Decorative sheets and decorative materials

Abstract

The decorative sheet for the outer packaging material of the present invention sequentially comprises a substrate layer, a decorative layer, a transparent resin layer and a surface protective layer. The substrate layer contains polyolefin, the transparent resin layer contains polyolefin, and the surface protective layer contains a hardened resin, a first ultraviolet absorber having an absorption peak at a first wavelength, a second ultraviolet absorber having an absorption peak at a second wavelength longer than the first wavelength, and a third ultraviolet absorber having an absorption peak at a third wavelength longer than the second wavelength.

Description

[Technical Field]

[0001] This invention relates to a decorative sheet and decorative material. [Previous Technology]

[0002] Previously, decorative sheets were used to decorate or protect the surfaces of building interior materials, building exterior materials, furniture, facility components, household appliances, etc. Decorative sheets, for example, have a surface protective layer on a substrate layer (see, for example, Patent Document 1).

[0003] Decorative sheets are sometimes used outdoors or in locations exposed to sunlight. When decorative sheets are used in such locations, they are affected by ultraviolet rays, causing changes in color or degradation of the resin. Therefore, ultraviolet absorbers are added to the surface protective layer of the decorative sheet to improve its weather resistance. [Prior Art Documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2000-117905 [Summary of the Invention]

[0005] [The problem the invention aims to solve]

[0006] Industry research has used polyolefins as the resin component constituting the substrate layer. However, ultraviolet light easily degrades polyolefins. The inventors have discovered that while decorative sheets containing a previously formulated surface protective layer with an ultraviolet absorber can inhibit resin degradation in the short term, they cannot adequately inhibit resin degradation in the long term.

[0007] One objective of this invention is to improve the long-term weather resistance of decorative sheets comprising a substrate layer containing a polyolefin. [Technical Means for Solving the Problem]

[0008] The decorative sheet of the present invention is an exterior decorative sheet, which sequentially comprises a substrate layer, a decorative layer, a transparent resin layer, and a surface protective layer. The substrate layer contains polyolefin, the transparent resin layer contains polyolefin, and the surface protective layer contains a hardened resin, a first ultraviolet absorber having an absorption peak at a first wavelength, a second ultraviolet absorber having an absorption peak at a second wavelength longer than the first wavelength, and a third ultraviolet absorber having an absorption peak at a third wavelength longer than the second wavelength. [Effects of the Invention]

[0009] According to the present invention, the long-term weather resistance of decorative sheets comprising a substrate layer containing polyolefin can be improved.

Implementation Method

[0011] Hereinafter, embodiments of the present invention will be described in detail. The present invention can be implemented in many different forms and is not limited to the description of the embodiments illustrated below. To make the explanation clearer, the width, thickness, and shape of each layer are sometimes schematically shown in the drawings in conjunction with the embodiments, but this is only one example and does not limit the interpretation of the present invention. In this specification and the drawings, elements that are the same as those described in existing drawings are marked with the same symbols, and detailed descriptions are sometimes appropriately omitted.

[0012] Regarding films and sheets, they are sometimes referred to as films and sheets in order of increasing thickness. However, in this invention, unless otherwise specified, sheets include films. In this invention, when multiple candidate upper limits and multiple candidate lower limits are listed for a certain parameter, the numerical range of the parameter can be formed by combining any candidate upper limit and any candidate lower limit. Examples of such parameters include: physical property values, component content, and layer thickness. As an example, the statement "Parameter B is preferably A1 or higher, more preferably A2 or higher, and even more preferably A3 or higher. Parameter B is preferably A4 or lower, more preferably A5 or lower, and even more preferably A6 or lower" will be explained. In this example, the value range of parameter B can be A1 or A4, or A1 or A5, or A1 or A6, or A2 or A4, or A2 or A5, or A2 or A6, or A3 or A4, or A3 or A5, or A3 or A6.

[0013] Unless otherwise specified, each of the components mentioned in the following description (such as resin components such as polyolefins, ultraviolet absorbers, light stabilizers, colorants and additives) may be used in one or more forms.

[0014] The decorative sheet of the present invention sequentially comprises a substrate layer, a decorative layer, a transparent resin layer, and a surface protective layer. The substrate layer contains polyolefin. The transparent resin layer contains polyolefin.

[0015] The surface protective layer contains a hardened resin, a first ultraviolet absorber having an absorption peak at a first wavelength, a second ultraviolet absorber having an absorption peak at a second wavelength longer than the first wavelength, and a third ultraviolet absorber having an absorption peak at a third wavelength longer than the second wavelength. These ultraviolet absorbers are described in detail below. With this configuration, the decorative sheet of the present invention can maintain its weather resistance for a long period in environments exposed to direct sunlight.

[0016] Decorative sheets comprising a substrate layer containing a polyolefin, a decorative layer, a transparent resin layer containing a polyolefin, and a surface protective layer in sequence tend to deteriorate easily due to ultraviolet radiation. The inventors have discovered that while decorative sheets containing a surface protective layer with one or two ultraviolet absorbers can suppress ultraviolet-induced degradation in the short term, they cannot adequately suppress ultraviolet-induced degradation in the long term. This is presumed to be due to the following reason: If the substrate layer or transparent resin layer is exposed to ultraviolet radiation for a long time, the polyolefin gradually deteriorates, and the absorption wavelength of the ultraviolet radiation slowly changes, for example, extending to the longer wavelength side. In the prior art, an ultraviolet absorber that absorbs ultraviolet radiation with the absorption wavelength before the change is added to the surface protective layer. However, this ultraviolet absorber cannot adequately absorb ultraviolet radiation with the changed absorption wavelength. Over time, ultraviolet radiation causes the decorative sheet to continuously deteriorate. Here, for example, when one or two ultraviolet absorbers are added in large quantities to the surface protective layer, the ultraviolet radiation with the changed absorption wavelength can also be absorbed. However, in such cases, problems sometimes arise due to the leakage of ultraviolet absorbers or a decrease in the adhesion and transparency of the surface protective layer. To address these issues, the inventors discovered that by using at least three ultraviolet absorbers with different wavelengths of absorption peaks in the surface protective layer, the long-term weather resistance of the decorative film can be improved. This is based on the following reasoning: By using three or more of the aforementioned ultraviolet absorbers, a wide range of ultraviolet wavelengths can be covered. Therefore, even if the absorption wavelength of the polyolefin changes due to ultraviolet radiation to the substrate layer or transparent resin layer, the aforementioned ultraviolet absorbers can still adequately absorb ultraviolet radiation across a wide wavelength range, including ultraviolet radiation with the changed absorption wavelengths. Thus, the surface protective layer can block such ultraviolet radiation. Therefore, long-term suppression of ultraviolet-induced degradation of the decorative film can be achieved. As a result, the weather resistance of the decorative film can be adequately maintained for a long period even when exposed to direct sunlight.

[0017] FIG1 shows a schematic cross-sectional view of one embodiment of the decorative sheet of the present invention. The decorative sheet 1 comprises, in sequence along the thickness direction: a substrate layer 10 having a first surface 11 and a second surface 12 located opposite to the first surface 11; a decorative layer 20 disposed on the first surface 11 of the substrate layer 10; a transparent resin layer 30; a base coating layer 40; and a surface protective layer 50. That is, the substrate layer 10, the decorative layer 20, the transparent resin layer 30, the base coating layer 40, and the surface protective layer 50 overlap in the thickness direction, which is the vertical direction in FIG1. ​​The decorative sheet 1 may also have an adhesive layer (not shown) between the decorative layer 20 and the transparent resin layer 30. The decorative sheet 1 may also have an adhesive layer (not shown) on the second surface 12 of the substrate layer 10.

[0018] The decorative sheet of the present invention includes a substrate layer. The substrate layer contains a polyolefin. Examples of polyolefins include polyethylene, polypropylene, polybutene, and polymethylpentene. In one embodiment, the substrate layer contains polypropylene.

[0019] Examples of polypropylene include: homopolymers of propylene; copolymers such as ethylene-propylene copolymers, propylene-butene copolymers, and ethylene-propylene-butene copolymers. Among these, homopolymers of propylene, ethylene-propylene copolymers, and propylene-butene copolymers are preferred.

[0020] Regarding the content ratio of polyolefin in the substrate layer, from the viewpoint of processability, it is preferably 50% by mass or more, more preferably 60% by mass or more, and even more preferably 70% by mass or more, and especially preferably 80% by mass or more, relative to the total resin content of the substrate layer.

[0021] The substrate layer may also contain additives. Examples of additives include: ultraviolet absorbers, light stabilizers, antioxidants, abrasion resistance improvers, infrared absorbers, antistatic agents, fillers, foaming agents, flame retardants, plasticizers, anti-settling agents, lubricants, and colorants. Examples of ultraviolet absorbers include: benzotriazole ultraviolet absorbers, benzophenone ultraviolet absorbers, triterpenoid ultraviolet absorbers, and hydroxyphenyl triterpenoid ultraviolet absorbers. Examples of light stabilizers include: hindered amine light stabilizers such as piperidinium sebacic acid ester light stabilizers.

[0022] The substrate layer may be colorless and transparent, or it may contain colorants such as dyes and pigments. For example, if the surface color of the object to which the decorative sheet is to be attached is uneven and it is desired to mask the surface color and improve the color stability of the decorative layer, the substrate layer may contain inorganic pigments such as white pigments.

[0023] As pigments, examples include: white pigments such as zinc white, lead white, zinc barium white, titanium dioxide, precipitated barium sulfate and barite; black pigments such as carbon black; red pigments such as lead oxide and iron oxide red; yellow pigments such as chrome yellow and zinc yellow (zinc potassium chromate, zinc chromate tetroxide); and blue pigments such as ultramarine blue and Prussian blue (ferrous ferrocyanide).

[0024] The content of colorant may be more than 1 part by mass, more than 3 parts by mass, more than 5 parts by mass, less than 50 parts by mass, less than 40 parts by mass, or less than 30 parts by mass, for example, more than 1 part by mass and less than 50 parts by mass.

[0025] From the viewpoint of balancing designability and processability, the thickness of the substrate layer is preferably 20 μm or more, more preferably 25 μm or more, and even more preferably 30 μm or more, and preferably 150 μm or less, more preferably 120 μm or less, and even more preferably 100 μm or less, for example, 20 μm or more and 150 μm or less.

[0026] Surface treatment can also be applied to one or both sides of the substrate layer. Examples of surface treatments include physical surface treatments such as oxidation and texturing, as well as chemical surface treatments. Examples of oxidation methods include corona discharge treatment, chromating treatment, flame treatment, hot air treatment, and ozone-ultraviolet treatment. Examples of texturing methods include sandblasting and solvent treatment. The substrate layer may have an easy-adhesion layer on one or both sides. This can, for example, improve the interlayer adhesion between the substrate layer and other layers.

[0027] The decorative sheet of the present invention includes a decorative layer. In one embodiment, the decorative layer is disposed on a substrate layer. In other words, in this embodiment, the decorative sheet includes a decorative layer that overlaps with the substrate layer in the thickness direction. The substrate layer and the decorative layer are in contact, and other layers may also exist between the substrate layer and the decorative layer.

[0028] A decorative layer is provided to give the decorative piece a sense of design. The decorative layer may have a pattern. Examples of patterns include: wood grain imitations such as annual rings or vascular bundles on the surface of wood panels; stone grain imitations such as marble and granite; fabric grain imitations; leather grain imitations; pear skin grain; brick grain; tile grain; geometric patterns; and abstract patterns such as text, graphics, symbols, water droplets, and flower stems. The pattern may be a single color (a so-called solid image). The pattern may also be a composite pattern containing two or more such patterns. The decorative layer may have two or more layers. For example, the decorative layer may have a first layer that has been colored, and a second layer on which the pattern is formed.

[0029] The decorative layer can be formed by, for example, printing or coating methods. Examples of printing methods include gravure printing, offset printing, screen printing, printing by transfer from a self-rotating sheet, and inkjet printing. Examples of coating methods include gravure coating, gravure reverse coating, gravure offset coating, spin coating, roller coating, and reverse roller coating. The layers described below can also be formed by such methods.

[0030] In one embodiment, the decorative layer contains a resin component and a colorant. Examples of resin components include: vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-(meth)acrylic acid copolymer, chlorinated polyethylene, chlorinated polypropylene, urethane-(meth)acrylic acid copolymer, (meth)acrylic resin, (meth)acrylic polyol resin, polystyrene, polyurethane, polyester, polyamide, butyraldehyde resin, nitrocellulose, and cellulose acetate.

[0031] As coloring agents, examples include pigments and dyes. Specifically, examples include inorganic pigments such as carbon black, iron black, titanium dioxide, antimony white, chrome yellow, titanium yellow, red lead, cadmium red, ultramarine, and cobalt blue; organic pigments or dyes such as quinacridone red, isoindolinone yellow, phthalocyanine blue, methyliminoazo black, and nickel azo complexes; metallic pigments containing flake-like foils such as aluminum and brass; and pearlescent (pearlescent) pigments containing flake-like foils such as titanium dioxide coated with mica and basic lead carbonate.

[0032] Compared to 100 parts by weight of resin component contained in the decorative layer, the content of colorant in the decorative layer may be 5 parts by weight or more, or 15 parts by weight or more, or 30 parts by weight or more, or 200 parts by weight or less, or 150 parts by weight or less, or 100 parts by weight or less, for example, 5 parts by weight or more and 200 parts by weight or less.

[0033] The decorative layer may also contain additives. Examples of additives include: ultraviolet absorbers, light stabilizers, antioxidants, fillers, defoamers, flame retardants, plasticizers, and lubricants. From the viewpoint of improving weather resistance, the decorative layer may contain weather-resistant agents such as ultraviolet absorbers, light stabilizers, and antioxidants.

[0034] The thickness of the decorative layer is preferably 0.5 μm or more, more preferably 1 μm or more, and even more preferably 2 μm or more, and preferably 20 μm or less, more preferably 15 μm or less, and even more preferably 10 μm or less, for example, 0.5 μm or more and 20 μm or less. This, for example, can improve the design flexibility of the decorative sheet.

[0035] The decorative layer may also have a metal thin film. Examples of metals constituting the metal thin film include tin, indium, chromium, aluminum, nickel, iron, cobalt, copper, silver, gold, platinum, and zinc, as well as alloys containing at least one of these metals. Examples of alloys include brass, bronze, and stainless steel. Examples of methods for forming the metal thin film include vacuum evaporation, sputtering, and ion plating. The thickness of the metal thin film is, for example, 0.1 μm or more and 1 μm or less.

[0036] The decorative sheet of the present invention may also have a masking layer between the substrate layer and the decorative layer. By providing a masking layer, for example, it is possible to suppress the adverse effects of the substrate layer on the color or pattern of the decorative sheet.

[0037] The masking layer may be an opaque layer. In one embodiment, the masking layer contains a resin component and a colorant. The resin component and colorant in the masking layer may be appropriately selected from the resin component and colorant in the decorative layer, and therefore description is omitted here. The masking layer may also contain the aforementioned additives. The thickness of the masking layer is, for example, 1 μm or more and 20 μm or less.

[0038] The decorative sheet of the present invention comprises a transparent resin layer. The transparent resin layer is located between the decorative layer and the surface protective layer.

[0039] The transparent resin layer contains a polyolefin. Examples of polyolefins include polyethylene, polypropylene, polybutene, and polymethylpentene. In one embodiment, the transparent resin layer contains polypropylene. The polyolefin contained in the transparent resin layer may be the same as or different from the polyolefin contained in the substrate layer.

[0040] Examples of polypropylene include: homopolymers of propylene; copolymers such as ethylene-propylene copolymers, propylene-butene copolymers, and ethylene-propylene-butene copolymers. Among these, homopolymers of propylene, ethylene-propylene copolymers, and propylene-butene copolymers are preferred.

[0041] Regarding the content ratio of polyolefin in the transparent resin layer, from the viewpoint of processability, it is preferably 50% by mass or more, more preferably 60% by mass or more, and even more preferably 70% by mass or more, and particularly preferably 80% by mass or more, relative to the total resin content of the transparent resin layer.

[0042] The transparent resin layer may also contain ultraviolet absorbers such as the first to third ultraviolet absorbers described later. The transparent resin layer may also contain light stabilizers described later. The transparent resin layer may also contain the above-mentioned additives.

[0043] Relative to 100 parts by mass of polyolefin contained in the transparent resin layer, the content of ultraviolet absorber in the transparent resin layer may be 0.05 parts by mass or more, or 0.10 parts by mass or more, or 10 parts by mass or less, or 5 parts by mass or less, for example, 0.05 parts by mass or more and 10 parts by mass or less.

[0044] Relative to 100 parts by mass of polyolefin contained in the transparent resin layer, the content of light stabilizer in the transparent resin layer may be 0.1 parts by mass or more, or 0.5 parts by mass or more, or 10 parts by mass or less, or 8 parts by mass or less, for example, 0.1 parts by mass or more and 10 parts by mass or less.

[0045] The transparent resin layer only needs to achieve the transparency that allows the substrate layer to be observed through the transparent resin layer. In addition to colorless and transparent, it can also be colored transparent and semi-transparent.

[0046] From the viewpoint of balancing scratch resistance, processability, and weather resistance, the thickness of the transparent resin layer can be 20 μm or more, or 40 μm or more, or 60 μm or more, or 150 μm or less, or 120 μm or less, or 100 μm or less, for example, 20 μm or more and 150 μm or less. From the viewpoint of protecting the decorative layer and obtaining excellent scratch resistance, the thickness of the transparent resin layer is preferably greater than the thickness of the substrate layer.

[0047] The decorative sheet of the present invention includes a surface protective layer. The surface protective layer is disposed on a transparent resin layer. In other words, the surface protective layer and the transparent resin layer overlap in the thickness direction. In one embodiment, the surface protective layer is disposed on the entire surface of the transparent resin layer. In one embodiment, the surface protective layer constitutes the outermost layer on one side of the decorative sheet. By providing a surface protective layer, for example, the heat resistance, scratch resistance, and stain resistance of the decorative sheet can be improved.

[0048] The surface protective layer contains a curing resin. The curing resin functions, for example, as an adhesive in the surface protective layer. Examples of curing resins include cured forms of curable compounds. Examples of cured forms of curable compounds include cured forms of ionizing radiation curable compounds and cured forms of thermosetting resins. The surface protective layer may also contain two or more of these curing resins.

[0049] Examples of thermosetting resins include: (meth)acrylic resins containing unsaturated groups, unsaturated polyesters, urethane resins, epoxy resins, phenolic resins, amino alkyd resins, urea resins, melamine resins, melamine-urea cocondensation resins, guanidine resins, diallyl phthalate resins, and polysiloxane resins.

[0050] A curing agent may be used in conjunction with a thermosetting resin as needed. In the case of (meth)acrylic resins containing unsaturated groups and unsaturated polyesters, peroxides such as methyl ethyl ketone peroxide or free radical initiators such as azoisobutyronitrile may be used. In the case of urethane resins, isocyanate-based curing agents may be used, for example. In the case of epoxy resins, organic amine-based curing agents may be used, for example.

[0051] Examples of thermosetting resins include, for example, two-component curable urethane resins using a polyol as the main agent and an isocyanate compound as the curing agent. Examples of polyols include, for example, (meth)acrylic acid polyols, polyether polyols, polyester polyols, polyethylene glycol, and polypropylene glycol. The isocyanate compound is a polyisocyanate containing two or more isocyanate groups, for example, aromatic isocyanates such as 4,4-diphenylmethane diisocyanate; aliphatic (or alicyclic) isocyanates such as hexamethylene diisocyanate, isophorone diisocyanate, hydrogenated toluene diisocyanate, and hydrogenated diphenylmethane diisocyanate.

[0052] In one embodiment, the surface protective layer contains a curing material of a thermosetting resin as the curing resin, such as a cross-linked curing material of a (meth)acrylic polyol obtained using an isocyanate-based curing agent.

[0053] Ionizing radiation-hardening compounds refer to compounds that are cross-linked and hardened by irradiation with ionizing radiation, possessing ionizing radiation-hardening functional groups. Ionizing radiation-hardening functional groups refer to groups that are cross-linked by irradiation with ionizing radiation, such as (meth)acrylyl, vinyl, and allyl functional groups possessing vinyl double bonds (vinyl unsaturated groups). Ionizing radiation refers to electromagnetic waves or charged particle beams containing energy quanta capable of polymerizing or cross-linking molecules. Examples of ionizing radiation include electron beams (EB) and ultraviolet light (UV); examples also include electromagnetic waves such as X-rays and gamma rays, and charged particle beams such as alpha rays and ion beams. From the viewpoint of containing ultraviolet absorbers in the surface protective layer, electron beams are preferred as ionizing radiation.

[0054] Examples of ionizing radiation hardening compounds include polymeric monomers and polymeric oligomers conventionally used as ionizing radiation hardening compounds. As a polymeric monomer, a (meth)acrylate monomer having a (meth)acrylic group in its molecule is preferred, and a polyfunctional (meth)acrylate monomer having two or more (meth)acrylic groups in its molecule is even more preferred. The number of (meth)acrylic groups in the polyfunctional (meth)acrylate monomer is two or more, and preferably eight or less, more preferably six or less.

[0055] As polymerizable monomers, examples include: difunctional (meth)acrylates such as ethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, bisphenol A tetraethoxydi(meth)acrylate and bisphenol A tetrapropoxydi(meth)acrylate; trifunctional or higher (meth)acrylates such as trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol tri(meth)acrylate, dipentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate and dipentaerythritol hexa(meth)acrylate; and ethylene oxide modified, propylene oxide modified, caprolactone modified, isocyanuric acid modified or propionic acid modified forms of such (meth)acrylates.

[0056] Examples of polymerizable oligomers include (meth)acrylate oligomers having two or more (meth)acrylic groups in the molecule. Examples of (meth)acrylate oligomers include: urethane (meth)acrylate, epoxy (meth)acrylate, polyester (meth)acrylate, polyether (meth)acrylate, polycarbonate (meth)acrylate, polycaprolactone urethane (meth)acrylate, polycaprolactone diol urethane (meth)acrylate, and acrylic (meth)acrylate. The number of (meth)acrylic groups in the polymerizable oligomer is two or more, preferably eight or less, and more preferably six or less.

[0057] Other examples of polymerizable oligomers include: polybutadiene (meth)acrylate oligomers with high hydrophobicity having (meth)acrylic groups in the side chains of polybutadiene oligomers, and polysiloxane (meth)acrylate oligomers having polysiloxane bonds in the main chain.

[0058] The weight average molecular weight of the polymeric oligomer can be 500 or more, 1,000 or more, 2,000 or more, and 10,000 or less, 8,000 or less, or 6,000 or less, for example, 500 or more and 10,000 or less. The weight average molecular weight is determined by gel permeation chromatography (GPC) analysis and is the average molecular weight obtained by conversion to standard polystyrene.

[0059] As a free-radiation curing compound, in order to reduce the viscosity of the curing composition during coating, a monofunctional (meth)acrylate may be appropriately used in combination with a polyfunctional (meth)acrylate. Examples of monofunctional (meth)acrylates include: methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, pentyl methacrylate, hexyl methacrylate, cyclohexyl methacrylate, 2-ethylhexyl methacrylate, lauryl methacrylate, stearyl methacrylate, and isopropyl methacrylate.

[0060] When the free radiation-curing compound is an ultraviolet-curing compound, it is preferable to use it together with the ultraviolet-curing compound at least one selected from photopolymerization initiator and photopolymerization accelerator.

[0061] From the viewpoint of excellent heat resistance, scratch resistance, and stain resistance, the surface protective layer is preferably a hardened material containing a hardening compound, and more preferably a hardened material containing an ionizing radiation hardening compound. Among ionizing radiation hardening compounds, electron beam hardening compounds can achieve solvent-free curing, do not require photopolymerization initiators, and can obtain stable curing properties, thus making them suitable as components forming the surface protective layer. Among ionizing radiation hardening compounds, polymeric oligomers are preferred, more preferably (meth)acrylate oligomers having two or more (meth)acrylic groups in the molecule, and even more preferably urethane (meth)acrylates.

[0062] The content of the hardened resin is preferably 50% by mass or more, more preferably 70% by mass or more, and even more preferably 80% by mass or more, and even more preferably 90% by mass or more, relative to all the resin components contained in the surface protective layer.

[0063] The surface protective layer contains a first ultraviolet absorber having an absorption peak at a first wavelength, a second ultraviolet absorber having an absorption peak at a second wavelength longer than the first wavelength, and a third ultraviolet absorber having an absorption peak at a third wavelength longer than the second wavelength. Each absorption peak is based on the absorbance spectrum measured using an ultraviolet-visible-near-infrared spectrophotometer.

[0064] The first ultraviolet absorber has an absorption peak at a first wavelength. The first wavelength is preferably in the range of 270 nm to 300 nm, more preferably in the range of 270 nm to 290 nm, and even more preferably in the range of 270 nm to 280 nm.

[0065] The second ultraviolet absorber has an absorption peak at a second wavelength. The second wavelength is preferably in the range of 310 nm to 330 nm, and more preferably in the range of 310 nm to 325 nm.

[0066] The third ultraviolet absorber has an absorption peak at a third wavelength. The third wavelength is preferably in the range of 340 nm to 370 nm, and more preferably in the range of 345 nm to 365 nm.

[0067] The above-mentioned absorption peak preferably refers to the maximum absorption peak in the wavelength region of 270 nm to 380 nm. For example, when the first ultraviolet absorber has multiple absorption peaks in the above-mentioned wavelength region, the maximum absorption peak is preferably in the range of 270 nm to 300 nm.

[0068] The difference between the second wavelength and the first wavelength is preferably 10 nm or more, more preferably 20 nm or more, and even more preferably 30 nm or more, and preferably 60 nm or less, more preferably 55 nm or less, and even more preferably 50 nm or less, for example, 10 nm or more and 60 nm or less.

[0069] The difference between the third wavelength and the second wavelength is preferably 10 nm or more, more preferably 20 nm or more, and even more preferably 30 nm or more, and preferably 60 nm or less, more preferably 55 nm or less, and even more preferably 50 nm or less, for example, 10 nm or more and 60 nm or less.

[0070] The difference between the third wavelength and the first wavelength is preferably 40 nm or more, more preferably 50 nm or more, and even more preferably 60 nm or more, and preferably 100 nm or less, more preferably 95 nm or less, and even more preferably 90 nm or less, for example, 40 nm or more and 100 nm or less.

[0071] It is believed that the first and second ultraviolet absorbers help to inhibit early resin degradation. It is believed that the second and third ultraviolet absorbers help to inhibit long-term resin degradation.

[0072] Examples of the first to third ultraviolet absorbers include triazine-based ultraviolet absorbers, benzotriazole-based ultraviolet absorbers and benzophenone-based ultraviolet absorbers. From the viewpoints of excellent weather resistance, absorbance, and wavelength selectivity, triazine-based ultraviolet absorbers are preferred.

[0073] Among triterpenoid ultraviolet absorbers, hydroxyphenyl triterpenoid ultraviolet absorbers are preferred from the viewpoint of weather resistance. Examples of hydroxyphenyl triterpenoid ultraviolet absorbers include compounds represented by formula (1), compounds represented by formula (2), and compounds represented by formula (3).

[0074] [Chemical 1]

[0075] In formula (1), R11 is a divalent organic group, R12 is a acetooxy group represented by -OC (=O)R15, R13 and R14 are each independently monovalent organic groups, R15 is a hydrogen atom or a monovalent organic group, and n11 and n12 are each independently an integer between 0 and 5. When there are multiple R13s, each R13 may be the same or different. When there are multiple R14s, each R14 may be the same or different.

[0076] As a divalent organic group of R 11, examples include aliphatic hydrocarbons such as alkyl and alkenyl groups. From the viewpoint of weather resistance, alkyl groups are preferred. From the viewpoint of weather resistance, the number of carbon atoms in the aliphatic hydrocarbon group is preferably 1 or more, more preferably 2 or more, and preferably 16 or less, more preferably 12 or less, further preferably 8 or less, and especially preferably 4 or less, for example, 1 or more and 16 or less. The aliphatic hydrocarbon group can be any of linear, branched, or cyclic forms. From the viewpoint of weather resistance, linear or branched forms are preferred, and linear forms are more preferred.

[0077] As a monovalent organic group of R 13 and R 14, for example: aliphatic hydrocarbons such as alkyl, alkenyl and cycloalkyl, aryl and arylalkyl hydrocarbons containing aromatic rings, from the viewpoint of weather resistance, it is more preferably an aromatic ring hydrocarbon, more preferably an aryl, and especially preferably a phenyl.

[0078] From the perspective of weather resistance, n11 and n12 are preferably 0.

[0079] From the viewpoint of weather resistance, R 15 is preferably a monovalent organic group. Examples of monovalent organic groups include aliphatic hydrocarbons such as alkyl, alkenyl, and cycloalkyl, and aromatic ring-containing hydrocarbons such as aryl and arylalkyl. From the viewpoint of weather resistance, aliphatic hydrocarbons are preferred, and alkyl hydrocarbons are more preferred. From the viewpoint of weather resistance, the aliphatic hydrocarbon has preferably 2 or more carbon atoms, more preferably 4 or more, and preferably 16 or less, more preferably 12 or less, and further preferably 10 or less, for example, 2 or more and 16 or less. The aliphatic hydrocarbon can be any of linear, branched, or cyclic forms, but from the viewpoint of weather resistance, linear or branched forms are preferred.

[0080] [Chemical 2]

[0081] In formula (2), R21 is a hydrogen atom or a monovalent organic group, R22 and R23 are each independently a hydroxyl group or a monovalent organic group, and n21, n22 and n23 are each independently an integer between 1 and 5. When there are multiple R21s, each R21 may be the same or different. When there are multiple R22s, each R22 may be the same or different. When there are multiple R23s, each R23 may be the same or different.

[0082] As a monovalent organic group of R 21, examples can be given of the groups represented by the monovalent organic groups of R 13 and R 14 in formula (1), and also of the group represented by -R 24-C(=O)OR 25. R 24 is a divalent organic group, and R 25 is a monovalent organic group. As for the monovalent organic groups of R 22 and R 23, examples can be given of the groups represented by the monovalent organic groups of R 13 and R 14 in formula (1). From the viewpoint of weather resistance, it is preferred to be a hydrocarbon group containing an aromatic ring, more preferably an aryl group, and especially preferably a phenyl group.

[0083] As a divalent organic group of R 24, an example can be the group exemplified as the divalent organic group of R 11 in formula (1). From the viewpoint of weather resistance, it is preferably an aliphatic hydrocarbon group, and more preferably an alkyl group. From the viewpoint of weather resistance, the number of carbons of the aliphatic hydrocarbon group is preferably 1 or more, more preferably 2 or more, and preferably 16 or less, more preferably 12 or less, further preferably 8 or less, and especially preferably 4 or less, for example, 1 or more and 16 or less. The aliphatic hydrocarbon group can be any of straight-chain, branched, or cyclic. From the viewpoint of weather resistance, it is preferably straight-chain or branched, and more preferably straight-chain.

[0084] As a monovalent organic group of R 25, examples can be given of the group exemplified as the monovalent organic group of R 15 in formula (1). From the viewpoint of weather resistance, it is preferably an aliphatic hydrocarbon group, and more preferably an alkyl group. From the viewpoint of weather resistance, the aliphatic hydrocarbon group preferably has 2 or more carbon atoms, more preferably 4 or more, and preferably 16 or less, more preferably 12 or less, and even more preferably 10 or less, for example, 2 or more and 16 or less. The aliphatic hydrocarbon group can be any of straight-chain, branched, or cyclic, and from the viewpoint of weather resistance, it is preferably straight-chain or branched.

[0085] n 21 can be 2 or more, and n 22 and n 23 can each be 1. In this case, one of the plurality of R 21 can be a hydrogen atom, and R 22 and R 23 can be the same organogroup when they are monovalent organogroups.

[0086] [Chemical 3]

[0087] In formula (3), R31, R32, and R33 are each independently a hydrogen atom or a monovalent organic group, and n31, n32, and n33 are each independently an integer between 1 and 5. When there are multiple R31s, each R31 may be the same or different. When there are multiple R32s, each R31 may be the same or different. When there are multiple R33s, each R31 may be the same or different.

[0088] As monovalent organic groups R 31, R 32 and R 33, examples can be given of the groups represented by R 13 and R 14 in formula (1), and also of the group represented by -R 34-C(=O)OR 35. R 34 is a divalent organic group and R 35 is a monovalent organic group.

[0089] As a divalent organic group of R 34, an example can be the group exemplified as the divalent organic group of R 11 in formula (1). From the viewpoint of weather resistance, it is preferably an aliphatic hydrocarbon group, and more preferably an alkyl group. From the viewpoint of weather resistance, the number of carbons of the aliphatic hydrocarbon group is preferably 1 or more, more preferably 2 or more, and preferably 16 or less, more preferably 12 or less, further preferably 8 or less, and especially preferably 4 or less, for example, 1 or more and 16 or less. The aliphatic hydrocarbon group can be any of straight-chain, branched, or cyclic. From the viewpoint of weather resistance, it is preferably straight-chain or branched, and more preferably straight-chain.

[0090] As a monovalent organic group of R 35, an example of the group exemplified as the monovalent organic group of R 15 in formula (1) can be taken. From the viewpoint of weather resistance, it is preferably an aliphatic hydrocarbon group, and more preferably an alkyl group. From the viewpoint of weather resistance, the aliphatic hydrocarbon group preferably has 2 or more carbon atoms, more preferably 4 or more, and preferably 16 or less, more preferably 12 or less, and even more preferably 10 or less, for example, 2 or more and 16 or less. The aliphatic hydrocarbon group can be any of straight-chain, branched, or cyclic, and from the viewpoint of weather resistance, it is preferably straight-chain or branched.

[0091] n 31, n 32 and n 33 can each be 2 or more. In this case, one of the plurality of R 31 can be a hydrogen atom, one of the plurality of R 32 can be a hydrogen atom, and one of the plurality of R 33 can be a hydrogen atom.

[0092] Specifically, examples of hydroxyphenyl triterpenoid ultraviolet absorbers include: 2-(2-hydroxy-4-[1-octoxycarbonylethoxy]phenyl)-4,6-bis(4-phenylphenyl)-1,3,5-triterpenoid, 2-[4-[(2-hydroxy-3-dodecyloxypropyl)oxy]-2-hydroxyphenyl]-4,6-bis(2,4-dimethylphenyl)-1,3,5-triterpenoid, 2,4-bis[2-hydroxy-4-butoxyphenyl]-6-(2,4-dibutoxyphenyl)-1,3,5-triterpenoid 𠯤, 2-[4-[(2-hydroxy-3-tetrazoxypropyl)oxy]-2-hydroxyphenyl]-4,6-bis(2,4-dimethylphenyl)-1,3,5-tris(2,4-dimethylphenyl)-1,3,5-tris(2,4-diphenyl-1,3,5-tris(2,4-dimethylphenyl)ethoxy]phenol, 2-[4-[(2-hydroxy-3-(2'-ethylhexyl)oxy]-2-hydroxyphenyl]-4,6-bis(2,4-dimethylphenyl)-1,3,5-tris(2,4-dimethylphenyl)-1,3,5-tris(2,4-dimethylphenyl)ethoxy], and compounds represented by the following formulas.

[0093] [Chemical 4]

[0094] In the surface protective layer, the total content of the first ultraviolet absorber, the second ultraviolet absorber, and the third ultraviolet absorber relative to 100 parts by weight of the cured resin is preferably 0.5 parts by weight or more, more preferably 1 part by weight or more, and even more preferably 2 parts by weight or more, and preferably 10 parts by weight or less, more preferably 8 parts by weight or less, and even more preferably 6 parts by weight or less, for example, 0.5 parts by weight or more and 10 parts by weight or less. If the total content of the ultraviolet absorber is at or above the lower limit, there is a tendency to improve the weather resistance of the decorative sheet. If the total content of the ultraviolet absorber is below the upper limit, there is a tendency to suppress the exudation of the ultraviolet absorber.

[0095] In the surface protective layer, the content of the first ultraviolet absorber relative to 100 parts by weight of the cured resin is preferably 0.1 parts by weight or more, more preferably 0.2 parts by weight or more, and even more preferably 0.3 parts by weight or more, and preferably 3 parts by weight or less, more preferably 2 parts by weight or less, and even more preferably 1.5 parts by weight or less, for example, 0.1 parts by weight or more and 3 parts by weight or less. This, for example, tends to further improve initial weather resistance.

[0096] In the surface protective layer, the content of the second ultraviolet absorber relative to 100 parts by weight of the cured resin is preferably 0.1 parts by weight or more, more preferably 0.5 parts by weight or more, and even more preferably 1 part by weight or more, and preferably 8 parts by weight or less, more preferably 6 parts by weight or less, and even more preferably 5 parts by weight or less, for example, 0.1 parts by weight or more and 8 parts by weight or less. This, for example, tends to further improve initial and long-term weather resistance.

[0097] In the surface protective layer, the content of the third ultraviolet absorber relative to 100 parts by weight of the cured resin is preferably 0.1 parts by weight or more, more preferably 0.2 parts by weight or more, and even more preferably 0.3 parts by weight or more, and preferably 3 parts by weight or less, more preferably 2 parts by weight or less, and even more preferably 1.5 parts by weight or less, for example, 0.1 parts by weight or more and 3 parts by weight or less. This, for example, tends to further improve long-term weather resistance.

[0098] In one embodiment, the content of the second ultraviolet absorber in the surface protective layer is greater than the content of the first ultraviolet absorber and also greater than the content of the third ultraviolet absorber. This allows the surface protective layer to absorb ultraviolet light across a wide wavelength range, and for example, it tends to further improve initial and even long-term weather resistance.

[0099] From the viewpoint of weather resistance, the surface protective layer may also contain a light stabilizer. Examples of light stabilizers include aromatic light stabilizers, amine light stabilizers, organic acid light stabilizers, catechin light stabilizers, and hindered amine light stabilizers, among which hindered amine light stabilizers are preferred. A hindered amine light stabilizer is, for example, a compound having a structure containing a 2,2,6,6-tetramethylpiperidine skeleton within its molecule.

[0100] Examples of light stabilizers include reactive light stabilizers having vinyl double bonds capable of polymerizing with a curing compound that can form a surface protective layer, and non-reactive light stabilizers not having vinyl double bonds capable of polymerizing with the curing compound. Vinyl double bonds may include, for example, (meth)acrylic, vinyl, and allyl functional groups. The surface protective layer may contain at least one selected from reactive and non-reactive light stabilizers, or it may contain both reactive and non-reactive light stabilizers.

[0101] Reactive light stabilizers are typically immobilized within the curing resin system during the formation of the surface protective layer, thus providing long-term effects. Non-reactive light stabilizers are mobile within the surface protective layer, thus providing immediate effects.

[0102] The number of vinyl double bonds in a reactive light stabilizer can be one or more.

[0103] Examples of reactive light stabilizers having one vinyl double bond include: 4-(meth)propenyloxy-2,2,6,6-tetramethylpiperidine, 4-(meth)propenylamino-2,2,6,6-tetramethylpiperidine, 4-(meth)propenyloxy-1,2,2,6,6-pentamethylpiperidine, and 4-(meth)propenylamino-1,2,2,6,6-pentamethylpiperidine. Piperidine, 4-cyano-4-(meth)propenylamino-2,2,6,6-tetramethylpiperidine, 4-crotonyloxy-2,2,6,6-tetramethylpiperidine and 4-crotonylamino-2,2,6,6-tetramethylpiperidine, pentamethylpiperidinyl(meth)acrylate, compounds with CAS number 1010692-24-6 and compounds with CAS number 1010692-21-3. Examples of reactive light stabilizers having two or more vinyl double bonds include: 1-(meth)propenyl-4-(meth)propenylamino-2,2,6,6-tetramethylpiperidine, 1-(meth)propenyl-4-cyano-4-(meth)propenylamino-2,2,6,6-tetramethylpiperidine, 1-crotonyl-4-crotonyloxy-2,2,6,6-tetramethylpiperidine, the compound with CAS number 1954659-42-7, and the compound with CAS number 1010692-23-5.

[0104] Examples of non-reactive light stabilizers include: 4-benzoyloxy-2,2,6,6-tetramethylpiperidine, bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, bis(1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate, bis(1-octoxy-2,2,6,6-tetramethyl-4-piperidinyl) sebacate, bis(1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate, and methyl sebacate (1,2,2,6,6...). 2,4-Bis[N-butyl-N-(1-cyclohexyloxy-2,2,6,6-tetramethyl-4-piperidinyl)amino]-6-(2-hydroxyethylamine)-1,3,5-trimethylol, 1,2,3,4-butanetetracarboxylic acid tetra(1,2,2,6,6-pentamethyl-4-piperidinyl) ester, and 2-(3,5-di-tert-butyl-4-hydroxy-benzyl)-2-n-butylmalonic acid bis-(1,2,2,6,6-pentamethyl-4-piperidinyl) ester.

[0105] In the surface protective layer, the content of the light stabilizer relative to 100 parts by weight of the cured resin is preferably 0.5 parts by weight or more, more preferably 1 part by weight or more, and even more preferably 1.5 parts by weight or more, and preferably 10 parts by weight or less, more preferably 8 parts by weight or less, and even more preferably 6 parts by weight or less, for example, 0.5 parts by weight or more and 10 parts by weight or less.

[0106] The surface protective layer preferably contains the above-mentioned reactive light stabilizer and the above-mentioned non-reactive light stabilizer. The mixing ratio of the above-mentioned reactive light stabilizer and the above-mentioned non-reactive light stabilizer in the surface protective layer (reactive light stabilizer: non-reactive light stabilizer) based on mass is preferably 8:2 to 0:10.

[0107] The surface protective layer may also contain additives, such as antioxidants, wear resistance improvers, infrared absorbers, antistatic agents, leveling agents, shake-tolerance agents, coupling agents, defoamers, flame retardants, plasticizers, particles and anti-blocking agents.

[0108] The surface protective layer is preferably substantially free of polyolefins. This, for example, tends to improve the weather resistance of the surface protective layer. "Substantially free of polyolefins" means that, relative to the total resin components contained in the surface protective layer, the content of polyolefins is 1% by mass or less, preferably 0.1% by mass or less, more preferably 0.01% by mass or less, and even more preferably 0% by mass.

[0109] In the decorative sheet of the present invention, the absorbance A1 of the surface protective layer at a wavelength of 270 nm to 300 nm is preferably 0.3 or more, the absorbance A2 at a wavelength of 310 nm to 330 nm is preferably 0.6 or more, and the absorbance A3 at a wavelength of 340 nm to 370 nm is preferably 0.2 or more.

[0110] Polyolefins tend to deteriorate by absorbing ultraviolet light with wavelengths between 270 nm and 300 nm. Therefore, by increasing the cutoff rate of ultraviolet light with wavelengths between 270 nm and 300 nm, the deterioration of polyolefins in each layer, including the substrate layer and the transparent resin layer, can be suppressed, thereby improving the weather resistance of the decorative sheet. Furthermore, as mentioned above, from the viewpoint of long-term weather resistance, not only absorbance A1 is considered, but also absorbance A2 at wavelengths between 310 nm and 330 nm, and absorbance A3 at wavelengths between 340 nm and 370 nm. This further improves the weather resistance of decorative sheets containing substrate layers and transparent resin layers, which each contain polyolefins.

[0111] The absorbance A1 is preferably 0.3 or higher, more preferably 0.35 or higher, for example, it can be 0.5 or higher, or it can be 0.7 or higher. There is no particular limit to the upper limit of absorbance A1, for example, it can be 1.5.

[0112] The absorbance A2 is preferably 0.6 or higher, more preferably 0.7 or higher, for example, it can be 1.0 or higher, or 1.2 or higher. There is no particular limit to the upper limit of absorbance A2, for example, it can be 3.0.

[0113] The absorbance A3 is preferably 0.2 or higher, and more preferably 0.25 or higher. There is no particular upper limit to the absorbance A3, for example, it can be 1.5.

[0114] The absorbance A1, A2 and A3 can be adjusted, for example, by the content of the first to third ultraviolet absorbers in the surface protective layer and the thickness of the surface protective layer. For example, by making the surface protective layer contain the first to third ultraviolet absorbers respectively, the absorbance can be easily adjusted.

[0115] In one embodiment, the absorbance of the surface protective layer in the wavelength region of 270 nm to 370 nm contains a maximum value in the range of 300 nm to 340 nm. This, for example, tends to further improve the long-term weather resistance of the decorative sheet.

[0116] The absorbance values ​​were measured as follows. Absorbance A1 was defined as the average absorbance of the surface protective layer according to JIS K0115:2004 at wavelengths between 270 nm and 300 nm. This average value was obtained by measuring absorbance every 1 nm for wavelengths between 270 nm and 300 nm. Absorbance A2 was defined as the average absorbance of the surface protective layer according to JIS K0115:2004 at wavelengths between 310 nm and 330 nm. This average value was obtained by measuring absorbance every 1 nm for wavelengths between 310 nm and 330 nm. Absorbance A3 was defined as the average absorbance of the surface protective layer according to JIS K0115:2004 at wavelengths between 340 nm and 370 nm. This average value was obtained by measuring absorbance every 1 nm for wavelengths between 340 nm and 370 nm.

[0117] The absorbance of the surface protective layer included in the decorative sheet can be measured by the following method. A decorative sheet having a substrate layer, a decorative layer, a transparent resin layer, and a surface protective layer in sequence is separated into a laminated portion containing the substrate layer and the decorative layer, and a laminated portion containing the transparent resin layer and the surface protective layer. The absorbance of the laminated portion containing the transparent resin layer and the surface protective layer is measured. Then, the surface protective layer of the laminated portion is removed using a solvent or the like, and the absorbance of the remaining portion is measured. The absorbance of the surface protective layer is obtained by subtracting the absorbance of the remaining portion from the absorbance of the laminated portion.

[0118] In the decorative sheet of the present invention, the absorbance A4 of the laminated portion comprising a transparent resin layer and a surface protective layer is preferably 0.2 or higher in the wavelength region of 280 nm to 350 nm. This further improves the long-term weather resistance of the decorative sheet. When the decorative sheet further comprises a base coating layer, the laminated portion comprises a transparent resin layer, a base coating layer, and a surface protective layer. The absorbance A4 may be, for example, 1.0 or higher, 2.0 or higher, 3.0 or higher, or 3.5 or higher. There is no particular limitation on the upper limit of the absorbance A4; for example, it may be 5.0.

[0119] The average absorbance of the above-mentioned laminated portion according to JIS K0115:2004 at wavelengths of 280 nm to 350 nm is set as absorbance A4. This average value is the average value of absorbance measured every 1 nm for wavelengths of 280 nm to 350 nm.

[0120] In one embodiment, the surface protective layer may be formed by: preparing a curable composition, coating the composition onto a transparent resin layer or a primer layer to form an uncured resin layer, and then cross-linking and curing the uncured resin layer. The form of cross-linking and curing may be, for example, curing by heat treatment when using a thermosetting resin, or curing by irradiation with ionizing radiation such as an electron beam or ultraviolet light when using an ionizing radiation-curing compound.

[0121] When using an electron beam as ionizing radiation, the radiation dose is, for example, 5 kGy or more and 300 kGy or less (0.5 Mrad or more and 30 Mrad or less), preferably 10 kGy or more and 100 kGy or less (1 Mrad or more and 10 Mrad or less). When using ultraviolet light as ionizing radiation, light containing ultraviolet rays with wavelengths of 190 nm or more and 380 nm or less may be emitted.

[0122] From the viewpoint of the balance between processability, scratch resistance and weather resistance, the thickness of the surface protective layer is preferably 1 μm or more, more preferably 1.5 μm or more, and even more preferably 2 μm or more, and preferably 20 μm or less, more preferably 15 μm or less, and even more preferably 10 μm or less, for example, 1 μm or more and 20 μm or less.

[0123] The decorative sheet of the present invention may also have a base coating layer between the transparent resin layer and the surface protective layer. The base coating layer may be provided as needed for purposes such as improving the adhesion between the transparent resin layer and the surface protective layer.

[0124] In one embodiment, the base coating contains a resin component. Examples of resin components include: vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-(meth)acrylic acid copolymer, chlorinated polyethylene, chlorinated polypropylene, urethane-(meth)acrylic acid copolymer, (meth)acrylic resin, (meth)acrylic polyol resin, polystyrene, polyurethane, polyester, polyamide, butyraldehyde resin, nitrocellulose, and cellulose acetate. The resin component may also be a cross-linked cured product of such resins obtained using a curing agent. For example, the resin component may be a cured product of the above-mentioned two-component curable urethane resin.

[0125] The primer layer may also contain ultraviolet absorbers such as the first to third ultraviolet absorbers mentioned above. The primer layer may also contain the light stabilizers mentioned above. The primer layer may also contain the additives mentioned above.

[0126] When the base coating contains an ultraviolet absorber, the content of the ultraviolet absorber in the base coating may be more than 1 part by mass, more than 5 parts by mass, more than 7 parts by mass, or less than 40 parts by mass, less than 30 parts by mass, or less than 25 parts by mass, for example, more than 1 part by mass and less than 40 parts by mass.

[0127] When the base coating contains a light stabilizer, the content of the light stabilizer in the base coating may be 0.1 parts by mass or more, or 0.5 parts by mass or more, or 1 part by mass or more, or 10 parts by mass or less, or 8 parts by mass or less, or 6 parts by mass or less, for example, 0.1 parts by mass or more and 10 parts by mass or less.

[0128] The thickness of the base coating is preferably 0.1 μm or more, more preferably 0.5 μm or more, and even more preferably 1 μm or more, and preferably 10 μm or less, more preferably 8 μm or less, and even more preferably 6 μm or less, for example, 0.1 μm or more and 10 μm or less.

[0129] The decorative sheet of the present invention may also have a first adhesive layer between the substrate layer and the transparent resin layer to improve the adhesion between the two layers. For example, the decorative sheet of the present invention may have a decorative layer, a first adhesive layer and a transparent resin layer in sequence from one side near the substrate layer, and may also have a first adhesive layer, a decorative layer and a transparent resin layer in sequence from one side near the substrate layer.

[0130] The first adhesive layer is, for example, composed of an adhesive. Examples of adhesives include: urethane resin adhesives, (meth)acrylic resin adhesives, epoxy resin adhesives, and rubber adhesives. Among these adhesives, urethane resin adhesives are preferred from the viewpoint of adhesion strength.

[0131] As an adhesive for urethane resin systems, an example of an adhesive using a two-component curing urethane resin can be cited. This two-component curing urethane resin includes various polyol compounds such as polyether polyol, polyester polyol and (meth)acrylic polyol, and curing agents such as the aforementioned various isocyanate compounds.

[0132] The thickness of the first bonding layer is preferably 0.1 μm or more, more preferably 1 μm or more, and even more preferably 2 μm or more, and preferably 30 μm or less, more preferably 15 μm or less, and even more preferably 10 μm or less, for example, 0.1 μm or more and 30 μm or less.

[0133] The decorative sheet of the present invention may also have a second adhesive layer on the side opposite to the decorative layer side of the substrate layer. The second adhesive layer is provided as needed for the purpose of improving the adhesion to the outer covering material of the attached body.

[0134] The second adhesive layer is, for example, composed of an adhesive. Examples of adhesives include: (meth)acrylic resins, (meth)acrylic modified polyolefins, chlorinated polyolefins, vinyl chloride resins, vinyl acetate resins, vinyl chloride-vinyl acetate copolymers, styrene-(meth)acrylic copolymers, polyesters, polyurethanes, and polyamides. Two-component curing polyurethane adhesives or polyester adhesives using isocyanate compounds as curing agents can also be used. Examples of adhesives include: (meth)acrylic, urethane, polysiloxane, or rubber-based adhesives (pressure-sensitive adhesives).

[0135] From the viewpoint of obtaining excellent adhesion, the thickness of the second adhesive layer is preferably 1 μm or more, more preferably 5 μm or more, and even more preferably 10 μm or more, and preferably 100 μm or less, more preferably 50 μm or less, and even more preferably 30 μm or less, for example, 1 μm or more and 100 μm or less.

[0136] The decorative sheet of the present invention may also have raised or recessed areas formed by embossing or the like. For example, the sheet may be heated to a temperature preferably 80°C or higher and 260°C or lower, more preferably 100°C or higher and 220°C or lower, and even more preferably 120°C or higher and 200°C or lower, and an embossing plate may be placed on the sheet and pressed to perform embossing. The area pressed by the embossing plate is preferably the protective layer side of the sheet surface.

[0137] The decorative material of the present invention comprises an outer casing and a decorative sheet of the present invention disposed on at least a portion of the surface of the outer casing. The decorative material may also have an adhesive layer between the outer casing and the decorative sheet. The adhesive layer is, for example, composed of an adhesive as described for the second adhesive layer. The decorative sheet may also include a second adhesive layer. The decorative material is obtained, for example, by laminating the surface of the outer casing to be decorated with the substrate layer side of the decorative sheet facing each other.

[0138] FIG2 shows a schematic cross-sectional view of one embodiment of the decorative material of the present invention. The decorative material 2 sequentially comprises an outer covering 60, an adhesive layer 70, and a decorative sheet 1. The decorative sheet 1 is arranged such that its substrate layer 10 faces the outer covering 60. In the decorative material 2, the surface protective layer 50 constitutes the outermost layer. Alternatively, the adhesive layer 70 may be omitted, and the decorative sheet 1 may have a second adhesive layer (not shown).

[0139] The decorative material of the present invention is obtained, for example, by disposing the decorative sheet of the present invention on the surface of an outer covering material. In one embodiment, the sheet is attached to the outer covering material in such a way that the second adhesive layer of the decorative sheet of the present invention is in contact with the surface of the outer covering material. In another embodiment, the sheet is attached to the outer covering material via the adhesive layer such that the substrate layer of the decorative sheet of the present invention faces the surface of the outer covering material. Attachment can be performed under heat and pressure.

[0140] Exterior materials are molded bodies used outdoors, such as those requiring weather resistance due to daily exposure to direct sunlight. The decorative sheet of this invention is suitable for exterior material applications due to its excellent weather resistance. The shape of the exterior material is not particularly limited; examples include: flat and curved panels, three-dimensional articles, sheets, or films. Examples of exterior materials include: resin components, wooden components, and non-mechanical components.

[0141] As a resin component, examples include sheets, plates or three-dimensional articles made of polyolefins, vinyl chloride resins, styrene resins, (meth)acrylic resins, polyesters, polycarbonates, polyamides, polyimides, cellulose resins, phenolic resins, rubber, etc.

[0142] Examples of wood-based components include: boards or three-dimensional articles made of wood fiberboard such as wood veneer, wood plywood, particleboard, medium-density fiberboard (MDF), and engineered wood. In one embodiment, the decorative material is a decorative panel whose outer cladding material is a wood-based component.

[0143] Examples of non-mechanical components include: metal components and other non-mechanical components. Examples of metal components include: sheets, plates, or three-dimensional articles made of iron, aluminum, copper, tin, titanium, or alloys containing at least one of these metals (e.g., carbon steel, stainless steel, duralumin, brass, and bronze). Examples of other non-mechanical components include: plates or three-dimensional articles made of glass, ceramics, gypsum, or lightweight aerated concrete (ALC) panels.

[0144] Examples of exterior materials include: exterior materials for building structures, vehicles, ships and aircraft, and industrial machinery. Examples of exterior materials for building structures include: exterior walls, roofs, eaves, ceilings, floors, fences, entrance doors and door panels, various doors and windows, handrails, balcony partitions, roof components for balconies or carports, agricultural buildings, and soundproof walls or windbreaks for general roads and highways. Examples of exterior materials for vehicles include: window materials such as side windows, rear windows, skylights, front windows and triangular windows; headlight covers, turn signal (winker lamp) lenses, reflectors; and pillars. Examples of vehicles include: automobiles, railway vehicles, construction machinery, and golf carts.

[0145] The thickness of the outer material can be appropriately selected according to the purpose and material. In one embodiment, it can be 0.1 mm or more, 0.3 mm or more, 0.5 mm or more, and 10 mm or less, 5 mm or less, or 3 mm or less. For example, it can be 0.1 mm or more and 10 mm or less.

[0146] The present invention relates, for example, to the following [1] to

[14] . [1] A decorative sheet for exterior decoration, comprising, in sequence, a substrate layer, a decorative layer, a transparent resin layer, and a surface protective layer, wherein the substrate layer contains a polyolefin, the transparent resin layer contains a polyolefin, and the surface protective layer contains a hardened resin, a first ultraviolet absorber having an absorption peak at a first wavelength, a second ultraviolet absorber having an absorption peak at a second wavelength longer than the first wavelength, and a third ultraviolet absorber having an absorption peak at a third wavelength longer than the second wavelength. [2] In the decorative sheet described in [1] above, the difference between the second wavelength and the first wavelength is 10 nm or more, and the difference between the third wavelength and the second wavelength is 10 nm or more. [3] In the decorative sheet described in [1] or [2] above, the second wavelength is in the range of 310 nm or more and 330 nm or less. [4] The decorative sheet described in any one of [1] to [3] above, wherein the first wavelength is in the range of 270 nm to 300 nm. [5] The decorative sheet described in any one of [1] to [4] above, wherein the third wavelength is in the range of 340 nm to 370 nm. [6] The decorative sheet described in any one of [1] to [5] above, wherein in the surface protective layer, the content of the second ultraviolet absorber is greater than the content of the first ultraviolet absorber and greater than the content of the third ultraviolet absorber. [7] The decorative sheet described in any one of [1] to [6] above, wherein the first ultraviolet absorber, the second ultraviolet absorber and the third ultraviolet absorber are each independently a trichloromethane ultraviolet absorber. [8] The decorative sheet described in any one of [1] to [7] above, wherein, relative to 100 parts by mass of the hardened resin contained in the surface protective layer, the surface protective layer contains a total of 0.5 parts by mass and 10 parts by mass of a first ultraviolet absorber, a second ultraviolet absorber, and a third ultraviolet absorber. [9] The decorative sheet described in any one of [1] to [8] above, wherein, relative to 100 parts by mass of the hardened resin contained in the surface protective layer, the surface protective layer contains 0.1 parts by mass and 3 parts by mass of a first ultraviolet absorber, 0.1 parts by mass and 8 parts by mass of a second ultraviolet absorber, and 0.1 parts by mass and 3 parts by mass of a third ultraviolet absorber.

[10] The decorative sheet described in any one of [1] to [9] above, further comprising a base layer between the transparent resin layer and the surface protective layer.

[11] The decorative sheet described in

[10] above, wherein the base layer contains an ultraviolet absorber.

[12] The decorative sheet described in any one of [1] to

[11] above, wherein the transparent resin layer contains an ultraviolet absorber.

[13] The decorative sheet described in any one of [1] to

[12] above, wherein the laminated portion comprising the transparent resin layer and the surface protective layer has an absorbance A4 of 0.2 or more in the wavelength region of 280 nm to 350 nm.

[14] A decorative material comprising an outer cladding material and a decorative piece disposed on the surface of at least a portion of the outer cladding material as described in any one of [1] to

[13] above. [Example].

[0147] Hereinafter, the decorative sheet of the present invention will be described in more detail based on the embodiments, but the decorative sheet of the present invention is not limited to any of the embodiments.

[0148] [Example 1] As a substrate, a 60 μm thick polypropylene sheet was prepared, both sides of which were treated with corona discharge. On one side of the substrate, a printing ink containing a two-component curable acrylate-urethane resin and a colorant was coated by gravure printing to form a 3 μm thick wood grain decorative layer. On the other side of the substrate, a resin composition containing a two-component curable urethane-nitrocellulose mixed resin (containing 5 parts by weight of hexamethylene diisocyanate as a curing agent relative to 100 parts by weight of the resin) was coated to form a 3 μm thick back undercoat.

[0149] A transparent urethane resin adhesive is applied to the decorative layer and dried to form an adhesive layer with a thickness of 3 μm. On the adhesive layer, transparent polypropylene is heated and melted and extruded using a T-die extruder to form a transparent resin layer with a thickness of 80 μm.

[0150] A resin composition for a base coating is prepared by mixing 100 parts by weight of a mixture comprising a polycarbonate-based urethane-acrylic acid copolymer and an acrylic polyol, 5 parts by weight of hexamethylene diisocyanate as a curing agent, 20 parts by weight of an ultraviolet absorber, and a diluent. After corona discharge treatment of the surface of the transparent resin layer, the resin composition for the base coating is applied to the treated surface by gravure printing and dried to form a base coating with a thickness of 4 μm.

[0151] An uncured resin layer is formed by coating the base layer with the following free radiation curable resin composition, and the uncured resin layer is cured by irradiating with an electron beam (accelerating voltage: 165 kV, irradiation line dose: 5 Mrad (50 kGy)) to form a surface protective layer with a thickness of 5 μm.

[0152] <Free Radiation Curable Resin Composition> ・100 parts by weight of trifunctional amino carbamate acrylate oligomer with a weight average molecular weight of 4,000・0.5 parts by weight of first UV absorber: hydroxyphenyl triterpenoid UV absorber, trade name: Adekastab LA-46, ADEKA Corporation, absorption peak wavelength: 275 nm・3 parts by weight of second UV absorber: hydroxyphenyl triterpenoid UV absorber, trade name: TINUVIN479, BASF Corporation, absorption peak wavelength: 322 nm・0.5 parts by weight of third UV absorber: hydroxyphenyl triterpenoid UV absorber, trade name: TINUVIN477, BASF Corporation, absorption peak wavelength: 356 nm • 3 parts by weight of hindered amine non-reactive light stabilizer, trade name: TINUVIN123, BASF Corporation, bis(1-octyloxy-2,2,6,6-tetramethyl-4-piperidinyl) sebacate. • 1.5 parts by weight of hindered amine reactive light stabilizer, trade name: SANOL LS-3410, Nippon Emulsifier Co., Ltd., 1,2,2,6,6-pentamethyl-4-piperidinyl methacrylate.

[0153] The decorative piece is obtained by means of the above method.

[0154] [Comparative Example 1] In the free radiation curable resin composition, the first ultraviolet absorber was not formulated, the amount of the second ultraviolet absorber (TINUVIN479) was changed to 1 part by mass, the amount of the third ultraviolet absorber (TINUVIN477) was changed to 3 parts by mass, and the hindered amine reactive light stabilizer was not formulated. Otherwise, the decorative sheet was obtained in the same manner as in Example 1.

[0155] [Absorbance] Test pieces were prepared by forming a surface protective layer on a polyethylene terephthalate (PET) film under the same conditions as described above. The absorbance of the test pieces in each wavelength region was measured using a UV-Vis-NIR spectrophotometer (manufactured by Hitachi, Ltd., trade name: UH-4150) according to JIS K0115:2004. The absorbance of the PET film was subtracted from this absorbance to obtain the aforementioned "Absorbance A1", "Absorbance A2", and "Absorbance A3".

[0156] Under the same conditions as described above, a test piece was prepared by forming a transparent resin layer, a base layer, and a surface protective layer on a polyethylene terephthalate (PET) film. The absorbance of the test piece was measured using a UV-Vis-NIR spectrophotometer (manufactured by Hitachi, Ltd., trade name: UH-4150) according to JIS K0115:2004. The absorbance of the PET film was subtracted from this absorbance to obtain the aforementioned "absorbance A4".

[0157] The absorbance values ​​of Example 1 are shown below. Absorbance A1: 0.9 Absorbance A2: 1.6 Absorbance A3: 0.5 Absorbance A4: 3.6

[0158] The absorbance values ​​of Comparative Example 1 are shown below. Absorbance A1: 0.3 Absorbance A2: 0.8 Absorbance A3: 0.7 Absorbance A4: 3.3

[0159] [Weather Resistance] The decorative sheets obtained in the Examples and Comparative Examples were subjected to a 1400-hour accelerated weather resistance test using the ultra-accelerated weather resistance testing apparatus described below (the test is as follows: after irradiation with ultraviolet light for 20 hours under the following irradiation conditions, condensation was carried out for 4 hours under the following condensation conditions; this step is considered as one cycle, and the cycle is repeated). After 1400 hours, the appearance of the decorative sheets was visually evaluated according to the following criteria.

[0160] <Ultra-Accelerated Weathering Test Apparatus> An ultra-accelerated weathering test apparatus (product name: Eye Super UV Tester SUV-W261, manufactured by Iwasaki Electric Co., Ltd.) consisting of a UV lamp (product name: M04-L21WB / SUV, manufactured by Iwasaki Electric Co., Ltd.), a lamp cover (product name: WJ50-SUV, manufactured by Iwasaki Electric Co., Ltd.), and an illuminometer (product name: UVD-365PD, manufactured by Iwasaki Electric Co., Ltd.) <Irradiation Conditions> ・Black panel temperature: 63℃ ・Illuminance: 100 mW / cm² ・Humidity inside the tank: 50%RH ・Time: 20 hours <Condensation Conditions> ・Illuminance: 0 mW / cm² ・Humidity inside the tank: 98%RH ・Time: 4 hours

[0161] <Evaluation Criteria> A: No overall appearance change was observed in the decorative sheet. B: Slight whitening was observed in the appearance of the decorative sheet, but no color change was observed in the transparent resin layer and / or substrate layer. C: Slight whitening was observed in the appearance of the decorative sheet, and a slight color change was observed in the transparent resin layer and / or substrate layer. D: Obvious whitening was observed in the appearance of the decorative sheet, and a significant color change was observed in the transparent resin layer and / or substrate layer.

[0162] The evaluation results of the decorative sheets obtained in the examples and comparative examples are shown below. • Example 1: A • Comparative Example 1: C

[0163] As industry practitioners should understand, the decorative pieces of the present invention are not limited to the descriptions of the above embodiments. The above embodiments and specifications are only used to illustrate the principles of the present invention. As long as they do not depart from the spirit and scope of the present invention, various changes or improvements can be made, and such changes or improvements are all included within the scope of protection of the present invention. Furthermore, the scope of protection of the present invention includes not only the descriptions in the patent application but also their equivalents. [Simplified Explanation of the Diagram]

[0010] Figure 1 is a schematic cross-sectional view showing one embodiment of the decorative sheet of the present invention. Figure 2 is a schematic cross-sectional view showing one embodiment of the decorative material of the present invention.

Claims

1. A decorative sheet for exterior decoration, comprising, in sequence, a substrate layer, a decorative layer, a transparent resin layer, and a surface protective layer, wherein the substrate layer contains a polyolefin, the transparent resin layer contains a polyolefin, and the surface protective layer contains a hardened resin, a first ultraviolet absorber having an absorption peak at a first wavelength, a second ultraviolet absorber having an absorption peak at a second wavelength longer than the first wavelength, and a third ultraviolet absorber having an absorption peak at a third wavelength longer than the second wavelength, wherein the difference between the second wavelength and the first wavelength is 10 nm or more, the difference between the third wavelength and the second wavelength is 10 nm or more, the second wavelength is in the range of 310 nm to 330 nm, and the content of the second ultraviolet absorber in the surface protective layer is greater than the content of the first ultraviolet absorber and greater than the content of the third ultraviolet absorber.

2. The decorative sheet as claimed in claim 1, wherein the first wavelength is in the range of 270 nm to 300 nm.

3. The decorative sheet as claimed in claim 1, wherein the third wavelength is in the range of 340 nm to 370 nm.

4. The decorative sheet as claimed in claim 1, wherein the first ultraviolet absorber, the second ultraviolet absorber and the third ultraviolet absorber are each independently a trichloromethane ultraviolet absorber.

5. The decorative sheet of claim 1, wherein, relative to 100 parts by mass of the hardened resin contained in the surface protective layer, the surface protective layer contains a total of 0.5 to 10 parts by mass of the first ultraviolet absorber, the second ultraviolet absorber, and the third ultraviolet absorber.

6. The decorative sheet of claim 1, wherein, relative to 100 parts by weight of the hardened resin contained in the surface protective layer, the surface protective layer contains 0.1 to 3 parts by weight of the first ultraviolet absorber, 0.1 to 8 parts by weight of the second ultraviolet absorber, and 0.1 to 3 parts by weight of the third ultraviolet absorber.

7. The decorative sheet of claim 1, wherein a base coating layer is further provided between the transparent resin layer and the surface protective layer.

8. The decorative sheet as claimed in claim 7, wherein the aforementioned base coating contains an ultraviolet absorber.

9. The decorative sheet of claim 1, wherein the aforementioned transparent resin layer contains an ultraviolet absorber.

10. The decorative sheet of claim 1, wherein the laminated portion comprising the above-mentioned transparent resin layer and the above-mentioned surface protective layer has an absorbance A4 of 0.2 or more in the wavelength region of 280 nm to 350 nm.

11. A decorative material comprising an outer cladding material and a decorative piece disposed on the surface of at least a portion of the outer cladding material, as claimed in any one of claims 1 to 10.

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