizers improves melt retention stability during fiber formation. Therefore, it is preferable.

If necessary, the average particle size is 0.01 μm.
Fine particles of m or more and 5 μm or less can be added in an amount of 0.05% by mass or more and 10% by mass or less during the polymerization reaction or in the subsequent step. The type of fine particles is not particularly limited, and for example, inert fine particles such as silica alumina, titanium oxide, calcium carbonate, barium sulfate can be added, and these may be used alone or in combination of two or more kinds. In particular, inorganic fine particles having an average particle diameter of 0.02 μm or more and 1 μm or less are preferable, and spinnability and stretchability are improved.

Next, a method for producing a composite non-woven fabric composed of long fibers composed of PVA (C) and a thermoplastic polymer (D) used in the present invention will be described. The composite non-woven fabric composed of the long fibers of the present invention can be efficiently produced by a method for producing a so-called spun-bonded non-woven fabric directly connected to melt spinning.

For example, PVA (C) and thermoplastic polymer (D) are melted and kneaded by different extruders respectively, and then the same melted polymer stream is guided to the spinning head, and the flow rate is measured and discharged from the spinning nozzle hole. After cooling the discharged composite fiber with a cooling device, a suction device such as an air jet nozzle is used to obtain the desired fineness.
000 to 6000 m / min. After being pulled and thinned by a high-speed air stream at a speed corresponding to the take-up speed of the composite fiber, the nonwoven fabric web is formed by depositing it on the movable collecting surface while opening the fiber. A composite long-fiber nonwoven fabric can be obtained by partially pressure-bonding and winding this web.

The composite cross section of the composite long fibers constituting the composite long fiber nonwoven fabric of the present invention has a splitting property in view of splittability, uniformity of ultrafine long fibers after splitting, quality as nonwoven fabric and artificial leather, physical properties and the like. Radial splittable conjugate fibers with wedge-shaped or fan-shaped components, multilayer bonded splittable conjugate fibers with strip-shaped components, sea-island type with multiple splitting components dispersed in matrix Those having a composite fiber are preferable.

In the present invention, it is necessary to appropriately set the conditions for fiberizing the composite long-fiber nonwoven fabric depending on the combination of polymers and the composite cross section. It is desirable to determine the conditions. The spinneret temperature is (Mp + 10) ° C. when the melting point of a polymer having a high melting point among the polymers constituting the composite filament is Mp.
(Mp + 80) ° C. is preferable, shear rate (γ) is 500-
25000 sec ^-1 , draft (V) 50 to 2000
It is preferable to carry out spinning. Further, when viewed from the combination of the polymers to be composited, it is preferable from the viewpoint of spinning stability to combine the polymers by combining polymers having melt viscosities close to each other when measured by the spinneret temperature during spinning and the shear rate when passing through the nozzle. .

The melting point Tm of PVA in the present invention is the peak temperature of the main endothermic peak observed with a differential scanning calorimeter (DSC: TA3000 manufactured by Mettler). The shear rate (γ) is calculated by γ = 4Q / πr ³ when the nozzle radius is r (cm) and the polymer discharge amount per single hole is Q (cm ³ / sec). Further, the draft V is calculated by V = 5A · πr ² / 3Q when the take-up speed is A (m / min).

In the production of the conjugate fiber of the present invention, when the spinneret temperature is lower than the melting point Mp + 10 ° C. of the polymer having a high melting point among the polymers constituting the conjugate filament, the melt viscosity of the polymer is too high, Inferior in stringing and thinning due to high-speed air flow, and PV when Mp + 80 ° C exceeded
A tends to be thermally decomposed, so that stable spinning is difficult. Further, the shear rate is easily Dan'ito lower than 500 sec ^-1, spinnability becomes high back pressure of the nozzle and higher than 25000Sec ^-1 tends to decrease. When the draft is lower than 50, the fineness unevenness becomes large and it becomes difficult to stably spin, and when the draft is higher than 2000, the yarn is easily broken.

In the present invention, when the discharged composite fibers are towed and thinned by using a suction device such as an air jet nozzle, a high-speed air flow is applied at a speed corresponding to the take-up speed of the composite fibers of 1000 to 6000 m / min. It is preferable to make the traction thin. The condition for drawing the composite fiber by the suction device is appropriately selected depending on the melt viscosity of the molten polymer discharged from the spinning nozzle hole, the discharge speed, the spinning nozzle temperature, the cooling condition, etc. Adhesion between adjacent composite fibers may occur due to delay in solidification, and it is difficult for orientation and crystallization of composite fibers to proceed.
The resulting composite non-woven fabric tends to be coarse and have low mechanical strength. On the other hand, if it exceeds 6000 m / min, it is difficult to follow the stringing / thinning properties of the discharged composite fiber, and the composite fiber is cut, which makes it difficult to manufacture a stable composite long-fiber nonwoven fabric. Further, in the stable production of the PVA-based composite long-fiber nonwoven fabric of the present invention, the distance between the spinning nozzle hole and a suction device such as an air jet nozzle is 30 to 30.
It is important that it is 200 cm. The distance depends on the polymer used, the composition, and the spinning conditions described above, but if the distance is less than 30 cm, fusion between adjacent conjugate fibers may occur due to a delay in cooling and solidification of the discharged conjugate fibers. In addition, the orientation and crystallization of the composite fibers do not proceed, and the resulting composite nonwoven fabric becomes coarse and has low mechanical strength, which is not preferable. On the other hand, when it exceeds 200 cm, the discharged composite fibers are cooled and solidified too much and the drawability / thinning property of the discharged composite fibers cannot be followed, and the composite fibers are cut, so that a stable composite long-fiber nonwoven fabric is produced. Is hard to do.

Next, in the step of converting the splittable composite continuous fibers into ultrafine continuous fibers having a single fiber fineness of 0.0005 to 0.5 dtex, the present invention changes the composite continuous fiber nonwoven fabric into PVA.
It is important to manufacture the divided ultrafine long fiber nonwoven fabric (A) of the thermoplastic polymer (D) which becomes the artificial leather substrate by dissolving and removing (C) with water. There is no particular limitation on the method for extracting PVA (C) from the composite long-fiber nonwoven fabric with water,
Any method such as a method of treating in hot water of a dyeing machine or a method of injecting a high-pressure water stream such as a water jet method can be appropriately selected. The extracted water may be neutral, and may be an alkaline aqueous solution, an acidic aqueous solution, or an aqueous solution added with a surfactant or the like. The extraction treatment temperature may be appropriately adjusted according to the purpose, but the higher the treatment temperature, the shorter the treatment time. When extracting using hot water,
It is preferable to carry out the treatment at 50 ° C. or higher, and it is particularly preferable to carry out the extraction treatment at 80 ° C. or higher. In addition, the water jet method is a very effective method in that it enables dissolution and removal of PVA and joining of divided ultrafine long fibers at the same time. Also,
The step of dissolving and removing PVA (C) and converting it into ultrafine long fibers may be performed either before or after the impregnation with the elastic polymer (B).

In the present invention, PVA is used instead of composite long fiber nonwoven fabric.
Each of the divided ultrafine filaments of the thermoplastic polymer (D) obtained by dissolving and removing (C) with water is 0.0005 to 0.5.
With a fineness of dtex, 0.001-0.45 dtex
Preferably has a fineness of 0.002 to 0.4d
It is more preferable to have a tex fineness of 0.005.
It is particularly preferable to have a fineness of ˜0.35 dtex. When the fineness of the segmented ultrafine fibers is less than 0.0005 dtex, the fiber strength of the ultrafine fibers becomes low and the function as a long fiber non-woven fabric cannot be sufficiently fulfilled, and as a result, artificial leather of good quality is obtained. It cannot be manufactured.
On the other hand, when the fineness of the divided ultrafine fibers is larger than 0.5 dtex, the ultrafine fibers are not sufficiently thinned and the flexibility of the artificial leather is lowered.

In the present invention, the composite long-fiber nonwoven fabric and divided ultrafine long-fiber nonwoven fabric obtained as described above are subjected to a hot embossing method, an emulsion bonding method, a water jet method, a needle punch method, an ultrasonic sealing method, a powder dot bonding method. ,
A method of maintaining the shape by a joining method such as a through air method or a stitch bond method is adopted. Among them, the hot embossing method, the water jet method, and the needle punch method are particularly preferable from the viewpoints of the appearance and quality of the ultrafine long fiber nonwoven fabric and artificial leather. There is no particular limitation on which stage the joining is performed, and the joining can be appropriately performed as necessary. For example, it may be before the PVA is extracted with water or after the divided ultrafine division.

Further, the ultrafine long fiber nonwoven fabric obtained by the present invention can be used not only alone but also as a laminate with a homo long fiber nonwoven fabric or a nonwoven fabric produced by other methods such as melt blown. Therefore, when used for the above-mentioned purposes, a practical function can be further provided. The non-woven fabric needs to have a shape suitable for the purpose in consideration of the thickness of the artificial leather and the like.
000 g / m ² , more preferably 70 to 1000 g / m
² , the thickness is preferably 0.2 to 20 mm, more preferably 0.5 to 10 mm from the viewpoint of easy handling during the process.

Next, in the step of impregnating the elastic polymer (B) into the long fiber nonwoven fabric, the elastic polymer (B) used in the present invention has, for example, an average molecular weight of 500 to 30.
00 polyester diol, polyether diol,
Polyols such as polycarbonate diols and polyester polyether diols; aromatic, alicyclic and aliphatic organic diisocyanates such as 4,4-diphenylmethane diisocyanate, isophorone diisocyanate and hexamethylene diisocyanate; ethylene glycol;
Examples thereof include polyurethanes obtained by reacting a chain extender having two or more active hydrogens such as 1,4-butanediol and isophoronediamine. If necessary, a polyester elastomer and a styrene-isoprene block copolymer may be mentioned. It is also possible to add a hydrogenated product of the above. The elastic polymer (B) is dissolved in a solvent or dispersed in a non-solvent such as water to prepare a polymer liquid, which is then impregnated into the nonwoven fabric and treated with the non-solvent of the polymer for wet coagulation, or heat treatment or It is subjected to hot water treatment, etc. for dry coagulation, hot water coagulation, or heat-sensitive gelation treatment. Among them, a preferable example is one obtained by impregnating and imparting a water-dispersed emulsion from the viewpoint that the load on the environment is small without using an organic solvent.

The ratio of the ultrafine fiber nonwoven fabric (A) to the elastic polymer (B) is preferably in the range of 90/10 to 50/50. In particular, as artificial leather, it is preferable that the amount of the elastic polymer is small if the characteristics of the leather are desired to be emphasized, and that the amount of the elastic polymer is large if the resilience characteristics are desired to be emphasized. The thickness of the obtained artificial leather can be arbitrarily selected according to the application and is not particularly limited, but is preferably 0.3 mm to 4 mm, particularly preferably 0.5 mm.
The range is from 3.0 mm. Further, the basis weight is preferably 120 g / m ^{2 to} 1600 g / in terms of texture and fullness.
m ² , particularly preferably 200 g / m ^{2 to} 1200 g / m
The range is ² .

If necessary, the elastic polymer may be blended with additives such as a colorant, a coagulation modifier, an antioxidant and a dispersant.

The essential point of the artificial leather of the present invention is to rationally provide the ultrafine long-fiber nonwoven fabric as the base material as described above. Therefore, the present invention is particularly limited in terms of mechanical properties such as basis weight and tensile strength, tensile elongation, tear strength and the like of nonwoven fabrics and artificial leather, morphological characteristics such as thickness and bulkiness, or characteristics such as flexibility. However, it can be appropriately selected within a set range.

[0043]

EXAMPLES The present invention will now be specifically described with reference to Examples.
The invention is not limited to these examples. In the examples, each physical property value was measured as follows.
The parts and% in the examples relate to mass unless otherwise specified.

[PVA analysis method] PVA analysis method was in accordance with JIS-K6726 unless otherwise specified. The modification amount is 500 MHz 1H-NMR (JEOL GX-50, using modified polyvinyl ester or modified PVA).
0) Obtained from the measurement by the device. The content of alkali metal ions was determined by the atomic absorption method.

[Analysis Method of Acid Content in PVA] Using 20 g of absolutely dried PVA, methanol Soxhlet extraction was carried out for 3 days using 100 mL of methanol. 50 mL of distilled water and a few drops of phenolphthalein were added to 50 mL of the extract, and the acid in the extract was neutralized and titrated with an aqueous solution of 1/1000 N sodium hydroxide to give a slightly red color as the end point. The acid content in PVA was converted to acetic acid by the following formula. Acetic acid (%) = (0.12 x titration mL x 100) / (1
000 × 20)

[Melting Point] The melting point of PVA was determined by using DSC (Mettler, TA3000) in nitrogen and at a heating rate of 10
The temperature at the peak top of the endothermic peak showing the melting point of PVA when the temperature was raised to 250 ° C. at a rate of ° C./min, cooled to room temperature, and then raised to 250 ° C. at a rate of temperature increase of 10 ° C./min was examined.

[Spinning state] The state of melt spinning was observed and evaluated according to the following criteria. ◎: Very good ○: Good, △: Somewhat difficult ×: Poor

[Nonwoven fabric state] The obtained nonwoven fabric was visually and touch-observed and evaluated according to the following criteria. ◎: Homogeneous and extremely good ○: Almost homogeneous and good, △: Somewhat difficult ×: Poor

[Nonwoven fabric and leather areal weight and thickness] JIS
It measured according to L1906.

[Tear strength of leather] Measured in the machine direction and the transverse direction according to JIS L1906, and shown as the average value.

[0051] [Appearance of leather]     ◎: Smooth and dense and extremely good ○: Smooth and dense and good     △: Somewhat difficult ×: Poor

[0052] [Leather texture]     ◎: Soft and smooth and extremely good ○: Soft and good     △: Somewhat difficult ×: Poor

Example-1 [Production of ethylene-modified PVA] Stirrer, nitrogen inlet, d
100L pressurization equipped with a ethylene inlet and an initiator addition port
29.0 kg vinyl acetate and 3 methanol in the reaction tank
Charge 1.0 kg, raise the temperature to 60 ° C, and then nitrogen for 30 minutes.
The system was replaced with nitrogen by bubbling. Then the reactor pressure
Power is 5.9kg / cm^Two(5.8 x 10⁵Pa)
Thus, ethylene was introduced and charged. 2, as an initiator
2'-azobis (4-methoxy-2,4-dimethylvale)
Ronitrile) (AMV) dissolved in methanol
Bubbling with nitrogen gas after adjusting 2.8 g / L solution
Then, the atmosphere was replaced with nitrogen. Adjust the temperature inside the polymerization tank to 60 ℃
After the preparation, 170 ml of the above initiator solution was injected to carry out polymerization.
Started. During the polymerization, ethylene is introduced to increase the reactor pressure.
5.9 kg / cm^Two(5.8 x 10 ⁵Pa), polymerization temperature
The temperature is maintained at 60 ° C. and 610 with the above initiator solution.
Polymerization was carried out by continuously adding AMV at ml / hr. 1
After 0 hours, when the rate of polymerization reached 70%, cool and
I stopped working. After removing the ethylene by opening the reaction tank,
The degassing was completely carried out by bubbling a raw gas. Next
Then, remove unreacted vinyl acetate monomer under reduced pressure to remove poly vinegar.
A vinyl acetate solution in methanol was used.

46.5 g (polyacetic acid) was added to 200 g of a methanol solution of polyvinyl acetate (100 g of polyvinyl acetate in the solution) prepared by adding methanol to the obtained polyvinyl acetate solution to adjust the concentration to 50%. Saponification was performed by adding an alkaline solution (NaOH 10% methanol solution) in a molar ratio (MR) of 0.10 to vinyl acetate units in vinyl. After about 2 minutes from the addition of the alkali, the system gelled was crushed with a crusher and allowed to stand at 60 ° C. for 1 hour to proceed with saponification, followed by 0.5% acetic acid in water / methanol = 20/80. 1000 g of the mixed solution was added to neutralize the remaining alkali. After confirming the completion of neutralization using a phenolphthalein indicator, the white solid PVA obtained by filtration was mixed with water / methanol = 20/80 mixed solution 2
000 g was added, and the mixture was left standing and washed at room temperature for 3 hours. After repeating the above washing operation 3 times, 1000 g of methanol is further added.
Was added and the mixture was left standing to be washed at room temperature for 3 hours. Then, the PVA obtained by centrifugal deliquoring was left in a dryer at 70 ° C. for 2 days to obtain dried PVA (PVA-1).

The degree of saponification of the obtained ethylene-modified PVA was 98.4 mol%. Further, the content of sodium measured by an atomic absorption spectrophotometer after ashing the modified PVA and dissolving it in an acid was 0.001 part by mass with respect to 100 parts by mass of the modified PVA. Subsequently, 20 g of absolutely dried PVA obtained by vacuum-drying the modified PVA obtained above at 50 ° C. for 10 hours was subjected to methanol Soxhlet extraction for 3 days using 100 mL of methanol. Extraction liquid 50m
50 mL of distilled water and a few drops of phenolphthalein were added to L, and the content of acetic acid measured by neutralization titration of the acid in the extract with an aqueous solution of 1/1000 N sodium hydroxide was
It was 0.00008 parts by mass with respect to 100 parts by mass of the modified PVA, and the value α representing the ratio of acetic acid and sodium ions in PVA was 0.08.

Further, a methanol solution of polyvinyl acetate obtained by removing unreacted vinyl acetate monomer after the polymerization is added to n.
-Precipitation in hexane and reprecipitation by dissolving in acetone were performed 3 times, and then dried under reduced pressure at 80 ° C for 3 days to obtain purified polyvinyl acetate. The polyvinyl acetate was dissolved in DMSO-d6 and subjected to 500 MHz proton NMR (JEOL GX
-500), the content of ethylene was 10 mol% when measured at 80 ° C. The above methanol solution of polyvinyl acetate was saponified at an alkali molar ratio of 0.5, and the pulverized product was allowed to stand at 60 ° C. for 5 hours to proceed with saponification, followed by methanol soxhlet for 3 days, and then at 80 ° C. The product was dried under reduced pressure for 3 days to obtain a purified ethylene-modified PVA. The average degree of polymerization of the PVA was measured by the conventional method J
It was 330 when measured according to IS K6726. Furthermore, a 5% aqueous solution of the purified modified PVA was prepared to prepare a cast film having a thickness of 10 μm.
After the film was dried under reduced pressure at 80 ° C. for 1 day, D
When the melting point of PVA was measured by the above-mentioned method using SC (Mettler, TA3000), it was 206 ° C. (Table 1).

[0057]

[Table 1]

The PVA obtained above was set at a temperature of 220 ° C. and a screw rotation speed of 100 rp using a Labo Plastomill (Biaxial, 20 mmφ, L / D = 28) manufactured by Toyo Seiki Co., Ltd.
Pellets were produced by melt extrusion at m (Table 1).

The PVA (PVA-1) pellets obtained above and polyethylene terephthalate (PET) having an intrinsic viscosity of 0.7 and a melting point of 255 ° C. were prepared, and each polymer was put into another PVA side by an extruder. 220 ℃ ± 1 ℃
Then, the PET side is heated to 285 ° C. ± 1 ° C., melt-kneaded,
The composite filaments constituting the non-woven fabric were introduced into a 16-split composite spinning pack (Fig. 1) at 285 ° C so that the mass ratio in the fiber cross section orthogonal to the fiber axis was PVA / PET = 30/70, and the nozzle diameter 0.35 mmφ x 1008 holes, discharge rate 625 g / min, shear rate 2500 sec
80 c from the nozzle while discharging from the spinneret under the condition of ^-1 and cooling the spun filament group with cooling air at 20 ° C.
300 with high-speed air by an ejector at a distance of m
The filament group opened and drawn by a draft 410 at a take-up speed of 0 m / min was collected and deposited on an endlessly rotating collecting conveyor device to form a long fiber web. In the spinning state, no yarn breakage was observed at all, and the cross-sectional shape was very good.

Then, this web was passed between an embossing roll having a concavo-convex pattern heated to 150 ° C. and a flat roll under a linear pressure of 50 kg / cm to thermocompression-bond the embossed portions to obtain a single fiber fineness of 1. A 16-division composite long-fiber nonwoven fabric having a basis weight of 171 g / m ² made of long fibers of 85 dtex was obtained. The non-woven fabric obtained was homogeneous and extremely good. Table 2 shows the manufacturing conditions and the manufacturing results of the composite long-fiber nonwoven fabric.

[0061]

[Table 2]

About 50 m of the obtained composite long fiber non-woven fabric, a water jet method (water pressure 150 kg / cm ² ,
The composite filaments were divided and joined at a nonwoven fabric passing speed of 3 m / min). Furthermore, a circular dyeing machine (water bath 700 L, 90 ° C., non-woven fabric rotation speed of about 50 m /
Min.) For 30 minutes × 2 times in hot water to completely extract and remove the PVA component in the composite long fiber nonwoven fabric. Completion of PVA extraction was confirmed by coloring the nonwoven fabric with an iodine solution. Then this web 8
An ultrafine long-fiber nonwoven fabric of polyethylene terephthalate was obtained by drying in a 0 ° C. hot air dryer for about 1 minute. Table 3 shows the results of evaluation of the fineness, unit weight and thickness of the obtained ultrafine long fiber nonwoven fabric.

[0063]

[Table 3]

Next, the ultrafine long-fiber nonwoven fabric obtained above is impregnated with a 15% polyurethane dimethylformamide solution and coagulated in a water bath to impregnate the nonwoven fabric composed of the ultrafine long-fibers with polyurethane. Obtained artificial leather. Table 3 shows the results of evaluation of the basis weight, tensile strength, appearance and texture of the obtained artificial leather.

Example-2 An ultrafine long-fiber non-woven fabric of polyethylene terephthalate was produced in the same manner as in Example-1, and the obtained non-woven fabric was treated with 2
The sheets were pasted together and joined by a needle punching method to produce an ultrafine long-fiber nonwoven fabric having a basis weight of 254 g / m ² . Then, the long-fiber nonwoven fabric was impregnated with polyurethane to obtain artificial leather having a basis weight of 447 g / m ² . Table 3 shows the results of evaluating the physical properties of the obtained ultrafine long fiber nonwoven fabric and artificial leather.

Examples-3 to 11 P shown in Table 1 was used instead of the PVA used in Example-1.
Example except that VA is used, the die for spinneret of the composite type described in Table 2 and the polymer are used, the spinning conditions described in Table 2 are adopted, and the nozzle-ejector distance and the line net speed are appropriately adjusted. PVA under exactly the same conditions as 1
After obtaining a non-woven web composed of a series of composite long fibers, it was partially thermocompressed at the embossing temperature shown in Table 2 to obtain a composite long fiber nonwoven fabric. Then, hydrothermal treatment and PVA extraction were carried out under exactly the same conditions as in Example-1, and artificial leather was obtained by further impregnating the long-fiber nonwoven fabric with polyurethane. The mass ratio of the composite fiber component was adjusted by changing the amount of polymer introduced into the pack. In addition, Example-8
In the cross-section of FIG. 2, the laminated composite fiber of PVA (C) was introduced so that the PVA (C) had 5 layers and the thermoplastic polymer (D) had 6 layers, and the sea-island composite fiber of Example-9 was PVA.
(C) is a sea component, and thermoplastic polymer (D) is an island component (4
00 island). Table 3 shows the results of evaluating the physical properties of the obtained ultrafine long fiber nonwoven fabric and artificial leather.

Example-12 and Example-13 The composite long-fiber nonwoven fabric obtained by thermocompression-bonding the embossed part of Example 1 was subjected to a joining process by the needle punch method,
A 15% polyurethane emulsion solution was impregnated into the inside to heat-gel-solidify and coagulate, and then circular type dyeing machine (water bath 700 L, 90 ° C., non-woven fabric rotation speed about 50
(m / min) for 30 minutes × 2 times in hot water to completely extract and remove the PVA component in the composite long fiber nonwoven fabric. Completion of PVA extraction was confirmed by coloring the nonwoven fabric with an iodine solution. Then, the artificial leather of Example-12 was obtained by drying in an 80 ° C hot air dryer for about 1 minute. An artificial leather of Example-13 was obtained by performing the same treatment as that of Example-12 except that the composite continuous fiber of Example-3 was used. Table 3 shows the results of evaluation of the basis weight, thickness, tear strength, appearance and texture of the obtained artificial leather.

Comparative Example-1 P shown in Table 1 was used in place of the PVA used in Example-1.
Using VA, the polymer and spinning conditions shown in Table 2 are employed, and the PVA-based composite continuous fiber is formed under exactly the same conditions as in Example 1 except that the nozzle-ejector distance and the line net speed are appropriately adjusted. A non-woven fabric was manufactured. Table 2 shows the results of the spinnability and the state of the obtained nonwoven fabric. When the PVA shown in Comparative Example-1 is used, many fibers are broken due to generation of gas containing acetic acid due to thermal decomposition of PVA and gelation, stable fiber formation is not possible, and non-woven fabric formation and artificial leather can also be produced. There wasn't.

Comparative Example-2 and Comparative Example-3 The same PVA as in Example-1 was used, the mold for spinneret of the type described in Table 2 and the polymer were used, and the spinning conditions described in Table 2 were adopted. After obtaining a nonwoven web made of PVA-based composite long fibers under the exact same conditions as in Example 1 except that the nozzle-ejector distance and the line net speed were appropriately adjusted, the embossing temperature shown in Table 2 was used. Partial thermocompression bonding was performed to obtain a composite long-fiber nonwoven fabric. Then, hydroentanglement treatment and PVA extraction treatment were carried out under exactly the same conditions as in Example 2 to make a segmented ultrafine fiber nonwoven fabric, and then impregnated with polyurethane to produce artificial leather. The mass ratio of the composite fiber component was adjusted by changing the amount of polymer introduced into the pack. Further, the sea-island type composite fiber of Comparative Example-2 was led so that the PVA (C) was a sea component and the thermoplastic polymer (D) was an island component (600 islands). Table 3 shows the results of evaluating the physical properties of the obtained ultrafine long fiber nonwoven fabric and artificial leather.

With regard to the artificial leather obtained in Comparative Example-2, the fineness of the split ultrafine filaments after PVA extraction was too small, and therefore the strength of the artificial leather was remarkably reduced. Regarding the artificial leather obtained in Comparative Example-3, since the fineness of the split ultrafine filaments after PVA extraction was too large, the flexibility was low and the texture as artificial leather was insufficient.

[0071]

According to the present invention, by using a melt-spun composite long-fiber nonwoven fabric (so-called spunbonded nonwoven fabric) composed of a water-soluble thermoplastic polyvinyl alcohol and a thermoplastic polymer, it is possible to use chemicals and the like. It is possible to manufacture ultrafine long-fiber non-woven fabric by treating it with water, stabilizing the production of ultra-fine fiber, and improving the quality of the non-woven fabric as a base material. It is now possible to provide leather.

[Brief description of drawings]

FIG. 1 is a fiber cross-sectional view showing an example of a composite form of splittable composite long fibers used in the present invention.

FIG. 2 is a fiber cross-sectional view showing another example of the composite form of the splittable composite long fibers used in the present invention.

[Explanation of symbols]

C Water-soluble thermoplastic polyvinyl alcohol D Thermoplastic polymer

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) D04H 3/14 D04H 3/14 A D06M 11/05 D06M 9/02 C F term (reference) 4F055 AA02 BA12 DA07 DA08 EA04 EA12 EA14 EA24 EA34 EA36 EA38 FA15 GA02 HA22 4L031 AA14 AA16 AA18 AA20 AA22 AB04 AB08 AB12 AB34 BA08 CA15 DA01 DA11 4L041 AA07 BA04 BA05 BA11 BA48 BC03 BD11 CA06 CA44 DD11 EE27 AA4A16 AA4 AA4 AA14 AA4 AA4 AA2 A4 AA2 A4 AA2 A4 A3 A4

Claims (8)

[Claims] 1. The conditions (a) and (b) below, (a)
The long fiber nonwoven fabric (A) is composed of split-type composite long fibers composed of a water-soluble thermoplastic polyvinyl alcohol (C) having a saponification degree of 90 to 99.99 mol% and a thermoplastic polymer (D). Is treated with water to dissolve and remove the water-soluble thermoplastic polyvinyl alcohol (C) constituting the splittable conjugate fiber, which is a non-woven fabric composed of ultrafine long fibers of the thermoplastic polymer (D), ( b) The elastic polymer (B) is impregnated inside the long fiber non-woven fabric (A) which simultaneously satisfies the requirement that the single fiber fineness of the ultrafine long fibers made of the thermoplastic polymer (D) is 0.0005 to 0.5 dtex. Artificial leather characterized by being formed. 2. The long fiber non-woven fabric (A) is a hot embossing method,
The artificial leather according to claim 1, which is joined by using at least one means selected from the group consisting of a water jet method and a needle punch method. 3. A thermoplastic polyvinyl alcohol (C)
Is a modified polyvinyl alcohol containing 0.1 to 15 mol% of an α-olefin unit having 4 or less carbon atoms and / or a vinyl ether unit, The artificial leather according to claim 1 or 2. 4. A thermoplastic polyvinyl alcohol (C)
Is a modified polyvinyl alcohol containing 3 to 15 mol% of ethylene units, The artificial leather according to any one of claims 1 to 3. 5. A thermoplastic polyvinyl alcohol (C)
Is polyvinyl alcohol containing 0.0001 to 0.05 parts by mass of the alkali metal ion (E) in terms of sodium ion based on 100 parts by mass of polyvinyl alcohol (C). The artificial leather described. 6. The polyvinyl alcohol (C) has a pKa at 25 ° C. with respect to the polyvinyl alcohol (C).
Is a polyvinyl alcohol containing an acid (F) having an acid group of 5.0 or less so that α represented by the following formula satisfies 0.01 ≦ α ≦ 1. The artificial leather described. α = {acid (F) content (%) in polyvinyl alcohol} / {alkali metal ion (E) content (%) in polyvinyl alcohol} 7. The thermoplastic polymer (D) is at least one thermoplastic polymer selected from the group consisting of polyesters, polyamides, polyolefins and ethylene-vinyl alcohol copolymers containing 20 to 70 mol% of ethylene units. The artificial leather according to any one of claims 1 to 6. 8. A water-soluble thermoplastic polyvinyl alcohol having a saponification degree of 90 to 99.99 mol% in the production of an artificial leather made of an elastic polymer (B) impregnated in a long fiber nonwoven fabric (A). C) and a step of producing a continuous fiber nonwoven fabric composed of splittable composite continuous fibers composed of a thermoplastic polymer (D), a step of impregnating the elastic polymer (B) inside the continuous fiber nonwoven fabric, the splittable composite Single fiber fineness of long fibers is 0.0005-
A process for producing artificial leather, which comprises performing the step of converting to 0.5 dtex ultrafine long fibers in the order of or.