JP6487715B2 - Painted body - Google Patents

Description

  The present invention relates to a coated body comprising a metal substrate and a coating film, and relates to a coated body comprising a coating film having excellent adhesion, workability and oil resistance of the coating film to the metal substrate.

  Conventionally, from the viewpoint of adhesion to a metal substrate, a thermosetting paint or a room temperature curable paint has been used. However, since the thermosetting paint and the room temperature curable paint contain water and / or an organic solvent, a drying process is required, and the production efficiency of the coating film is poor. There is also concern about the environmental impact caused by the volatilization of organic solvents.

  By the way, the active energy ray-curable coating has advantages such as high productivity, resource saving, energy saving, and reduction of environmental load, and has recently been studied as a coating for metal substrates.

  For example, Japanese Patent Application Laid-Open No. 2008-222848 (Patent Document 1) has (meth) acrylate having a phosphate ester group and a polyfunctional (meth) acrylate as main components, and is excellent for metals and metal oxide substrates. An ultraviolet curable hard coat resin composition having adhesion and excellent hardness and excellent productivity is described.

  JP-A-2009-57525 (Patent Document 2) discloses an ultraviolet-curing composition having a benzyl group-containing acrylate oligomer as a main component, excellent adhesion to plastics, metals and metal oxide substrates, and excellent productivity. A mold hard coat resin composition is described.

  Furthermore, Japanese Patent Application Laid-Open No. 2011-246515 (Patent Document 3) includes a dibutyl fumarate unit and a hydroxyl group-containing monomer unit, having a mass average molecular weight of 20,000 to 40,000 and a hydroxyl value of 40 to 60 mgKOH / a copolymer (A) which is g, (meth) acrylate (B) having at least one (meth) acryloyloxy group in the molecule, and a photopolymerization initiator (C), and having excellent smoothness. An active energy ray-curable coating composition having excellent curability, which has a cured film surface and can provide a molded article having excellent adhesion between the cured film and a metal substrate and excellent moisture resistance, is described. .

JP 2008-222848 A JP 2009-57525 A JP 2011-246515 A

  Although the active energy ray-curable coating has the advantages as described above, the shrinkage of the coating film during the curing process is large, so that the adhesion to the substrate, particularly the adhesion to the metal substrate, tends to be reduced. Cracks are likely to occur during processing. Furthermore, various physical properties such as rust prevention, water resistance, and oil resistance tend to decrease due to a decrease in adhesion. Patent Documents 1 to 3 describe active energy ray-curable coating compositions having excellent adhesion to metal substrates, but adhesion to metal substrates not subjected to surface treatment (untreated metal substrates). There is still room for improvement in the processability of the coating film. Moreover, in the specific embodiment of patent documents 1-3, all use the organic solvent and a drying process is required.

  Accordingly, an object of the present invention is to provide a coated body that solves the above-described problems of the prior art and includes a metal base material and a coating film formed on the surface of the metal base material. It is providing the coating body provided with the coating film which is excellent in adhesiveness, workability, and oil resistance.

As a result of intensive studies to achieve the above object, the present inventor has painted the surface of a metal substrate with an active energy ray-curable paint containing a urethane (meth) acrylate oligomer, and is formed on the surface of the metal substrate. It has been found that by adjusting the Martens hardness of the film to 10 to 250 N / mm ² , a coated body having a coating film excellent in adhesion, workability and oil resistance of the coating film to the metal substrate can be obtained. It came to complete.

That is, the coated body of the present invention is a coated body having a metal substrate and a coating film formed on the surface of the metal substrate, and the coating film includes an active energy ray containing a urethane (meth) acrylate oligomer. It is obtained by a curable paint, and the coating film has a Martens hardness of 10 to 250 N / mm ² .

  In a preferred example of the coated body of the present invention, the coating film further contains at least one pigment selected from the group consisting of a color pigment, an extender pigment, and a rust preventive pigment.

In another preferred embodiment of the coated body of the present invention, the active energy ray-curable paint is,
(A) a radical-polymerizable oligomer, and a cured product of the oligomer having a Martens hardness of greater than 40 N / mm ² and (B) a urethane (meth) acrylate oligomer, the cured product of the oligomer having a Martens hardness Including an oligomer having an N of 40 N / mm ² or less,
The mass ratio (A / B) of (A) radical polymerizable oligomer and (B) urethane (meth) acrylate oligomer is 85/15 to 15/85.

  In another preferred embodiment of the coated body of the present invention, the radically polymerizable oligomer (A) is selected from the group consisting of an ester (meth) acrylate oligomer, an epoxy (meth) acrylate oligomer, and a urethane (meth) acrylate oligomer. At least one oligomer selected.

  In another preferred embodiment of the coated body of the present invention, the (B) urethane (meth) acrylate oligomer has a number average molecular weight in the range of 800 to 15,000 and the number of functional groups in the range of 2 to 6.

  In another preferred embodiment of the coated body of the present invention, the coating film further contains oxide fine particles having an average particle diameter of 1 nm to 100 nm.

According to the coated body of the present invention, the surface of the metal substrate is coated with the active energy ray-curable coating material containing the urethane (meth) acrylate oligomer, and the Martens hardness of the coating film formed on the surface of the metal substrate is 10 to 250 N. By adjusting to / mm ² , it is possible to provide a coated body having a coating film excellent in adhesion, workability and oil resistance of the coating film to the metal substrate.

Below, the coated body of this invention is demonstrated in detail. The coated body of the present invention is a coated body having a metal substrate and a coating film formed on the surface of the metal substrate, and the coating film includes an active energy ray curable composition containing a urethane (meth) acrylate oligomer. It is obtained by a paint and has a Martens hardness of 10 to 250 N / mm ² . Here, in the coated body of the present invention, since the coating film formed on the surface of the metal substrate has a urethane bond and the Martens hardness of the coating film is 10 to 250 N / mm ² , It has a coating film with excellent film adhesion, processability and oil resistance. For this reason, the coated body of the present invention is useful for metal members for vehicles, specifically, engine blocks for vehicles such as automobiles, motorcycles and trucks.

  In the present invention, the Martens hardness is measured with a micro hardness tester (for example, SHIMADZU micro hardness tester DUH-211) using a 115 ° triangular pyramid indenter at a temperature of 20 ° C., 50% relative humidity, and a test force of 2 mN. Is the value to be

Coated article of the present invention, the Martens hardness of the coating film formed on the surface of the metal substrate, required to be in the range of 10~250N / mm ^2, in the range of 50~230N / mm ² A range of 100 to 230 N / mm ² is more preferable. When the Martens hardness of the coating film is less than 10 N / mm ² , the coating film becomes flexible and the coating film is easily damaged, and the oil resistance may be reduced. On the other hand, when the Martens hardness of the coating film exceeds 250 N / mm ² , the coating film is too hard, so that the processability is inferior, and the adhesion to the metal substrate is also reduced, and the coating film is cracked by impact. May occur.

  In the present invention, the metal substrate is not particularly limited, and the shape is, for example, a plate shape, a sheet shape, a foil shape, or the like. Moreover, as a metal which comprises this base material, steel, galvanized steel, stainless steel, magnesium alloy, aluminum, aluminum alloy etc. are mentioned, Among these, steel is preferable. Further, the metal substrate may be subjected to various surface treatments such as oxidation treatment. As an example, a base material obtained by subjecting aluminum to oxidation treatment by a method such as alumite treatment, phosphate treatment, chromate treatment, or non-chromate treatment can be used. The metal substrate includes various plastic substrates having a metal thin film on the surface (the shape thereof includes, for example, a casing and a film having a three-dimensional structure). For metal film formation, vapor deposition, sputtering, plating, or the like can be used. Examples of the metal thin film include metal thin films such as aluminum, tin, zinc, gold, silver, platinum, and nickel. As the plastic substrate, various known materials can be used. Specifically, ABS (acrylonitrile butadiene styrene copolymer), PC (polycarbonate), acrylic, PS (polystyrene), MS (copolymer of MMA and styrene). Polymer), PBT (polybutylene terephthalate), PPS (polyphenylene sulfide), PET (polyethylene terephthalate), TAC (triacetylcellulose), and polymer alloys thereof. Further, various primer treatments may be applied to the plastic substrate before forming the metal thin film on the plastic substrate.

  The coated body of the present invention comprises a metal substrate and a coating film formed on the surface of the metal substrate. For example, an active energy ray-curable coating containing a urethane (meth) acrylate oligomer is applied to the surface of the metal substrate. Then, it can be produced by forming a film by curing or the like by irradiation with active energy rays. The application method of the active energy ray-curable coating is not particularly limited, and is a known coating method such as spray coating, dipping, roll coating, die coating, air knife coating, blade coating, spin coating, reverse coating, gravure coating, and wire bar. In addition, known printing methods such as gravure printing, screen printing, and offset printing can be used. Moreover, it is preferable that the coating film formed is 20-100 micrometers in dry film thickness.

The active energy ray-curable coating is cured by a chemical reaction caused by irradiation with active energy rays (visible light, ultraviolet rays, electron beams, etc.). Here, as the active energy ray source, an ultraviolet ray source such as a mercury lamp, a metal halide lamp, a xenon lamp, an excimer laser, a dye laser, an LED lamp, an electron beam accelerator, or the like can be used. The irradiation energy amount (integrated light amount) of the active energy ray is preferably 200 to 2,000 mJ / cm ² .

  Moreover, in the coated body of this invention, the said coating film needs to be obtained with the active energy ray-curable coating material containing a urethane (meth) acrylate oligomer. Urethane (meth) acrylate oligomers have a urethane bond in the molecule, which means that there are crystal sites (hard segments) due to hydrogen bonds between urethane bonds in the coating film, and oil resistance is improved. . In addition, flexibility is exhibited by other non-crystalline parts (soft segments), and adhesion and workability are improved.

In the present invention, the active energy ray-curable coating material used for forming the coating film (hereinafter simply referred to as the coating composition of the present invention) needs to contain a urethane (meth) acrylate oligomer, but the coating film has a Martens hardness. From the viewpoint of adjusting to a range of 10 to 250 N / mm ² , the coating composition of the present invention is (A) a radical polymerizable oligomer, and the oligomer has a cured product with a Martens hardness of greater than 40 N / mm ^2. And (B) a urethane (meth) acrylate oligomer, wherein the oligomer cured product has a Martens hardness of 40 N / mm ² or less, (A) a radical polymerizable oligomer and (B) urethane (meth) The mass ratio (A / B) of the acrylate oligomer is preferably 85/15 to 15/85.

The (A) radical polymerizable oligomer is an oligomer having a cured product of the oligomer having a Martens hardness of greater than 40 N / mm ² . Here, the radical polymerizable oligomer is an oligomer having a functional group that is reactive with radical species generated by irradiation with active energy rays. By blending the above-mentioned (A) radical polymerizable oligomer, the coating film is likely to be dense, the oil resistance is improved, and the scratches are less likely to be scratched.

In the present invention, the Martens hardness is measured with a micro hardness tester (for example, SHIMADZU micro hardness tester DUH-211) using a 115 ° triangular pyramid indenter at a temperature of 20 ° C., 50% relative humidity, and a test force of 2 mN. Is the value to be Moreover, the cured product of the radically polymerizable oligomer (A) used for measuring the Martens hardness is prepared by mixing 10 parts by weight of a photopolymerization initiator with 100 parts by weight of the radically polymerizable oligomer (A). The mixture was applied on a degreased SPCC-SD (cold rolled steel sheet) so that the dry film thickness was 40 μm, and a mercury lamp (358 mW / cm ² ) was used, and 295 mJ / cm ² It is formed by irradiating the irradiation light quantity five times (integrated light quantity: 1,475 mJ / cm ² ). For measurement of the integrated light quantity, EYE UV METER UVPF-A1 (365 nm) manufactured by Iwasaki Electric Co., Ltd. can be used. Moreover, you may add the organic solvent whose boiling point is 80 degrees C or less which can be easily removed with a drying furnace, such as ethyl acetate, to the said mixture. The above (A) a radical polymerizable oligomer is required to be Martens hardness of the cured product of the oligomer is greater than 40N / mm ^2, is preferably 200 N / mm ² or less.

  The (A) radical polymerizable oligomer is not particularly limited, but preferably has a number average molecular weight of 500 to 10,000, and a number average molecular weight of 500 to 500 from the viewpoint of coating film properties such as oil resistance and scratch resistance. More preferably, it is in the range of 3,000. The number average molecular weight is a polystyrene equivalent number average molecular weight measured by gel permeation chromatography.

The radically polymerizable oligomer (A) is not particularly limited as long as it has one or more functional groups that are reactive when irradiated with active energy rays, but from the viewpoint of coating processability and oil resistance, the number of functional groups Is preferably in the range of 2-6. When the number of functional groups is less than 2, the crosslink density of the film is lowered and the oil resistance tends to be lowered. On the other hand, when it exceeds 6, the crosslink density becomes too high, and the workability may be lowered. Here, as a functional group which shows reactivity at the time of active energy ray irradiation, an acryloyloxy group (CH ₂ ═CHCOO—) or a methacryloyloxy group (CH ₂ ═C (CH ₃ ) COO—) is preferable.

  In the coating composition of this invention, it is preferable that content of the said (A) radically polymerizable oligomer is 5-50 mass%.

  In the coating composition of the present invention, the mass ratio (A / B) of the (A) radical polymerizable oligomer and the (B) urethane (meth) acrylate oligomer described later is from the viewpoint of the processability and oil resistance of the coating film. It is preferably 85/15 to 15/85, and more preferably 85/15 to 40/60 from the viewpoint of further improving the workability and oil resistance of the coating film. When the ratio of (A) radical polymerizable oligomer to the total of (A) radical polymerizable oligomer and (B) urethane (meth) acrylate oligomer exceeds 85% by mass, the processability of the coating film decreases, (A) If the ratio of a radically polymerizable oligomer is less than 15 mass%, oil resistance will fall. In the case where (B) urethane (meth) acrylate oligomer is not used and only (A) radical polymerizable oligomer is used (that is, mass ratio (A / B) is 100/0), Since the internal stress of the film increases with irradiation, adhesion to the metal substrate and workability are reduced.

  Examples of the (A) radical polymerizable oligomer include ester (meth) acrylate oligomers, epoxy (meth) acrylate oligomers, and urethane (meth) acrylate oligomers. Moreover, the said (A) radically polymerizable oligomer may be used individually by 1 type, and may use 2 or more types together.

  The ester (meth) acrylate oligomer is, for example, an ester (meth) acrylate oligomer obtained by reacting a hydroxyl group-containing polyester synthesized from a polybasic acid or acid anhydride thereof and a polyhydric alcohol with (meth) acrylic acid. Is mentioned. Here, as the polybasic acid, phthalic acid, succinic acid, adipic acid, glutaric acid, sebacic acid, isosebacic acid, tetrahydrophthalic acid, hexahydrophthalic acid, dimer acid, trimellitic acid, pyromellitic acid, pimelic acid, Examples include azelaic acid. Examples of the polyhydric alcohol include 1,6-hexanediol, diethylene glycol, 1,2-propylene glycol, 1,3-butylene glycol, neopentyl glycol, dipropylene glycol, polyethylene glycol, and polypropylene glycol.

  Examples of the epoxy-based (meth) acrylate oligomer include a (meth) acrylic acid-modified epoxy resin obtained by adding (meth) acrylic acid to an epoxy resin (preferably an alicyclic epoxy resin). Here, the epoxy resin subjected to modification is obtained, for example, by reacting bisphenol A, bisphenol F, bisphenol S, or phenol borak with epichlorohydrin. The alicyclic epoxy resin subjected to modification can be obtained, for example, by reacting cyclopentadiene oxide or cyclohexene oxide with epichlorohydrin.

  Examples of the urethane (meth) acrylate oligomer include a urethane (meth) acrylate oligomer obtained by reacting an isocyanate compound, a polyol compound, and a hydroxy group-containing (meth) acrylate compound. Here, examples of the isocyanate compound include tolylene diisocyanate, xylylene diisocyanate, hexamethylene diisocyanate, and isophorone diisocyanate. Examples of the polyol compound include adducts of hydrogenated bisphenol A and ethylene oxide, hydrogenated bisphenol A, neopentyl glycol, 1,6-hexanediol, trimethylolpropane, and the like. Examples of the hydroxy group-containing (meth) acrylate compound include hydroxyl-containing alkyl esters of (meth) acrylic acid such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, and 2-hydroxybutyl (meth) acrylate. Can be mentioned.

The (B) urethane (meth) acrylate oligomer is an oligomer having a cured product of the oligomer having a Martens hardness of 40 N / mm ² or less. Since the (B) urethane (meth) acrylate oligomer has a Martens hardness of 40 N / mm ² or less of the cured product of the oligomer, the adhesion to metal and workability can be improved. In addition, it is preferable that it is the range whose Martens hardness is 0.2-40N / mm < ² >, and, as for the hardened | cured material of (B) urethane (meth) acrylate oligomer, it is more preferable that it is the range of 0.3-10 N / mm < ² >. preferable. When the Martens hardness is less than 0.2 N / mm ² , the film becomes too flexible, the surface of the coating film is easily damaged, and the coating film performance such as oil resistance may be deteriorated.

In the present invention, the Martens hardness is measured with a micro hardness tester (for example, SHIMADZU micro hardness tester DUH-211) using a 115 ° triangular pyramid indenter at a temperature of 20 ° C., 50% relative humidity, and a test force of 2 mN. Is the value to be Moreover, the hardened | cured material of (B) urethane (meth) acrylate oligomer used for the measurement of Martens hardness mix | blends 10 mass parts of photoinitiators with respect to 100 mass parts of (B) urethane (meth) acrylate oligomers. The mixture was prepared and applied on SPCC-SD (cold rolled steel plate) subjected to degreasing treatment so that the dry film thickness was 40 μm, and using a mercury lamp (358 mW / cm ² ), 295 mJ It is formed by irradiating the irradiation light quantity of / cm ² five times (integrated light quantity: 1,475 mJ / cm ² ). For measurement of the integrated light quantity, EYE UV METER UVPF-A1 (365 nm) manufactured by Iwasaki Electric Co., Ltd. can be used. Moreover, you may add the organic solvent whose boiling point is 80 degrees C or less which can be easily removed with a drying furnace, such as ethyl acetate, to the said mixture.

  The (B) urethane (meth) acrylate oligomer preferably has a number average molecular weight in the range of 800 to 15,000, and more preferably in the range of 1,000 to 10,000. If the number average molecular weight is less than 800, the flexibility of the film tends to be lowered, so that adhesion to metal and workability may be lowered. On the other hand, if the number average molecular weight is more than 15,000, the film becomes too flexible, and The scratch resistance and oil resistance of the film may be reduced. The number average molecular weight is a polystyrene equivalent number average molecular weight measured by gel permeation chromatography.

The (B) urethane (meth) acrylate oligomer has an acryloyloxy group (CH ₂ ═CHCOO—) or a methacryloyloxy group (CH ₂ ═C (CH ₃ ) COO— as a functional group that exhibits reactivity when irradiated with active energy rays. ), But the number of functional groups is preferably in the range of 2-6. If the number of functional groups is less than 2, the curability tends to decrease and the oil resistance of the coating film tends to decrease. On the other hand, if it exceeds 6, the flexibility of the film tends to decrease, so that the adhesion to metal and workability are reduced. May decrease.

  Although the (B) urethane (meth) acrylate oligomer has a urethane bond in the molecule, a crystal part (hard segment) due to a hydrogen bond between the urethane bonds is present, thereby improving oil resistance. In addition, flexibility is exhibited by other non-crystalline parts (soft segments), and adhesion and workability are improved. As described above, the urethane (meth) acrylate oligomer is obtained, for example, by reacting an isocyanate compound, a polyol compound, and a hydroxy group-containing (meth) acrylate compound.

  In the coating composition of this invention, it is preferable that content of the said (B) urethane (meth) acrylate oligomer is 5-70 mass%, and it is more preferable that it is 5-40 mass%. (B) If the content of the urethane (meth) acrylate oligomer is less than 5% by mass, the internal stress of the film increases with the irradiation of the active energy ray, so that the adhesion to the metal substrate and the workability may decrease. is there. On the other hand, if it exceeds 70% by mass, the coating film properties such as water resistance, moisture resistance, oil resistance and the like are lowered, and the film becomes too flexible and the film is easily damaged. Moreover, the said (B) urethane (meth) acrylate oligomer may be used individually by 1 type, and may use 2 or more types together.

  The coating composition of the present invention preferably further contains (C) a radical polymerizable acid monomer, and the content of the (C) radical polymerizable acid monomer is preferably 0.5 to 10.0% by mass. . (C) Adhesion to a metal substrate can be improved by using a radical polymerizable acid monomer. However, if the content of the (C) radical polymerizable acid monomer is less than 0.5% by mass, Adhesive improvement effect is insufficient. Moreover, when content of (C) radically polymerizable acid monomer exceeds 10.0 mass%, coating-film physical properties, such as moisture resistance, will fall.

The (C) radical polymerizable acid monomer is a monomer having a functional group and an acid group that are reactive when irradiated with active energy rays. Here, as a functional group which shows reactivity at the time of active energy ray irradiation, an acryloyloxy group (CH ₂ ═CHCOO—) or a methacryloyloxy group (CH ₂ ═C (CH ₃ ) COO—) is preferable. Examples of the acid group include a sulfonic acid group, a phosphoric acid group, and a carboxylic acid group.

  The (C) radical polymerizable acid monomer preferably has an acid value of 5 to 800 mgKOH / g, and more preferably 50 to 400 mgKOH / g. If the acid value is less than 5 mgKOH / g, the adhesion to the metal may be insufficient. On the other hand, if it exceeds 800 mgKOH / g, the coating film will easily retain moisture, so the metal will be easily rusted and moisture resistant. The physical properties of the coating film may deteriorate. The acid value is the number of mg of potassium hydroxide required to neutralize 1 g of the sample.

  Examples of the (C) radical polymerizable acid monomer include phosphoric acid group-containing (meth) acrylates, carboxylic acid group-containing (meth) acrylates, sulfonic acid group-containing (meth) acrylates, etc. A meth) acrylate is preferred. Specific examples of the phosphoric acid group-containing (meth) acrylate include, for example, ethylene oxide-modified phosphoric acid (meth) acrylate, ethylene oxide-modified phosphoric acid di (meth) acrylate, dimethyl phosphate ethyl acrylate, diethyl phosphate ethyl acrylate, and 2-acryloyl. Examples include oxyethyl phosphoric acid, bisacryloyloxyethyl phosphate, trisacryloyloxyethyl phosphate, 2-methacryloyloxyethyl phosphoric acid, bismethacryloyloxyethyl phosphate, and ethoxylated tri (meth) acrylate. Specific examples of the carboxylic acid group-containing (meth) acrylate include, for example, pivalate ester neopentyl glycol di (meth) acrylate, hydroxypivalate neopentyl glycol di (meth) acrylate, caprolactone-modified hydroxypivalate neo Pentyl glycol di or mono (meth) acrylate, hydroxypivalic acid trimethylolpropane tri (meth) acrylate, 2-acryloyloxyethyl succinic acid, 2-acryloyloxyethyl phthalic acid, 2-acryloyl hexahydroethyl succinic acid, ω-carboxy -Polycaprolactone monoacrylate, 2-methacryloyloxyethyl succinic acid, 2-methacryloyloxyethyl phthalic acid, 2-methacryloyloxyethyl succinic acid, 2-methacryloyl Xylethylphthalic acid, β-carboxyethyl (meth) acrylate, 2-acryloyloxyethyl hexahydrophthalic acid, monohydroxyethyl (meth) acrylate phthalate, monohydroxyethyl (meth) acrylate 2-hydroxypropylphthalate, 2- Examples thereof include monohydroxyethyl (meth) acrylate of hydroxyethyl phthalate and neopentyl glycol (meth) acrylic acid benzoate. Specific examples of the sulfonic acid group-containing (meth) acrylate include 2-sulfoethyl (meth) acrylate and 2-acrylamido-2-methylpropanesulfonic acid. Further, CD9050, CD9051, CD9053 manufactured by Sartomer, HOA-MS (N) manufactured by Kyoeisha Chemical Co., Ltd., and β-CEA manufactured by Daicel Ornex Co., Ltd. are commercially available. The (C) radical polymerizable acid monomer may be used alone or in combination of two or more.

  The coating composition of the present invention preferably further comprises (D) oxide fine particles. By adding oxide fine particles, the oil resistance tends to be remarkably improved. The reason why the oil resistance is remarkably improved is not clear, but the addition of fine oxide particles has reduced the internal stress of the film and made it more firmly attached to the metal. A factor is that the oil component is prevented from entering the inside of the membrane by being dispersed in the membrane.

  Examples of the oxide fine particles (D) include those having an average particle diameter of 1 nm to 100 nm and high transparency, such as silica fine particles such as dry silica and wet silica, titanium oxide, zirconium oxide, zinc oxide, Examples include tin oxide, cerium oxide, antimony oxide, indium tin mixed oxide and antimony tin mixed oxide, and metal oxide fine particles such as aluminum oxide. Among these, aluminum oxide fine particles are more preferable.

  The (D) oxide fine particles preferably have an average particle diameter of 10 to 50 nm from the viewpoints of transparency, curability and oil resistance. When the particle diameter of the particles increases, the transmittance of light used for curing decreases, which adversely affects the curability of the film. Further, since the surface has irregularities, the gloss of the film tends to decrease. The average particle diameter of (D) oxide fine particles can be measured by a dynamic light scattering method using the speed of Brownian motion of the particles.

  In the coating composition of the present invention, the content of the (D) oxide fine particles is preferably 1.0 to 6.0% by mass. When the content of the (D) oxide fine particles is less than 1.0% by mass, the oil component may enter the inside of the membrane and the oil resistance may be lowered. On the other hand, when the content exceeds 6.0% by mass, In some cases, the film properties such as oil resistance are lowered due to the decrease in curability, and in addition, the gloss of the film may be decreased due to unevenness on the surface of the film. In addition, the said (D) oxide fine particle may be used individually by 1 type, and may use 2 or more types together.

  Similarly, in the coated body of the present invention, the coating film preferably includes (D) oxide fine particles having an average particle diameter in the range of 1 nm to 100 nm, and (D) the average particle diameter of the oxide fine particles is More preferably, it is the range of 10-50 nm. In addition, it is preferable that it is 1.0-20.0 mass%, and, as for content of (D) oxide microparticles | fine-particles in a coating film, it is more preferable that it is 1.0-6.0 mass%.

  The coating composition of the present invention may further contain (E) at least one pigment selected from the group consisting of a color pigment, an extender pigment, and a rust preventive pigment. Here, the pigment is generally classified into an inorganic pigment and an organic pigment, and the inorganic pigment may include a part of the inorganic oxide. However, the (D) oxide fine particles described above have an average particle diameter of 1 nm to 1 nm. In contrast to the high transparency in the range of 100 nm, the inorganic oxide belonging to the inorganic pigment usually has an average particle diameter in the range of more than 100 nm and 10 μm or less. It is a different component. The average particle diameter of the inorganic oxide belonging to the inorganic pigment here can be measured by a laser diffraction / scattering method. Examples of the color pigment include white pigments (titanium oxide, etc.), black pigments (carbon black, acetylene black, lamp black, bone black, graphite, iron black, aniline black, etc.), yellow pigments (yellow iron oxide, titanium yellow, monoazo). Yellow, condensed azo yellow, azomethine yellow, bismuth vanadate, benzimidazolone, isoindolinone, isoindoline, quinophthalone, benzidine yellow, permanent yellow, etc., orange pigment (permanent orange, etc.), red pigment (red iron oxide, naphthol) AS azo red, ansanthrone, anthraquinonyl red, perylene maroon, quinacridone red pigment, diketopyrrolopyrrole, watching red, permanent red, etc., purple pigment (cobalt purple, quinacridone violet , Dioxazine violet and the like), blue pigment (cobalt blue, phthalocyanine blue, threne blue and the like), can be given a green pigment (phthalocyanine green) and the like. In addition, these color pigments may be used individually by 1 type, and may use 2 or more types together. Examples of extender pigments include talc, clay, silica, mica, alumina, calcium carbonate, barium sulfate, and glass beads. In addition, these extender pigments may be used individually by 1 type, and may use 2 or more types together. In addition, as rust preventive pigments, zinc oxide, zinc phosphate, phosphorous zinc silicate, aluminum phosphate, aluminum zinc phosphate, calcium zinc phosphate, zinc phosphite, calcium phosphite, aluminum phosphite, cyanamide zinc calcium, Examples thereof include zinc-treated aluminum polyphosphate, aluminum dipolyphosphate, zinc calcium molybdate, zinc molybdate, zinc phosphomolybdate, and aluminum phosphomolybdate. In addition, these rust preventive pigments may be used individually by 1 type, and may use 2 or more types together. In the coating composition of the present invention, the content of the pigment (E) is preferably 0.1 to 45.0% by mass, and more preferably 10 to 45.0% by mass.

  Similarly, in the coated body of the present invention, the coating film may contain (E) at least one pigment selected from the group consisting of a color pigment, an extender pigment, and a rust preventive pigment. (E) The pigment content is preferably 0.1 to 45.0 mass%, more preferably 10 to 45.0 mass%.

  The coating composition of this invention can contain a photoinitiator as needed. Examples of the photopolymerization initiator include α-aminoketone compounds, benzophenone compounds, acetophenone compounds, thioxanthone compounds, phosphine oxide compounds, and the like. It is preferable that the absorption wavelengths of the photopolymerization initiator overlap as much as possible. Furthermore, in order to accelerate the initiation reaction of the photopolymerization initiator, an auxiliary such as a photosensitizer can be used in combination.

  Specific examples of the photopolymerization initiator include 2,2-dimethoxy-1,2-diphenylethane-1-one, 1-hydroxy-cyclohexyl-phenyl-ketone, and 2-hydroxy-2-methyl-1-phenylpropane. -1-one, benzophenone, 1- [4- (2-hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl-1-propan-1-one, 2-hydroxy-1- {4- [4- (2-Hydroxy-2-methylpropionyl) -benzyl] -phenyl} -2-methyl-propan-1-one, phenylglyoxylic acid methyl ester, 2-methyl-1- [4- (methylthio) phenyl]- 2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone, 2-di Tilamino-2- (4-methyl-benzyl) -1- (4-morpholin-4-yl-phenyl) -butan-1-one, bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide, Bis (2,6-dimethoxybenzoyl) -2,4,4-trimethyl-pentylphosphine oxide, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, 1,2-octanedione, 1- [4- (Phenylthio) -2- (O-benzoyloxime)], ethanone, 1- [9-ethyl-6- (2-methylbenzoyl) -9H-carbazol-3-yl]-, 1- (O-acetyloxime) 2,4-diethylthioxanthone, 2-isopropylthioxanthone, 2-chlorothioxanthone and the like. Among these, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide is preferable from the viewpoint of the curability of the paint. In addition, these photoinitiators may be used individually by 1 type, and may be used in combination of 2 or more type.

  Commercially available products of the above photopolymerization initiator include Irgacure 184, 369, 651, 500 (trade name, manufactured by Ciba Specialty Chemicals); Lucirin LR8728, Irgacure 819, Lucirin TPO (trade name, manufactured by BASF); Darocure 1116, 1173 (and above, (Trade name made by company); Ubekrill P36 (trade name made by UCB) and the like.

  In the coating composition of this invention, it is preferable that content of the said photoinitiator is 2.0-10.0 mass%, for example.

The coating composition of the present invention includes, as other components, a radical polymerizable monofunctional monomer (such as phenoxyethyl acrylate), a pigment dispersant, a surface conditioner, a thickener, as long as the object of the present invention is not impaired. Various additives such as an antifoaming agent and a leveling agent can be blended, and further, an ultraviolet absorber and an antioxidant can be blended for the purpose of improving the weather resistance.
The radically polymerizable monofunctional monomer is a monomer having one functional group that exhibits reactivity when irradiated with active energy rays but not an acid group. The viscosity adjustment of the coating composition and the solubility of the radically polymerizable oligomer are as follows. You may mix | blend in order to improve the adhesiveness with respect to a base material, the workability of a coating film, and also the dispersibility of a pigment, and it is preferable that the compounding quantity is 20-60 mass% in a coating composition. Among these, phenoxyethyl acrylate is preferable from the viewpoints of solubility of the above-mentioned radical polymerizable oligomer, adhesion to the substrate, processability of the coating film, and dispersibility of the pigment.
Although it is preferable that the coating composition of this invention does not contain an organic solvent, you may mix | blend an organic solvent as needed.

  The coating composition of the present invention can be prepared by mixing a urethane (meth) acrylate oligomer and various components appropriately selected as necessary.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples.

(Compositions 1-9 and 12-14)
According to the formulation shown in Tables 1 to 3, the respective components were mixed and each composition was prepared by stirring with a disper for about 10 minutes.

(Composition 10)
In accordance with the formulation shown in Table 2, a colored pigment and a rust preventive pigment are added to a solution prepared by dissolving TEGO DISPERSE685 in light acrylate PO-A, and the coarse kneaded product is stirred for about 10 minutes using a disper. Produced. Next, the kneaded product is prepared by kneading the coarse kneaded product with titania beads using a paint shaker, and the kneaded product includes an oligomer, an acid monomer, a photopolymerization initiator, which are other components, The surface conditioning agent was mixed and the composition 10 was prepared by stirring with a disper for about 10 minutes.

(Composition 11)
In accordance with the formulation shown in Table 2, a colored pigment was added to a solution obtained by dissolving TEGO DISPERSE685 in light acrylate PO-A, and the mixture was stirred for about 10 minutes to prepare a coarse kneaded product. Next, the coarse kneaded product is kneaded with a tit shaker bead using a paint shaker to produce a kneaded product, and the kneaded product is composed of other components such as oligomer, acid monomer, extender pigment, and photopolymerization. The initiator and the surface conditioner were mixed and the composition 11 was prepared by stirring with a disper for about 10 minutes.

Details of the materials described in Tables 1 to 3 are described below.
EBECRYL 812; ester acrylate oligomer (manufactured by Marcels hardness 171.1 N / mm ² , number of functional groups 4, polystyrene equivalent number average molecular weight 800)
EBECRYL 3500: Epoxy acrylate oligomer (manufactured by Marcels hardness 127.2 N / mm ² , number of functional groups 2, polystyrene conversion number average molecular weight 850) manufactured by Daicel-Cytec Co., Ltd.
Urethane (meth) acrylate oligomer 1; CN9004 manufactured by SARTOMER (hardened Martens hardness 0.77 N / mm ² , polystyrene equivalent number average molecular weight 9600, functional group number 2)
Urethane (meth) acrylate oligomer 2; CN966J75 manufactured by SARTOMER (hardened product Martens hardness 0.36 N / mm ² , polystyrene-equivalent number average molecular weight 6900, functional group number 2)
Urethane (meth) acrylate oligomer 3; CN991 made by SARTOMER (hardened product Martens hardness 5.09 N / mm ² , polystyrene-equivalent number average molecular weight 1200, functional group number 2)
Acid monomer 1; Kyoeisha Chemical Co., Ltd. light ester P-1M (2-methacryloyloxyethyl acid phosphate)
Acid monomer 2; Kyoeisha Chemical Co., Ltd. light acrylate P-1A (N) (2-acryloyloxyethyl acid phosphate)
NANOBYK-3602: Dispersion of aluminum oxide particles (oxide fine particles) manufactured by Big Chemie (content of aluminum oxide particles 30% by mass, average particle size: 40 nm)
Colored pigment; Eponic Degussa Printex V carbon black (average primary particle size 25 nm)
Extender pigment; EMB-20 (glass beads) manufactured by Mako Co., Ltd. (particle size range: 2 to 20 μm)
Anti-corrosive pigment: K-WHITE # 105 (aluminum phosphate) manufactured by Teika Co., Ltd. (average particle size 1.6 μm)
Light acrylate PO-A; phenoxyethyl acrylate TEGO DISPERSE 685 manufactured by Kyoeisha Chemical; modified polyester-based dispersant Darocur 1173 manufactured by TEGO; polymerization initiator manufactured by BASF, 2-hydroxy-2-methyl-1-phenyl-propan-1-one Lucirin TPO; BASF polymerization initiator, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide surface conditioner; BYK-UV3500 (polyether modified polydimethylsiloxane having an acrylic group) manufactured by BYK Chemie

<Measuring method of Martens hardness of cured product of component (A)>
(A) 5 parts by mass of photopolymerization initiators Darocur 1173 and Lucirin TPO are blended with 100 parts by mass of radically polymerizable oligomer, respectively, and then 50 parts by mass of ethyl acetate (solvent) is prepared for dilution to prepare a clear solution. did. The clear solution was applied on a degreased SPCC-SD (cold rolled steel sheet) so that the dry film thickness was 40 μm, and the solvent was dried in a drying furnace at 80 ° C. for 20 minutes, A cured product (coating film) was formed by irradiating the irradiation light amount of 295 mJ / cm ² 5 times using a mercury lamp (358 mW / cm ² ) (integrated light amount: 1,475 mJ / cm ² ). Note that EYE UV METER UVPF-A1 (365 nm) manufactured by Iwasaki Electric Co., Ltd. was used for measurement of the integrated light quantity. Next, using a SHIMADZU dynamic microhardness meter (indenter 115 ° triangular pyramid) DUH-211, the Martens hardness of the obtained coating film was measured under the conditions of a temperature of 20 ° C., 50% relative humidity and a test force of 2 mN. It was measured.

<Measurement method of Martens hardness of cured product of component (B)>
A clear solution was prepared by blending 5 parts by mass of photopolymerization initiators Darocur 1173 and Lucirin TPO with 100 parts by mass of urethane (meth) acrylate oligomer, and then blending 50 parts by mass of ethyl acetate (solvent) for dilution. . The clear solution was applied on a degreased SPCC-SD (cold rolled steel sheet) so that the dry film thickness was 40 μm, and the solvent was dried in a drying furnace at 80 ° C. for 20 minutes, A cured product (coating film) was formed by irradiating the irradiation light amount of 295 mJ / cm ² 5 times using a mercury lamp (358 mW / cm ² ) (integrated light amount: 1,475 mJ / cm ² ). Note that EYE UV METER UVPF-A1 (365 nm) manufactured by Iwasaki Electric Co., Ltd. was used for measurement of the integrated light quantity. Next, using a SHIMADZU dynamic microhardness meter (indenter 115 ° triangular pyramid) DUH-211, the Martens hardness of the obtained coating film was measured under the conditions of a temperature of 20 ° C., 50% relative humidity and a test force of 2 mN. It was measured.

<Preparation of test plate>
The above compositions 1 to 14 were applied onto the surface of a degreased SPCC-SD (cold rolled steel sheet) or PB-3100 (phosphate treated steel sheet) so as to have a dry film thickness of 40 μm. Using a lamp (286 mW / cm ² ), a coating film was formed by irradiating an irradiation light amount of 295 mJ / cm ² three times (integrated light amount: 885 mJ / cm ² ) to prepare a test plate. Note that EYE UV METER UVPF-A1 (365 nm) manufactured by Iwasaki Electric Co., Ltd. was used for measurement of the integrated light quantity.

<Evaluation of coating film>
While measuring the Martens hardness of the obtained coating film, evaluation of adhesiveness, workability, oil resistance, and moisture resistance was performed as follows. The results are shown in Tables 4-6.

<Adhesiveness>
According to JIS K5600-5-6 (cross-cut method), 100 squares with an interval of 2 mm were prepared, and a cellophane tape peeling test was performed, and evaluation was performed based on the residual rate of the squares.

<Processability>
The test plate cut to 1.0 cm × 7.5 cm was bent until both ends were in contact with each other, and cracking and peeling of the coating film at the bent portion were visually evaluated.
A: Even if the bent part is sharply scraped with a nail, there is no cracking or peeling of the coating film.
○: There is no cracking and peeling of the coating film, but the coating film peels slightly when the bent part is sharply scraped with a nail.
Δ: Slight cracking and peeling of coating film.
X: There is a crack and peeling of the coating film on the entire surface of the bent portion.

<Oil resistance>
The test plate was immersed in brake oil kept at 50 ° C. for 24 hours, and the state of the subsequent coating film was evaluated by visual observation and finger touch.
A: Gloss and hardness of the coating film are not changed at all.
○: The change in gloss by visual observation cannot be confirmed, but if the coating film is shaved with a nail, it is slightly damaged.
Δ: The coating film is slightly softened.
X: The coating film was softened and peeled from the substrate.

<Moisture resistance>
The test method according to JIS K5600-7-2.5 is performed for 48 hours, and then the above-mentioned adhesion test is performed, and the moisture resistance is evaluated according to the following criteria based on the appearance and adhesion evaluation results of the coating film. did.
○: There is no abnormality in the appearance of the coating film, and the residual rate of the squares in the adhesion test is 100%.
Δ: A slight decrease in gloss is observed in the appearance of the coating film, but the residual rate of the squares in the adhesion test is 100%.
X: Remarkable abnormalities such as swelling and cracking are observed in the appearance of the coating film, or peeling of the cells is observed in the adhesion test.

<Martens hardness of coating film>
The Martens hardness of the obtained coating film was measured under the conditions of a temperature of 20 ° C., 50% relative humidity and a test force of 2 mN using a SHIMADZU dynamic ultra-micro hardness meter (indenter 115 ° triangular pyramid) DUH-211.

From the results of Tables 4 and 5, it can be seen that the coated bodies of Examples 1 to 12 have good adhesion to metal and excellent workability and oil resistance. On the other hand, in Comparative Example 1, although the Martens hardness of the coating film is in the range of 10 to 250 N / mm ² , the paint used for forming the coating film does not contain a urethane (meth) acrylate oligomer. Adhesiveness, workability and oil resistance to water were not sufficient. In Comparative Example 2, a urethane (meth) acrylate oligomer was used for the paint, but the coating film had a Martens hardness of less than 10 N / mm ² , and therefore the results showed low oil resistance and low moisture resistance. In Comparative Example 3, the Martens hardness of the coating film exceeded 250 N / mm ² , and adhesion to metal, workability, and oil resistance were not sufficient.

Claims (5)

A coated body having a metal substrate and a coating film formed on the surface of the metal substrate, wherein the coating film is obtained by an active energy ray-curable coating material containing a urethane (meth) acrylate oligomer, and the activity The energy ray curable paint is (A) a radical polymerizable oligomer, and a cured product of the oligomer has an Martens hardness of greater than 40 N / mm ² and (B) a urethane (meth) acrylate oligomer, The oligomer cured product has a Martens hardness of 40 N / mm ² or less, and the mass ratio (A / B) of (A) radical polymerizable oligomer and (B) urethane (meth) acrylate oligomer is 85/15 to A coated body characterized by being 15/85 and having a Martens hardness of the coating film of 10 to 250 N / mm ² . The coated body according to claim 1, wherein the coating film further contains at least one pigment selected from the group consisting of a color pigment, an extender pigment, and a rust preventive pigment. The (A) radical polymerizable oligomer is at least one oligomer selected from the group consisting of an ester (meth) acrylate oligomer, an epoxy (meth) acrylate oligomer, and a urethane (meth) acrylate oligomer. The coated body according to claim 1 or 2 . The number average molecular weight of the (B) urethane (meth) acrylate oligomer is in the range of 800 to 15,000, and the number of functional groups is in the range of 2 to 6 , wherein any one of claims 1 to 3 is characterized. Painted body according to item . The coated body according to claim 1, wherein the coating film further contains oxide fine particles having an average particle diameter of 1 nm to 100 nm.