JP2013181252A - Method of manufacturing elastic artificial leather - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing artificial leather excellent in elasticity, particularly elasticity in a longitudinal direction which cannot be attained by a conventional method, without reducing surface quality of the artificial leather.SOLUTION: A method of manufacturing elastic artificial leather includes the steps of: (1) forming a web from a fiber splittable into ultrafine fibers; (2) entangling the obtained web to produce an entangled non-woven fabric; (3) impregnating the obtained entangled non-woven fabric with a polymer elastomer to solidify the fabric; (4) splitting the entangled non-woven not containing the polymer elastomer obtained at the step (2) or the fiber splittable into ultrafine fibers in the non-woven fabric containing the polymer elastomer obtained at the step (3) into ultrafine fibers to produce a base substance for artificial leather containing a fiber bundle of the ultrafine fibers and the polymer elastomer; (5) producing artificial leather by using the obtained base substance for artificial leather; and (6) closely contacting the obtained artificial leather with an elastomer sheet stretched in a longitudinal direction by 5-40%, then relaxing the stretch of the elastomer sheet to shrink the elastomer sheet and the artificial leather in a longitudinal direction, then heat-setting the shrinkage of the artificial leather, and then removing the artificial leather form the elastomer sheet.

Description

The present invention relates to a method for producing a stretchable artificial leather that has moderate stretchability in the vertical direction and has a feeling of non-stretching and is excellent in flexibility, molding processability, and wearing feeling.

Since leather-like sheets such as artificial leather have flexibility and functionality not found in natural leather, they are used in various applications such as clothing and materials. Stretchability has attracted attention as an important function from the viewpoints of wearing feeling in clothing, molding processability in materials, and ease of sewing and tailoring.

From the above background, various leather-like sheets having elasticity have been studied. For example, an elastic sheet obtained by stretching 15% or more in the vertical and / or horizontal direction on a base for artificial leather mainly composed of a fiber entanglement including ultrafine fibers having a single fiber fineness of 0.9 dtex or less and a polymer elastic body. After bonding, a method for producing artificial leather excellent in elasticity, characterized by shrinking the artificial leather by relaxing the extension of the elastic sheet and then removing the elastic sheet has been proposed (for example, Patent Document 1). However, this method requires the steps of applying an adhesive to the elastic sheet and removing the adhesive, which reduces productivity. Further, when the artificial leather substrate is shrunk after being bonded to the elastic sheet, the artificial leather substrate is curled on the elastic sheet side and the process passability is deteriorated. Further, since the artificial leather substrate is contracted only by the contraction force of the elastic sheet, it is difficult to contract the high-density artificial leather substrate at a high contraction rate. Furthermore, the use of adhesives degrades the quality of the artificial leather surface.

Therefore, a manufacturing method that does not use an elastic sheet has been proposed. For example, Patent Document 2 discloses that an artificial leather mainly composed of a fiber entangled body mainly containing ultrafine fibers having a single yarn fineness of 1.1 dtex or less and a polyurethane resin, after applying a softener to the artificial leather, A method for producing artificial leather excellent in stretchability in the width direction is disclosed, wherein the agent is applied and simultaneously stretched in the length direction and contracted in the width direction in a heated state. However, since it elongates in the length direction, spotted spots and thickness spots of artificial leather are promoted. Moreover, since it extended | stretched by providing a softening agent, when it used as a suede-like artificial leather, the surface uniformity and abrasion resistance were inadequate. In addition, the proposed manufacturing method is intended to improve the extensibility of the artificial leather in the width direction. In the production method, since the stretched product is stretched in the length direction in a heated state, the stretchability in the lengthwise direction of the obtained artificial leather is low. Therefore, Patent Document 2 describes the improvement of the stretchability in the vertical direction of the artificial leather. Not considering anything.

A method in which the fabric is forcibly compressed in the vertical direction using a shrinkage processing apparatus having a configuration in which the endless rubber belt runs while contacting a part of the peripheral surface of the thermal cylinder roll, thereby forming a wrinkle on a part of the fabric, or A method for softening a high-density fabric has been proposed (Patent Documents 3 and 4). However, Patent Documents 3 and 4 do not describe anything about artificial leather having an entangled body of ultrafine fibers, and do not discuss anything about improving the stretchability of the fabric in the vertical direction.

As described above, the above prior art documents do not provide a simple and efficient method for improving the stretchability and stretchability of artificial leather.

JP 2004-197282 A Japanese Patent Laying-Open No. 2005-0761151 Japanese Patent Laid-Open No. 5-44153 JP 9-31832 A

The present invention relates to a method for producing stretchable artificial leather having moderate stretchability, a feeling of non-stretching, and good flexibility (especially flexibility when bending) even at high density.

This invention solves the said subject with the following manufacturing methods. That is, the method for producing the stretchable artificial leather of the present invention includes:
(1) a process of forming ultrafine fibers into a web;
(2) A step of entangled the obtained web to produce an entangled nonwoven fabric,
(3) A step of arbitrarily giving a polymer elastic body to the entangled nonwoven fabric obtained,
(4) An ultra-fine fiber obtained by micronizing the entangled non-woven fabric that does not contain the polymer elastic body obtained in the step (2) or the ultrathin fiber in the polymer elastic body-containing non-woven fabric obtained in the step (3) A process for producing a substrate for artificial leather comprising a fiber bundle of
(5) a process for producing artificial leather using the obtained artificial leather substrate, and (6) the obtained artificial leather is closely attached to an elastic sheet that is stretched 5 to 40% in the vertical direction, and the elastic body The elastic sheet is contracted in the vertical direction by relaxing the extension of the sheet, the artificial leather is contracted in the vertical direction, the contracted state of the artificial leather is heat-set, and then the artificial leather is separated from the elastic sheet. Process.

Further, in a preferred embodiment of the production method of the present invention, a thick elastic sheet is used, and the thick elastic sheet is caused to travel while being in contact with the surface of the roller. The elastic sheet is stretched and contracted. In another preferred embodiment, the shrinkage state of the artificial leather is heat set by the ironing effect of the heating cylinder.

According to the production method of the present invention, it is possible to obtain a stretchable artificial leather having moderate stretchability and a feeling of non-stretching in the vertical direction.

It is the schematic which shows an example of the shrinkage processing apparatus for enforcing the manufacturing method of this invention. It is the schematic which shows the other example of the shrinkage processing apparatus for enforcing the manufacturing method of this invention. It is a figure which shows the load elongation curve (SS curve) of the length direction of the elastic | stretch artificial leather obtained in Example 1, and the non-shrink processing artificial leather of the comparative example 1. FIG. It is a scanning electron micrograph of the cross section parallel to the thickness direction and the vertical direction of the artificial leather before shrinkage processing of Example 1 (non-shrinkage processing artificial leather of Comparative Example 1). 2 is a scanning electron micrograph of a cross section parallel to the thickness direction and the vertical direction of the stretchable artificial leather obtained in Example 1. FIG.

The method for producing the stretchable artificial leather of the present invention comprises:
(1) a process of forming ultrafine fibers into a web;
(2) A step of entangled the obtained web to produce an entangled nonwoven fabric,
(3) impregnating the obtained entangled nonwoven fabric with a polymer elastic body and solidifying it,
(4) An ultra-fine fiber obtained by micronizing the entangled non-woven fabric that does not contain the polymer elastic body obtained in the step (2) or the ultrathin fiber in the polymer elastic body-containing non-woven fabric obtained in the step (3) A process for producing a substrate for artificial leather comprising a fiber bundle of
(5) a process for producing artificial leather using the obtained artificial leather substrate, and (6) the obtained artificial leather is closely attached to an elastic sheet that is stretched 5 to 40% in the vertical direction, and the elastic body The elastic sheet is contracted in the vertical direction by relaxing the extension of the sheet, the artificial leather is contracted in the vertical direction, the contracted state of the artificial leather is heat-set, and then the artificial leather is separated from the elastic sheet. Process. By the above manufacturing method, while maintaining the surface smoothness of the artificial leather, the micro-buckling structure of the ultrafine fibers contained in the artificial leather is formed along the vertical direction of the artificial leather, and the artificial leather has excellent stretchability in the vertical direction. Can be manufactured.

Process (1)
In step (1), the ultrathinnable fiber is made into a web. The ultrathinnable fiber is a multicomponent composite fiber composed of at least two types of polymers. For example, a sea-island fiber has a cross section in which a different type of island component polymer is dispersed in a sea component polymer. The ultrafine fiber can be formed by forming an entangled nonwoven fabric, and then extracting or decomposing and removing one component (removal component) of the polymer before or after impregnation with the polymer elastic body, thereby removing the remaining polymer ( The fiber bundle is converted into a bundle of fibers. In the case of a sea-island type fiber, the sea component polymer is extracted or decomposed to be removed, and thereby converted into a fiber bundle in which a plurality of ultrafine fibers made of the remaining island component polymer are collected.

The ultrathinnable fiber is not particularly limited, and can be appropriately selected from sea-island fibers, multilayer laminated fibers, and the like obtained by a method such as a mixed spinning method or a composite spinning method. Hereinafter, although the case where a sea-island type fiber is used as the ultra-thinnable fiber will be described, the present invention can be similarly carried out when an ultra-thinnable fiber other than the sea-island type fiber is used. The polymer forming the ultrafine fibers (island component of the sea-island fiber) is preferably an inelastic polymer. Specifically, ultrafine fibers made of polyester, polyamide, polypropylene, polyethylene or the like are preferably used. Elastic fibers such as polyether ester fibers and polyurethane fibers such as so-called spandex are not preferable.

The polyester is not particularly limited as long as it can be fiberized. Specifically, for example, polyethylene terephthalate, polytrimethylene terephthalate, polytetramethylene terephthalate, polycyclohexylene dimethylene terephthalate, polyethylene-2,6-naphthalenedicarboxylate, polyethylene-1,2-bis (2- Chlorophenoxy) ethane-4,4′-dicarboxylate and the like. Among them, polyethylene terephthalate that is most commonly used or a modified polyester mainly composed of ethylene terephthalate units (for example, isophthalic acid-modified polyethylene terephthalate) is preferably used.

Examples of the polyamide include polymers having an amide bond such as nylon 6, nylon 66, nylon 610, nylon 12, and the like.

To the island component polymer, inorganic particles such as titanium oxide particles may be added to improve the concealability, and lubricants, pigments, heat stabilizers, ultraviolet absorbers, conductive agents, heat storage materials, antibacterial agents, etc. These can also be added according to various purposes.

When the sea-island type fiber is converted into a fiber bundle of ultrafine fibers, the sea component polymer is extracted or decomposed and removed by a solvent or a decomposing agent. Accordingly, the sea component polymer needs to be more soluble in a solvent or decomposable by a decomposing agent than the island component polymer. From the viewpoint of spinning stability of the sea-island fiber, it is preferable that the affinity with the island component polymer is small and the melt viscosity and / or the surface tension is smaller than the island component polymer under the spinning conditions. As long as these conditions are satisfied, the sea component polymer is not particularly limited. For example, polyethylene, polypropylene, polystyrene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, styrene-ethylene copolymer, styrene-acrylic copolymer are used. Polymers, polyvinyl alcohol resins and the like are preferably used. Since artificial leather can be produced without using an organic solvent, water-soluble thermoplastic polyvinyl alcohol (PVA) or water-soluble thermoplastic modified polyvinyl alcohol (modified PVA) such as ethylene-modified PVA is used for the sea component polymer. Is preferred.

The average fineness of the sea-island fiber is preferably 1.0 to 6.0 dtex. In the cross section of the sea-island fiber, the mass ratio of the sea component polymer and the island component polymer is preferably 5/95 to 70/30,
The number of islands is preferably 5 or more.

The spinning method of the ultrafine fiber is not particularly limited, and may be manufactured by a method conventionally employed in the field of artificial leather manufacturing. The ultrathinnable fiber may be a short fiber or a long fiber. Short fibers are preferable because they can produce a non-woven fabric having a high-quality surface, but long fibers are preferable because they can simplify the manufacturing process and are excellent in physical properties such as strength. In addition, it is generally difficult to produce artificial leather having stretchability in the vertical direction using inelastic long fibers. However, according to the production method of the present invention, stretchability in the vertical direction can be achieved using nonelastic fibers. Can be produced.

The ultrafine fiber can be made into a web by a dry method such as carding or papermaking and a wet method, but it is preferable to make a web by a dry method because an artificial leather having a high quality surface can be obtained.

The ultrathinnable long fibers can be made into a web by the spunbond method, and if they are collected in the form of continuous filaments to form a web, some of the long fibers are cut in the subsequent process of making artificial leather. May be.

In the present invention, the long fiber is a fiber having a fiber length longer than a short fiber having a fiber length of usually about 3 to 80 mm, and means a fiber that is not intentionally cut like a short fiber. For example, the fiber length of the long fiber before ultrafinening is preferably 100 mm or more, and can be produced in a technical manner and has a fiber length of several meters, several hundreds of meters, several kilometers or more as long as it is not physically cut. It may be. In the case of a web using ultrathinnable continuous fibers, the surface fibers may be temporarily fused by hot pressing. When temporarily fused, the form of the web is stabilized and the handling property in the subsequent process is improved.

Basis weight of the web obtained in step (1) is preferably 10 to 100 g / m ^2.

Process (2)
In the step (2), the web obtained in the step (1) is entangled by a method such as needle punching or water jet to produce an entangled nonwoven fabric. For example, after a plurality of layers of the web are laminated using a cross wrapper or the like as necessary, needle punching is performed under the condition that at least one barb penetrates from both sides simultaneously or alternately. The punching density is preferably in the range of 200 to 5000 punches / cm ² . When it is within the above range, sufficient entanglement can be obtained, and damage to the ultrathinnable fiber by the needle is small. By the entanglement treatment, the ultrathinnable fibers are entangled three-dimensionally, and an entangled nonwoven fabric in which the ultrathinnable fibers are gathered very densely is obtained. The web may be provided with a silicone oil agent or a mineral oil agent such as a needle breakage preventing oil agent, an antistatic oil agent, or an entanglement improving oil agent at any stage from the production to the entanglement treatment. If necessary, the entangled state of the entangled nonwoven fabric may be made denser by a shrinking treatment such as immersing in warm water of 70 to 100 ° C. Moreover, the ultra-thinnable fibers may be gathered more densely by performing a heat press treatment to stabilize the form of the entangled nonwoven fabric. The basis weight of the entangled nonwoven fabric is preferably 100 to 2000 g / m ² .

Step (3)
In the step (3), the entangled nonwoven fabric obtained in the step (2) is impregnated with an aqueous dispersion or an organic solvent solution of a polymer elastic body as necessary and solidified. When the ultrathinnable fiber is a long fiber, the use of a polymer elastic body may be omitted.

Examples of the polymer elastic body include polyurethane elastomers, polyurea elastomers, polyurethane-polyurea elastomers, polyacrylic acid resins, acrylonitrile-butadiene elastomers, styrene-butadiene elastomers, among others, polyurethane elastomers, polyurea elastomers, polyurethane- Polyurethane elastomers such as polyurea elastomers are preferred. For example, a polyurethane-based elastomer obtained by using at least one selected from polymer diols having an average molecular weight of 500 to 3500 such as polyester diol, polyether diol, polyester polyether diol, polylactone diol, and polycarbonate diol is preferable. From the viewpoint of product durability, a polyurethane obtained by using a polymer diol containing 30% by weight or more of a polycarbonate diol is more preferable. When the polycarbonate diol is less than 30% by weight, the durability may be lowered.

Polycarbonate diol is one in which diol skeletons are linked via a carbonate bond to form a polymer chain and have hydroxyl groups at both ends. The diol skeleton is determined by the glycol used as a raw material, but the type thereof is not particularly limited. For example, 1,6-hexanediol, 1,5-pentanediol, neopentyl glycol, 3-methyl- 1,5-pentanediol can be used. In addition, a copolymer polycarbonate diol using at least two or more kinds of glycols selected from these glycol groups as raw materials is particularly preferable because an artificial leather excellent in flexibility and appearance can be obtained. In addition, when obtaining artificial leather with particularly excellent flexibility, it is preferable to introduce chemical bonds other than carbonate bonds, such as ester bonds and ether bonds, into the polymer diol within a range that does not impair durability.

As a method for introducing such a chemical bond, a method in which polycarbonate diol and other polymer diols are individually polymerized, and these are mixed and used in an appropriate ratio at the time of polyurethane production can be employed.

The polyurethane elastomer can be obtained by reacting a polymer diol, an organic polyisocyanate, and a chain extender in a predetermined molar ratio. The reaction conditions are not particularly limited, and a polyurethane elastomer can be produced by a conventionally known method.

Examples of the polymer diol include polyether polyols such as polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and poly (methyltetramethylene glycol) and copolymers thereof; polybutylene adipate diol, polybutylene sebacate diol, polyhexamethylene Polyester polyols such as adipate diol, poly (3-methyl-1,5-pentylene adipate) diol, poly (3-methyl-1,5-pentylene sebacate) diol, polycaprolactone diol and copolymers thereof; Hexamethylene carbonate diol, poly (3-methyl-1,5-pentylene carbonate) diol, polypentamethylene carbonate diol, polytetramethylene carbonate diol Polycarbonate polyols and their copolymers such as Le; polyester carbonate polyols and the like. Moreover, you may use together polyfunctional alcohols, such as a trifunctional alcohol and a tetrafunctional alcohol, or short chain alcohols, such as ethylene glycol, as needed. These may be used alone or in combination of two or more. In particular, amorphous polycarbonate polyols, alicyclic polycarbonate polyols, linear polycarbonate polyol copolymers, polyether polyols, and the like are preferable from the viewpoint of obtaining artificial leather excellent in the balance between flexibility and fullness. .

Examples of the organic polyisocyanate include non-yellowing diisocyanates such as aliphatic or alicyclic diisocyanates such as hexamethylene diisocyanate, isophorone diisocyanate, norbornene diisocyanate, and 4,4′-dicyclohexylmethane diisocyanate; 2,4-tolylene diisocyanate, Examples include aromatic diisocyanates such as 2,6-tolylene diisocyanate, 4,4′-diphenylmethane diisocyanate, and xylylene diisocyanate polyurethane. Moreover, you may use together polyfunctional isocyanates, such as trifunctional isocyanate and tetrafunctional isocyanate, as needed. These may be used alone or in combination of two or more. Among these, 4,4′-dicyclohexylmethane diisocyanate, isophorone diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4′-diphenylmethane diisocyanate, and xylylene diisocyanate have mechanical properties. It is preferable because it is excellent.

Examples of chain extenders include hydrazine, ethylenediamine, propylenediamine, hexamethylenediamine, nonamethylenediamine, xylylenediamine, isophoronediamine, piperazine and derivatives thereof, diamines such as adipic acid dihydrazide and isophthalic acid dihydrazide; and diethylenetriamine. Triamines; tetramines such as triethylenetetramine; ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, 1,4-bis (β-hydroxyethoxy) benzene, 1,4-cyclohexanediol Diols such as: Triols such as trimethylolpropane; Pentaols such as pentaerythritol; Aminoethyl alcohol, aminopropyl alcohol, etc. Roh alcohol, and the like. These may be used alone or in combination of two or more. Among these, it is preferable from the viewpoint of mechanical performance to use a combination of two or more of hydrazine, piperazine, ethylenediamine, hexamethylenediamine, isophoronediamine and derivatives thereof, and triamines such as diethylenetriamine. In addition, during the chain extension reaction, together with the chain extender, monoamines such as ethylamine, propylamine, and butylamine; carboxyl group-containing monoamine compounds such as 4-aminobutanoic acid and 6-aminohexanoic acid; methanol, ethanol, propanol, butanol, etc. Monools may be used in combination.

The polymer elastic body is impregnated into the entangled nonwoven fabric as an aqueous solution, an aqueous dispersion, or an organic solvent solution (for example, a solution of an organic solvent such as dimethylformamide, methyl ethyl ketone, acetone, toluene). The impregnation method is not particularly limited, and examples thereof include a method of uniformly impregnating the entangled nonwoven fabric by dipping and the like, and a method of applying to the front and back surfaces. The impregnated polymer elastic body aqueous solution, aqueous dispersion, or organic solvent solution may be solidified by conditions and methods conventionally employed in artificial leather production (for example, a wet method or a dry method).

The concentration of the polymer elastic body aqueous solution, aqueous dispersion (for example, aqueous emulsion), or organic solvent solution is preferably 5 to 50% by weight.

The application amount of the polymer elastic body varies depending on the fiber length (short fiber or long fiber) and the application method (aqueous solution, aqueous dispersion, organic solvent solution). From the product flexibility, surface touch, dyeing uniformity, The solid content is preferably in the range of 5 to 70% by weight of the ultrafine fiber weight. In particular, when short fibers are used and applied using an organic solvent solution of a polymer elastic body, the solid content is preferably 10 to 70% by weight of the ultrafine fiber weight. If the application amount is less than 10% by weight, the wear resistance tends to be lowered, and if the application amount exceeds 70% by weight, the texture tends to become hard, which is not preferable.

You may mix | blend additives, such as a coloring agent, antioxidant, an antistatic agent, a dispersing agent, a softening agent, and a coagulation regulator, in a polymeric elastic body as needed.

Step (4)
In the step (4), the ultrathin fiber in the non-woven fabric that does not contain the elastic polymer obtained in the step (2) or in the non-woven fabric containing the elastic polymer obtained in the step (3) is made extremely fine. By converting into a fiber bundle, an entangled body made of the ultrafine fiber bundle and a base for artificial leather made of a polymer elastic body contained in the entangled body are produced.

The ultrathinning of the ultrafine fiber is performed by removing the sea component polymer to convert the ultrafine fiber into a fiber bundle of ultrafine fibers. As a method for removing the sea component polymer, the non-island component polymer is dissolved but the sea component polymer is dissolved, or the non-degradable agent that does not decompose the island component polymer but decomposes the sea component polymer is contained in the elastic elastomer-containing nonwoven fabric. The method of processing is preferred. When the island component polymer is a polyamide resin or a polyester resin, if the sea component polymer is polyethylene, an organic solvent such as toluene, trichloroethylene, or tetrachloroethylene is used. If the sea component polymer is water-soluble thermoplastic PVA or modified PVA, warm water is used. However, if the sea component polymer is an easily alkali-decomposable modified polyester, an alkaline decomposing agent such as an aqueous sodium hydroxide solution is used. The removal of the sea component polymer may be performed according to methods and conditions conventionally employed in the artificial leather field, and is not particularly limited. When a method with a low environmental load is desired, water-soluble thermoplastic PVA or modified PVA is used as the sea component polymer, and this is used in hot water at 85 to 100 ° C. without using an organic solvent. It is preferable to process for a second, extract and remove until the removal rate is 95% by mass or more (including 100%), and convert the ultrafine fiber into a fiber bundle of ultrafine fibers made of island component polymers.

The average single fiber fineness of the ultrafine fibers forming the entangled body of the artificial leather substrate of the present invention is preferably 0.9 dtex or less, more preferably 0.0001 to 0.9 dtex, more preferably 0.0001 to 0. 5 dtex, particularly preferably 0.005 to 0.3 dtex. If the average single fiber fineness is less than 0.0001 dtex, the strength of the artificial leather substrate may be lowered. On the other hand, when the average single fiber fineness exceeds 0.9 dtex, the texture of the artificial leather substrate becomes stiff, the fiber entanglement becomes insufficient, the surface quality of the artificial leather substrate decreases, Problems such as a decrease in wear may occur. In addition, a limited amount of fibers having a single fiber fineness of less than 0.0001 dtex or fibers having a single fiber fineness of more than 0.9 dtex may be included as long as the effects of the present invention are not impaired. The content of fibers having a single fiber fineness of less than 0.0001 dtex and fibers having a single fiber fineness of more than 0.9 dtex is preferably 30% or less (several standards) of the total fibers constituting the substrate for artificial leather, 10% The following (number basis) is more preferable, and it is further preferable that none is included.

The fineness of the fiber bundle of ultrafine fibers is preferably 1.0 to 4.0 dtex, and the number of ultrafine fibers in one fiber bundle is preferably 9 to 500. Within the above range, the appearance uniformity of the artificial leather substrate and the suede-like artificial leather obtained therefrom and the balance between the color development and the wear resistance are good.

The basis weight of the artificial leather substrate is preferably 150 to 1500 g / m ² . When the basis weight of the artificial leather substrate is 150 g / m ² or more, a good rebound can be obtained. Further, when the basis weight of the artificial leather substrate is 1500 g / m ² or less, the processability for various uses is good. The apparent density of the artificial leather substrate is preferably 0.25 to 0.80 g / cm ³ . When the apparent density is 0.25 g / cm ³ or more, the wear resistance is good. Further, when the apparent fiber density is 0.80 g / cm ³ or less, the processability for various uses is good. The thickness of the artificial leather substrate is selected according to the use of the artificial leather, but is usually 0.3 to 3.0 mm.

Step (3) may be omitted. Further, after the step (4), the step (3) is performed to make the ultrathinnable fiber ultrafine, and then the polymer elastic body may be contained.

In addition to the additives described above, the artificial leather substrate of the present invention includes other dyes, softeners, texture modifiers, anti-pilling agents, antibacterial agents, deodorants, Functional agents such as a liquid medicine, a light-proofing agent, and an anti-glare agent may be contained.

Process (5)
In the step (5), a silver surface layer is provided on at least one surface of the artificial leather substrate obtained in the step (4), or at least one surface is napped to give a silver-tone artificial leather, semi-silver A tanned artificial leather, a napped artificial leather, or a nubuck artificial leather is obtained. A method of providing a silver layer on at least one surface of the artificial leather substrate, and a method of raising the surface of at least one surface of the artificial leather substrate may adopt a method conventionally used for manufacturing artificial leather, The present invention is not particularly limited. For example, a dry surface forming method in which a silver surface layer and an adhesive layer formed on a release paper are bonded to at least one surface of an artificial leather substrate via an adhesive layer, on at least one surface of an artificial leather substrate The silver surface layer can be formed by a method of applying a dispersion or solution of a polymer elastic body to be a silver surface layer and drying and coagulating it. Further, a raised surface can be formed by a method of raising at least one surface of the artificial leather substrate with a needle cloth, sandpaper or the like, and then performing a hair treatment.

Is preferably the basis weight of the artificial leather obtained as described above is 130~1600g / m ^2, more preferably from 150~1400g / m ^2, apparent density 0.25~0.80g / cm ³ It is preferable that it is 0.30-0.70 g / cm < ³ >, and it is preferable that thickness is 0.5-2.0 mm.

Step (6)
In step (6), the artificial leather obtained in step (5) is mechanically shrunk in the vertical direction (MD of the production line), and this contracted state is heat-set, so that it has appropriate stretchability in the vertical direction. In addition, there is obtained a stretchable artificial leather having a good feeling of being stretched and having good flexibility.

As one specific example of the mechanical shrinkage treatment for obtaining the stretchable artificial leather of the present invention, the artificial leather was stretched in the vertical direction of a thick elastic sheet (rubber sheet, felt, etc.) having a thickness of several centimeters or more. There is a method in which the artificial leather is contracted in the vertical direction by closely contacting the surface and elastically recovering the surface from the stretched state to the state before stretching. FIG. 1 is a schematic view showing an example of an apparatus for contracting artificial leather by this method. The belt 3 made of a thick elastic sheet advances while contacting the surface of the pressure roller 4 (surface material: metal). During this time, the outer surface of the belt 3 is elongated in the vertical direction due to the difference between the inner and outer circumferences of the belt. The artificial leather 1 sent from the turn rollers 5 a and 5 b is brought into close contact with the extended outer surface of the belt 3. The belt 3 and the artificial leather 1 in close contact with the belt 3 pass through the gap between the pressure roller 4 and the drum 2 (surface material: metal), and run while contacting the surface of the drum 2. After passing through this gap, the surface of the belt 3 on the side of the artificial leather 1 shrinks so as to be driven in the direction of travel (vertical direction) by elastic recovery from the stretched state in the vertical direction to the state before stretching. Corresponding to the change from the stretched state of the belt 3 to the elastic recovery state, the artificial leather 1 is shrunk so as to be driven in the traveling direction (vertical direction), and then taken up as the shrunk artificial leather 6. The outer diameter of the pressure roller 4 is preferably 10 to 50 cm in order to extend the outer surface of the elastic sheet by using the difference between the inner and outer circumferences at an elongation rate in the range described later. In addition, by relaxing the stretched state of the outer surface of the elastic sheet and restoring it to the state before stretching, the elastic sheet is contracted in the vertical direction (traveling direction), and at the same time, the artificial leather is contracted within the range described below. In order to contract in the vertical direction (traveling direction), the outer diameter of the drum 2 is preferably larger than the outer diameter of the pressure roller 4 and is 20 to 80 cm. The diameter of the drum 2 is preferably as large as possible in order to lengthen the heat setting time and efficiently perform the heat setting, but is smaller in order to set the contraction rate using the internal / external aberration of the elastic belt within the range of the present invention. Therefore, the outer diameters of the drum 2 and the roller 4 are determined in consideration of these. Usually, it is preferable to prioritize the heat setting time. The pressure roller 4 is generally not directly heated, but a method of preheating the original fabric (artificial leather) before shrinking is generally used, but the surface temperature of the roller 4 in a steady operation state is about 40 to 90 ° C. The surface temperature of the drum 2 is preferably heated to 70 to 150 ° C. The belt 3 is preferably a thick belt such as rubber or felt, and the thickness is usually 20 mm or more. Further, when the conveying speed of the artificial leather 1 by the turn rollers 5a and 5b in FIG. 1 is higher than the conveying speed of the belt 3, the artificial leather 1 is folded in the vertical direction on the surface of the belt 3, and the folded artificial leather 1 is folded. Since the surface of the belt 3 is shrunk due to the change from the stretched state to the elastic recovery state, the shrinkage effect of the artificial leather 1 can be increased.

As another mechanical shrinkage treatment method, there is a method in which the artificial leather is shrunk in the vertical direction (traveling direction) by utilizing the action of elastically recovering the elastic sheet from the stretched state by nip-deforming between the pressure rollers. is there. FIG. 2 is a schematic view showing an example of an apparatus for contracting artificial leather by this method. A belt 3 made of an elastic sheet circulates along the surface of a rubber roller 13 having a metal roller 11 and a thick rubber portion 12. The outer surface of the belt 3 extends in the vertical direction due to the difference between the inner and outer circumferences when traveling on the surface of the rubber roller 13. The artificial leather 1 is supplied to the extended outer surface of the belt 3. The belt 3 and the artificial leather 1 are guided to the nip portion between the metal roller 11 and the rubber roller 13. The thick rubber portion 12 is deformed toward the center of the rubber roller 13 by the pressure of the nip. Due to this deformation, the belt 3 elastically recovers from the stretched state to the original state, and accordingly, the artificial leather 1 contracts in the vertical direction (traveling direction) under compression. The contracted artificial leather 14 travels along the surface of the heated metal roller 11, and is heat-treated during this time and taken off. The surface temperature of the metal roller 11 is preferably 70 to 150 ° C. Generally, the rubber roller 13 is not directly heated, and the raw material (artificial leather) before shrinking is preheated, but the surface temperature of the rubber roller 13 in a steady operation state is 40 to 90 ° C. Is preferred.

The method for producing the artificial leather of the present invention using the mechanical shrinkage treatment described above causes the artificial leather to adhere to the surface without using an adhesive means such as an adhesive while extending the surface of the elastic sheet in the vertical direction. Next, the stretched state is relaxed to elastically recover the surface of the elastic sheet to the state before stretching, and the artificial leather is shrunk so as to be driven in the traveling direction (vertical direction). The elongation ratio of the elastic sheet surface when adhering the artificial leather ((extended length / length before extension) × 100) is 5 to 40%, preferably 7 to 25%, more preferably 10 to 20%. is there. If it is 5% or more, even when artificial leather that hardly stretches in the vertical direction is adhered, artificial leather that extends in the vertical direction can be obtained by the shrinking treatment in the step (6). For example, an artificial leather made of short fibers having a basis weight of 250 g / m ² or less is stretched by the tension applied in the manufacturing process, and as a result, hardly stretches in the vertical direction. However, according to the production method of the present invention, it is possible to obtain an artificial leather that easily extends in the vertical direction even when short fibers are used. In addition, when a web by a spunbond method is used, an artificial leather that generally has filaments arranged in the vertical direction and is difficult to extend in the vertical direction is obtained, but according to the manufacturing method of the present invention, artificial leather that extends in the vertical direction is obtained. Can be obtained.

The shrinkage treatment is preferably performed at 70 to 150 ° C., more preferably 90 to 130 ° C., and the artificial leather is shrunk in the vertical direction at a shrinkage rate of preferably 2 to 20%, more preferably 4 to 15%.
Shrinkage rate = [(length before shrinkage) − (length after shrinkage)] / length before shrinkage × 100

The elastic sheet used in the present invention is not particularly limited as long as it is a sheet-like material having the above-mentioned elastic characteristics, but it is preferable to use a sheet of natural rubber or synthetic rubber. Using an elastic sheet of natural rubber or synthetic rubber, especially because it has a high elastic recovery force, when shrinking together with an artificial leather that is in close contact, the effect of shrinking the artificial leather sufficiently against the resistance of the artificial leather is obtained. Can do. Moreover, in order to prevent the structural change of the artificial leather surface due to heating and pressurization during the shrinking treatment, it is preferable to control the tension of the elastic sheet low and use an elastic sheet having low hardness.

The thickness of the elastic sheet is preferably 20 to 100 mm, and more preferably 30 to 70 mm. Within the above range, the elastic sheet can be effectively extended and contracted in the vertical direction using the difference between the inner and outer circumferences.

As the natural rubber, rubber mainly composed of cis-1,4-polyisoprene collected from bark such as Hevea tree can be used.

Synthetic rubber includes styrene-butadiene rubber, butadiene rubber, isoprene rubber, butyl rubber, ethylene propylene rubber, chloroprene rubber, nitrile rubber, silicone rubber, acrylic rubber, epichlorohydrin rubber, fluorine rubber, urethane rubber, ethylene-vinyl acetate rubber, chlorinated Polyethylene rubber or the like can be used.

In the production method of the present invention, before the artificial leather is separated from the elastic sheet, the contraction state of the artificial leather is heat-set by heating. Therefore, the elastic sheet is preferably excellent in heat resistance, and heat resistant silicone. Rubber, fluororubber or ethylene propylene rubber is preferred.

In the production method of the present invention, after the artificial leather is shrunk in the vertical direction, the artificial leather is heated before being pulled away from the elastic sheet, and the contracted state is heat set. Thereby, elasticity can be improved. The heating temperature for the heat setting is preferably selected from the range of 100 to 150 ° C. in consideration of the thermal history received by the fibers contained in the artificial leather in the manufacturing process. For example, in the case of artificial leather treated with wet heat 120 ° C. with a liquid dyeing machine or the like, the temperature for heat setting is preferably 120 ° C. or higher for wet heat treatment and 140 ° C. or higher for dry heat treatment. The heat set treatment time varies depending on the polymer type of the fiber contained in the artificial leather and the heat set temperature, and is usually selected from the range of 0.1 to 5 minutes. For example, in the case of polyethylene terephthalate fiber, 1 to 3 minutes is preferable in terms of heat setting and processing stability. When one heat setting is insufficient, it is preferable to heat set again after separating the artificial leather from the elastic sheet.

The heat setting method may be a known method such as a method of heating by blowing hot air on artificial leather, a method of heating using an infrared heater, a method of heat-treating between a heating cylinder and an elastic sheet or non-woven sheet, and the like. However, from the viewpoint that it can be processed with low tension, a method of using the ironing effect of the heating cylinder by heat-treating it between the heating cylinder and the sheet is preferably used. Heat-set artificial leather is usually withdrawn at a speed of 2 to 15 m / min.

In order to shrink the artificial leather more effectively in the vertical direction, it is preferable to perform a preheat treatment and / or a humidification treatment for softening the artificial leather before the artificial leather is brought into close contact with the elastic sheet. As a preheating method, a known heating method such as a method of heating while humidifying by blowing steam or water, a method of blowing hot air to artificial leather, a method of heating using an infrared heater, or the like can be used. Although the optimum conditions for the preheat treatment vary depending on the artificial leather used, the preheat temperature is preferably 40 to 100 ° C. In order to prevent the artificial leather from excessively raising the temperature during the shrinkage treatment, it is preferable to impart moisture to the artificial leather by spraying steam or water and performing a humidification treatment. The amount of moisture applied is preferably 1 to 5% by weight based on the amount of ultrafine fibers in the artificial leather. Thereby, the temperature of artificial leather can be easily controlled to 100 degrees C or less. In addition, when it is desired to effectively perform the shrinkage treatment by raising the temperature of the artificial leather to 100 ° C. or higher, it is preferable to use hot air or an infrared heater. The preheat treatment and the humidification treatment may be combined.

In the production method of the present invention, the artificial leather is shrunk so as to drive it in the direction of travel (vertical direction), so that the resulting stretchable artificial leather has a micro-bending structure consisting of a fiber bundle of ultrafine fibers and an arbitrary polymer elastic body. It has a (swell structure) and has a soft texture and a dense fold regardless of the apparent density of the stretchable artificial leather. The micro-bending structure is a wavy structure that occurs along the vertical direction as a result of the artificial leather contracting in the vertical direction, and the artificial leather of the present invention has a nonwoven fabric structure composed of ultrafine fibers. It is easy to form (refer FIG.4 and FIG.5). The waviness structure does not need to be continuous and may be discontinuous in the vertical direction. The stretchable artificial leather of the present invention is not stretchable of the fiber itself, but stretches in the vertical direction due to such a change in the buckling structure (elongation), has a feeling of non-stretching, and is less likely to lose its shape when worn. Good feeling of wear and workability for various uses. The apparent density of the stretchable artificial leather is preferably 0.25 to 0.80 g / cm ³ , and if it is within this range, the wear resistance and processability to various uses are good. The basis weight is 150 to 1700 g / m ² , and the thickness is selected according to the application, but is preferably 0.5 to 2.0 mm.

The stretchable artificial leather of the present invention has moderate stretchability in the vertical direction, so that it has a good feeling of wear and processability to the product, and it has a feeling of non-stretching, so that it can be prevented from losing its shape and shape. it can. The stretchability in the vertical direction and the feeling of stoppage of elongation can be evaluated by a load elongation curve in the vertical direction (vertical axis: load, horizontal axis: elongation). For example, the stretchable artificial leather of the present invention can exhibit a stretch rate of 10 to 40% ((stretched length / length before stretching) × 100) at a load of 40 N / cm. The feeling of non-elongation does not mean that it does not elongate at all, but it means that when the elongation exceeds a certain value, the resistance to elongation becomes remarkably large, and it is not easy to elongate. It is influenced by the change in load. In the present invention, the feeling of elongation stoppage is expressed by the ratio of the load at the time of 30% extension and the load at the time of 5% extension (at the time of 30% extension / 5% extension) in the load elongation curve in the vertical direction (see FIG. 3). The load at 5% elongation greatly affects the sewability, workability and wearing feeling. When the artificial leather is stretched by more than 30%, the structure of the nonwoven fabric that usually constitutes the artificial leather is greatly changed, and such artificial leather cannot exhibit the effect of preventing the loss of shape and shape as intended by the present invention. . For this reason, the load at 30% elongation was adopted. The load ratio of the stretchable artificial leather of the present invention is preferably 5 or more, more preferably 5 to 40. When it is within the above range, there is a feeling of stoppage of elongation in the vertical direction, there is little loss of shape due to wearing, and the feeling of wearing and workability for various uses is good.

In the present invention, the vertical direction is the flow direction (MD) of the artificial leather production line, and the direction perpendicular to this is the horizontal direction. The vertical direction of the artificial leather in the product can generally be determined from a plurality of factors such as the orientation direction of the fiber bundle of ultrafine fibers, streak traces by needle punching or high-speed fluid treatment, and treatment traces. If the vertical direction cannot be determined because the vertical direction determined by these multiple elements is different, there is no clear orientation, or there are no streak marks, the vertical direction in which the tensile strength is maximized is determined. The direction and the direction perpendicular to the direction are the horizontal direction.

In the manufacturing method of the present invention, the artificial leather is brought into close contact with the elastic sheet extended in the vertical direction, and then the elastic sheet is contracted in the vertical direction and the artificial leather is also contracted in the vertical direction. This contraction improves the stretchability of the artificial leather in the vertical direction, and the stretchable artificial leather obtained by the production method of the present invention extends in the vertical direction with a lower load than conventionally known artificial leather. As a result, the load elongation curve becomes a curve in which the load greatly increases when a certain elongation is exceeded (see FIG. 3). Therefore, the stretchable artificial leather of the present invention has a property (extension stop feeling) that stretches with a low load in a low stretch region and does not stretch unless a high load is applied in a high stretch region.

The stretchable artificial leather of the present invention thus obtained has moderate stretchability in the vertical direction and a feeling of non-stretching, and is excellent in surface quality, so it can be used in a wide range of applications such as clothing, furniture, car seats, sundries, etc. Can be used.

EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to a following example. Each physical property value in the examples was measured by the following method.

(1) The basis weight and the apparent density basis weight were measured by the method described in JIS L 1096 8.4.2 (1999). Further, the thickness was measured with a dial thickness gauge (manufactured by Ozaki Mfg. Co., Ltd., trade name “Peacock H”), and the apparent density was determined by dividing the basis weight value by the thickness value.

(2) Bending softness (index of flexibility when bending)
Measured by JIS L 1096 8.19.5 E method (handle ohmmeter method). A test piece (vertical direction: 10 cm, lateral direction: 10 cm) is placed on a slit with a width of 20 mm provided on the test bench, and the test piece is pushed into the slit to a depth of 8 mm with a blade, and the resistance (g) at that time Was measured. The measurement was performed in the vertical and lateral directions on the front and back surfaces, respectively.

(3) Elongation stop feeling Measured by the method described in JIS L 1096 (1999) 8.14.1 Method A. A test piece having a width of 2.5 cm was fixed to a chuck having a holding interval of 20 cm, and the test piece was pulled at a constant speed to obtain elongation and load. From the results, a load elongation curve was created in which the horizontal axis represents the elongation rate (%) and the vertical axis represents the load per 2.5 cm width of the test piece (Kg / 2.5 cm). From this curve, the load at the time of 30% elongation and the load at the time of 5% elongation were obtained, and the ratio (at the time of 30% elongation / 5% elongation) was obtained. Measurement was performed three times, and the average value was rounded to one decimal place. Evaluation was made with “A” when there was a sense of no-stretching (the ratio was 5 or more) and “C” when the others were not.

(4) Elongation rate The longitudinal elongation rate at a load of 40 N / cm was determined from the load elongation curve.

(5) Average single fiber fineness The cross-sectional area of 100 fibers randomly selected with an optical microscope was measured, and the number average was obtained. From the average value of the fiber cross-sectional area and the specific gravity of the fiber, the fineness was calculated. In addition, the specific gravity of the fiber was measured based on JIS L1015 8.14.2 (1999).

Example 1
Water-soluble thermoplastic ethylene-modified polyvinyl alcohol (modified PVA, sea component, modified degree 10 mol%) and isophthalic acid-modified polyethylene terephthalate (modified PET, island component) having a modified degree 6 mol% It was discharged from a die for melt composite spinning (number of islands: 25 islands / fiber) at 260 ° C. so that the island component was 25/75 (mass ratio). The ejector pressure was adjusted so that the spinning speed was 3700 m / min, and sea-island long fibers having an average fineness of 2.1 dtex were collected on the net. Next, a sheet of sea-island long fibers on the net is lightly pressed with a metal roll with a surface temperature of 42 ° C, peeled off from the net while suppressing surface fuzz, and between the metal roll (lattice pattern) with a surface temperature of 75 ° C and the back roll To obtain a long fiber web having a basis weight of 34 g / m ² in which the surface fibers were temporarily fused in a lattice shape.

An oil agent and an antistatic agent were applied to the long fiber web, 14 sheets were overlapped by cross-wrapping to produce a laminated web having a total weight of 480 g / m ² , and sprayed with a needle breakage preventing oil agent. Next, using a 6 barb needle with a distance of 3.2 mm from the tip of the needle to the first barb, needle punching was alternately performed at 3300 punch / cm ² from both sides at a needle depth of 8.3 mm. The area shrinkage rate by this needle punching treatment was 68%, and the basis weight of the entangled nonwoven fabric after needle punching was 580 g / m ² .

Water is applied in an amount of 10% by mass to the entangled nonwoven fabric, causing shrinkage by heat treatment in an atmosphere of relative humidity of 95% and 70 ° C., improving the apparent density of the nonwoven fabric and densifying. A non-woven fabric was obtained. The area shrinkage due to this densification treatment was 45%, the basis weight of the nonwoven fabric was 1050 g / m ² , and the apparent density was 0.52 g / cm ³ . Next, the densified nonwoven fabric was dry-heated and roll-pressed, impregnated with a water-based polyurethane emulsion, dried and cured at 150 ° C. to obtain a nonwoven fabric sheet containing a polymer elastic body. Subsequently, PVA was dissolved and removed in hot water at 95 ° C. to obtain a base for artificial leather having a resin fiber ratio R / F = 12/88.

The obtained base for artificial leather was sliced in parallel to the main surface and divided into two, and the divided surface was buffed with sandpaper to make the thickness uniform (thickness: 0.75 mm). Next, the surface (opposite side of the dividing surface) was raised and hair-treated with sandpaper. Next, after dyeing with a disperse dye using a liquid dyeing machine and drying, the hair was finished by brushing to obtain a napped artificial leather (thickness 0.8 mm, basis weight 377 / m ² , apparent density 0) .471 g / cm ³ ). FIG. 3 shows a load elongation curve in the vertical direction of the napped-tone artificial leather, and FIG. 4 shows a scanning electron micrograph of a cross section parallel to the thickness direction and the vertical direction.

The napped-tone artificial leather comprises a humidifying part, a shrinking part for shrinking the artificial leather continuously sent from the humidifying part, and a heat setting part for heat setting the fabric shrink-processed by the shrinking part. In addition, using a shrinkage processing device (manufactured by Komatsubara Iron Works Co., Ltd., Sun Forging Machine), the drum temperature at the shrinkage part is 120 ° C., the drum temperature at the heat setting part is 120 ° C., and the conveyance speed is 10 m / min. Stretched 9.2% in the length direction) to obtain a stretchable artificial leather. FIG. 3 shows a load elongation curve in the vertical direction of the stretchable artificial leather, and FIG. 5 shows a scanning electron micrograph of a cross section parallel to the thickness direction and the vertical direction.

The resulting stretchable artificial leather is superior in stretch in the vertical direction, has a soft texture, has a high density and excellent mechanical properties, has a feeling of fullness and is flexible, and is fine when bent. It was an excellent material as an artificial leather for car seats and sports shoes.

The evaluation results of the obtained stretchable artificial leather are shown in Table 1.

Example 2
Sea-island-type composite fiber staple having an island component modified with 6 mol% isophthalic acid-modified polyethylene terephthalate and a sea component polyethylene (island component: sea component = 60: 40 (mass ratio); fineness 4.0 dtex; fiber length 51 mm; 12 crimps / inch) was carded and cross-wrapped to create a web.

The web was entangled with a 1200 punch / cm ² needle punch, and then contracted in hot water at 90 ° C. to obtain an entangled nonwoven fabric with a basis weight of 750 g / m ² .

The entangled nonwoven fabric obtained was impregnated with a 15% dimethylformamide (DMF) solution of polyether polyurethane, and then immersed in a mixed liquid bath of DMF and water to wet-coagulate the polyurethane. After removing the remaining DMF by washing with water, the sea component polyethylene was extracted and removed in a 85 ° C. toluene bath, and the remaining toluene was removed azeotropically in a 100 ° C. hot water bath, followed by drying. A substrate for artificial leather having m ² and a thickness of 1.5 mm was obtained.

The surface of the obtained artificial leather substrate was buffed twice with No. 180 sandpaper to make the surface smooth and the thickness was 0.65 mm. Subsequently, the surface was buffed twice with 240 sand paper and twice with 400 sand paper to obtain napped artificial leather having a raised surface made of polyethylene terephthalate ultrafine fibers.

Next, after dyeing and drying with a disperse dye using a liquid dyeing machine, the hair was finished by brushing to obtain a dyed raised artificial leather (thickness 0.65 mm, basis weight 304 / m ² , apparent density 0) .468 g / cm ³ ).

The above-mentioned dyed napped artificial leather was treated using a shrinkage processing apparatus in the same manner as in Example 1 and contracted by 3% in the vertical direction.

The resulting stretchable artificial leather is superior in stretch in the vertical direction, has a soft texture, has a high density and excellent mechanical properties, has a feeling of fullness and is flexible, and is fine when bent. It was an excellent material as an artificial leather for molding and sports shoes.

The evaluation results of the obtained stretchable artificial leather are shown in Table 1.

Example 3
Sea island type composite fiber staple with island component nylon 6 and sea component polyethylene (island component: sea component = 50: 50 (mass ratio); fineness 3.5 dtex; fiber length 51 mm; crimp number 12 crimps / inch) , Cross-wrapped to create a web.

The web was entangled by needle punching at 400 punch / cm ² to obtain an entangled nonwoven fabric having a basis weight of 370 g / m ² .

The entangled nonwoven fabric obtained was impregnated with a 22% DMF solution of polyether polyurethane, and then immersed in a DMF / water mixed bath to wet-solidify the polyurethane. After removing the remaining DMF by washing with water, the sea component polyethylene was extracted and removed in a 85 ° C. toluene bath, and the remaining toluene was removed azeotropically in a 100 ° C. hot water bath, followed by drying. A substrate for artificial leather having m ² and a thickness of 0.8 mm was obtained.

The surface of the obtained artificial leather substrate was buffed twice with No. 180 sandpaper to make the surface smooth and the thickness was 0.7 mm. Then, the surface was buffed twice with 240 sand paper and twice with 400 sand paper to obtain napped artificial leather having a raised surface made of nylon 6 ultrafine fibers.

Subsequently, after dyeing and drying with a metal-containing dye using a liquid dyeing machine, the hair was finished by brushing to obtain a dyed raised artificial leather (thickness 0.50 mm, basis weight 177 g / m ² , apparent density). 0.354 g / cm ³ ).

The above-mentioned dyed napped artificial leather was treated using a shrinkage processing apparatus in the same manner as in Example 1 and shrunk 2% in the vertical direction.

The resulting stretchable artificial leather is superior in stretch in the vertical direction, has a soft texture, has a high density and excellent mechanical properties, has a feeling of fullness and is flexible, and is fine when bent. It was an excellent material for artificial leather for clothing and sports shoes.

The evaluation results of the obtained stretchable artificial leather are shown in Table 1.

Example 4
A sea component polymer PVA and an island component polymer isophthalic acid-modified polyethylene terephthalate having a modification degree of 6 mol% are melted at 260 ° C. so that the sea component / island component is 25/75 (mass ratio). It was discharged from a base for composite spinning (number of islands: 25 islands / fiber). Then, the ejector pressure was adjusted so that the spinning speed was 3700 m / min, and a spunbond sheet in which sea-island fibers having an average fineness of 2.1 dtex were deposited on the net was obtained. Next, fluffing of the surface was suppressed by lightly pressing the spunbond sheet on the net with a metal roll having a surface temperature of 42 ° C. The spunbond sheet was peeled from the net. Next, the spunbond sheet was hot-pressed between a lattice-pattern metal roll having a surface temperature of 55 ° C. and a back roll, whereby the sea-island type fiber of the surface layer was temporarily fused in a lattice shape with a basis weight of 28 g / m ² . A long fiber web was obtained.

An oil agent and an antistatic agent were applied to the long fiber web, and eight webs were overlapped by cross-wrapping to produce a superposed web having a total basis weight of 218 g / m ² , and sprayed with a needle breakage preventing oil agent. Then, a 6 barb needle with a distance of 3.2 mm from the needle tip to the first barb is used, and the overlap web is alternately punched from both sides at a needle depth of 8.3 mm at 3300 punches / cm ² , and the entangled nonwoven fabric Got. In addition, the area shrinkage rate by the needle punch process was 68%. Further, the basis weight of the obtained entangled nonwoven fabric was 311 g / m ² .

Next, the shrinkage | contraction process by immersing an entangled nonwoven fabric in 70 degreeC hot water for 28 second was performed. And the modified PVA which is a sea component polymer was melt | dissolved and removed by repeating the dip nip process in 95 degreeC hot water. By dissolving and removing the modified PVA, an ultrafine nonwoven fabric in which a fiber bundle composed of 25 ultrafine fibers having an average fineness of 0.09 dtex was entangled three-dimensionally was obtained. The area shrinkage rate by the shrinkage treatment was 52%. The basis weight of the ultrafine nonwoven fabric was 446 g / m ² and the apparent density was 0.602 g / cm ³ .

Next, the thickness of the ultrafine nonwoven fabric was adjusted to 0.9 mm by buffing. Then, a dispersion containing 300 parts by mass of an aqueous acrylic emulsion having a solid content concentration of 60% by mass and 90 parts by mass of a pigment is twice applied at a line speed of 6 m / min to the obtained ultrafine nonwoven fabric using a putter. The dip nip was used for impregnation. The solid content concentration of the acrylic resin in the water-based emulsion was 180 g / L, and the solid content concentration of the pigment was 90 g / L. Then, by blowing hot air of 120 ° C. from the surface side and drying, an ice gray acrylic elastic body was migrated to the surface layer and solidified to obtain a semi-silver-like artificial leather (thickness 0.88 mm, basis weight 437 g / m ² , apparent density 0.497 g / cm ³ ).

The semi-silver-like artificial leather was treated using a shrinkage processing apparatus in the same manner as in Example 1, and contracted 10.6% in the vertical direction.

The resulting stretchable artificial leather has excellent stretch and soft texture, high density and excellent mechanical properties, but the texture is full and flexible, and when it is bent, it has fine wrinkles. It was generated uniformly and was an excellent material for artificial leather for men's shoes and sports shoes.

The evaluation results of the obtained stretchable artificial leather are shown in Table 1.

Example 5
A long-fiber web was prepared using sea-island composite long fibers (island component: sea component = 50: 50 (mass ratio); fineness 3.5 dtex), in which the island component is nylon 6 and the sea component is polyethylene.

The web was entangled by needle punching at 400 punch / cm ² to obtain an entangled nonwoven fabric having a basis weight of 780 g / m ² .

The entangled nonwoven fabric obtained was impregnated with a 22% DMF solution of polyether polyurethane, and then immersed in a DMF / water mixed bath to wet-solidify the polyurethane. After removing the remaining DMF by washing with water, the sea component polyethylene is extracted and removed in a 85 ° C. toluene bath, the remaining toluene is removed azeotropically in a 100 ° C. hot water bath, dried, and divided into two in the thickness direction. As a result, a base for artificial leather having a basis weight of 325 g / m ² and a thickness of 0.77 mm was obtained.

The surface of the obtained artificial leather substrate was buffed twice with No. 180 sandpaper to make the surface smooth and the thickness was 0.7 mm. Next, the surface was buffed twice with No. 240 sandpaper and twice with No. 400 sandpaper to obtain a raised artificial leather having a raised surface composed of nylon 6 ultrafine fibers (thickness 0.61 mm, (Mass per unit area 261 g / m ² , apparent density 0.428 g / cm ³ ).

The above-mentioned napped-tone artificial leather was treated using a shrinkage processing apparatus in the same manner as in Example 1, and shrinked by 4.8% in the vertical direction.

The resulting stretchable artificial leather is superior in stretch in the vertical direction, has a soft texture, has a high density and excellent mechanical properties, has a feeling of fullness and is flexible, and is fine when bent. It was an excellent material for artificial leather for clothing and sports shoes.

The evaluation results of the obtained stretchable artificial leather are shown in Table 1.

Comparative Examples 1-4
Artificial leather was obtained in the same manner as in Examples 1 to 4 except that the shrinkage processing was not performed. The evaluation results are shown in Table 2. See FIGS. 3 and 4 for the vertical direction load elongation curve of the artificial leather not subjected to shrinkage processing in Comparative Example 1, and the scanning electron micrograph of the cross section parallel to the thickness direction and the vertical direction.

As is clear from Tables 1 and 2, the artificial leather of the comparative example was poor in stretchability in the vertical direction and hard in texture as compared with the stretchable artificial leather of Examples 1 to 4.

According to the present invention, it is possible to obtain a stretchable artificial leather having moderate stretchability and a feeling of non-stretching in the vertical direction, and since it is excellent in wearing feeling and molding processability, clothing, furniture, car seats, shoes, sports It can be suitably used for the production of shoes and other leather products.

DESCRIPTION OF SYMBOLS 1 Artificial leather 2 Drum 3 Belt 4 Pressure roller 5a, 5b Turn roller 6 Shrinking artificial leather 11 Metal roller 12 Thick rubber part 13 Rubber roller 14 Shrinking artificial leather

Claims (7)

(1) a process of forming ultrafine fibers into a web;
(2) A step of entangled the obtained web to produce an entangled nonwoven fabric,
(3) impregnating the obtained entangled nonwoven fabric with a polymer elastic body and solidifying it,
(4) An ultra-fine fiber obtained by micronizing the entangled non-woven fabric that does not contain the polymer elastic body obtained in the step (2) or the ultrathin fiber in the polymer elastic body-containing non-woven fabric obtained in the step (3) A process for producing a substrate for artificial leather comprising a fiber bundle of
(5) a process for producing artificial leather using the obtained artificial leather substrate, and (6) the obtained artificial leather is closely attached to an elastic sheet that is stretched 5 to 40% in the vertical direction, and the elastic body The elastic sheet is contracted in the vertical direction by relaxing the extension of the sheet, the artificial leather is contracted in the vertical direction, the contracted state of the artificial leather is heat-set, and then the artificial leather is separated from the elastic sheet. A method for producing stretchable artificial leather including a process. The method for producing stretchable artificial leather according to claim 1, wherein the elastic sheet is a sheet of natural rubber or synthetic rubber. The elastic sheet is part thickness, and the elastic sheet is run while contacting the roller surface, and the elastic sheet is stretched in the vertical direction by utilizing the difference between the inner and outer circumferences, and then the stretching is relaxed. The method for producing a stretchable artificial leather according to claim 1 or 2, wherein the elastic sheet is elastically recovered and the artificial leather is contracted in a traveling direction. The manufacturing method of the stretchable artificial leather of any one of Claims 1-3 heat-set by the ironing effect of a heating cylinder. The method for producing stretchable artificial leather according to any one of claims 1 to 4, wherein the artificial leather is preheated, humidified, or both treated before the artificial leather is brought into close contact with the elastic sheet. The method for producing stretchable artificial leather according to any one of claims 1 to 5, wherein the polymer elastic body is a solidified product of an aqueous polyurethane emulsion. The method for producing a stretchable artificial leather according to any one of claims 1 to 6, wherein the ultrafine fiber is an inelastic fiber.