Decorative sheet

Abstract

Provided is a decorative sheet that imparts a unique tactile sensation. A decorative sheet (1) is provided with a base material layer (2) and a surface protective layer (5) provided on one surface of the base material layer (2). An uneven structure is provided on the surface of the surface protective layer (5). The uneven structure of the surface protective layer (5) has an autocorrelation length Sal of 20 μm or less and a root mean square gradient Sdq of 0.1 or more.

Description

Decorative sheet

[0001] The present invention relates to a decorative sheet.

[0002] Decorative sheets are used for the purpose of imparting design and durability to the surface decoration of interior and exterior materials such as building fixtures, furniture, fixtures, and flooring materials. Decorative sheets are generally widely used as decorative panels that are attached via an adhesive or the like to the surface of substrates such as wood, wood boards, metal plates, non-combustible boards, paper substrates, and resin substrates.

[0003] Designs can be added by forming patterns such as wood grain or stone grain using various printing methods. Plain decorative sheets without patterns are sometimes preferred. The choice of whether to have a pattern or not and the type of pattern vary depending on the application and preference.

[0004] The feel of a decorative sheet is also important for its design. For example, there is a demand for decorative sheets that have a feel similar to that obtained after planing a piece of wood to create a highly smooth surface and then lightly rubbing the planed surface with coarse sandpaper, i.e., a smooth, yet uneven feel that differs from a completely smooth surface. Hereinafter, this kind of feel will also be referred to as the "sanding feel."

[0005] As mentioned above, durability is an important function of decorative sheets, along with providing design. Durability is a comprehensive assessment of scratch resistance, stain resistance, and whether these can be maintained over a long period of time. Requirements vary depending on the environment and situation in which the decorative sheet is used, but decorative sheets with high performance are always in demand.

[0006] To impart durability, a surface protective layer is generally formed on the outermost surface of the decorative sheet, and to adjust the aforementioned gloss, particularly to achieve low gloss, a gloss adjuster (matt additive) is generally added to the surface protective layer.

[0007] As such, a decorative sheet that takes into consideration design (low gloss), scratch resistance, and stain resistance is disclosed in, for example, Patent Document 1.

[0008] Japanese Patent Application Publication No. 2019-119138

[0009] An object of the present invention is to provide a decorative sheet that provides a unique feel to the touch.

[0010] According to one aspect of the present invention, there is provided a decorative sheet comprising an original fabric layer and a surface protective layer provided on one surface of the original fabric layer, wherein a concave-convex structure is provided on the surface of the surface protective layer, and the concave-convex structure of the surface protective layer has an autocorrelation length Sal of 20 μm or less and a root-mean-square gradient Sdq of 0.1 or more.

[0011] According to another aspect of the present invention, there is provided a decorative sheet according to the above aspect, in which the convex area ratio is 40% or less.

[0012] According to yet another aspect of the present invention, there is provided a decorative sheet according to any one of the above aspects, wherein the surface protective layer contains a cured resin and particles.

[0013] According to yet another aspect of the present invention, there is provided a decorative sheet according to the above aspect, wherein the particles are contained in the surface protective layer in an amount of 5 to 10 parts by mass per 100 parts by mass of the resin.

[0014] According to yet another aspect of the present invention, there is provided a decorative sheet according to any one of the above aspects, wherein the resin is an ionizing radiation curable resin.

[0015] According to yet another aspect of the present invention, there is provided a decorative sheet according to any one of the above aspects, wherein the resin is an acrylate.

[0016] According to yet another aspect of the present invention, there is provided a decorative sheet according to any one of the above aspects, wherein the resin includes an acrylate having a functionality of three or less.

[0017] According to yet another aspect of the present invention, there is provided a decorative sheet according to any of the above aspects, wherein the resin contains a trifunctional acrylate, and the amount of the trifunctional acrylate per 100 parts by mass of the resin is 40 parts by mass or more.

[0018] According to yet another aspect of the present invention, there is provided a decorative sheet according to the above aspect, wherein the molecular weight of the trifunctional acrylate is in the range of 360 to 1,135.

[0019] According to yet another aspect of the present invention, there is provided a decorative sheet according to the above aspect, wherein the resin further comprises a difunctional acrylate, and the amount of the difunctional acrylate per 100 parts by mass of the resin is 40 parts by mass or more.

[0020] According to yet another aspect of the present invention, there is provided a decorative sheet according to the above aspect, wherein the molecular weight of the bifunctional acrylate is within the range of 250 to 850.

[0021] According to yet another aspect of the present invention, there is provided a decorative sheet according to any of the above aspects, wherein the resin further contains an acrylate having five or more functionalities, and the amount of the acrylate having five or more functionalities is 3 parts by mass or more and 20 parts by mass or less.

[0022] According to yet another aspect of the present invention, there is provided a decorative sheet according to any of the above aspects, wherein the resin comprises a tetrafunctional acrylate, the amount of the tetrafunctional acrylate per 100 parts by mass of the resin is 40 parts by mass or more, and the molecular weight of the tetrafunctional acrylate is in the range of 1800 to 2000.

[0023] According to yet another aspect of the present invention, there is provided a decorative sheet according to any one of the above aspects, wherein the thickness t of the surface protective layer is 3 μm or more and 10 μm or less.

[0024] According to yet another aspect of the present invention, there is provided a decorative sheet according to any one of the above aspects, wherein the gloss of the surface protective layer is 5 or less.

[0025] According to yet another aspect of the present invention, there is provided a decorative sheet according to any one of the above aspects, further comprising a design layer between the base layer and the surface protective layer.

[0026] According to yet another aspect of the present invention, there is provided a decorative material comprising a decorative sheet according to any one of the above aspects and a substrate to which the decorative sheet is attached.

[0027] According to yet another aspect of the present invention, there is provided a method for producing a decorative sheet, comprising: forming a coating film on an original layer, the coating film being made of a coating liquid containing an ionizing radiation curable resin and particles; carrying out a first irradiation step of irradiating the coating film with light having a wavelength of 200 nm or less; and then carrying out a second irradiation step of irradiating the coating film with ionizing radiation or ultraviolet light having a wavelength longer than that of the light irradiated in the first irradiation step, wherein the first irradiation step is carried out so that after the second irradiation step, the autocorrelation length Sal of the surface of the coating film is 20 μm or less and the root-mean-square gradient Sdq is 0.1 or more.

[0028] According to the present invention, a decorative sheet that provides a unique feel to the touch is provided.

[0029] Fig. 1 is a cross-sectional view of a decorative material including a decorative sheet according to one embodiment of the present invention. Fig. 2 is a cross-sectional view of a surface protective layer included in the decorative sheet of Fig. 1. Fig. 3 is a microscope image of a surface protective layer included in a decorative sheet according to one example of the present invention.

[0030] Hereinafter, embodiments of the present invention will be described with reference to the drawings. The embodiments described below are more specific embodiments of any of the above aspects. The following items can be incorporated into each of the above aspects, either singly or in combination.

[0031] Furthermore, the embodiments shown below are merely examples of configurations for embodying the technical idea of ​​the present invention, and the technical idea of ​​the present invention is not limited by the materials, shapes, structures, etc. of the components described below. Various modifications can be made to the technical idea of ​​the present invention within the technical scope defined by the claims.

[0032] In the drawings, elements having the same or similar functions are denoted by the same reference numerals, and redundant explanations will be omitted. Furthermore, the drawings are schematic, and the relationship between dimensions in one direction and dimensions in another direction, and the relationship between the dimensions of one member and the dimensions of another member, etc. may differ from the actual relationship.

[0033] <1> Decorative material and decorative sheet Fig. 1 is a cross-sectional view of a decorative material including a decorative sheet according to one embodiment of the present invention. Fig. 2 is a cross-sectional view of a surface protective layer included in the decorative sheet of Fig. 1. Fig. 3 is a micrograph of a surface protective layer included in a decorative sheet according to one example of the present invention.

[0034] The cross section shown in Fig. 2 is a cross section along the thickness direction of the surface protection layer, and the micrograph in Fig. 3 is a plan view photograph obtained by a laser microscope (OLS-4000 manufactured by Olympus Corporation).

[0035] The decorative material 11 shown in Figure 1 includes a substrate B and a decorative sheet 1 attached thereto. Here, the decorative material 11 is a decorative board. The decorative board may be a flat plate, or may be curved or folded. The decorative material 11 may have a shape other than a plate.

[0036] Here, the substrate B is a plate material. The plate material is, for example, a wood board, an inorganic board, a metal plate, or a composite board made of multiple materials. The substrate B may have a shape other than a plate.

[0037] The decorative sheet 1 includes a base fabric layer 2, a design layer 3, a transparent resin layer 4, a surface protective layer 5, an adhesive layer 7, a primer layer 6, and a concealing layer 8. The design layer 3, adhesive layer 7, transparent resin layer 4, and surface protective layer 5 are provided in this order from the base fabric layer 2 side on the surface of the base fabric layer 2 opposite the surface facing the substrate B. The concealing layer 8 and primer layer 6 are provided in this order from the base fabric layer 2 side on the surface of the base fabric layer 2 facing the substrate B. One or more of the design layer 3, transparent resin layer 4, primer layer 6, adhesive layer 7, and concealing layer 8 may be omitted. Below, the elements included in the decorative sheet 1 will be explained in order.

[0038] <1.1> Raw Fabric Layer The raw fabric layer 2 or its material can be any material selected from, for example, paper, synthetic resin, synthetic resin foam, 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 fabric include organic and inorganic nonwoven fabrics. Examples of metals for the metal foil include aluminum, iron, gold, and silver.

[0039] The thickness of the raw fabric layer 2 is preferably in the range of 20 μm to 250 μm, taking into consideration the printing workability and costs.

[0040] <1.2> Primer Layer When an olefin-based resin is used as the material of the raw fabric layer 2, the surface of the raw fabric layer 2 is often in an inactive state. Therefore, in this case, it is preferable to provide a primer layer 6 between the raw fabric layer 2 and the substrate B. When the raw fabric layer 2 is made of an olefin-based material, the primer layer 6 may be omitted, and the raw fabric layer 2 may be subjected to a surface modification treatment such as corona treatment, plasma treatment, ozone treatment, electron beam treatment, ultraviolet treatment, or dichromate treatment in order to improve the adhesion between the raw fabric layer 2 and the substrate B.

[0041] Materials that can be used for the primer layer 6 include, for example, the materials described below for the design layer 3. Since the primer layer 6 is applied to the back surface of the decorative sheet 1, and considering that the decorative sheet 1 will be wound up in web form, an inorganic filler may be added to the primer layer 6 to avoid blocking and increase adhesion to the adhesive. Examples of inorganic fillers include silica, alumina, magnesia, titanium oxide, and barium sulfate.

[0042] <1.3> Concealing Layer To provide the decorative sheet 1 with concealing properties for the substrate B, for example, a colored sheet is used as the base layer 2, or an opaque concealing layer 8 is provided. The concealing layer 8 can be made of, for example, the same material as that used for the design layer 3, which will be described later. However, since the purpose of the concealing layer 8 is to provide concealing properties, it is preferable to use, for example, an opaque pigment, titanium oxide, iron oxide, or the like, as the pigment. Furthermore, to improve concealing properties, metals such as gold, silver, copper, and aluminum can also be added to the material of the concealing layer 8. Generally, flake-shaped aluminum pieces are often added.

[0043] <1.4> Design Layer The design layer 3 is a layer formed by printing a design onto the base layer 2 using ink. Examples of ink binders include soluble nitrocellulose, cellulose, vinyl chloride-vinyl acetate copolymer, polyvinyl butyral, polyurethane, acrylic, polyesters, and modified versions thereof, either alone or in combination. The binder may be aqueous, solvent-based, or emulsion-based, and may be a one-component type or a two-component type incorporating a curing agent. The design layer 3 may be formed by curing a layer formed with a curable ink by exposure to ultraviolet light, electron beams, or the like. The most common method is to use a urethane-based ink that is cured with an isocyanate. The ink used to form the design layer 3 may further contain, in addition to the binder, pigments and colorants such as dyes, extender pigments, solvents, and various additives typically found in inks. Examples of versatile pigments include condensed azo, insoluble azo, quinacridone, isoindoline, anthraquinone, imidazolone, cobalt, phthalocyanine, carbon, titanium oxide, iron oxide, and pearl pigments such as mica.

[0044] In addition to applying ink, it is also possible to apply a design to the pattern layer 3 by vapor deposition or sputtering of various metals. In particular, it is preferable that a light stabilizer be added to the ink. This can suppress deterioration of the decorative sheet 1 itself caused by light degradation of the ink, and extend the life of the decorative sheet 1.

[0045] In the decorative sheet 1 shown in Figure 1, the pattern layer 3 is provided between the base fabric layer 2 and the adhesive layer 7, but it can be provided at any position between the base fabric layer 2 and the surface protective layer 5. The pattern layer 3 has, for example, a wood grain pattern. When the pattern layer 3 has a wood grain pattern, the user can get a wood-like tactile sensation from the visual information. The pattern layer 3 may be omitted.

[0046] <1.5> Adhesive Layer The adhesive layer 7 is also called a heat-sensitive adhesive layer, an anchor coat layer, or a dry lamination adhesive layer.

[0047] The resin material for the adhesive layer 7 is not particularly limited, and can be appropriately selected from acrylic, polyester, polyurethane, epoxy, and other resin materials. Furthermore, an ethylene-vinyl acetate copolymer resin adhesive can also be used as the resin material for the adhesive layer 7. The coating method can be appropriately selected depending on the viscosity of the adhesive. Generally, gravure coating is used, and the adhesive layer 7 is formed on the upper surface of the design layer 3 by gravure coating, and then the transparent resin layer 4 is laminated. The adhesive layer 7 can be omitted if sufficient adhesive strength can be obtained between the transparent resin layer 4 and the design layer 3.

[0048] <1.6> Transparent Resin Layer An olefin-based resin is preferably used as the resin material for the transparent resin layer 4. Examples of the olefin-based resin include polypropylene, polyethylene, polybutene, and the like, as well as α-olefins (e.g., 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, 4-ethyl-1-hexene, 3 Examples of the copolymer include homopolymers of α-olefins such as 9-ethyl-1-hexene, 9-methyl-1-decene, 11-methyl-1-dodecene, and 12-ethyl-1-tetradecene, or copolymers of two or more of these, 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.

[0049] Furthermore, in order to improve the surface strength of the decorative sheet 1, it is preferable to use highly crystalline polypropylene as the resin for the transparent resin layer 4. Note that, if necessary, various additives such as heat stabilizers, light stabilizers, antiblocking agents, catalyst scavengers, colorants, light scattering agents, and gloss adjusters can also be added to the transparent resin layer 4. Generally, phenol-based, sulfur-based, phosphorus-based, hydrazine-based, and other heat stabilizers are added, and hindered amine-based, and other light stabilizers are added, in any combination.

[0050] <1.7> Surface Protection Layer The surface protection layer 5 includes a core portion 5A and a plurality of ridge portions 5B each protruding in a ridge shape from one surface of the core portion 5A. These ridge portions 5B form an uneven structure.

[0051] Here, in the decorative sheet 1 according to this embodiment, the term "ridge-like" refers to a convex shape that is linear in plan view. The ridge portions 5B may be curved or linear in plan view, but are preferably curved in view of the fingerprint resistance of the decorative sheet 1. Each ridge portion 5B may be branched or unbranched in plan view. In addition, in the present disclosure, the ridge portions 5B refer to, for example, the portion from the lowest point to the tip of the uneven shape provided on the surface of the surface protective layer 5, and the core portion 5A refers to the portion of the surface protective layer 5 excluding the ridge portions 5B.

[0052] The ridge portions 5B are curved, and at least some of them are adjacent to each other in the width direction, as shown in Fig. 3. At a position where at least some of the ridge portions 5B are adjacent to each other in the width direction, the cross section of the surface protective layer 5 parallel to the width direction and the thickness direction of the surface protective layer 5 has a wave shape, such as a sine wave shape, in the portion where the uneven structure is provided, as shown in Fig. 2.

[0053] The surface protective layer 5 preferably covers the entire upper surface of the underlying layer (the transparent resin layer 4 in this embodiment) that contacts the surface protective layer 5. That is, in the decorative sheet 1 according to this embodiment, it is preferable that the underlying layer that contacts the surface protective layer 5 (i.e., the transparent resin layer 4) is not exposed on the surface.

[0054] The concave-convex structure of the surface protection layer 5 has an autocorrelation length Sal of 20 μm or less. The autocorrelation length Sal is, for example, 5.5 μm or more. The autocorrelation length Sal is preferably 5.5 μm or more and 15.0 μm or less, and more preferably 5.5 μm or more and 7.4 μm or less.

[0055] Here, the autocorrelation length Sal is the shortest distance at which the autocorrelation function decays to 0.2. The autocorrelation function is a function that indicates the correlation between a certain surface texture surface and a surface texture surface obtained by moving that surface texture surface by (tx, ty) in the reference region (A). The autocorrelation length represents the period of the uneven structure. When the autocorrelation length Sal is large, gentle unevenness predominates in the uneven structure. When the autocorrelation length Sal is small, steep unevenness predominates in the uneven structure. Therefore, when the autocorrelation length Sal is within the above range, the uneven structure has a fine structure. The autocorrelation length Sal is a surface texture parameter defined in ISO 25178-2:2021.

[0056] The uneven structure of the surface protection layer 5 has a root-mean-square gradient Sdq of 0.1 or more. The root-mean-square gradient Sdq is, for example, 0.4 or less. The root-mean-square gradient Sdq is preferably 0.15 or more and 0.6 or less, and more preferably 0.27 or more and 0.6 or less.

[0057] The root-mean-square gradient Sdq is the root-mean-square of the local gradient in a reference region. The root-mean-square gradient Sdq is a parameter that can be used to evaluate the magnitude of the local gradient. Specifically, the root-mean-square gradient Sdq quantifies the steepness of the convex or concave portions included in the uneven structure. When the root-mean-square gradient Sdq is large, the gradient of the convex or concave portion is steep. The root-mean-square gradient Sdq is a surface texture parameter defined in ISO 25178-2:2021.

[0058] The root mean square gradient Sdq is expressed by the following equation 1.

[0059]

[0060] Here, A denotes the reference region.

[0061] The uneven structure of the surface protective layer 5 has a convex area ratio of 40% or less, as described below. The convex area ratio is, for example, 30% or less. The convex area ratio is preferably 25% or more and 34% or less, and more preferably 25% or more and 30% or less.

[0062] The convex portion area ratio is a numerical value in percentage expressed by the following formula 2: Convex portion area ratio=(Smr1 / 100)×V / Spk / S×100 Formula 2 Here, Smr1 is the load area ratio in percentage at the point where the line separating the protruding peak portion of the evaluation area from the core portion of the profile curve intersects with the load curve.

[0063] The areal load ratio Smr1 is preferably 7% or more and 30% or less, and more preferably 15% or more and 30% or less. Smr1 is a surface texture parameter defined in ISO 25178-2:2021.

[0064] V is the volume of the entire shape above the minimum height in the evaluation area. The volume V is, for example, 0.21 mm ３ More than 1.2 mm ３ The volume V can be measured by integrating the height of the entire region with the minimum height of the shape image obtained by the laser microscope as the reference.

[0065] Spk is the average height of the protruding peaks. The average height Spk of the protruding peaks is preferably 0.8 μm or more and 5.1 μm or less, and more preferably 2.5 μm or more and 5.1 μm or less. The average height Spk of the protruding peaks is a surface texture parameter defined in ISO 25178-2:2021.

[0066] S is the surface area of ​​the evaluation area. The surface area S is 0.08 mm ２ More than 0.14 mm ２ Preferably, it is 0.1 mm or less. ２ More than 0.14 mm ２ It is more preferable that the surface area S is expressed by the following formula 3.

[0067]

[0068] where A is the reference area.

[0069] The convex area ratio corresponds to the ratio, expressed as a percentage, of the total area of ​​the upper surface of the rectangular parallelepiped, assuming that each of the multiple convex shapes contained in the concave-convex structure is a rectangular parallelepiped, to the area of ​​the concave-convex structure itself.

[0070] The thickness t of the surface protective layer 5 is preferably 10 μm or less. The thickness t of the surface protective layer 5 is more preferably 3 μm or more and 10 μm or less. If the thickness of the surface protective layer 5 is too small or too large, it becomes difficult to achieve a "sanding feel." Here, the thickness of the surface protective layer 5 is determined by observing the cross section with a scanning electron microscope and averaging the values ​​at 25 points. Specifically, the thickness of the surface protective layer 5 can be determined as described in the examples below. Note that when the coating liquid for the surface protective layer described below does not contain a solvent, the thickness of the coating film made of the coating liquid for the surface protective layer is equal to the thickness of the surface protective layer 5.

[0071] The surface protective layer 5 preferably contains a cured resin and particles. The resin contained in the surface protective layer 5 is preferably an ionizing radiation curable resin. Here, "ionizing radiation" refers to a charged particle beam such as an electron beam. The ionizing radiation curable resin is cured by irradiation with ionizing radiation. The ionizing radiation curable resin can also be cured by irradiation with ultraviolet light. The ionizing radiation curable resin used here is cured by irradiation with light having a wavelength of 200 nm or less, and has a large absorption coefficient for this light.

[0072] The amount of the cured ionizing radiation curable resin in the surface protective layer 5 is preferably 60% by mass or more, more preferably 70% by mass or more, and even more preferably 80% by mass or more. As the ionizing radiation curable resin, known resins such as various monomers and commercially available oligomers can be used, including (meth)acrylic resins, silicone resins, polyester resins, urethane resins, amide resins, and epoxy resins. The ionizing radiation curable resin may be either an aqueous resin or a non-aqueous (organic solvent-based) resin.

[0073] The main component of the ionizing radiation curable resin is preferably an acrylate. Here, the main component of the ionizing radiation curable resin means a component that accounts for 60 mass% or more of the ionizing radiation curable resin. The ionizing radiation curable resin preferably contains 70 mass parts or more of acrylate, more preferably 80 mass parts or more. The ionizing radiation curable resin is more preferably an acrylate.

[0074] The acrylate preferably contains a trifunctional or lower acrylate. The proportion of the trifunctional or lower acrylate per 100 parts by mass of the ionizing radiation curable resin is preferably 50 parts by mass or more, more preferably 70 parts by mass or more. The above proportion is, for example, 90 parts by mass or less. If the amount of the trifunctional or lower acrylate is too small, it is difficult to achieve a sanding effect. Furthermore, in this case, reflections are likely to occur when the user looks at the decorative sheet 1.

[0075] The acrylate preferably contains a trifunctional acrylate. The proportion of the trifunctional acrylate in 100 parts by mass of the ionizing radiation curable resin is preferably 40 parts by mass or more, more preferably 60 parts by mass or more. The proportion is, for example, 90 parts by mass or less.

[0076] The acrylate preferably contains a bifunctional acrylate in addition to a trifunctional acrylate. In this case, the proportion of the bifunctional acrylate in 100 parts by mass of the ionizing radiation curable resin is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and even more preferably 40 parts by mass or more. The proportion is, for example, 80 parts by mass or less.

[0077] According to one example, the acrylate comprises a difunctional acrylate and a trifunctional acrylate. In this case, the proportion of the trifunctional acrylate in 100 parts by mass of the ionizing radiation curable resin is preferably 40 parts by mass or more and 90 parts by mass or less. In this way, the acrylate preferably contains a plurality of acrylates having different numbers of functional groups.

[0078] The acrylate preferably further contains a pentafunctional or higher acrylate in addition to a trifunctional or lower acrylate. The proportion of the pentafunctional or higher acrylate in 100 parts by mass of the ionizing radiation curable resin is preferably 3 parts by mass or more and 20 parts by mass or less, and more preferably 5 parts by mass or more and 10 parts by mass or less.

[0079] According to one example, the acrylate comprises a trifunctional acrylate and a pentafunctional or higher acrylate, for example, a pentafunctional or hexafunctional acrylate.

[0080] The acrylate may contain a tetrafunctional acrylate. The proportion of the tetrafunctional acrylate in 100 parts by mass of the ionizing radiation curable resin is, for example, 40 parts by mass or more. The proportion is, for example, 80 parts by mass or less.

[0081] The acrylate preferably contains a repeating unit. This repeating unit is, for example, any one of an ethylene oxide (EO) unit, a propylene oxide (PO) unit, and an ε-caprolactone (CL) unit. The repeating unit is preferably ethylene oxide or propylene oxide. In the acrylate, the repeating unit may be present between the acryloyl group and the methylol group in an open ring state.

[0082] The number of repetitions of the repeating structure is preferably 3 or more per acryloyl group. However, when the number of functional groups is 2 or less, it is preferably 3 or more across the board. If an acrylate with a high number of repetitions is used, the cured film is more likely to expand in the in-plane direction during the first irradiation step described below, and at the same time, the cured film is more likely to buckle, thereby making it easier for wrinkles corresponding to the ridge portions 5B to form on the coating film surface. Furthermore, if an acrylate with a high number of repetitions is used, the gloss value tends to decrease and the design tends to improve. However, if the number of repetitions is increased, the crosslinking density may decrease, and the scratch resistance of the surface protective layer may decrease. Furthermore, if an acrylate with a low number of repetitions is used, it may be difficult to achieve high processability.

[0083] Examples of trifunctional acrylates containing repeating units include EO-modified, PO-modified, or CL-modified trimethylolpropane triacrylate, glycerin triacrylate, isocyanurate triacrylate, or pentaerythritol triacrylate. In trifunctional acrylates containing repeating units, the number of repeating units is preferably 9 or more and 15 or less. The molecular weight of the trifunctional acrylates containing repeating units is, for example, in the range of 690 or more and 1200 or less, and, for another example, in the range of 360 or more and 1135 or less.

[0084] The bifunctional acrylate containing a repeating unit is, for example, polyethylene glycol diacrylate or polypropylene glycol diacrylate, and may contain a caprolactone structure. In the bifunctional acrylate containing a repeating unit, the number of repeating units is preferably 3 or more and 14 or less. The molecular weight of the bifunctional acrylate containing a repeating unit is, for example, in the range of 250 or more and 850 or less.

[0085] An example of a pentafunctional or higher acrylate containing a repeating unit is dipentaerythritol polyacrylate. In the pentafunctional or higher acrylate containing a repeating unit, the number of repeating units is preferably 12 or less. The molecular weight of the pentafunctional or higher acrylate containing a repeating unit is, for example, in the range of 560 to 1200.

[0086] The acrylate may include a tetrafunctional acrylate containing a repeating unit. The tetrafunctional acrylate containing a repeating unit is, for example, EO-modified, PO-modified, or CL-modified pentaerythritol tetraacrylate. In the tetrafunctional acrylate containing a repeating unit, the number of repeating units is preferably 20 or more and 25 or less. The molecular weight of the tetrafunctional acrylate containing a repeating unit is, for example, in the range of 1,800 or more and 2,000 or less.

[0087] The number of repetitions of the repeating structure can be analyzed using MALDI-TOF-MS. Ionizing radiation curable resins may have a molecular weight distribution. When a molecular weight distribution exists, the number of repetitions is determined to be the number of repetitions corresponding to the molecular weight having the strongest peak in the MALDI-TOF-MS mass spectrum.

[0088] The particles contained in the surface protective layer 5 may be, for example, particles made of an organic material such as polyethylene (PE) wax, polypropylene (PP) wax, or resin beads, or particles made of an inorganic material such as silica, glass, alumina, titania, zirconia, calcium carbonate, or barium sulfate. When the surface protective layer 5 contains particles, a sanding feel is easily obtained.

[0089] The particles preferably have an average particle size (D50) of 3 μm or more, more preferably 3 μm or more and 11 μm or less, and even more preferably 3 μm or more and 8 μm or less.

[0090] When the surface protective layer 5 contains particles, wrinkles can be more uniformly generated on the coating surface in the first irradiation step described below. As the average particle size (D50) of the particles increases, the user tends to feel a stronger sense of particle unevenness. Therefore, if the average particle size (D50) is too large, it becomes difficult to achieve a "sanding feel." Furthermore, as the average particle size (D50) of the particles increases, particles tend to fall off easily from the surface protective layer 5, making it difficult to achieve high scratch resistance. Furthermore, when the particles are small, the effect of generating wrinkles uniformly tends to be reduced. Furthermore, when the particles are small, it becomes difficult to achieve a sanding feel.

[0091] Here, the "average particle size (D50)" refers to the median size (D50) measured using a laser diffraction / scattering particle size distribution analyzer. When the coating liquid for the surface protective layer contains particles, the surface protective layer 5 obtained from this coating liquid will also contain particles. The average particle size of the particles contained in the surface protective layer 5 can be determined by observing the cross section of the layer and averaging the particle sizes of multiple particles. The value obtained in this manner is substantially the same as the median size (D50) measured using a laser diffraction / scattering particle size distribution analyzer. Therefore, the above-mentioned range of average particle size can also be interpreted as the range of average particle sizes of the particles contained in the surface protective layer 5.

[0092] The particles are preferably contained in the surface protective layer 5 in an amount of 5 to 10 parts by mass per 100 parts by mass of the resin. The amount of particles added is more preferably 5 to 7 parts by mass per 100 parts by mass of the resin. Note that "100 parts by mass of the resin" refers to the parts by mass of the solid content of the resin.

[0093] When the amount of particles added is within the above range, wrinkles can be more uniformly formed on the coating surface in the first irradiation step described below, resulting in a reduction in gloss and an improvement in design properties.

[0094] If the amount of particles added is too large, it may be difficult to achieve high stain resistance. Also, if the amount of particles added is too small, the effect of generating wrinkles uniformly may be reduced. Therefore, if the amount of particles added is too small, it may be difficult to achieve a "sanding feel."

[0095] The glossiness of the surface protective layer 5 is preferably less than 10.0, and more preferably equal to or less than 5. Here, the "glossiness" is a value measured at an incident angle of 60 degrees using a glossmeter in accordance with JIS Z8741:1997.

[0096] <2> Manufacturing Method of Decorative Sheet The decorative sheet 1 is manufactured, for example, by the following method. For the sake of brevity, explanations of the design layer 3, transparent resin layer 4, primer layer 6, adhesive layer 7, and hiding layer 8 are omitted here.

[0097] First, a coating liquid for forming a surface protective layer is prepared and stirred. The coating liquid for forming a surface protective layer contains, for example, the above-mentioned resin and the above-mentioned particles. Here, the main component of the resin is assumed to be acrylate.

[0098] The coating liquid for the surface protective layer may further contain a solvent and additives for improving the functionality of the final product, such as an antibacterial agent and an antifungal agent. The coating liquid for the surface protective layer may further contain other additives such as an ultraviolet absorber and a light stabilizer. Examples of ultraviolet absorbers that can be used include benzotriazoles, benzoates, benzophenones, and triazines. Examples of light stabilizers that can be used include hindered amines. Note that, according to the method described herein, a surface protective layer 5 having a low gloss can be formed without a gloss adjuster (matt additive).

[0099] In the second irradiation step described below, when the entire coating film made of the coating liquid for surface protective layer is cured by ultraviolet irradiation, it is preferable that the coating liquid for surface protective layer further contains a photoinitiator. The photoinitiator is not particularly limited, but examples thereof include benzophenone-based, acetophenone-based, benzoin ether-based, and thioxanthone-based photoinitiators.

[0100] Next, a coating film made of a coating liquid for the surface protective layer is formed on one surface of the raw fabric layer 2. This coating film can be formed by various printing methods such as gravure printing, offset printing, screen printing, electrostatic printing, and inkjet printing, or various coating methods such as roll coating, knife coating, microgravure coating, and die coating.

[0101] After forming a coating film made from the coating liquid for a surface protective layer, a first irradiation step is carried out. In the first irradiation step, the coating film is irradiated with light having a wavelength of 200 nm or less (hereinafter referred to as first radiation). The ionizing radiation curable resin contained in the coating liquid for a surface protective layer has a large absorption coefficient for the first radiation. Therefore, the first radiation incident on the coating film can only reach a position several tens to several hundreds of nanometers away from the outermost surface. Therefore, in the first irradiation step, a crosslinking reaction proceeds in the surface region of the coating film, forming an extremely thin cured film, while in other regions, the crosslinking reaction does not proceed and the coating film remains semi-cured.

[0102] The coating film after the first irradiation step has wrinkles on its surface corresponding to the ridge portions 5 B. The present inventors believe that the reason why wrinkles are formed on the coating film surface by the first irradiation step is as follows.

[0103] As described above, the first radiation can only reach a position tens to hundreds of nanometers away from the outermost surface of the coating film. That is, the crosslinking reaction of the ionizing radiation-curable resin caused by irradiation with the first radiation occurs only on the surface of the coating film, and regions at a distance of more than tens to hundreds of nanometers from the outermost surface are partially uncured, resulting in the presence of highly fluid molecules. These highly fluid molecules swell the cured film, thereby increasing its volume. The increase in volume in the in-plane direction generates in-plane compressive stress, causing the cured film to buckle, resulting in wrinkles on the surface of the coating film.

[0104] The first radiation can be extracted from excimer VUV (Vacuum Ultra Violet) light. Excimer VUV light can be generated from a lamp using a rare gas or a rare gas halide compound. When high-energy electrons are externally applied to a lamp filled with a rare gas or a rare gas halide compound, a large number of discharge plasmas (dielectric barrier discharges) are generated. This plasma discharge excites atoms of the discharge gas (rare gas), which momentarily transition to an excimer state. When returning from this excimer state to the ground state, light is emitted in a wavelength range specific to the excimer.

[0105] The gas used in the excimer lamp may be any conventional gas that emits light of 200 nm or less. Examples of the gas include rare gases such as Xe, Ar, and Kr, and mixtures of rare gases such as ArBr and ArF with halogen gases. The wavelength (center wavelength) of excimer lamps varies depending on the gas, and examples include wavelengths of approximately 172 nm (Xe), approximately 126 nm (Ar), approximately 146 nm (Kr), approximately 165 nm (ArBr), and approximately 193 nm (ArF).

[0106] Considering the magnitude of photon energy and the difference between wavelength and bond energy of organic matter, it is preferable to use a xenon lamp that emits excimer light with a central wavelength of 172 nm as the light source. Also, considering the cost of maintaining the equipment and the availability of materials, it is preferable to use a xenon lamp as the light source.

[0107] The first irradiation step is carried out in an atmosphere with a low oxygen concentration. Oxygen has a high absorption coefficient for light of 200 nm or less. Therefore, the first irradiation step is preferably carried out in, for example, a nitrogen gas atmosphere. The oxygen concentration in the gas phase in the first irradiation step, i.e., the residual oxygen concentration in the reaction atmosphere, is preferably 100 ppm or less, and more preferably 20 ppm or less.

[0108] 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. Therefore, changing the residual oxygen concentration in the reaction atmosphere can also change the surface properties of the surface protective layer 5.

[0109] The integrated light amount of the first radiation is 8 mJ / cm ２ 20mJ / cm or more ２ It is preferable that the dose is 10 mJ / cm or less. ２ More than 17mJ / cm ２ It is more preferable that the integrated amount of light is set to the following: When the integrated amount of light is reduced, it is easier to obtain the surface protection layer 5 having the above-described surface properties.

[0110] The first irradiation step is preferably carried out within a temperature range of 20° C. to 65° C. When the temperature in the first irradiation step is within the above range, it is easy to obtain a surface protection layer 5 having the above surface properties.

[0111] After the first irradiation step is completed, the second irradiation step is carried out. In the second irradiation step, the coating film is irradiated with a second radiation to cure the entire coating film. In this way, the surface protective layer 5 is obtained.

[0112] The second radiation is ionizing radiation such as an electron beam, or ultraviolet radiation having a longer wavelength than the first radiation.

[0113] The cumulative amount of the second radiation is 10 mJ / cm ２ More than 500mJ / cm ２ It is preferable that the dose is 50 mJ / cm or less. ２ More than 400mJ / cm ２ More preferably, it is 100 mJ / cm or less. ２ More than 300mJ / cm ２ It is more preferable that:

[0114] The decorative sheet 1 can be produced by, for example, the method described above. The decorative sheet 1 may also be produced by other methods. For example, a plate may be formed using the method described above for the surface protective layer 5, and the surface protective layer 5 having a relief structure on its surface may be formed by transfer using this plate.

[0115] <3> Effects The decorative sheet 1 described with reference to Figures 1 to 3 has the surface protective layer 5 with the above-mentioned surface properties. Such a decorative sheet 1 can provide a unique tactile sensation to the user. For example, when a user presses the surface of the surface protective layer 5 with their finger and then slides their finger over the surface of the decorative sheet 1 described above, the user is given a smooth, yet uneven, textured sensation that differs from a completely smooth surface, i.e., a "sanding sensation." This tactile sensation will be explained below.

[0116] In the decorative sheet 1 described above, the autocorrelation length Sal of the concave-convex structure of the surface protective layer 5 is within the above-mentioned range. Therefore, the concave-convex structure has a small pitch. Therefore, when a user presses the surface of the surface protective layer 5 with their finger and slides their finger across the surface, the user can be given a smooth feel.

[0117] Furthermore, the decorative sheet 1 described above has a root-mean-square gradient Sdq of the uneven structure within the above-mentioned range. Furthermore, the decorative sheet 1 described above has a convex area ratio within the above-mentioned range. The convex portions forming this uneven structure are moderately steep, and their peaks are moderately small. Therefore, when a user slides their finger over the surface of the surface protective layer 5, the decorative sheet 1 stimulates the user's finger, giving the user a sense of unevenness.

[0118] In this way, when the autocorrelation length Sal of the uneven structure is within the above-mentioned range, the decorative sheet 1 provides a smooth feel to the user, and when the root-mean-square gradient Sdq and the convex area ratio of the uneven structure are within the above-mentioned range, the decorative sheet 1 provides a sense of unevenness to the user. Therefore, while the decorative sheet 1 is smooth, it provides a sense of unevenness to the user that is different from a completely smooth surface, i.e., a "sanding feel."

[0119] A decorative sheet that provides a sanded appearance preferably has low gloss. However, if an attempt is made to achieve low gloss by providing a textured structure on the decorative sheet to make it less likely to generate specular reflection, diffuse reflection may occur, causing the surface protective layer 5 to appear cloudy.

[0120] On the other hand, the decorative sheet 1 described above has the above-mentioned surface properties, and therefore diffuse reflection and glare are less likely to occur in the surface protective layer 5. This will be explained below.

[0121] For example, in the decorative sheet 1 described above, the autocorrelation length Sal of the uneven structure is within the above-mentioned range. Furthermore, in the decorative sheet 1 described above, the root-mean-square gradient Sdq of the uneven structure is within the above-mentioned range. Such an uneven structure has a relatively large number of convex portions, and the slopes of the convex portions are moderately steep, so that light incident on the convex portions easily penetrates into the surface protective layer 5. Therefore, diffuse reflection and specular reflection are unlikely to occur in the surface protective layer 5. Therefore, clouding of the surface protective layer 5 due to diffuse reflection is unlikely to occur. Furthermore, because specular reflection is unlikely to occur, glare is also unlikely to occur.

[0122] Because the surface protective layer 5 of the decorative sheet 1 has the above-described surface properties, it can achieve a low gloss even without containing a gloss adjuster (matt additive). Because gloss adjusters reduce the oil repellency of layers formed from resin materials, surface protective layers 5 containing gloss adjusters are prone to fingerprints. Surface protective layers 5 that do not contain gloss adjusters are less likely to absorb oil and therefore less likely to be marked with fingerprints. Furthermore, surface protective layers 5 with excellent oil repellency are less likely to develop oil stains or adsorb contaminants. Furthermore, surface protective layers 5 that do not contain gloss adjusters do not lose gloss adjuster particles when their surface is scratched, and therefore decorative sheets 1 containing such surface protective layers 5 are less likely to develop gloss changes or scratches.

[0123] Furthermore, as described above, the surface protective layer 5 can achieve a low glossiness, which can reduce reflection of external light on the surface of the surface protective layer 5.

[0124] Furthermore, the reason why the surface protection layer 5 having the above-described surface properties can be obtained by the above-described method is believed to be due to the following reasons in addition to those explained above.

[0125] In the first irradiation step, oxygen in the gas phase not only absorbs short-wavelength ultraviolet light but also inhibits radical polymerization. The effect of oxygen contained in the gas phase on radical polymerization is greatest in the portion of the coating film made of an 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, it is possible to change the relationship between the distance from the coating film surface and the progress of the crosslinking reaction.

[0126] If this relationship changes, the thickness of the cured film formed on the surface of the coating film by the first irradiation step and the degree of in-plane expansion of the cured film according to the progress of the crosslinking reaction will change. The integrated light amount in the first irradiation step also affects the thickness of the cured film and the degree of in-plane expansion of the cured film. The thickness of the cured film and the degree of in-plane expansion of the cured film also affect the surface properties of the surface protective layer. Furthermore, the amount of particles added in the coating film and the thickness of the coating film also affect the formation of wrinkles.

[0127] Therefore, for example, by appropriately setting the composition of the ionizing radiation curable resin, the amount of particles added, the thickness of the coating film, the oxygen concentration in the gas phase in the first irradiation step, and the integrated light amount in the first irradiation step, it is possible to obtain a surface protection layer having the desired surface properties.

[0128] The following describes examples of the present invention.

[0129] 1 to 3 was produced by the following method. In this example, the transparent resin layer 4, primer layer 6, adhesive layer 7, and hiding layer 8 were omitted.

[0130] First, the basis weight is 50 g / m ２ An impregnated paper (GFR-506, manufactured by Kojin Co., Ltd.) was prepared as the raw fabric layer 2. A design layer 3 was formed on one surface of the raw fabric layer 2 using an oil-based nitrocellulose resin gravure printing ink (PCNT (PCRNT) various colors, manufactured by Toyo Ink Co., Ltd.). The design pattern of the design layer was a wood grain pattern.

[0131] Next, a coating liquid for a surface protective layer was prepared. The coating liquid for the surface protective layer was prepared by blending the following ionizing radiation curable resins A and B with the following particles. Ionizing radiation curable resin A Type: Trimethylolpropane EO-modified triacrylate (EO 15 moles added) Product name: SR9035 (manufactured by Sartomer) Blend: 97 parts by mass Ionizing radiation curable resin B Type: Dipentaerythritol polyacrylate Product name: A-DPH (manufactured by Shin-Nakamura Chemical Co., Ltd.) Blend: 3 parts by mass Particles Product name: SYLYSIA320 (manufactured by Fuji Silysia Chemical Ltd.) Particle size: 3.2 μm Blend: 5 parts by mass Next, the coating liquid for the surface protective layer was stirred. Stirring was performed as follows. First, the coating liquid for the surface protective layer was placed in a stirring vessel. A ZT-20 (manufactured by Satake Multinics Co., Ltd.) stirring vessel was used. A Satake Multi A Mixer AT14-VPR-0.09BI (manufactured by Satake Multinics Co., Ltd.) was used for stirring. The stirring method was centripetal stirring. The power for stirring the surface protective layer coating liquid was 0.75 kW, and the stirring time was 5 minutes.

[0132] Next, a coating liquid for a surface protective layer was applied onto the design layer 3. A coating film made of the coating liquid for a surface protective layer was formed to a thickness of 4.0 μm.

[0133] Thereafter, the first irradiation step was carried out. Specifically, the first irradiation step was carried out at 25°C under atmospheric pressure in a nitrogen gas atmosphere with an oxygen concentration of 33.2 ppm, with an illuminance of 6 mW / cm on the surface of the coating film made of the coating liquid for surface protective layer. ２ Using a Xe excimer lamp with a wavelength of 172 nm, the integrated light intensity was 12 mJ / cm ２ This caused wrinkles to form on the surface of the coating film.

[0134] Subsequently, the second irradiation step was carried out. Specifically, the coating film was irradiated with ionizing radiation to cure the entire film, thereby forming a surface protective layer 5. In this manner, a decorative sheet 1 was obtained.

[0135] <Example 2> A decorative sheet 1 was produced in the same manner as in Example 1, except for the following points. In this example, the oxygen concentration in the first irradiation step was set to 36.6 ppm. Then, a coating film made of the surface protective layer coating liquid was formed to a thickness of 7.2 μm.

[0136] <Example 3> A decorative sheet 1 was produced in the same manner as in Example 1, except for the following points. That is, in this example, the oxygen concentration in the first irradiation step was set to 31.2 ppm. Then, a coating film made of the coating liquid for the surface protective layer was formed to a thickness of 9.1 μm.

[0137] Example 4 Decorative sheet 1 was produced in the same manner as in Example 1, with the following exceptions. Specifically, in this example, the following ionizing radiation curable resins were used: Ionizing radiation curable resin A Type: polyethylene glycol diacrylate Product name: Light Acrylate 14EG-A (manufactured by Kyoeisha Chemical Co., Ltd.) Blend: 60 parts by mass Ionizing radiation curable resin B Type: trimethylolpropane EO-modified triacrylate (15 moles of EO added) Product name: SR9035 (manufactured by Sartomer) Blend: 40 parts by mass The oxygen concentration in the first irradiation step was set to 35.1 ppm. A coating film made of the surface protective layer coating liquid was formed to a thickness of 6.8 μm.

[0138] Example 5 A decorative sheet 1 was produced in the same manner as in Example 1, with the following exceptions. That is, in this example, the following ionizing radiation curable resins A and B were used. Ionizing radiation curable resin A Type: polyethylene glycol diacrylate Product name: A-1000 (manufactured by Shin-Nakamura Chemical Co., Ltd.) Blend: 60 parts by mass Ionizing radiation curable resin B Type: trimethylolpropane EO-modified triacrylate (15 moles of EO added) Product name: SR9035 (manufactured by Sartomer) Blend: 40 parts by mass The oxygen concentration in the first irradiation step was set to 30.5 ppm, and the temperature was set to 65°C. A coating film made of the coating liquid for the surface protective layer was formed to a thickness of 2.9 μm.

[0139] Example 6 A decorative sheet 1 was produced in the same manner as in Example 1, with the following exceptions. Specifically, in this example, the following ionizing radiation curable resins A and B were used. Ionizing radiation curable resin A Type: tricyclodecane dimethanol diacrylate Product name: A-DCP (manufactured by Shin-Nakamura Chemical Co., Ltd.) Blend: 60 parts by mass Ionizing radiation curable resin B Type: trimethylolpropane EO-modified triacrylate (15 moles of EO added) Product name: SR9035 (manufactured by Sartomer) Blend: 40 parts by mass The oxygen concentration in the first irradiation step was set to 32.5 ppm. A coating film made of the surface protective layer coating liquid was formed to a thickness of 4.4 μm.

[0140] Example 7 Decorative sheet 1 was produced in the same manner as in Example 1, with the following exceptions. That is, in this example, the following ionizing radiation curable resins A and B were used. Ionizing radiation curable resin A Type: tricyclodecane dimethanol diacrylate Product name: A-DCP (manufactured by Shin-Nakamura Chemical Co., Ltd.) Blend: 60 parts by mass Ionizing radiation curable resin B Type: trimethylolpropane EO-modified triacrylate (15 moles of EO added) Product name: SR9035 (manufactured by Sartomer) Blend: 40 parts by mass The oxygen concentration in the first irradiation step was set to 36.6 ppm, and the temperature was set to 65°C. Furthermore, a coating film made of the coating liquid for the surface protective layer was formed to a thickness of 7.4 μm.

[0141] <Example 8> Decorative sheet 1 was produced in the same manner as in Example 1, except for the following points. That is, in this example, the amount of particles was 10 parts by mass. The oxygen concentration in the first irradiation step was 31.6 ppm. In addition, a coating film made of the surface protective layer coating liquid was formed to a thickness of 4.9 μm.

[0142] <Example 9> Decorative sheet 1 was produced in the same manner as in Example 1, except for the following points. That is, in this example, particles were not blended. The oxygen concentration in the first irradiation step was set to 33.9 ppm. A coating film made of the surface protective layer coating liquid was then formed to a thickness of 7.2 μm.

[0143] <Example 10> Decorative sheet 1 was produced in the same manner as in Example 1, except for the following points. That is, in this example, particles were not blended. The oxygen concentration in the first irradiation step was set to 31.7 ppm. A coating film made of the surface protective layer coating liquid was then formed to a thickness of 12.2 μm.

[0144] <Comparative Example 1> Decorative sheet 1 was produced in the same manner as in Example 1, except for the following points. That is, in this example, the oxygen concentration in the first irradiation step was set to 31.4 ppm. Then, a coating film made of the surface protective layer coating liquid was formed to a thickness of 1.5 μm.

[0145] Comparative Example 2 Decorative sheet 1 was produced in the same manner as in Example 1, with the following exceptions. That is, in this example, the following ionizing radiation curable resins A and B were used. Ionizing radiation curable resin A Type: dipentaerythritol polyacrylate Product name: A-DPH (manufactured by Shin-Nakamura Chemical Co., Ltd.) Blend: 60 parts by mass Ionizing radiation curable resin B Type: trimethylolpropane EO-modified triacrylate (15 moles of EO added) Product name: SR9035 (manufactured by Sartomer) Blend: 40 parts by mass The oxygen concentration in the first irradiation step was set to 32.0 ppm. In addition, a coating film made of the coating liquid for the surface protective layer was formed to a thickness of 3.5 μm.

[0146] Comparative Example 3: A decorative sheet 1 was produced in the same manner as in Example 1, except for the following points. In this example, a coating film made of a surface protective layer coating liquid was formed to a thickness of 4.0 μm, and then the coating film was cured only by the second irradiation step without performing the first irradiation step. The oxygen concentration in the second irradiation step was set to 37.1 ppm.

[0147] <Comparative Example 4> Decorative sheet 1 was produced in the same manner as in Example 1, except for the following points. That is, in this example, the blending amount of particles was set to 15 parts by mass. The oxygen concentration in the first irradiation step was set to 32.9 ppm. In addition, a coating film made of the coating liquid for the surface protective layer was formed to a thickness of 2.7 μm.

[0148] <Comparative Example 5> Decorative sheet 1 was produced in the same manner as in Example 1, except for the following points. That is, in this example, the oxygen concentration in the first irradiation step was set to 35.3 ppm. Then, a coating film made of the surface protective layer coating liquid was formed to a thickness of 11.0 μm.

[0149] <Evaluation> Each of the decorative sheets described above was subjected to the following evaluations.

[0150] (1) Thickness of Surface Protective Layer The thickness of the surface protective layer 5 was measured as follows. First, Pt was sputtered (40 mA, 20 seconds) on the surface of the surface protective layer 5 to form a Pt film for use as an interface mark. Next, the sample on which the Pt film was formed was embedded in a photocurable resin, and then a cross section parallel to the thickness direction of the surface protective layer 5 was exposed. To expose the cross section, for example, an ultramicrotome (EM UC7, manufactured by Leica Microsystems) was used. Then, this cross section was observed at 1000x magnification using an optical microscope. For this observation, for example, an optical microscope (BX53M) manufactured by Olympus Corporation was used.

[0151] Next, the shape of the surface protection layer 5 is extracted from this cross-sectional image by the method described below. ImageJ is used as the image processing software for shape extraction. Specifically, first, the connected cross-sectional image is converted into an 8-bit grayscale image. Next, in order to later set the gradation value of only the region corresponding to the surface protection layer to 255, a process of subtracting 1 from the gradation values ​​of all pixels is performed using the Subtract function of ImageJ. This adjusts the maximum gradation value to 254. Next, for the image with adjusted gradation values, the contour of the region corresponding to the surface protection layer is approximated by a polygon using the Polygon selection function of ImageJ. The contour of the polygonal approximation region is further converted into a smooth shape using the Fit Spline function of ImageJ. Then, the region surrounded by this smooth contour is filled using the Fill function of ImageJ so that the gradation value becomes 255. Then, using the Threshold function of ImageJ, pixels with a gradation value of 255 are left with the gradation value at 255, and pixels with a gradation value of 254 or less are converted to a gradation value of zero. In this way, a binarized image is obtained that includes the area corresponding to the surface protection layer as a bright area and the other areas as dark areas.

[0152] Next, the binarized image is converted into a 32-bit grayscale image. In this conversion, the gradation value of the pixels corresponding to the bright areas remains at 255, and the gradation value of the pixels corresponding to the dark areas remains at zero. Next, using the Multiply function of ImageJ, the gradation value of each pixel is multiplied by the vertical dimension H (μm) of the field of view, which corresponds to the entire vertical length of the image. Then, using the Divide function of ImageJ, the product is divided by 255. As a result, the gradation value of the pixels corresponding to the bright areas remains at zero, and the gradation value of the pixels corresponding to the dark areas is replaced with the dimension H (μm).

[0153] Next, using the Plot Profile function of ImageJ, the gradation values ​​of pixels aligned vertically are integrated for each horizontal coordinate (pixel) of the image, and a value is extracted by dividing this value by the number of vertical pixels N of the image. Here, since the gradation values ​​of pixels included in the region corresponding to the surface protective layer in the image are replaced by the vertical dimension H of the field of view, which corresponds to the entire vertical length of the image, the value obtained by dividing this integrated value by the number of vertical pixels N of the image can be used as the film thickness of the surface protective layer for a specific horizontal coordinate.

[0154] (2) Glossiness The glossiness was measured at 60 degrees using a Rhopoint IQ (manufactured by Konica Minolta, Inc.) The "glossiness value" in Tables 1 to 4 below represents this 60 degree glossiness.

[0155] (3) Sanding Feel The sanding feel was evaluated by the following method. First, advance preparation was carried out to ensure that the evaluation criteria for the tactile feel were consistent among the evaluators. Specifically, three standard test pieces with different surface properties were prepared. Next, five evaluators were blindfolded and asked to slide their fingers over the surface of the standard test piece while pressing it with their fingers, and then to evaluate the tactile feel as follows: A: A smooth tactile feel and a rough tactile feel were sufficiently obtained. B: A smooth tactile feel and a slightly rough tactile feel were obtained. C: Only one of a smooth tactile feel and a rough tactile feel was obtained.

[0156] The above procedure was repeated until the evaluations by each evaluator coincided three or more times in succession and the evaluation results between the evaluators coincided three times in succession.

[0157] Next, for each of the decorative sheets prepared in the above examples and comparative examples, each of the evaluators was blindfolded and asked to slide their fingers over the surface of the surface protective layer while pressing it with their fingers, and then to classify the tactile sensation related to surface roughness into the three groups mentioned above. This procedure was repeated until the evaluations by each evaluator were consistent three or more times in a row, and the evaluation results between the evaluators were consistent three or more times in a row. From these results, the tactile sensation was evaluated according to the above criteria.

[0158] (4) Cloudiness First, advance preparations were made to ensure that the evaluation criteria for the degree of cloudiness that occurs when observing the decorative sheet were consistent among the evaluators. Specifically, three standard test pieces with different surface properties were prepared (a test piece that does not easily produce diffuse reflection, a test piece that produces moderate diffuse reflection, and a test piece that is prone to produce strong diffuse reflection).

[0159] Next, five evaluators were asked to observe the test pieces and then evaluate the degree of cloudiness as follows.

[0160] A: The surface of the decorative sheet did not appear cloudy. B: The surface of the decorative sheet appeared slightly cloudy. C: The surface of the decorative sheet appeared cloudy.

[0161] Next, each of the evaluators was asked to observe each of the decorative sheets produced in the above examples and comparative examples, and then to classify the degree of cloudiness into the three groups mentioned above. This procedure was then repeated until the evaluations by each evaluator were consistent for three or more consecutive evaluations, and the evaluation results between the evaluators were consistent for three consecutive evaluations. From these results, the degree of cloudiness was evaluated according to the above criteria.

[0162] When observing the decorative sheet, if the diffuse reflection from the surface protective layer 5 appears stronger than the light reflected from the design layer, the decorative sheet will appear cloudy.

[0163] (5) Stain Resistance To evaluate stain resistance, the Stain A test specified in the Japanese Agricultural Standards (JAS) was carried out. That is, 10 mm wide lines were drawn on the surface protective layer of each decorative sheet using blue ink, black quick-drying ink, and red crayon, and the sheets were left for 4 hours. Thereafter, the blue ink, black quick-drying ink, and red crayon lines were wiped off with a cloth soaked in ethanol.

[0164] The evaluation criteria were as follows: AA: Lines of each color could be wiped off very easily. A: Lines of each color could be wiped off easily. A: Part of the lines of each color could be wiped off, but some stains remained. B: Lines of each color could not be wiped off.

[0165] (6) Reflection First, preliminary preparations were made to ensure that the evaluation criteria for the degree of reflection that occurred when observing the decorative sheet were consistent among the evaluators. Specifically, three standard test pieces with different surface properties (a test piece that produces strong specular reflection, a test piece that produces moderate specular reflection, and a test piece that produces little specular reflection) were prepared.

[0166] Next, each of the five evaluators was asked to observe the test pieces and then evaluate the reflection as follows.

[0167] A: No reflection occurred on the surface of the decorative sheet. B: Some reflection occurred on the surface of the decorative sheet. C: Significant reflection occurred on the surface of the decorative sheet. Next, each of the evaluators was asked to observe each of the decorative sheets produced in the above examples and comparative examples, and then to classify the degree of reflection into the three groups mentioned above. This procedure was then repeated until the evaluations by each evaluator were consistent three or more times in a row, and the evaluation results between the evaluators were consistent three times in a row. From these results, the degree of reflection was evaluated according to the above criteria.

[0168] (7) Weather Resistance Weather resistance was evaluated by the following method.

[0169] First, a weather resistance test was carried out on each of the decorative sheets produced in the above examples and comparative examples using a xenon weather meter (manufactured by Suga Test Instruments, product name: X75). The weather resistance test was carried out under the following conditions: illuminance 60 W / m ２ , wavelength 300-400 nm, tank environment 44.3°C / 50% RH, charging time 240 hours.

[0170] Next, the appearance (i.e., gloss, etc.) of the decorative sheet after the weather resistance test was visually compared with the appearance of a decorative sheet that had not been subjected to the weather resistance test. The appearance of the decorative sheet after the weather resistance test was then evaluated based on the following criteria: A: The weather resistance test did not change the appearance. B: The weather resistance test changed the appearance slightly. C: The weather resistance test changed the appearance significantly.

[0171] (8) Autocorrelation Length Sal, Root-Mean-Square Gradient Sdq, and Convex Area Ratio The autocorrelation length Sal, root-mean-square gradient Sdq, and convex area ratio were determined as described in the detailed description section. Furthermore, a shape measurement laser microscope VK-X3000 (manufactured by Keyence Corporation) was used for these measurements. The objective lens magnification was 50x, and data with a size of 1024 x 768 was obtained. The data was analyzed using the VK-X3000 multi-file analysis application as analysis software. The image processing procedure included performing "Waviness Removal: Strength 5" in the "Surface Shape Correction" of the image processing tool, followed by "Height Cut Level: Strong," then performing "Height Cut Level: Strong" again, then performing "Noise Removal: Strong," and finally performing "Noise Removal: Strong" again.

[0172] The evaluation results are shown in Tables 1 to 4.

[0173]

[0174]

[0175]

[0176]

[0177] As shown in Tables 1 to 4, the decorative sheets according to Examples 1 to 10 gave the evaluators a sanding sensation. Furthermore, these decorative sheets either exhibited slight cloudiness or no cloudiness. Furthermore, these decorative sheets either exhibited slight reflection or no reflection. In particular, the decorative sheets according to Examples 2 and 7 did not exhibit either cloudiness or reflection, gave the evaluators a sanding sensation, and were also excellent in stain resistance and weather resistance. On the other hand, the decorative sheets according to Comparative Examples 1 to 5 did not give the evaluators a sanding sensation. Furthermore, the decorative sheet according to Comparative Example 3 had a high gloss due to its strong specular reflection. While such decorative sheets exhibited strong specular reflection, they were not prone to diffuse reflection, so the decorative sheet did not appear cloudy.

[0178] 1...decorative sheet, 2...base layer, 3...pattern layer, 4...transparent resin layer, 5...surface protection layer, 6...primer layer, 7...adhesive layer, 8...hiding layer, 11...decorative material, B...base material.

Claims

1. A decorative sheet comprising an original fabric layer and a surface protective layer provided on one surface of the original fabric layer, wherein a concave-convex structure is provided on the surface of the surface protective layer, and the concave-convex structure of the surface protective layer has an autocorrelation length Sal of 20 μm or less and a root-mean-square gradient Sdq of 0.1 or more.

2. The decorative sheet according to claim 1, wherein the convex area ratio is 40% or less.

3. The decorative sheet according to claim 1 or 2, wherein the surface protective layer contains a cured resin and particles.

4. The decorative sheet according to claim 3, wherein the particles are contained in the surface protective layer in an amount of 5 to 10 parts by weight per 100 parts by weight of the resin.

5. A decorative sheet according to claim 3 or 4, wherein the resin is an ionizing radiation curable resin.

6. A decorative sheet according to any one of claims 3 to 5, wherein the resin is an acrylate.

7. A decorative sheet according to any one of claims 3 to 6, wherein said resin contains an acrylate having a functionality of 3 or less.

8. A decorative sheet according to any one of claims 3 to 7, wherein the resin contains a trifunctional acrylate, and the amount of the trifunctional acrylate per 100 parts by mass of the resin is 40 parts by mass or more.

9. The decorative sheet according to claim 8, wherein the molecular weight of said trifunctional acrylate is in the range of 360 to 1,135.

10. A decorative sheet according to claim 8 or 9, wherein the resin further contains a bifunctional acrylate, and the amount of the bifunctional acrylate per 100 parts by mass of the resin is 40 parts by mass or more.

11. The decorative sheet according to claim 10, wherein the molecular weight of said bifunctional acrylate is in the range of 250 to 850.

12. A decorative sheet according to any one of claims 7 to 11, wherein the resin further contains an acrylate having five or more functionalities, and the amount of the acrylate having five or more functionalities is 3 parts by mass or more and 20 parts by mass or less.

13. A decorative sheet according to any one of claims 3 to 12, wherein the resin contains a tetrafunctional acrylate, the amount of the tetrafunctional acrylate per 100 parts by mass of the resin is 40 parts by mass or more, and the molecular weight of the tetrafunctional acrylate is in the range of 1,800 or more and 2,000 or less.

14. A decorative sheet according to any one of claims 1 to 13, wherein the thickness t of said surface protective layer is 3 μm or more and 10 μm or less.

15. A decorative sheet according to any one of claims 1 to 14, wherein the gloss of said surface protective layer is 5 or less.

16. The decorative sheet according to any one of claims 1 to 15, further comprising a pattern layer between the base layer and the surface protective layer.

17. A decorative material comprising the decorative sheet according to any one of claims 1 to 16 and a substrate to which the decorative sheet is attached.

18. A method for manufacturing a decorative sheet, comprising: forming a coating film on an original layer, the coating film being made from a coating liquid containing an ionizing radiation curable resin and particles; carrying out a first irradiation step of irradiating the coating film with light having a wavelength of 200 nm or less; and then carrying out a second irradiation step of irradiating the coating film with ionizing radiation or ultraviolet light having a wavelength longer than that of the light irradiated in the first irradiation step, wherein the first irradiation step is carried out so that after the second irradiation step, the autocorrelation length Sal of the surface of the coating film is 20 μm or less and the root mean square gradient Sdq is 0.1 or more.

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