JP2021130778A - Coating material for metal, metal substrate for printing obtained therefrom and manufacturing method therefor, and coated metal material - Google Patents

Abstract

To provide a coating material for metal for forming a layer to which a cured material of a metal substrate and active ray energy ray curable composition are robustly bonded, a metal substrate for printing formed using the same and its manufacturing method, and a coated metal material.SOLUTION: The coating material for metal comprises a polyester resin having a number average molecular weight of 4000 to 12000 and a melamine resin. The polyester resin comprises an alcohol structural unit derived from polyvalent alcohol and a carboxylic acid structural unit derived from a polyvalent carboxylic acid, in which a ratio of an amount of the structural units derived from alcohol of trivalent or larger with respect to a total amount of the alcohol structural unit and the carboxylic acid structural unit is 20 mol% or smaller.SELECTED DRAWING: None

Description

The present invention relates to a metal coating material, a metal base material to be printed and a method for producing the same, and a coated metal material.

In recent years, there has been a demand for a coated metal material having a high design property, and it is required to form a coating film of various colors on a metal base material and to give a fine pattern on the surface of the metal base material. .. Therefore, it has been studied to apply an active energy ray-curable composition on a metal substrate.

The active energy ray-curable composition is cured by irradiation with active energy rays. Therefore, it is possible to form an image on a base material that does not have solvent absorption. However, the active energy ray-curable composition has a relatively large shrinkage during curing. Therefore, there is a problem that the ink layer, which is a cured product of the active energy ray-curable composition, is easily peeled off from various substrates.

To solve such problems, some methods for improving the adhesion of the ink layer to the substrate have been proposed. For example, Patent Document 1 describes a method in which an active energy ray-curable composition is applied onto a substrate, irradiated with active energy rays, and then further heated by a heater. According to this method, it is considered that the adhesion between the ink layer and the base material is enhanced by increasing the curability of the ink layer. Further, Patent Document 2 describes a method of applying an active energy ray-curable composition on a preheated substrate. According to this method, it is considered that the active energy ray-curable composition can be sufficiently wetted and spread on the base material, and the adhesion between the ink layer and the base material is enhanced.

Further, it is described in Patent Documents 3 and 4 that the resin film is subjected to a corona discharge treatment before the active energy ray-curable composition is applied onto the resin film to improve the adhesion between the resin film and the ink layer. Has been done.

Japanese Unexamined Patent Publication No. 2001-09367 Japanese Unexamined Patent Publication No. 2008-0872242 International Publication No. 2018/163941 Japanese Unexamined Patent Publication No. 9-300747

However, when the active energy ray-curable composition is applied onto the metal base material, the adhesion between the metal base material and the ink layer is sufficiently enhanced regardless of any of the methods of Patent Documents 1 to 4. Was difficult. Further, in particular, when the coating thickness of the active energy ray-curable composition is increased, the amount of curing shrinkage generated during curing increases, and the ink layer is more easily peeled off.

Therefore, the present invention relates to a metal coating material for forming a layer for firmly adhering a metal base material and a cured product of an active ray energy ray-curable composition, a metal base material to be printed formed by using the metal base material, and a metal base material to be printed. The purpose is to provide a manufacturing method and a coated metal material.

The present invention provides the following metallic paints.
A metal coating material containing a polyester resin having a number average molecular weight of 4000 to 12000 and a melamine resin, wherein the polyester resin has an alcohol structural unit derived from a polyhydric alcohol and a carboxylic acid structure derived from a polyvalent carboxylic acid. A metal coating material comprising a unit and, wherein the ratio of the amount of the structural unit derived from a trihydric or higher alcohol to the total amount of the alcohol structural unit and the carboxylic acid structural unit is 20 mol% or less.

The present invention provides the following metal substrates for printing.
A metal base material to be printed, which comprises a metal base material and a layer to be printed, which is a cured product of the paint for metal, which is arranged on the metal base material.

The present invention provides the following coated metal materials.
A coated metal material having the metal substrate for printing and an ink layer which is a cured product of an active energy ray-curable composition arranged on the layer to be printed.

The present invention provides the following method for producing a metal substrate for printing.
Production of a metal substrate to be printed, which comprises a step of applying the above-mentioned metal paint on a metal substrate to form a layer to be printed, and a step of performing a frame treatment or a corona discharge treatment on the layer to be printed. Method.

According to the metal coating material of the present invention, a layer to be printed having high adhesion to an ink layer can be formed on a metal base material. Therefore, it is possible to form various layers with high designability on various metal substrates by using the active energy ray-curable composition.

1. 1. Paints for metals and metal base materials for printing using the same As described above, it has been conventionally studied to apply an active energy ray-curable composition on a metal base material to enhance the design of the metal base material. .. However, it is difficult to improve the adhesion of the ink layer which is a cured product of the active energy ray-curable composition, and especially when the thickness of the ink layer is increased, peeling is likely to occur at these interfaces. The reason is that the active energy ray-curable composition shrinks greatly when it is cured, and residual stress is generated in the ink layer after curing, or stress is generated at the interface between the metal base material and the ink layer during curing. Therefore, it is considered that the ink layer is peeled off.

On the other hand, when the metal coating material of the present invention is applied onto a metal substrate to form a layer to be printed, and then an active energy ray-curable composition is applied to form an ink layer, the adhesion of the ink layer is formed. It became clear that it was very easy to increase. The metal coating material of the present invention includes a polyester resin having a number average molecular weight of 4000 to 12000 and a melamine resin. Then, the ratio of the amount of trihydric or higher alcohol-derived structural units to the total amount of the polyhydric alcohol-derived alcohol structural units and the polyvalent carboxylic acid-derived carboxylic acid structural units in the polyester resin is 20 mol. % Or less. Therefore, when the metal paint is applied onto the metal base material to form the print layer, the crosslink density does not become excessively high, and a relatively flexible print layer is formed. Then, when the active energy ray-curable composition is applied onto such a layer to be printed, the layer to be printed can relieve stress even if the active energy ray-curable composition shrinks during curing. Is. That is, the stress remaining in the ink layer is reduced. Further, since the layer to be printed is relatively flexible, the layer to be printed can be deformed following the curing shrinkage of the active energy ray-curable composition. Therefore, it is difficult for stress to act between the printing layer and the ink layer, and the adhesion between them can be enhanced.

Further, after forming the print layer on the metal base material, the ink layer may be formed so as to cover the entire print layer, but in general, there is a region where the ink layer is not formed on the print layer. .. Therefore, the layer to be printed is also required to have high weather resistance and the like. Here, the weather resistance of the layer to be printed obtained from the paint for metal is improved as the number average molecular weight of the polyester resin in the paint for metal is low and the crosslink density of the layer to be printed is high. However, as the crosslink density of the layer to be printed increases, the adhesion of the ink layer formed on the layer to be printed decreases, as described above. In particular, when the number average molecular weight of the polyester resin in the metal coating material is less than 4000, the crosslink density of the polyester resin and the melamine resin becomes excessively high in the obtained layer to be printed, and the above-mentioned sufficient ink adhesion is achieved. It was found that sex could not be obtained. On the other hand, when the number average molecular weight of the polyester resin exceeds 15,000, the crosslink density becomes low, so that a layer to be printed having high adhesion of the ink layer can be obtained, but it is also clear that it is difficult to obtain sufficient weather resistance of the coating film. rice field.

Therefore, by setting the number average molecular weight of the polyester resin to 4000 to 12000 and the ratio of structural units derived from polyhydric alcohol in the polyester resin to 20 mol% or less, the crosslink density of the obtained layer to be printed is adjusted. A layer to be printed having both weather resistance and ink adhesion that can be used outdoors can be obtained.

The metal paint may be used for producing a pre-coated metal plate, or may be used for producing a post-coated metal plate.

Hereinafter, the metal coating material will be described, and then the metal base material to be printed formed by using the metal coating material will be described.

(Metal paint)
The metal coating material of the present invention may contain a polyester resin having a specific structure and molecular weight and a melamine resin, and if necessary, contains other components such as a catalyst, an amine, an extender pigment, and a coloring pigment. You may be.

The polyester resin is a resin having a plurality of ester structures in the molecular chain, and is a resin containing a carboxylic acid structural unit derived from a polyvalent carboxylic acid and an alcohol structural unit derived from a polyhydric alcohol. The polyester resin can usually be prepared by polymerizing a polyvalent carboxylic acid and a polyhydric alcohol.

Here, examples of polyvalent carboxylic acids include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid, and 2,7-naphthalenedicarboxylic acid, and anhydrides thereof; succinic acid. , Adipic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, aliphatic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid and anhydrides thereof; lactones such as γ-butyrolactone and ε-caprolactone; trimellitic acid, trimedin. Trivalent or higher valent carboxylic acids such as acids and pyromellitic acids; etc. are included. The polyester resin may contain only one type of carboxylic acid structural unit derived from the polyvalent carboxylic acid, or may contain two or more types. The ratio of the amount of trivalent or higher polyvalent carboxylic acid-derived structural units to the total amount of polyhydric alcohol-derived alcohol structural units and polyvalent carboxylic acid-derived carboxylic acid structural units in the polyester resin is applied. In order to prevent the cross-linking density of the film from becoming excessively high, it is preferably 5 mol% or less, more preferably 2 mol% or less.

On the other hand, examples of polyhydric alcohols include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1, 2-Pentanediol, 1,4-Pentanediol, 1,5-Pentanediol, 2,3-Pentanediol, 1,4-Hexanediol, 2,5-Hexanediol, 1,5-Hexanediol, 1,6 -Hexanediol, 3-methyl-1,5-pentanediol, 2-methyl-1,3-propanediol, diethylene glycol, triethylene glycol, 1,2-dodecanediol, 1,2-octadecanediol, neopentyl glycol, Glycols such as 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, bisphenol A alkylene oxide adduct, bisphenol S alkylene oxide adduct; trihydric or higher polyhydric alcohols such as trimethylpropane, glycerin, pentaerythritol, etc. Kind etc. are included. The polyester resin may contain only one type of alcohol structural unit derived from the polyhydric alcohol, or may contain two or more types.

However, the ratio of the trivalent or higher alcohol-derived structural unit to the total amount of the carboxylic acid structural unit and the alcohol structural unit in the polyester resin contained in the metal coating material is 20 mol% or less. The proportion of the trihydric or higher alcohol-derived structural unit is more preferably 15 mol% or less, still more preferably 10 mol% or less. When the amount of the trivalent or higher alcohol-derived structural unit exceeds 20 mol%, the three-dimensional crosslinked structure increases when the polyester resin is crosslinked with the melamine resin described later. As a result, the obtained layer to be printed tends to be hard, and the adhesion to the ink layer tends to be low. When the polyester resin contains a structural unit derived from a trihydric or higher alcohol, it preferably contains a structural unit derived from trimethylolpropane. When the polyester resin contains an alcohol structural unit derived from trimethylolpropane, the crosslink density of the coating film becomes more stable, so that adhesion to the ink layer can be easily obtained.

The number average molecular weight of the polyester resin is 4000 to 12000, more preferably 5000 to 11000. The number average molecular weight of the polyester resin is a styrene equivalent value specified by gel permeation chromatography (GPC). When the number average molecular weight of the polyester resin is 4000 or more, the strength of the obtained layer to be printed tends to increase, and the weather resistance and processability of the layer to be printed tend to be improved. On the other hand, when the number average molecular weight of the polyester resin is 12000 or less, the adhesion between the printing layer and the ink layer tends to be good.

The hydroxyl value of the polyester resin is preferably 5 to 100 mgKOH / g, more preferably 10 to 70 mgKOH / g. The hydroxyl value is specified by the potentiometric titration method specified by JIS K0070 using a 0.5 mol / L KOH alcohol solution. When the hydroxyl value of the polyester resin is within the above range, the OH groups on the surface of the metal base material and the OH groups in the polyester resin (printed layer) are likely to form hydrogen bonds, and the metal base material and the printed layer are in close contact with each other. Increases sex. Similarly, the OH groups in the polyester resin (printed layer) are likely to hydrogen bond with the hydrophilic groups in the ink layer, and their adhesion is further enhanced.

The glass transition temperature of the polyester resin is preferably 0 to 100 ° C, more preferably 20 to 70 ° C. When the glass transition temperature of the polyester resin is in the above range, the processability of the obtained layer to be printed becomes good.

On the other hand, the melamine resin contained in the metal coating material is not particularly limited, but methylated melamine resin such as methylol melamine methyl ether; butylated melamine resin such as methylol melamine butyl ether; mixed etherified melamine resin of methyl and n-butyl, etc. included. The metal coating material may contain only one type of melamine resin, or may contain two or more types of melamine resin. Among the above, a methylated melamine resin, a butylated melamine resin, and a combination thereof are preferable, and a methylated melamine resin is particularly preferable. Excessive addition of the butylated melamine resin may result in an excessive crosslink density on the surface layer of the coating film.

The ratio (mass ratio) of the polyester resin and the melamine resin contained in the metal coating material is preferably 90: 10 to 60:40, more preferably about 85: 15 to 65:35. When the mass ratio of the polyester resin and the melamine resin is in the above range, a layer to be printed having excellent weather resistance and impact resistance can be obtained.

The total amount of the polyester resin and the melamine resin with respect to 100 parts by mass of the solid content of the metal coating material is preferably 30 to 80 parts by mass, more preferably 50 to 70 parts by mass. When the total amount of the polyester resin and the melamine resin is within the above range, the strength of the layer to be printed obtained from the metal coating material tends to be sufficiently increased. Further, the adhesion between the printing layer and the ink layer tends to be good.

The metallic paint may further contain a catalyst. Examples of catalysts include dodecylbenzene sulphonic acid, paratoluene sulphonic acid, benzenesulphonic acid and the like. The amount of the catalyst used is preferably 0.1 to 8% by mass with respect to the total solid content of the metal coating material.

In addition, the metallic paint may further contain amines. Amine is a compound for neutralizing a catalytic reaction, and examples thereof include triethylamine, dimethylethanolamine, dimethylaminoethanol, monoethanolamine, isopropanolamine and the like. The amount of amine used is not particularly limited, but is preferably 50 mol% or more of the acid (catalyst) equivalent.

Further, the metal coating material may further contain an extender pigment (including beads), a coloring pigment and the like. Examples of extender pigments include silica, calcium carbonate, barium sulfate, aluminum hydroxide, talc, mica, resin beads, glass beads and the like. Examples of resin beads include acrylic resin beads, polyacrylonitrile beads, polyethylene beads, polypropylene beads, polyester beads, urethane resin beads, epoxy resin beads and the like.

These resin beads may be manufactured by a known method, or a commercially available product may be used. Examples of commercially available acrylic resin beads include "Tuftic AR650S (average particle size 18 μm)", "Tuftic AR650M (average particle size 30 μm)", "Tuftic AR650MX (average particle size 40 μm)", and "Tuftic AR650MZ". (Average particle size 60 μm) ”,“ Toughtic AR650ML (average particle size 80 μm) ”,“ Toughtic AR650L (average particle size 100 μm) ”and“ Toughtic AR650LL (average particle size 150 μm) ”are included. Examples of commercially available polyacrylonitrile beads include Toyobo Co., Ltd.'s "Tuftic A-20 (average particle size 24 μm)", "Tuftic YK-30 (average particle size 33 μm)", and "Tuftic YK-50 (average grain size)". Diameter 50 μm) ”and“ Toughtic YK-80 (average particle size 80 μm) ”are included. The metal paint may contain only one kind of these, or may contain two or more kinds of these.

On the other hand, examples of colored pigments include carbon black, titanium oxide, iron oxide, yellow iron oxide, phthalocyanine blue, cobalt blue and the like. The amount of the pigment is appropriately selected according to the type of pigment, the particle size and the like. The metal paint may contain only one kind of these, or may contain two or more kinds of these.

The metallic paint may further contain a solvent, if necessary. The solvent is not particularly limited as long as it is possible to sufficiently dissolve the polyester resin and the melamine resin, and uniformly disperse the extender pigment, the coloring pigment and the like. Examples of solvents include toluene, xylene, Solvesso (registered trademark) 100 (trade name, manufactured by Exxon Mobile), Solvesso (registered trademark) 150 (trade name, manufactured by Exxon Mobile), Solvesso (registered trademark) 200 (commodity). (Name: Exxon Mobile Co., Ltd.) and other hydrocarbon solvents; methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, isophorone and other ketone solvents; ethyl acetate, butyl acetate, ethylene glycol monoethyl ether acetate and other ester solvents; methanol, isopropyl Alcohol-based solvents such as alcohol and n-butyl alcohol; ether alcohol-based solvents such as ethylene glycol monoethyl ether and diethylene glycol monobutyl ether; and the like are included. The metal paint may contain only one kind of these, or may contain two or more kinds of these. Among these, xylene, Solvesso (registered trademark) 100, Solvesso (registered trademark) 150, cyclohexanone, and n-butyl alcohol are preferable from the viewpoint of compatibility with polyester resin and melamine resin.

The method for preparing the above-mentioned metal coating material is not particularly limited, and the polyester resin, the melamine resin, and other components may be mixed by a known method, if necessary.

(Metal base material for printing)
A metal substrate for printing having a layer to be printed obtained from the above-mentioned paint for metal will be described. The metal base material to be printed has a metal base material and a layer to be printed, which is a cured product of the above-mentioned metal coating material, which is arranged on the metal base material. The metal base material to be printed is used as a base material for forming an ink layer by applying, for example, an active energy ray-curable composition described later. Further, the base material to be printed may be a pre-coated metal plate or a post-coated metal plate.

-Metal base material The metal base material may have a structure capable of forming a layer to be printed by applying the above-mentioned metal paint, and its shape is not particularly limited. For example, it may be flat or have a three-dimensional structure. Further, the metal base material may have a strip shape or the like. The thickness of the metal base material is not particularly limited, and is appropriately selected depending on the use of the coated metal material.

The material of the metal base material is not particularly limited, and is a hot-dip Zn-plated steel sheet, a hot-dip Zn-55% Al alloy-plated steel sheet, a hot-dip Zn-Al-Мg alloy-plated steel sheet, a hot-dip Al-plated steel sheet, an electric Zn-plated steel sheet, and an electric Cu. Includes galvanized steel sheets such as plated steel sheets; steel sheets such as ordinary steel sheets and stainless steel sheets; aluminum plates; copper plates and the like. A chemical conversion treatment film, an undercoat film, or the like may be formed on the surface of the metal substrate as long as the effects of the present invention are not impaired. Further, the metal base material may be subjected to uneven processing such as embossing or draw forming as long as the effect of the present invention is not impaired.

The type of chemical conversion treatment for forming the chemical conversion treatment film is not particularly limited. Examples of chemical conversion treatments include chromate treatment, chromium-free treatment, phosphate treatment and the like. The amount of the chemical conversion coating adhered is not particularly limited as long as it is within an effective range for improving the corrosion resistance.

Further, the undercoat coating film is a layer formed directly on the metal base material or on the chemical conversion treatment film to improve the adhesion of the layer to be printed and the corrosion resistance of the metal base material.

The undercoat coating film is formed by, for example, applying an undercoat coating material containing a resin to the surface of a metal base material or a chemical conversion treatment film and drying (or curing) the undercoat coating film. The type of resin contained in the undercoat paint is not particularly limited. Examples of the resin include polyester, epoxy resin, acrylic resin and the like. Epoxy resins are particularly preferable because they have high polarity and good adhesion to metal substrates. The thickness of the undercoat coating film is appropriately selected according to the intended use and type of the final coated metal material, and is, for example, about 5 μm.

-Layer to be printed The layer to be printed is a layer containing a cured product of the above-mentioned metal coating material, and is formed by applying the above-mentioned metal coating material on the above-mentioned metal base material and curing the above-mentioned metal coating material. The layer made of the cured product of the metal coating material may be used as it is as the layer to be printed, but it is more preferable that the layer further subjected to frame treatment or corona discharge treatment is used as the layer to be printed. By performing the frame treatment and the corona discharge treatment, the adhesion of the ink layer described later is remarkably enhanced, and even if a thick ink layer is formed, for example, it becomes difficult to peel off. Of these, the frame-processed layer to be printed is particularly preferable from the viewpoint of adhesion of the ink layer and the like.

The method of applying the above-mentioned metal paint on a metal base material is not particularly limited, and is appropriately selected according to the shape of the metal base material, the pattern of the layer to be printed to be formed, the area of the layer to be printed to be formed, and the like. NS. Examples of coating methods include inkjet printing, gravure printing, offset printing, screen printing, roll coating, bar coating, spin coating, air spray, airless spray, and immersion pulling. included. When applying the metal paint, two or more of these methods may be combined.

Then, after applying the metal paint on the metal base material, the metal paint is heated (hereinafter, also referred to as “baking”) and cured. The baking method is not particularly limited, but it is preferable to heat the metal base material so that the reaching plate temperature is in the range of 150 to 250 ° C.

When the layer to be printed is frame-processed after the metal paint is baked, the metal base material on which the layer to be printed is formed is placed on a conveyor such as a belt conveyor. Then, while moving in a certain direction, a flame is radiated to the layer to be printed with a burner for frame processing.

Here, the frame processing amount is preferably ^{100 to 600 kJ / m 2.} The "frame processing amount" in the present specification is the amount of heat per unit area of the metal base material calculated based on the supply amount of combustion gas such as LP gas. The frame processing amount can be adjusted by the distance between the burner head of the frame processing burner and the surface of the layer to be printed, the transport speed of the layer to be printed, and the like. When the frame processing amount is 100 kJ / m ² or more, the entire surface of the layer to be printed tends to be uniformly processed. On the other hand, when the frame processing amount is 600 kJ / m ² or less, the layer to be printed is unlikely to turn yellow.

Before the frame treatment, a preheat treatment may be performed to heat the surface of the layer to be printed to 40 ° C. or higher. When the layer to be printed formed on the surface of a metal substrate having a high thermal conductivity (for example, a metal substrate having a thermal conductivity of 10 W / mK or more) is irradiated with a flame, the water vapor generated by the combustion of the combustible gas is cooled. Becomes water and temporarily collects on the surface of the layer to be printed. Then, the water absorbs the energy during the frame treatment and becomes water vapor, which may hinder the frame treatment. On the other hand, by preheating the surface of the layer to be printed, it is possible to suppress the generation of water during flame irradiation.

The means for preheating the layer to be printed is not particularly limited, and is appropriately selected according to the shape of the metal substrate and the like. For example, a heating device generally called a drying oven can be used. For example, a batch-type drying oven (also referred to as a "safe oven") can be used, and specific examples thereof include a low-temperature thermostat manufactured by Isuzu Seisakusho Co., Ltd. (model Mini Catalina MRLV-11) and Tojo Thermostat. An automatic discharge type dryer (model ATO-101) manufactured by Tojo Thermal Science Co., Ltd. and a simple explosion-proof specification dryer (model TNAT-1000) manufactured by Tojo Thermal Science Co., Ltd. are included.

On the other hand, when the corona discharge treatment is performed on the layer to be printed, the metal base material on which the layer to be printed is formed is placed between the insulated electrode and the grounded counterpole dielectric roll. Then, a high frequency and a high voltage of 1 to 600 KHz and 5 to 30 KV are applied between them to generate a corona discharge. The corona discharge processing device includes a spark gap method, a vacuum tube method, a solid state method, and the like, and any of them can be used. Corona discharge treatment conditions, preferably 200 w / ^{m 2} / min or more, 200~800w / ^{m 2} / min is more preferred. May corona discharge treatment amount is less than 200 w / ^{m 2} / min is insufficient, and exceeding 800w / ^{m 2} / min, the process economically undesirable since excessive.

Here, the thickness of the layer to be printed is not particularly limited, but is preferably 10 to 40 μm, more preferably 12 to 25 μm, for example. When the thickness of the layer to be printed is 10 μm or more, the durability of the layer to be printed tends to be good. In addition, the layer to be printed tends to be flexible, and the adhesion of the ink layer described later tends to increase. On the other hand, when the thickness is 40 μm or less, armpits are less likely to occur during the above heating, and the surface condition tends to be good. Further, when the surface condition of the layer to be printed is good, the active energy ray-curable composition described later tends to be uniformly wetted and spread, and the adhesion between the ink layer to be printed and the layer to be printed tends to be improved.

Here, the ratio of the amount of O atoms to the amount of C atoms when the surface of the layer to be printed is analyzed by X-ray electron spectroscopy (hereinafter, also referred to as XPS method) is preferably 0.6 or more. The ratio of the amount of O atoms to the amount of C atoms is more preferably 0.8 or more. The ratio of the amount of O atoms to the amount of C atoms as measured by the XPS method can be adjusted by the above-mentioned frame treatment or corona discharge treatment. When the above-mentioned frame treatment or corona discharge treatment is performed, some organic groups on the surface of the layer to be printed are decomposed and OH groups are introduced. As a result, the amount of O atoms increases as compared with the case where the frame treatment and the corona discharge treatment are not performed. That is, the ratio of the amount of O atoms to the amount of C atoms increases. Then, the OH group is likely to hydrogen bond with the hydrophilic group in the ink layer formed on the print layer, and the adhesion between the print layer and the ink layer is likely to be high.

The analysis of the composition (amount of C atoms and O atoms) of the surface of the layer to be printed by the XPS method can be the same as the analysis by the general XPS method using AlKα as an X-ray source. For example, it can be performed with the following measuring devices and measuring conditions.
(Measuring equipment and measurement conditions)
Measuring device: AXIS-NOVA scanning X-ray photoelectron spectrometer manufactured by KRATOS X-ray source: AlKα 1486.6 eV
Analysis area 700 x 300 μm
Laboratory vacuum: 1.0 × ^10-7 Pa

As described above, the ratio of the amount of O atoms to the amount of C atoms can be increased by both the frame treatment and the corona discharge treatment. However, when the surface of the layer to be printed is treated by frame treatment, the surface can be hydrophilized more uniformly (the amount of O atoms is uniformly increased) than when the surface of the layer to be printed is treated by corona treatment. Adhesion can be improved.

Whether or not the surface of the layer to be printed is uniformly hydrophilic can be evaluated by the following methylene iodide rolling angle. For example, when the methylene iodide fall angle of the layer to be printed is 15 ° or more and 45 ° or less, it can be said that the surface is uniformly hydrophilic. The methylene iodide fall angle is more preferably 35 ° or less.

The methylene iodide fall angle tends to fall within the above range when the surface of the layer to be printed has sufficiently high hydrophilicity or when the surface of the layer to be printed has a rough surface. However, if the hydrophilicity of the layer to be printed is non-uniform, the methylene iodide fall angle will be higher than 45 °. For example, when the surface is treated by corona treatment, the methylene iodide fall angle tends to exceed 45 °. On the other hand, when the frame treatment is performed, the surface is uniformly hydrophilic and the methylene iodide rolling angle is 45 ° or less.

The reason why the methylene iodide fall angle becomes larger than 45 ° when the hydrophilicity of the surface of the layer to be printed becomes non-uniform due to the corona discharge treatment or the like is considered as follows. There are two types of coating films that have the same number of hydrophilic groups and hydrophobic groups on the surface, one with no bias in the distribution of hydrophilic groups and hydrophobic groups, and the other with a bias in the distribution of hydrophilic groups and hydrophobic groups. Suppose. At this time, the static contact angles of the two are not easily affected by the distribution of the hydrophilic group and the hydrophobic group, and are substantially the same. On the other hand, the dynamic contact angle (methylene iodide fall angle) of both depends on the distribution of hydrophilic groups and hydrophobic groups, and has different values. When measuring the fall angle of methylene iodide, if the distribution of hydrophilic groups and hydrophobic groups is non-uniform, methylene iodide droplets are adsorbed on the portion where the density of hydrophilic groups is high. That is, if the distribution of the hydrophilic group and the hydrophobic group is biased, the methylene iodide droplets become more difficult to move and the fall angle becomes larger than in the case where there is no uneven distribution. Therefore, when a large number of hydrophilic groups are introduced on the surface of the layer to be printed as in the corona discharge treatment, but the distribution is uneven, the methylene iodide tipping angle becomes a high value exceeding 45 °.

The methylene iodide tipping angle is a value measured as follows. First, 2 μl of methylene iodide is added dropwise onto the layer to be printed. Then, using a contact angle measuring device, the inclination angle of the layer to be printed (the angle formed by the plane perpendicular to gravity and the layer to be printed) is increased at a speed of 2 degrees / sec. At this time, the droplets of methylene iodide are observed by the camera attached to the contact angle measuring device. Then, the inclination angle at the moment when the droplets of methylene iodide fall is specified, and the average value of 5 times is taken as the methylene iodide fall angle of the layer to be printed. The moment when the droplet of methylene iodide falls is the moment when both the end point in the downward direction of gravity and the end point in the upward direction of gravity of methylene iodide (droplet) start to move.

2. Painted metal material The painted metal material is an active energy ray-curable composition (hereinafter, "curable composition") arranged on the above-mentioned metal substrate to be printed and the layer to be printed of the metal substrate to be printed. It also has an ink layer which is a cured product (also referred to as). The ink layer may be arranged in all the areas where the layer to be printed is formed, or may be arranged only in a part of the areas where the layer to be printed is formed.

The ink layer may be a cured product of only one type (for example, one color) of the curable composition, or may be a cured product of two or more types (for example, two or more colors) of the curable composition. The composition of the curable composition will be described later. Further, the type, arrangement area, arrangement pattern, etc. of the curable composition are appropriately selected according to the use of the coated metal material. Further, examples of active energy rays in the present specification include electron beams, ultraviolet rays, α rays, γ rays, X-rays and the like.

The method for applying the curable composition is not particularly limited, and is appropriately selected from known methods. Examples of the coating method of the curable composition include an inkjet printing method, a gravure printing method, an offset printing method, a screen printing method, a roll coating method, a bar coating method and the like. Among these, the inkjet method is preferable from the viewpoint that a multicolored pattern or a complicated pattern can be easily formed in a short time. These may be combined when applying the curable composition.

Further, the coating amount of the curable composition is not particularly limited, and it is preferable to apply the curable composition so that the thickness after curing is about 5 to 150 μm, and more preferably about 10 to 100 μm. The curable composition may be applied to the same location a plurality of times to achieve the above thickness. As described above, in general, when the amount of the curable composition applied is large, the curing shrinkage at the time of curing becomes large, and the obtained ink layer is easily peeled off. However, the metal substrate for printing (particularly when it has a frame-processed layer to be printed) has high adhesion between the layer to be printed and the ink layer to be formed, and is, for example, an ink layer having a thickness of 40 μm or more. It is difficult for peeling to occur even if the ink is formed.

The curable composition may be applied so that the thickness of the ink layer after curing changes continuously or intermittently. When layers to be printed with different thicknesses are formed on a general layer to be printed, the adhesion changes between the thick portion and the thin portion of the ink layer, and the ink layer is peeled off from the portion having low adhesion. Sometimes. On the other hand, in the above-mentioned metal base material for printing (particularly when it has a frame-processed layer to be printed), the ink layer is used regardless of whether the ink layer is thin or thick. Has high adhesion to the printed layer. Therefore, even if an ink layer having a varying thickness is formed, peeling is unlikely to occur.

After applying the curable composition, the coating film is irradiated with active energy rays to cure it. The active energy can be any of electron beam, ultraviolet ray, α ray, γ ray, and X-ray. Among these, electron beams or ultraviolet rays are preferable, and ultraviolet rays are particularly preferable, from the viewpoint of energy efficiency and the need for a large-scale device.

The amount of the active energy ray to be irradiated is appropriately selected according to the type and amount of the photopolymerization initiator and the photoacid generator in the curable composition described later. Further, the main wavelength of the active energy ray to be irradiated is also appropriately selected according to the type of the photopolymerization initiator and the photoacid generator, and can be, for example, a wavelength of 360 to 425 nm.

When a plurality of types of the curable composition are applied, each time one type of the curable composition is applied, irradiation with active energy rays may be performed. After applying the plurality of types of the curable composition, the active energy may be applied. Line irradiation may be performed.

-Curing composition The curing composition applied on the layer to be printed may be a known composition conventionally used for printing on a metal plate. The curable composition includes a radical polymerization type composition and a cationic polymerization type composition, and both can be used in the present invention.

The radical polymerization type composition can be, for example, a composition containing a photopolymerizable compound, a photopolymerization initiator, and a colorant. The photopolymerizable compound may be a compound having at least one photopolymerizable group that exhibits reactivity when irradiated with active energy rays. Examples of photopolymerizable compounds include known (meth) acrylic monomers or (meth) acrylic oligomers having 1 to 6 (meth) acryloyloxy groups. In the present specification, the description of (meth) acryloyl means either one or both of methacryloyl and acryloyl, and the description of (meth) acrylic means either one or both of methacryl and acrylic. The radical polymerization type composition may contain only one kind of photopolymerizable compound, or may contain two or more kinds of photopolymerizable compounds.

The radical polymerization type composition preferably contains the above photopolymerizable compound in an amount of 50 to 90% by mass in the solid content. When the amount of the photopolymerizable compound in the radical polymerization type composition is within the above range, the radical polymerization type composition is easily sufficiently wetted and spread on the above-mentioned layer to be printed, and the ink layer is easily adhered to the layer to be printed. ..

On the other hand, the photopolymerization initiator may be a compound capable of generating radicals by irradiation with active energy rays, and a compound having an absorption wavelength corresponding to the wavelength of the active energy rays is preferable. Examples of the photopolymerization initiator include benzophenone compounds, acetophenone compounds, thioxanthone compounds, phosphine oxide compounds and the like. In particular, since the phosphine oxide compound has an absorption wavelength of 370 nm or more, it is more preferable to add it in order to promote deep curing of the ink layer. The radical polymerization type composition may contain only one kind of photopolymerization initiator, or may contain two or more kinds of photopolymerization initiators.

The radical polymerization type composition preferably contains the above photopolymerization initiator in a solid content of 1 to 25% by mass. When the amount of the photopolymerization initiator in the radical polymerization type composition is within the above range, the photopolymerizable compound can be cured.

The type of colorant is not particularly limited, and known pigments or dyes can be used. The radical polymerization type composition preferably contains a colorant in the solid content of 0.1 to 10% by mass. The radical polymerization type composition may contain only one kind of colorant, or may contain two or more kinds of colorants.

On the other hand, the cationically polymerizable composition can be a composition containing a photopolymerizable compound, a photoacid generator, and a colorant.

The photopolymerizable compound may be a compound having at least one photopolymerizable group that exhibits reactivity when irradiated with active energy rays. Examples of photopolymerizable compounds include epoxy compounds having an oxylan group. Examples of epoxy compounds include aromatic epoxides, alicyclic epoxides, and aliphatic epoxides.

Further, the photopolymerizable compound may be a fatty acid ester, an epoxidized fatty acid ester in which an epoxy group is introduced into a fatty acid glyceride, an epoxidized fatty acid glyceride, or the like. Further, the photopolymerizable compound may be a compound containing an oxetane ring or a vinyl ether compound. The cationically polymerizable composition may contain only one type of photopolymerizable compound, or may contain two or more types of photopolymerizable compounds.

Further, the cationically polymerizable composition preferably contains the above photopolymerizable compound in an amount of 60 to 95% by mass in the solid content. When the amount of the photopolymerizable compound in the cationically polymerizable composition is within the above range, the cationically polymerizable composition is likely to be sufficiently wetted and spread on the above-mentioned layer to be printed, and the ink layer is likely to adhere to the layer to be printed. ..

Photoacid generators include, for example, salts of aromatic onium compounds; sulfonates that generate sulfonic acids; halides that generate hydrogen halides, and the like. The cationically polymerized composition preferably contains the photoacid generator in an amount of 3 to 20% by mass in the solid content. When the amount of the photoacid generator in the cationically polymerizable composition is within the above range, the photopolymerizable compound can be sufficiently cured.

The colorant contained in the cationically polymerized composition is the same as the colorant contained in the radically polymerized composition.

The curable composition may contain other components, if necessary. Examples of other ingredients include polymerization inhibitors, antioxidants, silane coupling agents, plasticizers, rust inhibitors, solvents, non-reactive polymers, fillers, pH regulators, defoamers, charge controllers, Includes stress relaxation agents, surface conditioners, etc.

(Use of painted metal material)
The use of the above-mentioned coated metal material is not particularly limited, and it can be used for a wide variety of members and uses that use a metal base material. Examples of applications include interior decorative building materials such as partitions, doors, ceiling materials, flooring materials, elevator doors, and elevator interior panels; various residential equipment such as range hoods and bathroom interior materials; desks, chairs, lockers, and shelves. Furniture such as; home appliances such as refrigerator outer panels, microwave oven outer panels, personal computer housings, air conditioner housings; vehicle components such as passenger car interiors and railway vehicle interiors. However, the use of the coated metal material is not limited to these.

Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited to these Examples.

1. 1. Preparation of metal base material A molten Zn-55% Al alloy plated steel sheet having a plate thickness of 0.27 mm and an A4 size plating adhesion amount of 90 g / m ^{2 per side was used.} After alkali degreasing of this metal plate, it was treated with a coating type chromate (manufactured by Nippon Paint Co., Ltd .: NRC300NS, ^{an adhesion amount of 50 mg / m 2 as Cr).} Further, as a primer layer, a commercially available epoxy resin-based primer paint (manufactured by Nippon Paint Industrial Coatings Co., Ltd .: 715P) was coated with a roll coater so that the dry film thickness was 5 μm. Then, it was baked so that the maximum plate temperature reached 215 ° C.

2. Preparation and Application of Metallic Paint The polyvalent carboxylic acids and polyhydric alcohols shown in Table 1 were polymerized by a conventional method to prepare polyester resins P1 to P8. Table 1 shows the number average molecular weight of each polyester resin, the hydroxyl value, and the amount of structural unit derived from an alcohol of trivalent or higher (mol%) with respect to the total amount of the carboxylic acid structural unit and the alcohol structural unit in the polyester resin.

After preparing the polyester resin, the polyester resin and the melamine resin were mixed. As the melamine resin, a methylated melamine resin (manufactured by Nippon Cytec Industries Co., Ltd .: Cymel 303) and / or a butylated melamine resin (manufactured by Nippon Cytec Industries Co., Ltd .: Cymel 325) was used. The combination and mixing ratio of the polyester resin and the melamine resin were the combinations and mixing ratios shown in Table 2.

The following components were further added to the mixture of the polyester resin and the melamine resin to prepare a paint for metals. The amount of each component is a value with respect to the solid content of the metal coating material. The balance of the solid content is a mixture of the polyester resin and the melamine resin.

40% by mass of titanium oxide (manufactured by Teika: JR-603) with an average particle size of 0.28 μm, 9% by mass of silica (manufactured by Yamaguchi Mica: SJ-010) with an average particle size of 10 μm, hydrophobicity with an average particle size of 5.5 μm 6% by mass of sex silica (manufactured by Fuji Silysia Chemical Ltd .: Cycilia 456) and 2% by mass of hydrophobic silica (manufactured by Fuji Silysia Chemical Ltd .: Cylysia 476) having an average particle size of 12 μm were used. Further, dodecylbenzene sulphonic acid was used as a catalyst in an amount of 1% by mass based on the solid content of the above-mentioned resin. Further, dimethylaminoethanol as an amine was used in an amount of 1.25 times as an amine equivalent with respect to the acid equivalent of dodecylbenzene sulphonic acid.

Then, the metal paint was coated on one surface of the metal base material having the above-mentioned primer layer with a roll coater so that the dry film thickness of the metal paint was 18 μm. Then, it was baked for 60 seconds so that the maximum plate temperature reached 225 ° C., and a layer to be printed was formed on the metal substrate.

3. 3. Frame processing or corona discharge treatment The above-mentioned layer to be printed was subjected to frame treatment or corona discharge treatment under the following conditions.

3-1. Frame processing The metal base material on which the above-mentioned layer to be printed was formed was placed on a conveyor, and the layer to be printed was frame-processed. As the frame processing burner, F-3000 manufactured by Flynn Burner (USA) was used. Further, as the combustible gas, a mixed gas (LP gas: clean dry air (volume ratio) = 1: 25) in which LP gas (combustion gas) and clean dry air were mixed with a gas mixer was used. The flow rate of each gas was adjusted so that LP gas (combustion gas) was 1.67 L / min and clean dry air was 41.7 L / min with respect to ^{1 cm 2 of the burner flame opening.} The length of the flame port of the burner head in the transport direction of the layer to be printed was set to 4 mm. On the other hand, the length of the burner head in the direction perpendicular to the transport direction of the flame port was 450 mm. Further, the distance between the flame port of the burner head and the surface of the layer to be printed was set to 50 mm according to the desired frame processing amount. Further, the frame processing amount was adjusted to ^{212 kJ / m 2} by setting the transport speed of the layer to be printed to 30 m / min.

3-2. Corona discharge treatment The layer to be printed formed on the surface of the above-mentioned metal substrate was subjected to corona discharge treatment. For the corona discharge treatment, a corona discharge treatment device manufactured by Kasuga Electric Co., Ltd. was used.
(specification)
・ Electrode ceramic electrode ・ Electrode length 430mm
・ Output 310W
The number of corona discharge treatments of the layer to be printed was set to 1 in each case. The amount of corona discharge processed was adjusted according to the processing speed. Specifically, the treatment was performed at 2.8 m / min, and the corona discharge treatment amount was 250 W / m ² / min.

4. Preparation of active energy ray-curable composition The active energy ray-curable composition (the following radicals) prepared as follows on the printed layer subjected to the above-mentioned frame treatment or corona discharge treatment and the untreated layer to be printed. A polymerizable composition or a cationically polymerized composition) was applied under the conditions described below.

4-1. Preparation of radical polymerization type black composition-Composition The following components were mixed to prepare a radical polymerization type black composition.
Pigment dispersion (pigment: 10% by mass) 10 parts by mass Photopolymerizable compound A 25 parts by mass Photopolymerizable compound B 57 parts by mass Photopolymerization initiator a 5 parts by mass Photopolymerization initiator b 3 parts by mass

-Material The following compounds were used as the material of the radical polymerization type black composition.
Pigment dispersion: A mixture of carbon black (manufactured by Degusa Japan, NIPex 35) and a dispersion medium (manufactured by Sartmer Japan, SR9003, PO-modified neopentyl glycol diacrylate) Photopolymerizable compound A: manufactured by Sartmer Japan, CN985B88 (mixture of 88% by mass of bifunctional aliphatic urethane acrylate and 12% by mass of 1,6-hexanediol diacrylate)
Photopolymerizable Compound B: 1,6-Hexanediol Diacrylate Photopolymerization Initiator a: Irgacure 184 (Hydroxyketones) manufactured by Ciba Japan Co., Ltd.
Photopolymerization Initiator b: Irgacure 819 (acylphosphine oxides) manufactured by Ciba Japan Co., Ltd.

4-2. Preparation of Cationicly Polymerized Black Composition The cationically polymerized black composition was prepared by first preparing a pigment dispersion liquid and then mixing the pigment dispersion liquid with other components.

-Preparation of pigment dispersion liquid 9 parts by mass of polymer dispersant (Ajinomoto Fine-Techno Co., Ltd., PB821), 71 parts by mass of oxetane compound (Toagosei Co., Ltd., OXT211), 20 parts by mass of black pigment (Pigment Black 7) Was mixed. Then, the mixture was placed in a glass bottle together with 200 g of zirconia beads having a diameter of 1 mm, sealed, and dispersed in a paint shaker for 4 hours. Then, the zirconia beads were removed to obtain a pigment dispersion liquid.

-Composition The following components were mixed to prepare a cationically polymerized black composition.
Pigment dispersion 14 parts by mass Photopolymerizable compound C 4 parts by mass Photopolymerizable compound D 34 parts by mass Photopolymerizable compound E 24 parts by mass Photopolymerizable compound F 8.9 parts by mass Basic compound 0.05 parts by mass Surface activity Agent a 0.025 parts by mass Surface active agent b 0.025 parts by mass Compatibility agent 10 parts by mass Photoacid generator 5 parts by mass

光重合性化合物Ｅ：オキセタン化合物（東亜合成社製、ＯＸＴ−２２１）
光重合性化合物Ｆ：オキセタン化合物（東亜合成社製、ＯＸＴ−２１１）
塩基性硬化型組成物：Ｎ−エチルジエタノールアミン
界面活性剤ａ：ＤＩＣ社製、メガファックＦ１７８ｋ（パーフルオロアルキル基含有アクリルオリゴマー）
界面活性剤ｂ：ＤＩＣ社製、メガファックＦ１４０５(パーフルオロアルキル基含有エチレンオキサイド付加物）
相溶化剤：東邦化学社製、ハイゾルブＢＤＢ（グリコールエーテル）
光酸発生剤：ダウケミカル社製、ＵＶ１６９９２ -Material The following compounds were used as the material for the cationically polymerized black composition.
Photopolymerizable compound C: Epoxy linseed oil (ATOFINA, Vikoflex 9040)
Photopolymerizable compound D: A compound represented by the following formula

Photopolymerizable compound E: Oxetane compound (manufactured by Toagosei Co., Ltd., OXT-221)
Photopolymerizable compound F: Oxetane compound (manufactured by Toagosei Co., Ltd., OXT-211)
Basic curable composition: N-ethyldiethanolamine Surfactant a: Megafuck F178k (perfluoroalkyl group-containing acrylic oligomer) manufactured by DIC
Surfactant b: Megafuck F1405 (perfluoroalkyl group-containing ethylene oxide adduct) manufactured by DIC Corporation
Compatibility agent: High-solve BDB (glycol ether) manufactured by Toho Chemical Industry Co., Ltd.
Photoacid generator: UV16992, manufactured by Dow Chemical Co., Ltd.

4-3. Printing conditions for the active energy ray-curable composition The printing conditions for the radical polymerization type black composition and the cationic polymerization type black composition described above are as follows.

(Inkjet printing conditions for radical polymerization type composition)
(A) Nozzle diameter: 35 μm
(B) Applied voltage: 11.5V
(C) Pulse width: 10.0 μs
(D) Drive frequency: 3,483 Hz
(E) Resolution: 360 dpi
(F) Volume of droplet: 42pl
(G) Head heating temperature: 45 ° C.
(H) Coating amount: 8.4 g / m ²
(I) Distance between head and recording surface: 5.0 mm
(J) Initial velocity of droplet: 5.9 m / sec

(Inkjet printing conditions for cationically polymerized compositions)
(A) Nozzle diameter: 35 μm
(B) Applied voltage: 13.2V
(C) Pulse width: 10.0 μs
(D) Drive frequency: 3,483 Hz
(E) Resolution: 360 dpi
(F) Volume of droplet: 42pl
(G) Head heating temperature: 45 ° C.
(H) Coating amount: 8.4 g / m ²
(I) Distance between head and recording surface: 5.0 mm
(J) Initial velocity of droplet: 6.1 m / sec

5. Evaluation The layers to be printed (untreated, framed, and corona discharge treated) were subjected to the following XPS analysis, methylene iodide fall angle measurement, and wet spread evaluation of the active energy ray-curable composition. In addition, a weather resistance test was performed on the untreated layer to be printed. Further, the adhesion of the ink layer, the impact resistance test, and the processability test were carried out on the coated metal material after applying the active energy ray-curable composition to form the ink layer. The results are shown in Tables 3 and 4.

5-1. XPS analysis (measurement of O-atom concentration and C-atom concentration on the surface of the layer to be printed)
The O atom concentration and the C atom concentration on the surface of the layer to be printed were measured by an XPS analyzer (AXIS-NOVA manufactured by KRATOS) under the following conditions.
X-ray source: Monochromatic AlKα (1486.6 eV)
Analysis area: 300 x 700 μm
Laboratory vacuum: 1.0 × ^10-7 Pa

5-2. Measurement of Methylene Iodide Fall Angle 2 μl of methylene iodide was dropped onto the layer to be printed held horizontally. Then, using a contact angle measuring device (DM901 manufactured by Kyowa Interface Science Co., Ltd.), the inclination angle of the layer to be printed (the angle formed by the horizontal plane and the layer to be printed) was increased at a speed of 2 degrees / sec. Then, the droplets of methylene iodide were observed by the camera attached to the contact angle measuring device. The inclination angle of the layer to be printed at the moment when the droplets of methylene iodide fell was specified, and the average value of 5 times was taken as the methylene iodide fall angle of the layer to be printed. The moment when the droplet of methylene iodide falls is the moment when both the end point in the downward direction of gravity and the end point in the upward direction of gravity of the droplet of methylene iodide start to move.

5-3. Weather resistance test For the layer to be printed (untreated), use a sunshine weather meter (“S80DH” manufactured by Suga Test Instruments Co., Ltd.) according to the sunshine carbon arc lamp type weather resistance test specified in JIS D0205. An accelerated weather resistance test was conducted under the following conditions.

(Test conditions)
Illuminance: 255 W / m ²
Irradiation cycle: 12 minutes out of 60 minutes Rainfall Irradiation time: 1,000 hours Black panel temperature: 63 ° C
After the accelerated weathering test, the gloss retention rate of the flat portion of the layer to be printed was calculated. The gloss retention rate is the ratio of the glossiness of the layer to be printed after the test to the glossiness (assumed to be 100) of the layer to be printed before the test. The glossiness was measured according to the method specified in JIS K5600-4-7. A digital variable angle gloss meter UGV-6P manufactured by Suga Test Instruments Co., Ltd. was used as a measuring device, and the incident angle of light was 60 °, and the evaluation was performed as follows. △ The above was regarded as a pass.
〇: Gloss retention rate 40% or more Δ: Gloss retention rate 20% or more, less than 40% ×: Gloss retention rate less than 20%

5-4. Evaluation of wet spreadability of active energy ray-curable composition The active energy ray-curable composition (radical polymerization type black composition and cationic polymerization type black composition) was applied in dots on the above-mentioned layer to be printed. Specifically, dots were printed using an inkjet printing machine (manufactured by Tritech Co., Ltd .: patterning jet) so that the volume of each droplet was 42 pl. The distance between the dots was set to 500 μm so that the dots did not overlap each other. Then, each dot diameter was measured using a scanning confocal laser scanning microscope LEXT OLS3000 manufactured by Olympus Corporation. More specifically, the dot diameter of eight dots was measured by enlarging the area so that only one dot could be seen (200 times), and the average value thereof was evaluated as the dot diameter. When the dot spread was close to an ellipse, the average value of the major axis and the minor axis was taken as the dot diameter and evaluated as follows. If the dot diameter is less than 100 μm, the active energy ray-curable composition is difficult to wet and spread, and even if 100% printing is performed, the surface of the metal substrate (printed layer) may be completely covered with the active energy ray-curable composition. Can not. Therefore, the smaller the dot diameter, the lower the evaluation. However, if it is △ or more, it can be said that there is no practical problem.
⊚: Dot diameter 130 μm or more ○: Dot diameter 100 μm or more and less than 130 μm Δ: Dot diameter 80 μm or more and less than 100 μm ×: Dot diameter less than 80 μm

5-5. Evaluation of Adhesion of Ink Layer 100 to 1000% (ink coating amount: 8.4 to 84.0 g) so that the active energy ray-curable composition has a resolution of 360 dpi under the above conditions on the above-mentioned layer to be printed. / M ² ) was printed. After that, using a high-pressure mercury lamp (H valve manufactured by Fusion UV Systems Japan Co., Ltd.), the output of the lamp: 200 W / cm, the integrated light intensity: 600 mJ / cm ² (manufactured by ORC Manufacturing Co., Ltd., UV light meter UV-351-25). The ink layer was formed by irradiating with ultraviolet rays (measured using). The obtained coated metal material was subjected to a grid test in accordance with JIS K5600-5-6 G 330. Specifically, a grid-like notch was made on the surface of the ink layer so as to form 25 squares at 2 mm intervals. Then, an adhesive tape was attached to the portion and peeled off. After peeling off the adhesive tape, the residual rate of the ink layer was observed. The evaluation was performed according to the following criteria, and a score of Δ or higher was considered acceptable.
〇: The peeled area of the ink layer is 0%
Δ: The peeled area of the ink layer is more than 0% and within 20% ×: The peeled area of the ink layer is more than 20%

5-6. Impact resistance test The active energy ray-curable composition was printed on the above-mentioned layer to be printed at 100% (ink application amount: 8.4 g / m ² ) so as to have a resolution of 360 dpi under the above-mentioned conditions. The ink layer was formed by irradiating with ultraviolet rays and curing in the same manner as in the above. The obtained coated metal material was impacted using a DuPont impact tester according to the impact test of JIS G3322. Then, an adhesive tape was attached to the surface of the ink layer and peeled off. The appearance of the coated metal material before the adhesive tape was attached and after the adhesive tape was peeled off was observed and evaluated as follows. In addition, the evaluation of △ or more was accepted.
⊚: No peeling of ink layer and printed layer and no crack (crack) before sticking ○: No peeling of ink layer and printed layer, but crack (crack) before sticking △: Ink layer or covered There is very slight peeling on the print layer ×: There is slight peeling on the ink layer or the layer to be printed × ×: There is peeling on the ink layer or the layer to be printed

5-7. Workability test Similar to the impact resistance test described above, an ink layer was formed on the layer to be printed with an active energy ray-curable composition. The obtained coated metal material was subjected to a 4T bending test according to the bending test of JIS G3322. Then, an adhesive tape was attached to the surface of the ink layer of the bent portion and peeled off. The appearance of the coated metal material before the adhesive tape was attached and after the adhesive tape was peeled off was observed and evaluated as follows. In addition, evaluations of △ or higher were accepted.
⊚: No peeling of ink layer and printed layer and no crack (crack) before pasting ○: No peeling of ink layer and printed layer, but crack (crack) before sticking △: Ink layer or covered There is very slight peeling on the print layer ×: There is slight peeling on the ink layer or the layer to be printed × ×: There is peeling on the ink layer or the layer to be printed

Polyester resins P1 to P4 in which the amount of triol-derived structural units (structural units derived from trivalent or higher alcohols) is less than 20 mol% with respect to a total of 100 mol% of alcohol structural units and carboxylic acid structural units in the polyester resin. When the layer to be printed containing the above was formed on a metal plate (combinations A to D of a polyester resin and a melamine resin), the adhesiveness of both the radical polymerization type composition and the cationic polymerization type composition was good. Further, in these examples, since the number average molecular weight of the polyester resin in the metal coating material was 4000 to 12000, the evaluation of weather resistance (gloss retention rate) was also good. When the layer to be printed was not subjected to corona discharge treatment or frame treatment, the adhesion tended to decrease as the amount of the active energy ray-curable composition increased. On the other hand, when the frame treatment or the corona discharge treatment was performed, the adhesion was difficult to decrease even if the amount of the active energy ray-curable composition was large. In particular, when the frame treatment was performed, the adhesion was good even when the coating amount was very large (Examples 2, 5, 8 and 11).

As in these examples, when the coating amount of the active energy ray-curable composition is 500% or more and sufficient adhesion is obtained, irregularities are formed on the ink layer itself obtained from the active energy ray-curable composition. It becomes possible to do such things. Therefore, the design of the coated metal base material can be significantly improved.

Further, in all of the layers to be printed in these examples, the dot diameter was 130 μm or more in the dot diameter evaluation of the ink droplets, and sufficient ink wettability and spreadability were obtained. In other words, it can be said that the frame processing has improved both the adhesion of the ink and the wettability. Then, according to such a layer to be printed, it is possible to increase the height difference of the uneven pattern due to the ink layer, and the color gamut thereof is also widened. Therefore, the frame processing greatly improves the design.

On the other hand, even if the amount of triol-derived structural units in the polyester resin of the metal plate paint is less than 20 mol%, the average molecular weight of the polyester resin in the metal plate paint exceeds 12000 (polyester resin and melamine). Although the resin combination E or F) and the impact resistance and workability when frame-treated were good, it was difficult to obtain sufficient performance in terms of adhesion when the amount of ink was large. When the number average molecular weight of the polyester resin is high, it is considered that it is difficult to introduce a sufficient amount of OH groups or the like on the surface even if the frame treatment or the like is performed. Moreover, in these comparative examples, the evaluation of the weather resistance of the layer to be printed was low. It is considered that this is because the cross-linking density of the melamine resin in the layer to be printed was too low.

Further, the polyester resin P7 and the polyester resin P7 containing 20 mol% or more of triol-derived structural units (triovalent or higher alcohol-derived structural units) with respect to a total of 100 mol% of alcohol structural units and carboxylic acid structural units in the polyester resin. When the layer to be printed containing P8 is formed on a metal plate (combination G and H of polyester resin and melamine resin), the adhesion of the active energy ray-curable composition is improved even if frame treatment or corona discharge treatment is performed. No (Comparative Examples 7 to 12). In these metal substrates to be printed, it is considered that the crosslink density of the polyester resin in the layer to be printed formed on the metal plate was excessively high. Then, when the active energy ray-curable composition applied on the layer to be printed is cured, if it is cured and shrunk, it is between the layer to be printed and the ink layer obtained from the active energy ray-curable composition. It is considered that stress was applied and the ink was easily peeled off.

According to the metal coating material of the present invention, a layer to be printed having high adhesion to an ink layer can be formed on a metal base material. Therefore, it is possible to form various layers with high designability on various metal substrates by using the active energy ray-curable composition.

Claims (10)

Polyester resin with a number average molecular weight of 4000-12000 and
With melamine resin,
Is a metal paint that contains
The polyester resin contains an alcohol structural unit derived from a polyhydric alcohol and a carboxylic acid structural unit derived from a polyvalent carboxylic acid.
The ratio of the amount of the trivalent or higher alcohol-derived structural unit to the total amount of the alcohol structural unit and the carboxylic acid structural unit is 20 mol% or less.
Metal paint. The polyester resin contains a structural unit derived from trimethylolpropane.
The metal paint according to claim 1. Pre-coated metal plate paint,
The metallic paint according to claim 1 or 2. With a metal base material
A layer to be printed, which is a cured product of the metal coating material according to any one of claims 1 to 3, arranged on the metal substrate.
Have,
Metal substrate for printing. When the surface of the layer to be printed is analyzed by X-ray electron spectroscopy using AlKα rays as an X-ray source, the ratio of the amount of O atoms to the amount of C atoms is 0.6 or more.
The metal substrate for printing according to claim 4. The methylene iodide fall angle on the surface of the layer to be printed is 15 ° or more and 45 ° or less.
The metal substrate to be printed according to claim 4 or 5. Pre-coated metal plate,
The metal substrate for printing according to any one of claims 4 to 6. The metal substrate to be printed according to any one of claims 4 to 7.
An ink layer, which is a cured product of an active energy ray-curable composition arranged on the layer to be printed,
Have,
Painted metal material. The thickness of the ink layer is 40 μm or more.
The coated metal material according to claim 8. A step of applying the metal coating material according to any one of claims 1 to 3 onto a metal substrate to form a layer to be printed.
A step of performing a frame treatment or a corona discharge treatment on the layer to be printed, and
including,
A method for manufacturing a metal substrate to be printed.