Decorative sheet and method for manufacturing decorative sheet

Abstract

To provide a decorative sheet excellent in weather resistance and scratch resistance, and to provide a production method of the decorative sheet.SOLUTION: A decorative sheet 10 comprises: a substrate layer 11 containing polyolefin; a pattern layer 12 formed on the substrate layer 11; an anchor layer 13 formed on the pattern layer 12; a transparent resin layer 14 formed on the anchor layer 13 and having polypropylene as the main component; and a top coat layer 15 formed on the transparent resin layer 14 and having an acryl resin as the main component. The acryl resin contained in the top coat layer 15 is an acrylic copolymer containing cyclohexyl acrylate as the essential component and having a glass-transition temperature of 80°C or more and an acid value of 50 mgKOH / g or more. The acrylic copolymer is an aqueous emulsion synthesized by emulsion polymerization and having a molecular weight of 100,000 or more, and contains a carbodiimide-based compound as the hardener component.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a decorative sheet used for the interior and exterior decoration of buildings, fittings, surfaces of furniture, etc., and a method for producing the decorative sheet. [Background technology]

[0002] In recent years, with the diversification of usage environments, there has been an increasing demand for decorative sheets with higher functionality. Generally, it is difficult to simultaneously achieve high functionality in all physical properties, such as weather resistance, scratch resistance, and stain resistance. For this reason, a top coat layer is often provided on the outermost surface of a decorative sheet for the purpose of imparting functionality. When imparting weather resistance to this top coat layer, it is common to add weather resistance agents such as ultraviolet absorbers and light stabilizers, and examples of prior art include decorative sheets described in Patent Document 1. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-30998 Summary of the Invention [Problem to be solved by the invention]

[0004] Decorative sheets are also being used for exterior applications, and improving weather resistance in particular is a challenge. To improve weather resistance, it is common to add weather resistance agents such as ultraviolet absorbers and light stabilizers to the top coat layer. Increasing the amount of these agents added generally improves weather resistance, but this can potentially reduce physical properties such as scratch resistance and stain resistance of the top coat layer. In other words, in conventional decorative sheets, there is a so-called trade-off between improving weather resistance and improving scratch resistance and stain resistance. The present invention aims to provide a decorative sheet that has excellent weather resistance and scratch resistance by specifying the resin composition of the top coat layer, thereby minimizing the amount of weather resistance agent used in combination, without compromising other performance properties, and a method for producing such a decorative sheet. [Means for solving the problem]

[0005] The inventors discovered the present invention by studying the composition of the acrylic resin used in the top coat layer with the aim of further improving the weather resistance and scratch resistance of the decorative sheet. In order to solve the above problems, one aspect of the present invention provides a decorative sheet comprising a polyolefin substrate, a design layer formed on the polyolefin substrate, an anchor coat layer formed on the design layer, a transparent resin layer formed on the anchor coat layer and primarily composed of polypropylene, and a top coat layer formed on the transparent resin layer and primarily composed of acrylic resin, wherein the acrylic resin of the top coat layer is an acrylic copolymer containing cyclohexyl acrylate as an essential component, having a glass transition temperature of 80°C or higher, an acid value of 50 mgKOH / g or higher, the acrylic copolymer being an aqueous emulsion synthesized by emulsion polymerization and having a molecular weight of 100,000 or higher, and containing a carbodiimide compound as a curing agent. Specifically, the acrylic polymer (acrylic resin) of the top coat layer is a polymer containing cyclohexyl acrylate as an essential component, having a glass transition temperature of 80°C or higher, an acid value of 50 mgKOH / g or higher, and a molecular weight of 100,000 or higher, and the top coat layer contains a carbodiimide compound as a curing agent. [Effects of the Invention]

[0006] According to one aspect of the present invention, by specifying the resin composition of the top coat layer, it is possible to provide a decorative sheet with excellent weather resistance and scratch resistance without compromising other performance properties, as well as a method for producing such a decorative sheet. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a schematic cross-sectional view illustrating the configuration of a decorative sheet according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0008] Next, an embodiment of the present invention will be described with reference to the drawings. The drawings are schematic, and the relationship between thickness and planar dimensions, the thickness ratio of each layer, etc. may differ from the actual ones. Therefore, specific thicknesses and dimensions should be determined by taking the following description into consideration. Furthermore, the embodiments shown below are merely examples of devices and methods for embodying the technical concept of the present invention, and the technical concept of the present invention does not limit the materials, shapes, structures, arrangements, etc. of the components to those described below. The technical concept of the present invention can be modified in various ways within the technical scope defined by the claims.

[0009] [Overall composition of decorative sheet] 1, a decorative sheet 10 according to an embodiment of the present invention (hereinafter referred to as this embodiment) comprises a substrate layer 11, a design layer 12, an anchor layer 13, a transparent resin layer 14, and a top coat layer 15 laminated in this order. The structure of each of the above-mentioned layers will be described below.

[0010] (Base material layer 11) The substrate layer 11 is a layer composed of a polyolefin substrate, i.e., a substrate containing polyolefin or a substrate containing only polyolefin. Examples of polyolefins that constitute the substrate layer 11 include polyethylene, polypropylene, and polybutylene, with polyethylene being the most preferred. By using a polyolefin substrate as the substrate layer 11, it is possible to reduce the generation of harmful gases and the like during disposal. Furthermore, by using a substrate containing polyethylene or a substrate containing only polyethylene as the substrate layer 11, it is possible to further reduce the generation of harmful gases and the like during disposal.

[0011] As described above, the base layer 11 is preferably a layer made of a polyolefin base material, but may be a layer made of other materials. Below, a base layer 11 made of a material other than polyolefin will be described. The base material layer 11 can be made of any material selected from paper, synthetic resin, synthetic resin foam, rubber, nonwoven fabric, synthetic paper, metal foil, etc. Examples of paper include tissue paper, titanium paper, and resin-impregnated paper. Examples of synthetic resins include polystyrene, polycarbonate, polyester, polyamide, ethylene-vinyl acetate copolymer, polyvinyl alcohol, and acrylic. Examples of rubber include ethylene-propylene copolymer rubber, ethylene-propylene-diene copolymer rubber, styrene-butadiene copolymer rubber, styrene-isoprene-styrene block copolymer rubber, styrene-butadiene-styrene block copolymer rubber, and polyurethane. Examples of nonwoven fabrics include organic and inorganic nonwoven fabrics. Examples of metals for the metal foil include aluminum, iron, gold, and silver. To improve adhesion to adjacent layers, the substrate layer 11 may be subjected to surface treatment such as corona treatment, plasma treatment, ozone treatment, electron beam treatment, ultraviolet treatment, or dichromate treatment.

[0012] (Picture layer 12) The design layer 12 is a layer of a design printed on the base layer 11 using ink.

[0013] The ink forming the design layer 12 contains a binder, which can be selected from, for example, soluble nitrocellulose, cellulose, vinyl chloride-vinyl acetate copolymer, polyvinyl butyral, polyurethane, acrylic, polyester, and the like, either alone or modified versions thereof. The binder may be aqueous, solvent-based, or emulsion-type, and may be a one-component type or a two-component type that uses a curing agent. Furthermore, the design layer 12 may be formed using a curable ink, which is cured by exposure to ultraviolet light, electron beams, or the like. The most common method is to use a urethane-based ink and cure it with an isocyanate to form the design layer 12. In addition to the binder described above, pigments contained in ordinary inks, colorants such as dyes, extender pigments, solvents, various additives, etc. may be added to the design layer 12. Examples of versatile pigments include condensed azo, insoluble azo, quinacridone, isoindoline, anthraquinone, imidazolone, cobalt, phthalocyanine, carbon, titanium oxide, iron oxide, and pearl pigments such as mica.

[0014] The curing agent used to cure the urethane-based ink is not particularly limited, and can be appropriately selected from commercially available curing agents including, for example, hexamethylene diisocyanate, isophorone diisocyanate, tolylene diisocyanate, xylylene diisocyanate and its hydrogenated products, or diphenylmethane diisocyanate and its hydrogenated products.

[0015] In addition to applying ink, it is also possible to apply a design to the pattern layer 12 by vapor deposition or sputtering of various metals. It is also preferable that a light stabilizer be added to the ink described above, which can suppress deterioration of the decorative sheet 10 itself caused by light degradation of the ink, thereby extending the life of the decorative sheet 10. In order to effectively suppress deterioration of the decorative sheet 10 itself caused by light degradation of the ink, it is preferable to set the content of the light stabilizer within the range of 1% by mass or more and 5% by mass or less of the total mass of the ink.

[0016] There is no particular limitation on the method for forming the design layer 12. The design layer 12 can be formed using a common printing method such as gravure printing, offset printing, screen printing, flexographic printing, or inkjet printing.

[0017] (Anchor layer 13) The anchor layer (anchor coat layer) 13 is a layer provided to enhance the adhesion between the design layer 12 and the transparent resin layer 14. The material constituting the anchor layer 13 is not particularly limited, and can be selected appropriately from resin materials such as urethane-based, acrylic-based, acrylic silicone-based, fluorine-based, epoxy-based, and polyester-based materials, and can be made into ink by selecting a material that has excellent adhesion between the pattern layer 12 and the transparent resin layer 14.

[0018] There is no particular limitation on the method for forming the anchor layer 13. The anchor layer 13 can be formed using a common coating method such as gravure coating, microgravure coating, comma coating, knife coating, or die coating.

[0019] (Transparent resin layer 14) The transparent resin layer 14 is a layer provided to improve the strength (mechanical strength) of the entire decorative sheet 10, etc. The transparent resin layer 14 is a layer whose main component is polypropylene. Here, "main component" means that the mass of polypropylene accounts for 50 mass % or more of the total mass of the transparent resin layer 14.

[0020] The transparent resin layer 14 may contain a resin component other than polypropylene. As a material other than polypropylene that can be contained in the transparent resin layer 14, an olefin-based resin is preferably used, and in addition to polyethylene, polybutene, etc., α-olefins (for example, propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, tridecene, 1-tetradecene, 1-pentadecene, 1-hexadecene, 1-heptadecene, 1-octadecene, 1-nonadecene, 1-eicosene, 3-methyl-1-butene, 3-methyl-1-pentene, 3-ethyl-1-pentene, 4-methyl-1-pentene, 4-methyl-1-hexene, 4,4-dimethyl-1-pent ... Examples of such copolymers include homopolymers or copolymers of two or more types of α-olefins (e.g., ethylene, 4-ethyl-1-hexene, 3-ethyl-1-hexene, 9-methyl-1-decene, 11-methyl-1-dodecene, 12-ethyl-1-tetradecene), as well as copolymers of ethylene or α-olefins with other monomers, such as ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, ethylene-methyl methacrylate copolymer, ethylene-ethyl methacrylate copolymer, ethylene-butyl methacrylate copolymer, ethylene-methyl acrylate copolymer, ethylene-ethyl acrylate copolymer, and ethylene-butyl acrylate copolymer.

[0021] Furthermore, in order to improve the surface strength of the decorative sheet 10, it is preferable to use highly crystalline polypropylene as the resin that constitutes the transparent resin layer 14. In other words, it is preferable that the transparent resin layer 14 is a layer whose main component is highly crystalline polypropylene.

[0022] The transparent resin layer 14 may also contain, as weather resistance agents, an ultraviolet absorber having a triazine skeleton and a light stabilizer having a NOR skeleton. The transparent resin layer 14 may also contain, for example, a benzophenone-based ultraviolet absorber and a hindered amine-based light stabilizer as weather resistance agents. The benzophenone-based ultraviolet absorber is preferably present in an amount ranging from 0.1% by mass to 5% by mass, based on the total mass of the transparent resin layer 14. The hindered amine-based light stabilizer is preferably present in an amount ranging from 0.1% by mass to 5% by mass, based on the total mass of the transparent resin layer 14.

[0023] If necessary, various additives such as a heat stabilizer, a light stabilizer, an antiblocking agent, a catalyst scavenger, a colorant, a light scattering agent, and a gloss adjuster may be added to the transparent resin layer 14. Generally, phenol-based, sulfur-based, phosphorus-based, hydrazine-based, or other heat stabilizers are added, and hindered amine-based, or other light stabilizers are added in any combination.

[0024] The method for forming the transparent resin layer 14 is not particularly limited. The transparent resin layer 14 can be formed using a common method such as calendar film formation or extrusion film formation. Among these, extrusion molding is preferred as a method for forming the transparent resin layer 14. Extrusion molding allows the transparent resin layer 14 to be formed uniformly. Furthermore, in order to provide a design, the transparent resin layer 14 may be provided with surface irregularities. Examples of methods for providing the irregularities include a method of subjecting the transparent resin layer 14 to hot embossing after extrusion molding, and a method of subjecting the extrusion layer 14 to embossing simultaneously with extrusion molding using a cooling roll provided with irregularities.

[0025] (Topcoat layer 15) The topcoat layer 15 is a layer provided to impart functions such as weather resistance, scratch resistance, stain resistance, and designability to the decorative sheet 10. The top coat layer 15 is a layer whose main component is an acrylic polymer. Here, "main component" means that the mass of the acrylic polymer accounts for 50% by mass or more of the total mass of the top coat layer 15. The material constituting the topcoat layer 15 is not particularly limited, and for example, an ionizing radiation curable resin or a thermosetting resin is preferably used.

[0026] As the ionizing radiation curable resin, for example, known materials such as various monomers and commercially available oligomers can be used. For example, it is preferable to use polyfunctional monomers such as pentaerythritol triacrylate (PET3A), pentaerythritol tetraacrylate (PET4A), trimethylolpropane triacrylate (TMPTA), dipentaerythritol hexaacrylate (DPHA), etc., polyfunctional oligomers such as Shikou UV-1700B (manufactured by Nippon Synthetic Chemical Industry Co., Ltd.), or mixtures thereof.

[0027] The thermosetting resin is preferably formed by thermally curing a polymer containing a carboxyl group described below and a carbodiimide compound as a curing agent component. The polymer containing a carboxyl group is not particularly limited, but may be used to impart mechanical properties to the top coat layer 15 by elongating the molecular structure, for example. The polymer containing a carboxyl group is appropriately selected from, for example, various acrylic polymers, various polyesters, various polyethers, various polycarbonates, various polyurethanes, etc.

[0028] Among the above-mentioned resins, the most preferable material for forming the top coat layer 15 is an acrylic polymer containing cyclohexyl acrylate as an essential component.

[0029] The carbodiimide compound serving as the curing agent component is not particularly limited as described above, but examples thereof include diisopropylcarbodiimide, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride, N-3-dimethylaminopropyl-N'-ethylcarbodiimide, N-tert-butyl-N'-ethylcarbodiimide, N-cyclohexyl-N'-2-morpholinoethylcarbodiimide meso-p-toluenesulfonic acid, and N,N'-di-tert-butylcarbodiimide. The content (mass) of the carbodiimide compound is preferably in the range of 3 to 20 parts by mass, more preferably 4 to 15 parts by mass, and most preferably 5 to 10 parts by mass, per 100 parts by mass of the total acrylic polymer containing cyclohexyl acrylate as an essential component. If the content of the carbodiimide compound is less than 3 parts by mass, the content of the carbodiimide compound is too low, which may prevent the acrylic polymer from curing sufficiently, resulting in an insufficient hardness of the top coat layer 15. If the content of the carbodiimide compound is more than 20 parts by mass, the content of the acrylic polymer will be relatively low, and the amount of carbodiimide compound that does not contribute to the curing reaction will be increased, resulting in an insufficient hardness of the top coat layer 15.

[0030] In addition, the resin constituting the top coat layer 15 in this embodiment is preferably an acrylic copolymer having a glass transition temperature of 80°C or higher and an acid value of 50 mgKOH / g or higher, which is crosslinked with a curing agent. If the glass transition temperature is 80°C or lower, the surface hardness of the top coat layer 15 may decrease, and scratch resistance may also decrease. If the acid value is 50 mgKOH / g or lower, the crosslink density after curing may be low, and scratch resistance may also decrease. The upper limit of the glass transition temperature of the resin constituting the top coat layer 15 in this embodiment is not particularly limited, but is preferably, for example, 200° C. or lower. If the glass transition temperature of the resin constituting the top coat layer 15 in this embodiment exceeds 200° C., the surface hardness of the top coat layer 15 may become too high, making it vulnerable to external impacts. In addition, the upper limit of the acid value of the resin constituting the top coat layer 15 in this embodiment is not particularly limited, but is preferably, for example, 200 mgKOH / g or less. If the acid value of the resin constituting the top coat layer 15 in this embodiment exceeds 200 mgKOH / g, the crosslink density after curing may become too high, which may make the layer vulnerable to external impacts.

[0031] The acrylic resin (acrylic polymer) contained in the top coat layer 15 is preferably applied in the form of an aqueous emulsion together with the curing agent. If the acrylic resin contained in the top coat layer 15 is applied in the form of an aqueous emulsion together with the curing agent, a resin coating with a high molecular weight is obtained, and the surface hardness of the top coat layer 15 is improved, as well as the contamination resistance.

[0032] A filler is generally added to the top coat layer 15 as a gloss adjuster, and can be either an organic material such as acrylic beads or silicone beads, or an inorganic material such as alumina or silica, but silica (silica filler), which is an inorganic material, is preferred in terms of scratch resistance. Silica exhibits better scratch resistance than other materials, which is thought to be due to its moderate hardness. The silica preferably has a spherical shape and a pore volume of 1 mL / g or more. Silica with a large pore volume (specifically, 1 mL / g or more) tends to have excellent scratch resistance, which is thought to be due to the influence of the binder resin component impregnating the silica pores. Furthermore, silica with a large pore volume has a significant effect of reducing gloss and the required amount of gloss adjuster. The content of the gloss adjuster is preferably in the range of 1% by mass to 30% by mass, and more preferably in the range of 2% by mass to 20% by mass, relative to the total mass of the top coat layer 15. In other words, in this embodiment, when silica (silica filler) with a pore volume of 1 mL / g or more is added as a gloss adjuster, the content of the silica is preferably in the range of 1% by mass to 30% by mass, and more preferably in the range of 2% by mass to 20% by mass, relative to the total mass of the top coat layer 15.

[0033] Furthermore, the silica preferably has a spherical shape and an oil content of, for example, 100 mL to 200 mL / 100 g. Silica tends to exhibit excellent scratch resistance when the oil content is large (specifically, 100 mL to 200 mL / 100 g), which is thought to be due to the increased affinity between the binder resin component and the silica surface. Furthermore, silica with a large oil content has a significant effect of reducing gloss and the required amount of gloss adjuster. Therefore, in this embodiment, when silica (silica filler) with an oil content of 100 mL to 200 mL / 100 g is added as a gloss adjuster, the content of the silica is preferably in the range of 1% by mass to 30% by mass, more preferably 2% by mass to 20% by mass, based on the total mass of the top coat layer 15.

[0034] In order to impart various functions to the top coat layer 15 constituting the decorative sheet 10 of this embodiment, various additives such as heat stabilizers, antiblocking agents, catalyst scavengers, colorants, light scattering agents, antibacterial agents, and antifungal agents may be blended therein.

[0035] The antibacterial agent is preferably a silver-supported compound. Examples of the antibacterial agent that can be used include inorganic antibacterial agents such as antibacterial zeolite, antibacterial apatite, and antibacterial zirconia, which are formed by incorporating metal ions (silver ions, copper ions, or zinc ions) into inorganic compounds such as zeolite, apatite, and zirconia. Organic antibacterial agents such as zinc pyridinone, 2-(4-thiazolyl)-benzimidazole, 10,10-oxybisphenoxanodine, organic titanium sulfur halogen compounds, and pyridine-2-thiol oxide can also be used, but silver-based antibacterial agents (antibacterial agents containing silver-based materials) are superior in terms of antibacterial effect.

[0036] The antibacterial agent may also be configured such that a silver-based material is supported on an inorganic material. Although "glass" is used as the "inorganic material," the "inorganic material" is not limited to glass. By supporting the silver component (silver-based material) on an inorganic substance, it is possible to prevent the silver component from falling off over time and from transferring to the polyvinyl chloride layer. The antibacterial agent may also contain finely ground silver. Specific examples of antibacterial agents that can be used in this embodiment include diiodomethyl complex (trade name: PBM-H7, manufactured by MIC), calcined calcium hydroxide (trade name: Scallow, manufactured by Bacteriological Research Institute), and Biocide TB-B100 (trade name) (manufactured by Taisho Technos Co., Ltd.).

[0037] (Relationship between average particle size of antibacterial agent and amount added) To obtain antibacterial performance, a relatively large amount of antibacterial agent is preferable, while a relatively small amount of antibacterial agent is preferable for surface strength, as a large amount of antibacterial agent cannot provide sufficient surface strength. Specifically, for example, when the thickness D of the top coat layer 15 is 3 μm or more and 20 μm or less, the amount of antibacterial agent added is preferably 3 mass % or more and 20 mass % or less with respect to the total mass of the top coat layer 15. If the amount of antibacterial agent added is less than 3 mass %, antibacterial performance cannot be exhibited, and if it is more than 20 mass %, surface strength cannot be ensured.

[0038] The average particle size (μm) of the antibacterial agent is preferably 0.1 to 1.0 times, and more preferably 0.3 to 0.4 times, the thickness D (μm) of the top coat layer 15. If the average particle size of the antibacterial agent is less than 0.1 times the thickness D of the top coat layer 15, the dispersibility of the antibacterial agent decreases, making it impossible to obtain a sufficient antibacterial effect, and if it exceeds 1.0 times, the surface hardness decreases. Specifically, the average particle size (D50) of the antibacterial agent added to the top coat layer 15 is preferably 2 μm or more and 20 μm or less, and more preferably 5 μm or more and 12 μm or less.

[0039] Furthermore, if the above-mentioned antibacterial agent having an average particle size (D50) of 0.1 to 1.0 times the thickness D of the top coat layer 15 is defined as the "first antibacterial agent," and the antibacterial agent having an average particle size (D50) of 1.4 to 1.6 times the thickness D of the top coat layer 15 is defined as the "second antibacterial agent," the top coat layer 15 may contain both the first antibacterial agent and the second antibacterial agent. In other words, the top coat layer 15 may contain two or more types of antibacterial agents with different average particle sizes. By including the second antibacterial agent, the second antibacterial agent protrudes from the surface of the top coat layer 15, and the second antibacterial agent exerts its antibacterial effect.

[0040] Furthermore, the ratio of the amount of the first antibacterial agent added to the amount of the second antibacterial agent added (amount of first antibacterial agent added / amount of second antibacterial agent added) may be 1.5 or more and 10 or less, more preferably 2 or more and 8 or less, and even more preferably 3 or more and 5 or less. Within the above numerical range, a high antibacterial effect can be obtained. Furthermore, the first antibacterial agent and the second antibacterial agent may be the same type of antibacterial agent (for example, the same type of silver-based antibacterial agent), or may be different types of antibacterial agents.

[0041] Although the case where an antibacterial agent is added to the top coat layer 15 has been described, a silver-based antibacterial agent may also be added to the transparent resin layer 14 as an antibacterial agent. This allows the antibacterial performance to be maintained even when the transparent resin layer 14 is exposed due to wear or the like. The amount of the antibacterial agent added to the transparent resin layer 14 is preferably 1 mass % or more and 30 mass % or less with respect to the total mass of the transparent resin layer 14. The average particle size of the antibacterial agent is preferably 2 μm or more and 20 μm or less, and more preferably 5 μm or more and 12 μm or less. When an antibacterial agent is added to the transparent resin layer 14, it is preferable not to add a component containing chlorine to the transparent resin layer 14.

[0042] In the above-described embodiment, an antibacterial agent is added to the top coat layer 15. However, this antibacterial agent may be an antiviral agent having antiviral properties. That is, in the present embodiment, an antiviral agent may be added to the top coat layer 15 instead of an antibacterial agent, or both an antibacterial agent and an antiviral agent may be added to the top coat layer 15. When an antiviral agent is added to the top coat layer 15, the amount added, the average particle size, and the like may be the same as those of the antibacterial agent described above. Furthermore, as with the antibacterial agent, two or more types of antiviral agents having different average particle sizes may be added to the top coat layer 15.

[0043] Furthermore, the top coat layer 15 has a crosslinked structure. The migration of the antibacterial agent containing a silver component can be blocked by forming the top coat layer 15 into a crosslinked structure. The crosslinked structure can be crosslinked by high energy irradiation such as ultraviolet light or an electron beam, or by heat, to increase the degree of crosslinking, thereby further inhibiting the migration of the antibacterial agent containing a silver component.

[0044] If necessary, an ultraviolet absorber or a light stabilizer can be added to the top coat layer 15 as a weathering agent. Examples of ultraviolet absorbers include benzotriazoles, benzoates, benzophenones, and triazines. Light stabilizers include hindered amines, and these are typically added in any combination. That is, the top coat layer 15 may contain, as weathering agents, an ultraviolet absorber having a triazine skeleton and a light stabilizer having a NOR skeleton. The content of the ultraviolet absorber having a triazine skeleton in the top coat layer 15 is preferably in the range of 1% to 15% by mass, and more preferably in the range of 3% to 6% by mass, relative to the total mass of the top coat layer 15. The content of the light stabilizer having a NOR skeleton in the top coat layer 15 is preferably in the range of 1% to 10% by mass, and more preferably in the range of 3% to 6% by mass, relative to the total mass of the top coat layer 15. When the content of the ultraviolet absorber having a triazine skeleton and the content of the light stabilizer having a NOR skeleton are within the above numerical ranges, the weather resistance can be further improved while maintaining the basic functions of the top coat layer 15, such as scratch resistance and contamination resistance.

[0045] Furthermore, the content of the ultraviolet absorber having a triazine skeleton in the top coat layer 15 is preferably greater than the content of the light stabilizer having a NOR skeleton, and is preferably within the range of 1.5 to 3 times. If the content of the ultraviolet absorber having a triazine skeleton is within the above numerical range, the weather resistance can be further improved while maintaining the basic functions of the top coat layer 15, such as scratch resistance and contamination resistance.

[0046] If necessary, a polyethylene wax can be added to the top coat layer 15 as a lubricant. Here, "polyethylene wax" refers to low-molecular-weight polyethylene having a molecular weight of tens of thousands or less. Also, "wax" refers to "(1) a substance that is solid or semi-solid at room temperature and has a melting point of 40°C or higher, and (2) a substance that melts when heated without decomposing and has low viscosity." Examples of polyethylene waxes that can be used include the "Sun Wax" series manufactured by Sanyo Chemical Industries, Ltd. and the "Hi Wax" series manufactured by Mitsui Chemicals, Inc. The content of the polyethylene wax in the top coat layer 15 is preferably, for example, in the range of 1% by mass to 10% by mass, and more preferably in the range of 3% by mass to 6% by mass, relative to the total mass of the top coat layer 15. If the content of the polyethylene wax is within the above numerical range, it is possible to further improve contamination resistance while maintaining the basic functions of the top coat layer 15, such as scratch resistance.

[0047] There are no particular limitations on the method for forming the top coat layer 15. The top coat layer 15 may be formed by applying a coating liquid made from the above-mentioned material by a common method such as gravure coating, microgravure coating, comma coating, knife coating, or die coating, and then curing the coating by a method suited to the material, such as thermal curing or ultraviolet curing. The top coat layer 15 may also be provided after the pattern layer 12 provided on the base layer 11 is bonded to the transparent resin layer 14 via the anchor layer 13 .

[0048] The following describes the thickness of each layer constituting the decorative sheet 10 of this embodiment. Considering printing workability, cost, etc., the thickness of the base layer 11 is preferably in the range of 20 μm to 150 μm, and more preferably in the range of 50 μm to 100 μm. Similarly, in consideration of printing workability, cost, etc., the thickness of the design layer 12 is preferably in the range of 0.5 μm to 10 μm, more preferably in the range of 1 μm to 5 μm. Similarly, in consideration of printing workability, cost, and the like, the thickness of the anchor layer 13 is preferably in the range of 1 μm to 20 μm, and more preferably in the range of 1 μm to 3 μm. Similarly, in consideration of printing workability, cost, and the like, the thickness of the transparent resin layer 14 is preferably in the range of 20 μm to 200 μm, more preferably in the range of 70 μm to 100 μm. Similarly, in consideration of printing workability, cost, and the like, the thickness of the topcoat layer 15 is preferably in the range of 3 μm to 20 μm, and more preferably in the range of 3 μm to 15 μm. Additionally, the total thickness of the decorative sheet 10 is preferably within the range of 45 μm or more and 250 μm or less. If the total thickness of the decorative sheet 10 is less than 45 μm, the strength of the entire decorative sheet 10 will be insufficient, and if the decorative sheet 10 is manufactured in-line, for example, there is a risk that the decorative sheet 10 will be damaged during manufacturing. If the total thickness of the decorative sheet 10 exceeds 250 μm, there is a risk that the flexibility of the entire decorative sheet 10 will decrease, and cracks and whitening will occur in the decorative sheet 10.

[0049] [Manufacturing method of decorative sheet] A method for producing the decorative sheet 10 according to this embodiment will now be briefly described. First, the pattern layer 12 is formed on the base layer 11 containing polyolefin. Next, the anchor layer 13 is formed on the pattern layer 12. Next, a transparent resin layer 14 containing polypropylene as a main component is formed on the anchor layer 13 by extrusion molding to a thickness of 70 μm or more and 100 μm or less. Next, on the transparent resin layer 14, a top coat layer 15 containing an acrylic resin as a main component is formed to a film thickness of 3 μm or more and 15 μm or less. The top coat layer 15 is made of an acrylic resin with cyclohexyl a The content of cyclohexyl acrylate in the acrylic resin is in the range of 20% by mass to 70% by mass. a The acrylate content (mass) is preferably in the range of 30% by mass to 60% by mass, and more preferably in the range of 40% by mass to 50% by mass, relative to the mass of the acrylic resin. If the cyclohexyl acrylate content is less than 20% by mass, sufficient weather resistance may not be imparted to the top coat layer 15. If the cyclohexyl acrylate content exceeds 70% by mass, sufficient strength may not be imparted to the top coat layer 15.

[0050] In the step of forming the transparent resin layer 14, the surface of the transparent resin layer 14 may be treated so that the wettability index of the surface is 60 dyne or more. The wettability index of the surface of the transparent resin layer 14 can be confirmed using a so-called "wetability reagent."

[0051] In addition, in at least one of the step of forming the anchor layer 13 and the step of forming the topcoat layer 15, each layer may be formed using any one of gravure printing, flexographic printing, and inkjet printing.

[0052] As described above, the manufacturing method for the decorative sheet 10 of this embodiment includes at least the steps of forming, in this order, a substrate layer 11 containing polyolefin, a design layer 12, an anchor layer 13, a transparent resin layer 14 primarily composed of polypropylene, and a top coat layer 15 primarily composed of an acrylic polymer. In the step of forming the top coat layer 15, a top coat layer coating material is applied to the transparent resin layer 14 to form the top coat layer 15. The top coat layer coating material contains an acrylic copolymer containing cyclohexyl acrylate as an essential component, having a glass transition temperature of 80°C or higher and an acid value of 50 mgKOH / g or higher, and a carbodiimide compound as a curing agent. The acrylic copolymer is a polymer with a molecular weight of 100,000 or higher synthesized by emulsion polymerization, and is present in the top coat layer coating material in the form of an aqueous emulsion.

[0053] Examples based on the present invention will be described below.

[0054] Example 1 ~Synthesis of acrylic resin emulsion~ In a four-neck flask equipped with a stirrer, a nitrogen inlet tube, and a reflux condenser, 70 g of methyl methacrylate, 20 g of cyclohexyl methacrylate, and 10 g of methacrylic acid were used as acrylic monomers, 4 g of a copolymer emulsifier (Aqualon AR-10, manufactured by Daiichi Kogyo Seiyaku) as an emulsifier, and 0.25 g of potassium persulfate (manufactured by Kokusan Chemical) as an initiator, and emulsion polymerization was carried out in 300 g of water to obtain a milky-white, translucent acrylic resin emulsion A with a solids content of approximately 25%.

[0055] ~Preparation of coating material for top coat layer~ A coating material for the top coat layer was prepared according to the following formulation. Resin: Acrylic resin emulsion A, 100 parts by mass Hardener: Carbodilite SV-02 (Nisshinbo Chemical), 5.0 parts by mass

[0056] ~Making decorative sheets~ A 55 μm thick polyethylene sheet with opacity was used as the base layer 11, and a 3 μm thick pattern layer 12 was formed on one side of it using a two-component urethane ink (V180, manufactured by Toyo Ink) by gravure printing, and a primer coat composed of the same resin components as the pattern layer 12 was formed on the other side of the base layer 11. An anchor layer 13 was formed on the surface of this pattern layer 12 to a thickness of 2 μm by gravure printing using a dry laminating adhesive (Takelac A540, manufactured by Mitsui Chemicals, Inc.), and a transparent resin layer 14 of 70 μm in thickness was formed on top of this by extrusion lamination using a polypropylene resin containing 0.5% by mass of a benzophenone-based ultraviolet absorber and 0.5% by mass of a hindered amine-based light stabilizer. Furthermore, the above-mentioned coating material for the top coat layer was used to form a top coat layer 15 on the transparent resin layer 14 by gravure coating to a thickness of 7 μm, thereby producing the decorative sheet 10 of Example 1.

[0057] ~Adhesion evaluation~ The adhesiveness of the decorative sheet 10 was evaluated under the following conditions, and the state of the sample after the test was visually evaluated. <Test conditions> The surface of the topcoat layer was cross-cut with a cutter and a cellophane tape peeling test was carried out. <Evaluation criteria> 〇: No peeling △: Partial peeling ×: Easily peeled off In this evaluation, "〇" was considered a pass.

[0058] ~Scratch resistance evaluation~ The scratch resistance of the decorative sheet 10 described above was evaluated under the following conditions, and the state of the sample after the test was visually evaluated. <Test conditions> Hoffman scratch test; BYK Hoffman scratch hardness tester Test conditions: 100 to 1000g load, in 100g increments <Evaluation criteria> 〇: No scratches with a load of 500g or more △: Scratches with a load of 100g or more but less than 500g, no damage ×: Scratches occur even with a load of less than 100g In this evaluation, "〇" was considered a pass.

[0059] ~Weather resistance evaluation~ The weather resistance of the decorative sheet 10 described above was evaluated under the following conditions, and the state of the sample after the test was visually evaluated. <Test conditions> Super xenon tester; Toyo Seiki Atlas Weather-O-Meter Ci4000 Test conditions: 180W light irradiation, 12min rainfall / 120min cycle, 500hr <Evaluation criteria> 〇: No change before and after the test △: Whitening was observed in some areas of the sample after the test, but the whitening was at a level that did not pose a problem in use. ×: Whitening and partial peeling were observed on the sample after the test. The whitening and peeling were at a level that was problematic for use. In this evaluation, "〇" was considered a pass.

[0060] <Example 2> The evaluation was carried out in the same manner as in Example 1, except that the coating material for the top coat layer was formulated as follows. ~Preparation of coating material for top coat layer~ A coating material for the top coat layer was prepared according to the following formulation. Resin: Acrylic resin emulsion A, 100 parts by mass Curing agent: Carbodilite SV-02 (manufactured by Nisshinbo Chemical), 10 parts by mass Gloss adjuster (inorganic particles): Silohobic 702 (Fuji Silysia Chemical Co., Ltd.), 8 parts by mass

[0061] Example 3 The evaluation was carried out in the same manner as in Example 1, except that the coating material for the top coat layer was formulated as follows. ~Preparation of coating material for top coat layer~ A coating material for the top coat layer was prepared according to the following formulation. Resin: Acrylic resin emulsion A, 100 parts by mass Curing agent: Carbodilite SV-02 (manufactured by Nisshinbo Chemical), 10 parts by mass UV absorber: Tinuvin 400DW (BASF), 4 parts by mass Light stabilizer: Tinuvin 123DW (BASF), 2 parts by mass

[0062] Example 4 The evaluation was carried out in the same manner as in Example 1, except that the coating material for the top coat layer was formulated as follows. ~Preparation of coating material for top coat layer~ A coating material for the top coat layer was prepared according to the following formulation. Resin: Acrylic resin emulsion A, 100 parts by mass Curing agent: Carbodilite SV-02 (manufactured by Nisshinbo Chemical), 10 parts by mass Lubricant: AQUAMAT263 (manufactured by BYK), 6 parts by weight

[0063] <Example 5> The evaluation was carried out in the same manner as in Example 1, except that the coating material for the top coat layer was formulated as follows. ~Preparation of coating material for top coat layer~ A coating material for the top coat layer was prepared according to the following formulation. Resin: Acrylic resin emulsion A, 100 parts by mass Curing agent: Carbodilite SV-02 (manufactured by Nisshinbo Chemical), 10 parts by mass Antibacterial agent: Scallow (manufactured by Antibacterial Laboratory), 0.5 parts by weight

[0064] Example 6 The evaluation was carried out in the same manner as in Example 1, except that the coating material for the top coat layer was prepared according to the following formulation and the decorative sheet was prepared according to the following steps. ~Preparation of coating material for top coat layer~ A coating material for the top coat layer was prepared according to the following formulation. Resin: Acrylic resin emulsion A, 100 parts by mass Curing agent: Carbodilite SV-02 (manufactured by Nisshinbo Chemical), 10 parts by mass Gloss adjuster (inorganic particles): Silohobic 702 (Fuji Silysia Chemical Co., Ltd.), 8 parts by mass UV absorber: Tinuvin 400DW (BASF), 4 parts by mass Light stabilizer: Tinuvin 123DW (BASF), 2 parts by mass Lubricant: AQUAMAT263 (manufactured by BYK), 6 parts by weight Antibacterial agent: Scallow (manufactured by Antibacterial Laboratory), 0.5 parts by weight

[0065] <Comparative Example 1> Synthesis of acrylic resin Evaluation was carried out in the same manner as in Example 1, except that the following formulation was used. ~Synthesis of acrylic resin solution~ In a four-neck flask equipped with a stirrer, a nitrogen inlet tube, and a reflux condenser, 70 g of methyl methacrylate, 20 g of cyclohexyl methacrylate, and 10 g of methacrylic acid were used as acrylic monomers, and 3 g of azobisisobutyronitrile (manufactured by Tokyo Chemical Industry Co., Ltd.) was used as an initiator, and solution polymerization was carried out in 300 g of ethyl acetate to obtain a transparent, viscous acrylic resin solution X with a solids content of approximately 25%.

[0066] ~Preparation of coating material for top coat layer~ A coating material for the top coat layer was prepared according to the following formulation. Resin: Acrylic resin solution X, 100 parts by weight Hardener: Carbodilite SV-02 (Nisshinbo Chemical), 5.0 parts by mass

[0067] <Comparative Example 2> Synthesis of acrylic resin emulsion Evaluation was carried out in the same manner as in Example 1, except that the following formulation was used. ~Synthesis of acrylic resin emulsion~ In a four-neck flask equipped with a stirrer, a nitrogen inlet tube, and a reflux condenser, 75 g of methyl methacrylate, 20 g of cyclohexyl methacrylate, and 5 g of methacrylic acid were used as acrylic monomers, 4 g of a copolymer emulsifier (Aqualon AR-10, manufactured by Daiichi Kogyo Seiyaku) as an emulsifier, and 0.25 g of potassium persulfate (manufactured by Kokusan Chemical) as an initiator, and emulsion polymerization was carried out in 300 g of water to obtain a milky-white, translucent acrylic resin emulsion B with a solids content of approximately 25%.

[0068] ~Preparation of coating material for top coat layer~ A coating material for the top coat layer was prepared according to the following formulation. Resin: Acrylic resin emulsion B, 100 parts by mass Hardener: Carbodilite SV-02 (Nisshinbo Chemical), 2.5 parts by mass

[0069] <Comparative Example 3> The evaluation was carried out in the same manner as in Example 1, except that an epoxy-based curing agent (EX-614B, manufactured by Nagase ChemteX) was used as the curing agent in the formulation of the coating material for the top coat layer.

[0070] <Comparative Example 4> Synthesis of acrylic resin emulsion Evaluation was carried out in the same manner as in Example 1, except that the following formulation was used. ~Synthesis of acrylic resin emulsion~ In a four-neck flask equipped with a stirrer, a nitrogen inlet tube, and a reflux condenser, 90 g of methyl methacrylate and 10 g of methacrylic acid were used as acrylic monomers, 4 g of a copolymer emulsifier (Aqualon AR-10, manufactured by Daiichi Kogyo Seiyaku) as an emulsifier, and 0.25 g of potassium persulfate (manufactured by Kokusan Chemical) as an initiator, and emulsion polymerization was carried out in 300 g of water to obtain a milky-white, translucent acrylic resin emulsion C with a solids content of approximately 25%.

[0071] <Comparative Example 5> Synthesis of acrylic resin emulsion Evaluation was carried out in the same manner as in Example 1, except that the following formulation was used. ~Synthesis of acrylic resin emulsion~ In a four-neck flask equipped with a stirrer, a nitrogen inlet tube, and a reflux condenser, 70 g of ethyl acrylate, 20 g of cyclohexyl methacrylate, and 10 g of methacrylic acid were used as acrylic monomers, 4 g of a copolymer emulsifier (Aqualon AR-10, manufactured by Daiichi Kogyo Seiyaku) as an emulsifier, and 0.25 g of potassium persulfate (manufactured by Kokusan Chemical) as an initiator, and emulsion polymerization was carried out in 300 g of water to obtain a milky-white, translucent acrylic resin emulsion D with a solids content of approximately 25%.

[0072] [Table 1]

[0073] As shown in Table 1, this example provides a decorative sheet having excellent physical properties such as weather resistance and scratch resistance. [Explanation of symbols]

[0074] 10 Decorative Sheet 11 Base material layer 12 Picture layer 13 Anchor Layer 14 Transparent resin layer 15 Topcoat layer

Claims

1. a polyolefin substrate; A design layer formed on the polyolefin substrate; An anchor coat layer formed on the design layer; a transparent resin layer formed on the anchor coat layer and containing polypropylene as a main component; a top coat layer formed on the transparent resin layer and containing an acrylic polymer as a main component, the acrylic polymer is a polymer containing cyclohexyl acrylate as an essential component, having a glass transition temperature of 80°C or higher, an acid value of 50 mgKOH / g or higher, and a molecular weight of 100,000 or higher; The top coat layer contains a carbodiimide compound as a curing agent component, A decorative sheet characterized in that the content of said cyclohexyl acrylate in said acrylic polymer is in the range of 20% by mass or more and 70% by mass or less.

2. 2. The decorative sheet according to claim 1, wherein the top coat layer contains a silica filler as a gloss adjuster.

3. 3. The decorative sheet according to claim 1, wherein the top coat layer contains, as weather resistance agents, an ultraviolet absorber having a triazine skeleton and a light stabilizer having a NOR skeleton.

4. 4. The decorative sheet according to claim 1, wherein the top coat layer contains a polyethylene wax as a lubricant.

5. 5. The decorative sheet according to claim 1, wherein the top coat layer contains fine particles of a silver-carrying compound as an antibacterial agent.

6. The method includes a step of forming a polyolefin substrate, a design layer, an anchor coat layer, a transparent resin layer containing polypropylene as a main component, and a top coat layer containing an acrylic polymer as a main component in this order; In the step of forming the top coat layer, a coating material for a top coat layer is applied onto the transparent resin layer to form the top coat layer; The coating material for the top coat layer includes an acrylic copolymer containing cyclohexyl acrylate as an essential component, having a glass transition temperature of 80°C or higher and an acid value of 50 mgKOH / g or higher, and a carbodiimide compound as a curing agent component, the acrylic copolymer is a polymer having a molecular weight of 100,000 or more that is synthesized by emulsion polymerization, and is present in the coating material for the top coat layer in the form of an aqueous emulsion; A method for producing a decorative sheet, wherein the content of the cyclohexyl acrylate in the acrylic polymer is within the range of 20% by mass or more and 70% by mass or less.

7. A method for manufacturing a decorative sheet according to any one of claims 1 to 5, comprising: The method includes a step of forming a polyolefin substrate, a design layer, an anchor coat layer, a transparent resin layer containing polypropylene as a main component, and a top coat layer containing an acrylic polymer as a main component in this order; In the step of forming the top coat layer, a coating material for a top coat layer is applied onto the transparent resin layer to form the top coat layer; The coating material for the top coat layer includes an acrylic copolymer containing cyclohexyl acrylate as an essential component, having a glass transition temperature of 80°C or higher and an acid value of 50 mgKOH / g or higher, and a carbodiimide compound as a curing agent component, A method for producing a decorative sheet, wherein the acrylic copolymer is a polymer having a molecular weight of 100,000 or more that is synthesized by emulsion polymerization, and is present in the coating material for the top coat layer in the form of an aqueous emulsion.

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