JP5247121B2 - Coating method for signboard or interior board and multilayer composite board - Google Patents

Description

  The present invention relates to a coating film forming method for a signboard or an interior board and a multilayer composite board. The present invention particularly relates to a coating film forming method for a signboard or interior panel using a coating material for a precoat metal having excellent coating stability, coating film hardness, processability, corrosion resistance and adhesion to a UV ink coating film, and the coating film. The present invention relates to a multilayer composite board for signboards or interior boards obtained by a forming method.

  In recent years, in the field of pre-coated metal sheets for building materials and equipment processing, there has been a demand for coated metal sheets with excellent coating film hardness, processability, corrosion resistance and adhesion to UV ink. A coated metal plate is commercially available in which a primer coating film is formed on a metal plate, a pre-coated metal paint is formed to form a coating film, and UV ink is applied on the coating film.

  On the other hand, a hydroxyl group-containing polyester resin having a number average molecular weight of 1,500 to 35,000, a glass transition temperature of −30 ° C. to 60 ° C., and a hydroxyl value of 3 to 100 mgKOH / g, and a melamine resin in which methylol groups are alkyletherified. 20% or more of the number of methylol groups is composed of a melamine crosslinking agent etherified with an alkyl group having 6 to 12 carbon atoms, and 0.1 to 0.1 parts by weight of the curing catalyst with respect to 100 parts by weight of the total amount of the film-forming resin component. A coating composition containing 2.0 parts by weight is disclosed (Patent Document 1).

In addition, a primer coating film is formed on a metal plate that may be subjected to chemical conversion treatment on the surface, and an intermediate coating film that is a cured film of a polyester / melamine resin-based intermediate coating paint on this primer coating film Further, a technique relating to a coated metal plate in which a top coat film is formed on the intermediate coat film is disclosed (Patent Document 2). However, the coating composition disclosed in Patent Document 1 or 2 does not have sufficient adhesion between the obtained coating film and the top coating film, so that even if the adhesion is improved, the workability may be reduced. there were.
Japanese Patent Laid-Open No. 10-330685 JP 2000-178758 A

  In order to solve the problems of the prior art as described above, the present invention is for signboards or interiors using a paint for precoat metal that is excellent in paint stability, paint film hardness, processability, corrosion resistance, and adhesion to UV ink paint film. It is an object of the present invention to provide a multilayer composite board for signboards or interior boards obtained by using the method for forming a paint film for boards and the method for forming a paint film for signboards or interior boards.

The present inventors apply a precoat metal paint having a specific composition on a metal plate or a paint film formed by applying a primer paint on the metal plate to form a paint film. The present inventors have found that the above-mentioned problems can be solved by a coating film forming method including coating a UV ink that is cured by irradiation of the above to form a coating film, and have completed the present invention.
Therefore, the present invention relates to the following matters.

1. On the metal plate, with or without a primer coating, a precoat metal paint having the following composition is applied to form a coating, and then UV ink that is cured by irradiation of ultraviolet rays is applied to the coating. A method for forming a coating film for a signboard or an interior board, comprising coating to form a coating film.
Precoat metal paint: hydroxyl group-containing resin (A) 60 to 95 parts by mass, amino resin and / or blocked isocyanate compound 5 to 40 parts by mass, and hydroxyl group-containing resin (A) and crosslinking agent ( A coating material containing 0.1 to 30 parts by mass of an epoxidized polybutadiene resin (C) having a number average molecular weight of 500 to 10,000 with respect to 100 parts by mass of the total solid content of B).

  2. The coating film forming method for signboards or interior boards according to the above 1, wherein the hydroxyl group-containing resin (A) is a hydroxyl group-containing polyester resin having a hydroxyl value of 1 to 100 mgKOH / g.

3. A signboard or interior comprising at least a metal plate, a coating film formed by coating a paint for a precoat metal having the following composition, and a coating film formed by coating a UV ink cured by irradiation with ultraviolet rays Multi-layer composite board for board.
Precoat metal paint: hydroxyl group-containing resin (A) 60 to 95 parts by mass, amino resin and / or blocked isocyanate compound 5 to 40 parts by mass, and hydroxyl group-containing resin (A) and crosslinking agent ( The coating material which contains 0.1-30 mass parts of epoxidized polybutadiene resin (C) of the number average molecular weight 500-10,000 with respect to 100 mass parts of solid content total of B).

  4). 4. The multilayer composite board for signboard or interior board according to 3 above, wherein the hydroxyl group-containing resin (A) is a hydroxyl group-containing polyester resin having a hydroxyl value of 1 to 100 mgKOH / g.

  5. The multilayer composite board for signboards or interior boards described in 3 or 4 above, which has a primer coating.

  6). The said primer coating film is formed between the said metal plate and the coating film formed by coating the said coating material for precoat metals, For the signboard or interior board in any one of said 3-5 Multi-layer composite board.

  7). The multilayer composite plate for signboards or interior plates according to any one of the above 3 to 6, wherein the metal plate is made of aluminum or iron.

  By the coating film forming method of the present invention, a multilayer composite board for signboards or interior boards excellent in coating film hardness, processability, corrosion resistance and UV ink coating film adhesion can be obtained.

  Hereinafter, preferred embodiments of the present invention will be described. However, it should be understood that the present invention is not limited to these embodiments, and various modifications can be made within the spirit and scope of the present invention.

Object to be coated:
Examples of the metal plate to be coated include iron, aluminum alloy, brass, copper plate, stainless steel plate, tin plate, galvanized steel plate, alloyed zinc (Zn-Al, Zn-Ni, Zn-Fe, etc.) plated steel plate, Examples thereof include metal plates such as aluminum-plated steel plates, and surface-treated metal plates obtained by subjecting the surfaces of these metal plates to chemical conversion treatment such as phosphate treatment and chromate treatment.

  “Metal plate / adhesive layer / resin layer”, “metal plate / adhesive layer / resin layer / adhesive layer / metal plate” having a metal plate on the outermost layer on one or both sides in addition to the above metal plate A metal resin composite plate having a layer structure such as the above can be used.

  In addition, a metal resin composite plate in which the surface of a non-metallic substance such as a resin is coated with a metal layer by vapor deposition or the like can be used as an object to be coated. Further, by melting the resin and sandwiching it between the metal resin composite plates, What is referred to as “plate / resin layer / metal plate” can also be used as an article to be coated.

  From the viewpoint of light weight and durability, a metal plate is provided on the outermost layer on one or both sides, “metal plate / adhesive layer / resin layer”, “metal plate / adhesive layer / resin layer / adhesive layer / A metal resin composite plate having a layer structure such as “metal plate” is preferably used, and an aluminum plate is more preferable as the metal plate.

Primer paint:
A primer coating film is formed on the metal plate as necessary. Examples of the primer coating used to form a primer coating on a metal plate to be coated include primer coatings such as epoxy resin and polyester resin. The thickness of the primer coating is usually 1 to 20 μm, preferably 2 to 10 μm.

Pre-coated metal paint:
The coating material for precoat metal used for the coating film forming method and the multilayer composite plate of the present invention comprises 60 to 95 parts by mass of a hydroxyl group-containing resin (A), a crosslinking agent (B) 5 to 40 which is an amino resin and / or a blocked isocyanate compound. 0.1-30 mass parts of epoxidized polybutadiene resin (C) with a number average molecular weight of 500-10,000 with respect to 100 mass parts of solid content total of a mass part and hydroxyl-containing resin (A) and a crosslinking agent (B). Parts.

Hydroxyl-containing resin (A):
As an example of hydroxyl-containing resin (A), 1 type (s) or 2 or more types, such as a polyester resin, an epoxy resin, an acrylic resin, a fluororesin, can be mentioned. Especially, a polyester resin can be used conveniently.

  Examples of the polyester resin include oil-free polyester resins, oil-modified alkyd resins, and modified products of these resins, such as urethane-modified polyester resins, urethane-modified alkyd resins, epoxy-modified polyester resins, and acrylic-modified polyester resins. . The polyester resin has a number average molecular weight of 1,500 to 35,000, preferably 2,000 to 25,000, a glass transition temperature of -30 ° C to 100 ° C, preferably 20 ° C to 80 ° C, and a hydroxyl value of 1 to 100 mgKOH / g, preferably 5-80 mg KOH / g.

Here, the number average molecular weight is a standard polystyrene calibration curve by gel permeation chromatography (GPC) at 40 ° C. and a flow rate of 1.0 ml / min using tetrahydrofuran for GPC as an eluent according to JIS K0214-83. It was measured using.
The glass transition temperature is obtained by differential scanning thermal analysis (DSC).

  The oil-free polyester resin may be an esterified product of a polybasic acid component and a polyhydric alcohol component. Examples of the polybasic acid component include one selected from phthalic anhydride, isophthalic acid, terephthalic acid, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, succinic acid, fumaric acid, adipic acid, sebacic acid, maleic anhydride, and the like. Ester-forming derivatives such as the above dibasic acids and lower alkyl esterified products of these acids and acid anhydrides can be mainly used, and benzoic acid, crotonic acid, pt-butylbenzoic acid, etc. A tribasic or higher polybasic acid such as monobasic acid, trimellitic anhydride, methylcyclohexytricarboxylic acid, pyromellitic anhydride can be used in combination.

  Examples of the polyhydric alcohol component include ethylene glycol, diethylene glycol, propylene glycol, 1,4-butanediol, neopentyl glycol, 3-methylpentanediol, 1,4-hexanediol, 1,6-hexanediol, and the like. A trihydric or higher polyhydric alcohol such as glycerin, trimethylolethane, trimethylolpropane, or pentaerythritol can be used in combination as needed. These polyhydric alcohols can be used alone or in admixture of two or more.

  The esterification or transesterification reaction of both components can be carried out by a method known per se. Here, as the acid component, it is particularly preferable to use isophthalic acid, terephthalic acid, and lower alkyl esterified products of these acids.

  The alkyd resin is obtained by reacting an oil fatty acid with a method known per se in addition to the acid component and the alcohol component of the oil-free polyester resin. Examples of the oil fatty acid include coconut oil fatty acid and soybean oil fatty acid. Linseed oil fatty acid, safflower oil fatty acid, tall oil fatty acid, dehydrated castor oil fatty acid, tung oil fatty acid and the like. The oil length of the alkyd resin is preferably 30% or less, particularly about 5 to 20%.

  As the urethane-modified polyester resin, the oil-free polyester resin, or a low molecular weight oil-free polyester resin obtained by reacting an acid component and an alcohol component used in the production of the oil-free polyester resin, a polyisocyanate compound and Examples thereof include those reacted by a method known per se.

  Further, the urethane-modified alkyd resin is obtained by reacting a polyisocyanate compound with a low molecular weight alkyd resin obtained by reacting each component used in the production of the alkyd resin or the alkyd resin, a polyester resin or an alkyd. The thing which added and reacted the polyisocyanate compound at the time of manufacture of resin is mentioned.

  Polyisocyanate compounds that can be used in the production of urethane-modified polyester resins and urethane-modified alkyd resins include hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, tolylene diisocyanate, 4,4′-diphenylmethane diisocyanate, 4,4 ′. -Methylenebis (cyclohexyl isocyanate), 2,4,6-triisocyanatotoluene and the like. Generally as said urethane modified resin, the thing of the modification degree from which the quantity of the polyisocyanate compound which forms urethane modified resin becomes the quantity of 30 mass% or less with respect to urethane modified resin can be used conveniently.

  As the epoxy-modified polyester resin, a polyester resin produced from each component used in the production of the polyester resin is used. A reaction product between the carboxyl group of the resin and an epoxy group-containing resin, or a hydroxyl group and an epoxy resin in the polyester resin are used. A reaction product obtained by a reaction such as addition, condensation, or grafting between a polyester resin and an epoxy resin, such as a product in which a hydroxyl group therein is bonded via a polyisocyanate compound, can be mentioned. In general, the degree of modification in the epoxy-modified polyester resin is preferably such that the amount of the epoxy resin is 0.1 to 30% by mass with respect to the epoxy-modified polyester resin.

  As the acrylic-modified polyester resin, a polyester resin produced from each component used in the production of the polyester resin is used, and a group having reactivity with these groups on the carboxyl group or hydroxyl group of the resin, for example, carboxyl group, hydroxyl group or Reaction products obtained with an acrylic resin containing an epoxy group, or a reaction product obtained by graft polymerization of a (meth) acrylic acid or (meth) acrylic acid ester to a polyester resin using a peroxide polymerization initiator Can be mentioned. In general, the degree of modification in the acrylic-modified polyester resin is preferably such that the amount of the acrylic resin is 0.1 to 50% by mass with respect to the acrylic-modified polyester resin. Of the polyester resins described above, oil-free polyester resins and epoxy-modified polyester resins are particularly suitable from the viewpoints of processability and corrosion resistance.

  Examples of the epoxy resin include bisphenol-type epoxy resins, novolac-type epoxy resins, and modified epoxy resins obtained by reacting various modifiers with epoxy groups or hydroxyl groups in these epoxy resins. In the production of the modified epoxy resin, the timing of modification with the modifier is not particularly limited, and it may be modified in the middle of the epoxy resin production or in the final stage of the epoxy resin production.

  The bisphenol-type epoxy resin is, for example, a resin obtained by condensing epichlorohydrin and bisphenol up to a high molecular weight in the presence of a catalyst such as an alkali catalyst as necessary, epichlorohydrin and bisphenol, if necessary, an alkali catalyst In the presence of such a catalyst, any of resins obtained by condensation to form a low molecular weight epoxy resin and a polyaddition reaction of the low molecular weight epoxy resin and bisphenol may be used.

  Examples of the bisphenol include bis (4-hydroxyphenyl) methane [bisphenol F], 1,1-bis (4-hydroxyphenyl) ethane, 2,2-bis (4-hydroxyphenyl) propane [bisphenol A], 2, 2-bis (4-hydroxyphenyl) butane [bisphenol B], bis (4-hydroxyphenyl) -1,1-isobutane, bis (4-hydroxy-tert-butylphenyl) -2,2-propane, p- ( 4-hydroxyphenyl) phenol, oxybis (4-hydroxyphenyl), sulfonylbis (4-hydroxyphenyl), 4,4′-dihydroxybenzophenone, bis (2-hydroxynaphthyl) methane, and the like. A, bisphenol F is preferably usedThe above bisphenols can be used alone or as a mixture of two or more.

  As a commercial item of bisphenol type epoxy resin, for example, Epicoat 828, 812, 815, 820, 834, 1001, 1004, 1007, 1007, 1009, 1010 (above, manufactured by Japan Epoxy Resin, (Trade name); Araldite AER6099 (trade name, manufactured by Asahi Ciba); and Epomic R-309 (trade name, manufactured by Mitsui Chemicals, Inc.).

  Examples of the novolak type epoxy resin include various novolak type epoxy resins such as a phenol novolak type epoxy resin, a cresol novolak type epoxy resin, and a phenol glyoxal type epoxy resin having a large number of epoxy groups in the molecule. it can.

  Examples of the modified epoxy resin include an epoxy ester resin obtained by reacting, for example, a dry oil fatty acid with the bisphenol type epoxy resin or novolak type epoxy resin; and a polymerizable unsaturated monomer component containing acrylic acid or methacrylic acid. An epoxy acrylate resin; a polyester-modified epoxy resin reacted with a polyester resin; a urethane-modified epoxy resin reacted with an isocyanate compound; an amine compound in an epoxy group in the bisphenol-type epoxy resin, novolak-type epoxy resin or the various modified epoxy resins. And an amine-modified epoxy resin obtained by introducing an amino group or a quaternary ammonium salt.

Crosslinking agent (B):
The crosslinking agent (B) can be used without particular limitation as long as it can react with the hydroxyl group-containing resin (A) by heating to cure the resin, and among them, an amino resin and a blocked polyisocyanate can be used. At least one selected from compounds can be suitably used as a crosslinking agent.

  Examples of the amino resin include methylolated amino resins obtained by reaction of amino components such as melamine, urea, benzoguanamine, acetoguanamine, steroguanamine, spiroguanamine, dicyandiamide and the aldehyde. Examples of the aldehyde used in the reaction include formaldehyde, paraformaldehyde, acetaldehyde, and benzaldehyde. Moreover, what etherified the said methylolated amino resin with suitable alcohol can also be used as an amino resin. Here, examples of alcohol used for etherification include methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, 2-ethylbutanol, 2-ethylhexanol and the like.

  The blocked polyisocyanate compound that can be used as the crosslinking agent (B) is a compound obtained by blocking free isocyanate groups of a polyisocyanate compound with a blocking agent.

  Examples of the polyisocyanate compound before blocking include aliphatic diisocyanates such as hexamethylene diisocyanate or trimethylhexamethylene diisocyanate; cyclic aliphatic diisocyanates such as hydrogenated xylylene diisocyanate or isophorone diisocyanate; tolylene diisocyanate or 4 Organic diisocyanates such as aromatic diisocyanates such as 4,4'-diphenylmethane diisocyanate itself, adducts of these organic diisocyanates with polyhydric alcohols, low molecular weight polyester resins, water, etc., or organic diisocyanates as described above And cyclized polymers, and isocyanate / biuret bodies.

  Examples of the blocking agent for blocking the isocyanate group include phenols such as phenol, cresol and xylenol; ε-caprolactam; lactams such as δ-valerolactam and γ-butyrolactam; methanol, ethanol, n-, i- or Alcohols such as t-butyl alcohol, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monoethyl ether, propylene glycol monomethyl ether, benzyl alcohol; formamidoxime, acetaldoxime, acetoxime, methyl ethyl ketoxime, diacetyl monooxime, benzophenone Oximes such as oxime and cyclohexane oxime; dimethyl malonate, diethyl malonate, ethyl acetoacetate, It can be suitably used blocking agent such as active methylene such as cetyl acetone.

  By mixing the polyisocyanate compound and the blocking agent, free isocyanate groups of the polyisocyanate compound can be easily blocked.

  It is a coating film that the said hydroxyl-containing resin (A) is 65-95 mass parts, Preferably it is 70-90 mass parts, and a crosslinking agent (B) is 5-35 mass parts, Preferably it is 10-30 mass parts. It is preferable from the viewpoints of hardness, workability and corrosion resistance.

Epoxidized polybutadiene resin (C):
The precoat metal paint used in the coating film forming method for a signboard or interior board of the present invention needs to contain an epoxidized polybutadiene resin (C) in order to improve adhesion to UV ink. The epoxidized polybutadiene resin (C) usually uses 3 to 12 moles, preferably 5 to 8 moles of oxirane groups per 1 kg of the resin, utilizing functional groups such as double bonds, hydroxyl groups and carboxyl groups in the liquid polybutadiene resin. It may be a resin having a number average molecular weight of 500 to 10,000, preferably 1,000 to 4,000, contained in a molar amount.

  Specific examples of the epoxidized polybutadiene resin (C) include, for example, R-45EPI, R-15EPI (trade name, manufactured by Idemitsu Petrochemical Co., Ltd.), E-1000-8, E-1800-6.5, E -1000-3.5, E-700-6.5 (trade name, manufactured by Nippon Petrochemical Co., Ltd.), BF-1000 (trade name, manufactured by Adeka Argus), and the like.

  As a blending ratio of the epoxidized polybutadiene resin (C), the epoxidized polybutadiene resin (C) is 0.1 to 30 masses per 100 mass parts in total of the solid content of the hydroxyl group-containing resin (A) and the crosslinking agent (B). Part, preferably 1 to 15 parts by weight, more preferably 3 to 10 parts by weight, from the viewpoints of adhesion to the UV ink coating film and paint stability.

  In addition to the hydroxyl group-containing resin (A), the crosslinking agent (B) and the epoxidized polybutadiene resin (C), the precoat metal coating material may further contain a curing catalyst as appropriate. The curing catalyst is blended as necessary to promote the reaction between the hydroxyl group-containing resin (A) and the crosslinking agent (B), and when the crosslinking agent (B) is an amino resin, A sulfonic acid compound or an amine neutralized product of a sulfonic acid compound is preferably used.

  Representative examples of the sulfonic acid compound include p-toluenesulfonic acid, dodecylbenzenesulfonic acid, dinonylnaphthalenesulfonic acid, dinonylnaphthalenedisulfonic acid, and the like. The amine in the amine neutralized product of the sulfonic acid compound may be any of primary amine, secondary amine, and tertiary amine. Among these, an amine neutralized product of p-toluenesulfonic acid and / or an amine neutralized product of dodecylbenzenesulfonic acid is preferable from the viewpoints of coating stability, reaction promoting effect, and obtained coating film properties.

  When the crosslinking agent (B) is a blocked polyisocyanate compound, the curing catalyst includes tin octylate, dibutyltin di (2-ethylhexanoate), dioctyltin di (2-ethylhexanote), dioctyl. Mention may be made of organometallic compounds such as tin diacetate, dibutyltin dilaurate, dibutyltin oxide, monobutyltin trioctate, lead 2-ethylhexanoate and zinc octylate.

  The usage-amount of a curing catalyst is 0.1-5.0 mass parts with respect to 100 mass parts of total solid content of a hydroxyl-containing resin (A) and a crosslinking agent (B), Preferably it is 0.2-1.5. A mass part is suitable for curability and moldability.

  In the coating film forming method for signboards or interior boards of the present invention, generally, on a metal plate or on a primer coating film formed by coating a primer paint so that the dry film thickness is 2 to 10 μm. The precoat metal coating composition is applied with a roll coater or the like so that the dry film thickness is about 2 to 30 μm, and the maximum material temperature (PMT) is 160 to 250 ° C. within the range of 15 to 180 seconds, particularly PMT 180 to A coating film is preferably formed by baking and drying at 230 ° C. for 20 to 120 seconds.

UV ink:
In the method for forming a coating film of the present invention, a coating film is formed by further applying UV ink on the coating film for precoat metal so that the dry film thickness becomes 1 to 10 μm. The UV ink is an ink that is cured by irradiation with ultraviolet rays containing an ultraviolet curable resin, a photopolymerization initiator, and a pigment.

  Here, examples of the ultraviolet curable resin include urethane (meth) acrylate, epoxy (meth) acrylate, and polyester (meth) acrylate. Urethane (meth) acrylate is a reaction product obtained by further reacting a hydroxyl group-containing (meth) acrylate with a reaction product of a polyol and a polyisocyanate. Polyester (meth) acrylate is a dehydration condensate of polyester polyol and (meth) acrylic acid. Epoxy (meth) acrylates include those obtained by addition reaction of unsaturated carboxylic acids such as (meth) acrylic acid to epoxy resins, and epoxy (meth) acrylates of bisphenol A type epoxy resins, phenol or cresol novolac type epoxy resins Epoxy (meth) acrylate, and diglycidyl ether (meth) acrylate of polyether.

  Examples of the photopolymerization initiator include 2,2-dimethoxy-2-phenylacetophenone, acetophenone, benzophenone, xanthone, fluorenone, benzaldehyde, fluorene, anthraquinone, triphenylamine, carbazole, 3-methylacetophenone, 4-chlorobenzophenone, 4,4′-dimethoxybenzophenone, 4,4′-diaminobenzophenone, Michler's ketone, benzoin propyl ether, acetophenone diethyl ketal, benzoin ethyl ether, 1-hydroxycyclohexyl phenyl ketone, benzyldimethyl ketal, 1- (4-isopropylphenyl)- 2-hydroxy-2-methylpropan-1-one, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 2,4,6-tri And chill benzoyl diphenyl phosphine oxide, may be mentioned thioxanthone-based compounds and the like.

  In order to promote the photopolymerization reaction by the photopolymerization initiator, a photosensitization accelerator may be used in combination with the photopolymerization initiator. For example, tertiary amines, alkylphosphines such as triphenylphosphine, β-thio A thioether photosensitizer such as diglycol can be added.

  Examples of the pigment include inorganic pigments such as carbon black, titanium dioxide, zinc white and other pigments, MIO, zinc chromate, strontium chromate, aluminum tripolyphosphate, zinc, alumina, glass, mica, but are not limited thereto. It is not a thing.

Further additives include antioxidants, colorants, light stabilizers, UV absorbers, silane coupling agents, thermal polymerization inhibitors, leveling agents, storage stabilizers, plasticizers, solvents, anti-aging agents, and wettability improvers. Additives such as can also be blended. Moreover, on the UV ink coating film, a clear coating is appropriately applied so that the dry film thickness is 1 to 10 μm, and ultraviolet rays are applied with an energy dose of 1 to 10 mJ / m ² , preferably ² to 5 mJ / m ² . Irradiation may form a film.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. However, the present invention is not limited to the following examples unless it exceeds the gist. In the following examples, both “parts” and “%” are based on mass.

Production Example 1 Paint No. 1 for precoat metal Production of Resin No. 1 shown below 1 part 75 parts (solid content), Cymel 303 25 parts (solid content), R-45EPI 5 parts (solid content), Nure Cure 5225 0.6 parts (solid content), titanium white 70 parts, carbon black 2 parts and an organic solvent were mixed in a predetermined amount, and a pre-coated metal paint No. having a viscosity of 80 seconds (Ford Cup # 4, 25 ° C.) was used. 1 was obtained.

Production Examples 2 to 7 Precoat metal paint No. Production of Pre-Coated Metal Paint No. 2 in the same manner as in Production Example 1 except that the contents of Table 1 were used. 2-7 were obtained.

Resin No. 1: Oil-free polyester resin having a number average molecular weight of 18,000 and a glass transition temperature (Tg) of 0 ° C. 2: Oil-free polyester resin having a number average molecular weight of 9,000 and a glass transition temperature (Tg) of 25 ° C. Cymel 303: Nippon Cytec Industries, Ltd., trade name, methyl etherified melamine resin , Trade name, hexamethylene diisocyanate-based blocked polyisocyanate compound R-45EPI: manufactured by Idemitsu Petrochemical Co., Ltd., trade name, epoxidized polybutadiene resin, number average molecular weight 3,000
R-15EPI: Idemitsu Petrochemical Co., Ltd., trade name, epoxidized polybutadiene resin, number average molecular weight 1,000
E-1000-8: Nippon Petrochemical Co., Ltd., trade name, epoxidized polybutadiene resin, number average molecular weight 1,000
BF-1000: manufactured by Adeka Argus, trade name, epoxidized polybutadiene resin, number average molecular weight 1,000
NACURE 5225: King Industries, Inc. (USA), trade name, amine neutralized solution of dodecylbenzenesulfonic acid Scat-24: Sansha Co., Ltd., trade name, dibutyltin dilaurate

Comparative Production Examples 1 to 4 Precoat Metal Paint No. Production of pre-coated metal No. 8 to 11 in the same manner as in Production Example 1 except that the contents of Table 2 were used. 8 to 11 were obtained.

Examples 1-7 and Comparative Examples 1-4
On a hot-dip galvanized steel sheet with a thickness of 0.5 mm x 70 mm x 150 mm subjected to chromate treatment, KP Color 8630 primer manufactured by Kansai Paint Co., Ltd. ) Was coated so that the dry film thickness was about 4 μm, and baked for 30 seconds so that the maximum material reached temperature was 220 ° C. to obtain a primer-coated steel sheet.

On this primer-coated steel sheet, the precoat metal paint No. 1 obtained in the above production example and comparative production example was used. 1 to 11 were coated by a roller curtain coating method so that the dry film thickness was about 15 μm, and baked for 70 seconds so that the maximum material temperature reached 235 ° C., to obtain “precoated metal coated steel sheet”. Next, the following UV ink was applied onto this coating film so that the dry film thickness was about 5 μm, and a coating was formed by irradiation with a dose of 5 mJ / m ² .
UV ink: UV ink that contains an acrylic monomer, a photopolymerization initiator, and a pigment, and is polymerized and cured by a radical reaction upon irradiation with ultraviolet rays.

Example 8
Except for using a galvanized steel sheet having a thickness of 0.5 mm × 70 mm × 150 mm subjected to chromate treatment, an aluminum alloy (3000 series) subjected to anodization treatment having a thickness of 0.12 mm × 200 mm × 300 mm was used. A film was formed in the same manner as in Example 1.

Comparative Example 5
Except for using a galvanized steel sheet having a thickness of 0.5 mm × 70 mm × 150 mm subjected to chromate treatment, an aluminum alloy (3000 series) subjected to anodization treatment having a thickness of 0.12 mm × 200 mm × 300 mm was used. A film was formed in the same manner as in Comparative Example 1.
Each test plate thus obtained was subjected to a test according to the following test conditions. Table 3 shows the test results of the examples and Table 4 shows the test results of the comparative examples.

Paint stability: Each paint was put in a container, sealed and stored at 30 ° C. for 4 weeks, and the state of the paint was evaluated according to the following criteria.
○: almost no increase in viscosity is observed, and no phase separation is observed Δ: considerable increase in viscosity is observed, but no phase separation is observed ×: at least one of significant increase in viscosity and phase separation is observed.

  Pencil hardness: About the coating film of a test board, the pencil scratch test prescribed | regulated to JISK5600-5-4 (1999) was done, and the evaluation by the tear of a coating film was performed.

Workability: In a room at 20 ° C., 0T bending was performed by bending the coated plate surface outward with a coating plate surface outside, and bending the painted plate 180 degrees in a vise without sandwiching anything inside. When the coating plate is folded, the coating plate surface of the coating plate is bent outside in a room at 0 ° C, and two spacers with the same thickness as the coating plate are sandwiched inside. The coating state of the bent part when performing 2T bending which is bent 180 degrees with force was evaluated according to the following criteria.
◎: Abnormalities such as cracks and peelings are not observed in the coating film ○: Slight cracking is observed in the coating film △: There is considerable cracking in the coating film ×: Remarkably cracking is observed in the coating film

Corrosion resistance: The test plate used for “0T bending” in the workability test was subjected to a salt spray test. The salt spray test was performed according to JIS Z-2371, the salt spray test time was 1,000 hours, and the degree of rust generation in the processed part was evaluated according to the following criteria.
A: Generation of rust in the processed part is not recognized. O: Generation of rust is recognized in the processed part, but is less than 10% of the length of the processed part. Δ: 50% when the length is 10% or more of the processed part. The occurrence of rust is observed in less than x: The occurrence of rust is observed in 50% or more of the length of the processed part in the processed part

Adhesion: According to JIS K 5600-5-6 (1999) grid pattern-tape method, using a knife to reach the substrate on the paint film surface of the paint plate, parallel to each other at intervals of about 1 mm. Eleven cuts were made to form a goby, and a cellophane (registered trademark) adhesive tape was attached to the surface, and the gobang eye coating surface after the tape was peeled off was evaluated according to the following criteria.
A: No peeling of the coating film is observed. ○: A slight peeling is observed in a part of the coating film at the corner of the knife scratch. Δ: One in which at least all of the UV ink has peeled out of 100 gobangs. ~ 20 x: Out of 100 gobangs, at least all of the UV ink is peeled off is 21 or more

  INDUSTRIAL APPLICABILITY The present invention is industrially useful because it can provide a precoated steel sheet for signboards or interior boards that is excellent in coating film hardness, processability, corrosion resistance, and UV ink coating film adhesion.

Claims (3)

A metal plate having a primer coating film with a thickness of 2 to 10 μm, and a coating film with a thickness of 2 to 30 μm formed by applying a pre-coating metal paint having the following composition on the primer coating film and curing by ultraviolet irradiation. A multilayer composite board for signboards or interior boards, comprising a coating film having a thickness of 1 to 10 μm formed by coating UV ink.
Precoat metal paint: hydroxyl group-containing resin (A) 60 to 95 parts by mass, amino resin and / or blocked isocyanate compound 5 to 40 parts by mass, and hydroxyl group-containing resin (A) and crosslinking agent ( The coating material which contains 0.1-30 mass parts of epoxidized polybutadiene resin (C) of the number average molecular weight 500-10,000 with respect to 100 mass parts of solid content total of B). Hydroxyl-containing resin (A) is a hydroxyl-containing polyester resin having a hydroxyl value 1~100mgKOH / g, the multilayer composite plate for signboard or for interior plate of claim 1. The multilayer composite board for signboards or interior boards according to claim 1 or 2 , wherein the metal plate is made of aluminum or iron.