JPH0623319A - Method for manufacturing fabricated product of coated metal plate - Google Patents

Abstract

PURPOSE:To provide a method for manufacturing a fabricated product of coated metal plate where a uniformly thick, highly contamination-resistant coat with high hardness can be formed by donating workability over time and high hardness contrary to the former and high contamination resistance to the coat formed using a precoat metal technique. CONSTITUTION:The subject method for manufacturing a fabricated product of coated metal plate comprises a step (I) to apply a paint which contains (A) a polymer with a polymerizable double bond and a crosslinkable hydroxyl and (B) a blocked polyisocyanate compound to a metal plate and form a primary cured coat by irradiation an with an active energy beam, a step (II) to mold and fabricate the metal plate with the formed primary cured coat, and a step (III) to bake the molded and fabricated metal plate and thereby cure the primary cured coat completely.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a coating film on the surface of a product formed by processing a metal plate (hereinafter referred to as a metal plate processed product), which has a particularly complicated shape. The present invention relates to a method for producing a coated metal plate processed product, which can form a uniform coating having a high hardness and a high stain resistance on the surface of the metal plate processed product.

[0002]

2. Description of the Related Art Conventionally, electric appliances, kitchen appliances, office equipment,
For the coating of roofing materials, outer wall siding materials, etc., the so-called post-coating method, in which an unpainted metal plate is formed by cutting, bending, squeezing, etc. and then painting, is the mainstream. The coating method is not only poor in coating workability, but also when the object to be coated has a complicated shape,
There was a problem that it was difficult to coat the entire surface uniformly. Therefore, a plate-shaped or coil-shaped metal plate such as a galvanized steel plate, a cold-rolled steel plate, an aluminum plate, and a stainless plate is pre-painted, the coating film is hardened, and then this coated metal plate is formed and processed. The (PCM) method has been adopted. But,
The coating film formed by the precoat metal method has the workability (that is, flexibility) of the coating film that can follow the elongation and bending of the metal material during the forming process, and at the same time, the high processability that is contradictory to this processability after the forming process. There is a contradiction that hardness and stain resistance are required. For this reason, a paint for precoat metal that satisfies both requirements has not been developed yet.

Conventionally, as a paint or coating method used in the precoat metal method, a composition comprising a polyester resin, a curing agent therefor and a radiation-curable monomer or oligomer is undercoated on a metal plate and heat-cured, followed by radiation. A method of overcoating a curable coating and radiation curing (JP-A-62-125879), a polyester resin having active hydrogen, an electron beam and a heat containing a compound having a group capable of reacting with active hydrogen as an essential component. A coating composition (Japanese Patent Laid-Open No. 102279/1990) that cures with a coating composition has been developed. A coating film formed from these coating materials has sufficient processability but has a drawback of low hardness. On the contrary, the method disclosed in Japanese Examined Patent Publication No. Sho 56-8070 has the drawback that the hardness of the coating film is very high, but the workability is insufficient. Coating which satisfies both properties of high workability and high hardness was not obtained. Further, a coating composition using both ultraviolet curing and heat curing is generally known (for example, JP-A-60-112865 and JP-A-2-103216), but the hardness of the obtained coating film is still high. , Was inadequate.

[0004]

DISCLOSURE OF THE INVENTION The present invention solves the problems of the prior art, and gradually imparts processability and contradictory high hardness and stain resistance to the coating film formed by the precoat metal method. By doing so, it is an object of the present invention to provide a method for producing a coated metal plate product, which can form a uniform coating film with high hardness and high stain resistance on the surface of the metal plate product.

[0005]

[Means for Solving the Problems] That is, the present invention provides a method for producing a coated metal plate product, comprising: (I) a metal plate having (A) a polymerizable double bond and a crosslinkable hydroxyl group. And (B) a step of applying a coating material containing a blocked polyisocyanate compound, irradiating with active energy rays to form a primary cured coating film, (II) a metal plate on which a primary cured coating film is formed. The present invention provides a manufacturing method characterized by including a step of forming and (III) baking a formed metal plate to completely cure the primary cured coating film. Hereinafter, the present invention will be described in detail.

The coating composition used in the present invention mainly comprises a polymer (A) having a polymerizable double bond and a crosslinkable hydroxyl group and a blocked polyisocyanate compound (B) which reacts with the hydroxyl group by heating. It is what This coating composition is applied to a metal plate and then irradiated with active energy rays so that the polymerizable double bond of the polymer (A) reacts and undergoes radical polymerization to form a primary cured coating film. . At this stage, the blocked polyisocyanate compound (B) in the composition does not substantially cross-link with the polymer (A), so that the primary cured coating film has flexibility and processability. Highly excellent coating film. Such a highly workable primary cured coating film can easily follow the elongation and bending of the metal material during the metal plate forming process. Molding can be performed while maintaining uniformity and aesthetics without causing cracks or cracks on the painted surface. After further molding, by baking this primary cured coating film, the hydroxyl groups in the polymer (A) and the blocked polyisocyanate compound (B) react, forming a crosslinked structure in a network, A coating film having high hardness and excellent stain resistance can be obtained.

As the polymer (A) used in the present invention, conventionally known polymers having a polymerizable double bond and a crosslinkable hydroxyl group can be used without any particular limitation. Among them, vinyl polymers Unsaturated polyester resins, epoxy resins, fluororesins, and the like can be mentioned as typical ones. Of these, the following vinyl polymers are particularly preferable. This vinyl polymer having a polymerizable double bond and a crosslinkable hydroxyl group has a hydroxyl value of about 10 to 120 mg.
KOH / g, especially 30 to 100 mg KOH / g, and containing 0.01 to 0.2 of the polymerizable double bond per 100 g of the polymer.
Mol, particularly 0.05 to 0.15 mol, and 50% by weight or more of methyl methacrylate unit in the main chain of the polymer, especially 65 to
90% by weight is preferred. The weight average molecular weight of the vinyl polymer is preferably 10,000 to 300,000, particularly preferably 30,000 to 200,000. In addition to the hydroxyl group, a functional group such as a carboxyl group or an amino group may be used in combination as the functional group.

As a method for producing such a vinyl-based polymer, a vinyl copolymer (X) having a functional group is prepared by adding an ethylenically unsaturated monomer (Y) having a functional group reactive with the functional group. ) Can be mentioned as a typical method. However, the copolymer (X) and the monomer (Y)
It is necessary to make at least one of the functional groups of the above a part or all of them into a hydroxyl group and react them so that the hydroxyl groups remain in the above proportion even after both react. In addition, since the glycidyl group also changes into a hydroxyl group by the reaction, it is possible to use the copolymer (X) or the monomer (Y) having a glycidyl group. As the vinyl copolymer (X), methyl methacrylate and a functional group-containing ethylenically unsaturated monomer (A), or those and other ethylenically unsaturated monomers
(B) and, for example, in the presence of an ordinary peroxide-based or azo-based radical polymerization initiator at about 80 to 140 ° C. for 3 to 10
A typical example is a copolymer obtained by reacting for a period of time.

Typical examples of the ethylenically unsaturated monomer (A) include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, and glycoloxy (meth) acrylate. Hydroxyl group-containing monomers such as ethyl; carboxyl group-containing monomers such as (meth) acrylic acid; glycidyl group-containing monomers such as glycidyl (meth) acrylate; (meth) acrylic acid-t-butylaminoethyl and the like Amino group-containing monomers; amine-methacrylimides such as trimethylamine-methacrylimide, N-methylolacrylamide, Nn-butoxymethylacrylamide, acrylamides and the like. In addition, typical examples of the other ethylenically unsaturated monomer (B) include methyl acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, and n-butyl. (Meth) acrylic such as (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, dodecyl (meth) acrylate, cyclohexyl (meth) acrylate. Acid esters; Substituted styrenes such as styrene, vinyltoluene, α-methylstyrene, chlorostyrene; (meth) acrylonitrile, vinyl chloride, vinyl formate, vinyl acetate, vinyl propionate, vinyl stearate, dialkyl maleate Divinylbenzene and the like. The ethylenically unsaturated monomer (Y)
Is a polymerizable double bond in the vinyl copolymer (X) and /
Alternatively, in order to introduce a hydroxyl group, a vinyl copolymer (X)
React with.

As the ethylenically unsaturated monomer (Y), when the functional group in the vinyl copolymer (X) is a hydroxyl group, the carboxyl group-containing monomer and the glycidyl group-containing monomer are included. Body, amine-methacrylimides, acrylamides, isocyanate group-containing monomers such as isocyanate ethyl (meth) acrylate,
When the functional group in the vinyl copolymer (X) is a carboxyl group, it is the glycidyl group-containing monomer, amine-methacrylimides, acrylamides, amino group-containing monomer, or the like, and the vinyl copolymer is further included. When the functional group in (X) is a glycidyl group, it is the above-mentioned carboxyl group-containing monomer, hydroxyl group-containing monomer, amino group-containing monomer, amine-methacrylimides or acrylamides. When the functional group in the vinyl copolymer (X) is an amino group, the isocyanate group-containing monomer, the carboxyl group-containing monomer, the glycidyl group-containing monomer and the like can be mentioned as typical ones. . These ethylenically unsaturated monomer (Y) and vinyl copolymer (X) can be reacted in the presence of an ordinary catalyst at 0 to 150 ° C. for 30 minutes to 15 hours.

The polymer (A) can be produced under the above-mentioned starting materials and conditions, but the reactivity of the polymer (A) with the blocked polyisocyanate compound (B) is increased, and the polymer (A) A functional group other than a hydroxyl group may be added to the polymer (A) in order to impart adhesiveness and the like. As the blocked polyisocyanate compound (B) which is a cross-linking agent, those conventionally used as a cross-linking agent for thermosetting coatings can be used as they are. Representative examples of this compound (B) are hexamethylene diisocyanate, tetramethylene diisocyanate, isophorone diisocyanate, hydrogenated phenyl diisocyanate, hydrogenated xylene diisocyanate, tolylene diisocyanate,
Diphenylmethane diisocyanate or buret, dimers, trimers of these, and an excess amount of these polyisocyanate compounds and ethylene glycol,
Glycerin, polyisocyanates such as reaction products with low molecular weight polyols such as pentaerythritol are phenols, alcohols, oximes, lactams,
There are blocked polyisocyanate compounds masked with masking agents such as amines and amides.

When the active energy ray irradiated in the manufacturing process is ultraviolet rays, a photopolymerization initiator must be added to the coating composition used in the present invention. Specific examples of the photopolymerization initiator include benzoin, benzoin alkyl ethers, anthraquinone derivatives, benzanthrone derivatives, and 2,2-dimethoxy-.
2-phenylacetophenone, 1-hydroxycyclohexyl phenyl ketone, 2-methyl- [4- (methylthio) phenyl] -2-morpholino-1-propane, benzyl derivative, benzophenone derivative, xanthone derivative, thioxanthone derivative, bisimidazoles, acyl Phosphines, 4,4'-bis-dimethylaminobenzophenone, trichloromethyl-8-triazine,
There are 3,4,3 ', 4'-tetra (t-butylperoxycarbonyl) benzophenone and the like, and combinations of these with amine compounds and the like. These should be used alone or as a mixture of two or more kinds. You can

In the coating composition used in the present invention, the polymer (A) and the blocked polyisocyanate compound (B) are the same as those in the coating composition such as the isocyanate group of the compound (B) and the hydroxyl group of the polymer (A). Of the total active hydrogen of 0.2
: 1 to 3.0: 1, particularly 0.8: 1 to 1.5: 1. Further, the photopolymerization initiator, 0.05 to 10 parts by weight, particularly 100 parts by weight of the polymer (A),
It is preferably used in a proportion of 0.1 to 6 parts by weight. However, when the active energy rays are high-energy radiation other than ultraviolet rays, they may be blended as necessary. In the coating composition used in the present invention, if necessary, various reactive oligomers, reactive diluents, non-reactive diluents, color pigments, extender pigments, plasticizers, other dispersants, polymerization inhibitors, Various additives such as a crosslinking catalyst can be blended. As the oligomer, a number average molecular weight of 500 to 10,00
Examples of the urethane (meth) acrylate oligomer, epoxy (meth) acrylate oligomer and the like. These oligomers are suitably added in an amount of 20 parts by weight or less, preferably 2 to 5 parts by weight, based on 100 parts by weight of the polymer (A).

Examples of the reactive diluent include glycidyl (meth) acrylate, glycerol (meth) acrylate and glucoxy (meth).
Acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate,
Ethylene oxide modified phosphoric acid (meth) acrylate,
Monomers having a polymerizable double bond and a crosslinkable hydroxyl group, such as ethylene oxide, butanol modified phosphoric acid (meth) acrylate, ethylene glycol di (meth) acrylate, and trimethylolpropane tri (meth) acrylate.
A monomer having a polymerizable double bond and a crosslinkable carboxyl group such as (meth) acrylic acid, other methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, propyl (meth) acrylate, hexyl ( (Meth) acrylate, octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, vinyltoluene, styrene, vinyl acetate, vinyl isobutyl ether, 2-ethylhexyl vinyl ether, acrylonitrile, N-vinylbenzene, dimethyl (meth)
For example, acrylamide.

As the non-reactive diluent, for example, toluene, xylene, ethyl acetate, butyl acetate, methyl cellosolve, ethyl cellosolve, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, diethylene glycol monoethyl ether acetate, For example, water. These diluents have a coating composition viscosity of about 20 to 150 seconds (Ford Cup No. 4 /
It is desirable to blend it so that it becomes 20 ° C). Next, each step of the manufacturing method of the present invention will be described. First, in the step (I), a wide range of metal plates such as a galvanized steel plate, a cold-rolled steel plate, an aluminum plate, and a stainless plate, which are selected according to the purpose of use, are subjected to degreasing treatment, surface treatment, primer as necessary. The coating composition is applied, and the coating composition is applied to the metal plate by means such as spray coating, roller coating and curtain flow coating. It is appropriate that the coating amount is such that the dry film thickness is about 10 to 300 μm. Then, the coating surface is irradiated with active energy rays to cure the coating film, thereby forming a primary cured coating film. When using a coating composition containing a non-reactive diluent, it is preferable to evaporate the non-reactive diluent in the coating film before irradiating with active energy rays. At this time, the polymer
(A) hydroxyl group and blocked polyisocyanate compound
(B) and the temperature at which the crosslinking reaction does not occur (for example, 120
You may heat-process at (degreeC or less).

In the present invention, X is used as the active energy ray.
Rays, α-rays, β-rays, γ-rays, high-energy radiation such as electron rays and neutron rays, and ultraviolet rays can be used, but particularly when ultraviolet rays are used, a photopolymerization initiator is added to the coating composition of the present invention. Need to be added. Typical examples of electron beam sources include Cockcroft type, Van de Graaf type, resonant transformer type, dynamitron type, and high frequency type, and the dose is set to 0.1 to 20 megarads. Is appropriate. Typical examples of the ultraviolet ray irradiation source include a mercury lamp, a xenon lamp, a metal halide lamp, a carbon arc, and the like, and an irradiation amount of about 200 to 2000 mj / cm ² is suitable. In this way, the coating film is cured by the active energy ray in the step (I) to form a primary cured coating film. In addition, at the stage of completing the step (I), the polymer (A)
Functional groups in (and functional groups in reactive diluents) and crosslinkers
Substantially no reaction with (B).

Next, in the step (II), the coated metal plate obtained in the step (I) is formed into a desired shape by cutting, bending, squeezing or the like. The coated metal plate obtained in the step (I) does not need to be immediately subjected to the forming process in the step (II), but can be formed after being stored for a certain period of time. After forming the coated metal plate in this way, in step (III), put it in a heating furnace etc. to perform baking treatment, and to remove the functional group of the polymer (A) (and the functional group in the reactive diluent). By crosslinking reaction with the crosslinking agent (B), the primary cured coating film is completely cured to form a coating film having high hardness and excellent stain resistance. The baking conditions are such that the masking agent dissociates at a temperature of, for example, about 130 to 300 ° C. and about 1 to 30.
It is suitable to heat for a minute. In the present invention, a coated metal plate processed product is produced as described above, but when the coated metal plate is irradiated with an active energy ray, the purpose is to prevent the curing of the coating film by oxygen, or to prevent damage to the coating film or the like. Then, it is desirable to laminate a protective film of polyethylene, polyethylene terephthalate or the like with a thickness of 20 to 1000 μm before or after irradiating the coated metal plate with active energy rays. The protective film is removed before starting the baking step (III).

[0018]

According to the manufacturing method of the present invention, when a coated metal plate is formed and processed, a primary cured coating film having good flexibility and high workability is formed on the surface of the metal plate. Even when molding is performed, the coating film easily follows the elongation and bending of the metal material, maintaining the uniformity and aesthetics of the coating film, and the coating surface is free from cracks and cracks. After the molding process, the primary cured coating film is baked to form a network-like crosslinked structure in the coating film, and a final coating film having high hardness and excellent stain resistance can be obtained. That is, the workability of the primary cured coating film (JIS G3312 12.2 inner spacing of bending: 0 plate of the indicated thickness) is OT, and the pencil hardness of the final coating film (JIS
K5400 8.4.2) gives coatings of 5H and above, therefore
INDUSTRIAL APPLICABILITY The present invention and the metal plate molded product produced by the present invention have high industrial utility value.

[0019]

(Synthesis of polymer (A))

(Synthesis Example 1) 103.7 parts of butyl acetate was charged into a four-necked flask, heated to 92 ° C. in a nitrogen stream, and stirred with stirring, 128.5 parts of methyl methacrylate and ethyl acrylate.
15.5 parts, acrylic acid 9 parts and butyl acetate 125 parts to tertiary butyl peroxy 2-ethylhexanoate.
A mixture prepared by dissolving 3 parts in advance was added dropwise over 3 hours. Then, the temperature was raised to 98 ° C. over 1 hour, and a mixture of 0.3 part of tert-butyl peroxy 2-ethylhexanoate in 90 parts of butyl acetate was added dropwise over 2 hours, and further 2 hours. Aged. Next, 0.25 parts of hydroquinone and 0.1 part of triethylamine were added, the temperature was raised to 130 ° C., 17.7 parts of glycidyl methacrylate was added, and the reaction was carried out for 2 hours. The obtained polymer has a solid content concentration.
It was 35% and the weight average molecular weight was 17 × 10 ⁴ (polymer (A-
1).

(Synthesis Example 2) 103.7 parts of butyl acetate were charged into a four-necked flask, heated to 92 ° C. in a nitrogen stream, and then 111.8 parts of methyl methacrylate, 5.5 parts of ethyl acrylate while stirring. 18 parts acrylic acid and 1 butyl acetate
A mixture in which 0.3 parts of tertiary butyl peroxy 2-ethylhexanoate was dissolved in 25 parts in advance was added dropwise over 3 hours. Then, the temperature was raised to 98 ° C over 1 hour, and tert-butyl peroxy 2 was added to 90 parts of butyl acetate.
-2 parts of a mixture containing 0.3 parts of ethylhexanoate dissolved.
The mixture was dropped over a period of time and aged for 2 hours. Then add 0.25 parts of hydroquinone and 0.1 parts of triethylamine,
After the temperature was raised to 0 ° C., 35.4 parts of glycidyl methacrylate was added and reacted for 2 hours. The resulting polymer had a solid content concentration of 35% and a weight average molecular weight of 19 × 10 ⁴ (polymer (A-
2)).

(Synthesis Example 3) 10.1 parts of methyl isobutyl ketone was charged into a four-necked flask, and the mixture was heated to 92 ° C in a nitrogen stream.
After heating up to 95 parts, under stirring, 95 parts of methyl methacrylate,
A mixture of 11.4 parts of ethyl acrylate, 32.4 parts of 2-hydroxyether methacrylic acid and 125 parts of methyl isobutyl ketone and 0.45 parts of tertiary butyl peroxy 2-ethylhexanoate was previously added dropwise over 3 hours. Then, the temperature was raised to 98 ° C. in 1 hour, and a mixture of 90 parts of methyl isobutyl ketone and 0.3 part of tert-butyl peroxy 2-ethylhexanoate was added dropwise over 2 hours. Aged for hours. After cooling to 80 ° C, 2.5 parts of dibutyltin dilaurate, 3-isopropenyl-α, α-dimethylbenzyl isocyanate.
26.3 parts were added and reacted for 2 hours. The obtained polymer is
The solid content was 35% and the weight average molecular weight was 9 × 10 ⁴ (polymer (A-3)).

Examples and comparative examples were carried out as follows. First, the components were mixed in the proportions shown in Table 1, and the obtained compositions were each treated with ethyl acetate to give a viscosity of 70 seconds (Ford Cup No. 4
/ 20 ° C). These compositions were dried on a stainless steel substrate using a curtain flow coater to give a dry film thickness of 30 μm.
And was dried at 80 ° C. for 5 minutes to evaporate the diluent. Next, a transparent polyethylene film with a thickness of 50 μm was applied as a protective film, and exposed with ultraviolet rays from a high-pressure mercury lamp with a light intensity of 120 w / cm from a distance of 10 cm at a substrate speed of 5 m / min to obtain a first cured coating film. Got The obtained substrate was subjected to a 180 ° T-bending process and a blocking creep test. The cracks and peeling of the bent portion and the blocking and creep test were evaluated after heat curing. After removing the protective film from the substrate that was bent and the like, it was heat-cured at 150 ° C. for 30 minutes to obtain a final coating film. The final cured coating film was tested for hardness, stain resistance and impact resistance. The obtained results are shown in Table 2.

[0023]

[Table 1]Table 1(Recipes) (Parts by weight of solids) ──────────────────────────────────Polymer (A) Cross-linking agent (B)⁽¹⁾ Photopolymerization Other Examples A-1 A-2 A-3 Initiator⁽²⁾ Ingredients ────────────────────────────────── 1 50 13 1.4 2 50 13 1.4 5⁽³⁾ 3 50 26 1.4 4 50 26 1.4 2^(Four) 5 50 13.4 1.4 6 50 13.4 1.4 5⁽³⁾ ──────────────────────────────────── Comparative example 1 50 1.4 30^(Five) 2 50 26 3 50 13.4 5⁽³⁾ ──────────────────────────────────── (1) Blocked polyisocyanate: Coronate 2507
[Product name, manufactured by Nippon Polyurethane Industry Co., Ltd.], NV = 81
%, Effective isocyanate content = 11.8% (2) Benzophenone as a photopolymerization initiator 1 part and Michler
Use a mixture with 0.4 parts of ketone (3) Silica pigment (4) Urethane acrylate oligomer: Aronix M
1100 [Brand name, Toagosei Co., Ltd.] (5) CH₂= CHCOOCH₂-C (CH₂OCOCH = CH₂)₂CH₂OCOCH = CH₂

[0024]

[Table 2] Table 2 [Test Results] ────────────────────────────────── Brockin 'Grief Bend Pencil Resistance Impact Stain resistance Example Recovery rate ⁽⁶⁾ Workability ⁽⁷⁾ Hardness ⁽⁸⁾ Property ⁽⁹⁾ Property ⁽¹⁰⁾ ──────────────────────── ────────── 1 ○ Pass 5H ○ ○ 2 ◎ Pass 5 ~ 6H ○ ○ 3 ◎ Pass 5H ○ ○ 4 ◎ Pass 5 ~ 6H ○ ○ 5 ○ Pass 5H ○ ○ 6 ◎ Pass 5 ~ 6H ○ ○ ───────────────────────────────── Comparative Example 1 ○ Failure 4H × △ 2 × Failure 5H ○ ○ 3 ○ Fail 5H ○ ○ ──────────────────────────────────

(6) Blocking / creep recovery rate: The film after UV curing was subjected to longitudinal deformation of 20, 30 and 50% of the film thickness, and applied to the film at 40 ° C. of 40 kg / cm ² . Pressure was applied for 8 hours to evaluate how much the resulting deformation had recovered after the final heat cure. ◎: Deformation disappears even at 50% ○: Deformation disappears at 30% △: Deformation disappears at 20% ×: Deformation remains even at 20% (7) Bending workability: JIS-K-5400, After U-bending in advance with a bending vise specified in Section 8.1 (bending resistance), crush with a vise and observe the coating state of the bend R part with a 30 times magnifier to check that the coating does not crack. Passed, and those with cracks etc. were rejected. (8) Pencil hardness: JIS-K-5400, 8.4.2 using Mitsubishi Uni-Pencil
Tested according to paragraph. (9) Impact resistance: JIS-K-5400, Item 8.3.2, using a DuPont impact tester, a 300 g weight is dropped onto the surface of the coating film on which a hemispherical die with a radius of 6.35 mm is placed. ◎: 20 cm or more without any abnormality ○: 10 cm without cracks ×: 10 cm with cracks

(10) Contamination resistance: Draw on the surface of the coating film with a magic ink (manufactured by Yoko Uchida) at 20 ° C., leave it for 24 hours, wipe ethanol with gauze, wipe off, and evaluate after line. ◯: No traces remained at all Δ: Slight traces remained ×: Traces remained clear As is clear from the test results in Table 2, the coating films of the coated metal sheets of Examples 1 to 6 obtained by the method of the present invention. Had good workability, high hardness, and excellent stain resistance and impact resistance.
On the other hand, Comparative Example 1 using a coating material containing no cross-linking agent had poor workability and impact resistance, and had a hardness lower than that of the present invention. It is considered that this is because the coating film is only polymerized and cured by irradiation of ultraviolet rays and there is no crosslinking reaction between the polymer (A) and the blocked polyisocyanate compound (B). Also,
Despite the use of ultraviolet rays as the active energy rays, Comparative Examples 2 and 3 using the paint containing no photopolymerization initiator had poor processability. It is considered that this is because the coating is only cured by the crosslinking reaction between the polymer (A) and the crosslinking agent (B), and is not cured by ultraviolet irradiation.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location B05D 7/24 301 T 8720-4D R 8720-4D 302 T 8720-4D

Claims (3)

[Claims] 1. A method for producing a coated metal plate product, comprising: (I) a metal plate having (A) a polymer having a polymerizable double bond and a crosslinkable hydroxyl group, and (B) a blocked polyisocyanate compound. Of coating with a coating material containing, and irradiating with active energy rays (excluding ultraviolet rays) to form a primary cured coating film, (II) Step of forming a metal plate on which a primary cured coating film has been formed And (III) a method for producing a coated metal sheet product, which comprises a step of baking a formed metal sheet to completely cure the primary cured coating film. 2. A method for producing a coated metal plate product, comprising: (I) a metal plate having (A) a polymer having a polymerizable double bond and a crosslinkable hydroxyl group, and (B) a blocked polyisocyanate compound. And (c) a step of applying a paint containing a photopolymerization initiator and irradiating ultraviolet rays to form a primary cured coating film, (II) forming a metal plate on which a primary cured coating film is formed And (III) baking the formed metal plate to completely cure the primary cured coating film. 3. The protective film is laminated on the surface of a coated metal plate before or after the irradiation with the active energy ray, and the protective film is removed before baking. Manufacturing method of painted metal sheet products.