Cosmetic sheet

Abstract

To provide a decorative sheet having low gloss due to a matte effect and excellent aesthetic appearance. [Solution] The decorative sheet 1 includes a substrate 2 and a surface layer 3 provided on the substrate 2. The surface layer 3 is composed of a continuous layer 4 made up of an ultraviolet-cured material layer 6 formed on the surface 2a of the substrate 2 and an excimer light-cured material layer 7 formed on the surface 6a of the ultraviolet-cured material layer 6, and a dispersion 5 dispersed in the continuous layer 4 and made up of at least one of organic particles and inorganic particles. In the surface layer 3, the content of the dispersion 5 is 20 parts by mass or more and 90 parts by mass or less per 100 parts by mass of the continuous layer, and the dispersion 5 contains cellulose nanofiber particles with an average particle diameter of less than 0.1 μm.

Description

[Technical field]

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

[0002] Decorative sheets are used to enhance design by providing surface decoration in various applications, such as wall materials, construction materials, building materials such as fittings, surface decoration of furniture, etc., automotive interiors, low-electricity electrical coverings, etc. Known decorative sheets include, for example, those having a layer with a low gloss (matte) effect provided on a substrate.

[0003] For example, a decorative sheet has been proposed that has a decorative layer containing a coloring material on a substrate, and a clear layer containing wet gel silica particles having an average particle size of 5 μm or less as measured by the Coulter Counter method (AP 50 μm) on the decorative layer. It is described that such a configuration can provide a decorative sheet that favorably maintains the color of the coloring layer and has a good matte surface even when it has a clear layer containing inorganic particles (see, for example, Patent Document 1).

[0004] Also, a decorative sheet has been proposed in which the surface of a coating film construction provided on a substrate is irradiated with excimer light from an excimer lamp, thereby reducing the gloss of the portion of the surface of the coating film construction irradiated with the electromagnetic waves compared to before the electromagnetic waves were irradiated. It is described that such a configuration can provide a decorative sheet having areas with different matte textures (see, for example, Patent Document 2). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2015-77691 A [Patent Document 2] JP 2018-164901 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, in the cosmetic sheet described in Patent Document 1 above, since it merely contains silica particles in the clear layer, a sufficient dulling effect cannot be obtained, and there is a problem that low glossiness is difficult to exhibit.

[0007] Further, in the cosmetic sheet described in Patent Document 2 above, since silica particles or the like are not contained in the clear layer and it merely irradiates excimer light, a sufficient dulling effect cannot be obtained, and furthermore, uneven irregularities are formed in the clear layer, resulting in a problem that the aesthetic appearance (design property) deteriorates.

[0008] Therefore, the present invention has been made in view of the above problems, and an object thereof is to provide a cosmetic sheet having low glossiness due to a dulling effect and excellent aesthetic appearance.

Means for Solving the Problems

[0009] In order to achieve the above object, the cosmetic sheet of the present invention includes a base material and a surface layer provided on the base material. The surface layer is composed of a continuous layer formed by an ultraviolet curable layer formed on the surface of the base material and an excimer light curable layer formed on the surface of the ultraviolet curable layer, and a dispersion composed of at least one of organic particles and inorganic particles dispersed in the continuous layer. In the surface layer, the content of the dispersion is 20 parts by mass or more and 90 parts by mass or less with respect to 100 parts by mass of the continuous layer, and the dispersion contains cellulose nanofiber particles having an average particle diameter of less than 0.1 μm.

Effects of the Invention

[0010] According to the present invention, it is possible to provide a cosmetic sheet having low glossiness and excellent aesthetic appearance in which uneven irregularities are uniformly formed over the entire surface of the surface layer.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Mode for Carrying Out the Invention

[0012] Hereinafter, the cosmetic sheet of the present invention will be specifically described. Note that the present invention is not limited to the following embodiments, and can be appropriately modified and applied without changing the gist of the present invention.

[0013] <Cosmetic sheet> As shown in FIG. 1, the cosmetic sheet 1 of the present invention includes a base material 2 and a surface layer 3 provided on the surface 2a of the base material 2.

[0014] <Base material> The base material 2 is made of, for example, a thermoplastic resin sheet, and as this thermoplastic resin sheet, those usually used for the base material in the cosmetic sheet 1 can be used. Specific examples include, for example, a polyvinyl chloride sheet, a glycol-modified polyethylene terephthalate (PETG) sheet, an amorphous crystalline polyester resin (APET) sheet, a polyolefin sheet (a polyethylene sheet, a polypropylene sheet, etc.), an acrylonitrile-butadiene-styrene resin (ABS) sheet, a polycarbonate sheet, and the like. Further, as the amorphous crystalline polyester resin (APET) sheet used for the base material 2, a recycled polyethylene terephthalate (RPET) sheet made from PET bottles or the like can be mentioned.

[0015] As for the thermoplastic resin sheet, from the viewpoint of being easy to perform secondary surface processing and having excellent three-dimensional formability, a glycol-modified polyethylene terephthalate sheet is preferable. The glycol-modified polyethylene terephthalate sheet is a kind of polyethylene terephthalate. While the glycol component of polyethylene terephthalate is ethylene glycol, it is an amorphous polyester containing, as the glycol component, in addition to ethylene glycol, a diol other than ethylene glycol (1,4-cyclohexanedimethanol).

[0016] Also, the thermoplastic resin sheet may be a stretched sheet or an unstretched sheet. Further, the thermoplastic resin sheet may contain additives such as a colorant, an ultraviolet absorber, a light stabilizer, an antioxidant, an antistatic agent, a storage stabilizer, a lubricant, and a filler, as necessary. Note that the thermoplastic resin sheet is preferably colored from the viewpoint of design.

[0017] The thickness of the base material 2 is not particularly limited, but is preferably 50 to 800 μm, and more preferably 250 to 500 μm. If the thickness of the base material 2 is 50 μm or more, the mechanical strength and the concealing property can be sufficiently improved. Further, if the thickness of the base material 2 is 800 μm or less, the three-dimensional formability is more excellent, and it becomes easier to ensure flexibility and printability.

[0018] <Surface layer> The surface layer 3 is composed of a continuous layer 4 which is a coating film of a paint mainly composed of urethane acrylate and monofunctional acrylate, and a dispersion 5 composed of at least one of organic particles and inorganic particles.

[0019] This surface layer 3 can be formed by applying a paint containing the dispersion 5 onto the surface 2a of the base material 2 and curing it. The surface layer 3 is formed by the continuous layer 4 which is a cured product of the paint and the dispersion 5 which are particles dispersed in the continuous layer 4.

[0020] Further, as shown in FIG. 1, the continuous layer 4 is composed of an ultraviolet curable layer 6 formed on the surface 2a of the base material 2 and an excimer light curable layer 7 formed on the surface 6a of the ultraviolet curable layer 6. The excimer light curable layer 7 is formed so as to cover the dispersion 5 on the surface 6a of the ultraviolet curable layer 6.

[0021] Further, as shown in FIG. 1, wrinkles are formed on the surface 3a of the surface layer 3 (that is, the surface on the side opposite to the base material 2 side), and unevenness starting from the dispersion 5 is formed.

[0022] As the urethane acrylate for forming the continuous layer 4, those having 2 to 10 functional groups are used. For example, phenylglycamidyl ether acrylate hexamethylene diisocyanate urethane prepolymer, pentaerythritol triacrylate hexamethylene diisocyanate urethane prepolymer, dipentaerythritol pentaacrylate hexamethylene diisocyanate urethane prepolymer, etc. can be mentioned. In addition, commercially available products such as EBECRYL8402, KRM8452, EBECRYL210, EBECRYL220, EBECRYL4500, EBECRYL230, EBECRLY270, EBECRYL4858, EBECRYL8804, EBECRYL8807, EBECRYL9270, EBECRYL4100, EBECRYL4513, EBECRYL8311, EBECRYL8465, EBECRYL9260, EBECRYL8701, KRM8667, EBECRYL4265, EBECRYL4587, EBECRYL4200, EBECRYL8210, EBECRYL1290, EBECRYL5129, EBECRYL5129, EBECRYL8254, EBECRYL8301R, KRM8200, KRM8904, RUA-062NS (product containing 2-functional acrylate monomer), U-6LPA, UA-1100H, U-200PA, UA-160TM, and UV-7600B (all are trade names) can be used. These urethane acrylates may be used alone or in combination of two or more.

[0023] In addition, examples of the monofunctional acrylate for forming the continuous layer 4 include ethyl carbitol acrylate, methoxyethylene glycol (meth)acrylate, methoxypolyethylene glycol (meth)acrylate, β-(meth)acryloyloxyethyl hydrogen phthalate, β-(meth)acryloyloxyethyl hydrogen succinate, nonylphenoxyethyl (meth)acrylate, 3-chloro-2-hydroxypropyl (meth)acrylate, phenoxyethyl (meth)acrylate, phenoxypolyethylene glycol (meth)acrylate, butoxypolyethylene glycol (meth)acrylate, alkyl (meth)acrylate, cyclohexyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, isobornyl (meth)acrylate, benzyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, 2-(meth)acryloyloxyethyl-2-hydroxyethyl phthalic acid, 3-acryloyloxyglycerin mono(meth)acrylate, 2-hydroxybutyl (meth)acrylate, 2-hydroxy-1-(meth)acryloxy-3-(meth)acryloxypropane, polypropylene glycol mono(meth)acrylate, polyethylene glycol mono(meth)acrylate, polyε-caprolactone mono(meth)acrylate, dialkylaminoethyl (meth)acrylate, glycidyl (meth)acrylate, mono[2-(meth)acryloyloxyethyl] acid phosphate, trifluoroethyl (meth)acrylate, 2,2,3,3-tetrafluoropropyl (meth)acrylate, 2,2,3,4,4,4-hexafluorobutyl (meth)acrylate, perfluorooctylethyl (meth)acrylate, dicyclopentenyl oxyalkyl (meth)acrylate, dicyclopentenyl (meth)acrylate, tricyclodecanyl (meth)acrylate, tricyclodecanyloxyethyl (meth)acrylate, and isobornyloxyethyl (meth)acrylate. These monofunctional acrylates may be used alone or in combination of two or more.

[0024] Also, the blending ratio of urethane acrylate and monofunctional acrylate in the continuous layer 4 is not particularly limited as long as the characteristics of the cosmetic sheet 1 of the present invention are not impaired. However, in terms of mass ratio, the range of urethane acrylate:monofunctional acrylate = 10:90 to 90:10 is preferable. This is because urethane acrylate has low fluidity. When the mass ratio of urethane acrylate increases, wrinkles are less likely to occur on the surface 3a of the surface layer 3, and it becomes difficult to exhibit the low gloss property due to the dulling effect. Also, since monofunctional acrylate has low reactivity, when the mass ratio of monofunctional acrylate increases, it becomes difficult for the paint to cure.

[0025] Also, the thickness of the continuous layer 4 (that is, the thickness of the portion in the continuous layer 4 where the dispersion 5 is not dispersed, which is the thickness T shown in FIG. 1) is not particularly limited, but is preferably 1 to 45 μm, and more preferably 1 to 10 μm. When the thickness of the continuous layer 4 is less than 1 μm, the movable coating film region during excimer irradiation decreases, so wrinkles are less likely to occur, and the low gloss property due to the dulling effect may be difficult to exhibit. Also, when the thickness of the continuous layer 4 is greater than 45 μm, the touch sensitivity further decreases and the hardness increases, so the molding processability may decrease. In addition, when the thickness of the continuous layer 4 is greater than 10 μm, the surface roughness Sa of the surface layer 3 increases, so the fingerprint resistance improves, but the touch sensitivity may decrease.

[0026] The dispersion 5 is for forming unevenness uniformly over the entire surface 3a of the surface layer 3 to improve the aesthetic appearance (design property) of the cosmetic sheet 1. That is, in the surface layer 3, unevenness is formed starting from the uniformly dispersed dispersion 5, so it becomes possible to form unevenness uniformly over the entire surface 3a of the surface layer 3.

[0027] Examples of the material of the organic particles constituting the dispersion 5 include acrylic copolymers, cellulose nanofiber particles, polystyrene, epoxy, polyester, polyamide, polyurethane, and melamine. Examples of the material of the inorganic particles constituting the dispersion 5 include glass, silica, alumina, zirconia, yttria, magnesia, and silicon nitride. From the viewpoint of achieving low gloss of the surface layer 3, it is preferable to use inorganic particles such as glass and silica. These materials may be used alone or in combination of two or more.

[0028] When particles having a substantially spherical shape are used as the dispersion 5, the average particle diameter R shown in FIG. 1 is preferably 0.1 μm or more and 10 μm or less. This is because when it is less than 0.1 μm, the particles may undergo secondary aggregation, resulting in a non-uniform dispersion state in the continuous layer and the formation of non-uniform irregularities. Also, when it is larger than 10 μm, particle detachment may occur.

[0029] Here, the "average particle diameter" refers to the 50% particle diameter (D50), which can be measured as the volume average particle diameter using a laser diffraction / scattering particle size distribution measuring device (manufactured by Nikkiso Co., Ltd., Microtrac (registered trademark) particle size distribution measuring device MT3200) or the like.

[0030] When cellulose nanofiber particles are used as the dispersion 5, even when the average particle diameter (BET average particle diameter) is less than 0.1 μm, due to the large aspect ratio of the particles, the particles do not undergo secondary aggregation due to physical obstacles, and a non-uniform dispersion state does not occur in the continuous layer, so uniform irregularities can be formed on the entire surface of the surface layer.

[0031] The BET average particle diameter of the cellulose nanofiber particles can be measured using the BET method. More specifically, the average particle diameter of the cellulose nanofiber particles refers to the specific surface area S (m 2 / g) measured by the BET method and the density of the cellulose nanofiber particles (g / cm 3It refers to the particle diameter calculated by the formula average particle diameter (nm) = 6000 / (S × density).

[0032] Further, by using cellulose nanofiber particles as the dispersion 5, during heat stretching, fine cracks starting from the cellulose nanofibers occur, and large cracks that affect the appearance are not formed. Therefore, a decorative sheet excellent in heat stretchability (that is, when the decorative sheet is heat stretched, linear cracks do not occur throughout the direction perpendicular to the heat stretching direction, and the appearance is excellent) can be obtained.

[0033] Also, it is preferable that the average particle diameter R of the dispersion 5 is 0.001 times or more and 4 times or less of the thickness T of the continuous layer 4, and more preferably 0.01 times or more and 4 times or less. This is because when it is less than 0.001 times, it may be difficult to form uniform irregularities by the dispersion 5. Also, when it is more than 4 times, the volume ratio of the dispersion 5 to the total volume of the continuous layer 4 becomes too large. Therefore, when applying the paint containing the dispersion 5 onto the surface 2a of the base material 2, there are restrictions on the formation of irregularities by the dispersion 5, and as a result, it may be difficult to form uniform irregularities by the dispersion 5.

[0034] Also, in the surface layer 3, when the continuous layer 3 is 100 parts by mass, it is preferable that the dispersion 5 is 10 parts by mass or more and 90 parts by mass or less. This is because when it is 10 parts by mass or less, the formation of irregularities is insufficient over the entire surface 3a of the surface layer 3, and there may be variations in the surface roughness Sa of the surface layer 3. Also, when it is more than 90 parts by mass, there is a disadvantage that the cost increases because the expensive dispersion 5 increases.

[0035] Also, the paint for forming the surface layer 3 may contain urethane acrylate, monofunctional acrylate, and other components other than the dispersion 5 as long as the effects of the invention are not impaired. Examples of other components include a photopolymerization initiator, a colorant, an ultraviolet absorber, a light stabilizer, an antioxidant, an antistatic agent, a storage stabilizer, a plasticizer, a lubricant, a filler, and the like.

[0036] As the photoinitiator, for example, initiators such as alkylphenone-based, acylphosphine oxide-based, and cationic-based initiators can be used.

[0037] <Manufacturing Method> When manufacturing the cosmetic sheet 1 of the present invention, first, for example, a base material 2 made of the above-mentioned thermoplastic resin sheet is prepared. This thermoplastic resin sheet may be a commercially available one, or one manufactured by a known manufacturing method such as a calender method or an extrusion molding method may be used.

[0038] Next, a paint added with urethane acrylate, monofunctional acrylate, photoinitiator, and dispersion 5 is applied onto the surface 2a of the base material 2 to form a coating film that becomes the surface layer 3 on the surface 2a of the base material 2.

[0039] In addition, for example, when using urethane acrylate containing a bifunctional acrylate monomer such as the above-mentioned RUA-062NS, the use of monofunctional acrylate can be omitted.

[0040] Also, the coating method of the paint is not particularly limited, and examples include a cast coating method, a die coating method, a gravure coating method, a roll knife coating method, a reverse roll coating method, a roll coating method, and a comma coating method.

[0041] Next, the coating film formed on the surface 2a of the base material 2 is irradiated with excimer light. More specifically, excimer light having a short peak wavelength (within the range of 120 to 230 nm) is irradiated onto the coating film. Then, curing occurs only on the outermost surface of the coating film that becomes the surface layer 3, and the above-mentioned excimer light-cured product layer 7 is formed, resulting in non-uniformity between the surface and the inside of the coating film, and the coating film components move from the unreacted portion inside the coating film to the surface, so wrinkles are formed on the surface of the coating film. As a result, it becomes possible to achieve the glossiness (low glossiness) in the surface layer 3.

[0042] When irradiating excimer light using an excimer lamp, the peak wavelength of the electromagnetic wave can be changed by changing the discharge gas filled in the excimer lamp. Examples of the discharge gas for irradiating excimer light with the above peak wavelength include Ar 2 , Kr 2 , Xe 2 etc. can be used.

[0043] Then, by irradiating ultraviolet rays (350 to 450 nm) to cure the coating film, an ultraviolet-cured product layer 6 is formed. A continuous layer 4 composed of the ultraviolet-cured product layer 6 formed on the surface 2a of the base material 2 and the excimer light-cured product layer 7 formed on the surface 6a of the ultraviolet-cured product layer 6, and a surface layer 3 composed of the dispersion 5 dispersed in the continuous layer 4 are formed. Due to the dispersion 5, unevenness is uniformly formed over the entire surface 3a. As a result, a decorative sheet 1 with improved aesthetics due to the uniformly formed unevenness is manufactured while maintaining the low gloss property by excimer irradiation.

[0044] Note that even if the coating film is irradiated again with excimer light having a short peak wavelength (within the range of 120 to 230 nm) instead of the above ultraviolet rays (350 to 450 nm), the coating film will not be completely cured.

[0045] Here, in the decorative sheet 1 of the present invention, as described above, since unevenness is uniformly formed over the entire surface 3a of the surface layer 3 by the dispersion 5, the standard deviation σ [μm] of the surface roughness Sa [μm] on the surface 3a of the surface layer 3 is 0.2 or less.

[0046] Note that the "surface roughness Sa" mentioned here refers to the "three-dimensional surface texture parameter (three-dimensional arithmetic mean roughness)" defined in ISO 25178.

[0047] Also, the "standard deviation σ of the surface roughness Sa" indicates the spread width (variation of the surface roughness Sa) of the surface roughness Sa, and this standard deviation σ can be obtained by the method described later.

[0048] In the cosmetic sheet 1 of the present invention, it is characterized in that the value obtained by dividing the standard deviation σ [μm] of the surface roughness Sa by the thickness T [μm] of the continuous layer 3 is 7% or less (that is, the following formula (1) holds).

[0049] [Equation 1] (Standard deviation σ [μm] of surface roughness Sa ÷ Thickness T [μm] of continuous layer 3) × 100 ≦ 7 [%] (1)

[0050] Therefore, as described above, it becomes possible to provide the cosmetic sheet 1 with excellent aesthetics, in which unevenness is uniformly formed over the entire surface 3a of the surface layer 3.

[0051] In addition, in the cosmetic sheet 1 of the present invention, due to the above-described dulling effect caused by wrinkles, the glossiness G on the surface 3a of the surface layer 3 becomes 13 or less, so that it is possible to achieve low glossiness.

[0052] Here, the "glossiness" mentioned here is an index of low luster, and refers to the 60° glossiness measured by a method conforming to JIS Z 8741:1997.

[0053] Further, from the viewpoint of further improving the low luster and enhancing the design property, the glossiness G is preferably 10 or less, and more preferably 8 or less.

[0054] As described above, in the cosmetic sheet 1 of the present invention, since the value obtained by dividing the standard deviation σ [μm] of the surface roughness Sa on the surface 3a of the surface layer 3 by the thickness T [μm] of the continuous layer 3 is 7% or less, it is possible to provide the cosmetic sheet 1 with excellent aesthetics, in which unevenness is uniformly formed over the entire surface 3a of the surface layer 3.

[0055] In addition, due to the above-described dulling effect caused by wrinkles, it becomes possible to provide the cosmetic sheet 1 having low glossiness.

Example

[0056] The present invention will be described below based on examples. Note that the present invention is not limited to these examples, and these examples can be modified and changed based on the gist of the present invention, and they are not excluded from the scope of the present invention.

[0057] The materials used for producing the cosmetic sheet are shown below. (1) Urethane acrylate - 1: 3 - functional urethane acrylate (manufactured by Asia Industrial Co., Ltd., trade name: RUA - 062NS, containing 2 - functional acrylate monomer) (2) Urethane acrylate - 2: 6 - functional urethane acrylate (manufactured by Mitsubishi Chemical Corporation, trade name: UV - 7600B) (3) Urethane acrylate - 3: 3 - 4 - functional urethane acrylate (manufactured by Daicel - Ornex Co., Ltd., trade name: EBECRYL4265) (4) Urethane acrylate - 4: 3 - functional urethane acrylate (manufactured by Daicel - Ornex Co., Ltd., trade name: EBECRYL9260) (5) Monofunctional acrylate: Tetrahydrofurfuryl acrylate (manufactured by Tokyo Chemical Industry Co., Ltd., trade name: Tetrahydrofurfuryl Acrylate) (6) Initiator: Alkylphenone - based photopolymerization initiator (manufactured by IGM Resins B.V., trade name: Omnirad1173) (7) Dispersion - 1: Low - alkali glass (manufactured by Potters & Barotti Co., trade name: EMB - 10, average particle diameter: 5μm) (8) Dispersion - 2: Low - alkali glass (manufactured by Potters & Barotti Co., trade name: EMB - 20, average particle diameter: 10μm) (9) Dispersion - 3: Acrylic copolymer fine particles (manufactured by Dainichi Seika Kogyo Co., Ltd., trade name: 030(10MD) Clear, average particle diameter: 9μm) (10) Dispersion - 4: Silica fine particles (manufactured by Denka Co., Ltd., trade name: UFP30, average particle diameter: 0.1μm) (11) Dispersion - 5: Cellulose nanofiber particles (manufactured by Mori Machinery Co., trade name: C - 100(IPA), IPA - dispersed cellulose nanofiber, solid content 5%, average particle diameter: 0.027μm) (12) Dispersion - 6: Cellulose nanofiber particles (manufactured by Sugino Machine, product name: Ima - 10002, water - dispersed cellulose nanofibers replaced with acetone, solid content 2%, average particle diameter: 0.01 - 0.05 μm) (13) Dispersion - 7: Cellulose nanofiber particles (manufactured by Sugino Machine, product name: Wfo - 10002, water - dispersed cellulose nanofibers replaced with acetone, solid content 2%, average particle diameter: 0.01 - 0.05 μm) (14) Urethane acrylate - 5: 6 - functional urethane acrylate + 6 - functional acrylate (manufactured by Showa Ink Manufacturing Co., Ltd., product name: HGUV - 022)

[0058] (Example 1) <Preparation of cosmetic sheet> First, RPET with a thickness of 250 μm was prepared as a substrate. Next, each material shown in Table 1 was blended to prepare a paint for Example 1 having the composition (parts by mass) shown in Table 1, and this paint was applied onto the surface of the substrate using a bar coater to form a coating film serving as the surface layer on the surface of the substrate.

[0059] In the paint for the surface layer, the volume part of the dispersion was 16 volume parts with respect to 100 volume parts of the materials (urethane acrylate, monofunctional acrylate) forming the continuous layer.

[0060] Next, using an excimer irradiation device (manufactured by M.D. Com, product name: 172 nm air - cooled excimer irradiation device (model: MEIRA - M - 1 - 152 - H4)), in a nitrogen atmosphere, excimer light (peak wavelength: 172 nm) using Xe 2 as the discharge gas was irradiated onto the coating film. The integrated light quantity was 20 mJ / cm 2 and the irradiation luminous intensity was 40 mW / cm 2 and irradiation was performed so as to achieve these values.

[0061] Then, using an ultraviolet irradiation device (manufactured by Eye Graphics Co., Ltd., high-pressure mercury lamp for ultraviolet curing 4 kW (H04-L41)), the coating film was irradiated with ultraviolet rays (main wavelength: 365 nm) to photocure the coating film, thereby forming a surface layer composed of a continuous layer containing a dispersion on the surface of the substrate to produce a decorative sheet. The ultraviolet irradiation was performed under the conditions that the irradiation distance of the ultraviolet rays was 15 cm and the lamp moving speed was 0.75 m / min, and the irradiation dose was 150 mJ / cm 2 was set.

[0062] <Measurement of thickness> Next, the thickness T of the continuous layer in the surface layer of the produced decorative sheet (the thickness of the portion in the continuous layer where the dispersion is not dispersed) was measured using a digital microscope (manufactured by Keyence Corporation, product name: VHX-5000) or a field emission scanning electron microscope (SEM) (manufactured by Hitachi High-Technologies Corporation, product name: S-4800).

[0063] More specifically, the cross-section was exposed by cutting the sheet, and when observing the cross-section with a digital microscope (measurement magnification: 500 times) or a field emission scanning electron microscope (measurement magnification: 1000 times), 10 portions with high and low coating film heights were selected, the thickness was measured, and the average value was calculated. The above measurement was performed 3 times, the average value of the coating film heights for the 3 times was calculated, and this was taken as the thickness T of the continuous layer. The above results are shown in Table 1.

[0064] <Measurement of glossiness> Next, the 60° glossiness G in the surface layer of the produced decorative sheet was measured using a gloss meter (manufactured by Horiba, Ltd., product name: Gloss Checker IG-320) in accordance with JIS Z 8741:1997. The above measurement was performed 5 times, the average value of the glossiness for the 5 times was calculated, and this was taken as the glossiness G in the surface layer.

[0065] Also, using the 5 measured glossiness values, the standard deviation σ G was calculated. More specifically, the 5 measured glossiness values were denoted as G1, G2, G3, G4, G5, and were obtained using the following formula (1). The above results are shown in Table 1.

[0066]

Number

[0067] <Measurement of surface roughness> Next, the surface roughness Sa of the surface layer of the produced cosmetic sheet (the surface roughness on the surface of the surface layer opposite to the base material side) was measured using a shape analysis laser microscope (manufactured by Keyence Corporation, product name: VK-X1000) in accordance with ISO 25178. Note that a 404 nm semiconductor laser was used as the laser type, and a range of 277 μm × 208 μm was measured using a standard objective lens with a magnification of 50 times. Further, the above measurement was performed 10 times, and the average value of the surface roughness Sa for 10 times was calculated and used as the surface roughness Sa in the surface layer.

[0068] Also, the standard deviation σ was calculated using the measured surface roughness Sa for 10 times. More specifically, the measured surface roughness for 10 times was designated as Sa1, Sa2, Sa3, Sa4, Sa5, Sa 6, Sa7, Sa8, Sa9, Sa 10 and was obtained using the following formula (2). The above results are shown in Table 1.

[0069]

Number

[0070] Then, using the calculated standard deviation σ of the surface roughness Sa of the surface layer and the thickness T of the continuous layer, the value obtained by dividing the standard deviation σ of the surface roughness Sa by the thickness T of the continuous layer 3 (that is, σ / T) was calculated. The above results are shown in Table 1.

[0071] Note that a laser microscope photograph showing the surface state of the surface layer in the cosmetic sheet of this example is shown in FIG. 2. As shown in FIG. 2, it can be seen that the cosmetic sheet of this example has low gloss, and unevenness is uniformly formed on the entire surface of the surface layer, and it has excellent aesthetics.

[0072] (Examples 2 to 28, Comparative Examples 1 to 8) A decorative sheet was produced in the same manner as in Example 1 described above, except that the composition of the coating components was changed to the compositions (parts by mass) shown in Tables 1 to 4. In Comparative Examples 7 to 8, excimer irradiation was not performed.

[0073] Then, in the same manner as in Example 1 described above, the thickness, glossiness, and surface roughness were measured. The above results are shown in Tables 1 to 3.

[0074] A laser microscope photograph showing the surface state of the surface layer in the decorative sheet of Comparative Example 3 is shown in FIG. 3. As shown in FIG. 3, it can be seen that the decorative sheet of Comparative Example 3 does not obtain a sufficient matting effect, and uneven irregularities are formed, resulting in a decrease in aesthetics (design).

[0075] <Evaluation of heat stretchability> In Examples 23 to 28, the heat stretchability was evaluated. More specifically, strip-shaped test pieces of 50 mm × 120 mm were prepared, and a tensile test was carried out to stretch 100% in the long side direction under the conditions of a stretching temperature of 90 °C, a tensile speed of 300 mm / min, and a chuck distance of 80 mm. Then, visually, those without cracks occurring perpendicular to the direction of heat stretching were marked as ○, and those with such cracks were marked as ×. The above results are shown in Table 4.

[0076]

Table 1

[0077]

Table 2

[0078]

Table 3

[0079]

Table 4

[0080] As shown in Tables 1 to 2, in the cosmetic sheets of Examples 1 to 12, they have low gloss, the standard deviation [μm] of the surface roughness Sa is 0.2 or less, and the value obtained by dividing the standard deviation [μm] of the surface roughness Sa by the thickness [μm] of the continuous layer (that is, σ / T) is 7% or less. Therefore, it can be seen that unevenness is uniformly formed on the entire surface of the surface layer and the appearance is excellent.

[0081] In addition, in the cosmetic sheets of Examples 16 to 17 and 19 using inorganic particles (low-alkali glass, silica fine particles) as the dispersion, it can be seen that they have lower gloss compared to the cosmetic sheet of Example 18 using organic particles (acrylic copolymer fine particles) as the dispersion.

[0082] On the other hand, as shown in Table 3, in the cosmetic sheets of Comparative Examples 1 to 6, the standard deviation of the surface roughness Sa is larger than 0.2 μm and σ / T is larger than 7%. Therefore, it can be seen that unevenness is formed non-uniformly on the entire surface of the surface layer and the appearance is poor.

[0083] In addition, in the cosmetic sheet of Comparative Example 3, since the blending ratio of urethane acrylate with low fluidity is large, wrinkles are less likely to occur on the surface of the surface layer, and it can be seen that the glossiness in the surface layer is high (lacking in low gloss).

[0084] Also, in the cosmetic sheets of Comparative Examples 7 to 8, since excimer irradiation was not performed, wrinkles were not formed on the surface of the coating film, and it can be seen that the glossiness in the surface layer is high (lacking in low gloss).

[0085] Also, as shown in Table 4, in the cosmetic sheets of Examples 23 to 28 using cellulose nanofiber particles as the dispersion, even when low-alkali glass is not blended, they have low gloss, the standard deviation [μm] of the surface roughness Sa is 0.2 or less, and the value obtained by dividing the standard deviation [μm] of the surface roughness Sa by the thickness [μm] of the continuous layer (that is, σ / T) is 7% or less. Therefore, it can be seen that unevenness is uniformly formed on the entire surface of the surface layer and the appearance is excellent.

[0086] Also, as shown in Table 4, in the cosmetic sheets of Examples 23 to 28 using cellulose nanofiber particles as the dispersion, no linear cracks have occurred throughout the direction perpendicular to the direction of heat stretching, and since the appearance is excellent, it can be seen that the heat stretchability is excellent. A laser microscopic photograph showing the state of the surface of the surface layer in the cosmetic sheet of Example 23 (a state in which the above-described linear cracks do not occur) is shown in FIG. 4.

Industrial Applicability

[0087] As described above, the present invention is suitable for cosmetic sheets.

Explanation of Symbols

[0088] 1 Cosmetic sheet 2 Base material 2a Surface of the base material 3 Surface layer 3a Surface of the surface layer 4 Continuous layer 5 Dispersion 6 Ultraviolet curable layer 6a Surface of the ultraviolet curable layer 7 Excimer light curable layer R Average particle diameter of the dispersion T Thickness of the continuous layer (surface layer)

Claims

1. A base material, a surface layer provided on the base material, and comprising: the surface layer is composed of a continuous layer formed by an ultraviolet curable layer formed on the surface of the base material and an excimer light curable layer formed on the surface of the ultraviolet curable layer, and a dispersion composed of at least one of organic particles and inorganic particles dispersed in the continuous layer; in the surface layer, the content of the dispersion is 20 parts by mass or more and 90 parts by mass or less with respect to 100 parts by mass of the continuous layer; the surface roughness Sa [μm] on the surface of the surface layer opposite to the base material side is 0.1 to 2.5 μm; the standard deviation σ [μm] of the surface roughness Sa [μm] is 0.2 or less; the value obtained by dividing the standard deviation σ [μm] of the surface roughness Sa [μm] by the thickness T [μm] of the continuous layer is 7% or less; the dispersion contains glass having an average particle diameter of 0.1 μm or more and 10 μm or less, and cellulose nanofiber particles having an average particle diameter of less than 0.1 μm. A cosmetic sheet characterized by the above.

2. A base material, a surface layer provided on the base material, and comprising: the surface layer is composed of a continuous layer formed by an ultraviolet curable layer formed on the surface of the base material and an excimer light curable layer formed on the surface of the ultraviolet curable layer, and a dispersion composed of at least one of organic particles and inorganic particles dispersed in the continuous layer; in the surface layer, the content of the dispersion is 10 parts by mass or more and 90 parts by mass or less with respect to 100 parts by mass of the continuous layer; the surface roughness Sa [μm] on the surface of the surface layer opposite to the base material side is 0.1 to 2.5 μm; the standard deviation σ [μm] of the surface roughness Sa [μm] is 0.2 or less; the value obtained by dividing the standard deviation σ [μm] of the surface roughness Sa [μm] by the thickness T [μm] of the continuous layer is 7% or less; The cosmetic sheet is characterized in that the dispersion is cellulose nanofiber particles having an average particle diameter of 0.01 to 0.05 μm.

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