JP2011073373A - Decorative sheet, and decorative resin molded article using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a decorative sheet having a surface protective layer compatibly having both of scratch resistance and three-dimensional moldability. <P>SOLUTION: The decorative sheet has at least a surface protective layer on a base material. The surface protective layer contains at least polycarbonate (meth)acrylate and multi-functional (meth)acrylate, and consists of a cured matter of an ionizing radiation-curable resin composition with a mass ratio of the polycarbonate (meth)acrylate to multi-functional (meth)acrylate of 98:2 to 70:30. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a decorative sheet having a surface protective layer made of a cured product of a specific ionizing radiation curable resin composition.

  Decorated resin molded products decorated by laminating decorative sheets on the surface of molded products are used in various applications such as vehicle interior parts. As a molding method of such a decorative resin molded product, the decorative sheet is formed into a three-dimensional shape in advance by a vacuum mold, the molded sheet is inserted into an injection mold, and the resin in a fluid state is placed in the mold. An insert molding method (for example, refer to Patent Document 1) for injecting a resin and a molded sheet, and a decorative sheet inserted into a mold at the time of injection molding, and a molten resin injected and injected into a cavity There is an injection molding simultaneous decorating method (for example, see Patent Document 2 and Patent Document 3) that integrates and decorates the surface of the resin molded body.

  The decorative resin molded product is provided with a surface protective layer for the purpose of improving the scratch resistance of the surface. However, in the molding method of the decorative resin molded product described above, in the insert molding method, the decorative sheet is preliminarily formed into a three-dimensional (three-dimensional) shape by a vacuum mold, and in the simultaneous injection molding method, the decorative sheet is preliminarily used. During molding or injection of molten resin, in the process of drawing and adhering along the inner peripheral surface of the cavity, the decorative sheet is molded by vacuum / pneumatic action or by pulling of molten resin pressure or shear stress. Since the film is stretched beyond the minimum necessary amount to conform to the shape, there has been a problem that the surface protective layer of the curved surface portion of the molded product is cracked.

For the above-mentioned problems, by using an ionizing radiation curable resin such as an ultraviolet curable resin as a surface protective layer and increasing the crosslink density of the resin forming the surface protective layer of the decorative sheet, Although attempts have been made to improve the wear resistance and scratch resistance of the surface, there is still a problem that cracks occur in the curved surface of the molded product during molding.
In addition, an attempt has been made to use an ionizing radiation curable resin such as an ultraviolet curable resin as a surface protective layer, to make a semi-cured state in the decorative sheet stage, and to completely cure after the decorative molding (Patent Document 4). The surface protective layer containing the uncured resin component is easily damaged and difficult to handle, and there is a problem of mold contamination due to the uncured resin component adhering to the mold. In order to solve this problem, there is a method of providing a protective film on the semi-cured surface protective layer. However, the manufacturing is complicated and the cost is increased.
Therefore, a surface protective layer that can achieve both scratch resistance and three-dimensional formability is desired.

  By the way, a polycarbonate (meth) acrylate-containing resin composition is known (for example, Patent Documents 5 to 10). There is an example using a resin composition containing a small amount (Patent Document 11), but there was no example using polycarbonate (meth) acrylate for the surface protective layer of the decorative sheet.

JP 2004-322501 A Japanese Patent Publication No. 50-19132 Japanese Examined Patent Publication No. 61-17255 Japanese Patent Application Laid-Open No. 6-134859 Japanese Patent Application Laid-Open No. 64-24809 JP-A-3-181517 Japanese Unexamined Patent Publication No. 7-44913 JP 2000-53887 A JP 2000-198840 A JP 2000-351843 A JP 2003-145573 A

  This invention makes it a subject to provide the decorating sheet which has a surface protection layer which can make a scratch resistance and three-dimensional moldability compatible in such a condition.

  As a result of intensive studies to solve the above problems, the present inventors have solved the above problems by making the surface protective layer of the decorative sheet a cured product of a specific ionizing radiation curable resin composition. Found to get. The present invention has been completed based on such findings.

That is, the present invention
(1) A decorative sheet having at least a surface protective layer on a substrate, wherein the surface protective layer contains at least polycarbonate (meth) acrylate and polyfunctional (meth) acrylate, and the polycarbonate (meth) acrylate And a mass ratio of the polyfunctional (meth) acrylate is a cured product of an ionizing radiation curable resin composition having a polycarbonate (meth) acrylate: polyfunctional (meth) acrylate = 98: 2 to 70:30. Decorative sheet,
(2) The decorative sheet according to (1), wherein the polyfunctional (meth) acrylate is trifunctional or higher.
(3) The decorative sheet according to (1) or (2) above, wherein the weight average molecular weight of the polycarbonate (meth) acrylate exceeds 2,000, and (4) the above (1) to (1) The present invention provides a decorative resin molded product using the decorative sheet according to any one of 3).

  In the decorative sheet of the present invention, the surface protective layer satisfies both excellent scratch resistance and good three-dimensional formability at the same time. Therefore, in both the insert molding method and the simultaneous injection molding method, the surface protective layer is used. Thus, it is possible to obtain a decorated resin molded product that is not cracked or the like and that can be easily three-dimensionally molded.

It is a schematic diagram which shows the cross section of the one aspect | mode of the decorating sheet of this invention.

The decorative sheet of the present invention is a decorative sheet having at least a surface protective layer on a substrate, and the surface protective layer contains at least a polycarbonate (meth) acrylate and a polyfunctional (meth) acrylate, and From the cured product of the ionizing radiation curable resin composition in which the mass ratio of the polycarbonate (meth) acrylate and the polyfunctional (meth) acrylate is polycarbonate (meth) acrylate: polyfunctional (meth) acrylate = 98: 2 to 70:30 It is characterized by becoming.
Here, the ionizing radiation curable resin composition refers to a composition containing an ionizing radiation curable resin. The ionizing radiation curable resin refers to a resin having an energy quantum capable of crosslinking and polymerizing molecules in an electromagnetic wave or a charged particle beam, that is, a resin that is crosslinked and cured by irradiation with ultraviolet rays or electron beams.
In the present invention, at least polycarbonate (meth) acrylate and polyfunctional (meth) acrylate are used as the ionizing radiation curable resin. When the mass ratio of the polycarbonate (meth) acrylate and the polyfunctional (meth) acrylate is larger than 98: 2 (that is, when the amount of the polycarbonate (meth) acrylate exceeds 98 mass%), the scratch resistance is lowered. On the other hand, when the mass ratio of the polycarbonate (meth) acrylate and the polyfunctional (meth) acrylate is smaller than 70:30 (that is, when the amount of the polycarbonate (meth) acrylate is less than 70% by mass), the three-dimensional moldability is lowered. End up.
Preferably, the mass ratio of polycarbonate (meth) acrylate and polyfunctional (meth) acrylate is 95: 5 to 80:20.
In the present invention, “(meth) acrylate” means “acrylate or methacrylate”, and other similar things have the same meaning.

The polycarbonate (meth) acrylate used in the present invention is not particularly limited as long as it has a carbonate bond in the polymer main chain and has (meth) acrylate in the terminal or side chain. This (meth) acrylate preferably has two or more functional groups from the viewpoint of crosslinking and curing.
Said polycarbonate (meth) acrylate is obtained by converting a part or all of the hydroxyl group of polycarbonate polyol into (meth) acrylate (acrylic acid ester or methacrylic acid ester), for example. This esterification reaction can be performed by a normal esterification reaction. For example, 1) a method of condensing polycarbonate polyol and acrylic acid halide or methacrylic acid halide in the presence of a base, 2) a method of condensing polycarbonate polyol and acrylic acid anhydride or methacrylic acid anhydride in the presence of a catalyst, Or 3) the method of condensing polycarbonate polyol and acrylic acid or methacrylic acid in the presence of an acid catalyst.

The polycarbonate polyol is a polymer having a carbonate bond in the polymer main chain and having 2 or more, preferably 2 to 50, more preferably 3 to 50 hydroxyl groups at the terminal or side chain. A typical method for producing this polycarbonate polyol is a method by a polycondensation reaction from a diol compound (A), a trihydric or higher polyhydric alcohol (B), and a compound (C) to be a carbonyl component.
The diol compound (A) used as a raw material is represented by the general formula HO—R ₁ —OH. Here, R ₁ is a divalent hydrocarbon group having 2 to 20 carbon atoms, and the group may contain an ether bond. For example, a linear or branched alkylene group, a cyclohexylene group, or a phenylene group.

  Specific examples of the diol compound include ethylene glycol, 1,2-propylene glycol, diethylene glycol, dipropylene glycol, triethylene glycol, polyethylene glycol, neopentyl glycol, 1,3-propanediol, 1,4-butanediol, 1 , 5-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, 1,3-bis (2-hydroxyethoxy) benzene, 1,4-bis (2 -Hydroxyethoxy) benzene, neopentyl glycol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol and the like. These diols may be used alone or in admixture of two or more.

  Examples of the trihydric or higher polyhydric alcohol (B) include alcohols such as trimethylolpurpan, trimethylolethane, pentaerythritol, ditrimethylolpropane, dipentaerythritol, glycerin and sorbitol. Furthermore, alcohols having a hydroxyl group in which 1 to 5 equivalents of ethylene oxide, propylene oxide, or other alkylene oxide are added to the hydroxyl group of these polyhydric alcohols may be used. These polyhydric alcohols may be used alone or in combination of two or more.

  The compound (C) serving as the carbonyl component is any compound selected from carbonic acid diesters, phosgene, and equivalents thereof. Specific examples thereof include carbonic acid diesters such as dimethyl carbonate, diethyl carbonate, diisopropyl carbonate, diphenyl carbonate, ethylene carbonate and propylene carbonate, phosgene, and halogenated formates such as methyl chloroformate, ethyl chloroformate and phenyl chloroformate. Etc. These may be used alone or in admixture of two or more.

  The polycarbonate polyol is synthesized by subjecting the above-described diol compound (A), a trihydric or higher polyhydric alcohol (B), and a compound (C) to be a carbonyl component to a polycondensation reaction under general conditions. . For example, the charged molar ratio of the diol compound (A) to the polyhydric alcohol (B) is preferably in the range of 50:50 to 99: 1, and the diol compound (C) as the carbonyl component ( The charged molar ratio of A) to the polyhydric alcohol (B) is preferably 0.2 to 2 equivalents with respect to the hydroxyl group of the diol compound and polyhydric alcohol.

The number of equivalents (eq./mol) of hydroxyl groups present in the polycarbonate polyol after the polycondensation reaction at the above charge ratio is 3 or more on average in one molecule, preferably 3 to 50, more preferably 3 to 20. Within this range, a necessary amount of (meth) acrylate groups are formed by the esterification reaction described later, and moderate flexibility is imparted to the polycarbonate (meth) acrylate resin. The terminal functional group of this polycarbonate polyol is usually an OH group, but a part thereof may be a carbonate group.
The method for producing the polycarbonate polyol described above is described in, for example, JP-A No. 64-1726. The polycarbonate polyol can also be produced by an ester exchange reaction between a polycarbonate diol and a trihydric or higher polyhydric alcohol as described in JP-A-3-181517.

  The molecular weight of the polycarbonate (meth) acrylate used in the present invention is preferably 500 or more, more preferably 1,000 or more, as measured by GPC analysis and converted to standard polystyrene. More preferably, it exceeds 2,000. The upper limit of the weight average molecular weight of the polycarbonate (meth) acrylate is not particularly limited, but is preferably 100,000 or less and more preferably 50,000 or less from the viewpoint of controlling the viscosity not to be too high. From the viewpoint of achieving both scratch resistance and three-dimensional formability, it is more preferably more than 2,000 and not more than 50,000, and particularly preferably 5,000 to 20,000.

The polyfunctional (meth) acrylate used for this invention should just be bifunctional or more (meth) acrylate, and there is no restriction | limiting in particular. However, trifunctional or higher functional (meth) acrylates are preferred from the viewpoint of curability. Here, bifunctional means having two ethylenically unsaturated bonds {(meth) acryloyl group} in the molecule.
The polyfunctional (meth) acrylate may be either an oligomer or a monomer, but a polyfunctional (meth) acrylate oligomer is preferable from the viewpoint of improving three-dimensional moldability.

  Examples of the polyfunctional (meth) acrylate oligomer include urethane (meth) acrylate oligomers, epoxy (meth) acrylate oligomers, polyester (meth) acrylate oligomers, and polyether (meth) acrylate oligomers. Here, the urethane (meth) acrylate oligomer can be obtained, for example, by esterifying a polyurethane oligomer obtained by the reaction of polyether polyol or polyester polyol and polyisocyanate with (meth) acrylic acid. 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. 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. Examples of polyester (meth) acrylate oligomers include esterification of hydroxyl groups of polyester oligomers having hydroxyl groups at both ends obtained by condensation of polyvalent carboxylic acids and polyhydric alcohols with (meth) acrylic acid, It can be obtained by esterifying the terminal hydroxyl group of an oligomer obtained by adding alkylene oxide to a monovalent 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 polyfunctional (meth) acrylate oligomers include polybutadiene (meth) acrylate oligomers with high hydrophobicity having (meth) acrylate groups in the side chain of polybutadiene oligomers, and silicones (meta-methacrylate) having polysiloxane bonds in the main chain. ) Acrylate oligomers, aminoplast resin (meth) acrylate oligomers obtained by modifying aminoplast resins having many reactive groups in small molecules.

Moreover, as said polyfunctional (meth) acrylate monomer, 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, hydroxypivalic acid neopentyl glycol di (meth) acrylate, dicyclopentanyl di (meth) acrylate, caprolactone modified di Cyclopentenyl di (meth) acrylate, ethylene oxide modified phosphoric acid di (meth) acrylate, allylated cyclohexyl di (meth) acrylate, isocyanurate di (meth) acrylate, trimethylol proppant (Meth) acrylate, ethylene oxide modified trimethylolpropane tri (meth) acrylate, dipentaerythritol tri (meth) acrylate, propionic acid modified dipentaerythritol tri (meth) acrylate, pentaerythritol tri (meth) acrylate, propylene oxide modified trimethylol Propane 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 Examples include dipentaerythritol hexa (meth) acrylate.
The polyfunctional (meth) acrylate oligomer and polyfunctional (meth) acrylate monomer described above may be used alone 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.

When using an ultraviolet curable resin composition as the ionizing radiation curable resin composition, it is desirable to add about 0.1 to 5 parts by mass of the photopolymerization initiator to 100 parts by mass of the ultraviolet curable resin. . The initiator for photopolymerization can be appropriately selected from those conventionally used, and is not particularly limited. For example, 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-propan-1-one, 4- (2-hydroxyethoxy) phenyl-2 (hydroxy-2-propyl) ketone, Nzophenone, p-phenylbenzophenone, 4,4′-diethylaminobenzophenone, dichlorobenzophenone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tertiarybutylanthraquinone, 2-aminoanthraquinone, 2-methylthioxanthone, 2-ethylthioxanthone, Examples include 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, benzyl dimethyl ketal, acetophenone dimethyl ketal and the like.
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.

Moreover, various additives can be mix | blended with the ionizing radiation curable resin composition which comprises the surface protective layer 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. Moreover, as an organic type ultraviolet absorber, benzotriazole type, for example, 2- (2-hydroxy-5-methylphenyl) benzotriazole, 2- (2-hydroxy-3,5-di-tert-) is specifically mentioned. 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. Further, 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. Moreover, it can also be copolymerized and used to such an extent that the performance (scratch resistance and three-dimensional moldability) as a surface protective layer of the polymer of this invention is not impaired.

Examples of the wear resistance improver include 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.

Next, the configuration of the decorative sheet of the present invention will be described in detail with reference to FIG.
Drawing 1 is a mimetic diagram showing the section of one mode of decoration sheet 10 of the present invention at the time of using for insert molding. In the example shown in FIG. 1, a picture layer 12, a primer layer, and a surface protective layer 14 are sequentially laminated on a base material 11. Here, the surface protective layer 14 is formed by crosslinking and curing the above-mentioned ionizing radiation curable resin composition.

The substrate 11 is selected in consideration of suitability for vacuum forming, and typically a resin sheet made of a thermoplastic resin is used. As the thermoplastic resin, acrylonitrile-butadiene-styrene resin (hereinafter referred to as “ABS resin”), polyolefin resin such as acrylic resin, polypropylene, polyethylene, polycarbonate resin, vinyl chloride resin and the like are generally used. . Moreover, the base material 11 can be used as a single layer sheet of these resins or a multilayer sheet of the same kind or different kind of resin.
Although the thickness of a base material is selected according to a use, it is about 0.05-1.0 mm normally, and when considering the cost etc., about 0.1-0.7 mm is common.

These base materials can be subjected to physical or chemical surface treatment such as an oxidation method or an unevenness method on one side or both sides, if desired, in order to improve the adhesion with the layer provided thereon.
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 a sand blast method and a solvent treatment method. These surface treatments are appropriately selected depending on the type of substrate, but generally, a corona discharge treatment method is preferably used from the viewpoints of effects and operability.
In addition, the base material may be subjected to a treatment such as forming a primer layer, or a coating for adjusting color or a pattern from a design viewpoint may be formed in advance.

  The pattern layer 12 shown in FIG. 1 gives decorativeness to the decorative resin molded product, and is formed by printing various patterns using ink and a printing machine. Patterns include stone patterns that mimic the surface of rocks, such as wood grain patterns, marble patterns (for example, travertine marble patterns), fabric patterns that simulate cloth and cloth-like patterns, tiled patterns, brickwork patterns, etc. There are also patterns such as marquetry and patchwork that combine these. These patterns are formed by multicolor printing with the usual yellow, red, blue and black process colors, as well as by multicolor printing with special colors prepared by preparing the individual color plates constituting the pattern. Is done.

As the pattern ink used for the pattern layer 12, a binder and 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. 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 combination 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, metal 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.

  The decorative sheet 10 of the present invention may be provided with a concealing layer (not shown) between the base material 11 and the pattern layer 12 as desired. It is provided for the purpose of preventing the color of the pattern of the decorative sheet 10 from being affected by changes and variations in the color of the surface of the substrate 11. Usually, it is often formed with an opaque color, and a so-called solid printing layer having a thickness of about 1 to 20 μm is preferably used.

In the decorative sheet 10 of the present invention, a primer layer 13 is provided between the pattern layer 12 and the surface protective layer 14 as desired in order to make it difficult for fine cracks and whitening to occur in the stretched portion of the surface protective layer 14. it can. The primer composition constituting the primer layer 13 is (meth) acrylic resin, urethane resin, (meth) acrylic / urethane copolymer resin, vinyl chloride-vinyl acetate copolymer, polyester resin, butyral resin, chlorinated polypropylene, Chlorinated polyethylene or the like is used.
(Meth) acrylic resins include (meth) acrylic acid ester homopolymers, copolymers of two or more different (meth) acrylic acid ester monomers, or (meth) acrylic acid esters and other monomers. Polymers, and specifically, poly (meth) methyl acrylate, poly (meth) ethyl acrylate, poly (meth) acrylate propyl, poly (meth) acrylate butyl, methyl (meth) acrylate (Meth) butyl acrylate copolymer, (meth) ethyl acrylate / (meth) butyl acrylate copolymer, ethylene / (meth) methyl acrylate copolymer, styrene / methyl (meth) acrylate copolymer A (meth) acrylic resin composed of a homopolymer or a copolymer containing a (meth) acrylic acid ester such as is preferably used. Here, (meth) acryl means acryl or methacryl.

As the urethane resin, polyurethane having a polyol (polyhydric alcohol) as a main ingredient and an isocyanate as a crosslinking agent (curing agent) can be used. As the polyol, one having two or more hydroxyl groups in the molecule, for example, polyester polyol, polyethylene glycol, polypropylene glycol, acrylic polyol, polyether polyol and the like are used. Examples of the isocyanate include polyvalent isocyanate having two or more isocyanate groups in the molecule, aromatic isocyanate such as 4,4-diphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated diphenylmethane diisocyanate. Aliphatic (or alicyclic) isocyanates such as are used. It is also possible to mix urethane resin and butyral resin.
As the (meth) acryl / urethane copolymer resin, for example, an acrylic / urethane (polyester urethane) block copolymer resin is preferable. As the curing agent, the above-mentioned various isocyanates are used. The acrylic / urethane (polyester urethane) block copolymer resin may have an acrylic / urethane ratio (mass ratio) of preferably (9/1) to (1/9), more preferably (8/2) to (2). Since it can be adjusted within the range of / 8) and used for various decorative sheets, it is particularly preferable as a resin used in the primer composition.

  The decorative sheet 10 of the present invention is provided with an adhesive layer (not shown) on the back surface (surface opposite to the surface protective layer 14) of the decorative sheet 10 as desired in order to improve the adhesion with the injection resin. be able to. A thermoplastic resin or a curable resin is used for the adhesive layer depending on the injection resin. Examples of thermoplastic resins include acrylic resins, acrylic-modified polyolefin resins, chlorinated polyolefin resins, vinyl chloride-vinyl acetate copolymers, thermoplastic urethane resins, thermoplastic polyester resins, polyamide resins, rubber resins, and the like. Can be used alone or in combination of two or more. Examples of the thermosetting resin include urethane resin and epoxy resin.

The surface protective layer 14 can be formed by preparing a coating liquid containing the above-mentioned ionizing radiation curable resin composition, applying it, and crosslinking and curing it. In addition, the viscosity of a coating liquid should just be a viscosity which can form a non-hardened resin layer on the surface of a base material by the below-mentioned coating system, and there is no restriction | limiting in particular.
In the present invention, the prepared coating liquid is applied to the surface of the pattern layer 12 or the primer layer 13 so that the thickness after curing is 1-1000 μm, such as gravure coating, bar coating, roll coating, reverse roll coating. The coating is performed by a known method such as comma coating, preferably gravure coating, to form an uncured resin layer.

In the present invention, the uncured resin layer thus formed is irradiated with ionizing radiation such as an electron beam and ultraviolet rays to cure the uncured resin layer. 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 addition, in electron beam irradiation, since the transmission capability increases as the acceleration voltage is higher, when using a base material that deteriorates due to the electron beam as the base material 11, the transmission depth of the electron beam and the thickness of the resin layer are By selecting the accelerating voltage so as to be substantially equal, it is possible to suppress the irradiation of the extra electron beam to the base material 11 and to minimize the deterioration of the base material due to the excess 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).
Further, the electron beam source is not particularly limited. For example, various electron beam accelerators such as a cockroft Walton type, a bandegraft type, a resonant transformer type, an insulated core transformer type, a linear type, a dynamitron type, and a high frequency type. 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, high hardness and scratch resistance, so-called hard coat function, anti-fogging coating function, anti-fouling coating. 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.

In this invention, it is preferable that the thickness after hardening of the surface protective layer 14 is 1-1000 micrometers. If the thickness of the surface protective layer 14 after curing is 1 μm or more, sufficient physical properties as a protective layer such as scratch resistance and weather resistance can be obtained. On the other hand, when the thickness of the surface protective layer 14 after curing is 1000 μm or less, it is easy to uniformly apply ionizing radiation, and uniform curing is easily obtained, which is economically advantageous.
Further, by setting the thickness of the surface protective layer 14 after curing to more preferably 1 to 50 μm, and more preferably 1 to 30 μm, the three-dimensional formability is improved, and a complicated three-dimensional shape such as automobile interior use is obtained. High followability can be obtained. Therefore, in the decorative sheet of the present invention, even if a hard ionizing radiation curable resin is blended, excellent three-dimensional formability can be expressed, and the coating film is hardened without impairing the three-dimensional formability. Therefore, it is possible to provide excellent scratch resistance that is preferable in terms of processing and practical use.
Since the decorative sheet of the present invention can provide a sufficiently high three-dimensional formability even if the surface protective layer 14 is made thicker than the conventional one, a particularly high film thickness is required for the surface protective layer. It is also useful as a decorative sheet for a member such as a vehicle exterior part.

The pattern layer 12 is formed by a normal printing method such as gravure printing. The concealing layer is formed by a normal printing method such as gravure printing or a normal coating method such as gravure coating, gravure reverse coating, gravure offset coating, spinner coating, roll coating, reverse roll coating.
Primer layer 13 and adhesive layer are gravure coat, gravure reverse coat, gravure offset coat, spinner coat, roll coat, reverse roll coat, kiss coat, wheeler coat, dip coat, silk screen solid coat, wire bar coat, flow coat, comma It is formed by a usual coating method such as a coat, a flow coat, a brush coating, a spray coating, or a transfer coating method. The transfer coating method is a method in which a primer layer 13 or an adhesive layer is once formed on a thin sheet (film substrate), and then the target layer surface in the decorative sheet 10 is coated.

The thickness of the pattern layer 12 is appropriately selected depending on the pattern. The thickness of the masking layer is about 1 to 20 μm.
The thickness of the primer layer 13 is preferably about 0.1 to 10 μm. When it is 0.1 μm or more, the effect of preventing the surface protective layer from cracking, breaking, whitening, etc. can be sufficiently exerted. On the other hand, if the thickness of the primer layer is 10 μm or less, it is preferable that the three-dimensional formability does not fluctuate since the drying and curing of the coating film is stable when the primer layer is applied. From the above points, the thickness of the primer layer is more preferably 1 to 10 μm. Similarly, the thickness of the adhesive layer is preferably about 0.1 to 10 μm.

The decorative sheet of the present invention can be used for various injection molding methods such as insert molding method, injection molding simultaneous decoration method, blow molding method, gas injection molding method, etc. Preferably used.
In the insert molding method, in the vacuum forming process, the decorative sheet of the present invention is vacuum formed into a surface shape of the molded product in advance (off-line pre-molding) with a vacuum forming die, and then the excess portion is trimmed as necessary to form a molded sheet. Get. This molded sheet is inserted into an injection mold, the injection mold is clamped, the resin in a fluid state is injected into the mold and solidified, and the decorative sheet is integrated on the outer surface of the resin molding simultaneously with the injection molding. To produce decorative resin molded products.

  As the injection resin, a resin corresponding to the application is used, and thermoplastic resins such as polyolefin resins such as polyethylene and polypropylene, ABS resins, styrene resins, polycarbonate resins, acrylic resins, and vinyl chloride resins are typical. In addition, thermosetting resins such as urethane resins and epoxy resins can be used depending on the application.

Next, in the simultaneous injection molding decoration method, the decorative sheet of the present invention is placed in a female mold that is also used as a vacuum forming mold provided with a suction hole for injection molding, and pre-molding (in-line pre-molding) with this female mold ), The injection mold is clamped, the resin in a fluid state is injected into the mold, solidified, and the decorative sheet is integrated with the outer surface of the resin molding simultaneously with the injection molding, Manufactures decorative resin molded products.
In the injection molding simultaneous decorating method, the decorative sheet receives heat pressure from the injection resin, and therefore, if the decorative sheet is close to a flat plate and the aperture of the decorative sheet is small, the decorative sheet may or may not be preheated. .
In addition, as injection resin used here, the thing similar to what was demonstrated by the insert molding method can be used.

  The decorative resin molded body produced as described above has good three-dimensional moldability without cracking in the surface protective layer during the molding process, and the surface has high scratch resistance. In addition, the solvent resistance and chemical resistance are high. Furthermore, in the production method of the present invention, the surface protective layer is completely cured at the production stage of the decorative sheet, and therefore a step of crosslinking and curing the surface protective layer after producing the decorative resin molded body is unnecessary.

EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by this example.
Evaluation method (1) Three-dimensional formability (vacuum forming)
About the decorative sheet obtained by each Example and the comparative example, it vacuum-formed by the method shown below, and evaluated by the external appearance after shaping | molding. The evaluation criteria are as follows.
A: No coating film cracking or whitening was observed on the surface protective layer, and the shape of the mold was followed well.
○: Although a fine coating crack or whitening was observed in a part of the three-dimensional shape portion or the maximum stretched portion, there was no practical problem.
Δ: Slight coating cracking or whitening occurred in a part of the three-dimensional shape portion or the maximum stretched portion.
X: The coating film cracking and whitening were observed in the surface protective layer without following the shape of the mold.
<Vacuum forming>
The decorative sheet is heated to 160 ° C. with an infrared heater and softened. Next, vacuum forming is performed using a vacuum forming die (maximum draw ratio: 150%) to form the internal shape of the die. After the sheet is cooled, the decorative sheet is released from the mold.

(2) Scratch resistance The appearance of a test piece after reciprocating five times with a load of 1.5 kgf was evaluated using # 0000 steel wool. The evaluation criteria are as follows.
A: There was no scratch.
○: Although fine scratches were observed on the surface, the coating film was not scraped or whitened.
Δ: Minor scratches on the surface.
X: There was a remarkable scratch on the surface.

(3) Measurement of molecular weight A high-speed GPC apparatus manufactured by Tosoh Corporation was used. The column used was “TSKgel αM” manufactured by Tosoh Corporation, the solvent was N-methyl-2-pyrrolidinone (NMP), and the measurement was performed at a column temperature of 40 ° C. and a flow rate of 0.5 cc / min. . In addition, the weight average molecular weight in this invention performed polystyrene conversion.

Examples 1-7 and Comparative Examples 1-4
An ABS resin film (flexural modulus: 2000 MPa, thickness: 400 μm) was used as a substrate, and a woodgrain pattern layer was formed on the surface of the film by gravure printing using an acrylic resin composition. Next, a primer layer made of an acrylic resin (acrylic ester homopolymer) was applied to the surface of the pattern layer by gravure coating. The thickness of the primer layer was 3 μm.
Next, an electron beam curable resin composition having the composition shown in Table 1 is applied to the surface of the primer layer by gravure coating so that the thickness (μm) after curing of the resin composition becomes the value shown in Table 1. Coated. The uncured resin layer was irradiated with an electron beam having an acceleration voltage of 165 kV and an irradiation dose of 50 kGy (5 Mrad) to cure the electron beam curable resin composition, thereby obtaining 11 types of decorative sheets.
The decorative sheet was evaluated by the above method. The evaluation results are shown in Table 1.

[note]
Electron beam curable resin A; bifunctional polycarbonate acrylate, weight average molecular weight: 10,000
Electron beam curable resin B; hexafunctional polycarbonate acrylate, weight average molecular weight: 6,000
Electron beam curable resin C; hexafunctional urethane acrylate oligomer, weight average molecular weight: 6,000
Electron beam curable resin D; hexafunctional urethane acrylate oligomer, weight average molecular weight: 10,000

  The decorative sheet of the present invention has a rapid temperature drop, a rapid stretching speed, and a high degree of stretching from a heating temperature of about 160 ° C. to a temperature at the time of contact with the mold in a normal insert molding method and injection molding simultaneous decoration method. Even under these conditions, cracks and cracks did not occur, and the three-dimensional formability was good. Furthermore, it was confirmed that the surface of the manufactured decorative resin molded product has high scratch resistance.

  The decorative sheet of the present invention is used for various decorative resin molded products, for example, interior materials or exterior materials of vehicles such as automobiles, construction members such as baseboards, and rims, joinery such as window frames and door frames, and walls. It is suitably used for decorative resin molded products for uses such as interior materials for buildings such as floors and ceilings, casings and containers of household electrical appliances such as television receivers and air conditioners.

10. Decorative sheet Base material 12. Pattern layer 13. Primer layer 14. Surface protective layer

Claims (4)

  A decorative sheet having at least a surface protective layer on a substrate, wherein the surface protective layer contains at least a polycarbonate (meth) acrylate and a polyfunctional (meth) acrylate, and the polycarbonate (meth) acrylate and the polyvalent A decoration characterized by comprising a cured product of an ionizing radiation curable resin composition in which the mass ratio of the functional (meth) acrylate is polycarbonate (meth) acrylate: polyfunctional (meth) acrylate = 98: 2 to 70:30 Sheet.   The said polyfunctional (meth) acrylate is trifunctional or more, The decorating sheet of Claim 1 characterized by the above-mentioned.   The decorative sheet according to claim 1 or 2, wherein the polycarbonate (meth) acrylate has a weight average molecular weight of more than 2,000.   The decorative resin molded product which uses the decorating sheet in any one of Claims 1-3.

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