JP2007291380A - Resin composition and decorative sheet using the same resin composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resin composition forming a surface protecting layer having high abrasion and scuff resistances and good moldability without forming cracks, etc., as the surface protecting layer of a decorative sheet used for molding a decorative molded product, to provide the decorative sheet using the resin composition in the surface protecting layer, to provide a method for producing the decorative resin molded product using the decorative sheet and to provide the decorative resin molded product produced by the method for production. <P>SOLUTION: The resin composition for forming the surface protecting layer of the decorative sheet is a resin composition comprising an ionizing radiation curing resin and a polymer obtained by polymerizing an acrylic or a methacrylic ester containing at least methyl methacrylate as a monomer component. The weight-average molecular weight of the polymer measured by GPC (gel permeation chromatography) and converted into polystyrene is within the range of 90,000 to 120,000. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a resin composition for forming a surface protective layer of a decorative sheet, a decorative sheet having a surface protective layer obtained by crosslinking and curing the resin composition, and a method for producing a decorative resin molded product using the decorative sheet In addition, the present invention relates to a decorative resin molded product manufactured by the manufacturing method.

  A decorative molded product decorated by laminating a decorative sheet on the surface of the molded product is used in various applications such as vehicle interior parts. As a method for molding such a decorative molded product, the decorative sheet is molded into a three-dimensional shape in advance by a vacuum mold, the molded sheet is inserted into an injection mold, and a fluid resin is injected into the mold. The insert molding method (for example, refer to Patent Document 1) for integrating the resin and the molded sheet, and the decorative sheet inserted into the mold during the injection molding are integrated with the molten resin injected into the cavity. There is an injection molding simultaneous decorating method (see, for example, Patent Document 2 and Patent Document 3) that decorates the surface of the resin molded body.

  By the way, the decorative molded product is provided with a surface protective layer for the purpose of improving the wear resistance and scratch resistance of the surface. However, in the molding method of the decorative molded product described above, in the insert molding method, the decorative sheet is formed into a three-dimensional shape in advance by a vacuum mold, and in the injection molding simultaneous decorating method, the decorative sheet is pre-molded or molten resin. In the process of drawing and adhering along the inner peripheral surface of the cavity, the decorative sheet is made to conform to the mold shape by vacuum / pneumatic action, or by pulling by the pressure of molten resin, shear stress, etc. Since it is extended beyond the minimum necessary amount, there has been a problem that cracks occur in the surface protective layer of the curved surface portion of the molded product.

In order to improve the moldability of the surface protective layer, a thermosetting resin has been used as the surface protective layer (for example, see Patent Document 4). The thermosetting resin showed good results for moldability, and the surface protective layer was hardly cracked, but the surface wear resistance and scratch resistance of the decorative molded product were not satisfactory.
In addition, by using an ionizing radiation curable resin such as an ultraviolet curable resin as the surface protective layer and increasing the crosslink density of the resin that forms the surface protective layer of the decorative sheet, the surface wear resistance of the decorative molded product can be increased. Attempts were made to improve the scratch resistance, but there was a problem that cracks occurred in the curved surface of the molded product during molding.
Furthermore, although an ionizing radiation curable resin such as an ultraviolet curable resin is used as a surface protective layer, a method of making it a semi-cured state at the stage of a decorative sheet and completely curing it after decorative molding has been tried (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. In addition, since it is necessary to irradiate the three-dimensional molded product with ultraviolet rays, a separate facility for irradiating the three-dimensional molded product with ultraviolet rays is required.

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

  In view of the above problems, the present invention has high wear resistance and scratch resistance as a surface protective layer of a decorative sheet used for molding a decorative molded product, and has good moldability and cracks and the like. Composition capable of forming a non-surface protective layer, a decorative sheet using the resin composition as a surface protective layer, a method for manufacturing a decorative resin molded product using the decorative sheet, and a manufacturing method thereof An object is to provide a decorated resin molded product.

  As a result of intensive studies to achieve the above object, the present inventors have found that a resin composition containing an ionizing radiation curable resin and a specific thermoplastic methacrylic polymer can solve the above problems. I found it. The present invention has been completed based on such findings.

That is, the present invention
(1) A resin composition comprising a polymer obtained by polymerizing an ionizing radiation curable resin and a (meth) acrylic acid ester containing at least methyl methacrylate as a monomer component, the gel permeation chromatography of the polymer ( Resin composition for forming a surface protective layer of a decorative sheet having a polystyrene equivalent weight average molecular weight measured by GPC) in the range of 90,000 to 120,000,
(2) The resin composition according to (1), wherein the polydispersity of the polymer is in the range of 1.1 to 3.0,
(3) The polymer is a copolymer of methyl methacrylate and methyl acrylate, and the structural unit derived from methyl acrylate is 0.1 mol with respect to 100 mol of the structural unit derived from methyl methacrylate in the polymer. The resin composition according to the above (1) or (2), which is in the range of 10 mol to 10 mol,
(4) The resin composition according to (1) or (2), wherein the polymer is a homopolymer of methyl methacrylate,
(5) The resin composition according to any one of (1) to (4), wherein the mass ratio of the ionizing radiation curable resin and the polymer is 75:25 to 25:75,
(6) The resin composition according to any one of (1) to (5), wherein the ionizing radiation curable resin is an electron beam curable resin,
(7) Any of (1) to (6) above, wherein the storage elastic modulus at 140 ° C. measured under the following measurement conditions is in the range of 7.7 × 10 ^{5 to} 1.2 × 10 ⁸ . According to JIS K7244-1 and 7244-4, according to JIS K7244-1 and 7244-4, a 10 mm wide sheet having a width of 10 mm and a thickness of 15 μm is formed to a distance between clamps of 10 mm. Measured at a start temperature of 30 ° C., an end temperature of 180 ° C., a temperature increase rate of 5 ° C./min, and a measurement frequency of 1 Hz.
(8) A decorative sheet having at least a surface protective layer on a substrate, wherein the surface protective layer is a crosslinked and cured resin composition described in any of (1) to (7) above. Sheet,
(9) The decorative sheet according to (8), wherein the tensile elongation in a tensile test measured under the following measurement conditions based on JIS K 7127 is 50% or more,
Measurement conditions: Using a test piece with a width of 25 mm and a length of 120 mm, tensile elongation until a crack occurs in the surface protective layer under the conditions of a tensile speed of 1000 mm / min, a distance between chucks of 80 mm, a distance between marked lines of 50 mm, and a temperature of 160 ° C. Measure the degree,
(10) A vacuum forming step in which the decorative sheet according to (8) or (9) is formed into a three-dimensional shape in advance using a vacuum forming die, a step of trimming excess portions to obtain a formed sheet, and injecting the formed sheet A method for producing a decorative resin molded article having a step of inserting into a mold, closing the injection mold, injecting a resin in a fluid state into the mold, and integrating the resin and the molded sheet;
(11) The decorative sheet according to the above (8) or (9) is installed so that the base material of the decorative sheet faces the molding surface of the movable mold having a molding surface with a predetermined shape. Thereafter, the decorative sheet is heated and softened, and vacuum suction is performed from the movable mold side, and the softened decorative sheet is brought into close contact with the molding surface of the movable mold, thereby preliminarily decorating the decorative sheet. After the molding process, the movable mold having the decorative sheet closely adhered along the molding surface and the fixed mold are clamped, and the resin molding material in a fluid state is injected into the cavity formed by both molds. By filling and solidifying, the injection molding process for stacking and integrating the formed resin molded body and the decorative sheet, and the movable mold is separated from the fixed mold, and the entire decorative sheet is laminated. Decorative resin composition that sequentially performs the process of taking out the molded resin product Method for producing goods, and (12) above (10) or (11) decorated resin molded article produced by the method described in,
Is to provide.

  The decorative sheet having a surface protective layer obtained by crosslinking and curing the resin composition of the present invention has high wear resistance and scratch resistance, has good moldability, and is an insert molding method or an injection molding simultaneous decoration method. In this case, cracks or the like do not enter the surface protective layer.

The resin composition for forming a surface protective layer of the present invention comprises an ionizing radiation curable resin and a polymer obtained by polymerizing (meth) acrylic acid ester containing at least methyl methacrylate as a monomer component, and the gel permeation of the polymer. The polystyrene-reduced weight average molecular weight measured by chromatography chromatography (GPC) is in the range of 90,000 to 120,000.
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. Specifically, it can be appropriately selected from polymerizable monomers, polymerizable oligomers, or prepolymers conventionally used as ionizing radiation curable resins.

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

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

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

  Furthermore, other polymerizable oligomers include polybutadiene (meth) acrylate oligomers with high hydrophobicity 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 novolac type epoxy resin, bisphenol type epoxy resin, aliphatic vinyl ether, aromatic vinyl ether, etc. There are oligomers having a cationic polymerizable functional group.

When an ultraviolet curable resin is used as the ionizing radiation curable resin, it is desirable to add about 0.1 to 5 parts by mass of the photopolymerization initiator with respect to 100 parts by mass of the resin. The initiator for photopolymerization can be appropriately selected from those conventionally used and is not particularly limited. For example, for a polymerizable monomer or polymerizable oligomer having a radically polymerizable unsaturated group in the molecule. Benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin-n-butyl ether, benzoin isobutyl ether, acetophenone, dimethylaminoacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2 -Phenylacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholino-propane-1 - 4- (2-hydroxyethoxy) phenyl-2 (hydroxy-2-propyl) ketone, benzophenone, p-phenylbenzophenone, 4,4′-diethylaminobenzophenone, dichlorobenzophenone, 2-methylanthraquinone, 2-ethylanthraquinone, 2 -Tertiary butylanthraquinone, 2-aminoanthraquinone, 2-methylthioxanthone, 2-ethylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, benzyldimethyl ketal, acetophenone dimethyl ketal It is done.
Examples of the polymerizable oligomer having a cationic polymerizable functional group in the molecule include aromatic sulfonium salts, aromatic diazonium salts, aromatic iodonium salts, metallocene compounds, and benzoin sulfonic acid esters.
Moreover, as a photosensitizer, p-dimethylbenzoic acid ester, tertiary amines, a thiol type sensitizer, etc. can be used, for example.

  In the present invention, it is preferable to use an electron beam curable resin 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.

  The resin composition of the present invention comprises a polymer obtained by polymerizing (meth) acrylic acid ester containing at least methyl methacrylate as a monomer component (hereinafter referred to as “the polymer of the present invention”). The polymer of this invention should just contain methyl methacrylate as a monomer component, and contains the homopolymer of methyl methacrylate and the copolymer of methyl methacrylate and other (meth) acrylic acid ester. In addition, these copolymers may be random copolymers or block copolymers.

Regarding the copolymer of methyl methacrylate and other (meth) acrylic acid esters, other (meth) acrylic acid esters include methyl acrylate, ethyl acrylate, propyl acrylate, ethyl methacrylate, propyl methacrylate. Normal butyl methacrylate, isobutyl methacrylate, secondary butyl methacrylate, tertiary butyl methacrylate, isobornyl methacrylate, 2-methyl-2-adamantyl methacrylate, 2-ethyl-2-adamantyl methacrylate, etc. In particular, methyl acrylate is preferred.
In the copolymer of methyl methacrylate and other (meth) acrylic acid ester, the structural unit derived from other (meth) acrylic acid ester monomer is 0.000 per 100 mol of the structural unit derived from methyl methacrylate. A range of 1 to 10 mol is preferable. When the structural unit derived from other (meth) acrylic acid ester monomer is within the above range with respect to 100 mol of the structural unit derived from methyl methacrylate, the abrasion resistance of the surface after forming the surface protective layer, Scratch resistance and solvent resistance are improved. From the above points, the structural unit derived from other (meth) acrylic acid ester monomer is more preferably in the range of 1 to 9 moles with respect to 100 moles of the structural unit derived from methyl methacrylate.

Next, it is essential that the polymer of the present invention has a weight average molecular weight in the range of 90,000 to 120,000. 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. From the above points, the weight average molecular weight of the thermoplastic resin is preferably in the range of 90,000 to 120,000.
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).
Further, the polydispersity (weight average molecular weight Mw / number average molecular weight Mn) of the polymer of the present invention 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 polymer of the present invention is preferably in the range of 1.5 to 2.5.

  In the resin composition of the present invention, the mass ratio of the ionizing radiation curable resin and the polymer of the present invention is preferably in the range of 75:25 to 25:75. Within this range, the balance between the formability after crosslinking and curing to form the surface protective layer, the surface wear resistance, and the scratch resistance becomes good. From the above points, the mass ratio of the ionizing radiation curable resin and the polymer of the present invention is more preferably in the range of 60:40 to 25:75.

The resin composition of the present invention preferably has a storage elastic modulus at 140 ° C. in the range of 7.7 × 10 ^{5 to} 1.2 × 10 ⁸ . When the storage elastic modulus is 1.2 × 10 ⁸ or less, the surface protective layer is not cracked during vacuum forming and can be molded. In the case of a cross-linked resin, the higher the storage elastic modulus in the rubber state, the lower the average molecular weight between cross-linking points, that is, the higher the cross-linking density, so that the surface wear resistance, scratch resistance, solvent resistance, Contamination resistance is improved. Therefore, if the storage elastic modulus is within this range, a well-decorated decorative sheet that satisfies both the moldability after forming the surface protective layer, the surface wear resistance, and the scratch resistance at a high level. Is obtained.
The storage elastic modulus was measured in accordance with JIS K7244-1 and 7244-4, and a sheet having a width of 10 mm and a thickness of 15 μm formed by crosslinking and curing the resin composition constituting the surface protective layer was 10 mm in distance between clamps. Measured at a start temperature of 30 ° C., an end temperature of 180 ° C., a heating rate of 5 ° C./min, and a measurement frequency of 1 Hz.

Moreover, various additives can be mix | blended with the resin composition in this invention according to the desired physical property of the cured resin layer obtained. Examples of this additive include a weather resistance improver, an abrasion resistance improver, a polymerization inhibitor, a crosslinking agent, an infrared absorber, an antistatic agent, an adhesion improver, a leveling agent, a thixotropic agent, a coupling agent, A plasticizer, an antifoamer, a filler, a solvent, a coloring agent, etc. are mentioned.
Here, as the weather resistance improving agent, an ultraviolet absorber or a light stabilizer can be used. The ultraviolet absorber may be either inorganic or organic, and as the inorganic ultraviolet absorber, titanium dioxide, cerium oxide, zinc oxide or the like having an average particle diameter 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.

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

  The present invention also provides a decorative sheet having a surface protective layer obtained by crosslinking and curing the resin composition. That is, 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 is a decorative sheet obtained by crosslinking and curing the resin composition.

The decorative sheet of the present invention preferably has a tensile elongation of 50% or more in a tensile test based on JIS K 7127. The higher the tensile elongation is, the better the moldability is. However, if the tensile elongation is 50% or more, the surface protective layer is not cracked during vacuum forming with a commonly used vacuum forming die. The tensile elongation is more preferably 150% or more. When the tensile elongation is 150% or more, it follows a complicated shape or a shape with large deformation, and no cracks are generated in the surface protective layer.
The measurement conditions were a test piece having a width of 25 mm and a length of 120 mm, a tensile speed of 1000 mm / min, a distance between chucks of 80 mm, a distance between marked lines of 50 mm, and a temperature of 160 ° C. The surface protective layer was cracked. The tensile elongation at the time of entering is evaluated.
Further, the decorative sheet of the present invention may have a pattern layer or the like on the base material for the purpose of decoration. Hereinafter, a decorative sheet having a picture layer and a surface protective layer on a substrate will be described in detail with reference to FIG.

  FIG. 1 is a schematic view showing a cross section of a decorative sheet 10 of the present invention when used for insert molding. In the example shown in FIG. 1, the pattern layer 12, the masking layer 13, and the adhesive layer 14 are provided on the base material 11, and the surface protective layer 15 is provided on the opposite side of the pattern layer 12 of the base material 11. . Here, the surface protective layer 15 is formed by crosslinking and curing the resin composition of the present invention.

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, acrylic resins, polyolefin resins such as polypropylene and polyethylene, polycarbonate resins, acrylonitrile-butadiene-styrene resins (hereinafter referred to as “ABS resins”), vinyl chloride resins 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 0.03-1.0 mm normally, and when considering the cost etc., about 0.03-0.2 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 substrate may be subjected to a treatment such as forming a primer layer, or a coating for adjusting the color or a pattern from a design viewpoint may be formed in advance.

  The pattern layer 12 shown in FIG. 1 gives decorativeness to the resin molded product, and is formed by printing various patterns using ink and a printing machine. As patterns, there are stone patterns imitating the surface of rocks such as wood grain patterns, marble patterns (for example, travertine marble patterns), fabric patterns imitating cloth or cloth 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 that make up 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, metallic pigments composed of scaly foil pieces such as aluminum and brass, pearlescent pigments composed of scaly foil pieces such as titanium dioxide-coated mica and basic lead carbonate, and the like are used.

  The hiding layer 13 is a layer provided as desired, and is provided for the purpose of preventing the pattern color of the decorative sheet from being affected by changes and variations in the color of the backer film surface. 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.

  Since the decorative sheet 10 improves the adhesion with the injection resin, an adhesive layer 14 can be provided if desired. A thermoplastic resin or a curable resin is used for the adhesive layer 14 in accordance with the injection resin. Examples of the thermoplastic resin 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 a urethane resin and an epoxy resin.

The formation of the surface protective layer 15 can be obtained by preparing a coating liquid containing the above-described resin composition of the present invention, 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 substrate 11 so that the thickness after curing is 1-1000 μm, such as gravure coating, bar coating, roll coating, reverse roll coating, comma coating, etc. The known method, preferably gravure coating, is applied to form an uncured resin layer. When the thickness after curing is 1 μm or more, a cured resin layer having a desired function is obtained.

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 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.

  The cured resin layer thus formed has various functions by adding various additives, for example, a so-called hard coat function, anti-fogging coat function, and anti-fouling coat having high hardness and scratch resistance. A function, an antiglare coating function, an antireflection coating function, an ultraviolet shielding coating function, an infrared shielding coating function, and the like can also be imparted.

The decorative sheet 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 a thermoplastic resin such as a polyolefin resin such as polyethylene or polypropylene, an ABS resin, a styrene resin, a polycarbonate resin, an acrylic resin, or a vinyl chloride resin is representative. In addition, thermosetting resins such as urethane resins and epoxy resins can be used depending on applications.

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 the thermal pressure from the injection resin, so if the decorative sheet is close to the 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 decorated resin molded body produced as described above does not crack in the surface protective layer during the molding process, and its surface has high wear resistance and scratch resistance. Moreover, solvent resistance and chemical resistance are high with respect to the acrylic film conventionally used as a surface protective layer. 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.
The decorative resin molded body of the present invention is, for example, an interior material or exterior material of a vehicle such as an automobile, a construction member such as a skirting board or a fringe, a fitting such as a window frame or a door frame, a building such as a wall, a floor, or a ceiling. It is suitable for applications such as interior materials for products, housings and containers for household electrical appliances such as television receivers and air conditioners.

EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by this example.
Evaluation method (1) 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.
◎: No abnormal appearance ○: Minor gloss change or crack in part of 3D shape part or 200% stretched part, but no problem in practical use △; Minor part of 3D shape part or 200% stretched part Gloss change or crack generation ×: Significant gloss change or crack generation in the entire stretched part <Vacuum forming>
The decorative sheet is heated to 140-160 ° C. with an infrared heater and softened. Next, vacuum molding is performed using a mold having the same shape as the female mold for injection molding, and the inner mold is molded. The decorative sheet is released from the mold, and unnecessary parts are trimmed to obtain a molded product.

(2) Formability (simultaneous injection molding)
The decorative sheet obtained in each example and comparative example was subjected to simultaneous injection molding by the method shown below, and the appearance after molding was evaluated. The evaluation criteria are the same as the evaluation criteria in the vacuum forming.
<Injection molding simultaneous decoration>
The decorative sheet was placed in a movable mold, the decorative sheet was heated to 130 ° C. with an infrared radiation surface heater and softened, and then preliminarily molded by vacuum molding with an injection mold. Thereafter, both the male and female molds were clamped, and then the heat-resistant ABS resin was injected from the male gate, and the decorative sheet was laminated and integrated on the surface simultaneously with the molding of the injection molded product, thereby molding a decorative molded product. The injection molding conditions are: injection resin temperature 230 ° C., hot runner manifold portion temperature 240 ° C., gate portion temperature 235 ° C., mold is female die 45 ° C., male die 50 ° C., injection time 5 seconds, cooling time 20 Went in seconds. After mold opening, the decorative molded product was taken out of the mold to obtain a simultaneous injection molded decorative product.

(3) Scratch resistance About the decorative sheet manufactured by each Example and the comparative example, it tested based on JISL0849 [Abrasion testing machine type II (Gakushin type)], and evaluated with the following references | standards. The apparatus used for the test was a “Gakushin Abrasion Tester” manufactured by Tester Sangyo Co., Ltd., and evaluated using test pieces after 50 reciprocations at 500 g load using Kanakin No. 3 as a white cotton cloth for friction. The evaluation criteria are as follows.
◎: No scratch ○: No significant scratch on appearance △: Scratch or gloss change occurs on the surface of 1/4 to 1/2 of the test surface ×: Scratch or gloss change is 1/2 of the test surface Above

(4) Tensile elongation On the back surface of a transparent acrylic resin film having a thickness of 75 μm, a woodgrain pattern layer was formed by gravure printing. Next, the thickness after curing of the electron beam curable resin composition used for the production of the surface protective layer of the decorative sheet produced in each of the examples and comparative examples is 5 μm. Coated so that. This uncured resin layer is 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, and then a urethane film having a thickness of 10 μm is applied to the pattern layer of the sheet. Adhesive was applied, and a decorative sheet was obtained by laminating with a masked colored ABS resin sheet having a film thickness of 400 μm as a backer film. A test piece having a width of 25 mm and a length of 120 mm was cut out as a test piece, a tensile test was performed under the conditions of a tensile speed of 1000 mm / min, a chuck distance of 80 mm, a gauge line distance of 50 mm, and a temperature of 160 ° C., and the elongation was measured to 200%. . Evaluation was made based on the tensile elongation (%) at which cracks occurred in the cured film, and those having no cracks up to an elongation of 200% were expressed as> 200.

(5) Measurement of molecular weight A high-speed GPC apparatus manufactured by Tosoh Corporation was used. The column used was TSKgel αM (trade name) 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. The molecular weight and molecular weight distribution in the present invention were converted to polystyrene.

(6) Storage elastic modulus The resin compositions produced in each of the examples and comparative examples were applied on a PET film that had not been surface-treated so that the film thickness after crosslinking and curing would be about 15 μm. 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. The cured film was peeled off from the PET film, and a test piece having a width of 10 mm and a length of 20 mm was cut out. Using this test piece, in accordance with JIS K7244-1 and 7244-4, using a dynamic viscoelasticity measuring apparatus (“RSA II” manufactured by Rheometric Science F.E.), storage at 140 ° C. The elastic modulus was measured. The measurement was performed at a distance between clamps of 10 mm, a start temperature of 30 ° C., an end temperature of 180 ° C., a temperature increase rate of 5 ° C./min, and a measurement frequency of 1 Hz.

Example 1
A molar ratio of methyl methacrylate (hereinafter referred to as “MMA”) and methyl acrylate (hereinafter referred to as “MA”) to 25 parts by mass of tetrafunctional urethane acrylate which is an electron beam curable resin (hereinafter referred to as “EB resin”): 100: 75 parts by mass of a copolymer of 5 (hereinafter referred to as “PMMA-1”, see Table 1) was obtained to obtain a resin composition. The mass ratio of EB resin: PMMA-1 is 25:75.
Next, a transparent acrylic resin film having a thickness of 75 μm was used as a substrate, and a woodgrain pattern layer was formed on the back surface of the film by gravure printing. Next, the electron beam curable resin composition was applied to the surface where the pattern layer was not applied so that the thickness after curing was 5 μm. This uncured resin layer is irradiated with an electron beam with an acceleration voltage of 165 kV and an irradiation dose of 50 kGy (5 Mrad) to cure the electron beam curable resin composition, and then a urethane film having a thickness of 10 μm on the pattern layer side of the sheet. A decorative resin sheet was obtained by applying a resin adhesive and laminating it with a masked colored ABS resin sheet having a film thickness of 400 μm as a backer film.
The decorative sheet was evaluated by the above method. The evaluation results are shown in Table 2.

Examples 2-4
A decorative sheet was obtained in the same manner as in Example 1 except that the mass ratio of the EB resin and PMMA-1 was changed as described in Table 2. The decorative sheet was evaluated by the above method. The evaluation results are shown in Table 2.

Examples 5 and 6
A decorative sheet was obtained in the same manner as in Example 2 except that PMMA-2 and PMMA-3 shown in Table 1 were used instead of PMMA-1. The decorative sheet was evaluated by the above method. The evaluation results are shown in Table 2.

Examples 7 and 8
The same procedure as in Example 1 was performed except that bifunctional urethane acrylate (EB-2) was used as the EB resin instead of EB-1, and the mass ratio of the EB resin to PMMA-1 was changed as shown in Table 2. To obtain a decorative sheet. The decorative sheet was evaluated by the above method. The evaluation results are shown in Table 2.

Example 9
Instead of PMMA-1, MMA homopolymer [weight average molecular weight (Mw) 1.1 × 10 ⁵ , number average molecular weight (Mn) 0.64 × 10 ⁵ , polydispersity (Mw / Mn) 1.72 Hereinafter, a decorative sheet was obtained in the same manner as in Example 2 except that "PMMA-7" was used. The decorative sheet was evaluated by the above method. The evaluation results are shown in Table 2.

Example 10
A decorative sheet was obtained in the same manner as in Example 1 except that the same PMMA-7 as in Example 9 was used. The decorative sheet was evaluated by the above method. The evaluation results are shown in Table 2.

Comparative Examples 1-3
A decorative sheet was obtained in the same manner as in Example 2 except that PMMA-4, PMMA-5 and PMMA-6 shown in Table 1 were used instead of PMMA-1. The decorative sheet was evaluated by the above method. The evaluation results are shown in Table 2.

* 1 EB-1; tetrafunctional urethane acrylate * 2 EB-2; bifunctional urethane acrylate

The decorative sheet on which the surface protective layer using the resin composition of the present invention is formed is abruptly increased 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 or injection molding simultaneous decoration method. Cracks and cracks do not occur even under conditions of low temperature drop, rapid extension speed, and high extension.
Furthermore, it was confirmed that the moldability of the decorative resin molded product thus produced was excellent in moldability and high abrasion resistance and scratch resistance.

  By applying the resin composition of the present invention as a surface protective layer of the decorative sheet, the surface of the decorative sheet has high wear resistance and scratch resistance, and has good moldability and no cracks or the like. . Therefore, the decorative resin molded body manufactured using the decorative sheet of the present invention does not crack in the surface protective layer during the molding process, and the surface has high wear resistance and scratch resistance. Moreover, according to the manufacturing method of this invention, since a surface protective layer is fully hardened in the manufacture stage of a decorating sheet, the process of bridge | crosslinking and hardening a surface protective layer after manufacturing a decorating resin molding is unnecessary.

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

Explanation of symbols

10. Decorative sheet Base material 12. Pattern layer 13. Concealment layer 14. Adhesive layer 15. Surface protective layer 20. Backer film

Claims (12)

  A resin composition comprising an ionizing radiation curable resin and a polymer obtained by polymerizing (meth) acrylic acid ester containing at least methyl methacrylate as a monomer component, the gel permeation chromatography (GPC) of the polymer A resin composition for forming a surface protective layer of a decorative sheet having a measured polystyrene equivalent weight average molecular weight in the range of 90,000 to 120,000.   The resin composition according to claim 1, wherein the polydispersity of the polymer is in the range of 1.1 to 3.0.   The polymer is a copolymer of methyl methacrylate and methyl acrylate, and the structural unit derived from methyl acrylate is 0.1 to 10 moles relative to 100 moles of the structural unit derived from methyl methacrylate in the polymer. The resin composition according to claim 1, which is in the range of   The resin composition according to claim 1, wherein the polymer is a homopolymer of methyl methacrylate.   The resin composition according to claim 1, wherein a mass ratio of the ionizing radiation curable resin to the polymer is 75:25 to 25:75.   The resin composition according to claim 1, wherein the ionizing radiation curable resin is an electron beam curable resin. The resin composition according to any one of claims 1 to 6, wherein the storage elastic modulus at 140 ° C measured under the following measurement conditions is in the range of 7.7 x 10 ^{5 to} 1.2 x 10 ⁸ . .
Storage elastic modulus measurement conditions: In accordance with JIS K7244-1 and 7244-4, a sheet of 10 mm width and 15 μm thickness formed by crosslinking and curing the resin composition was 10 mm distance between clamps, start temperature 30 ° C., end The measurement is performed at a temperature of 180 ° C., a heating rate of 5 ° C./min, and a measurement frequency of 1 Hz.   A decorative sheet having at least a surface protective layer on a substrate, wherein the surface protective layer is obtained by crosslinking and curing the resin composition according to any one of claims 1 to 7. The decorative sheet according to claim 8, wherein the tensile elongation in a tensile test measured under the following measurement conditions based on JIS K 7127 is 50% or more.
Measurement conditions: Using a test piece with a width of 25 mm and a length of 120 mm, tensile elongation until a crack occurs in the surface protective layer under the conditions of a tensile speed of 1000 mm / min, a distance between chucks of 80 mm, a distance between marked lines of 50 mm, and a temperature of 160 ° C. Measure the degree.   A vacuum forming step in which the decorative sheet according to claim 8 or 9 is previously formed into a three-dimensional shape by a vacuum forming die, a step of trimming excess portions to obtain a formed sheet, and inserting the formed sheet into an injection mold A method for producing a decorative resin molded article, which includes a step of closing an injection mold and injecting a resin in a fluid state into the mold to integrate the resin and the molded sheet.   The decorative sheet according to claim 8 or 9, wherein the decorative sheet is installed so that the base material of the decorative sheet faces the molding surface of the movable mold having a molding surface of a predetermined shape. Heating and softening, and vacuum suction from the movable mold side, the softened decorative sheet is brought into close contact with the molding surface of the movable mold, thereby pre-molding the decorative sheet, molding surface After the movable mold and the fixed mold having the decorative sheet closely adhered to each other are clamped, a resin molding material in a fluid state is injected into the cavity formed by both molds, and solidified by filling. An injection molding step of stacking and integrating the formed resin molded body and the decorative sheet, and a resin molded body in which the decorative sheet is laminated by separating the movable mold from the fixed mold. Manufacturing method of decorative resin molded product that sequentially performs the process of taking out   A decorative resin molded product produced by the production method according to claim 10.

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