JP2012136801A - Artificial leather having novel pattern and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an artificial leather which not only has high strength and excellent stability in shape but also has a novel pattern closely resemble to natural grain shape including random recesses and protrusions on a surface layer of the artificial leather.SOLUTION: The artificial leather has a sheet substrate which has piloerection on a surface of a nonwoven fabric in which a nonwoven fabric including ultrafine fibers and a woven fabric are entangled and integrated, and a polymer elastomer provided on the sheet substrate as a binder. A plurality of protrusion parts which are separated by recess parts are formed on the piloerection side of the surface layer part of the nonwoven fabric in a size having a height difference of 70 μm or more and 500 μm or less and a width of 200 μm or more and 2000 μm or less. The top face of the protrusion part has a gentle protruding curved surface.

Description

  The present invention relates to an artificial leather having a new pattern not only having high strength and excellent shape stability, but also having a surface pattern of the artificial leather made of random irregularities and resembling a natural texture, and a method for producing the same.

  In recent years, the types of artificial leather have been diversified from the diversification of consumer demands to the suede tone with brushed surface and the silver tone with a polymer elastic body on the surface layer. Suede-like artificial leather is evaluated for its high-quality uniform touch and lighting effect due to the surface raised parts, and is used in various applications such as vehicle seat upholstery materials, interiors, shoes, bags and gloves.

  On the other hand, silver-like artificial leather is used in the same field as suede-like artificial leather as a substitute for natural leather because of the texture of the polymer elastic body on the surface layer. However, general artificial leather with silver has a problem that the appearance is a regular pattern because of the embossed texture of natural leather, resulting in a strong artificial impression and lack of luxury. .

  In order to improve the above-mentioned artificial impression, by applying liquid bath dyeing to the surface layer part of the artificial leather sheet base material, liquid wrinkle dyeing, random wrinkles enter the surface layer part, making it more natural wrinkled A method that can achieve a close appearance has been proposed (see Patent Document 1).

  In this way, in the artificial leather with silver, it has become possible to achieve an appearance close to a natural wrinkle pattern, but in order to meet the diverse demands of consumers, both a high-quality suede tone and a natural wrinkle pattern are compatible. At present, no new appearance has been achieved.

  In the background described above, several methods have been proposed for imparting an uneven pattern to a suede-like artificial leather. The concavo-convex pattern imparting method is as follows. In the entanglement of the nonwoven fabric constituting the artificial leather, a method has been proposed in which a high-speed fluid is jetted into the nonwoven fabric in a streak shape to adjust the tightness of the entanglement of the nonwoven fabric to provide irregularities (see Patent Document 2). ). In addition, another method has been proposed in which an artificial leather having a raised surface is embossed to provide an uneven pattern on the surface (see Patent Document 3). However, in any of these methods, the concavo-convex pattern has regularity and has a suede-like high-grade, but has an artificial appearance, a suede-like high-grade, and random unevenness of natural leather. The present condition is that the achievement means of the quality which balances the natural wrinkle pattern which consists of is not found.

JP2007-46183 JP 61-207664 A JP 58-151250 A

  Therefore, an object of the present invention is not only a conventional high-strength and excellent shape stability, but also a suede in an artificial leather in which a polymer elastic body is provided as a binder to a non-woven fabric made of ultrafine fibers and a sheet substrate made of woven or knitted fabric. Another object of the present invention is to provide an artificial leather sheet that has a high quality of tone and has a new pattern with an appearance resembling a natural texture pattern, the surface layer of the artificial leather having random irregular irregularities.

  Another object of the present invention is to provide a method for efficiently producing artificial leather having the above characteristics by employing a heat shrink treatment.

  As a result of intensive studies to achieve the above-mentioned problems, the inventors of the present invention have realized that the artificial leather surface layer portion is made of random and irregular irregularities, and in order to achieve an appearance that closely resembles a natural texture, In an artificial leather in which a polymer elastic body is applied as a binder to a sheet substrate having napped surfaces on the surface of the nonwoven fabric formed of a nonwoven fabric and a woven / knitted fabric, the nonwoven fabric layer in the upper layer portion of the woven / knitted fabric inserted into the artificial leather By making the woven fabric thicker than the woven or knitted fabric, in the finishing process such as dyeing, the woven / knitted fabric layer portion in the artificial leather sheet base and the raised surface side layer portion of the nonwoven fabric have gentle unevenness caused by the difference in shrinkage stress between the two layers. The present inventors have found that it is important to generate it, and have reached the present invention.

  That is, the artificial leather of the present invention is an artificial leather in which a polymer elastic body is provided as a binder on a sheet base having napped surfaces on a nonwoven fabric surface in which a nonwoven fabric made of ultrafine fibers and a woven or knitted fabric are intertwined and integrated. The napped-side surface layer portion of the nonwoven fabric is formed of a plurality of convex portions separated by concave portions, the height difference of the convex portions is 70 μm or more and 500 μm or less, and the width is 200 μm or more and 2000 μm or less. It is a featured artificial leather.

  According to a preferred aspect of the artificial leather of the present invention, the plurality of convex portions are separated by the concave portions and are independent, and the shapes of the convex portions are random irregular and all have patterns formed in different shapes. The upper surface of the convex portion has a gentle convex curved surface.

  According to a preferred aspect of the artificial leather of the present invention, in the cross section of the artificial leather, the thickness of the nonwoven fabric intertwined with the woven or knitted fabric is 70% to 95% thick with respect to the total thickness of the artificial leather. It is.

  In the method for producing artificial leather of the present invention, a polymer elastic body is applied as a binder to a sheet substrate having napped surfaces on a nonwoven fabric surface in which a nonwoven fabric made of ultrafine fibers and a woven or knitted fabric are intertwined and integrated. In the method for manufacturing artificial leather, a woven or knitted fabric having an area shrinkage of 10% or more and 20% or less at a temperature of 120 ° C. is used as the woven or knitted fabric, and the thickness of the nonwoven fabric intertwined with the woven or knitted fabric is artificially determined. The woven or knitted fabric is shrunk by adjusting it to 70% or more and 95% or less with respect to the entire thickness of the leather, and the height difference is 70 μm or more and 500 μm or less and the width is 200 μm on the surface layer side of the nonwoven fabric. A plurality of convex portions having a size of 2000 μm or less and separated by concave portions are formed.

  That is, in the method for producing artificial leather, a woven or knitted fabric having an area shrinkage of 10% or more and 20% or less at a temperature of 120 ° C. is used as the woven or knitted fabric, and the upper layer portion of the woven or knitted fabric inserted into the artificial leather. It is important to adjust the layer thickness of the nonwoven fabric so that the layer thickness of the nonwoven fabric is 70% to 95% with respect to the total thickness of the artificial leather. Thereby, in the heat treatment in the finishing process such as the dyeing process, the height difference is 70 μm or more and 500 μm or less, resulting from the difference in shrinkage stress between the layer part of the woven or knitted fabric in the artificial leather and the surface layer part of the napped side of the nonwoven fabric. A plurality of convex portions having gentle convex curved surfaces of 200 μm or more and 2000 μm or less can be formed on the surface layer portion of the artificial leather.

  In this invention, a surface layer part means the surface site | part located in the napped side of a nonwoven fabric as above-mentioned.

  According to the present invention, not only has high strength and excellent shape stability, but also has a high quality of suede tone, and the artificial leather surface layer portion is made of irregular irregularities that are random, with an appearance that closely resembles natural wrinkles. An artificial leather sheet having a novel pattern is obtained.

  The artificial leather of the present invention comprises a suede-like artificial leather base material in which a woven or knitted fabric is entangled and integrated, and the inserted woven or knitted fabric has high strength and excellent shape stability. Furthermore, the surface layer part is formed with multiple convex parts separated by concave parts with natural appearance, which the natural leather has, and the appearance has not only the lighting effect effect produced by the raised parts of the suede-like artificial leather, It is an artificial leather with a new surface layer that has a natural leather-like pattern. Furthermore, in this invention, the surface layer with a natural leather feeling is reproducible cheaply by employ | adopting the heat shrink process of a suede-like artificial leather base material.

FIG. 1 is a drawing-substituting photograph for illustrating a cross-section of the artificial leather obtained in Example 1 of the present invention, and explaining the shape of the convex part of the surface layer part and the ratio of the nonwoven fabric on the upper part of the fabric. FIG. 2 is a drawing-substituting photograph for illustrating a cross-section of the artificial leather obtained in Comparative Example 1, and for explaining the shape of the convex part of the surface layer part and the ratio of the nonwoven fabric on the upper part of the fabric. FIG. 3 is a schematic cross-sectional view for explaining the structure of the artificial leather of the present invention. FIG. 4 is a schematic plan view of the surface layer pattern of the artificial leather of the present invention.

<Artificial leather>
The artificial leather of the present invention is composed of a sheet substrate having napping on a nonwoven fabric surface in which a nonwoven fabric mainly composed of ultrafine fibers and a woven or knitted fabric are intertwined and a polymer elastic body, and a surface layer portion of the artificial leather is composed of gentle irregularities. It is artificial leather.

  FIG. 3 is a schematic cross-sectional view for explaining the basic structure of the artificial leather of the present invention. In the artificial leather of the present invention, a woven / knitted fabric 1 and a nonwoven fabric 2 are entangled and laminated, and a raised portion 3 made of fibers constituting the nonwoven fabric 2 is formed on the upper surface of the nonwoven fabric 2.

  The artificial leather of the present invention is an artificial leather in which a polymer elastic body is applied as a binder to a sheet substrate composed of a nonwoven fabric and a woven or knitted fabric formed of ultrafine fibers. A concave portion consisting of gentle irregularities having a height difference of 70 μm or more and 500 μm or less and a width of 200 μm or more and 2000 μm or less by creating gentle irregularities on the surface layer from the difference in shrinkage stress between the artificial leather surface layer and the inner layer of the artificial leather sheet base material It is the artificial leather which has the surface layer part in which the some convex-shaped part divided | segmented by is formed. As described above, the surface layer portion is a surface portion on the napped portion 3 side of the nonwoven fabric 2 (see FIG. 3).

  If the height difference of the convex portion is less than 70 μm, the surface layer portion of the artificial leather has little unevenness, and it is about the quality of the conventional suede-like artificial leather. Conversely, if the height difference is larger than 500 μm, the surface layer portion unevenness is too large, The direction of the napped fibers on the surface part will fall apart, and the lighting effect of the suede artificial leather will be lost. The height difference is preferably 70 μm or more and 500 μm or less, and more preferably 100 μm or more and 350 μm or less.

  On the other hand, with respect to the width of the convex portion, when the width is less than 200 μm, the unevenness becomes fine, the texture pattern is not sufficiently developed, the quality of the conventional suede-like artificial leather is improved, and when the width is greater than 2000 μm, Although the pattern of the shape appears, it lacks a sense of quality due to the denseness of the pattern. The width is preferably 200 μm or more and 2000 μm or less, and more preferably 400 μm or more and 1500 μm or less.

  FIG. 4 is a schematic plan view of the surface layer pattern of the artificial leather of the present invention. In FIG. 4, the plurality of convex portions 4 are separated by the concave portions 5 and exhibit independent random irregular patterns. Such an irregular pattern is achieved for the first time by the manufacturing method of the present invention described later.

  The area shrinkage rate of the woven or knitted fabric used in the artificial leather of the present invention is important for widening the difference in shrinkage stress between the surface layer portion and the inner layer portion of the woven or knitted fabric after applying the polymer elastic body, and causing distortion in the artificial leather. The shrinkage ratio of the woven fabric so that the dry heat area shrinkage ratio at a temperature of 120 ° C. is 10% or more and 20% or less of a woven or knitted fabric having a shrinkage stress higher than that of the surface layer of the nonwoven fabric generally made of ultrafine fibers. Is preferably adjusted. When the dry heat area shrinkage rate of the woven or knitted fabric is less than 10%, the shrinkage stress inside the artificial leather is small, and sufficient gentle unevenness cannot be expressed on the surface layer portion. Moreover, when the dry heat area shrinkage rate of the woven or knitted fabric is larger than 20%, the artificial leather itself is distorted. The dry heat area shrinkage ratio is more preferably 11% or more and 15% or less.

  Examples of the single yarn constituting the woven or knitted fabric used in the artificial leather of the present invention include single yarns made of synthetic fibers such as polyester fibers and polyamide fibers, and from the viewpoint of dyeing fastness and the like, The same material is preferable. Examples of the form of such a single yarn include filament yarn and spun yarn. These strong twisted yarns are preferably used in order to maintain high physical properties.

  Since the spun yarn has many defects of surface fluff, it is preferable to use a filament yarn.

  The single fiber fineness is preferably 0.01 dtex or more and 3.5 dtex or less, more preferably 0.1 dtex or more and 1.0 dtex or less. When the single fiber fineness is less than 0.01 dtex, there are many breaks in the single yarn due to the needle punch, which is not preferable in terms of deterioration of physical properties of the product. In addition, if the single fiber fineness is greater than 3.5 dtex, the exposure of the fibers constituting the woven or knitted fabric to the product surface layer is conspicuous due to the difference in dyeability with the ultrafine fibers constituting the nonwoven fabric layer, and the product quality tends to decrease. Show.

  The diameter of the single yarn constituting the woven or knitted fabric is preferably 50 μm or more and 300 μm or less, and more preferably 100 μm or more and 200 μm or less. When the diameter of the single twisted yarn is smaller than 50 μm, the shrinkage stress of the woven or knitted fabric layer portion during shrinkage in the dyeing process is reduced. If the diameter of the single twisted yarn is larger than 300 μm, the shrinkage stress of the woven or knitted fabric layer portion in the dyeing process is high, but the entanglement between the nonwoven fabric web and the woven or knitted fabric by the needle punch becomes insufficient, and the shape stability of the product is improved. Shows a downward trend.

  Furthermore, for the woven or knitted fabric, a woven fabric is preferably used in order to enhance the shape stability of the artificial leather. In particular, a plain weave excellent in form stability is preferably used. The weave density of the plain weave is preferably 40 / inch to 120 / inch, more preferably 60 / inch to 90 / inch. There is a tendency that the weave density is less than 40 pieces / inch and the shape stability is lacking. On the other hand, when the weave density is higher than 120 / inch, the fabric is greatly distorted and the texture tends to be hard.

  On the other hand, the structure of the single fiber constituting the single yarn of the woven fabric can be made a high-viscosity polymer and a low-viscosity polymer in a side-by-side structure to increase the shrinkage rate. By making the high-viscosity polymer and the low-viscosity polymer into a side-by-side structure, stress concentrates on the high-viscosity side during stretching, thereby causing different internal strains between the two components. Due to the internal strain, the high-viscosity side is greatly shrunk due to the heat shrinkage difference during the heat shrinking process, and strain is generated in the single fiber, so that the shrinkage rate can be increased. In addition, the number of single yarn twists, weave density, etc. may be adjusted to adjust the area shrinkage of the woven fabric at a temperature of 120 ° C. to 10% or more and 20% or less.

  When using a strongly twisted yarn, the number of twists is preferably 1000 T / m or more and 4000 T / m or less, more preferably 1500 T / m or more and 3500 T / m or less. When the number of twists is less than 1000 T / m, the single fiber breakage of the ultrafine fibers due to the needle punch increases, and the physical properties of the product are lowered and the exposure of the single fibers to the product surface tends to increase. When the twist number is greater than 4000 T / m, the single fiber breakage is suppressed, but the single yarn (strongly twisted yarn) constituting the woven fabric becomes too hard, and thus tends to cause hardening of the texture. In addition, by reducing the number of twists, not only can the lengthwise shrinkage of the entire single yarn constituting the fabric due to shrinkage of the single yarn be increased, but also the flatness of the single yarn increases, and the warp of the fabric By increasing the friction at the intersection, the shrinkage of the fabric can be increased.

  The ultrafine fibers constituting the nonwoven fabric used in the artificial leather of the present invention have a single fiber fineness of 1.0 dtex or less and 0.001 dtex in order to improve the performance as an artificial leather, that is, flexibility, touch, appearance quality and strength properties. It is preferable that it is the structure which can express the above ultrafine fiber.

  Examples of the polymer constituting the ultrafine fiber used in the present invention include polyester polymers such as polyethylene terephthalate, polybutylene terephthalate and polyester elastomer, polyamide polymers such as nylon 6, nylon 66 and polyamide elastomer, polyurethane polymers, Any polymer having a fiber form, such as a polyolefin polymer and an acrylonitrile polymer, can be used, but polyester and polyamide polymers are preferably used from the viewpoint of practical performance.

  Nonwoven fabrics used in the artificial leather of the present invention include short fiber nonwoven fabrics obtained by forming staple webs with a card or cross wrap and then needle punching or water jet punching, spunbonding or melt blown. A long-fiber nonwoven fabric obtained by a method or the like, a nonwoven fabric obtained by a papermaking method, or the like can be employed. Among them, the short fiber nonwoven fabric is preferably used because a napped fiber length is uniform and good.

  The thickness of the nonwoven fabric is important in order to develop random irregularities on the surface layer portion of the artificial leather. By making the nonwoven fabric layer thicker than the woven or knitted fabric layer, the nonwoven fabric layer on the upper side of the woven or knitted fabric in the artificial leather is made thicker. To do. Moreover, the thickness adjustment of the layer of the nonwoven fabric in the upper part of the woven or knitted fabric in the artificial leather can be adjusted by the grinding amount of the surface layer portion of the nonwoven fabric of the artificial leather in the buff process of the manufacturing method described later. Considering the manufacturing cost, the latter is preferable because less nonwoven fabric is discarded.

  The thickness of the sheet substrate formed by intertwining and integrating the nonwoven fabric and the woven / knitted fabric used in the present invention is preferably 0.6 mm or more and 3.9 mm or less, and preferably 1.0 mm or more and 3.0 mm or less. More preferred. If the thickness is smaller than 0.6 mm, the soft texture of the artificial leather is impaired, and if it is larger than 3.9 mm, the shape stability of the artificial leather due to the inserted fabric tends to be poor.

  As the polymer elastic body used in the artificial leather of the present invention, polyurethane, polyurea, polyurethane / polyurea elastomer, polyacrylic acid, acrylonitrile / butadiene elastomer, styrene / butadiene elastomer, and the like can be used. From the viewpoint of polyurethane, polyurethane is preferably used.

  In addition, the polymer elastic body may contain an elastomer resin such as polyester, polyamide, and polyolefin, an acrylic resin, and an ethylene-vinyl acetate resin. The elastic polymer may be either dissolved in an organic solvent or dispersed in water.

  With respect to a suitable use ratio of the polymer elastic body, the mass of the polymer elastic body with respect to the weight of the sheet substrate is preferably 10% by mass or more and 200% by mass or less, more preferably 20% by mass or more and 180% by mass or more. When the weight of the polymer elastic body is less than 10% by mass, the fiber is largely detached from the artificial leather, and when it exceeds 200% by mass, the texture of the artificial leather becomes hard.

  The polymer elastic body used in the present invention includes a pigment such as carbon black, a dye antioxidant, an antioxidant, a light-resistant agent, an antistatic agent, a dispersant, a softening agent, a coagulation adjusting agent, if necessary. Additives such as flame retardants, antibacterial agents and deodorants may be blended.

<Manufacturing method of artificial leather>
Next, a method for producing the artificial leather of the present invention will be described.

  In the present invention, as means for obtaining a nonwoven fabric composed of ultrafine fibers, it is preferable to use ultrafine fiber generating fibers such as sea-island type composite fibers. Since it is practically difficult to produce a nonwoven fabric directly from ultrafine fibers, a nonwoven fabric is first produced from ultrafine fiber-generating fibers, and ultrafine fibers are generated from the ultrafine fiber-generating fibers in this nonwoven fabric. A nonwoven fabric in which the bundles are intertwined can be obtained.

  The ultra-fine fiber generation type fiber is a sea-island type in which two-component thermoplastic resins with different solvent solubility are used for the sea component and the island component, and the sea component is dissolved and removed using a solvent, etc. It is possible to employ a peelable composite fiber that splits fibers into ultrafine fibers by alternately arranging fibers or two-component thermoplastic resin radially or in a multilayer shape on the fiber cross section, and separating and separating each component.

  For sea-island type fibers, sea-island type composite fibers that use a sea-island type composite base to spun two components of the sea component and the island component, and mixed spinning that mixes and spins the two components of the sea component and the island component are spun. Although there are fibers, sea-island type composite fibers are particularly preferable because ultrafine fibers with a uniform fineness can be obtained, and because a sufficiently long ultrafine fiber is obtained and contributes to the strength of the sheet substrate (fiber entangled body). Used.

  As the sea component of the sea-island fiber, polyethylene, polypropylene, polystyrene, copolymerized polyester obtained by copolymerizing sodium sulfoisophthalic acid, polyethylene glycol, or the like, and polylactic acid can be used.

  The sea component may be dissolved and removed at any stage before, after, or after raising the polymer elastic body.

  Further, as the island component of the sea-island fiber, the polymer constituting the ultrafine fiber described above is used.

  As the method for obtaining the nonwoven fabric used in the present invention, as described above, a method of entanglement of the fiber web with a needle punch or a water jet punch, a spun bond method, a melt blow method, a paper making method, and the like can be employed. In order to obtain a state of such an ultrafine fiber bundle as described above, a method such as needle punching or water jet punching is preferably used. In the present invention, as described above, a short fiber nonwoven fabric obtained by applying these, a long fiber nonwoven fabric obtained from a spunbond method or a melt blow method, a nonwoven fabric obtained by a papermaking method, or the like can be employed. Among them, the short fiber nonwoven fabric is preferably used because a napped fiber length is uniform and good.

  In addition, a needle punch, a water jet punch, or the like is preferably used from the viewpoint of fiber entanglement for laminating and integrating the nonwoven fabric and the woven or knitted fabric.

In addition, in order to prevent wrinkling when the nonwoven fabric and the woven / knitted fabric are separated and integrated with the needle punch, the preliminary entanglement is given before the nonwoven fabric and the woven / knitted fabric are entangled and integrated. desirable. Thus, when a method of preliminarily entangling with a needle punch is adopted, it is effective that the needle punch density is 20 lines / cm ² or more, preferably 100 lines / cm. Pre-entanglement is preferably given at a needle punch density of ² or more, and more preferably pre-entanglement is given at a needle punch density of 300 / cm ^{2 to} 1300 / cm ² .

At a needle punch density of less than 20 pre-entanglements / cm ² , the width of the nonwoven fabric leaves room for narrowing at the time of entanglement with the woven or knitted fabric and subsequent needle punches. This is because wrinkles may occur in the woven or knitted fabric with the change, and a smooth sheet substrate may not be obtained. Moreover, when the needle punch density of the pre-entanglement is 1300 / cm ² or more, generally, the non-woven fabric itself is excessively entangled so that the entanglement with the fibers constituting the woven or knitted fabric is sufficiently formed. This is because the room is reduced, which is disadvantageous for realizing a non-separated integrated structure in which the nonwoven fabric and the woven or knitted fabric are firmly intertwined.

In the present invention, when the woven and knitted fabric and the nonwoven fabric are entangled and integrated, the needle punch density range is preferably 300 / cm ^{2 to} 6000 / cm ^2, and 1000 / cm ^{2 to} 3000 / A more preferred embodiment is cm ² .

  For entanglement of the nonwoven fabric and the woven or knitted fabric, the woven or knitted fabric is laminated on one or both sides of the nonwoven fabric, or the fibers are entangled by pinching the woven or knitted fabric between a plurality of nonwoven fabric webs and needle punching. It can be.

  Moreover, when performing a water jet punch process, it is preferable to perform water in the state of a columnar flow. Specifically, water is preferably ejected from a nozzle having a diameter of 0.05 to 1.0 mm at a pressure of 1 to 60 MPa.

It is preferable that the apparent density of the nonwoven fabric made of the ultrafine fiber generating fiber after the needle punching process or the water jet punching process is 0.15 to 0.30 g / cm ³ . By setting the apparent density to 0.15 g / cm ³ or more, an artificial leather having sufficient form stability and dimensional stability can be obtained. On the other hand, when the apparent density is 0.30 g / cm ³ or less, a sufficient space for applying the polymer elastic body can be maintained.

  From the viewpoint of densification, it is preferable that the nonwoven fabric made of ultrafine fiber-generating fibers thus obtained is contracted by dry heat or wet heat, or both, and further densified.

  As the solvent that dissolves the easily soluble polymer that is the sea component from the ultrafine fiber-generating fiber constituting the nonwoven fabric, if the sea component is a polyolefin such as polyethylene or polystyrene, an organic solvent such as toluene or trichloroethylene is used. If the component is polylactic acid or copolymer polyester, an aqueous alkali solution such as sodium hydroxide can be used. Further, this ultrafine fiber generation processing (sea removal treatment) can be performed by immersing a non-woven fabric made of ultrafine fibers in a solvent and squeezing it.

  In the present invention, N, N'-dimethylformamide, dimethyl sulfoxide, or the like is used as a solvent used when polyurethane is imparted as a polymer elastic body, and a water dispersion type in which polyurethane is dispersed as an emulsion in water. A polyurethane liquid may be used.

  When a sheet substrate (fiber entangled body) made of a nonwoven fabric and a woven or knitted fabric is immersed in a polymer elastic body solution dissolved in a solvent, the polymer elastic body is applied to the sheet substrate containing the nonwoven fabric, and then dried to increase the thickness. The molecular elastic body is substantially solidified and solidified. In the case of a solvent-based polyurethane solution, it can be solidified by dipping in a non-soluble solvent. Further, in the case of a water-dispersed polyurethane liquid having gelling properties, it can be solidified by a dry solidification method in which it is gelled and then dried. In drying, the sheet substrate (fiber entangled body) and the elastic polymer may be heated at a temperature that does not impair the performance.

  With respect to a suitable use ratio of the polymer elastic body, the mass of the polymer elastic body with respect to the weight of the sheet substrate is preferably 10% by mass or more and 200% by mass or less, more preferably 20% by mass or more and 180% by mass or more. When the weight of the polymer elastic body is less than 10% by mass, the fibers fall off from the artificial leather, and when it exceeds 200% by mass, the texture of the artificial leather tends to be hard.

The artificial leather of the present invention has napping on at least one side. Napping is formed on the nonwoven fabric surface. The napping treatment can be performed by buffing the surface of the nonwoven fabric using a sandpaper or a roll sander. In particular, by using sandpaper, uniform and dense napping can be formed. Furthermore, in order to form uniform napping on the surface of the artificial leather sheet substrate, it is preferable to reduce the grinding load. In order to reduce the grinding load, for example, the number of buffs is preferably multi-stage buffing with 3 or more stages, and the sandpaper count used in each stage should be in the range of No. 150 to 600 of JIS regulations. This is a preferred embodiment. The surface nap length can be uniformly finished by gradually reducing the count.
The buffing step is an important step for increasing the thickness of the nonwoven fabric layer in order to develop random irregularities on the surface layer portion of the artificial leather. For this purpose, the grinding amount of the surface layer portion is preferably 100 μm or more and 500 μm or less. If the amount of grinding is less than 100 μm, the layer of the nonwoven fabric can be thickened, but unevenness may occur in the length of the napped fibers. On the other hand, when the grinding amount is larger than 500 μm, grinding scraps increase, so that sandpaper is frequently clogged and processing stability may be poor.

  The artificial leather of the present invention is suitably dyed. Dyeing is preferably carried out using a high-temperature and high-pressure dyeing machine in order to soften the texture of the artificial leather base sheet to be dyed using disperse dyes, cationic dyes and other reactive dyes. The dyeing temperature is preferably 80 ° C to 150 ° C, more preferably 110 ° C or higher.

  Furthermore, if necessary, a finishing treatment such as a softener such as silicone, an antistatic agent, a water repellent, a flame retardant, and a light-resistant agent may be performed. The finishing treatment may be performed after dyeing or in the same bath as dyeing.

  In the present invention, in the sheet base material constituting the artificial leather after application of the binder of the polymer elastic body, it is possible to increase the difference in shrinkage stress between the woven fabric and the napped surface layer portion of the nonwoven fabric in the sheet base material. It is important for developing a new pattern that has a high quality of artificial leather and closely resembles natural wrinkles made of random and gentle irregularities. Specifically, the thickness of the nonwoven fabric layer above the woven or knitted fabric in the artificial leather sheet base material in the finishing step such as the dyeing step, particularly the dyeing step, may be 70% or more and 95% or less with respect to the thickness of the artificial leather. This is a particularly preferred embodiment. When the thickness of the nonwoven fabric layer is less than 70%, the shrinkage stress of the woven or knitted fabric having a large shrinkage rate in the artificial leather spreads throughout the nonwoven fabric layer having a small shrinkage rate, and the napped surface layer portion of the nonwoven fabric is a layer of the woven or knitted fabric. Since it shrinks in the same manner, only the fine irregularities similar to the woven or knitted fabric layer appear on the surface layer portion of the nonwoven fabric, and the appearance becomes a uniform surface layer of the suede-like artificial leather. On the other hand, if the thickness of the non-woven fabric layer is higher than 95%, excessively gentle irregularities are developed, so that the embossed pattern is thin and difficult to visually judge.

  When the thickness of the nonwoven fabric layer on the upper part of the woven or knitted fabric in the artificial leather sheet substrate is set to 70% or more and 95% or less with respect to the thickness of the artificial leather, a surface-like pattern that can be visually judged is expressed on the surface layer portion of the nonwoven fabric. A gentle unevenness is developed. Since the nonwoven fabric layer is thick, the strong shrinkage stress generated in the woven / knitted fabric layer is relieved internally, and the fine irregularities that appear when the thickness of the nonwoven fabric layer is less than 70% are combined. A plurality of uneven surface layer portions appear.

Further, in order to make the uneven pattern expressing a natural wrinkled pattern more prominent, the shrinkage rate of the woven or knitted fabric entangled with each other is increased, and in particular, the internal strain of the artificial leather sheet substrate in the dyeing process is increased. It is effective. That is, it is a particularly preferable aspect to design the woven or knitted fabric so that the area shrinkage rate at a dry heat of 120 ° C. is 10% or more and less than 20%. When the dry heat shrinkage rate of the woven or knitted fabric is less than 10%, there is little distortion inside the artificial leather sheet substrate, and the surface unevenness is low. On the other hand, if the area shrinkage rate at 120 ° C. of the woven or knitted fabric is larger than 20%, the artificial leather sheet base material itself may be distorted.
The artificial leather of the present invention has not only high strength and excellent shape stability, but also has an artificial leather surface layer with random irregularities and an appearance that resembles a natural wrinkle, and uses a conventional suede-like artificial leather. It can be used in a wide range of applications, from furniture, chairs and vehicle interior materials to clothing applications.

  EXAMPLES Next, although an Example is given and this invention is demonstrated in more detail, this invention is not limited by these Examples.

[Measuring method and processing method for evaluation]
(1) Method for measuring convex-shaped height difference of surface layer of artificial leather A cross section perpendicular to the thickness direction of the artificial leather was observed with a scanning electron microscope (VE-7800 manufactured by SEM Keyence) at a magnification of 100 times. The height difference of the convex part observed is measured as the distance AB between the uppermost point A and the lowermost point B shown in FIGS. 1 and 2, and evaluated by an average value of 20 convex parts extracted at random. did. For the lowest point B, the lower one of the positions (0 °) at which the slopes of both ends disappear in the convex portion was selected.

(2) Measurement of convex part width of surface layer part of artificial leather A cross section perpendicular to the thickness direction of the artificial leather was observed with a scanning electron microscope (VE-7800 manufactured by SEM Keyence) at a magnification of 100 times and observed. The width C of the convex portion to be measured was measured as the distance C in FIGS. 1 and 2, and the average value of 20 convex portions extracted at random was evaluated. The width C of the convex portion was evaluated as the distance between both ends of the convex portion determined by the above-described height difference evaluation.

(3) Method for measuring the ratio of the nonwoven fabric layer on the upper part of the fabric in the artificial leather The cross section perpendicular to the thickness direction of the artificial leather was observed with a scanning electron microscope (VE-7800 manufactured by SEM Keyence) at a magnification of 100 times. Evaluation was made as a ratio of the distance E to the thickness D of the observed artificial leather (total thickness of the woven and knitted fabric and non-woven fabric excluding the raised portions), and the average value of 20 points of randomly extracted convex portions was evaluated. The thickness D of the artificial leather indicates the thickness of the sheet substrate excluding the raised portions of the artificial leather, and E indicates the thickness of the non-woven fabric layer on the woven or knitted fabric in the artificial leather. The position of the upper layer of the fabric was evaluated as the uppermost portion of the observed cross section of the fabric.

(4) Dry heat area shrinkage of woven or knitted fabric The dry heat area of the woven or knitted fabric from the rate of change in the length and width of the woven or knitted fabric after heating the woven or knitted fabric (10 cm × 10 cm) at 120 ° C. for 20 minutes. Shrinkage was calculated.

(5) Surface quality evaluation of artificial leather Evaluation is made by sensory inspection of 10 subjects. Eight or more people determined to have natural wrinkle-like irregularities (irregular turtle shell wrinkle-like patterns on the surface of natural leather) (double circles), and those judged by 5-7 ( (Single circle), 3-4 people judged (triangle), 2 or less people judged (x). Double circle and single circle were accepted. In this determination, a value close to the conventional suede-like surface quality is a low determination.

[Example 1]
<Raw cotton>
Polyethylene terephthalate is used as the island component, polystyrene is used as the sea component, and a sea-island type composite die having 36 islands is melt-spun at an island / sea mass ratio of 55/45, and then stretched and crimped. Thereafter, it was cut into a length of 51 mm to obtain a raw material of sea-island type composite fiber having a single fiber fineness of 3.1 dtex.

<Entanglement of nonwoven fabric and woven / knitted fabric (sheet substrate)>
Using the above-mentioned raw material of sea-island type composite fiber, a laminated web is formed through a card and cross wrapping process, and the number of punches is 100 / cm ^{2 in} order to suppress fabric wrinkles due to a sudden change in width after fabric bonding. Needle punched. Separately, it is a single yarn of side-by-side structure composed of polyethylene terephthalate with an intrinsic viscosity (IV) of 0.78 and polyethylene terephthalate with an intrinsic viscosity (IV) of 0.51, and a multifilament with a twist number of 1500 T / m (56 dtex, 12 filaments) Is used as a weft, multifilaments (84 dtex, 72 filaments) having a twist of 2500 T / m with a single component having an intrinsic viscosity (IV) of 0.65 as warp, and a weaving density of 69 warps / 2. A plain woven fabric having a dry heat area shrinkage ratio of 11.7% at 54 cm and 84 wefts / 2.54 cm was woven. The obtained plain woven fabric was laminated on the upper and lower sides of the laminated web.
Thereafter, needle punching was performed with a punch number (density) of 2500 / cm ² to obtain a sheet substrate having a basis weight of 740 g / m ² and a thickness of 3.1 mm.

<Artificial leather>
The sheet substrate obtained above is shrunk with hot water at a temperature of 96 ° C., then impregnated with a PVA (polyvinyl alcohol) aqueous solution, and dried with hot air at a temperature of 110 ° C. for 10 minutes, thereby reducing the weight of the sheet substrate. A sheet substrate having a PVA weight of 22% by weight was obtained. This sheet substrate was dipped in trichlorethylene to dissolve and remove the sea component polystyrene, thereby obtaining a sea removal sheet in which ultrafine fibers and plain fabric were entangled. The seawater-free sheet composed of the nonwoven fabric and the plain fabric thus obtained was immersed in a polyurethane DMF (dimethylformamide) solution adjusted to a solid content concentration of 12%, and then an aqueous solution having a DMF concentration of 30%. The polyurethane was coagulated in it. Thereafter, PVA and DMF are removed with hot water and dried with hot air at a temperature of 110 ° C. for 10 minutes, whereby an artificial leather sheet having a polyurethane weight of 20% by weight with respect to the total weight of the ultrafine fibers made of island components and the plain fabric is obtained. A substrate was obtained.

  The artificial leather sheet substrate thus obtained was cut in half in the thickness direction and the nonwoven fabric layer inside the substrate vertically, and the cut nonwoven fabric surface was ground by 100 μm with an endless sandpaper of sandpaper number 240 A raised surface was formed on the surface layer portion to obtain an artificial leather sheet substrate having a thickness of 0.75 mm. The artificial leather sheet substrate thus obtained was subjected to shrinkage treatment and dyeing at the same time under a temperature of 120 ° C. using a liquid dyeing machine, and then dried with a dryer to produce artificial leather. Got. The artificial leather obtained in this way can clearly determine the irregularities of the surface layer at random and irregularities, and has a lighting effect of a suede-like artificial leather, which is a novel that resembles a natural texture. It had a random pattern surface layer. Further, as shown in FIG. 1, the convex portion of the surface layer portion has a width of 581 μm, a height of 114 μm, a width of 200 μm or more and 2000 μm or less, and a height of 70 μm or more and 500 μm or less. The upper surface of the shaped part exhibited a gentle convex curve, and the ratio of the nonwoven fabric layer on the upper side of the woven fabric in the cross section of the artificial leather was 73% and 70% or more. Moreover, the product strength was high and the form stability was excellent. The results are shown in Table 1.

[Example 2]
<Raw cotton>
Polyethylene terephthalate is used as the island component, polystyrene is used as the sea component, a sea-island type composite die having 16 islands is melt-spun at an island / sea mass ratio of 80/20, and then stretched and crimped. Then, it was cut into a length of 51 mm to obtain a raw material of sea-island type composite fiber having a single fiber fineness of 4.2 dtex.

<Entanglement of nonwoven fabric and woven / knitted fabric (sheet substrate)>
The number of punches of 100 / cm ² is used to form a laminated web through the card and cross wrapping process using the above-mentioned raw material of the island-shaped composite fiber, and to suppress fabric wrinkles due to a sudden width change after the fabrics are bonded. A needle web was punched to obtain a laminated web. Separately, a single yarn composed of a single component of polyethylene terephthalate having an intrinsic viscosity (IV) of 0.65, a multifilament (84 dtex, 72 filaments) having a twist number of 2500 T / m, and a weft density of 96 yarns / A plain weave was woven at 2.54 cm, weft 76 / 2.54 cm, and a dry heat area shrinkage of 10.2%. The obtained plain woven fabric was laminated on the upper and lower sides of the laminated web. Thereafter, needle punching was performed at a punch number of 3000 / cm ² to obtain a sheet substrate having a basis weight of 710 g / m ² and a thickness of 3.0 mm.

<Artificial leather>
Except that the amount of PVA applied to the sheet substrate obtained above was changed to 7.5%, in the same manner as in Example 1, the surface layer portion of the half-cut nonwoven fabric was ground by 100 μm, and an artificial thickness of 1.10 mm was obtained. The leather sheet base material was dyed to obtain artificial leather. The artificial leather obtained in this way can clearly determine the irregularities of the surface layer at random and irregularities, and has a lighting effect of a suede-like artificial leather, which is a novel that resembles a natural texture. It had a random pattern surface layer. Further, the surface layer convex portion has a width of 258 μm, a height of 82 μm, a width of 200 μm or more and 2000 μm or less, and a height of 70 μm or more and 500 μm or less. The convex portion is partitioned by a concave portion, and the upper surface of the convex portion is a gentle convex shape In the cross section of the artificial leather, the ratio of the nonwoven fabric layer on the upper side of the woven fabric was 74% and 70% or more in the artificial leather cross section. Moreover, the product strength was high and the form stability was excellent. The results are shown in Table 1.

[Example 3]
<Raw cotton>
By using polyethylene terephthalate as the island component, copolymerized polyethylene terephthalate copolymerized with 8 mol% of 5-sodium isophthalic acid as the sea component, and using a sea-island type composite base with 16 islands, After melt spinning at a mass ratio of 60/40, stretching and crimping were performed, and then cut to a length of 51 mm to obtain a sea-island composite fiber raw cotton having a single fiber fineness of 5.0 dtex.

<Entanglement of nonwoven fabric and woven / knitted fabric (sheet substrate)>
Except having used said raw cotton, it processed similarly to Example 2, and obtained the sheet | seat base | substrate of 883 g / m < ² > of fabric weights and thickness 3.5mm.

<Artificial leather>
Sodium sulfate as a heat-sensitive gelling agent is added to the nonionic forced emulsification type polyurethane emulsion (polycarbonate), which is a water-dispersed polyurethane liquid, in an amount of 4% by mass relative to the polyurethane solid content, so that the polyurethane liquid concentration becomes 10% by mass. A water-dispersed polyurethane liquid was prepared. The sheet base obtained as described above is provided with the water-dispersed polyurethane liquid, dried with hot air at a drying temperature of 120 ° C. for 5 minutes, and is based on the total weight of the ultrafine fibers made of island components and the woven fabric. An artificial leather sheet base material having a polyurethane weight of 30% by weight was obtained.

  The polyurethane-coated sheet base material obtained as described above is immersed in a 40 g / L sodium hydroxide aqueous solution heated to 90 ° C. and treated for 30 minutes to dissolve and remove sea components from the sea-island composite fibers. did. After that, using a half-cutting machine having an endless band knife, cut in half in the direction perpendicular to the thickness direction, the half-cut surface of the cut non-woven fabric is ground in three steps using JIS # 320 sandpaper, and the surface layer is ground by 150 μm. Then, napping was formed to produce a sheet base material for artificial leather. The artificial leather sheet substrate having a thickness of 1.05 mm thus obtained was simultaneously subjected to shrinkage treatment and dyeing using a liquid dyeing machine at a temperature of 120 ° C. and then dried with a dryer. I obtained artificial leather.

  The artificial leather obtained in this way can clearly determine the irregularities of the surface layer at random and irregularities, and has a lighting effect of a suede-like artificial leather, which is a novel that resembles a natural texture. It had a random pattern surface layer. The convex portion of the surface layer portion has a width of 1730 μm, a height of 359 μm, a width of 200 μm or more and 2000 μm or less, and a height of 70 μm or more and 500 μm or less. Exhibited a gentle convex curve, and in the cross section of the artificial leather, the ratio of the nonwoven fabric layer of the upper layer of the fabric in the cross section of the artificial leather was 91% and 70% or more. Moreover, the product strength was high and the form stability was excellent. The results are shown in Table 1.

[Comparative Example 1]
<Raw cotton>
In the same manner as in Example 1, a sea-island composite fiber raw cotton having a single fiber fineness of 3.1 dtex and a fiber length of 51 mm was obtained.

<Entanglement of nonwoven fabric and woven / knitted fabric (sheet substrate)>
A sheet substrate was obtained in the same manner using the same fabric as in Example 1.

<Base for artificial leather>
Artificial leather in the same manner as in Example 1 except that the surface grinding amount of the artificial leather sheet base material in the buffing process was changed to 330 μm and the artificial leather sheet base material having a thickness of 0.55 mm was used in the buffing process. Got for. The artificial leather thus obtained was a uniform surface of a conventional suede-like artificial leather. Further, as shown in FIG. 2, the convex part of the surface layer part has a width of 282 μm and a height of 59 μm and a height difference of less than 70 μm, and in the cross section of the artificial leather, the ratio of the nonwoven fabric layer on the upper part of the fabric in the artificial leather cross section is 60 % And less than 70%. The results are shown in Table 1.

[Comparative Example 2]
<Raw cotton>
In the same manner as in Example 2, a sea-island composite fiber raw cotton having a single fiber fineness of 4.2 dtex and a fiber length of 51 mm was obtained.

<Entanglement of nonwoven fabric and woven fabric (sheet substrate)>
Using the same woven fabric as in Example 2, a sheet substrate was obtained in the same manner as in Example 2.

<Base for artificial leather>
Artificial artificial leather sheet base material in the buffing process was changed to 300 μm and the artificial leather sheet base material having a thickness of 0.91 mm was used in the buffing process. Obtained for leather. The artificial leather thus obtained was a uniform surface without the unevenness of conventional suede-like artificial leather.
Further, the surface layer convex portion has a width of 182 μm, a height of 60 μm, a width of less than 200 μm and a height difference of less than 70 μm, and in the cross section of the artificial leather, the ratio of the nonwoven fabric layer on the upper side of the woven fabric to the cross section of the artificial leather is 64. % And less than 70%. The results are shown in Table 1.

[Comparative Example 3]
<Raw cotton>
In the same manner as in Example 1, a sea-island composite fiber raw cotton having a single fiber fineness of 3.1 dtex and a fiber length of 51 mm was obtained.

<Entanglement of nonwoven fabric and woven fabric (sheet substrate)>
A multifilament (110 dtex, 288 filament) having a twist of 2000 T / m as a single yarn composed of a single component of polyethylene terephthalate having an intrinsic viscosity (IV) of 0.65 is used as a warp, and the weave density is 80 warps / Except for using a plain woven fabric of 2.54 cm, 66 wefts / 2.54 cm, and a dry heat area shrinkage rate of 8.8%, in the same manner as in Example 1, the basis weight is 730 g / m ² and the thickness is 3.0 mm. A sheet substrate was obtained.

<Base for artificial leather>
Artificial leather was obtained in the same manner as in Example 1 except that the surface grinding amount of the artificial leather sheet substrate in the buffing process was changed to 250 μm and the thickness was changed to 0.89 mm in the buffing process. The artificial leather thus obtained was a uniform surface without the unevenness of conventional suede-like artificial leather.
Further, the convex portion of the surface layer portion has a width of 329 μm and a height of 43 μm, and a height difference of less than 70 μm. In the cross section of the artificial leather, the ratio of the non-woven fabric layer on the upper side of the fabric in the artificial leather cross section is 55%. %. The results are shown in Table 1.

A: Top point B: Bottom point C: Width of convex part D: Thickness excluding napped part of artificial leather E: Thickness of non-woven fabric layer 1: Woven knitted fabric 2: Non-woven fabric 3: Napped part 4: Convex part 5: Recess

Claims (4)

  In artificial leather in which a polymer elastic body is applied as a binder to a sheet base having napped surfaces on a non-woven fabric surface in which a non-woven fabric made of ultrafine fibers and a woven or knitted fabric are intertwined, the napped side surface layer portion of the non-woven fabric has The artificial leather is formed of a plurality of convex portions separated by concave portions, the height difference of the convex portions is 70 μm or more and 500 μm or less, and the width is 200 μm or more and 2000 μm or less.   A plurality of convex portions are separated by concave portions and are independent, and the shapes of the convex portions are randomly irregular and all have different shapes, and the upper surface of the convex portion is a gentle convex The artificial leather according to claim 1, which has a curved surface.   The artificial leather according to claim 1 or 2, wherein, in the cross section of the artificial leather, the thickness of the nonwoven fabric intertwined with the woven or knitted fabric is 70% or more and 95% or less with respect to the total thickness of the artificial leather.   In the method for producing artificial leather, in which a polymer elastic body is provided as a binder on a sheet substrate having napped surfaces on a nonwoven fabric surface in which a nonwoven fabric made of ultrafine fibers and a woven fabric are intertwined and integrated, A woven or knitted fabric having an area shrinkage of 10% or more and 20% or less at a temperature of 120 ° C., and the thickness of the nonwoven fabric intertwined with the woven or knitted fabric is 70% or more and 95% of the total thickness of the artificial leather. The woven or knitted fabric is contracted by adjusting to the following and heat-treating the surface, and the napped side surface layer portion of the nonwoven fabric has a height difference of 70 μm to 500 μm and a width of 200 μm to 2000 μm and is separated by a recess. A method for producing artificial leather, comprising forming a plurality of convex portions.