Light-Transmitting Device

Abstract

The present invention provides artificial leather that has a deep color of medium or higher density while also maintaining the feel and texture thereof and having light transmissivity.　Artificial leather according to the present invention comprises an entangled fiber body that comprises ultrafine fibers having an average single fiber diameter of 0.1 μm or more, and a polymer elastic body, wherein: the thickness of the artificial leather is 0.4-1.2 mm; the weight per unit area is 80-450 g / m2; one surface of the artificial leather is a design surface colored with a dye and / or a pigment; and expressions (1)-(3) are satisfied.　(1): L* 1≤55 (2): L* 0>50 (3): ΔL*<-5 In the expressions, L* 1 is the lightness index (L* value) of the design surface in the CIE1976L*a*b* color space, L* 0 is the lightness index (L* value) of the surface on the opposite side from the design surface in the CIE1976L*a*b* color space, and ΔL* is difference between the L* value of the design surface and the L* value of the surface on the opposite side from the design surface (CIELAB1976ab lightness difference, L* 1-L* 0). The lightness indices are values measured with a CIE standard illuminant D65 and a viewing angle of 10°.

Description

[Technical Field]

[0001] The present invention relates to an artificial leather and a light-transmitting device using the same. [Background technology]

[0002] Suede-like artificial leather, made from ultrafine fibers and elastomers, has superior properties not found in natural leather, such as durability and uniformity. Taking advantage of these characteristics, suede-like artificial leather has been used in a wide range of applications, including clothing, furniture, and automotive interiors. In recent years, with the need for further diversification, consideration is being given to using it as a covering material for various home appliances and automobile consoles.

[0003] In this environment, in recent years, for the sake of design, an increasing number of home appliances and automobile consoles have become light-transmitting devices with backlit buttons (keyboards) that emit light themselves. A technology has been proposed that uses suede-like artificial leather, which has traditionally been used for such light-transmitting devices, as the covering material (see, for example, Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-71956 [Patent Document 2] Japanese Patent Application Laid-Open No. 2014-185404 Summary of the Invention [Problem to be solved by the invention]

[0005] In general, when artificial leather is used as a surface material, CIE1976L * a * b * The lightness index in the color space (hereinafter simply referred to as L *Medium- to dark-colored artificial leathers with a light transmittance (sometimes referred to as a "light transmittance value") of 50 or less have poor light transmittance and may not transmit light depending on conditions such as the color of the artificial leather and the light intensity of the light source. For this reason, techniques such as those disclosed in Patent Documents 1 and 2 involve providing cutouts or light-transmitting areas made by turning nonwoven fabric into a film, thereby preventing the creation of areas that substantially block light. However, such techniques involve removing or fusing the artificial leather in areas where light is desired to pass through, which poses a problem of impairing the texture, feel, and quality of the artificial leather.

[0006] The present invention has been made in view of the above circumstances, and its object is to provide artificial leather that is medium to dark in color, yet retains its texture and feel, and also has optical transparency, and a light-transmitting device made using the same. [Means for solving the problem]

[0007] As a result of extensive research to achieve the above object, the inventors have discovered that, in an artificial leather of a specific thickness and basis weight, by setting the color difference between the design surface and the opposite surface within a specific range, it is possible to obtain light transparency while maintaining the texture and feel of artificial leather, even without the need for cutouts or light-transmitting portions made of nonwoven fabric. Even more surprisingly, it has been discovered that even when the design surface of this artificial leather is dark in color, sufficient light transparency is achieved when used as a light-transmitting device.

[0008] The present invention has been completed based on these findings, and provides the following inventions.

[0009] The artificial leather of the present invention is an artificial leather containing, as constituent elements, a fiber-entangled body made of ultrafine fibers having an average single fiber diameter of 0.1 μm or more and 8 μm or less, and a polymeric elastomer, and the thickness of the artificial leather is 0.4 mm or more and 1.2 mm or less, and the basis weight of the artificial leather is 80 g / m 2 More than 450g / m 2The artificial leather has one surface that is a design surface colored with a dye and / or a pigment and satisfies the following formulas (1) to (3). L * 1≦55 (1) L * 0>50 (2) ΔL * <-5 (3) where L * 1 is the design surface CIE1976L * a * b * Lightness index in color space (L * value), L * 0 is the CIE1976L on the surface opposite the design surface * a * b * Lightness index in color space (L * value), ΔL * is the design surface L * value and L on the surface opposite to the design surface * The difference between the values ​​(CIELAB1976ab lightness difference, L * 1-L * 0). The brightness index is a value measured under CIE standard light source D65 conditions and at a viewing angle of 10°.

[0010] According to a preferred embodiment of the artificial leather of the present invention, the fiber-entangled body is dyed with a dye.

[0011] The light transmission device of the present invention includes at least one light source and the above-mentioned artificial leather as at least constituent elements, and is configured by placing the above-mentioned artificial leather on the above-mentioned light source. [Effects of the Invention]

[0012] According to the present invention, artificial leather can be obtained that has excellent light transmittance while maintaining the texture and feel of artificial leather. In particular, the artificial leather of the present invention has excellent light transmittance even though it is a medium- to dark-colored artificial leather that has traditionally had poor light transmittance, and therefore can be suitably used for home appliances, automobile consoles, etc. In particular, when it is made into an artificial leather with raised nap, it can be made into an artificial leather with high-quality light transmittance while maintaining the raised nap and texture of suede leather, and can be effectively used for the above-mentioned applications. DETAILED DESCRIPTION OF THE INVENTION

[0013] The artificial leather of the present invention is an artificial leather containing, as constituent elements, a fiber-entangled body made of ultrafine fibers having an average single fiber diameter of 0.1 μm or more and 8 μm or less, and a polymeric elastomer, and the thickness of the artificial leather is 0.4 mm or more and 1.2 mm or less, and the basis weight of the artificial leather is 80 g / m 2 More than 450g / m 2 The artificial leather has one surface that is a design surface colored with a dye and / or a pigment and satisfies the following formulas (1) to (3). L * 1≦55 (1) L * 0>50 (2) ΔL * <-5 (3) where L * 1 is the design surface CIE1976L * a * b * Lightness index in color space (L * value), L * 0 is the CIE1976L on the surface opposite the design surface * a * b * Lightness index in color space (L * value), ΔL * is the design surface L * value and L on the surface opposite to the design surface * The difference between the values ​​(CIELAB1976ab lightness difference, L * 1-L *0). The brightness index is a value measured under CIE standard illuminant D65 conditions and a viewing angle of 10°. The components will be described in detail below, but the present invention is not limited to the scope described below as long as it does not deviate from the gist of the invention.

[0014] [Ultrafine fiber] The ultrafine fibers constituting the fiber-entangled structure, which is one of the components of the artificial leather of the present invention, have an average single fiber diameter of 0.1 μm or more and 8 μm or less. By setting the average single fiber diameter to 0.1 μm or more, preferably 0.2 μm or more, and more preferably 0.3 μm or more, the artificial leather will have good color fastness, and in particular good light fastness. On the other hand, by setting the average single fiber diameter to 8.0 μm or less, preferably 4.0 μm or less, and more preferably 2.0 μm or less, the artificial leather will have good texture.

[0015] The average single fiber diameter of the ultrafine fibers is calculated by the following method. In the present invention, the average single fiber diameter of the ultrafine fibers is measured as follows and the calculated value is adopted. (1) The fiber-entangled body is cut to expose a cross section in the thickness direction that will be used for observation. (2) A scanning electron microscope (SEM) photograph is taken of the cross section in the thickness direction. (3) Randomly select 100 ultrafine fibers that are circular or nearly circular in shape. (4) The single fiber diameter of the selected ultrafine fibers is measured, and the number average value is calculated.

[0016] Furthermore, the ultrafine fibers of the present invention can be made from various synthetic fibers made from polymers such as polyesters (e.g., polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate, and polyethylene 2,6-naphthalenedicarboxylate), polyamides (e.g., 6-nylon and 66-nylon), acrylic, polyethylene, and polypropylene. Among these, polyester fibers made from polymers (e.g., polyethylene terephthalate, polybutylene terephthalate, and polytrimethylene terephthalate) are preferably used because of their excellent strength, dimensional stability, light resistance, and dyeability. Furthermore, ultrafine fibers made from different materials can be mixed in the fiber-entangled structure, as long as the object of the present invention is not impaired.

[0017] Depending on various purposes, inorganic particles such as titanium oxide particles, lubricants, pigments, heat stabilizers, ultraviolet absorbers, conductive agents, heat storage agents, antibacterial agents, and the like can be added to the ultrafine fibers that constitute the fiber-entangled body.

[0018] The cross-sectional shape of the ultrafine fibers constituting the fiber-entangled structure may be a round cross section, or an irregular cross section such as an oval, flat, or triangular polygon, a sector, or a cross.

[0019] [Fiber entanglement] The fiber-entangled body, which is one of the components of the artificial leather of the present invention, is made of the ultrafine fibers.

[0020] The form of the fiber-entangled body may be a woven fabric, a knitted fabric, a nonwoven fabric, or a fiber-entangled body in which a polymeric elastomer is filled in the fiber structure of any of these, and these may be appropriately selected depending on the cost and properties required for each application or purpose. From the viewpoint of cost, woven fabrics and knitted fabrics are preferably used, while from the viewpoint of quality due to a rich feel and fine nap, nonwoven fabrics and fiber-entangled bodies in which a polymeric elastomer is filled are preferably used.

[0021] When a woven or knitted fabric is used as the fiber-entangled body, examples of the woven fabric include plain weave, twill weave, satin weave, and various woven fabrics based on these weave structures. Also, examples of the knitted fabric include warp knitting, weft knitting represented by tricot knitting, lace knitting, and various knitted fabrics based on these knit structures.

[0022] When a nonwoven fabric is used as the fiber-entangled body, all nonwoven fabrics expressed in various categories can be applied, such as general short fiber nonwoven fabrics, long fiber nonwoven fabrics, needle-punched nonwoven fabrics, paper-made nonwoven fabrics, spunbonded nonwoven fabrics, melt-blown nonwoven fabrics, electrospun nonwoven fabrics, etc. Here, nonwoven fabrics are preferred in terms of quality due to a rich feel and fine nap.

[0023] These fiber-entangled bodies filled with a polymeric elastomer are more preferably used in terms of the durability of the artificial leather and the abrasion resistance of the surface of the artificial leather.

[0024] Furthermore, in the artificial leather of the present invention, it is a preferred embodiment that the artificial leather contains a woven or knitted fabric within its structure, from the viewpoint of excellent mechanical strength.

[0025] When the entangled fiber structure includes a woven or knitted fabric, the yarns constituting the woven or knitted fabric are preferably synthetic fibers made of polyester, polyamide, polyethylene, polypropylene, or copolymers thereof. Among these, synthetic fibers made of polyester, polyamide, and copolymers thereof can be used alone, in combination, or in a mixture. Furthermore, the yarns constituting the woven or knitted fabric can include filament yarns, spun yarns, and blended yarns of filaments and staple fibers.

[0026] The woven or knitted fabrics contained in the entangled fiber structure may also be those containing bicomponent fibers in which two or more polymers are combined in a side-by-side or eccentric core-sheath configuration (hereinafter, sometimes referred to as side-by-side or other bicomponent fibers). For example, in side-by-side or other bicomponent fibers made of two or more polymers with different intrinsic viscosities (IV), stress concentration on the higher-viscosity side during stretching causes different internal strains between the two components. This internal strain causes the higher-viscosity side to shrink more significantly due to differences in elastic recovery after stretching and differences in thermal shrinkage during the heat treatment process, resulting in strain within the single fiber and the development of a three-dimensional coil-type crimp. This three-dimensional coil-type crimp provides the stretchability required for artificial leather.

[0027] As described above, examples of the woven fabric contained in the entangled fiber structure include plain weave, twill weave, satin weave, and various woven fabrics based on these weave structures. Furthermore, as the knitted fabric, any of warp knitting, weft knitting represented by tricot knitting, lace knitting, and various knitted fabrics based on these knitting structures can be used. Among these, woven fabrics are preferred from the viewpoint of processability, and plain weave fabrics are particularly preferred from the viewpoint of cost. Furthermore, the weave density of the woven fabric can be appropriately set depending on the total fineness of the yarns and the equipment and conditions for entangling the nonwoven fabric and woven / knitted fabric, which will be described later.

[0028] In the artificial leather of the present invention, it is also preferable that the fiber-entangled body is dyed with a dye. By minimizing the color difference with the design surface in this way, when the artificial leather of the present invention is viewed from the design surface, flickering due to the color on the opposite side of the design surface is suppressed, and a sense of uniformity in the overall hue is obtained. The color difference referred to here is CIE1976L * a * b * a in color space * This refers to the difference between the Δa* and Δb* values, and both the Δa* and Δb* values ​​are preferably within ±20, more preferably within ±10. The color difference is measured under CIE standard illuminant D65 conditions and at a viewing angle of 10°. Using a hue of the same type as the design surface will give a more consistent hue. The Δa* and Δb* values ​​referred to here are values ​​determined by the method described below.

[0029] [Polymer elastic material] In the artificial leather of the present invention, as described above, the inclusion of a polymeric elastomer within the fiber-entangled structure improves the shape stability and surface abrasion resistance of the artificial leather. When the polymeric elastomer is contained within the fiber-entangled structure, polyurethane, styrene-butadiene rubber (SBR), nitrile rubber (NBR), acrylic resin, etc. can be used as the polymeric elastomer, and among these, it is preferable to use polyurethane as the main component. By using polyurethane, it is possible to obtain artificial leather with a rich feel, a leather-like appearance, and physical properties that can withstand practical use.

[0030] When polyurethane is used as the polymeric elastomer contained in the fiber-entangled body, either an organic solvent-based polyurethane, which is used in a state of being dissolved in an organic solvent, or a water-dispersed polyurethane, which is used in a state of being dispersed in water, can be used. Furthermore, polyurethane obtained by reacting a polymer diol, an organic diisocyanate, and a chain extender is preferably used.

[0031] The polymeric elastomer inside the fiber-entangled body may contain various additives, for example, pigments such as carbon black; phosphorus-based, halogen-based, and inorganic flame retardants; phenol-based, sulfur-based, and phosphorus-based antioxidants; benzotriazole-based, benzophenone-based, salicylate-based, cyanoacrylate-based, and oxalic acid anilide-based ultraviolet absorbers; hindered amine-based and benzoate-based light stabilizers; hydrolysis-resistant stabilizers such as polycarbodiimides; plasticizers; antistatic agents; surfactants; coagulation adjusters; and dyes.

[0032] The content of the polymer elastomer inside the fiber-entangled body can be adjusted appropriately taking into consideration the type of polymer elastomer used, the manufacturing method of the polymer elastomer, and the feel and physical properties. The content of the polymer elastomer is preferably 5% by mass or more and 80% by mass or less, more preferably 10% by mass or more and 60% by mass or less, and even more preferably 15% by mass or more and 45% by mass or less, based on the mass of the fiber-entangled body. By setting the content ratio of the polymer elastomer to 5% by mass or more, it is possible to obtain sheet strength and maintain the entangled state by binding the fibers, while by setting the content ratio to 80% by mass or less, it is possible to prevent the feel from becoming hard.

[0033] [Artificial leather] The artificial leather of the present invention contains the above-mentioned fiber-entangled body and a polymeric elastomer as constituent elements.

[0034] The thickness of the artificial leather of the present invention is 0.4 mm or more and 1.2 mm or less. By making the thickness of the artificial leather 0.4 mm or more, preferably 0.5 mm or more, and more preferably 0.6 mm or more, the strength and elongation required for artificial leather can be obtained. On the other hand, by making the thickness 1.2 mm or less, preferably 1.0 mm or less, and more preferably 0.8 mm or less, the artificial leather can easily achieve the optical transparency that is the objective of the present invention.

[0035] The thickness of artificial leather refers to the value measured and calculated using the following procedure in accordance with "8.4 Thickness Method A" of JIS L1096:2010 "Testing methods for woven and knitted fabrics." (1) The measurement sample is pre-dried in an environment with a relative humidity of 10 to 25% and a temperature of less than 50°C, and then left in a room under standard conditions until it reaches a constant weight and is adjusted. (2) Using a thickness measuring device, measure the thickness (mm) of five different points of the adjusted material for 10 seconds under a pressure of 0.7 kPa, calculate the average value, and round it to two decimal places.

[0036] Furthermore, the weight of the artificial leather of the present invention is 80 g / m 2 More than 450g / m 2The weight of the artificial leather is 80g / m 2 More than 100 g / m 2 More preferably, 120 g / m 2 By setting the weight to 450g / m or more, the artificial leather will have durability. 2 Preferably, 400 g / m or less 2 or less, more preferably 350 g / m 2 By doing so, the artificial leather can be more easily provided with the light transmittance that is the object of the present invention.

[0037] The basis weight of artificial leather refers to the value measured and calculated using the following procedure in accordance with "8.3.2 Mass per unit area under standard conditions, Method A" of JIS L1096:2010 "Testing methods for woven and knitted fabrics." (1) The measurement sample is pre-dried under a relative humidity of 10-25% and a temperature of less than 50°C, and then left in a room under standard conditions. Once it has reached a constant weight, two test pieces of approximately 200 mm x 200 mm are taken, and the mass (g) of each is measured under standard conditions and calculated using the following formula: 2 Mass per unit (g / m 2 ) and calculate the average, then round to one decimal place. Sm=W / A where: Sm: Mass per unit area under standard conditions (g / m 2 ) W: Mass of the test piece under standard conditions (g) A: Area of ​​the test piece (m 2 ) is.

[0038] The artificial leather of the present invention has one surface that is a design surface colored with a dye and / or a pigment, and satisfies the following formulas (1) to (3): L * 1≦55 (1) L * 0>50 (2) ΔL * <-5 (3) where L * 1 is the design surface CIE1976L* a * b * Lightness index in color space (L * value), L * 0 is the CIE1976L on the surface opposite the design surface * a * b * Lightness index in color space (L * value), ΔL * is the design surface L * value and L on the surface opposite to the design surface * The difference between the values ​​(CIELAB1976ab lightness difference, L * 1-L * 0). The brightness index is a value measured under CIE standard light source D65 conditions and at a viewing angle of 10°.

[0039] That is, as shown in the above formula (1), L * 1≦55 means that the design surface is a medium to dark color. * Even if the color is dark, such as 1≦30, it is possible to obtain artificial leather with excellent light transmittance.

[0040] Furthermore, as shown in the above equation (2), L * 0>50 means that the color is lighter than the design surface when measured from the surface opposite the design surface, and ΔL * <-5, that is, ΔL * By ensuring that the color difference is at least a certain level, it is possible to improve the light transmittance even for a dark-colored design surface.

[0041] Preferably L * 0>60, more preferably L * The upper limit is L 0 > 70 from the viewpoint of design, that is, to make it less susceptible to the influence of the hue on the opposite side of the design surface. * It is preferable that 0≦90.

[0042] Also, ΔL * <-5 is preferably ΔL * <-10, and more preferably ΔL* <-15.

[0043] [Manufacturing method for artificial leather] Here, the method for producing the artificial leather of the present invention will be described. The artificial leather of the present invention can be obtained, for example, using ultrafine fiber-developing fibers made of two or more polymeric substances with different solubilities in solvents.

[0044] Examples of ultrafine fiber-forming fibers that can be used include islands-in-sea composite fibers in which two thermoplastic resin components having different solubilities in solvents are used as a sea component and an island component, and the sea component is dissolved and removed with a solvent to turn the island component into ultrafine fibers, and peel-type composite fibers in which two thermoplastic resin components are alternately arranged radially or in multiple layers on the fiber surface and then peeled and split by solvent treatment to split into ultrafine fibers. Among these, islands-in-sea composite fibers are preferably used from the viewpoint of the flexibility and texture of the substrate, because the removal of the sea component can provide appropriate voids between the island component fibers, i.e., between the ultrafine fibers within the fiber bundle.

[0045] Islands-in-sea type composite fibers can be produced using an islands-in-sea type composite spinneret by a polymer mutual alignment method in which two components, a sea part and an island part, are mutually aligned and spun, or a mixed spinning method in which two components, a sea part and an island part, are mixed and spun, but the polymer alignment method for producing islands-in-sea type composite fibers is more preferably used because it can produce ultrafine fibers with a uniform fineness.

[0046] In a preferred embodiment, the ultrafine fibers are in the form of a nonwoven fabric (ultrafine fiber web) in the fiber-entangled body. By forming the ultrafine fibers into a nonwoven fabric, a uniform and elegant appearance and texture can be obtained. The form of the nonwoven fabric (ultrafine fiber web) may be either a short fiber nonwoven fabric or a long fiber nonwoven fabric.

[0047] The fiber length of the ultrafine fibers used to produce short-fiber nonwoven fabrics can be appropriately selected depending on the type of nonwoven fabric. For conventional short-fiber nonwoven fabrics, the fiber length is preferably 25 mm to 90 mm. By setting the fiber length of the ultrafine fibers to 90 mm or less, good quality and texture can be achieved, and by setting the fiber length to 25 mm or more, artificial leather with good abrasion resistance can be produced. For nonwoven fabrics produced by a papermaking method, the fiber length is preferably 0.1 mm to 10 mm. Setting the fiber length to 10 mm or less makes it possible to obtain a stable suspension and suppress unevenness in the basis weight and thickness of the nonwoven fabric. Setting the fiber length to 0.1 mm or more makes it possible to suppress shedding of fuzz from the nonwoven fabric. Furthermore, the ultrafine fiber-forming fiber of the present invention is preferably subjected to crimping processing to promote entanglement of the fibers. Known methods can be used for crimping and cutting.

[0048] Next, the obtained raw cotton is made into a fiber web using a cross wrapper or the like, and entangled to obtain a nonwoven fabric. Methods that can be used to entangle the fiber web to obtain a nonwoven fabric include needle punching and water jet punching. The basis weight of the fiber web can be appropriately set taking into consideration the design of the final product, dimensional changes in subsequent processes, the characteristics of the processing machine, and the like.

[0049] Another preferred embodiment is to entangle a fiber-entangled body made of a woven or knitted fabric with an ultrafine fiber-generating fiber to obtain a laminated sheet of a nonwoven fabric made of the ultrafine fiber-generating fiber and the woven or knitted fabric. Methods such as needle punching and water jet punching can be used to entangle the two. Among these, needle punching is preferred from the viewpoint of bonding properties and product quality. From the viewpoint of densification, the laminated sheet of the fiber-entangled body made of the ultrafine fiber-generating fiber and the woven or knitted fabric obtained in this manner is preferably shrunk by dry heat, wet heat, or both before adding the polymeric elastomer to further increase its density. This shrinkage treatment can be performed either before or after the ultrafine fiber formation. However, performing the shrinkage treatment before the formation of the ultrafine fibers is preferred because it allows the properties of the sea component polymer of the ultrafine fiber-generating fiber to be utilized in the shrinkage. Furthermore, the area shrinkage ratio of the laminated sheet in this shrinkage step is preferably in the range of 15% to 35%. By setting the area shrinkage ratio to 15% or more, the effect of improving the quality due to shrinkage can be preferably obtained. Furthermore, by setting the areal shrinkage rate to 35% or less, it is possible to leave room for shrinkage in the woven or knitted fabric integrated with the nonwoven fabric, and therefore it is possible to efficiently shrink it after the polymeric elastomer is subsequently added. A more preferable range of the areal shrinkage rate is 1% or more and 30% or less, and even more preferably 15% or more and 25% or less. The areal shrinkage rate is measured by calculating the shrinkage rate in the length direction and the shrinkage rate in the width direction from the length and width before and after processing in the shrinking step, and then calculating it using the following formula: Length shrinkage rate = length after shrinking / length before shrinking Width shrinkage rate = Width after shrinkage / Width before shrinkage Area shrinkage rate (%) = (1 - (1 - length shrinkage rate) x (1 - width shrinkage rate)) x 100.

[0050] As the shrinkage method, known methods such as hot water shrinkage, steam shrinkage, dry heat shrinkage, etc. can be used. The time and temperature of the shrinkage treatment may be adjusted so as to achieve the above-mentioned areal shrinkage rate depending on the shrinkage method to be used, the type of fibers constituting the fiber-entangled body, etc.

[0051] The method for producing an artificial leather of the present invention includes a step of treating a laminated sheet of the fiber-entangled body made of the ultrafine fiber-forming fiber and a woven or knitted fabric to produce ultrafine fibers having an average single fiber diameter of 0.1 μm to 8 μm. Examples of the method for producing ultrafine fibers include a method of dissolving one of the resins constituting the ultrafine fiber-forming fiber with a solvent. In particular, for an ultrafine fiber-forming sea-island composite fiber in which the sea part is made of an easily soluble polymer and the island parts are made of a sparingly soluble polymer, a method of dissolving the sea part is preferred.

[0052] As a solvent for dissolving the sea component, when the sea component is a polyolefin such as polyethylene or polystyrene, an organic solvent such as toluene or trichloroethylene can be used. When the sea component is polylactic acid or a copolymer polyester, an alkaline aqueous solution such as sodium hydroxide can be used. This ultrafine fiber generating process (sea-removal process) can be carried out by immersing a fiber-entanglement body made of ultrafine fiber generating fibers in a solvent and squeezing the solvent.

[0053] Next, a process for imparting a polymeric elastomer to the obtained fiber-entangled body containing ultrafine fibers is carried out. It is possible to adopt a method in which either the process for developing ultrafine fibers from the ultrafine fiber-developing fibers or the process for imparting a polymeric elastomer is carried out first. When the process for developing ultrafine fibers is carried out first, the polymeric elastomer holds the ultrafine fibers, preventing the ultrafine fibers from falling off and making the product durable for longer use. Furthermore, when the polymeric elastomer is imparted first, the ultrafine fibers are not held by the polymeric elastomer, resulting in a structure in which the ultrafine fibers are not held, resulting in an artificial leather with a good texture. The order in which the processes are carried out first can be appropriately selected depending on the type of polyurethane used, etc.

[0054] Furthermore, when the polymer elastomer is applied after the ultrafine fiber development treatment, it is preferable to provide a step of applying a water-soluble resin between the two steps. By providing this step of applying a water-soluble resin, the surfaces of the fibers constituting the ultrafine fiber bundles or woven or knitted fabrics are protected by the water-soluble resin, and the surfaces of the fibers constituting the ultrafine fiber bundles or woven or knitted fabrics are directly bonded to the polymer elastomer in discontinuous rather than continuous areas, thereby appropriately reducing the bonding area. As a result, an artificial leather can be obtained that has a good handle due to the polymer elastomer, but also a soft texture, and when a woven or knitted fabric made of composite fibers such as a side-by-side type is used, has high stretchability.

[0055] Examples of such water-soluble resins that can be used include polyvinyl alcohol, polyethylene glycol, sugars, and starch. Among these, polyvinyl alcohol with a saponification degree of 80% or more is preferably used.

[0056] Examples of a method for imparting the water-soluble resin to the fiber-entangled body include a method of impregnating the fiber-entangled body with an aqueous solution of the water-soluble resin and drying it. From the viewpoint of suppressing shrinkage of woven or knitted fabrics, it is preferable that the drying conditions, such as the drying temperature and drying time, be such that the temperature of the fiber-entangled body to which the water-soluble resin has been imparted is kept at 110°C or less.

[0057] The amount of water-soluble resin applied is preferably 1 to 30% by mass relative to the mass of the fiber-entangled structure immediately before application. By applying an amount of 1% by mass or more, good texture and, in the case of artificial leather using a woven or knitted fabric made of composite fibers such as a side-by-side type, good stretchability can be obtained. Furthermore, by applying an amount of 30% by mass or less, artificial leather can be obtained that is easy to process and has good physical properties such as abrasion resistance. Furthermore, since the amount of polymeric elastomer that can be applied to the fiber-entangled structure in the subsequent process increases, it becomes possible to increase the density of the artificial leather and make the texture more precise.

[0058] In the method for producing the artificial leather of the present invention, a step of cutting the fiber-entangled body (precursor sheet of the artificial leather) to which the polymeric elastomer has been added in half in the planar direction can be carried out. By including the half-cutting step, the productivity of the artificial leather can be improved. For example, when a method of sandwiching a nonwoven fabric layer made of ultrafine fiber-generating fibers between woven and knitted fabric layers is used as a lamination method for woven and knitted fabrics, cutting the precursor sheet in half and making the inner surface a napped surface is a preferred embodiment for achieving a dense quality.

[0059] The artificial leather of the present invention preferably has nap on at least one side. The nap-raising treatment can be carried out by buffing the surface of the precursor sheet of the artificial leather with sandpaper, a roll sander, or the like. In particular, the use of sandpaper can form uniform and dense nap. Furthermore, in order to form uniform nap on the surface of the precursor sheet of the artificial leather, it is preferable to reduce the grinding load.

[0060] The obtained precursor sheet of artificial leather can be dyed. * a * b * Lightness index in color space (L * The dyeing method is carried out so that the value of the dyeing temperature is within the range of the present invention. As for the dyeing method, there is no particular problem in that a precursor sheet of the artificial leather is prepared in advance and dyed with a general dye that is suitable for the fiber material. When dyeing, a dye that is suitable for the fiber base material of the artificial leather can be used. If the fiber base material is a polyester-based fiber, a disperse dye can be used, and if it is a polyamide-based fiber, an acid dye or a metal-containing dye, or other dye that is usually used for dyeing polyamide, can be used.

[0061] Dyeing is preferably carried out using a disperse dye, cationic dye or other reactive dye, using a high-temperature, high-pressure dyeing machine in order to make the texture of the dyed artificial leather substrate soft.

[0062] The artificial leather of the present invention has a design surface colored with a dye and / or a pigment.* Value and design L * value and L on the surface opposite to the design surface * The difference between the values ​​is ΔL * In order to obtain a colored layer colored with dyes and / or pigments on the design surface, printing techniques such as dye printing and pigment printing can be used.

[0063] For dye printing, a dye suited to the fiber substrate of the artificial leather can be used, and if the fiber substrate is polyester-based fiber, disperse dyes, acid dyes, metal-containing dyes, and other dyes normally used for dyeing polyamide can be used if the fiber substrate is polyamide-based fiber. There are no limitations on the printing method, and any method such as transfer printing, screen printing, or inkjet printing can be used.

[0064] For pigment printing, a mixture of pigment and binder resin can be used, and the binder resin can be urethane resin, acrylic resin, silicone resin, etc., and there is no particular limitation. As with dye printing, there is no limitation on the printing method, and any method such as transfer printing, screen printing, inkjet printing, etc. can be used.

[0065] Alternatively, there is no particular problem with a method in which an artificial leather (artificial leather substrate) is prepared in advance before the colored layer is formed, and then colored with a dye, pigment, or the like.

[0066] Furthermore, if necessary, finishing treatments such as softeners such as silicone, antistatic agents, water repellents, flame retardants, and light fasteners can be applied, and the finishing treatments can be carried out after dyeing or in the same bath as dyeing. For the flame retardant treatment, known halogen-based flame retardants such as bromine and chlorine, or non-halogen-based flame retardants such as phosphorus can be used, and the flame retardant treatment can be applied by immersion after dyeing or by back coating such as knife coating or rotary screen method.

[0067] These finishing treatments may be carried out either before or after the formation of the colored layer, but in order to form a uniform colored layer, it is preferable to carry out the finishing treatment after the formation of the colored layer. Furthermore, these finishing agents can be applied simultaneously with the formation of the colored layer, but as described above, in order to form a uniform colored layer, it is preferable to carry out the finishing treatment after the formation of the colored layer.

[0068] [Light-transmitting device] The artificial leather of the present invention is light-transmitting and therefore suitable for use in a light-transmitting device. The light-transmitting device includes at least one light source and the above-described artificial leather as at least constituent elements, and is configured by placing the above-described artificial leather on the light source. Because the artificial leather of the present invention is light-transmitting, light from the light source can be transmitted through the artificial leather of the present invention and be visible.

[0069] The light source constituting the light-transmitting device of the present invention is not particularly limited, but since it must be built into the device, small light sources such as electroluminescent light-emitting diodes (LEDs) and electroluminescent devices (ELs) are preferably used. The wavelength that can be used is also not particularly limited, and any visible light between 380 nm and 780 nm is acceptable. The illuminance of the light source is also not particularly limited, but is preferably 2000 lx or more from the viewpoint of light transmittance.

[0070] When used in the above-mentioned light-transmitting device, the artificial leather satisfies the above formulas (1) to (3) at least in the parts that require light transmission, but the color tone of other parts that do not require light transmission can be configured with a similar design surface or can be configured with a free design. [Example]

[0071] Next, the artificial leather of the present invention will be described in more detail using examples, but the present invention is not limited to these examples. Next, the evaluation methods and measurement conditions used in the examples will be described. However, in measuring each physical property, unless otherwise specified, the measurement was carried out based on the above-mentioned method.

[0072] [Measurement method] (1) Average single fiber diameter of ultrafine fibers The ultrafine fibers were observed using a scanning electron microscope (SEM) model VE-7800 manufactured by Keyence Corporation, and the average single fiber diameter was calculated.

[0073] (2) Thickness As mentioned above, the calculation was carried out according to JIS L1096:2010 8.4 Method A.

[0074] (3) Metsuke As mentioned above, calculation was performed according to JIS L1096:2010 8.3.2 Method A.

[0075] (4) CIE1976L * a * b * Lightness index in color space Using a spectrophotometer, JIS Z8781-4:2013 "Colorimetry - Part 4: CIE1976L * a * b * L defined in 3.3 of the "Color Space" * , a * , b * The ΔL value was calculated by measuring the design surface and the surface opposite the design surface (the back surface of the design surface) five times under the conditions of CIE standard illuminant D65 and a viewing angle of 10°, and then using the average value. * , Δa * , Δb * The measurements were carried out using the "CR-310" manufactured by Konica Minolta, Inc. ΔL * =L * 1-L * 0 Δa * =a * 1-a * 0 Δb * =b * 1-b * 0 where: L * 1: Design surface CIE1976L * a * b* Lightness index in color space (L * value) L * 0: CIE1976L on the surface opposite the design surface * a * b * Lightness index in color space (L * value), ΔL * is the design surface L * value and L on the surface opposite to the design surface * The difference between the values ​​(CIELAB1976ab lightness difference, L * 1-L * 0)a * 1: Design surface CIE1976L * a * b * The lightness index in the color space (a * value) a * 0: CIE1976L on the surface opposite the design surface * a * b * The lightness index in the color space (a * value), Δa * is the design surface a * value and a on the surface opposite to the design surface * Difference from the value (CIELAB1976a * difference, a * 1-a * 0) b * 1: Design surface CIE1976L * a * b * The brightness index (b * value) b * 0: CIE1976L on the surface opposite the design surface * a * b * The brightness index (b * value), Δb * is the design surface b * value and the b value of the surface opposite to the design surface * Difference from the value (CIELAB1976b * difference, b * 1-b* 0) is.

[0076] (5) Light transparency To confirm the light transmittance, the spectral transmittance was measured using a spectrophotometer "V-770" (ISN-923 integrating sphere) manufactured by JASCO Corporation, and the "Spectralon Reflectance Standard" manufactured by Labsphere Inc. as a standard white plate. The spectral transmittance (%) was measured in the range of 400 to 800 nm with a bandwidth of 5 nm.

[0077] Measurements were performed with incidence from the opposite side of the design surface (back side of the design surface). A value of 0.2% or more was considered to have light transmittance and was marked with ○ (B) in Table 1, and an even better light transmittance of 3.0% or more was marked with ◎ (A) in Table 1. A value of less than 0.2% was considered to have no light transmittance and was marked with × (C).

[0078] (6) Texture The texture was evaluated as follows in Table 1: ◯ (A) indicates that the material had the smoothness characteristic of artificial leather, and × (B) indicates that the material had a rough feel.

[0079] (7) Color flicker on the opposite side of the design The color of the opposite side of the design surface was visually judged to be flickering when viewed from the design surface. Table 1 lists the results as follows: ○ (A) for no flickering, △ (B) for slight flickering but usable, and × (C) for flickering.

[0080] (8) Overall Judgment Based on the evaluation results of light transmittance, texture, and color flicker on the opposite side of the design surface, an overall judgment was made as follows: ◎ (A) indicates that the material can be preferably used in a light-transmitting device; ○ (B) indicates that it can be used; and × (C) indicates that it cannot be used in a light-transmitting device.

[0081] [Example 1] <Raw cotton> Polyethylene terephthalate was used as the island component and polystyrene was used as the sea component. The fibers were melt spun at an islands / sea mass ratio of 80 / 20 using an islands-in-sea composite spinneret with 16 islands, and then stretched and crimped, and then cut to a length of 51 mm to obtain raw fibers for islands-in-sea composite fibers.

[0082] <Laminated web (nonwoven fabric) and laminated sheet with woven and knitted fabric> The raw cotton of the above-mentioned islands-in-the-sea composite fiber is used to form a laminated web (nonwoven fabric) through carding and cross-wrapping processes, and the density is 100 threads / cm to prevent wrinkles in the fabric due to sudden width changes after lamination. 2 Separately, a plain weave fabric was woven using a weft yarn made of a single component yarn having an intrinsic viscosity (IV) of 0.65 and a multifilament yarn (84 dtex, 72 filaments) with a twist of 2500 T / m, and a warp yarn made of a single component yarn having an intrinsic viscosity (IV) of 0.65 and a multifilament yarn (84 dtex, 72 filaments) with a twist of 2500 T / m, with a warp yarn having a weave density of 97 threads / 2.54 cm and 76 threads / 2.54 cm. The obtained plain weave fabric was laminated on top and bottom of the laminated web (nonwoven fabric).

[0083] Then, 2500 lines / cm 2 The fabric is needle punched with a punch count (density) of 740g / m 2 Thus, a laminated sheet was obtained having a thickness of 3.4 mm, which was made of a nonwoven fabric made of ultrafine fiber-generating fibers and a heat-shrinkable woven fabric.

[0084] <Fiber entanglement> The laminated sheet obtained in the above process was treated with hot water at a temperature of 96°C to shrink it, then impregnated with an aqueous solution of polyvinyl alcohol (hereinafter sometimes abbreviated as PVA) and dried with hot air at a temperature of 110°C for 10 minutes to obtain a sheet base with a PVA mass of 7.6% by mass relative to the mass of the laminated sheet. The sheet base obtained in this way was immersed in trichloroethylene to dissolve and remove the sea component polystyrene, obtaining a sea-removed sheet consisting of ultrafine fibers with an average single fiber fineness of 4.4 μm entangled with plain weave fabric. The sea-removed sheet thus obtained, consisting of a nonwoven fabric made of ultrafine fibers and plain weave fabric, was immersed in a dimethylformamide (hereinafter sometimes abbreviated as DMF) solution of polyurethane adjusted to a solids concentration of 12%, and then the polyurethane was coagulated in an aqueous solution with a DMF concentration of 30%. Thereafter, the PVA and DMF were removed with hot water, and the sheet was dried with hot air at 110°C for 10 minutes to obtain a precursor sheet of a fiber-entangled body in which the polyurethane mass was 27% by mass relative to the total mass of the ultrafine fibers constituting the island component and the plain weave fabric.

[0085] The precursor sheet for the fiber-entangled body thus obtained was cut in half in the thickness direction, and the nonwoven fabric layer inside the precursor sheet was cut in half perpendicular to the thickness direction. The surfaces of the cut sheets were ground with endless sandpaper of sandpaper count 320 to form a napped surface on the surface layer, thereby obtaining a fiber-entangled body with a thickness of 0.90 mm.

[0086] <How to color the design surface and the opposite side of the design surface (back side of the design surface)> The fiber entanglement thus obtained is dyed with a disperse dye using a liquid jet dyeing machine. * The fabric was dyed a light gray color with a value of 50 or more, then reduced and washed, dried in a dryer, and then pigment printed on the design surface using a screen printer. Black pigment and urethane resin were used as binders for the pigment printing. * Value is 20.08, L on the back of the design surface * The fiber entanglement body had a L value of 70.86. * Difference from the value ΔL *The spectral transmittance was measured to be 1.5%, confirming that the film has optical transparency. * value, Δb * Both values ​​were within ±20, and the coloring was similar, so there was no color flicker on the opposite side of the design surface. The texture was also good, and it was confirmed that it can be used favorably in light-transmitting devices. The results are shown in Table 1.

[0087] [Example 2] <Raw cotton - fiber entanglement> The same materials as those used in Example 1 were used.

[0088] <How to color the design surface and the opposite side of the design surface (back side of the design surface)> The obtained fiber entanglement body was treated so that the back side of the design surface was L * The fabric was dyed in the same manner as in Example 1, except that the L value (gray color) was obtained. After that, reduction cleaning was performed, and the fabric was dried in a dryer, and then pigment printing was performed on the design surface using a screen printing machine. In the pigment printing, gray pigment and urethane resin were used as binders. In this way, the L value (gray color) of the design surface was obtained. * Value is 50.34, L on the back of the design surface * The fiber entanglement body had a L value of 56.53. * Difference from the value ΔL * The spectral transmittance was measured to be 2.2%, confirming that the film has optical transparency. * value, Δb * Both values ​​were within ±20, and the coloring was similar, so there was no color flicker on the opposite side of the design surface. The texture was also good, and it was confirmed that it can be used favorably in light-transmitting devices. The results are shown in Table 1.

[0089] [Example 3] <Raw cotton - fiber entanglement> The same materials as those used in Example 1 were used.

[0090] <How to color the design surface and the opposite side of the design surface (back side of the design surface)> The obtained fiber entanglement body was treated so that the back side of the design surface was L* The fabric was dyed in the same manner as in Example 1, except that the L value (light gray) of the design surface was changed to 0.01.00. After that, reduction cleaning was performed, and the fabric was dried in a dryer. Then, a dye print was performed on the design surface using a dark gray disperse dye in a screen printing machine. * Value is 33.98, L on the back of the design surface * The fiber entanglement body had a L value of 72.20. * Difference from the value ΔL * The spectral transmittance was measured to be 2.7%, confirming that the film has optical transparency. * value, Δb * Both values ​​were within ±20, and the coloring was similar, so there was no color flicker on the opposite side of the design surface. The texture was also good, and it was confirmed that it can be used favorably in light-transmitting devices. The results are shown in Table 1.

[0091] [Example 4] <Raw cotton - fiber entanglement> The same materials as those used in Example 1 were used.

[0092] <How to color the design surface and the opposite side of the design surface (back side of the design surface)> The obtained fiber entanglement body was treated so that the back side of the design surface was L * The fabric was dyed in the same manner as in Example 1, except that the L value (light gray) of the design surface was changed to 0.01.0 ... * Value is 52.44, L on the back of the design surface * The fiber entanglement body had a L value of 72.20. * Difference from the value ΔL * The spectral transmittance was measured to be 2.9%, confirming that the film has optical transparency. * value, Δb * Both values ​​were within ±20, and the coloring was similar, so there was no color flicker on the opposite side of the design surface. The texture was also good, and it was confirmed that it can be used favorably in light-transmitting devices. The results are shown in Table 1.

[0093] [Example 5] <Raw cotton - fiber entanglement> The same materials as those used in Example 1 were used.

[0094] <How to color the design surface and the opposite side of the design surface (back side of the design surface)> The resulting fiber entanglement was subjected to blue pigment printing only on the design side. * Value is 36.88, L on the back of the design surface * The fiber entanglement body had a L value of 88.14. * Difference from the value ΔL * The spectral transmittance was measured to be 5.1%, confirming that the film has optical transparency. * The values ​​were within ±20, but Δb * The value was 39.97, which was more than ±20, so the white color on the opposite side of the design surface was slightly visible from the design surface, and there was color flicker. The texture was good, and it was confirmed that it can be used in light-transmitting devices. The results are shown in Table 1.

[0095] [Example 6] <Raw cotton - fiber entanglement> The same materials as those used in Example 1 were used.

[0096] <How to color the design surface and the opposite side of the design surface (back side of the design surface)> The resulting fiber-entangled body was subjected to gray pigment printing on the design surface in the same manner as in Example 2. * Value is 50.34, L on the back of the design surface * The fiber entanglement body had a L value of 88.14. * Difference from the value ΔL * The spectral transmittance was measured to be 5.8%, confirming that the film has optical transparency. * value, Δb *Both values ​​were within ±20 of the same color, and there was no color flicker on the opposite side of the design surface. The texture was also good, and it was confirmed that it can be used favorably in light-transmitting devices. The results are shown in Table 1.

[0097] [Comparative Example 1] <Raw cotton - fiber entanglement> The same materials as those used in Example 1 were used.

[0098] <How to color the design surface and the opposite side of the design surface (back side of the design surface)> The obtained fiber entanglement body is dyed with a disperse dye using a liquid jet dyeing machine. * The fabric was dyed a dark gray with a value of 50 or less, then reduced and washed, and dried in a dryer. * The fiber entanglement body had a L value of 27.33. * Difference from the value ΔL * was 0.00, and the spectral transmittance was measured to be 0.0%, meaning that there was no light transmittance. * value, Δb * Both values ​​were within ±20, and there was no color flicker on the opposite side of the design surface, but the lack of light transparency confirmed that the film could not be used in light-transmitting devices. The results are shown in Table 1.

[0099] Comparative Example 2 <Raw cotton - fiber entanglement> The same materials as those used in Example 1 were used.

[0100] <How to color the design surface and the opposite side of the design surface (back side of the design surface)> The fiber entanglement thus obtained is dyed with a disperse dye using a liquid jet dyeing machine. * The fabric was dyed gray so that the L value was 50 or less, then reduction cleaning was performed, and after drying in a dryer, black pigment printing was performed on the design surface using a screen printing machine. * Value is 22.50, L on the back of the design surface * The fiber entanglement body had a L value of 44.02. * Difference from the value ΔL *The spectral transmittance was measured to be 0.0%, which means that there was no light transmittance. * value, Δb * Both values ​​were within ±20, and there was no color flicker on the opposite side of the design surface, but the lack of light transparency confirmed that the film could not be used in light-transmitting devices. The results are shown in Table 1.

[0101] Comparative Example 3 <Raw cotton - fiber entanglement> The same materials as those used in Example 1 were used.

[0102] <How to color the design surface and the opposite side of the design surface (back side of the design surface)> The fiber entanglement thus obtained was dyed in dark gray using a jet dyeing machine with the same dyeing recipe as in Comparative Example 1, then reduced and washed, dried in a dryer, and then a gray pigment print was applied to the design surface using a screen printing machine. * Value is 50.34, L on the back of the design surface * The fiber entanglement body had a L value of 27.33. * Difference from the value ΔL * The spectral transmittance was 23.01, and the result of measuring the spectral transmittance was 0.0%, which means that there was no light transmittance. * value, Δb * Both values ​​were within ±20, and there was no color flicker on the opposite side of the design surface, but the lack of light transparency confirmed that the film could not be used in light-transmitting devices. The results are shown in Table 1.

[0103] [Table 1]

[0104] As shown in Table 1, the artificial leathers of Examples 1 to 6 had a spectral transmittance of 0.2% or more, indicating light transmittance. On the other hand, the artificial leathers of Comparative Examples 1 to 3 all had a spectral transmittance of 0.0%, indicating no light transmittance. In particular, it was noteworthy that Example 1 had good light transmittance despite having a dark black design surface that was equal to or greater than that of Comparative Example 1.

Claims

1. A light-transmitting device comprising at least one light source and artificial leather as at least constituent elements, the artificial leather being placed on the light source, The artificial leather includes, as components, a fiber-entangled body made of ultrafine fibers having an average single fiber diameter of 0.1 μm or more and 8 μm or less, and a polymeric elastomer, and the thickness of the artificial leather is 0.4 mm or more and 1.2 mm or less, and the basis weight of the artificial leather is 80 g / m ２ 450g / m or more ２ The light-transmitting device is as follows: one surface of the artificial leather is a design surface colored with a dye and / or a pigment, and satisfies the following formulas (1) to (3). L ＊ １ ≦55 ・・・(1) L ＊ ０ >50 ・・・(2) ΔL ＊ <-5 ・・・(3) Here, L ＊ １ is CIE1976L for design surface ＊ a ＊ b ＊ Lightness index in color space (L ＊ value), L ＊ ０ is CIE1976L on the surface opposite the design surface. ＊ a ＊ b ＊ Lightness index in color space (L ＊ value), ΔL ＊ is the design surface L ＊ value and L on the surface opposite to the design surface ＊ The difference between the CIELAB 1976ab lightness values ​​(L ＊ １ -L ＊ ０ The brightness index is a value measured under the conditions of CIE standard light source D65 and a viewing angle of 10°.

2. The light transmission device according to claim 1 , wherein the fiber entanglement is dyed with a dye.

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