decorative sheet

Abstract

A decorative sheet (1) comprising a raw fabric layer (2), and a surface-protective layer (5) that is provided to one surface of the raw fabric layer (2). A structure of bumps and dips including a plurality of ridge-form parts each of which protrude in the form of ridges is provided to the surface of the surface-protective layer (5). In a power spectrum obtained by Fourier-transforming the surface shape of a cross-section of the surface-protective layer (5), the power ratio x of the average value logPf500-1000 of a common logarithm of power in a section having a spatial frequency of 500-1000 cycle / mm with respect to the average value logPf3000-3500 of a common logarithm of power in a section having a spatial frequency of 3000-3500 cycle / mm is within the range of 4.0-13.5. The glossiness of the surface-protective layer (5) is less than 10.

Description

[Technical Field]

[0001] This invention relates to a decorative sheet. The decorative sheet can be used, for example, for the interior and exterior finishes of buildings, as well as for the surface finishing of fixtures, furniture, joinery, flooring, etc. [Background technology]

[0002] In recent years, as shown in Patent Document 1, many decorative sheets using olefin resins (e.g., polypropylene sheets) have been proposed as alternatives to decorative sheets made of polyvinyl chloride, which pose environmental protection concerns. These decorative sheets do not use polyvinyl chloride resin, thus suppressing the generation of toxic gases during incineration.

[0003] Decorative sheets are widely used in buildings to add aesthetic appeal and durability to the surface. They are typically bonded to surfaces such as wood, wood-based boards, metal sheets, non-combustible boards, paper substrates, or resin substrates using adhesives to create decorative panels. For aesthetic appeal, various printing methods are used to create patterns such as wood grain or stone patterns, while plain, unpatterned surfaces are selected according to requirements and applications. Similarly, surface gloss is also an important aesthetic element, ranging from high gloss like a mirror to low gloss with no reflection at all, depending on requirements and applications. Another crucial function of decorative sheets, alongside aesthetic appeal, is durability. Durability encompasses scratch resistance, stain resistance, and the long-term sustainability of these properties. Decorative sheets are used as interior building materials for houses and public facilities, exterior building components such as entrance doors, surface materials for joinery, and surface materials for home appliances. Therefore, they are exposed to direct sunlight and rain daily, requiring extremely high weather resistance.

[0004] To provide durability, it is common to form a surface protective layer on the outermost surface of the decorative sheet. Furthermore, to adjust the gloss level, particularly to achieve low gloss, it is common to add a gloss adjuster (matte additive) to the surface protective layer. Thus, a decorative sheet that takes into account aesthetics (low gloss), scratch resistance, and stain resistance is described in Patent Document 2, for example.

[0005] On the other hand, Patent Documents 3 to 7 propose a method for producing low-gloss decorative sheets by forming wrinkles using excimer light with a wavelength of less than 200 nm. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent No. 3271022 [Patent Document 2] Japanese Patent Publication No. 2019-119138 [Patent Document 3] International Publication No. 2021 / 201105 [Patent Document 4] Japanese Patent Application Publication No. 2022-008024 [Patent Document 5] International Publication No. 2022 / 054644 [Patent Document 6] International Publication No. 2022 / 054645 [Patent Document 7] International Publication No. 2022 / 054646 [Overview of the project]

[0007] The present invention aims to provide a decorative sheet that is low-gloss and has a moist texture.

[0008] According to one aspect of the present invention, it includes a base fabric layer and a surface protection layer provided on one surface of the base fabric layer, and an uneven structure including a plurality of ridge-shaped portions each protruding in a ridge shape is provided on the surface of the surface protection layer. The power spectrum obtained by Fourier-transforming the surface shape in the cross-section of the surface protection layer has an average value logPf of the common logarithm of the power in the section where the spatial frequency is 3000 cycles / mm or more and 3500 cycles / mm or less 3000-3500 compared to the average value logPf of the common logarithm of the power in the section where the spatial frequency is 500 cycles / mm or more and 1000 cycles / mm or less, and the power ratio x is in the range of 4.0 to 13.5, and a decorative sheet having a glossiness of less than 10 of the surface protection layer is provided. 500-1000 According to another aspect of the present invention, a decorative sheet according to the above aspect is provided, wherein the surface protection layer contains a cured product of a resin and particles, and the particles are contained in the surface protection layer in an amount of 3 parts by mass or more and 13 parts by mass or less with respect to 100 parts by mass of the resin.

[0009] According to still another aspect of the present invention, a decorative sheet according to any of the above aspects is provided, wherein the resin is a radiation-curable resin.

[0010] According to still another aspect of the present invention, a decorative sheet according to any of the above aspects is provided, wherein the resin is an acrylate.

[0011] According to still another aspect of the present invention, a decorative sheet according to any of the above aspects is provided, wherein the resin is a trifunctional acrylate containing a repeating structure, and the number of repetitions of the repeating structure is 6 or more and 20 or less.

[0012] According to still another aspect of the present invention, a decorative sheet according to any of the above aspects is provided, which further includes a pattern layer between the base fabric layer and the surface protection layer.

[0013] According to still another aspect of the present invention, a decorative material is provided, which includes a decorative sheet according to any of the above aspects and a base material to which the decorative sheet is attached.

[0014] ​

[0015] According to the present invention, it is possible to provide a decorative sheet that is low-gloss and has a moist texture. [Brief explanation of the drawing]

[0016] [Figure 1] Figure 1 is a cross-sectional view of a decorative material including a decorative sheet according to one embodiment of the present invention. [Figure 2] Figure 2 is a cross-sectional view of a decorative material including a decorative sheet according to another embodiment of the present invention. [Figure 3] Figure 3 is a cross-sectional view of the surface protective layer of the decorative sheet shown in Figures 1 and 2. [Figure 4] Figure 4 is a microscopic image of the surface protective layer of a decorative sheet according to an example of the present invention. [Figure 5] Figure 5 is a graph showing the cross-sectional profile of the surface protective layer of a decorative sheet according to an example of the present invention. [Figure 6] Figure 6 is a graph showing the power spectrum obtained by performing a Fourier transform on the cross-sectional profile shown in Figure 5. [Modes for carrying out the invention]

[0017] The configuration of the decorative sheet according to an embodiment of the present invention will be described below with reference to the drawings. The embodiments described below are more specific to any of the above aspects. The matters described below can be incorporated into each of the above aspects, individually or in combination.

[0018] In the drawings referenced below, elements with similar or identical functions are given the same reference numeral, and redundant explanations are omitted. Furthermore, the drawings are schematic, and the relationship between thickness and planar dimensions, the ratio of the thicknesses of each layer, etc., may differ from reality.

[0019] Furthermore, the embodiments shown below illustrate configurations for realizing the technical concept of the present invention, and the technical concept of the present invention does not limit the materials, shapes, and structures of the components to those described below. The technical concept of the present invention can be modified in various ways within the technical scope defined by the claims described in the patent claims.

[0020] <1> Decorative materials and decorative sheets Figure 1 is a cross-sectional view of a decorative material including a decorative sheet according to one embodiment of the present invention. Figure 2 is a cross-sectional view of a decorative material including a decorative sheet according to another embodiment of the present invention. Figure 3 is a cross-sectional view of the surface protective layer of the decorative sheet in Figures 1 and 2. Figure 4 is a micrograph of the surface protective layer of a decorative sheet according to an example of the present invention.

[0021] The cross-section shown in Figure 3 is a cross-section along the thickness direction of the surface protective layer. The micrograph in Figure 4 is a planar image obtained using a laser microscope (Olympus OLS-4000).

[0022] The decorative material 11 shown in Figures 1 and 2 includes a base material B and a decorative sheet 1 attached thereto. Here, the decorative material 11 is a decorative board. The decorative board may be flat, bent, or folded. The decorative material 11 may have a shape other than a board.

[0023] In this case, base material B is a board. The board material is, for example, a wood-based board, an inorganic board, a metal plate, or a composite board made of multiple materials. Base material B may have a shape other than a board.

[0024] In the decorative sheet 1 shown in Figure 1, the pattern layer 3 and the surface protection layer 5 are provided in this order from the side of the base layer 2 on the surface side of the base layer 2, and the primer layer 6 is provided on the other side of the base layer 2 (i.e., the side facing the substrate B). In Figure 1, one or more of the pattern layer 3 and primer layer 6 may be omitted.

[0025] Furthermore, in the decorative sheet 1 shown in Figure 2, the pattern layer 3, adhesive resin layer 4b, transparent resin layer 4, and surface protection layer 5 are provided in this order from the side of the base layer 2 on the surface side, which is one side of the base layer 2, and a primer layer 6 is provided on the other side of the base layer 2 (i.e., the side facing the substrate B). Here, the transparent resin layer 4 is given an embossed pattern (embossed pattern 4a). In Figure 2, one or more of the pattern layer 3, adhesive resin layer 4b, transparent resin layer 4, and primer layer 6 may be omitted. Also, the embossed pattern 4a may not be provided.

[0026] Furthermore, to meet requirements such as scratch resistance, multiple layers of at least one of the transparent resin layer 4 and the surface protection layer 5 may be laminated. Also, considering the adhesion between each layer, other known layers may be arranged. In addition, a concealing layer (not shown) or the like may be provided between the base layer 2 and the primer layer 6 as appropriate.

[0027] Next, we will describe each layer that makes up the decorative sheet 1.

[0028] <1.1>Primitive layer For the base layer 2, any material can be arbitrarily selected from, for example, paper, synthetic resin, or foamed synthetic resin, rubber, nonwoven fabric, synthetic paper, metal foil, etc. Examples of paper include tissue paper, titanium paper, and resin-impregnated paper. Examples of synthetic resins include polyethylene, polypropylene, polybutylene, polystyrene, polycarbonate, polyester, polyamide, ethylene-vinyl acetate copolymer, polyvinyl alcohol, and acrylic. Examples of rubber include ethylene-propylene copolymer rubber, ethylene-propylene-diene copolymer rubber, styrene-butadiene copolymer rubber, styrene-isoprene-styrene block copolymer rubber, styrene-butadiene-styrene block copolymer rubber, and polyurethane. Examples of nonwoven fabrics include organic and inorganic nonwoven fabrics. Examples of metals for metal foil include aluminum, iron, gold, and silver. Furthermore, the base layer 2 may be a sheet made of the same resin composition as the transparent resin layer 4. In this case, the base layer 2 is obtained by forming the resin material or resin composition into a film. Examples of molding methods include calendering and extrusion molding.

[0029] The raw material layer 2 preferably has a colored layer formed by mixing inorganic pigments with a synthetic resin, and a skin layer made of synthetic resin. The thickness of the skin layer is preferably 3 μm to 20 μm, and the ratio of the thickness of the skin layer to the colored layer is preferably 1:6 to 1:50. When the raw material layer 2 is formed by co-extrusion, if the colored layer is the outermost layer, the pigment components contained in the colored layer will blade out and contaminate the T-die of the extruder and the rolls during transport, so it is preferable that the outermost layer be a skin layer that does not contain pigment. It is preferable to provide skin layers on both sides of the colored layer. If the skin layer is made thicker and its ratio to the colored layer is increased, the ratio of the colored layer decreases, which reduces the opacity and is therefore undesirable.

[0030] Furthermore, the thickness of the base layer 2 is preferably 50 μm or more and 150 μm or less. If the thickness of the base layer 2 is less than 50 μm, the ability to cover unevenness in the substrate (unevenness) will decrease. On the other hand, if the thickness of the base layer 2 exceeds 150 μm, defects such as whitening and cracking may occur during bending.

[0031] (Inorganic pigments) The inorganic pigment can be any known inorganic pigment, such as titanium dioxide, used to provide opacity. The base layer 2 plays the role of concealing the pattern of the substrate B. To obtain the required opacity from the viewpoint of the design of the decorative sheet 1, it is preferable that the light transmittance be 40% or less. If the opacity is low, the pattern of the design layer 3 and the pattern of the substrate B will be mixed, which is undesirable. By including an inorganic pigment, a decorative sheet 1 with good opacity can be obtained. The amount of inorganic pigment to be mixed is preferably 5 parts by mass or more and 50 parts by mass or less, based on 100 parts by mass of resin material. If the amount of inorganic pigment is too low, the opacity will be poor, and if the amount is 50 parts by mass or more, the base layer 2 will become brittle, which is undesirable. The inorganic pigment to be included is not particularly limited, but examples include natural inorganic pigments and synthetic inorganic pigments. Examples of natural inorganic pigments include earth-based pigments, calcined earth, and mineral pigments. Examples of synthetic inorganic pigments include oxide pigments, hydroxide pigments, sulfide pigments, silicate pigments, phosphate pigments, carbonate pigments, metal powder pigments, and carbon pigments. Furthermore, mixed pigments, which are mixtures of one or more natural inorganic pigments and synthetic inorganic pigments, may be used as synthetic inorganic pigments. Organic pigments such as carbon black may also be used in combination with synthetic inorganic pigments.

[0032] Furthermore, additives such as fatty acid metal salts may be added to inorganic pigments to improve their dispersibility and extrusion suitability.

[0033] When using a substrate with an inert surface, such as an olefin-based substrate, as the base layer 2, it is desirable to perform corona treatment, plasma treatment, ozone treatment, electron beam treatment, ultraviolet treatment, dichromate treatment, etc., on both the front and back surfaces of the base layer 2.

[0034] <1.2>Pattern Layer A pattern layer 3 can be provided on the surface of the raw material layer 2 to add a pattern to the decorative sheet 1. Examples of patterns that can be used include wood grain, stone, sand, tile, brickwork, fabric, leather texture, and geometric shapes.

[0035] Furthermore, a base solid ink layer (not shown) may be provided between the base material layer 2 and the pattern layer 3, depending on the desired degree of design. The base solid ink layer is provided so as to cover the entire surface of the base material layer 2. The base solid ink layer may also be made up of two or more layers as needed for opacity, etc. Furthermore, the pattern layer 3 may be formed by laminating as many layers as necessary to express the desired design. Thus, the pattern layer 3 and the base solid ink layer can be in various combinations depending on the desired design, that is, the design to be expressed, but there are no particular limitations.

[0036] The constituent materials of the base ink layer and the pattern layer 3 are not particularly limited. As constituent materials of the base ink layer and the pattern layer 3, for example, printing inks or coating agents can be used, which are obtained by dissolving and dispersing a matrix and a coloring agent such as a dye or pigment in a solvent. As the matrix, various synthetic resins such as oily nitrite resin, two-component urethane resin, acrylic resin, styrene resin, polyester resin, urethane resin, polyvinyl resin, alkyd resin, epoxy resin, melamine resin, fluororesin, silicone resin, rubber resin, or mixtures or copolymers thereof can be used. As the coloring agent, inorganic pigments such as carbon black, titanium white, zinc oxide, iron oxide, yellow lead, Prussian blue, and cadmium red, or organic pigments such as azo pigments, lake pigments, anthraquinone pigments, phthalocyanine pigments, isoindolinone pigments, and dioxazine pigments, or mixtures thereof can be used. Furthermore, solvents such as toluene, xylene, ethyl acetate, butyl acetate, methyl alcohol, ethyl alcohol, isopropyl alcohol, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, water, or mixtures thereof can be used.

[0037] Furthermore, functional additives such as extender pigments, plasticizers, dispersants, surfactants, tackifiers, adhesion aids, drying agents, curing agents, curing accelerators, and curing retarders may be added to the base ink layer and the pattern layer 3 in order to impart various functions.

[0038] Here, the base solid ink layer and the pattern layer 3 can be formed by various printing methods such as gravure printing, offset printing, screen printing, electrostatic printing, and inkjet printing. Furthermore, since the base solid ink layer covers the entire surface of the base material layer 2, it can also be formed by various coating methods such as roll coating, knife coating, microgravure coating, and die coating. These printing and coating methods may be selected separately depending on the layer to be formed, but it is more efficient to select the same method and process them all at once.

[0039] The thickness of the pattern layer 3 is preferably 3 μm or more and 20 μm or less. When the thickness of the pattern layer 3 is within this range, the printing can be made clearer, the printability when manufacturing the decorative sheet 1 can be improved, and manufacturing costs can be reduced.

[0040] <1.3>Transparent resin layer The resin material used as the main component of the transparent resin layer 4 is preferably an olefin-based resin, and in addition to polypropylene, polyethylene, polybutene, etc., α-olefins (for example, propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, tridecene, 1-tetradecene, 1-pentadecene, 1-hexadecene, 1-heptadecene, 1-octadecene, 1-nonadecene, 1-eicosene, 3-methyl-1-butene, 3-methyl-1-pentene, 3-ethyl-1-pentene, 4-methyl-1-pentene, 4-methyl-1-hexene, 4,4-dimethyl-1-pentene) Examples include monopolymers or copolymers of two or more of the following (e.g., 4-ethyl-1-hexene, 3-ethyl-1-hexene, 9-methyl-1-decene, 11-methyl-1-dodecene, 12-ethyl-1-tetradecene), as well as copolymers of ethylene or α-olefins with other monomers, such as ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, ethylene-methyl methacrylate copolymer, ethylene-ethyl methacrylate copolymer, ethylene-butyl methacrylate copolymer, ethylene-methyl acrylate copolymer, ethylene-ethyl acrylate copolymer, and ethylene-butyl acrylate copolymer. Furthermore, to improve the surface strength of the decorative sheet 1, it is preferable to use highly crystalline polypropylene.

[0041] Here, in this specification, the main component refers to 90% or more by mass of the material in question, unless otherwise specified.

[0042] When a transparent resin layer 4 is provided, the thickness of the transparent resin layer 4 is preferably 50 μm or more and 100 μm or less. If it is less than 50 μm, the effect of improving the scratch resistance of the surface of the transparent resin layer 4 is low, and the significance of providing the transparent resin layer 4 diminishes. If the thickness of the transparent resin layer 4 exceeds 100 μm, the rigidity of the decorative sheet 1 becomes too high, which may cause problems such as whitening or cracking during bending.

[0043] However, if a surface protection layer 5 is provided on top of the transparent resin layer 4, the thickness of the transparent resin layer 4 may be less than 50 μm.

[0044] Furthermore, the resin composition constituting the transparent resin layer 4 may contain various functional additives as needed, such as heat stabilizers, light stabilizers, ultraviolet absorbers, blocking inhibitors, catalyst scavengers, colorants, light scattering agents, and gloss modifiers. These various functional additives can be appropriately selected from well-known sources.

[0045] Furthermore, the adhesive used to bond the pattern layer 3 and the transparent resin layer 4 can be selected from any material depending on the bonding method. Examples of bonding methods include lamination methods such as heat lamination, extrusion lamination, and dry lamination, and the adhesive can be selected from materials such as acrylic, polyester, and polyurethane. Usually, due to its cohesive strength, a two-component curing type urethane material that utilizes the reaction of isocyanate and polyol is preferable. There are no particular restrictions on the lamination method of the transparent resin layer 4, but methods using heat and pressure, extrusion lamination, and dry lamination are common.

[0046] Furthermore, the transparent resin layer 4 may have an embossed pattern (embossed pattern 4a). It is also possible to embed ink in the embossed pattern 4a to further improve its aesthetic appeal. When applying the embossed pattern 4a, there are methods such as applying the embossing later by heat and pressure to a sheet that has been laminated using various methods, or creating an embossed pattern on a cooling roll and applying the embossing simultaneously with extrusion lamination.

[0047] Alternatively, a method can be used in which the embossed pattern layer 3 and the transparent resin layer 4 are bonded together by heat or dry lamination simultaneously with the extrusion.

[0048] Furthermore, to improve the adhesion between the pattern layer 3 and the transparent resin layer 4, an adhesive resin layer 4b may be provided between the pattern layer 3 and the transparent resin layer 4. Specifically, when further lamination strength is desired by the extrusion lamination method, an adhesive resin layer 4b may be provided between the transparent resin layer 4 and the adhesive. When an adhesive resin layer 4b is provided, lamination can be performed by co-extrusion of the transparent resin layer 4 and the adhesive resin layer 4b. The adhesive resin layer 4b can be made of a resin such as polypropylene, polyethylene, or acrylic that has been acid-modified. The thickness of the adhesive resin layer 4b is preferably 2 μm or more for the purpose of improving adhesive strength.

[0049] <1.4>Surface protective layer As shown in Figure 3, the surface protection layer 5 has a core portion 5A and ridged portions 5B that protrude in a ridge-like manner from one surface of the core portion 5A. This creates an uneven surface on the surface protection layer 5. In the decorative sheet 1 according to this embodiment, "ridged" means a long, narrow, raised shape that is linearly connected in a plan view. The ridged portions 5B may be curved or straight in a plan view, but a curved shape is preferable from the viewpoint of fingerprint resistance of the decorative sheet 1. In this embodiment, the ridged portions 5B refer to, for example, the portion of the uneven surface protection layer 5 from the lowest to the highest point, and the core portion 5A refers to the portion of the surface protection layer 5 excluding the ridged portions 5B. The cross-sectional shape of the ridged portions 5B in the thickness direction of the surface protection layer 5 may be sinusoidal. A sinusoidal shape here refers to a shape in which the line from the lowest to the highest point of the ridged portions 5B can be represented by a sine wave.

[0050] Figure 3 is a schematic cross-sectional view showing the cross-section of the ridged portion 5B of the surface protective layer 5 (cross-section in the thickness direction of the surface protective layer 5), and Figure 4 is a plan view showing the surface structure of the surface protective layer 5. Here, Figure 4 is a plan view obtained using a laser microscope (OLS-4000 manufactured by Olympus Corporation).

[0051] As shown in the plan view of Figure 4, the ridged portion 5B is elongated and raised, and in a plan view it is formed in a linear fashion. The ridged portion 5B is formed when the surface of the ionizing radiation-curable resin is irradiated with light of a specific wavelength, causing the cured film of the ionizing radiation-curable resin to buckle, as will be described later.

[0052] The shape of the ridged portion 5B can be expressed by the ratio RSm / Ra, which is the ratio of the surface roughness index RSm (μm) in the horizontal direction (the planar direction of the surface protective layer 5, which is the left-right direction in Figure 3) to the surface roughness index Ra (μm) in the vertical direction (the depth direction of the ridged portion 5B, which is the thickness direction of the surface protective layer 5, which is the up-down direction in Figure 3). The ratio RSm / Ra is preferably between 10 and 300. More preferably, RSm / Ra is between 10 and 250. When the value of the ratio RSm / Ra is small, the shape of the ridged portion 5B becomes finer, making it more difficult to wipe away dirt and tending to reduce stain resistance. When the value of the ratio RSm / Ra is large, the spacing between the ridges becomes wider, which tends to increase glossiness. Here, the surface roughness indices Ra and RSm are measured values ​​obtained using a wire roughness meter and are measured in accordance with JIS B0601.

[0053] In the power spectrum obtained by Fourier transforming the surface shape in the cross-section of the surface protective layer 5, the average value of the common logarithm of the power in the interval where the spatial frequency is between 3000 cycles / mm and 3500 cycles / mm is logPf. 3000-3500 logPf is the average value of the common logarithm of the power in the interval between 500 cycles / mm and 1000 cycles / mm, relative to the given value. 500-1000 The power ratio x is within the range of 4.0 to 13.5.

[0054] The power ratio x is preferably in the range of 4.2 to 13.5, more preferably in the range of 4.5 to 13.5, even more preferably in the range of 4.5 to 10.0, and even more preferably in the range of 4.5 to 8.0.

[0055] Regarding the uneven structure of the surface protective layer 5, the power ratio x is defined here, and the power ratio x is a value obtained by the following method. In deriving the power ratio x, first, the cross-section of the surface protective layer 5 is observed with an optical microscope. The cross-sectional observation is performed in the following procedure.

[0056] First, a Pt film for interface marking is formed on the surface of the surface protection layer 5 by sputtering Pt (40mA, 20 seconds). Next, the sample with the Pt film is embedded in a photocurable resin, and then a cross section parallel to the thickness direction of the surface protection layer 5 is exposed. For the exposure of the cross section, an ultramicrotome (Leica Microsystems, EM UC7) is used, for example. Then, this cross section is observed at 1000x magnification with an optical microscope. For this observation, an Olympus optical microscope (BX53M) is used, for example. In this observation, 22 consecutive fields of view are captured in a direction perpendicular to the thickness direction of the surface protection layer 5, and by appropriately stitching these 22 acquired images in the lateral direction, a stitched cross section image with a width of 2 mm is obtained. The number of pixels in the width direction of this stitched cross section image is set to 15240. The number of pixels N in the vertical direction of the image is set to 553 here.

[0057] Next, the shape of the surface protective layer 5 is extracted from this connected cross-sectional image using the method described below. ImageJ is used as the image processing software for shape extraction.

[0058] First, the stitched cross-sectional image is converted to an 8-bit grayscale image. Next, to set the gradation value of only the region corresponding to the surface protection layer to 255 later, the ImageJ Subtract function is used to subtract 1 from the gradation value of all pixels. This adjusts the maximum gradation value to 254. Then, using the ImageJ Polygon selection function, the contour of the region corresponding to the surface protection layer is approximated by a polygon in the image whose gradation values ​​have been adjusted. The contour of the polygonally approximated region is further converted into a smooth shape using the ImageJ Fit Spline function. Then, the region enclosed by this smooth contour is filled using the ImageJ Fill function so that the gradation value becomes 255. After that, the ImageJ Threshold function is used to keep the gradation value of pixels with a gradation value of 255, and convert the gradation value of pixels with a gradation value of 254 or less to zero. In this way, a binarized image is obtained in which the region corresponding to the surface protection layer is included as a bright area and the other areas are included as dark areas.

[0059] Next, the binarized image is converted to a 32-bit grayscale image. In this conversion, the tonal values ​​of pixels corresponding to the bright areas remain at 255, and the tonal values ​​of pixels corresponding to the dark areas remain at zero. Subsequently, the tonal value of each pixel is multiplied by the vertical dimension H (μm) of the field of view, which corresponds to the total vertical length of the image, using ImageJ's Multiply function. Then, the above product is divided by 255 using ImageJ's Divide function. As a result, the tonal values ​​of pixels corresponding to the dark areas remain at zero, while the tonal values ​​of pixels corresponding to the bright areas are replaced with the dimension H (μm), which in this case is 135.3 μm.

[0060] Next, using the ImageJ Plot Profile function, the grayscale values ​​of the vertically aligned pixels are accumulated for each horizontal coordinate (pixel) of the image, and this is divided by the vertical number of pixels in the image, N, in this case 553, to extract a value. Here, in the above image, the grayscale values ​​of the pixels included in the region corresponding to the surface protective layer are replaced by the vertical dimension H of the field of view, which corresponds to the total vertical length of the image. Therefore, the value obtained by dividing the above accumulated value by the vertical number of pixels in the image, N, represents the thickness of the surface protective layer for a specific horizontal coordinate.

[0061] In this way, a cross-sectional profile of the surface protection layer is obtained, with the horizontal pixel coordinates of the stitched images as the horizontal axis and the thickness as the vertical axis. An example of a cross-sectional profile of the surface protection layer is shown in Figure 5.

[0062] Next, the obtained cross-sectional profile is subjected to a one-dimensional Fourier transform to create a power spectrum. Specifically, the power spectrum for the frequency components of the cross-sectional profile is created by performing a Fourier transform analysis on the cross-sectional profile. As for the Fourier transform analysis, the Fast Fourier Transform (FFT) is preferred because it can be computed in a short amount of time.

[0063] The power spectrum represents the intensity of the period in the cross-sectional profile, decomposed for each spatial frequency. The results of the analysis using the one-dimensional Fourier transform are expressed as a power spectrum with frequency on the horizontal axis and power (square of amplitude) on the vertical axis. Figure 6 shows the power spectrum against spatial frequency, created by performing a one-dimensional Fourier transform on the cross-sectional profile shown in Figure 5. Here, the power has been reduced in noise by performing a 64-period moving average and is expressed on a common logarithmic scale.

[0064] The power ratio x is a value calculated from the power spectrum obtained in this way using the following equation. Power ratio x = (logPf 500-1000 ) / (logPf 3000-3500 ) Here, in the above equation, logPf 500-1000logPf is the average of the common logarithms of power in the spatial frequency range of 500 cycles / mm to 1000 cycles / mm. 3000-3500 This is the average of the common logarithms of power in the spatial frequency range of 3000 cycles / mm to 3500 cycles / mm.

[0065] As described above, the power spectrum obtained by Fourier transforming the surface shape in the cross-section of the surface protective layer 5 has a power ratio x within the range of 4.0 to 13.5. The inventors have found a correlation between the tactile feel of the decorative sheet and the power ratio x. That is, when the power ratio x is within the above range, a moist tactile feel can be obtained.

[0066] Specifically, when the power ratio x is within the above range, when a user presses their finger against the surface of the decorative sheet and slides their finger across the surface, the contact area between the finger and the raised surface can be gradually increased while keeping the pressure resistance due to contact between the finger and the surface low. As a result, a tactile sensation of the decorative sheet surface sticking to the finger is obtained. This tactile sensation can be described as a "moist tactile sensation."

[0067] On the other hand, when the power ratio x is greater than 13.5, when pressing down on the surface of the decorative sheet with a finger and sliding the finger across the surface, the resistance to pressing due to the contact between the finger and the surface increases, and the contact area between the finger and the raised surface increases gradually with increasing pressure. Therefore, with such a decorative sheet, the contact area between the finger and the raised surface does not increase as much as with decorative sheets that give a "moist" or "smooth" feel during pressing. As a result, such a decorative sheet gives a tactile sensation that makes one feel the presence of irregularities on its surface, and also gives a rougher feel compared to the "moist" feel mentioned above, resulting in a stronger overall impression of a tactile sensation that makes one feel the presence of irregularities. This tactile sensation can be associated with a "rough" feel.

[0068] Furthermore, when the power ratio x is less than 4.0, when pressing down on the surface of the decorative sheet with a finger and sliding the finger across the surface, the resistance to pressing due to the contact between the finger and the surface becomes smaller, and the contact area between the finger and the raised surface increases rapidly with pressure. Consequently, the contact area between the finger and the raised surface becomes large from the start of the pressing motion, and the user does not feel the presence of the bumps. In this case, the surface of the decorative sheet gives a tactile sensation that feels as if it is sticking to the finger, while also giving a smoother tactile sensation compared to the "moist tactile sensation" described above, resulting in a stronger overall impression of a smooth tactile sensation. This tactile sensation can be described as a "smooth tactile sensation."

[0069] The thickness t of the surface protective layer 5 is 2 μm or more and 18 μm or less. Preferably, the thickness t of the surface protective layer 5 is 3 μm or more and 10 μm or less. If the surface protective layer 5 is too thick or too thin, it becomes difficult to achieve a "moist touch." Furthermore, if the surface protective layer 5 is too thin, it becomes difficult to achieve a low gloss level, and if it is too thick, the processability decreases and whitening occurs when bent.

[0070] Here, the thickness of the surface protection layer 5 is the thickness of a layer that has the same apparent area and volume as the surface protection layer 5 and has a flat surface. The thickness of the surface protection layer 5 can be determined, for example, by the following method. First, a cross-section parallel to the thickness direction of the surface protection layer 5 and perpendicular to the length direction of the ridged portion 5B is imaged. Next, from this cross-sectional image, the dimensions of the surface protection layer 5 in the width direction of the ridged portion 5B and the area of ​​the cross-section of the surface protection layer 5 are determined. The thickness of the surface protection layer 5 is the value obtained by dividing this area by the above dimensions. Alternatively, the thickness of the surface protection layer 5 can be determined by observing the cross-section with a scanning electron microscope and averaging 25 points. Specifically, the thickness of the surface protection layer 5 can be determined as described in the examples below. Note that if the coating liquid for the surface protection layer described later does not contain a solvent, the thickness of the coating film made from the coating liquid for the surface protection layer is equal to the thickness of the surface protection layer 5.

[0071] Here, the surface protection layer 5 can be formed by various printing methods such as gravure printing, offset printing, screen printing, electrostatic printing, and inkjet printing. Furthermore, since the surface protection layer 5 covers the entire surface of the base layer 2, it can also be formed by various coating methods such as roll coating, knife coating, microgravure coating, and die coating. These printing or coating methods may be selected separately depending on the layer to be formed, or the same method may be selected for batch processing.

[0072] The pattern layer 3 and the surface protection layer 5 may be synchronized from an aesthetic standpoint. If they are synchronized, it is necessary to form the surface protection layer 5 in one step after forming the pattern layer 3, so it is preferable to use gravure printing. Furthermore, since gravure printing can be processed relatively quickly, it is also advantageous in terms of cost and is therefore preferable. Here, synchronization means that 50% or more, preferably 70% or more, and most preferably 90% or more of the portion on which the surface protection layer 5 is formed overlaps with the pattern portion of the pattern layer 3 in a plan view.

[0073] To adjust the thickness of the surface protection layer 5, the amount applied in the printing and coating methods described above can be adjusted. The amount applied can be calculated by creating a base sheet (including the raw material layer) with and without the surface protection layer 5 in each printing and coating method, and then calculating the difference in mass between them.

[0074] The main material of the surface protection layer 5 is preferably an ionizing radiation-curable resin. The main material refers to a quantity of 60 parts by mass or more, more preferably 70 parts by mass or more, and most preferably 80 parts by mass or more, per 100 parts by mass of the surface protection layer 5. Here, "ionizing radiation" refers to charged particle beams such as electron beams. Ionizing radiation-curable resins harden when irradiated with ionizing radiation. Ionizing radiation-curable resins can also be hardened by ultraviolet irradiation. The ionizing radiation-curable resin used here hardens when irradiated with light with a wavelength of 200 nm or less, while having a large absorption coefficient for this light. As the ionizing radiation-curable resin constituting the surface protection layer 5, various monomers and commercially available oligomers, etc., can be known and used. For example, (meth)acrylic resins, silicone resins, polyester resins, urethane resins, amide resins, and epoxy resins can be used. The ionizing radiation-curable resin may be either an aqueous resin or a non-aqueous (organic solvent) resin, and may be used alone or in combination of multiple types.

[0075] The main component of the ionizing radiation-curable resin is preferably acrylate. Here, the main component of the ionizing radiation-curable resin means a component that accounts for 60% by mass or more of the ionizing radiation-curable resin. The ionizing radiation-curable resin preferably contains acrylate in an amount of 70 parts by mass or more, and more preferably in an amount of 80 parts by mass or more.

[0076] The acrylate is preferably a two-functional or more-functional acrylate, and more preferably a three-functional or more-functional acrylate. For obtaining a surface protective layer 5 with excellent scratch resistance, it is preferable that the acrylate be three-functional or more. There is no upper limit to the number of functional groups in the acrylate, but one example suggests it is six-functional or less.

[0077] The acrylate preferably contains a repeating structure. This repeating structure is, for example, one of the following: an ethylene oxide (EO) structure, a propylene oxide (PO) structure, or an ε-caprolactone (CL) structure. The repeating structure is preferably ethylene oxide or propylene oxide. In the acrylate, the above repeating structure may be interposed between the acryloyl group and the methylol group in an open ring state.

[0078] The number of repetitions of the repeating structure is preferably 6 or more. When an acrylate with a high number of repetitions is used, expansion in the in-plane direction of the cured film is more likely to occur in the first irradiation step described later, and therefore, wrinkles corresponding to the ridged portions 5B are more likely to occur on the surface of the coating film. In addition, when an acrylate with a high number of repetitions is used, the value of the power ratio x mentioned above tends to increase. However, increasing the number of repetitions reduces the crosslinking density and decreases the scratch resistance of the surface protective layer.

[0079] In a preferred embodiment, the ionizing radiation-curable resin is a trifunctional acrylate containing a repeating structure. Examples of trifunctional acrylates containing a repeating structure include EO-modified, PO-modified, or CL-modified trimethylolpropane triacrylate, glycerin triacrylate, isocyanurate triacrylate, or pentaerythritol triacrylate. When gravure printing is used as the coating method for the ionizing radiation-curable resin, the optimal viscosity range is 10 to 500 mPa·s. Therefore, using trimethylolpropane triacrylate or glycerin triacrylate as the trifunctional acrylate resin is preferable as it allows the viscosity to be kept within the optimal range. Resins with skeletons that induce hydrogen bonding or π-π stacking often have high viscosities of 500 mPa·s or higher, which is undesirable. Furthermore, organic solvents or low-viscosity bifunctional acrylate resins can be added to adjust the viscosity. However, from the viewpoint of environmental impact, it is preferable not to use organic solvents. Difunctional acrylate resins are undesirable because high addition amounts reduce scratch resistance. Therefore, the amount of difunctional acrylate resin added is preferably within the range of 10% to 30% by mass of the content (mass) of the trifunctional acrylate resin.

[0080] In trifunctional acrylates containing repeating structures, the number of repetitions of the repeating structure is preferably 6 or more, more preferably 6 to 20, and even more preferably 6 to 17. If the number of repetitions is small, when irradiated with vacuum ultraviolet light (VUV light), the cured film of the ionizing radiation-curable resin constituting the surface protective layer 5 does not swell easily in the in-plane direction, and therefore wrinkles are not sufficiently formed, making it difficult for the surface protective layer 5 to have low gloss. If the number of repetitions is large, the crosslinking density decreases and the scratch resistance of the surface protective layer 5 tends to decrease.

[0081] In another preferred embodiment, the ionizing radiation-curable resin is a tetrafunctional acrylate containing a repeating structure. Examples of tetrafunctional acrylates containing a repeating structure include EO-modified, PO-modified, or CL-modified pentaerythritol tetraacrylate. In the tetrafunctional acrylate containing a repeating structure, the number of repetitions of the repeating structure is preferably 12 or more, more preferably 12 to 50, even more preferably 20 to 50, and still more preferably 20 to 35. If the number of repetitions is low, when irradiated with VUV light, the cured film of the ionizing radiation-curable resin constituting the surface protective layer 5 does not swell easily in the in-plane direction, and therefore, wrinkles are not sufficiently formed, making it difficult for the surface protective layer 5 to have low gloss. If the number of repetitions is high, the crosslinking density decreases, and the scratch resistance of the surface protective layer 5 tends to decrease.

[0082] The number of repetitions in the above repeating structure can be analyzed using MALDI-TOF-MS. Ionizing radiation-curable resins may have a molecular weight distribution. If a molecular weight distribution exists, the number of repetitions should be the number of repetitions corresponding to the molecular weight with the strongest peak in the MALDI-TOF-MS mass spectrum.

[0083] The surface protective layer 5 may contain particles. By adding particles with an optimal particle size and optimal content, a uniform surface can be formed. Examples of particles include organic materials such as polyethylene (PE) wax, polypropylene (PP) wax, and resin beads, or inorganic materials such as silica, glass, alumina, titania, zirconia, calcium carbonate, and barium sulfate. It is desirable that the average particle size (D50) of the particles be 3 μm or more. Preferably, the average particle size (D50) is 3 μm or more and 11 μm or less, and more preferably 4 μm or more and 10 μm or less.

[0084] When the surface protective layer 5 contains particles, wrinkles can be generated more uniformly on the coating surface during the first irradiation step described later. Therefore, if the average particle size (D50) is too small or too large, it becomes difficult to achieve a "moist texture." Also, if large particles are used, the particles are more likely to fall off the surface protective layer 5, which may make it difficult to achieve high scratch resistance. If the particles are small, the effect of generating wrinkles uniformly is small.

[0085] Here, "average particle size (D50)" refers to the median diameter (D50) measured by a laser diffraction / scattering particle size distribution analyzer. Note that if the coating liquid for the surface protection layer contains particles, the surface protection layer 5 obtained from this coating liquid will also contain particles. The average particle size of the particles contained in the surface protection layer 5 can be determined by observing its cross-section, measuring the particle sizes of multiple particles, and averaging the result. The value obtained in this way is substantially the same as the median diameter (D50) measured by a laser diffraction / scattering particle size distribution analyzer. Therefore, the range of average particle size described above can also be interpreted as the range of average particle size of the particles contained in the surface protection layer 5.

[0086] The particles are preferably included in the surface protective layer 5 in an amount of 2 to 13 parts by mass per 100 parts by mass of the ionizing radiation-curable resin. More preferably, the amount of particles added is 3 to 12 parts by mass per 100 parts by mass of the resin. Note that "100 parts by mass of resin" refers to the parts by mass of the solid content of the resin.

[0087] When the amount of added particles is within the above range, the effect of creating wrinkles uniformly is particularly large. If wrinkles are not created uniformly, the power ratio x mentioned above tends to decrease. For this reason, if the amount of added particles is too little or too much, it becomes difficult to achieve a "moist texture". Also, if the amount of added particles is too large, the particles are more likely to fall off the surface protective layer 5, making it difficult to achieve high scratch resistance. If the amount of added particles is too small, the effect of creating wrinkles uniformly is small.

[0088] When curing the entire surface protective layer 5 with UV light, it is necessary to add a photopolymerization initiator to the surface protective layer 5. There are no particular limitations on the photopolymerization initiator, but examples include benzaphenone-based, acetophenone-based, benzoin ether-based, and thioxanthone-based initiators.

[0089] The surface protective layer 5 may further contain additives such as antibacterial agents and antifungal agents to impart the required functions. Furthermore, as other additives, it may further contain ultraviolet absorbers and light stabilizers as needed. Commonly used ultraviolet absorbers include benzotriazole-based, benzoate-based, benzophenone-based, and triazine-based types, while common light stabilizers include hindered amine-based types, in any combination.

[0090] Examples of hindered amine-based light stabilizers include bis(1,2,2,6,6-pentamethyl-4-piperidyl)[[3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl]methyl]butylmalonate (a typical example being BASF's trade name "Tinuvin 144"), BASF's trade name "Tinuvin 123", and reaction products of bis(2,2,6,6-tetramethyl-1-(octyloxy)-4-piperidinyl) ester (1,1-dimethylethyl hydroperoxide) with octane.

[0091] When adding a hindered amine-based light stabilizer to the surface protective layer 5, it is preferable to add it in an amount of 0.05 parts by mass or more and 5 parts by mass or less per 100 parts by mass of the ionizing radiation-curable resin. More preferably, the amount of hindered amine-based light stabilizer added is in the range of 0.2 parts by mass or more and 3 parts by mass or less. If the amount of hindered amine-based light stabilizer added is less than 0.05 parts by mass, the effect of stabilizing the resin against ultraviolet light may be low. On the other hand, if it is more than 5 parts by mass, the possibility of bleed-out increases. Furthermore, the surface protective layer 5 can be formed by curing and shrinking the area near the surface by irradiating it with light of 200 nm or less to form a fine uneven shape, but in this case, if the amount of hindered amine-based light stabilizer is more than 3 parts by mass, it may inhibit curing near the surface. In order to achieve both low gloss and weather resistance, it is desirable to include the hindered amine-based light stabilizer in an amount of 3 parts by mass or less.

[0092] The gloss of the surface protective layer 5 should preferably be less than 10.0. More preferably, the gloss of the surface protective layer 5 should be 5.0 or less. Here, "gloss" refers to the measured value when measured at an incident angle of 60 degrees using a gloss meter compliant with JIS Z8741:1997.

[0093] <1.5> Primer layer The primer layer 6 can basically be made from the same material as the pattern layer 3. Considering that the primer layer 6 is applied to the back surface of the decorative sheet 1 and wound in a web-like manner, inorganic fillers such as silica, alumina, magnesia, titanium oxide, and barium sulfate may be added to avoid blocking and improve adhesion with the adhesive. The coating thickness of the primer layer 6 is preferably 0.1 μm to 3.0 μm, as the purpose is to ensure adhesion with the substrate B. The primer layer 6 is necessary when the base material layer 2 is an olefin-based material with an inert surface, but it is not particularly necessary when the surface is active.

[0094] <2> Manufacturing method of decorative sheets The decorative sheet 1 is manufactured, for example, by the following method. For simplicity, the descriptions of the pattern layer 3, the transparent resin layer 4, the adhesive resin layer 4b, and the primer layer 6 are omitted here.

[0095] First, a coating film consisting of a surface protection coating liquid is formed on one side of the base layer 2. As described in section <1.4> Surface Protection Layer, the surface protection coating liquid contains an ionizing radiation-curable resin and, if necessary, particles and additives. The coating film consisting of the surface protection coating liquid can be formed, for example, by printing.

[0096] After forming a coating film consisting of a surface protection coating liquid, a first irradiation step is performed. In the first irradiation step, light with a wavelength of 200 nm or less (hereinafter referred to as first radiation) is irradiated onto the coating film. The ionizing radiation-curable resin contained in the surface protection coating liquid has a large absorption coefficient for first radiation. Therefore, first radiation incident on the coating film can only reach a distance of tens to hundreds of nanometers from its outermost surface. Consequently, in the first irradiation step, a crosslinking reaction proceeds in the surface region of the coating film, forming an extremely thin cured film, while other regions remain uncured as the crosslinking reaction does not proceed.

[0097] The coating film after the first irradiation process has wrinkles on its surface corresponding to the ridged portion 5B. The inventors believe the reason why wrinkles form on the coating film surface due to the first irradiation process is as follows.

[0098] As described above, the first radiation can only reach a distance of tens to hundreds of nanometers from the outermost surface of the coating film. In other words, the crosslinking reaction of the ionizing radiation-curable resin occurs only at the surface of the coating film, and regions further than tens to hundreds of nanometers from the outermost surface remain uncured, containing highly fluid molecules. These highly fluid molecules increase the volume of the cured film by causing it to swell. The in-plane compressive stress caused by this increase in volume in the in-plane direction leads to buckling of the cured film, resulting in wrinkles on the coating film surface.

[0099] The first type of radiation can be extracted from excimer VUV light. Excimer VUV light can be generated from lamps using noble gases or noble gas halide compounds. When high-energy electrons are supplied from an external source to a lamp containing a noble gas or noble gas halide compound, numerous discharge plasmas (dielectric barrier discharges) are generated. This plasma discharge excites the atoms of the discharge gas (noble gas), causing them to instantaneously enter an excimer state. When returning from this excimer state to the ground state, it emits light in a wavelength range specific to that excimer state.

[0100] The gas used in an excimer lamp can be any conventionally used gas, as long as it emits light of 200 nm or less. As gases, noble gases such as Xe, Ar, and Kr, or mixed gases of noble gases and halogen gases such as ArBr and ArF can be used. The central wavelength of an excimer lamp varies depending on the gas used, and has wavelengths such as approximately 172 nm (Xe), approximately 126 nm (Ar), approximately 146 nm (Kr), approximately 165 nm (ArBr), and approximately 193 nm (ArF).

[0101] Considering the magnitude of the photon energy and the difference between the wavelength and the bonding energy of the organic material, it is preferable to use a xenon lamp that emits excimer light with a central wavelength of 172 nm as the light source. Furthermore, considering the costs of equipment maintenance and material availability, it is also preferable to use a xenon lamp as the light source.

[0102] The first irradiation step is carried out in an atmosphere with a low oxygen concentration. Oxygen has a large absorption coefficient for light below 200 nm. Therefore, it is preferable to carry out the first irradiation step in a nitrogen gas atmosphere, for example. The oxygen concentration in the gas phase during the first irradiation step, i.e., the residual oxygen concentration in the reaction atmosphere, is preferably 2000 ppm or less, and more preferably 1000 ppm or less.

[0103] Furthermore, oxygen in the atmosphere inhibits radical polymerization. Therefore, the residual oxygen concentration in the reaction atmosphere affects the formation of wrinkles on the coating surface. Consequently, changing the residual oxygen concentration in the reaction atmosphere can also change the surface properties of the protective layer 5.

[0104] The integrated light quantity of the first radiation is 0.5 mJ / cm 2 or more and 200 mJ / cm 2 or less, preferably 1 mJ / cm 2 or more and 100 mJ / cm 2 or less, more preferably 3 mJ / cm 2 or more and 50 mJ / cm 2 or less, still more preferably 5 mJ / cm 2 or more and 30 mJ / cm 2 or less, most preferably. When the integrated light quantity is reduced, the expansion of the cured film in the in-plane direction becomes smaller. When the integrated light quantity is increased, the surface state of the coating film deteriorates.

[0105] After completing the first irradiation step, a second irradiation step is carried out. In the second irradiation step, the coating film is irradiated with the second radiation to cure the entire coating film. Thereby, the surface protective layer 5 is obtained.

[0106] The second radiation is ionizing radiation such as an electron beam or ultraviolet light having a longer wavelength than the first radiation. When ultraviolet light is used as the second radiation, this ultraviolet light shall have a wavelength at which the radiation-curable resin exhibits a small absorption coefficient.

[0107] The integrated light quantity of the second radiation is 10 mJ / cm 2 or more and 500 mJ / cm 2 or less, preferably 50 mJ / cm 2 or more and 400 mJ / cm 2 or less, more preferably 100 mJ / cm 2 or more and 300 mJ / cm 2 or less, still more preferably.

[0108] <3> Action and Others The decorative sheet 1 described with reference to Figures 1 to 6 has a surface protective layer 5 having the surface properties described above. When a user presses their skin against the surface of the surface protective layer 5 and slides their fingers across the surface, for example, when a user presses their skin against the surface of the surface protective layer 5 and slides their fingers across the surface, such a decorative sheet 1 gives the user a moist tactile sensation. That is, because the slopes of the uneven shape on the surface of the surface protective layer 5 of this decorative sheet 1 are relatively gentle, when touched by the above action, the contact area between the finger and the surface can be gradually increased while keeping the pressure resistance due to contact between the finger and the surface low. As a result, a tactile sensation is obtained in which the surface of the decorative sheet adheres to the finger.

[0109] The moist texture of the decorative sheet 1 can give a person who touches it a feeling of comfort and warmth. Furthermore, the moist texture can give the decorative sheet 1 a sense of luxury. Therefore, the decorative sheet 1, which provides a moist texture to the user, is suitable for applications where the user's skin comes into frequent contact with the sheet or where the user's skin is in contact with the sheet for extended periods, such as on desk tops, chair armrests, and handrails on stairs and in passageways.

[0110] The surface protection layer 5 of the decorative sheet 1 has the surface properties described above, so it can achieve a low gloss level even without containing a gloss adjuster (matte additive). Gloss adjusters reduce the oil repellency of the layer formed by the resin material, so the surface protection layer 5 containing a gloss adjuster is prone to fingerprints. The surface protection layer 5 without a gloss adjuster does not easily absorb oil, so fingerprints do not easily adhere to it. In addition, the surface protection layer 5 with excellent oil repellency is less prone to the adsorption of oil stains and contaminants. Furthermore, when the surface of the surface protection layer 5 without a gloss adjuster is scratched, the particles of the gloss adjuster do not fall off, and therefore, the decorative sheet 1 containing such a surface protection layer 5 is less prone to gloss changes and scratches. In addition to excellent fingerprint resistance, stain resistance, and scratch resistance, the decorative sheet 1 also has excellent weather resistance and processability.

[0111] The surface protective layer 5 having the above surface properties can be obtained by the method described above for the following reasons.

[0112] Oxygen in the gas phase not only absorbs short-wavelength ultraviolet light but also inhibits radical polymerization. The effect of oxygen in the gas phase on radical polymerization is greatest in the portion of the coating film made of ionizing radiation-curable resin adjacent to the gas phase, and decreases as the distance from the coating film surface increases. Therefore, by changing the oxygen concentration in the gas phase in the first irradiation step, the relationship between the distance from the coating film surface and the progress of the crosslinking reaction can be changed.

[0113] When this relationship changes, the thickness of the cured film formed on the surface of the coating by the first irradiation process and the degree of in-plane expansion of the cured film in accordance with the progress of the crosslinking reaction change. The cumulative amount of light in the first irradiation process also affects the thickness of the cured film and the degree of in-plane expansion of the cured film. Furthermore, the thickness of the cured film and the degree of in-plane expansion of the cured film affect the surface properties of the surface protective layer. In addition, the particle size and amount of particles added in the coating film, as well as the thickness of the coating film, also affect wrinkle formation.

[0114] Therefore, by appropriately setting, for example, the composition of the ionizing radiation-curable resin, the thickness of the coating film, the oxygen concentration in the gas phase during the first irradiation step, and the integrated light intensity during the first irradiation step, a surface protective layer having the desired surface properties can be obtained. [Examples]

[0115] Examples of the present invention are described below.

[0116] <Example 1> A 55 μm thick olefin film (manufactured by Riken Technos Co., Ltd.) was used as the base layer 2. One side of the base layer 2 was subjected to corona treatment, and a pattern was printed on that side to form the pattern layer 3. The pattern layer 3 was formed using an ink prepared by adding 0.5 parts by mass of a hindered amine-based light stabilizer (Kimasorb 944; manufactured by BASF) to a two-component urethane ink (V180; manufactured by Toyo Ink Co., Ltd.) relative to the binder resin component of the ink.

[0117] Next, a primer layer 6 was formed on the back surface of the base material layer 2. The primer layer 6 was formed by printing the same two-component urethane ink as the pattern layer 3.

[0118] Next, a protective coating solution for the surface layer was applied to the pattern layer 3. The thickness of the protective coating solution was 5 μm. The protective coating solution used was a mixture of the following ionizing radiation-curable resin and the following additives (particles, photopolymerization initiator). ·Ionizing radiation curable resin Type: Trimethylolpropane EO-modified triacrylate (EO 15 molar added) Product Name: SR9035 (manufactured by Sartomer) Blend: 95 parts by mass Type: Dipentaerythritol hexaacrylate Blend: 5 parts by mass ·particle Product Name: Silysia 250N (Manufactured by Fuji Silysia Chemical Co., Ltd.) Particle size: 5μm Blend: 5 parts by mass • Photopolymerization initiator Product Name: Omnirad184 (manufactured by IGM Resins) Blend: 3 parts by mass.

[0119] Subsequently, the first irradiation process was carried out. Specifically, under atmospheric pressure and in a nitrogen gas atmosphere with an oxygen concentration of 100 ppm, a Xe excimer lamp was used to emit ultraviolet light with a wavelength of 172 nm, accumulating to a total light intensity of 30 mJ / cm². 2 The irradiation was applied in such a manner that wrinkles were created on the surface of the coating.

[0120] Next, the second irradiation process was carried out. Specifically, the coating film was irradiated with a high-pressure mercury lamp at a rate of 200 mJ / cm². 2 By irradiating it with ultraviolet light in such a way that the entire surface hardens, a surface protective layer 5 is formed. In this way, a decorative sheet 1 with a total thickness of 60 μm was obtained.

[0121] <Example 2> A decorative sheet with a total thickness of 60 μm was obtained in the same manner as in Example 1, except that the ionizing radiation-curable resin in Example 1 was replaced with the following. ·Ionizing radiation curable resin Type: Trimethylolpropane EO-modified triacrylate (EO 15 molar added) Product Name: SR9035 (manufactured by Sartomer) Blend: 100 parts by mass.

[0122] <Comparative Example 1> A decorative sheet with a total thickness of 60 μm was obtained in the same manner as in Example 1, except that the ionizing radiation-curable resin in Example 1 was replaced with the following. ·Ionizing radiation curable resin Type: Trimethylolpropane EO-modified triacrylate (EO 3 molar addition) Product Name: Miramer M3130 (Manufactured by Miwon) Blend: 100 parts by mass.

[0123] <Example 3> A decorative sheet with a total thickness of 60 μm was obtained in the same manner as in Example 1, except that the ionizing radiation-curable resin in Example 1 was replaced with the following. ·Ionizing radiation curable resin Type: Trimethylolpropane EO-modified triacrylate (EO 9 molar addition) Product Name: SR502 (manufactured by Sartomer) Blend: 100 parts by mass.

[0124] <Example 4> A decorative sheet with a total thickness of 60 μm was obtained in the same manner as in Example 1, except that the ionizing radiation-curable resin in Example 1 was replaced with the following. ·Ionizing radiation curable resin Type: Trimethylolpropane EO-modified triacrylate (EO 20 molar added) Product Name: NK Ester AT-20E (Manufactured by Shin-Nakamura Chemical Co., Ltd.) Blend: 100 parts by mass.

[0125] <Example 5> Except for not adding the particles from Example 2 (product name: Cylysia 250N), a decorative sheet with a total thickness of 60 μm was obtained in the same manner as in Example 2.

[0126] <Example 6> A decorative sheet with a total thickness of 60 μm was obtained by following the same procedure as in Example 2, except that the particle composition ratio was changed as shown below. ·particle Product Name: Silysia 250N (Manufactured by Fuji Silysia Chemical Co., Ltd.) Particle size: 5μm Blend: 2 parts by mass.

[0127] <Example 7> A decorative sheet with a total thickness of 60 μm was obtained by following the same procedure as in Example 2, except that the particle composition ratio was changed as shown below. ·particle Product Name: Silysia 250N (Manufactured by Fuji Silysia Chemical Co., Ltd.) Particle size: 5μm Blend: 3 parts by mass.

[0128] <Example 8> A decorative sheet with a total thickness of 60 μm was obtained by following the same procedure as in Example 2, except that the particle composition ratio was changed as shown below. ·particle Product Name: Silysia 250N (Manufactured by Fuji Silysia Chemical Co., Ltd.) Particle size: 5μm Blend: 11 parts by mass.

[0129] <Example 9> A decorative sheet with a total thickness of 60 μm was obtained by following the same procedure as in Example 2, except that the particle composition ratio was changed as shown below. ·particle Product Name: Silysia 250N (Manufactured by Fuji Silysia Chemical Co., Ltd.) Particle size: 5μm Blend: 13 parts by mass.

[0130] <Comparative Example 2> A decorative sheet with a total thickness of 60 μm was obtained by following all the same procedures as in Example 2, except that the first irradiation step in Example 2 was omitted and the second irradiation step was performed.

[0131] <Example 10> In Example 2, no photopolymerization initiator was added to the ionizing radiation-curable resin. Furthermore, in the second irradiation step, the coating film was irradiated with ionizing radiation to cure the entire film, thereby forming the surface protective layer 5. Otherwise, everything was carried out in the same manner as in Example 2 to obtain a decorative sheet with a total thickness of 60 μm.

[0132] <Example 11> A decorative sheet with a total thickness of 60 μm was obtained in the same manner as in Example 2, except that the following light stabilizer was added to the ionizing radiation-curable resin of Example 2. • Light stabilizer Product Name: Tinuvin 123 (Manufactured by BASF) Formula: 1 part by mass.

[0133] <Example 12> A decorative sheet with a total thickness of 60 μm was obtained in the same manner as in Example 2, except that the following light stabilizer was added to the ionizing radiation-curable resin of Example 2. • Light stabilizer Product Name: Tinuvin 123 (Manufactured by BASF) Blend: 3 parts by mass.

[0134] <Comparative Example 3> A decorative sheet with a total thickness of 60 μm was obtained in the same manner as in Example 2, except that the following light stabilizer was added to the ionizing radiation-curable resin of Example 2. • Light stabilizer Product Name: Tinuvin 123 (Manufactured by BASF) Blend: 5 parts by mass.

[0135] <Example 13> Similar to Example 1, a sheet consisting of a primer layer 6, a base layer 2, and a pattern layer 3 was prepared. Next, a mixture prepared by mixing 100 parts by mass of crystalline polypropylene resin (pentad fraction 97.8%, molecular weight distribution 2.3, MFR 18g / 10min) with 0.5 parts by mass of a hindered amine-based light stabilizer (BASF's "Kimasorb 944") and 0.5 parts by mass of a benzotriazole-based ultraviolet absorber (BASF's "Tinuvin 328") was co-extruded with a polyethylene-based easy-adhesion resin using a melt extruder to form a transparent resin layer 4 with a thickness of 60 μm and an adhesive resin layer 4b with a thickness of 10 μm. Next, a dry laminating adhesive (Takelac A540; manufactured by Mitsui Chemicals, Inc.; application amount 2g / m²) was applied to the surface of the pattern layer 3. 2 A coating was applied. Subsequently, the pattern layer 3 of the sheet to which the adhesive had been applied and the transparent resin layer 4 were bonded together by extrusion lamination via the formed adhesive resin layer 4b. Furthermore, an embossed pattern 4a was applied to the transparent resin layer 4 side of the bonded sheet by pressing it with an embossing die roll.

[0136] Next, a surface protective coating solution was applied to the transparent resin layer 4. The thickness of the surface protective coating solution was 5 μm. The surface protective coating solution used was a mixture of the following ionizing radiation-curable resin and the following additives (particles, photopolymerization initiator). ·Ionizing radiation curable resin Type: Trimethylolpropane EO-modified triacrylate (EO 15 molar added) Product Name: SR9035 (manufactured by Sartomer) Blend: 100 parts by mass ·particle Product Name: Silysia 250N (Manufactured by Fuji Silysia Chemical Co., Ltd.) Particle size: 5μm Blend: 5 parts by mass • Photopolymerization initiator Product Name: Omnirad184 (manufactured by IGM Resins) Blend: 3 parts by mass.

[0137] Subsequently, the first irradiation process was carried out. Specifically, under atmospheric pressure and in a nitrogen gas atmosphere with an oxygen concentration of 100 ppm, a Xe excimer lamp was used to emit ultraviolet light with a wavelength of 172 nm, accumulating to a total light intensity of 30 mJ / cm². 2 The irradiation was applied in such a manner that wrinkles were created on the surface of the coating.

[0138] Next, the second irradiation process was carried out. Specifically, the coating film was irradiated with a high-pressure mercury lamp at a rate of 200 mJ / cm². 2 By irradiating it with ultraviolet light in such a way that the entire surface hardens, a surface protective layer 5 is formed. In this manner, a decorative sheet with a total thickness of 130 μm was obtained.

[0139] <Example 14> A decorative sheet with a total thickness of 130 μm was obtained in the same manner as in Example 13, except that the following light stabilizer was added to the ionizing radiation-curable resin of Example 13. • Light stabilizer Product Name: Tinuvin 123 (Manufactured by BASF) Formula: 1 part by mass.

[0140] <Example 15> A decorative sheet with a total thickness of 130 μm was obtained in the same manner as in Example 13, except that the following light stabilizer was added to the ionizing radiation-curable resin of Example 13. • Light stabilizer Product Name: Tinuvin 123 (Manufactured by BASF) Blend: 3 parts by mass.

[0141] <Comparative Example 4> A decorative sheet with a total thickness of 130 μm was obtained in the same manner as in Example 13, except that the following light stabilizer was added to the ionizing radiation-curable resin of Example 13. • Light stabilizer Product Name: Tinuvin 123 (Manufactured by BASF) Blend: 5 parts by mass.

[0142] <Rating> The following evaluations were performed on each of the above-mentioned decorative sheets. (1) Thickness of the surface protective layer The thickness of the surface protection layer was measured as follows. The decorative sheet was embedded in a resin such as a cold-curing epoxy resin or a UV-curing resin, and the resin was allowed to cure completely. Next, the sheet was cut so that the cross-section of the decorative sheet was exposed, and the measurement surface was obtained by mechanical polishing. Subsequently, the cross-section of the surface protection layer was imaged using a Carl Zeiss Microscopy SIGMA500 scanning electron microscope. For this imaging, the acceleration voltage was set to 0.5 keV (low acceleration voltage), the imaging mode was SE2 mode, and the magnification was 2000x. No sputtering was performed on the measurement sample. Next, from this cross-sectional image, the dimensions of the surface protection layer in the width direction of the ridged portion and the area of ​​the cross-section of the surface protection layer were determined. The thickness of the surface protection layer was calculated by dividing this area by the above dimensions. Measurements were performed at 25 arbitrary points, and the average value of these 25 points was defined as "thickness t of the surface protection layer". "Thickness t of the surface protection layer" was equal to the thickness of the coating film made of the coating liquid for the surface protection layer.

[0143] (2) Surface state The surface condition was evaluated visually to assess the uniformity of the surface. The evaluation criteria were as follows: ○: Uniform surface condition △: Some areas are uneven. ×: The entire surface is uneven.

[0144] (3) Glossiness Glossiness was measured using a Rhopoint IQ (manufactured by Konica Minolta) at 60 degrees. In the table below, "60° glossiness" refers to this 60° glossiness.

[0145] (4) Power ratio x As described above, the power ratio x was calculated using the following equation based on the power spectrum obtained by performing a one-dimensional Fourier transform on the profile observed in the cross-section with an optical microscope. Power ratio x = (logPf 500-1000 ) / (logPf 3000-3500 ) Here, in the above equation, logPf500-1000 logPf is the average of the common logarithms of power in the spatial frequency range of 500 cycles / mm to 1000 cycles / mm. 3000-3500 This is the average of the common logarithms of power in the spatial frequency range of 3000 cycles / mm to 3500 cycles / mm.

[0146] (5) Fingerprint resistance As part of the fingerprint resistance evaluation, the ability to wipe away fingerprints was assessed. The 60° gloss of the surface of each decorative sheet was measured and defined as the "initial gloss." Next, a fingerprint resistance evaluation solution was applied to the outermost layer, and then the solution adhering to the surface of the decorative sheet was wiped off. After that, the 60° gloss of the area from which the fingerprint resistance evaluation solution had been wiped off was measured and defined as the "gloss after wiping." In this test, a higher fatty acid was used as the fingerprint resistance evaluation solution.

[0147] The fingerprint removal rate was calculated using the following formula. Fingerprint removal rate (%) = (Glossiness after wiping / Initial glossiness) × 100 The evaluation criteria were as follows: AA: 70% to less than 250% A: 50% or more but less than 70%, or 250% or more but less than 300% B: Less than 50%, or 300% or more.

[0148] (6) Stain resistance To evaluate stain resistance, a stain test A, as defined by the Japanese Agricultural Standards (JAS), was conducted. Specifically, lines 10 mm wide were drawn on the surface protective layer of each decorative sheet using blue ink, black quick-drying ink, and red crayon, and left for 4 hours. Afterward, the lines were wiped off with a cloth soaked in ethanol, and the stain resistance to the inks was evaluated.

[0149] The evaluation criteria were as follows: AA: The lines of each color could be easily wiped away. A: You can wipe away some of the lines of each color, but some stains will remain. B: The lines of each color cannot be wiped away.

[0150] (7) Scratch resistance: Steel wool rubbing test After the resulting decorative sheet was attached to the wood substrate B using a urethane-based adhesive, a steel wool rubbing test was conducted to evaluate its scratch resistance. Specifically, a 100g load was applied to the steel wool and rubbed back and forth 20 times, and scratches and changes in gloss on the surface of the decorative sheet were visually observed.

[0151] The evaluation criteria were as follows: AA: No scratches or changes in gloss occurred on the surface. A: Minor scratches and changes in gloss have occurred on the surface. B: Significant scratches or changes in gloss occurred on the surface.

[0152] (8) Processability To evaluate processability, a bending test was conducted. In the bending test, each sheet was attached to a wood substrate, and a V-shaped groove was made on the other side of the substrate up to the boundary where the substrate and the decorative sheet were bonded, taking care not to damage the decorative sheet on the opposite side. Next, the substrate was bent 90 degrees along the V-shaped groove so that the surface of the decorative sheet was folded inwards, and the state of bending processability was evaluated by observing the folded portion of the surface of the decorative sheet using an optical microscope to check for whitening, cracks, etc.

[0153] The evaluation criteria were as follows: A rating of "A" or higher was considered sufficient for practical use. AA: No whitening or cracking is observed. A: Some areas show signs of whitening. B: Whitening is visible across the entire surface, or cracks are visible in some areas.

[0154] (9) Weather resistance: Super UV tester The appearance of the decorative sheet after the accelerated weathering test was visually evaluated according to the following criteria. The accelerated weathering test was conducted using an iSuper UV tester (SUV-W161; manufactured by Iwasaki Electric Co., Ltd.) at a black panel temperature of 63°C and an illuminance of 65 mW / cm². 2The appearance of the decorative sheet was visually evaluated after 30 cycles (720 hours) of UV irradiation (20 hours + condensation).

[0155] The evaluation criteria were as follows: AA: No change in appearance of the decorative sheet. A: Whitening is observed on the decorative sheet. B: Cracks are visible in the decorative sheet.

[0156] (10) Skin feel The skin texture was evaluated using the following method. First, preliminary preparations were made to ensure consistency in evaluation criteria among the evaluators. Specifically, three standard test specimens with different surface properties were prepared. Next, each of the five evaluators, blindfolded, was asked to press their fingers against the surface of the standard test specimens and slide their fingers across the surface, and then classify the tactile sensations into the following three groups. Group 1: There was almost no resistance when pressing down, and the presence of any bumps or irregularities was not felt. However, the surface of the decorative sheet had a tactile sensation that felt as if it was sticking to the fingers, and a smooth feel was obtained. Overall, the impression of a smooth feel was strong. In other words, a smooth feel was obtained. Group 2: There was almost no resistance when pressing, but the surface of the decorative sheet had a tactile sensation of sticking to the finger. However, it did not give the impression of being smooth to the touch. In other words, it had a moist tactile sensation. Group 3: Resistance to indentation was felt, along with the presence of irregularities. In other words, a rough texture was obtained.

[0157] The above procedure was repeated until the evaluations from each evaluator matched three or more times consecutively, and the evaluation results matched three or more times consecutively among the evaluators.

[0158] Next, for each of the above-mentioned cosmetic sheets, each of the evaluators was asked, blindfolded, to press their fingers against the surface of the protective layer and slide their fingers across the surface, and then classify the tactile sensation into the three groups described above. This procedure was repeated until the evaluations from each evaluator agreed three or more times in a row, and the evaluation results agreed three or more times in a row among the evaluators. Based on these results, the skin feel was evaluated according to the following criteria. A (Smooth): Group 1 B (Moist): Group 2 C (rough): Group 3.

[0159] The evaluation results are shown in the table below. In the table, if the skin texture evaluation result is A (smooth), it is indicated by writing the letter Y in the "A (smooth)" column; if the skin texture evaluation result is B (moist), it is indicated by writing the letter Y in the "B (moist)" column; and if the skin texture evaluation result is C (rough), it is indicated by writing the letter Y in the "C (rough)" column.

[0160] [Table 1]

[0161] [Table 2]

[0162] [Table 3]

[0163] As shown in the table, a correlation was observed between the skin feel of the decorative sheet and the power ratio x. The decorative sheets according to Examples 1 to 15 gave the evaluator a moist feel. The decorative sheets according to Examples 1 to 15 had a power ratio x within the range of 4.0 to 13.5. In addition, the decorative sheets according to Examples 1 to 15 had low gloss and excellent resistance to fingerprints, stains, scratches, processability, and weathering. In particular, the decorative sheets according to Examples 13 to 15, which included a transparent resin layer, were able to further improve scratch resistance, processability, and weathering resistance.

[0164] Comparative Examples 1, 3, and 4 did not give the evaluator a moist feel, but rather a smooth feel. The decorative sheets in Comparative Examples 1, 3, and 4 had a power ratio x less than 4.0. Comparative Example 2 did not give the evaluator a moist feel, but rather a rough feel. The decorative sheet in Comparative Example 2 had a power ratio x greater than 13.5. [Explanation of Symbols]

[0165] 1…Decorative sheet, 2…Base layer, 3…Pattern layer, 4…Transparent resin layer, 4a…Embossed pattern, 4b…Adhesive resin layer, 5…Surface protective layer, 5A…Core part, 5B…Ridged part, 6…Primer layer, 11…Decorative material, B…Base material

Claims

1. It comprises a raw material layer and a surface protection layer provided on one surface of the raw material layer, The surface of the aforementioned surface protective layer is provided with an uneven structure including a plurality of ridge-like portions, each of which protrudes in a ridge-like manner. The power spectrum obtained by Fourier transforming the surface shape in the cross-section of the surface protective layer is the average value of the common logarithm of the power in the spatial frequency range of 3000 cycles / mm to 3500 cycles / mm (logPf). ３０００－３５００ The logPf value is the average of the common logarithms of power in the interval between 500 cycles / mm and 1000 cycles / mm for a given spatial frequency. ５００－１０００ The power ratio x is within the range of 4.5 to 8.

0. The surface protective layer comprises a cured product of an ionizing radiation-curable resin, the ionizing radiation-curable resin comprises trimethylolpropane EO-modified triacrylate, and the number of repeating ethylene oxide groups in the trimethylolpropane EO-modified triacrylate is between 6 and 20. The surface protective layer further contains particles, the particles being included in the surface protective layer in an amount of 2 parts by mass or more and 13 parts by mass or less per 100 parts by mass of the ionizing radiation-curable resin. The gloss level of the surface protective layer is less than 10 in this decorative sheet.

2. The decorative sheet according to claim 1, further comprising a pattern layer between the base material layer and the surface protective layer.

3. A decorative sheet according to claim 1 or 2, The base material to which the decorative sheet is attached and A decorative material that has the following features.

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