Decorative sheet

Abstract

Provided is a technique with which it is possible to suppress the generation of a stain or a trace thereof caused by water absorption in a decorative sheet comprising a paper-containing raw fabric layer and a pigment-containing layer. A decorative sheet (1) comprises: a paper-containing raw fabric layer (2); a pigment-containing layer (3) provided on the raw fabric layer (2), the pigment-containing layer (3) containing a pigment and a binder resin; a primer layer (4) provided on the pigment-containing layer (3); and a surface protective layer (5) provided on the primer layer (4). The primer layer (4) contains only a cured product of a first ionizing-radiation-curable resin serving as a resin cured product. The first ionizing-radiation-curable resin is a first mixture of acrylate and methacrylate. The surface protective layer (5) contains only a cured product of a second ionizing-radiation-curable resin serving as a resin cured product. A structure of recesses and protrusions including a plurality of ridge-form parts, each of which protrudes in the form of a ridge, is provided to the surface of the surface protective layer (5).

Description

Decorative sheet

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

[0002] Decorative sheets are used to decorate the surfaces of interior and exterior materials such as building fixtures, furniture, fixtures, and flooring materials, for the purpose of imparting design and durability to these 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 glossiness of the surface is also important for the design of decorative sheets. There are a variety of decorative sheets to choose from depending on the application and preference, ranging from high gloss like a mirror to low gloss that does not reflect light at all.

[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] Furthermore, decorative sheets are generally subjected to processes such as cutting and bending in order to form decorative materials such as decorative plates, and therefore it is preferable that the decorative sheets have processability that can withstand these processes.

[0008] 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.

[0009] Japanese Patent Application Publication No. 2019-119138

[0010] The present invention aims to provide a technology that can prevent stains or traces of stains caused by water absorption from occurring in a decorative sheet having a paper-containing base layer and a pigment-containing layer.

[0011] According to one aspect of the present invention, there is provided a decorative sheet comprising: a base fabric layer containing paper; a pigment-containing layer provided on the base fabric layer and containing a pigment and a binder resin; a primer layer provided on the pigment-containing layer; and a surface protective layer provided on the primer layer, wherein the primer layer contains only a cured product of a first ionizing radiation curable resin as a resin cured product, and the first ionizing radiation curable resin is a first mixture of acrylate and methacrylate; the surface protective layer contains only a cured product of a second ionizing radiation curable resin as a resin cured product; and the decorative sheet has a surface provided with an uneven structure including a plurality of ridge-like portions each protruding in a ridge-like shape.

[0012] According to another aspect of the present invention, there is provided a decorative sheet according to the above aspect, wherein in the primer layer, the proportion of the number of moles of methacryloyl groups to the total number of moles of acryloyl groups and the number of moles of methacryloyl groups is in the range of 3% or more and 50% or less.

[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 methacrylate is a monofunctional, difunctional, or trifunctional methacrylate.

[0014] According to yet another aspect of the present invention, there is provided a decorative sheet according to any of the above aspects, wherein the mass of the filler in the primer layer is 10 parts by mass or less when the mass of the first ionizing radiation curable resin is 100 parts by mass.

[0015] According to yet another aspect of the present invention, there is provided a decorative sheet according to any of the above aspects, wherein the second ionizing radiation curable resin is an acrylate or a second mixture of an acrylate and a methacrylate, and the second mixture has a smaller proportion of the number of moles of methacryloyl groups in the sum of the number of moles of acryloyl groups and the number of moles of methacryloyl groups compared to the first mixture.

[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 second ionizing radiation curable resin contains a di- or higher functional acrylate containing a repeating structure.

[0017] According to yet another aspect of the present invention, there is provided a decorative sheet according to the above aspect, wherein the repeating structure is repeated three or more times.

[0018] 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 primer layer is in the range of 0.5 μm to 10 μm.

[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 thickness of the surface protective layer is in the range of 2 μm or more and 20 μm or less.

[0020] 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.

[0021] According to yet another aspect of the present invention, there is provided a decorative sheet according to the above aspect, in which the mass of the particles is in the range of 0.5 parts by mass or more and 20 parts by mass when the mass of the second ionizing radiation curable resin is 100 parts by mass.

[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 uneven structure has a ratio RSm / Ra of the average length RSm of the roughness curve elements to the arithmetic mean roughness Ra in the range of 10 or more and 800 or less, preferably 10 or more and 700 or less.

[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 surface protective layer has a specular gloss GS(60°) of 20 or less.

[0024] According to yet another aspect of the present invention, there is provided a decorative material comprising the decorative sheet according to any one of the above aspects and a substrate to which the decorative sheet is attached.

[0025] According to yet another aspect of the present invention, there is provided a method for producing a decorative sheet, comprising: forming a pigment-containing layer containing a pigment and a binder resin on a base layer containing paper; forming a first coating film on the pigment-containing layer, the first coating film containing only a first ionizing radiation curable resin as a resin, the first ionizing radiation curable resin being a first mixture of acrylate and methacrylate; performing a first irradiation step of irradiating the first coating film with ionizing radiation or ultraviolet light to semi-cure the first coating film; forming a second coating film on the semi-cured first coating film, the second coating film containing only a second ionizing radiation curable resin as a resin; and irradiating the first coating film and the second coating film with ionizing radiation or ultraviolet light to completely cure the first coating film and the second coating film.

[0026] According to yet another aspect of the present invention, there is provided a method for producing a decorative sheet according to the above aspect, wherein the complete curing of the first coating film and the second coating film includes a second irradiation step in which the second coating film is irradiated with light having a wavelength of 200 nm or less, and then a third irradiation step in which the first coating film and the second coating film are irradiated with ionizing radiation or ultraviolet light having a longer wavelength than the light irradiated in the second irradiation step.

[0027] According to yet another aspect of the present invention, there is provided a method for producing a decorative sheet according to any of the above aspects, wherein the irradiation of the first coating film with ionizing radiation or ultraviolet light in the first irradiation step is carried out so that the ratio of the number of C=C bonds after irradiation to the number of C=C bonds before irradiation is within the range of 5% or more and 80% or less.

[0028] According to yet another aspect of the present invention, there is provided a method for manufacturing a decorative sheet according to any of the above aspects, in which the ionizing radiation or ultraviolet light is irradiated onto the first coating film in the first irradiation step so that the cumulative light amount is within the range of 3% to 30% of the minimum cumulative light amount required to completely cure the first coating film.

[0029] According to yet another aspect of the present invention, there is provided a method for manufacturing a decorative sheet according to any of the above aspects, wherein the irradiation of the first coating film with ionizing radiation or ultraviolet light in the first irradiation step is carried out so that the absorbed dose is within the range of 0.2% or more and 50% or less of the minimum absorbed dose required to completely cure the first coating film.

[0030] According to the present invention, a technique is provided that can prevent stains or traces thereof caused by water absorption from occurring in a decorative sheet having a base layer containing paper and a pigment-containing layer.

[0031] 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. Fig. 4 is a cross-sectional view showing an enlarged portion of the surface protective layer shown in Fig. 2.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] <1> Decorative material and decorative sheet Figure 1 is a cross-sectional view of a decorative material including a decorative sheet according to one embodiment of the present invention. Figure 2 is a cross-sectional view of a surface protective layer included in the decorative sheet of Figure 1. Figure 3 is a micrograph of a surface layer included in a decorative sheet according to one example of the present invention. Figure 4 is a cross-sectional view showing an enlarged portion of the surface protective layer shown in Figure 2.

[0036] 2 and 4 are cross sections taken along the thickness direction of the surface protection layer, and the micrograph in Fig. 3 is a plan view taken with a laser microscope (OLS-4000 manufactured by Olympus Corporation).

[0037] 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.

[0038] 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.

[0039] The decorative sheet 1 includes a base fabric layer 2, a pigment-containing layer 3, a primer layer 4, and a surface protective layer 5. The pigment-containing layer 3, primer 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 decorative sheet 1 may further include one or more other layers, such as a transparent resin layer. Below, the elements included in the decorative sheet 1 will be explained one by one.

[0040] <1.1> Raw Fabric Layer The raw fabric layer 2 contains paper. The raw fabric layer 2 may have a single-layer structure or a multi-layer structure. In one example, the raw fabric layer 2 is entirely made of paper. In another example, the raw fabric layer 2 has a multi-layer structure, and at least the outermost layer facing the surface protective layer 5 is made of paper. When the raw fabric layer 2 has a multi-layer structure, it may include one or more layers made of a material other than paper in addition to one or more layers made of paper.

[0041] The paper may be, for example, tissue paper, resin-mixed paper, titanium paper, resin-impregnated paper, flame-retardant paper, or inorganic paper. The paper contained in the raw paper layer 2 may be, for example, paper containing cellulose fibers. The raw paper layer 2 may have various forms, such as a film, a sheet, a plate, or a specially shaped molded body.

[0042] <1.2> Pigment-Containing Layer The pigment-containing layer 3 is, for example, a continuous film formed by coating one entire surface of the base fabric layer 2 with ink. The layers contained in the pigment-containing layer 3 contain at least one of a white pigment and a colored pigment as a pigment. The pigment-containing layer 3 can function as a concealing layer that conceals the substrate B or the base fabric layer 2. The pigment-containing layer 3 can also function as a planarizing layer.

[0043] The pigment-containing layer 3 may have a single-layer structure or a multi-layer structure. When the pigment-containing layer 3 has a multi-layer structure, all of the layers may be continuous films, all of the layers may be discontinuous films, or one or more layers may be continuous films and the remaining layers may be discontinuous films.

[0044] The pigment-containing layer 3 can be formed using, for example, a printing ink (or a coating agent) in which a binder resin serving as a matrix and a pigment are dissolved or dispersed in a solvent.

[0045] Examples of binder resins that can be used include various synthetic resins such as oil-based nitrocellulose resin, two-component urethane resin, acrylic resin, styrene resin, polyester resin, urethane resin, polyvinyl resin, alkyd resin, epoxy resin, melamine resin, fluorine resin, silicone resin, and daimi rubber resin, as well as mixtures or copolymers of these.

[0046] Examples of pigments that can be used include inorganic pigments such as carbon black, titanium oxide (titanium white), zinc oxide, 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.

[0047] The average particle size of the pigment is preferably in the range of 50 nm to 5 μm, and more preferably in the range of 100 nm to 1 μm. This average particle size is the median diameter (D50) of the particles in the surface protective layer 5, which will be described later.

[0048] The amount of pigment is preferably in the range of 2 parts by mass to 50 parts by mass, and more preferably in the range of 5 parts by mass to 30 parts by mass, per 100 parts by mass of binder resin.

[0049] Examples of the solvent that can be used include toluene, xylene, ethyl acetate, butyl acetate, methyl alcohol, ethyl alcohol, isopropyl alcohol, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, water, and mixtures thereof.

[0050] To the ink, functional additives such as plasticizers, dispersants, surfactants, tackifiers, adhesion aids, drying agents, curing agents, curing accelerators, and curing retarders may be added in order to impart various functions.

[0051] The ink used to form the pigment-containing layer 3 may contain the binder resin in various forms. For example, the ink may be solvent-free. Alternatively, the ink may contain the binder resin in the form of a solution, emulsion, or dispersion. According to one example, the ink contains the binder resin in the form of a water-based emulsion or dispersion. Furthermore, the ink may be cured by volatilization of the solvent, by irradiation with ionizing radiation, or by heat curing.

[0052] <1.3> Primer Layer The primer layer 4 is provided on the pigment-containing layer 3. Here, the primer layer 4 covers the entire surface of one side of the raw fabric layer 2, with the pigment-containing layer 3 sandwiched therebetween.

[0053] The primer layer 4 contains only the cured product of the first ionizing radiation curable resin as the cured resin. According to one example, the primer layer 4 consists essentially of the cured product of the first ionizing radiation curable resin, or essentially of a cured product obtained by curing a mixture of the first ionizing radiation curable resin and a filler. Here, "ionizing radiation" refers to a charged particle beam such as an electron beam. The first ionizing radiation curable resin is cured by irradiation with ionizing radiation. The first ionizing radiation curable resin can also be cured by irradiation with ultraviolet light.

[0054] "The primer layer consists essentially of a cured product of the first ionizing radiation curable resin" means that the primer layer consists solely of a cured product of the first ionizing radiation curable resin, or a cured product obtained by curing a mixture of the first ionizing radiation curable resin and an additive dissolved therein. Also, "the primer layer consists essentially of a cured product obtained by curing a mixture of first ionizing radiation and a filler" means that the primer layer consists solely of a cured product obtained by curing a mixture of the first ionizing radiation curable resin and a filler, or a cured product obtained by curing a mixture of the first ionizing radiation curable resin, an additive dissolved therein, and a filler.

[0055] As described above, the pigment-containing layer 3 can serve as a concealing layer that conceals the substrate B or the raw fabric layer 2. Therefore, the proportion of the pigment in the pigment-containing layer 3 is relatively large. That is, the total area of ​​the interface between the pigment and the resin in the pigment-containing layer 3 is large. Furthermore, because the proportion is large, in forming the pigment-containing layer 3, a binder resin that has high polarity and produces a cured product with a low degree of crosslinking is used in order to sufficiently disperse the pigment.

[0056] The primer layer 4 is a layer provided between the pigment-containing layer 3 and the surface protective layer 5, and is visible light transmissive and preferably colorless and transparent. The primer layer 4 is not a layer containing a high content of particles. Therefore, the primer layer 4 does not have an internal interface, or even if it does have an internal interface, the total area of ​​the interface is small. Furthermore, even if the primer layer 4 contains a filler, the content is small, so the filler can be sufficiently dispersed in the first ionizing radiation curable resin.

[0057] The first ionizing radiation curable resin is a first mixture of an acrylate resin and a methacrylate resin.

[0058] The methacrylate is preferably a monofunctional, difunctional, or trifunctional methacrylate. The methacrylate may be any one of a monofunctional methacrylate, a difunctional methacrylate, and a trifunctional methacrylate, or may be two or more of them.

[0059] When a methacrylate with a large number of functional groups is used, the degree of crosslinking is increased and scratch resistance is improved compared to when a methacrylate with a small number of functional groups is used. However, when a methacrylate with an excessively large number of functional groups is used, the rate of the crosslinking reaction due to irradiation with ionizing radiation or ultraviolet light increases, narrowing the process window in which high adhesion between the primer layer 4 and the surface protective layer 5 can be achieved.

[0060] In the first ionizing radiation curable resin, the proportion of the number of moles of methacryloyl groups to the total number of moles of acryloyl groups and methacryloyl groups is preferably in the range of 3% or more and 50% or less, and more preferably in the range of 5% or more and 40% or less.

[0061] The methacrylate enables the first coating film containing the first ionizing radiation-curable resin to be semi-cured by irradiation with ionizing radiation or ultraviolet light. Increasing the above ratio widens the process window that allows for achieving high adhesion between the primer layer 4 and the surface protective layer 5. However, if the above ratio is excessively increased, the scratch resistance of the decorative sheet 1 decreases.

[0062] The additives added to the first ionizing radiation curable resin are intended to improve the functionality of the final product, as will be described later, and are, for example, one or more of an antibacterial agent, an antifungal agent, an ultraviolet absorber, and a light stabilizer. The total amount of the additives is preferably 15 parts by mass or less, and more preferably 10 parts by mass or less, per 100 parts by mass of the first ionizing radiation curable resin.

[0063] The filler is made of an inorganic compound such as an inorganic oxide, for example, silica, alumina, magnesia, titanium oxide, and barium sulfate.

[0064] The average particle size of the filler is preferably 10 μm or less, more preferably 8 μm or less. The average particle size of the filler is preferably 2 μm or more, more preferably 5 μm or more. This average particle size is the median diameter (D50) of the particles of the surface protective layer 5, which will be described later.

[0065] The amount of filler per 100 parts by mass of the first ionizing radiation curable resin is smaller than the amount of pigment per 100 parts by mass of the binder resin. The amount of filler per 100 parts by mass of the first ionizing radiation curable resin is preferably 10 parts by mass or less, and more preferably 8 parts by mass or less. The primer layer 4 does not need to contain particles such as filler.

[0066] The thickness of the primer layer 4 is preferably in the range of 0.5 μm to 10 μm, more preferably in the range of 1 μm to 8 μm, and even more preferably in the range of 1.5 μm to 6 μm. If the thickness of the primer layer 4 is reduced, the scratch resistance decreases. If the thickness of the primer layer 4 is increased, the processability of the decorative sheet 1 decreases, and it becomes more likely to whiten when folded.

[0067] <1.4> Surface Protective Layer The surface protective layer 5 is provided on the primer layer 4. Here, the surface protective layer 5 covers the entire upper surface of the primer layer 4.

[0068] The specular gloss GS(60°) of the surface protective layer 5 is preferably 20 or less, more preferably 18 or less, and even more preferably 15 or less. For example, the specular gloss GS(60°) of the surface protective layer 5 is 0.5 or more. Here, the "specular gloss GS(60°)" is the specular gloss measured at an incident angle of 60 degrees using a glossmeter conforming to ISO 2813. The specular gloss GS(60°) is sometimes expressed by adding "%" after the numerical value, but the "%" will be omitted here.

[0069] An uneven structure is provided on the surface of the surface protective layer 5. The uneven structure provided on the upper surface of the surface protective layer 5 serves to reduce the specular gloss GS (60°) of the surface protective layer 5.

[0070] Here, an uneven structure including a plurality of ridge-like portions each protruding in a ridge-like shape is provided on the surface of the surface protection layer 5. That is, as shown in Figures 2 and 4, the surface protection layer 5 includes a core portion 5A which is a thin layer having a flat upper surface, and a plurality of ridge-like portions 5B each protruding in a ridge-like shape from the upper surface of the core portion 5A.

[0071] In the present disclosure, the ridge portion 5B refers to, for example, the portion from the lowest part to the tip of the protrusion provided on the surface of the surface protection layer 5, and the core portion 5A refers to the portion of the surface protection layer 5 excluding the ridge portion 5B. Furthermore, the term "ridge-like" refers to a convex shape that extends linearly in a plan view.

[0072] The ridge portions 5B may be curved or linear in plan view, but are preferably curved as shown in Fig. 3 from the viewpoint of fingerprint resistance of the surface of the decorative sheet 1. The surface protection layer 5 having ridge portions 5B can be formed, for example, as described below, by irradiating the surface of a coating film containing a second ionizing radiation curable resin with light of a specific wavelength, and causing the cured film formed on the surface of the coating film to expand in the in-plane direction.

[0073] The uneven structure on the upper surface of the surface protective layer 5 preferably has a ratio RSm / Ra of the average length RSm of the roughness curve elements to the arithmetic mean roughness Ra in the range of 10 to 800, more preferably in the range of 10 to 700. The ratio RSm / Ra is preferably in the range of 10 to 400, and more preferably in the range of 50 to 350. When the ratio RSm / Ra is reduced, the pitch of the convex portions becomes smaller. As a result, it becomes difficult to wipe off dirt adhering to the surface of the decorative sheet 1, and the contamination resistance decreases. When the ratio RSm / Ra is increased, the pitch of the convex portions becomes larger, and the effect of the uneven structure in reducing the specular gloss GS(60°) of the surface protective layer 5 becomes smaller.

[0074] The ratio RSm / Ra is preferably equal to or greater than 80. Increasing the ratio RSm / Ra increases the pitch of the convex portions, improving the affinity of water or detergents (water containing surfactants or alcohol) to the upper surface of the surface protective layer 5. If the surface protective layer 5 of the decorative sheet 1 has such surface properties, even if the surface becomes dirty, the dirt can be easily wiped off with water or detergent.

[0075] It is most preferable that the ratio RSm / Ra is equal to or greater than 100. If the ratio RSm / Ra is within this range, a commonly available cleaning sponge can be brought into contact with the boundaries of the convex portions and the areas in their vicinity on the upper surface of the surface protective layer 5. Therefore, even if the surface of the decorative sheet 1 becomes soiled, the soiling can be easily wiped off using a commonly available cleaning sponge.

[0076] Here, the arithmetic mean roughness Ra and the mean length RSm of the roughness curve elements are measured using a line roughness meter (in accordance with JIS B0601:2013).

[0077] The arithmetic mean roughness Ra is preferably in the range of 0.2 μm to 10.0 μm, more preferably in the range of 0.5 μm to 5.0 μm, and even more preferably in the range of 0.8 μm to 4.0 μm.

[0078] The average length RSm of the roughness curve elements is preferably in the range of 50 μm or more and 800 μm or less, more preferably in the range of 80 μm or more and 600 μm or less, and even more preferably in the range of 100 μm or more and 500 μm or less.

[0079] The upper surface of the surface protection layer 5 may have a sinusoidal shape in a cross section parallel to the thickness direction and the arrangement direction of the ridge portions 5B. Here, the "sinusoidal shape" refers to a shape in which a line extending from the lowest point C of the ridge portions 5B to the highest point D (vertex) can be expressed as a sine wave, as shown in FIG.

[0080] The thickness of the surface protective layer 5 is preferably in the range of 2 μm to 20 μm, more preferably in the range of 3 μm to 20 μm, even more preferably in the range of 5 μm to 15 μm, and most preferably in the range of 5 μm to 12 μm. If the thickness of the surface protective layer 5 is small, it is difficult to achieve the above-mentioned surface properties by the method described below while referring to the ratio RSm / Ra, etc. If the thickness of the surface protective layer 5 is large, the processability of the decorative sheet 1 decreases and it becomes more likely to whiten when folded.

[0081] Here, the thickness of the surface protective layer 5 is 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 is 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. 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 this coating liquid is equal to the thickness of the surface protective layer 5.

[0082] Furthermore, the thickness of the surface protection layer 5 is preferably set so that the ratio of the thickness (or height) of the ridge portion 5B to the thickness of the core portion 5A (thickness of the ridge portion 5B / thickness of the core portion 5A) is within the range of 0.01 or more and 2.0 or less, and more preferably within the range of 0.1 or more and 1.0 or less.

[0083] The surface protective layer 5 contains a cured resin. As described below, the surface protective layer 5 may further contain particles. When the mass of the surface protective layer 5 is taken as 100 parts by mass, the mass of the cured resin contained in the surface protective layer 5 is preferably 60 parts by mass or more, more preferably 70 parts by mass or more, and even more preferably 80 parts by mass or more.

[0084] The surface protection layer 5 contains only the cured product of the second ionizing radiation curable resin as the cured resin product. As described above, the ionizing radiation is a charged particle beam such as an electron beam. The second ionizing radiation curable resin is cured by irradiation with ionizing radiation. The second ionizing radiation curable resin can also be cured by irradiation with ultraviolet light. The second 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.

[0085] The second ionizing radiation curable resin may be any known resin, such as various monomers or commercially available oligomers, including (meth)acrylic resins, silicone resins, polyester resins, urethane resins, amide resins, or epoxy resins. The second ionizing radiation curable resin may be either an aqueous resin or a non-aqueous (organic solvent-based) resin. The second ionizing radiation curable resin may be solvent-free.

[0086] The main component of the second ionizing radiation curable resin is preferably an acrylate, and the main component here means that the content is 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 resin components constituting the second ionizing radiation curable resin.

[0087] The acrylate is preferably a difunctional or higher acrylate, more preferably a trifunctional or higher acrylate. In order to obtain a surface protective layer 5 having excellent scratch resistance, the acrylate is preferably a trifunctional or higher acrylate. There is no upper limit to the number of functional groups of the acrylate, but according to one example, it is hexafunctional or lower.

[0088] 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.

[0089] The number of repetitions of the repeating structure is preferably 3 or more. If an acrylate with a large number of repetitions is used, the cured film is more likely to expand in the in-plane direction during the second irradiation step described below, and therefore wrinkles corresponding to the ridge portions 5B are more likely to appear on the coating film surface. However, if the number of repetitions is increased, the crosslinking density decreases, and the scratch resistance of the surface protective layer decreases. Therefore, the number of repetitions is preferably 30 or less, and more preferably 20 or less.

[0090] 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.

[0091] When the second ionizing radiation curable resin contains an acrylate, it may further contain a methacrylate. For example, the second ionizing radiation curable resin may be a second mixture of an acrylate and a methacrylate, in which the proportion of the number of moles of methacryloyl groups in the total number of moles of acryloyl groups and the number of moles of methacryloyl groups is smaller than that in the first mixture. The proportion in the second mixture is preferably 90% or less, and more preferably 80% or less, of the proportion in the first mixture.

[0092] The surface protective layer 5 may further contain particles in addition to the cured resin. Examples of the particles contained in the surface protective layer 5 include particles made of an organic material such as polyethylene (PE) wax, polypropylene (PP) wax, and resin beads, and particles made of an inorganic material such as silica, glass, alumina, titania, zirconia, calcium carbonate, and barium sulfate.

[0093] The average particle size (D50) of the particles is preferably 10 μm or less, more preferably 1 μm to 8 μm, even more preferably 2 μm to 7 μm, and most preferably 3 μm to 6 μm. Increasing the average particle size (D50) of the particles can lead to particles easily falling off the surface protective layer 5, making it difficult to achieve high scratch resistance. Small particles reduce the effect of uniformly forming wrinkles. Here, "average particle size" or "average particle size (D50)" refers to the median diameter (D50) measured using a laser diffraction / scattering particle size distribution analyzer. If the surface protective layer coating liquid 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 surface protective layer and averaging the particle sizes of multiple particles. The value obtained in this manner is substantially the same as the median diameter (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 size of the particles contained in the second gloss control layer.

[0094] The amount of particles in the surface protective layer 5 is preferably in the range of 0.5 parts by mass or more and 10 parts by mass or less, more preferably in the range of 2 parts by mass or more and 8 parts by mass or less, and even more preferably in the range of 2 parts by mass or more and 6 parts by mass or less, relative to 100 parts by mass of the cured resin.

[0095] When the amount of particles added is within the above range, the effect of generating wrinkles uniformly is particularly large. If the amount of particles added is too large, the particles are likely to fall off from the surface protective layer 5, which may make it difficult to achieve high scratch resistance.

[0096] <2> Manufacturing Method of Decorative Sheet The decorative sheet 1 is manufactured, for example, by the following method. First, a pigment-containing layer 3 containing a pigment and a binder resin is formed on one side of a raw fabric layer 2 containing paper. The pigment-containing layer 3 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.

[0097] Next, a first coating film containing only the first ionizing radiation curable resin as the resin is formed on the pigment-containing layer 3. According to one example, a first coating film consisting essentially of the first ionizing radiation curable resin is formed on the pigment-containing layer 3. Here, the first coating film is formed so as to cover the entire upper surface of the pigment-containing layer 3.

[0098] Here, "the first coating film consists essentially of a first ionizing radiation curable resin" means that the first coating film consists solely of the first ionizing radiation curable resin, or consists solely of a mixture of the first ionizing radiation curable resin and an additive dissolved therein. Also, "the first coating film consists essentially of a first ionizing radiation curable resin and a filler" means that the first coating film consists solely of a mixture of the first ionizing radiation and a filler, or consists solely of a mixture of the first ionizing radiation curable resin and an additive and a filler dissolved therein.

[0099] The first coating film is formed by applying a coating liquid for a primer layer to the pigment-containing layer 3. The first 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.

[0100] The primer layer coating liquid contains the first ionizing radiation curable resin described above. As described above, the first ionizing radiation curable resin is a first mixture of acrylate and methacrylate.

[0101] The primer layer coating liquid may further contain the filler described above. The primer layer coating liquid may further contain other components, such as a solvent, and additives for improving the functionality of the final product, such as one or more antibacterial agents and antifungal agents. The primer layer coating liquid 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. When the primer layer coating liquid contains a solvent, the first coating film described above is obtained by applying the primer layer coating liquid and drying the resulting coating film.

[0102] When the first coating film is completely cured by ultraviolet light irradiation in the third irradiation step described below, the primer layer coating liquid preferably 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.

[0103] Next, a first irradiation step is carried out. In the first irradiation step, the first coating film is irradiated with a first radiation to semi-cure the first coating film. Here, "semi-cure" refers to a state in which the coating film has become solid but still contains a sufficient amount of C═C bonds derived from the acryloyl groups and methacryloyl groups.

[0104] The first radiation is, for example, ionizing radiation. As described above, the ionizing radiation is a charged particle beam such as an electron beam. The first radiation may be ultraviolet light, for which the first ionizing radiation curable resin exhibits a small absorption coefficient. The wavelength of the ultraviolet light irradiated onto the first coating film is preferably greater than 200 nm, more preferably in the range of 230 nm to 450 nm, and even more preferably in the range of 250 nm to 400 nm.

[0105] When the first coating film is irradiated with ionizing radiation or ultraviolet light, the curing of the first coating film can proceed substantially uniformly throughout the entire thickness of the first coating film. Therefore, unlike the second coating film described below, the first coating film after semi-curing does not have an irregular surface.

[0106] The first coating film is irradiated with the first radiation so that the unreacted rate of the first coating film, i.e., the ratio of the number of C═C bonds after irradiation with the first radiation to the number of C═C bonds before irradiation with the first radiation, is preferably in the range of 5% or more and 80% or less, more preferably in the range of 10% or more and 60% or less, and even more preferably in the range of 15% or more and 50% or less.

[0107] The first coating film is irradiated with the first radiation so that the cumulative light amount is within a range of 3% to 30% of the minimum cumulative light amount required to completely cure the first coating film, more preferably within a range of 5% to 25%, and even more preferably within a range of 8% to 20%.

[0108] The minimum integrated amount of light required to completely cure the first coating film is, for example, 10 mJ / cm ２ More than 1000mJ / cm ２ It is within the following range:

[0109] The first coating film is irradiated with the first radiation so that the absorbed dose is preferably in the range of 0.2% or more and 50% or less, more preferably in the range of 0.5% or more and 40% or less, and even more preferably in the range of 1% or more and 30% or less, of the minimum absorbed dose required to completely cure the first coating film.

[0110] The minimum absorbed dose required to completely cure the first coating film is, for example, in the range of 5 kGy to 200 kGy.

[0111] As described above, the first ionizing radiation curable resin further contains methacrylate in addition to acrylate. The methacrylate slows down the rate of the crosslinking reaction caused by exposure to the first radiation, thereby widening the process window in which the desired cured state can be achieved.

[0112] Next, a second coating film made of the coating liquid for forming a surface protective layer is formed on the semi-cured first coating film. Here, the second coating film is formed so as to cover the entire upper surface of the first coating film.

[0113] The second 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.

[0114] The coating liquid for the surface protective layer contains the second ionizing radiation curable resin described above. As described above, the second ionizing radiation curable resin is, in one example, an acrylate. In another example, the second ionizing radiation curable resin is a second mixture of an acrylate and a methacrylate, in which the ratio of the number of moles of methacryloyl groups to the total number of moles of acryloyl groups and the number of moles of methacryloyl groups is smaller than that of the first mixture.

[0115] The coating liquid for the surface protective layer may further contain other components, such as the above-mentioned particles, solvent, and additives for improving the functionality of the final product, such as one or more antibacterial agents and antifungal agents. The coating liquid for the surface protective layer may further contain other additives such as an ultraviolet absorber and a light stabilizer. Examples of the ultraviolet absorber that can be used include benzotriazole-based, benzoate-based, benzophenone-based, and triazine-based stabilizers. Examples of the light stabilizer that can be used include hindered amine-based stabilizers.

[0116] Next, the first coating film and the second coating film are irradiated with ionizing radiation or ultraviolet light to completely cure the first coating film and the second coating film. For example, the second irradiation step and the third irradiation step described below are carried out sequentially.

[0117] In the second step, the second coating film is irradiated with a second radiation, which is light having a wavelength of 200 nm or less.

[0118] The second ionizing radiation-curable resin contained in the coating liquid for the surface protective layer has a large absorption coefficient for the second radiation. Therefore, the second radiation incident on the second coating film can only reach a position several tens to several hundreds of nanometers away from the outermost surface. Therefore, in the second irradiation step, the crosslinking reaction proceeds in the surface region of the second coating film, forming an extremely thin cured film, while the crosslinking reaction does not proceed in other regions, leaving the other regions uncured.

[0119] The second coating film after the second irradiation step has wrinkles on its surface corresponding to the ridge portions 5 B. The inventors believe that the reason why wrinkles are formed on the coating film surface by the second irradiation step is as follows.

[0120] As described above, the second radiation can only reach a position tens to hundreds of nanometers away from the outermost surface of the second coating film. That is, the crosslinking reaction of the second ionizing radiation-curable resin occurs only on the surface of the second 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 causes the cured film to buckle, resulting in wrinkles on the surface of the second coating film.

[0121] The second radiation does not reach the portion of the first coating film that is covered with the second coating film, and therefore, no crosslinking reaction occurs in this portion due to irradiation with the second radiation.

[0122] The second 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 that excimer.

[0123] 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).

[0124] 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.

[0125] The second 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 second irradiation step is preferably carried out in, for example, a nitrogen gas atmosphere. The oxygen concentration in the gas phase in the second 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.

[0126] Furthermore, oxygen in the atmosphere inhibits radical polymerization. Therefore, the residual oxygen concentration in the reaction atmosphere affects the formation of wrinkles on the surface of the second coating film. Therefore, changing the residual oxygen concentration in the reaction atmosphere can also change the surface properties of the surface protective layer 5.

[0127] The cumulative amount of the second radiation is 0.5 mJ / cm ２ More than 200mJ / cm ２ It is preferable to set the concentration within the range of 1 mJ / cm ２ More than 100mJ / cm ２ It is more preferable to set it within the range of 3 mJ / cm ２ More than 50mJ / cm ２ It is more preferable to set it within the range of 5 mJ / cm ２ 30mJ / cm or more ２ It is most preferable to set the integrated light dose within the following range: If the integrated light dose is small, the expansion of the cured film in the in-plane direction will be small, whereas if the integrated light dose is large, the surface condition of the second coating film will deteriorate.

[0128] In the third irradiation step, the second coating film is irradiated with third radiation. The third radiation is ionizing radiation or ultraviolet light having a longer wavelength than the light irradiated in the second irradiation step. The third radiation can be any of the radiations described above for the first radiation.

[0129] In the third irradiation step, a crosslinking reaction proceeds throughout the entire thickness of each of the first and second coating films. Because the first coating film is in a semi-cured state at the start of the third irradiation step, crosslinking reactions can also occur between molecules contained in the first coating film and molecules contained in the second coating film at the contact points between the first and second coating films. Therefore, high adhesion can be achieved between the primer layer 4 and the surface protective layer 5.

[0130] The cumulative light amount of the third radiation is 10 mJ / cm ２ More than 500mJ / cm ２ It is preferable to set the dose within the range of 50 mJ / cm ２ More than 400mJ / cm ２ It is more preferable to set it within the range of 100 mJ / cm ２ More than 300mJ / cm ２ It is more preferable to set it within the following range.

[0131] The irradiation of the third radiation is preferably carried out so that the absorbed dose is in the range of 5 kGy or more and 200 kGy or less, more preferably in the range of 10 kGy or more and 150 kGy or less, and even more preferably in the range of 15 kGy or more and 100 kGy or less.

[0132] In the third irradiation step, if a layer having sufficient strength cannot be obtained by irradiation with only one type of radiation, the type of third radiation may be changed. For example, irradiation with ionizing radiation may be performed first, followed by irradiation with ultraviolet light having a longer wavelength than the light irradiated in the second irradiation step. Alternatively, irradiation with ultraviolet light having a longer wavelength than the light irradiated in the second irradiation step may be performed first, followed by irradiation with ionizing radiation. Alternatively, irradiation with ultraviolet light having a longer wavelength than the light irradiated in the second irradiation step may be performed first, followed by irradiation with ultraviolet light having an even longer wavelength.

[0133] In this manner, a decorative sheet 1 is obtained. In the decorative sheet 1 obtained by the above method, there is no interface between the core portion 5A and the rib portion 5B, and they are integrally formed.

[0134] <3> Effects The above-described configuration of the decorative sheet 1 makes it possible to prevent stains or traces thereof caused by water absorption, as will be explained below.

[0135] As described above, the pigment-containing layer 3 has a large total interface area between the pigment and the binder resin. Furthermore, when forming the pigment-containing layer 3, a binder resin with high polarity and a low degree of cross-linking is used, which produces a cured product. Therefore, the pigment-containing layer 3 has high water permeability. Therefore, when water adhering to the surface protective layer 5 reaches the pigment-containing layer 3, this water passes through the pigment-containing layer 3 and is absorbed by the paper contained in the raw fabric layer 2. This water-absorbed area can be seen as a stain. Furthermore, because the paper shrinks during the drying process in the water-absorbed area, traces of water absorption can be seen even after drying.

[0136] The surface protective layer 5 can impart a certain degree of water resistance to the decorative sheet 1. However, as described above, the surface protective layer 5 has an uneven structure on its surface, and therefore its thickness is non-uniform. Therefore, in order to achieve high water resistance with the surface protective layer 5 alone, its minimum thickness must be sufficiently large. However, since the thickness of the second coating film can affect the surface properties of the surface protective layer 5, the thickness of the surface protective layer 5 cannot be determined by considering only water resistance.

[0137] As described above, the resin contained in the primer layer 4 is a cured product of an ionizing radiation-curable resin, and therefore has a higher degree of crosslinking than the cured resin contained in the pigment-containing layer 3. The primer layer 4 does not have any interfaces inside, or even if it does have interfaces inside, the total area of ​​these interfaces is small. Therefore, the primer layer 4 greatly contributes to improving water resistance. Furthermore, the primer layer 4 does not participate in the formation of a concave-convex structure.

[0138] Therefore, by combining the primer layer 4, which is essentially made of a cured product of an ionizing radiation curable resin, with the above-mentioned surface protective layer 5, high water resistance can be achieved, and therefore stains or traces thereof caused by water absorption by the paper can be prevented from occurring.

[0139] Furthermore, in the decorative sheet 1, the primer layer 4 contains a cured product of a first ionizing radiation curable resin, which is a first mixture of acrylate and methacrylate. The acrylate contributes to improving scratch resistance, and the methacrylate contributes to improving adhesion between the primer layer 4 and the surface protective layer 5. Therefore, the decorative sheet 1 has excellent scratch resistance and adhesion between the gloss-adjusting layers.

[0140] Furthermore, the decorative sheet 1 has a surface protective layer provided with a concave-convex structure. This concave-convex structure preferably has a ratio RSm / Ra of the average length RSm of the roughness curve elements to the arithmetic mean roughness Ra within the above range. Such a concave-convex structure makes it possible to achieve a low gloss level.

[0141] Furthermore, the uneven structure including the ridge portions 5B formed on the upper surface of the surface protective layer 5 by the above-described method is finer than an uneven structure formed by mechanical processing such as embossing. Because the decorative sheet 1 has such a fine uneven structure on the upper surface of the surface protective layer 5, it has a matte finish and excellent fingerprint resistance.

[0142] Examples of the present invention will be described below. Note that the "particle size" described below is the above-mentioned "average particle size (D50)".

[0143] <Example 1> The decorative sheet 1 described with reference to Figs. 1 to 4 was produced by the following method. ２ An impregnated paper (GFR-506, manufactured by Kojin Co., Ltd.) was prepared as the raw paper layer 2. A pigment-containing layer 3 was formed on one surface of the raw paper layer 2 using a water-based ink (manufactured by Toyo Ink Co., Ltd.). The pigment contained in the ink used here had an average particle size of 500 nm.

[0144] Next, a primer layer coating liquid having the following composition was applied onto the pigment-containing layer 3. The primer layer coating liquid was applied so that the thickness of the primer layer 4 would be 5 μm.

[0145] (Primer layer coating liquid) Ionizing radiation curable resin R1 Type: Trimethylolpropane EO modified triacrylate (EO 3 moles added) Product name: Miramer M3130 (manufactured by Miwon Co., Ltd.) Blend: 50 parts by mass Ionizing radiation curable resin R2 Type: Methoxypolyethylene glycol (400) methacrylate Product name: NK Ester M-90G (manufactured by Shin-Nakamura Chemical Co., Ltd.) Blend: 50 parts by mass

[0146] Thereafter, a first irradiation step was carried out. Specifically, the first coating film made of the primer layer coating liquid was irradiated with an electron beam as ionizing radiation so that the absorbed dose of the first coating film was 10 kGy. This resulted in semi-curing of the first coating film.

[0147] Subsequently, a coating liquid for forming a surface protective layer having the following composition was printed on the first coating film: The coating liquid for forming a surface protective layer was printed so that the thickness of the surface protective layer 5 would be 5 μm.

[0148] (Coating liquid for surface protective layer) Ionizing radiation curable resin Type: Trimethylolpropane EO modified triacrylate (EO 6 moles added) Product name: Miramer M3160 (manufactured by Miwon) Blending amount: 100 parts by mass Particles Product name: Sylysia 250N (manufactured by Fuji Silysia Chemical Ltd.) Particle size: 5 μm Blending amount: 0.5 parts by mass

[0149] Next, a second irradiation step was carried out. Specifically, ultraviolet light having a wavelength of 172 nm was irradiated onto the surface of the second coating film made of the coating liquid for surface protective layer using a Xe excimer lamp in a nitrogen gas atmosphere with an oxygen concentration of 500 ppm under atmospheric pressure, with an integrated light intensity of 50 mJ / cm. ２ This caused wrinkles to form on the surface of the second coating film.

[0150] Subsequently, the third irradiation step was carried out. Specifically, the first and second coating films were irradiated with 100 kGy of ionizing radiation, and the entirety of the films was completely cured, thereby forming the primer layer 4 and the surface protective layer 5. In this manner, the decorative sheet 1 was obtained.

[0151] <Example 2> The decorative sheet 1 described with reference to Figures 1 to 4 was produced in the same manner as in Example 1, except that the blending amount of ionizing radiation curable resin R1 in the primer layer coating liquid was 80 parts by mass and the blending amount of ionizing radiation curable resin R2 was 20 parts by mass.

[0152] <Example 3> The decorative sheet 1 described with reference to Figures 1 to 4 was produced in the same manner as in Example 1, except that the blending amount of ionizing radiation curable resin R1 in the primer layer coating liquid was 90 parts by mass and the blending amount of ionizing radiation curable resin R2 was 10 parts by mass.

[0153] <Example 4> The decorative sheet 1 described with reference to Figures 1 to 4 was produced in the same manner as in Example 1, except that the following resin was used as the ionizing radiation curable resin R2, and the blending amount of ionizing radiation curable resin R1 in the primer layer coating liquid was 90 parts by mass and the blending amount of ionizing radiation curable resin R2 was 10 parts by mass. Ionizing radiation curable resin R2 Type: isobornyl methacrylate Product name: Light Ester IB-X (manufactured by Kyoeisha Chemical Co., Ltd.)

[0154] <Example 5> The decorative sheet 1 described with reference to Figures 1 to 4 was produced in the same manner as in Example 1, except that the following resin was used as the ionizing radiation curable resin R2. Ionizing radiation curable resin R2 Type: EO-modified bisphenol A dimethacrylate (EO 10 moles added) Product name: NK Ester BPE-500 (manufactured by Shin-Nakamura Chemical Co., Ltd.)

[0155] <Example 6> The decorative sheet 1 described with reference to Figures 1 to 4 was produced in the same manner as in Example 1, except that the following resin was used as the ionizing radiation curable resin R2, and the blending amount of ionizing radiation curable resin R1 in the primer layer coating liquid was 80 parts by mass and the blending amount of ionizing radiation curable resin R2 was 20 parts by mass. Ionizing radiation curable resin R2 Type: EO-modified bisphenol A dimethacrylate (EO 10 moles added) Product name: NK Ester BPE-500 (manufactured by Shin-Nakamura Chemical Co., Ltd.)

[0156] <Example 7> The decorative sheet 1 described with reference to Figures 1 to 4 was produced in the same manner as in Example 1, except that the following resin was used as the ionizing radiation curable resin R2, and the blending amount of ionizing radiation curable resin R1 in the primer layer coating liquid was 90 parts by mass and the blending amount of ionizing radiation curable resin R2 was 10 parts by mass. Ionizing radiation curable resin R2 Type: EO-modified bisphenol A dimethacrylate (EO 10 moles added) Product name: NK Ester BPE-500 (manufactured by Shin-Nakamura Chemical Co., Ltd.)

[0157] <Example 8> The decorative sheet 1 described with reference to Figures 1 to 4 was produced in the same manner as in Example 1, except that the following resin was used as the ionizing radiation curable resin R2, and the blending amount of ionizing radiation curable resin R1 in the primer layer coating liquid was 80 parts by mass and the blending amount of ionizing radiation curable resin R2 was 20 parts by mass. Ionizing radiation curable resin R2 Type: polyethylene glycol (200) dimethacrylate Product name: NK Ester 4G (manufactured by Shin-Nakamura Chemical Co., Ltd.)

[0158] <Example 9> The decorative sheet 1 described with reference to Figures 1 to 4 was produced in the same manner as in Example 1, except that the following resin was used as the ionizing radiation curable resin R2. Ionizing radiation curable resin R2 Type: Trimethylolpropane EO-modified trimethacrylate (3 EO moles added) Product name: NK Ester TMPT-3EO (manufactured by Shin-Nakamura Chemical Co., Ltd.)

[0159] <Example 10> The decorative sheet 1 described with reference to Figures 1 to 4 was produced in the same manner as in Example 1, except that the following resin was used as the ionizing radiation curable resin R2. Ionizing radiation curable resin R2 Type: Trimethylolpropane PO-modified trimethacrylate (3 moles of PO added) Product name: NK Ester TMPT-3PO (manufactured by Shin-Nakamura Chemical Co., Ltd.)

[0160] <Example 11> The decorative sheet 1 described with reference to Figures 1 to 4 was produced by the same method as in Example 1, except for the following points. That is, in this example, the following resin was used as the ionizing radiation curable resin in the coating liquid for the surface protective layer. - Ionizing radiation curable resin Type: Trimethylolpropane EO-modified triacrylate (3 EO moles added) Product name: Miramer M3130 (manufactured by Miwon Co., Ltd.) Then, in the second irradiation step, ultraviolet light having a wavelength of 172 nm was irradiated to the surface of the second coating film consisting of the first coating film and the coating liquid for the surface protective layer at an integrated light intensity of 100 mJ / cm using a Xe excimer lamp under atmospheric pressure in a nitrogen gas atmosphere with an oxygen concentration of 200 ppm. ２ The irradiation was carried out so that

[0161] <Example 12> Decorative sheet 1 described with reference to Figures 1 to 4 was produced in the same manner as in Example 1, except that the following resin was used as the ionizing radiation curable resin in the coating liquid for the surface protective layer: Ionizing radiation curable resin Type: Trimethylolpropane EO-modified triacrylate (15 mols of EO added) Product name: SR9035 (manufactured by Sartomer)

[0162] <Example 13> The decorative sheet 1 described with reference to Figures 1 to 4 was produced in the same manner as in Example 1, except that the following resin was used as the ionizing radiation curable resin in the coating liquid for the surface protective layer: Ionizing radiation curable resin Type: ethylene glycol diacrylate (9 moles of EO added) Product name: Light Acrylate 9EG-A (manufactured by Kyoeisha Chemical Co., Ltd.)

[0163] <Example 14> The decorative sheet 1 described with reference to Figures 1 to 4 was produced by the same method as in Example 1, except for the following points. That is, in this example, the following resin was used as the ionizing radiation curable resin in the coating liquid for the surface protective layer. - Ionizing radiation curable resin Type: Ethoxylated pentaerythritol tetraacrylate (35 moles of EO added) Product name: NK Ester ATM-35E (manufactured by Shin-Nakamura Chemical Co., Ltd.) Then, in the second irradiation step, ultraviolet light having a wavelength of 172 nm was irradiated to the surface of the second coating film consisting of the coating liquid for the surface protective layer at an integrated light intensity of 50 mJ / cm using a Xe excimer lamp under atmospheric pressure in a nitrogen gas atmosphere with an oxygen concentration of 200 ppm. ２ The irradiation was carried out so that

[0164] <Example 15> The decorative sheet 1 described with reference to Figures 1 to 4 was produced by the same method as in Example 1, except for the following points. That is, in this example, the following resin was used as the ionizing radiation curable resin in the coating liquid for the surface protective layer. - Ionizing radiation curable resin Type: Ethoxylated dipentaerythritol hexaacrylate (12 moles of EO added) Product name: NK Ester A-DPH-12E (manufactured by Shin-Nakamura Chemical Co., Ltd.) Then, in the second irradiation step, ultraviolet light having a wavelength of 172 nm was irradiated to the surface of the second coating film consisting of the first coating film and the coating liquid for the surface protective layer at an integrated light intensity of 150 mJ / cm using a Xe excimer lamp under atmospheric pressure in a nitrogen gas atmosphere with an oxygen concentration of 100 ppm. ２ The irradiation was carried out so that

[0165] <Example 16> The decorative sheet 1 described with reference to Figures 1 to 4 was produced in the same manner as in Example 1, except that the coating liquid for the surface protective layer was printed so that the thickness of the surface protective layer 5 was 2 µm.

[0166] <Example 17> The decorative sheet 1 described with reference to Figures 1 to 4 was produced in the same manner as in Example 1, except that the coating liquid for the surface protective layer was printed so that the thickness of the surface protective layer 5 was 20 µm.

[0167] 1 to 4 was produced in the same manner as in Example 1, except for the following points. That is, in this example, particles were omitted from the coating liquid for the surface protective layer. The coating liquid for the surface protective layer was printed so that the thickness of the surface protective layer 5 was 3 μm.

[0168] Example 19 The decorative sheet 1 described with reference to FIGS. 1 to 4 was produced in the same manner as in Example 1, except that the blending amount of particles in the coating liquid for the surface protective layer was set to 10 parts by mass.

[0169] <Example 20> Decorative sheet 1 described with reference to Figures 1 to 4 was produced in the same manner as in Example 1, except that the following particles were added to the primer layer coating liquid: Particles Product name: Sylysia 250N (manufactured by Fuji Silysia Chemical Ltd.) Particle size: 5 μm Blend: 5 parts by mass

[0170] 1 to 4 was produced by the same method as in Example 1, except for the following points. That is, in this example, the following resins were used as the ionizing radiation curable resin in the coating liquid for the surface protective layer. Ionizing radiation curable resin R3 Type: Trimethylolpropane EO-modified triacrylate (6 EO moles added) Product name: Miramer M3160 (manufactured by Miwon) Blend: 60 parts by mass Ionizing radiation curable resin R4 Type: Dipentaerythritol hexaacrylate Blend: 40 parts by mass Particles Product name: Sylysia 250N (manufactured by Fuji Silysia Chemical Ltd.) Particle size: 5 μm Blend: 0.5 parts by mass

[0171] 1 to 4 was produced in the same manner as in Example 21, except for the following: In this example, the amounts of ionizing radiation curable resins R3 and R4 in the coating liquid for the surface protective layer were 40 parts by mass and 60 parts by mass, respectively.

[0172] Comparative Example 1 A decorative sheet similar to that described with reference to FIGS. 1 to 4 was produced in the same manner as in Example 1, except that the second irradiation step was omitted.

[0173] Comparative Example 2 A decorative sheet similar to that described with reference to FIGS. 1 to 4 was produced in the same manner as in Example 1, except that the ionizing radiation curable resin R2 was omitted from the primer layer coating liquid.

[0174] Comparative Example 3 A decorative sheet similar to that described with reference to FIGS. 1 to 4 was produced in the same manner as in Example 1, except that the ionizing radiation curable resin R1 was omitted from the primer layer coating liquid.

[0175] Comparative Example 4 A decorative sheet similar to that described with reference to FIGS. 1 to 4 was produced in the same manner as in Example 1, except that the primer layer 4 was not formed.

[0176] <Evaluation> Each of the decorative sheets described above was evaluated as follows: Those rated "AAA", "AA" or "A" were deemed to pass, as they presented no problems in actual use.

[0177] (1) Thickness of the Surface Protective Layer The thickness of the surface protective layer was measured using the same method as described above. Specifically, the decorative sheet was embedded in a resin such as a cold-setting epoxy resin or a UV-curable resin, and the resin was allowed to fully harden. Next, the decorative sheet was cut so that the cross section of the decorative sheet was exposed, and the measurement surface was obtained by mechanically polishing it.

[0178] Subsequently, a 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 2000. No sputtering was performed on the measurement sample.

[0179] Next, from this cross-sectional image, the dimension of the surface protective layer in the width direction of the ridge-like 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. The thickness thus obtained was equal to the thickness of the coating film made of the surface protective layer coating liquid. The thickness of the primer layer was also measured by the same method as above.

[0180] (2) Gloss The gloss was measured as a specular gloss GS(60°) using a Rhopoint IQ-S (manufactured by Rhopoint Instruments). The "60° gloss value" in Tables 1 to 4 below represents this specular gloss GS(60°).

[0181] (3) Adhesion The adhesion of the surface protective layer to the primer layer was evaluated by a cross-cut test specified in JIS K5400 (discontinued). Here, cuts were formed in a grid pattern at 1 mm intervals on the surface of the decorative sheet, with the depth exceeding the interface between the primer layer and the surface protective layer. This resulted in 100 squares arranged in a grid pattern. Next, adhesive tape was applied to the surface of the decorative sheet, and the adhesive tape was subsequently peeled off from the decorative sheet. The number of squares remaining on the decorative sheet was then counted, and this number was used to evaluate adhesion based on the following criteria:

[0182] AAA: The number of remaining squares was 100. AA: The number of remaining squares was within the range of 95 to 99. A: The number of remaining squares was within the range of 90 to 94. B: The number of remaining squares was 89 or less.

[0183] (4) Scratch Resistance Each decorative sheet was attached to wood substrate B using a urethane adhesive. A steel wool rubbing test was then conducted to evaluate scratch resistance. Specifically, the decorative sheet was rubbed back and forth 20 times with steel wool while applying a load of 100 g, and the occurrence of scratches on the surface of the decorative sheet and any changes in gloss were visually confirmed.

[0184] The evaluation criteria were as follows: AAA: No scratches or changes in gloss occurred on the surface. AA: Minor scratches or changes in gloss occurred on a part of the surface. A: Minor scratches or changes in gloss occurred on the surface. B: Significant scratches or changes in gloss occurred on the surface.

[0185] (5) Water Resistance Each decorative sheet was attached to wood substrate B using a urethane adhesive. Water was dropped onto the surface protective layer of each decorative sheet, and the sheet was covered with a watch glass and left for 24 hours. After that, the water was wiped off the surface protective layer, and the decorative sheet was observed.

[0186] The evaluation criteria were as follows: AAA: No stains or traces of water absorption were found. AA: Traces of stains or water absorption were found in some areas, but they were difficult to confirm. A: Traces of stains or water absorption were found in some areas, but they were relatively easy to confirm. B: Traces of water absorption were clearly found throughout the entire surface.

[0187] The evaluation results are shown in Tables 1 to 5. In Tables 1 to 5, "proportion of moles of methacryloyl groups" represents the proportion of moles of methacryloyl groups to the total number of moles of acryloyl groups and methacryloyl groups.

[0188]

[0189]

[0190]

[0191]

[0192]

[0193] As shown in Tables 1 to 5, the decorative sheets according to Examples 1 to 22 exhibited sufficient performance in all of adhesion, scratch resistance, and water resistance. In contrast, the sheet according to Comparative Example 2 exhibited insufficient performance in all of adhesion, scratch resistance, and water resistance. Furthermore, the sheet according to Comparative Example 4 exhibited sufficient performance in adhesion and scratch resistance, but insufficient performance in water resistance. Furthermore, the sheets according to Comparative Examples 1 and 2 exhibited sufficient performance in adhesion and water resistance, but insufficient performance in scratch resistance.

[0194] 1...decorative sheet, 2...base layer, 3...pigment-containing layer, 4...primer layer, 5...surface protective layer, 5A...core portion, 5B...ridge portion, 11...decorative material, B...base material, C...position, D...position.

Claims

1. A decorative sheet comprising: an original fabric layer containing paper; a pigment-containing layer provided on the original fabric layer and containing a pigment and a binder resin; a primer layer provided on the pigment-containing layer; and a surface protective layer provided on the primer layer, wherein the primer layer contains only a cured product of a first ionizing radiation curable resin as a resin cured product, the first ionizing radiation curable resin being a first mixture of acrylate and methacrylate; and the surface protective layer contains only a cured product of a second ionizing radiation curable resin as a resin cured product, and the surface is provided with an uneven structure including a plurality of ridge-like portions each protruding in the form of a ridge.

2. The decorative sheet according to claim 1, wherein in said primer layer, the ratio of the number of moles of methacryloyl groups to the total number of moles of acryloyl groups and methacryloyl groups is within the range of 3% to 50%.

3. The decorative sheet according to claim 1 or 2, wherein the methacrylate is a monofunctional, difunctional or trifunctional methacrylate.

4. A decorative sheet according to any one of claims 1 to 3, wherein the mass of the filler in the primer layer is 10 parts by mass or less when the mass of the first ionizing radiation curable resin is 100 parts by mass.

5. A decorative sheet as described in any one of claims 1 to 4, wherein the second ionizing radiation curable resin is an acrylate or a second mixture of an acrylate and a methacrylate, and the second mixture has a smaller ratio of the number of moles of methacryloyl groups to the total number of moles of acryloyl groups and the number of moles of methacryloyl groups compared to the first mixture.

6. A decorative sheet according to any one of claims 1 to 5, wherein the second ionizing radiation curable resin contains a di- or higher functional acrylate having a repeating structure.

7. The decorative sheet according to claim 6, wherein the repeating structure is repeated three or more times.

8. A decorative sheet according to any one of claims 1 to 7, wherein the thickness of said primer layer is within the range of 0.5 µm to 10 µm.

9. The decorative sheet according to any one of claims 1 to 8, wherein the thickness of said surface protective layer is within the range of 2 μm to 20 μm.

10. The decorative sheet according to any one of claims 1 to 9, 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 mass of the particles is in the range of 0.5 parts by mass or more and 10 parts by mass, when the mass of the second ionizing radiation curable resin is taken as 100 parts by mass.

12. A decorative sheet according to any one of claims 1 to 11, wherein the uneven structure has a ratio RSm / Ra of the average length RSm of the roughness curve elements to the arithmetic mean roughness Ra in the range of 10 or more and 800 or less.

13. The decorative sheet according to any one of claims 1 to 12, wherein the surface protective layer has a specular gloss GS(60°) of 20 or less.

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

15. A method for manufacturing a decorative sheet comprising: forming a pigment-containing layer containing a pigment and a binder resin on a base layer containing paper; forming a first coating film on the pigment-containing layer, the first coating film containing only a first ionizing radiation curable resin as a resin, the first ionizing radiation curable resin being a first mixture of acrylate and methacrylate; performing a first irradiation step of irradiating the first coating film with ionizing radiation or ultraviolet light to semi-cure the first coating film; forming a second coating film on the semi-cured first coating film, the second coating film containing only a second ionizing radiation curable resin as a resin; and irradiating the first coating film and the second coating film with ionizing radiation or ultraviolet light to completely cure the first coating film and the second coating film.

16. A method for producing a decorative sheet as described in claim 15, wherein complete curing of the first coating film and the second coating film includes a second irradiation step of irradiating the second coating film with light having a wavelength of 200 nm or less, and then a third irradiation step of irradiating the first coating film and the second coating film with ionizing radiation or ultraviolet light having a longer wavelength than the light irradiated in the second irradiation step.

17. A method for producing a decorative sheet as described in claim 15 or 16, wherein the first coating film is irradiated with ionizing radiation or ultraviolet light in the first irradiation step so that the ratio of the number of C=C bonds after irradiation to the number of C=C bonds before irradiation is within the range of 5% or more and 80% or less.

18. A method for manufacturing a decorative sheet described in any one of claims 15 to 17, wherein the first coating film is irradiated with ionizing radiation or ultraviolet light in the first irradiation step so that the accumulated light amount is within the range of 3% to 30% of the minimum accumulated light amount required to completely cure the first coating film.

19. A method for producing a decorative sheet described in any one of claims 15 to 18, wherein the first coating film is irradiated with ionizing radiation or ultraviolet light in the first irradiation step so that the absorbed dose is within the range of 0.2% or more and 50% or less of the minimum absorbed dose required to completely cure the first coating film.

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