Manufacturing method of decorative sheet

Abstract

To provide a manufacturing method of a decorative sheet capable of preventing air intrusion from occurring even when a rugged shape is applied.SOLUTION: A manufacturing method of a decorative sheet having a rugged shape includes: a preparation step of preparing a substrate sheet; and a shape application step of laminating a transparent resin layer on the substrate sheet and at the same time applying a rugged shape to the transparent resin sheet by an embossment plate. The embossment plate has a plate depth of (plate depth / thickness of the transparent resin layer) 70% or less with regard to a thickness of the transparent resin layer.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] BACKGROUND ART When it is desired to decorate components used in building materials, furniture, home appliances, etc., decorative panels having a decorative sheet with a design attached thereto are generally used.

[0003] In order to impart visual design to such decorative sheets, depressions are sometimes formed by embossing or the like to impart a three-dimensional visual effect.

[0004] For example, Patent Document 1 discloses a decorative floor sheet that is attached to the surface of a veneer decorative floor board, which has veneer attached to a base material, and is characterized in that a transparent protective layer is formed on the surface of a transparent or translucent synthetic resin film, and the synthetic resin film and transparent protective layer are given an embossed uneven shape.

[0005] Patent Document 1 describes laminating a molten polyolefin resin onto a substrate film and simultaneously embossing the film.

[0006] However, with this method, unevenness may also be formed on the side of the molten polyolefin resin that is laminated to the base film, and when the molten polyolefin resin is laminated to the base film, air may get into the unevenness on the side of the molten polyolefin resin that is laminated to the base film and remain there without being able to escape (air bubbles), which could potentially reduce the design. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 2019-60159 Summary of the Invention [Problem to be solved by the invention]

[0008] Therefore, an object of the present invention is to provide a method for producing a decorative sheet that can suppress the occurrence of air bubbles even when an uneven shape is provided. [Means for solving the problem]

[0009] The inventors conducted extensive research to solve the above-mentioned problems and discovered that by setting the thickness of the transparent resin layer laminated to the base sheet and the embossing depth within specific ranges, it is possible to suppress the occurrence of air bubbles and solve the above-mentioned problems, which led to the completion of the present invention.

[0010] In other words, the present invention is a method for manufacturing a decorative sheet having a textured shape, which includes a preparation step of preparing a base sheet, and a shaping step of laminating a transparent resin layer on the base sheet and simultaneously shaping a textured shape into the transparent resin layer using an embossing plate, wherein the value obtained by dividing the plate depth (μm) of the embossing plate by the thickness (μm) of the transparent resin layer is 70% or less.

[0011] In the method for producing a decorative sheet of the present invention, the embossing plate preferably has a plate depth of 10 μm or more and 150 μm or less. The transparent resin layer preferably has a thickness of 40 μm or more and 300 μm or less. The substrate sheet preferably has a thickness of 30 μm or more. It is also preferable to have a coating step of coating an adhesive on the base sheet between the preparing step and the shaping step. Furthermore, it is preferable that the adhesive contains a two-component curing polyurethane resin obtained by mixing a polyol and an isocyanate, and a solvent, and that the adhesive still contains the solvent even after the shaping step. Furthermore, when the transparent resin layer is laminated on the base sheet, the adhesive is preferably in a semi-cured state. The transparent resin layer preferably has a two-layer structure, with the side in contact with the base sheet being made of acid-modified polypropylene and the side opposite to the base sheet being made of random polypropylene and / or homopolypropylene. The acid-modified polypropylene is preferably maleic acid-modified polypropylene. The transparent resin layer preferably contains low-density polyethylene. [Effects of the Invention]

[0012] The present invention can provide a method for producing a decorative sheet that can suppress the occurrence of air bubbles even when an uneven shape is provided. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is an explanatory diagram that schematically shows an example of the shaping step in the method for producing a decorative sheet of the present invention. [Figure 2] FIG. 2 is a cross-sectional view that schematically shows an example of a decorative sheet produced by the decorative sheet production method of the present invention. [Figure 3] FIG. 3 is a cross-sectional view that schematically shows a preferred example of a decorative sheet produced by the decorative sheet production method of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0014] The method for producing the decorative sheet of the present invention will now be described. In the following description, the lower and upper limits of numerical ranges expressed with "to" mean "greater than or equal to" (for example, if α to β, it means greater than or equal to α and less than or equal to β).

[0015] The method for manufacturing a decorative sheet of the present invention is a method for manufacturing a decorative sheet having a concave-convex shape, and comprises a preparation step of preparing a base sheet, and a shaping step of laminating a transparent resin layer on the base sheet and simultaneously shaping a concave-convex shape in the transparent resin layer using an embossing plate, characterized in that the value obtained by dividing the plate depth (μm) of the embossing plate by the thickness (μm) of the transparent resin layer is 70% or less. First, the preparation process will be described.

[0016] <Preparation process> The preparation step is a step of preparing a base sheet.

[0017] (Base sheet) Examples of the base sheet include polyolefin resins such as low-density polyethylene (including linear low-density polyethylene), medium-density polyethylene, high-density polyethylene, ethylene-α-olefin copolymer, homopolypropylene, polymethylpentene, polybutene, ethylene-propylene copolymer, propylene-butene copolymer, ethylene-vinyl acetate copolymer, saponified ethylene-vinyl acetate copolymer, and mixtures thereof; thermoplastic ester resins such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyethylene naphthalate-isophthalate copolymer, polycarbonate, and polyarylate; thermoplastic acrylic resins such as polymethyl methacrylate, polyethyl methacrylate, polyethyl acrylate, and polybutyl acrylate; thermoplastic polyamide resins such as nylon-6 and nylon-66; and polyimide, polyurethane, polystyrene, and acrylonitrile-butadiene-styrene resins. These may be used alone or in combination of two or more. Among these, olefin resins are preferred because they are inexpensive and have excellent printability for the design layer described below.

[0018] The substrate sheet may be colored by adding a coloring agent (pigment or dye) to the substrate sheet. As the colorant, for example, inorganic pigments such as titanium dioxide, carbon black, and iron oxide, organic pigments such as phthalocyanine blue, and various dyes can also be used. These may be selected from known or commercially available materials, and the amount of colorant added may be appropriately determined depending on the desired color tone, etc.

[0019] The substrate sheet may contain various additives, such as fillers, matting agents, foaming agents, flame retardants, lubricants, antistatic agents, antioxidants, ultraviolet absorbers, and light stabilizers, as required.

[0020] The substrate sheet preferably has a thickness of 30 μm or more. By having such a thickness, it is possible to eliminate the influence of the roughness of the adherend surface, which will be described later, and to maintain the smoothness of the surface of the decorative material using the decorative sheet. The upper limit of the thickness of the base sheet is, for example, 300 μm.

[0021] (Picture layer) The substrate sheet may have a pattern layer on one surface. The pattern layer is a layer that imparts decorative properties to the decorative sheet.

[0022] The design layer may be, for example, a design layer formed by printing various patterns using ink and a printing machine, or may be a layer that combines a concealing layer and a design layer.

[0023] By providing the concealing layer, when the above-mentioned base sheet is colored or has color unevenness, it is possible to impart an intended color to the surface and adjust the color. Furthermore, by providing a pattern layer, it is possible to impart to the decorative sheet a pattern such as a wood grain pattern, a marble pattern (e.g., travertine marble pattern) or other stone pattern that imitates the surface of rock, a fabric pattern that imitates a cloth or fabric-like pattern, a tiled pattern, a brickwork pattern, or a combination of these, such as marquetry or patchwork. These design patterns are formed by multi-color printing using the usual process colors of yellow, red, blue, and black, as well as by multi-color printing using special colors in which the individual colors that make up the pattern are prepared.

[0024] The ink composition used for the design layer is a mixture of a binder resin, a colorant such as a pigment or dye, an extender pigment, a solvent, a stabilizer, a plasticizer, a catalyst, a hardener, etc., as appropriate.

[0025] The binder resin is not particularly limited, and preferred examples thereof include urethane resin, acrylic resin, urethane-acrylic resin, urethane-acrylic copolymer resin, vinyl chloride / vinyl acetate copolymer resin, vinyl chloride / vinyl acetate / acrylic copolymer resin, acrylic resin, polyester resin, nitrocellulose resin, etc. Any of these may be used as the binder resin, either alone or in combination of two or more.

[0026] Preferred examples of the colorant include inorganic pigments such as carbon black (ink), iron black, titanium white, antimony white, yellow lead, titanium yellow, red iron oxide, cadmium red, ultramarine blue, and cobalt blue; organic pigments such as quinacridone red, isoindolinone yellow, and phthalocyanine blue; metal pigments consisting of scaly flakes of dyes, aluminum, brass, and the like; and pearlescent pigments consisting of scaly flakes of titanium dioxide-coated mica and basic lead carbonate, and the like. These can be used alone or in combination of two or more.

[0027] The design layer has a feature portion and a non-feature portion. The characteristic part refers to a part that has characteristics that allow the pattern of the pattern layer to be recognized. For example, if the pattern layer has a wood grain pattern, this would be the vessels, knots, annual rings, and spots in the wood grain. If the pattern layer has a stone grain pattern, this would be the pattern (crack pattern) expressed by the stripes and cracks of different crystalline components in the rock. Furthermore, a marking pattern may be provided at the end of the design layer, and this may be used as the characteristic portion. The non-characteristic portion refers to a portion other than the characteristic portion.

[0028] The thickness of the design layer is not particularly limited, but is preferably 0.1 μm or more, and more preferably 0.5 μm or more and 600 μm or less. If the thickness of the design layer is within the above range, the resulting decorative sheet can be imparted with an excellent design and hiding properties.

[0029] Examples of methods for forming the design layer include gravure printing, offset printing, screen printing, flexographic printing, electrostatic printing, inkjet printing, etc. In addition, when forming a hiding layer, examples of various coating methods include roll coating, knife coating, air knife coating, die coating, lip coating, comma coating, kiss coating, flow coating, and dip coating.

[0030] <Formation process> The shaping step is a step of laminating a transparent resin layer on the substrate sheet and simultaneously forming a concave-convex shape in the transparent resin layer using an embossing plate. When the base sheet has the design layer, the transparent resin layer is laminated on the side of the base sheet on which the design layer is provided. The above "simultaneously" means that the steps are carried out in one process, and in the shaping process, the transparent resin layer is laminated on the substrate sheet and an uneven shape is formed in the transparent resin layer.

[0031] FIG. 1 is an explanatory diagram that schematically shows an example of the shaping step in the method for producing a decorative sheet of the present invention. In the shaping process shown in Figure 1, a transparent resin layer 2 extruded by an extrusion mechanism 20 is laminated on the base sheet 1 prepared in the preparation process described above, and at the same time, the transparent resin layer 2 is passed between a pressure roller 30 and an embossing plate 40 to form an uneven shape on the side of the transparent resin layer 2 opposite the base sheet 1.

[0032] (Transparent resin layer) The transparent resin layer is preferably a layer formed from a thermoplastic resin. Examples of the thermoplastic resin include olefin resins such as polyethylene, polypropylene, polybutene, polymethylpentene, and olefin-based thermoplastic elastomers; polyester resins such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, ethylene glycol-terephthalic acid-isophthalic acid copolymer resin, terephthalic acid-ethylene glycol-1,4 cyclohexanedimethanol copolymer resin, and polyester-based thermoplastic elastomers; acrylic resins such as polymethyl (meth)acrylate, methyl (meth)acrylate-butyl (meth)acrylate copolymer resin, and methyl (meth)acrylate-styrene copolymer resin; polycarbonate resin, polyvinyl chloride, polystyrene, and ionomers. Among these, polyethylene or polypropylene is more preferred because of its high tensile strength, excellent chemical resistance, and excellent production process.

[0033] The polyethylene may be a homopolymer of ethylene or a copolymer of ethylene and another comonomer copolymerizable with ethylene (for example, an α-olefin such as propylene, 1-butene, 1-hexene, or 1-octene, vinyl acetate, or vinyl alcohol). Examples of polyethylene resins include high-density polyethylene (HDPE), medium-density polyethylene (MDPE), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), very low-density polyethylene (VLDPE), ultra-high molecular weight polyethylene (UHMWPE), and cross-linked polyethylene (PEX). These polyethylenes may be used alone or in combination of two or more.

[0034] The polypropylene may be a homopolymer of propylene or a copolymer of propylene and another comonomer copolymerizable with propylene (for example, an α-olefin such as ethylene, 1-butene, 1-hexene, or 1-octene; vinyl acetate, vinyl alcohol, or the like). These polypropylenes may be used alone or in combination of two or more.

[0035] The transparent resin layer preferably has a two-layer structure, with the side in contact with the base sheet being made of acid-modified polypropylene and the side opposite to the base sheet being made of random polypropylene and / or homopolypropylene. By making the side in contact with the base sheet from acid-modified polypropylene, adhesion to the base sheet or the adhesive described below can be improved, and air bubbles can be suitably suppressed. On the other hand, by making the side opposite to the base sheet from random polypropylene and / or homopolypropylene, it is possible to improve heat resistance and scratch resistance. From the viewpoint of processability, the random polypropylene is preferably a copolymer of propylene and ethylene.

[0036] The acid-modified polypropylene is preferably maleic acid-modified polypropylene. Maleic acid-modified polypropylene can further improve adhesion to the base sheet or the adhesive described below, and can more suitably suppress air bubbles.

[0037] The transparent resin layer preferably contains low-density polyethylene (LDPE). By including low-density polyethylene (LDPE) in the transparent resin layer, flexibility can be imparted to the transparent resin layer, and when laminated to the base sheet, air can escape, thereby effectively suppressing the occurrence of air bubbles. Low-density polyethylene (LDPE) has a density of 0.910 kg / m 3 More than 0.930kg / m 3 The following polyethylene:

[0038] The low-density polyethylene (LDPE) is preferably contained in an amount of 2 to 10% by mass relative to the total mass of the thermoplastic resin constituting the transparent resin layer.

[0039] The transparent resin layer preferably has a thickness of 40 μm or more and 300 μm or less, and more preferably 60 μm or more and 180 μm or less. Such a thickness makes it possible to form a textured shape sufficient to impart design, and also to obtain excellent scratch resistance and bending workability. The thickness of the transparent resin layer refers to the thickness when laminated onto the base sheet in the shaping process, and means the length from the surface on the side laminated onto the base sheet to the surface opposite the side laminated onto the base sheet.

[0040] When the transparent resin layer is composed of two or more layers, the total thickness of the transparent resin layer is preferably 40 μm or more and 300 μm or less, and more preferably 60 μm or more and 180 μm or less.

[0041] When the transparent resin layer is composed of a plurality of layers, the types of resins forming the layers may be the same or different, and the thicknesses may be the same or different. The method for laminating two or more transparent resin layers is not limited as long as it is a common method, and examples thereof include a dry lamination method and an extrusion lamination method in which molten resin is extruded using a T-die to laminate. A T-die or the like capable of extruding molten resin can be used as the extrusion mechanism described above.

[0042] The transparent resin layer may further contain various additives as needed, such as thermoplastic resins such as urethane resin, polyvinyl acetal resin, polyester resin, polyolefin resin, styrene resin, polyamide resin, polycarbonate resin, acetal resin, vinyl chloride-vinyl acetate copolymer resin, vinyl acetate resin, acrylic resin, and cellulose resin, lubricants such as silicone resin, wax, and fluorine resin, ultraviolet absorbers such as benzotriazole, benzophenone, and triazine, light stabilizers such as hindered amine radical scavengers, and colorants such as dyes and pigments.

[0043] The transparent resin layer may be subjected to surface treatment such as saponification treatment, glow discharge treatment, corona discharge treatment, plasma discharge treatment, ultraviolet (UV) treatment, and flame treatment within the scope of the present invention.

[0044] (Embossed version) In the shaping step, the transparent resin layer is laminated on the base sheet, and simultaneously, an embossing plate is used to form a concave-convex shape in the transparent resin layer.

[0045] The embossing plate has a value obtained by dividing the plate depth (μm) by the thickness (μm) of the transparent resin layer (plate depth / transparent resin layer thickness) of 70% or less. Such a plate depth allows the surface of the transparent resin layer that is laminated to the base sheet to be smooth, reducing air infiltration and thereby suppressing the occurrence of air bubbles. The embossed plate preferably has a plate depth (μm) divided by the thickness (μm) of the transparent resin layer of 50% or less, more preferably 45% or less, even more preferably 40% or less, particularly preferably 35% or less, and most preferably 30% or less. On the other hand, from the viewpoint of imparting sufficient design to the decorative sheet, it is preferable that the embossing plate has a plate depth (μm) divided by the thickness (μm) of the transparent resin layer of 15% or more.

[0046] The embossing plate preferably has a plate depth of 10 μm or more and 150 μm or less, and more preferably has a plate depth of 15 μm or more and 45 μm or less. By setting the plate depth to such a value, it is possible to suitably prevent the occurrence of air bubbles and to impart sufficient design properties to the decorative sheet.

[0047] In the shaping step, for example, a device equipped with an embossing plate, such as a well-known sheet-type or rotary embossing machine, can be used. As the pattern of the embossing plate, it is preferable to appropriately select and use a design that matches the above-mentioned design layer.

[0048] The temperature during the shaping step is not particularly limited, but is preferably a temperature that reduces the disappearance of recesses during thermocompression molding, that is, so-called embossing return, and is, for example, 130 to 160°C. The heating method is not particularly limited, and for example, an infrared heater or the like can be used.

[0049] In the shaping step, it is preferable to simultaneously form the concave and convex shapes using an embossing plate and to perform cooling. The temperature of the embossing plate is, for example, 10 to 20°C.

[0050] In the shaping step, the pressure roll preferably has a surface made of rubber from the viewpoint of forming a more regular uneven shape. The pressure to be applied when laminating the transparent resin layer onto the substrate sheet is not particularly limited, but is, for example, 5 to 10 kg / cm.

[0051] <Coating process> It is preferable to have a coating step of coating an adhesive on the base sheet between the preparing step and the shaping step. The adhesive is cured to form an adhesive layer.

[0052] Examples of the adhesive include polyurethane-based, acrylic-based, polyolefin-based, polyvinyl acetate-based, polyvinyl chloride-based, vinyl chloride-vinyl acetate copolymer, ethylene-acrylic acid copolymer, ionomer, butadiene-acrylonitrile rubber, neoprene rubber, natural rubber, etc. Among these, it is preferable to use a two-component curing polyurethane resin obtained by mixing a polyol (base resin) and an isocyanate (curing agent), and a solvent.

[0053] Preferred examples of the polyol include polyols such as polyethylene glycol, polypropylene glycol, butylene glycol, neopentyl glycol, and 1,6-hexanediol; and polyols having a hydroxyl group as a functional group, such as acrylic polyol, polyester polyol, and polyether polyol. These may be used alone or in combination.

[0054] Examples of the isocyanate that can be used include aromatic isocyanates such as 2,4-tolylene diisocyanate (TDI), xylene diisocyanate (XDI), and naphthalene diisocyanate; and polyisocyanates such as aliphatic (or alicyclic) isocyanates such as 1,6-hexamethylene diisocyanate (HMDI), isophorone diisocyanate (IPDI), methylene diisocyanate (MDI), and hydrogenated tolylene diisocyanate. Also usable are adducts or polymers of these various isocyanates, such as adducts of tolylene diisocyanate and tolylene diisocyanate trimer.

[0055] The ratio of the polyol to the isocyanate is not particularly limited, but for example, the ratio of the isocyanate is 5 to 30 parts by mass per 100 parts by mass of the polyol.

[0056] Examples of the solvent include organic solvents such as aromatic hydrocarbons (toluene, xylene, etc.), esters (butyl acetate, ethyl acetate, methyl acetate, isopropyl acetate, ethylene glycol monoacetate, etc.), ketones (methyl ethyl ketone, methyl isobutyl ketone, acetone, methyl isobutyl ketone, cyclohexanone, etc.), and alcohols (methanol, ethanol, isopropanol, butanol, propylene glycol monomethyl ether, propylene glycol, etc.). The organic solvents may be used alone or in combination of two or more.

[0057] The content of the solvent is preferably 50 to 70% by mass relative to the total mass of the adhesive.

[0058] The adhesive preferably has a viscosity measured with a Zahn Cup No. 3 (manufactured by Rigo Co., Ltd.) of 25 to 35 seconds, more preferably 28 to 32 seconds. By having such a viscosity, the adhesive conforms to the shape of the surface of the transparent resin layer, making it difficult for air to remain, and therefore air leakage can be suitably suppressed.

[0059] The method for applying the adhesive is not particularly limited, but for example, roll coating, comma coating, curtain coating, squeeze coating, blade coating, gravure coating, etc. can be used.

[0060] The adhesive preferably has a thickness of about 0.1 to 30 μm after drying, more preferably about 1 to 5 μm.

[0061] It is preferable that the adhesive contains a solvent even after the shaping step. Even after the shaping step, the adhesive contains a solvent, which allows it to more easily conform to the shape of the surface of the transparent resin layer, thereby making it possible to suitably suppress air bubbles. Whether the adhesive contains a solvent after the shaping step can be confirmed by gas chromatographic analysis (headspace method, in accordance with JIS K 0114:2012).

[0062] When the transparent resin layer is laminated on the base sheet, the adhesive is preferably in a semi-cured state. Even after the shaping step, the adhesive contains a solvent, which allows it to more easily conform to the shape of the surface of the transparent resin layer, thereby making it possible to suitably suppress air bubbles. In this specification, the adhesive being in a "semi-cured state" means that the peel strength measured by T-peel (according to JIS K 6854-3:1999) is 10 N / 25 mm or less.

[0063] If the adhesive contains a solvent or is in a semi-cured state, it can be cured by heating and curing at a temperature of, for example, about 40°C.

[0064] <Coating process> The method for producing a decorative sheet of the present invention may include a coating step of coating a surface protective layer on the transparent resin layer. The coating step is preferably carried out after the shaping step.

[0065] (Surface protective layer) The surface protective layer is a layer that imparts durability (scratch resistance, contamination resistance, weather resistance, etc.) to the resulting decorative sheet, and by having the surface protective layer, it is possible to more effectively protect the pattern layer and effectively prevent deterioration of the design due to scratches. The surface protective layer may be a single layer, or may be a multi-layer structure made of the same or different materials, or may be a suitable mixture of the materials shown below.

[0066] The surface protection layer is not particularly limited, but examples thereof include those made of a two-component curing resin or a crosslinked cured product of an ionizing radiation curing resin composition. The crosslinked and cured product is preferably transparent, and may be translucent or colored as long as it is transparent to the extent that the design layer can be seen.

[0067] As the two-component curing resin, the adhesives mentioned above may be used. As the ionizing radiation-curable resin, for example, an oligomer (hereinafter, so-called prepolymer, macromonomer, etc.) having a radically polymerizable unsaturated bond or a cationically polymerizable functional group in the molecule and / or a monomer having a radically polymerizable unsaturated bond or a cationically polymerizable functional group in the molecule is preferably used. Here, ionizing radiation refers to electromagnetic waves or charged particles having energy capable of polymerizing or crosslinking molecules, and typically includes electron beams (EB) or ultraviolet rays (UV).

[0068] Examples of the oligomer or monomer include compounds having a radically polymerizable unsaturated group such as a (meth)acryloyl group or a (meth)acryloyloxy group, or a cationically polymerizable functional group such as an epoxy group in the molecule. These oligomers and monomers can be used alone or in combination. In this specification, the (meth)acryloyl group refers to an acryloyl group or a methacryloyl group.

[0069] As the oligomer having a radically polymerizable unsaturated group in the molecule, for example, oligomers such as urethane (meth)acrylate, polyester (meth)acrylate, epoxy (meth)acrylate, melamine (meth)acrylate, triazine (meth)acrylate, etc. can be preferably used, and urethane (meth)acrylate oligomers are more preferred. As the molecular weight, those having a molecular weight of about 250 to 100,000 are usually used.

[0070] The monomer having a radically polymerizable unsaturated group in the molecule is preferably, for example, a polyfunctional monomer, more preferably a polyfunctional (meth)acrylate. Examples of the polyfunctional (meth)acrylate include diethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, bisphenol A ethylene oxide-modified di(meth)acrylate, trimethylolpropane tri(meth)acrylate, trimethylolpropane ethylene oxide tri(meth)acrylate, dipentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate {pentafunctional (meth)acrylate}, dipentaerythritol hexa(meth)acrylate {hexafunctional (meth)acrylate}, etc. Here, the polyfunctional monomer refers to a monomer having multiple radically polymerizable unsaturated groups.

[0071] The ionizing radiation curable resin composition further preferably contains an ionizing radiation curable resin component consisting of a urethane acrylate oligomer and a polyfunctional monomer, and it is particularly preferable that the ionizing radiation curable resin component has a urethane acrylate oligomer / polyfunctional monomer (mass ratio) of 6 / 4 to 9 / 1. This mass ratio range allows for more excellent scratch resistance. If necessary, a monofunctional monomer may be used in addition to the ionizing radiation curable resin component. Examples of the monofunctional monomer include methyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and phenoxyethyl (meth)acrylate.

[0072] When the ionizing radiation curable resin composition is crosslinked by ultraviolet light, it is preferable to add a photopolymerization initiator to the ionizing radiation curable resin composition. When the ionizing radiation-curable resin composition is a resin system having a radically polymerizable unsaturated group, acetophenones, benzophenones, thioxanthones, benzoin, and benzoin methyl ethers can be used alone or in combination as the photopolymerization initiator. When the ionizing radiation-curable resin composition is a resin system having a cationically polymerizable unsaturated group, the photopolymerization initiator may be an aromatic diazonium salt, an aromatic sulfonium salt, an aromatic iodonium salt, a methacerone compound, a benzoin sulfonate ester, or the like, either alone or in combination. The amount of these photopolymerization initiators added is about 0.1 to 10 parts by mass per 100 parts by mass of the ionizing radiation-curable resin component.

[0073] The ionizing radiation-curable resin composition may further contain various additives as needed, such as thermoplastic resins such as urethane resin, polyvinyl acetal resin, polyester resin, polyolefin resin, styrene-based resin, polyamide resin, polycarbonate resin, acetal resin, vinyl chloride-vinyl acetate copolymer resin, vinyl acetate resin, acrylic resin, and cellulose-based resin, lubricants such as silicone resin, wax, and fluorine resin, ultraviolet absorbers such as benzotriazole, benzophenone, and triazine, light stabilizers such as hindered amine-based radical scavengers, and colorants such as dyes and pigments.

[0074] As the electron beam source of ionizing radiation, for example, various electron beam accelerators such as Cockcroft-Walton type, Van de Graaf type, resonant transformer type, insulating core transformer type, or linear type, dynamitron type, high frequency type, etc. can be used, which irradiate electrons having an energy of 70 to 1000 keV. The exposure dose of ionizing radiation is preferably, for example, about 1 to 10 Mrad. As the ultraviolet light source of the ionizing radiation, for example, an ultra-high pressure mercury lamp, a high pressure mercury lamp, a low pressure mercury lamp, a carbon arc lamp, a black light, a metal halide lamp, etc. can be used, and the wavelength of the ultraviolet light is usually in the wavelength range of 190 to 380 nm.

[0075] The thickness of the surface protective layer is not particularly limited, but the lower limit is preferably 1 μm, the upper limit is preferably 50 μm, the lower limit is more preferably 10 μm, the upper limit is more preferably 40 μm, the lower limit is even more preferably 13 μm, and the upper limit is even more preferably 35 μm. If the thickness of the surface protection layer is less than 1 μm, it may not be possible to provide sufficient durability (scratch resistance, contamination resistance, weather resistance, etc.), and if it exceeds 50 μm, the transmittance may decrease, reducing the visibility of the pattern on the pattern layer.

[0076] The coating step is not particularly limited, and may involve, for example, applying the ionizing radiation curable resin composition and then irradiating with ionizing radiation. As the coating method, various coating methods such as roll coating, knife coating, air knife coating, die coating, lip coating, comma coating, kiss coating, flow coating, and dip coating can be used.

[0077] <Other> In the method for producing a decorative sheet of the present invention, a primer layer and an adhesive layer may be provided as needed. The primer layer or adhesive layer can be provided between layers, for example, between the base sheet and the pattern layer, between the base sheet and the transparent resin layer, or between the transparent resin layer and the surface protective layer. The adhesive layer can be formed by appropriately selecting the adhesive and the application method described in the application step above.

[0078] The primer layer can be formed by applying a known primer agent, such as a urethane resin primer agent made of an acrylic-modified urethane resin (acrylic urethane resin), a primer agent made of a urethane-cellulose resin (e.g., a two-component curing resin of urethane cellulose nitrate obtained by adding hexamethylene diisocyanate to a mixture of urethane and cellulose nitrate), or a resin primer agent made of an acrylic-urethane block copolymer. The primer agent may contain additives as needed. Examples of additives include fillers such as calcium carbonate and clay, flame retardants such as magnesium hydroxide, antioxidants, lubricants, foaming agents, ultraviolet absorbers, and light stabilizers. The amount of additives added can be appropriately determined depending on the product characteristics.

[0079] The thickness of the primer layer is not particularly limited, but is preferably 0.01 to 10 μm, and more preferably 0.1 to 1 μm.

[0080] The primer layer may be formed by applying the resin-based primer agent and curing it with ionizing radiation or the like. The above coating method and curing method may be appropriately selected from known methods.

[0081] <Decorative sheet> The decorative sheet produced by the method for producing a decorative sheet of the present invention will now be described. FIG. 2 is a cross-sectional view that schematically shows an example of a decorative sheet produced by the decorative sheet production method of the present invention. The decorative sheet 10 produced by the decorative sheet manufacturing method of the present invention has a structure in which a transparent resin layer 2 is laminated on a base sheet 1, and an uneven shape is formed on the side of the transparent resin layer 2 opposite the base sheet 1.

[0082] FIG. 3 is a cross-sectional view that schematically shows a preferred example of a decorative sheet produced by the decorative sheet production method of the present invention. As shown in Figure 3, the decorative sheet 10 manufactured through the above-mentioned coating process has a structure in which an adhesive layer 3 and a transparent resin layer 2 are laminated in this order on a base sheet 1, and an uneven shape is formed on the side of the transparent resin layer 2 opposite to the side having the base sheet 1.

[0083] The decorative sheet produced by the decorative sheet producing method of the present invention has excellent designability because the occurrence of air bubbles is suppressed even when an uneven shape is imparted to the sheet.

[0084] <Decorative board> The decorative sheet produced by the decorative sheet production method of the present invention can be laminated on an adherend to produce a decorative board that has a visually excellent three-dimensional effect and is also highly durable.

[0085] Examples of the adherend include wood boards such as wood veneer, wood plywood, particle board, and MDF (medium density fiberboard); gypsum boards such as gypsum boards and gypsum slag boards; cement boards such as calcium silicate boards, asbestos slate boards, lightweight foam concrete boards, and hollow extruded cement boards; fiber cement boards such as pulp cement boards, asbestos cement boards, and wood chip cement boards; ceramic boards such as pottery, porcelain, earthenware, glass, and enamel; metal boards such as iron boards, galvanized steel boards, polyvinyl chloride sol-coated steel boards, aluminum boards, and copper boards; polyolefin resin boards, polyvinyl chloride resin boards, acrylic resin boards, and A Examples of such boards include thermoplastic resin boards such as BS boards and polycarbonate boards; thermosetting resin boards such as phenolic resin boards, urea resin boards, unsaturated polyester resin boards, polyurethane resin boards, epoxy resin boards and melamine resin boards; and so-called FRP boards, which are formed by impregnating and curing resins such as phenolic resins, urea resins, unsaturated polyester resins, polyurethane resins, epoxy resins, melamine resins and diallyl phthalate resins into glass fiber nonwoven fabrics, cloth, paper and other various fibrous substrates. These may be used alone, or two or more of these may be laminated together to form a composite substrate. Furthermore, the thermoplastic resin board or thermosetting resin board may contain various additives, such as coloring materials (pigments or dyes), fillers such as wood flour or calcium carbonate, matting agents such as silica, foaming agents, flame retardants, lubricants such as talc, antistatic agents, antioxidants, ultraviolet absorbers, and light stabilizers, as needed. The thickness of the adherend may be selected appropriately depending on the application.

[0086] The method for laminating the decorative sheet of the present invention to the above-mentioned substrate is not particularly limited, and examples include laminating via the above-mentioned primer layer or via the above-mentioned adhesive. [Example]

[0087] Next, the present invention will be described in more detail by way of examples, but the present invention is not limited to these examples.

[0088] Example 1 A substrate sheet was prepared by forming a 2 μm pattern layer on one side of an 80 μm thick substrate sheet (colored olefin-based film) using a gravure printing machine and forming a 1.5 μm primer layer (a two-component curing type of urethane nitrocellulose) on the other side (preparation process). Next, an adhesive (main agent: 100 parts by weight of polyester polyol, curing agent: 10 parts by weight of 1,6-hexamethylene diisocyanate, solvent: 60 parts by weight of ethyl acetate, viscosity: Zahn Cup No. 3 (manufactured by Rigo Co., Ltd.) 30 seconds) was applied to the surface of the base sheet on which the pattern layer was provided (application process). Furthermore, a transparent resin layer extruded by the T-die method (opposite side to the base sheet: random polypropylene (propylene-ethylene copolymer) with a thickness of 50 μm, on the base sheet side: maleic acid-modified polypropylene with a thickness of 10 μm) was laminated onto the adhesive-coated surface of the above-mentioned base sheet, and at the same time, it was passed between two rolls (a pressure roll made of rubber on the base sheet side, and an embossing plate made of metal on the transparent resin layer side) to form an uneven shape (forming process). Then, a primer layer (a urethane-based two-component curing resin, 1.5 μm thick) was formed on the transparent resin layer with the uneven shape, and a multifunctional urethane acrylate was applied to the primer layer and then cured by irradiating with an electron beam to form a surface protection layer with a thickness of 15 μm (coating process), thereby producing a decorative sheet. The thickness of the transparent resin layer, the depth of the embossing plate, and the value obtained by dividing the depth of the embossing plate (μm) by the thickness of the transparent resin layer (μm) (plate depth / thickness of the transparent resin layer) are shown in Table 1.

[0089] (Examples 2 to 4, Comparative Example 1) A decorative sheet was produced in the same manner as in Example 1, except that the thickness of the transparent resin layer and the depth of the embossing plate were changed as shown in Table 1.

[0090] Example 5 A decorative sheet was produced in the same manner as in Example 1, except that an adhesive (main agent: 100 parts by weight of polyester polyol, curing agent: 10 parts by weight of 1,6-hexamethylene diisocyanate, solvent: none, viscosity: Zahn Cup No. 3 (manufactured by Rigo Co., Ltd.) 60 seconds) was used in the coating process.

[0091] Example 6 A decorative sheet was produced in the same manner as in Example 1, except that an adhesive (main agent: 100 parts by weight of polyester polyol, curing agent: 10 parts by weight of 1,6-hexamethylene diisocyanate, solvent: 180 parts by weight of ethyl acetate, viscosity: Zahn Cup No. 3 (manufactured by Rigo Co., Ltd.) 15 seconds) was used in the coating process.

[0092] Example 7 A decorative sheet was produced in the same manner as in Example 1, except that a transparent resin layer (a random polypropylene single layer with a thickness of 60 μm) was used in the shaping step.

[0093] Example 8 A decorative sheet was produced in the same manner as in Example 1, except that a transparent resin layer (a homopolypropylene single layer with a thickness of 60 μm) was used in the shaping step.

[0094] Example 9 A decorative sheet was produced in the same manner as in Example 1, except that a transparent resin layer (50 μm thick homopolypropylene on the side opposite the base sheet, 10 μm thick maleic acid-modified polypropylene on the base sheet side) was used in the shaping process.

[0095] Example 10 After carrying out the preparation process in the same manner as in Example 1, the shaping process was carried out in the same manner as in Example 1 to produce a decorative sheet (a configuration in which the application process and coating process of Example 1 were omitted).

[0096] Example 11 A decorative sheet was produced in the same manner as in Example 1, except that 5% by mass of low-density polyethylene was added to the random polypropylene on the side of the transparent resin layer extruded by the T-die method opposite the substrate sheet.

[0097] Example 12 A decorative sheet was produced in the same manner as in Example 1, except that the transparent resin layer described in Example 1 was changed to a single layer of random polypropylene having a thickness of 30 μm.

[0098] Example 13 A decorative sheet was produced in the same manner as in Example 1, except that the transparent resin layer described in Example 1 was changed to a single layer of random polypropylene with a thickness of 250 μm and the depth of the embossing plate was changed to 160 μm.

[0099] Example 14 A decorative sheet was produced in the same manner as in Example 1, except that a 73 μm thick polybutylene terephthalate (PBT) base sheet was used instead of the 80 μm thick base sheet (colored olefin-based film) described in Example 1.

[0100] (Comparative Example 2) The same procedures as in Example 1 were carried out except that the transparent resin layer described in Example 1 was changed to a single layer of random polypropylene having a thickness of 30 μm and the depth of the embossing plate was changed to 25 μm.

[0101] <Design evaluation> The decorative sheets produced in the examples and comparative examples were visually inspected and evaluated according to the following criteria. The results are shown in Table 1. Items with a rating of "+ / -" or better were considered to pass. +: No visible air bubbles + / -: Minor air bubbles occur, but not a design defect -: Air bubbles occur, which is a drawback

[0102] [Table 1]

[0103] In examples where the value obtained by dividing the depth (μm) of the embossing plate by the thickness (μm) of the transparent resin layer (plate depth / thickness of the transparent resin layer) was 70% or less, it was confirmed that the occurrence of air bubbles could be suppressed. In Examples 1 to 4, when the state of the adhesive was checked during lamination of the transparent resin layer, it was found to be in a semi-cured state. It was also confirmed that the adhesive after the shaping step contained a solvent. On the other hand, in Example 5, the adhesive was in a cured state when the transparent resin layer was laminated, and the adhesive after the shaping step did not contain a solvent, which is thought to be why the air bubble suppression effect was reduced. In addition, in Example 6, the amount of solvent was too large, which reduced the viscosity and the adhesion between the transparent resin layer and the substrate sheet, which is thought to have reduced the effect of suppressing air bubbles. Furthermore, in Examples 7 and 8, since there was no layer made of acid-modified polypropylene on the side of the transparent resin layer that was laminated to the base sheet, it is believed that the adhesion between the transparent resin layer and the base sheet was reduced, resulting in a reduced effect of suppressing air bubbles. [Industrial Applicability]

[0104] According to the present invention, it is possible to provide a method for producing a decorative sheet that can suppress the occurrence of air bubbles even when an uneven shape is provided. [Explanation of symbols]

[0105] 1 Base sheet 2 Transparent resin layer 3 Adhesive layer 10 Decorative Sheet 20 Extrusion means 30 Crimping means 40 Embossed Plate

Claims

1. A method for manufacturing a decorative sheet having a concave-convex shape, a preparation step of preparing a base sheet; a shaping step of laminating a transparent resin layer on the base sheet and simultaneously shaping a concave-convex shape in the transparent resin layer using an embossing plate, a value obtained by dividing the plate depth (μm) of the embossing plate by the thickness (μm) of the transparent resin layer is 15% or more and 30% or less; The substrate sheet contains an olefin-based resin and has a thickness of 30 μm or more, the transparent resin layer contains a thermoplastic resin, has a thickness of 40 μm or more and 300 μm or less, and has a two-layer structure, the transparent resin layer on the base sheet side is made of acid-modified polypropylene, The transparent resin layer on the opposite side to the base sheet is made of random polypropylene and / or homopolypropylene and contains low-density polyethylene. A method for producing a decorative sheet, comprising:

2. The method for producing a decorative sheet according to claim 1, wherein the embossing plate has a plate depth of 10 μm or more and 150 μm or less.

3. 3. The method for producing a decorative sheet according to claim 1, further comprising a coating step of coating an adhesive onto the base sheet between the preparation step and the shaping step.

4. 4. The method for producing a decorative sheet according to claim 3, wherein the adhesive comprises a two-component curing polyurethane resin obtained by mixing a polyol and an isocyanate, and a solvent, and the adhesive still contains the solvent even after the shaping step.

5. 5. The method for producing a decorative sheet according to claim 3, wherein the adhesive is in a semi-cured state when the transparent resin layer is laminated on the base sheet.

6. 6. The method for producing a decorative sheet according to any one of claims 3 to 5, wherein the adhesive has a viscosity measured with a Zahn cup No. 3 of 25 to 35 seconds.

7. 7. The method for producing a decorative sheet according to claim 1, wherein the acid-modified polypropylene is maleic acid-modified polypropylene.

Images