Decorative sheet

Abstract

This decorative sheet 1 comprises a base layer 2 and a surface protection layer 5 that is provided on one surface of the base layer 2. The surface of the surface protection layer 5 is provided with a relief structure that includes a plurality of ridge-shaped parts each protruding in a ridge shape. The surface protection layer 5 contains a cured product of an ionizing radiation curable resin. The ionizing radiation curable resin includes an ionizing radiation curable resin that has a cyclic structure.

Description

Decorative sheet

[0001] The present invention relates to a decorative sheet. The decorative sheet can be used, for example, for the interior and exterior decoration of buildings, and for the surface decoration of fixtures, furniture, fixtures, flooring materials, and the like.

[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 are of concern in terms of environmental protection. By not using vinyl chloride resin, these decorative sheets suppress the generation of toxic gases and the like when incinerated.

[0003] Decorative sheets are widely used in architecture to impart design and durability to the surface of wood, wood boards, metal sheets, non-flammable boards, paper substrates, or resin substrates. These sheets are bonded to the surface of these substrates with adhesives or other adhesives to create decorative panels. Designs can be selected based on requirements and applications, from patterns such as wood grain or stone grain printed using various printing methods to plain surfaces. Similarly, surface gloss is also an important design feature, ranging from a high mirror-like gloss to a low gloss with no reflections at all. Another important function of decorative sheets, along with design, is durability. Durability is a comprehensive assessment of scratch resistance, stain resistance, and whether these properties are maintained over the long term. Decorative sheets are used for architectural interior materials in homes and public facilities, architectural exterior components such as entrance doors, surface materials for building fixtures, and surface materials for home appliances. Because of this, they are exposed to direct sunlight, wind, and rain every day, requiring extremely high weather resistance.

[0004] To provide durability, a surface protective layer is generally formed on the outermost surface of the decorative sheet. Furthermore, to adjust the aforementioned glossiness, particularly to achieve low gloss, a gloss adjuster (matt additive) is generally added to the surface protective layer. Thus, a decorative sheet that takes into consideration design (low gloss), scratch resistance, and stain resistance is disclosed, for example, in Patent Document 2.

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

[0006] Japanese Patent No. 3271022 Japanese Patent Application Publication No. 2019-119138 International Publication No. 2021 / 201105 Japanese Patent Application Publication No. 2022-008024 International Publication No. 2022 / 054644 International Publication No. 2022 / 054645 International Publication No. 2022 / 054646

[0007] In recent years, due to the expanding range of applications for decorative sheets and the increasing sophistication of consumer awareness of quality, decorative sheets are required to have various properties, such as low gloss, fingerprint resistance, scratch resistance, stain resistance, and bendability. Focusing on stain resistance, stain resistance is required in wet areas (kitchens, bathroom sinks, etc.) against stains with strong coloring components. For example, hair dyes are often used on bathroom sinks to color hair. Such hair dyes are a mixture of a first agent containing a dye and an alkaline agent and a second agent containing an oxidizing agent. If left unattended after adhering to a decorative sheet, they can react with the resin in the top coat of the decorative sheet, causing severe staining. For this reason, it is desirable for decorative sheets to have stain resistance.

[0008] An object of the present invention is to provide a decorative sheet that has low gloss and excellent resistance to staining and contamination.

[0009] 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 the surface of the surface protective layer is provided with an uneven structure including a plurality of ridge-like portions each protruding in a ridge-like shape, the surface protective layer including a cured product of an ionizing radiation curable resin, and the ionizing radiation curable resin including an ionizing radiation curable resin having a cyclic structure.

[0010] According to another aspect of the present invention, there is provided a decorative sheet according to any of the above aspects, wherein the ionizing radiation curable resin contains the ionizing radiation curable resin having a cyclic structure, such that the cyclic structure portion accounts for 2 to 45 mass % of the total ionizing radiation curable resin. According to yet another aspect of the present invention, there is provided a decorative sheet according to any of the above aspects, wherein the cyclic structure is composed of a monocyclic, dicyclic, or tetracyclic hydrocarbon.

[0011] According to yet another aspect of the present invention, there is provided a decorative sheet according to any of the above aspects, wherein the ionizing radiation curable resin having a cyclic structure is an acrylate.

[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 ionizing radiation curable resin having a cyclic structure is monofunctional.

[0013] 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 ionizing radiation curable resin further contains an oligomer having 10 or fewer functionalities.

[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 oligomer is a urethane acrylate or an acrylic acrylate.

[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 uneven structure of the surface protective layer has an RSm / Ra in the range of 10 to 600.

[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 thickness of the surface protective layer is in the range of 2 to 20 μm.

[0017] 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 further contains particles having an average particle size of 10 μm or less.

[0018] According to yet another aspect of the present invention, there is provided a decorative sheet according to any of the above aspects, wherein the particles are contained in the surface protective layer in an amount ranging from 0.5 to 10 parts by mass, when the total amount of the ionizing radiation curable resin is 100 parts by mass.

[0019] 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 glossiness of the surface protective layer is 10 or less.

[0020] 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.

[0021] According to yet another aspect of the present invention, there is provided a method for producing a decorative sheet, comprising: forming a coating film made of a coating liquid for a surface protective layer on one side of an original sheet layer; irradiating the coating film with light having a wavelength of 200 nm or less; and, after the irradiation, irradiating with ionizing radiation or ultraviolet light having a wavelength longer than that of the light, wherein the coating liquid for the surface protective layer comprises an ionizing radiation curable resin, and the ionizing radiation curable resin comprises an ionizing radiation curable resin having a cyclic structure.

[0022] According to yet another aspect of the present invention, there is provided the method according to the above aspect, wherein the light has a wavelength of 172 nm.

[0023] According to the present invention, it is possible to provide a decorative sheet that has low gloss and excellent resistance to staining and contamination.

[0024] Fig. 3 is a cross-sectional view of a decorative material including a decorative sheet according to one embodiment of the present invention. Fig. 4 is a cross-sectional view of a decorative material including a decorative sheet according to another embodiment of the present invention. Fig. 5 is a cross-sectional view of the surface protective layer of the decorative sheet of Figs. 1 and 2. Fig. 6 is a microscope image of the surface protective layer of a decorative sheet according to an example of the present invention.

[0025] The configuration of a 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 embodiments of any of the above aspects. The following features can be incorporated into each of the above aspects, either singly or in combination.

[0026] In the drawings referred to below, 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 thickness and planar dimensions, the thickness ratio of each layer, etc. may differ from the actual ones.

[0027] 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 does not limit the materials, shapes, structures, etc. of the components to those described below. The technical idea of ​​the present invention can be modified in various ways within the technical scope defined by the claims.

[0028] <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 decorative material including a decorative sheet according to another embodiment of the present invention. Fig. 3 is a cross-sectional view of the surface protective layer of the decorative sheet of Figs. 1 and 2. Fig. 4 is a micrograph of the surface protective layer of a decorative sheet according to one example of the present invention.

[0029] The cross section shown in Fig. 3 is a cross section along the thickness direction of the surface protection layer, and the micrograph in Fig. 4 is a plan view taken with a laser microscope (OLS-4000 manufactured by Olympus Corporation).

[0030] The decorative material 11 shown in Figures 1 and 2 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 board, or may be curved or folded. The decorative material 11 may have a shape other than a board.

[0031] 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.

[0032] The decorative sheet 1 shown in Figure 1 has a pattern layer 3 and a surface protective layer 5 provided in this order from the raw fabric layer 2 side on one surface, i.e., the front side, of the raw fabric layer 2, and a primer layer 6 provided on the other surface (i.e., the surface facing the substrate B) of the raw fabric layer 2. In Figure 1, one or more of the pattern layer 3 and the primer layer 6 may be omitted.

[0033] 2 has a pattern layer 3, an adhesive resin layer 4b, a transparent resin layer 4, and a surface protective layer 5 provided in this order from the raw fabric layer 2 side on one surface (the front side) of the raw fabric layer 2, and a primer layer 6 provided on the other surface of the raw fabric layer 2 (i.e., the surface facing the substrate B). Here, an embossed uneven pattern (embossed pattern 4a) is provided on the transparent resin layer 4. In FIG. 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 does not have to be provided.

[0034] Furthermore, if scratch resistance or other requirements are required, at least one of the transparent resin layer 4 and the surface protective layer 5 may be laminated in multiple layers. Also, in consideration of the adhesion between the layers, other known layers may be arranged. Furthermore, a concealing layer (not shown) or the like may be provided between the base layer 2 and the primer layer 6 as appropriate.

[0035] Next, each layer that constitutes the decorative sheet 1 will be described.

[0036] <1.1> Raw Fabric Layer The raw fabric layer 2 can be made of any material selected from the group consisting of paper, synthetic resin, synthetic resin foam, rubber, nonwoven fabric, synthetic paper, and metal foil. 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. The raw fabric layer 2 may also be a sheet made of the same resin composition as the transparent resin layer 4. In this case, the raw fabric layer 2 is obtained by molding a resin material or a resin composition into a film shape. Examples of the molding method include calendar molding and extrusion molding.

[0037] The raw fabric layer 2 preferably has a colored layer formed by mixing an inorganic pigment with a synthetic resin, and a skin layer formed of a synthetic resin. The thickness of the skin layer is preferably 3 μm or more and 20 μm or less, and the thickness ratio of the skin layer to the colored layer is preferably 1:6 to 1:50. When the raw fabric 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 and contaminate the T-die of the extruder and the rolls during transport, so it is desirable that the outermost layer be a skin layer that does not contain pigment. It is desirable to provide skin layers on both sides of the colored layer. Increasing the thickness of the skin layer and increasing its ratio to the colored layer is undesirable because it reduces the ratio of the colored layer and reduces hiding power.

[0038] The thickness of the raw fabric layer 2 is preferably 50 μm or more and 150 μm or less. If the thickness of the raw fabric layer 2 is less than 50 μm, the performance of covering the unevenness of the base (unevenness) will be reduced. On the other hand, if the thickness of the raw fabric layer 2 exceeds 150 μm, problems such as whitening and cracking may occur during bending.

[0039] (Inorganic Pigment) Known inorganic pigments, such as titanium oxide, can be used to provide opacity. The base layer 2 serves to conceal the pattern on the substrate B. To achieve the required opacity from the standpoint of the design of the decorative sheet 1, a light transmittance of 40% or less is preferable. Low opacity results in the pattern of the design layer 3 and the pattern of the substrate B intermingling, which is undesirable. By incorporating an inorganic pigment, a decorative sheet 1 with good opacity can be obtained. The amount of inorganic pigment mixed is preferably 5 to 50 parts by weight, based on 100 parts by weight of the resin material. A small amount of inorganic pigment results in poor opacity, while a mixed amount of 50 parts by weight or more causes embrittlement of the base layer 2, which is undesirable. The inorganic pigment to be incorporated 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, the synthetic inorganic pigment may be a mixture of one or more natural or synthetic inorganic pigments. Furthermore, the synthetic inorganic pigment may also be used in combination with an organic pigment such as carbon black.

[0040] Furthermore, additives such as fatty acid metal salts may be added to the inorganic pigment to improve dispersibility and extrusion suitability.

[0041] When a substrate with an inactive surface such as an olefin-based substrate is used as the raw fabric layer 2, it is desirable to subject the front and back surfaces of the raw fabric layer 2 to corona treatment, plasma treatment, ozone treatment, electron beam treatment, ultraviolet treatment, dichromate treatment, etc.

[0042] <1.2> Pattern Layer A pattern layer 3 for adding a pattern to the decorative sheet 1 can be provided on the surface of the base fabric layer 2. Patterns that can be used include wood grain, pebble grain, sand grain, tiled, brickwork, fabric grain, leather-grained patterns, and geometric shapes.

[0043] Furthermore, a base solid ink layer (not shown) may be provided between the base layer 2 and the design layer 3 depending on the level of the desired design. The base solid ink layer is provided so as to cover the entire surface of the base layer 2. The base solid ink layer may also be multi-layered, consisting of two or more layers, as needed for hiding properties, etc. Furthermore, the design layer 3 may be formed by laminating as many plates as necessary to express the desired design. In this way, the design layer 3 and the base solid ink layer can be combined in various ways depending on the desired design, i.e., the design to be expressed, but there are no particular limitations.

[0044] The constituent materials of the base solid ink layer and the design layer 3 are not particularly limited. Examples of materials that can be used for the base solid ink layer and the design layer 3 include printing inks and coating agents prepared by dissolving or dispersing a matrix and a colorant such as a dye or pigment in a solvent. Examples of the matrix include various synthetic resins, such as oil-based nitrocellulose resins, two-component urethane resins, acrylic resins, styrene resins, polyester resins, urethane resins, polyvinyl resins, alkyd resins, epoxy resins, melamine resins, fluorine-containing resins, silicone resins, and rubber resins, as well as mixtures and copolymers thereof. Examples of colorants that can be used include inorganic pigments, such as carbon black, titanium white, zinc white, red iron oxide, yellow lead, iron blue, and cadmium red; organic pigments, such as azo pigments, lake pigments, anthraquinone pigments, phthalocyanine pigments, isoindolinone pigments, and dioxazine pigments; and mixtures thereof. As the solvent, toluene, xylene, ethyl acetate, butyl acetate, methyl alcohol, ethyl alcohol, isopropyl alcohol, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, water, or a mixture thereof can be used.

[0045] In addition, functional additives such as extender pigments, plasticizers, dispersants, surfactants, tackifiers, adhesion aids, drying agents, hardeners, hardening accelerators, and hardening retarders may be added to the base solid ink layer and the pattern layer 3 to impart various functions.

[0046] Here, the base solid ink layer and the design 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 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.

[0047] The thickness of the design layer 3 is preferably 3 μm or more and 20 μm or less. When the thickness of the design layer 3 is within this range, the printing can be made clear, the printing workability when producing the decorative sheet 1 is improved, and production costs can be reduced.

[0048] <1.3> Transparent Resin Layer The resin material used as the main component of the transparent resin layer 4 is preferably made of 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-pent ... Examples of suitable olefins include homopolymers or copolymers of two or more types of α-olefins (e.g., ethylene, 4-ethyl-1-hexene, 3-ethyl-1-hexene, 9-methyl-1-decene, 11-methyl-1-dodecene, 12-ethyl-1-tetradecene, etc.), and 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, ethylene-butyl acrylate copolymer, etc. Furthermore, when an attempt is made to improve the surface strength of the decorative sheet 1, it is preferable to use highly crystalline polypropylene.

[0049] Here, in this specification, the term "main component" refers to 90% by mass or more of the material in question, unless otherwise specified.

[0050] 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, which reduces the significance of providing the transparent resin layer 4. If the thickness of the transparent resin layer 4 exceeds 100 μm, the rigidity of the decorative sheet 1 may be too high, which may cause problems such as whitening and cracking during bending.

[0051] However, when the surface protection layer 5 is provided on the transparent resin layer 4, the thickness of the transparent resin layer 4 may be less than 50 μm.

[0052] The resin composition constituting the transparent resin layer 4 may contain various functional additives, such as a heat stabilizer, a light stabilizer, an ultraviolet absorber, an antiblocking agent, a catalyst scavenger, a colorant, a light scattering agent, and a gloss adjuster, as needed. These various functional additives can be appropriately selected from well-known additives.

[0053] Furthermore, the adhesive used to bond the design layer 3 and the transparent resin layer 4 can be any material selected depending on the bonding method. Examples of bonding methods include lamination methods such as thermal lamination, extrusion lamination, and dry lamination, and the adhesive can be selected from acrylic, polyester, polyurethane, and other materials. Due to their cohesive strength, a two-component curing urethane material that utilizes the reaction between isocyanate and polyol is usually desirable. There are no particular restrictions on the lamination method for the transparent resin layer 4, but methods that apply heat and pressure, extrusion lamination, dry lamination, and the like are commonly used.

[0054] The transparent resin layer 4 may also be provided with an embossed pattern (embossed pattern 4a). Ink can be embedded in the embossed pattern 4a to further improve the design. The embossed pattern 4a can be formed by embossing a sheet that has been laminated by various methods using heat and pressure, or by forming a pattern on a cooling roll and embossing the sheet simultaneously with extrusion lamination.

[0055] Alternatively, a method may be used in which the pattern layer 3 embossed simultaneously with extrusion and the transparent resin layer 4 are bonded together by heat or dry lamination.

[0056] Furthermore, to improve adhesion between the design layer 3 and the transparent resin layer 4, an adhesive resin layer 4b may be provided between the design layer 3 and the transparent resin layer 4. Specifically, when further lamination strength is required in the extrusion lamination method, an adhesive resin layer 4b may be provided between the transparent resin layer 4 and the adhesive. When the 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 an acid-modified resin such as polypropylene, polyethylene, or acrylic resin. The thickness of the adhesive resin layer 4b is preferably 2 μm or more to improve adhesive strength.

[0057] When an embossed pattern 4a is applied to the transparent resin layer 4, the uneven structure can be expressed by the cut level difference Rdc. The "cut level difference Rdc" is a surface texture parameter defined in JIS B0601:2013. The cut level difference Rdc indicates the cut level difference of the roughness curve and expresses the steepness of the uneven shape. Here, the position of the highest peak of the roughness curve is used as the reference for the cut level c. Furthermore, here, c(Rmr1) is defined as the cut level when the load length ratio Rmr of the roughness curve is 10%, and c(Rmr2) is defined as the cut level when the load length ratio Rmr of the roughness curve is 25%. The cut level difference Rdc (μm) of the roughness curve is the difference between the cut level c(Rmr1) and the cut level c(Rmr2).

[0058] The Rdc of the transparent resin layer 4 is preferably 0.2 μm or more and 2.9 μm or less. If the Rdc is less than 0.2 μm, the effect of embedding ink tends to be weakened. Furthermore, if the Rdc is greater than 2.9 μm, when the surface protection layer 5 is formed on the transparent resin layer 4, the tactile feel tends to be rough and gritty rather than moist. The Rdc of the transparent resin layer 4 is preferably 0.2 μm or more and 1.0 μm or less.

[0059] <1.4> Surface Protective Layer As shown in FIG. 3 , the surface protective layer 5 has a core portion 5A and ridge portions 5B that protrude in a ridge-like manner from one side of the core portion 5A. This forms an uneven shape in the surface protective layer 5. Here, in the decorative sheet 1 according to this embodiment, the term "ridge-like" refers to a long, raised, linear shape in a planar view. The ridge portions 5B may be curved or linear in a planar view, but are preferably curved from the viewpoint of the fingerprint resistance of the decorative sheet 1. Furthermore, in this embodiment, the ridge portions 5B refer to, for example, the portions from the lowest to the highest points of the uneven shape 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. The cross-sectional shape of the ridge portions 5B in the thickness direction of the surface protective layer 5 may be sinusoidal. The sine wave shape here refers to a shape in which the line from the lowest point to the highest point of the ridge portion 5B can be expressed as a sine wave.

[0060] Fig. 3 is a cross-sectional view schematically showing a cross section of the ridge portion 5B of the surface protective layer 5 (a cross section in the thickness direction of the surface protective layer 5), and Fig. 4 is a planar photograph showing the surface configuration of the surface protective layer 5. Here, Fig. 4 is a planar photograph obtained with a laser microscope (OLS-4000 manufactured by Olympus Corporation).

[0061] 4, the ridge portions 5B are elongated raised portions that are connected linearly in plan view. As will be described later, the ridge portions 5B are formed by irradiating the surface of the ionizing radiation curable resin with light of a specific wavelength, causing the cured film of the ionizing radiation curable resin to buckle.

[0062] The shape of the ridge portions 5B can be expressed by the ratio RSm / Ra of the surface roughness index RSm (μm) in the horizontal direction (the planar direction of the surface protective layer 5, the left-right direction in FIG. 3 ) to the surface roughness index Ra (μm) in the vertical direction (the depth direction of the ridge portions 5B, the thickness direction of the surface protective layer 5, the up-down direction in FIG. 3 ). The ratio RSm / Ra is preferably in the range of 10 to 600, more preferably in the range of 10 to 400, and even more preferably in the range of 10 to 300. More preferably, RSm / Ra is in the range of 10 to 250. As the ratio RSm / Ra decreases, the shape of the ridge portions 5B becomes finer, making it difficult to wipe off dirt and reducing contamination resistance. As the ratio RSm / Ra increases, the spacing between the ridges becomes wider, tending to increase gloss. Here, the surface roughness indices Ra and RSm are measured values ​​obtained by using a line roughness meter in accordance with JIS B0601.

[0063] The thickness t of the surface protective layer 5 is preferably in the range of 2 to 20 μm. More preferably, the thickness t of the surface protective layer 5 is in the range of 5 to 20 μm. If the thickness t of the surface protective layer 5 is less than 2 μm, the shaping by the vacuum ultraviolet light does not penetrate deeply, making it difficult to achieve a low gloss level. Furthermore, if the thickness t of the surface protective layer 5 is greater than 20 μm, the processability decreases and the layer is prone to whitening when bent.

[0064] Here, the thickness of the surface protective layer 5 refers to the thickness of a layer having the same apparent area and volume as the surface protective layer 5 and a flat surface. The thickness of the surface protective layer 5 can be determined, for example, by the following method. First, a cross section parallel to the thickness direction of the surface protective layer 5 and perpendicular to the length direction of the ridge portions 5B is imaged. Next, from this cross-sectional image, the dimension of the surface protective layer 5 in the width direction of the ridge portions 5B and the area of ​​the cross section of the surface protective layer 5 are determined. The thickness of the surface protective layer 5 is a value obtained by dividing this area by the above dimension. The thickness of the surface protective layer 5 is also 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.

[0065] Here, the surface protective layer 5 can be formed by various printing methods such as gravure printing, offset printing, screen printing, electrostatic printing, inkjet printing, etc. Furthermore, since the surface protective layer 5 covers the entire surface of the front side of the raw fabric 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 for each layer to be formed, or the same method may be selected and used for batch processing.

[0066] The design layer 3 and the surface protective layer 5 may be synchronized from the viewpoint of design. In this case, the surface protective layer 5 must be formed after the design layer 3 is formed, and therefore, gravure printing is preferably used. Furthermore, gravure printing allows for relatively high speed printing, which is advantageous in terms of cost and is therefore preferred. Here, synchronization means that 50% or more, preferably 70% or more, and most preferably 90% or more of the area where the surface protective layer 5 is formed overlaps with the design portion of the design layer 3 in a planar view.

[0067] The thickness of the surface protective layer 5 can be adjusted by adjusting the amount of coating in the printing method and coating method described above. The amount of coating can be calculated from the mass difference between a base sheet (including a raw fabric layer) with the surface protective layer 5 formed thereon and a base sheet without the surface protective layer 5 formed thereon, using various printing and coating methods.

[0068] The surface protective layer 5 includes a cured product of an ionizing radiation curable resin. The surface protective layer 5 preferably contains an ionizing radiation curable resin as a main material. The term "main material" refers to a content 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 protective layer 5. Here, "ionizing radiation" refers to charged particle beams such as electron beams. The ionizing radiation curable resin is cured by irradiation with ionizing radiation. The ionizing radiation curable resin can also be cured by 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 high absorption coefficient for this light. The ionizing radiation curable resin constituting the surface protective layer 5 can be any known resin, such as various monomers or commercially available oligomers. 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-based) resin, and may be used alone or in combination of two or more types.

[0069] The ionizing radiation curable resin includes an ionizing radiation curable resin having a cyclic structure. The ionizing radiation curable resin preferably includes the ionizing radiation curable resin having a cyclic structure in an amount within a range of 2 to 45 mass% of the entire ionizing radiation curable resin. The ionizing radiation curable resin more preferably includes the ionizing radiation curable resin having a cyclic structure in an amount within a range of 5 to 45 mass% of the entire ionizing radiation curable resin. When the ionizing radiation curable resin includes an ionizing radiation curable resin having a cyclic structure (hereinafter also referred to as a cyclic compound), a decorative sheet with excellent resistance to discoloration and contamination can be provided. This effect is believed to be due to the following reasons.

[0070] As described later in this specification, the surface protective layer 5 is formed by a first irradiation step and a second irradiation step. In the first irradiation step, a crosslinking reaction of the ionizing radiation curable resin occurs only on the surface of the coating film, and in the second irradiation step, curing of the entire coating film occurs. Here, the first irradiation step is generally performed in a nitrogen gas atmosphere with a low oxygen concentration. A nitrogen gas atmosphere with a low oxygen concentration is a hydrophobic atmosphere. On the other hand, the cyclic structure portion of the cyclic compound contained in the coating film is hydrophobic. Therefore, the cyclic structure portion of the cyclic compound is easily exposed to the surface of the coating film. As a result, the cyclic structure portion of the cyclic compound is more abundant on the surface of the surface protective layer 5 than in regions other than the surface. Because the cyclic structure portion of the cyclic compound is bulky, when a hair dye adheres to the surface protective layer 5, it prevents the dye molecules of the hair dye from coming into contact with the ionizing radiation curable resin, which does not have a cyclic structure. As a result, it is believed that the ionizing radiation curable resin having a cyclic structure exhibits excellent resistance to coloring and contamination by hair dyes.

[0071] If the amount of the cyclic structure portion is too small relative to the entire ionizing radiation curable resin, it becomes difficult to fully exhibit color stain resistance. On the other hand, if the amount of the cyclic structure portion is too large relative to the entire ionizing radiation curable resin, the crosslinking density decreases, making it difficult to fully prevent color staining caused by dye molecules of the hair dye. Furthermore, if the amount of the cyclic structure portion is too large relative to the entire ionizing radiation curable resin, wrinkle formation becomes insufficient and glossiness tends to increase. The proportion Rc (mass %) of the "cyclic structure portion" in the entire ionizing radiation curable resin can be calculated using the following formula: Rc = (Mc / Mr) x Rr Mc: Molecular weight of the "cyclic structure portion" Mr: Molecular weight of the "ionizing radiation curable resin having a cyclic structure" Rr: Proportion (mass %) of the "ionizing radiation curable resin having a cyclic structure" in the entire ionizing radiation curable resin

[0072] The term "cyclic structure" refers to a ring structure based on a carbon skeleton. The cyclic structure may be one in which the ring constituent atoms are only carbon (i.e., a carbocyclic ring), or one in which the ring constituent atoms are carbon and an element other than carbon (i.e., a heterocyclic ring). The cyclic structure may be a monocyclic ring or a polycyclic ring. The polycyclic ring may be a fused ring, a spiro ring, or a bridged ring. The cyclic structure may be composed of, for example, a monocyclic, a bicyclic, or a tetracyclic hydrocarbon. The cyclic structure has, for example, 5 or more ring constituent atoms, preferably 5 to 18, more preferably 6 to 18, and even more preferably 6 to 10 ring constituent atoms.

[0073] Examples of the cyclic structure include an isobornyl group, an adamantyl group, a dicyclopentanyl group, a cyclohexyl group, a cyclopentyl group, a cyclopentadienyl group, a 3,4-epoxycyclohexyl group, a 6,7-epoxydecahydro-1,4:5,8-dimethanonaphthalene group, a decahydronaphthalene group, a tricyclodecane group, a benzyl group, and a phenyl group. The isobornyl group, the adamantyl group, the dicyclopentanyl group, the 6,7-epoxydecahydro-1,4:5,8-dimethanonaphthalene group, and the tricyclodecane group correspond to bridged rings and have particularly bulky structures. The ionizing radiation-curable resin having a cyclic structure may or may not have a substituent on the cyclic structure. When the ionizing radiation-curable resin having a cyclic structure has a substituent on the cyclic structure, the term "cyclic structure" refers to the ring portion that does not contain a substituent. When the ionizing radiation curable resin having a cyclic structure has a bulky substituent such as a tert-butyl group in the cyclic structure, it is thought that in addition to the cyclic structure, the bulky substituent portion also functions to prevent dye molecules of the hair dye from coming into contact with the ionizing radiation curable resin which does not have a cyclic structure when the hair dye adheres to the surface protective layer 5.

[0074] The ionizing radiation curable resin having a cyclic structure is preferably an acrylate. Examples of the ionizing radiation curable resin having a cyclic structure include cyclohexyl (meth)acrylate, 3,3,5-trimethylcyclohexyl (meth)acrylate, 4-tert-butylcyclohexyl (meth)acrylate, cyclopentyl (meth)acrylate, dicyclopentanyl (meth)acrylate, 3,4-epoxycyclohexylmethyl acrylate, 6,7-epoxydecahydro-1,4:5,8-dimethanonaphthalen-2-yl acrylate, tricyclodecane dimethanol diacrylate, and isobornyl (meth)acrylate. acrylate, 2-adamantylprop-2-enoate (i.e., 2-adamantyl acrylate), 1-adamantyl(meth)acrylate, 3-hydroxy-1-adamantyl(meth)acrylate, 2-methyl-2-adamantyl(meth)acrylate, 2-ethyl-2-adamantyl(meth)acrylate, 2-isopropyl-2-adamantyl(meth)acrylate, 1,3-adamantanediol di(meth)acrylate, benzyl(meth)acrylate, phenoxyethyl(meth)acrylate, and the like. Here, the term "(meth)acrylate" is used to encompass acrylate, methacrylate, and combinations thereof. These "ionizing radiation-curable resins having a cyclic structure" may be used alone or in combination of two or more.

[0075] The ionizing radiation curable resin having a cyclic structure is, for example, monofunctional or bifunctional. The ionizing radiation curable resin having a cyclic structure is preferably monofunctional. When the ionizing radiation curable resin having a cyclic structure is monofunctional, a surface protection layer having a better surface condition, i.e., a surface protection layer having more uniformly wrinkled surfaces, can be obtained.

[0076] The ionizing radiation curable resin preferably contains the ionizing radiation curable resin having a cyclic structure in a proportion within a range of 10 to 85% by mass, more preferably 10 to 80% by mass, and even more preferably 30 to 60% by mass.

[0077] Preferably, the ionizing radiation curable resin further contains an oligomer having 10 or less functionalities. Such an oligomer is preferably a urethane acrylate or an acrylic acrylate. Preferably, the oligomer is a di- to deca-functional oligomer. Preferably, the oligomer does not have a cyclic structure. That is, the oligomer is preferably a chain acrylate. When an oligomer is contained in the surface protective layer, the shaping property of the surface protective layer can be improved. Furthermore, a low-functional oligomer is preferred in that a low gloss can be achieved.

[0078] Examples of oligomers include EBECRYL9270 (difunctional urethane acrylate) (Daicel-Allnex Corporation), EBECRYL4666 (tetrafunctional urethane acrylate) (Daicel-Allnex Corporation), EBECRYL5129 (hexafunctional urethane acrylate) (Daicel-Allnex Corporation), UN-904 (decafunctional urethane acrylate) (Negami Chemical Industrial Co., Ltd.), and OAP-5000 (acrylic acrylate) (Negami Chemical Industrial Co., Ltd.). The oligomers may be used alone or in combination of two or more.

[0079] The ionizing radiation curable resin preferably contains the above-mentioned oligomer in a proportion within a range of 20 to 70% by mass, more preferably 25 to 60% by mass, and even more preferably 30 to 50% by mass.

[0080] The oligomer is preferably contained in the surface protective layer in an amount of 25 to 200 parts by mass, more preferably 30 to 150 parts by mass, based on 100 parts by mass of the ionizing radiation curable resin having a cyclic structure.

[0081] The ionizing radiation curable resin preferably further contains a monomer. The monomer is preferably an acrylate. The monomer is preferably a monofunctional to tetrafunctional monomer. The monomer preferably has a viscosity of about 100 mPa·s or less at 25°C. The monomer preferably does not have a cyclic structure. That is, the monomer is preferably a chain acrylate. When the monomer is contained in the surface protective layer, the scratch resistance of the surface protective layer can be improved. Furthermore, the monomer can reduce the viscosity of the coating liquid for the surface protective layer.

[0082] Examples of the monomer include tripropylene glycol diacrylate, 1,6-hexanediol diacrylate, dipropylene glycol diacrylate, PO-modified neopentyl glycol diacrylate, trimethylolpropane triacrylate, trimethylolpropane ethoxy triacrylate, glycerin propoxy triacrylate, pentaerythritol, pentaerythritol ethoxy tetraacrylate, pentaerythritol (tri / tetra)acrylate, etc. The monomer may be used alone or in combination of two or more.

[0083] The ionizing radiation curable resin preferably contains the above-mentioned monomer in a proportion within a range of 0 to 60% by mass, more preferably 10 to 50% by mass, and even more preferably 20 to 40% by mass.

[0084] The above-mentioned monomer is contained in the surface protective layer in an amount of preferably 10 to 1,000 parts by mass, more preferably 20 to 800 parts by mass, based on 100 parts by mass of the ionizing radiation curable resin having a cyclic structure.

[0085] As described above, the main component of the ionizing radiation curable resin (i.e., the entire ionizing radiation curable resin including the ionizing radiation curable resin having a cyclic structure) 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. Several types of acrylate may be mixed, but the average number of functional groups thereof is preferably 1.1 or more. To obtain a surface protective layer 5 with excellent scratch resistance, the average number of functional groups is preferably 2.0 or more. There is no upper limit to the average number of functional groups of the acrylate, but according to one example, it is 6.0 or less.

[0086] The surface protection layer 5 may contain particles. Adding particles of an optimal particle size and content can form a uniform surface. Examples of particles that can be used include organic materials such as polyethylene (PE) wax, polypropylene (PP) wax, and resin beads, as well as inorganic materials such as silica, glass, alumina, titania, zirconia, calcium carbonate, and barium sulfate. The average particle size (D50) of the particles is preferably 10 μm or less. The average particle size (D50) of the particles is preferably 3 μm or more. The average particle size (D50) of the particles is preferably 3 μm or more and 10 μm or less, and more preferably 4 μm or more and 10 μm or less.

[0087] When the surface protective layer 5 contains particles, wrinkles can be more uniformly formed on the coating surface in the first irradiation step described below. If large particles are used, the particles are likely to fall off from the surface protective layer 5, making it difficult to achieve high scratch resistance. If the particles are small, the effect of forming wrinkles uniformly is small.

[0088] 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.

[0089] The particles are preferably contained in the surface protective layer 5 in an amount ranging from 0.5 to 10 parts by mass, based on 100 parts by mass of the entire ionizing radiation curable resin. The amount of particles added is more preferably in the range of from 3 to 10 parts by mass, and even more preferably in the range of from 4 to 10 parts by mass, based on 100 parts by mass of the entire ionizing radiation curable resin. Note that "100 parts by mass of ionizing radiation curable resin" refers to the parts by mass of the solid content of the resin.

[0090] When the amount of particles added is within the above range, the effect of generating wrinkles uniformly is particularly large. When the amount of particles added is large, the particles tend to fall off from the surface protective layer 5, making it difficult to achieve high scratch resistance. When the amount of particles added is small, the effect of generating wrinkles uniformly is small.

[0091] When the entire surface protective layer 5 is cured by UV light, it is necessary to add a photopolymerization initiator to the surface protective layer 5. The photopolymerization initiator is not particularly limited, but examples thereof include benzaphenone-based, acetophenone-based, benzoin ether-based, and thioxanthone-based initiators.

[0092] The surface protective layer 5 may further contain additives such as antibacterial agents and antifungal agents to impart required functions. Furthermore, as other additives, the surface protective layer 5 may further contain ultraviolet absorbers and light stabilizers as necessary. Generally, ultraviolet absorbers such as benzotriazoles, benzoates, benzophenones, and triazines are used as ultraviolet absorbers, and light stabilizers such as hindered amines are used as light stabilizers, and these are generally added in any combination.

[0093] Examples of hindered amine light stabilizers that can be used include bis(1,2,2,6,6-pentamethyl-4-piperidyl)[[3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl]methyl]butyl malonate (typical examples include those available from BASF under the trade name "Tinuvin 144"), BASF under the trade name "Tinuvin 123", and a reaction product of decanedioic acid bis(2,2,6,6-tetramethyl-1-(octyloxy)-4-piperidinyl) ester (1,1-dimethylethyl hydroperoxide) and octane.

[0094] When a hindered amine light stabilizer is added to the surface protective layer 5, it is preferably added in an amount ranging from 0.05 to 5 parts by mass relative to 100 parts by mass of the ionizing radiation-curable resin. The amount of hindered amine light stabilizer added is more preferably from 0.2 to 3 parts by mass. If the amount of hindered amine light stabilizer added is less than 0.05 parts by mass, the resin's stability against ultraviolet light may be reduced. On the other hand, if the amount added is more than 5 parts by mass, bleed-out may occur. Furthermore, the surface protective layer 5 can be formed by irradiating light of 200 nm or less to cure and shrink the surface vicinity, forming a fine uneven shape. In this case, if the hindered amine light stabilizer is added in an amount greater than 3 parts by mass, curing of the surface vicinity may be inhibited. In order to achieve both low gloss and weather resistance, it is desirable to add the hindered amine light stabilizer in an amount ranging from 3 parts by mass or less.

[0095] The glossiness of the surface protective layer 5 is preferably 10.0 or less. The glossiness of the surface protective layer 5 is more preferably 5.0 or less. Here, the "glossiness" is a measured value measured at an incident angle of 60 degrees using a glossmeter conforming to JIS Z8741:1997.

[0096] <1.5> Primer Layer The material for the primer layer 6 can basically be the same as that for the design layer 3. Considering that the primer layer 6 is applied to the back surface of the decorative sheet 1 and is wound up in web form, 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 or more and 3.0 μm or less, as its purpose is to ensure adhesion with the substrate B. The primer layer 6 is necessary when the base layer 2 has an inactive surface, such as an olefin-based material, but is not particularly necessary when the surface is active.

[0097] <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, adhesive resin layer 4b, and primer layer 6 are omitted here.

[0098] First, a coating film made of a coating liquid for a surface protective layer is formed on one surface of the base layer 2. As described in the section <1.4> Surface protective layer, the coating liquid for a surface protective layer contains an ionizing radiation curable resin and, if necessary, particles and additives. The coating film made of the coating liquid for a surface protective layer can be formed, for example, by printing.

[0099] 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 the crosslinking reaction does not proceed in other regions, leaving the other regions uncured.

[0100] 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.

[0101] 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 occurs only on the surface of the coating film, and regions more than tens to hundreds of nanometers away from the outermost surface are uncured and contain 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, which causes the cured film to buckle, resulting in wrinkles on the surface of the coating film.

[0102] The first radiation can be extracted from excimer VUV 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.

[0103] The gas used in the excimer lamp may be any conventional gas that emits light of 200 nm or less. Examples of suitable gases include rare gases such as Xe, Ar, and Kr, and mixtures of rare gases such as ArBr and ArF with halogen gases. The center wavelength of excimer lamps varies depending on the gas used, with wavelengths of approximately 172 nm (Xe), approximately 126 nm (Ar), approximately 146 nm (Kr), approximately 165 nm (ArBr), and approximately 193 nm (ArF).

[0104] 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.

[0105] 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 2000 ppm or less, and more preferably 1000 ppm or less.

[0106] 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.

[0107] The integrated light amount of the first radiation is 0.5 mJ / cm ２ More than 200mJ / cm ２ It is preferable that the dose is 1 mJ / cm or less. ２ More than 100mJ / cm ２ More preferably, it is 3 mJ / cm or less. ２ More than 50mJ / cm ２ More preferably, it is 5 mJ / cm or less. ２ 30mJ / cm or more ２It is most preferable to set the integrated light dose as follows: If the integrated light dose is small, the expansion of the cured film in the in-plane direction will be small; if the integrated light dose is large, the surface condition of the coating film will deteriorate.

[0108] 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.

[0109] The second radiation is ionizing radiation such as an electron beam, or ultraviolet radiation having a longer wavelength than the first radiation. When ultraviolet radiation is used as the second radiation, the ultraviolet radiation has a wavelength at which the ionizing radiation curable resin exhibits a small absorption coefficient.

[0110] 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:

[0111] <3> Functions and Others The decorative sheet 1 according to this embodiment has a surface protective layer 5 with an uneven surface. The decorative sheet 1 according to this embodiment also contains a cured product of an ionizing radiation curable resin in the surface protective layer 5, and the ionizing radiation curable resin contains a predetermined amount of an ionizing radiation curable resin having a cyclic structure. This gives the decorative sheet 1 according to this embodiment low gloss and excellent resistance to staining and contamination.

[0112] Furthermore, because the decorative sheet 1 according to this embodiment includes a surface protective layer 5 having an uneven surface, the gloss (gloss level) of the surface protective layer can be adjusted even without including a gloss adjuster (matt additive) in the surface protective layer. Gloss adjusters reduce the oil repellency of layers formed from resin materials, making them more susceptible to fingerprints. Because the surface protective layer 5 does not include a gloss adjuster, it does not absorb oil, resulting in relatively improved oil repellency. Therefore, in various situations, such as during on-site construction, furniture assembly, and in the daily lives of residents, fingerprints are less likely to adhere to the decorative sheet 1 having the surface protective layer 5.

[0113] Furthermore, by forming an uneven surface on the surface protective layer 5, the oil repellency of the surface protective layer 5 is improved, making it possible to suppress oil stains and adsorption of contaminants onto the surface of the decorative sheet 1.

[0114] Furthermore, by configuring the surface protection layer 5 so as not to contain a gloss adjusting agent, the particles of the gloss adjusting agent do not fall off when the surface of the decorative sheet 1 is scratched, making it possible to make the surface of the decorative sheet 1 less susceptible to changes in gloss or scratches.

[0115] Furthermore, since the surface protection layer 5 does not contain a gloss adjuster, whitening that can occur due to a gloss adjuster does not occur during bending, and therefore it is possible to prevent deterioration of bending workability.

[0116] The reason why the surface protection layer 5 having the above-described surface properties can be obtained by the above-described method is as follows.

[0117] Oxygen in the gas phase not only absorbs short-wavelength ultraviolet rays 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.

[0118] 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 particle size and amount of particles added in the coating film, as well as the thickness of the coating film, also affect the formation of wrinkles.

[0119] Therefore, for example, by appropriately setting the composition of the ionizing radiation curable resin, 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.

[0120] The following describes examples of the present invention.

[0121] Example 1 A 55 μm thick olefin film (manufactured by Riken Technos Corporation) was used as the base fabric layer 2, one side of which was subjected to a corona treatment, and a pattern was printed on that side to form a pattern layer 3. The pattern layer 3 was formed using a two-component urethane ink (V180; manufactured by Toyo Ink Co., Ltd.) to which 0.5 parts by mass of a hindered amine light stabilizer (Chimasorb 944; manufactured by BASF) was added relative to the binder resin content of the ink.

[0122] Next, a primer layer 6 was formed on the back surface of the raw fabric layer 2. The primer layer 6 was formed by printing with the same two-component urethane ink as used for the design layer 3.

[0123] Next, a coating liquid for a surface protective layer was applied onto the design layer 3. The thickness of the coating liquid for a surface protective layer was 5 μm. The coating liquid for a surface protective layer was prepared by blending the following ionizing radiation curable resin with the following additives (particles, photopolymerization initiator). Ionizing radiation curable resin Resin 1 (resin having a cyclic structure): Type: 2-adamantylprop-2-enoate (steric cyclic acrylate) Blend: 40 parts by mass Resin 2 (monomer): Type: tripropylene glycol diacrylate (TPGDA) (bifunctional acrylate) Blend: 30 parts by mass Resin 3 (oligomer): Type: EBECRYL 9270 (bifunctional urethane acrylate) (manufactured by Daicel Allnex Corporation) Blend: 30 parts by mass Particles Product name: Sylysia 250N (manufactured by Fuji Silysia Chemical Ltd.) Particle size: 5 μm Blend: 5 parts by mass Photopolymerization initiator Product name: Omnirad 184 (manufactured by IGM Resins) Blend: 3 parts by mass.

[0124] In Resin 1 (a resin having a cyclic structure) used in Example 1, the cyclic structure is an adamantyl group (C １０ H １５ Since the adamantyl group is a bridged ring, Resin 1 used in Example 1 can be called a stereocyclic acrylate.

[0125] Thereafter, the first irradiation step was carried out. Specifically, under atmospheric pressure in a nitrogen gas atmosphere with an oxygen concentration of 100 ppm, ultraviolet light having a wavelength of 172 nm was irradiated onto the surface of the coating film made of the coating liquid for surface protective layer using a Xe excimer lamp at an integrated light intensity of 30 mJ / cm. ２ This caused wrinkles to form on the surface of the coating film.

[0126] Subsequently, a second irradiation step was carried out. Specifically, the coating film was irradiated with 200 mJ / cm using a high-pressure mercury lamp. ２ The entire surface was cured by irradiating it with ultraviolet light so that the surface protective layer 5 was formed.

[0127] <Example 2> A decorative sheet was obtained in the same manner as in Example 1, except that Resin 1 (a resin having a cyclic structure) used in Example 1 was replaced with the following: Type: dicyclopentanyl acrylate (stereocyclic acrylate) Blend: 40 parts by mass. In Resin 1 (a resin having a cyclic structure) used in Example 2, the cyclic structure is a dicyclopentanyl group (C １０ H １５ Since the dicyclopentanyl group is a bridged ring, Resin 1 used in Example 2 can be called a stereocyclic acrylate.

[0128] Example 3 A decorative sheet was obtained in the same manner as in Example 1, except that Resin 1 (a resin having a cyclic structure) used in Example 1 was replaced with the following: Type: 4-tert-butylcyclohexyl acrylate (cyclic acrylate) Blend: 40 parts by mass. In Resin 1 (a resin having a cyclic structure) used in Example 3, the cyclic structure is formed by the ring portion (C ６ H １０ )

[0129] <Example 4> A decorative sheet was obtained in the same manner as in Example 1, except that Resin 1 (a resin having a cyclic structure) used in Example 1 was replaced with the following: Type: cyclohexyl acrylate (cyclic acrylate) Blend: 40 parts by mass. In Resin 1 (a resin having a cyclic structure) used in Example 4, the cyclic structure is a cyclohexyl group (C ６ H １１ )

[0130] Example 5 A decorative sheet was obtained in the same manner as in Example 1, except that the ionizing radiation curable resin used in Example 1 was replaced with the following: Resin 1 (resin having a cyclic structure): Type: 2-adamantylprop-2-enoate (steric cyclic acrylate) Blend: 10 parts by mass Resin 2 (monomer): Type: tripropylene glycol diacrylate (TPGDA) (bifunctional acrylate) Blend: 30 parts by mass Resin 3 (oligomer): Type: EBECRYL 9270 (bifunctional urethane acrylate) (manufactured by Daicel Allnex Corporation) Blend: 60 parts by mass.

[0131] Example 6 A decorative sheet was obtained in the same manner as in Example 1, except that the ionizing radiation curable resin used in Example 1 was replaced with the following: Resin 1 (resin having a cyclic structure): Type: 2-adamantylprop-2-enoate (steric cyclic acrylate) Blend: 80 parts by mass Resin 3 (oligomer): Type: EBECRYL 9270 (bifunctional urethane acrylate) (manufactured by Daicel Allnex Corporation) Blend: 20 parts by mass.

[0132] <Example 7> A decorative sheet was obtained in the same manner as in Example 1, except that Resin 1 (a resin having a cyclic structure) used in Example 1 was replaced with the following: Type: tricyclodecane dimethanol diacrylate (stereocyclic acrylate) Blend: 40 parts by mass. In Resin 1 (a resin having a cyclic structure) used in Example 7, the cyclic structure is a tricyclodecane group (C １０ H １４ Since the tricyclodecane group is a bridged ring, Resin 1 used in Example 7 can be called a stereocyclic acrylate.

[0133] Example 8 A decorative sheet was obtained in the same manner as in Example 1, except that Resin 3 (oligomer) used in Example 1 was replaced with the following: Type: EBECRYL 4666 (tetrafunctional urethane acrylate) (manufactured by Daicel Allnex Corporation) Blend: 30 parts by mass.

[0134] Example 9 A decorative sheet was obtained in the same manner as in Example 1, except that Resin 3 (oligomer) used in Example 1 was replaced with the following: Type: EBECRYL 5129 (hexafunctional urethane acrylate) (manufactured by Daicel Allnex Corporation) Blend: 30 parts by mass.

[0135] Example 10 A decorative sheet was obtained in the same manner as in Example 1, except that Resin 3 (oligomer) used in Example 1 was replaced with the following: Type: UN-904 (10-functional urethane acrylate) (manufactured by Negami Chemical Industrial Co., Ltd.) Blend: 30 parts by mass.

[0136] Example 11 A decorative sheet was obtained in the same manner as in Example 1, except that Resin 3 (oligomer) used in Example 1 was replaced with the following: Type: OAP-5000 (acrylic acrylate) (manufactured by Negami Chemical Industrial Co., Ltd.) Blend: 30 parts by mass.

[0137] Example 12 A decorative sheet was obtained in the same manner as in Example 1, except that the ionizing radiation curable resin used in Example 1 was replaced with the following: Resin 1 (resin having a cyclic structure): Type: 2-adamantylprop-2-enoate (stereocyclic acrylate) Blend: 4 parts by mass Resin 2 (monomer): Type: tripropylene glycol diacrylate (TPGDA) (bifunctional acrylate) Blend: 66 parts by mass Resin 3 (oligomer): Type: EBECRYL 9270 (bifunctional urethane acrylate) (manufactured by Daicel Allnex Corporation) Blend: 30 parts by mass.

[0138] Example 13 A decorative sheet was obtained in the same manner as in Example 1, except that the ionizing radiation curable resin used in Example 1 was replaced with the following: Resin 1 (resin having a cyclic structure): Type: 2-adamantylprop-2-enoate (steric cyclic acrylate) Blend: 90 parts by mass Resin 3 (oligomer): Type: EBECRYL 9270 (bifunctional urethane acrylate) (manufactured by Daicel Allnex Corporation) Blend: 10 parts by mass.

[0139] Comparative Example 1 A decorative sheet was obtained in the same manner as in Example 1, except that the blending amount of the particles added in Example 1 was changed as follows and the first irradiation step carried out in Example 1 was not carried out: Particles Product name: Sylysia 250N (manufactured by Fuji Silysia Chemical Ltd.) Particle size: 5 μm Blending: 10 parts by mass

[0140] Comparative Example 2 A decorative sheet was obtained in the same manner as in Example 1, except that Resin 1 (a resin having a cyclic structure) used in Example 1 was replaced with the following: Type: butyl acrylate (chain acrylate) Blend: 40 parts by mass.

[0141] Comparative Example 3 A decorative sheet was obtained in the same manner as in Example 1, except that the ionizing radiation curable resin used in Example 1 was replaced with the following: Resin 2 (monomer): Type: tripropylene glycol diacrylate (TPGDA) (bifunctional acrylate) Blend: 70 parts by mass Resin 3 (oligomer): Type: EBECRYL 9270 (bifunctional urethane acrylate) (manufactured by Daicel Allnex Corporation) Blend: 30 parts by mass.

[0142] <Evaluation> Each of the above decorative sheets was evaluated as follows. (1) Thickness of the Surface Protective Layer The thickness of the surface protective layer was measured as follows. The decorative sheet was embedded in a resin such as a cold-curing epoxy resin or a UV-curable resin, and the resin was allowed to fully cure. The sheet was then cut so that the cross section of the decorative sheet was exposed, and mechanically polished to obtain a measurement surface. Subsequently, the cross section of the surface protective layer was imaged using a SIGMA 500 scanning electron microscope manufactured by Carl Zeiss Microscopy. The imaging was performed at an acceleration voltage of 0.5 keV (low acceleration voltage), in the SE2 imaging mode, and at a magnification of 2000x. No sputtering was performed on the measurement sample. Next, from this cross-sectional image, the dimension of the surface protective layer in the width direction of the ridge portion and the area of ​​the cross section of the surface protective layer were determined. The thickness of the surface protective layer was calculated by dividing this area by the above dimension. Measurements were performed at 25 random points, and the average value of the 25 points was defined as the "thickness t of the surface protective layer." The "thickness t of the surface protective layer" was equal to the thickness of the coating film made of the coating liquid for the surface protective layer.

[0143] (2) Surface Condition The surface condition was evaluated visually for uniformity of the surface. The evaluation criteria were as follows: AA: Very uniform surface condition A: Uniform surface condition B: Some uneven areas present C: Ununiform surface condition over the entire surface.

[0144] (3) Glossiness The glossiness was measured at 60 degrees using a Rhopoint IQ (manufactured by Konica Minolta, Inc.).

[0145] (4) Fingerprint Resistance To evaluate fingerprint resistance, fingerprint wiping ability was evaluated. The 60-degree glossiness of the surface of each decorative sheet was measured and defined as "initial glossiness." Next, a fingerprint resistance evaluation liquid was applied to the surface protective layer of each decorative sheet, and then the fingerprint resistance evaluation liquid applied to the surface of the decorative sheet was wiped off. Thereafter, the 60-degree glossiness of the portion from which the fingerprint resistance evaluation liquid had been wiped off was measured and defined as "glossiness after wiping." Here, a higher fatty acid was used as the fingerprint resistance evaluation liquid.

[0146] The fingerprint wiping rate was calculated using the following formula: Fingerprint wiping rate (%) = (glossiness after wiping / initial glossiness) x 100 The evaluation criteria were as follows: A: 70% or more and less than 250% B: 50% or more and less than 70%, or 250% or more and less than 300% C: Less than 50%, or 300% or more.

[0147] (5) Resistance to Staining and Coloring To evaluate resistance to staining and coloring, resistance to staining and coloring caused by hair dye was evaluated. A hair dye was applied to the surface protective layer of each decorative sheet and left for 24 hours. Bigen Cream Tone 7G (natural blackish brown) (Hoyu Corporation) was used as the hair dye. The hair dye was then wiped off with a cloth soaked in water, and the degree of staining was evaluated visually.

[0148] The evaluation criteria were as follows: AA: No coloring at all A: Some coloring is present but is barely noticeable B: Overall, the coloring is faintly noticeable C: Colored.

[0149] (6) Scratch Resistance To evaluate scratch resistance, a nail scratch test was carried out. The surface of the surface protection layer of each decorative sheet was scratched in one direction with a fingernail, and the occurrence of scratches and changes in gloss were visually confirmed.

[0150] The evaluation criteria were as follows: AA: No change in appearance A: Slight change in gloss B: Slight scratches C: Clear scratches.

[0151] (7) Workability To evaluate workability, a wrapping test was conducted. A decorative sheet was attached to MDF (Medium Density Fiberboard) with an adhesive, grooved, and bent at a 90-degree angle. The surface of each decorative sheet was observed under an optical microscope to check for whitening or cracks at the bent portion, and the workability was evaluated. This wrapping workability corresponds to so-called bending workability.

[0152] The evaluation criteria were as follows: A: No whitening or cracks were observed B: Whitening was observed in some areas C: Whitening was observed over the entire surface, or cracks were observed in some areas.

[0153] The evaluation results are shown in the table below. Evaluation results of B or higher are considered to be passing.

[0154]

[0155]

[0156]

[0157] The above table shows the composition of the ionizing radiation curable resin, as well as the proportion (mass %) of the "cyclic structure portion of resin 1 (resin having a cyclic structure)" in the entire ionizing radiation curable resin. When resin 1 (resin having a cyclic structure) has a substituent in the cyclic structure, the "cyclic structure portion" refers to the ring portion that does not contain the substituent.

[0158] As shown in the table, the decorative sheets of Examples 1 to 13 contained a cured product of an ionizing radiation curable resin in the surface protective layer, and the ionizing radiation curable resin contained an ionizing radiation curable resin having a cyclic structure. The decorative sheets of Examples 1 to 13 had low gloss and excellent resistance to discoloration and staining. Furthermore, the decorative sheets of Examples 1 to 12 contained a cured product of an ionizing radiation curable resin in the surface protective layer, and the ionizing radiation curable resin contained an ionizing radiation curable resin having a cyclic structure, such that the cyclic structure portion accounted for 2 to 45 mass% of the total ionizing radiation curable resin. The decorative sheets of Examples 1 to 12 had low gloss and excellent fingerprint resistance, discoloration and stain resistance, scratch resistance, and processability.

[0159] The decorative sheet according to Comparative Example 1 did not have an uneven structure on the surface of the surface protective layer, which included a plurality of ridge-like portions, each of which protruded in a ridge-like shape. Furthermore, the decorative sheets according to Comparative Examples 2 and 3 did not include an ionizing radiation curable resin having a cyclic structure. None of the decorative sheets according to Comparative Examples 1 to 3 achieved excellent resistance to coloring and staining.

[0160] 1...decorative sheet, 2...raw material layer, 3...pattern layer, 4...transparent resin layer, 4a...embossed pattern, 4b...adhesive resin layer, 5...surface protection layer, 5A...core portion, 5B...ridge portion, 6...primer 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 the surface of the surface protective layer is provided with an uneven structure including a plurality of ridge-like portions each protruding in a ridge-like shape, the surface protective layer including a cured product of an ionizing radiation curable resin, and the ionizing radiation curable resin including an ionizing radiation curable resin having a cyclic structure.

2. The decorative sheet according to claim 1, wherein the ionizing radiation curable resin contains an ionizing radiation curable resin having a cyclic structure, the portion with the cyclic structure occupying an amount within the range of 2 to 45 mass % of the entire ionizing radiation curable resin.

3. The decorative sheet according to claim 1, wherein said cyclic structure is composed of monocyclic to tetracyclic hydrocarbons.

4. The decorative sheet according to claim 1, wherein said ionizing radiation curable resin having a cyclic structure is an acrylate.

5. The decorative sheet according to claim 1, wherein said ionizing radiation curable resin having a cyclic structure is monofunctional.

6. The decorative sheet according to claim 1, wherein said ionizing radiation curable resin further contains an oligomer having 10 or less functionalities.

7. The decorative sheet according to claim 6, wherein said oligomer is a urethane acrylate or an acrylic acrylate.

8. The decorative sheet according to claim 1, wherein the uneven structure of the surface protective layer has an RSm / Ra in the range of 10 to 600.

9. The decorative sheet according to claim 1, wherein the thickness of said surface protective layer is within the range of 2 to 20 μm.

10. The decorative sheet according to claim 1, wherein said surface protective layer further contains particles having an average particle size of 10 μm or less.

11. The decorative sheet according to claim 10, wherein the particles are contained in the surface protective layer in an amount within the range of 0.5 to 10 parts by mass, assuming the entire ionizing radiation curable resin to be 100 parts by mass.

12. The decorative sheet according to claim 1, wherein the gloss of said surface protective layer is 10 or less.

13. A decorative material comprising: a decorative sheet according to any one of claims 1 to 12; and a substrate to which the decorative sheet is attached.

14. A method for producing a decorative sheet comprising: forming a coating film made of a coating liquid for a surface protective layer on one side of an original fabric layer; irradiating the coating film with light having a wavelength of 200 nm or less; and, after the irradiation, irradiating with ionizing radiation or ultraviolet light having a longer wavelength than the light, wherein the coating liquid for the surface protective layer contains an ionizing radiation curable resin, and the ionizing radiation curable resin contains an ionizing radiation curable resin having a cyclic structure.

15. The method of claim 14, wherein the light has a wavelength of 172 nm.

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