JP5374299B2 - Manufacturing method of silvered leather-like sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a grained leather-like sheet which has a texture giving a sense of oneness and flexibility, has a high grade appearance free from the irregularity of gloss, and giving a sense of fulfillment similar to that of natural leather. <P>SOLUTION: There is provided the method for producing the leather-like sheet, including coating and drying a liquid obtained by foaming an aqueous polyurethane dispersion into a one and half to fourfold volume on at least one side of a substrate layer comprising a fiber-interlaced nonwoven fabric arbitrarily impregnated with a polyurethane to form a foamed coating layer, and then integrally laminating a polyurethane nonwoven fabric to the foamed coating layer. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  In the present invention, the surface has a silver surface layer composed of a molten layer of a polyurethane nonwoven fabric in which micropores are formed, and foaming is performed between the silver surface layer and the underlying substrate layer. By integrating and laminating with a coat layer, it has a texture and flexibility with a sense of unity, has a high-grade appearance without uneven gloss, and has a solid feel similar to natural leather. It relates to a manufacturing method.

  Conventionally, many proposals have been made regarding methods for producing a leather-like sheet having a silver surface. Many of these proposals are methods for forming a silver surface by providing a wet solidified layer or a dry solidified layer made of a polymer elastic body on one surface of a fiber sheet. In addition, many proposals have been made for a method for producing a silver-finished leather-like sheet having air permeability and moisture permeability. These methods include a method of laminating a breathable foam coat layer formed by a wet coagulation method or a dry coagulation method by adding a foaming agent, an additive, a coagulation regulator, or the like to the fiber surface, or by a laser beam or the like. For example, a hole is made in the surface silver layer.

As a method for producing a leather-like sheet having a natural leather-like appearance and having air permeability and moisture permeability, a method of heat-melting the surface of a fibrous sheet containing a polymer elastic body, or a fiber or elastic body on the surface There has also been proposed a method of forming a silver surface by applying a solvent (1) to melt the fiber or polymer elastic body constituting the surface of the sheet to smooth the surface (see, for example, Patent Documents 1 to 3). Furthermore, an ultrafine fiber raised surface is formed on the surface of the fiber entangled body, a fiber solvent or swelling agent is applied, the fibers are joined by hot pressing to smooth the surface, and a coating layer of a polymer elastic body is provided on the surface. A method for producing a leather-like sheet is also known. Patent Document 4 proposes a method of forming a surface while directly bonding a polyurethane nonwoven fabric to a base fabric.
Further, in Patent Document 5, a porous foam containing a resin is included in a base fabric, and when forming a leather-like film layer on the surface of the base fabric, one side of the base fabric on the side on which the leather-like film layer is formed In addition, a sheet structure in which a porous foam is included at a high density has been proposed.
Further, Patent Document 6 proposes a leather-like sheet that is excellent in volume feeling and air permeability by laminating a hot melt nonwoven fabric layer on a base material layer and providing a colored layer thereon.

Japanese Patent Publication No. 48-535 Japanese Patent Publication No. 48-536 Japanese Patent Publication No. 48-537 Japanese Patent Laid-Open No. 10-8382 JP 2003-3379 A JP 2008-63674 A

  However, a breathable foam coat layer formed by a wet coagulation method or a dry coagulation method is added to the surface of the fiber layer by adding a foaming agent, an additive, a coagulation regulator, etc., as in the conventionally proposed method. The sheet obtained by this method is not satisfactory in terms of air permeability. In addition, in this method, the silver surface also has problems such as strong rubber rebound and poor surface wrinkling. In the case of a method of making a hole in the surface coating layer with a laser or the like, although the air permeability is satisfactory, the appearance is lacking in luxury.

  Further, as in Patent Documents 1 to 3 and the like, in the case of a method of forming a silver surface by melting and smoothing the fibers and the polymer elastic body constituting the fibrous sheet by hot melting or a solvent, Although satisfactory in terms of moisture permeability, the surface becomes hard, lacking in solidity close to that of natural leather, and glossy unevenness in appearance occurs, resulting in lack of luxury.

  Further, as in Patent Document 4, in the method of making a surface while directly melting a polyurethane non-woven fabric into a base fabric, a high-quality appearance without uneven gloss is achieved by slowing the surface forming speed during production, Although a leather-like sheet with good air permeability can be obtained, since the polyurethane nonwoven fabric is bonded to the base fabric while being melted with heat, the melted polyurethane nonwoven fabric does not necessarily adhere to the base fabric. It is necessary to be fused at high temperature and / or high pressure in order to develop sufficient adhesion, and gloss unevenness is likely to occur due to this effect. There was also variation depending on the sampling position of the measurement sample. Furthermore, in order to achieve a quality closer to natural leather, when a dense base fabric is realized by keeping the polyurethane content as low as possible, the adhesiveness of the polyurethane nonwoven fabric to the base fabric is extremely reduced, This phenomenon becomes remarkable and is not preferable.

On the other hand, in the method described in Patent Document 5, when a porous foam containing a resin is included in a base fabric and a leather-like film layer is formed on the surface of the base fabric, the base on the side on which the leather-like film layer is formed. A sheet structure in which a porous foam is included at a high density on one side of the cloth, the cell diameter of the porous foam is composed of open cells in the range of 20 to 250 μm, and the air permeability of the sheet structure is 3 to 3. The sheet is 13 cm ³ / cm ² / sec and is a highly breathable sheet. However, the leather-like film layer is filled with a film material only on the concave and convex portions of the transfer paper having a concave and convex surface obtained by inverting the leather-like concave and convex surface, and this is overlapped with the base fabric to form the concave portion of the concave portion. Since the film material is transferred to form convex portions on the base fabric, the number of steps is required and the cost is high. Also, in terms of design, the sheet structure has a flat feeling and has a high-quality appearance. It is not possible to obtain a leather-like sheet having a solid feeling close to that of natural leather.
Furthermore, since the leather-like film layer contains a solvent, toxicity to the human body cannot be denied.
Further, in this method, since the number of resin layers and the constituent resins of the convex portion and the concave portion are different, the convex coat layer is easily peeled off due to friction during use.
In addition, the foamed resin used has sufficient durability (light resistance, weather resistance) even in the concave portion where the film material is not transferred to the surface after ensuring foamability and stability of the foam. In other words, there is a problem that usable resins and chemicals are limited.

Also, in the case of laminating a hot melt nonwoven fabric layer as in Patent Document 6, when a hot melt nonwoven fabric that has been similarly heat fused is fused to the base fabric, it is simultaneously fused to the base fabric (thermal embossing). It is easy to be fused to a device etc., and it is difficult to manufacture stably.
Furthermore, hot melt nonwoven fabrics usually have a large fiber diameter and uneven formation, so if this layer is not thickened, sufficient smoothness and luxury on the silver surface cannot be obtained, while sufficient smoothness is obtained. For this reason, when the basis weight of this layer is increased and the layer is thickened, the obtained silver-finished leather-like sheet has a hard texture.

As a result of intensive studies on a silver-finished leather-like sheet having a high-quality appearance and a sense of solidity close to natural leather, the present inventors have found that the fiber-entangled nonwoven fabric and the polymer elastic body contained therein A foamed coating layer is formed on at least one surface of the substrate layer by applying and drying a polyurethane aqueous dispersion foamed 1.5 to 6 times, and then a polyurethane nonwoven fabric is laminated on the foamed coating layer. It has been found that the above-mentioned problems can be solved by making them.
That is, the present invention
(1) Applying and drying a liquid obtained by foaming a polyurethane water dispersion 1.5 to 6 times on at least one surface of a base layer composed of a fiber-entangled nonwoven fabric impregnated with polyurethane arbitrarily, A silver- coated leather-like sheet manufacturing method in which a polyurethane non-woven fabric is laminated and integrated on the foam coat layer after forming , and the surface of the foam coat layer is 20 above the softening temperature of the polyurethane constituting the polyurethane non-woven fabric. A method for producing a silvered leather-like sheet, characterized in that a solution of a heat-adhesive resin having a temperature of ℃ or more is applied in the form of dots, and the polyurethane nonwoven fabric is immediately laminated and integrated ;
(2) After superposing the polyurethane nonwoven fabric, the polyurethane nonwoven fabric is temporarily bonded with an embossing roll having a surface temperature in the vicinity of the softening temperature of the thermal adhesive resin, and then an embossing roll having a surface temperature equal to or higher than the softening temperature of the polyurethane nonwoven fabric. The method for producing a silver-finished leather-like sheet according to (1), wherein the base layer and the foamed coat layer and the polyurethane nonwoven fabric are laminated and integrated together,
( 3 ) The method for producing a grained leather-like sheet according to (1) or (2) , wherein the polyurethane nonwoven fabric has a basis weight of 15 to 125 g / m ² .
( 4 ) The method for producing a silver-finished leather-like sheet according to any one of (1) to (3) , wherein the polyurethane in the polyurethane aqueous dispersion and the polyurethane impregnated in the fiber-entangled nonwoven fabric are the same. ,
( 5 ) The method for producing a grained leather-like sheet according to any one of (1) to ( 4 ), wherein the foam coat layer has a basis weight of 3 to 40 g / m ² .
(6) The silver-coated leather according to any one of (1) to (5) above, wherein the fiber-entangled nonwoven fabric of the base layer contains ultrafine elongated fiber nonwoven fabric and 0 to 20% by mass of polyurethane contained therein. Manufacturing method of the sheet,
I will provide a.

  According to the method for producing a silver-finished leather-like sheet of the present invention, the surface is composed of a silver surface having micropores having a polyurethane fiber bridging structure, and the silver surface and the foamed coating layer and the base layer below the silver surface. A silver-finished leather-like sheet that has a texture with a sense of unity between them, has a practically sufficient peel strength, has excellent air permeability and moisture permeability, and has a particularly excellent appearance with no uneven gloss. Can be manufactured. Further, the silver-finished leather-like sheet obtained by the production method of the present invention has an effect that it can be used for men's shoes, sports shoes, general shoes, and the like.

  Hereinafter, the present invention will be described in detail. The present invention provides a foam coating layer by applying and drying a liquid obtained by foaming a polyurethane aqueous dispersion 1.5 to 6 times on at least one surface of a base layer composed of a fiber-entangled nonwoven fabric impregnated with polyurethane arbitrarily. Is formed, and a polyurethane non-woven fabric is laminated and integrated on the foamed coat layer.

(Fiber entangled nonwoven fabric of base layer)
Examples of the fiber constituting the fiber-entangled nonwoven fabric of the base layer constituting the present invention (hereinafter sometimes referred to as “web-entangled sheet”) include, for example, from the viewpoint of flexibility of the obtained leather-finished leather-like sheet. And ultrafine fiber-generating fibers composed of at least two types of polymers. Ultrafine fiber generation type fiber is an extractable fiber that has a sea-island structure in cross section, or sea components are fibrillated into island components by dissolving or decomposing with water, solvent, or a decomposing agent such as sodium hydroxide. This is a collective term for split fibers or the like that fibrillate into ultrafine fibers made of each polymer. When flexibility is not particularly required, it may of course be composed of fibers having a normal thickness, or may be a mixture of the above ultrafine fiber-generating fibers and normal fibers.

  Examples of the polymer constituting the ultrafine fiber used for the fiber entangled nonwoven fabric of the base layer include polyamides that can be melt-spun such as 6-nylon and 66-nylon, polyethylene terephthalate, polybutylene phthalate, isophthalic acid-modified polyester, Examples thereof include at least one polymer selected from melt-spinnable polyesters such as cationic dyeable modified polyethylene terephthalate and polyolefins typified by polypropylene. In addition, as the component extracted or decomposed and removed by the extractable fiber, the solubility or decomposability with respect to water, a solvent or a decomposing agent is different from that of the ultrafine fiber component, and the solubility or decomposability with respect to water or a specific solvent or decomposing agent Is a polymer that is higher than the ultrafine fiber component and has a lower melt viscosity or lower surface tension than the ultrafine fiber component under spinning conditions, such as polyvinyl alcohol, olefin-modified polyvinyl alcohol, polyethylene, polystyrene, polyethylene propylene. It is at least one polymer selected from polymers such as copolymers and modified polyesters. The volume ratio of the sea component to the island component of this ultrafine fiber-generating fiber is 1: 2 to 2: 1, and the preferred fineness after extracting the sea component is 0.01 in terms of texture and fulfillment. A range of ~ 0.0001 dtex is good.

(Manufacture of fiber entangled nonwoven fabric and stabilization of form)
Ultrafine fiber-generating fibers are collected as short fibers having a length of 20 to 75 mm and then made into a short fiber web by the card method, or after making into a long fiber web at the same time as spinning by a direct method such as the spunbond method. Or entangled with a high-speed fluid to obtain a fiber-entangled nonwoven fabric. Next, in this fiber-entangled nonwoven fabric, it is necessary to ensure the necessary strength and stability while maintaining the flexibility as much as possible. The method is to fix the fiber while maintaining the flexibility. It may be impregnated with a polymer elastic body solution such as polyurethane, and as long as necessary strength and stability can be ensured by sufficiently promoting fiber entanglement due to shrinkage of the nonwoven fabric as described later, It is not necessary to impregnate the polymer elastic body solution. That is, impregnation of polyurethane into the fiber-entangled nonwoven fabric is optional.

  When the polyurethane solution is impregnated, prior to the impregnation treatment, the fiber-entangled nonwoven fabric may be subjected to a surface smoothing treatment by a method such as hot pressing, if necessary. In addition, the fiber-entangled nonwoven fabric surface is heated and pressed between the constituent fibers in order to prevent shape breakage of the fiber-entangled nonwoven fabric that is likely to occur during the subsequent impregnation / coagulation of the polymer elastic body fluid and the extraction process of the fiber-constituting polymer. A method of partially fusing or a method of impregnating a fiber-entangled nonwoven fabric with a water-soluble resin typified by polyvinyl alcohol and gluing and fixing the fibers may be used. Furthermore, when a resin that can be easily heat-shrinked, such as a modified polyester, is used as the fiber component, a high fiber density nonwoven fabric having stronger fiber entanglement can be obtained by developing heat shrinkage with hot water or the like. Is possible. The thickness of the fiber-entangled nonwoven fabric thus formed is preferably 1.0 to 3.0 mm.

The fiber entangled nonwoven fabric can be improved in the fiber density and the degree of entanglement by heat shrinking the fiber entangled nonwoven fabric because the fibers of the fiber entangled nonwoven fabric bind to each other. Form stability can be improved, and when finished into a leather-like leather-like sheet, a sense of fulfillment is expressed, and it can be made closer to natural leather.
In this heat shrinking step, when the fiber-entangled nonwoven fabric containing long fibers is thermally shrunk, the fiber-entangled nonwoven fabric is greatly shrunk compared to the case where the fiber-entangled nonwoven fabric containing short fibers is thermally shrunk. As a result, the fiber density of the ultrafine single fibers is particularly high. The heat shrinkage treatment condition is not particularly limited as long as it is a temperature at which sufficient shrinkage can be obtained, and may be appropriately set according to the shrinkage treatment method to be employed, the processing amount of the object to be treated, and the like. For example, when shrinkage treatment is performed by introducing into warm water, the shrinkage treatment is preferably performed at any temperature within a temperature range of 70 to 150 ° C.
Also, dry heat shrinkage is preferably employed, but wet heat shrinkage treatment is more preferred, and the wet heat shrinkage treatment method is preferably performed by steam heating. As steam heating conditions, it is preferable to heat-treat for 60 to 600 seconds under conditions of an ambient temperature of 60 to 100 ° C. and a relative humidity of 40 to 100% RH, more preferably 70 to 100% RH. Such heating conditions are preferable because the fiber-entangled nonwoven fabric can be shrunk at a high shrinkage rate. In addition, when a polyvinyl alcohol-based resin is used as a constituent component of the sea-island type composite fiber, if the relative humidity is too low, the moisture in contact with the fiber tends to dry quickly and the shrinkage tends to be insufficient. .
The fiber-entangled nonwoven fabric subjected to the wet heat shrinkage treatment in this way may further increase the fiber density by heating or pressing at a temperature equal to or higher than the heat deformation temperature of the ultrafine fiber-generating fiber.
By securing sufficient fiber entanglement and by expressing sufficient morphological stability by ensuring a high fiber density, it can be used as a base layer for the silver-finished leather-like sheet of the present invention without providing a polymer elastic body later. As a result, when it is finished in a silver-finished leather-like sheet, it gives a sense of fulfillment and can be made closer to natural leather.
And by securing a high fiber density, the adhesion between the polyurethane nonwoven fabric and the fiber-entangled nonwoven fabric constituting the base layer is lowered as the application of the polymer elastic body is lowered. However, in the present invention, even if the base layer is made of a long fiber entangled nonwoven fabric capable of securing a high fiber density, the long fiber entanglement can be uniformly applied with a small amount of coating through the foam coat layer made of a polyurethane water dispersion. By penetrating the inside of the surface of the synthetic nonwoven fabric and staying in the vicinity of the surface, it is possible to stably improve the adhesion between the polyurethane nonwoven fabric and the long-fiber entangled nonwoven fabric and have a feeling of unity.
As the change in the basis weight of the fiber-entangled nonwoven fabric in the wet heat shrinkage treatment step, it is 1.1 times (mass ratio) or more, further 1.3 times or more as compared with the basis weight before the shrinkage treatment, and 2.0. It is preferable that it is 2 times or less, and further 1.6 times or less.

(Impregnation of polyurethane into fiber-entangled nonwoven fabric)
In addition, for the purpose of improving the shape stability of the fiber-entangled nonwoven fabric, before and / or after performing the ultrafine fiber treatment of the fiber-entangled nonwoven fabric, if necessary, a liquid containing a polyurethane non-solvent. A dense foamed sponge may be formed by dipping in and solidifying by wet. Alternatively, the form stability may be improved by impregnating the fiber-entangled nonwoven fabric with a polyurethane-based aqueous liquid, followed by thermal gelation and dry coagulation.

  Examples of the method for impregnating the fiber-entangled nonwoven fabric with polyurethane include a method in which a polyurethane solution or dispersion is impregnated and solidified by a conventionally known dry method or wet method. As the impregnation method, after immersing the fiber-entangled nonwoven fabric in a bath filled with a solution or dispersion of a polymer elastic body, the treatment is squeezed once or a plurality of times with a press roll or the like so as to be in a predetermined impregnation state. The dip nip method is preferably used. As other methods, a bar coating method, a knife coating method, a roll coating method, a comma coating method, a spray coating method, or the like may be used.

In the present invention, polyurethane is used as the resin impregnated in the fiber-entangled nonwoven fabric because of its flexibility, elastic recovery, sponge formation and the like. As a polymer elastic body other than polyurethane, for example, an acrylonitrile elastomer, an olefin elastomer, a polyester elastomer, a polyamide elastomer, an acrylic elastomer, or the like may be appropriately mixed with polyurethane.
Examples of the polyurethane impregnated here include at least one polymer diol selected from polyester diol, polyether diol, polycarbonate diol or polyester polyether diol having an average molecular weight of 500 to 3000, and 4,4′-diphenylmethane diisocyanate, At least one diisocyanate compound selected from aromatic, alicyclic or aliphatic diisocyanates such as isophorone diisocyanate and hexamethylene diisocyanate, and at least one low molecule having two or more active hydrogen atoms Compounds having a molecular weight of 300 or less, such as ethylene glycol, propylene glycol, 1,4-butanediol, hexanediol, 3-methylpentanediol-1,5,1, Diols such as 4-cyclohexanediol and xylene glycol, diamine compounds such as ethylenediamine, propylenediamine, xylylenediamine, isophoronediamine, piperazine, phenylenediamine, and tolylenediamine, hydrazines and hydrazides such as adipic hydrazide and isophthalic acid dihydrazide A polyurethane obtained by reacting at least one selected from the above.

In particular, in order to achieve the object of the present invention, a polyurethane obtained by reacting a chain extender mainly composed of 1,4-butanediol or 3-methylpentanediol-1,5 at a predetermined molar ratio is preferable. is there.
The polyurethane concentration in the polyurethane solution is preferably in the range of 10 to 50% by mass. The polyurethane preferably has a molar ratio of the polymer diol and the low molecular weight compound in the range of 1: 1 to 1: 7.

After polyurethane is added to the fiber-entangled nonwoven fabric, the island component of polyurethane and ultrafine fiber-generating fiber is treated with a non-solvent and the sea component with a liquid that acts as a solvent or a decomposing agent. The fiber-generating fiber is transformed into an ultrafine fiber bundle to form a sheet made of an ultrafine fiber entangled nonwoven fabric and polyurethane, and this is used as the base layer of the silvered leather-like sheet of the present invention. Of course, prior to the inclusion of polyurethane, the base layer may be a sheet formed using a method of transforming ultrafine fiber-generating fibers into ultrafine fiber bundles.
And in the case of containing polyurethane in this way, the content ratio to the ultrafine fiber entangled nonwoven fabric is not particularly limited as long as it achieves the purpose as a silvered leather-like sheet of the present invention, preferably Is not more than 30% by mass, more preferably not more than 20% by mass, and most preferably not more than 15% by mass in terms of having a solid texture and peel strength comparable to natural leather. If the polyurethane resin content exceeds 30% by mass, the resulting silvered leather-like sheet tends to be hard, which is not preferable.

(Foam coat layer)
In the present invention, at least one surface of a base layer composed of a fiber-entangled nonwoven fabric impregnated with polyurethane arbitrarily, a foamed polyurethane aqueous dispersion is applied 1.5 to 6 times, dried, and then coated with foam. A layer is formed. When the expansion ratio is less than 1.5, the resin constituting the foam coat layer does not stay near the surface of the base layer but tends to penetrate into the base layer, and a sufficient foam coat layer cannot be obtained. On the other hand, when the expansion ratio exceeds 6, the resin constituting the foam coat layer tends to hardly penetrate into the base layer, and the peel strength decreases.
The polyurethane that forms the foam coat layer may be the same as or different from the polyurethane contained in the fiber-entangled nonwoven fabric. This is preferable because the unity feeling of the sheet is improved. Foaming is preferably formed by either dry foaming or mechanical foaming. However, in each method, it is a major premise that an organic solvent that is toxic to the human body such as DMF is not used. For this reason, based on the polyurethane aqueous dispersion, for example, a thickener, a foam stabilizer, a foaming agent or a foaming agent is blended, and mechanical foaming, that is, the resin is mechanically agitated and air is entrained. The foaming method is most preferable.

For dry foaming, foaming is performed by adding a foaming agent to the resin to be used, but if the expansion ratio is low, the embossing property may be lowered. Therefore, the expansion ratio is preferably 1.5 times or more. Further, when the expansion ratio exceeds 6 times, the viscosity becomes extremely high, and handling and uniform application are difficult.
The expansion ratio here means how many times the apparent volume of the foam obtained when the resin solution containing the foaming agent is dried with hot air as it is is the volume of the resin of the same mass not containing the foaming agent.

As for mechanical foaming, foaming is uniformly present in the foamed coating layer, but if the foaming ratio is low, sufficient embossability tends to be difficult to obtain. Therefore, the expansion ratio is preferably 1.5 times or more. Further, when the expansion ratio exceeds 6 times, the viscosity becomes extremely high, and handling and uniform application are difficult.
The expansion ratio here means how many times the volume of the resin solution with the same mass not mechanically foamed and the volume of the resin solution dried after mechanical foaming.

  It does not specifically limit as a formation method of a foam coat layer, It can form by having a well-known application | coating process and a drying process. For example, the coating method can be appropriately selected from a comma coater, a reverse coater, a knife coater or a gravure coater.

The thickness of the foam coat layer is preferably in the range of 50 to 400 μm from the viewpoint of balance with the base layer. If it is less than 50 μm, it tends to be affected by unevenness of the base layer and the smoothness tends to decrease. If it exceeds 400 μm, the constitutional balance of the silver-finished leather-like sheet tends to change and the leather-like fullness tends to be impaired. There is. Moreover, it is more preferable from being excellent in the sense of unity and fullness of the textured silver leather-like sheet obtained in the range of 70 to 200 μm.
Further, the basis weight of the foam coat layer is preferably 3 to 40 g / m ² from the viewpoint of the balance between layers in the silver-finished leather-like sheet.

  In addition to polyurethane as the base resin, the polyurethane water dispersion that forms the foam coat layer contains foam stabilizers, foaming aids, thickeners, water for adjusting the solid content, etc. for adjusting the viscosity. You may contain. Moreover, it is preferable to contain the elasticity imparting agent which gives elasticity to the porous layer formed, the crosslinking agent for bridge | crosslinking a base resin, etc. Furthermore, it goes without saying that various additives usually used in the production of leather-like sheet structures such as pigments can be added as necessary.

  The aqueous polyurethane dispersion can be used in the form of an emulsion or dispersion. In addition, from the viewpoint of foamability, a polyurethane having a high solid content and low TG (glass transition temperature), good foaming properties, and low antifoaming agent content is suitable.

  Examples of the foam stabilizer contained in the polyurethane aqueous dispersion include long-chain alkylcarboxylates such as ammonium stearate. The preferable content of the foam stabilizer is 1 to 10 parts by mass with respect to 100 parts by mass of the solid content of the polyurethane.

  Moreover, the polyurethane aqueous dispersion may contain a foaming aid. Examples of the foaming aid include sodium dialkylsulfosuccinate. The content of the foaming aid is 0.5 to 6 parts by mass with respect to 100 parts by mass of the solid content of the polyurethane.

  Furthermore, the polyurethane aqueous dispersion may contain a thickener for stabilizing the generated foam. Preferred examples of the thickener include ammonium polyacrylate and polyacrylic acid. Content of a thickener is 0.5-3 mass parts with respect to 100 mass parts of solid content of a polyurethane.

  Further, the amount of water added in the polyurethane water dispersion is preferably in the range of 30 to 200 parts by mass with respect to 100 parts by mass of the solid content of the base resin in order to adjust the solid content and the viscosity.

  If the polyurethane has some self-crosslinking properties, it cures over time, but if a slow-curing polyurethane is used, it is necessary to add a crosslinking agent. Preferred examples of the crosslinking agent include isocyanate. Content of a crosslinking agent is 1.5-4 mass parts with respect to 100 mass parts of solid content of a polyurethane.

  Also, due to the nature of the polyurethane used, if the foam after the formation of the foam coat layer is crushed by pressing and the walls of the bubbles remain attached to each other and cannot be restored to the original bubble state, an elasticity-imparting agent may be added. preferable. An example of the elasticity imparting agent is silicon oil. The content of the elasticity-imparting agent is 0.2 to 1.5 parts by mass with respect to 100 parts by mass of the solid content of the polyurethane.

(Polyurethane nonwoven fabric)
In the present invention, the polyurethane nonwoven fabric laminated on the foam coat layer formed on at least one surface of the substrate layer constitutes a surface layer (silver surface layer) and is made of polyurethane, and its basis weight is 15 to 125 g / m. ² , the polyurethane nonwoven fabric is heated and pressurized to form a film to form a silver surface layer.
The filmed layer, that is, the silver surface layer, preferably retains fine pores. In order to maintain such fine pores, it is preferable that the polyurethane nonwoven fabric is composed of a nonwoven fabric made of ultrafine polyurethane fibers. By constituting with a nonwoven fabric made of such an ultra-fine polyurethane fiber, the basic part of the excellent performance of the present invention described above can be obtained.

Examples of the polyurethane component constituting the polyurethane nonwoven fabric of the present invention include low molecular diols such as ethylene glycol, propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, and 3-methylpentane. Polyester glycol obtained by condensation polymerization with at least one selected from diol-1,5, etc., polyether glycol such as polyethylene ether glycol, polypropylene ether glycol, polytetramethylene ether glycol, polyhexamethylene glycol, polycaprolactone glycol At least one polymer diol selected from polylactone glycols such as polyvalerolactone glycol, and having a mean molecular weight of 500 to 3000 It is a polyurethane to a segment. In particular, polyurethane using a polyester diol having an average molecular weight of 700 to 3000 obtained by condensation polymerization of a diol mainly composed of 3-methylpentanediol-1,5 and a dicarboxylic acid is melt moldability, solvent stability, and hydrolysis resistance. gender, weather resistance, flexibility, is suitable in terms of flexibility, in particular have the following fine pore diameter 300 [mu] m 100 / cm ² or more, and at least a portion of the micropores bridges of polyurethane fibers This is preferable in that a silver surface layer having a structure is easily formed.

  Examples of the organic diisocyanate to be reacted with the polymer diol include aromatic diisocyanates such as 4,4′-diphenylmethane diisocyanate, tolylene diisocyanate, phenylene diisocyanate, and xylylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, and hydrogenated xylene diisocyanate. In combination with at least one selected from aliphatic or alicyclic diisocyanates, etc., or an organic polyisocyanate having 3 or more isocyanate groups such as organic triisocyanate within a range not impairing melt spinnability or melt moldability May be.

  As the chain extender, a compound having two active hydrogen atoms and a molecular weight of 300 or less, for example, ethylene glycol, propylene glycol, 1,4-butanediol, hexanediol, 3-methylpentanediol-1,5,1,4 -Diols such as cyclohexanediol and xylene glycol, diamines such as ethylenediamine, propylenediamine, xylylenediamine, isophoronediamine, piperazine, phenylenediamine, and tolylenediamine, hydrazines and hydrazides such as adipic hydrazide and isophthalic acid dihydrazide, etc. And at least one selected from. Particularly preferred is a polyurethane using a chain extender mainly composed of 1,4-butanediol or 3-methylpentanediol-1,5. The molar ratio of the polymer diol to the chain extender can be freely changed depending on the physical properties of the nonwoven fabric, but is preferably about 1: 2 to 7.

When the basis weight of the polyurethane nonwoven fabric forming the surface layer of the silver-finished leather-like sheet of the present invention is less than 15 g / m ² , a continuous linear body of a heat-adhesive resin described later is used at the time of bonding to the base layer. When the base layer and the layer made of the ultrafine fiber polyurethane nonwoven fabric are bonded by melting, the continuous linear body of the melted heat-adhesive resin passes through the fiber voids of the layer made of the ultrafine fiber polyurethane nonwoven fabric and flows out to the surface. In this case, a silver surface having a rough texture with a rough surface or a smooth appearance of the silver surface is deteriorated. On the other hand, if it exceeds 125 g / m ² , the heat-adhesive resin may not be sufficiently heated, and the balance between the silver surface and the substrate layer tends to decrease, and the texture tends to decrease. Furthermore, after heat sealing, the diameter of the micropores is reduced, or the micropores are blocked and air permeability tends to be lowered, which is not preferable. The ultra-fine polyurethane nonwoven fabric is produced by a method in which polyurethane fibers produced by a normal spinning method are entangled to make a nonwoven fabric, or a method of making a nonwoven fabric simultaneously with spinning, such as a spunbond method or a melt blown method. good. In particular, the nonwoven fabric obtained using the melt blown method has thin constituent fibers, a range that can be referred to as a so-called ultrafine fiber, and the reason is that the fiber direction is random, the fiber diameter is not constant, and has a certain distribution This is preferable because a silver surface layer closer to natural leather with a higher quality is formed.
In the present invention, the “ultrafine polyurethane nonwoven fabric” refers to those having an average fiber diameter of 10 μm or less. Here, the average fiber diameter of the fiber is an average value obtained by observing the surface of the ultra-fine polyurethane fiber nonwoven fabric with an electron micrograph and measuring fiber diameters at arbitrary 10 locations.

(Manufacturing method of leather-like sheet with silver)
The method for producing a silver-finished leather-like sheet of the present invention, in which a layer made of a polyurethane nonwoven fabric and a base layer are bonded via a foamed coating layer and laminated and integrated, Sufficient flexibility can be ensured and sensitivity close to that of natural leather can be expressed. In particular, in order to provide the same level of feeling as solid leather, the flexibility and breathability of natural leather, and to provide the same sensitivity as natural leather, the density of the fiber layer as the base layer is kept high, and the polymer contained It is important to reduce the number of elastic bodies.
However, on the other hand, there is a problem that it is difficult to ensure the adhesive strength with the silver surface layer due to the low content of the elastic polymer contained in the base layer.
Therefore, in order to achieve the necessary and sufficient adhesive strength while keeping the ratio of the polymer elastic body contained in the base layer as low as possible and ensuring sufficient flexibility, Forming a polyurethane layer in a lighter and thicker state is particularly effective for forming a silver surface layer using this layer as an adhesive layer.
In the present invention, this object is achieved by coating a foamed polyurethane resin solution on the substrate layer. That is, by coating the base layer in the foamed state of polyurethane resin and immediately drying, the coating liquid is concentrated near the surface of the base layer due to the increase in apparent viscosity due to foaming and low density. In this state, a polyurethane layer is formed.
In addition, when a silver surface layer is formed by laminating an ultrafine polyurethane nonwoven fabric layer on the base layer, a resin layer having a sufficient thickness is secured on the base layer so that they can be uniformly laminated over the entire surface. In this respect as well, by making the polyurethane resin layer to be coated into a foamed state, it becomes possible to secure a foamed polyurethane resin coated layer with a sufficient thickness while keeping the weight increased by the coating as low as possible. This makes it possible to stably and uniformly form a silver surface layer made of an ultrafine polyurethane nonwoven fabric.

  In the method of integrating the substrate layer and the polyurethane nonwoven fabric layer in the present invention, there is a particular limitation as long as the method can be thermally bonded after the foamed coating layer is disposed between them by the method described above. Is not to be done. However, as a method of integrating these three layers more easily and stably, and uniformly and firmly laminating them while ensuring flexibility, the softening temperature of the polyurethane constituting the polyurethane nonwoven fabric on the surface of the foam coat layer Apply a solution of a heat-adhesive resin having a temperature lower by 20 ° C. or more in a dotted manner, immediately overlay the polyurethane nonwoven fabric, and temporarily bond it with an embossing roll having a surface temperature near the softening temperature of the heat-adhesive resin. Thereafter, a method in which the base layer and the foamed coating layer are laminated and integrated with the polyurethane nonwoven fabric by main bonding with an embossing roll having a surface temperature equal to or higher than the softening temperature of the polyurethane nonwoven fabric is preferable.

Here, as a method of laminating these three layers, a state in which the polyurethane nonwoven fabric is not unevenly distributed locally with respect to the central foam coat layer, and the shape is generally uniformly maintained while maintaining its form. There is no particular limitation as long as it is a method that can be adhered by.
Specifically, a hot press using hot embossing is preferably used. In this case, the pressing temperature and pressure are not particularly limited, but it is necessary that the nonwoven fabric composed of the continuous linear body of the heat-adhesive resin at the center melts uniformly and contributes efficiently to the adhesion of the three layers. Therefore, it is preferable to use a roll of flat or fine shallow wrinkles (such as satin).
At this time, it is necessary to arrange so that at least the side of the polyurethane nonwoven fabric that becomes the surface layer comes to the hot embossing roll side. And it is preferable to carry out temporary adhesion by heating and pressurizing at a pressure of 0.1 to 1 MPa at a temperature 0 to 50 ° C. higher than the softening point of the thermoadhesive resin applied for temporary adhesion.

The laminated body integrated by temporary bonding in this manner is further bonded and integrated at a temperature equal to or higher than the softening temperature of the polyurethane nonwoven fabric. For example, the surface of the polyurethane nonwoven fabric is heat-treated at high temperature and high pressure. The film can be made into a smooth silver surface.
Further, the lamination and integration treatment by the main adhesion is effective for allowing the thermoadhesive resin to penetrate into the base layer and the polyurethane nonwoven fabric and to develop a sufficient adhesive force.

As a method for achieving these, the hot embossing method is preferably used.
Although the press temperature and pressure at this time are not particularly limited, they are usually laminated and integrated at a temperature 0 to 80 ° C. higher than the softening point of the resin constituting the polyurethane nonwoven fabric and / or at a pressure of 1 to 10 MPa. It is preferable. If bonding is performed at a low temperature with respect to the softening point, the silver layer may not be formed, or the appearance of the silver surface may be deteriorated and adhesion failure may also occur. On the other hand, at a temperature higher than 80 ° C. from the softening point, the fine pores of the foam coat layer may be crushed too much, resulting in poor air permeability. Or the fluidity | liquidity of resin which comprises a polyurethane nonwoven fabric increases too much, and it becomes impossible to ensure surface smoothness by adhering to a heat | fever embossing roll or flowing into a base layer.
Moreover, as the pressure of lamination (bonding), if the lamination is performed at a pressure lower than 1 MPa, poor adhesion may occur, and if the pressure is higher than 10 MPa, the texture tends to be hard. In the present invention, the softening point was defined as the temperature at which it was determined that the resin began to melt visually using a melting point measurement device (YANACO MP-500V).

Surface layer made of the resulting polyurethane nonwoven fabric thus (grain layer) is preferably has the following fine pore diameter 300 [mu] m 100 / cm ² or more. A polyurethane nonwoven fabric is formed into a film by heating and pressurization, but micropores remain in the film. When the diameter of the micropores exceeds 300 μm, uneven glossiness is caused and the appearance is deteriorated. Therefore, it is necessary that the diameter is 300 μm or less, and preferably 100 μm or less. Further, the number of micropores is 100 / cm ² or more, preferably 300 / cm ² or more. By satisfying this number, the air permeability is improved.
In the present invention, pores having a diameter exceeding 300 μm may exist if the amount is small. The micropore diameter is defined as the diameter of a circle having the same area as the surface area of the hole.

  Furthermore, it is preferable that at least some of the micropores have a polyurethane fiber bridging structure. The ratio of the bridge structure is not particularly limited, but if it is 10% or more of all the fine holes, it tends to eliminate uneven gloss. Preferably more than 30% has a bridge structure. The micropores having a bridge structure in the present invention are an arbitrary selection of the surface of the sheet, and an electron micrograph is observed. In the micropores, one or more fibers having a fiber diameter of 3 μm or more are bridged. It exists in such a state. Although it is not always clear why a polyurethane fiber bridge structure is effective in resolving uneven luster, it is blocked by the bridge fiber when light incident on the micropores is reflected. Therefore, it is predicted that it is difficult to emit from the fine holes or diffused.

  Moreover, as for the thickness which consists of a polyurethane nonwoven fabric, ie, the surface of a silver surface, 10-100 micrometers is preferable. When it is thinner than 10 μm, the abrasion resistance of the silver layer is not practically sufficient, and when it is thicker than 100 μm, a natural crease / texture cannot be obtained and the high-grade feeling is impaired. The thickness of the silver surface layer referred to here is the average of the thicknesses obtained from an electron micrograph.

In the production method of the present invention, the solution of the heat-adhesive resin used for bonding needs to have a softening point of the heat-adhesive resin that is at least 20 ° C. lower than the softening point of the polyurethane constituting the polyurethane nonwoven fabric. When the laminated leather-like sheet is laminated and heat-sealed, the fibers of the polyurethane non-woven fabric are additionally fused to increase the adhesion area, and as a result, the adhesion is improved.
At that time, the adhesive strength is expressed by suppressing the decrease in air permeability, and the heat-sealing of the polyurethane nonwoven fabric on the surface is suppressed to the extent necessary to obtain a high-quality silver surface layer. This is based on the heat-adhesive resin used in the above. Therefore, when the difference in softening point is less than 20 ° C. or the softening point of the adhesive resin is higher, the adhesive strength is lowered, and in some cases, the sense of unity of the laminate is impaired, or the micropores of the polyurethane nonwoven fabric are blocked, Air permeability is reduced.

Further, the peel strength between the polyurethane nonwoven fabric layer (silver surface side) and the base layer is preferably 30 N / 2.5 cm or more, more preferably 30 to 150 N / 2.5 cm in the measurement method described later. .
When the peel strength is 30 N / 2.5 cm, in practical use as a silvered leather-like sheet, it is possible to almost avoid the problem that the polyurethane nonwoven fabric layer on the surface, that is, the silver surface layer peels from the base layer.

The silvered leather-like sheet thus obtained can be subjected to post-processing such as coloring. Regarding coloring, of course, dyes and pigments can be added in advance to the components constituting the silver-finished leather-like sheet. When coloring is performed by post-processing, it can be colored with a colorant solution composition comprising a solvent, a resin and a colorant containing dimethylformamide in an amount of less than 10% by mass. On the other hand, if the dimethylformamide content is 10% by mass or more, fine pores on the surface are crushed and air permeability is impaired.
Then, if necessary, finish processing such as embossing embossing, dyeing, softening treatment, fir treatment and the like can be carried out to finish a silvered leather-like sheet.

Next, embodiments of the present invention will be described with specific examples, but the present invention is not limited to these examples. In addition, unless otherwise indicated, the part and% in an Example are related to mass.
Moreover, the peeling strength of the layer (silver side) which consists of a polyurethane nonwoven fabric, and a base material layer, and the air permeability of the leather-like sheet | seat were measured with the following method, respectively.

[Peel Strength]: The test piece having a width of 2.5 cm and a length of 25 cm is bonded to a rubber plate having a thickness of about 4 mm with a urethane adhesive. The test piece is marked with 5 sections at intervals of 2 cm, then immersed in water for 10 minutes, taken out, and subjected to a peel test at a speed of 50 mm / min with a tensile tester. The lowest value of each section was read from the obtained chart, and the average value was converted to 1 cm width.

[Air permeability]: Measured by a method defined by A method of 6.27.2 of JIS L-1096.

Production Example 1 (Base Layer Production Example)
As the sea component polymer, ethylene-modified polyvinyl alcohol (ethylene unit content: 8.5 mol%, polymerization degree: 380, saponification degree: 98.7 mol%), and island component polymer: polyethylene terephthalate (inherent viscosity: 0.65), Melted individually. The molten polymer can be combined with the sea component polymer in the cross section in a multi-spinning base in which a large number of nozzle holes are arranged in parallel to form a cross section in which 25 island component polymers having a uniform cross-sectional area are distributed in the sea component polymer. The island component polymer was supplied in a pressure balance so that the average area ratio of the island component polymer was sea component / island component = 25/75, and was discharged from the nozzle hole at a die temperature of 250 ° C. The islands are pulled and thinned by an air jet / nozzle type suction device that adjusts the pressure of the airflow so that the average spinning speed is 3600 m / min, and sea-island fibers having an average cross-sectional area of 177 μm ² (about 2.4 dtex) are spun. This was continuously collected on the net while being sucked from the back side. The amount of deposition was adjusted by adjusting the moving speed of the net, and the embossing roll kept at 80 ° C. was pressed at a linear pressure of 686 N (70 kg) / cm to obtain a long fiber web having a basis weight of 30 g / m ² .

After embossing the surface of the long fiber web, spraying an oil agent mainly composed of a mineral oil-based slipping oil and mixing an antistatic agent, and then continuously folding the long fiber web using a cross wrapper device, A 14 layer laminar long fiber web. Subsequently, a three-dimensional entanglement treatment was performed by a needle punching method in which needle punching is applied to the layered long fiber web, thereby obtaining an entangled nonwoven fabric having a number density of sea-island fibers of 500 pieces / mm ² . The needle punching conditions are: needle number 40, barb depth 40 μm, one barb with a regular triangular cross-section needle A, and pre-entanglement with the punch depth through which the barb penetrates in the thickness direction from both sides, After entanglement to the extent that the folded long fiber web does not slip, needle No. 42, barb depth 40μm, 6 barbs, needle B with equilateral triangle cross section, 3 barbs from both sides are thick The entanglement process was performed so that the sea-island fibers were entangled in the thickness direction to a desired level at the punch depth penetrating in the vertical direction. Needle punching with the needle B was performed with a total number of punches of 1700 punch / cm ² from both sides.

Next, 18 ° C. water is uniformly sprayed on both sides of the entangled nonwoven fabric, and immediately after that, tension and frictional stress are applied in both the length direction and the width direction in an atmosphere at a temperature of 75 ° C. and a relative humidity of 95%. By performing the wet heat shrinkage treatment under the condition that it is allowed to pass continuously over 4 minutes while hardly acting, a structure that easily develops extensibility during molding is obtained. Then, before drying the entangled nonwoven fabric, press it between metal rolls kept at 120 ° C. and dry it while compressing and smoothing the surface, and then introduce the entire nonwoven fabric structure into an atmosphere at 120 ° C. and dry it. Thus, an extremely dense entangled nonwoven fabric was obtained so that the number density of sea-island fibers was 1900 / mm ² in a cross section parallel to the thickness direction at a basis weight of 1125 g / m ² .

  The obtained entangled nonwoven fabric was impregnated with an aqueous dispersion (solid content concentration 15%) of a polyurethane composition mainly composed of polycarbonate / ether-based polyurethane as a polymer elastic body fluid, and the polymer with respect to the mass 100 of the entangled nonwoven fabric. After pressing (squeezing) with a metal roll so that the liquid content of the elastic body fluid is 50, heat-coagulation is performed by applying an infrared heater for 1 minute under the condition that the surface temperature of the entangled nonwoven fabric is 80 ° C. Finally, it is introduced into the atmosphere at 120 ° C. to dry the moisture, then immediately introduced into the atmosphere at 150 ° C. and cured for 2 minutes, so that the polyurethane composition exists in the voids between the sea-island fibers. I let you. Next, after treatment with hot water at 90 ° C. for 20 minutes in a liquid dyeing machine to extract and remove the denatured polyvinyl alcohol, which is a sea component in the sea-island fiber, it is introduced into an atmosphere at 120 ° C. to dry the moisture. Thus, a base layer (for artificial leather) having a thickness of about 1.4 mm, in which the polyurethane composition was contained inside the entangled nonwoven fabric composed of the ultrafine fiber bundles of modified polyethylene terephthalate, was obtained.

Production example 2 (polyurethane nonwoven fabric production example)
A molar ratio of poly-3methyl-1,5 pentyl adipate glycol having an average molecular weight of 1150, 4,4-diphenylmethane diisocyanate and 1,4-butanediol in a molar ratio of 1: 4: 3 (theoretical nitrogen content based on isocyanate is 4.63%) Then, polyurethane was polymerized by melt polymerization using a screw type kneading type polymerization machine. The polyurethane had a softening point of 172 ° C. The obtained polyurethane was extruded in a molten state from a die orifice heated to a temperature of 260 ° C. by a melt blow method, and at 25 m / h by high-speed air heated to 260 ° C. ejected from a slot on both sides thereof at a pressure of 0.4 MPa. Installing blown onto a conveyor net that travels at a speed of the resin extruded from the orifice to obtain a nonwoven fabric a having an average basis weight 25 g / m ² while microfine fiber formation. At this time, on the side opposite to the orifice of the conveyor net, the suction of air at a flow rate more than 3 times the hot air blown out from the slot prevents the disturbance of the fiber flow and the desired uniformity of the formed web. Secured. The distance between the conveyor and the nozzle was 25 cm. The resulting nonwoven fabric was a random web of fine fibers.

Example 1
As a coating liquid to be applied onto the base layer obtained in Production Example 1, a thickener (100% aqueous dispersion of a polyurethane composition mainly composed of polycarbonate / ether polyurethane) (solid content concentration: 40%) ACSUL810A) 1.0 part was added and mixed lightly to such an extent that it did not foam, and then 3.0 parts of foam stabilizer (Nopco DC100A) was added, and this was also mixed lightly to the extent that no foaming occurred. The viscosity of the liquid mixture at this time was 2240 poise. This liquid was made into a foaming liquid foamed twice by mechanical foaming, coated on the base layer with a comma coater at a thickness of 50 μm, and then dried by passing through a hot air dryer at a speed of 6 m / min. . The temperature in the hot air dryer is set with a temperature gradient that gradually increases to 70 to 120 ° C., and the foam coating layer is passed through the substrate layer coated with the foaming liquid over about 2 minutes. Formed.
Next, the foam coating layer and the ultrafine polyurethane nonwoven fabric obtained in Production Example 2 were overlapped so that the ultrafine polyurethane nonwoven fabric was in contact with the embossing roll, and the embossing roll having a surface temperature of 160 ° C. was used to press the press pressure 0.49 MPa (5 kg / The ultrafine polyurethane nonwoven fabric was melt bonded to the foam coat layer at a pressure of cm ² ) to obtain a silvered leather-like sheet.
This silver-finished leather-like sheet had a high-grade leather-like appearance without uneven glossiness and air permeability of 1.9 cm ³ / cm ² / sec. And about 800 fine pores / cm ² having an average diameter of 10 μm exist on the surface, and about 30% of the fine pores were bridged from the electron micrograph. The thickness of the silver surface layer (coating layer) was 47 μm.
The peel strength of this product was 87 N / 2.5 cm.

Example 2
In Example 1, as a polyurethane aqueous dispersion for forming a foam coat layer, 1 part of a thickener (ACSUL810A) was added to 100 parts of an aqueous polyurethane (manufactured by Nikka Chemical, Evaphanol HA10C), and after uniform stirring, foam regulation 3 parts of the agent (Nopco DC100A) was added, and the liquid was mixed with stirring until no foaming occurred. The liquid after the mixing had a viscosity of 2300 cps was foamed by mechanical foaming to double the volume, and a coating liquid comprising this foamed liquid was prepared. This coating solution is coated with a thickness of 50 μm on the substrate layer (fiber sheet) obtained in Production Example 1 using a comma coater, and is run in a tenter dryer set at 120 ° C. in about 1 minute. And dried to obtain a base layer having a foam coat layer.
A 10% dimethylformamide (hereinafter DMF) solution of polyurethane (SSTC-44: manufactured by Dainichi Seika Co., Ltd., softening point 110 ° C.) was used as an adhesive resin using a 150 mesh gravure roll on the base layer having the foamed coating layer. Immediately after being applied in the form of dots, the polyurethane nonwoven fabric obtained in Production Example 2 was superposed and temporarily bonded at a press pressure of 0.196 MPa (2 kg / cm ² ) with a hot embossing roll having a surface texture of 110 ° C., A leather-like sheet laminated with a polyurethane nonwoven fabric was obtained.
Thereafter, the surface temperature of the embossing roll was raised to 160 ° C., and the ultrafine polyurethane nonwoven fabric was melt-bonded at a press pressure of 0.49 MPa (5 kg / cm ² ) to obtain a grained leather-like sheet. This silver-finished leather-like sheet had a high-grade leather-like appearance with no unevenness of gloss and air permeability of 0.7 cm ³ / cm ² / sec. And about 800 fine pores / cm ² having an average diameter of 10 μm exist on the surface, and about 30% of the fine pores were bridged from the electron micrograph. The thickness of the coating layer was 36 μm. The peel strength of this product was 118 N / 2.5 cm.

Comparative Example 1
Using a 150 mesh gravure roll on the fiber sheet obtained in Production Example 1, a 10% dimethylformamide (hereinafter DMF) solution of polyurethane (SSTC-44: manufactured by Dainichi Seika, softening point 110 ° C.) as an adhesive resin. Immediately after the application in the form of dots, the polyurethane nonwoven fabric obtained in Production Example 2 was superposed, adhered with a press roll, dried, and temporarily fixed to obtain a leather-like sheet on which the polyurethane nonwoven fabric was laminated. Thereafter, the ultrafine polyurethane nonwoven fabric was melt-bonded with an embossing roll having a surface temperature of 160 ° C. at a press pressure of 0.49 MPa (5 kg / cm ² ) to obtain a textured leather-like sheet with silver. This silver-finished leather-like sheet had a high-grade leather-like appearance without uneven glossiness and air permeability of 4.3 cm ³ / cm ² / sec. The surface had about 750 micropores having an average diameter of 12 μm / cm ² , and about 30% of micropores were bridged from the electron micrograph. The thickness of the coating layer was 22 μm. The peel strength of this product was 26 N / 2.5 cm.

  The method for producing a silver-finished leather-like sheet according to the present invention is such that a polyurethane nonwoven fabric on the surface is composed of a silver surface with fine pores having a bridging structure, and between the silver surface and the foam coat layer and the substrate layer below it. To obtain a textured leather-like sheet with silver that has a feeling of unity, has a practically sufficient peel strength, has excellent air permeability and moisture permeability, and has a particularly excellent appearance with no uneven glossiness. And can be effectively used as a method for stably producing a grained leather-like sheet that can be used for men's shoes, sports shoes, general shoes, and the like.

Claims (6)

After forming a foam coat layer by applying and drying a liquid obtained by foaming a polyurethane water dispersion 1.5 to 6 times on at least one surface of a fiber entangled nonwoven fabric impregnated with polyurethane arbitrarily A method for producing a silver- coated leather-like sheet in which a polyurethane nonwoven fabric is laminated and integrated with the foam coat layer, and is 20 ° C. or more lower than the softening temperature of the polyurethane constituting the polyurethane nonwoven fabric on the surface of the foam coat layer. A method for producing a silvered leather-like sheet, wherein a solution of a heat-adhesive resin having a temperature is applied in the form of dots, and the polyurethane nonwoven fabric is immediately laminated and integrated . After the polyurethane nonwoven fabric is overlaid, it is temporarily bonded with an embossing roll having a surface temperature close to the softening temperature of the thermal adhesive resin, and then finally bonded with an embossing roll having a surface temperature equal to or higher than the softening temperature of the polyurethane nonwoven fabric. The method for producing a silver-finished leather-like sheet according to claim 1, wherein the base layer, the foamed coating layer, and the polyurethane nonwoven fabric are laminated and integrated. Polyurethane nonwoven production method of grain-finished leather-like sheet according to claim 1 or 2 consisting of basis weight of 15~125g / m ^2. The method for producing a silver-finished leather-like sheet according to any one of claims 1 to 3 , wherein the polyurethane in the polyurethane aqueous dispersion and the polyurethane impregnated in the fiber-entangled nonwoven fabric are the same. Foam coating layer, basis weight 3~40g / m ² at which claim 1 or grain-finished production method of the leather-like sheet according to one of 4. The method for producing a silver-finished leather-like sheet according to any one of claims 1 to 5, wherein the fiber-entangled nonwoven fabric of the base layer contains ultrafine elongated fiber nonwoven fabric and 0 to 20 mass% of polyurethane therein. .