JP2000199184A - Leather-like sheet and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a leather-like sheet having soft feeling, excellent abrasion resistance and drapeability and crease appearance of folded surface having feeling integrated with a substrate by successively laminating a nonporous polyurethane resin layer and a layer having a prescribed porous structure on the surface of a specific substrate. SOLUTION: The objective leather-like sheet is produced by successively laminating a layer B of a nonporous polyurethane resin and a layer C having a porous structure and containing a polyurethane resin having a weight loss of >=95% with dimethylformamide solvent in the form of a film and a polyurethane resin having a weight loss of <=5% at a weight ratio of 10/90 to 90/10 on the surface of a substrate A composed of an entangled nonwoven fabric composed of ultrafine fiber of polyethylene terephthalate, or the like, having a fineness of <=0.5 de and a polymeric elastomer. The thickness of the polyurethane resin layers B and C are preferably 5-45 μm each.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a grain-finished leather-like sheet having both abrasion resistance, flexibility and drapeability on the surface, and having a surface with a sense of unity with the substrate, and a method for producing the same. It is.

[0002]

2. Description of the Related Art Conventionally, a leather-like sheet with a silver finish is prepared by forming a thick polyurethane resin coating layer by a dry surface method in order to eliminate irregularities on the surface of a woven fabric or a foam coating of a polyurethane resin. A so-called synthetic leather type in which a layer is formed and a non-porous coating layer is further formed thereon has been proposed, but it is generally a semi-hard type, and those pursuing softness have a rubber-like surface. It is. On the other hand, a type in which a non-porous coating layer of an elastic polymer is formed on the surface of a sheet made of an entangled nonwoven fabric and an elastic polymer composed of ultrafine fibers or fibers having a normal thickness, and an elastic polymer Finished with a porous coating layer or laminated with a porous coating layer of an elastic polymer and a non-porous coating layer have also been proposed. It will be. For the formation of a porous layer on the surface, a wet coagulation method in which a solution of an elastic polymer is treated with a non-solvent of the elastic polymer to coagulate into a porous material, and salts, starch, gelatin, etc. are easily extracted into the elastic polymer solution. After coating and drying a composition liquid containing a mixture of conductive fine particles, or after kneading the easily extractable fine particles into an elastic polymer to form a sheet, a method of extracting and removing the fine particles to form a porous structure,
A method in which a composition liquid obtained by mixing a foaming agent with an elastic polymer solution is applied and dried to form a foamed porous structure is used.

Further, a polyurethane resin layer obtained by mixing a water-soluble natural organic substance such as gelatin or starch, or a fine powder of a water-soluble organic compound such as ammonia-modified maleic anhydride and isobutylene copolymer is provided on the surface of the wet porous layer. After the formation, the water-soluble fine powder is dissolved and removed to form a porous coating layer, as disclosed in JP-A-2-91279, JP-A-2-169777, JP-A-2-3077987, and JP-A-6-307987. It has been proposed in JP-A-330474.

[0004]

As described above, there have been various kinds of leather-like sheets which have been conventionally proposed, which are characterized by softness. All of them have excellent softness, drapability and high-grade surface. In addition, materials for high-grade clothing, various gloves and bags, soft general shoes, sports shoes, and other silver-based preparation products that also require abrasion resistance on the surface have not yet been developed. That is, in the method of providing a porous wet film as a surface layer, a thick film is required to obtain smoothness of the surface, so that the texture becomes hard, and a non-porous dry film is used as a finishing layer on the porous wet film. In the method of applying a film, the surface layer becomes hard, and the balance with the substrate tends to be lost, resulting in a lack of unity.

[0005] On the other hand, a method of providing a nonporous film or a porous film by a dry surface method or the like can produce a relatively thin film, but lacks a sense of quality on the surface and is flexible for use in clothing and various gloves. , Drape property was insufficient. Also, the method of forming a polyurethane resin layer in which a water-soluble fine powder is mixed on the surface of the wet porous layer and dissolving and removing the water-soluble fine particles to form a porous coating layer, the thickness of the wet microporous coating layer is reduced. Insufficient flexibility and drapability for thin clothing, various gloves and other applications due to the large pore size of the porous coating layer obtained by removal and removal due to the particle size of the water-soluble fine powder. However, the abrasion resistance of the surface was insufficient. An object of the present invention is to provide a silver-finished leather-like sheet having both abrasion resistance, flexibility and drapability on the surface, and having a surface with a textured crease, and a method for producing the same.

[0006]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies focusing on the structure of the coating layer, and as a result, have found that a base material composed of an entangled nonwoven fabric of ultrafine fibers of 0.5 denier or less and an elastic polymer. A non-porous polyurethane resin layer (B) on the surface of (A),
Dimethylformamide of resin after film formation (abbreviated as DMF)
A polyurethane resin having a weight loss of 95% or more due to a solvent and a polyurethane resin having a weight loss of 5% or less are 10: 9 by weight.
A leather-like sheet in which a layer (C) having a porous structure mixed in the range of 0 to 90:10 is sequentially laminated to solve the above-mentioned problem, and further such a leather-like sheet Is obtained by coating a nonporous polyurethane resin layer (B) on the surface of a base material (A) composed of an entangled nonwoven fabric of ultrafine fibers of 0.5 denier or less and a polymer elastic body, and a DMF solvent of a resin after film formation. A polyurethane resin having a weight loss of 95% or more and a polyurethane resin having a weight loss of 5% or less are 10:90 by weight.
To 90:10, and more preferably obtained by sequentially laminating layers (C) having a porous structure, more preferably on a release sheet, after forming a film. A layer having a porous structure of a polyurethane resin having a weight loss rate of the resin of DMF solvent of 95% or more is formed, and a polyurethane resin solution having a weight loss rate of the resin after film formation of 5% or less by the DMF solvent is formed thereon. A part of the solution is applied to penetrate the layer having a porous structure, and is present as a resin liquid layer on the layer. When the resin liquid layer has tackiness, , And a substrate (A) composed of an elastic polymer and an entangled nonwoven fabric of ultrafine fibers of 0.5 denier or less, and then peeling off the release sheet.

The substrate (A) used in the present invention is a sheet composed of an entangled nonwoven fabric of ultrafine fibers of 0.5 denier or less and an elastic polymer, and of course, it may be laminated with other sheets. Good. Preferably, the surface on the side on which the layer (B) described later is laminated is made of an entangled nonwoven fabric of ultrafine fibers of 0.5 denier or less and an elastic polymer. Representative examples of the base material (A) used in the present invention include, for example, those in which the entire layer is made of an entangled nonwoven fabric of ultrafine fibers of 0.5 denier or less and an elastic polymer, or 0.5% on one surface of a woven fabric. Examples include a layer in which an entangled nonwoven fabric of ultrafine fibers of denier or less and a layer made of an elastic polymer are laminated and integrated.

In the present invention, the fineness of the ultrafine fibers constituting the layer (A) is 0.5 denier or less, and preferably 0.1 to 0.0001 denier. If it exceeds 0.5 denier, the bending stress of the single fiber becomes large, and the smoothness of the substrate surface becomes poor. On the other hand, if it is less than 0.0001 denier, the fiber strength becomes weak and the peel strength becomes inferior. Here, as a method for producing the ultrafine fibers constituting the surface of the base material, a mixed spinning method, a sea-island type composite spinning method, and a split type composite spinning method using two or more kinds of polymers having different solubility or degradability are used. A method of extracting or decomposing and removing a part (for example, a sea component) of the ultrafine fiber-generating fiber obtained by the spinning method such as the above, or forming a sheet having a nap structure after forming a sheet having a nap structure. Known ultrafine fibers such as a method of forming ultrafine fibers by decomposing and removing a portion (for example, a sea component), and a method of so-called melt-blowing, in which the fibers are blown off with a high-speed gas immediately after discharging a fiber-forming polymer from a melt spinning nozzle to thin the fibers. Can be used, but a method is preferred in which the fine fiber-generating fiber is used in view of the control of the fiber thickness and the stability of the fine fiber.

Examples of the resin constituting the ultrafine fibers include polyesters containing aromatic rings such as polyethylene terephthalate and polybutylene terephthalate, polyamides such as nylon-6, nylon-66 and nylon-610, polyethylene and polypropylene. Examples include polymers selected from known resins such as polyolefins.

Examples of the resin component constituting the ultrafine fiber-generating fiber which are extracted or decomposed and removed include polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, polystyrene and styrene-acryl. At least one polymer selected from polymers such as a system monomer copolymer and a styrene-ethylene copolymer is exemplified.

Next, as a method for forming a substrate using the above-mentioned ultrafine fibers or ultrafine fiber-generating fibers, there are known methods, for example, a step of producing an entangled nonwoven fabric comprising the ultrafine fiber-generating fibers, The step of impregnating and coagulating an elastic polymer solution and the step of modifying ultrafine fiber-generating fibers into ultrafine fibers are sequentially performed. Needless to say, the step of modifying into ultrafine fibers and the step of impregnating and coagulating an elastic polymer may be reversed.

As a method for producing an entangled nonwoven fabric using the ultrafine fiber-generating fiber, the ultrafine fiber-generating fiber is subjected to spinning, drawing, heat setting, crimping, cutting, and the like by a conventionally known method. Thus, a raw cotton of the same fiber is produced, and the raw cotton is defibrated with a card and formed into a random web or a cross-wrap web with a weber. The resulting web is laminated as needed to the desired weight. The weight of the web is appropriately selected according to the intended final use field, and generally, the range of 100 to 3000 g / m ² is desirable. When a thin leather-like sheet used for clothing or the like is intended, an entangled nonwoven fabric having a weight about twice the required weight is impregnated with an elastic polymer solution and then divided in the thickness direction with a band knife or the like. Thereby, two base materials can be efficiently manufactured at once. Next to the lamination of the web, an entangled nonwoven fabric is formed by performing an entanglement treatment using a known means, for example, a needle punching method or a high-pressure water jet method. The number of needle punching and the conditions for needle punching vary depending on the shape of the needle used and the thickness of the web, but are generally preferably set within the range of 200 to 2500 punches / cm ² .

Prior to the process of containing the elastic polymer, the surface of the entangled nonwoven fabric can be subjected to a smoothing treatment by a known method such as hot pressing, if necessary. When the fiber constituting the entangled nonwoven fabric is, for example, a multicomponent fiber having polyethylene as a sea component and polyester or polyamide as a very fine island component, the surface component is extremely fused by fusing the sea component polyethylene with a hot press. It is particularly preferable because an entangled nonwoven fabric having excellent smoothness can be obtained. In addition, when the fibers constituting the entangled nonwoven fabric are not multicomponent fibers that can be dissolved and removed as one component to be modified into ultrafine fibers, the elastic polymer contained therein is prevented from sticking to the fibers and hardening the hand. Therefore, it is preferable to cover the fiber surface with a temporary filling material such as polyvinyl alcohol before the impregnation. Also, in the case of a multicomponent fiber which can be made into an ultrafine fiber by dissolving and removing one component, a more flexible sheet can be obtained by providing the temporary filling substance at the stage of the entangled nonwoven fabric.

As the elastic polymer to be contained in the entangled nonwoven fabric, known ones can be used, but it is preferable to use a polyurethane resin from the viewpoint of feeling. Preferred polyurethane resins are selected from the group consisting of polyester-based diols, polylactone-based diols, polycarbonate-based diols, and polyether-based diols obtained by reacting a diol with a dicarboxylic acid or an ester-forming derivative thereof as a soft segment. A so-called segmented polyurethane obtained by using at least one kind of polymer diol having a number average molecular weight of 500 to 5,000 and reacting this with a diisocyanate compound and a low molecular chain extender is used.

The diol compound constituting the soft segment is preferably a compound having 6 to 10 carbon atoms in terms of durability or leather-like texture.
-Methyl-1,5-pentanediol, 1,6-hexanediol, 2-methyl-1,8-octanediol,
Examples thereof include 1,9-nonanediol and 1,10-decanediol. Representative examples of dicarboxylic acids include aliphatic dicarboxylic acids such as succinic acid, glutaric acid, adipic acid, azelaic acid and sebacic acid, and aromatic dicarboxylic acids such as terephthalic acid and isophthalic acid.

The number average molecular weight of the polymer diol is 500
If it is less than 10%, it is not preferable because it lacks flexibility and a natural leather-like texture cannot be obtained. When the number average molecular weight of the polymer diol exceeds 5,000, the urethane group concentration decreases, so that it is difficult to obtain a base sheet having a good balance in flexibility, durability, heat resistance and hydrolysis resistance. Examples of the low molecular chain extender include, for example, ethylene glycol, propylene glycol, butanediol,
Low molecular compounds having two active hydrogen atoms such as hexanediol and ethylenediamine are exemplified. Examples of the diisocyanate compound include aromatic, aliphatic, and alicyclic compounds such as 4,4'-diphenylmethane diisocyanate, tolylene diisocyanate, phenylene diisocyanate, and xylylene diisocyanate. Also, if necessary, a pigment,
Dyes, coagulation regulators, stabilizers and the like may be added, and two or more polymers may be used in combination.

The method for incorporating the elastic polymer into the entangled non-woven fabric is not particularly limited, but a method of directly impregnating the entangled non-woven fabric with the elastic polymer solution and squeezing it with a mangle, if necessary, from the viewpoint of the balance of texture. And a method of impregnating an elastic polymer solution while coating it with a coater. From the viewpoint of natural leather-like soft texture, the weight ratio of the fibers constituting the sheet to the elastic polymer is preferably in the range of 30/70 to 80/20, more preferably in the range of 40/60 to 55/45. Is within. If the ratio of fibers is too low, the leather-like sheet with silver will have a rubber-like unfavorable texture, and if the ratio of fibers is too high, it will have a paper-like texture, and the target natural leather-like texture will be obtained. Absent.

After the elastic polymer is contained in the entangled nonwoven fabric, a non-solvent is used for the island component of the elastic polymer and the microfine fiber-generating fiber, and a solvent or a liquid acting as a decomposer is used for the sea component. By performing the treatment, the ultrafine fiber-generating fibers are modified into an ultrafine fiber bundle, and a sheet made of the ultrafine fiber entangled nonwoven fabric and the elastic polymer, that is, a substrate (A) is obtained. Needless to say, the sheet may be formed by a method of modifying the ultrafine fiber-generating fibers into an ultrafine fiber bundle prior to containing the elastic polymer. A desired base material can also be obtained by laminating a sheet obtained by the above method as a front surface and a known sheet such as a knitted woven fabric as a backing material by a known method on the back surface.

Next, a nonporous polyurethane resin layer (B), which is laminated and integrated on the surface of the base material (A), and a polyurethane resin having a weight loss rate of 95% or more of the resin after film formation with a DMF solvent. The surface coating layer composed of the layer (C) having a weight loss ratio of 5% or less of a polyurethane resin mixed in a weight ratio in the range of 10:90 to 90:10 and having a porous structure is a leather with silver finish. It is indispensable to achieve a high level of compatibility between physical properties such as abrasion resistance and scratch resistance of the sheet surface and sensitivity aspects such as surface smoothness, flexibility, and good crimping. That is, the polyurethane resin layer (B) is located at an intermediate position between the base material (A) and the polyurethane resin layer (C) to create characteristics such as surface smoothness and flexibility of the silver-finished leather-like sheet. In the adhesion between the material (A) and the polyurethane resin layer (C), a texture with a feeling of unity that is preferable for the silver-finished leather-like sheet is created.

In order to impart the above characteristics to the polyurethane resin layer (B), it is essential that the polyurethane resin layer (B) be substantially nonporous. The flexibility of the polyurethane resin constituting this layer (B) is such that the 100% modulus after film formation is 5 to 50 kg.
/ Cm ² , the thickness of the polyurethane resin layer (B) is 5 to 45
It is preferably μm. When the 100% modulus after the formation of the polyurethane resin is less than 5 kg / cm ² , the strength of the polyurethane resin layer (B) becomes low, and
If it exceeds cm ² , the texture of the polyurethane resin layer (B) becomes hard, and the sense of unity of the silver-finished leather-like sheet is lost. When the thickness of the polyurethane resin layer (B) is less than 5 μm, the adhesive strength between the base material (A) and the polyurethane resin layer (C) cannot be sufficiently obtained, and the surface of the leather-like sheet with silver becomes smooth. When the thickness exceeds 45 μm, the texture of the grain-finished leather-like sheet becomes hard and does not have a sense of unity.

The polyurethane resin layer (C) is the most important part of the present invention, and the polyurethane resin layer (C) described below is required to achieve the desired flexibility, drapability and abrasion resistance of the grain-finished leather-like sheet. The configuration of C) is indispensable. The polyurethane resin layer (C) has a weight ratio of the polyurethane resin having a weight loss rate of 95% or more and the polyurethane resin having a weight loss rate of 5% or less of the polyurethane resin after film formation in a range of 10:90 to 90:10 by weight ratio. And a layer having a porous structure. The flexibility of the polyurethane resin used is 100% modulus after film formation.
It is preferably 30 kg / cm ² , and the thickness of the polyurethane resin layer (C) is preferably 5 to 45 μm. The polyurethane resin having a weight loss of 95% or more and the polyurethane resin having a weight loss of 5% or less due to a DMF solvent after film formation mixed with the polyurethane resin layer (C) are known materials per se. Is obtained by drying and solidifying a one-component polyurethane resin solution, and the latter is obtained by drying and solidifying a two-component polyurethane resin solution.

The one-pack type polyurethane resin is obtained by reacting an organic diisocyanate with a high molecular weight diol and, if necessary, a low molecular weight bifunctional active hydrogen compound in the vicinity of an equivalent of NCO / OH ratio. Examples of the organic diisocyanate include 4,4′-diphenylmethane diisocyanate (M
DI), 2,4-tolylene diisocyanate, 2,6-
Aromatic diisocyanates such as tolylene diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, 1,5-naphthalene diisocyanate, 1,6-hexamethylene diisocyanate,
Examples include aliphatic diisocyanates such as 3-xylylene diisocyanate, 1,4-xylylene diisocyanate, and lysine diisocyanate, and alicyclic diisocyanates such as isophorone diisocyanate, hydrogenated MDI, and hydrogenated TDI. As the polymer diol, for example, polyethylene adipate, polyethylene propylene adipate, polyethylene butylene adipate, polydiethylene adipate, polybutylene adipate, polyhexamethylene adipate, polyethylene sebacate, polybutylene sebacate, poly-ε-caprolactone diol, polycarbonate polyol And polyether diols such as polyethylene glycol, polypropylene glycol and polytetramethylene ether glycol, and polyether ester diols, and mixtures thereof.

The two-pack polyurethane resin comprises two components, an active hydrogen component and an NCO component. Among them, the active hydrogen component is obtained by reacting a high molecular weight diol with a diisocyanate compound, and optionally a divalent low molecular weight active hydrogen compound. And a polymer having an active hydrogen atom at the terminal. As the high molecular diol and diisocyanate compound used for the active hydrogen component, those described above can be similarly used, and as the divalent low molecular active hydrogen compound, ethylene glycol, butanediol, and other low molecular diamines are used. No. As the NCO component, which is the other component of the two-component polyurethane,
A trivalent or higher valent compound having an NCO group at its terminal, for example, an adduct of trimethylolpropane (TMP) and tolylene diisocyanate, an adduct of TMP and 4,4'-methylenebis (cyclohexyl isocyanate) (HMDI), and an adduct of TMP and hexa Examples include an adduct of methylene diisocyanate, an adduct of TMP and isophorone diisocyanate, and a trimer of HMDI.

In the present invention, the 100% modulus of the polyurethane resin constituting the layer (C) after film formation is 5 kg /
If it is less than ² cm ² , the abrasion resistance of the surface and the strength of the polyurethane resin layer (C) will be low, and if it exceeds 50 kg / cm ² , the texture of the polyurethane resin layer (C) will be hard and a sense of unity of the leather-like sheet with silver will be obtained. Is gone. If the thickness of the polyurethane resin layer (C) is less than 5 μm, the strength and wear resistance of the surface of the polyurethane resin layer (C) cannot be sufficiently obtained, and
If it exceeds m, the texture of the silver-finished leather-like sheet becomes hard and does not have a sense of unity.

As a method for forming the layer (C), first, a polyurethane resin layer having a porous structure having a weight loss of 5% or less is formed by a dry method, and the polyurethane resin layer having a weight loss of 95% or more is formed in voids of the porous structure. A method of filling a resin or a method of forming a polyurethane resin layer having a porous structure with a weight loss of 95% or more and then filling the voids of the porous structure with a polyurethane resin having a weight loss of 5% or less, etc. . Methods for obtaining a polyurethane resin layer having a porous structure include a method using a foaming agent, a method of foaming by reaction, a method of using a mechanically foamed coating film, a method of using extractable particles, and the like. Although not necessarily, in the present invention, since a method is preferably used in which a porous polyurethane resin layer is formed and then another polyurethane resin is filled into voids of the porous structure, the porous polyurethane resin layer is formed over the entire porous polyurethane layer. It is desirable that the micropores are continuous, and a method in which independent bubbles are easily formed is not preferable.

The porosity of the porous structure of the one-component polyurethane resin dry film is preferably in the range of 20 to 70%. Depending on the type and physical properties of the polyurethane resin, as the porosity increases, the dry film itself with a porous structure is flexible, but the flexibility of the surface coating layer formed by filling the two-component polyurethane resin is relatively hard. The flexibility of the two-component polyurethane resin greatly depends on the flexibility, and therefore the flexibility is inferior. Conversely, if the porosity is too low, the softness is poor and the surface strength is low.

The method of forming the intermediate coating layer includes a method in which a polymer composition solution is applied to the surface coating layer formed on the release sheet by bar coating or knife coating and then bonded to a base sheet. Although there is a method of directly applying the coalescing composition liquid, the former is preferred from the viewpoint of the surface smoothness of the surface coating layer and the sense of unity between the intermediate coating layer and the base sheet. As described above, the elastic polymer which is the main constituent of the intermediate coating layer is preferably a polyurethane resin, and the type thereof is selected in consideration of the overall texture, peeling strength, etc., as long as the compatibility with the polyurethane resin of the base sheet is good. Can be selected. That is, the polyurethane resin used as the coating layer may be the same type of polyurethane resin as the polyurethane resin for the base sheet or a different type of polyurethane resin. The concentration of the polyurethane resin composition solution to be applied, the type and amount of the additive, and the like can be appropriately selected depending on the required physical properties of the intermediate coating layer, the forming conditions, and the like. Particularly, the polyurethane resin used for the intermediate coating layer has a surface coating. The layer is preferably the same as the polyurethane resin filling the voids having a uniform and dense porous structure made of a one-pack type polyurethane resin, and in such a case, it is selected from a two-pack type polyurethane resin.

The surface coating layer is the most important part of the present invention. That is, it can be said that the flexibility and drapability are largely determined by the configuration of the surface coating layer. The wet method is not suitable for forming a mixed layer of a one-pack type polyurethane resin and a two-pack type polyurethane resin, which is essential in the composition of the surface coating layer of the present invention, in terms of workability and the like. Preferably, the surface coating layer is formed by a method of forming a dense one-component polyurethane resin dry film of a porous structure by a dry method and then filling the voids of the porous structure with a two-component polyurethane resin. In general, methods for obtaining a dry film having a porous structure include a method using a foaming agent, a method for foaming by reaction, a method using a mechanically foamed coating film, a method using extractable particles, and the like, and are particularly limited. Although not limited to this, in the present invention, it is preferable to form a porous layer with a one-component polyurethane resin and then fill the voids of the porous structure with a two-component polyurethane resin.

The above-mentioned (A) thus obtained,
In the leather-like sheet composed of (B) and (C), a desired color can be imparted by adding a coloring agent such as a pigment or a dye to at least one of the resins forming the layer. In addition, by adding a softening agent to the layer (C), it is possible to have a softness similar to that of natural leather. Further, if necessary, the surface of the leather-like sheet thus obtained may be subjected to coloring or softening treatment. The leather-like sheet of the present invention can be used as a material for bags and shoes, as well as clothing such as jackets, skirts, coats, and other small articles represented by belts.

[0030]

Next, embodiments of the present invention will be described with reference to specific examples, but the present invention is not limited to these examples. The parts and percentages in the examples relate to weight unless otherwise specified. Further, as defined in the present invention, the weight loss rate of the resin after film formation by the DMF solvent is, after forming the film to a thickness of about 100 μm, 1g is precisely weighed, and a sample cut into a square of about 1 cm square, The residue is obtained by immersing in about 500 cc of a DMF solvent at about 40 ° C. and stirring for 1 hour, drying the residue after filtration, and weighing the residue. The 100% modulus after film formation was set to an autograph with a sample cut into strips after forming a film to a thickness of about 100 μm, and a gripping interval of 10 c
m, elongation curve measured at a tensile speed of 10 cm / min.
It is the value obtained by reading the stress corresponding to 00% elongation and dividing by the sample cross-sectional area.

Example 1 Nylon-6 and polyethylene were mixed in a chip form in a ratio of 50: 5.
The mixture was mixed at a weight ratio of 0 and spun with an extruder to spin sea-island fibers (nylon-6 was an island component, polyethylene was a sea component), stretched, crimped, and cut to 4 denier, 51 mm.
A long short fiber is produced, a cross wrap is made with a weber, and a needle punching machine is used to make 1500 punches / cm ^2.
Was subjected to needle punching to obtain an entangled nonwoven fabric. A polyurethane resin (poly 3-methyl-
After impregnating with a dimethylformamide solution of 1,5-pentane adipate diol and a polyethylene diol having an average molecular weight of 2,000 comprising polyethylene glycol and 4,4'-diphenylmethane diisocyanate and butanediol) and wet coagulating, a fiber component is obtained. The sea component is extracted with toluene at 80 ° C, and the basis weight is 27.
A base layer having 0 g / m ² , a thickness of 0.8 mm, and a ratio of polyurethane resin to fiber of 55/45 was obtained. The fineness of the nylon ultrafine fibers of the obtained sheet is 0.006 denier,
And it had a soft leather-like texture. One surface of the obtained substrate layer was buffed with sandpaper to obtain a substrate having a raised surface made of the nylon ultrafine fibers. Next, it was dyed with a circular dyeing machine under the following conditions.

Dyeing conditions Kayakaran Black 2RL (manufactured by Nippon Kayaku) 4% (owf) Dyeing aid 1 g / l Dyeing temperature 90 ° C. After drying, a black soft base material having excellent mechanical properties was obtained.

One-pack type polyurethane resin solution (manufactured by Dainichi Seika Kogyo Co., Ltd., Heimlen X-3040: DM after film formation)
100 parts of the weight loss rate by the F solvent, 100% modulus after film formation is 38.4 kg / cm ² ), 100 parts of black colorant, 18 parts of methyl ethyl ketone (MEK), 18 parts of toluene, and 50 parts of water in a homomixer. The solution prepared by sufficiently stirring the solution is directly coated on release paper having a grain pattern so that the coating amount is 80 g / m ² (Wet), and then dried at 120 ° C. for 2 minutes to obtain a uniform and dense pore. A polyurethane resin surface coating layer [C] having a porous structure was obtained. On this polyurethane resin surface coating layer [C], a two-pack type polyurethane resin solution (manufactured by Dainichi Seika Kogyo Co., Ltd., Rezamin UD-8310 Rev .: Weight loss rate by DMF solvent after film formation is 0.8%, film formation Later 100% modulus 24.5
kg / cm ² ) 100 parts, black colorant 20 parts, crosslinking agent 8
Part, 5 parts of an accelerator, 80 parts of methyl ethyl ketone, and 20 parts of dimethylformamide (DMF) were thoroughly stirred with a homomixer and directly coated with a liquid to a coating amount of 80 g / m ² (Wet). C. for 2 minutes to form a polyurethane resin intermediate coating layer [B]. The composite substrate sheet [A] was bonded onto the polyurethane resin intermediate coating layer [B] with a clearance roll, dried at 80 ° C. for 2 minutes, and aged at 50 ° C. for 3 days, and then the release paper was peeled off. Then, a leather-like sheet in which a polyurethane resin surface coating layer [C], a polyurethane resin intermediate coating layer [B] and a composite substrate sheet [A] were laminated was obtained.

A 70% apparent concentration ethyl acetate solution of a polyamino acid resin finishing agent (A-3571-60, manufactured by Seiko Chemical Co., Ltd.) was applied on the surface coating layer [C] of the leather-like sheet at a coating amount of 30 g / m ² (Wet) and dried at 120 ° C. to form a polyamino acid resin finishing layer [IV], and then a silicon softening agent (Nikka Silicon AM-204, manufactured by Nikka Chemical Co., Ltd.) )
Was subjected to Dip-Nip treatment and dried, and further subjected to mechanical kneading treatment to finish artificial leather with a silver surface.

The finishing layer [IV], the surface coating layer [C] and the intermediate coating layer [B] formed on the surface of the artificial leather having a silver surface.
The longitudinal section of the coating layer in which the three layers were laminated was enlarged and photographed with a scanning electron microscope, and the average thickness of the coating layer was measured. As a result, the total thickness of the coating layer was about 45 μm, and Each has a finish layer [IV] of about 2 μm and a surface coating layer [C]
Was about 13 μm, and the thickness of the intermediate coating layer [B] was about 30 μm. In addition, as a result of observing the cross-sectional state of this coating layer, the surface coating layer [C] was formed of a two-pack type polyurethane resin constituting the intermediate coating layer [B] with voids having a uniform and dense porous structure made of a one-pack type polyurethane resin. It had a partially filled structure. The resulting artificial leather with a silver surface combines excellent wear resistance of the silver side surface and a very soft texture with rich drape properties, and also has a natural leather-like luxury in appearance and touch, It was very preferable as a material for products with a silver layer such as clothing, various gloves and bags, soft general shoes and sports shoes.

Comparative Example 1 In the step of laminating a polyurethane resin coating layer comprising a surface coating layer [C '] and an intermediate coating layer [B] on the substrate used in Example 1, the surface coating layer [C'] In a liquid preparation, a liquid prepared without mixing 50 parts of water was used.
Except for drying for 00 minutes, the same processing as in Example 1 was performed.
Finishing layer [IV], surface coating layer [C '], intermediate coating layer [B]
And an artificial leather with a silver surface on which the base sheet [A] was sequentially laminated.

The finishing layer [I
V], a longitudinal section of the coating layer consisting of the surface coating layer [C '] and the intermediate coating layer [B] was enlarged and photographed by a scanning electron microscope, and the cross-sectional state of this coating layer was observed. The resin surface coating layer [C '] was a non-porous layer, and the two-pack polyurethane resin constituting the intermediate coating layer [B] did not substantially penetrate the [C'] layer. The obtained artificial leather with a grain surface is far inferior to that of Example 1 in the point of soft texture, and further inferior to Example 1 in the abrasion resistance of the surface on the silver surface side. It was insufficient as a material for products with a layer of silver such as various gloves and bags, soft general shoes and sports shoes.

Comparative Example 2 In Example 1, a one-pack type polyurethane resin solution (Resamine ME-8105, manufactured by Dainichi Seika Kogyo Co., Ltd.) was used without preparing a two-pack type polyurethane resin solution in preparing the liquid for the intermediate coating layer.
LP: 100% of weight loss due to DMF solvent after film formation, 100% modulus after film formation is 41.2 kg / cm ² ), and a coating amount of a liquid prepared without using a crosslinking agent or an accelerator. Of 80 g / m ² on the surface coating layer [C], and the substrate sheet [A] is adhered with a clearance roll without drying the liquid.
A finishing layer [IV], a surface coating layer [C], an intermediate coating layer [B "], and a base sheet by the same treatment as in Example 1 except that the adhesive layer [B"] is formed by drying at 2 ° C. for 2 minutes. [A]
Were sequentially laminated to obtain artificial leather with a silver surface.

The finishing layer [I
V], a longitudinal section of the polyurethane resin coating layer composed of the surface coating layer [C] and the intermediate coating layer [B ″] was enlarged and photographed with a scanning electron microscope, and the cross-sectional state of this coating layer was observed. In the cross-sectional state of the layer and the intermediate coating layer, the surface coating layer [C] has a uniform and dense porous structure made of the one-pack type polyurethane resin and a part of the one-pack type polyurethane resin constituting the intermediate coating layer [A ″]. Most of the one-pack type polyurethane resin constituting the intermediate coating layer [B "] has a structure filled with the voids close to the surface by penetrating into the very porous substrate sheet [A]. That is, in this leather-like sheet, there is no layer that satisfies the layer (C) defined in the present invention. Features leather-like appearance and touch However, compared to Example 1, it has poor drape property and has a hard texture, and the abrasion resistance of the surface on the silver side is inferior to that of Example 1. Clothing, various gloves and bags, soft general shoes and It was unsuitable as a material for products with a silver layer such as sports shoes.

[0040]

The artificial leather with a silver surface according to the present invention has an intermediate coating while using a soft one-pack type polyurethane resin for the surface coating layer to reduce the layer thickness so that the artificial leather as a whole has a soft texture. One-pack type by integrating the surface coating layer and the composite substrate sheet while using a part of the two-component polyurethane resin used for the layer to form a structure in which the surface coating layer is densely reinforced over all layers It is an artificial leather that has never been seen before and has a dramatically improved surface abrasion resistance while giving a feeling of unity utilizing the flexibility of polyurethane resin as much as possible.

 ──────────────────────────────────────────────────の Continued on the front page F-term (reference) 4F055 AA01 AA27 BA12 BA16 CA15 DA10 EA11 EA14 EA24 EA30 FA15 GA01 GA11 4F100 AK01A AK48A AK51B AK51C AL05C AL09A BA03 BA07 BA10A BA10C BA15 DG15A DH00A DJ00J00C

Claims (3)

[Claims] 1. A nonporous polyurethane resin layer (B) on the surface of a base material (A) comprising an entangled nonwoven fabric of ultrafine fibers of 0.5 denier or less and an elastic polymer, and a resin dimethyl after film formation. A layer having a porous structure in which a polyurethane resin having a weight loss of 95% or more and a polyurethane resin having a weight loss of 5% or less by a formamide solvent are mixed in a weight ratio of 10:90 to 90:10 ( A leather-like sheet on which C) is sequentially laminated. 2. A nonporous polyurethane resin layer (B) on the surface of a base material (A) comprising an entangled nonwoven fabric of ultrafine fibers of 0.5 denier or less and a polymer elastic material, and a resin after film formation. A layer having a porous structure in which a polyurethane resin having a weight loss of 95% or more and a polyurethane resin having a weight loss of 5% or less by a dimethylformamide solvent are mixed in a weight ratio of 10:90 to 90:10 ( A method for producing a leather-like sheet, wherein C) is sequentially laminated. 3. A layer having a porous structure composed of a polyurethane resin having a weight loss of 95% or more of a resin after film formation by a dimethylformamide solvent is first formed on a release sheet. A polyurethane resin solution having a weight loss of 5% or less by a dimethylformamide solvent of the later resin is applied to allow a part of the solution to permeate the layer having a porous structure and to be present as a resin liquid layer on the layer. When the resin liquid layer has tackiness, 0.5
A method for producing a leather-like sheet, comprising: adhering a base material (A) made of an elastic polymer and an entangled nonwoven fabric of ultrafine fibers of denier or less, and then releasing the release sheet.