JP2022048994A - Artificial leather - Google Patents

Abstract

To provide an artificial leather, which is formed of a fiber-entangled body that is mainly formed of ultrafine fiber bundle made of ultrafine fibers and an elastic polymer and excellent in flexibility and has a good touch feeling and graceful surface quality.SOLUTION: An artificial leather contains a fiber-entangled body that is mainly made of ultrafine fiber bundle formed of ultrafine fibers with average single fiber diameter of 0.1 μm or larger and 7.0 μm or less and an elastic polymer. Modification degree of an ultrafine fiber A disposed at outermost peripheral of the ultrafine fiber bundle is 1.5 or higher and 5.0 or less and is larger than the modification degree of an ultrafine fiber B disposed at the section other than the outermost peripheral.SELECTED DRAWING: Figure 1

Description

The present invention relates to artificial leather, which is composed of a fiber entangled body made of ultrafine fibers and a polymer elastic body, has excellent flexibility, has a good touch, and has an elegant surface quality.

Natural leather-like artificial leather, which is mainly composed of an entangled fiber mainly composed of ultrafine fibers and a polymer elastic body, has excellent characteristics in comparison with natural leather such as high durability and uniformity of quality. Therefore, it is used in a wide range of applications such as automobile interior materials, interiors, consumer electronics, and clothing. Above all, when artificial leather is used for automobile interior materials, in addition to excellent mechanical properties, good texture and high-quality surface quality are required.

As for the texture and surface quality of the artificial leather, the higher the fiber density of the fiber entanglement, the finer fibers constituting the fiber entanglement grip the polymer elastic body, and the adhesive portion between the ultrafine fiber and the polymer elastic body. The more it is, the better it tends to be. Therefore, it is common for the fiber entanglement to be a highly entangled and highly dense sheet, and for artificial leather, to increase the adhesive portion between the ultrafine fiber and the polymer elastic body, and to have a flexible texture and excellent surface quality. Is required.

Further, regarding the surface quality of artificial leather, an artificial leather having local brilliance and excellent surface quality by partially deforming the fibers constituting the fiber entanglement has been proposed (for example, Patent Document 1). See.).

Japanese Unexamined Patent Publication No. 2018-178271

In the technique disclosed in Patent Document 1, the deformed cross-section fiber and the non-deformed cross-section fiber are uniformly dispersed in water by a papermaking method to form a sheet, so that fiber lumps and the like are less likely to occur, which is a relatively disadvantage. It is possible to obtain an artificial leather having a certain surface quality with a local brilliance by increasing the light intensity of the reflected light to some extent by containing a small amount of fibers and a deformed cross-sectional fiber. In addition, it is possible to obtain a sheet with relatively high density by entanglement by high-pressure water injection.

However, in the papermaking method as disclosed in Patent Document 1, it is difficult to give the sheet bulkiness, and as a result, it tends to be difficult to attach the polymer elastic body. As a result, there is a problem that the elasticity of the artificial leather is lowered and the artificial leather has a hard texture. Further, since it does not have a fiber bundle, the adhesive structure of the polymer elastic body is between fibers, and as a result, there is a problem that the texture of the obtained artificial leather is hard and the fluff length is shortened.

Therefore, the present invention has been made in view of the above circumstances, and an object thereof is to make the artificial leather made of a fiber entangled body mainly composed of ultrafine fiber bundles composed of ultrafine fibers and a polymer elastic body flexible. It is an object of the present invention to provide artificial leather which is excellent and has a good touch and an elegant surface quality.

As a result of repeated studies by the present inventors to achieve the above object, a polymer elastic body is obtained by setting the ultrafine fibers arranged on the outermost periphery of the ultrafine fiber bundle constituting the fiber entangled body to a specific degree of deformation. It was found that when the polymer elastic body is applied, it becomes difficult for the polymer elastic body to invade the inside of the ultrafine fiber bundle, and an artificial leather in which the adhesive structure of the polymer elastic body is not between the fibers but between the fiber bundles and the fiber bundles can be obtained. did. Furthermore, it has been found that when the artificial leather is brushed, the length of the napped hair becomes long, so that it is possible to obtain an artificial leather having excellent flexibility, a good touch and an elegant surface quality.

The present invention has been completed based on these findings, and according to the present invention, the following inventions are provided.

That is, the artificial leather of the present invention is an artificial leather containing a fiber entangled body mainly composed of ultrafine fiber bundles composed of ultrafine fibers having an average single fiber diameter of 0.1 μm or more and 7.0 μm or less, and a polymer elastic body. The degree of deformation of the ultrafine fibers A arranged on the outermost periphery of the ultrafine fiber bundle is 1.5 or more and 5.0 or less, and is larger than the degree of deformation of the ultrafine fibers B arranged on other than the outermost periphery. ..

According to a preferred embodiment of the artificial leather of the present invention, the single fiber diameter b of the ultrafine fiber B satisfies the following formula (i) with respect to the single fiber diameter a of the ultrafine fiber A 0.5 ≦ a /. b ≦ 1.5 ・ ・ ・ (i).

According to a preferred embodiment of the artificial leather of the present invention, the degree of deformation of the ultrafine fiber B is 1.0 or more and less than 1.5.

According to a preferred embodiment of the artificial leather of the present invention, the variation in the degree of deformation of the ultrafine fiber A is 0.1% or more and 25% or less.

According to a preferred embodiment of the artificial leather of the present invention, the variation in the degree of deformation of the ultrafine fiber B is 0.1% or more and 25% or less.

According to a preferred embodiment of the artificial leather of the present invention, the mass ratio of the polymer elastic body to the artificial leather is 15% by mass or more and 50% by mass or less.

According to a preferred embodiment of the artificial leather of the present invention, the nap length of the artificial leather is 200 μm or more and 500 μm or less.

According to the artificial leather of the present invention, the adhesive structure of the polymer elastic body is obtained by imparting the polymer elastic body to the fiber entangled body mainly composed of the ultrafine fiber bundle in which the ultrafine fibers arranged on the outermost periphery are irregular shapes. It becomes between the fiber bundle and the fiber bundle, and as a result, it is possible to obtain an artificial leather having excellent flexibility and a good touch and an elegant surface quality. Therefore, the artificial leather of the present invention can be widely used from furniture, chairs and vehicle interior materials to clothing applications.

FIG. 1 is a cross-sectional view of an artificial leather illustrating and explaining an ultrafine fiber bundle contained in the artificial leather of the present invention.

The artificial leather of the present invention is an artificial leather containing a fiber entangled body mainly composed of ultrafine fiber bundles composed of ultrafine fibers having an average single fiber diameter of 0.1 μm or more and 7.0 μm or less, and a polymer elastic body. The feature is that the degree of deformation of the ultrafine fiber A arranged on the outermost periphery of the ultrafine fiber bundle is 1.5 or more and 5.0 or less, and is larger than the degree of deformation of the ultrafine fiber B arranged on other than the outermost periphery. It is artificial leather. The components thereof 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.

[Fiber entanglement]
The artificial leather of the present invention contains a fiber entangled body mainly composed of an ultrafine fiber bundle composed of ultrafine fibers as a component. As the type of the ultrafine fiber, synthetic fiber is preferably used from the viewpoint of durability, particularly mechanical strength, heat resistance and the like, and light resistance.

When synthetic fibers are used as the ultrafine fibers, examples of the polymer constituting the ultrafine fibers include polyester, polyamide, polyolefin, acrylic, polyphenylene sulfide and the like. Examples of the polyester include polyethylene terephthalate, polybutylene terephthalate, potitrimethylene terephthalate, polylactic acid and the like. Examples of the polyamide include polyamide 6, polyamide 66, polyamide 610, and polyamide 12. Further, examples of the polyolefin include polyethylene and polypropylene. Of these, polyester is preferably used from the viewpoint of strength, dimensional stability, and heat resistance.

In the present invention, the dicarboxylic acid and / or its ester-forming derivative used in polyester includes 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 these dicarboxylic acids, an acid anhydride, an acyl chloride or the like, and specifically, a methyl ester, an ethyl ester, a hydroxy ethyl ester or the like is 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.

In the present invention, examples of the diol used in polyester include ethylene glycol, 1,3-propanediol, 1,4-butanediol, cyclohexanedimethanol, and the like, and ethylene glycol is preferably used.

When synthetic fibers are used as the ultrafine fibers, the polymers forming the ultrafine fibers include inorganic particles such as titanium oxide particles, lubricants, pigments, heat stabilizers, ultraviolet absorbers, and conductive agents, depending on various purposes. It can contain a heat storage agent, an antibacterial agent, and the like.

In the present invention, the average single fiber diameter of the ultrafine fibers is 0.1 μm or more and 7.0 μm or less. By setting the average single fiber diameter of the ultrafine fibers to 0.1 μm or more, preferably 0.5 μm or more, more preferably 1.0 μm or more, color development after dyeing, light resistance and friction fastness, and stability during spinning are performed. Has an excellent effect on. On the other hand, by setting the thickness to 7.0 μm or less, preferably 6.0 μm or less, more preferably 4.5 μm or less, artificial leather having a fine and soft touch and excellent surface quality can be obtained.

The average single fiber diameter of the ultrafine fibers shall be calculated by the following method.
(1) Take a scanning electron microscope (SEM) photograph of the cross section of the artificial leather, and randomly select 10 oval ultrafine fibers that are circular or close to circular.
(2) Measure the diameter of a single fiber, calculate the arithmetic mean value of 10 fibers, and round off to the second decimal place.
(However, when ultrafine fibers with a modified cross section are used, the diameter of the single fiber shall be obtained by first measuring the cross-sectional area of the single fiber and calculating the diameter when the cross section is regarded as a circle. )
Further, the fiber entanglement of the present invention is mainly composed of an ultrafine fiber bundle made of the ultrafine fibers. In the present invention, the "ultrafine fiber bundle" composed of ultrafine fibers is an aggregate of a plurality of ultrafine fibers that can be regarded as facing the same direction, and when the cross section of artificial leather is observed by SEM at an arbitrary magnification. In addition, it refers to an aggregate of ultrafine fibers surrounded by a circle having a fiber bundle deformation degree of 1.5 or less. Here, as shown in FIG. 1, the “fiber bundle deformity” means that a line (1) surrounding an aggregate of ultrafine fibers is drawn on the SEM image so as to follow the aggregate, and the outer circumference thereof is drawn. It shall refer to the value obtained by dividing the diameter of the circumscribed circle of the line (1) surrounding the outer circumference by the diameter of the inscribed circle of the line surrounding the outer circumference.

As for the cross-sectional shape of the ultrafine fibers, it is important that the degree of deformation of the ultrafine fibers A arranged on the outermost periphery of the ultrafine fiber bundle is 1.5 or more and 5.0 or less. By setting the degree of deformation of the ultrafine fiber A to 1.5 or more, more preferably 1.6 or more, still more preferably 1.8 or more, the polymer elastic body is less likely to penetrate into the ultrafine fiber bundle, resulting in a result. The artificial leather to be made is flexible and has a long standing hair length. Further, by setting the degree of deformation of the ultrafine fiber A to 5.0 or less, more preferably 4.0 or less, still more preferably 3.0 or less, artificial leather having sufficient strength can be obtained. In the present invention, the "ultrafine fiber A" arranged on the outermost circumference of the ultrafine fiber bundle is a line surrounding the outer periphery along the aggregate of the ultrafine fibers drawn when calculating the degree of deformation of the fiber bundle. It shall refer to the ultrafine fibers that are in contact with each other. Further, the degree of deformation of the ultrafine fiber A shall be calculated by the following method.
(1) Take an SEM photograph of the cross section of artificial leather and randomly select 5 ultrafine fiber bundles.
(2) Draw an circumscribed circle and an inscribed circle for the cross section of the ultrafine fiber A contained in the selected five ultrafine fiber bundles, and divide the circumscribed circle diameter by the inscribed circle diameter.
(3) Calculate the arithmetic mean value for the divided value and round it to the second decimal place.

Further, the variation in the degree of deformation of the ultrafine fiber A is preferably 0.1% or more and 25% or less. By setting the variation in the degree of deformation of the ultrafine fiber A to 0.1% or more, 25% or less, more preferably 20% or less, still more preferably 15% or less, artificial leather having an elegant surface quality can be obtained.

Further, it is preferable that the degree of deformation of the ultrafine fibers B arranged outside the outermost periphery of the ultrafine fiber bundle is 1.0 or more and less than 1.5. When the degree of deformation of the ultrafine fiber B is 1.0 or more, more preferably 1.1 or more, or less than 1.5, more preferably 1.4 or less, the bending hardness of the ultrafine fiber itself does not increase, and it is artificial. The fineness of the leather can be maintained. In the present invention, the "ultrafine fiber B" arranged outside the outermost periphery of the ultrafine fiber bundle refers to the ultrafine fiber surrounded by the ultrafine fiber A among the ultrafine fiber bundles. The degree of deformation of the ultrafine fiber B can be obtained by the same method as the above-mentioned method for calculating the degree of deformation of the ultrafine fiber A.

Further, the variation in the degree of deformation of the ultrafine fiber B is preferably 0.1% or more and 25% or less. By setting the variation in the degree of deformation of the ultrafine fiber B to 0.1% or more, 25% or less, more preferably 20% or less, still more preferably 15% or less, artificial leather having an elegant surface quality can be obtained.

Further, in the present invention, it is preferable that the single fiber diameter b of the ultrafine fiber B satisfies the following formula with respect to the single fiber diameter a of the ultrafine fiber A. i)
By satisfying this formula, it is possible to obtain artificial leather in which the polymer elastic body does not easily invade the inside of the ultrafine fiber bundle and has higher density. The single fiber diameter a of the ultrafine fiber A and the single fiber diameter b of the ultrafine fiber B shall be calculated by the following method.
(1) Take an SEM photograph of the cross section of artificial leather and randomly select 5 ultrafine fiber bundles.
(2) For each of the ultrafine fibers A and B contained in the five selected ultrafine fiber bundles, the cross-sectional area of the single fiber is measured, and the single fiber diameters a and b when the cross section is regarded as a circle are calculated. do.
(3) Calculate the arithmetic mean value for each of the calculated single fiber diameters a and b, and round off to the second decimal place.

The artificial leather of the present invention is in the form of a fiber entangled body mainly composed of the ultrafine fiber bundle composed of the above-mentioned ultrafine fibers, so that when the surface is raised by the method described later, a uniform and graceful appearance and texture are obtained. Can be obtained.

As the form of fiber entanglement, short fiber entanglement obtained by forming a laminated fiber web of short fibers using a card or cross wrapper and then applying needle punch or water jet punch, spunbond method, melt blow method, etc. There are long fiber entanglements obtained from, and entanglements obtained by the papermaking method. When the base material of the fiber layer constituting the artificial leather is a long fiber entangled body, it is preferable because the artificial leather having excellent strength can be obtained. On the other hand, in the case of the short fiber entanglement, the number of fibers oriented in the thickness direction of the artificial leather can be increased as compared with the case of the long fiber entanglement or the entanglement obtained by the papermaking method, and when the artificial leather is raised. It is possible to give a high degree of fineness to the surface of the artificial leather. Further, it is preferably used because a product having good thickness uniformity and the like can be obtained.

When the staple fiber entanglement is used, the fiber length of the ultrafine fibers is preferably 25 mm or more and 90 mm or less. By setting the fiber length of the ultrafine fibers 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 obtained. Further, by setting the fiber length of the ultrafine fibers to 90 mm or less, more preferably 80 mm or less, still more preferably 70 mm or less, artificial leather having good surface quality and texture can be obtained.

The texture of the fiber entangled body constituting the artificial leather according to the present invention is measured by "6.2 Mass per unit area (ISO method)" of JIS L1913: 2010 "General non-woven fabric test method", and is 50 g / m ² or more. It is preferably 800 g / m ² or less. By setting the basis weight of the fiber entangled body to 50 g / m ² or more, more preferably 80 g / m ² or more, it is possible to obtain artificial leather with a full feeling and excellent texture. Further, by setting the basis weight of the fiber entangled body to 800 g / m ² or less, more preferably 700 g / m ² or less, it is possible to obtain a flexible artificial leather having excellent moldability.

[Polymer elastic body]
The polymer elastic body constituting the artificial leather of the present invention indicates a polymer compound having rubber elasticity at room temperature. The binder effect of the polymer elastic body not only prevents the ultrafine fibers from falling out of the artificial leather, but also makes it possible to impart appropriate cushioning properties.

Examples of the polymer elastic body include polyurethane, acrylonitrile-butadiene rubber (NBR), styrene-butadiene rubber (SBR), ethylene-vinyl acetate resin, acrylic resin, etc., from the viewpoint of a fulfilling feel and durability. Polyurethane is preferably used. The polymer elastic body may contain a plurality of polymer elastic bodies.

In the present invention, when polyurethane is used as the polymer elastic body, both the organic solvent-based polyurethane used in a state of being dissolved in an organic solvent and the water-dispersed polyurethane used in a state of being dispersed in water can be adopted. can.

When an organic solvent-based polyurethane is used, its weight average molecular weight is preferably 50,000 or more and 500,000 or less. By setting the weight average molecular weight to 50,000 or more, more preferably 100,000 or more, still more preferably 150,000 or more, the strength of the artificial leather can be maintained and the composite fibers can be prevented from falling off. Further, by setting the weight average molecular weight to 500,000 or less, more preferably 400,000 or less, still more preferably 300,000 or less, it is possible to suppress an increase in viscosity of the polyurethane solution and facilitate impregnation into the fiber entanglement.

When water-dispersed polyurethane is used, its number average molecular weight is preferably 20,000 or more and 500,000 or less. By setting the number average molecular weight to 20,000 or more, more preferably 30,000 or more, the strength of polyurethane can be increased. Further, by setting the number average molecular weight to 500,000 or less, more preferably 300,000 or less, the viscosity stability of the polyurethane solution can be improved and the workability can be improved.

As the above-mentioned polyurethane, polyurethane obtained by reacting a polymer diol with an organic diisocyanate and a chain extender is preferably used.

As the polymer diol when polyurethane is used as the polymer elastic body, for example, a polycarbonate-based diol, a polyester-based diol, a polyether-based diol, a silicone-based diol, and a fluoro-based diol can be adopted, and the copolymer weight obtained by combining these can be adopted. Coalescence can also be used. Above all, from the viewpoint of hydrolysis resistance, it is preferable to use a polycarbonate-based diol and a polyether-based diol.

The above-mentioned polycarbonate-based diol can be produced by a transesterification reaction of an alkylene glycol with a carbonic acid ester, a reaction of a phosgen or a chloraterate with an alkylene glycol, or the like.

Examples of the alkylene glycol include ethylene glycol, propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,9-nonanediol, and 1,10-decanediol. Chain alkylene glycols, branched alkylene glycols such as neopentyl glycols, 3-methyl-1,5-pentanediol, 2,4-diethyl-1,5-pentanediol and 2-methyl-1,8-octanediol, 1 , Alicyclic diols such as 4-cyclohexanediol, aromatic diols such as bisphenol A, glycerin, trimethylolpropane, pentaerythritol and the like. In the present invention, either a polycarbonate-based diol obtained from a single alkylene glycol or a copolymerized polycarbonate-based diol obtained from two or more types of alkylene glycol can be adopted.

Examples of the polyester-based diol include polyester diols obtained by condensing various low molecular weight polyols with polybasic acids.

Examples of the low molecular weight polyol include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,3-butanediol, 1,4-butanediol, and 2,2-dimethyl-1,3-propane. Diol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 1,8-octanediol, diethylene glycol, triethylene glycol, dipropylene glycol, tripropylene glycol, cyclohexane-1,4-diol, and One or more selected from cyclohexane-1,4-dimethanol can be used. Further, an adduct obtained by adding various alkylene oxides to bisphenol A can also be used.

Examples of the polybasic acid include succinic acid, maleic acid, adipic acid, glutaric acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, dodecandicarboxylic acid, phthalic acid, isophthalic acid, terephthalic acid, and hexahydro. One or more selected from isophthalic acid can be mentioned.

Examples of the polyether diol include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and a copolymer diol in which they are combined.

The number average molecular weight of the polymer diol used in the present invention is preferably 500 or more and 5000 or less. By setting the number average molecular weight to 500 or more, more preferably 1500 or more, it is possible to prevent the artificial leather from hardening. Further, by setting the number average molecular weight to 5000 or less, more preferably 4000 or less, the strength as polyurethane can be maintained.

Examples of the organic diisocyanate when polyurethane is used as the polymer elastic body include aliphatic diisocyanates such as hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, isophorone diisocyanate, and xylylene diisocyanate, and aromatics such as diphenylmethane diisocyanate and tolylene diisocyanate. Examples thereof include system diisocyanates, and these can also be used in combination. Among them, aromatic diisocyanates such as 4,4'-diphenylmethane diisocyanate are preferable when durability and heat resistance are important, and hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, isophorone diisocyanate and the like are preferable when light resistance is important. The aliphatic diisocyanate of the above is preferably used.

When polyurethane is used as the polymer elastic body, examples of the chain extender include water, ethylene glycol, propylene glycol, 1,3-butylene glycol, 1,4-butanediol, 1,6-hexanediol, diethylene glycol and the like. 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, aliphatic diamines such as ethylenediamine, and isophorone. Examples thereof include alicyclic diamines such as diamines, aromatic diamines such as 4,4-diaminodiphenylmethane, aromatic aliphatic diamines such as xylenediamine, alkanolamines such as ethanolamine, hydrazines and dihydrazides such as adipic acid dihydrazide. These can also be used in combination. Among them, more preferable chain extenders are water, low molecular weight diols and aromatic diamines, and more preferably water, ethylene glycol, 1,4-butanediol, 4,4'-diaminodiphenylmethane and two or more of these. Examples include mixtures.

When water-dispersed polyurethane is used in the present invention, it is preferable to use an internal emulsifier in order to disperse the polyurethane in water. Examples of the internal emulsifier include a cationic internal emulsifier such as a quaternary amine salt, an anionic internal emulsifier such as a sulfonate and a carboxylate, and a nonionic internal emulsifier such as polyethylene glycol, and further, a cationic internal emulsifier. Any combination of an anionic and nonionic internal emulsifiers and a combination of anionic and nonionic internal emulsifiers can be adopted. Among them, the nonionic internal emulsifier is preferably used because it has excellent light resistance as compared with the cationic internal emulsifier and is not adversely affected by the neutralizing agent as compared with the anionic internal emulsifier.

The polymer elastic body used in the present invention can be used in combination with a cross-linking agent for the purpose of improving water resistance, wear resistance, hydrolysis resistance and the like. The cross-linking agent may be an external cross-linking agent added as a third component to the polymer elastic body, or an internal cross-linking agent that previously introduces a reaction point having a cross-linking structure into the molecular structure of the polymer elastic body may be used. can. It is preferable to use an internal cross-linking agent from the viewpoint that cross-linking points can be formed more uniformly in the molecular structure of the polymer elastic body and the decrease in flexibility can be reduced.

As the cross-linking agent, a compound having an isocyanate group, an oxazoline group, a carbodiimide group, an epoxy group, a melamine resin, a silanol group and the like can be used.

In addition, various additives such as pigments such as carbon black, flame retardants such as phosphorus-based, halogen-based and inorganic-based, and oxidation of phenol-based, sulfur-based and phosphorus-based substances are added to the polymer elastic body depending on the purpose. Inhibitors, benzotriazole-based, benzophenone-based, salicylate-based, cyanoacrylate-based and oxalic acid-anilide-based UV absorbers, hindered amine-based and benzoate-based light stabilizers, hydrolysis-resistant stabilizers such as polycarbodiimide, etc. It can contain plasticizers, antistatic agents, surfactants, coagulation modifiers, dyes and the like.

Generally, the content of the polymer elastic body in the artificial leather can be appropriately adjusted in consideration of the type of the polymer elastic body to be used, the method for producing the polymer elastic body, and the texture and physical properties. The content of the polymer elastic body is preferably 15% by mass or more and 50% by mass or less with respect to the mass of the artificial leather. By setting the content of the polymer elastic body to 15% by mass or more, more preferably 20% by mass or more, it is possible to strengthen the bond between the fibers by the polymer elastic body and improve the wear resistance of the artificial leather. Can be made to. On the other hand, by setting the content of the polymer elastic body to 50% by mass or less, more preferably 45% by mass or less, the artificial leather can be made more flexible.

[Artificial leather]
In the artificial leather of the present invention, it is a preferable aspect to have fluff on the surface. The fluff may be held only on the surface of the artificial leather, and it is permissible to have it on both sides. From the viewpoint of the design effect, the fluff morphology when the surface has fluff has a fluff length and directional flexibility to the extent that a so-called finger mark is generated, which leaves a mark when the direction of the fluff changes when traced with a finger. Is preferable.

More specifically, the fluff length on the surface is preferably 200 μm or more and 500 μm or less. By setting the nap length to 200 μm or more, more preferably 250 μm or more, a voluminous feeling and a design effect can be obtained. Further, by setting the fluff length to 500 μm or less, more preferably 450 μm or less, artificial leather having excellent wear resistance can be obtained, and deterioration of surface quality due to entanglement of ultrafine fibers can be suppressed.

In the present invention, the fluff length of artificial leather shall be calculated by the following method.
(1) Using a lint brush or the like, in a state where the fluff of the artificial leather is turned upside down, a thin section having a thickness of 1 mm is prepared in the cross-sectional direction of the surface perpendicular to the longitudinal direction of the artificial leather.
(2) An SEM photograph of the cross section of the artificial leather is taken, and the height of the napped portion (layer consisting only of ultrafine fibers) is measured at 10 points at intervals of 200 μm in the cross section width direction.
(3) Arithmetic mean values are calculated for the measured heights of the naps at 10 points.

The artificial leather of the present invention has a grain size of 100 g / m ² or more and 500 g / m ² or less as measured by 6.2 “Mass per unit area (ISO method)” of JIS L1913: 2010 “General non-woven fabric test method”. Is preferable. By setting the basis weight of the artificial leather to 100 g / m ² or more, more preferably 150 g / m ² or more, it becomes easy to obtain sufficient morphological stability and dimensional stability for the artificial leather. Further, by setting the basis weight of the artificial leather to 500 g / m ² or less, more preferably 400 g / m ² or less, sufficient flexibility and texture can be obtained.

Further, the artificial leather of the present invention has a thickness of 0.2 mm measured by "6.1.1 A method" of "6.1 thickness (ISO method)" of JIS L1913: 2010 "general nonwoven fabric test method". It is preferably 1.2 mm or more and preferably 1.2 mm or less. By setting the thickness of the artificial leather to 0.2 mm or more, more preferably 0.3 mm or more, and further preferably 0.4 mm or more, not only the workability at the time of manufacturing is excellent, but also the texture is excellent. It becomes a thing. Further, by setting the thickness of the artificial leather to 1.2 mm or less, more preferably 1.1 mm or less, still more preferably 1.0 mm or less, it is possible to obtain a flexible artificial leather having excellent moldability.

Further, the artificial leather of the present invention is the "8.19.5 E method (Martindale method)" of "8.19 Abrasion strength and frictional discoloration" of JIS L1096: 2010 "Fabric test method of woven fabric and knitted fabric". In the abrasion resistance test measured in, the pressing load is 12.0 kPa, and the mass loss of the artificial leather after being worn 20000 times is preferably 10 mg or less, more preferably 8 mg or less, and 6 mg. The following is more preferable. When the mass reduction is 10 mg or less, it is possible to prevent contamination due to fluffing during actual use.

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

With respect to the artificial leather according to the present invention, it is a preferable embodiment to use ultrafine fiber-expressing fibers as a means for obtaining a fiber entangled body mainly composed of the ultrafine fiber bundle composed of the above-mentioned ultrafine fibers. By preliminarily entwining the ultrafine fiber-expressing type fibers to form a fiber entangled body and then performing the ultrafine fiber, it is possible to easily obtain a fiber entangled body in which the ultrafine fiber bundles are entangled.

As the ultrafine fiber-expressing type fiber, two components of thermoplastic resins having different solvent solubility are used as a sea component and an island component, and the sea component is dissolved and removed using a solvent or the like to obtain an island component as an ultrafine fiber. It is possible to adopt a Kaishima-type composite fiber or a peel-type composite fiber in which two-component thermoplastic resin is alternately arranged radially or in a multilayer shape on the fiber cross section, and each component is split and split into ultrafine fibers. can.

For the sea-island type composite fiber, a method using a sea-island type composite base and a polymer mutual arrangement in which two components of the sea component and the island component are mutually arranged and spun, and a method of mixing the two components of the sea component and the island component are mixed. There is a mixed spinning method in which the fibers are spun in a mixed manner, but from the viewpoint of obtaining ultrafine fibers having a uniform single fiber fineness, a sea-island type composite fiber by a method using a polymer mutual arrangement is preferable.

The ultrafine fiber bundle used in the artificial leather of the present invention is, for example, a measuring plate having a plurality of measuring holes for measuring a polymer flow of a sea island component and a plurality of measuring plates as described in Japanese Patent Application Laid-Open No. 2011-174215. It can be obtained by using a composite spinneret capable of forming various cross-sectional shapes by combining a distribution plate having a plurality of distribution holes in a confluence groove for merging the polymer flow discharged from the measuring holes.

The ratio of the sea component to the island component of the sea-island type composite fiber is preferably 20% or more and 90% or less in terms of the mass ratio of the island component to the sea-island type composite fiber. By setting the mass ratio of the island component to 20% or more, more preferably 30% or more, the removal rate of the sea component can be reduced and the productivity is further improved. Further, by setting the mass ratio of the island components to 90% or less, more preferably 85% or less, it is possible to prevent the island components from merging and suppress the deterioration of the surface quality.

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, polystyrene and copolymerized polyester are preferably used.

When a copolymerized polyester is used, a copolymerized polyester obtained by copolymerizing 3 mol% or more and 15 mol% or less of sodium 5-sulfoisophthalate is preferable. Sufficient alkali elution can be obtained by copolymerizing the sodium 5-sulfoisophthalate component in an amount of 3 mol% or more. Further, when the copolymerization amount of the sodium 5-sulfoisophthalate component is 15 mol% or less, the thickening of the polyester is suppressed and the yarn breakage at the time of spinning the composite fiber is less likely to occur. More preferably, it is in the range of 7 mol% or more and 13 mol% or less.

Further, the sea component and the island component constituting the sea-island type composite fiber include inorganic particles such as titanium oxide particles, a lubricant, a heat stabilizer, and ultraviolet absorption according to various purposes and within a range that does not impair the object of the present invention. Agents, conductive agents, heat storage agents, antibacterial agents and the like can be added.

When the sea-island type composite fiber is used in the method for producing artificial leather of the present invention, the strength of the island component is preferably 2.5 cN / dtex or more. By setting the strength of the island component to 2.5 cN / dtex or more, more preferably 2.8 cN / dtex or more, still more preferably 3.0 cN / dtex or more, the abrasion resistance of the artificial leather can be improved.

In the present invention, the strength of the island component of the sea-island type composite fiber shall be calculated by the following method.
(1) Bundle 10 sea-island type composite fibers with a length of 20 cm.
(2) After dissolving and removing the sea component from the sample of (1), it is air-dried.
(3) Grasp length 5 cm, tensile speed 5 cm / min in "8.5.1 Standard time test" of "8.5 Tensile strength and elongation" of JIS L1013: 2010 "Chemical fiber filament yarn test method". , Test 10 times under the condition of load 2N.
(4) The value obtained by rounding off the arithmetic mean value (cN / dtex) of the test results obtained in (3) to the second decimal place is taken as the strength of the island component constituting the sea-island type composite fiber.

The fiber entangled body constituting the artificial leather of the present invention can be obtained by opening the spun ultrafine fiber-expressing fiber, forming a fiber web with a cloth wrapper or the like, and entwining the fiber web. As a method of entwining the fiber webs to obtain a fiber entangled body, a needle punching process, a water jet punching process, or the like can be used.

As the form of the fiber entanglement, either the short fiber entanglement or the long fiber entanglement can be used as described above, but in the case of the short fiber entanglement, the fibers oriented in the thickness direction of the artificial leather are the long fiber entanglement. It is more than coalesced, and a high degree of fineness can be obtained on the surface of the artificial leather when it is raised.

In the case of staple entanglement, the obtained ultrafine fiber phenotype fiber is preferably crimped, cut to a predetermined length to obtain raw cotton, and then opened, laminated and entangled. This gives a staple entanglement. A known method can be used for the crimping process and the cutting process.

In the needle used for the needle punching process, the number of needle barbs (cutting) is preferably 1 to 9. By preferably using one or more needle barbs, efficient fiber entanglement is possible. Further, by setting the number of needle barbs to preferably 9 or less, fiber damage can be suppressed.

The number of ultrafine fiber-expressing fibers caught in the barb is determined by the shape of the barb and the diameter of the ultrafine fiber-expressing fiber. Therefore, the barb shape of the needle used in the needle punching process has a kick-up of 0-50 μm, an undercut angle of 0-40 °, a throat depth of 40-80 μm, and a slow length of 0.5. The one having a thickness of about 1.0 mm is preferably used.

The number of punches is preferably 1000 to 8000 / cm ² . By setting the number of punching lines to preferably 1000 lines / cm ² or more, a fine fiber entanglement can be obtained. Further, by setting the number of punches to preferably 8000 / cm ² or less, deterioration of workability, fiber damage and strength deterioration can be prevented.

Further, when the water jet punching treatment is performed, it is preferable that the water is performed in a columnar flow state. Specifically, it is preferable to eject water from a nozzle having a diameter of 0.05 mm or more and 1.0 mm or less at a pressure of 2 MPa or more and 60 MPa or less.

The apparent density of the fiber entangled body made of the ultrafine fiber-expressing fiber 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, the artificial leather can obtain sufficient morphological stability and dimensional stability. Further, 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 body.

It is also a preferable embodiment that the fiber entangled body is subjected to a heat shrinkage treatment with warm water or steam in order to improve the denseness of the fibers.

Next, the water-soluble resin can be imparted by impregnating the fiber entanglement with an aqueous solution of the water-soluble resin and drying it. By applying the water-soluble resin to the fiber entanglement, the fibers are fixed and the dimensional stability is improved.

Subsequently, the obtained fiber entanglement is treated with a solvent to develop ultrafine fibers having an average single fiber diameter of 0.1 μm or more and 7.0 μm or less.

The expression treatment of the ultrafine fibers can be performed by immersing a fiber entanglement composed of the ultrafine fiber expression type fibers in a solvent to dissolve and remove the sea component of the ultrafine fiber expression type fibers.

When the ultrafine fiber-expressing fiber is a sea-island type composite fiber, an organic solvent such as toluene or trichlorethylene can be used as the solvent for dissolving and removing the sea component when the sea component is polyethylene, polypropylene or polystyrene. When the sea component is a copolymerized polyester or polylactic acid, an alkaline aqueous solution such as sodium hydroxide can be used. Further, when the sea component is a water-soluble thermoplastic polyvinyl alcohol-based resin, hot water can be used.

Further, after impregnating the fiber entanglement composed of the ultrafine fiber-expressing fiber with the polymer elastic solution (that is, before dissolving and removing the sea component of the ultrafine fiber-expressing fiber), the polymer elastic solution is applied. After impregnation) or after impregnating a fiber entanglement consisting of ultrafine fibers from which the sea component of the ultrafine fiber-expressing fiber has been dissolved and removed with a solution of a polymer elastic body (that is, after impregnating the ultrafine fiber-expressing fiber). After the sea component is dissolved and removed to form a fiber entangled body made of ultrafine fibers and then impregnated with a solution of the polymer elastic body), the polymer elastic body is imparted by solidification. As a method of fixing the polymer elastic body to the fiber entanglement, a wet coagulation method in which the fiber entanglement is impregnated with a solution of the polymer elastic body and then immersed in a coagulation bath to fix the polymer elastic body, or a wet coagulation method of drying and fixing the polymer elastic body. There are dry coagulation methods, and these methods can be appropriately selected depending on the type of polymer elastic body to be applied.

As the solvent used for imparting polyurethane as a polymer elastic body, N, N'-dimethylformamide, dimethyl sulfoxide and the like are preferably used. Further, an aqueous dispersion type polyurethane liquid in which polyurethane is dispersed as an emulsion in water may be used.

The sheet-like material that has completed the above steps may be used as it is as artificial leather, but from the viewpoint of improving manufacturing efficiency, it is also preferable to cut it in half in the thickness direction to form two sheet-like materials and use it as artificial leather. be.

Further, the surface of the sheet-like material to which the polymer elastic body is applied or the sheet-like material to which the half-cut polymer elastic material is applied can be brushed to obtain artificial leather. The raising treatment can be performed by a method of grinding using sandpaper, a roll sander, or the like. The raising treatment can be applied to only one surface of the sheet-like material or to both sides.

When the above-mentioned raising treatment is applied, a lubricant such as a silicone emulsion can be applied to the surface of the sheet-like material before the raising treatment. Further, by applying an antistatic agent before the raising treatment, the grinding powder generated from the sheet-like material by grinding is less likely to be deposited on the sandpaper.

Further, it is also preferable to dye the sheet-like material to obtain artificial leather. The dyeing process includes, for example, a liquid flow dyeing process using a jigger dyeing machine or a liquid flow dyeing machine, a dip dyeing process such as a thermosol dyeing process using a continuous dyeing machine, or roller printing, screen printing, inkjet printing, and sublimation. It is possible to use a printing treatment on a napped surface by printing, vacuum sublimation printing, or the like. Above all, it is preferable to use a liquid flow dyeing machine from the viewpoint of quality and quality as well as obtaining a flexible texture. Further, if necessary, various resin finishing processes can be applied after dyeing.

In addition, the sheet-like material may be made into artificial leather by applying a design property to the surface thereof according to a desired embodiment. For example, post-processing such as perforation and other drilling, embossing, laser processing, pinsonic processing, and printing can be performed.

The artificial leather of the present invention obtained by the above-exemplified manufacturing method has excellent flexibility, a good touch, and an elegant surface quality, and is therefore widely used, for example, from furniture, chairs, vehicle interior materials, and clothing applications. be able to.

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. Next, the evaluation method used in the examples and the measurement conditions thereof will be described. However, in the measurement of each physical property, if there is no particular description, the measurement is performed based on the above method.

[Measurement method and processing method for evaluation]
A. Average single fiber diameter of ultrafine fibers:
In the measurement of the average single fiber diameter of the ultrafine fiber, the ultrafine fiber was observed using a digital microscope "VW-9000 type" manufactured by KEYENCE CORPORATION, and the average single fiber diameter was calculated.

B. Deformity of ultrafine fibers A and B:
For the cross-sectional image of the artificial leather, the cross-sectional image of the artificial leather was imaged using a digital microscope "VW-9000 type" manufactured by KEYENCE CORPORATION, and the degree of deformation of the ultrafine fibers A and B was calculated.

C. Fleece length of artificial leather:
In the measurement of the nap length of the artificial leather, the cross section of the artificial leather was imaged using a digital microscope "VW-9000 type" manufactured by KEYENCE CORPORATION, and the nap length was calculated.

D. Texture of artificial leather:
A total of 20 people, 10 healthy adult men and 10 adult women, were evaluated as follows by sensory evaluation, and the most common evaluation was the texture of artificial leather. If the evaluations were the same, the higher evaluation was decided to be the texture of the artificial leather. A good level in the present invention is "A or B".
・ A: Flexible and good texture ・ B: Slightly flexible and good texture ・ C: Slightly hard and poor texture ・ D: Strong and poor texture.

E. Surface quality of artificial leather:
A total of 20 people, 10 healthy adult men and 10 adult women, were evaluated as follows by sensory evaluation, and the most common evaluation was the surface grade of artificial leather. If the evaluations were the same, the higher evaluation was decided to be the surface quality of the artificial leather. A good level in the present invention is "A or B".
-A: Very good surface quality-B: Good surface quality-C: Poor surface quality-D: Very poor surface quality.

[Example 1]
First, the sea-island type composite fiber was melt-spun under the following conditions.
-Island component polymer: Polyethylene terephthalate (PET) with an intrinsic viscosity (IV value) of 0.72
-Sea component polymer: Polystyrene with MFR (melt flow rate, measured by the test method specified in ISO 1133: 1997) of 65 g / 10 minutes-Cap: 16 islands / hole sea-island type composite base-Spinning temperature: 285 ° C
・ Shimabe / Umibe mass ratio: 80/20
・ Discharge rate: 1.2 g / (minutes / holes)
-Spinning speed: 1100 m / min Next, the obtained Kaishima-type composite fiber was stretched 2.7 times, crimped using a push-in crimping machine, and then cut to a length of 51 mm to make a single fiber. Raw cotton of Kaishima composite fiber with a fineness of 4.2 dtex was obtained. The average single fiber diameter of the ultrafine fibers obtained from this sea-island composite fiber was 4.4 μm.

Using the raw cotton obtained as described above, a laminated web was formed through a card and cross wrapper process. Then, a needle punching process was performed with a punching number of 2500 lines / cm ² to obtain a fiber entangled body having a basis weight of 540 g / m ² and a thickness of 2.4 mm.

The fiber entanglement obtained as described above was shrink-treated with hot water at 98 ° C. Then, an aqueous solution of polyvinyl alcohol (PVA) having a saponification degree of 88%, which was prepared to have a concentration of 12% by mass, was impregnated into a fiber entanglement body which had been shrink-treated with hot water. Further, this was squeezed with a roll and dried while migrating PVA with hot air at a temperature of 120 ° C. for 10 minutes to obtain a sheet with PVA so that the mass of PVA was 25% by mass with respect to the mass of the sheet substrate. The sheet with PVA thus obtained was immersed in trichlorethylene, and squeezed and compressed with a mangle 10 times. As a result, the sea portion was dissolved and removed, and the sheet with PVA was compressed to obtain a sheet with PVA in which ultrafine fiber bundles to which PVA was added were entangled.

A polyurethane dimethylformamide (hereinafter, may be abbreviated as DMF) solution prepared so that the concentration of the solid content containing polyurethane as a main component is 13% is applied to the sheet with PVA obtained as described above. Soaked. Then, the sheet with desea PVA immersed in the DMF solution of polyurethane was squeezed with a roll. Next, this sheet was immersed in a DMF aqueous solution having a concentration of 30% by mass to solidify the polyurethane. Then, PVA and DMF were removed with hot water and dried with hot air at a temperature of 110 ° C. for 10 minutes to obtain a sheet with polyurethane having a thickness of 1.8 mm.

The polyurethane-attached sheet obtained through each of the above steps was cut in half so that the thickness was halved. The surface layer portion of the semi-cut surface was ground by 0.3 mm with endless sandpaper having a sandpaper count of 180 and raised to obtain a raised sheet having a thickness of 0.6 mm.

The fluff sheet obtained as described above was dyed with a liquid flow dyeing machine under the condition of 120 ° C. and then dried with a dryer, and the average single fiber diameter of the ultrafine fibers was 4.4 μm. An artificial leather having a degree of deformation of the ultrafine fiber A of 2.0, a degree of deformation of the ultrafine fiber B of 1.3, a mass ratio of polyurethane to 30% by mass in the artificial leather, and a fluff length of 330 μm was obtained. The obtained artificial leather had excellent flexibility and texture, and had a good touch and an elegant surface quality. The results are shown in Table 1.

[Example 2]
Artificial leather was obtained in the same manner as in Example 1 except that the degree of deformation of the ultrafine fibers A arranged on the outermost periphery of the ultrafine fiber bundle was set to 3.0. The obtained artificial leather had excellent flexibility and texture, and had a good touch and an elegant surface quality. The results are shown in Table 1.

[Example 3]
Artificial leather was obtained in the same manner as in Example 1 except that the degree of deformation of the ultrafine fibers A arranged on the outermost periphery of the ultrafine fiber bundle was set to 1.5. The obtained artificial leather had excellent flexibility and texture, and had a good touch and an elegant surface quality. The results are shown in Table 1.

[Example 4]
Artificial leather was obtained in the same manner as in Example 1 except that the single fiber diameter a of the ultrafine fiber A and the single fiber diameter b of the ultrafine fiber B were set to a / b = 0.4. The obtained artificial leather had a graceful surface quality, although the flexibility and texture were slightly inferior to those of the artificial leather of Example 1. The results are shown in Table 1.

[Example 5]
Artificial leather was obtained in the same manner as in Example 1 except that the degree of deformation of the ultrafine fibers B arranged outside the outermost periphery of the ultrafine fiber bundle was set to 1.5. The obtained artificial leather had a graceful surface quality, although the flexibility and texture were slightly inferior to those of the artificial leather of Example 1. The results are shown in Table 1.

[Example 6]
Artificial leather was obtained in the same manner as in Example 1 except that the variation in the degree of deformation of the ultrafine fibers A arranged on the outermost periphery of the ultrafine fiber bundle was set to 30%. The obtained artificial leather had a good flexibility and texture, although the surface quality was slightly inferior to that of the artificial leather of Example 1. The results are shown in Table 1.

[Example 7]
Artificial leather was obtained in the same manner as in Example 1 except that the variation in the degree of deformation of the ultrafine fibers B arranged outside the outermost periphery of the ultrafine fiber bundle was set to 30%. The obtained artificial leather had a good flexibility and texture, although the surface quality was slightly inferior to that of the artificial leather of Example 1. The results are shown in Table 1.

[Example 8]
An artificial leather was obtained in the same manner as in Example 1 except that the mass ratio of polyurethane to the artificial leather was 10%. The obtained artificial leather had a graceful surface quality, although the flexibility and texture were slightly inferior to those of the artificial leather of Example 1. The results are shown in Table 1.

[Example 9]
An artificial leather was obtained in the same manner as in Example 1 except that the nap length of the artificial leather was 190 mm. The obtained artificial leather had a good flexibility and texture, although the surface quality was slightly inferior to that of the artificial leather of Example 1. The results are shown in Table 1.

[Example 10]
Kaishima-type composite fibers were melt-spun under the following conditions.
-Island component polymer: Same as Example 1-Sea component polymer: Copolymerized PET obtained by copolymerizing 8 mol% of 5-sodium sulfoisophthalate.
・ Cap: 16 islands / hole sea island type composite cap ・ Spinning temperature: 285 ℃
・ Shimabe / Umibe mass ratio: 80/20
・ Discharge rate: 1.6 g / (minutes / holes)
-Spinning speed: 1100 m / min Next, the obtained Kaishima-type composite fiber was stretched 3.8 times, crimped using a push-in crimping machine, and then cut to a length of 51 mm to be a single fiber. Raw cotton of Kaishima composite fiber with a fineness of 4.4 dtex was obtained. The average single fiber diameter of the ultrafine fibers obtained from this sea-island composite fiber was 4.4 μm.

Using the raw cotton obtained as described above, a laminated web was formed through a card and cross wrapper process. Then, a needle punching process was performed with a number of punches of 3500 / cm ² to obtain a fiber entangled body having a basis weight of 700 g / m ² and a thickness of 3.0 mm.

After the fiber entanglement obtained as described above is shrink-treated with hot water at 98 ° C., 20% by mass of sodium sulfate as a heat-sensitive coagulant is added to 100% by mass of the solid content of polyurethane to obtain a carbodiimide system. A sheet with polyurethane having a thickness of 2.1 mm was obtained by impregnating with a water-dispersed polyurethane solution prepared by adding 3% by mass of a cross-linking agent and water to a solid content of 12%, and drying with hot air at 160 ° C. for 20 minutes. rice field.

The polyurethane-coated sheet obtained as described above 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 5 minutes to remove the sea component of the sea-island type composite fiber. Then, it was immersed in water, washed for 30 minutes, and dried in a dryer at 160 ° C. for 30 minutes to obtain a sheet made of ultrafine fibers (sheet with polyurethane).

The polyurethane sheet obtained through each of the above steps is cut in half so that the thickness is halved, ground with sandpaper count 180 endless sandpaper, and brushed to a thickness of 0.75 mm. I got a fluffy sheet.

The fluff sheet obtained as described above was dyed with a liquid flow dyeing machine under the condition of 120 ° C. and then dried with a dryer. The average single fiber diameter of the ultrafine fibers was 4.4 μm, and the ultrafine fibers were ultrafine. An artificial leather having a degree of deformation of fiber A of 1.9, a degree of deformation of ultrafine fiber B of 1.4, a mass ratio of polyurethane to 20% by mass in the artificial leather, and a fluff length of 290 μm was obtained. The obtained artificial leather had excellent flexibility and texture, and had a good touch and an elegant surface quality. The results are shown in Table 2.

[Example 11]
Artificial leather was obtained in the same manner as in Example 10 except that the degree of deformation of the ultrafine fibers A arranged on the outermost periphery of the ultrafine fiber bundle was set to 3.0. The obtained artificial leather had excellent flexibility and texture, and had a good touch and an elegant surface quality. The results are shown in Table 2.

[Comparative Example 1]
Artificial leather was obtained in the same manner as in Example 1 except that the degree of deformation of the ultrafine fibers A arranged on the outermost periphery of the ultrafine fiber bundle was 6.0. Although the obtained artificial leather had good flexibility and texture, the artificial leather was poor in strength and the surface quality was inferior to that of Example 1. The results are shown in Table 2.

[Comparative Example 2]
Artificial leather was obtained in the same manner as in Example 1 except that the degree of deformation of the ultrafine fibers A arranged on the outermost periphery of the ultrafine fiber bundle was 1.4. The obtained artificial leather had good surface quality, but its flexibility and texture were inferior to those of Example 1. The results are shown in Table 2.

[Comparative Example 3]
Artificial leather was obtained in the same manner as in Example 1 except that the degree of deformation of the ultrafine fibers B arranged outside the outermost periphery of the ultrafine fiber bundle was set to 2.5. The obtained artificial leather had good surface quality, but its flexibility and texture were inferior to those of Example 1. The results are shown in Table 2.

As shown in Tables 1 and 2, the artificial leathers of Examples 1 to 11 are polymer by setting the ultrafine fibers arranged on the outermost periphery of the ultrafine fiber bundle constituting the fiber entanglement to a specific degree of deformation. When the elastic body is applied, it becomes difficult for the polymer elastic body to invade the inside of the ultrafine fiber bundle, and the adhesive structure of the polymer elastic body is not between the fibers but between the fiber bundles and the fiber bundles. Is excellent in flexibility and texture, and has a good touch and an elegant surface quality.

On the other hand, as shown in Comparative Example 1, when the degree of deformation of the ultrafine fibers A arranged on the outermost periphery of the ultrafine fiber bundle is increased, the strength of the fiber entanglement becomes low and the fibers are easily shed. Leather has inferior surface quality.

Further, as shown in Comparative Example 2, when the degree of deformation of the ultrafine fibers A arranged on the outermost periphery of the ultrafine fiber bundle is reduced, the polymer elastic body is formed inside the ultrafine fiber bundle when the polymer elastic body is applied. The resulting artificial leather is inferior in flexibility and texture because it penetrates and the adhesive structure of the polymer elastic body adheres between the fibers.

Further, as shown in Comparative Example 3, when the degree of deformation of the ultrafine fiber B arranged outside the outermost circumference of the ultrafine fiber bundle is equal to or greater than the degree of deformation of the ultrafine fiber A arranged on the outermost circumference of the ultrafine fiber bundle, the ultrafine fiber Since the tightness of the bundle is poor, it is difficult to make the fiber entangled fine, and the obtained artificial leather is inferior in surface quality.

1: Line surrounding the outer circumference of the ultrafine fiber bundle 2: Extrafine fiber A arranged on the outermost circumference of the ultrafine fiber bundle
3: Extrafine fibers B arranged outside the outermost circumference of the ultrafine fiber bundle
4: Aggregation of multiple microfibers that are not considered to point in the same direction

Claims (7)

An artificial leather containing a fiber entangled body mainly composed of ultrafine fiber bundles having an average single fiber diameter of 0.1 μm or more and 7.0 μm or less and a polymer elastic body, and is the outermost periphery of the ultrafine fiber bundle. Artificial leather in which the degree of deformation of the ultrafine fibers A arranged in is 1.5 or more and 5.0 or less, and larger than the degree of deformation of the ultrafine fibers B arranged outside the outermost periphery. The artificial leather according to claim 1, wherein the single fiber diameter b of the ultrafine fiber B satisfies the following formula (i) with respect to the single fiber diameter a of the ultrafine fiber A.
0.5 ≤ a / b ≤ 1.5 ... (i) The artificial leather according to claim 1 or 2, wherein the ultrafine fiber B has a degree of deformation of 1.0 or more and less than 1.5. The artificial leather according to any one of claims 1 to 3, wherein the variation in the degree of deformation of the ultrafine fiber A is 0.1% or more and 25% or less. The artificial leather according to any one of claims 1 to 4, wherein the variation in the degree of deformation of the ultrafine fiber B is 0.1% or more and 25% or less. The artificial leather according to any one of claims 1 to 5, wherein the mass ratio of the polymer elastic body to the artificial leather is 15% by mass or more and 50% by mass or less. The artificial leather according to any one of claims 1 to 6, wherein the artificial leather has a nap length of 200 μm or more and 500 μm or less.

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