Decorative sheet

Abstract

To provide a decorative sheet which has improved wiping property on its surface against a contaminant substance having high viscosity, and has a wrinkle-like uneven surface on the surface.SOLUTION: A decorative sheet 10 has a matte layer 30 having an uneven surface 32, wherein the matte layer 30 contains a resin layer 36 and a plurality of particles 38, the uneven surface 32 has a wrinkle structure, 60-degree specular glossiness specified in JIS Z8741:1997 on the uneven surface 32 is 5 or less, and an average length RSm specified in JIS B0601:2013 on the uneven surface 32 is 25 μm or more and 35 μm or less.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to decorative sheets. [Background technology]

[0002] Decorative sheets have traditionally been used for the interior and exterior decoration of buildings, the surfaces of fixtures, furniture, home appliances, and the interior decoration of vehicles. Decorative sheets can have a design layer. The design layer includes a picture layer corresponding to a predetermined pattern, color, and the like. A matte layer for suppressing gloss may be provided on the surface of the decorative sheet. The matte layer has an uneven surface (a so-called matte surface) on its surface. Light incident on the matte layer is diffusely reflected and diffused by this uneven surface, thereby reducing the gloss on the surface of the matte layer.

[0003] In recent years, a method for producing a textured surface has been proposed in which an excimer light is used to form a wrinkled textured surface on the surface of a resin. One example of such a method for producing a textured surface is disclosed in Patent Document 1. In Patent Document 1, first, an excimer light is irradiated onto the surface of a coating film made of a photocurable resin. Then, ultraviolet light is irradiated onto the coating film to cure the entire coating film. As a result, wrinkles are formed on the surface of the coating film. In Patent Document 1, the wrinkles formed in this manner result in a coating film with low gloss. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-24102 Summary of the Invention [Problem to be solved by the invention]

[0005] With use, decorative sheets may become soiled. When soiling a decorative sheet, it is removed by wiping it off with, for example, a cloth or tissue paper. Therefore, decorative sheets are required to have a surface with good wiping properties. That is, they are required to be able to easily remove soil by rubbing the surface of the decorative sheet with a cloth or tissue paper. However, in the past, decorative sheets with a wrinkled, uneven surface have made it difficult to remove soiling adhered to the decorative sheet due to the wrinkled, uneven structure. In particular, when the soiling includes highly viscous contaminants such as crayons, shoe polish, or lipstick, the contaminants may spread when wiping. Therefore, removing highly viscous contaminants has been particularly difficult. Therefore, there have been no decorative sheets with a wrinkled, uneven surface that have achieved good wiping properties for highly viscous contaminants.

[0006] An embodiment of the present disclosure aims to improve the wiping ability of a decorative sheet having a wrinkled, uneven surface against highly viscous contaminants. [Means for solving the problem]

[0007] A decorative sheet according to one embodiment of the present disclosure comprises: A matte layer having an uneven surface is provided, the matte layer includes a resin layer and a plurality of particles, the uneven surface has a wrinkled structure, The 60° specular gloss of the uneven surface as defined in JIS Z8741:1997 is 5 or less, A decorative sheet in which the mean length RSm of the uneven surface as defined in JIS B0601:2013 is 25 μm or more and 35 μm or less. [Effects of the Invention]

[0008] According to one embodiment of the present disclosure, in a decorative sheet having a wrinkled uneven surface, the wiping ability of the surface against highly viscous contaminants is improved. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram illustrating an embodiment of the present disclosure, and is a cross-sectional view of an example of a decorative sheet. [Figure 2] FIG. 2 is a photograph of the textured surface of Sample 1. [Figure 3] FIG. 3 is a photograph of the textured surface of Sample 2. [Figure 4] FIG. 4 is a photograph of the textured surface of Sample 3. [Figure 5] FIG. 5 is a photograph of the uneven surface of Sample 4. [Figure 6] FIG. 6 is a photograph of the textured surface of Sample 5. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the drawings attached to this specification, the scale and aspect ratios have been changed and exaggerated from those of the actual objects in order to make the drawings easier to understand. Note that the embodiments shown below are examples of embodiments of the present disclosure. Therefore, the present disclosure should not be interpreted as being limited to these embodiments.

[0011] In this specification, the terms "plate," "sheet," and "film" are not distinguished from one another solely based on differences in name. For example, "sheet" also includes members called "plate" or "film."

[0012] Furthermore, the term "plate surface (sheet surface, film surface)" refers to the surface that coincides with the extension direction of the target plate-shaped (sheet-shaped, film-shaped) member when the target plate-shaped (sheet-shaped, film-shaped) member is viewed overall and in a broad perspective. Furthermore, the normal direction used for a plate-shaped (sheet-shaped, film-shaped) member refers to the direction in which the normal to the plate surface (sheet surface, film surface) of the member extends.

[0013] In this specification, "plan view" refers to the state of a target plate-shaped (sheet-shaped, film-shaped) member as viewed from the normal direction of the member. For example, when a certain plate-shaped member "has a rectangular shape in a plan view," this means that the member has a rectangular shape when viewed from the normal direction to the plate surface.

[0014] Terms used in this specification that specify shapes, geometric conditions, physical characteristics, and their degrees, such as "parallel," "orthogonal," and "identical," as well as ranges of lengths, angles, and values ​​of physical characteristics, are not strictly limited to those ranges but include ranges within which similar functions can be expected, unless otherwise specified to be strictly interpreted.

[0015] The decorative sheet 10 of the embodiment of the present disclosure is used, for example, as a component constituting the outermost layer of the interior and exterior of buildings, the surfaces of fixtures, furniture, and home appliances, and the interior of vehicles. More specifically, the decorative sheet 10 may be used, for example, as interior components for buildings such as walls, ceilings, and floors; exterior components such as exterior walls, eaves ceilings, roofs, fences, and fences; fixtures or fittings such as window frames, doors, door frames, handrails, baseboards, moldings, and other fixtures and fittings; general furniture such as chests of drawers, shelves, and desks; kitchen furniture such as dining tables and sinks; surface decorative panels for cabinets and the like for home appliances and office automation equipment; and interior and exterior components for vehicles. The decorative sheet 10 may also be used for packaging materials, antiglare films for displays, whiteboards or blackboards, various cards such as credit cards, cash cards, telephone cards, and various certificates; various keyboard keys; transparent panels (window glass, etc.) for windows, doors, and partitions; artificial leather, etc.

[0016] The decorative sheet 10 of this embodiment includes a matte layer 30. The matte layer 30 has an uneven surface 32 and a back surface 34. The uneven surface 32 and the back surface 34 face each other and face away from each other. The uneven surface 32 constitutes the surface of the matte layer 30. The uneven surface 32 is a so-called matte surface. Light incident on the matte layer 30 is diffusely reflected and diffused by the uneven surface 32. This reduces the gloss on the surface of the matte layer 30. In other words, the matte layer 30 exhibits a matte effect. In this embodiment, the uneven surface 32 has a specific shape. Therefore, dirt can be easily removed by rubbing the dirty areas of the uneven surface 32 with a cloth, tissue paper, or the like. In particular, the uneven surface 32 of this embodiment has a shape that allows for easy removal of viscous contaminants that have adhered to it. This improves the ease with which viscous contaminants can be wiped off the uneven surface 32. In particular, in the decorative sheet 10 of this embodiment, the textured surface 32 has a specific shape, which improves the ease of wiping off dirt while still providing a sufficient matte effect. The shape of this textured surface 32 will be described later.

[0017] An example of a decorative sheet 10 having such a matte layer 30 will be described below with reference to FIG. 1. FIG. 1 shows a cross section of an example of the decorative sheet 10. In the illustrated example, the decorative sheet 10 has a substrate 12, a design layer 20, an adhesive layer 14, a transparent resin layer 16, a primer layer 18, and a matte layer 30, in that order. Note that none of the substrate 12, design layer 20, adhesive layer 14, transparent resin layer 16, and primer layer 18 are essential components of the decorative sheet 10. The decorative sheet 10 may not have one or more of the substrate 12, design layer 20, adhesive layer 14, transparent resin layer 16, and primer layer 18. The decorative sheet 10 may also have other components (layers) intended to perform specific functions.

[0018] The substrate 12 has a function of supporting the matte layer 30. In particular, in this embodiment, the substrate 12 supports the design layer 20, the adhesive layer 14, the transparent resin layer 16, the primer layer 18, and the matte layer 30. The substrate 12 is disposed facing the back surface 34 of the matte layer 30. The substrate 12 may be a film-like member. The thickness of the substrate 12 may be 10 μm or more and 1 mm or less. Preferably, the thickness of the substrate 12 may be 20 μm or more and 300 μm or less.

[0019] The substrate 12 may be made of, for example, a resin material, a metal material, or a fibrous material. The resin material may be, for example, a polyester resin such as polyethylene terephthalate, an olefin resin such as polyethylene or polypropylene, a vinyl chloride resin such as polyvinyl chloride, or an acrylic resin. The metal material may be, for example, aluminum, iron, copper, gold, silver, chromium, nickel, cobalt, tin, titanium, or an alloy thereof. The fibrous material may be, for example, paper, woven fabric, nonwoven fabric, or a resin-impregnated material thereof. The substrate 12 may include only one layer made of these materials. Alternatively, the substrate 12 may include multiple layers made of these materials. When the substrate 12 includes multiple layers, the multiple layers may be made of different materials.

[0020] The design layer 20 has the function of displaying a design that should be visible to an observer observing the decorative sheet 10. This design may be, for example, a picture, photograph, figure, pattern, mark, letter, color, or other pattern. The design layer 20 may also display a monochrome color pattern as a design. The design layer 20 is disposed facing the back surface 34 of the matte layer 30. In this embodiment, the design layer 20 is disposed between the substrate 12 and the matte layer 30. The thickness of the design layer 20 may be 0.5 μm or more and 20 μm or less. Preferably, the thickness of the design layer 20 may be 1 μm or more and 10 μm or less. More preferably, the thickness of the design layer 20 may be 2 μm or more and 5 μm or less.

[0021] The design layer 20 may include a coloring layer 22 and a pattern layer 24. The coloring layer 22 is a layer that imparts a desired color to the entire surface of the substrate 12. The coloring layer 22 may be a so-called solid layer. The coloring layer 22 may have a single color. Alternatively, the coloring layer 22 may have a pattern composed of multiple colors. The pattern layer 24 is a layer that constitutes the design to be displayed by the design layer 20. The coloring layer 22 and the pattern layer 24 may each be formed by coating, printing, or the like using ink. For example, an ink containing a binder resin and a colorant such as a pigment or dye may be used. Note that the design layer 20 may have only either the coloring layer 22 or the pattern layer 24. That is, the design layer 20 may have only the coloring layer 22 or only the pattern layer 24.

[0022] The transparent resin layer 16 functions to protect the design layer 20. The transparent resin layer 16 also functions to increase the strength of the decorative sheet 10. The transparent resin layer 16 is disposed facing the back surface 34 of the matte layer 30. In this embodiment, the transparent resin layer 16 is disposed between the design layer 20 and the matte layer 30. The transparent resin layer 16 is formed of a transparent resin material. Examples of the resin material include polyolefin resin, polyester resin, polycarbonate resin, acrylonitrile-butadiene-styrene resin (ABS resin), acrylic resin, and vinyl chloride resin. The transparent resin layer 16 may contain additives such as weathering agents, ultraviolet absorbers, light stabilizers, and colorants. The thickness of the transparent resin layer 16 may be 20 μm or more and 150 μm or less. Preferably, the thickness of the transparent resin layer 16 may be 40 μm or more and 120 μm or less. More preferably, the thickness of the transparent resin layer 16 may be 60 μm or more and 100 μm or less.

[0023] As used herein, "transparent" means that the visible light transmittance is 50% or more, preferably 80% or more. The visible light transmittance is determined as the average value of the total light transmittance at each wavelength measured in 1-nm increments within the measurement wavelength range of 380 nm to 780 nm using a spectrophotometer (Shimadzu Corporation's "UV-3100PC," compliant with JIS K0115). "Transparent" also includes colorless transparency and colored transparency.

[0024] The adhesive layer 14 functions to bond the design layer 20 and the transparent resin layer 16 together. If the decorative sheet 10 does not have the design layer 20, the adhesive layer 14 may bond the substrate 12 and the transparent resin layer 16 together. The adhesive layer 14 may be made of, for example, a urethane adhesive, an acrylic adhesive, an epoxy adhesive, or a rubber adhesive. The thickness of the adhesive layer 14 may be 0.1 μm or more and 30 μm or less. Preferably, the thickness of the adhesive layer 14 may be 1 μm or more and 15 μm or less. More preferably, the thickness of the adhesive layer 14 may be 2 μm or more and 10 μm or less.

[0025] The primer layer 18 functions to improve adhesion between the transparent resin layer 16 and the matte layer 30. The primer layer 18 is formed, for example, from a resin material. The resin material may be a resin such as a urethane resin, an acrylic polyol resin, an acrylic resin, an ester resin, an amide resin, a butyral resin, a styrene resin, a urethane-acrylic copolymer, a polycarbonate-based urethane-acrylic copolymer, a vinyl chloride-vinyl acetate copolymer resin, a vinyl chloride-vinyl acetate-acrylic copolymer resin, a chlorinated propylene resin, a nitrocellulose resin, or a cellulose acetate resin. The primer layer 18 may contain additives such as an ultraviolet absorber or a light stabilizer, as needed. The thickness of the primer layer 18 may be 0.1 μm or more and 10 μm or less. Preferably, the thickness of the primer layer 18 may be 1 μm or more and 8 μm or less. More preferably, the thickness of the primer layer 18 may be 2 μm or more and 6 μm or less.

[0026] The matte layer 30 is a layer that provides a matte effect on the surface of the decorative sheet 10. The matte layer 30 has an uneven surface 32 provided on its surface. If the decorative sheet 10 has a substrate 12, the uneven surface 32 faces away from the substrate 12. The uneven surface 32 is a so-called matte surface. Light incident on the matte layer 30 is diffused by the uneven surface 32. This reduces the gloss on the surface of the matte layer 30. In other words, the matte effect is provided by the matte layer 30. In this embodiment, the matte layer 30 includes a resin layer 36 and a plurality of particles 38. The resin layer 36 constitutes the main body of the matte layer 30. The uneven surface 32 is formed on the surface of the resin layer 36. In other words, the resin layer 36 has the uneven surface 32. The uneven surface 32 has a wrinkled structure. The plurality of particles 38 function as a wrinkle-forming agent that imparts a specific wrinkled structure to the uneven surface 32.

[0027] The wrinkle structure is a structure including a streak-like uneven structure (see FIGS. 2 to 10). In particular, the wrinkle structure of this embodiment includes streak-like protrusions and / or streak-like recesses. The streak-like protrusions and / or streak-like recesses have irregular shapes and are irregularly arranged in a planar view. The wrinkle structure may include a plurality of curved streak-like protrusions and a recess formed by being surrounded by the plurality of protrusions. The wrinkle structure may also include a plurality of curved streak-like recesses and a protrusion formed by being surrounded by the plurality of recesses. "Curved" means that, in a planar view, the direction of extension of one streak-like protrusion or recess has an inverted portion where it is reversed from one side to the other. The wrinkle structure may include meandering streak-like protrusions and a recess formed by being surrounded by the meandering streak-like protrusions. The wrinkle structure may also include meandering streak-like recesses and a protrusion formed by being surrounded by the meandering streak-like recesses. "Meandering" means that, in a planar view, one streak-like convex or concave portion includes two or more inverted portions, and the extension directions of the convex or concave portions are reversed in opposite directions in two adjacent inverted portions of one convex or concave portion.

[0028] The convex portions and concave portions in the wrinkle structure may be distinguished from each other, for example, by utilizing the difference in brightness of the image of the surface of the decorative sheet 10. For example, the darkest portion in the density distribution image of the surface of the decorative sheet 10 is designated as gradation 255, and the lightest portion in the density distribution image is designated as gradation 0, and the density of the density distribution image is divided into gradations 0 to 255. Of these, gradations 0 to 127 may be designated as concave portions, and gradations 128 to 255 may be designated as convex portions by binarization processing. The gradation threshold for distinguishing between concave portions and convex portions can be set arbitrarily.

[0029] The thickness of the matte layer 30 may be 1 μm or more. Preferably, the thickness of the matte layer 30 may be 2 μm or more. More preferably, the thickness of the matte layer 30 may be 3 μm or more. Even more preferably, the thickness of the matte layer 30 may be 4 μm or more. Alternatively, the thickness of the matte layer 30 may be 300 μm or less. Preferably, the thickness of the matte layer 30 may be 200 μm or less. More preferably, the thickness of the matte layer 30 may be 100 μm or less. Even more preferably, the thickness of the matte layer 30 may be 50 μm or less. In this embodiment, the thickness of the matte layer 30 refers to the thickness of the matte layer 30 excluding the particles 38. In other words, the thickness of the matte layer 30 is the thickness of the resin layer 36. The thickness of the resin layer 36 is determined by measuring the thickness at 20 points on an image of a cross section parallel to the normal direction of the resin layer 36 taken using a scanning electron microscope (SEM), and calculating the arithmetic mean of the thickness values ​​at the 20 points. The acceleration voltage of the SEM is set to 3 kV, and the magnification is set according to the thickness. The same applies to the thicknesses of the other layers.

[0030] The textured surface 32 is required to fully exhibit a matte effect on the surface of the decorative sheet 10. At the same time, the surface of the decorative sheet 10 is required to have good wiping properties. However, in the past, decorative sheets with a wrinkled surface have made it difficult to remove dirt adhering to the decorative sheet due to the wrinkled structure. In particular, when the dirt contains highly viscous contaminants such as crayon, shoe polish, or lipstick, the contaminants may spread when wiping. Therefore, removing highly viscous contaminants has been particularly difficult. Therefore, there have been no decorative sheets with a wrinkled surface that have achieved good wiping properties for highly viscous contaminants.

[0031] The present inventors have conducted extensive research into the wiping ability of a decorative sheet having a wrinkled surface to remove viscous contaminants, and have found that imparting a specific shape to the surface (uneven surface 32) of the matte layer 30 improves the wiping ability of contaminants from the surface of the decorative sheet 10. In particular, they have found that by setting the gloss value and the average length RSm defined in JIS B0601:2013 of the uneven surface 32 to values ​​within a specific range, the matte layer 30 can fully exhibit its matting effect while effectively improving the wiping ability of the surface (uneven surface 32) of the matte layer 30 to remove viscous contaminants. The shape of the uneven surface 32 in this embodiment will now be described.

[0032] The 60° specular gloss of the uneven surface 32, as defined in JIS Z8741:1997, is 5 or less. By having the 60° specular gloss of the uneven surface 32 be 5 or less, the uneven surface 32 can exhibit a sufficient matte effect. The 60° specular gloss of the uneven surface 32 may be 2 or more. Furthermore, the 85° specular gloss of the uneven surface 32, as defined in JIS Z8741:1997, may be 30 or less. By having the 85° specular gloss of the uneven surface 32 be 30 or less, the uneven surface 32 can exhibit a more sufficient matte effect. The 85° specular gloss of the uneven surface 32 may be 10 or more. Surfaces that feel rough to the touch tend to have low 60° specular gloss as well as low 85° specular gloss. An uneven surface 32 with an 85° specular gloss of 10 or more feels smooth to the touch. Therefore, when the 85° specular gloss of the textured surface 32 is 10 or more, the textured surface 32 has a good feel to the touch. The 60° specular gloss and the 85° specular gloss can be measured using, for example, a micro-gloss gloss meter manufactured by BYK-Gardner.

[0033] The mean length RSm of the uneven surface 32, as defined in JIS B0601:2013, is 25 μm or more and 35 μm or less. The mean length RSm can be measured using a Keyence laser microscope (model number: VK-X100). The mean length (mean length of curved elements) RSm is a horizontal parameter of the profile curve and is the average length of the profile curve elements in the reference length. The smaller the mean length RSm, the narrower the width of the convex and concave portions, indicating that the surface shape tends to have narrower convex and concave portions.

[0034] When highly viscous contaminants such as crayons, shoe polish, and lipstick penetrate into the recesses of the textured surface 32, they adhere firmly to the textured surface 32. Therefore, with conventional decorative sheets, it has been difficult to remove highly viscous contaminants from the textured surface 32. In this embodiment, the average length RSm of the textured surface 32 is 25 μm or more, thereby increasing the dimension of the recesses of the textured surface 32 in the direction along the sheet surface of the matte layer 30. This makes it easier for a wiping member such as a cloth or tissue paper to penetrate into the recesses of the textured surface 32. Therefore, highly viscous contaminants that have penetrated into the recesses of the textured surface 32 are easily removed by the wiping member. Preferably, the average length RSm of the textured surface 32 may be 25.5 μm or more. More preferably, the average length RSm may be 26 μm or more. Note that the cutoff value for measuring the average length RSm in this specification is 0.8 mm.

[0035] Furthermore, in this embodiment, by setting the average length RSm of the uneven surface 32 to 35 μm or less, the wrinkle structure of the uneven surface 32 is prevented from becoming coarse. Therefore, the glossiness of the uneven surface 32 can be sufficiently prevented from increasing. In other words, the uneven surface 32 exhibits a sufficient matte effect. Preferably, the average length RSm of the uneven surface 32 may be 34 μm or less. More preferably, the average length RSm may be 33 μm or less.

[0036] The maximum height Rz of the uneven surface 32 may be 3 μm or more and 7 μm or less. The maximum height Rz can be measured in accordance with JIS B0601:2013. The maximum height Rz can be measured, for example, using a laser microscope (model number: VK-X100) manufactured by Keyence Corporation. The maximum height Rz is one of the peak and height parameters of a profile curve, and is the sum of the height of the highest peak and the depth of the deepest valley in the profile curve over a reference length. The larger the maximum height Rz, the more valleys with greater depths as viewed from the peaks of the peaks are present, and the more such valleys tend to be present. By having the maximum height Rz be 7 μm or less, contaminants that have entered the recesses of the uneven surface 32 are more easily removed. Furthermore, by having the maximum height Rz be 3 μm or more, the glossiness of the uneven surface 32 can be further suppressed. In other words, the uneven surface 32 exhibits a more matte effect. Note that the cutoff value for measuring the maximum height Rz in this specification is 0.8 mm.

[0037] The resin layer 36 includes a resin composition. The resin composition used for the resin layer 36 may include an ionizing radiation-curable resin. The ionizing radiation-curable resin is a resin having an ionizing radiation-curable functional group. The ionizing radiation-curable functional group is a group that crosslinks upon irradiation with ionizing radiation. The ionizing radiation-curable functional group may be, for example, a functional group having an ethylenic double bond, such as a (meth)acryloyl group, a vinyl group, or an allyl group. In this specification, a (meth)acryloyl group refers to an acryloyl group or a methcroyl group. In this specification, a (meth)acrylate refers to an acrylate or a methacrylate. In addition, ionizing radiation refers to electromagnetic waves or charged particle beams that have an energy quantum capable of polymerizing and / or crosslinking molecules. Examples of ionizing radiation include electromagnetic waves such as ultraviolet (UV) rays, electron beams (EB), X-rays, and gamma rays, as well as charged particle beams such as alpha rays and ion beams.

[0038] The ionizing radiation curable resin may be an electron beam curable resin or an ultraviolet ray curable resin. The ionizing radiation curable resin may be appropriately selected from polymerizable monomers and polymerizable oligomers that have been conventionally used as ionizing radiation curable resins.

[0039] The polymerizable monomer is preferably a (meth)acrylate-based monomer having a radically polymerizable unsaturated group in the molecule. In particular, the polymerizable monomer is preferably a polyfunctional (meth)acrylate monomer. The polyfunctional (meth)acrylate monomer may be a (meth)acrylate monomer having two or more ionizing radiation-curable functional groups in the molecule, and having at least a (meth)acryloyl group as the functional group. The number of functional groups in the polyfunctional (meth)acrylate monomer may be 2 or more and 8 or less. Preferably, the number of functional groups in the polyfunctional (meth)acrylate monomer may be 2 or more and 6 or less. These polyfunctional (meth)acrylates may be used alone or in combination of two or more.

[0040] The polymerizable oligomer may be, for example, a (meth)acrylate oligomer having two or more ionizing radiation-curable functional groups in the molecule and having at least a (meth)acryloyl group as the functional group. The polymerizable oligomer may be, for example, a urethane (meth)acrylate oligomer, an epoxy (meth)acrylate oligomer, a polyester (meth)acrylate oligomer, a polyether (meth)acrylate oligomer, a polycarbonate (meth)acrylate oligomer, an acrylic (meth)acrylate oligomer, etc. Furthermore, the polymerizable oligomer may also be a highly hydrophobic polybutadiene (meth)acrylate oligomer having a (meth)acrylate group in the side chain of a polybutadiene oligomer, a silicone (meth)acrylate oligomer having a polysiloxane bond in the main chain, an aminoplast resin (meth)acrylate oligomer obtained by modifying an aminoplast resin having many reactive groups in a small molecule, or an oligomer having a cationically polymerizable functional group in the molecule, such as a novolac epoxy resin, a bisphenol epoxy resin, an aliphatic vinyl ether, or an aromatic vinyl ether.

[0041] These polymerizable oligomers may be used alone or in combination of two or more. The polymerizable oligomer may be a urethane (meth)acrylate oligomer, an epoxy (meth)acrylate oligomer, a polyester (meth)acrylate oligomer, a polyether (meth)acrylate oligomer, a polycarbonate (meth)acrylate oligomer, or an acrylic (meth)acrylate oligomer. Preferably, the polymerizable oligomer may be a urethane (meth)acrylate oligomer or a polycarbonate (meth)acrylate oligomer. More preferably, the polymerizable oligomer may be a urethane (meth)acrylate oligomer.

[0042] The number of functional groups of these polymerizable oligomers may be 2 or more and 8 or less. Preferably, the number of functional groups of the polymerizable oligomers may be 2 or more and 6 or less. The weight average molecular weight of the polymerizable oligomers may be 2500 or more and 7500 or less. Preferably, the weight average molecular weight of the polymerizable oligomers may be 3000 or more and 7000 or less. More preferably, the weight average molecular weight of the polymerizable oligomers may be 3500 or more and 6000 or less. Here, the weight average molecular weight is an average molecular weight measured by GPC analysis and converted into standard polystyrene.

[0043] In the present embodiment, a combination of a polymerizable oligomer and a polymerizable monomer may be used as the resin forming the resin layer 36. The polymerizable oligomer may be a polyfunctional urethane (meth)acrylate oligomer. Preferably, the polymerizable oligomer may be a polyfunctional urethane acrylate oligomer. The polymerizable monomer may be a polyfunctional polymerizable monomer. Preferably, the polymerizable monomer may be a polyfunctional (meth)acrylate monomer. More preferably, the polymerizable monomer may be a polyfunctional acrylate monomer. When a combination of a polymerizable oligomer and a polymerizable monomer is used, the content of the polymerizable oligomer may be 40 parts by mass or more relative to 100 parts by mass of the total of the polymerizable oligomer and the polymerizable monomer. Preferably, the content of the polymerizable oligomer may be 50 parts by mass or more. More preferably, the content of the polymerizable oligomer may be 60 parts by mass or more. More preferably, the content of the polymerizable oligomer may be 70 parts by mass or more. More preferably, the content of the polymerizable oligomer may be 80 parts by mass or more. The content of the polymerizable oligomer may be 98 parts by mass or less. Preferably, the content of the polymerizable oligomer may be 95 parts by mass or less. More preferably, the content of the polymerizable oligomer may be 92 parts by mass or less.

[0044] The resin composition used in the resin layer 36 may contain other components in addition to the above-mentioned resins depending on the desired performance, etc. For example, the resin composition used in the resin layer 36 may contain a monofunctional (meth)acrylate for the purpose of reducing its viscosity, etc. These monofunctional (meth)acrylates may be used alone or in combination of two or more types.

[0045] Furthermore, when the resin is an ultraviolet-curable resin that is cured by ultraviolet light, it may contain additives such as a photopolymerization initiator and a photopolymerization accelerator. As the photopolymerization initiator, for example, one or more selected from acetophenone, benzophenone, α-hydroxyalkylphenone, Michler's ketone, benzoin, benzyl dimethyl ketal, benzoyl benzoate, α-acyloxime ester, thioxanthones, etc. may be used. The photopolymerization accelerator can reduce polymerization inhibition by air during curing and increase the curing rate. As the photopolymerization accelerator, for example, one or more selected from p-dimethylaminobenzoic acid isoamyl ester, p-dimethylaminobenzoic acid ethyl ester, etc. may be used.

[0046] Particles 38 function as a wrinkle-forming agent for imparting a specific wrinkled structure to textured surface 32. In conventional techniques for forming a wrinkled textured surface on a resin surface using excimer light or the like, it was difficult to precisely control the shape of the wrinkled structure of the textured surface. After extensive research into this issue, the present inventors found that the shape of the wrinkled structure of textured surface 32 can be controlled by further adding particles 38 to the resin composition for forming matte layer 30.

[0047] A technique for forming a matte layer by adding particles such as silica to a resin layer without a wrinkled structure has been known. In this technique, particles protruding from the surface of the resin layer form irregularities on the surface, which provide a matte effect. In contrast, in the present embodiment, the irregularities on the irregular surface 32 are realized by the wrinkled structure. The particles 38 of this embodiment are not intended to form the irregularities on the irregular surface 32 by themselves. In this respect, the particles 38 of this embodiment are essentially different from particles added to a resin layer without a wrinkled structure. The present inventors speculate that when a resin composition is irradiated with excimer light or the like, as in the manufacturing method described below, the particles 38 act as the starting point for the formation of the convex and / or concave portions that constitute the wrinkled structure. This is believed to make it possible to impart a shape to the wrinkled structure that was difficult to achieve using conventional techniques. In this embodiment, the inclusion of particles 38 in the matte layer 30 enables the average length RSm on the irregular surface 32 to be 25 μm or more and 35 μm or less. The following describes such particles 38.

[0048] The particles 38 may be, for example, organic particles or inorganic particles. Examples of organic materials that may be used for the organic particles include polymethyl methacrylate, acrylic-styrene copolymer resin, melamine resin, polycarbonate, polystyrene, polyvinyl chloride resin, benzoguanamine-melamine-formaldehyde condensate, silicone, fluorine-based resin, and polyester-based resin. Examples of inorganic materials that may be used for the inorganic particles include silica, alumina, calcium carbonate, aluminosilicate, and barium sulfate. Among these, silica is preferably used for the inorganic particles. The shape of the particles 38 may be, for example, spherical, polyhedral, scaly, or irregular.

[0049] The average particle diameter of particles 38 may be 1 μm or more. Preferably, the average particle diameter of particles 38 may be 1.3 μm or more. More preferably, the average particle diameter of particles 38 may be 1.5 μm or more. Even more preferably, the average particle diameter of particles 38 may be 1.8 μm or more. The average particle diameter of particles 38 may be 20 μm or less. Preferably, the average particle diameter of particles 38 may be 15 μm or less. Even more preferably, the average particle diameter of particles 38 may be 10 μm or less. In this specification, the average particle diameter of particles 38 is measured as the mass average value d50 in particle size distribution measurement by laser light diffraction method.

[0050] The plurality of particles 38 may include particles 38 having a maximum dimension equal to or greater than half the thickness of the resin layer 36. The inventors of the present invention have found through their studies that the shape of the wrinkle structure of the uneven surface 32 can be more appropriately controlled when the plurality of particles 38 include particles 38 having a maximum dimension equal to or greater than half the thickness of the resin layer 36. Preferably, the plurality of particles 38 may include particles 38 having a maximum dimension equal to or greater than the thickness of the resin layer 36.

[0051] The maximum dimension of particle 38 is measured in a cross section of particle 38 observed in a cross section parallel to the normal direction of matte layer 30. The length of the longest straight line that intersects particle 38 in the cross section of particle 38 is the maximum dimension of particle 38. By measuring the maximum dimension of particle 38 in this manner, the maximum dimension of particle 38 contained in matte layer 30 can be easily measured. Note that, depending on the position of the cross section of particle 38, the maximum dimension of particle 38 measured as described above may differ from the true maximum dimension of particle 38. However, the maximum dimension of particle 38 measured as described above will never be larger than the true maximum dimension of particle 38. Therefore, it can be assumed that the true maximum dimension of particle 38 is equal to or larger than the maximum dimension of particle 38 measured as described above.

[0052] The content of particles 38 may be 0.5 parts by mass or more relative to 100 parts by mass of the resin forming resin layer 36. Preferably, the content of particles 38 may be 0.75 parts by mass or more. More preferably, the content of particles 38 may be 1.0 part by mass or more. Even more preferably, the content of particles 38 may be 1.2 parts by mass or more. The content of particles 38 may be 25.0 parts by mass or less relative to 100 parts by mass of the resin forming resin layer 36. Preferably, the content of particles 38 may be 15.0 parts by mass or less. Even more preferably, the content of particles 38 may be 10.0 parts by mass or less. Even more preferably, the content of particles 38 may be 7.5 parts by mass or less. Even more preferably, the content of particles 38 may be 6.0 parts by mass or less.

[0053] Next, an example of a method for manufacturing the decorative sheet 10 of this embodiment will be described. First, a laminate of the substrate 12, the design layer 20, the adhesive layer 14, the transparent resin layer 16, and the primer layer 18 is prepared. Next, a mixture of particles 38 and a resin composition that will later become the resin layer 36 is placed on the primer layer 18 of this laminate. The mixture may be applied to the primer layer 18 in a fluid state, for example. The mixture may be applied by gravure printing, bar coating, roll coating, reverse roll coating, comma coating, or the like. Alternatively, the mixture may be formed into a sheet and then attached to the primer layer 18.

[0054] Next, the resin composition is irradiated with light having a wavelength of more than 380 nm to pre-cure the entire resin composition. Preferably, the wavelength of this light may be 385 nm or more and 400 nm or less. Note that this pre-cure step is not an essential step and may be omitted.

[0055] The surface of the resin composition is then irradiated with light having a wavelength of 100 nm or more and 380 nm or less. This forms a wrinkled structure on the surface of the resin composition. The mechanism by which this wrinkled structure is formed is presumed to be as follows. When the surface of the resin composition is irradiated with light having a wavelength of 100 nm or more and 380 nm or less, the light energy penetrates only the surface portion due to the short wavelength of the light, and the light energy does not reach the layers below. At this time, only the surface portion of the resin composition begins to harden. As a result, only the surface undergoes cure shrinkage, and a wrinkled structure is formed on the surface of the resin composition. It is believed that only the portion of the resin composition within a certain thickness from the surface is in a hardened state. Furthermore, it is believed that at this time, particles 38 function like a nucleus that triggers the formation of the wrinkled structure. Therefore, it is presumed that the resin on the surface portion of the resin composition gathers around particles 38, forming the convex and concave portions of the wrinkled structure.

[0056] Examples of light having a wavelength of 100 nm or more and 380 nm or less include "excimer light," which includes light in the ultraviolet wavelength range from excited dimers, i.e., excimers, formed by discharge of rare gases such as Ar, Kr, Xe, and Ne, halides of rare gases such as halogens F, Cl, I, and Br, or mixed gases thereof. The wavelength and source of the excimer light may be, for example, 126 nm light emitted from the excimer of Ar (hereinafter abbreviated as "126 nm (Ar)"), 146 nm (Kr), 157 nm (F), 172 nm (Xe), 193 nm (ArF), 222 nm (KrCl), 247 nm (KrF), 308 nm (XeCl), or 351 nm (XeF). The excimer light may be spontaneous emission light or highly coherent laser light due to stimulated emission. Discharge lamps that emit such light are also called "excimer lamps." Excimer light has a single wavelength peak and a narrower half-width wavelength than ordinary ultraviolet light (e.g., ultraviolet light emitted from metal halide lamps, mercury lamps, etc.). Using such excimer light stabilizes wrinkle formation and improves the matte effect stably.

[0057] The wavelength of the light irradiated onto the surface of the resin composition may be 120 nm or more. Preferably, the wavelength of the light may be 140 nm or more. More preferably, the wavelength of the light may be 150 nm or more. Even more preferably, the wavelength of the light may be 155 nm or more. The wavelength of the light irradiated onto the surface of the resin composition may be 320 nm or less. Preferably, the wavelength of the light may be 300 nm or less. Even more preferably, the wavelength of the light may be 250 nm or less. Even more preferably, the wavelength of the light may be 200 nm or less. Even more preferably, the wavelength of the light may be 172 nm (Xe2).

[0058] The cumulative exposure dose of light irradiated onto the surface of the resin composition is 1 mJ / cm 2 Preferably, the cumulative exposure dose is 10 mJ / cm or more. 2 More preferably, the cumulative exposure dose is 30 mJ / cm. 2 More preferably, the cumulative exposure dose is 50 mJ / cm. 2 The cumulative exposure dose of light irradiated onto the surface of the resin composition may be 1000 mJ / cm or more. 2 Preferably, the cumulative exposure dose is 500 mJ / cm or less. 2 More preferably, the cumulative exposure dose is 300 mJ / cm 2 It may be the following:

[0059] The power density of the light irradiated onto the surface of the resin composition may be 0.001 W / cm or more. Preferably, the power density may be 0.01 W / cm or more. More preferably, the power density may be 0.03 W / cm or more. The power density of the light irradiated onto the surface of the resin composition may be 10 W / cm or less. Preferably, the power density may be 5 W / cm or less. More preferably, the power density may be 3 W / cm or less.

[0060] The oxygen concentration when irradiating the surface of the resin composition with light may be 1000 ppm or less. Preferably, the oxygen concentration may be 750 ppm or less. More preferably, the oxygen concentration may be 500 ppm or less. Still more preferably, the oxygen concentration may be 300 ppm or less.

[0061] As described above, the surface of the resin composition is irradiated with light having a wavelength of 100 nm or more and 380 nm or less, and then the resin composition is irradiated with light having a wavelength longer than the wavelength of the light irradiated with the light. This causes curing to proceed in the depthwise distant portion of the resin composition from the surface, resulting in the entire resin composition being cured. At this time, the formation of a wrinkle structure further progresses due to the difference in the degree of curing progress between the surface portion of the resin composition and the depthwise distant portion of the resin composition. For example, ultraviolet (UV) light may be used as the light used to completely cure the resin composition. Furthermore, other ionizing radiation, such as an electron beam (EB), may be used instead of ultraviolet light to completely cure the resin composition.

[0062] The decorative sheet 10 of this embodiment comprises a matte layer 30 having an uneven surface 32, the matte layer 30 comprising a resin layer and a plurality of particles, the uneven surface 32 having a wrinkled structure, the 60° specular gloss of the uneven surface 32 as defined in JIS Z8741:1997 being 5 or less, and the average length RSm of the uneven surface 32 as defined in JIS B0601:2013 being 25 μm or more and 35 μm or less.

[0063] When highly viscous contaminants such as crayon, shoe polish, and lipstick find their way into the recesses of the textured surface 32, they adhere firmly to the textured surface 32. Therefore, with conventional decorative sheets, it has been difficult to remove highly viscous contaminants from the textured surface 32. According to the decorative sheet 10 of this embodiment, the average length RSm of the textured surface 32 is 25 μm or more, so that the dimensions of the recesses of the textured surface 32 in the direction along the sheet surface of the matte layer 30 are large. This makes it easier for a wiping member such as cloth or tissue paper to find its way into the recesses of the textured surface 32. Therefore, highly viscous contaminants that have found their way into the recesses of the textured surface 32 can be easily removed by the wiping member.

[0064] Furthermore, according to the decorative sheet 10 of this embodiment, the average length RSm on the uneven surface 32 is 35 μm or less, which prevents the wrinkle structure of the uneven surface 32 from becoming coarse. Therefore, the glossiness of the uneven surface 32 can be sufficiently prevented from increasing. In other words, the uneven surface 32 can fully exhibit a matte effect. Furthermore, according to the decorative sheet 10 of this embodiment, the glossiness of the uneven surface 32 is 5 or less, which allows the uneven surface 32 to further fully exhibit a matte effect.

[0065] An example of an experiment conducted by the present inventors will be described below. Note that the embodiments of the present disclosure are not limited to the results of the following experiment.

[0066] Samples 1 to 5 were prepared under the following conditions. Photographs of the matte layer surface were taken for each sample. Figures 2 to 6 are photographs of the matte layer surface for each sample. Furthermore, the gloss and surface roughness (average length RSm and maximum height Rz) of each sample were measured. Furthermore, the wiping properties of each sample were evaluated. Table 1 shows the conditions for each sample, the measured gloss, maximum height Rz, and average length RSm values, the wiping properties evaluation, and the drawing number of the corresponding surface photograph.

[0067] Sample 1 50 parts by mass of a polyfunctional oligomer (average number of functional groups: 3) and 50 parts by mass of a bifunctional monomer were mixed, and 3 parts by mass of a photopolymerization initiator was added to the mixture to obtain a resin composition. 3 parts by mass of particles A were added to this resin composition to obtain an energy beam-curable ink. Particles A are silica particles with an average particle diameter of 5 μm. Particles A are intended to exhibit the same effect as particles 38 in the above-described embodiment. That is, particles A in Sample 1 are intended to serve as starting points for forming the convex and / or concave portions that constitute the wrinkle structure. Therefore, particles A in Sample 1 are not intended to form the convex and concave portions on the convex and concave surface by themselves. Therefore, the amount of particles A added in Sample 1 is smaller than the amount of particles B added in Sample 4 described below. A 3 μm thick white pattern layer and a 2 μm thick two-component curable primer layer were formed on one side of a 60 μm thick polypropylene sheet that had been subjected to corona discharge treatment. The above energy ray curable ink was applied to the primer layer and dried. The amount of the energy ray curable ink applied was 5 g / m. 2 (when dry). The energy beam curable ink was irradiated with ultraviolet light from a UV-LED light source with a wavelength of 395 nm to pre-cure the resin composition. The output was 0.6 W / cm. 2 , cumulative exposure dose 30mJ / cm 2 It was. Next, the energy ray-curable ink was irradiated with excimer light from an excimer lamp with a wavelength of 172 nm to cure the surface of the resin composition. The output was 30 mW / cm. 2 , the cumulative exposure is 6 mJ / cm 2 It was. Thereafter, the energy ray-curable ink was irradiated with ultraviolet light from a high-pressure mercury lamp with a wavelength of 365 nm to cure the entire resin composition, thereby obtaining a matte layer from the energy ray-curable ink. The output was 200 W / cm. 2 , the cumulative exposure is 400mJ / cm 2 After curing, an uneven surface having a wrinkled structure was formed on the surface of the matte layer.

[0068] Sample 2 The resin ratio was 40 parts by mass of polyfunctional oligomer (average number of functional groups: 3) and 60 parts by mass of difunctional oligomer, but the other components were the same as those in Sample 1. After curing, an uneven surface with a wrinkled structure was formed on the surface of the matte layer.

[0069] Sample 3 The resin ratio was changed to 30 parts by mass of polyfunctional oligomer (average number of functional groups: 3), 30 parts by mass of difunctional monomer, and 40 parts by mass of monofunctional monomer, the amount of particles A was changed to 2 parts by mass, and the amount of photopolymerization initiator was changed to 0.5 parts by mass, but the same as Sample 1. After curing, an uneven surface with a wrinkled structure was formed on the surface of the matte layer.

[0070] Sample 4 A resin composition was prepared by mixing 65 parts by mass of a polyfunctional oligomer (average number of functional groups: 3) and 35 parts by mass of a bifunctional monomer, to which 0.5 parts by mass of a photopolymerization initiator was added. 30 parts by mass of particles B were added to this resin composition to prepare an energy beam-curable ink. Particles B are silica particles with an average particle diameter of 4 μm. Particles B themselves are intended to form the irregularities on the irregular surface. Therefore, the amount of particles B added in Sample 4 is greater than the amount of particles A added in Samples 1 to 3 and 5. The energy ray-curable ink was irradiated with ultraviolet light from a high-pressure mercury lamp to cure the entire resin composition, thereby obtaining a matte layer from the energy ray-curable ink. The output was 200 W / cm. 2 , the cumulative exposure is 400mJ / cm 2 After curing, an uneven surface was formed on the surface of the matte layer due to the presence of particles B. That is, convex portions were formed in the areas where particles B were present, and as a result, an uneven surface was formed on the surface of the matte layer. On the other hand, an uneven surface with a wrinkled structure was not formed on the surface of the matte layer.

[0071] Sample 5 The procedure was the same as Sample 2, except that no UV-LED light source was used during curing, and the cumulative exposure of ultraviolet light from the excimer light and high-pressure mercury lamp was reduced to 1.5. After curing, an uneven surface with a wrinkled structure was formed on the surface of the matte layer.

[0072] In Table 1, "60°" in the "Gloss" column indicates the 60° specular gloss as defined in JIS Z8741:1997. Similarly, "85°" indicates the 85° specular gloss as defined in JIS Z8741:1997. The 60° specular gloss and 85° specular gloss were measured using a micro-gloss gloss meter manufactured by BYK-Gardner.

[0073] In Table 1, "RSm" in the "Surface Roughness" column indicates the average length RSm as defined in JIS B0601:2013. "Rz" indicates the maximum height Rz as defined in JIS B0601:2013. The average length RSm and maximum height Rz were measured using a Keyence laser microscope (model number: VK-X100). The objective lens magnification was 50x. The average length RSm and maximum height Rz were measured at 20 locations on the matte layer, and the arithmetic mean values ​​were used as the average length RSm and maximum height Rz values ​​for each sample.

[0074] The wiping ability was evaluated using a crayon and shoe polish.

[0075] Wiping evaluation using crayons A red crayon was used as the crayon. The crayon was attached to the sheets of Samples 1 to 5, left to stand for a predetermined time, and then wiped off. First, the crayon was wiped off with a cloth soaked in undiluted household detergent. If the crayon was no longer visible to the naked eye at this stage, the evaluation was rated A. If the crayon was still visible to the naked eye, it was then wiped off with a cloth soaked in disinfectant ethanol. If the crayon was still visible to the naked eye at this stage, the evaluation was rated B. If the crayon was still visible to the naked eye after this stage, the evaluation was rated C.

[0076] Evaluation of wiping ability using shoe polish The evaluation was carried out in the same manner as in the evaluation of wiping properties using crayons, except that black shoe polish was used instead of crayons.

[0077] [Table 1]

[0078] As shown in Table 1, Sample 4 was evaluated as B in both the wiping performance evaluation using a crayon and the wiping performance evaluation using shoe polish. This shows that Sample 4, whose textured surface does not have a wrinkled structure, does not have good wiping performance.

[0079] Of Samples 1 to 3 and 5, whose textured surfaces have a wrinkled structure, Samples 1 to 3, which have a 60° specular gloss of 5 or less, exhibit a sufficient matting effect. Furthermore, of Samples 1 to 3 and 5, Samples 1, 2 and 5, which have an average length RSm of 25 μm or more, were evaluated as A in both the wiping performance evaluation using crayon and the wiping performance evaluation using shoe polish, demonstrating good wiping performance. Furthermore, of Samples 1 to 3 and 5, Samples 1 to 3, which have an average length RSm of 35 μm or less, exhibit a 60° specular gloss of 5 or less, demonstrating a sufficient matting effect.

[0080] Therefore, in this experiment, it was found that in samples 1 and 2, whose uneven surfaces had a wrinkled structure, a 60° specular gloss of 5 or less, and an average length RSm of 25 μm or more and 35 μm or less, the uneven surfaces exhibited a sufficient matting effect and had good wiping properties against highly viscous contaminants such as crayons and shoe polish.

[0081] Although one embodiment has been described with reference to specific examples, the above-described specific examples do not limit the present invention. The above-described embodiment can be implemented with various other specific examples, and various omissions, substitutions, changes, additions, etc. can be made without departing from the spirit of the present invention. [Explanation of symbols]

[0082] 10 Decorative Sheet 12 Base material 14 Adhesive layer 16 Transparent resin layer 18 Primer layer 20 Design Layer 22 Colored layer 24 Picture layer 30 Matte layer 32 Uneven surface 34 Back side 36 Resin layer 38 particles

Claims

[Claim 1] A decorative sheet provided with a matte layer having an uneven surface, the matte layer includes a resin layer and a plurality of particles, the uneven surface has a wrinkled structure, The 60° specular gloss of the uneven surface as defined in JIS Z8741:1997 is 5 or less, The average length RSm of the uneven surface as defined in JIS B0601:2013 is 25 μm or more and 35 μm or less, A decorative sheet, wherein the plurality of particles include particles having a maximum dimension equal to or greater than half the thickness of the resin layer.

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