JP4957319B2 - Decorative sheet for steel plate and decorative steel plate using the same - Google Patents

Description

  The present invention relates to a decorative sheet for steel sheet and a decorative steel sheet using the same, and more specifically, a decorative sheet for steel sheet in which cracks are not generated in the outermost surface protective layer even when bending is performed, and a cosmetic using the same It relates to steel plates.

  In order to impart a design to a steel sheet, a sheet decorated with a vinyl chloride resin film, an olefin resin film, or a polyester resin film such as PET is laminated on the steel sheet. In particular, a PET film laminated steel sheet has been proposed as having stain resistance, molding processability and high hardness (see Patent Document 1 and Claims). In addition, a decorative sheet for a steel sheet is proposed in which a pattern layer, a transparent adhesive layer, and a transparent polyester resin layer are sequentially laminated on a base material sheet made of polyolefin resin or polyester resin ( Patent Document 2).

  The decorative sheet has high contamination resistance and high hardness, but has a problem that cracks are generated on the surface of the curved surface portion when the steel sheet is bent. When a polyester film such as PET is used, cracks hardly occur and a certain degree of workability is ensured, but there is a problem that resistance to scratches is low. In order to impart scratch resistance to PET or the like, there is a method of hard-coating the surface. When such a crack occurs, dirt accumulates in the crack portion, and the stain resistance decreases. Moreover, when it is used around water, problems such as generation of mold at the crack portion arise.

JP 2000-43192 A JP 2005-238498 A

  The present invention is for a steel sheet that has a high formability as well as a stain resistance and a scratch resistance, with no cracks in the curved surface portion even when the steel sheet is laminated and bent for the above problems. An object is to provide a decorative sheet and a decorative steel sheet.

  As a result of intensive studies to achieve the above object, the present inventors crosslinked a primer layer made of a urethane resin composition and an ionizing radiation curable resin composition on a substrate made of a biaxially stretched polyester film. It has been found that a decorative sheet for steel sheet in which hardened surface protective layers are laminated in this order can solve the above problems. The present invention has been completed based on such findings.

That is, the present invention
(1) A decorative sheet for a steel sheet in which at least a primer layer and a surface protective layer are laminated in this order on a substrate, the substrate is made of a biaxially stretched polyester film, and the primer layer is made of a urethane-based resin composition A decorative sheet for steel sheet, wherein the surface protective layer is a cross-linked and hardened ionizing radiation curable resin composition,
(2) The decorative sheet for steel sheet according to (1) above, wherein the urethane resin has an elongation at room temperature measured in accordance with JIS K6732 of 300% or more,
(3) The decorative sheet for steel sheet according to the above (1) or (2), which contains an inorganic pigment in the urethane resin composition,
(4) The decorative sheet for steel sheet according to any one of (1) to (3), wherein the ionizing radiation curable resin composition is an electron beam curable resin composition,
(5) The decorative sheet for steel sheet according to any one of (1) to (4), wherein the surface protective layer contains a matting agent, and the matting agent is an organic filler.
(6) The decorative sheet for steel sheet according to (5), wherein the organic filler is made of a urea-based resin having an average particle size of 5 μm or less,
(7) The decorative sheet for steel sheet according to any one of (1) to (6), wherein the biaxially stretched polyester film has a thickness of 25 to 100 µm.
(8) The decorative sheet for steel sheet according to any one of (1) to (7), wherein a concealing layer is further laminated on the opposite side of the primer layer of the base material, and (9) (1) to ( 8) a decorative steel sheet obtained by affixing the decorative sheet according to any one of
Is to provide.

  According to the present invention, even when laminated and bent on a steel sheet, the curved surface portion does not crack, and has high formability, and the curved surface portion also has excellent stain resistance and scratch resistance. A decorative sheet for steel sheet and a decorative steel sheet can be provided.

A typical structure of the decorative sheet for steel sheet according to the present invention will be described with reference to FIGS. FIG. 1 is a schematic view showing a cross section of a decorative sheet 1 for steel sheet according to the present invention. In the example shown in FIG. 1, a primer layer 3 and a surface protective layer 4 obtained by crosslinking and curing an electron beam curable resin composition are laminated on a substrate 2 in this order.
In the decorative sheet for steel sheet according to the present invention, the substrate 2 is made of a biaxially stretched polyester film. The polyester resin used here is not particularly limited, and those usually used in the field of decorative sheets can be used. Examples thereof include polyethylene terephthalate (hereinafter sometimes referred to as “PET”), polybutylene terephthalate, polyethylene naphthalate, polyarylate, polycarbonate, ethylene terephthalate-isophthalate copolymer, polyarylate, and the like. Among these, polyethylene terephthalate, polybutylene terephthalate, and the like are preferable, and polyethylene terephthalate is particularly preferable.

  As the polyester resin, in addition to various homopolymers, copolymerized polyester resins and polyester thermoplastic elastomers to which various copolymerization components or modifying components are added for the purpose of softening the resin can be used. For example, in the case of PET, in the condensation polymerization reaction of terephthalic acid and ethylene glycol, as the dicarboxylic acid component, for example, long-chain aliphatic dicarboxylic acids such as sebacic acid, eicoic acid, dodecanedioic acid, dimer acid, cyclohexanedicarboxylic acid, and the like / Or an alicyclic dicarboxylic acid can be introduced. In addition, polyether diols having hydroxyl groups at both ends, such as polyethylene glycol and polytetramethylene glycol, can be introduced as the diol component.

In the present invention, the polyester film used as the substrate 2 is prepared by, for example, forming a film by a calendar method, an inflation method, a T-die extrusion method, or the like, and biaxially stretching.
By using the biaxially stretched polyester resin film as the base material 2, it is possible to suppress the elongation of the surface protective layer 4, which will be described in detail later, and to suppress the occurrence of cracks in the surface protective layer 4.

The thickness of the base material 2 is not particularly limited, and can be appropriately set according to product characteristics, but a range of 25 to 100 μm is preferable. When the thickness of the substrate 2 is in the range of 25 to 100 μm, the tension applied to the surface protective layer 4 can be sufficiently relaxed.
The biaxially stretched polyester resin film used for the substrate 2 preferably has a tensile strength measured in accordance with JIS C2151 of 150 MPa or more.
When the tensile strength is 150 MPa or more, since it is highly rigid, local elongation generated in the bent portion can be suppressed, and extension of the upper surface protective layer can also be suppressed.

  The polyester resin used for the substrate 2 may be blended with additives as necessary. Examples of the additive include a filler, a flame retardant, an antioxidant, a lubricant, a foaming agent, a colorant, an ultraviolet absorber, and a light stabilizer.

Among the above additives, in particular, from the viewpoint of improving the elasticity and elongation rate of the base material 2, imparting impact resistance, and not causing cracks or cracks in the surface protective layer when subjected to bending, It is preferable to contain inorganic fillers such as calcium, barium sulfate, clay and talc.
The content of these inorganic fillers is preferably in the range of 5 to 60% by mass with respect to the substrate 2.

Moreover, it does not specifically limit as said coloring agent, Well-known coloring agents, such as a pigment and dye, can be used. For example, titanium white, zinc white, petal, vermilion, ultramarine blue, cobalt blue, titanium yellow, yellow lead, carbon black and other inorganic pigments; isoindolinone, Hansa Yellow A, quinacridone, permanent red 4R, phthalocyanine blue, indanthrene Organic pigments (including dyes) such as blue RS and aniline black; metal pigments such as aluminum and brass; pearlescent pigments made of foil powder such as titanium dioxide-coated mica and basic lead carbonate.
The coloring of the substrate 2 includes transparent coloring and opaque coloring (hiding coloring), and these can be arbitrarily selected. For example, when the ground color of the adherend (steel plate to which the decorative sheet is bonded) is concealed, opaque coloring may be selected. On the other hand, in order to make the ground pattern of the adherend visible, transparent coloring may be selected.
Moreover, about a ultraviolet absorber and a light stabilizer, the thing similar to what can be added to the resin composition which comprises the surface protective layer 4 of this invention explained in full detail later can be used.

The base material 2 can be subjected to physical or chemical surface treatment such as an oxidation method or a concavo-convex method on one side or both sides as desired in order to improve the adhesion with other layers.
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 according to the type of the substrate 2, but generally, a corona discharge treatment method is preferably used from the viewpoints of effects and operability.

The decorative sheet of the present invention is characterized by having a primer layer 3 made of a urethane resin composition. The urethane-based resin composition has flexibility, toughness, and elasticity. By providing such a specific primer layer 3, the impact, tensile force, or shearing force applied to the surface protective layer 4 during bending is reduced. And generation of cracks in the surface protective layer 4 can be suppressed.
As for the urethane resin used here, it is preferable that the elongation rate in normal temperature measured based on JISK6732 is 300% or more. When the elongation is 300% or more, the impact, tensile force or shear force applied to the surface protective layer 4 during bending can be sufficiently relaxed. From the above viewpoint, the elongation is more preferably 400% or more, and further preferably 500% or more. Further, the glass transition point (Tg) is −20 ° C. or less from the viewpoint of imparting bending workability at low temperatures in addition to the necessary and sufficient flexibility, toughness and elasticity of the decorative sheet for steel plate. Is preferred.

As a urethane resin, what satisfies said elongation rate and Tg is preferable, and it can select from a conventionally well-known thermoplastic urethane resin. For example, thermoplastic urethane resins such as polyester, polyether, acrylic, and polycarbonate are used alone or in combination.
As the thermoplastic urethane resin, for example, a urethane resin having no cross-linked structure and having a structure in which the skeleton structure is linear or branched is preferably exemplified. A saturated thermoplastic urethane resin having no isocyanate group is also preferred in that it is not cured by moisture or the like and has good stability over time.
On the other hand, when water resistance is particularly required, a urethane resin having a crosslinked structure to some extent while satisfying the above-described elongation rate and Tg is suitable. When particularly toughness is required, polyester urethane or polycarbonate Urethane is preferred.

As a specific example of such a thermoplastic urethane resin, a urethane resin composed of a linear polymer obtained by reacting a polyol having a hydroxyl group at a terminal and a polyisocyanate can be exemplified.
Examples of the polyol include polyester polyol, polyether polyol, polycarbonate polyol, and the like. More specifically, examples of the polyester polyol include poly (ethylene adipate), poly (butylene adipate), poly (neopentyl adipate), Examples include polyester diols such as poly (hexamethylene adipate), poly (butylene azelate), poly (butylene sebacate), and polycaprolactone. Polyether polyols include polyethylene oxide, polypropylene oxide, and poly (tetramethylene ether). Polyether diols such as poly (butylene carbonate) and poly (hexamethylene carbonate) are exemplified as polycarbonate polyols. Other examples include acrylic polyol, urethane polyol, fluorine-based polyol, acrylic silicone-based polyol, polyethylene glycol, and polypropylene glycol. These are used alone or in combination of two or more.

  Examples of the diisocyanate component include various aliphatic (or alicyclic) or aromatic diisocyanates conventionally known in the polyurethane field. For example, aliphatic (or alicyclic) systems include aliphatic isocyanates such as 1,6-hexamethylene diisocyanate, alicyclic isocyanates such as isophorone diisocyanate and hydrogenated tolylene diisocyanate, and 2,4-tolylene diisocyanate. 2,6-tolylene diisocyanate, xylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 1,5-naphthalene diisocyanate and other aromatic isocyanates. These can be used alone or in combination of two or more.

The urethane resin composition used in the present invention can contain a colorant. The colorant is not particularly limited, and examples thereof include the same ones that can be used for coloring the substrate 2 and carbon black.
Of these colorants, inorganic pigments such as titanium white (titanium oxide) are preferred. These inorganic pigments have a high effect of concealing the base, and also have an effect of cutting off ultraviolet rays. Furthermore, there is an effect of preventing blocking in the production process of the decorative sheet.
As content of an inorganic pigment, it is preferable that it is the range of 5-300 mass parts with respect to 100 mass parts of urethane type resins. The effect as an inorganic pigment can fully be exhibited as it is 5 mass parts or more. On the other hand, when the content of the inorganic pigment is too large, the elongation rate of the urethane resin composition is decreased. However, if it is 300 parts by mass or less, sufficient toughness is maintained even when the elongation rate is decreased.
The particle size of the inorganic pigment is preferably 5 μm or less. If it is 5 μm or less, there is no problem that cracks are generated starting from the inorganic particles. From the above points, the particle size is preferably 2 μm or less.

Although there is no restriction | limiting in particular about the thickness of the primer layer 3, The range of 1-10 micrometers is preferable. When the thickness is 1 μm or more, the impact, tensile force or shear force applied to the surface protective layer 4 during bending can be relaxed, and the occurrence of cracks in the surface protective layer 4 can be suppressed. Further, when it is 10 μm or less, blocking can be suppressed in the production process of the decorative sheet, and when the printing surface comes into contact with the guide roll that leads the printing paper, the printing ink is transferred to the guide roll. There is no inconvenience. From the above points, the thickness of the primer layer 3 is preferably in the range of 1 to 5 μm.
Moreover, the coating amount of the urethane resin composition forming the primer layer is usually in the range of 1 to 10 g / m ² , more preferably in the range of ^{2 to 5} g / m ² .

Next, as shown in FIG. 2, the decorative sheet of the present invention can be further laminated with a concealing layer 6 via an adhesive layer 5 on the opposite side of the primer layer. Even when the base material 2 is transparent and when the base material 2 is concealed and colored, it can be formed in order to stabilize the concealability.
It does not specifically limit as a material which comprises the concealment layer 6, A vinyl chloride resin film, an olefin film, a polyester film etc. can be used. Among these, it is preferable to use a polyester film such as a biaxially stretched PET film similar to the substrate 2 from the viewpoint of suppressing the occurrence of cracks in the surface protective layer 4.

The film constituting the masking layer 6 usually contains a colorant in order to exhibit the function as the masking layer. The kind of the colorant is not particularly limited, and the same colorant as that which can be used for coloring the base material 2 can be used.
Although there is no restriction | limiting in particular as the thickness of the film which comprises the concealing layer 6, The range of 25-100 micrometers is preferable. When the thickness is 25 μm or more, a sufficient hiding effect is obtained, and when the thickness is 100 μm or less, the surface protective layer 4 is not extended more than necessary due to the curvature, and the generation of cracks can be further suppressed.
Although the formation method of the concealing layer 6 is not particularly limited, a method that can be formed so as to cover the entire base material 2 (entire solid surface) is preferable. For example, a roll coating method, a knife coating method, an air knife coating method, a die coating method, a lip coating method, a comma coating method, a kiss coating method, a flow coating method, a dip coating method and the like are preferable.

There is no restriction | limiting in particular as a material used for the adhesive bond layer 5, A well-known adhesive can be used in the field of a decorative sheet. Specific examples thereof include thermoplastic resins such as polyamide resin, acrylic resin and vinyl acetate resin, and curable resins such as thermosetting urethane resin. Further, a two-component curable polyurethane resin or polyester resin using isocyanate as a curing agent can also be applied. Among these, a thermoplastic resin is preferable because it functions as a cushion layer and has an effect of suppressing cracks in the surface protective layer 4 during processing of the decorative steel sheet.
Although there is no restriction | limiting in particular in the thickness of the adhesive bond layer 5, Usually, the thickness after drying is the range of 3-50 micrometers.

  In the decorative sheet of this invention, you may provide a pattern layer between the base material 2 and the primer layer 3, or the back side (opposite side of the primer layer 3) of the base material 2 (not shown). The design pattern layer imparts design properties with a desired design to the decorative sheet and the decorative steel plate, and the type of the design is not particularly limited. Examples thereof include a wood grain pattern, a stone pattern, a grain pattern, a tiled pattern, a brickwork pattern, a cloth pattern, a leather pattern, a geometric figure, a character, a symbol, and an abstract pattern.

The method for forming the pattern layer is not particularly limited. For example, a colored ink or coating obtained by dissolving (or dispersing) a known colorant (dye or pigment) in a solvent (or dispersion medium) together with a binder resin. What is necessary is just to form by the printing method etc. which used the agent etc.
Examples of the colorant include inorganic pigments such as carbon black, titanium white, zinc white, dial, bitumen, and cadmium red; azo pigments, lake pigments, anthraquinone pigments, quinacridone pigments, phthalocyanine pigments, isoindolinone pigments, dioxazine pigments. Organic pigments such as aluminum powder, metal powder pigments such as bronze powder, pearlescent pigments such as titanium oxide-coated mica and bismuth oxide chloride; fluorescent pigments; These colorants can be used alone or in admixture of two or more. These colorants may further contain fillers such as silica, extender pigments such as organic beads, neutralizing agents, surfactants and the like.

Examples of the binder resin include acrylic resins, styrene resins, polyester resins, urethane resins, chlorinated polyolefin resins, vinyl chloride-vinyl acetate copolymer resins, polyvinyl butyral resins, alkyd resins, petroleum Resin, ketone resin, epoxy resin, melamine resin, fluorine resin, silicone resin, fiber derivative, rubber resin and the like. These resins can be used alone or in admixture of two or more.
Examples of the solvent (or dispersion medium) include petroleum-based organic solvents such as hexane, heptane, octane, toluene, xylene, ethylbenzene, cyclohexane, and methylcyclohexane; ethyl acetate, butyl acetate, 2-methoxyethyl acetate, acetic acid -2-Ethoxyethyl and other ester organic solvents; methyl alcohol, ethyl alcohol, normal propyl alcohol, isopropyl alcohol, isobutyl alcohol, ethylene glycol, propylene glycol and other alcohol organic solvents; acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, etc. Ketone organic solvents; ether organic solvents such as diethyl ether, dioxane, tetrahydrofuran; dichloromethane, carbon tetrachloride, trichloroethylene, tetrachloroethylene Chlorinated organic solvents such emissions; inorganic solvents such as water. These solvents (or dispersion media) can be used alone or in admixture of two or more.

Examples of the printing method used for forming the pattern layer include a gravure printing method, an offset printing method, a screen printing method, a flexographic printing method, an electrostatic printing method, and an inkjet printing method. When forming a solid pattern pattern layer, for example, roll coating method, knife coating method, air knife coating method, die coating method, lip coating method, comma coating method, kiss coating method, flow coating method, dip coating Various coating methods such as a coating method may be mentioned. In addition, a hand-drawn method, an ink-sink method, a photographic method, a transfer method, a laser beam drawing method, an electron beam drawing method, a partial vapor deposition method such as metal, an etching method, or the like may be used.
The thickness of the pattern layer is not particularly limited, and can be set as appropriate according to product characteristics, but the layer thickness after drying is about 0.1 to 10 μm.

Next, the surface protective layer 4 is formed by crosslinking and curing the ionizing radiation curable resin composition. Here, the ionizing radiation curable resin composition is one having an energy quantum capable of crosslinking and polymerizing molecules in an electromagnetic wave or a charged particle beam, that is, crosslinking or curing by irradiating ultraviolet rays or electron beams. Refers to a resin composition. Specifically, it can be appropriately selected from polymerizable monomers, polymerizable oligomers or prepolymers conventionally used as ionizing radiation curable resin compositions.
Typically, a (meth) acrylate monomer having a radical polymerizable unsaturated group in the molecule is suitable as the polymerizable monomer, and among them, a polyfunctional (meth) acrylate is preferable. Here, “(meth) acrylate” means “acrylate or methacrylate”. The polyfunctional (meth) acrylate is not particularly limited as long as it is a (meth) acrylate having two or more ethylenically unsaturated bonds in the molecule. Specifically, ethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) ) Acrylate, polyethylene glycol di (meth) acrylate, hydroxypivalate neopentyl glycol di (meth) acrylate, dicyclopentanyl di (meth) acrylate, caprolactone modified dicyclopentenyl di (meth) acrylate, ethylene oxide modified diphosphate ( (Meth) acrylate, allylated cyclohexyl di (meth) acrylate, isocyanurate di (meth) acrylate, trimethylolpropane tri (meth) acrylate, ethylene oxide modified trimethylo Propane tri (meth) acrylate, dipentaerythritol tri (meth) acrylate, propionic acid modified dipentaerythritol tri (meth) acrylate, pentaerythritol tri (meth) acrylate, propylene oxide modified trimethylolpropane tri (meth) acrylate, tris ( Acryloxyethyl) isocyanurate, propionic acid modified dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, ethylene oxide modified dipentaerythritol hexa (meth) acrylate, caprolactone modified dipentaerythritol hexa (meth) acrylate, etc. Is mentioned. These polyfunctional (meth) acrylates may be used singly or in combination of two or more.

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

  Next, as the polymerizable oligomer, an oligomer having a radical polymerizable unsaturated group in the molecule, for example, epoxy (meth) acrylate, urethane (meth) acrylate, polyester (meth) acrylate, polyether (meth) acrylate 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 novolak epoxy resin, bisphenol epoxy resin, aliphatic vinyl ether, aromatic vinyl ether, etc. There are oligomers having a cationic polymerizable functional group.

When an ultraviolet curable resin composition is used as the ionizing radiation curable resin composition, it is desirable to add about 0.1 to 5 parts by mass of the photopolymerization initiator with respect to 100 parts by mass of the resin composition. The initiator for photopolymerization can be appropriately selected from those conventionally used and is not particularly limited. For example, for a polymerizable monomer or polymerizable oligomer having a radically polymerizable unsaturated group in the molecule. Benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin-n-butyl ether, benzoin isobutyl ether, acetophenone, dimethylaminoacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2 -Phenylacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholino-propane-1 - 4- (2-hydroxyethoxy) phenyl-2 (hydroxy-2-propyl) ketone, benzophenone, p-phenylbenzophenone, 4,4′-diethylaminobenzophenone, dichlorobenzophenone, 2-methylanthraquinone, 2-ethylanthraquinone, 2 -Tertiary butylanthraquinone, 2-aminoanthraquinone, 2-methylthioxanthone, 2-ethylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 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 composition as the ionizing radiation curable resin composition. This is because the electron beam curable resin composition can be made solvent-free, is more preferable from the viewpoint of environment and health, and does not require a photopolymerization initiator and can provide stable curing characteristics.

  Moreover, various additives can be mix | blended with the ionizing radiation-curable resin composition in this invention according to the desired physical property of the cured resin layer obtained. Examples of the 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, and a coupling agent. , Plasticizers, antifoaming agents, fillers, solvents, colorants and the like.

  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. Examples of the organic ultraviolet absorber include benzotriazole-based compounds, specifically 2- (2-hydroxy-5-methylphenyl) benzotriazole, 2- (2-hydroxy-3,5-di-tert-). Amylphenyl) benzotriazole, 3- [3- (benzotriazol-2-yl) -5-tert-butyl-4-hydroxyphenyl] propionic acid ester of polyethylene glycol, and the like. On the other hand, examples of the light stabilizer include hindered amines, specifically 2- (3,5-di-tert-butyl-4-hydroxybenzyl) -2′-n-butylmalonate bis (1,2,2). , 6,6-pentamethyl-4-piperidyl), bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate, tetrakis (2,2,6,6-tetramethyl-4-piperidyl)- 1,2,3,4-butanetetracarboxylate and the like. 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.
As the crosslinking agent, for example, fluorinated acrylate, silicone acrylate, polyisocyanate compound, epoxy compound, metal chelate compound, aziridine compound, oxazoline compound and the like are used. Of these, fluorinated acrylate and silicone acrylate are particularly preferable.
As the filler, for example, barium sulfate, talc, clay, calcium carbonate, aluminum hydroxide and the like are used.
Examples of the colorant include known coloring pigments such as quinacridone red, isoindolinone yellow, phthalocyanine blue, phthalocyanine green, titanium oxide, and carbon black.
As the infrared absorber, for example, a dithiol metal complex, a phthalocyanine compound, a diimmonium compound, or the like is used.

In the present invention, the polymerizable monomer and polymerizable oligomer, which are the electron beam curing components, and various additives are homogeneously mixed at predetermined ratios to prepare a coating liquid comprising an electron beam curable resin composition. To do. The viscosity of the coating solution is not particularly limited as long as it is a viscosity capable of forming an uncured resin layer on the surface of the substrate by a coating method described later.
In the present invention, the coating liquid prepared in this way is applied to the surface of the substrate so that the thickness after curing is 1 to 20 μm, gravure coating, bar coating, roll coating, reverse roll coating, Coating is performed by a known method such as comma coating, preferably gravure coating, to form an uncured resin layer.
The preferable film thickness after curing is appropriately determined according to the type of resin used in the range of 1 to 20 μm. When the resin composition is composed of a hard system, the relatively thin film thickness is less likely to cause cracks in the surface protective layer. Conversely, when the resin composition is a soft system, the film thickness is relatively thick. Cracks in the surface protective layer are unlikely to occur.

The uncured resin layer formed as described above is irradiated with an electron beam to cure the uncured resin layer. The acceleration voltage can be appropriately selected according to the resin to be used and the thickness of the layer, but it is preferable to cure the uncured resin layer at an acceleration voltage of about 70 to 300 kV.
In electron beam irradiation, the transmission capability increases as the acceleration voltage increases. Therefore, when using a base material that deteriorates due to the electron beam as the base material, the transmission depth of the electron beam and the thickness of the resin layer are substantially equal. By selecting the accelerating voltage so as to be equal to each other, it is possible to suppress the irradiation of the electron beam to the base material, and to minimize the deterioration of the base material due to the excessive electron beam.
The irradiation dose is preferably an amount that saturates the crosslink density of the resin layer, and is usually selected in the range of 5 to 300 kGy.

  The electron beam source is not particularly limited, and for example, various electron beam accelerators such as a Cockloft 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 are used. be able to.

  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.

In the decorative sheet of the present invention, the gloss of the surface can be controlled by an additive, and a matte surface can be obtained by adding a matting agent. Various matting agents are used in this case, and inorganic fine powders, organic fillers, and the like can be used. As inorganic fine powder, silica, clay, heavy calcium carbonate, light calcium carbonate, precipitated barium sulfate, calcium silicate, synthetic silicate, fine powder of silicate, etc. can be used, and acrylic, urethane, Examples include fillers made of nylon, polypropylene, urea resins, styrene crosslinked fillers, benzoguanamine crosslinked fillers, and the like. Here, the filler also contains beads.
In the present invention, organic fillers are more preferable than inorganic fillers such as silica that are commonly used. When a matting agent is added, cracks may occur from the interface between the resin constituting the surface protective layer and the matting agent, but the organic filler is more familiar with the ionizing radiation curable resin and is caused by the interface. This is because the occurrence of cracks is less likely to occur. Among organic fillers, fillers made of urea resins are particularly preferable.
The average particle size of the matting agent is preferably 5 μm or less and more preferably 3 μm or less in order to suppress cracks generated from the interface between the resin constituting the surface protective layer and the matting agent. On the other hand, in order to obtain a sufficient matting effect, the average particle size of the matting agent is preferably 1 μm or more.

The decorative sheet of the present invention is used as a decorative steel sheet by sticking to a steel sheet. Examples of the steel plate to be adhered include metal materials such as iron, aluminum, and copper, and these may be subjected to surface treatment such as hot dip galvanizing or electrogalvanizing. Moreover, the shape of a to-be-adhered body is not specifically limited, For example, shapes, such as a flat plate, a curved surface board, a polygonal column, can be employ | adopted arbitrarily.
Moreover, there is no restriction | limiting in particular about the thickness of a steel plate, Usually, it is about 0.2-1 mm. In addition, in order to provide the concealability, the steel plate which is a to-be-adhered body may be directly colored on the steel plate and provided with a coating layer.

The adhesive or pressure-sensitive adhesive used for laminating the steel sheet as the adherend and the decorative sheet is not particularly limited, and any adhesive or pressure-sensitive adhesive known in the field of decorative sheets can be used. As the adhesive, the same adhesive as that used in the adhesive layer 5 for adhering the hiding layer 6 can be used. Further, as the pressure-sensitive adhesive, an acrylic, urethane-based, silicone-based, rubber-based or the like can be appropriately selected and used. Among these, from the viewpoint of weather resistance and the like, an acrylic pressure-sensitive adhesive mainly composed of a polymer or copolymer of an acrylic monomer such as acrylic acid ester or methacrylic acid ester is preferable, and in particular, n-butyl acrylate, 2- Ethylhexyl acrylate and the like are suitable.
Moreover, a crosslinking agent can also be added and specifically, an isocyanate type, a metal chelate, an epoxy type, and a melamine type are mentioned.
Although there is no restriction | limiting in particular about the thickness of this adhesive agent or an adhesive, Usually, it is the range of 1-100 micrometers.

  The steel sheet to which the decorative sheet of the present invention is attached is suitably used for, for example, a white wall or the like where a wall of a unit bath that easily gets dirty or a marker is required to be erased. In addition, for building interior materials such as walls and ceilings, surface materials for fittings such as doors, door frames and window frames, surface materials for construction materials such as skirts and skirting boards, surface materials for furniture such as fences and cabinets, etc. Can also be used. Further, the decorative sheet itself can be used as a laminate material, a wrapping material, or the like for a building material member without using a steel plate as an adherend. For example, the decorative sheet of the present invention may be attached to the surface of a steel plate substrate used in a bathroom or the like for decoration.

EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by this example.
(Evaluation methods)
(1) Bending test of decorative steel plate The decorative steel plate manufactured in each of the examples and comparative examples was subjected to a 90-degree bending test at a test temperature of 25 ± 5 ° C. and an inner radius of 2 mm in accordance with JIS K6744. Evaluation was performed according to the following criteria.
○: No cracks occurred.
Δ: A fine crack occurred in the bent portion, but the design was not impaired.
X: A crack occurred.
(2) Scratch resistance Measured according to JIS L0849 using a “Gakushin friction tester” manufactured by Tester Sangyo Co., Ltd. As measurement conditions, it was reciprocated 2000 times with a load of 500 g. The evaluation criteria are as follows.
○: No change in appearance.
X: The appearance was damaged and the gloss was changed.
(3) Contamination resistance In accordance with JIS K-6902, the contaminant was applied to the surface of the decorative steel sheet, and the residual state of the contaminant after wiping was visually observed. Judgment criteria were evaluated as follows.
○: No contamination remained.
Δ: Although the contaminants remained, they were minor and had no problem in practical use.
X: Residual contaminants were remarkable.

Example 1
As the substrate 2, a biaxially stretched transparent PET film (“Cosmo Shine A4300” manufactured by Toyobo Co., Ltd.) having a thickness of 50 μm was prepared. A primer ink containing a soft urethane resin (elongation rate 780%, Tg-41 ° C.) as a binder and containing 50% by weight of titanium white (titanium oxide, particle size 0.2 to 0.3 μm) is used as a base material. The primer layer 3 was obtained by coating on one side of No. 2 at a coating amount of 3.5 g / m ² .
Next, 60 parts by mass of ethylene oxide-modified trimethylolpropane ethylene oxide triacrylate, which is a trifunctional acrylate monomer, and 40 parts by mass of dipentaerythritol hexaacrylate, which is a hexafunctional acrylate monomer, are formed on the primer layer 3 and a silicone acrylate prepolymer. An electron beam curable resin composition to which 1 part by mass and 5 parts by mass of a filler made of urea resin were added was applied by a gravure direct coater method. After the coating, an electron beam with an acceleration voltage of 175 kV and an irradiation dose of 50 kGy (5 Mrad) was irradiated to cure the electron beam curable resin composition, whereby the surface protective layer 4 was obtained. Next, curing was performed at 70 ° C. for 24 hours to obtain a decorative sheet 1. The thickness of the surface protective layer 4 was 10 μm.
The decorative sheet 1 was attached to a galvanized steel sheet having a thickness of 0.4 mm using a urethane-based adhesive to obtain a decorative steel sheet of the present invention.
The decorative steel sheet was evaluated by the above method. The evaluation results are shown in Table 1.

Examples 2 and 3
A decorative steel sheet was obtained in the same manner as in Example 1 except that the thickness of the substrate 2 was 75 μm and 188 μm, respectively. The results of evaluation in the same manner as in Example 1 are shown in Table 1.

Example 4
In Example 1, a 50 μm-thick white PET film (“Diameter” manufactured by Mitsubishi Chemical Polyester Film Co., Ltd.) is interposed on the side opposite to the side on which the primer layer 3 is formed with respect to the substrate 2 through a polyester urethane adhesive. A decorative steel plate was obtained in the same manner as in Example 1 except that the foil and the concealing layer 6) were affixed. The results of evaluation in the same manner as in Example 1 are shown in Table 1.

Example 5
A decorative steel plate was obtained in the same manner as in Example 4 except that the thickness of the substrate 2 was 75 μm. The results of evaluation in the same manner as in Example 1 are shown in Table 1.

Example 6
In Example 1, a decorative steel sheet was obtained in the same manner as in Example 1 except that a soft urethane resin (elongation rate: 350%) was used as the resin used for the binder of the primer layer 3. The results of evaluation in the same manner as in Example 1 are shown in Table 1.

Example 7
A decorative steel sheet was obtained in the same manner as in Example 1 except that a soft urethane resin (elongation rate 400%) was used as the resin used for the binder of the primer layer 3. The results of evaluation in the same manner as in Example 1 are shown in Table 1.

Example 8
A decorative steel plate was obtained in the same manner as in Example 1 except that a soft urethane resin (elongation rate: 500%) was used as the resin used for the binder of the primer layer 3. The results of evaluation in the same manner as in Example 1 are shown in Table 1.

Example 9
In Example 1, a decorative steel sheet was obtained in the same manner as in Example 1 except that a filler (average particle size: 1 μm) made of urea resin was used as the matting agent in the surface protective layer 4. The results of evaluation in the same manner as in Example 1 are shown in Table 1.

Example 10
In Example 1, a decorative steel sheet was obtained in the same manner as in Example 1 except that a filler (average particle size: 3 μm) made of urea resin was used as the matting agent in the surface protective layer 4. The results of evaluation in the same manner as in Example 1 are shown in Table 1.

Example 11
In Example 1, a decorative steel plate was obtained in the same manner as in Example 1 except that a filler (average particle size: 4 μm) made of urea resin was used as the matting agent in the surface protective layer 4. The results of evaluation in the same manner as in Example 1 are shown in Table 1.

Comparative Examples 1-5
A decorative steel sheet was obtained in the same manner as in Examples 1 to 5 except that the primer layer 3 was not provided for each of Examples 1 to 5. The results of evaluation in the same manner as in Example 1 are shown in Table 1.

Comparative Example 6
A decorative steel sheet was obtained in the same manner as in Example 1 except that a polypropylene film (indicated as “PP” in the table, thickness 80 μm, tensile strength 50 MPa) was used as the substrate 2. The results of evaluation in the same manner as in Example 1 are shown in Table 1.

Comparative Example 7
A decorative steel sheet was obtained in the same manner as in Example 1 except that a polyethylene film (indicated in the table as “PE”, thickness 80 μm, tensile strength 50 MPa) was used as the substrate 2. The results of evaluation in the same manner as in Example 1 are shown in Table 1.

Comparative Example 8
A decorative steel plate was obtained in the same manner as in Example 1 except that a polyvinyl chloride film (indicated as “PVC” in the table, thickness 80 μm, tensile strength 50 MPa) was used as the substrate 2. The results of evaluation in the same manner as in Example 1 are shown in Table 1.

Comparative Example 9
A decorative steel sheet was obtained in the same manner as in Example 1 except that a biaxially stretched polypropylene film (indicated as “OPP” in the table, thickness 60 μm, tensile strength 140 MPa) was used as the substrate 2. The results of evaluation in the same manner as in Example 1 are shown in Table 1.

  According to the present invention, a decorative sheet for a steel sheet and a decorative steel sheet, which are not cracked in a curved surface portion even when laminated and bent by a steel sheet, have high formability, and have stain resistance and scratch resistance. Can be obtained. The decorative sheet and the decorative steel plate of the present invention are a wall interior material such as a ceiling, a door, a door frame, a surface material of a fitting such as a window frame, a surface material of a construction member such as a curb, a baseboard, a fence, a cabinet. It can also be used for furniture surface materials. In particular, it is suitably used for a whiteboard or the like where the wall of a unit bath that is easily soiled or the marker needs to be erased.

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

Explanation of symbols

1. Cosmetic sheet Base material 3. Primer layer 4. 4. Surface protective layer Adhesive layer 6. Concealment layer

Claims (8)

A decorative sheet for a steel sheet in which at least a primer layer and a surface protective layer are laminated in this order on a substrate, the substrate is made of a biaxially stretched polyester film, the primer layer is made of a urethane resin composition, Electron beam curable resin composition whose elongation at normal temperature measured in accordance with JIS K6732 is 300% or more and whose surface protective layer contains a polyfunctional (meth) acrylate monomer as an electron beam curable resin. A decorative sheet for steel sheet, which is obtained by crosslinking and curing a product. The decorative sheet for steel sheet according to claim 1, wherein the urethane resin composition contains an inorganic pigment. The decorative sheet for steel sheet according to claim 1 or 2 , wherein the surface protective layer contains a matting agent, and the matting agent is an organic filler. The decorative sheet for steel sheet according to claim 3, wherein the organic filler is made of a urea-based resin having an average particle size of 5 µm or less. The decorative sheet for steel sheet according to any one of claims 1 to 4, wherein the biaxially stretched polyester film has a thickness of 25 to 100 µm. The decorative sheet for steel sheet according to any one of claims 1 to 5, wherein the biaxially stretched polyester film has a tensile strength measured according to JIS C2151 of 150 MPa or more. The decorative sheet for steel sheet according to any one of claims 1 to 6, wherein a concealing layer is further laminated on the opposite side of the primer layer of the substrate. The decorative steel plate which stuck the decorative sheet in any one of Claims 1-7 on the steel plate.

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