JPH05138122A - Production of decorative metallic plate - Google Patents

Abstract

PURPOSE:To improve coating workability by coating the surface of a metallic plate with a primer coating material and an intermediate coating material and coating the entire surface with a clear coating material consisting of an acrylic resin, aminoplast resin, silicone oil and org. solvent to have prescribed film thickness. CONSTITUTION:The surface of the metallic plate is so coated with the primer coating material as to have 3 to 10mum dry coating film thickness and is then coated with the intermediate coating material so as to have 10 to 30mum dry coating film thickness. The surface of the intermediate coating film is subjected to full-surface or partial pattern-like printing, then to baking and drying. The entire surface is then coated with the clear coating material consisting of the acrylic resin having 60 to 200 deg.C glass transition temp., 15000 to 100000 number average mol.wt. and 20000 to 150000 weight average mol.wt., the aminoplast resin which is a hardener, 30 to 80 pts.wt. hard body pigment of <=30mum average grain size, per 100 pts.wt. total of the above-mentioned acrylic resin and the hardener, 0.01 to 10 pts.wt. silicone oil and the org. solvent contg. high boiling ether alcohols in such a manner as to have 10 to 30mum dry coating film thickness of the coating film and >=9H hardness.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a decorative metal sheet having a design pattern finish, which is capable of easily peeling off a paper sticker or a letter, and has a high hardness and excellent bending workability. It is a thing.

[0002]

2. Description of the Related Art Conventionally, as a means for preventing contamination by accidental writing on the inner wall or ceiling of a vehicle or the like, a method of forming a metal plate, which is a material thereof, and then hollow-finishing it, or an inorganic coating or As seen in Japanese Patent Laid-Open No. 55-132662, a method of applying an anti-paper-sticking paint has been used.

[0003]

However, according to the above-mentioned prior art, since the coating is performed after the metal plate is formed, the workability of the coating is poor, and even if the coating is broken or slightly bent, the coating film may be broken. Easy to peel off,
Further, it was difficult to form a coating film having smoothness, and it was also difficult to finish the design pattern. Further, a method for producing a pre-coated metal having a high hardness as shown in Japanese Patent Publication No. 3-44820 and excellent in bending workability has also been developed. In this case as well, a design pattern finish such as a melamine decorative board is finished. There was a problem that it was difficult.

The present invention has been earnestly studied in view of such a situation as described above, has good coating workability, is less likely to cause cracks or peeling of a coating film even during cutting or bending, and is not suitable for paper sticking or lettering. An object of the present invention is to provide a method for producing a decorative metal plate that enables a design pattern finish having a coating film that can be easily peeled off.

[0005]

In order to achieve the above object, a method for producing a decorative metal plate according to the present invention is such that a glass transition temperature of 5 to 70 is applied to a metal plate which has been subjected to a surface treatment such as chemical conversion treatment if necessary. C., a polyester resin having a number average molecular weight of 4,500 to 35,000 and an aminoplast resin as a curing agent,
Based on 100 parts by weight of the total amount of the polyester resin and the curing agent, 30 to 100 parts by weight of the pigment and the necessary amount of the organic solvent are used, and the degree of dispersion of the pigment is 15 μm or less of the Grindage A method. Painted to 10 μm, baked and dried, then glass transition temperature 60-200
50 ° C., a color pigment of 50 to 15 per 100 parts by weight of the acrylic resin having a number average molecular weight of 5,000 to 100,000 and a weight average molecular weight of 20,000 to 150,000 and a curing agent, aminoplast resin, and the acrylic resin and the curing agent.
0 parts by weight, hard extender pigment having an average particle size of 5 μm or less 5 to 50
And a necessary amount of an organic solvent containing a high boiling point ether alcohol, and a pigment dispersity is applied so that a dry film thickness of 10 to 30 μm is obtained by applying an intermediate coating composition having a pigment dispersity of 15 μm or less. Then, the intermediate coating film is subjected to pattern printing on the entire surface or a part thereof and baked and dried, and then the entire surface is subjected to a glass transition temperature of 60 to 200 ° C. and a number average molecular weight of 15
000 to 100,000, weight average molecular weight 20,000 to 1
50,000 acrylic resin and aminoplast resin which is a curing agent, and the total amount of the acrylic resin and the curing agent is 100.
Hard extender pigment 3 having an average particle size of 30 μm or less with respect to parts by weight
A clear coating composition consisting of 0 to 80 parts by weight, 0.01 to 10 parts by weight of silicone oil, and a necessary amount of an organic solvent containing high boiling ether alcohols is applied to a dry film thickness of 10 to 30 μm. Then, it is baked and dried to produce a decorative metal plate having a coating film having a hardness of 9H or more.

The structure of the present invention will be described in more detail below. The undercoat paint used in the present invention comprises a polyester resin, a curing agent, an aminoplast resin, a pigment and an organic solvent as main components, and if necessary, various additives and modifiers. This is for improving the workability and adhesion of the film.

The polyester resin is obtained by polymerizing a polyvalent carboxylic acid and a polyvalent alcohol by a known method. As the polyvalent carboxylic acid, for example, adipic acid, terephthalic acid, isophthalic acid, phthalic anhydride, hexahydrophthalic anhydride, trimellitic anhydride, maleic anhydride, succinic anhydride, etc. are used, and as the polyvalent alcohol. Are, for example, neopentyl glycol, ethylene glycol, propylene glycol, diethylene glycol, glycerin, trimethylolpropane, trimethylolethane, pentaerythritol,
Bisphenol A or the like is used. This polyester resin has a glass transition temperature (hereinafter, simply referred to as Tg) of 5
The number average molecular weight (hereinafter, simply referred to as Mn) is preferably from 4500 to 35000, and more preferably from 5000 to 20000. In addition,
If the Tg is less than 5 ° C, the adhesion will be insufficient and the hardness of the coating film after topcoating will be low, and if the Tg exceeds 70 ° C and the Mn is less than 4500, the post-processing will be
In particular, at the time of cutting, the coating film on the end portion is easily peeled off, and when Mn exceeds 35000, it is difficult to dissolve in an organic solvent and it is difficult to obtain a smooth coating film. The acid value of the polyester resin is preferably 5 or less and the hydroxyl value is 10 to 50, and in this range, a coating film having excellent processability, adhesion, corrosion resistance and the like can be obtained.

The aminoplast resin is a condensation product of an amino compound such as melamine, urea or benzoguanamine and an aldehyde compound, or the condensation product is further etherified with an alcohol such as methanol or butanol. It was done. The solid content ratio of the polyester resin and the aminoplast resin is appropriately (70/30 to 85/15) by weight ratio, and the original resin characteristics can be exhibited in this range.

As the above-mentioned pigment, a usual coloring pigment for paints such as titanium oxide, red iron oxide, phthalocyanine blue and the like, an extender pigment for usual paints such as kaolin, barium sulfate precipitating and talc can be used, and rust preventive property is added. Therefore, it is desirable to use an ordinary rust preventive pigment for paint such as strontium chromate. This pigment is preferably added in an amount of 30 to 100 parts by weight, based on 100 parts by weight of the total amount of the polyester resin and the curing agent.
It is desirable to blend in parts by weight.

The organic solvent is toluene, xylene, methyl isobutyl ketone, cellosolve, ethylene glycol-
What is normally used for paints, such as rumonobutyl ether and cyclohexanone, can be used. This organic solvent has a viscosity of 40 to 120 depending on the coating workability.
Blend for seconds (Food cup # 4 / room temperature).

The undercoat paint used in the present invention comprises the above-mentioned constituents. This paint is kneaded and dispersed so that the pigment dispersity is 15 μm or less by the Grindge A method. 15 μm
If it exceeds the range, it is not preferable because the coating film is likely to have spots. In the present invention, an acrylic resin-based or epoxy resin-based coating was also examined as the undercoating paint, but cracks in the coating film during cutting or bending,
It was unsuitable because peeling easily occurred.

Next, the intermediate coating used in the present invention is an acrylic resin, a curing agent such as aminoplast resin,
The main component is a coloring pigment, a hard extender pigment, and an organic solvent, and if necessary, various additives and modifiers.

The acrylic resin is a monomer having a functional group-3 to 40% by weight and a monomer having no functional group-97 to
It is desirable that 60% by weight is copolymerized by a normal solution polymerization method. If the amount of the former exceeds 40% by weight, the reaction with the curing agent will occur excessively, the printability in the subsequent printing step tends to deteriorate, and the adhesion with the clear top coat film tends to decrease. Examples of the monomer having a functional group include acrylic acid, methacrylic acid, acrylic amide, butyl acrylic amide, isopropyl acrylic amide, isononyl acrylic amide, isooctyl acrylic amide, N-isopropyl acrylic amide, N, N diisopropyl acrylic amide, N, N dimethyl acrylic amide, N-methyl-N-phenyl acrylic amide,
Morpholyl acrylate, piperidyl acrylate, 2 hydroxyethyl methacrylate, 2 hydroxypropyl methacrylate, 4 ethoxycarbonylphenyl acrylate, 4 methoxycarbonyl phenyl methacrylate, 4-butoxycarbonyl Phenyl methacrylic amide, 4-carbonyl phenyl methacrylic amide, 4-ethoxycarbonyl phenyl methacrylic amide, 4-methoxy carbonyl phenyl methacrylic amide, butyl chloro acrylate, butyl cyano acrylate, hexyl chloro acrylate , Pentachlorophenyl acrylate, methoxycarbonylphenyl acrylate, etc. are used.
(2-Dimethylaminoethoxycarbonyl) styrene, 4- (2-dimethylaminoethoxycarbonyl) styrene, 2-phenylaminocarbonylstyrene, 2 and 4-propoxycarbonylstyrene, 4-propoxymethylstyrene, 4-propoxy. Sulfonylstyrene and the like are used. As the non-functional group monomer, 4-biphenyl acrylate, butyl acrylate, butyl phenyl acrylate, hexadecyl acrylate, isobomyl acrylate, naphthyl acrylate. , Phenyl acrylate, tolyl acrylate, adamantyl methacrylate, benzyl methacrylate, t-butyl methacrylate, ethyl methacrylate, isobutyl methacrylate, isopropyl methacrylate, 3, 5 dimethyl radadamantyl methacrylate, 3,3 dimethyl butyl methacrylate, 3,3-dimethyl 2-butyl methacrylate, methyl methacrylate, trimethylsilyl methacrylate, phenyl methacrylate , Propyl methacrylate, etc. are used, and as the styrene type, α-
Methylstyrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, dimethylstyrene, trimethylstyrene, 4-phenylstyrene, styrene and the like are used.

The Tg of the acrylic resin polymerized by the heretofore commonly used solution polymerization method with the above-mentioned monomer composition is 60 to 200 ° C., preferably 70 to 160.
C, Mn of 5,000 to 100,000, preferably 600
0 to 80,000, weight average molecular weight (hereinafter, simply referred to as Mw) of 20,000 to 150,000, preferably 2,000
Those of 0 to 80,000 are preferable. In addition, Tg is 60
If the temperature is lower than 0 ° C, the hardness of the coating film is low. On the contrary, if the temperature exceeds 200 ° C, the smoothness of the coating film is deteriorated and the coating film is apt to crack during cutting, which is not preferable. Also, Mn is 50
If it is less than 00, the hardness of the coating film is low and the workability tends to decrease. On the contrary, if it exceeds 100,000, the smoothness of the coating film is deteriorated, which is not preferable. Further, if the Mw is less than 20000, the pick-up characteristics required for roll coater coating (the property that the pick-up roll lifts the paint from the paint pan) are poor, and continuous coating at a speed of 30 m / min or more becomes impossible. If it exceeds 150,000, the smoothness of the coating film deteriorates, which is not preferable.

The acrylic resin preferably has an acid value of 2 to 15 and a hydroxyl value of 15 to 60. Within this range, a coating film having hardness and the like can be obtained by sufficient reaction with the aminoplast resin. As the aminoplast resin, the same ones as those used in the undercoat paint can be used, but hexamethoxymethyl etherified melamine condensate having a good compatibility with an acrylic resin is particularly preferable. Examples of commercially available products include Summar 30S, 40S, 50 manufactured by Sumitomo Chemical Co., Ltd.
S; Cymel 303, 305, 30 manufactured by Mitsui Toatsu Chemicals, Inc.
7,325,370; Sanwa Chemical Nikarac M
X45, Nikarac 001; Melan 230 manufactured by Hitachi Chemical Co., Ltd., and the like.

The mixing ratio of the solid contents of the acrylic resin and the aminoplast resin is appropriate (60/40 to 80/20) by weight ratio, and the original resin characteristics can be exhibited within this range.

As the color pigment, a color pigment usually used for paints can be used, and the compounding amount thereof is 50 to 15 with respect to 100 parts by weight of the total amount of the acrylic resin and the curing agent.
0 parts by weight is suitable. When the amount of the coloring pigment is less than the above range, sufficient hiding power cannot be obtained. On the contrary, when the amount of the coloring pigment is too large, the smoothness of the coated surface is deteriorated, and good printing in the subsequent step becomes difficult. The above-mentioned hard extender is blended to improve the hardness of the coating film, and the hardness of silicic acid anhydride, silicon carbide, glass, alumina or the like having an average particle size of 5 μm or less is 6.
Extender pigments of 5 or more are suitable. The hard extender pigment is 5 parts with respect to 100 parts by weight of the total amount of the acrylic resin and the curing agent.
-50 parts by weight is suitable. When the amount is less than 5 parts by weight, the contribution to the improvement of the coating film hardness is small. On the contrary, when the amount is more than 50 parts by weight, the smoothness of the coated surface is deteriorated and it becomes difficult to perform good printing in the subsequent step.

In the present invention, in the case of roll coater coating, a specific surface area (BET method) of 50 m ² / g or less is contained in the intermediate coating composition in order to improve pickup characteristics.
It is desirable to add ultrafine precipitated barium sulfate having an average particle diameter of 0.06 μm or less as an extender pigment, and the amount thereof is 10 to 30 parts by weight per 100 parts by weight of the total amount of the acrylic resin and the curing agent. Is. Commercially available products of the ultrafine-grain precipitated barium sulfate include, for example, BF-1, 10, 20 manufactured by Sakai Chemical Co., Ltd.

The organic solvent is blended with an organic solvent usually used for paints so that the viscosity of the intermediate coating paint is 40 to 120 seconds (fod cup # 4 / room temperature) in accordance with the coating workability. In the present invention, high boiling ether alcohols are used as an essential component as an organic solvent in order to improve smoothness after coating, at least in part. The high-boiling ether alcohols include ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, ethylene glycol monoethyl ether, diethylene glycol monoethyl ether, ethylene glycol monomethyl ether, diethylene glycol monomethyl ether. , Ethylene glycol monopropyl ether
Tellurium, diethylene glycol monopropyl ether and the like. The above-mentioned high boiling ether alcohols can achieve the above effects by blending about 10 to 50 parts by weight with respect to 100 parts by weight of the total amount of the acrylic resin and the curing agent. It may cause coating film defects in the above, and should be avoided.

The intermediate coating composition used in the present invention comprises the above-mentioned components. The coating composition is kneaded and dispersed so that the pigment dispersity is 15 μm or less by the Grindge A method. 15 μm
If it exceeds the range, it is not preferable because the coating film is likely to have spots.

Next, the printing ink used for pattern printing in the present invention is an epoxy resin (number average molecular weight (hereinafter referred to as Mn) 800 to 3000), an acrylic resin (Mn 5000 to 30000) or a polyester resin (Mn 2000). .About.20000) as a main component, and based on 100 parts by weight of the resin solid content, 5 to 150 parts by weight of color pigments and 0 to 100 parts by weight of extender pigments such as talc, kaolin, calcium carbonate, barium sulfate and silicic acid anhydride. Then
If necessary, a crosslinking agent such as an aminoplast resin may be added in an amount of 1 to 20 parts by weight based on 100 parts by weight of the resin solid content to increase the hardness of the ink. In order to disperse the pigment and defoam, an acrylic additive and silicone oil should be added in an amount of 0.
Add from 02 to 1.0 parts by weight. Examples of commercially available acrylic additives include Modaflow (manufactured by Monsanto); Polyflo-9
0, 85 (manufactured by Kyoeisha Yushi); Disvalon 1980,
1982 (produced by Kusumoto Kasei Co., Ltd.) can be used, and as the silicone oil, Shin-Etsu Silicon KP357, 358, 367; B
BYK300, 301, 37 made by YK CHEMIE
0,310; Toray Silicon S428 manufactured by Toray Silicon Co., Ltd.
PA, SH29PA, SH30PA, SH34PH; Tegoprene manufactured by Goldschmidt, etc. can be used.

Further, in order to assist the drying property of the ink, 5 to 15 parts by weight of nitrocellulose or a homopolymer or copolymer of vinyl chloride or vinyl acetate is added to 100 parts by weight of the resin solid content. Is desirable. In addition,
For this ink, a solvent usually used for paints or inks can be used, but it is preferable to add 0.1 to 5 parts by weight of a high boiling point solvent such as diethylene glycol or isophorone in order to improve printability.

Next, the clear topcoat paint used in the present invention is mainly composed of an acrylic resin, a curing agent such as aminoplast resin, a hard extender pigment, silicone oil and an organic solvent containing high boiling ether alcohols. As a component, it further comprises, if necessary, a small amount of a coloring pigment, an extender pigment, various additives, a modifier, etc., to the extent that the visibility of the design pattern printing surface of the lower layer is not deteriorated.

The acrylic resin may be substantially the same as the acrylic resin used in the intermediate coating paint, but M
For n, it is necessary to use one having a hardness of 15,000 or more so that the coating film hardness is not less than a predetermined value.

The aminoplast resin may be the same as the aminoplast resin used in the intermediate coating composition. In addition, the mixing ratio of the solid content of the acrylic resin and the aminoplast resin is preferably 60/40 to 80/20 by weight.

The hard extender pigment may be substantially the same as the hard extender pigment used in the intermediate coating composition, but its average particle size is 30 μm or less, and the mixing ratio thereof is the sum of the acrylic resin and the curing agent. 3 for 100 parts by weight
0 to 80 parts by weight is suitable. If the particle size exceeds 30 μm, the coating film will have a rough feel, and is not suitable as a decorative plate. Further, if the blending ratio is less than 30 parts by weight, the contribution to the improvement of the coating film hardness is small, and conversely if it exceeds 80 parts by weight,
It is not preferable because the coated surface tends to be porous, the antifouling property is deteriorated, and the transparency is weakened to deteriorate the design.

The silicone oil is added in order to assist the function of facilitating the removal of deposits on the coating film and to improve the smoothness of the coating film. Examples of commercially available products include Shin-Etsu Chemical. Shin-Etsu Silicon KP357,35 made by Kogyo Co., Ltd.
8,367; BYK30 manufactured by BYK CHEMIE
0,301,320,370; Toray Silicon SH28PA, SH29PA, SH30PA, manufactured by Toray Silicon Co., Ltd.
SH34PA, ST92PA; Tegoprene manufactured by Goldschmidt, and the like. It is suitable that the silicone oil is blended in an amount of 0.01 to 10 parts by weight based on 100 parts by weight of the total amount of the acrylic resin and the curing agent. If the blending amount is less than 0.01 parts by weight, the above effect cannot be sufficiently exhibited, and conversely if it exceeds 10 parts by weight, stable dispersion cannot be obtained, and coating film defects such as cissing tend to occur. Therefore, it is not preferable.

The above-mentioned organic solvent is blended with an organic solvent usually used for coating so that the viscosity of the top coating clear coating is 40 to 120 seconds (Food cup # 4 / room temperature) according to the coating workability. .. In the present invention, the same high boiling point ether alcohols used in the intermediate coating composition for improving the dispersion effect of the silicone oil are used at least partially as the organic solvent as an essential component. It should be noted that the high-boiling ether alcohols can achieve the above effect by blending about 10 to 50 parts by weight with respect to 100 parts by weight of the total amount of the acrylic resin and the curing agent, but if blended in excess, It causes coating defects such as cissing and must be avoided. In addition, if necessary, an organic bentonite used in ordinary paints, a precipitation inhibitor such as silica, or the like may be used in an amount of 0.1 parts by weight per 100 parts by weight of the total amount of the acrylic resin and the curing agent.
It is desirable to add ~ 2.0 parts by weight.

The clear coating composition for top coating used in the present invention is a transparent or semi-transparent coating composition comprising the above-mentioned components, which is mixed and dispersed to obtain a pigment dispersity of 30 μm or less by the Grindage A method. ..

Next, a method for manufacturing the decorative metal plate of the present invention will be described. The surface of conventionally used sheet-like or coil-like metal sheets such as galvanized steel sheets, aluminum sheets, and stainless steel sheets is subjected to ordinary base treatment such as chemical conversion treatment, if necessary, and then the undercoat paint is dried to a dry film thickness. Coating is performed so as to have a thickness of 3 to 10 μm, and baking is performed at a maximum plate temperature (hereinafter, simply referred to as PMT) of about 180 to 230 ° C. for a short time of 30 to 70 seconds to form an undercoat coating film. If the film thickness is smaller than the above range, sufficient corrosion resistance cannot be obtained, and conversely, if the film thickness is larger, the hardness of the coating film after top coating is lowered, which is not preferable. Further, as the coating means, an ordinary coil coating means such as a roll coater or a flow coater can be used, but in the present invention, the use of a roll coater whose film thickness can be easily adjusted is particularly preferable. It is suitable.

After applying the undercoat coating film as described above, an intermediate coating composition is applied onto the coating film by a similar coating method to give a dry film thickness of 10 to 10.
It is coated so as to have a thickness of 30 μm, preferably 15 to 25 μm, and is baked at PMT of about 170 to 220 ° C. for a short time of 20 to 100 seconds to form an intermediate coating film.

After applying the above-mentioned intermediate coating film, on the coating film,
An arbitrary design pattern is entirely or partially applied by printing means such as gravure printing, gravure offset printing, flexographic printing, screen printing. This printing is carried out so that the dry film thickness is about 1 to 10 μm, then the entire surface is undercoated with a clear coating, and the dry film thickness is adjusted to 10 to 30 μm, preferably 15 to 25 μm by the same coating means as the intermediate coating. And PMT at 220 ~ 250 ℃, 30 ~
Baking is performed for 100 seconds to form a clear coating film having a hardness of 9H or more, and a decorative metal plate is manufactured. The hardness is 9H
If it is less than, abrasion resistance is insufficient and scratches easily occur with a waste cloth or a brush when removing a missing letter,
Not preferable. If necessary, the printing ink may be PMT.
The top clear coating composition may be applied by baking at about 170 to 220 ° C. for 20 to 100 seconds.

[0033]

EXAMPLES Examples of the present invention will be described below. In addition, "part" and "%" are shown by weight. <Preparation of Undercoat Paint> Polyester resin solution shown in Table 1 (solid content 60%; organic solvent isophorone, Solvesso 15)
0 (trade name manufactured by Shell Co.), a mixed solvent of ethylene glycol monoethyl ether acetate (1: 1: 1), melamine resin [“Cymel 303” (trade name manufactured by Mitsui Toatsu Chemicals, Inc.); solid content 100 %] And a pigment are kneaded and dispersed, and then paratoluenesulfonic acid and an organic solvent (a mixed solvent of isophorone and xylene are mixed at a ratio of 1: 1) are added to the undercoat paint having a pigment dispersity of 15 μm or less by the Grindage A method Was prepared. In each of the examples and comparative examples, a coating solvent having a viscosity of 50 seconds (foad cup # 4 / fused with a diluting solvent (mixed solvent of xylene and ethylene glycol monoethyl ether acetate / cyclohexanone 3: 1: 1) was used immediately before coating. Two
An undercoat paint prepared to have a temperature of 0 ° C. was used.

<Preparation of Intermediate Coating Composition> Acrylic resin solution shown in Table 2 (solid content 50%; organic solvent Solvesso # 150,
Ethylene glycol monobutyl ether 4: 1 mixed solvent), melamine resin solution ["Cymel 370"
(Mitsui Toatsu Chemical Co., Ltd. product name); solid content 88%; organic solvent: a mixed solvent of isobutanol and isopropanol 1: 1] and a pigment are kneaded and dispersed, and then paratoluenesulfonic acid and an organic solvent. (Ethylene glycol monobutyl ether, isobutanol, Solvesso # 150 1:
A mixed solvent of 1: 3) was added to prepare an intermediate coating composition having a pigment dispersity of 15 μm or less by the method of Grindge A.
In the Examples and Comparative Examples, a coating viscosity of 80 seconds was prepared with a diluting solvent (solvent of Solvesso # 150, isobutanol, diethylene glycol monobutyl ether 7: 2: 1) immediately before coating. The used intermediate coating paint was used.

<Preparation of Ink> Polyester resin solution [ALMATEX P646 (trade name, manufactured by Mitsui Toatsu Chemicals, Inc.), Mn 2700 to 3000, solid content 60%, organic solvent Solvesso # 100, 9 of methyl isobutyl ketone:
1 mixed solvent], melamine resin solution [Coban 1
28 (trade name, manufactured by Mitsui Toatsu Chemicals, Inc.); solid content 60%; mixed solvent consisting of organic solvent xylol and normal butanol 4: 6 parts by weight, 167 parts by weight and 17 parts by weight, respectively, and titanium oxide 100 as a pigment. Parts by weight, 0.5 parts by weight of carbon black, 0.2 parts of Disparlon 1980 (trade name of Kusumoto Kasei Co., Ltd.) as a dispersant and an antifoaming agent, and then kneaded and dispersed. Separately, 18% with methyl ethyl ketone. Prepared into a solution [Eslec A (vinyl chloride, vinegar bicopolymer;
Sekisui Plastics Co., Ltd.)] as solid content, 7 parts by weight, diethylene glycol 3 parts by weight, and Solvesso 100.
/ Xylol / Isobutanol = 7/2/1 (40 parts by weight) was added to the mixture to prepare a Grindage A method 1
An ink of 5 μm or less was prepared. In the examples and comparative examples, immediately before printing, Solvesso # 100, isobutanol, and diethylene glycol monobutyl ether (6: 6) were used.
An ink prepared to have a viscosity of 60 seconds with a mixed solvent of 3: 1 was used.

<Preparation of Topcoat Clear Paint> Acrylic resin solutions shown in Table 3 (solid content 50%; organic solvent Solvesso #
150, ethylene glycol monobutyl ether 4:
1), a melamine resin solution [“Cymel 370” (trade name, manufactured by Mitsui Toatsu Chemicals, Inc.); solid content 88%;
Organic solvent isobutanol and isopropanol 1: 1 mixed solvent) and a hard extender pigment are mixed and dispersed, and then paratoluenesulfonic acid and an organic solvent (ethylene glycol monobutyl ether, isobutanol, Solvesso # 150). Mixed solvent consisting of 1: 1: 3 of
A clear top coat paint having a pigment dispersity of 30 μm or less by the Grindge A method was prepared. In the Examples and Comparative Examples, a coating viscosity of 80 seconds was prepared with a diluting solvent (solvent of Solvesso # 150, isobutanol, diethylene glycol monobutyl ether 7: 2: 1) immediately before coating. A clear topcoat paint was used.

[Examples 1 to 7 and Comparative Examples 1 to 8] Galvanized steel sheet (0.5 mm thick) which has been subjected to zinc phosphate chemical conversion treatment.
Reversing type roll coater [peripheral speed ratio (peripheral speed of backup roll: peripheral speed of coating roll: peripheral speed of pickup roll) 1: 1.4: 0.4 ], The above undercoat paint was applied under the condition of a line speed of 35 m / min.
It was baked at T210 ° C. for 40 seconds.

Next, a reverse type roll coater [peripheral speed ratio (peripheral speed of backup roll: peripheral speed of coating roll: peripheral speed of pickup roll) 1: 1.2 : 0.
3], the intermediate coating composition was applied under the condition of the line speed of 35 m / min and baked at PMT 200 ° C. for 40 seconds.

Then, the above ink was used for gravure printing, and printing was carried out, followed by baking at PMT 200 ° C. for 60 seconds.

Next, the above-mentioned clear topcoat paint was applied under the same conditions as the intermediate coat and baked at PMT 241 ° C. for 40 seconds. For the coatings that could not be coated at a speed of 35 m / min, the coating film obtained at the maximum speed was tested for hardness, stain resistance, bendability, and appearance, and the results are shown in Table 4.

Further, the maximum line speed of a reverse type roll coater [peripheral speed ratio 1: 1.2: 0.3] with an intermediate coating was tested, and the results are shown in the lower row of Table 2. .. The test method was as follows. Hardness: According to JIS K-5400. Antifouling property ... Acrylic lacquer (black) was applied and the ease of peeling of the coating film was evaluated. (A) Peeling by cellophane tape 5: 100% peeling, 4:80 to 99% peeling, 3:50 to 79% peeling, 2:10 to 49% peeling, less than 1: 10%. (B) Peeling by rubbing gauze soaked with benzene 5: Peeling times within 5 times, 4: Peeling times 6 to 15 times, 3: Peeling times 16 to 30 times, 2: Peeling times 31 to 100 times, 1: Peeling frequency is 101 times or more. Bendability: A coating film state was observed by bending 180 ° of 20 mmφ. ○: No abnormality in coating film Х: Crack, crack or peeling occurs in coating film. Maximum line speed of middle coating: Pickup property is insufficient and the coating film becomes uneven, which is the limit line speed (m / mi
n) was measured.

As is clear from Tables 4 and 2, the coating film performance and design of the examples obtained by the method of the present invention were excellent, and the coating line speed was also practical.

On the other hand, Comparative Example 1 using a polyester resin having a low Tg has a low hardness, and conversely Comparative Example 2 using a polyester resin having a high Tg has a poor processability and a topcoat having a small amount of a hard extender pigment. Comparative Example 3 using the clear paint has a low hardness, and Comparative Example 4 using an acrylic resin having a low Tg has a poor antifouling property and a low hardness. Further, Comparative Example 5 using an acrylic resin having a low molecular weight is poor in processability, Comparative Example 6 in which a hard extender pigment is not mixed has low hardness, and conversely, Comparative Example 7 in which a hard extender pigment is excessively mixed is processed. Comparative Example 8 in which the silicone oil was not mixed was poor in antifouling property.

[0044]

As described above, according to the present invention, it is possible to form a smooth coating film capable of easily artificially peeling off a paper sticker, graffiti, etc., with good coating workability, and at the same time, to obtain a decorative board. Even when subjected to a forming process such as cutting or bending, it is possible to maintain an excellent coating film that is unlikely to cause cracking or peeling, and thus it is possible to obtain a decorative metal plate having a good design pattern finish.

[0045]

[Table 1]

[0046]

[Table 2]

[0047]

[Table 3]

[0048]

[Table 4]

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Reference number within the agency FI Technical display location B05D 7/24 302 V 8616-4D S 8616-4D P 8616-4D (72) Inventor Natsuhiko Akita 4-1-1 Minamihonmachi, Chuo-ku, Osaka-shi, Osaka Prefecture Inside the Yodogawa Steel Works (72) Inventor Osamu Terao 1-22-10 Taishibashi, Asahi-ku, Osaka-shi, Osaka (72) Takashi Yamaguchi Kobe-shi, Hyogo Prefecture Hyogo Prefecture 249-6 Hirano-cho, Tokyo

Claims (1)

[Claims] 1. A glass transition temperature of 5 to 70 on a metal plate.
C., consisting of a polyester resin having a number average molecular weight of 4500 to 35000, an aminoplast resin which is a curing agent, and 30 to 100 parts by weight of a pigment and 100 parts by weight of an organic solvent based on 100 parts by weight of the total amount of the polyester resin and the curing agent. An undercoat paint having a pigment dispersity of 15 μm or less in the Grindage A method is applied to a dry film thickness of 3 to 10 μm, baked and dried, and then the glass transition temperature is 60 to 200 ° C. and the number average molecular weight is 5000.
~ 100,000, weight average molecular weight 20000-1500
No. 00 acrylic resin and aminoplast resin which is a curing agent, and 50 to 150 parts by weight of a color pigment, and an average particle diameter of 5 μm with respect to 100 parts by weight of the total amount of the acrylic resin and the curing agent.
It comprises 5 to 50 parts by weight of the following hard extender pigments and the required amount of an organic solvent containing high boiling ether alcohols, and the degree of dispersion of the pigment is an intermediate coating composition of 15 μm or less of the Grindage A method. 30 μm, then the intermediate coating film is subjected to pattern printing on the entire surface or a part thereof, and baked and dried. Then, the entire surface has a glass transition temperature of 60 to 200 ° C. and a number average molecular weight of 15,000 to 100,000. , Weight average molecular weight 20000
~ 150,000 acrylic resin and aminoplast resin which is a curing agent, and the total amount of the acrylic resin and the curing agent is 1
It is composed of 30 to 80 parts by weight of a hard extender pigment having an average particle diameter of 30 μm or less, 0.01 to 10 parts by weight of silicone oil, and a required amount of an organic solvent containing high boiling point ether alcohols, relative to 00 parts by weight. A method for producing a decorative metal plate having a coating film having a hardness of 9H or more, which is obtained by applying a clear coating material to a dry film thickness of 10 to 30 µm and baking and drying.