JP2005125208A - Coating method by uv light-curable coating composition, surface coated resin film and surface coated paper - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coating method by a UV light-curable coating composition having excellent adhesion property, injuring-proof property, contamination-proof property, alkali-resistance property, acid-resistance property, hot water-resistance property and weather-resistance property, and a surface coated resin film and paper obtained by using this. <P>SOLUTION: In the coating method by the UV light-curable coated composition, a curing method of the UV light-curable coated composition comprises a step (1) for coating the UV light-curable coating composition and a step (2) for irradiating with an electro-magnetic wave. The UV light-curable coating composition contains a UV light absorbent having an absorption area at a wavelength of 300-400 nm. The above step (2) comprises a step (2-1) for irradiating with the electro-magnetic wave in which a relative output ratio of wavelength area of 400-410 nm/wavelength area of 250-260 nm is 1.1 or more; and a step (2-2) for irradiating with the electro-magnetic wave in which a relative output ratio of wavelength area of 400-410 nm/wavelength area of 250-260 nm is 0.7 or less. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

The present invention relates to a coating method using a UV-curable coating composition, a surface-coated resin film, and a surface-coated paper.

Conventionally, in order to improve the surface characteristics of plastic materials and the like, a photocurable coating is formed on the surface, but the photocurable coating is generally light transmissive and does not have ultraviolet blocking properties. Therefore, in the long term, the coating film and the like are deteriorated by ultraviolet rays entering from the outside, and problems such as discoloration, cracks, and peeling of the coating film are likely to occur. For this reason, various methods for forming a photocurable coating film containing an ultraviolet absorber have been proposed.

Patent Documents 1 and 2 disclose a method for forming a coating film in which an ultraviolet absorber is blended with a specific photopolymerizable composition and ultraviolet rays are irradiated in one step. Patent Document 3 discloses a method of irradiating in one step so that the total amount of irradiated light of a specific wavelength falls within a certain range as a method of curing an ultraviolet curable composition having a specific composition including an ultraviolet absorber.

Patent Document 4 discloses a curing method in which a photocurable resin composition containing an ultraviolet absorber is irradiated with light of a specific emission spectrum in a single step. Patent Document 5 discloses a method of heating after irradiating ultraviolet rays as a method of curing an ultraviolet curable paint containing a specific ultraviolet absorber, a hindered amine antioxidant, and a thermosetting agent.

However, these methods have a problem that the weather resistance of the formed coating film is insufficient. In addition, a large amount of energy is required for curing the coating film, and there are problems such as difficulty in coating a resin film or paper with low heat resistance, and the method cannot be used practically.

Patent Documents 6 to 9 disclose a method of irradiating light beams having different specific wavelengths in two stages. However, these are methods of curing a concealable photocurable coating composition containing a colorant without any abnormalities in the coating film such as Chijimi, and suggest a method of curing a photocurable coating composition containing an ultraviolet absorber. There is no description.

JP-A-2-163134 JP-A-6-142611 Japanese Patent Laid-Open No. 4-18430 Japanese Patent Laid-Open No. 5-76837 Japanese Unexamined Patent Publication No. 1-111169 Japanese Patent Publication No.54-1996 Japanese Patent Publication No.54-19897 Japanese Patent Publication No.55-94 Japanese Patent Publication No.55-28741

In view of the above situation, the present invention provides a coating method using an ultraviolet curable coating composition excellent in adhesion, scratch resistance, contamination resistance, alkali resistance, acid resistance, hot water resistance, and weather resistance, and by using the same. The object is to provide a surface-coated resin film and paper to be obtained.

The present invention is a coating method using an ultraviolet curable coating composition comprising a step (1) of coating an ultraviolet curable coating composition and a step (2) of irradiating electromagnetic waves, wherein the ultraviolet curable coating composition comprises: It contains an ultraviolet absorber having an absorption region at a wavelength of 300 to 400 nm, and the step (2) irradiates an electromagnetic wave having a relative output ratio of 1.1 or more in the wavelength region of 400 to 410 nm / wavelength region of 250 to 260 nm. And a step (2-2) of irradiating an electromagnetic wave having a relative output ratio in the wavelength range of 400 to 410 nm / wavelength range of 250 to 260 nm of 0.7 or less. It is the coating method by the ultraviolet curable coating composition.
The ultraviolet curable coating composition is preferably an ultraviolet curable clear coating composition.

The present invention is a surface-coated resin film obtained by applying a coating method using the ultraviolet curable coating composition on a resin film.
The present invention is also a surface-coated paper obtained by applying a coating method using the above-described ultraviolet curable coating composition on paper.
Hereinafter, the present invention will be described in detail.

The coating method using the ultraviolet curable coating composition of the present invention is a method comprising a step (1) of coating an ultraviolet curable coating composition and a step (2) of irradiating electromagnetic waves, and by using this, weather resistance is achieved. It is possible to obtain a coating film that is excellent in adhesion, scratch resistance, stain resistance, alkali resistance, acid resistance, warm water resistance, and the like.

A feature of the present invention is that an ultraviolet curable coating composition containing an ultraviolet absorber having an absorption region at a wavelength of 300 to 400 nm is applied, and then applied to the coating film formed by coating. A step (2-1) of irradiating an electromagnetic wave having a relative output ratio of 260 nm or more at a wavelength of 260 nm and a step of irradiating an electromagnetic wave having a relative output ratio of a wavelength region of 400 to 410 nm / wavelength region of 250 to 260 nm of 0.7 or less. (2-2) is performed.

Since the present invention irradiates a coating film formed from a composition containing an ultraviolet absorber having an absorption region at a specific wavelength with an electromagnetic wave having a specific relative output ratio as described above, the weather resistance In addition, a coating film having excellent adhesion, scratch resistance, stain resistance, alkali resistance, acid resistance, and hot water resistance can be obtained. Furthermore, since this invention is a method of hardening by the said process (2-1) and (2-2), the lower layer part and surface layer part of a coating film are equalized by irradiating less energy than the conventional hardening method. It is a method that can be cured, and is a preferable method from the economical aspect.

In the coating method using the ultraviolet curable coating composition of the present invention, the first step is absorption at a wavelength of 300 to 400 nm (hereinafter simply referred to as “300 nm” when referred to as “wavelength 300 nm”). It is a step (step (1)) of applying an ultraviolet curable coating composition containing an ultraviolet absorber having a region. The sunlight that reaches the ground and promotes the deterioration of the coating is 300 to 400 nm. However, in the present invention, since the ultraviolet curable coating composition containing the ultraviolet absorber is used, Deterioration of the film can be prevented.

The ultraviolet absorber contained in the ultraviolet curable coating composition is not particularly limited as long as it has an absorption region at a wavelength of 300 to 400 nm. For example, salicylic acid type, benzozonone type, benzotriazole type, cyanoacrylate type, triazine type, etc. Can be mentioned.

Examples of the salicylic acid ultraviolet absorber include phenyl salicylate, pt-butylphenyl salicylate, and p-octylphenyl salicylate.
Examples of the benzophenone-based ultraviolet absorber include 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-octoxybenzophenone, 2-hydroxy-4-dodecyloxybenzophenone, 2, 2'-dihydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, 2-hydroxy-4-methoxy-5-sulfobenzophenone, bis (2-methoxy-4-hydroxy-5- And benzoylphenyl) methane.

Examples of the benzotriazole ultraviolet absorber include 2- (2′-hydroxy-5′-methylphenyl) benzotriazole, 2- (2′-hydroxy-5′-t-butylphenyl) benzotriazole, 2 -(2'-hydroxy-3 ', 5'-di-t-butylphenyl) benzotriazole, 2- (2'-hydroxy-3'-t-butyl-5'-methylphenyl) -5-chlorobenzotriazole 2- (2'-hydroxy-3,5'-di-t-amylphenyl) benzotriazole, 2- [2'-hydroxy-3 '-(3 ", 4", 5 ", 6' '-Tetrahydrophthalimidomethyl) -5'-methylphenyl] benzotriazole, 2,2-methylenebis [4- (1,1,3,3-tetramethylbutyl) -6- (2H-be Zotriazol-2-yl) phenol], 2- (2'-hydroxy-5'-methacryloxyphenyl) -2H-benzotriazole, octyl- [3-tert-butyl-4-hydroxy-5- (2H- Benzotriazol-2-yl) phenyl] propionate, octyl- [3-tert-butyl-4-hydroxy-5- (5′-chloro-2H-benzotriazol-2-yl) phenyl] propionate, 2, -(2H-benzotriazol-2-yl) -4- (1 ', 1', 3 ', 3'-tetramethylbutyl) -6- (1' '-methyl-1' '-phenylethyl) phenol, 2- (2H-benzotriazol-2-yl) -4,6-bis (1'-methyl-1'-phenylethyl) phenol, 2- (2H-benzotriazol-2-yl) -4,6-di-t-pentylphenol.

Examples of the cyanoacrylate ultraviolet absorber include 2-ethylhexyl-2-cyano-3,3'-diphenyl acrylate, ethyl-2-cyano-3,3'-diphenyl acrylate, and the like.

Examples of the triazine-based UV absorber include 2- [4 ′-[2 ″ -hydroxy-3 ″ -dodecyloxypropyl] oxy] -2′-hydroxyphenyl-4,6-bis (2 ′ '', 4 '' '-dimethylphenyl) -1,3,5-triazine, 2,4-bis (2', 4'-dimethylphenyl) -6- (2 ''-hydroxy-4 ''-iso Octyloxyphenyl) -1,3,5-triazine and the like. Among these ultraviolet absorbers, benzotriazole and triazine are preferable, and triazine is particularly preferable. These ultraviolet absorbers may be used alone or in combination of two or more.

The content of the ultraviolet absorber is preferably a lower limit of 0.1% by mass and an upper limit of 30% by mass in 100% by mass of the solid content of the ultraviolet curable coating composition. There exists a possibility that the weather resistance of a coating film may fall that it is less than 0.1 mass%. When it exceeds 30% by mass, the weather resistance is not improved any more, which is disadvantageous from the economical viewpoint, and the curability may be inhibited. The lower limit is more preferably 0.5% by mass, and still more preferably 1% by mass. The upper limit is more preferably 20% by mass, and still more preferably 15% by mass.

The ultraviolet curable coating composition may contain a hindered amine light stabilizer. When the ultraviolet curable coating composition contains both the ultraviolet absorber and the hindered amine light stabilizer, even better weather resistance can be obtained.

The hindered amine light stabilizer is not particularly limited. For example, Tinuvin 123, Tinuvin 144, Tinuvin 292 (all of which are manufactured by Ciba Specialty Chemicals), Adeka Stab LA-77, Adeka Stub LA-57, Adeka Stub LA -62, ADK STAB LA-67, ADK STAB LA-63, ADK STAB LA-82, ADK STAB LA-87 (all of which are manufactured by Asahi Denka Co., Ltd.). These may be used alone or in combination of two or more.

The content of the hindered amine light stabilizer is preferably a lower limit of 0.1% by mass and an upper limit of 3% by mass in 100% by mass of the solid content of the ultraviolet curable coating composition. There exists a possibility that the weather resistance of a coating film may fall that it is less than 0.1 mass%. When it exceeds 3% by mass, the weather resistance is not improved any more, which is disadvantageous from the economical viewpoint, and the curability may be inhibited.

The ultraviolet curable coating composition is not particularly limited as long as it is a composition curable with ultraviolet rays. For example, radical polymerization ultraviolet curable coating composition, cationic polymerization ultraviolet curable coating composition, and its combined ultraviolet curable coating. A composition etc. can be mentioned.

The radical polymerization ultraviolet curable coating composition is not particularly limited as long as it contains a radically polymerizable reactive group such as one or more (meth) acrylate groups or (meth) allyl groups in the molecule. For example, (un) saturated polyester resin, epoxy resin, urethane resin, acrylic resin, etc. with acid-containing monomers such as (meth) acrylic acid, glycidyl group-containing monomers such as glycidyl (meth) acrylate, (meth) allyl glycidyl ether, etc. Modified, 2-hydroxyethyl (meth) acrylate, glycerin di (meth) acrylate, trimethylolpropane di (meth) acrylate, hydroxyl group-containing (meth) acrylic monomer such as pentaerythritol tri (meth) acrylate and hexamethylene diisocyanate, Xylylene diisocyanate It may be mentioned polyfunctional isocyanate monomers, such as toluene diisocyanate denatured number average molecular weight 300-5000 of modified polyester resins, modified epoxy resins, modified urethane resin, a mixture of one or more such modified acrylic resin. If necessary, ethylene glycol mono (meth) acrylate, ethylene glycol di (meth) acrylate, 1,6-hexanediol mono (meth) acrylate, 1,6-hexanediol di (meth) acrylate, Methylolpropane di (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate (Meth) acrylate monomers such as can also be blended. These radical polymerization ultraviolet curable coating compositions may be used alone or in combination of two or more.

The radical polymerization ultraviolet curable coating composition may contain a photo radical polymerization initiator.
The radical polymerization initiator that can be contained in the radical polymerization ultraviolet curable coating composition is not particularly limited, and known ones can be used, for example, benzoin methyl ether, benzoin propyl ether, benzyl, benzyl dimethyl ketal, Acyl type such as benzoylcyclohexanol, diphenyl- (2,4,6-trimethylbenzoyl) phosphine oxide, bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide, bis (2,6-dimethoxybenzoyl) -2 , 4,4-trimethyl-pentylphosphine oxide, bis (2,6-dimethoxybenzoyl) -phenylphosphine oxide, bis (2,6-dimethoxybenzoyl) -2,4,4-trimethyl-pentylphosphine oxide, etc. Examples include fin oxides, 2-isopropylthioxanthone, 4-isopropylthioxanthone, 2-chlorothioxanthone, 1-chloro-4-propoxythioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, and other thioxanthones. it can. Of these, photo radical polymerization initiators such as phosphine oxides and thioxanthones having a photosensitive region at 400 to 450 nm that do not overlap with the absorption region of the ultraviolet absorber are particularly preferable because curing proceeds with as little energy as possible. These may be used alone or in combination of two or more.

The content of the photo radical polymerization initiator is preferably a lower limit of 0.5% by mass and an upper limit of 10% by mass in a solid content of 100% by mass of the radical polymerization UV curable coating composition. If it is less than 0.5% by mass, curing of the resin component may not sufficiently proceed. Even if it exceeds 10% by mass, the curability is not improved any more, which is disadvantageous from the economical viewpoint, and the coating film may be colored. The lower limit is more preferably 1.0% by mass, and still more preferably 2.0% by mass. The upper limit is more preferably 8% by mass, and still more preferably 5% by mass.

The cationic polymerization ultraviolet curable coating composition is particularly limited as long as it contains one or more cationically polymerizable reactive groups such as epoxy group, oxetanyl group, tetrahydrofuryl group, and vinyl group in the molecule. For example, an epoxy resin, an epoxidized polydiene resin, etc. can be mentioned.

Examples of the epoxy resin include aromatic epoxy resins, aliphatic epoxy resins obtained by reacting polyethers such as bisphenol A, B, F, polyethylene glycol, polypropylene glycol, and polybutylene glycol with (methyl) epihalohydrin, Aromatic / aliphatic epoxy resins, those having a polybasic acid such as adipic acid, sebacic acid, trimellitic acid, pyromellitic acid and the like to leave an epoxy group, and those having a number average molecular weight of 2000 or more can be mentioned. .

Examples of the epoxidized polydiene resin include styrene, (meth) acrylonitrile, vinyl acetate, methyl (meth) acrylate, ethyl (meth) acrylate, (meth ) A vinyl monomer such as acrylic acid or a copolymer obtained by epoxidizing two or more kinds of copolymers with peracetic acid, epoxidized soybean oil and the like can be mentioned. These cationic polymerization ultraviolet curable coating compositions may be used alone or in combination of two or more.

The cationic polymerization ultraviolet curable coating composition may contain a photocationic polymerization initiator in order to enhance ultraviolet curability.
The cationic photopolymerization initiator that can be contained in the cationic polymerization ultraviolet curable coating composition is not particularly limited, and known ones can be used, such as triphenylsulfonium hexafluorophosphate, triphenylsulfonium. Hexafluoroantimonate, triphenylsulfonium trifluoromethanesulfonate, naphthyldiphenylsulfonium hexafluorophosphate, 2,4,6-trimethylphenyldiphenylsulfonium-4-methylbenzenesulfonate, bis [alkyl (C = 10-14) phenyl] iodonium Trifluoromethanesulfonate, bis [alkyl (C = 10-14) phenyl] iodonium tetrafluoroborate, bis [alkyl (C = 10-14) phenyl] iod It can be mentioned hexafluorophosphate and the like. These may be used alone or in combination of two or more.

The content of the photocationic polymerization initiator is preferably a lower limit of 0.5% by mass and an upper limit of 10% by mass with respect to 100% by mass of the solid content of the cationic polymerization ultraviolet curable coating composition. If it is less than 0.5% by mass, curing of the resin component may not sufficiently proceed. Even if it exceeds 10% by mass, the curability is not improved any more, which is disadvantageous from the economical viewpoint, and the coating film may be colored. The lower limit is more preferably 1.0% by mass, and still more preferably 2.0% by mass. The upper limit is more preferably 8% by mass, and still more preferably 5% by mass.

In addition, the cationic polymerization ultraviolet curable coating composition includes 2-isopropylthioxanthone, 4-isopropylthioxanthone, 2-chlorothioxanthone, 1-chloro-4-propoxythioxanthone for the purpose of shifting the photosensitive region to a long wavelength. It is particularly preferable to contain a thioxanthone compound such as 2,4-dimethylthioxanthone or 2,4-diethylthioxanthone. These may be used alone or in combination of two or more.

It is preferable that content of the said thioxanthone type compound is 1-10 mass% with respect to 100 mass% of solid content of the said cationic polymerization ultraviolet curable coating composition. If it is less than 1% by mass, curing of the resin component may not sufficiently proceed. Even if it exceeds 10% by mass, the curability is not improved any more, which is disadvantageous from the economical viewpoint, and the coating film may be colored.

The combined polymerization UV curable coating composition is a blend of the radical polymerization UV curable coating composition and the cationic polymerization UV curable coating composition, one or more (meth) acrylate groups in the molecule, ( Examples thereof include those having both a radically polymerizable reactive group such as a (meth) allyl group and one or more cationically polymerizable reactive groups such as an epoxy group, an oxetanyl group, a tetrahydrofuryl group, and a vinyl group.

When using the above-mentioned combined polymerization ultraviolet curable coating composition, a photopolymerization initiator can be used. As said photoinitiator, the said photocationic polymerization initiator etc. can be mentioned, for example. Moreover, the said radical photopolymerization initiator can also be used together as needed.

In the above UV curable coating compositions, inorganic pigments such as titanium oxide, lead sulfate, yellow lead, dials, bitumen and carbon black, nitroso, nitro, and azo as long as the curability and coating properties are not deteriorated. Organic pigments such as phthalocyanine, basic dye, acid dye, vat dye, and mordant dye, extender pigments such as barium sulfate, barium carbonate, calcium carbonate, clay, and talc can be blended.

As the ultraviolet absorber used for the cationic polymerization ultraviolet curable coating composition, the combined polymerization ultraviolet curable coating composition, and the colorant, among the ultraviolet absorber and the colorant, from the viewpoint of curability, neutrality, It is preferable to select an acidic one.

In order to improve the paintability, the ultraviolet curable coating composition includes toluene, xylene, acetone, methyl ethyl ketone, methyl isobutyl ketone, ethyl acetate, butyl acetate, methanol, ethanol, isopropanol and other organic solvents, water, silicon Additives such as fluorine and acrylic resins can be blended.

The UV curable coating composition can be applied to a substrate such as metal, plastic, paper, wood, glass, ceramic, mortar, etc., but it can be applied particularly advantageously to heat-sensitive resin films and paper. it can. Therefore, by using the present invention, it is also suitable for a heat-sensitive substrate such as a resin film or paper, which has been difficult to coat by a conventional method that requires relatively large energy for curing. can do.

The resin film as the article to be coated is not particularly limited, and known ones can be used, for example, acrylic films such as polymethyl methacrylate, polyester films such as polyethylene terephthalate and polyethylene naphthalate, and bisphenols. Polycarbonate films obtained from carbonyl chloride, nylon films such as nylon 6, nylon 66 and nylon 12, olefin films such as polyethylene and polypropylene, vinyl films such as polyvinyl alcohol, polyvinyl acetate, polyvinyl chloride and polyvinylidene chloride, and the like, and What extended these etc. can be mentioned.

The paper as the coating object is not particularly limited, and is made of paper made of pulp fibers such as wood, Japanese paper made of starch fibers such as Kozo and Mitsumata, polystyrene, polyethylene, polypropylene, vinyl chloride resin, etc. Examples thereof include a film made of a thermoplastic resin as a raw material, a paper making method, a synthetic paper by a synthetic pulp method, and the like. These base materials may be used independently and may use 2 or more types together.

Before coating the ultraviolet curable coating composition, the substrate can be subjected to ordinary degreasing, chemical conversion treatment, corona discharge treatment, flame treatment, silane coupling agent coating treatment, primer coating treatment, and the like.

It does not specifically limit as coating of the said ultraviolet curable coating composition, For example, it can carry out by well-known methods, such as spray, roll coat, curtain flow coat, brush coating, and immersion.

In the conventional curing method, it is possible to obtain a hard coat with a thin film that can be applied to a substrate having weak weather resistance such as a PET film to prevent deterioration of the coating film as well as suppressing deterioration of the substrate. It was difficult. That is, if it is going to suppress the permeation | transmission of an ultraviolet-ray with a thin film, since it is necessary to mix | blend a large amount of ultraviolet curing agents, sclerosis | hardenability will fall large as a result. Therefore, the conventional curing method is a technique for two-stage curing of a coating film having a relatively thick film and a concealing property, and in the case of a thin film, even if the concealing property is increased by increasing the pigment concentration, It was difficult to suppress deterioration and deterioration of the base material, and as a result, the superiority of the two-stage irradiation was reduced.

On the other hand, the curing method using the ultraviolet curable coating composition of the present invention causes deterioration of the coating film and the base material even when it is coated with a thin film on a base material having weak weather resistance such as a PET film. This is a method that can be sufficiently suppressed, and is superior to the conventional curing method, particularly in the case of a thin film.

Accordingly, the dry film thickness of the ultraviolet curable coating composition is not particularly limited and can be set as appropriate. In particular, in the case of a thin film, the lower limit is preferably 1 μm and the upper limit is 20 μm. If it is less than 1 μm, the weather resistance, alkali resistance, acid resistance, and hot water resistance of the coating film may be lowered. If it exceeds 20 μm, the adhesion of the coating film may be lowered, which may be economically disadvantageous. The lower limit is more preferably 2 μm, still more preferably 3 μm. The upper limit is more preferably 15 μm, still more preferably 10 μm.

When an organic solvent or water is blended as a solvent in the ultraviolet curable coating composition, the coating is dried with hot air at 50 to 200 ° C. for 1 second to 10 minutes to evaporate the solvent, and then irradiated with ultraviolet rays. It is preferable. Thereby, necessary and sufficient hardening can be performed.

In the coating method using the ultraviolet curable coating composition of the present invention, the second step is a step of irradiating the coating film formed by coating in the step (1) with electromagnetic waves (step (2)). . By performing the above step (2), the coated film can be sufficiently cured, and has excellent adhesion, scratch resistance, stain resistance, alkali resistance, acid resistance, warm water resistance, and weather resistance. It is possible to obtain an ultraviolet curable coating film.

The step (2) includes a step (2-1) of irradiating an electromagnetic wave having a relative output ratio of 400 to 410 nm / 250 to 260 nm of 1.1 or more, and a relative output ratio of 400 to 410 nm / 250 to 260 nm. It consists of the process (2-2) which irradiates the electromagnetic wave which is 0.7 or less.

The step (2) is a step (2-1) of irradiating an electromagnetic wave having a relative output ratio of 1.1 or more in the wavelength range of 400 to 410 nm / wavelength range of 250 to 260 nm as the first ultraviolet irradiation. It is. By performing the above step (2-1), the lower layer portion of the coating film can be sufficiently cured mainly. When the relative power ratio of the wavelength range of 400 to 410 nm / wavelength range of 250 to 260 nm of the light source of the first stage is less than 1.1, the coating surface layer portion cures faster than the inside, and the cured coating film adheres. Property, alkali resistance, water resistance and the like may be reduced. In the step (2-1), the lower limit of the relative output ratio is preferably 1.1, and more preferably 1.5.

In the present invention, it is also a characteristic point that the relative intensity is defined by selecting wavelength ranges of 400 to 410 nm and 250 to 260 nm. Although 400 nm becomes a boundary region with visible light, a photopolymerization initiator having an absorption region at a long wavelength itself has a color such as yellow. Therefore, in consideration of coloring of the coating film, an absorption region is provided at 400 to 410 nm. Since it is preferable to use a photopolymerization initiator, the light source in the present invention also defines a relative intensity of 400 to 410 nm accordingly. In addition, when ultraviolet rays are irradiated in the air, the surface of the coating film usually formed by radical polymerization ultraviolet curable coating is subject to curing inhibition by oxygen in the air and the curing is delayed, but the wavelength range of 250 to 260 nm is in the air Therefore, the surface layer can be efficiently cured by irradiating ultraviolet rays in this wavelength range. For this reason, in this invention, the relative intensity | strength of 250-260 nm is prescribed | regulated.

Further, for example, compared with the case where the first stage is irradiated with electromagnetic waves having main wavelengths of 380 to 420 nm and the second stage is 200 to 365 nm, the coating method using the ultraviolet curable coating composition of the present invention. Is a more practical method because it defines a relative intensity ratio of 400 to 410 nm and 250 to 260 nm.

In addition, the relative output ratio of the wavelength range of 400 to 410 nm / wavelength range of 250 to 260 nm in the step (2-1) is the integrated energy in the range of wavelengths from 400 to 410 nm / integrated in the range of wavelengths from 250 to 260 nm. Energy.

As a light source for performing the above-mentioned step (2-1), an ozone type quartz arc tube metal halide lamp in which one or more halides such as Ga, Zn, Pb, Al, Sn, Cd, and Fe are enclosed, less than 230 nm is used. Examples thereof include a single tube type using ozone-free quartz that hardly transmits light as a luminous tube material, or a double tube type metal halide lamp using a special ultraviolet ray transmitting glass as an outer tube.

The irradiation dose of ultraviolet rays of the step (2-1), the lower limit 50 mJ / cm ^2, it is preferable that the upper limit 5000 mJ / cm ^2. If it is less than 50 mJ / cm ² , the coated film may not be cured sufficiently. If it exceeds 5000 mJ / cm ² , curing may proceed excessively, the coating film may be discolored, and it may be economically disadvantageous. The lower limit is more preferably 100 mJ / cm ² , and the upper limit is more preferably 4000 mJ / cm ² .

In the step (2), following the step (2-1), electromagnetic waves having a relative output ratio in the wavelength range of 400 to 410 nm / wavelength range of 250 to 260 nm are 0.7 or less as the second-stage ultraviolet irradiation. The irradiation step (2-2) is performed. By performing the above step (2-2), the surface layer portion of the coating film can be sufficiently cured mainly. When the relative output ratio of the wavelength range of 400 to 410 nm / wavelength range of 250 to 260 nm of the second-stage light source exceeds 0.7, the coating surface layer portion is insufficiently cured, and the hardness of the cured coating film, scratch resistance, Contamination and the like are reduced, and more energy is required to obtain sufficient coating performance. In the step (2-2), the upper limit of the relative output ratio is preferably 0.7, and more preferably 0.5.

In addition, the relative output ratio of the wavelength range of 400 to 410 nm / wavelength range of 250 to 260 nm in the step (2-2) is the integrated output (energy) in the range of wavelengths from 400 to 410 nm / range of wavelengths from 250 to 260 nm. Is the accumulated output (energy).

Examples of the light source for performing the step (2-2) include a medium pressure mercury lamp, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, a carbon arc lamp, and a xenon lamp using ozone type quartz as an arc tube.

The irradiation dose of ultraviolet rays of the step (2-2) (the output of the ultraviolet (Energy W / cm ²⁾ to those obtained by integrating the irradiation time (sec)), the lower limit 50 mJ / cm ^2, is at the upper limit 5000 mJ / cm ² It is preferable. If it is less than 50 mJ / cm ² , the coated film may not be cured sufficiently. If it exceeds 5000 mJ / cm ² , curing may proceed excessively, the coating film may be discolored, and it may be economically disadvantageous. The lower limit is more preferably 100 mJ / cm ² , and the upper limit is more preferably 4000 mJ / cm ² .

As the total irradiation amount of the ultraviolet of the step (2-1) and (2-2), the lower limit 100 mJ / cm ^2, it is preferable that the upper limit 10000 mJ / cm ^2. If it is less than 100 mJ / cm ² , the coated film may not be sufficiently cured. If it exceeds 10,000 mJ / cm ² , curing may proceed excessively, the coating film may be discolored, and it may be economically disadvantageous. The lower limit is more preferably 200 mJ / cm ² , and the upper limit is more preferably 8000 mJ / cm ² .

By performing the above steps (2-1) and (2-2), the lower layer portion and the surface layer portion of the coating film are uniformly cured with less energy, and adhesion, scratch resistance, contamination resistance, alkali resistance are reduced. In addition, an ultraviolet curable coating film excellent in acid resistance, hot water resistance, and weather resistance can be obtained. In addition, since an ultraviolet-cured coating film having excellent physical properties can be obtained with less energy, it can be particularly advantageously applied to a heat-sensitive resin film or paper. The effect as described above is to form a coating film using an ultraviolet curable coating composition containing an ultraviolet absorber having an absorption region at 300 to 400 nm, and to cure the formed coating film by irradiating with ultraviolet rays. In particular, a specific effect obtained by first irradiating an electromagnetic wave having a relative output ratio of 400 to 410 nm / 250 to 260 nm of 1.1 or more and then irradiating an electromagnetic wave having a relative output ratio of 0.7 or less. It is.

In the coating method using the ultraviolet curable coating composition, the ultraviolet curable coating composition may be an ultraviolet curable clear coating composition. A coating method using such an ultraviolet curable clear coating composition is also one aspect of the present invention.

The coating method using the ultraviolet curable coating composition can be suitably applied to a heat-sensitive substrate. A surface-coated resin film and a surface-coated paper, the surfaces of which are coated with a coating film formed from the ultraviolet curable coating composition by applying a coating method using the ultraviolet curable coating composition onto a resin film or paper Can be obtained. Such a surface-coated resin film and surface-coated paper are also one aspect of the present invention.

The coating method using the ultraviolet curable coating composition of the present invention is formed by the step (1) of applying an ultraviolet curable coating composition containing an ultraviolet absorber having an absorption region at 300 to 400 nm and the above step (1). The coating film is irradiated with an electromagnetic wave having a relative output ratio of 400 to 410 nm / 250 to 260 nm of 1.1 or more and irradiated with an electromagnetic wave having a relative output ratio of 0.7 or less (2). is there. Therefore, the lower layer part and the surface layer part of the coating film are uniformly cured with less energy, and an ultraviolet curable coating excellent in adhesion, scratch resistance, stain resistance, alkali resistance, acid resistance, warm water resistance, and weather resistance. A film can be obtained and can be suitably applied to resin films, paper, and the like that are vulnerable to heat.

Since the coating method using the ultraviolet curable coating composition of the present invention has the above-described configuration, it is an ultraviolet curable coating excellent in adhesion, scratch resistance, stain resistance, alkali resistance, acid resistance, warm water resistance, and weather resistance. A membrane can be obtained. Moreover, since a cured coating film can be obtained with less energy, it can be advantageously used for an external building material coating film or the like.

EXAMPLES Hereinafter, although an Example is hung up and demonstrated in more detail, this invention is not limited only to these Examples. In the examples, “parts” and “%” mean “parts by mass” and “% by mass” unless otherwise specified.

Production Example 1
A four-necked flask equipped with a stirrer was charged with 610 parts of ethyl acetate, 1200 parts of Aronix M-305 (manufactured by Toa Gosei Co., Ltd., pentaerythritol triacrylate), 0.8 part of hydroquinone, and 0.8 part of dibutyltin dilaurate and stirred at 40 ° C. Below, 222 parts of isophorone diisocyanate was added dropwise over 1 hour. Thereafter, the temperature was raised to 70 ° C. and stirring was continued for 2 hours. After confirming that absorption based on an isocyanate group of 2220 cm ⁻¹ disappeared with an infrared spectrophotometer, urethane having a number average molecular weight of 600 and a solid content of 70% was obtained. An acrylate resin solution was obtained.

Example 1
100 parts of the urethane acrylate resin solution obtained in Production Example 1, 2 parts of Darocur TPO [manufactured by Ciba Specialty Chemicals, diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide], 400 parts of Tinuvin [Ciba Specialty Chemicals UV absorber, 2- [4 ′-[2 ″ -hydroxy-3 ″ -dodecyloxypropyl] oxy] -2′-hydroxyphenyl-4,6-bis (2 ′ ″, 4 ′) '' -Dimethylphenyl) -1,3,5-triazine and 2,4-bis (2 ', 4'-dimethylphenyl) -6- (2''-hydroxy-4''-isooctyloxyphenyl)- 1,3,5-triazine 1-methoxy-2-propanol solution] 3 parts, Tinuvin 928 [manufactured by Ciba Specialty Chemicals, UV absorber, 2- (2H- Nzotriazol-2-yl) -6- (1-methyl-1-phenylethyl) -4- (1,1,3,3-tetramethylbutyl) phenol] 3 parts, Tinuvin 292 [Ciba Specialty Chemicals Hindered amine light stabilizer, bis (1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate, methyl (1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate Mixture] A radical polymerization ultraviolet curable coating composition consisting of 1 part and 40 parts of ethyl acetate was coated on a 25 μm thick easy-adhesion-treated polyethylene terephthalate film with a roll coater so as to have a dry film thickness of 10 μm. After applying warm air of 80 ° C. for 1 minute to this, first, a condensing metal halide lamp MBL-250NL (manufactured by Nippon Battery Co., Ltd., 120 W / cm, ozone type quartz tube, 400 to 410 nm / 250 to 260 nm relative output ratio 1. 5) Passed under at a speed of 15 m / min. The amount of ultraviolet irradiation at this time was 530 mJ / cm ² . Next, under a concentrating high-pressure mercury lamp HAL-250NL (manufactured by Nippon Battery, 120 W / cm, ozone type quartz tube, relative output ratio of 400 to 410 nm / 250 to 260 nm, 0.5) at a speed of 15 m / min. Harden. The amount of ultraviolet irradiation at this time was 550 mJ / cm ² .

Table 1 shows the results of evaluating adhesion, scratch resistance, contamination resistance, warm water resistance, alkali resistance, acid resistance, and weather resistance using the obtained coated sheet by the following methods.

Evaluation method <Adhesion>
100 grids with a 1 mm interval were made with a sharp cutter on the coating film, and a cellophane tape was applied and peeled off. The remaining area of the coating film was measured to determine adhesion.
◯: Remaining area is 80% or more Δ: Remaining area is 80-20%
X: Remaining area is less than 20%

<Scratch resistance>
Scratch the painted surface with a little fingernail at room temperature. The degree of scratching was judged visually.
◯: No scratches are observed Δ: Some scratches are observed ×: Significant scratches are observed

<Contamination resistance>
Draw with red magic on the painted surface. After leaving at room temperature for 1 day, wipe with ethanol. The presence or absence of traces was visually determined.
◯: No trace Δ: Some trace ×: Significant trace

<Hot water resistance>
The coated sheet was immersed in 60 ° C. warm water for 10 days. The droplets were pulled up and wiped off, and the appearance of the coated surface was visually judged.
○: No abnormality △: Slight whitening ×: Significant whitening

<Alkali resistance>
The coated sheet was immersed in a 5% aqueous sodium hydroxide solution at 25 ° C. for 10 days. It was pulled up and washed with water to wipe off water droplets, and the appearance of the coated surface was visually judged.
○: No abnormality △: Slight whitening ×: Significant whitening

<Acid resistance>
The coated sheet was immersed in a 5% aqueous hydrochloric acid solution at 25 ° C. for 10 days. It was pulled up and washed with water to wipe off water droplets, and the appearance of the coated surface was visually judged.
○: No abnormality △: Slight whitening ×: Significant whitening

<Weather resistance>
The coated sheet is exposed to eye super UV tester SUVF11 (Iwasaki Electric Co., Ltd.) for 100 hours. The degree of discoloration of the coating film was visually judged.
◯: Slightly yellowed △: Significantly yellowed ×: Significantly yellowed

Example 2
100 parts of urethane acrylate resin solution obtained in Production Example 1, 30 parts of Aronix M-305 (supra), Irgacure 819 [Ciba Specialty Chemicals, bis (2,4,6-trimethylbenzoyl) -phenylphosphine Oxide] 3 parts, Tinuvin 384-2 [manufactured by Ciba Specialty Chemicals, benzenepropanoic acid, 3- (2H-benzotriazol-2-yl) -5- (1,1-dimethylethyl) -4- Hydroxy-C7-9 side chain or linear alkyl ester and 1-methoxy-2-propyl acetate] 3 parts, Tinuvin 928 (supra) 3 parts, Tinuvin 123 [Bis (2,2,6,6-tetramethyl- 1- (Octyloxy) -4-piperidinyl) decandioic acid ester] 1 part, ethyl acetate The radical polymerization UV curable coating composition consisting of 0 parts was coated to a dry film thickness of 10μm on the easy-adhesion treated polyethylene terephthalate film having a thickness of 25μm by a roll coater. After applying warm air of 80 ° C. to this for 1 minute, first, under the fusion UV irradiation device V valve (manufactured by Fusion, 240 W / cm, relative output ratio of 400 to 410 nm / 250 to 260 nm of 14.0), 15 m / Pass at a speed of minutes. The amount of ultraviolet irradiation at this time was 1100 mJ / cm ² . Subsequently, it was cured by passing under a fusion UV irradiation apparatus H plus valve (manufactured by Fusion, 240 W / cm, relative output ratio of 400 to 410 nm / 250 to 260 nm of 0.5) at a speed of 15 m / min. The amount of ultraviolet irradiation at this time was 1300 mJ / cm ² . Using the obtained coated sheet, it was evaluated in the same manner as in Example 1, and the obtained results are shown in Table 1.

Example 3
The radical polymerization ultraviolet curable coating composition obtained in Example 1 was coated on a 25 μm thick easy-adhesion-treated polyethylene terephthalate film with a roll coater to a dry film thickness of 10 μm. After applying warm air of 80 ° C. to this for 1 minute, a condensing metal halide lamp MAL-250NL (manufactured by Nihon Battery, 120 W / cm, ozone type quartz tube, relative output ratio of 400 to 410 nm / 250 to 260 nm, 1.1. ) Was cured at a speed of 15 m / min. The amount of ultraviolet irradiation at this time was 500 mJ / cm ² . Next, it was cured by passing under a concentrating high-pressure mercury lamp HAL-250NL (supra) at a speed of 15 m / min. The amount of ultraviolet irradiation at this time was 600 mJ / cm ² . Using the obtained coated sheet, it was evaluated in the same manner as in Example 1, and the obtained results are shown in Table 1.

Example 4
The radical polymerization ultraviolet curable coating composition obtained in Example 1 was coated on a 25 μm thick easy-adhesion-treated polyethylene terephthalate film with a roll coater to a dry film thickness of 10 μm. After applying warm air of 80 ° C. to this for 1 minute, a condensing metal halide lamp MAL-250L (manufactured by Nihon Battery, 120 W / cm, ozone-free type quartz tube, 400 to 410 nm / 250 to 260 nm relative output ratio 2. It was cured by passing under 4) at a speed of 15 m / min. The amount of ultraviolet irradiation at this time was 540 mJ / cm ² . Next, it was cured by passing under a fusion UV irradiation device H bulb (supra) at a speed of 15 m / min. The amount of ultraviolet irradiation at this time was 1300 mJ / cm ² . Using the obtained coated sheet, it was evaluated in the same manner as in Example 1, and the obtained results are shown in Table 1.

Comparative Example 1
Using the coated sheet obtained in the same manner as in Example 1 except that it is cured by passing twice under a concentrating high-pressure mercury lamp HAL-250NL (supra) at a speed of 15 m / min, Evaluation was conducted in the same manner, and the results obtained are shown in Table 1.

Comparative Example 2
Using the coated sheet obtained in the same manner as in Example 1 except that it is cured by passing twice under a condensing metal halide lamp MBL-250NL (supra) at a speed of 15 m / min, Example 1 and Evaluation was conducted in the same manner, and the results obtained are shown in Table 1.

Comparative Example 3
After passing under the condensing type high-pressure mercury lamp HAL-250NL (above) at a speed of 15 m / min, then passing under the condensing type metal halide lamp MBL-250NL (above) at a speed of 15 m / min. Using the coated sheet obtained in the same manner as in Example 1 except for curing, the evaluation was performed in the same manner as in Example 1, and the obtained results are shown in Table 1.

Comparative Example 4
Passed twice under a condensing type high-pressure mercury lamp HAL-250L (Japan Battery, 120 W / cm, ozone-free quartz tube, relative output ratio of 400 to 410 nm / 250 to 260 nm of 1.0) at a speed of 15 m / min. Using the coated sheet obtained in the same manner as in Example 1 except that it was used, evaluation was performed in the same manner as in Example 1, and the obtained results are shown in Table 1.

Comparative Example 5
After passing under the concentrating high-pressure mercury lamp HAL-250L (above) at a speed of 15 m / min, then passing under the concentrating high-pressure mercury lamp HAL-250NL (above) at a speed of 15 m / min. Using the coated sheet obtained in the same manner as in Example 1 except for curing, the evaluation was performed in the same manner as in Example 1, and the obtained results are shown in Table 1.

From Table 1, the ultraviolet curable coating film on the surface-coated resin film obtained in the examples was excellent in adhesion, scratch resistance, stain resistance, warm water resistance, alkali resistance, acid resistance and weather resistance. It was. On the other hand, what was obtained by the comparative example was not excellent in all the physical properties.

Comparative Example 6
Using the coated sheet obtained in the same manner as in Example 1 except that the number of passages is changed at a speed of 15 m / min under the condensing metal halide lamp MBL-250NL (described above) and cured, Example 1 and Evaluation was conducted in the same manner, and the results obtained are shown in Table 2.

Comparative Example 7
Using the coated sheet obtained in the same manner as in Example 1 except that the number of times of passage is changed under a condensing high-pressure mercury lamp HAL-250NL (supra) at a speed of 15 m / min and cured, Example 1 and Evaluation was conducted in the same manner, and the results obtained are shown in Table 2.

From Table 2, when using the method of Example, compared with the case of using the method of Comparative Examples 6 and 7, excellent adhesion with less energy, scratch resistance, stain resistance, hot water resistance, and alkali resistance. It became clear that an ultraviolet-cured coating film having acid resistance and weather resistance could be obtained.

The coating method using the ultraviolet curable coating composition of the present invention is a UV curable coating film having excellent adhesion, scratch resistance, stain resistance, alkali resistance, acid resistance, warm water resistance, and weather resistance with relatively little energy. Since it is a method that can be obtained, it can be suitably applied to exterior building material-coated film resin films (eg, exterior building material-coated film, etc.), paper, etc., which are particularly vulnerable to heat.

Claims (4)

A method of curing an ultraviolet curable coating composition comprising a step (1) of coating an ultraviolet curable coating composition and a step (2) of irradiating electromagnetic waves,
The ultraviolet curable coating composition contains an ultraviolet absorber having an absorption region at a wavelength of 300 to 400 nm,
The step (2) includes a step (2-1) of irradiating an electromagnetic wave having a relative output ratio of 1.1 or more in a wavelength range of 400 to 410 nm / wavelength range of 250 to 260 nm, and a wavelength range of 400 to 410 nm / wavelength range. A coating method using an ultraviolet curable coating composition, comprising the step (2-2) of irradiating an electromagnetic wave having a relative output ratio of 250 to 260 nm of 0.7 or less. The method for coating with an ultraviolet curable coating composition according to claim 1, wherein the ultraviolet curable coating composition is an ultraviolet curable clear coating composition. A surface-coated resin film obtained by applying a coating method with an ultraviolet curable coating composition according to claim 1 or 2 on a resin film. A surface-coated paper obtained by applying a coating method with the ultraviolet curable coating composition according to claim 1 or 2 onto the paper.