JP5663927B2 - Decorative sheet, decorative resin molded product using the same, and method for producing the same - Google Patents

Description

  The present invention relates to a decorative sheet having a primer layer formed using a specific primer composition, a decorative resin molded product using the decorative sheet, and a method for producing the same.

  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.

  In addition, in a transfer foil to be painted on the surface of a plastic molded product, a method using a resin containing acrylic polyol or isocyanate as a release varnish is known (for example, see Patent Document 5). There is no teaching or suggestion about using it as a 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 JP-A-5-8597

In order to solve the above problems, a method of reducing the crosslink density of the surface protective layer and improving the formability of the decorative sheet is also conceivable, but physical properties such as wear resistance and scratch resistance of the surface protective layer are impaired. In addition, there is a possibility that a chemical or the like attached to the surface easily passes through the surface protective layer, and a problem such as swelling of other layers formed under the surface protective layer may occur.
This invention makes it a subject to provide the decorating sheet which can make chemical-resistance and three-dimensional moldability compatible in such a condition, the decorating resin molded product using the same, and its manufacturing method. .

  As a result of intensive studies to solve the above problems, the present inventor can solve the above problems by forming a primer layer of a decorative sheet using a primer composition containing a specific component. I found out. The present invention has been completed based on such findings.

That is, the present invention
1. A decorative sheet having at least a primer layer and a surface protective layer on a substrate, the surface protective layer comprising a cured product of an ionizing radiation curable resin composition , wherein the ionizing radiation curable resin composition is at least It contains polycarbonate (meth) acrylate or acrylic silicone (meth) acrylate and polyfunctional (meth) acrylate , and the primer layer is formed using a primer composition containing at least a polyol and an isocyanate. Decorative sheet,
2 . The decorative sheet according to the above 1, wherein the ionizing radiation curable resin composition contains at least a polycarbonate (meth) acrylate and a polyfunctional (meth) acrylate,
3 . The decorative sheet according to 1 or 2 above, wherein a mass ratio of the polycarbonate (meth) acrylate and the polyfunctional (meth) acrylate is 98: 2 to 70:30,
4 . The decorative sheet according to any one of 1 to 3 above, wherein the polyfunctional (meth) acrylate is trifunctional or higher,
5 . The decorative sheet according to any one of 1 to 4 above, wherein the polycarbonate (meth) acrylate has a weight average molecular weight of 2,000 to 10,000,
6 . The decorative sheet according to any one of 1 to 5 , wherein the polyol is an acrylic polyol,
7 . The decorative sheet according to any one of 1 to 6 , wherein the primer composition further contains a non-crosslinked urethane resin,
8 . The decorative sheet according to 7 above, wherein a mass ratio of the polyol and the non-crosslinked urethane resin in the primer composition is 99: 1 to 50:50,
9 . The decorative sheet according to 7 or 8 above, wherein the glass transition point of the non-crosslinked urethane resin is 100 ° C or lower,
10 . The decorative sheet according to any one of 1 to 9 above, wherein an equivalent ratio of an isocyanate group of the isocyanate to a hydroxyl group of the polyol is 0.5 to 2.0.
11 . A decorative resin molded product using the decorative sheet according to any one of 1 to 10 above, and
12 . A step of forming a primer layer on a substrate, a step of laminating an ionizing radiation curable resin composition on the primer layer, and a step of forming a surface protective layer by crosslinking and curing the ionizing radiation curable resin composition The manufacturing method of the decorating sheet in any one of said 1-10 characterized by including these,
Is to provide.

  The decorative sheet of the present invention has excellent chemical resistance and good three-dimensional formability by a combination of a specific surface protective layer and a primer layer, in addition to the surface protective layer having excellent scratch resistance. At the same time, both the insert molding method and the injection molding simultaneous decoration method do not cause cracks in the surface protective layer, and have a high chemical resistance and a decorative resin molded product that is easy to three-dimensionally mold. Can be obtained.

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 primer layer and a surface protective layer on a substrate, and the surface protective layer is a cured product of an ionizing radiation curable resin composition, and The primer layer is formed using a primer composition containing at least a polyol and an isocyanate.
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.

First, the structure of the decorating sheet of this invention is demonstrated in detail using 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 13, 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.

[Primer layer]
The decorative sheet 10 of the present invention is less likely to cause fine cracking and whitening in the stretched portion of the surface protective layer 14 and imparts three-dimensional formability, and also imparts chemical resistance of the decorative sheet 10. The primer layer 13 is provided between the substrate 11 and the surface protective layer 14. As a primer composition which comprises the primer layer 13, what contains a polyol and isocyanate at least is used.

(Polyol)
As the polyol, those having two or more hydroxyl groups in the molecule, for example, acrylic polyol, polyester polyol, polyether polyol, polycarbonate polyol, polycaprolactone polyol, polyethylene glycol, polypropylene glycol, etc. are used. From this viewpoint, an acrylic polyol is preferred.
As the polyol, those having a glass transition point of 180 ° C. or lower are preferable, and those having −50 to 150 ° C. are more preferable.

The acrylic polyol can be synthesized by copolymerizing an acrylic monomer and a hydroxyl group-containing (meth) acrylic monomer.
Examples of the hydroxyl group-containing (meth) acrylic monomer include hydroxyalkyl (meth) acrylates such as 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 4-hydroxybutyl acrylate, and 1,4-cyclohexanediol monoacrylate. The alkyl group of the hydroxyalkyl (meth) acrylate may be linear, branched or cyclic, preferably has 1 to 10 carbon atoms, and more preferably has 1 to 6 carbon atoms.
Examples of the acrylic monomer include (meth) acrylic acid, methyl (meth) acrylate, ethyl (meth) acrylate, (meth) acrylic acid-n-propyl, isopropyl (meth) acrylate, (meth) acrylic acid- Examples include (meth) acrylic acid alkyl esters such as n-butyl and isobutyl (meth) acrylate, and these can be used alone or in combination of two or more.

(Isocyanate)
The isocyanate may be a polyvalent isocyanate having two or more isocyanate groups in the molecule, and is an aromatic isocyanate such as xylylene diisocyanate or 4,4-diphenylmethane diisocyanate, or hexamethylene diisocyanate, isophorone diisocyanate, hydrogenated. An aliphatic (or alicyclic) isocyanate such as tolylene diisocyanate or hydrogenated diphenylmethane diisocyanate is used, and from the viewpoint of suppressing yellowing of the primer layer 13, it is preferable to use a non-yellowing one such as hexamethylene diisocyanate. .

  The polyol and the isocyanate are preferably used at a blending ratio such that the equivalent ratio of the isocyanate group of the isocyanate to the hydroxyl group of the polyol is 0.5 to 2.0, and is used at a blending ratio of 0.8 to 1.2. More preferably.

The primer composition used for forming the primer layer 13 further includes (meth) acrylic resin, urethane resin, (meth) acrylic / urethane copolymer resin, vinyl chloride-vinyl acetate copolymer, polyester resin, butyral resin. Chlorinated polypropylene, chlorinated polyethylene, and the like may be contained, but inclusion of a urethane resin is preferable because it is excellent in compatibility with acrylic polyol, flexibility, heat resistance, and the like.
As the urethane resin, select a non-cross-linked type, that is, a resin having a linear molecular structure instead of a three-dimensionally cross-linked three-dimensional molecular structure. It is preferable. As such a non-crosslinked urethane resin, a polyol component such as polyester polyol, polyether polyol, polycarbonate polyol, polycaprolactone polyol, polyethylene glycol, polypropylene glycol, etc. is used as a main ingredient, and is reacted with the above isocyanate. A cross-linked urethane resin can be used, and is synthesized from a combination of a polyester polyol and a non-yellowing isocyanate such as hexamethylene diisocyanate from the viewpoints of moldability, heat resistance, weather resistance, adhesion to the surface protective layer 14, and the like. Those are particularly preferred. Usually, the number of hydroxyl groups in one molecule of polyol and the number of isocyanate groups in one molecule of isocyanate are two on average.
As the urethane resin, those having a glass transition point of 100 ° C. or lower are preferable, and those having a temperature of 40 to 100 ° C. are more preferable. When the glass transition point of the urethane resin is 100 ° C. or less, the primer layer is excellent in flexibility at room temperature. It does not decrease or the primer layer does not dissolve.
The ratio of the polyol and the urethane resin in the primer composition is preferably 99: 1 to 50:50 and more preferably 90:10 to 60:40 in terms of mass ratio.

  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.

  Moreover, it is preferable that the thickness of the primer layer 13 is about 0.5-5.0 micrometers. When the thickness is 0.5 μm or more, a portion where the primer layer is not formed as a complete film does not occur, so that 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 5.0 μm or less, when the primer layer 13 is applied, the solvent does not remain in the layer, so that the drying and curing of the coating film is stable and the moldability fluctuates. This is preferable because blocking can be suppressed. From the above points, the thickness of the primer layer 13 is more preferably 0.5 to 3.0 μm.

[Surface protective layer]
In the decorative sheet 10 of the present invention, the ionizing radiation curable resin used in 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, ultraviolet rays. Or the resin which bridge | crosslinks and hardens | cures by irradiating an electron beam etc. Specifically, it can be appropriately selected from polymerizable oligomers and polymerizable monomers conventionally used as ionizing radiation curable resins.

  As the polymerizable oligomer, an oligomer having a radical polymerizable unsaturated group in the molecule, for example, acrylic (meth) acrylate, epoxy (meth) acrylate, urethane (meth) acrylate, polyester (meth) acrylate, poly Preferred examples include ether (meth) acrylate-based, polycarbonate (meth) acrylate-based, and acrylic silicone (meth) acrylate-based oligomers. Among these oligomers, polyfunctional polymerizable oligomers are preferable, and the number of functional groups is preferably 2 to 16, more preferably 2 to 8, and still more preferably 2 to 6.

  Furthermore, other polymerizable oligomers include polybutadiene (meth) acrylate oligomers with high hydrophobicity that have (meth) acrylate groups in the side chain of polybutadiene oligomers, and silicone (meth) acrylate oligomers that have 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 type epoxy resin, bisphenol type epoxy resin, aliphatic vinyl ether, aromatic vinyl ether, etc. There are oligomers having a cationic polymerizable functional group. These polymerizable oligomers may be used individually by 1 type, and may be used in combination of 2 or more type.

  As the polymerizable monomer, a (meth) acrylate monomer having a radically polymerizable unsaturated group in the molecule is suitable, and in particular, a polyfunctionality having two or more ethylenically unsaturated bonds in the molecule ( (Meth) acrylate is preferred, and one kind may be used alone, or two or more kinds may be used in combination. As a functional group number, 2-8 are preferable, 2-6 are more preferable, and 3-4 are more preferable.

  In the present invention, together with the polyfunctional (meth) acrylate, for the purpose of adjusting the viscosity, methyl (meth) acrylate, cyclohexyl (meth) acrylate, stearyl (meth) acrylate, isobornyl (meth) acrylate, etc. A monofunctional (meth) acrylate can be appropriately used in combination as long as the object of the present invention is not impaired. A monofunctional (meth) acrylate may be used individually by 1 type, and may be used in combination of 2 or more type.

  The ionizing radiation curable resin composition in the present invention contains at least polycarbonate (meth) acrylate or acrylic silicone (meth) acrylate and polyfunctional (meth) acrylate among the above various ionizing radiation curable resins. Since it satisfies both excellent chemical resistance and scratch resistance and good three-dimensional formability at the same time, there is no cracks in the surface protective layer, and it is easy to form in three dimensions and has chemical resistance. It is preferable in that a high decorative sheet can be obtained.

When using an ionizing radiation curable resin composition containing polycarbonate (meth) acrylate and polyfunctional (meth) acrylate, the mass ratio of polycarbonate (meth) acrylate and polyfunctional (meth) acrylate is preferably 98: It is 2-70: 30, More preferably, it is 95: 5-80: 20. 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 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.
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. The polycarbonate (meth) acrylate preferably has two or more functions, more preferably 2 to 5 functions, from the viewpoint of crosslinking and curing. If it is bifunctional or higher, the crosslinking density will be sufficient, so that the surface protective layer 14 after curing will be less likely to be scratched, and if it is pentafunctional or lower, the crosslinking density will not be too high. Even when it is subjected to three-dimensional molding, it can sufficiently follow the shape.
The polycarbonate (meth) acrylate has a weight average molecular weight measured by GPC analysis and converted to standard polystyrene of preferably 500 or more, more preferably 1,000 or more, and 2,000 or more. More preferably, it is particularly preferably 5,000 or more. 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, more preferably 50,000 or less, and even more preferably 20,000 or less from the viewpoint of controlling the viscosity not to be too high. It is preferably 10,000 or less. From the viewpoint of achieving both scratch resistance and three-dimensional formability, 1,000 to 20,000 are preferable, and 2,000 to 10,000 are more preferable.

When using an ionizing radiation curable resin composition containing acrylic silicone (meth) acrylate and polyfunctional (meth) acrylate, the mass ratio of acrylic silicone (meth) acrylate and polyfunctional (meth) acrylate is preferably It is 50: 50-95: 5, More preferably, it is 80: 20-95: 5.
The acrylic silicone (meth) acrylate used in the present invention is not particularly limited, and a part of the acrylic resin structure is substituted with a siloxane bond (Si—O) in one molecule, and the acrylic resin is a functional group. Any of those having two or more (meth) acryloyloxy groups (acryloyloxy group or methacryloyloxy group) at the side chain and / or main chain terminal of the above.
The acrylic silicone (meth) acrylate has a weight average molecular weight measured by GPC analysis and converted to standard polystyrene of preferably 1,000 or more, and more preferably 2,000 or more. The upper limit of the weight average molecular weight of the acrylic silicone (meth) acrylate is not particularly limited, but is preferably 150,000 or less and more preferably 100,000 or less from the viewpoint of controlling the viscosity not to be too high. From the viewpoint of establishing three-dimensional formability, chemical resistance, and scratch resistance, it is particularly preferably 2,000 to 100,000.

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

  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. 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. 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 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, when using ultraviolet curable resin as ionizing radiation curable resin, it is desirable to add about 0.1-5 mass parts of photopolymerization initiators with respect to 100 mass parts of ultraviolet curable resin. The initiator for photopolymerization can be appropriately selected from those conventionally used. For example, benzoin ethers such as benzoin methyl ether, benzoin isopropyl ether, and benzoin isobutyl ether; acetophenone, 2,2′-diethoxyacetophenone , Acetophenones such as p-dimethylacetophenone and p-tert-butylacetophenone; benzophenones such as benzophenone, 2-chlorobenzophenone and p, p'-bisdimethylaminobenzophenone; 2-methyl-1- [4- (methylthio) [Alpha] -aminoalkylphenones such as phenyl] -2-monforinopropanone-1,2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1; benzyldimethyl ketal, thioxa Sulfur compounds such as Nson, 2-chlorothioxanthone and 2,4-diethylthioxanthone are preferred.
As the photosensitizer, for example, p-dimethylbenzoate, tertiary amines, thiol sensitizers, and the like can be used.

  In the present invention, it is preferable to use an electron beam curable resin as the ionizing radiation curable resin. This is because the electron beam curable resin 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 said ionizing radiation curable resin composition, other resin can be contained in the range with the effect of this invention. For example, when it is desired to impart flexibility to the decorative sheet 10 obtained by the production method of the present invention, a thermoplastic resin can be added. On the other hand, when resistance to a solvent is required, it is preferable not to contain a thermoplastic resin.
Thermoplastic resins include (meth) acrylic resins such as (meth) acrylic acid esters, polyvinyl acetals (butyral resin) such as polyvinyl butyral, polyester resins such as polyethylene terephthalate and polybutylene terephthalate, vinyl chloride resins, urethane resins, Polyolefins such as polyethylene and polypropylene, styrene resins such as polystyrene and α-methylstyrene, acetal resins such as polyamide, polycarbonate and polyoxymethylene, fluororesins such as ethylene-tetrafluoroethylene copolymer, polyimide, polylactic acid, A polyvinyl acetal resin, liquid crystalline polyester resin, etc. are mentioned, These may be used individually by 1 type or in combination of 2 or more types. When combining 2 or more types, the copolymer of the monomer which comprises these resin may be sufficient, and each resin may be mixed and used.

Among the above thermoplastic resins, those having a (meth) acrylic resin as a main component are preferred in the present invention, and in particular, those obtained by polymerizing a monomer containing at least a (meth) acrylic acid ester as a monomer component. preferable.
More specifically, a homopolymer of (meth) acrylic acid ester, a copolymer of two or more different (meth) acrylic acid ester monomers, or a copolymer of (meth) acrylic acid ester and other monomers Is preferred.

As said thermoplastic resin, the range whose weight average molecular weight is 90,000-120,000 is used, for example. When the weight average molecular weight is within this range, the formability after crosslinking and curing to form the surface protective layer, the surface wear resistance, and the scratch resistance can all be obtained at a high level.
Here, the weight average molecular weight is a value in terms of polystyrene measured by gel permeation chromatography (GPC). The solvent used here can be appropriately selected from those usually used, and examples thereof include tetrahydrofuran (THF) and N-methyl-2-pyrrolidinone (NMP).

  The polydispersity (weight average molecular weight Mw / number average molecular weight Mn) of the thermoplastic resin is preferably in the range of 1.1 to 3.0. If the polydispersity is within this range, it is possible to obtain a high level of moldability, surface abrasion resistance, and scratch resistance after crosslinking and curing to form a surface protective layer. From the above points, the polydispersity of the (meth) acrylic resin is preferably in the range of 1.5 to 2.5.

  The surface protective layer 14 thus formed has various functions by adding various additives, for example, a so-called hard coat function, antifogging function, antifouling function having high hardness and scratch resistance, An antiglare function, an antireflection function, an ultraviolet shielding function, an infrared shielding function, and the like can also be imparted.

  Examples of additives include a weather 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 antifoaming agent, Examples thereof include fillers, solvents, colorants, and wear resistance improvers.

  In the present invention, the thickness of the surface protective layer 14 after curing is preferably 1 to 20 μm. When the thickness of the surface protective layer 14 after curing is 1 μm or more, excellent design properties such as transparency and glossiness can be obtained, and further sufficient as a protective layer such as stain resistance, scratch resistance, and weather resistance. Physical properties can be obtained. On the other hand, if it is 20 μm or less, the thickness of the coating film can be easily controlled, and there is no cracking or whitening of the protective layer at the time of molding, and it can follow the desired shape, so that it is good even after three-dimensional molding. In addition, the solvent does not remain in the layer and does not cause poor curing. From this viewpoint, the thickness of the surface protective layer 14 after curing is preferably in the range of 2 to 20 μm, and more preferably in the range of 3 to 10 μm.

[Base material]
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.
Further, the base material may be preliminarily formed with a paint for adjusting the color or a pattern from a design viewpoint.

[Picture layer]
As shown in FIG. 1, the decorative sheet of the present invention may be provided with a pattern layer 12 that gives decorativeness to the decorative resin molded product, and by printing various patterns using ink and a printing machine. Can be formed. Patterns include stone patterns that simulate 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, 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 made of scaly foil pieces such as aluminum and brass, pearlescent pigments made 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. This is provided for the purpose of preventing the color of the surface of the base material 11 from affecting the pattern color of the decorative sheet 10 and is usually formed in an opaque color, and its thickness is A so-called solid print layer of about 1 to 20 μm is preferably used.

  Since the decorative sheet 10 of the present invention improves the adhesion to the injection resin, an adhesive layer (not shown) is provided on the back surface (the surface opposite to the surface protective layer 14) of the decorative sheet 10 as desired. Can be provided. 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.

[Method for producing decorative sheet]
The decorative sheet of the present invention includes, for example, a step of forming a primer layer 13 on the substrate 11, a step of laminating an ionizing radiation curable resin composition on the surface of the primer layer 13, and the ionizing radiation curable resin composition. And a step of forming a surface protective layer 14 by crosslinking and curing the product.
When forming the pattern layer 12, the pattern layer 12 can be formed on the substrate 11, and the primer layer 13 and the surface protective layer 14 can be sequentially stacked on the pattern layer 12.
Hereinafter, each step will be specifically described.

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.
In addition, the pattern layer 12 can be smoothed by applying a heat press treatment using a mirror plate after the formation or a roll press treatment using a mirror roll, and a primer layer formed thereon. 13 and the surface of the surface protective layer 14 can also be smoothed. By smoothing the surface of the surface protective layer 14, the smoothness and gloss of the decorative sheet surface and the smoothness and gloss of the decorative resin molded product after three-dimensional molding are remarkably different from each other. The problem that a feeling and the design feeling of a decorative resin molded product are greatly different is suppressed.
When the decorative sheet 10 whose both surfaces are smoothed is wound up in a roll shape, fine dust or the like is sandwiched between the decorative sheets 10, and the front and back surfaces of the decorative sheet 10 are in close contact with each other. In this case, the surface of the surface protective layer 14 may be scratched or wrinkled. This problem is caused by the back side of the base material 11 (the pattern layer 12 and the primer) when the heat press treatment and roll press treatment are performed. Suppression by roughening by using a satin board or a satin roll on the side where the layer 13 is not formed, or by providing a resin layer containing a binder resin and fine particles on the back side of the substrate 11 can do.

The primer layer 13 is a 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 coat, coat It is formed by a usual coating method such as sink coating, brush coating, spray coating, or transfer coating method. The transfer coating method is a method in which a coating film of the primer layer 13 is once formed on a release film, and then the target layer surface in the decorative sheet 10 is coated.
In the transfer coating method, the primer layer 13 having a smooth surface can be formed by selecting the release film having a smooth surface.

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.
The prepared coating solution is a known method such as gravure coating, bar coating, roll coating, reverse roll coating, comma coating, etc., on the surface of the primer layer 13 so that the thickness after curing is 1-1000 μm, Preferably, it is applied by gravure coating to form an uncured resin layer.

The uncured resin layer can be cured by irradiating the uncured resin layer thus formed 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 addition, in electron beam irradiation, since the transmission capability increases as the acceleration voltage is higher, when a base material that deteriorates due to an electron beam is used 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 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.

[Use of decorative sheet]
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 the external appearance after shaping | molding visually. The evaluation criteria are as follows.
◯: No cracking or whitening of the coating film was observed on the surface protective layer, and the shape of the mold was satisfactorily followed.
X: The coating film cracking and whitening were seen by the surface protective layer, without being able to follow the shape of a type | mold.
<Vacuum forming>
The decorative sheet is heated to 170 ° C. with an infrared heater and softened. Next, vacuum forming is performed using a vacuum forming die (maximum draw ratio: 100%) to form the internal shape of the die. After the sheet is cooled, the decorative sheet is released from the mold.

(2) Chemical resistance Five layers of gauze were placed on the surface of the decorative sheet obtained in each example and comparative example, 0.5 ml of ethanol was dropped and covered with a watch glass. After being allowed to stand at room temperature (25 ° C.) for 30 minutes, the watch glass and the gauze were removed, the state of the decorative sheet surface was visually confirmed, and the following criteria were evaluated.
○: Traces could not be confirmed on the surface.
X: Abnormalities such as whitening, swelling, and peeling were confirmed 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 1-6 and Comparative Examples 1-2
A sheet made of ABS resin (thickness: 400 μm) was used as a substrate, and a woodgrain pattern layer was formed on the surface of the sheet by gravure printing using acrylic urethane copolymer resin ink. Next, the primer composition described in Table 1 was applied to the surface of the pattern layer by gravure coating to form a primer layer. The thickness of the primer layer was 1 μm.
Next, an electron beam curable resin composition having the composition shown in Table 1 was applied to the surface of the primer layer by gravure reverse so that the cured thickness of the resin composition was 6 μm.
This 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 to obtain a decorative sheet.
The decorative sheet was evaluated by the above method. The evaluation results are shown in Table 1.

  Furthermore, the obtained decorative sheet was heated with an infrared heater until the temperature of the sheet reached 170 ° C., softened, and then vacuum-formed. The decorative sheet was released from the mold, and unnecessary parts were trimmed by pressing the die-cut mold with hydraulic pressure. Using this trimmed decorative sheet, it is inserted into an injection mold, then clamped, ABS resin is injected into the mold, and the decorative sheet is laminated and integrated on the surface of the molded product. A resin molded product was obtained.

[note]
Electron beam curable resin A: Bifunctional polycarbonate acrylate (weight average molecular weight: 10,000)
Electron curable resin B: hexafunctional urethane acrylate oligomer (weight average molecular weight: 6,000)
Polyol A: Acrylic polyol (Glass transition point: 99 ° C)
Polyol B: Polyester polyol (Glass transition point: −40 ° C.)
Polyol C: Polycarbonate polyol (Glass transition point: -45 ° C)
Urethane resin A: Polyester non-crosslinked urethane resin (glass transition point: 60 ° C.)
Urethane resin B: Polyether-based non-crosslinked urethane resin (glass transition point: 140 ° C.)
Acrylic urethane copolymer: (number average molecular weight: 20,000, glass transition point: 50 ° C.)
Acrylic resin: (number average molecular weight: 8,000, glass transition point: 100 ° C.)
Isocyanate: Hexamethylene diisocyanate

  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 decorative sheet has high chemical 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 (12)

A decorative sheet having at least a primer layer and a surface protective layer on a substrate, the surface protective layer comprising a cured product of an ionizing radiation curable resin composition , wherein the ionizing radiation curable resin composition is at least It contains polycarbonate (meth) acrylate or acrylic silicone (meth) acrylate and polyfunctional (meth) acrylate , and the primer layer is formed using a primer composition containing at least a polyol and an isocyanate. A decorative sheet. The decorative sheet according to claim 1, wherein the ionizing radiation curable resin composition contains at least a polycarbonate (meth) acrylate and a polyfunctional (meth) acrylate. The decorative sheet according to claim 1 or 2 , wherein a mass ratio of the polycarbonate (meth) acrylate and the polyfunctional (meth) acrylate is 98: 2 to 70:30. The polyfunctional (meth) acrylate, decorative sheet according to any one of claims 1 to 3, characterized in that a trifunctional or more. The decorative sheet according to any one of claims 1 to 4 , wherein the polycarbonate (meth) acrylate has a weight average molecular weight of 2,000 to 10,000. The decorative sheet according to any one of claims 1 to 5 , wherein the polyol is an acrylic polyol. The decorative sheet according to any one of claims 1 to 6 , wherein the primer composition further contains a non-crosslinked urethane resin. The decorative sheet according to claim 7 , wherein a mass ratio of the polyol and the non-crosslinked urethane resin in the primer composition is 99: 1 to 50:50. The decorative sheet according to claim 7 or 8 , wherein a glass transition point of the non-crosslinked urethane resin is 100 ° C or lower. The decorative sheet according to any one of claims 1 to 9 , wherein an equivalent ratio of an isocyanate group of the isocyanate to a hydroxyl group of the polyol is 0.5 to 2.0. A decorative resin molded product using the decorative sheet according to any one of claims 1 to 10 . A step of forming a primer layer on a substrate, a step of laminating an ionizing radiation curable resin composition on the primer layer, and a step of forming a surface protective layer by crosslinking and curing the ionizing radiation curable resin composition The manufacturing method of the decorating sheet in any one of Claims 1-10 characterized by the above-mentioned.

Images