JP2020050724A - Transparent resin layer for decorative sheet and manufacturing method therefor, and decorative sheet and decorative plate having the transparent resin layer - Google Patents

Abstract

To provide a transparent resin layer for decorative sheet consisting of a monolayer film of an ionomer element containing no resin component other than an ionomer nor an additive (such as a crosslinking agent), and achieving excellent heat resistance and scratch resistance, and a manufacturing method therefor, and a decorative sheet and a decorative plate having the transparent resin layer.SOLUTION: There is provided a transparent resin layer for decorative sheet, in which (1) the transparent resin layer is constituted by an electron beam crosslinked article of an ionomer consisting of an ethylene-methacrylic acid copolymer and a zinc ion, and (2) the transparent resin layer has melting point measured by DSC of 74 to 88°C, dimensional change rate measured by heat machine analysis with tensile mode 90°C of 5% or less, and storage elasticity measured by dynamic viscoelasticity analysis with tensile mode 100°C of 2×10to 1×10.SELECTED DRAWING: None

Description

  The present invention relates to a transparent resin layer for a decorative sheet and a method for producing the same, and a decorative sheet and a decorative plate provided with the transparent resin layer.

  2. Description of the Related Art Conventionally, heat resistance and scratch resistance have been required for skin materials of interior materials of buildings (fittings, floors, walls, etc.), skin materials of automobile interiors and exteriors, and daily necessities, and the skin materials include ionomers. It is known to use films. Specifically, use of a decorative sheet having a film containing an ionomer as a transparent resin layer as a skin material may be mentioned.

  For example, Patent Literature 1 relates to a crosslinked product, a film, and an adhesive film, “Ionomer (A) of an ethylene-α, β-unsaturated carboxylic acid-based copolymer, epoxy compound (B), and polyolefin (C). (Claim 1) ", a film containing the crosslinked product (Claim 9), and an adhesive film containing the film and an adhesive layer (Claim 10). ) Is disclosed.

  In Patent Document 1, by containing an epoxy compound (B) in addition to the ionomer (A), it reacts with the carbonyl group of the ionomer (A) to form a first crosslink, and the second crosslink by electron beam irradiation It is said that the abrasion resistance and the heat resistance of the crosslinked product are improved by combining with the crosslink of ([0035], [0068] paragraphs, etc.). Further, Patent Document 1 discloses that by containing a polyolefin (C) in addition to the ionomer (A), the dispersibility of other components is improved and the heat resistance is improved (paragraph [0052]).

  Regarding the scratch resistance of a film containing an ionomer, a large part is attributed to the resilience peculiar to the ionomer. However, as in Patent Document 1, in addition to the ionomer (A), additives such as an epoxy compound (B) and a polyolefin (C When another resin such as (1) is added, there is a problem that the resilience peculiar to the ionomer relatively decreases.

  Therefore, there is still room for improvement in the problem that conventional films containing ionomers satisfy both heat resistance and scratch resistance. In particular, a product exhibiting excellent heat resistance and scratch resistance in a single-layer film of an ionomer alone containing no resin component other than the ionomer and no additives (such as a crosslinking agent) has yet been developed.

JP 2014-148652 A

  The present invention is a transparent resin layer for a decorative sheet composed of a single-layer film of an ionomer alone containing no resin component other than the ionomer and no additive (such as a crosslinking agent), and exhibits excellent heat resistance and scratch resistance. It is an object of the present invention to provide a transparent resin layer and a method for producing the same, and a decorative sheet and a decorative board provided with the transparent resin layer.

  The present inventor has conducted extensive studies, and as a result, a film comprising a specific ionomer electron beam cross-linked product, when the film meets the requirements of a specific melting point, dimensional change rate, and storage modulus measured by DSC. Have found that the above object can be achieved, and have completed the present invention.

That is, the present invention relates to the following transparent resin layer for a decorative sheet and a method for producing the same, and a decorative sheet and a decorative plate provided with the transparent resin layer.
1. A transparent resin layer for a decorative sheet,
(1) The transparent resin layer is formed of an electron beam cross-linked product of an ionomer comprising an ethylene-methacrylic acid copolymer and zinc ions,
(2) The transparent resin layer has a melting point of 74 to 88 ° C measured by DSC, a dimensional change rate of 5% or less measured by thermomechanical analysis in a tensile mode of 90 ° C, and a tensile mode of 100 ° C. Storage elastic modulus measured by dynamic viscoelasticity analysis of 2 × 10 ⁷ to 1 × 10 ⁹ ,
A transparent resin layer, characterized in that:
2. Item 2. The transparent resin layer according to item 1, wherein the storage elastic modulus measured by dynamic viscoelasticity analysis in a tensile mode of 150 ° C is 5 × 10 ⁶ to 1 × 10 ⁹ .
3. A method for producing a transparent resin layer for a decorative sheet,
(1) a step of obtaining a film by forming an ionomer composed of an ethylene-methacrylic acid copolymer and zinc ions, wherein the melting point of the ionomer measured by DSC is 88 to 94 ° C;
(2) a step of irradiating the film with an electron beam to obtain a transparent resin layer in which the ionomer is crosslinked, wherein the melting point of the transparent resin layer measured by DSC is 74 to 88 ° C. A step in which the dimensional change rate measured by thermomechanical analysis at 90 ° C. is 5% or less, and the storage elastic modulus measured by dynamic viscoelasticity analysis in tensile mode 100 ° C. is 2 × 10 ⁷ to 1 × 10 ⁹ 2,
A method for producing a transparent resin layer, comprising:
4. Item 4. The method according to Item 3, wherein the irradiation amount of the electron beam is 60 Mrad or more and 150 Mrad or less.
5. Item 3. A decorative sheet comprising the transparent resin layer according to item 1 or 2.
6. A decorative sheet comprising a laminate comprising at least a substrate sheet and the transparent resin layer according to item 1 or 2 in the thickness direction.
7. A decorative panel comprising a laminate comprising, in order in the thickness direction, a decorative panel substrate and the decorative sheet according to item 5 or 6.

The transparent resin layer of the present invention,
(1) an ionomer composed of an ethylene-methacrylic acid copolymer and zinc ions, which is constituted by an electron beam crosslinked product;
(2) The melting point measured by DSC is 74 to 88 ° C., the dimensional change rate measured by thermomechanical analysis in tensile mode 90 ° C. is 5% or less, and the dynamic viscoelasticity analysis in tensile mode 100 ° C. The measured storage modulus is 2 × 10 ⁷ to 1 × 10 ⁹ ;
Thereby, excellent heat resistance and scratch resistance are exhibited even in the state of a single-layer film of the ionomer alone, which does not contain resin components and additives (such as a crosslinking agent) other than the ionomer.

  Such a transparent resin layer of the present invention is useful as a transparent resin layer for a decorative sheet, and in the form of a film of the transparent resin layer, and a decorative sheet or a decorative plate provided with the film, an interior material for a building. It is useful as a skin material for (fittings, floors, walls, etc.), interior and exterior of automobiles, and skin materials for daily necessities.

  The production method of the present invention is useful as a method for producing the transparent resin layer of the present invention.

It is sectional drawing which shows one aspect of the decorative sheet provided with the transparent resin layer of this invention. It is sectional drawing which shows one aspect of the decorative sheet provided with the transparent resin layer of this invention. It is a cross section showing an embodiment of the decorative board provided with the transparent resin layer of the present invention.

  Hereinafter, a transparent resin layer for a decorative sheet of the present invention and a method for producing the same, and a decorative sheet and a decorative plate provided with the transparent resin layer will be described in detail. In the present specification, the direction in which the transparent surface protective layer is laminated as viewed from the base sheet is referred to as “up” or “front side”, and the back primer layer is laminated as viewed from the base sheet. Is referred to as “down” or “back side”. The “front (side) surface” or the “transparent surface protective layer (side) surface” of the decorative sheet or decorative plate means a surface that is visually recognized after the decorative sheet or decorative plate is applied. In the following, the lower limit and the upper limit of the numerical range represented by “to” mean “not more than” (for example, if α to β, it is not less than α and not more than β).

1. Transparent resin layer for decorative sheet, and method for producing the same The transparent resin layer for a decorative sheet of the present invention (hereinafter, abbreviated as “transparent resin layer”) includes:
(1) an ionomer composed of an ethylene-methacrylic acid copolymer and zinc ions, which is constituted by an electron beam crosslinked product;
(2) The melting point measured by DSC is 74 to 88 ° C., the dimensional change rate measured by thermomechanical analysis in tensile mode 90 ° C. is 5% or less, and the dynamic viscoelasticity analysis in tensile mode 100 ° C. The measured storage modulus is 2 × 10 ⁷ to 1 × 10 ⁹ ;
It is characterized by the following.

  The transparent resin layer of the present invention having the above characteristics exhibits excellent heat resistance and scratch resistance even in the state of a single-layer film of the ionomer alone containing no resin components other than the ionomer and additives (such as a crosslinking agent). . Therefore, it is useful as a transparent resin layer film, a decorative sheet or a decorative plate provided with the transparent resin layer, as a skin material for building interior materials (fittings, floors, walls, etc.), and as a skin material for interior and exterior of automobiles and daily necessities. It is.

Further, the transparent resin layer of the present invention,
(1) a step of obtaining a film by forming an ionomer composed of an ethylene-methacrylic acid copolymer and zinc ions, wherein the melting point of the ionomer measured by DSC is 88 to 94 ° C;
(2) a step of irradiating the film with an electron beam to obtain a transparent resin layer in which the ionomer is crosslinked, wherein the melting point of the transparent resin layer measured by DSC is 74 to 88 ° C. A step in which the dimensional change rate measured by thermomechanical analysis at 90 ° C. is 5% or less, and the storage elastic modulus measured by dynamic viscoelasticity analysis in tensile mode 100 ° C. is 2 × 10 ⁷ to 1 × 10 ⁹ 2,
(Hereinafter referred to as “the production method of the present invention”)
Can be more suitably produced.

  The ionomer used as the raw material is an ionomer composed of an ethylene-methacrylic acid copolymer and zinc ions and having a melting point measured by DSC (melting point of the ionomer film) in the range of 88 to 94 ° C.

  In addition, the melting point measured by DSC in this specification is obtained by measuring the film sample or the transparent resin layer (each 5 mg) from 30 ° C. in a nitrogen atmosphere at a cooling rate of 10 ° C./min using a differential scanning calorimeter DSC. After cooling to 30 ° C., the temperature was raised to 200 ° C. at a rate of 10 ° C./min, then cooled again to −30 ° C. at a rate of 10 ° C./min, and again to 200 ° C. at a rate of 10 ° C./min. It means the peak top (° C.) of the second endothermic peak when the heating operation is repeated twice.

  As the ionomer, those having a melt mass flow rate measured in JIS K7210: 1999 (190 ° C., 2.16 kg load) of 0.5 to 5.5 g / 10 min are preferable, and particularly 0.8 to 1.5 g / min. Those that are 10 minutes are preferred.

  The content of methacrylic acid in the ethylene-methacrylic acid copolymer constituting the ionomer is not limited, but is preferably 2 to 35% by weight, and particularly preferably 5 to 30% by weight. Further, the zinc ion constituting the ionomer is preferably one in which 20 to 90% of the carboxyl groups in the copolymer have been neutralized, particularly preferably one in which 50 to 80% has been neutralized. . As metal ions constituting the ionomer, sodium ions and the like are known in addition to zinc ions. However, the ionomer used in the present invention requires that the metal ions be substantially zinc ions, and other ions such as sodium ions It is preferable that the metal ion is not contained. In particular, when sodium ions are contained, the hygroscopicity increases, which may affect the transparent resin layer and a decorative sheet including the same. In the present invention, it is preferable that the composition does not contain a resin component and an additive (such as a cross-linking agent) other than the ionomer, and substantially contains only the ionomer.

  When the ionomer is formed into a film in Step 1, a known film forming method can be widely used. For example, the film can be easily formed by forming the ionomer pellet into a film using a cast film manufacturing machine. The processing temperature in this case is not limited, but is preferably about 200 to 250 ° C. The thickness of the formed film is not limited, but is preferably 40 μm or more and 300 μm or less, more preferably 60 μm or more and 200 μm or less, and most preferably 80 μm or more and 120 μm or less. By setting the thickness of the film in the above range, when producing a decorative sheet provided with the transparent resin layer of the present invention, it is possible to form a deep emboss, and to improve the scratch resistance, The effect of suppressing scraping (pattern removal) due to abrasion of the picture pattern layer is easily obtained. In addition, the step of obtaining a film in the step 1 includes any of an embodiment in which the film is formed from the ionomer pellets into a film as described above, and an embodiment using a commercially available ionomer film.

Next, the film obtained in the first step is irradiated with an electron beam in the second step to obtain a transparent resin layer in which the ionomer is crosslinked. The melting point of the transparent resin layer measured by DSC with electron beam irradiation is 74 to 88 ° C., and the dimensional change (also referred to as TMA dimensional change) measured by thermomechanical analysis (TMA) in a tensile mode of 90 ° C. is 5% or less. And the storage elastic modulus (also referred to as DMA storage elastic modulus) measured by dynamic viscoelasticity analysis (DMA) in a tensile mode of 100 ° C. becomes 2 × 10 ⁷ to 1 × 10 ⁹ .

  The amount of electron beam irradiation may be any amount such that the melting point, TMA dimensional change rate, and DMA storage elastic modulus of the transparent resin layer after electron beam irradiation measured by DSC are within a predetermined range, but is preferably 60 Mrad or more. The upper limit is about 150 Mrad. That is, the irradiation amount is preferably from 60 Mrad to 150 Mrad, and if it exceeds 150 Mrad, the elongation of the transparent resin layer may be insufficient, that is, the restoring property may be insufficient. When irradiating with an electron beam, for example, when irradiating 60 MRad, irradiation of 60 MRad at once may accelerate the deterioration of the film. Therefore, it is preferable to divide the film into a plurality of 10 MRads (six times for 60 MRads). Irradiation is preferably performed.

  The melting point of the transparent resin layer measured by DSC may be 74 to 88 ° C, and among them, 74 to 80 ° C is preferable.

The TMA dimensional change of the transparent resin layer in the tensile mode at 90 ° C. may be 5% or less, and among them, 4.5 to 2.5% is preferable. In this specification, the TMA dimensional change rate is defined as TMA% at 90 ° C. when the temperature is increased to 110 ° C. at a load of 70 mN / mm ² and 10 ° C./min in the tensile mode, and each dimensional change rate is N = 3. It is the average value measured in.

The DMA storage elastic modulus of the transparent resin layer in the tensile mode at 100 ° C. may be 2 × 10 ⁷ to 1 × 10 ⁹ , and among them, 2.5 × 10 ⁷ to 1 × 10 ⁸ is preferable. Further, the DMA storage elastic modulus of the transparent resin layer in the tensile mode at 150 ° C. is preferably 5 × 10 ⁶ to 1 × 10 ^{9, and} more preferably 5.5 × 10 ⁶ to 1 × 10 ⁸ . In this specification, the DMA storage elastic modulus is as follows: measurement mode: frequency dependence, chuck: tension, waveform: sine wave, sample width: 5 mm, thickness: about 80 μm, length: 20 mm, starting temperature: 0 ° C., Step temperature: 2 ° C., end temperature: 200 ° C., heating rate: 3 ° C./min, hold time: 0 s, frequency: 10 Hz, static load: constant 15 g.

  The transparent resin layer of the present invention can be suitably obtained by the production method of the present invention. The obtained transparent resin layer may be used as various skin materials in the state of a single layer (film), or as a decorative sheet or a decorative plate provided with the same as described below.

2. Decorative sheet The decorative sheet of the present invention includes the above-described transparent resin layer of the present invention, and is preferably a laminate including at least the base sheet and the transparent resin layer of the present invention sequentially in the thickness direction. Consists of

  For example, as a decorative sheet, an embodiment in which at least a pattern layer, an adhesive layer, and the transparent resin layer of the present invention are sequentially laminated on a base sheet is given. A transparent surface protective layer may be further provided on the transparent resin layer of the present invention. In addition, the outermost surface layer of the decorative sheet may be provided with an uneven pattern by embossing.

  Hereinafter, each layer will be described using the above-described decorative sheet as an example.

≪Base sheet≫
The substrate sheet has a pattern layer or the like sequentially laminated on the surface (front surface).

  Examples of the substrate sheet include various types such as a resin film, paper, and resin-impregnated paper, and among resin films, those formed of a thermoplastic resin are preferable. Specifically, polyvinyl chloride, polyethylene terephthalate, polybutylene terephthalate, polyamide, polyethylene, polypropylene, polycarbonate, polyethylene naphthalate, ethylene-vinyl acetate copolymer, ethylene-acrylic acid copolymer, ethylene-acrylic acid ester copolymer Examples include a polymer, an ionomer, an acrylate, and a methacrylate. Among them, polyolefins such as polypropylene are preferable.

  The base sheet may be colored. For example, coloring can be performed by adding a coloring agent (pigment or dye) to the thermoplastic resin. 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 be used. One or more of these can be selected. Further, the amount of the coloring agent to be added may be appropriately set according to a desired color or the like.

  The base sheet contains various additives such as fillers, matting agents, foaming agents, flame retardants, lubricants, antistatic agents, antioxidants, ultraviolet absorbers, and light stabilizers as necessary. It may be.

  The thickness of the base sheet can be appropriately set depending on the use of the final product, the method of use, and the like, but is generally preferably 50 to 250 μm.

  If necessary, the base sheet may be subjected to a corona discharge treatment on the surface (front surface) in order to enhance the adhesiveness of the ink forming the design pattern layer. The method and conditions of the corona discharge treatment may be performed according to a known method. If necessary, a corona discharge treatment may be performed on the back surface of the base material sheet, a pattern pattern layer (a so-called back print) may be formed, a back surface primer layer, a backer layer described later, or the like may be formed. .

≪Pattern pattern layer (Pattern layer) ≫
The picture layer is for imparting a desired picture (design) to the decorative sheet, and the type of the picture is not limited. For example, a wood grain pattern, a stone grain pattern, a grain grain pattern, a tiled pattern, a brickwork pattern, a cloth grain pattern, a leather pattern, a geometric figure, a character, a symbol, an abstract pattern, and the like can be given.

  The method for forming the picture layer is not particularly limited. For example, printing using an ink obtained by dissolving (or dispersing) a known colorant (dye or pigment) in a solvent (or dispersion medium) together with a binder resin. What is necessary is just to form it on the base material sheet surface by the method.

  Examples of colorants include inorganic pigments such as carbon black, titanium white, zinc white, red iron oxide, navy blue and cadmium red; azo pigments, lake pigments, anthraquinone pigments, quinacridone pigments, phthalocyanine pigments, isoindolinone pigments, dioxazine pigments Organic pigments such as aluminum powder and bronze powder; pearlescent pigments such as titanium oxide-coated mica and bismuth oxychloride; fluorescent pigments; These colorants can be used alone or in combination of two or more. Fillers such as silica, extenders such as organic beads, neutralizing agents, surfactants and the like may be further added to these colorants.

  Examples of the binder resin include polyester-based urethane resins, hydrophilically-treated polyester-based urethane resins, polyester, polyacrylate, polyvinyl acetate, polybutadiene, polyvinyl chloride, chlorinated polypropylene, polyethylene, polystyrene, and polystyrene-acrylate. A polymer, a rosin derivative, an alcohol adduct of a styrene-maleic anhydride copolymer, a cellulose resin, and the like can also be used in combination.

  More specifically, for example, polyurethane-polyacrylic resin, polyacrylamide resin, poly (meth) acrylic acid resin, polyethylene oxide resin, poly N-vinylpyrrolidone resin, water-soluble polyester resin, water-soluble Polyamide resins, water-soluble amino resins, water-soluble phenolic resins, and other water-soluble synthetic resins; water-soluble natural polymers such as polynucleotides, polypeptides, and polysaccharides; and the like can be used. Further, for example, natural rubber, synthetic rubber, polyvinyl acetate resin, (meth) acrylic resin, polyvinyl chloride resin, polyurethane-polyacrylic resin modified or mixed resin, and other resins can also be used. The binder resin may be used alone or in combination of two or more.

  Examples of the printing method used for forming the picture layer include a gravure printing method, an offset printing method, a screen printing method, a flexographic printing method, an electrostatic printing method, an inkjet printing method, and the like. In the case of forming a solid pattern pattern layer (also referred to as a colored concealing layer) over the entire surface, for example, a gravure coating method, a gravure reverse coating method, a roll coating method, a knife coating method, an air knife coating method, a die coating method And various coating methods such as a lip coating method, a comma coating method, a kiss coating method, a flow coating method, and a dip coating method.

  In addition to the above, for example, a hand-drawing method, an ink-washing method, a photographic method, a transfer method, a laser beam drawing method, an electron beam drawing method, a partial vapor deposition method of metal or the like, an etching method, or the like, or in combination with another forming method It may be used.

  The thickness of the picture layer is not particularly limited and can be appropriately set according to the product characteristics, but the layer thickness at the time of coating is about 0.1 to 10 μm.

≪Adhesive layer≫
The adhesive layer exists between the picture layer and the transparent resin layer. The adhesive used in the adhesive layer can be appropriately selected according to the components constituting the picture layer or the transparent resin layer. For example, various adhesives including polyurethane resin, polyacrylic resin, polycarbonate resin, epoxy resin and the like can be used. In addition to the reaction curing type, an adhesive such as a hot melt type, an ionizing radiation curing type, and an ultraviolet curing type may be used.

  The adhesive layer may be transparent or translucent as long as the pattern layer can be recognized.

  In the present invention, if necessary, a known easy adhesion treatment such as a corona discharge treatment, a plasma treatment, a degreasing treatment, and a surface roughening treatment may be applied to the bonding surface.

  The adhesive layer can be formed, for example, by applying the adhesive on the pattern layer, drying once, and then laminating a transparent resin. The method of applying the adhesive is not particularly limited, and examples thereof include roll coating, curtain flow coating, wire bar coating, reverse coating, gravure coating, gravure reverse coating, air knife coating, kiss coating, blade coating, smooth coating, and comma coating. The method can be adopted.

  The thickness of the adhesive layer varies depending on the type of the transparent protective layer, the adhesive used, and the like, but is generally about 0.1 to 30 μm.

≪Transparent resin layer≫
The transparent resin layer may be translucent as long as the pattern layer is visible as long as it is transparent.

  In the present invention, the above-mentioned transparent resin layer of the present invention is used as the transparent resin layer.

≪Transparent surface protective layer≫
A transparent surface protective layer may be formed on the transparent resin layer. The transparent surface protective layer is not limited, but preferably contains an ionizing radiation curable resin or a two-component curable urethane resin as a resin component. Substantially, those formed from these resins are preferable. When a transparent surface protective layer is formed of an ionizing radiation-curable resin or a two-component curable urethane-based resin, the abrasion resistance, impact resistance, stain resistance, scratch resistance, weather resistance, etc. of the decorative sheet are improved. easy. In the present invention, among these, the outermost layer is preferably an ionizing radiation-curable resin layer.

  The ionizing radiation-curable resin is not particularly limited, and may include a prepolymer (including an oligomer) and / or a monomer containing a radical polymerizable double bond capable of undergoing a polymerization crosslinking reaction upon irradiation with ionizing radiation such as ultraviolet rays or an electron beam. Can be used. These prepolymers or monomers can be used alone or as a mixture of two or more. The curing reaction is usually a cross-linking curing reaction.

  Specifically, compounds having a radical polymerizable unsaturated group such as a (meth) acryloyl group and a (meth) acryloyloxy group and a cationic polymerizable functional group such as an epoxy group in the molecule as the prepolymer or the monomer. Is mentioned. Further, a polyene / thiol prepolymer based on a combination of a polyene and a polythiol is also preferable. Here, the (meth) acryloyl group means an acryloyl group or a methacryloyl group.

  Examples of the prepolymer having a radical polymerizable unsaturated group include polyester (meth) acrylate, urethane (meth) acrylate, epoxy (meth) acrylate, melamine (meth) acrylate, triazine (meth) acrylate, and silicone (meth) acrylate. And the like. Usually, the molecular weight is preferably about 250 to 100,000.

  Examples of the monomer having a radical polymerizable unsaturated group include monofunctional monomers such as methyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and phenoxyethyl (meth) acrylate. Examples of the polyfunctional monomer include, for example, diethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, trimethylpropane tri (meth) acrylate, trimethylolpropane ethylene oxide tri (meth) acrylate, dipentaerythritol tetra ( (Meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate and the like.

  Examples of the prepolymer having a cationically polymerizable functional group include prepolymers of epoxy resins such as bisphenol epoxy resins and novolak epoxy compounds, and vinyl ether resins such as fatty acid vinyl ethers and aromatic vinyl ethers. Examples of the thiol include polythiols such as trimethylolpropane trithioglycolate and pentaerythritol tetrathioglycolate. Examples of the polyene include those obtained by adding allyl alcohol to both ends of a polyurethane made of diol and diisocyanate.

  As the ionizing radiation used for curing the ionizing radiation-curable resin, an electromagnetic wave or a charged particle having energy capable of causing a curing reaction of molecules in the ionizing radiation-curable resin (composition) is used. Usually, ultraviolet rays or electron beams may be used, but visible rays, X-rays, ion beams, or the like may be used.

  As the ultraviolet light source, for example, a light source such as an ultra-high pressure mercury lamp, a high pressure mercury lamp, a low pressure mercury lamp, a carbon arc lamp, a black light, and a metal halide lamp can be used. The wavelength of the ultraviolet light is usually preferably 190 to 380 nm.

  As the electron beam source, for example, various electron beam accelerators such as a Cockcroft-Walton type, a Van degraft type, a resonance transformer type, an insulating core transformer type, a linear type, a dynamitron type, and a high frequency type can be used. Among them, those capable of irradiating electrons having an energy of 100 to 1000 keV, preferably 100 to 300 keV are preferable.

  The two-component curable urethane-based resin is not particularly limited. Among them, a polyol component having an OH group (such as an acrylic polyol, a polyester polyol, a polyether polyol, or an epoxy polyol) as a main component, and an isocyanate component as a curing agent component (tolylene diene) Isocyanate, hexamethylene diisocyanate, meta-xylene diisocyanate, etc.) can be used.

  The transparent surface protective layer may contain a plasticizer, a stabilizer, a filler, a dispersant, a coloring agent such as a dye and a pigment, a solvent, and the like, if necessary.

  The transparent surface protective layer is, for example, coated with an ionizing radiation curable resin or a two-component curable urethane resin on the transparent resin layer by a known coating method such as gravure coating or roll coating, and then curing the resin. Can be formed. In the case of an ionizing radiation-curable resin, the resin is cured by electron beam irradiation.

  The thickness of the transparent surface protective layer is not particularly limited and can be appropriately set according to the characteristics of the final product, but is usually about 0.1 to 50 μm, preferably about 1 to 20 μm.

≪Embossing≫
The decorative sheet may be embossed from the transparent surface protective layer side.

  The embossing is performed to impart a desired texture such as a grain pattern to the decorative sheet. For example, after the transparent protective layer is heated and softened, a texture is imparted by pressing and shaping with an embossed plate having a desired shape of an uneven pattern, followed by cooling and fixing. The embossing can be performed by a known single-wafer or rotary embossing machine.

  Examples of the embossed concavo-convex pattern include a wood grain conduit groove, an embossed pattern (embossed annual ring-shaped concavo-convex pattern), a hairline, a grain of sand, and a satin finish.

  When embossing is performed, the embossed concave portion may be filled with ink by wiping as required. For example, ink is filled into the embossed concave portion while scratching the surface with a doctor blade. As the ink to be filled (wiping ink), an ink having a two-component curable urethane resin as a binder can be used. In particular, by performing wiping processing on the wood grain conduit groove irregularities, it is possible to enhance the commercial value by expressing a design closer to the actual wood grain.

  In the present invention, other components may be contained in the transparent surface protective layer. For example, additives such as a solvent, an ultraviolet absorber, an antioxidant, a dispersant, a light stabilizer, a gloss adjusting agent, an antiblocking agent, and a lubricant can be added.

Vesicle formation of various additives contained in each layer of the decorative sheet Various additives (such as inorganic fillers added to the primer layer and the surface protective layer) added to each of the above-mentioned layers of the decorative sheet of the present invention are used as the various additives. Is preferably vesicle-formed. The method for vesicleizing various additives is not particularly limited, and vesicles can be formed by a known method. Among them, a supercritical reversed phase evaporation method is preferable.

  Hereinafter, the supercritical reversed-phase evaporation method will be described in detail. Supercritical reversed-phase evaporation is a process in which a substance that forms an outer membrane of a vesicle is uniformly dissolved in carbon dioxide in a supercritical state or at a temperature or pressure above the supercritical point. In this method, an aqueous phase containing various additives as the encapsulating substance is added to form a capsule-shaped vesicle containing the various additives as the encapsulating substance in a single layer. Note that the carbon dioxide in a supercritical state means carbon dioxide in a supercritical state at a critical temperature (30.98 ° C.) and a critical pressure (7.3773 ± 0.0030 MPa) or higher. The term “carbon dioxide under pressure conditions” means carbon dioxide under conditions where only the critical temperature or only the critical pressure exceeds the critical conditions. By this method, a single-layer lamellar vesicle having a diameter of 50 to 800 nm can be obtained. In general, vesicles are a general term for those containing a liquid phase inside vesicles having a membrane structure closed in a spherical shell, and those in which the outer membrane is composed of biological lipids such as phospholipids are called liposomes. .

  Examples of the phospholipids include phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine, phosphatidic acid, phosphatidylglycerol, phosphatidylinositol, cardiolipin, egg lecithin, hydrogenated yellow egg lecithin, soy lecithin, glycerophospholipids such as hydrogenated soy lecithin, sphingomyelin. And sphingolipids such as ceramide phosphorylethanolamine and ceramide phosphorylglycerol.

  As the substance constituting the outer membrane, a nonionic surfactant or a dispersant such as a mixture of the nonionic surfactant and cholesterol or triacylglycerol can be used.

  Examples of the nonionic surfactant include polyglycerin ether, dialkylglycerin, polyoxyethylene hydrogenated castor oil, polyoxyethylene alkyl ether, polyoxyethylene sorbitan fatty acid ester, sorbitan fatty acid ester, polyoxyethylene polyoxypropylene copolymer, and polybutadiene- One or two kinds of polyoxyethylene copolymer, polybutadiene-poly2-vinylpyridine, polystyrene-polyacrylic acid copolymer, polyethylene oxide-polyethylethylene copolymer, polyoxyethylene-polycaprolactam copolymer, etc. The above can be used.

  Examples of the cholesterol include one or more of cholesterol, α-cholestanol, β-cholestanol, cholestane, desmosterol (5,24-cholestadiene-3β-ol), sodium cholate, and cholecalciferol. Can be used.

  The outer membrane of the liposome may be formed from a mixture of a phospholipid and a dispersant. In the decorative sheet of the present invention, by using a liposome having an outer membrane formed of a phospholipid, the compatibility between the resin composition as a main component of each layer and various additives can be improved.

3. Decorative board The decorative board of the present invention is composed of a laminate including a decorative board substrate and the above-described decorative sheet of the present invention in order in the thickness direction.

  FIG. 3 shows an example of the decorative sheet 9 in which the decorative sheet 1 of the present invention (the surface opposite to the surface protective layer side and the decorative sheet substrate 11) is laminated on the decorative sheet substrate 8 in this order. .

  As a decorative board base material, for example, medium-density wood fiber board, high-density wood fiber board, particle board, softwood plywood, hardwood plywood, fast-growing plywood, cork sheet, cork-containing composite base material, thermoplastic At least one type of resin plate (a resin plate containing a polyvinyl chloride resin, a polypropylene resin, a polyethylene resin, an acrylic resin, an ABS resin, or the like as a main component, or a foam thereof) is used. These decorative board substrates may be used alone or in combination of two or more kinds and laminated.

  Here, examples of conifers include Todomatsu, Karamatsu, Ezomatsu, Cedar, Hinoki, Pine, Sequoia, and Spruce. Examples of the hardwood include lauan, china, hippo, sen, beech, oak, and meranti. In addition, examples of the early-growth tree include poplar, falcata, acacia, chamelere, eucalyptus, and terminaria.

  When using a woody plywood such as a softwood plywood, a hardwood plywood, or a fast-growing plywood, the number of laminated wood veneers (the number of plies) is not limited, but usually 3 to 7 is preferable, and 5 to 7 is more preferable. In addition, the adhesive used when preparing the wood plywood is not limited, and a known woodworking adhesive can be widely used. Examples of the adhesive include acrylic, urethane, acryl-urethane, polyvinyl acetate, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, ethylene-acrylic acid copolymer, ionomer, butadiene-acrylonitrile rubber, and neoprene rubber And an adhesive containing natural rubber or the like as an active ingredient. Examples of the thermosetting adhesive include melamine-based, phenol-based, and urea-based (vinyl acetate-urea-based) adhesives.

  As the cork sheet, not only so-called natural cork, which is a material having high elasticity obtained by peeling and processing the cork tissue of the bark of cork oak, but also so-called synthetic cork made to resemble cork can be used. The cork sheet may be a single layer, or may be a laminate of a plurality of cork sheets having different elastic moduli and densities.

  Examples of the cork-containing composite base material include a composite material obtained by laminating and attaching a cork sheet and another material (for example, a medium-density wood fiber board or a high-density wood fiber board).

  Although the thickness of the decorative board substrate is not limited, it is preferably about 2 to 15 mm, more preferably about 2 to 12 mm.

  The laminating method for laminating the decorative sheet and the decorative board substrate is not limited, and for example, a method of sticking each with an adhesive can be adopted. The adhesive may be appropriately selected from known adhesives according to the type of the adherend and the like. Examples include polyvinyl acetate, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, ethylene-acrylic acid copolymer, ionomer, etc., butadiene-acrylonitrile rubber, neoprene rubber, natural rubber and the like. These adhesives are used alone or in combination of two or more.

  Hereinafter, the present invention will be specifically described with reference to Examples, Comparative Examples, and Test Examples. However, the present invention is not limited to the contents shown in the embodiments.

Example 1
(Production of decorative sheet)
(1) A sheet was prepared by printing a pattern layer having a thickness of 2 μm on a base sheet which was a colored polypropylene film having a thickness of 0.06 mm.
(2) Ionomer A pellets were molded at a processing temperature of 230 ° C. using a cast film production machine to produce an 80 μm ionomer film (the details of the ionomer A and the ionomers B and C described later are described in the following table). Described in footnote).
(3) The ionomer film produced in (2) was irradiated with an electron beam under the condition of 165 kV × 60 Mrad using an electron beam irradiator to produce a transparent resin layer. In addition, when irradiating the ionomer film with an electron beam in Examples and Comparative Examples, 165 kV × 10 Mrad electron beam irradiation was performed a plurality of times (six times in Example 1).
(4) The transparent resin layer prepared in (3) was adhered to the sheet prepared in (1) using a urethane-based adhesive for dry lamination.
(5) A coating film (15 μm) of the composition for forming an electron beam-curable transparent surface protective layer is formed on the transparent resin layer, and then the electron beam is cured under a condition of 165 kV × 5 Mrad to cure the coating film. To form a transparent surface protective layer.

(Production of decorative board)
A 3 mm MDF (medium density fiberboard) was adhered to the back surface of the prepared decorative sheet via an adhesive described later to prepare a decorative plate. A urethane-modified ethylene-vinyl acetate emulsion adhesive (100 g / m ² wet) was used for the attachment.

Examples 2 to 4
In the above step (3), a decorative sheet and a decorative board were prepared in the same manner as in Example 1 except that the electron beam irradiation amount was changed to 90 Mrad (Example 2), 120 Mrad (Example 3), and 150 Mrad (Example 4). Produced.

Example 5
A decorative sheet and a decorative plate were prepared in the same manner as in Example 1 except that the transparent surface protective layer was not formed.

Comparative Examples 1-4
In the above step (3), the amount of electron beam irradiation was changed to 30 Mrad (Comparative Example 1) and 5 Mrad (Comparative Examples 2 to 4), and the type of ionomer was ionomer B (Comparative Example 3) and ionomer C (Comparative Example 4). A decorative sheet and a decorative plate were produced in the same manner as in Example 1 except that the decorative sheet was replaced with the decorative sheet.

Comparative Example 5
In the above step (3), the ionomer film is irradiated with the electron beam from the side of the coating film without forming the coating film of the composition for forming a transparent surface protective layer of the above (5) without irradiating the ionomer film with the electron beam. Then, a decorative sheet and a decorative plate were produced in the same manner as in Example 1, except that the transparent resin layer and the transparent surface protective layer were simultaneously formed.

Test example 1
The color of the transparent resin layer alone was evaluated visually. Further, a JAS wet heat test, a Hoffman scratch test and a Dupont impact test were performed on the decorative board.

(Evaluation of color by visual observation of a single transparent resin layer)
The evaluation criteria by visual inspection were as follows.
++: No problem, +: Slightly yellowish,-: Coloring is recognized.

(JAS wet heat test)
After fixing the decorative board horizontally, drop boiling water on the decorative board surface, leave a 1L aluminum container containing 0.5L boiling water on it for 20 minutes, and wipe off moisture with a dry cloth. It was left as it was for 24 hours. The presence or absence of a change in appearance after 24 hours was visually checked.

The evaluation criteria by visual inspection were as follows.
++: no problem, +: slightly whitened,-: whitened, wrinkled on the surface,
+ Or more is a pass.

(Hoffman scratch test)
The scratch resistance of the decorative plate was confirmed using a Hoffman scratch tester (manufactured by BYK-Gardnar). Specifically, a scratch blade (edge portion of a 7 mm diameter cylinder) was set so as to be in contact with the surface of the decorative plate at an angle of 45 degrees, and the surface was rubbed by moving the scratch blade to pull. . At this time, the load applied to the scratch blade was changed by 100 g in the range of 300 to 1500 g load, and the scratched load at which the surface was damaged was confirmed.

(DuPont impact test)
The impact resistance of the decorative board was evaluated using a DuPont impact tester (based on JIS K5600-5-3). Specifically, a weight having a prescribed weight was dropped on the surface of the decorative board from each height of 10 cm, 20 cm, 30 cm, 40 cm, and 50 cm, and it was confirmed whether or not cracks occurred on the surface. The presence or absence of cracks at each height of 10 to 50 cm was confirmed.

DISCUSSION In the transparent resin layers produced in Examples 1 to 5, the thermal stability was improved with an increase in the amount of electron beam irradiation, and the values of the TMA dimensional change rate and the DMA storage modulus were improved. However, Example 4 (150 Mrad of electron beam irradiation) was slightly yellowish as a result of visual observation.

  The same ionomers as in Examples 1 to 5 were used for the transparent resin layers prepared in Comparative Examples 1 and 2, but the values of the TMA dimensional change rate and the DMA storage elastic modulus were low because the amount of electron beam irradiation was small. It is lower. In Comparative Examples 3 and 4 in which the high melting point ionomer was used, sufficient TMA dimensional change rate and DMA storage modulus were not obtained.

  The transparent resin layers produced in Examples 1 to 4 and Example 5 without the surface protective layer exhibited sufficient heat resistance and high physical properties in the Hoffman scratch test and the DuPont impact test. In Comparative Examples 1 and 2 using the same ionomer as in Examples 1 to 5, sufficient physical properties can be obtained in the Hoffman scratch test and the Dupont impact test, but there is a disadvantage that heat resistance is inferior. The transparent resin layers produced in Comparative Examples 3 and 4 have the problem that the ionomer is reduced by changing the ionomer, and the performance deteriorates in the Hoffman scratch test and the Dupont impact test.

  The transparent resin layer prepared in Comparative Example 5 was irradiated with an electron beam from the side of the coating film after the formation of the coating film of the composition for forming a transparent surface protective layer was performed without irradiating the ionomer film with an electron beam. As a result, the transparent resin layer and the transparent surface protective layer were formed at the same time, and the adhesive resin layer was decomposed by the electron beam, causing large swelling of the surface irregularities, making it impossible to evaluate.

Ionomer A: an ionomer comprising a combination of an ethylene-methacrylic acid copolymer and zinc ions

Ionomer B: Ionomer composed of a combination of an ethylene-methacrylic acid copolymer and zinc ion Ionomer C: Ionomer composed of a combination of an ethylene-methacrylic acid copolymer and zinc ion * Transparent without irradiating the ionomer film with an electron beam A transparent resin layer and a transparent surface protection layer are simultaneously formed by irradiating an electron beam from the side of the coating film after the formation of a coating film of the composition for forming a functional surface protection layer.

1. 1. decorative sheet 2. base sheet Picture pattern layer4. 4. transparent adhesive layer 5. transparent resin layer 6. Transparent surface protective layer Backside primer layer8. Decorative board substrate 9. Decorative board

Claims (7)

A transparent resin layer for a decorative sheet,
(1) The transparent resin layer is formed of an electron beam cross-linked product of an ionomer comprising an ethylene-methacrylic acid copolymer and zinc ions,
(2) The transparent resin layer has a melting point of 74 to 88 ° C measured by DSC, a dimensional change rate of 5% or less measured by thermomechanical analysis in a tensile mode of 90 ° C, and a tensile mode of 100 ° C. Storage elastic modulus measured by dynamic viscoelasticity analysis of 2 × 10 ⁷ to 1 × 10 ⁹ ,
A transparent resin layer, characterized in that: The transparent resin layer according to claim 1, wherein the storage elastic modulus measured by a dynamic viscoelasticity analysis in a tensile mode of 150 ° C is 5 × 10 ⁶ to 1 × 10 ⁹ . A method for producing a transparent resin layer for a decorative sheet,
(1) a step of obtaining a film by forming an ionomer composed of an ethylene-methacrylic acid copolymer and zinc ions, wherein the melting point of the ionomer measured by DSC is 88 to 94 ° C;
(2) a step of irradiating the film with an electron beam to obtain a transparent resin layer in which the ionomer is crosslinked, wherein the melting point of the transparent resin layer measured by DSC is 74 to 88 ° C. A step in which the dimensional change rate measured by thermomechanical analysis at 90 ° C. is 5% or less, and the storage elastic modulus measured by dynamic viscoelasticity analysis in tensile mode 100 ° C. is 2 × 10 ⁷ to 1 × 10 ⁹ 2,
A method for producing a transparent resin layer, comprising:   The manufacturing method according to claim 3, wherein the irradiation amount of the electron beam is 60 Mrad or more and 150 Mrad or less.   A decorative sheet comprising the transparent resin layer according to claim 1.   A decorative sheet comprising a laminate including at least the base sheet and the transparent resin layer according to claim 1 in the thickness direction.   A decorative board comprising a laminate including a decorative board base material and the decorative sheet according to claim 5 in order in the thickness direction.