JP5515370B2 - Decorative sheet and decorative plate using the decorative sheet - Google Patents

Description

  The present invention relates to a decorative sheet, and more particularly to a decorative sheet using a polylactic acid resin as a base material and a decorative plate using the decorative sheet.

Conventionally, as a decorative sheet, one using a sheet made of a polyvinyl chloride resin has been mainly used. Polyvinyl chloride sheets are not only excellent in printing and embossing, are easy to process into decorative sheets, but also have excellent post-processability such as V-cut and lapping, and are inexpensive.
On the other hand, styrene-based, olefin-based, urethane-based, polyamide-based, and ester-based thermoplastic elastomers and EVA (ethylene vinyl alcohol) can be used as an alternative to polyvinyl chloride resin for the purpose of improving heat resistance and surface contamination resistance. A decorative sheet using a copolymer) resin, a PET (polyethylene terephthalate) resin, an acrylic resin, or the like has been used.

  However, decorative sheets using these materials have the problem that the resin remains permanently as waste when discarded, which is undesirable from the viewpoint of protecting the natural environment. As a decorative sheet that can disappear naturally, a decorative sheet is proposed in which a base sheet made of a polylactic acid-based resin sheet containing poly-L-lactic acid as a main component is decorated, and a surface protective layer is laminated on the base sheet. (For example, refer to Patent Document 1 or Patent Document 2).

By the way, in recent years, non-petroleum resins such as the above-mentioned polylactic acid-based resins that do not use petroleum as a raw material have attracted attention from the viewpoint of environmental problems such as global warming accompanying an increase in carbon dioxide emission. That is, these are plastics using biomass, and those that attracted attention as biodegradable resins at the beginning of development have recently been reviewed from the viewpoint of plant-derived resins. In plant-derived resins, the carbon in the resin is carbon in which carbon dioxide in the atmosphere is immobilized by photosynthesis. Even if discarded by incineration, the total amount of carbon dioxide does not increase. It is a material.
Of these plant-derived resins, the above-mentioned polylactic acid resin is promising in view of various physical properties and the possibility of mass production, and a decorative sheet using a polylactic acid resin or a polylactic acid-based thermoplastic resin composition, etc. It has been proposed (see, for example, Patent Documents 3 to 5).

JP-A-11-129426 Japanese Patent Laid-Open No. 11-227147 JP 2006-7728 A JP 2008-73998 A JP 2008-80703 A

However, since polylactic acid resin is easily hydrolyzed, simply replacing a resin film, which is a conventional petrochemical product, with a polylactic acid resin or a polylactic acid-based thermoplastic resin composition increases the moisture permeability of the decorative sheet. There is a risk of warping of the decorative board to which is applied, and there is also a risk of causing a decrease in physical properties of the decorative sheet due to a decrease in hydrolysis resistance of the decorative sheet.
Under such circumstances, the present invention provides a decorative sheet suitable from the viewpoint of environmental protection, which can suppress the moisture permeability and suppress the discharge amount of carbon dioxide gas without reducing the hydrolysis resistance. Let it be an issue.

  As a result of intensive studies to achieve the above object, the present inventors have found that the above problem can be solved by using a polylactic acid resin as a base material and a polypropylene resin as an intermediate layer. . The present invention has been completed based on such findings.

That is, the present invention
(1) A decorative sheet having an intermediate layer, a colored layer and / or a pattern layer, and a surface protective layer on a substrate, wherein the substrate is made of a polylactic acid resin, the intermediate layer is made of a polypropylene resin, and A decorative sheet characterized in that the surface protective layer comprises a crosslinked and cured resin layer;
(2) The decorative sheet according to (1), wherein the base material has a thickness of 20 to 100 μm, and the intermediate layer has a thickness of 8 to 100 μm.
(3) The decorative sheet according to (1) or (2), which has an adhesive layer between the base material and the intermediate layer, and (4) any one of (1) to (3). A decorative board with a decorative sheet attached to the substrate,
Is to provide.

  ADVANTAGE OF THE INVENTION According to this invention, the decorative sheet suitable from the viewpoint of environmental protection which can suppress the discharge | emission amount of a carbon dioxide gas can be provided, without suppressing moisture permeability and reducing hydrolysis resistance.

It is a cross-sectional schematic diagram which shows an example of the decorative sheet of this invention.

The decorative sheet of the present invention is a decorative sheet having an intermediate layer, a colored layer and / or a pattern layer, and a surface protective layer on a base material, the base material is made of a polylactic acid resin, and the intermediate layer is a polypropylene resin. And the surface protective layer is a cross-linked and cured resin layer.
A typical structure of the decorative sheet of the present invention will be described with reference to FIG. FIG. 1 is a schematic cross-sectional view showing an example of a decorative sheet 1 of the present invention. In the example shown in FIG. 1, a uniform and uniform adhesive layer 7 that covers the entire surface of the base material 2 as desired, a uniform and uniform intermediate layer 3 that covers the entire surface of the adhesive layer 7, and a colored layer 4. The pattern layer 5 and the surface protective layer 6 made of a crosslinked and cured resin layer are laminated in this order. Further, a primer layer 8 is laminated on the back surface of the substrate 1 as desired.

The substrate 2 used in the present invention is made of polylactic acid resin. The polylactic acid resin is obtained by converting starch obtained from a plant raw material such as corn or potato or vegetable food waste into lactic acid by a method such as fermentation, and polymerizing the lactic acid.
The polylactic acid used in the present invention is a polymer mainly composed of L-lactic acid, D-lactic acid or DL-lactic acid unit, or a mixture of these polymers, and is a copolymer of optical isomers of lactic acid. There may be. That is, a copolymer obtained by copolymerizing D-lactic acid with respect to L-lactic acid and L-lactic acid with respect to D-lactic acid may be used. The polylactic acid may contain other hydroxycarboxylic acid or the like as a small amount of a copolymer component.
In addition, although the base material 2 in this invention consists essentially of polylactic acid resin and does not contain other resin, it prevents that a small amount of other resin mixes in the range which does not inhibit the effect of this invention. is not.
Moreover, various additives, such as a ultraviolet absorber, a light stabilizer, a flame retardant, a hydrolysis inhibitor, can be added to a polylactic acid resin as needed.

  The polymerization method of the polylactic acid resin is not particularly limited, and for example, it can be produced by a condensation polymerization method, a ring-opening polymerization method, or the like. In the condensation polymerization method, L-lactic acid, D-lactic acid or a mixture thereof is directly subjected to dehydration condensation polymerization to obtain a polylactic acid resin. In the ring-opening polymerization method, a lactate which is a cyclic dimer of lactic acid is used to obtain a polylactic acid resin using an appropriate catalyst while using a polymerization regulator or the like as necessary.

  The polylactic acid resin used in the present invention preferably has a weight average molecular weight in the range of 50,000 to 400,000. When the weight average molecular weight is 50,000 or more, good physical properties such as heat resistance can be obtained, and when it is 400,000 or less, good moldability can be obtained. From the above points, the weight average molecular weight of the polylactic acid resin is more preferably in the range of 100,000 to 250,000. The weight average molecular weight (Mw) is calculated as a polystyrene equivalent value by gel permeation chromatography (GPC).

The base material 2 in the decorative sheet of the present invention can be produced by using the polylactic acid resin as a film-like base material by, for example, a melt extrusion method. The substrate may be stretched or unstretched. In the case of stretching, both uniaxially stretched and biaxially stretched can be used, but usually biaxially stretched is preferable from the viewpoint of durability. That is, the biaxially stretched base material is more elastic and excellent in tensile strength and elongation. Furthermore, heat treatment (annealing) at about 80 to 120 ° C. can impart heat resistance and heat shrinkage. Moreover, the biaxially stretched base material has high transparency. The draw ratio is preferably about 2 to 4 times. On the other hand, an unstretched base material is easily plastically deformed and has good moldability.
The thickness of the substrate 2 used in the present invention is usually about 20 to 100 μm, and the range of 30 to 50 μm is preferable in consideration of workability and the like.

Moreover, you may mix | blend a pigment and / or dye with this base material 2 in order to provide concealability. The pigments can be classified into inorganic pigments and organic pigments. Inorganic pigments include titanium oxide white, zinc white, lead white, carbon black, petal, vermilion, yellow lead, ultramarine, cobalt blue, cobalt purple. , Zinc chromate and the like. Examples of organic pigments include phthalocyanine, dioxazine, and anthraquinone pigments, and typical examples include quinacridone, watch ang red, and dioxazine violet.
The dyes can be classified into natural dyes and synthetic dyes, and examples of natural dyes include indigo (indigo). Synthetic dyes include azo dyes, indigoid dyes, sulfur dyes, nitro dyes, nitroso dyes and the like. These pigments and dyes can be used singly or in combination of two or more, and inorganic pigments are optimal in order to have excellent light resistance and to conceal the substrate.

In addition, the base material 2 in the present invention can be easily subjected to an oxidation method or an unevenness method on one side or both sides as desired in order to improve adhesion to a layer provided thereon or a back layer provided as desired. An adhesion treatment (physical or chemical surface treatment) can be applied.
Examples of the oxidation method include corona discharge treatment, chromium oxidation treatment, flame treatment, hot air treatment, ozone / ultraviolet treatment method, and examples of the unevenness method include sand blast method and solvent treatment method. Of these surface treatments, the corona discharge treatment method is generally preferably used from the viewpoints of effects and operability.

  Next, the adhesive layer 7 shown in FIG. 1 is a layer provided as desired for the purpose of improving the adhesion between the substrate 2 and the intermediate layer 3. The material constituting the adhesive layer 7 is not particularly limited as long as the adhesion between the base material 2 and the intermediate layer 3 can be improved, but usually a polyester-based urethane resin (polyester-modified polyurethane resin or the like), A polyurethane resin, an acrylic / urethane copolymer resin, an acrylic resin, or the like is preferably used.

The intermediate layer 3 in the present invention is a layer made of polypropylene resin. By using a polypropylene resin, it is possible to suitably suppress moisture permeability of the decorative sheet 1 and improve hydrolysis resistance.
As this polypropylene resin, an isotactic polypropylene resin, an atactic polypropylene resin, a hard segment made of isotactic polypropylene and a soft segment made of atactic polypropylene are preferably in a mass ratio (10:90) to (90:10). May be a polypropylene resin mixed with a mass ratio (60:40) to (90:10), for example, a mass ratio (75:25) or (80:20), or a block polypropylene resin.
The polypropylene resin is usually colorless and transparent, but may be colored and transparent or opaque.

The polypropylene resin used for the intermediate layer 3 may be formed into a film by, for example, a calendar method, an inflation method, a T-die extrusion method, or the like.
The polypropylene resin may be stretched or unstretched. In the case of stretching, both uniaxially stretched and biaxially stretched can be used, but usually biaxially stretched is preferable from the viewpoint of durability.
The thickness of the intermediate layer 3 may be appropriately selected from the viewpoint of suppressing the moisture permeability of the decorative sheet 1 and improving the hydrolysis resistance, but the thickness of the intermediate layer 3 is determined between the decorative sheet and the substrate surface in the lapping process. 100 μm or less is preferable, 50 μm or less is more preferable, and 8 μm or more is preferable in terms of keeping moisture permeability low.
Moreover, since it is preferable that the base material 2 is a plant degree of 25% or more with respect to the total mass of a decorative sheet, the ratio of the thickness of the base material 2 and the intermediate layer 3 (the thickness of the base material / the intermediate layer) ) Is preferably 0.4 or more. If the intermediate layer 3 is 100 μm, the substrate 2 is preferably about 42 μm or more, and if the intermediate layer 3 is 50 μm, the substrate 2 is preferably about 20 μm or more.

  In order to improve the adhesiveness with the base material 2 or the colored layer 4 and / or the pattern layer 5, the intermediate layer 3 in the present invention is the same as the base material 2 as described above on one side or both sides as desired. Easy adhesion treatment (physical or chemical surface treatment) such as an uneven method can be performed.

In the decorative sheet 1 of the present invention, the colored layer 4 can be provided on the intermediate layer 3 in place of the pattern layer 5 or together with the pattern layer 5.
The colored layer 4 in the present invention functions as a concealing layer that conceals the color of the substrate 2 and / or the intermediate layer 3 and a decorative layer that imparts design properties to the decorative sheet 1. The colored layer 4 is also referred to as a concealing layer or a full surface solid layer.
The colored layer 4 is formed on the surface of the intermediate layer 3 by adjusting the color of the surface of the intermediate layer 3 and is formed when the base material 2 and / or the intermediate layer 3 is colored or uneven in color. Give the color. Usually, it is formed with an opaque color, but it may be formed with a colored transparent color and may make use of the pattern of the base. When the base material 2 and / or the intermediate layer 3 are utilized white, or when the base material 2 and / or the intermediate layer 3 are appropriately colored, it is not necessary to form the colored layer 4.
The colored layer 4 is a known coating method such as gravure coat, bar coat, gravure reverse coat, gravure offset coat, spinner coat, roll coat, reverse roll coat, comma coat, kiss coat, wheeler coat, dip coat, silk screen, Or it forms by well-known printing methods, such as gravure printing, offset printing, and flexographic printing.

Moreover, the pattern layer 5 in the present invention imparts design properties to the decorative sheet 1. The pattern layer 5 is provided in place of the colored layer 4 or together with the colored layer 4.
In the decorative sheet 1 of the present invention, when the picture layer 5 is provided together with the colored layer 4, the colored layer 4 and the picture layer 5 are usually provided on the intermediate layer 3 in this order.
The pattern layer 5 is formed by known printing methods such as gravure printing, offset printing, flexographic printing, and screen printing using various types of patterns using ink and a printing machine. The patterns include oak, teak, walnut and other grained or plank-like wood grain patterns, marble patterns (for example, travertine marble patterns), stone patterns that simulate the surface of rocks, and fabrics that simulate textures and cloth-like patterns. There are patterns, tiled patterns, brickwork patterns, etc., and there are also patterns such as marquetry and patchwork that combine these. These patterns can be formed by multicolor printing with normal yellow, red, blue, and black process colors, and also by multicolor printing with special colors prepared by preparing individual color plates that make up the pattern. Is done.

As the ink used for forming the colored layer 4 and / or the pattern layer 5 in the present invention, a binder, a colorant such as a pigment and a dye, an extender pigment, a solvent, a stabilizer, a plasticizer, a catalyst, and a curing agent are appropriately mixed. Used. The binder is not particularly limited, and examples thereof include polyurethane resins, vinyl chloride / vinyl acetate copolymer resins, vinyl chloride / vinyl acetate / acrylic copolymer resins, chlorinated polypropylene resins, acrylic resins, and polyesters. Arbitrary resins, polyamide resins, butyral resins, polystyrene resins, nitrocellulose resins, cellulose acetate resins and the like may be used alone or in admixture of two or more.
Colorants include carbon black (black), iron black, titanium white, antimony white, yellow lead, titanium yellow, petal, cadmium red, ultramarine, cobalt blue and other inorganic pigments, quinacridone red, isoindolinone yellow, phthalocyanine Organic pigments or dyes such as blue, metallic pigments composed of scaly foil pieces such as aluminum and brass, pearlescent pigments composed of scaly foil pieces such as titanium dioxide-coated mica and basic lead carbonate, and the like are used. In particular, it is preferable to add a luster pigment such as a pearl pigment or a metal pigment in order to express the “shine” of the grain well.

The surface protective layer 6 in the present invention is a layer made of a crosslinked and cured resin layer. The resin layer obtained by crosslinking and curing may be a resin layer obtained by thermosetting the thermosetting resin composition, but a resin layer obtained by crosslinking and curing the ionizing radiation curable resin composition is preferable.
As said thermosetting resin composition, 2 liquid curable urethane resin is preferable.
In addition, the ionizing radiation curable resin composition has an energy quantum capable of crosslinking and polymerizing molecules in electromagnetic waves or charged particle beams, that is, crosslinking by irradiating ultraviolet rays or electron beams, etc. It refers to a resin composition that cures. Specifically, it can be appropriately selected from polymerizable monomers, polymerizable oligomers or prepolymers conventionally used as ionizing radiation curable resin compositions.

  Typically, a (meth) acrylate monomer having a radical polymerizable unsaturated group in the molecule is suitable as the polymerizable monomer, and among them, a polyfunctional (meth) acrylate is preferable. Here, “(meth) acrylate” means “acrylate or methacrylate”. The polyfunctional (meth) acrylate is not particularly limited as long as it is a (meth) acrylate having two or more ethylenically unsaturated bonds in the molecule. Specifically, ethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) ) Acrylate, polyethylene glycol di (meth) acrylate, hydroxypivalate neopentyl glycol di (meth) acrylate, dicyclopentanyl di (meth) acrylate, caprolactone modified dicyclopentenyl di (meth) acrylate, ethylene oxide modified diphosphate ( (Meth) acrylate, allylated cyclohexyl di (meth) acrylate, isocyanurate di (meth) acrylate, trimethylolpropane tri (meth) acrylate, ethylene oxide modified trimethylo Propane tri (meth) acrylate, dipentaerythritol tri (meth) acrylate, propionic acid modified dipentaerythritol tri (meth) acrylate, pentaerythritol tri (meth) acrylate, propylene oxide modified trimethylolpropane tri (meth) acrylate, tris ( Acryloxyethyl) isocyanurate, propionic acid modified dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, ethylene oxide modified dipentaerythritol hexa (meth) acrylate, caprolactone modified dipentaerythritol hexa (meth) acrylate, etc. Is mentioned. These polyfunctional (meth) acrylates may be used singly or in combination of two or more.

  In the present invention, a monofunctional (meth) acrylate can be used in combination with the polyfunctional (meth) acrylate as long as the object of the present invention is not impaired, for the purpose of lowering the viscosity. Examples of monofunctional (meth) acrylates include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, cyclohexyl ( Examples include meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, and isobornyl (meth) acrylate. These monofunctional (meth) acrylates may be used alone or in combination of two or more.

  Next, as the polymerizable oligomer, an oligomer having a radical polymerizable unsaturated group in the molecule, for example, epoxy (meth) acrylate, urethane (meth) acrylate, polyester (meth) acrylate, polyether (meth) acrylate And the like. Here, the epoxy (meth) acrylate oligomer can be obtained, for example, by reacting (meth) acrylic acid with an oxirane ring of a relatively low molecular weight bisphenol type epoxy resin or novolak type epoxy resin and esterifying it. . Further, a carboxyl-modified epoxy (meth) acrylate oligomer obtained by partially modifying this epoxy (meth) acrylate oligomer with a dibasic carboxylic acid anhydride can also be used. The urethane (meth) acrylate oligomer can be obtained, for example, by esterifying a polyurethane oligomer obtained by reaction of polyether polyol or polyester polyol and polyisocyanate with (meth) acrylic acid. Examples of polyester (meth) acrylate oligomers include esterification of hydroxyl groups of polyester oligomers having hydroxyl groups at both ends obtained by condensation of polycarboxylic acid and polyhydric alcohol with (meth) acrylic acid, It can be obtained by esterifying the terminal hydroxyl group of an oligomer obtained by adding an alkylene oxide to a carboxylic acid with (meth) acrylic acid. The polyether (meth) acrylate oligomer can be obtained by esterifying the hydroxyl group of the polyether polyol with (meth) acrylic acid.

  Furthermore, other polymerizable oligomers include polybutadiene (meth) acrylate oligomers with high hydrophobicity having (meth) acrylate groups in the side chain of polybutadiene oligomers, and silicone (meth) acrylate oligomers having polysiloxane bonds in the main chain. In a molecule such as an aminoplast resin (meth) acrylate oligomer modified with an aminoplast resin having many reactive groups in a small molecule, or a novolak epoxy resin, bisphenol epoxy resin, aliphatic vinyl ether, aromatic vinyl ether, etc. There are oligomers having a cationic polymerizable functional group.

When an ultraviolet curable resin composition is used as the ionizing radiation curable resin composition, it is desirable to add about 0.1 to 5 parts by mass of the photopolymerization initiator with respect to 100 parts by mass of the resin composition. The initiator for photopolymerization can be appropriately selected from those conventionally used and is not particularly limited. For example, for a polymerizable monomer or polymerizable oligomer having a radically polymerizable unsaturated group in the molecule. Benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin-n-butyl ether, benzoin isobutyl ether, acetophenone, dimethylaminoacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2 -Phenylacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholino-propane-1 - 4- (2-hydroxyethoxy) phenyl-2 (hydroxy-2-propyl) ketone, benzophenone, p-phenylbenzophenone, 4,4′-diethylaminobenzophenone, dichlorobenzophenone, 2-methylanthraquinone, 2-ethylanthraquinone, 2 -Tertiary butylanthraquinone, 2-aminoanthraquinone, 2-methylthioxanthone, 2-ethylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, benzyl dimethyl ketal, acetophenone dimethyl ketal, etc. It is done.
Examples of the polymerizable oligomer having a cationic polymerizable functional group in the molecule include aromatic sulfonium salts, aromatic diazonium salts, aromatic iodonium salts, metallocene compounds, and benzoin sulfonic acid esters.
Moreover, as a photosensitizer, p-dimethylbenzoic acid ester, tertiary amines, a thiol type sensitizer, etc. can be used, for example.
In the present invention, it is preferable to use an electron beam curable resin composition as the ionizing radiation curable resin composition. This is because the electron beam curable resin composition can be made solvent-free, is more preferable from the viewpoint of environment and health, and does not require a photopolymerization initiator and can provide stable curing characteristics.
In the present invention, as will be described in detail later, the uncured resin layer constituting the surface protective layer is irradiated with ionizing radiation such as an electron beam and ultraviolet rays to cure the uncured resin layer.

Moreover, various additives can be mix | blended with the ionizing radiation-curable resin composition in this invention according to the desired physical property of the cured resin layer obtained. Examples of this additive include a weather resistance improver, an abrasion resistance improver, a polymerization inhibitor, a crosslinking agent, an infrared absorber, an antistatic agent, an adhesion improver, a leveling agent, a thixotropic agent, a coupling agent, A plasticizer, an antifoamer, a filler, a solvent, a coloring agent, etc. are mentioned.
Here, as the weather resistance improving agent, an ultraviolet absorber or a light stabilizer can be used. The ultraviolet absorber may be either inorganic or organic. As the inorganic ultraviolet absorber, titanium dioxide, cerium oxide, zinc oxide or the like having an average particle size of about 5 to 120 nm can be preferably used. Examples of the organic ultraviolet absorber include benzotriazole-based compounds, specifically 2- (2-hydroxy-5-methylphenyl) benzotriazole, 2- (2-hydroxy-3,5-di-tert-). Amylphenyl) benzotriazole, 3- [3- (benzotriazol-2-yl) -5-tert-butyl-4-hydroxyphenyl] propionic acid ester of polyethylene glycol, and the like. On the other hand, examples of the light stabilizer include hindered amines, specifically 2- (3,5-di-tert-butyl-4-hydroxybenzyl) -2′-n-butylmalonate bis (1,2,2). , 6,6-pentamethyl-4-piperidyl), bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate, tetrakis (2,2,6,6-tetramethyl-4-piperidyl)- 1,2,3,4-butanetetracarboxylate and the like. In addition, as the ultraviolet absorber or light stabilizer, a reactive ultraviolet absorber or light stabilizer having a polymerizable group such as a (meth) acryloyl group in the molecule can be used.

Examples of the wear resistance improver include, for inorganic substances, spherical particles such as α-alumina, silica, kaolinite, iron oxide, diamond, and silicon carbide. Examples of the particle shape include a sphere, an ellipsoid, a polyhedron, a scale shape, and the like. Although there is no particular limitation, a spherical shape is preferable. Organic materials include synthetic resin beads such as cross-linked acrylic resin and polycarbonate resin. The particle size is usually about 30 to 200% of the film thickness. Among these, spherical α-alumina is particularly preferable because it has high hardness and a large effect on improving wear resistance, and it is relatively easy to obtain spherical particles.
Examples of the polymerization inhibitor include hydroquinone, p-benzoquinone, hydroquinone monomethyl ether, pyrogallol, and t-butylcatechol. Examples of the crosslinking agent include a polyisocyanate compound, an epoxy compound, a metal chelate compound, an aziridine compound, and an oxazoline compound. Used.
As the filler, for example, barium sulfate, talc, clay, calcium carbonate, aluminum hydroxide and the like are used.
Examples of the colorant include known coloring pigments such as quinacridone red, isoindolinone yellow, phthalocyanine blue, phthalocyanine green, titanium oxide, and carbon black.
As the infrared absorber, for example, a dithiol metal complex, a phthalocyanine compound, a diimmonium compound, or the like is used.

In the surface protective layer 6 according to the present invention, the above-mentioned ionizing radiation-curable component, the polymerizable monomer, the polymerizable oligomer, and various additives are homogeneously mixed at predetermined ratios, respectively, from the ionizing radiation-curable resin composition. A coating solution is prepared. The viscosity of the coating solution is not particularly limited as long as it is a viscosity capable of forming an uncured resin layer on the surface of the colored layer 4 and / or the pattern layer 5 by a coating method described later.
In the present invention, the coating liquid prepared in this way is applied to the surface of the colored layer 4 and / or the pattern layer 5 so that the thickness after curing is 1 to 20 μm, It coats by well-known systems, such as roll coat, reverse roll coat, comma coat, preferably gravure coat, and forms an uncured resin layer. When the thickness after curing is 1 μm or more, a cured resin layer having a desired function is obtained. The thickness of the surface protective layer after curing is preferably about 2 to 20 μm.

In the surface protective layer 6 according to the present invention, the uncured resin layer is cured by irradiating the uncured resin layer formed as described above with ionizing radiation such as an electron beam or ultraviolet rays. Here, when an electron beam is used as the ionizing radiation, the acceleration voltage can be appropriately selected according to the resin used and the thickness of the layer, but the uncured resin layer is usually cured at an acceleration voltage of about 70 to 300 kV. preferable.
In electron beam irradiation, the transmission capability increases as the acceleration voltage increases. Therefore, when using a base material that deteriorates due to the electron beam as the base material, the transmission depth of the electron beam and the thickness of the resin layer are substantially equal. By selecting the accelerating voltage so as to be equal to each other, it is possible to suppress the irradiation of the electron beam to the base material, and to minimize the deterioration of the base material due to the excessive electron beam.
The irradiation dose is preferably such that the crosslink density of the resin layer is saturated, and is usually selected in the range of 5 to 300 kGy (0.5 to 30 Mrad), preferably 10 to 50 kGy (1 to 5 Mrad).

Furthermore, there is no restriction | limiting in particular as an electron beam source, For example, various electron beam accelerators, such as a cock loft Walton type, a van de Graft type, a resonance transformer type, an insulated core transformer type, or a linear type, a dynamitron type, a high frequency type, etc. Can be used.
When ultraviolet rays are used as the ionizing radiation, those containing ultraviolet rays having a wavelength of 190 to 380 nm are emitted. There is no restriction | limiting in particular as an ultraviolet-ray source, For example, a high pressure mercury lamp, a low pressure mercury lamp, a metal halide lamp, a carbon arc lamp, etc. are used.
The cured resin layer thus formed has various functions by adding various additives, for example, a so-called hard coat function, anti-fogging coat function, and anti-fouling coat having high hardness and scratch resistance. A function, an antiglare coating function, an antireflection coating function, an ultraviolet shielding coating function, an infrared shielding coating function, and the like can also be imparted.

The decorative sheet 1 of the present invention can be attached to various substrates and used as a decorative board. Therefore, in order to strengthen the adhesion between the decorative sheet 1 and various substrates, a primer layer 8 is provided on the back surface of the base material 2 as desired. The primer layer 8 can be formed by applying a known primer agent. Examples of the primer agent include a urethane resin primer agent made of acrylic modified urethane resin, a primer agent made of urethane-cellulose resin (for example, a resin made by adding hexamethylene diisocyanate to a mixture of urethane and nitrified cotton), and the like. Is mentioned.
Although the thickness of a primer layer is not specifically limited, Usually, 0.01-10 micrometers, Preferably it is about 0.5-5 micrometers.

The decorative sheet 1 of the present invention may further be provided with a film layer on the back surface of the substrate 2 as desired. With the sandwich structure in which the base material 2 made of polylactic acid resin is sandwiched between the intermediate layer 3 and the film layer, moisture permeability is further suppressed, and hydrolysis resistance is further improved. In this case, an adhesive layer may be provided between the substrate 2 and the film layer as desired, and a primer layer 8 may be provided on the back surface of the film layer.
As the film layer, polypropylene resin and PET resin are used.

  The decorative board of the present invention is formed by attaching the decorative sheet 1 to various substrates. Here, the board | substrate used as a to-be-adhered body is not specifically limited, Wooden board | plates, such as a timber, ceramic material, a plastic sheet, a metal plate, etc. can be selected suitably according to a use. When these substrates, particularly plastic sheets, are used as substrates, the above oxidation method may be applied to one side or both sides as desired, as with the base material 2 and the intermediate layer 3, in order to improve adhesion to the decorative sheet 1. And easy adhesion treatment (physical or chemical surface treatment) such as a method for forming irregularities.

Examples of wood-based boards include veneer of various materials such as cedar, firewood, firewood, pine, lawan, teak, and merapie, wood veneer, wood plywood, particle board, medium density fiber board (MDF), and other wood materials. It is done. These can be used alone or in a stacked manner. The wooden board includes not only a wooden board but also a plastic board containing paper powder and reinforced paper having strength.
Examples of the ceramic material include ceramic building materials such as a gypsum plate, a calcium silicate plate, and a wood cement plate, ceramics, glass, firewood, fired tiles, plates made mainly of volcanic ash, and the like.
In addition to these, composites of various materials, such as fiber reinforced plastic (FRP) plates, paper honeycombs with iron plates pasted on both sides, and two aluminum plates sandwiched with polyethylene resin can also be used as the base material. .

As a plastic sheet, what consists of various synthetic resins is mentioned. Synthetic resins include polyethylene resin, polypropylene resin, polymethylpentene resin, polyvinyl chloride resin, polyvinylidene chloride resin, polyvinyl alcohol resin, vinyl chloride-vinyl acetate copolymer resin, ethylene-vinyl acetate copolymer resin, ethylene-vinyl. Representative examples include alcohol copolymer resin, polyethylene terephthalate resin, polybutylene terephthalate resin, polyethylene naphthalate-isophthalate copolymer resin, polymethyl methacrylate resin, polyethyl methacrylate resin, polybutyl acrylate resin, nylon 6 or nylon 66 And polyamide resin, cellulose triacetate resin, cellophane, polystyrene resin, polycarbonate resin, polyarylate resin, polyimide resin, and the like.
As a metal plate, what consists of aluminum, iron, stainless steel, or copper can be used, for example, and what gave these metals by plating etc. can also be used.

  Further, the substrate may be subjected to a treatment such as forming a primer layer, or a coating for adjusting the color or a pattern from a design viewpoint may be formed in advance. As a substrate to be an adherend, plate materials such as flat plates and curved plates of various materials, or three-dimensional shaped articles (molded products) in which the above materials are used alone or in combination are targeted.

  A backing material such as Japanese paper, Western paper, synthetic paper, non-woven fabric, woven fabric, cold paper, impregnated paper, synthetic resin sheet, or the like may be attached to the decorative sheet. By sticking the backing material, it acts to reinforce the decorative sheet itself, prevent cracking and tearing of the decorative sheet, prevent bleeding of the adhesive to the decorative sheet surface, and prevent the occurrence of defective products, Handling becomes easy and productivity can be improved.

  Thus, a substrate on which a decorative sheet is placed every leaf or continuously via an adhesive is attached to a cold press, a hot press, a roll press, a laminator, a lapping, an edge pasting machine, a vacuum press, etc. The decorative sheet is bonded to the substrate surface by pressing with an apparatus to obtain a decorative plate.

The adhesive is applied using an application device such as a spray, spreader, or bar coater. As the adhesive, vinyl acetate resin-based, urea resin-based, melamine resin-based, phenol resin-based, isocyanate-based adhesives, etc., are used alone or as a mixed adhesive obtained by arbitrarily mixing them. As needed, talc, calcium carbonate, clay, titanium white and other inorganic powders, wheat flour, wood flour, plastic powder, coloring agents, insect repellents, fungicides and the like can be added and mixed in the adhesive. . In general, the adhesive is applied to the substrate surface with a solid content of 35 to 80% by mass and an application amount of 50 to 300 g / m ² .
Adhesion of the decorative sheet on the substrate is usually performed by forming an adhesive layer on the back surface of the decorative sheet of the present invention and adhering the substrate or applying an adhesive on the substrate and adhering the decorative sheet. Etc.

  The decorative board manufactured as described above is also optionally cut by the decorative board, and optionally decorated such as grooving and chamfering on the surface and the mouth using a cutting machine such as a router or a cutter. Can be applied.

EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by this example.
(Evaluation method)
The decorative sheets obtained in Examples, Comparative Examples and Reference Examples were evaluated by the following methods.
(1) Moisture permeability According to JIS Z 0208, moisture permeability (g / m ² · 24h) was measured at 40 ° C., relative humidity 90%, and 24 hours.
A: The moisture permeability was 0 or more and 12 or less.
○: The water vapor transmission rate was more than 12 and 18 or less.
(Triangle | delta): The water vapor transmission rate exceeded 18 and was 30 or less.
X: The moisture permeability exceeded 30.
(2) Hydrolysis resistance The test sample was immersed in warm water at 70 ° C and evaluated according to the following evaluation criteria.
A: The elongation at break after immersion for 300 hours was 20% or more.
A: The elongation at break after 200 hours immersion was 20% or more, and the elongation at break after immersion for 300 hours was less than 20%.
Δ: The elongation at break after immersion for 100 hours was 20% or more, and the elongation at break after immersion for 200 hours was less than 20%.
X: The elongation at break after immersion for 100 hours was less than 20%.
The elongation at break was determined by taking a test piece for tensile test (JIS-K 7127 test piece type 1B size) from the test sample after immersion and measuring the strength at a rate of 100 mm / min in the tensile test. The measurement was interrupted when one of the layers broke, and the elongation at that time was defined as the elongation at break.
(3) Flat sticking property The test sample was evaluated according to the following evaluation criteria.
A: No floating occurs between the decorative sheet and the substrate surface.
X: Floating occurs between the decorative sheet and the substrate surface.
(4) Bending lapping workability The test sample was evaluated according to the following evaluation criteria.
A: No floating occurs between the decorative sheet and the substrate surface at the lapping portion.
X: Floating occurs between the decorative sheet and the substrate surface at the lapping portion.

Example 1
Apply a transparent polyester-based urethane resin 5-10 g / m ² (dry) on the surface of a substrate made of a white polylactic acid resin film (Mitsubishi Resin Co., Ltd., trade name “Ecology SW”) having a thickness of 40 μm. After forming the adhesive layer by the above, a transparent polypropylene resin film (trade name “FOR-BT”, 20 μm in thickness, manufactured by Phutamura Chemical Co., Ltd.) biaxially stretched was dry laminated to form an intermediate layer.
Next, on the intermediate layer, titania as a white pigment is added to a polyurethane resin (weight average molecular weight (Mw); 55000, Tg; −30 ° C.) so as to have a PV ratio of 2.4, and a nurate-modified hexa as a curing agent. A colored layer was formed by applying a polyurethane resin composition added with methylene diisocyanate at a dry weight of 10 g / m ² . On the colored layer, a woodgrain pattern layer was gravure-printed using an ink made of a nitrocellulose alkyd resin (manufactured by The Inktec Co., Ltd., KL-MAX).
Next, 60 parts by mass of ethylene oxide-modified trimethylolpropane ethylene oxide triacrylate, which is a trifunctional acrylate monomer, and 40 parts by mass of dipentaerythritol hexaacrylate, which is a hexafunctional acrylate monomer, are formed on the pattern layer. An electron beam curable resin composition comprising 15 parts by mass of particles and 1 part by mass of a silicone acrylate prepolymer was applied at 5 g / m ² by a gravure offset coater method. After coating, an electron beam with an acceleration voltage of 175 kV and an irradiation dose of 50 kGy (5 Mrad) was irradiated to cure the electron beam curable resin composition, thereby forming a surface protective layer. Next, curing was performed at 40 ° C. for 72 hours. Then, the primer layer was formed by apply | coating 3 g / m < ² > (dry) of the primer agent which consists of acrylic modified urethane resin to the back surface of the base material of the obtained lamination sheet, and the decorative sheet was obtained.
This decorative sheet was evaluated by the above method. The results are shown in Table 1.

Comparative Example 1
A decorative sheet having a layer structure in which the intermediate layer and the adhesive layer were removed from the decorative sheet of Example 1 was obtained. This decorative sheet was evaluated by the above method. The results are shown in Table 1.

Comparative Example 2
A decorative sheet was obtained in the same manner as in Example 1 except that the transparent polypropylene resin film of Example 1 was changed to a transparent PET resin film (trade name “T600E25N”, thickness 25 μm, manufactured by Mitsubishi Plastics, Inc.). This decorative sheet was evaluated by the above method. The results are shown in Table 1.

Reference example 1
Comparative Example 1 except that a colored polyester resin film (Mitsubishi Resin Co., Ltd., polyethylene terephthalate, trade name “Z210”) having a thickness of 45 μm was used as the substrate 2 and the primer layer on the back surface of the substrate was not provided. A decorative sheet was obtained in the same manner. This decorative sheet was evaluated by the above method. The results are shown in Table 1.

  As is apparent from Table 1, the decorative sheet of Example 1 has lower moisture permeability than Comparative Examples 1 and 2 and the reference example, and when used for a wooden decorative board, the decorative sheet is further warped. It became difficult. Furthermore, compared with the comparative example 1, hydrolysis resistance improved significantly and it could have hydrolysis resistance equivalent to the reference example which does not use a polylactic acid resin.

  Since the so-called carbon neutral material is used as the base material, the decorative sheet of the present invention is an environmentally friendly decorative sheet. Moreover, since it has a moisture permeability equal to or higher than that when using a PET film as a base material and equivalent hydrolysis resistance, it can be used for various purposes as a decorative board, for example, interiors of buildings such as walls, ceilings, floors, etc. Used for exterior materials, window frames, doors, handrails, skirting boards, edges, exterior decorative panels for furniture such as malls, decorative panels for kitchens, furniture or light electrical appliances, cabinets for OA equipment, interiors and exteriors of vehicles, etc. Can do. In particular, it can be suitably used for various building materials such as interior doors such as indoor doors, storage doors, cupboards, furniture, kitchens, cabinets, surface decorative plates, and interior walls.

1. Cosmetic sheet Base material 3. Intermediate layer 4. 4. Colored layer Pattern layer 6. Surface protective layer 7. Adhesive layer 8. Primer layer

Claims (4)

A decorative sheet formed by laminating an adhesive layer on a base material, an intermediate layer on the adhesive layer, a colored layer and / or a picture layer on the intermediate layer, and a surface protective layer on the colored layer and / or the picture layer The base material is made of polylactic acid resin, and the adhesive layer is selected from the group consisting of polyester urethane resin, polyurethane resin, acrylic / urethane copolymer resin and acrylic resin, and an intermediate layer A decorative sheet, characterized in that is made of a polypropylene resin and the surface protective layer is a crosslinked and cured resin layer.   The decorative sheet according to claim 1, wherein the base material has a thickness of 20 to 100 µm, and the intermediate layer has a thickness of 8 to 100 µm. It said substrate and said adhesive layer, and formed by laminating the to contact the adhesive layer and the intermediate layer directly, the decorative sheet according to claim 1 or 2. The decorative board which stuck the decorative sheet in any one of Claims 1-3 to the board | substrate.

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