Leather-like sheet, and a backpack using it as the backing material.

Abstract

This leather-like sheet comprises a fibrous substrate and a colored resin layer laminated on the fibrous substrate, wherein: the colored resin layer includes a middle layer and a surface skin layer laminated on the middle layer; the surface skin layer contains a polyurethane and a black pigment in the amount of 3 g / m2 or more; the middle layer contains a polyurethane and a black pigment; and in the L*a*b* color system, lightness L* ≦30.

Description

[Technical Field]

[0001] This invention relates to a leather-like sheet with excellent detection properties by LIDAR (Laser Imaging Detection and Ranging), and a backpack using this sheet as a backing material. [Background technology]

[0002] LiDAR is a well-known technology that uses laser light, such as near-infrared light, to measure the time it takes for the light to hit an object and bounce back, thereby determining the distance and direction to the object. While this technology is also known as LiDAR (Light Detection and Ranging), it will be referred to as LiDAR below.

[0003] In recent years, with the increasing demand for autonomous driving technology in automobiles, research and development to improve the detection sensitivity of LIDAR sensors used as safety devices has accelerated. The purpose of adopting LIDAR sensors in autonomous driving technology for automobiles is to reduce traffic accidents by detecting vehicles, people, objects, etc., around the vehicle being driven in advance and reflecting this information in the driving situation.

[0004] LIDAR sensors, which are increasingly being adopted in autonomous driving technology for automobiles, often use pulsed laser light, which is near-infrared light in the 905-1600 nm range. Because such pulsed laser light has high reflectivity, it offers excellent accuracy in distance measurement.

[0005] Incidentally, leather-like sheets, such as artificial leather with a silver-plated resin layer, are used as materials for bags, clothing, shoes, etc. The resin layer of these leather-like sheets is usually colored. Among these, leather-like sheets with a black-colored silver-plated resin layer are the most widely used.

[0006] For example, Patent Document 1 below comprises a base layer, a resin layer provided on the base layer, and an outermost layer provided on the resin layer, wherein the resin layer contains hygroscopic fine particles and infrared reflective pigments, and the outermost layer contains 0.2 g / m² 2 More than 1g / m 2 The following synthetic leather containing hygroscopic fine particles is disclosed. Furthermore, because such synthetic leather contains an infrared reflective pigment in the resin layer, it does not easily become hot in sunlight even if it is black or dark in color, and because it has an outermost layer on top of the resin layer, it also has excellent fade resistance. In addition, the infrared reflective pigment has an average reflectance of 20% or more in the 780-1800 nm (near-infrared region) and an average absorptance of 70% or more in the 400-760 nm (visible light region).

[0007] Furthermore, regarding infrared reflective pigments, Patent Document 2 below describes a method for producing a black near-infrared reflective pigment, comprising mixing at least a calcium compound, a titanium compound, and a manganese compound by a wet grinding method and firing at a temperature higher than 1100°C, wherein the black near-infrared reflective pigment has a perovskite phase as its main phase and a BET specific surface area of ​​1.0 m². 2 / g or more 3.0m 2 A method for producing a black near-infrared reflective pigment with a weight of less than / g is disclosed.

[0008] Furthermore, Patent Document 3 below discloses an artificial leather with a black grain layer, characterized in that the upper layer is a polyurethane-based resin layer with a thickness of 30 to 100 μm containing 2% or more perylene black relative to the weight of the resin, and the lower layer is a polyurethane-based resin layer containing carbon black. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] Japanese Patent Publication No. 2015-168907 [Patent Document 2] Japanese Patent Publication No. 2016-20549 [Patent Document 3] International Publication No. 2018 / 168596

Summary of the Invention

Problems to be Solved by the Invention

[0010] In the LIDAR sensor that has been increasingly adopted in autonomous driving technology, there was a problem that the detection sensitivity for black objects was low. This is because the pulsed laser light in the 905 - 1600 nm range used by the LIDAR sensor for distance measurement is absorbed by carbon black, which is widely used as a black pigment for black objects, resulting in weak reflected light and making it difficult to be detected.

[0011] The inventors noticed that a leather-like sheet having a resin layer with a silver-tone coloration and colored black, which is worn or held by a person, becomes difficult to be detected by the LIDAR sensor and fails to detect the presence of a person hidden behind it. As a result of intensive studies on technologies for improving safety, the inventors arrived at the present invention.

[0012] That is, an object of the present invention is to provide a leather-like sheet with a dark color that is easily detected by the LIDAR sensor.

Means for Solving the Problems

[0013] One aspect of the present invention is a leather-like sheet including a fiber substrate and a colored resin layer laminated on the fiber substrate. The colored resin layer includes an intermediate layer and an epidermis layer laminated on the intermediate layer. The epidermis layer is a layer containing polyurethane and an infrared reflective black pigment of 3 g / m A porous layer with a thickness of 100-600 μm is stacked on top of, and on the porous layer or more. The intermediate layer is a layer containing polyurethane and a black pigment. In the L 2 a * a * b * color system, a leather-like sheet having a surface with a lightness L * value ≦ 30, such as The leather-like sheet has a LiDAR sensor reflectance of 40 or higher at a wavelength of 905 nm and a measurement distance of 10 m, as measured using a HORIZON sensor manufactured by Livox Technology Company Limited. The infrared reflective black pigment is CaO-TiO 2 -MnO 2 This includes at least one selected from the following: a titanium-based black pigment, Tilack D, a titanium-based black pigment manufactured by Akaho Chemical Industries, Ltd., and a composite oxide pigment of chromium oxide and iron oxide. has an infrared reflective black pigment with a high reflectance in the near infrared range of 3 g / m 2By including the above-mentioned surface layer, a leather-like sheet with a black surface layer that is easily detected by a LIDAR sensor emitting pulsed laser light in the 905-1600 nm range is obtained. However, a surface layer colored only with infrared-reflective black pigment has low blackness, making it difficult to obtain a leather-like sheet with high blackness. When carbon black is added to the surface layer to increase blackness, the reflectivity of near-infrared light decreases significantly. In such cases, by adding black pigment to the intermediate layer, a leather-like sheet with high blackness and LIDAR light can be obtained. * A leather-like sheet can be obtained that has a darkly colored surface such that the value is ≤ 30.

[0014] Furthermore, it is preferable that the surface of the leather-like sheet has a reflectance of 10% or more to near-infrared light with a wavelength of 905 nm and a reflectance of 10% or more to near-infrared light with a wavelength of 1550 nm, as this makes it easier to detect by the near-infrared light across the wide wavelength range of the LIDAR sensor.

[0015] Furthermore, it is preferable that the surface of the leather-like sheet has an average solar reflectance of 10% or more in the wavelength range of 250 to 2500 nm, because this results in high reflectance to near-infrared rays and high reflectivity in the visible light region, making it easier to obtain a leather-like sheet with good color development.

[0016] Furthermore, if the infrared-reflective black pigment has a reflectance of 25% or more to near-infrared light at a wavelength of 905 nm, a reflectance of 50% or more to near-infrared light at a wavelength of 1550 nm, and a transmittance of less than 50% to near-infrared light at a wavelength of 905 nm, or if it is a CaO-Tio2-MnO2-based titanium-based black pigment, it is preferable because it is more easily detected by the near-infrared light across a wide wavelength range of the LIDAR sensor.

[0017] Furthermore, the surface layer contains 0-0.5 g / m² of carbon black. 2 It is preferable to include it because it does not significantly reduce the reflectivity of near-infrared rays.

[0018] Furthermore, the surface reflectance of the leather-like sheet was measured using a HORIZON device manufactured by Livox Technology Company Limited, at a wavelength of 905 nm and a measurement distance of 10 m. is under 40 Being above Therefore, For example, in dark-colored leather-like sheets used in bags and clothing, they are more easily detected by LIDAR sensors. ru. [Effects of the Invention]

[0019] According to the present invention, it is possible to provide a dark-colored leather-like sheet that is easily detected by a LIDAR sensor. [Brief explanation of the drawing]

[0020] [Figure 1] Figure 1 is a schematic cross-sectional view illustrating the layer structure of the full-grain artificial leather of the embodiment. [Figure 2] Figure 2 illustrates the method for measuring the LIDAR sensor reflectance on the surface of the leather-like sheet used in the example. [Figure 3] Figure 3 shows the results obtained when the surface of the leather-like sheet obtained in the example was measured with a LIDAR sensor. [Modes for carrying out the invention]

[0021] The following describes in detail one embodiment of the leather-like sheet according to the present invention. The leather-like sheet of this embodiment is a leather-like sheet comprising a fibrous base material and a colored resin layer laminated on the fibrous base material, wherein the colored resin layer includes an intermediate layer and a surface layer laminated on the intermediate layer, and the surface layer is made of polyurethane and 3 g / m 2 The above is a layer containing an infrared-reflective black pigment, and the intermediate layer is a layer containing polyurethane and a black pigment, L * a * b * In a color system, lightness L * This is a leather-like sheet with a surface value of ≤30.

[0022] Figure 1 is a schematic cross-sectional view illustrating the layer structure of a leather-like sheet 10, which is an example of a leather-like sheet according to this embodiment. The leather-like sheet 10 comprises a fiber base material 1, a porous layer 2 mainly composed of polyurethane laminated on the fiber base material 1, a colored resin layer 5 including an intermediate layer 3 and a surface layer 4 adhered to the intermediate layer 3, and an adhesive layer 6 mainly composed of polyurethane that bonds the porous layer 2 and the colored resin layer 5. The leather-like sheet is not limited to this layer structure; any leather-like sheet comprising a fiber base material and a colored resin layer laminated on the fiber base material, including the intermediate layer and surface layer described above, is acceptable. The surface layer may, if necessary, be further provided with a clear layer of about 1 to 5 μm in thickness, which is an uncolored transparent resin layer, on its surface, as long as it does not impair the effects of the present invention.

[0023] As the fiber base material, conventionally known artificial leather base materials used in the manufacture of artificial leather and synthetic leather base materials used in synthetic leather can be used without particular limitation, such as nonwoven fabrics, woven fabrics, knitted fabrics, or base materials to which a polymer elastic material such as polyurethane has been impregnated. In addition, pigments may be blended into the polymer elastic material as needed. The thickness of the fiber base material is not particularly limited, but is preferably, for example, 0.3 to 3 mm, and more preferably 0.5 to 1.5 mm. Furthermore, the type of fiber forming the fiber base material is not particularly limited, and is not particularly limited, for example, nylon fibers, polyester fibers, polyolefin fibers, polyurethane fibers, etc.

[0024] Furthermore, the fineness and morphology of the fibers are not particularly limited. For example, the fineness may be that of a regular fiber greater than 1 dtex, or an ultrafine fiber less than 1 dtex. Also, the morphology of the fibers may be that of a solid fiber, or a hollow fiber or a fiber having voids such as a lotus root-like fiber.

[0025] The epidermal layer contains 3 g / m². 2 This is a surface-coloring polyurethane layer containing the above-mentioned infrared-reflective black pigment.

[0026] The epidermal layer contains 3 g / m². 2As a result of the polyurethane layer containing the above-mentioned infrared-reflective black pigment, a colored polyurethane layer with high reflectivity to near-infrared pulsed laser light is obtained, as will be described later.

[0027] An infrared-reflective black pigment is a black pigment with high reflectivity to near-infrared rays, having a reflectivity of 25% or more to near-infrared rays at a wavelength of 905 nm, a reflectivity of 50% or more to near-infrared rays at a wavelength of 1550 nm, and a transmittance of 50% or less to near-infrared rays at a wavelength of 905 nm. Furthermore, it is preferable that the infrared-reflective black pigment has a reflectivity of 30% or more to near-infrared rays at a wavelength of 905 nm, and a transmittance of 30% or less, more preferably 20% or less, and especially 10% or less. Specific examples of such infrared-reflective black pigments include, for example, CaO-Tio2-MnO2-based titanium-based black pigments (e.g., Typake Black SG-103 manufactured by Ishihara Sangyo Co., Ltd.), titanium-based black pigments (Tilack D) manufactured by Ako Kasei Co., Ltd., and composite oxide pigments of chromium oxide and iron oxide. CaO-Tio2-MnO2-based titanium black pigments have a reflectance of 30% or more for near-infrared light at a wavelength of 905 nm, a reflectance of 55% or more for near-infrared light at a wavelength of 1550 nm, and a transmittance of 10% or less for near-infrared light at a wavelength of 905 nm.

[0028] For example, in the case of CaO-Tio2-MnO2-based titanium black pigments, a calcium compound, a titanium compound, and a manganese compound are mixed by a wet grinding method and then fired at a temperature higher than 1100°C. Such CaO-Tio2-MnO2-based titanium black pigments have a perovskite phase as the main phase and a BET specific surface area of ​​1.0 m². 2 / g or more 3.0m 2 It is preferable that the amount be less than / g.

[0029] The epidermal layer contains 3 g / m² of infrared-reflective black pigment. 2 It contains the above amount, preferably 3-5 g / m² 2 Contains. The infrared reflective black pigment content is 3 g / m 2If the value is less than the specified amount, the reflectivity of the leather-like sheet to near-infrared light will be low, reducing its detectability by the LIDAR sensor. Furthermore, if the content of infrared-reflective black pigment is too high, the blackness will be low, and cost-effectiveness will also decrease.

[0030] The epidermal layer contains 3 g / m² of infrared-reflective black pigment. 2 As long as the above amount is contained, the thickness is not particularly limited, but it is preferably 10 μm or more, and more preferably 20 to 30 μm. If the epidermal layer is too thin, 3 g / m of infrared reflective black pigment may be added. 2 It tends to become more difficult to contain the above amounts.

[0031] Furthermore, the proportion of infrared-reflective black pigment in the epidermal layer is also such that the epidermal layer contains 3 g / m² of infrared-reflective black pigment. 2 As long as it contains the above amount, it is not particularly limited, but it is preferable that it be 10% by mass or more, more preferably 15% by mass or more, and especially preferably 20% by mass or more. If the content of infrared reflective black pigment is too low, add 3 g / m of infrared reflective black pigment. 2 It becomes difficult to achieve a high concentration of the ingredient, and if the concentration is too high, the blackness decreases, and cost-effectiveness tends to decline.

[0032] Furthermore, the surface layer may not contain carbon black, or may contain 0 to 0.5 g / m² of carbon black, depending on the type of carbon black, within a range that does not impair the effects of the present invention. 2 Furthermore, 0-0.1 g / m 2 It may contain within the range of 0.5 g / m². The epidermal layer contains carbon black. 2 If the amount exceeds a certain limit, the carbon black preferentially absorbs the near-infrared light irradiated onto the surface of the resulting leather-like sheet, resulting in a lower near-infrared reflectivity and a tendency for detection by LIDAR sensors to decrease.

[0033] Furthermore, the epidermal layer may contain other pigments besides carbon black, as long as they do not impair the effects of the present invention. The other pigments are not particularly limited as long as their absorption rate in the near-infrared wavelength range of 905 to 1600 nm is not too high, but specifically, examples include anthraquinone-based pigments, diketopyrrolopyrrole-based pigments, and perylene-based pigments such as perylene black.

[0034] For example, perylene black has a transmittance of over 60% to near-infrared light at a wavelength of 905 nm. Therefore, when used alone, its low near-infrared reflectivity results in poor detection by LIDAR sensors, and it also produces poor dark colors.

[0035] The average dispersed particle size in the colored resin layer of the infrared-reflective black pigment is not particularly limited, but is preferably 1 to 10 μm, and more preferably 1.5 to 8 μm. When the average dispersed particle size of the infrared-reflective black pigment is within this range, diffuse reflection of light on the surface of the infrared-reflective black pigment particles is easily suppressed, and a highly black colored resin layer with high blackness tends to be formed. If the average dispersed particle size of the infrared-reflective black pigment is too small, diffuse reflection of light is more likely to occur on the surface of the infrared-reflective black pigment particles, which tends to cause the surface of the leather-like sheet to develop a reddish tint. Also, if the average dispersed particle size of the infrared-reflective black pigment is too large, the mechanical properties of the colored resin layer film tend to decrease, which tends to reduce the abrasion resistance of the surface of the leather-like sheet.

[0036] On the other hand, the intermediate layer is a layer containing polyurethane and black pigment, and is colored in a dark color.

[0037] The intermediate layer is a polyurethane layer that is colored dark by containing black pigment. This intermediate layer is used to adjust the color so that the visible color from the surface is dark, without having to incorporate a large amount of carbon black into the surface layer.

[0038] Examples of black pigments included in the intermediate layer include carbon black such as furnace black, channel black, and acetylene black, infrared reflective black pigments, and composite oxide-based black pigments. Among these, carbon black is preferred because it easily yields a dark-colored surface. Infrared reflective black pigments are also preferred because they further increase the reflectivity of near-infrared rays.

[0039] The intermediate layer may contain other pigments besides black pigment for color matching, as long as they do not hinder the effects of the present invention. The other pigments are not particularly limited, but examples include anthraquinone-based pigments, diketopyrrolopyrrole-based pigments, perylene-based pigments, and the like.

[0040] If the intermediate layer contains carbon black as a black pigment, the carbon black content should be 0.2 g / m². 2 Furthermore, 0.5~5g / m 2 It contains L * This is preferable because it makes it easier to obtain a dark-colored leather-like sheet with a surface value of ≤30. Furthermore, if the intermediate layer contains an infrared-reflective black pigment as the black pigment, the infrared-reflective black pigment is 2 g / m². 2 Furthermore, 2-5g / m 2 It contains L * This is preferable because it makes it easier to obtain a dark-colored leather-like sheet with a surface value of ≤30.

[0041] The thickness of the intermediate layer is such that the surface of the leather-like sheet has a brightness of L * While not particularly limited as long as it can be adjusted to a surface with a value ≤ 30, it is preferably 10 to 50 μm, and more preferably 20 to 30 μm. If the intermediate layer is too thin, L * It tends to be more difficult to adjust to darker surfaces, such as values ​​≤ 30.

[0042] Furthermore, the proportion of black pigment in the intermediate layer is determined by the surface of the leather-like sheet. *It is not particularly limited as long as it can be adjusted to a surface with a value of ≤30. When carbon black is included as the black pigment, it is preferable to include 2% by mass or more, and more preferably 2 to 10% by mass, of carbon black. Also, when infrared reflective black pigment is included as the black pigment, it is preferable to include 10% by mass or more, and more preferably 10 to 20% by mass, of infrared reflective black pigment. If the content of black pigment is too low, L * It tends to be difficult to obtain dark-colored surfaces with a value of ≤ 30.

[0043] Polyurethanes for forming the intermediate layer, surface layer, and porous layer are obtained by reacting urethane raw materials containing high-molecular-weight polyols, organic polyisocyanates, and chain extenders. During the production of leather-like sheets, polyurethanes are prepared as a melt, an organic solvent solution (e.g., a solution of organic solvents such as dimethylformamide, methyl ethyl ketone, acetone, or toluene), an aqueous dispersion, or an emulsion.

[0044] Specific examples of polymeric polyols include, for example, polyether polyols such as polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and polymethyltetramethylene glycol; polycarbonate polyols such as polyhexamethylene carbonate diol, poly(3-methyl-1,5-pentylene carbonate) diol, polypentamethylene carbonate diol, and polytetramethylene carbonate diol; polyester polyols such as polyethylene adipate diol, polybutylene adipate diol, polypropylene adipate diol, polybutylene sebacate diol, polyhexamethylene adipate diol, poly(3-methyl-1,5-pentylene adipate) diol, poly(3-methyl-1,5-pentylene sebacate) diol, and polycaprolactone diol, or copolymers thereof. These may be used individually or in combination of two or more types.

[0045] Specific examples of organic polyisocyanates include, for example, non-yellowing diisocyanates containing aromatic diisocyanates such as 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, and xylylene diisocyanate; and non-yellowing diisocyanates such as aliphatic or alicyclic diisocyanates such as hexamethylene diisocyanate, isophorone diisocyanate, norbornene diisocyanate, and 4,4'-dicyclohexylmethane diisocyanate. Furthermore, polyfunctional isocyanates such as trifunctional or tetrafunctional isocyanates may be used in combination as needed. These may be used individually or in combination of two or more.

[0046] Specific examples of chain extenders include, for example, diamines such as hydrazine, ethylenediamine, propylenediamine, hexamethylenediamine, nonamethylenediamine, xylylenediamine, isophoronediamine, piperazine and its derivatives, adipic acid dihydrazide, isophthalic acid dihydrazide; triamines such as diethylenetriamine; tetramines such as triethylenetetramine; diols such as ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, 1,4-bis(β-hydroxyethoxy)benzene, 1,4-cyclohexanediol; triols such as trimethylolpropane; tetraols such as pentaerythritol; and amino alcohols such as aminoethyl alcohol and aminopropyl alcohol. These may be used individually or in combination of two or more. Furthermore, during the chain extension reaction, monoamines such as ethylamine, propylamine, and butylamine; carboxyl group-containing monoamine compounds such as 4-aminobutanoic acid and 6-aminohexanoic acid; and monools such as methanol, ethanol, propanol, and butanol may be used in combination with the chain extension agent.

[0047] The polyurethane for forming the porous layer is formed, for example, by applying a wet-coagulation polyurethane solution to the surface of a fiber substrate, and then immersing it in an aqueous coagulation bath to solidify the porous polyurethane. The porous layer may also penetrate into the interior of the fiber substrate for purposes such as providing morphological stability. In this case, the fiber substrate can be impregnated with a polyurethane solution beforehand, and then coated with another polyurethane solution before being immersed in an aqueous coagulation bath to solidify it, thereby providing porous polyurethane to the interior of the fiber substrate as well. The thickness of the porous layer is not particularly limited, but is preferably, for example, 100 to 600 μm, and more preferably 200 to 400 μm.

[0048] To form an intermediate layer and an epidermal layer on the surface of a porous layer, for example, a dry surface preparation method such as the following can be used.

[0049] A polyurethane film for forming the surface layer is formed on the release paper. Then, a polyurethane film for forming the intermediate layer is formed on the polyurethane film of the surface layer, thereby forming a colored resin layer that includes the intermediate layer and the surface layer laminated on the intermediate layer. The colored resin layer may further include other layers besides the intermediate layer below the surface layer.

[0050] Next, an adhesive is applied to the colored resin layer, and the solvent is completely or partially removed and dried. Then, the adhesive laminated onto the colored resin layer formed on the release paper is bonded to the surface of the porous layer and pressed, and the adhesive is cured to bond the porous layer and the colored resin layer via the adhesive layer. Finally, by peeling the release paper from the surface of the colored resin layer, a leather-like sheet is obtained comprising a fibrous base material and a colored resin layer laminated onto the fibrous base material.

[0051] The leather-like sheet of this embodiment is made of a colored resin layer comprising a surface layer containing an infrared-reflective black pigment as described above and an intermediate layer containing a black pigment, L * a * b * In a color system, L *The leather-like sheet is colored so that it has a surface with a value of ≤ 30.

[0052] Note L * a * b * In a color system, lightness L * Coloring such that the surface has a value ≤ 30 means that the dark colored surface, which is the design surface of the leather-like sheet, is colored using a spectrophotometer and the result is L * a * b * Lightness L calculated from the coordinate values ​​of the color system * This means the value is ≤ 30. For the lightness of a dark surface, L * Value ≤ 30, and furthermore, L * It is preferable that the value be ≤ 25.

[0053] The leather-like sheet of this embodiment has a surface layer containing the infrared-reflective black pigment described above, thereby providing a leather-like sheet with high reflectivity to near-infrared light. As a result, a dark-colored leather-like sheet that is easily detected by a LIDAR sensor can be obtained.

[0054] Brightness L of this leather-like sheet * For surfaces with a value ≤ 30, it is preferable that the reflectance to near-infrared light at a wavelength of 905 nm is 10% or more, and more preferably 15% or more. Furthermore, it is preferable that the reflectance to near-infrared light at a wavelength of 1550 nm is 10% or more, and more preferably 15% or more.

[0055] Furthermore, the solar reflectance of the surface of the leather-like sheet in the wavelength range of 250-2500 nm is preferably 10% or more, and more preferably 15% or more. When the solar reflectance is within this range, in addition to having high reflectance to near-infrared rays, it also has good color development and brightness L * This is preferable because it makes it easier to obtain leather-like sheets with a value of ≤30.

[0056] As described above, the leather-like sheet of this embodiment is preferably used as a leather-like sheet with a grain finish that resembles natural leather, and is used as an outer covering material for bags, clothing, shoes, etc. In particular, it is preferably used as a material for backpacks such as school bags, where the leather-like sheet is used as a back cover that covers a large area of ​​the wearer's body, or as a material for clothing, as a grain finish leather-like sheet that can be detected with high precision by a LIDAR sensor even when a large area of ​​the body is covered by it.

[0057] In particular, when small children wear school backpacks, a large portion of their body may be hidden by the backpack. In such cases, children wearing backpacks that are difficult to detect with LIDAR sensors are less likely to be noticed by cars equipped with LIDAR sensors. With the backpack of this embodiment, the back material is more easily detected by cars equipped with LIDAR sensors, thus reducing the possibility of traffic accidents involving children on their way to school.

[0058] Such leather-like sheets are preferable because, for example, the reflectance intensity measured from the surface layer side using a Livox Technology Company Limited HORIZON LIDAR sensor, at a wavelength of 905 nm and a measurement distance of 10 m, is 40 or higher, and even 50 or higher, as this makes them easier to detect by LIDAR sensors, such as those installed as safety devices in automobiles. [Examples]

[0059] The present invention will be described in more detail below with reference to examples. However, the scope of the present invention is not limited in any way to these examples.

[0060] [Example 1] A sea-island type composite fiber containing 45 parts by mass of nylon 6 (sea component) and 55 parts by mass of polystyrene (island component) was melt-spun, stretched to three times its original length, treated with a fiber oil, mechanically crimped, and then dried. The resulting crimped fibers were cut to 51 mm lengths and stapled to form a 3-decitex staple, which was used to form a web. Then, the web was alternately joined from both sides and punched at approximately 500 punches / cm².2 A tangled nonwoven fabric was obtained by needle punching. The basis weight of this tangled nonwoven fabric was 350 g / m². 2 The apparent specific gravity was 0.17. This entangled nonwoven fabric was treated with a 4% aqueous solution of polyvinyl alcohol, compressed and fixed to a thickness of approximately 1.3 mm, and the surface was buffed to make it smooth. Then, a 13% concentration polyurethane dimethylformamide (hereinafter referred to as DMF) solution mainly composed of polyester polyurethane was impregnated into it. Furthermore, the same polyurethane solution was applied to the surface at a solid content of 100 g / m². 2 After applying the required amount, the polyurethane was wet-coated into a porous state by immersion in a DMF / water mixture. Then, the island components were eluted and removed in hot toluene to convert the sea-island type composite fibers into hollow fibers. In this way, a fibrous substrate with a porous layer that had penetrated the surface was obtained. The thickness of the porous layer was 300 μm.

[0061] Next, on a release paper (R-70 manufactured by Lintec Corporation), a polyurethane composition solution containing 100 parts by mass of a 22% DMF solution of non-yellowing polycarbonate polyurethane, 30 parts by mass of a black vehicle containing 20% ​​by mass of infrared reflective black pigment (titanium-based black pigment), and 30 parts by mass of DMF is spread at a density of 100 g / m² so that the thickness after drying is approximately 20 μm. 2 A black surface layer was formed by coating and drying at 120°C for 2 minutes. The titanium-based black pigment used was Typake Black SG103, a CaO-Tio2-MnO2-based black pigment manufactured by Ishihara Sangyo Co., Ltd., which has a reflectance of 30.1% at 905 nm, a reflectance of 57.1% at 1550 nm, and a transmittance of less than 10% to near-infrared light at a wavelength of 905 nm. The resulting surface layer did not contain carbon black, and the amount of titanium-based black pigment contained in the surface layer was 4.8 g / m². 2 Furthermore, the content of titanium-based black pigment in the epidermal layer was 20% by mass.

[0062] Then, on the surface layer, a polyurethane composition solution containing 100 parts by mass of a 30% DMF solution of non-yellowing polyether polyurethane, 20 parts by mass of a black vehicle containing 5% by mass of carbon black (furnace black), and 30 parts by mass of DMF and 30 parts by mass of MEK is applied at a density of 120 g / m² so that the thickness after drying is approximately 20 μm. 2 A black intermediate layer was formed by coating and drying at 120°C for 2 minutes. The furnace black has a reflectance of approximately 5% at 905 nm, approximately 6% at 1550 nm, and a transmittance of less than 5% for near-infrared light at a wavelength of 905 nm. The amount of carbon black per unit area of ​​the resulting intermediate layer was 0.6 g / m². 2 Furthermore, the carbon black content in the intermediate layer was 3% by mass.

[0063] Then, a polyurethane adhesive solution is applied to the surface of the intermediate layer formed on the release paper at a rate of 110 g / m². 2 An adhesive layer was formed by applying the adhesive and drying it at 120°C for 2 minutes to evaporate the solvent. Then, the adhesive layer on the release paper was bonded to a porous layer laminated on a fibrous substrate to produce a laminated intermediate. The laminated intermediate was then pressed together by pressing it with a roll at a surface temperature of 75°C with a clearance. After curing at 50°C for 3 days, the release paper was peeled off to obtain a leather-like sheet, which is a silver-plated artificial leather with a black surface.

[0064] The resulting leather-like sheets were then evaluated as follows.

[0065] (L * (Measurement of values) L on the surface of the leather-like seat * a * b * The coordinate values ​​of the color system were measured using a spectrophotometer (Minolta CM-3700), and L * The values ​​were calculated. The sample size was N=3, and the average value was calculated.

[0066] (reflectance, transmittance) The reflectance of the surface of the leather-like sheet was determined by measuring the reflectance spectrum in the wavelength range of 250 nm to 2500 nm using a spectrophotometer (V-770 spectrophotometer and ISN-923 integrating sphere, manufactured by JASCO Corporation), and reading the reflectances at 905 nm and 1550 nm. The average of the reflectances in the entire wavelength range from 250 nm to 2500 nm was calculated as the solar reflectance. The reflectance and transmittance of the titanium-based black pigment were measured using an ultraviolet-visible-near-infrared spectrophotometer (V-670, manufactured by Nippon Denshoku Industries, Ltd.). The sample was placed in a measurement cell in powder form, and the spectral reflectance and transmittance in the range of 300 nm to 2500 nm were measured.

[0067] (LIDAR sensor reflectivity) As shown in Figure 2, a 26cm x 26cm leather-like sheet was placed vertically within a frame enclosed by black cardboard. A HORIZON sensor manufactured by Livox Technology Company Limited was placed at a measurement distance of 10m, with the light-emitting part at a height of 41cm, and laser light with a wavelength of 905nm was irradiated. The reflection intensity was then measured using a method that quantifies the energy of the laser light reflected from the object, ranging from 0 (total absorption) to 255 (total reflection). Figure 3 shows the results when the near-infrared reflection intensity of the surface of the leather-like sheet was measured with a LIDAR sensor. (a) shows the surface of the leather-like sheet of Example 1, and (b) shows the surface of the leather-like sheet of Comparative Example 1.

[0068] (Average dispersed particle size) Using a scanning electron microscope (JEOL Ltd. JSM-IT500), 2000x magnification SEM images were taken of the cross-section in the thickness direction of the colored resin layer of a test piece cut from a leather-like sheet. Then, an arbitrary 2500 μm 2The particle size Rn of n individual particles of all infrared-reflecting black pigments observed within the specified range was measured. The longest portion of each observed infrared-reflecting black pigment was used as the particle size. If multiple particles aggregated to form secondary particles, the longest portion of these secondary particles was used as the particle size. Furthermore, if multiple types of black pigment particles were present within the SEM imaging range, qualitative analysis using EDS elemental analysis was performed beforehand within the SEM imaging range to identify the infrared-reflecting black pigments for which particle size measurement was to be performed. Then, the volume Vn of each of the n obtained particle sizes Rn was calculated using the following formula. Note that each volume Vn was calculated assuming a spherical shape. The volume of the particles of the infrared-reflective black pigment is Vn = 4 / 3 × π × (Rn / 2). 3 Then, the n volumes Vn obtained were arranged in ascending order of particle size Rn, and the cumulative sum was calculated to obtain the volume cumulative frequency. From the graph plotting the volume cumulative frequency against particle size Rn, the particle size at which the volume cumulative frequency reached 50% was defined as the dispersed particle size (D50). The above measurements were performed at five arbitrary points on the leather-like sheet, and the average value of the dispersed particle size (D50) at the five points was defined as the mean dispersed particle size.

[0069] The results are shown in Table 1 below.

[0070] [Table 1]

[0071] [Example 2] In Example 1, 4.8 g / m 2 Instead of the epidermal layer containing the infrared-reflective black pigment, use 3.4 g / m 2 Artificial leather was obtained and evaluated in the same manner as in Example 1, except that the surface layer was changed to one containing an infrared-reflective black pigment. The results are shown in Table 1.

[0072] [Example 3] In Example 1, 0.6 g / m 2 Instead of an intermediate layer containing carbon black, use 3.4 g / m 2Artificial leather was obtained and evaluated in the same manner as in Example 1, except that the intermediate layer containing an infrared-reflective black pigment was changed. The results are shown in Table 1.

[0073] [Example 4] In Example 3, 4.8 g / m 2 Instead of the epidermal layer containing infrared reflective black pigment, use 4.8 g / m 2 Infrared reflective black pigment and 0.5 g / m 2 Artificial leather was obtained and evaluated in the same manner as in Example 1, except that the surface layer contained carbon black. The results are shown in Table 1.

[0074] [Comparative Example 1] In Example 1, 4.8 g / m 2 Instead of the epidermal layer containing the infrared-reflective black pigment, use 3.4 g / m 2 Artificial leather was obtained and evaluated in the same manner as in Example 1, except that the surface layer containing carbon black was changed to adjust the color to a black with an approximate brightness. The results are shown in Table 1.

[0075] [Comparative Example 2] In Example 1, 0.6 g / m 2 Artificial leather was obtained and evaluated in the same manner as in Example 1, except that the intermediate layer containing carbon black was replaced with an intermediate layer that does not contain pigment. The results are shown in Table 1.

[0076] [Comparative Example 3] In Example 1, 4.8 g / m 2 Instead of the epidermal layer containing the infrared-reflective black pigment, use 1.9 g / m 2 Infrared reflective black pigment and 1.9 g / m 2 Artificial leather was obtained and evaluated in the same manner as in Example 1, except that the surface layer contained carbon black. The results are shown in Table 1.

[0077] [Comparative Example 4] In Example 1, 4.8 g / m 2 Instead of the epidermal layer containing the infrared-reflective black pigment, use 2.9 g / m 2 Infrared reflective black pigment and 1.9 g / m2 An artificial leather was obtained and evaluated in the same manner as in Example 1, except that the skin layer containing carbon black was changed. The results are shown in Table 1.

[0078] [Comparative Example 5] In Example 1, instead of the skin layer containing 4.8 g / m 2 of infrared-reflective black pigment, 4.8 g / m 2 of infrared-reflective black pigment and 0.6 g / m 2 of carbon black were used to form the skin layer. Instead of the intermediate layer containing 0.6 g / m 2 of carbon black, an intermediate layer containing no pigment was used. An artificial leather was obtained and evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0079] [Comparative Example 6] In Example 1, an artificial leather was obtained and evaluated in the same manner as in Example 1, except that the skin layer and the intermediate layer were interchanged. The results are shown in Table 1.

[0080] [Comparative Example 7] In Example ①, instead of the skin layer containing 4.8 g / m 2 of infrared-reflective black pigment, 4.8 g / m 2 of perylene-based black pigment was used to form the skin layer. An artificial leather was obtained and evaluated in the same manner as in Example 1. For the perylene-based black pigment, perylene black (Paliogen Black L0084) with a transmittance of 65% or more for near-infrared light with a wavelength of 905 nm was used. The results are shown in Table 1.

[0081] [Comparative Example 8] In Example 3, instead of the skin layer containing 4.8 g / m2 of infrared-reflective black pigment, 4.8 g / m 2 of perylene-based black pigment (Paliogen Black L0084) was used to form the skin layer. An artificial leather was obtained and evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0082] Referring to Table 1, when the skin layer is 3 g / m 2 Note: There seems to be a typo in "実施例①" in line 27, which should probably be "実施例1". This has been translated as "Example 1" while keeping the error in the original text for accuracy in translation.The leather-like sheets of artificial leather of Examples 1 to 4, which contain the above infrared-reflecting black pigment and in which the intermediate layer is a layer containing a black pigment, all had an L * value ≤ 30 and a dark-colored surface, and were leather-like sheets with high detectability by a LIDAR sensor. On the other hand, the leather-like sheets of Comparative Examples 1, 3, 4, and 6, which did not contain 3 g / m 2 or more of the infrared-reflecting black pigment in the epidermal layer, all had insufficient detectability by the LIDAR sensor. Also, the leather-like sheet of artificial leather of Comparative Example 2, in which the epidermal layer contained 3 g / m 2 or more of the infrared-reflecting black pigment but the intermediate layer was a layer not containing a black pigment, did not obtain a dark-colored surface with an L * value ≤ 30. Furthermore, the leather-like sheet of artificial leather of Comparative Example 5, in which the epidermal layer contained carbon black together with 3 g / m 2 or more of the infrared-reflecting black pigment and the intermediate layer was a layer not containing a black pigment, obtained a dark-colored surface with an L * [[ID= Twelve]]value ≤ 30, but due to the absorption of near-infrared rays by the carbon black, the detectability by the LIDAR sensor was not sufficient. Furthermore, the leather-like sheet of artificial leather of Comparative Example Seven, in which the epidermal layer contained a perylene-based black pigment and the intermediate layer was a layer containing a black pigment, obtained a dark-colored surface with an L * value ≤ 30, but since the epidermal layer easily transmitted near-infrared rays, the detectability by the LIDAR sensor was not sufficient. Also, the leather-like sheet of Comparative Example 8, in which the epidermal layer contained a perylene-based black pigment and the intermediate layer was a layer containing an infrared-reflecting black pigment, had good detectability by the LIDAR sensor, but an L * value ≤ 30 and a dark-colored surface were not obtained.

Explanation of Signs

[0083] 1 Fiber substrate 2 Porous layer 3 Intermediate layer 4 Epidermal layer 5 Colored resin layer 6 Adhesive layer 10 Leather-like sheet

Claims

1. A leather-like sheet comprising a fibrous base material, a porous layer with a thickness of 100 to 600 μm laminated on the fibrous base material, and a colored resin layer laminated on the porous layer, The colored resin layer includes an intermediate layer and a surface layer laminated on the intermediate layer. The aforementioned surface layer is made of polyurethane and 3 g / m² ２ It contains the above infrared reflective black pigments, The aforementioned intermediate layer is a layer containing polyurethane and black pigment. The infrared-reflecting black pigment includes at least one selected from CaO-TiO₂-MnO₂-based titanium-based black pigments, Tilack D (registered trademark), a titanium-based black pigment manufactured by Ako Chemical Co., Ltd., and a composite oxide pigment of chromium oxide and iron oxide. L * a * b * In a color system, lightness L * Having a surface with a value ≤ 30, A leather-like sheet characterized in that the LIDAR sensor reflectance of the surface, measured using a HORIZON manufactured by Livox Technology Company Limited, is 40 or higher at a wavelength of 905 nm and a measurement distance of 10 m.

2. The leather-like sheet according to claim 1, wherein the reflectance to near-infrared light with a wavelength of 905 nm is 10% or more, and the reflectance to near-infrared light with a wavelength of 1550 nm is 10% or more.

3. The leather-like sheet according to claim 1 or 2, wherein the solar reflectance in the wavelength range of 250 to 2500 nm is 10% or more on average.

4. The leather-like sheet according to any one of claims 1 to 3, wherein the infrared-reflective black pigment has a reflectance of 25% or more to near-infrared light with a wavelength of 905 nm, a reflectance of 50% or more to near-infrared light with a wavelength of 1550 nm, and a transmittance of less than 50% to near-infrared light with a wavelength of 905 nm.

5. The aforementioned infrared reflective black pigment is CaO-TiO 2 -MnO 2 A leather-like sheet according to any one of claims 1 to 4, comprising a titanium-based black pigment.

6. The aforementioned surface layer contains 0 to 0.5 g / m² of carbon black. ２ A leather-like sheet containing any one of claims 1 to 5.

7. The surface layer is a leather-like sheet according to any one of claims 1 to 5, wherein the surface layer does not contain carbon black.

8. The leather-like sheet according to any one of claims 1 to 7, wherein the intermediate layer contains carbon black as a black pigment.

9. The leather-like sheet according to any one of claims 1 to 8, wherein the thickness of the surface layer is 10 to 30 μm.

10. The leather-like sheet according to any one of claims 1 to 9, wherein the thickness of the intermediate layer is 10 to 50 μm.

11. A backpack characterized by using a leather-like sheet as the backing material according to any one of claims 1 to 10.

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