Laminated Sheet and Method for Evaluating Weather Resistance of Laminated Sheet

Abstract

To provide a laminated sheet which can shorten weather resistance evaluation time capable of shortening time required for weather resistance evaluation, and a weather resistance evaluation method for the laminated sheet.SOLUTION: In a laminated sheet 10, when an ultraviolet irradiation test is performed on the laminated sheet 10 from the side of a surface protective layer 15 using a metal halide lamp for 250 hours, and surface side Martens hardness (N / mm2) at a surface side measurement position E1 set in a region on the side of the surface protective layer 15 in a thickness direction of a transparent resin layer 14 and back face side Martens hardness (N / mm2) at a back face side measurement position E2 set in a region on the side of a base material sheet 11 in the thickness direction of the transparent resin layer 14 are measured before and after the irradiation test, a change rate before and after the irradiation test of a ratio (A1 / A2) of the surface side Martens hardness (A1) to the back face side Martens harness (A2) is 10% or less.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a laminated sheet and a method for evaluating the weather resistance of the laminated sheet.

Background Art

[0002] Conventionally, laminated sheets used for exterior building materials by bonding to wooden boards, inorganic boards, metal plates, etc. are known. Since the laminated sheets used for the exterior of buildings are exposed to ultraviolet rays and wind and rain outdoors, improving weather resistance has become a major issue. In order to improve weather resistance, it is generally known to add an ultraviolet absorber or a radical scavenger (light stabilizer) to the outermost layer of the laminated sheet (for example, Patent Documents 1 to 4).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0004] When abnormalities such as whitening occur on the surface of a laminated sheet used outdoors, the weather resistance decreases due to the occurrence location of the abnormality being exposed to ultraviolet rays and wind and rain, and the deterioration is accelerated. That is, as the weather resistance of the laminated sheet decreases, the deterioration of the building exterior occurs. In recent years, long-term warranties for buildings (e.g., houses) have been becoming common sense, and as part of this, the needs regarding the quality assurance of laminated sheets used as exterior building materials have also been increasing. Therefore, as a weather resistance evaluation, for example, it is required to preliminarily evaluate whether the weather resistance of the laminated sheet is maintained without degradation during a period corresponding to the warranty period. In conventional laminated sheets, the weather resistance has been evaluated by visually observing the change over time of the surface due to ultraviolet irradiation. However, such an evaluation method has a problem in that it requires a very long time of several thousand hours as the time (evaluation time) to derive the evaluation result.

[0005] Therefore, in view of such problems, an object of the present invention is to provide a laminated sheet capable of shortening the time related to weather resistance evaluation and a method for evaluating the weather resistance of the laminated sheet.

[0006] In order to solve the above problems, a laminated sheet according to an aspect of the present invention is a laminated sheet in which a printing layer is provided on a base sheet, and at least a transparent resin layer and a surface protection layer are laminated in this order on the printing layer. When irradiance is 65 mW / cm 2 on the laminated sheet from the surface protection layer side with an integrated light meter having a sensitivity wavelength range of 310 nm or more and 390 nm or less, a black panel temperature is 63°C, and a tank humidity is 50%, an ultraviolet irradiation test is performed using a metal halide lamp for 250 hours, and before and after the irradiation test, the surface side Martens hardness (N / mm 2 ) at a surface side measurement position set in a region on the surface protection layer side in the thickness direction of the transparent resin layer and the back side Martens hardness (N / mm 2 ) at a back side measurement position set in a region on the base sheet side in the thickness direction of the transparent resin layer are measured, the ratio (A1 / A2) of the surface side Martens hardness (A1) to the back side Martens hardness (A2) has a change rate of 10% or less before and after the irradiation test, and the back side measurement position and the back side measurement position are set in regions in the transparent resin layer that are not affected by other layers when measuring the surface side Martens hardness and the back side Martens hardness.

[0007] In order to solve the above problems, a laminated sheet according to another aspect of the present invention is a laminated sheet having a printing layer provided on a base material sheet, and at least a transparent resin layer and a surface protection layer laminated in this order on the printing layer, wherein the transparent resin layer has a Martens hardness of 30 N / mm 2 or less, and at least one of the transparent resin layer and the surface protection layer contains a hindered amine light stabilizer.

[0008] Further, in order to solve the above problems, a weather resistance evaluation method according to one aspect of the present invention is a weather resistance evaluation method of a laminated sheet having a printing layer provided on a base material sheet, and at least a transparent resin layer and a surface protection layer laminated in this order on the printing layer, wherein from the surface protection layer side which is the outermost surface of the laminated sheet, an integrated light meter with a sensitivity wavelength range of 310 nm or more and 390 nm or less is used to irradiate the laminated sheet with an illuminance of 65 mW / cm 2 , a UV irradiation step of performing a 250-hour UV irradiation test using a metal halide lamp under the conditions of a black panel temperature of 63°C and a tank humidity of 50%, and before and after the UV irradiation test, the surface-side Martens hardness (N / mm 2 ) at the surface-side measurement position set in the region on the surface protection layer side in the thickness direction of the transparent resin layer, and the back-side Martens hardness (N / mm 2 ) at the back-side measurement position set in the region on the base material sheet side in the thickness direction of the transparent resin layer are measured, and an evaluation step of evaluating the weather resistance based on whether or not the change rate of the ratio (A1 / A2) of the surface-side Martens hardness (A1) to the back-side Martens hardness (A2) before and after the irradiation test is 10% or less, wherein the surface-side measurement position and the back-side measurement position are set in regions of the transparent resin layer that are not affected by other layers when measuring the surface-side Martens hardness and the back-side Martens hardness.

Advantages of the Invention

[0009] According to the present invention, it is possible to provide a laminated sheet capable of shortening the time related to weather resistance evaluation and a weather resistance evaluation method for the laminated sheet.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Modes for Carrying Out the Invention

[0011] Hereinafter, the present disclosure will be described through embodiments. However, the following embodiments do not limit the invention according to the claims. Also, not all combinations of features described in the embodiments are essential for the solution means of the invention. Further, the drawings schematically show the invention according to the claims, and dimensions such as the width and thickness of each part are different from the actual ones, and these ratios are also different from the actual ones.

[0012] The laminated sheet according to the first embodiment of the present disclosure will be described. The laminated sheet according to the present disclosure is, for example, a laminated sheet applied to fittings for building exteriors. In the following description, the substrate sheet side in contact with the pasting surface of the laminated sheet may be referred to as "down", and the side opposite to the side in contact with the pasting surface of the laminated sheet (surface) may be referred to as "up". Hereinafter, each aspect of each embodiment of the present disclosure will be described with reference to the drawings.

[0013] 1. First Embodiment (1.1) Basic Configuration of the Laminated Sheet FIG. 1 is a schematic view showing a cross section of the laminated sheet 10 according to the present embodiment, which is a view of the cross section as seen from the front. As shown in FIG. 1, the laminated sheet 10 according to the first embodiment (hereinafter, the present embodiment) of the present invention includes a base material sheet 11, a printing layer 12, an anchor layer 13, a transparent resin layer 14, and a surface protection layer 15, which are laminated in this order. Hereinafter, the configurations of the above-described respective layers will be described. The laminated sheet 10 according to the present embodiment may be a laminated sheet in which the printing layer 12 is provided on the base material sheet 11, and at least the transparent resin layer 14 and the surface protection layer 15 are laminated in this order on the printing layer 12. Therefore, in the laminated sheet 10, the formation of the anchor layer 13 may be omitted.

[0014] (Base material sheet 11) As the material of the base sheet 11, for example, a thermoplastic resin can be used. There is no particular limitation on the thermoplastic resin, and the same ones as those used for the base material in conventional cosmetic sheets can be used. For example, polyolefin resins such as polyethylene, polypropylene, polymethylpentene, polybutene, ethylene-propylene copolymer, ethylene-α-olefin copolymer, propylene-α-olefin copolymer, etc., and olefin-based copolymer resins such as ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, ethylene-(meth)acrylic acid (ester) copolymer, ethylene-unsaturated carboxylic acid copolymer metal neutralized product (ionomer), etc., polyester resins such as polyethylene terephthalate, polybutylene terephthalate, polytetramethylene terephthalate, polyethylene naphthalate, polyethylene terephthalate-isophthalate copolymer, 1,4-cyclohexanedimethanol copolymerized polyethylene terephthalate, polyarylate, polycarbonate, etc., acrylic resins such as poly(meth)acrylonitrile, polymethyl(meth)acrylate, polyethyl(meth)acrylate, polybutyl(meth)acrylate, polyacrylamide, etc., polyamide resins such as 6-nylon, 6,6-nylon, 6,10-nylon, etc., styrene resins such as polystyrene, AS resin, ABS resin, etc., vinyl resins such as polyvinyl chloride, polyvinyl acetate, polyvinyl alcohol, polyvinyl acetal, polyvinyl butyral, etc., fluorine-based resins such as polyvinyl fluoride, polyvinylidene fluoride, polytetrafluoroethylene, ethylene-tetrafluoroethylene copolymer, ethylene-perfluoroalkyl vinyl ether copolymer, etc., or a mixture, copolymer, composite, laminate, etc. of two or more of them can be used.

[0015] Here, although a number of thermoplastic resins were listed as the thermoplastic resin that can be used for the base sheet 11, in view of the increasing social concern about environmental problems in recent years, it is not desirable to use a thermoplastic resin containing chlorine (halogen) such as polyvinyl chloride resin, and it is desirable to use a non-halogen-based thermoplastic resin. In particular, from the aspects of various physical properties, processability, versatility, economy, etc., it is most desirable to use a polyolefin-based resin or a polyester-based resin (amorphous or biaxially stretched) as the non-halogen-based thermoplastic resin.

[0016] As the polyolefin-based resin, it may be appropriately selected and used from the many types already listed according to the purpose of use of the laminated sheet 10 and the like. In particular, the most suitable for general applications is a polypropylene-based resin, that is, a homopolymer or copolymer having propylene as the main component. For example, homopolypropylene resin, random polypropylene resin, block polypropylene resin, etc. can be used alone or in appropriate combinations, or resins obtained by further appropriately blending atactic polypropylene with them can be used. Also, a copolymer containing an olefin-based monomer other than propylene may be used. For example, a propylene-α-olefin copolymer having a polypropylene crystal part and containing 15 mol% or more of one or more comonomers of α-olefins having 2 to 20 carbon atoms other than propylene, preferably ethylene, butene-1, 4-methylpentene-1, hexene-1 or octene-1 can be exemplified. In addition, modifiers such as low-density polyethylene, ethylene-α-olefin copolymer, ethylene-propylene copolymer rubber, ethylene-propylene-non-conjugated diene copolymer rubber, styrene-butadiene copolymer or its hydrogenated product, which are usually used for softening polypropylene-based resins, can be appropriately added.

[0017] As the base sheet 11, in addition to the above-described thermoplastic resin, those arbitrarily selected from, for example, paper, rubber, non-woven fabric, synthetic paper, metal foil, etc. can be used. Examples of the paper include tissue paper, titanium paper, resin-impregnated paper, etc. Examples of the rubber include ethylene-propylene copolymer rubber, ethylene-propylene-diene copolymer rubber, styrene-butadiene copolymer rubber, styrene-isoprene-styrene block copolymer rubber, styrene-butadiene-styrene block copolymer rubber, polyurethane, etc. As the non-woven fabric, organic or inorganic non-woven fabrics can be used. Examples of the metal of the metal foil include aluminum, iron, gold, silver, etc. In order to supplement the adhesion with the adjacent layer, the base sheet 11 may be subjected to surface treatment such as corona treatment, plasma treatment, ozone treatment, electron beam treatment, ultraviolet treatment, dichromic acid treatment, etc.

[0018] Further, the base sheet 11 in the present embodiment may be an opaque colored olefin-based resin layer (colored thermoplastic resin layer) having concealability. Thereby, when forming the exterior building material by laminating the laminated sheet 10 and a predetermined substrate, for example, the base sheet 11 can conceal the color variation, defects, etc. on the substrate surface. Also, when making use of the texture of the substrate surface, the base sheet 11 may be a colored olefin-based resin layer having a transparency that allows the substrate surface to be seen through.

[0019] (Printing layer 12) The printing layer 12 is a layer that imparts design properties to the laminated sheet 10, and is a layer of pattern printing applied to the base sheet 11 using ink. The printing layer 12 is formed using printing ink, coating agent, or the like. There are no particular restrictions on the printing ink or the like, and the same ones as those conventionally used for the printing layer in decorative sheets can be used. For example, acrylic ink can be used as the printing ink. As the acrylic ink, for example, ink using a two-component curable urethane resin obtained by blending an isocyanate curing agent in an acrylic polyol vehicle as a binder resin can be used. Further, other resin components may be added to the printing layer 12 as necessary. As components other than the binder resin of the printing layer 12, for example, coloring agents such as pigments and dyes, extender pigments, solvents, various additives such as light stabilizers, etc. can be used. Examples of the pigment include condensed azo, insoluble azo, quinacridone, isoindoline, anthraquinone, imidazolone, cobalt, phthalocyanine, carbon, titanium oxide, iron oxide, pearl pigments such as mica, etc.

[0020] The method of providing the printing layer 12 is not particularly limited, and for example, ordinary printing methods such as gravure printing, offset printing, screen printing, flexographic printing, inkjet printing, etc. can be used. Also, as the pattern of the printing layer 12, any pattern can be used, for example, wood grain pattern, stone grain pattern, cloth grain pattern, abstract pattern, geometric pattern, etc., or a combination of two or more of these can be used.

[0021] (Anchor layer 13) The anchor layer (anchor coat layer) 13 is a layer provided to enhance the adhesiveness between the base sheet 11 (lower layer) and the transparent resin layer 14 (upper layer). In this embodiment, the base sheet 11 provided with the printing layer 12 and the transparent resin layer 14 may be joined via the anchor layer 13, and various lamination methods such as thermal lamination, extrusion lamination, dry lamination, and sand lamination can be used as the joining method. Here, considering the various performances of the laminated sheet 10 according to this embodiment, the dry lamination method is preferable as the joining method. For this reason, the anchor layer 13 is preferably a dry lamination adhesive layer using a dry lamination adhesive. Further, the anchor layer 13 is formed, for example, by using ordinary coating methods such as gravure coating, microgravure coating, comma coating, knife coating, and die coating. Note that the configuration of the anchor layer 13 in the laminated sheet 10 is not essential, and the anchor layer 13 may not be provided.

[0022] (Transparent resin layer 14) The transparent resin layer 14 is a layer for improving the weather resistance and durability of the laminated sheet 10. The transparent resin layer 14 is formed, for example, using a polyolefin resin. Examples of the polyolefin resin include polyolefin resins such as polyethylene, polypropylene, polymethylpentene, polybutene, ethylene-propylene copolymer, ethylene-α-olefin copolymer, and propylene-α-olefin copolymer, and olefin-based copolymer resins such as ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, ethylene-(meth)acrylic acid (ester) copolymer, and ethylene-unsaturated carboxylic acid copolymer metal neutralized product (ionomer), or a mixture, copolymer, composite, laminate, etc. of two or more of these. Also, the type of the polyolefin resin constituting the transparent resin layer 14 may be one type or a plurality of types. Among these polyolefin resins, a polypropylene resin can be preferably used as the polyolefin resin constituting the transparent resin layer 14. That is, in the laminated sheet 10 according to this embodiment, the transparent resin layer 14 may be formed of polypropylene.

[0023] In addition, in the laminated sheet 10 according to the present embodiment, the transparent resin layer 14 preferably contains an ultraviolet absorber (Urtra Violet Absorber: UVA) and a light stabilizer as weathering agents in order to improve the weather resistance of the laminated sheet 10.

[0024] The transparent resin layer 14 preferably contains at least a light stabilizer among the weathering agents. As the light stabilizer, a hindered amine light stabilizer (Hindered Amine Light Stabilizers: HALS) which is a light stabilizer using a hindered amine-based compound can be preferably used. That is, the transparent resin layer 14 in the laminated sheet 10 preferably contains HALS. HALS functions as a radical scavenger that captures radicals generated by ultraviolet exposure and suppresses the decomposition of the coating film. Therefore, by the transparent resin layer 14 containing HALS, the weather resistance of the laminated sheet 10 can be improved.

[0025] Furthermore, it is more preferable that the transparent resin layer 14 contains an ultraviolet absorber (UVA) in addition to HALS. The ultraviolet absorber has the effect of suppressing the generation of radicals. By containing HALS and UVA having different functions as weathering agents, a synergistic effect between the radical control effect and the effect of suppressing the generation of radicals can be obtained, and the weather resistance of the laminated sheet 10 can be further improved.

[0026] Examples of the ultraviolet absorber include ultraviolet absorbers such as benzotriazole-based, benzoate-based, benzophenone-based, triazine-based, benzoate-based, and cyanoacrylate-based ultraviolet absorbers. One type of these ultraviolet absorbers may be added to the transparent resin layer 14, or a plurality of types of ultraviolet absorbers may be mixed and added. In the present embodiment, a benzotriazole-based ultraviolet absorber can be preferably used as the ultraviolet absorber added to the transparent resin layer 14.

[0027] The transparent resin layer 14 preferably contains 0.2 parts by mass or more of a light stabilizer (HALS) with respect to the mass of the entire transparent resin layer 14. When the content of the light stabilizer in the transparent resin layer 14 is less than 0.2 parts by mass, sufficient weather resistance may not be obtained. Also, from the viewpoints of cost suppression and maintaining the content ratio of the resin component in the transparent resin layer 14, the content of the light stabilizer in the transparent resin layer 14 is preferably 1 part by mass or less with respect to the mass of the entire transparent resin layer 14.

[0028] Further, the transparent resin layer 14 preferably contains 0.2 parts by mass or more of an ultraviolet absorber (UVA) with respect to the mass of the entire transparent resin layer 14. When the content of the ultraviolet absorber in the transparent resin layer 14 is less than 0.2 parts by mass, sufficient weather resistance may not be obtained. Also, from the viewpoints of preventing the occurrence of bleed and maintaining the content ratio of the resin component in the transparent resin layer 14, the content of the ultraviolet absorber in the transparent resin layer 14 is preferably in the range of 1 part by mass or less with respect to the mass of the entire transparent resin layer 14.

[0029] Thus, in this embodiment, the transparent resin layer 14 is preferably a polypropylene resin composition (polyolefin resin composition) containing at least a light stabilizer, and more preferably a polypropylene resin composition containing a light stabilizer and an ultraviolet absorber. Thereby, excellent weather resistance can be imparted to the laminated sheet 10 used for exterior.

[0030] Also, the thickness of the transparent resin layer 14 is preferably in the range of 40 μm or more and 100 μm or less. When the thickness of the transparent resin layer 14 is less than 40 μm, the weather resistance and scratch resistance may decrease. Also, when the thickness of the transparent resin layer 14 exceeds 100 μm, the manufacturing cost may increase and the flexibility may decrease.

[0031] In addition, various additives such as heat stabilizers, antiblocking agents, catalyst scavengers, colorants, light scattering agents, and gloss modifiers can be added to the transparent resin layer 14 as needed. As heat stabilizers, phenolic, sulfur-based, phosphorus-based, hydrazine-based, etc. are generally added in any combination.

[0032] The method for forming the transparent resin layer 14 is not particularly limited. The transparent resin layer 14 can be formed using ordinary methods such as calender film formation or extrusion film formation. Among them, as the method for forming the transparent resin layer 14, extrusion molding is preferred. With extrusion molding, the transparent resin layer 14 can be uniformly formed into a film. Also, in order to impart design properties, surface irregularities may be provided on the transparent resin layer 14. As the method for providing the irregularities, for example, there are a method of performing thermal embossing after extruding and molding the transparent resin layer 14, and a method of performing embossing simultaneously with extrusion molding using a cooling roll provided with irregularities during extrusion molding.

[0033] (Surface protection layer) The surface protection layer 15 is a layer formed on the transparent resin layer 14, and is a layer provided to impart functions such as weather resistance, scratch resistance, stain resistance, and design properties to the laminated sheet 10. As the material of the surface protective layer 15, for example, considering improving the weather resistance of the surface protective layer 15, a reaction product mainly composed of an acrylic resin composition and using polyisocyanate as a curing agent (hereinafter, also referred to as "isocyanate-cured acrylic resin composition") can be used. As the acrylic resin composition, for example, acrylic polyol can be used. As the acrylic polyol, for example, ordinary acrylic monomers such as methyl acrylate, ethyl acrylate, butyl acrylate, cyclohexyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, cyclohexyl methacrylate, 2-ethylhexyl methacrylate, etc., are combined with monomers containing a hydroxyl group such as 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, etc., and, if necessary, copolymerizable polymerizable monomers such as styrene, α-methylstyrene, vinyltoluene, divinylbenzene, vinyl acetate, vinyl butyrate, vinyl versatate, ethyl vinyl ether, acrylonitrile, methacrylonitrile, etc., and copolymerized to obtain an acrylic polymer compound having a hydroxyl group in the side chain can be adopted.

[0034] Further, as the isocyanate prepolymer of polyisocyanate, for example, considering the weather resistance of the surface protective layer 15, a trimer of hexamethylene diisocyanate can be used. Further, as the side chain of the isocyanate prepolymer, for example, considering imparting flexibility to the surface protective layer 15, a urethane bond can be used.

[0035] In addition, as the material of the surface protective layer 15, for example, considering scratch resistance, weather resistance, and durability, a mixture of a radiation-curable resin and an isocyanate-curable acrylic resin composition can be used. As for scratch resistance, it is preferable that the surface protective layer 15 has a pencil hardness of B or higher in the pencil hardness test according to JIS K 5600. Further, as the radiation-curable resin, for example, a composition mainly composed of at least any one of prepolymers, oligomers, and monomers having a polymerizable unsaturated bond such as a (meth)acryloyl group, which has the property of undergoing a crosslinking reaction upon irradiation with radiation, can be used. As the radiation, for example, an electron beam or ultraviolet rays can be used. Additives such as a polymerization initiator and a sensitizer may be added to the radiation-curable resin as necessary.

[0036] As prepolymers and oligomers having a polymerizable unsaturated bond, for example, melamine (meth)acrylate, epoxy (meth)acrylate, urethane (meth)acrylate, polyester (meth)acrylate, polyether (meth)acrylate, polyol (meth)acrylate, etc. can be used. Further, as monomers, for example, monofunctional monomers such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, cyclohexyl (meth)acrylate, ethylhexyl (meth)acrylate, hydroxyethyl (meth)acrylate, glycidyl (meth)acrylate, etc., bifunctional monomers such as ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, polyethylene glycol diacrylate, propylene glycol diacrylate, butanediol diacrylate, hexanediol diacrylate, etc., and polyfunctional monomers such as trimethylolpropane triacrylate, pentaerythritol tetraacrylate, dipentaerythritol hexaacrylate, etc. can be used.

[0037] As the isocyanate-curing type acrylic resin composition, for example, a reaction product using an acrylic resin composition as the main component and a polyisocyanate as the curing agent can be used. As the acrylic resin composition, for example, an acrylic polyol compound can be adopted. As the acrylic polyol compound, for example, ordinary acrylic monomers such as methyl acrylate, ethyl acrylate, butyl acrylate, cyclohexyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, cyclohexyl methacrylate, 2-ethylhexyl methacrylate, etc., are copolymerized with monomers containing a hydroxyl group such as 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, etc., and, if necessary, copolymerizable polymerizable monomers such as styrene, α-methylstyrene, vinyltoluene, divinylbenzene, vinyl acetate, vinyl butyrate, vinyl versatate, ethyl vinyl ether, acrylonitrile, methacrylonitrile, etc., can be blended and copolymerized to obtain an acrylic polymer compound having a hydroxyl group in the side chain and adopted.

[0038] Also, as the isocyanate prepolymer of polyisocyanate, for example, tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), naphthalene diisocyanate (NDI), xylylene diisocyanate (XDI), hydrogenated diphenylmethane diisocyanate (hydrogenated MDI), hydrogenated xylylene diisocyanate (hydrogenated XDI), hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), etc., can be used. In particular, considering weather resistance, yellowing resistance, and productivity, a trimer of hexamethylene diisocyanate (HDI) can be used. That is, an isocyanurate type using HDI as a raw material, that is, HDI isocyanurate which is a derivative of HDI can be used. Also, as the side chain of the isocyanate prepolymer, for example, considering the imparting of flexibility to the surface protection layer 15, a urethane bond can be used.

[0039] In addition, as the material of the surface protection layer 15, polymethyl (meth)acrylate, polyethyl (meth)acrylate, polybutyl (meth)acrylate, polyacrylamide, etc. may be used as acrylic resins.

[0040] Thus, it is preferable that the surface protection layer 15 in the present embodiment is a layer mainly composed of an acrylic resin. Here, the main component in this specification refers to a resin material contained in 70% by mass or more, preferably 90% by mass or more of the materials constituting the target layer. That is, the surface protection layer 15 is preferably formed of an acrylic resin.

[0041] In addition, it is preferable that the surface protection layer 15 contains at least one of a light stabilizer or an ultraviolet absorber. That is, it is preferable that the surface protection layer 15 is formed of an acrylic resin composition containing at least one of an ultraviolet absorber or a light stabilizer. All of the resin components excluding the light stabilizer and the ultraviolet absorber in the surface protection layer 15 may be composed of an acrylic resin. In the present embodiment, a hindered amine light stabilizer (HALS) can be added as a light stabilizer to the surface protection layer 15 in the same manner as the transparent resin layer 14. Also, the surface protection layer 15 can be added with an ultraviolet absorber such as a benzotriazole-based, benzoate-based, benzophenone-based, triazine-based, benzoate-based, cyanoacrylate-based ultraviolet absorber in the same manner as the ultraviolet absorber contained in the transparent resin layer 14.

[0042] Furthermore, it is more preferable that the surface protection layer 15 contains both a light stabilizer and an ultraviolet absorber (UVA). Thereby, a synergistic effect between the radical control effect and the effect of suppressing the generation of radicals can be obtained, and the weather resistance of the laminated sheet 10 can be further improved.

[0043] The content of the light stabilizer (in this example, HALS) in the surface protective layer 15 is preferably 0.2 parts by mass or more with respect to the mass of the entire surface protective layer 15. When the content of the light stabilizer in the surface protective layer 15 is less than 0.2 parts by mass, sufficient weather resistance may not be obtained. Further, from the viewpoints of cost reduction and maintaining the content ratio of the resin component in the surface protective layer 15, the content of the light stabilizer in the transparent resin layer 14 is preferably 1 part by mass or less with respect to the mass of the entire surface protective layer 15.

[0044] Also, the content of the ultraviolet absorber (UVA) in the surface protective layer 15 is preferably 0.2 parts by mass or more with respect to the mass of the entire surface protective layer 15. When the content of the ultraviolet absorber in the surface protective layer 15 is less than 0.2 parts by mass, sufficient weather resistance may not be obtained. Further, from the viewpoints of preventing the occurrence of bleeding and maintaining the content ratio of the resin component in the surface protective layer 15, the content of the ultraviolet absorber in the transparent resin layer 14 is preferably in the range of 1 part by mass or less with respect to the mass of the entire surface protective layer 15.

[0045] Note that the content of the ultraviolet absorber in the surface protective layer 15 may be more than the content of the ultraviolet absorber in the transparent resin layer 14. Also, the content of the light stabilizer in the surface protective layer 15 may be more than the content of the light stabilizer in the transparent resin layer 14. Also, the light stabilizer and the ultraviolet absorber contained in the surface protective layer 15 may be of the same type as those contained in the transparent resin layer 14, or may be of different types.

[0046] The surface protective layer 15 may be blended with various additives such as, for example, a heat stabilizer, an anti-blocking agent, a catalyst scavenger, a colorant, a light scattering agent, and a gloss modifier, if necessary. The method for forming the surface protective layer 15 is not particularly limited. After applying a liquefied material of the above-mentioned materials by an ordinary method such as gravure coating, microgravure coating, comma coating, knife coating, die coating, etc., the surface protective layer 15 is formed by curing by a method suitable for the material such as heat curing or ultraviolet curing.

[0047] Also, the layer thickness of the surface protective layer 15 is desirably in the range of 3 μm or more and 15 μm or less. If the thickness of the surface protective layer 15 is 3 μm or more, the scratch resistance is improved. If the thickness of the surface protective layer 15 is 15 μm or less, it is not necessary to use an excessive amount of resin material, and the cost can be reduced.

[0048] Also, in the laminated sheet 10 according to the first embodiment of the present invention, an embossed pattern (concavo-convex pattern) may be formed on the surface protective layer 15. By forming an embossed pattern (not shown), any desired concavo-convex shape such as a wood grain conduit can be three-dimensionally formed on the surface protective layer 15. Thereby, a laminated sheet 10 having excellent texture and excellent weather resistance can be produced.

[0049] (Weather resistance evaluation of the laminated sheet 10) Next, with reference to FIGS. 1 and 2, a method for evaluating the weather resistance of the laminated sheet 10 according to the present embodiment will be described. FIG. 2 is a flowchart showing an example of the flow of the weather resistance evaluation method according to the present embodiment.

[0050] The inventor of the present invention has intensively studied the weather resistance evaluation of the laminated sheet used for exterior and the shortening of the evaluation time related thereto, and as a result, has found that it is possible to perform the weather resistance evaluation based on the change in the Martens hardness in the transparent resin layer 14 due to ultraviolet exposure. And, by performing the weather resistance evaluation based on the change in the Martens hardness, the time related to the evaluation was successfully shortened significantly. Hereinafter, an example of the weather resistance evaluation method according to the present embodiment will be specifically described. In the following description, an example in which the weather resistance evaluation according to the weather resistance evaluation method according to the present embodiment is performed on the laminated sheet 10 will be described, but the present invention is not limited thereto, and the weather resistance evaluation may be performed on a sample (sample) in which the surface protective layer 15 is formed on the transparent resin layer 14. In any case, equivalent evaluation results can be obtained.

[0051] (Pre-irradiation hardness measurement step S1) As shown in Fig. 2, in the weather resistance evaluation method of the laminated sheet 10 according to this example, first, in the pre-irradiation hardness measurement step, the Martens hardness (N / mm 2 ) of the transparent resin layer 14 is measured.

[0052] Here, the measurement of the Martens hardness in the transparent resin layer 14 will be described. In the pre-irradiation hardness measurement step, the Martens hardness is measured in two regions in the transparent resin layer 14. In Fig. 1, as two measurement positions in the transparent resin layer 14, the surface-side measurement position E1 and the back-side measurement position E2 are illustrated. The surface-side measurement position E1 is set in the region on the surface protection layer 15 side (surface side) in the thickness direction of the transparent resin layer 14. Also, the back-side measurement position E2 is set in the region on the base material sheet 11 side (back side) in the thickness direction of the transparent resin layer 14.

[0053] Here, the Martens hardness at the surface-side measurement position E1 is defined as the surface-side Martens hardness, and the Martens hardness at the back-side measurement position E2 is defined as the back-side Martens hardness. That is, in the pre-irradiation hardness measurement step, the surface-side Martens hardness at the surface-side measurement position E1 and the back-side Martens hardness at the back-side measurement position E2 are measured.

[0054] As shown in Fig. 1, the surface-side measurement position E1 and the back-side measurement position E2 are located on the cut surface of the transparent resin layer 14 when the laminated sheet 10 is cut in the thickness direction. That is, in the pre-irradiation hardness measurement step S1, when measuring the surface-side Martens hardness and the back-side Martens hardness, a sample of the laminated sheet 10 is cut in the thickness direction to expose the cross section.

[0055] Also, the surface-side measurement position E1 and the back-side measurement position E2 are set in regions in the transparent resin layer 14 that are not affected by other layers when measuring the surface-side Martens hardness and the back-side Martens hardness. Here, the region not affected by other layers refers to, for example, a region where infiltration (bleed, etc.) of components from other layers in contact with the transparent resin layer 14 does not reach. That is, the surface-side measurement position E1 is set in the transparent resin layer 14 in a region that is not affected by infiltration or the like from the surface protection layer 15 during the measurement of the surface-side martensitic hardness. Further, the back-side measurement position E2 is set in the transparent resin layer 14 in a region that is not affected by infiltration or the like from the base material sheet 11 and each layer (printing layer 12, anchor layer 13) provided on the base material sheet 11 during the measurement of the back-side martensitic hardness.

[0056] For example, the surface-side measurement position E1 is preferably set in a region that is 10 μm away from the boundary surface on the surface protection layer 15 side in the thickness direction toward the base material sheet 11 side in the transparent resin layer 14, and the back-side measurement position E2 is preferably set at a position that is 10 μm away from the boundary surface on the base material sheet 11 side in the thickness direction toward the surface protection layer 15 side in the transparent resin layer 14. Thereby, the surface-side martensitic hardness can be reliably measured without being affected by the surface protection layer 15, and the back-side martensitic hardness can be reliably measured without being affected by each layer (printing layer 12 or anchor layer 13) provided on the base material sheet 11.

[0057] Note that the surface-side measurement position E1 and the back-side measurement position E2 shown in FIG. 1 are merely examples, and the surface-side measurement position E1 and the back-side measurement position E2 are not limited to the positions shown in FIG. 1. As described above, the surface-side measurement position E1 and the back-side measurement position E2 may be separated from the boundary surface on the surface protection layer 15 side and the boundary surface on the base material sheet 11 side to such an extent that they are not affected by other layers during the measurement of the martensitic hardness.

[0058] The surface-side martensitic hardness and the back-side martensitic hardness can be measured using a microhardness measuring device. As the microhardness measuring device, for example, "FISCHERSCOPE Hm2000" manufactured by Fischer can be used. The microhardness measuring device measures the surface-side martensitic hardness and the back-side martensitic hardness by using a load parameter in which a load of up to 5 mN is applied for 10 seconds to each of the surface-side measurement position E1 and the back-side measurement position E2, then this is held for 5 seconds, and the load is decreased by applying a load of up to 0.1 mN for 10 seconds.

[0059] The surface-side martensite hardness before the irradiation test is 20 N / mm 2 It is preferably as follows. Thereby, in the state before performing the ultraviolet irradiation, it can be confirmed that the laminated sheet 10 has weather resistance suitable for outdoor use.

[0060] (Ultraviolet irradiation step S2) As shown in FIG. 2, after performing the pre-irradiation hardness measurement step S1, the ultraviolet irradiation step is then performed. In the ultraviolet irradiation step S2, an ultraviolet irradiation test on the laminated sheet 10 is performed.

[0061] Here, the ultraviolet irradiation test in the ultraviolet irradiation step S2 will be specifically described. In the ultraviolet irradiation test of this example, an ultraviolet irradiation test is performed using a metal halide lamp as a light source. The ultraviolet irradiation test using a metal halide lamp can be carried out, for example, using a "Metal Weather Tester (KW-R7TP-A) manufactured by Daipla Wintersteiger Co., Ltd.".

[0062] The conditions of the ultraviolet irradiation test of this example are such that the illuminance in an integrating photometer with a sensitivity wavelength range of 310 nm or more and 390 nm or less is 65 mW / cm 2 , the black panel temperature is 63°C, and the humidity inside the tank is 50%. As the integrating photometer, for example, "Ultraviolet Illuminometer UIT-201: manufactured by Ushio Electric Inc." is used. Under these conditions, from the side of the surface protective layer 15, which is the outermost surface of the laminated sheet 10, an ultraviolet irradiation test on the laminated sheet 10 is performed using a metal halide lamp for 250 hours. Note that the ultraviolet irradiation test is performed on a laminated sheet having the same composition as the laminated sheet 10 used in the above pre-irradiation hardness measurement step S1 and with no exposed cross-section.

[0063] (Post-irradiation hardness measurement step S3) As shown in FIG. 2, after performing the ultraviolet irradiation step S2, the post-irradiation hardness measurement step S3 is then performed. In the post-irradiation hardness measurement step S3, the Martens hardness of the transparent resin layer 14 after the ultraviolet irradiation test is measured. In this step, in the same manner as in the pre-irradiation hardness measurement step S1, the surface-side Martens hardness at the surface-side measurement position E1 and the back-side Martens hardness at the back-side measurement position E2 are measured. Thus, in the weather resistance evaluation method of the laminated sheet 10 according to the present embodiment, the surface-side Martens hardness and the back-side Martens hardness are measured before and after the ultraviolet irradiation test. Note that in the post-irradiation hardness measurement step S3, for the sample of the laminated sheet 10 after performing the ultraviolet irradiation test in the ultraviolet irradiation step S2, the surface-side Martens hardness and the back-side Martens hardness are measured. Further, the pre-irradiation hardness measurement step S1 and the post-irradiation hardness measurement step S3 may be collectively referred to as the "Martens hardness measurement step".

[0064] (Hardness ratio calculation step S4) As shown in FIG. 2, after performing the post-irradiation hardness measurement step S3, the hardness ratio calculation step S4 is then performed. In the hardness ratio calculation step S4, the ratio (A1 / A2) of the surface-side Martens hardness (A1) to the back-side Martens hardness (A2) in the transparent resin layer 14 of the laminated sheet 10 is calculated.

[0065] Specifically, in the hardness ratio calculation step S4, first, the ratio of the surface-side Martens hardness and the back-side Martens hardness measured in the pre-irradiation hardness measurement step S1 is calculated as the pre-irradiation hardness ratio. Further, the ratio of the surface-side Martens hardness and the back-side Martens hardness measured in the post-irradiation hardness measurement step S3 is calculated as the post-irradiation hardness ratio. By calculating the ratio from the values of the Martens hardness measured in the pre-irradiation hardness measurement step S1 and the post-irradiation hardness measurement step S3, the variation in data can be corrected, and the evaluation accuracy based on the Martens hardness can be improved.

[0066] (Hardness ratio change rate calculation step S5) As shown in Fig. 2, after performing the hardness ratio calculation step S4, the hardness ratio change rate calculation step S5 is then performed. In the present embodiment, in the hardness ratio change rate calculation step S5, the change rate (%) of the ratio (A1 / A2) of the surface-side martensite hardness to the back-side martensite hardness before and after the ultraviolet irradiation step S2 is calculated. Specifically, using the hardness ratio before irradiation and the hardness ratio after irradiation calculated in the hardness ratio calculation step S4, the above-described change rate is calculated. Here, when the change rate is denoted as "C1", the change rate (C1) is calculated using, for example, the following formula (1). C1 = (hardness ratio after irradiation - hardness ratio before irradiation) / hardness ratio before irradiation ··· (1) According to the above formula (1), the change rate (increase rate) of the martensite hardness ratio after ultraviolet irradiation with respect to the martensite hardness ratio before ultraviolet irradiation is calculated.

[0067] (Evaluation step S6) As shown in Fig. 2, after performing the hardness ratio change rate calculation step S5, the evaluation step S6 is then performed. In the evaluation step S6 in the present embodiment, based on the change rate (C1) of the ratio (A1 / A2) of the surface-side martensite hardness to the back-side martensite hardness before and after the ultraviolet irradiation step S2, the weather resistance of the laminated sheet 10 is evaluated. Specifically, in the evaluation step S6, it is evaluated whether the laminated sheet 10 has sufficient weather resistance based on whether the change rate (C1) of the martensite hardness ratio is equal to or less than a predetermined threshold value. Here, sufficient weather resistance means that when the laminated sheet 10 is used outdoors, the weather resistance can be maintained without any abnormalities such as whitening on the surface for at least 5 years.

[0068] In the present embodiment, the above-described threshold value related to the weather resistance evaluation is set according to the change in martensite hardness due to ultraviolet irradiation, the ultraviolet irradiation time in the ultraviolet irradiation step S2, and the period (for example, the warranty period) for which weather resistance retention is required. Generally, the warranty period for buildings (such as houses) is about 5 to 10 years. When the UV irradiation time is 250 hours, the present inventors set the threshold value for the change rate of the Martens hardness ratio to "10%", and by determining whether or not the change rate is 10% or less, the inventors discovered that it is possible to evaluate whether or not the weather resistance can be maintained for at least five years by capturing the initial change in the weather resistance of the laminated sheet. Therefore, in the present embodiment, the UV irradiation time is 250 hours, and the threshold value for performing weather resistance evaluation based on the change rate of the Martens hardness ratio is set to 10%.

[0069] That the change rate (C1) of the ratio (A1 / A2) of the surface-side Martens hardness to the back-side Martens hardness is 10% or less before and after the UV irradiation step S2 indicates that the flexibility of the laminated sheet 10 is maintained and the hardening (deterioration) of the laminated sheet 10 due to UV exposure is suppressed. Therefore, the weather resistance will be maintained over a longer period compared to the case where the change rate (C1) of the Martens hardness ratio exceeds 10%.

[0070] Thus, in the evaluation step S6, based on whether or not the change rate (C1) of the ratio (A1 / A2) of the surface-side Martens hardness to the back-side Martens hardness before and after the UV irradiation test in the UV irradiation step S2 is 10% or less, it is evaluated whether the laminated sheet 10 has sufficient weather resistance. Thereby, it is possible to evaluate whether or not the laminated sheet 10 can maintain its weather resistance for at least five years.

[0071] That is, in the present embodiment, in the evaluation step S6, when the change rate (C1) is equal to or less than the threshold value of "10%", it is evaluated that the laminated sheet 10 has sufficient weather resistance, and when the change rate (C1) is not 10% or less, that is, when the change rate (C1) exceeds 10%, it is evaluated that the laminated sheet 10 does not have sufficient weather resistance. That is, the laminated sheet 10 has sufficient weather resistance by being configured such that the change rate (C1) is 10% or less.

[0072] Further, the smaller the value of the above change rate (C1), that is, the closer it is to 0%, the less the deterioration, and the longer the period during which the weather resistance is maintained. Therefore, when the change rate (C1) of the martensite hardness ratio before and after the ultraviolet irradiation test in the ultraviolet irradiation step S2 is less than 5%, it may be evaluated that the weather resistance can be maintained within a period of 5 to 10 years when the laminated sheet 10 is used outdoors. Also, although the above change rate (C1) may be a negative value, this indicates that the martensite hardness ratio has hardly changed before and after the ultraviolet irradiation test in the ultraviolet irradiation step S2, and does not indicate softening of the laminated sheet 10.

[0073] Further, in the evaluation method of the laminated sheet 10 according to the present embodiment, the measurement of the martensite hardness in the hardness measurement step (pre-irradiation hardness measurement step S1, post-irradiation hardness measurement step S3), the hardness ratio calculation step S4, the hardness ratio change rate calculation step S5, and the calculation process and determination process in the evaluation step S6 may be executed by a predetermined electronic computer (such as a computer). Therefore, the time related to the weather resistance evaluation of the laminated sheet 10 according to the present embodiment is mainly the ultraviolet irradiation time in the ultraviolet irradiation step S2. Conventionally, in the method for evaluating the weather resistance of a laminated sheet by visual inspection, the time related to the evaluation was several thousand hours (for example, about 1000 hours to 3000 hours). On the other hand, in the method for evaluating the weather resistance of the laminated sheet 10 according to the present embodiment, the time related to the weather resistance evaluation is about 250 hours. That is, according to the weather resistance evaluation method according to the present embodiment, the time related to the weather resistance evaluation can be reduced by 70% or more.

[0074] Thus, according to the method for evaluating the weather resistance of the laminated sheet 10 according to the present embodiment, the time related to the evaluation of the laminated sheet can be significantly shortened. As a result, it is possible to suppress costs, reduce the burden on personnel related to the evaluation, and obtain rapid evaluation results for commercial materials. Further, in the method for evaluating the weather resistance of the laminated sheet 10 according to the present embodiment, the weather resistance evaluation is performed based on numerical data (the change rate (C1) of the martensite hardness ratio and the threshold value (10%)). Thereby, the evaluation accuracy can be improved as compared with the visual evaluation. Further, the laminated sheet 10 according to the present embodiment is configured such that the change rate of the ratio (A1 / A2) of the surface-side martensite hardness to the back-side martensite hardness before and after the irradiation test is 10% or less, so that it has excellent weather resistance and can shorten the time related to the weather resistance evaluation.

[0075] As described above, in the weather resistance evaluation method of the laminated sheet 10 according to the present embodiment, from the surface protection layer 15 side which is the outermost surface of the laminated sheet 10, the laminated sheet 10 is irradiated with an integrated light meter having a sensitivity wavelength range of 310 nm or more and 390 nm or less, and the illuminance is 65 mW / cm 2 , an ultraviolet irradiation step S2 of performing an ultraviolet irradiation test for 250 hours using a metal halide lamp under the conditions that the black panel temperature is 63°C and the humidity in the tank is 50%, and before and after the ultraviolet irradiation test in the ultraviolet irradiation step S2, the surface-side martensite hardness (A1) at the surface-side measurement position E1 set in the region on the surface protection layer 15 side in the thickness direction of the transparent resin layer 14 and the back-side martensite hardness (A2) at the back-side measurement position E2 set in the region on the base material sheet 11 side in the thickness direction within the transparent resin layer 14 are measured (hardness measurement step before irradiation S1, hardness measurement step after irradiation S3), and an evaluation step S6 of evaluating the weather resistance based on whether or not the change rate (C1) of the ratio (A1 / A2) of the surface-side martensite hardness to the back-side martensite hardness before and after the irradiation test is 10% or less. Further, the surface-side measurement position E1 and the back-side measurement position E2 are set in regions within the transparent resin layer 14 that are not affected by other layers (the surface protection layer 15, each layer on the base material sheet 11) when measuring the surface-side martensite hardness and the back-side martensite hardness.

[0076] Thereby, in the weather resistance evaluation method of the laminated sheet 10 according to the present embodiment, the time related to the weather resistance evaluation can be shortened.

[0077] Further, the laminated sheet 10 according to the present embodiment is configured to be applicable to the weather resistance evaluation method shown in FIG. 2. Specifically, the laminated sheet 10 according to the present embodiment is a laminated sheet in which a printing layer 12 is provided on a base material sheet 11, and at least a transparent resin layer 14 and a surface protection layer 15 are laminated in this order on the printing layer 12. Further, with respect to the laminated sheet 10 from the surface protection layer 15 side, when the integrated illuminometer with a sensitivity wavelength range of 310 nm or more and 390 nm or less has an illuminance of 65 mW / cm 2 , under the conditions that the black panel temperature is 63°C and the humidity in the tank is 50%, an ultraviolet irradiation test (ultraviolet irradiation step S2) is performed using a metal halide lamp for 250 hours, and before and after the ultraviolet irradiation test, the surface side Martens hardness (A1) at the surface side measurement position E1 set in the region on the surface protection layer 15 side in the thickness direction of the transparent resin layer 14, and the back side Martens hardness (A2) at the back side measurement position E2 set in the region on the base material sheet 11 side in the thickness direction of the transparent resin layer 14 are measured (when the Martens hardness measurement step is implemented), the ratio (A1 / A2) of the surface side Martens hardness to the back side Martens hardness has a change rate of 10% or less before and after the irradiation test. Further, in the laminated sheet 10, the surface side measurement position E1 and the back side measurement position E2 are set in regions that are not affected by other layers (the surface protection layer 15, each layer on the base material sheet 11) when measuring the surface side Martens hardness and the back side Martens hardness in the transparent resin layer 14.

[0078] Thereby, the laminated sheet 10 according to the present embodiment has excellent weather resistance and can shorten the time related to weather resistance evaluation.

[0079] (Modification example) Further, the laminated sheet 10 according to the present embodiment is a laminated sheet in which a printing layer 12 is provided on a base material sheet 11, and at least a transparent resin layer 14 and a surface protection layer 15 are laminated in this order on the printing layer 12, and the transparent resin layer 14 has a Martens hardness of 30 N / mm 2 or less, and a configuration in which at least one of the transparent resin layer 14 and the surface protection layer 15 contains a hindered amine light stabilizer may be adopted. Even with such a configuration, the laminated sheet 10 has excellent weather resistance and can shorten the time related to weather resistance evaluation.

[0080] Here, the Martens hardness (N / mm 2 ) of the transparent resin layer 14 may be the surface-side Martens hardness at the surface-side measurement position E1, or may be the back-side Martens hardness at the back-side measurement position E2, or may be the Martens hardness in the region between the surface-side measurement position E1 and the back-side measurement position E2 in the thickness direction of the transparent resin layer 14. Also, the Martens hardness of the transparent resin layer 14 is preferably in the range of 1 N / mm 2 or more and 30 N / mm 2 or less, and more preferably 20 N / mm 2 or less. Also, the hindered amine-based light stabilizer may be contained in both the transparent resin layer 14 and the surface protection layer 15, may be contained only in the transparent resin layer 14, or may be contained only in the surface protection layer 15.

[0081] <Second Embodiment> (Weather Resistance Evaluation) A method for evaluating the weather resistance of the decorative sheet according to the second embodiment of the present invention (hereinafter referred to as the present embodiment) will be described with reference to FIGS. 1 and 3. FIG. 3 is a flowchart for explaining an example of the flow of the evaluation method of the laminated sheet 10 according to the present embodiment. The weather resistance evaluation method according to the present embodiment is different from the weather resistance evaluation method of the laminated sheet 10 according to the first embodiment in that the weather resistance of the laminated sheet 10 is evaluated based on the indentation elastic modulus.

[0082] As a result of intensive studies on the weather resistance evaluation of the laminated sheet used for exterior decoration and the shortening of the evaluation time related thereto, the inventor of the present invention has found that it is possible to perform the weather resistance evaluation based on the change in the indentation elastic modulus in the transparent resin layer 14 due to ultraviolet exposure. And, by performing the weather resistance evaluation based on the change in the indentation elastic modulus, the time related to the evaluation has been successfully shortened significantly. Hereinafter, an example of the weather resistance evaluation method according to the present embodiment will be specifically described. In the following description, the differences from the weather resistance evaluation method of the laminated sheet 10 according to the first embodiment (see FIG. 2) will be mainly described, and detailed descriptions of the same points will be omitted as appropriate.

[0083] (Pre-irradiation Elastic Modulus Measurement Step S21) As shown in FIG. 3, in the weather resistance evaluation method of the laminated sheet 10 according to this example, first, in the pre-irradiation elastic modulus measurement step, the indentation elastic modulus (E IT / 1-V S ^2) of the transparent resin layer 14 is measured. The unit of the indentation elastic modulus is Mpa. The pre-irradiation elastic modulus measurement step S21 is different from the pre-irradiation hardness measurement step S1 in the first embodiment in that the indentation elastic modulus is measured at the surface-side measurement position E1 and the back-side measurement position E2.

[0084] In the pre-irradiation elastic modulus measurement step S21, the indentation elastic modulus is measured at the surface-side measurement position E1 and the back-side measurement position E2 shown in FIG. 1. Here, the indentation elastic modulus at the surface-side measurement position E1 is defined as the surface-side indentation elastic modulus, and the indentation elastic modulus at the back-side measurement position E2 is defined as the back-side indentation elastic modulus. That is, in the pre-irradiation elastic modulus measurement step, the surface-side indentation elastic modulus at the surface-side measurement position E1 and the back-side indentation elastic modulus at the back-side measurement position E2 are measured. Also in the pre-irradiation elastic modulus measurement step S21, similar to the pre-irradiation hardness measurement step S1, when measuring the surface-side indentation elastic modulus and the back-side indentation elastic modulus, a sample of the laminated sheet 10 is cut in the thickness direction to expose the cross section. In addition, the surface-side measurement position E1 and the back-side measurement position E2 are set in the transparent resin layer 14 in a region that is not affected by other layers even when measuring the surface-side indentation elastic modulus and the back-side indentation elastic modulus. Also in this embodiment, similar to the first embodiment, the surface-side measurement position E1 is set in a region 10 μm apart in the thickness direction from the boundary surface on the surface protection layer 15 side in the transparent resin layer 14 toward the base material sheet 11 side, and the back-side measurement position E2 is preferably set at a position 10 μm apart in the thickness direction from the boundary surface on the base material sheet 11 side in the transparent resin layer 14 toward the surface protection layer 15 side. Thereby, without being affected by the surface protection layer 15, the surface-side indentation elastic modulus can be surely measured, and without being affected by each layer (printing layer 12 or anchor layer 13) provided on the base material sheet 11, the back-side indentation elastic modulus can be surely measured.

[0085] The surface-side indentation elastic modulus and the back-side indentation elastic modulus can be measured using a microhardness measuring device. As the microhardness measuring device, for example, "FISCHERSCOPE Hm2000 manufactured by Fischer" can be used. The microhardness measuring device uses a load parameter in which a load is applied to each of the surface-side measurement position E1 and the back-side measurement position E2 for 10 seconds up to a load of 5 mN, then held for 5 seconds, and then the load is decreased by applying it for 10 seconds up to a load of 0.1 mN, thereby measuring the surface-side indentation elastic modulus (E IT / 1-v s ^2) and the back-side indentation elastic modulus (E IT / 1-v s ^2). In addition, in the elastic modulus measurement by the indentation tester (the above microhardness measuring device), it is not the true indentation elastic modulus (E IT ), but the measurement of the coefficient of the indentation elastic modulus (E IT / 1-v s ^2) including the Poisson's ratio of the measurement sample. Therefore, in this example, the coefficient of the indentation elastic modulus (E IT / 1-v s ^2) measurable by the indentation tester will be referred to as the indentation elastic modulus.

[0086] (UV irradiation step S22) As shown in Fig. 3, after performing the pre-irradiation elastic modulus measurement step S21, the ultraviolet irradiation step S22 is then performed. In the ultraviolet irradiation step S22, an ultraviolet irradiation test on the laminated sheet 10 is conducted. Since the ultraviolet irradiation test in the ultraviolet irradiation step S22 is the same as the ultraviolet irradiation test in the ultraviolet irradiation step S2 of the first embodiment, the description thereof is omitted.

[0087] (Post-irradiation elastic modulus measurement step S23) As shown in Fig. 3, after performing the ultraviolet irradiation step S22, the post-irradiation elastic modulus measurement step S23 is then performed. In the post-irradiation elastic modulus measurement step S23, the indentation elastic modulus of the transparent resin layer 14 after the ultraviolet irradiation test is measured. In this step, in the same manner as in the pre-irradiation elastic modulus measurement step S21, the surface-side indentation elastic modulus at the surface-side measurement position E1 and the back-side indentation elastic modulus at the back-side measurement position E2 are measured. Thus, in the weather resistance evaluation method of the laminated sheet 10 according to the present embodiment, the surface-side indentation elastic modulus and the back-side indentation elastic modulus are measured before and after the ultraviolet irradiation test.

[0088] Note that in the post-irradiation elastic modulus measurement step S23, for the sample of the laminated sheet 10 after performing the ultraviolet irradiation test in the ultraviolet irradiation step S22, the surface-side indentation elastic modulus and the back-side indentation elastic modulus are measured. Further, the pre-irradiation elastic modulus measurement step S21 and the post-irradiation elastic modulus measurement step S23 may be collectively referred to as the "elastic modulus measurement step".

[0089] (Elastic modulus ratio calculation step S24) As shown in Fig. 3, after performing the post-irradiation elastic modulus measurement step S23, the elastic modulus ratio calculation step S24 is then performed. In the elastic modulus ratio calculation step S24, the ratio (P1 / P2) of the surface-side indentation elastic modulus (P1) to the back-side indentation elastic modulus (P2) in the transparent resin layer 14 of the laminated sheet 10 is calculated. Specifically, in the elastic modulus ratio calculation step S24, first, the ratio of the surface-side indentation elastic modulus and the back-side indentation elastic modulus measured in the pre-irradiation elastic modulus measurement step S21 is calculated as the pre-irradiation elastic modulus ratio. Further, the ratio of the surface-side indentation elastic modulus and the back-side indentation elastic modulus measured in the post-irradiation elastic modulus measurement step S23 is calculated as the post-irradiation elastic modulus ratio. By calculating the ratio from the values of the indentation elastic modulus measured in the pre-irradiation elastic modulus measurement step S21 and the post-irradiation elastic modulus measurement step S23, the variation in data can be corrected, and the evaluation accuracy based on the indentation elastic modulus can be improved.

[0090] (Elastic modulus ratio change rate calculation step S25) As shown in FIG. 3, after performing the elastic modulus ratio calculation step S24, the elastic modulus ratio change rate calculation step S25 is then performed. In the present embodiment, in the elastic modulus ratio change rate calculation step S25, the change rate (%) of the ratio (P1 / P2) of the surface-side indentation elastic modulus and the back-side indentation elastic modulus before and after the ultraviolet irradiation step S22 is calculated. Specifically, the above-described change rate is calculated using the pre-irradiation elastic modulus ratio and the post-irradiation elastic modulus ratio calculated in the elastic modulus ratio calculation step S24. Here, when the change rate is denoted as "C2", the change rate (C2) is calculated using, for example, the following formula (2). C2 = (Post-irradiation elastic modulus ratio - Pre-irradiation elastic modulus ratio) / Pre-irradiation elastic modulus ratio ··· (2) According to the above formula (2), the change rate (increase rate) of the post-irradiation indentation elastic modulus ratio with respect to the pre-irradiation indentation elastic modulus ratio is calculated.

[0091] (Evaluation step S26) As shown in FIG. 3, after performing the elastic modulus ratio change rate calculation step S25, the evaluation step S26 is then performed. In the evaluation step S26 in the present embodiment, the weather resistance of the laminated sheet 10 is evaluated based on the change rate (C2) of the ratio (P1 / P2) of the surface-side indentation elastic modulus and the back-side indentation elastic modulus before and after the ultraviolet irradiation step S22. Specifically, in the evaluation step S26, it is evaluated whether the laminated sheet 10 has sufficient weather resistance based on whether the change rate (C2) of the indentation elastic modulus ratio is less than a predetermined threshold value. Here, sufficient weather resistance means that, similar to the weather resistance evaluation in the above first embodiment, when the laminated sheet 10 is used outdoors, the weather resistance can be maintained without any abnormalities such as whitening on the surface for at least five years.

[0092] In this embodiment, the above threshold value related to the weather resistance evaluation is set according to the change in the indentation modulus due to ultraviolet irradiation, the ultraviolet irradiation time in the ultraviolet irradiation step S22, and the period (for example, the warranty period) during which weather resistance retention is required. Generally, the warranty period for buildings (such as houses) is about 5 to 10 years. The inventors of the present invention set the threshold value related to the change rate of the indentation modulus ratio to "25%" when the ultraviolet irradiation time is 250 hours, and by determining whether the change rate is less than 25%, the initial change in the weather resistance of the laminated sheet can be captured, and it was discovered that it is possible to evaluate whether the weather resistance can be maintained for at least five years. Therefore, in this embodiment, the ultraviolet irradiation time is 250 hours, and the threshold value for performing the weather resistance evaluation based on the change rate of the indentation modulus ratio is set to 25%.

[0093] The change rate (C2) of the ratio (P1 / P2) of the surface-side indentation modulus to the back-side indentation modulus being less than 25% before and after the ultraviolet irradiation step S22 indicates that the flexibility of the laminated sheet 10 is maintained and the hardening (deterioration) of the laminated sheet 10 due to ultraviolet exposure is suppressed. Therefore, compared with the case where the change rate (C2) of the indentation modulus is 25% or more, the weather resistance will be maintained over a longer period.

[0094] Thus, in the evaluation step S26, based on whether the change rate (C2) of the ratio (P1 / P2) of the surface-side indentation modulus to the back-side indentation modulus before and after the ultraviolet irradiation test in the ultraviolet irradiation step S22 is less than 25%, it is evaluated whether the laminated sheet 10 has sufficient weather resistance. Thereby, it is possible to evaluate whether the laminated sheet 10 can maintain its weather resistance for at least five years.

[0095] That is, in the present embodiment, in the evaluation step S26, when the change rate (C2) is less than the threshold value of "25%", it is evaluated that the laminated sheet 10 has sufficient weather resistance. When the change rate (C2) is not less than 25%, that is, when the change rate (C2) is 25% or more, it is evaluated that the laminated sheet 10 does not have sufficient weather resistance. That is, the laminated sheet 10 is configured such that the change rate (C2) is less than 25%, and thus has sufficient weather resistance.

[0096] In addition, the smaller the value of the change rate (C2), that is, the closer it is to 0%, the less the deterioration, and the longer the period during which the weather resistance is maintained tends to be. Therefore, for example, when the change rate (C2) of the indentation elastic modulus before and after the ultraviolet irradiation test in the ultraviolet irradiation step S22 is less than 5%, when the laminated sheet 10 is used outdoors, the probability of maintaining the weather resistance within a period of 5 to 10 years is high. In addition, the change rate (C2) may be a negative value, which indicates that the indentation elastic modulus ratio hardly changes before and after the ultraviolet irradiation test in the ultraviolet irradiation step S22, and does not indicate the softening of the laminated sheet 10.

[0097] In addition, in the evaluation method of the laminated sheet 10 according to the present embodiment, the measurement of the indentation elastic modulus in the elastic modulus measurement steps (the pre-irradiation elastic modulus measurement step S21 and the post-irradiation elastic modulus measurement step S23), the elastic modulus ratio calculation step S24, the elastic modulus ratio change rate calculation step S25, and the calculation process and determination process in the evaluation step S26 may be executed by a predetermined electronic computer (such as a computer) in the same manner as the weather resistance evaluation method according to the first embodiment. Also in the weather resistance evaluation method according to the present embodiment, similar to the weather resistance evaluation method according to the first embodiment, the time related to the weather resistance evaluation can be reduced by 70% or more.

[0098] Thus, according to the weather resistance evaluation method of the laminated sheet 10 according to this embodiment, the time required for evaluating the laminated sheet can be significantly shortened, cost can be reduced, the burden on the personnel involved in the evaluation can be alleviated, and quick evaluation results for commercial materials can be obtained. Further, in the weather resistance evaluation method of the laminated sheet 10 according to this embodiment, weather resistance evaluation is performed based on numerical data (the change rate (C2) of the indentation elastic modulus ratio and the threshold value (25%)). Thereby, the evaluation accuracy can be improved as compared with visual evaluation. Further, the laminated sheet 10 according to this embodiment is configured such that the change rate of the ratio (P1 / P2) of the surface-side indentation elastic modulus to the back-side indentation elastic modulus before and after the irradiation test is less than 25%, thereby having excellent weather resistance and being able to shorten the time related to weather resistance evaluation.

[0099] As described above, the weather resistance evaluation method of the laminated sheet 10 according to this embodiment is such that, from the surface protection layer 15 side which is the outermost surface of the laminated sheet 10, an integrating photometer with a sensitivity wavelength range of 310 nm or more and 390 nm or less is used to irradiate the laminated sheet 10 with an illuminance of 65 mW / cm 2 , under the conditions that the black panel temperature is 63 °C and the humidity in the tank is 50%, an ultraviolet irradiation step S22 of performing an ultraviolet irradiation test for 250 hours using a metal halide lamp, and before and after the ultraviolet irradiation test in the ultraviolet irradiation step S22, the surface-side indentation elastic modulus (E IT / 1-V S ^2) at the surface-side measurement position E1 set in the region on the surface protection layer 15 side in the thickness direction of the transparent resin layer 14, and the back-side indentation elastic modulus (E IT / 1-V Sa pressing elastic modulus measurement step of measuring (2) (a pre-irradiation elastic modulus measurement step S21 and a post-irradiation elastic modulus measurement step S23), and an evaluation step S26 of evaluating the weather resistance based on whether or not a change rate (C2) of the ratio (P1 / P2) of the surface-side pressing elastic modulus (P1) to the back-side pressing elastic modulus (P2) before and after the irradiation test is less than 25%. Further, the surface-side measurement position E1 and the back-side measurement position E2 are set in regions that are not affected by other layers (the surface protection layer 15 and each layer on the base material sheet 11) when measuring the surface-side pressing elastic modulus and the back-side pressing elastic modulus in the transparent resin layer 14.

[0100] Thereby, in the weather resistance evaluation method of the laminated sheet 10 according to the present embodiment, the time related to the weather resistance evaluation can be shortened.

[0101] Further, the laminated sheet 10 according to the present embodiment is configured to be applicable to the weather resistance evaluation method shown in FIG. 3. Specifically, the laminated sheet 10 according to the present embodiment is a laminated sheet in which a printing layer 12 is provided on a base material sheet 11, and at least a transparent resin layer 14 and a surface protection layer 15 are laminated in this order on the printing layer 12. Further, the laminated sheet 10 is irradiated with ultraviolet rays for 250 hours using a metal halide lamp under the conditions that the integrated illuminometer with a sensitivity wavelength range of 310 nm or more and 390 nm or less has an illuminance of 65 mW / cm 2 , the black panel temperature is 63° C., and the humidity in the tank is 50%. Before and after the ultraviolet irradiation test, the surface-side pressing elastic modulus (E IT / 1-V S ^2) at the surface-side measurement position E1 set in the region on the surface protection layer 15 side in the thickness direction of the transparent resin layer 14, and the back-side pressing elastic modulus (E IT / 1-V SWhen measuring (when performing the indentation elastic modulus measurement step) the following formula (2), the ratio (P1 / P2) of the surface-side indentation elastic modulus (P1) to the back-side indentation elastic modulus (P2) has a change rate of less than 25% before and after the irradiation test. Further, in the laminated sheet 10, the surface-side measurement position E1 and the back-side measurement position E2 are set in a region that is not affected by other layers (the surface protection layer 15 and each layer on the base sheet 11) when measuring the surface-side indentation elastic modulus and the back-side indentation elastic modulus in the transparent resin layer 14.

[0102] Thereby, the laminated sheet 10 according to the present embodiment has excellent weather resistance and can shorten the time related to the weather resistance evaluation.

[0103] (Modification example) In addition, the laminated sheet 10 according to the present embodiment is a laminated sheet in which a printing layer 12 is provided on the base sheet 11, and at least a transparent resin layer 14 and a surface protection layer 15 are laminated in this order on the printing layer 12. The transparent resin layer 14 has an indentation elastic modulus (E IT / 1-V S ^2) of 600 MPa or less, and a configuration in which at least one of the transparent resin layer 14 and the surface protection layer 15 contains a hindered amine light stabilizer may be used. Even with such a configuration, the laminated sheet 10 has excellent weather resistance and can shorten the time related to the weather resistance evaluation.

[0104] Here, as the indentation elastic modulus of the transparent resin layer 14, it may be the surface-side indentation elastic modulus at the surface-side measurement position E1, the back-side indentation elastic modulus at the back-side measurement position E2, or the indentation elastic modulus in the region between the surface-side measurement position E1 and the back-side measurement position E2 in the thickness direction of the transparent resin layer 14. Further, the indentation elastic modulus of the transparent resin layer 14 is preferably in the range of 300 Ma or more and 600 MPa or less, and more preferably 450 MPa or less. In addition, the hindered amine light stabilizer may be contained in both the transparent resin layer 14 and the surface protection layer 15, may be contained only in the transparent resin layer 14, or may be contained only in the surface protection layer 15.

[0105] <Third Embodiment> (Weather Resistance Evaluation) The method for evaluating the weather resistance of a decorative sheet according to the third embodiment of the present invention (hereinafter referred to as this embodiment) will be described with reference to FIGS. 1 and 4. FIG. 4 is a flowchart for explaining an example of the flow of the evaluation method of the laminated sheet 10 according to this embodiment. The weather resistance evaluation method according to this embodiment is different from the weather resistance evaluation methods of the laminated sheet 10 according to the first and second embodiments in that the weather resistance of the laminated sheet 10 is evaluated based on the indentation hardness.

[0106] As a result of intensive studies on the evaluation of the weather resistance of a laminated sheet used for exterior applications and the shortening of the evaluation time related thereto, the inventor of the present invention has found that it is possible to evaluate the weather resistance based on the change in the indentation hardness (H IT ) of the transparent resin layer 14 due to ultraviolet exposure. And, by performing the weather resistance evaluation based on the change in the indentation hardness, the inventors have succeeded in significantly shortening the time related to the evaluation. Hereinafter, an example of the weather resistance evaluation method according to this embodiment will be specifically described. In the following description, the differences from the weather resistance evaluation method (FIG. 2) of the laminated sheet 10 according to the first embodiment will be mainly described, and detailed descriptions of the same points will be omitted as appropriate.

[0107] (Pre-Irradiation Indentation Hardness Measurement Step S31) As shown in FIG. 4, in the weather resistance evaluation method of the laminated sheet 10 according to this example, first, in the pre-irradiation indentation hardness measurement step S31, the indentation hardness (H IT ) of the transparent resin layer 14 is measured. The unit of the indentation hardness is N / mm 2 . The pre-irradiation indentation hardness measurement step S31 is different from the pre-irradiation hardness measurement step S1 in the first embodiment in that the indentation hardness is measured at the surface-side measurement position E1 and the back-side measurement position E2.

[0108] In the pre-irradiation indentation hardness measurement step 31, the indentation hardness is measured at the front surface side measurement position E1 and the back surface side measurement position E2 shown in FIG. 1. Here, the indentation hardness at the front surface side measurement position E1 is defined as the front surface side indentation hardness, and the indentation hardness at the back surface side measurement position E2 is defined as the back surface side indentation hardness. That is, in the pre-irradiation indentation hardness measurement step, the front surface side indentation hardness at the front surface side measurement position E1 and the back surface side indentation hardness at the back surface side measurement position E2 are measured. Also in the pre-irradiation indentation hardness measurement step S31, similar to the pre-irradiation hardness measurement step S1, when measuring the front surface side indentation hardness and the back surface side indentation hardness, a sample (specimen) of the laminated sheet 10 is cut in the thickness direction to expose the cross section. Further, the front surface side measurement position E1 and the back surface side measurement position E2 are set in the transparent resin layer 14 in a region that is not affected by other layers even during the measurement of the front surface side indentation hardness and the back surface side indentation hardness. Also in the present embodiment, similar to the first embodiment, the front surface side measurement position E1 is set in a region that is 10 μm apart in the thickness direction from the boundary surface on the surface protective layer 15 side toward the base material sheet 11 side in the transparent resin layer 14, and the back surface side measurement position E2 is preferably set at a position that is 10 μm apart in the thickness direction from the boundary surface on the base material sheet 11 side toward the surface protective layer 15 side in the transparent resin layer 14. Thereby, the front surface side indentation hardness can be reliably measured without being affected by the surface protective layer 15, and the back surface side indentation hardness can be reliably measured without being affected by each layer (printing layer 12 or anchor layer 13) provided on the base material sheet 11.

[0109] The front surface side indentation hardness and the back surface side indentation hardness can be measured using a microhardness measuring device. As the microhardness measuring device, for example, "FISCHERSCOPE Hm2000 manufactured by Fischer" can be used. The microhardness measuring device uses a load parameter in which a load is applied to each of the front surface side measurement position E1 and the back surface side measurement position E2 for 10 seconds up to a load of 5 mN, then held for 5 seconds, and then the load is decreased by applying it for 10 seconds up to a load of 0.1 mN, thereby measuring the front surface side indentation hardness (H IT ) and the back surface side indentation hardness (H IT ).

[0110] (Ultraviolet irradiation step S32) As shown in Fig. 4, after performing the pre-irradiation indentation hardness measurement step S31, the ultraviolet irradiation step S32 is then performed. In the ultraviolet irradiation step S32, an ultraviolet irradiation test on the laminated sheet 10 is conducted. Since the ultraviolet irradiation test in the ultraviolet irradiation step S32 is the same as the ultraviolet irradiation test in the ultraviolet irradiation step S2 of the first embodiment, the description thereof is omitted.

[0111] (Post-irradiation indentation hardness measurement step S33) As shown in Fig. 4, after performing the ultraviolet irradiation step S32, the post-irradiation indentation hardness measurement step S33 is then performed. In the post-irradiation indentation hardness measurement step S33, the indentation hardness of the transparent resin layer 14 after the ultraviolet irradiation test is measured. In this step, in the same manner as in the pre-irradiation indentation hardness measurement step S31, the surface-side indentation hardness at the surface-side measurement position E1 and the back-side indentation hardness at the back-side measurement position E2 are measured. Thus, in the weather resistance evaluation method of the laminated sheet 10 according to the present embodiment, the surface-side indentation hardness and the back-side indentation hardness are measured before and after the ultraviolet irradiation test.

[0112] Note that in the post-irradiation indentation hardness measurement step S33, for the sample of the laminated sheet 10 after performing the ultraviolet irradiation test in the ultraviolet irradiation step S22, the surface-side indentation hardness and the back-side indentation hardness are measured. Further, the pre-irradiation indentation hardness measurement step S31 and the post-irradiation indentation hardness measurement step S33 may be collectively referred to as the "indentation hardness measurement step".

[0113] (Indentation hardness ratio calculation step S34) As shown in Fig. 4, after performing the post-irradiation indentation hardness measurement step S33, the indentation hardness ratio calculation step S34 is then performed. In the indentation hardness ratio calculation step S34, the ratio (R1 / R2) of the surface-side indentation hardness (R1) to the back-side indentation hardness (R2) in the transparent resin layer 14 of the laminated sheet 10 is calculated. Specifically, in the indentation hardness ratio calculation step S34, first, the ratio of the surface-side indentation hardness and the back-side indentation hardness measured in the pre-irradiation indentation hardness measurement step S31 is calculated as the pre-irradiation indentation hardness ratio. Further, the ratio of the surface-side indentation hardness and the back-side indentation hardness measured in the post-irradiation indentation hardness measurement step S33 is calculated as the post-irradiation indentation hardness ratio. By calculating the ratio from the values of the indentation hardness measured in the pre-irradiation indentation hardness measurement step S31 and the post-irradiation indentation hardness measurement step S33, the variation in data can be corrected, and the evaluation accuracy based on the indentation hardness can be improved.

[0114] (Indentation hardness ratio change rate calculation step S35) As shown in FIG. 4, after performing the indentation hardness ratio calculation step S34, the indentation hardness ratio change rate calculation step S35 is then performed. In the present embodiment, in the indentation hardness ratio change rate calculation step S35, the change rate (%) of the ratio (R1 / R2) of the surface-side indentation hardness and the back-side indentation hardness before and after the ultraviolet irradiation step S32 is calculated. Specifically, using the pre-irradiation indentation hardness ratio and the post-irradiation indentation hardness ratio calculated in the indentation hardness ratio calculation step S34, the above-described change rate is calculated. Here, when the change rate is denoted as "C3", the change rate (C3) is calculated using, for example, the following formula (3). C3 = (Post-irradiation indentation hardness ratio - Pre-irradiation indentation hardness ratio) / Pre-irradiation indentation hardness ratio ··· (3) According to the above formula (3), the change rate (increase rate) of the post-irradiation indentation hardness ratio with respect to the pre-irradiation indentation hardness ratio is calculated.

[0115] (Evaluation step S36) As shown in FIG. 4, after performing the indentation hardness ratio change rate calculation step S35, the evaluation step S36 is then performed. In the evaluation step S36 in the present embodiment, the weather resistance of the laminated sheet 10 is evaluated based on the change rate (C3) of the ratio (R1 / R2) of the surface-side indentation hardness and the back-side indentation hardness before and after the ultraviolet irradiation step S32. Specifically, in the evaluation step S36, it is evaluated whether the laminated sheet 10 has sufficient weather resistance based on whether the change rate (C3) of the indentation hardness ratio is less than a predetermined threshold value. Here, sufficient weather resistance means that, similar to the weather resistance evaluation in the first embodiment, when the laminated sheet 10 is used outdoors, the weather resistance can be maintained without any abnormalities such as whitening on the surface for at least five years.

[0116] In this embodiment, the above-mentioned threshold value related to the weather resistance evaluation is set according to the change in indentation hardness due to ultraviolet irradiation, the ultraviolet irradiation time in the ultraviolet irradiation step S32, and the period (for example, the warranty period) during which weather resistance retention is required. Generally, the warranty period for buildings (such as houses) is about 5 to 10 years. The inventors of the present invention set the threshold value for the change rate of the indentation hardness ratio to "20%" when the ultraviolet irradiation time is 250 hours, and by determining whether the change rate is less than 20%, the initial change in the weather resistance of the laminated sheet can be captured, and it was discovered that it is possible to evaluate whether the weather resistance can be maintained for at least five years. Therefore, in this embodiment, the ultraviolet irradiation time is 250 hours, and the threshold value for performing the weather resistance evaluation based on the change rate of the indentation hardness ratio is set to 20%.

[0117] The change rate (C3) of the ratio (R1 / R2) of the surface-side indentation hardness to the back-side indentation hardness before and after the ultraviolet irradiation step S32 being less than 20% indicates that the flexibility of the laminated sheet 10 is maintained and the hardening (deterioration) of the laminated sheet 10 due to ultraviolet exposure is suppressed. Therefore, compared with the case where the change rate (C3) of the indentation hardness is 20% or more, the weather resistance will be maintained over a longer period.

[0118] Thus, in the evaluation step S36, based on whether the change rate (C3) of the ratio (R1 / R2) of the surface-side indentation hardness to the back-side indentation hardness before and after the ultraviolet irradiation test in the ultraviolet irradiation step S32 is less than 20%, it is evaluated whether the laminated sheet 10 has sufficient weather resistance. Thereby, it is possible to evaluate whether the laminated sheet 10 can maintain its weather resistance for at least five years.

[0119] That is, in the present embodiment, in the evaluation step S26, when the change rate (C3) is less than the threshold value "20%", it is evaluated that the laminated sheet 10 has sufficient weather resistance. When the change rate (C3) is not less than 20%, that is, when the change rate (C3) is 20% or more, it is evaluated that the laminated sheet 10 does not have sufficient weather resistance. That is, the laminated sheet 10 is configured such that the change rate (C3) is less than 20%, and thus has sufficient weather resistance.

[0120] In addition, the smaller the value of the change rate (C3), that is, the closer it is to 0%, the less the deterioration, and the longer the period during which the weather resistance is maintained tends to be. In addition, although the change rate (C3) may be a negative value, this indicates that the indentation hardness ratio before and after the ultraviolet irradiation test in the ultraviolet irradiation step S32 has hardly changed, and does not indicate softening of the laminated sheet 10.

[0121] In addition, in the evaluation method of the laminated sheet 10 according to the present embodiment, the measurement of the indentation hardness in the indentation hardness measurement step (pre-irradiation indentation hardness measurement step S31, post-irradiation indentation hardness measurement step S33), the indentation hardness ratio calculation step S34, the indentation hardness ratio change rate calculation step S35, and the calculation process and determination process in the evaluation step S36 may be executed by a predetermined electronic computer (such as a computer) in the same manner as the weather resistance evaluation method according to the first embodiment. Also in the weather resistance evaluation method according to the present embodiment, similar to the weather resistance evaluation method according to the first embodiment, the time related to the weather resistance evaluation can be reduced by 70% or more.

[0122] As described above, according to the weather resistance evaluation method of the laminated sheet 10 according to the present embodiment, the time related to the evaluation of the laminated sheet can be significantly shortened, the cost can be suppressed, the burden on the personnel related to the evaluation can be reduced, and a rapid evaluation result for commercial materials can be obtained. Further, in the weather resistance evaluation method of the laminated sheet 10 according to the present embodiment, the weather resistance evaluation is performed based on numerical data (the change rate (C3) of the indentation hardness ratio and the threshold value (20%)). Thereby, the evaluation accuracy can be improved as compared with the visual evaluation. In addition, the laminated sheet 10 according to the present embodiment is configured such that the change rate of the ratio (R1 / R2) of the surface-side indentation hardness to the back-side indentation hardness before and after the irradiation test is less than 20%, thereby having excellent weather resistance and being able to shorten the time related to the weather resistance evaluation.

[0123] As described above, the weather resistance evaluation method of the laminated sheet 10 according to the present embodiment is such that, from the surface protection layer 15 side which is the outermost surface of the laminated sheet 10, with respect to the laminated sheet 10, the illuminance is 65 mW / cm with an integrating photometer having a sensitivity wavelength range of 310 nm or more and 390 nm or less. 2 , an ultraviolet irradiation step S32 of performing an ultraviolet irradiation test for 250 hours using a metal halide lamp under the conditions that the black panel temperature is 63°C and the humidity in the tank is 50%; before and after the ultraviolet irradiation test in the ultraviolet irradiation step S32, the surface-side indentation hardness (H IT ) at the surface-side measurement position E1 set in the region on the surface protection layer 15 side in the thickness direction of the transparent resin layer 14, and the back-side indentation hardness (H IT ) at the back-side measurement position E2 set in the region on the base material sheet 11 side in the thickness direction of the transparent resin layer are measured (indentation hardness measurement step before irradiation S31, indentation hardness measurement step after irradiation S33); and an evaluation step of evaluating the weather resistance based on whether the change rate of the ratio (R1 / R2) of the surface-side indentation hardness (R1) to the back-side indentation hardness (R2) before and after the irradiation test is less than 20%. Further, the surface-side measurement position E1 and the back-side measurement position E2 are set in regions in the transparent resin layer 14 that are not affected by other layers when measuring the surface-side indentation hardness and the back-side indentation hardness.

[0124] Thereby, in the weather resistance evaluation method of the laminated sheet 10 according to the present embodiment, the time related to the weather resistance evaluation can be shortened.

[0125] In addition, the laminated sheet 10 according to the present embodiment is configured to be applicable to the weather resistance evaluation method shown in FIG. 4. Specifically, the laminated sheet 10 according to the present embodiment is a laminated sheet in which a printing layer 12 is provided on a base material sheet 11, and at least a transparent resin layer 14 and a surface protection layer 15 are laminated in this order on the printing layer 12. Further, with respect to the laminated sheet 10 from the surface protection layer 15 side, an illuminance of 65 mW / cm 2 is measured with an integrated photometer having a sensitivity wavelength range of 310 nm or more and 390 nm or less. Under the conditions where the black panel temperature is 63° C. and the humidity inside the tank is 50%, an ultraviolet irradiation test is performed for 250 hours using a metal halide lamp. Before and after the ultraviolet irradiation test, the surface side indentation hardness (H IT ) at the surface side measurement position E1 set in the region on the surface protection layer 15 side in the thickness direction of the transparent resin layer 14 and the back side indentation hardness (H IT ) at the back side measurement position E2 set in the region on the base material sheet 11 side in the thickness direction of the transparent resin layer 14 are measured (when the indentation hardness measurement step is performed). The ratio (R1 / R2) of the surface side indentation hardness (R1) to the back side indentation hardness (R2) has a change rate of less than 20% before and after the irradiation test. Further, in the laminated sheet 10, the surface side measurement position E1 and the back side measurement position E2 are set in regions of the transparent resin layer 14 that are not affected by other layers when measuring the surface side indentation hardness and the back side indentation hardness.

[0126] Thereby, the laminated sheet 10 according to the present embodiment has excellent weather resistance and can shorten the time related to weather resistance evaluation.

[0127] (Modification example) Further, the laminated sheet 10 according to the present embodiment is a laminated sheet in which a printing layer 12 is provided on a base material sheet 11, and at least a transparent resin layer 14 and a surface protection layer 15 are laminated in this order on the printing layer 12. The transparent resin layer 14 has an indentation hardness (H IT ) of 45 N / mm 2 or less, and a configuration in which at least one of the transparent resin layer 14 and the surface protection layer 15 contains a hindered amine light stabilizer may be employed. Even with such a configuration, the laminated sheet 10 has excellent weather resistance and can shorten the time related to weather resistance evaluation.

[0128] Here, as the indentation hardness of the transparent resin layer 14, it may be the surface-side indentation hardness at the surface-side measurement position E1, or the back-side indentation hardness at the back-side measurement position E2, or the indentation hardness in the region between the surface-side measurement position E1 and the back-side measurement position E2 in the thickness direction of the transparent resin layer 14. Also, the indentation hardness of the transparent resin layer 14 is preferably in the range of 10 N / mm 2 or more and 45 N / mm 2 or less, and more preferably 30 N / mm 2 or less. Also, the hindered amine-based light stabilizer may be contained in both the transparent resin layer 14 and the surface protection layer 15, or may be contained only in the transparent resin layer 14, or may be contained only in the surface protection layer 15.

[0129] (Example) Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited by the examples. <Example 1> (Process for forming a resin sheet for the transparent resin layer) First, a benzotriazole-based ultraviolet absorber and a hindered amine-based light stabilizer were added to a homopolypropylene resin to obtain a resin material for the transparent resin layer. Here, as the homopolypropylene resin, a material having a meso pentad fraction of 95% or more and an MFR (melt flow rate) of 4.5 g / 10 min (JIS K 7210:99) was used. A benzotriazole-based ultraviolet absorber and a hindered amine-based light stabilizer were added to the resin material for the transparent resin layer. As the benzotriazole-based ultraviolet absorber, "Tinuvin 328: manufactured by BASF)" was used and added at 2000 PPM (0.2 parts by mass) with respect to the homopolypropylene resin. Also, as the hindered amine-based light stabilizer, "Chimasorb 944: manufactured by BASF" was used and added at 2000 PPM (0.2 parts by mass) with respect to the homopolypropylene resin. Such a resin material for the transparent resin layer was extruded using a melt extruder to form a polypropylene transparent resin sheet having a thickness of 80 μm to be used as the transparent resin layer. (Formation Process of Surface Protective Layer) To the surface of the above transparent resin layer, a benzotriazole-based ultraviolet absorber and a hindered amine-based light stabilizer were added to an acrylic urethane resin to obtain a resin material for the surface protective layer. As the acrylic urethane resin, a two-component curable urethane top coat (W184; manufactured by DIC Graphics Co., Ltd.) was used. Further, a benzotriazole-based ultraviolet absorber and a hindered amine-based light stabilizer were added to the resin material for the surface protective layer. As the benzotriazole-based ultraviolet absorber, "Tinuvin 328: manufactured by BASF" was used and added at 2000 PPM (0.2 parts by mass) with respect to the urethane top coat. As the hindered amine-based light stabilizer, "Chimasorb 944: manufactured by BASF" was used and added at 2000 PPM (0.2 parts by mass) with respect to the urethane top coat. Such a resin material for the surface protective layer was applied onto the transparent resin layer at a coating thickness of 6 g / m 2 and dried to form a surface protective layer.

[0130] <Example 2> No ultraviolet absorber was added to the resin material for the transparent resin layer. Otherwise, in the same manner as in Example 1, a transparent resin layer and a surface protective layer according to Example 2 were produced.

[0131] <Example 3> No ultraviolet absorber was added to the resin material for the surface protective layer. Otherwise, in the same manner as in Example 1, a transparent resin layer and a surface protective layer according to Example 3 were produced.

[0132] <Example 4> No hindered amine-based light stabilizer was added to the urethane top coat which is the resin material for the surface protective layer. Otherwise, in the same manner as in Example 1, a transparent resin layer and a surface protective layer according to Example 4 were produced.

[0133] <Example 5> Neither an ultraviolet absorber nor a hindered amine-based light stabilizer was added to the resin material for the surface protective layer, and only the urethane top coat was used. Otherwise, in the same manner as in Example 1, a transparent resin layer and a surface protective layer according to Example 5 were produced.

[0134] <Example 6> As the homopolypropylene resin in the resin material for the transparent resin layer, a material with a mesopentad fraction of 95% or more and an MFR (melt flow rate) of 6.2 g / 10 min (JIS K 7210:99) was used. Otherwise, in the same manner as in Example 1, the transparent resin layer and the surface protective layer according to Example 6 were produced.

[0135] <Comparative Example 1> The transparent resin layer and the surface protective layer according to Comparative Example 1 were produced in the same manner as in Example 1, except that the resin material for the transparent resin layer was only homopolypropylene resin.

[0136] <Comparative Example 2> A hindered amine-based light stabilizer was not added to the resin material for the transparent resin layer. Otherwise, in the same manner as in Example 1, the transparent resin layer and the surface protective layer according to Comparative Example 2 were created.

[0137] <Comparative Example 3> As the homopolypropylene resin in the resin material for the transparent resin layer, a material with a mesopentad fraction of 95% or more and an MFR (melt flow rate) of 15 g / 10 min (JIS K 7210:99) was used. Otherwise, in the same manner as in Example 1, the transparent resin layer and the surface protective layer according to Comparative Example 3 were created.

[0138] <Evaluation> For each of the samples (transparent resin layer and surface protective layer) obtained in the above Examples 1 to 5 and Comparative Examples 1 to 3, (1) weather resistance evaluation based on Martens hardness, (2) weather resistance evaluation based on indentation elastic modulus, and (3) weather resistance evaluation based on indentation hardness were respectively carried out. The evaluation results of (1) are shown in Table 1 below, the evaluation results of (2) are shown in Table 2 below, and the evaluation results of (3) are shown in Table 3 below.

[0139]

Table 1

[0140]

Table 2

[0141]

Table 3

[0142] The evaluation contents of each weather resistance evaluation are described below. <Weather resistance evaluation based on Martens hardness> (1-1) Measurement of Martens hardness before ultraviolet irradiation Using the "FISCHERSCOPE Hm2000" manufactured by Fischer as a microhardness measuring device, for each sample of Examples 1 to 6 and Comparative Examples 1 to 3 before the ultraviolet irradiation test in (1-2) below, the Martens hardness was measured at two locations (surface-side measurement position, back-side measurement position) of the transparent resin layer. The surface-side measurement position was set as the position 10 μm away from the interface with the surface protection layer side in the thickness direction (the direction opposite to the surface protection layer) in the transparent resin layer. Also, the back-side measurement position was set as the position 10 μm away from the surface (back surface) on the opposite side of the surface protection layer in the thickness direction (the direction of the surface protection layer). The Martens hardness at the surface-side measurement position (surface-side Martens hardness) and the Martens hardness at the back-side measurement position (back-side Martens hardness) were measured using a load parameter in which a load was applied up to 5 mN for 10 seconds, held for 5 seconds after the load increase, and then the load was decreased by applying it up to 0.1 mN for 10 seconds for each of the surface-side measurement position and the back-side measurement position in the microhardness measuring device. In the "Before irradiation test" column of Table 1, the Martens hardness (surface-side Martens hardness, back-side Martens hardness) before the ultraviolet irradiation test for each sample of Examples 1 to 6 and Comparative Examples 1 to 3 is shown together with the Martens hardness ratio (surface-side Martens hardness before irradiation test / back-side Martens hardness before irradiation test).

[0143] (1-2) Ultraviolet irradiation test Using the "Metal Weathering Tester (KW-R7TP-A) manufactured by Dipla Wintersteiger Co., Ltd.", an ultraviolet irradiation test was conducted on each sample of Examples 1 to 6 and Comparative Examples 1 to 3. The conditions of the test were such that the illuminance in an integrating photometer with a sensitivity wavelength range of 310 nm or more and 390 nm or less was 65 mW / cm 2 , the black panel temperature was 63°C, and the humidity inside the tank was 50%. As the integrating photometer, "Ultraviolet Irradiance Meter UIT-201: manufactured byUSHIO INC." was used. Thus, samples for measuring the martensite hardness after ultraviolet irradiation, which will be described later, were prepared.

[0144] (1-3) Measurement of martensite hardness after ultraviolet irradiation For each sample of Examples 1 to 6 and Comparative Examples 1 to 3 after the ultraviolet irradiation test in (1-2) above, the surface-side martensite hardness and the back-side martensite hardness were measured in the same manner as the martensite hardness measurement before irradiation in (1-1) above. In the "After Irradiation Test" column of Table 1, the martensite hardness (surface-side martensite hardness, back-side martensite hardness) after the ultraviolet irradiation test for each sample of Examples 1 to 6 and Comparative Examples 1 to 3 is shown together with the martensite hardness ratio (surface-side martensite hardness after irradiation test / back-side martensite hardness after irradiation test).

[0145] (1-4) Life test For each sample of Examples 1 to 6 and Comparative Examples 1 to 3, using the "Metal Weathering Tester (KW-R7TP-A) manufactured by Dipla Wintersteiger Co., Ltd.", light irradiation was carried out under the conditions of illuminance 65 mW / cm 2 (calibrated with an ultraviolet irradiance meter UIT-201: manufactured by USHIO INC.), black panel temperature 63°C, and humidity inside the tank 50%, and each sample was visually checked every 24 hours. In the life test, the time (h) until whitening was confirmed on the outermost surface (surface protective layer) was taken as the life (weather resistance retention period) of each sample, and weather resistance evaluation was carried out. 〔Evaluation criteria〕 ◎: 2800 hours or more 〇: 2500 hours or more ×: Less than 2500 hours In this evaluation, if the time (life time) until whitening is confirmed on the outermost surface (surface protective layer) is 2500 hours or more, it is considered that the weather resistance of the laminated sheet can be maintained for 5 years (excellent weather resistance), and it is judged as qualified "○". Also, when the evaluation result is "◎", it indicates an evaluation result that the weather resistance of the laminated sheet can be maintained for a period of 5 years or more and 10 years or less.

[0146] (Regarding the weather resistance evaluation result based on Martens hardness) As shown in Table 1, from the evaluation results of Examples 1 to 6, when the change rate of the ratio of Martens hardness (surface side Martens hardness / back side Martens hardness) before and after the ultraviolet irradiation test is 10% or less, the life evaluation result is good (all qualified "〇" or above), and it was found that it has excellent weather resistance. Also, from the evaluation results of Examples 1 and 2, when the change rate of the ratio of Martens hardness is less than 5%, it was found that the life evaluation result is extremely good (◎).

[0147] On the other hand, from the evaluation results of Comparative Examples 1 to 3, when the change rate of the ratio of Martens hardness before and after the ultraviolet irradiation test exceeds 10%, it was found that the life evaluation result is unqualified (×) and the weather resistance is not sufficient. From the above, it was found that the weather resistance can be evaluated based on whether the change rate of the ratio of Martens hardness is 10% or less. Furthermore, by the weather resistance evaluation based on Martens hardness, the weather resistance evaluation of a laminated sheet that requires thousands of hours (in this example, 2000 hours or more) visually can be performed in 250 hours (ultraviolet irradiation time in the ultraviolet irradiation test), and it was found that the evaluation time can be significantly reduced compared to the visual case.

[0148] (Weather resistance evaluation based on indentation elastic modulus) (2-1) Measurement of indentation elastic modulus before ultraviolet irradiation Using "FISCHERSCOPE Hm2000" manufactured by Fischer as a microhardness measuring device, for each sample of Examples 1 to 5 and Comparative Examples 1 to 3 before the ultraviolet irradiation test in the following (2-2), the indentation elastic modulus (E) at two locations (surface side measurement position, back side measurement position) of the transparent resin layerIT / 1 - v s ^2) was measured. The measurement positions on the front side and the back side were the same as those in the martensite hardness measurement in (1 - 1) above. The indentation elastic modulus at the measurement position on the front side (front - side indentation elastic modulus) and the indentation elastic modulus at the measurement position on the back side (back - side indentation elastic modulus) were measured using a micro - hardness measuring device with a load parameter where a load was applied for 10 seconds up to 5 mN, held for 5 seconds after the load increase, and then the load was decreased for 10 seconds down to 0.1 mN for each of the measurement positions on the front side and the back side. In the "before irradiation test" column of Table 2, the indentation elastic moduli (front - side indentation elastic modulus, back - side indentation elastic modulus) before the ultraviolet irradiation test for each sample of Examples 1 - 5 and Comparative Examples 1 - 3 are shown together with the indentation elastic modulus ratio (front - side indentation elastic modulus before irradiation test / back - side indentation elastic modulus before irradiation test).

[0149] (2 - 2) Ultraviolet irradiation test An ultraviolet irradiation test was carried out under the same apparatus and conditions as in (1 - 2) above. As a result, samples for measuring the indentation elastic modulus after ultraviolet irradiation, which will be described later, were prepared.

[0150] (2 - 3) Measurement of indentation elastic modulus after ultraviolet irradiation For each sample of Examples 1 - 5 and Comparative Examples 1 - 3 after the ultraviolet irradiation test in 2 - 2 above, the front - side indentation elastic modulus and the back - side indentation elastic modulus were measured in the same manner as the measurement of the indentation elastic modulus before irradiation in (2 - 1) above. In the "after irradiation test" column of Table 2, the indentation elastic moduli (front - side indentation elastic modulus, back - side indentation elastic modulus) after the ultraviolet irradiation test for each sample of Examples 1 - 5 and Comparative Examples 1 - 3 are shown together with the indentation elastic modulus ratio (front - side indentation elastic modulus after irradiation test / back - side indentation elastic modulus after irradiation test).

[0151] (2 - 4) Life test For each sample of Examples 1 to 5 and Comparative Examples 1 to 3, weather resistance evaluation was performed using the same apparatus and conditions as in (1 - 4) above. Also, in the same manner as in (1 - 4) above, the time (h) until whitening was confirmed on the outermost surface (surface protective layer) was defined as the life (weather resistance retention period) of each sample, and weather resistance evaluation was carried out. 〔Evaluation Criteria〕 ◎: 2800 hours or more 〇: 2500 hours or more ×: Less than 2500 hours Also, in this evaluation, in the same manner as in (1 - 4) above, if the time (life time) until whitening was confirmed on the outermost surface (surface protective layer) was 2500 hours or more, it was considered that the weather resistance of the laminated sheet could be maintained for 5 years (excellent weather resistance), and the result was judged as qualified "〇". Also, when the evaluation result was "◎", it indicated an evaluation result that the weather resistance of the laminated sheet could be maintained in the period of 5 years or more and 10 years or less.

[0152] (Regarding the evaluation results based on the indentation elastic modulus) As shown in Table 2, from the evaluation results of Examples 1 to 5, when the change rate of the ratio of the indentation elastic modulus before and after the ultraviolet irradiation test (surface - side indentation elastic modulus / back - side indentation elastic modulus) was less than 25%, the life evaluation results were good (all qualified "〇" or above), and it was found that they had excellent weather resistance. Also, from the evaluation results of Examples 1 and 2, it was found that when the change rate of the ratio of the indentation elastic modulus was less than 5%, the probability that the life evaluation results would be extremely good (◎) was high.

[0153] On the other hand, from the evaluation results of Comparative Examples 1 to 3, when the change rate of the ratio of the indentation elastic modulus before and after the ultraviolet irradiation test was 25% or more, it was found that the life evaluation results were unqualified (×) and the weather resistance was insufficient. From the above, it was found that the weather resistance can be evaluated by whether the change rate of the ratio of the indentation elastic modulus is less than 25%. Furthermore, by evaluating the weather resistance based on the indentation elastic modulus, the weather resistance evaluation of the laminated sheet that requires thousands of hours (in this example, 2000 hours or more) visually can be performed in 250 hours (the ultraviolet irradiation time in the ultraviolet irradiation test), and it was found that the evaluation time can be significantly reduced compared to the visual case.

[0154] <Weather Resistance Evaluation Based on Indentation Hardness> (3-1) Measurement of Indentation Hardness before Ultraviolet Irradiation Using the "FISCHERSCOPE Hm2000" manufactured by Fischer as a microhardness measuring device, for each sample of Examples 1 to 5 and Comparative Examples 1 to 3 before the ultraviolet irradiation test in the following (3-2), the indentation hardness (H IT ) was measured at two locations (surface-side measurement position, back-side measurement position) of the transparent resin layer. The surface-side measurement position and the back-side measurement position were the same as the positions during the Martens hardness measurement in the above (1-1). The indentation hardness at the surface-side measurement position (surface-side indentation hardness) and the indentation hardness at the back-side measurement position (back-side indentation hardness) were measured using a load parameter in the microhardness measuring device, where a load of up to 5 mN was applied for 10 seconds to increase the load, then this was held for 5 seconds, and the load was decreased by applying a load of up to 0.1 mN for 10 seconds for each of the surface-side measurement position and the back-side measurement position. In the "Before Irradiation Test" column of Table 3, the indentation hardness (surface-side indentation hardness, back-side indentation hardness) before the ultraviolet irradiation test for each sample of Examples 1 to 5 and Comparative Examples 1 to 3 is shown together with the indentation hardness ratio (surface-side indentation hardness before the irradiation test / back-side indentation hardness before the irradiation test).

[0155] (3-2) Ultraviolet Irradiation Test An ultraviolet irradiation test was carried out under the same apparatus and conditions as in the above (1-2). As a result, samples for measuring the indentation hardness after ultraviolet irradiation, which will be described later, were produced.

[0156] (3-3) Measurement of Indentation Hardness after Ultraviolet Irradiation After conducting the ultraviolet irradiation test in 3-2 above, for each sample of Examples 1 to 5 and Comparative Examples 1 to 3, in the same manner as the indentation hardness measurement before irradiation in (3-1) above, the surface-side indentation hardness and the back-side indentation hardness were measured. In the "After Irradiation Test" column of Table 3, the indentation hardness (surface-side indentation hardness, back-side indentation hardness) after the ultraviolet irradiation test for each sample of Examples 1 to 5 and Comparative Examples 1 to 3 is shown together with the indentation hardness ratio (surface-side indentation hardness after irradiation test / back-side indentation hardness after irradiation test).

[0157] (3-4) Life Test For each sample of Examples 1 to 5 and Comparative Examples 1 to 3, weather resistance evaluation was carried out under the same apparatus and conditions as in (1-4) above. Also, in the same manner as in (1-4), the time (h) until whitening was confirmed on the outermost surface (surface protective layer) was taken as the life (weather resistance retention period) of each sample, and weather resistance evaluation was carried out. 〔Evaluation Criteria〕 ◎: 2800 hours or more 〇: 2500 hours or more ×: Less than 2500 hours Also, in this evaluation, in the same manner as in (1-4) above, if the time (life time) until whitening was confirmed on the outermost surface (surface protective layer) was 2500 hours or more, it was considered that the weather resistance of the laminated sheet could be maintained for 5 years (excellent weather resistance), and it was judged as qualified "〇". Also, when the evaluation result was "◎", it showed an evaluation result that the weather resistance of the laminated sheet could be maintained in the period of 5 years or more and 10 years or less.

[0158] (Regarding the evaluation results based on indentation hardness) As shown in Table 3, from the evaluation results of Examples 1 to 5, when the change rate of the ratio of indentation hardness (surface-side indentation hardness / back-side indentation hardness) before and after the ultraviolet irradiation test was less than 20%, the life evaluation results were good (all qualified "〇" or above), and it was found that they had excellent weather resistance.

[0159] On the other hand, from the evaluation results of Comparative Examples 1 to 3, when the change rate of the ratio of the indentation hardness before and after the ultraviolet irradiation test is 20% or more, it was found that the life evaluation result is unacceptable (×) and the weather resistance is insufficient. From the above, it was found that the weather resistance can be evaluated depending on whether the change rate of the ratio of the indentation hardness is less than 20%. Furthermore, by the weather resistance evaluation based on the indentation hardness, the weather resistance evaluation of the laminated sheet that requires thousands of hours (in this example, 2000 hours or more) visually can be performed in 250 hours (the ultraviolet irradiation time in the ultraviolet irradiation test), and it was found that the evaluation time can be significantly reduced compared to the visual case.

[0160] Note that the laminated sheet and the method for evaluating the weather resistance of the laminated sheet of the present invention are not limited to the above-described embodiments and examples, and various modifications are possible without impairing the features of the invention.

Explanation of Reference Numerals

[0161] 10 Cosmetic sheet 11 Base material sheet 12 Printing layer 13 Anchor layer 14 Transparent resin layer 15 Surface protection layer E1 Measurement position on the surface side E2 Measurement position on the back side

Claims

1. A laminated sheet having a printing layer provided on a base material sheet, and at least a transparent resin layer and a surface protection layer laminated in this order on the printing layer, wherein the transparent resin layer, is formed of polypropylene having a thickness of 80 μm and an MFR within the range of 4.5 g / 10 min or more and 6.2 g / 10 min or less, and contains a benzotriazole-based ultraviolet absorber and a hindered amine-based light stabilizer, the content of the hindered amine-based light stabilizer in the transparent resin layer is 0.2 parts by mass or more based on the total mass of the transparent resin layer, the surface protection layer is formed of an acrylic urethane resin and contains at least one of a hindered amine-based light stabilizer or an ultraviolet absorber, the coating thickness of the acrylic urethane resin for forming the surface protection layer on the transparent resin layer is 6 g / m 2, From the surface protection layer side, with an integrating photometer having a sensitivity wavelength range of 310 nm or more and 390 nm or less, the illuminance is 65 mW / cm ２ , under the conditions of a black panel temperature of 63 °C and a humidity inside the tank of 50%, an ultraviolet irradiation test is performed for 250 hours using a metal halide lamp, and Before and after the irradiation test, the surface-side Martens hardness (N / mm ２ ) at the surface-side measurement position set in the region on the surface protection layer side in the thickness direction of the transparent resin layer, and the back-side Martens hardness (N / mm ２ ) at the back-side measurement position set in the region on the base sheet side in the thickness direction of the transparent resin layer are measured, and the ratio (A1 / A2) of the surface side Martens hardness (A1) to the back side Martens hardness (A2) has a change rate of 10% or less before and after the irradiation test, the surface side Martens hardness (A1) and the back side Martens hardness (A2) measured before the irradiation test are 30 N / mm 2 or less, the surface side measurement position is set in a region 10 μm away in the thickness direction from the interface on the surface protection layer side in the transparent resin layer toward the base material sheet side, the back side measurement position is set in a region 10 μm away in the thickness direction from the interface on the base material sheet side in the transparent resin layer toward the surface protection layer side, a laminated sheet.

2. The surface side martensite hardness before the irradiation test is 20 N / mm ２ or less The laminated sheet according to claim 1.

3. the surface protection layer contains a hindered amine-based light stabilizer, the content of the hindered amine-based light stabilizer in the surface protection layer is 0.2 parts by mass or more based on the total mass of the surface protection layer The laminated sheet according to claim 1 or 2.

4. the surface protection layer contains an ultraviolet absorber, the content of the ultraviolet absorber in the surface protection layer is 0.2 parts by mass or more based on the total mass of the surface protection layer The laminated sheet according to any one of claims 1 to 3.

5. A method for evaluating the weather resistance of a laminated sheet having a printing layer provided on a base material sheet, and at least a transparent resin layer and a surface protection layer laminated in this order on the printing layer, From the surface protection layer side, which is the outermost surface of the laminated sheet, to the laminated sheet, with an integrating photometer having a sensitivity wavelength range of 310 nm or more and 390 nm or less, the illuminance is 65 mW / cm ２ , an ultraviolet irradiation step of performing an ultraviolet irradiation test for 250 hours using a metal halide lamp under the conditions of a black panel temperature of 63 °C and a humidity inside the tank of 50%; Before and after the ultraviolet irradiation test, the surface-side Martens hardness (N / mm ２ ), and the back-side Martens hardness (N / mm ２ ) at the back-side measurement position set in the region on the base material sheet side in the thickness direction of the transparent resin layer are measured, and a Martens hardness measurement step is performed. An evaluation step of evaluating the weather resistance based on whether or not the change rate of the ratio (A1 / A2) of the surface-side martensitic hardness (A1) to the back-side martensitic hardness (A2) before and after the irradiation test is 10% or less; including; The transparent resin layer is; formed of polypropylene having a thickness of 80 μm and an MFR in the range of 4.5 g / 10 min or more and 6.2 g / 10 min or less, and contains a hindered amine-based light stabilizer; the content of the hindered amine-based light stabilizer in the transparent resin layer is 0.2 parts by mass or more based on the total mass of the transparent resin layer; the surface protective layer is formed of an acrylic urethane resin and contains at least one of a hindered amine-based light stabilizer or an ultraviolet absorber; the coating thickness of the acrylic urethane resin for forming the surface protective layer on the transparent resin layer is 6 g / m 2 ; the surface-side martensitic hardness (A1) and the back-side martensitic hardness (A2) measured before the irradiation test are 30 N / mm 2 or less; the surface-side measurement position is set in a region 10 μm away in the thickness direction from the interface on the surface protective layer side in the transparent resin layer toward the base material sheet side; the back-side measurement position is set in a region 10 μm away in the thickness direction from the interface on the base material sheet side in the transparent resin layer toward the surface protective layer side, A method for evaluating the weather resistance of a laminated sheet.

Images