JPH0659717B2 - Coated surface treated metal plate - Google Patents

Description

Detailed Description of the Invention

[0001]

[Industrial application] The present invention is used for building materials such as roofing materials and wall materials, automobiles, home appliances, soundproof / windproof, civil engineering products such as sand barriers and guardrails, and agricultural products such as agricultural pipes. Regarding the coated surface-treated metal plate used for coating the surface, the metal plate to be treated means aluminum-zinc alloy plated metal plate, aluminized metal plate, stainless steel plate, aluminum plate and other plating A metal plate or the like.

[0002]

2. Description of the Related Art This type of metal plate is used while showing a bare surface having a metallic luster, but it is often subjected to a chromate treatment as a primary rust preventive treatment against moisture during storage. However, when the chromate treatment is left as it is, the surface of the metal plate has no lubricity, and flaws and abrasions are generated during the molding process, which lowers the product value. Therefore, in order to provide lubricity to the metal plate surface, wax or oil has been applied. However, when wax or oil is used, the molding line itself may be contaminated by these, or the metal plate with these adhering to the surface may be sent to the next step and cause problems. It was necessary to remove oil and wax adhering to prevent this. Furthermore, since this removal produces a degreasing waste liquid, an extra step and labor for treating this is required. As one method for solving these problems, a water-soluble organic film is formed on a metal plate and dried with hot air (a plate temperature of 80
It was also carried out to obtain a coated metal plate with improved moldability and durability.

[0003]

Nevertheless, the above-mentioned metal plate coated with the water-soluble organic coating also has aluminum-zinc alloy-plated metal plates (Al = 55 wt%, Zn = 4) as metal plates.
As an example of the case of a metal plate plated with an alloy having a composition of 3.4 wt% and Si = 1.6 wt%, there were the following problems.

First, when the roll forming or press forming is performed, the lubricity between the coated aluminum-zinc alloy plated metal plate and the forming roll surface or the press die may be insufficient. However, it is impossible to completely prevent the peeling of the plating layer (metal pickup) due to abrasion. This reduces the design of the appearance of the metal plate. The part where the metal pickup is produced may turn black due to the molding feed, which may lower the commercial value. When a metal pickup occurs, seizure occurs on a molding roll or a press die, making it impossible to continuously pass through the sheet during molding, which necessitates cleaning of the entire molding machine, resulting in a significant decrease in workability.

Secondly, a water-soluble or water-dispersible resin is used for this coating treatment agent, which is applied on both sides of a metal plate, dried, cooled, wound into a coil and put on the market. The coatings that come into contact with each other may adhere to each other. Then, at the time of unwinding in the next step such as molding, noise is generated due to peeling between the adhered films, and if the adherence becomes severe, blocking occurs, the surface of the film is roughened, and the appearance becomes poor. Even after being processed into a sheet form from a coil form, due to the excessive adhesion of the films due to the stacking of the sheets, the feeding to the molding machine in the next step cannot be performed smoothly and the work efficiency is reduced.

Thirdly, it is easy to combine this with the fact that the water permeability of this resin film and the durability of the film itself are not very strong due to contact with an acidic or alkaline solution, and that the aluminum-zinc alloy plating layer is an amphoteric metal. A blackening phenomenon occurs on the surface, and the design of the appearance is impaired (this performance is hereinafter referred to as chemical resistance performance). As an example of this phenomenon, when such a metal plate is used as a roofing material for building materials and the wall material that intersects with the roof is slate, contact with the alkaline component eluted from the slate due to rainfall, and slate during slate construction There is an example of the blackening phenomenon caused by the rainfall caused by contact with the roofing material due to the mistreatment of the leftover material.

Therefore, an object of the present invention is to provide a surface having lubricity, which can prevent excessive adhesion, excellent chemical resistance (particularly alkali resistance) and corrosion resistance, and can be used for post-coating properties of normally dry or dry type paints. The object is to obtain a coated surface-treated metal plate having a film with good spot weldability. The metal plate subjected to the coating surface treatment is an aluminum-zinc alloy plated metal plate, an aluminum plated metal plate, a stainless steel plate, an aluminum plate, or other plated metal plate.

[0008]

The present invention is a coated surface-treated metal plate having a resin film on the surface of a metal plate, the resin film having a radical-polymerizable anionic and / or nonionic reactivity. 0.5 to 5 wt% emulsifier per solid resin content
%, An acrylic emulsion resin obtained by emulsion-polymerizing an α, β-ethylenically unsaturated monomer so as to have a resin acid value of 0 to 9;
0.1 to 2 parts by weight of hexavalent chromium, and 0.5 to 5 parts by weight
A film is formed using a coating composition obtained by mixing 5 parts by weight of a wax solid component and 5 to 50 parts by weight of a hydrophilic solvent and adjusting the liquidity to PH = 6 to 8. Is a requirement. In this coated surface-treated metal plate, the dry coating weight of the resin coating can be preferably 0.5 to 5 g / m ² .

The α, β-ethylenically unsaturated monomers used in the present invention include methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, n
-Butyl acrylate, n-butyl methacrylate, i
Acrylic acid alkyl esters and methacrylic acid alkyl esters such as so-butyl acrylate, iso-butyl methacrylate, tert-butyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, styrene, α-methylstyrene, tert-
Aromatic compounds such as butyl styrene, carboxyl group-containing monomers such as acrylic acid, methacrylic acid and itaconic acid,
Compounds such as hydroxyl group-containing monomers such as 2-hydroxyethyl acrylate and 2-hydroxyethyl methacrylate can be used alone or in combination of two or more kinds.

Ereminol JS-2 is a reactive emulsifier.
(Manufactured by Sanyo Chemical Industry Co., Ltd.), New Frontier A229E
Anion type (made by Dai-ichi Kogyo Seiyaku Co., Ltd.), ADEKA REASOAP NE-20 (made by Asahi Denka Kogyo Co., Ltd.), Aqualon RN-
Nonionic type such as 20 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), anion-nonionic type such as Adecarya Soap SE-10N (manufactured by Asahi Denka Kogyo Co., Ltd.), and AQUARON HS-10 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) are used. be able to.

As a source of hexavalent chromium, ammonium chromate, chromic anhydride, etc. can be used.
As the chromic anhydride, it is preferable to use an ammonium salt which does not easily volatilize in the drying process after coating or a non-volatile alkali-containing one. Microcrystalline wax emulsion is used as the wax solid content, and examples thereof include Nopco 1245M-SN (manufactured by San Nopco). As the hydrophilic solvent, isopropyl alcohol (IPA), ethylene glycol monobutyl ether (butyl cellosolve), diethylene glycol monobutyl ether (butyl carbitol) or the like can be used.

In the present invention, a water-dispersible resin having the above composition is applied to the surface of a metal plate and dried to form a resin film. The coating is performed by a known coating means such as a roll coating method. Drying is performed by a known method such as a hot-air drying oven or an infrared lamp, and a film of resin is applied to the surface of the metal plate by evaporating water and the like to form a dry film. The resin film applied to the surface of the metal plate is coated on both sides or one side depending on the purpose of use and application.

The amount of the resin dry film is to ensure the lubricity in roll molding or press molding, to prevent the sounding phenomenon due to the excessive adhesion of the films when the coiled coated surface-treated metal plate is unwound, and the chemical resistance. Considering such things as one side
It is preferably 0.5 to 5 g / m ² . Further, when considering the spot weldability and the manufacturing cost, it is desirable that one side has 1 to 3 g / m ² .

[0014]

[Function] Since the emulsifier is a radically polymerizable reactive emulsifier, it is incorporated into the polymer chain of the α, β-ethylenically unsaturated monomer during film formation. Therefore, it is possible to prevent a phenomenon in which the emulsifier moves to the voids between the resin particles after the emulsion polymerization and is condensed there, and it is possible to suppress the water permeability after the film formation. The amount of the emulsifier added is 0.5 to 5 wt% based on the solid resin content,
This is because if it is less than 0.5 wt%, the stability during polymerization is poor and the resin may be aggregated, and if it exceeds 5 wt%, the water permeation suppression of the membrane itself becomes insufficient.

The resin acid value of 0 to 9 means that the acid value is 10
This is because the water permeability becomes high, the chemical resistance is lowered, and it becomes easy to be hydrolyzed by the contact with the acidic solution and the alkaline solution.

By using hexavalent chromium, a film formation promoting effect can be obtained in the process of forming the film of the acrylic emulsion resin, and the durability of the film itself can be improved accordingly. Add hexavalent chromium to the resin solid content 10
0.1 to 2 parts by weight with respect to 0 parts by weight means that this is 0.1.
This is because if the amount is less than 1 part by weight, the effect of suppressing water permeability is small, and if the amount is more than 2 parts by weight, aggregates are likely to be formed during mixing with the resin.

The wax solid component largely contributes to the lubricity of the formed film itself, and for that purpose, microcrystalline wax emulsion is suitable. This lubricity significantly impairs the appearance such as blackening of the surface of the metal plate due to metal pickup (peeling phenomenon of the plating component) due to abrasion between the film and the roll die in the roll molding or press molding of the metal plate described above. To prevent this. The amount of microcrystalline wax solid content added was 0.
The amount of 5 to 5 parts by weight is used because if it is less than 0.5 parts by weight, the lubricating performance is deteriorated, and if it exceeds 5 parts by weight, the water permeability is deteriorated and, as a result, the chemical resistance is deteriorated.

The use of the hydrophilic solvent strengthens the fusion bondability of the emulsion particles, and as a result, the effect of suppressing the water permeation of the film itself is increased. That is, it functions as a film-forming aid and greatly contributes to the improvement of chemical resistance and corrosion resistance. Hydrophilic solvent is 5 to 100 parts by weight of resin solid content.
The reason for adding 50 parts by weight is that if the amount is less than 5 parts by weight, the suppression of water permeability will be reduced, and if the amount exceeds 50 parts by weight, no further increase in effect will be obtained.

The reason why the liquidity of the coating composition is adjusted to PH = 6.0 to 8.0 is to prevent unnecessary chemical changes on the surface of the metal plate. Therefore, the coating composition after application stably forms a film, and the adhesion of the film to a metal plate, the flexibility of the obtained coated surface-treated metal plate, and the corrosion resistance with time are good. Become. Particularly when the metal plate is an aluminum plated plate, an aluminum-zinc alloy plated steel plate, an aluminum plate, etc., it is not preferable that the pH of the coating composition is high or low because the components aluminum and zinc are amphoteric metals.

The amount of the resin dry film is to ensure the lubricity in roll molding or press molding, to prevent the sounding phenomenon due to the excessive adhesion of the films when the coiled coated surface-treated metal plate is unwound, and the chemical resistance. Considering such things as one side
It is preferably 0.5 to 5 g / m ² . Further, in the case of performing spot weldability or considering the manufacturing cost, 1 to 3 g / m ² is desirable on one side.

[0021]

EXAMPLES Example 1 Examples of the present invention will be described below. (Production of resin) 700 g of deionized water and an emulsifier (Adeka Riaso SE-10N: manufactured by Asahi Denka Co., Ltd.) were placed in a 3 l flask equipped with a stirrer, a reflux condenser, a dropping funnel, and a thermometer.
Add g and keep the temperature at 80 ° C. An aqueous solution of a polymerization initiator consisting of 3 g of ammonium persulfate and 290 g of deionized water was added dropwise to this over 150 minutes. At the same time, 500 g of deionized water and an emulsifier (Adecaria Soap SE-10N:
Asahi Denka Kogyo Co., Ltd.) 9 g, methacrylic acid 12 g, styrene 300 g, methyl methacrylate 270 g, and 2-ethylhexyl acrylate 408 g were added dropwise over 140 minutes. Here, 10 g of an emulsifier is used in 990 g of the α, β-ethylenically unsaturated monomer, and the emulsifier corresponds to 1 wt% per resin solid content.
After all the dropping was completed, aging was carried out at the same temperature for 120 minutes. Thus, an acrylic emulsion resin having a nonvolatile content of 40% and a resin acid value of 8 was obtained. (Production of coating composition) 0.80 g of ammonium chromate (0.3 g of hexavalent chromium), 2 g of microcrystalline wax (Nopco 1245M-SN: manufactured by San Nopco), hydrophilicity to 100 g of the above acrylic emulsion resin solid content. Add 15 g of butyl cellosolve as a solvent,
= 6.5 and the coating composition was obtained. (Metal plate) As a metal plate, the composition of the plating layer is Al = 55.
An aluminum-zinc alloy plated metal plate having a wt%, Zn = 43.4 wt%, Si = 1.6 wt%, a coating weight of 85 g / m ² on one side, a thickness of 0.8 mm and a width of 914 mm was used. This metal plate is degreased by washing with trichloroethane. (Film forming step) The coating composition was roll-coated on a metal plate so that the dry coating amount was 2 g / m ² . Immediately after the roll coating, a coated surface-treated metal plate was obtained by drying with hot air at 150 ° C. for 6 seconds to form a film. The reached plate temperature of the coated surface-treated metal plate at this time was 85 ° C. This was cooled and used as a test material thereafter.

In Examples 1, 2 and 3, and Comparative Examples 1 and 2, the resins and coating compositions used were those shown in Table 1. The metal plate used in Example 2 and Comparative Examples 1 and 2 was the same as that in Example 1, and in Example 3 and Comparative Examples 3 to 5, the plating adhesion amount was 80 g / m ² on one side. Then, an aluminum-zinc alloy plated metal plate whose thickness was changed to 0.35 mm was used.

[0023]

[Table 1]

Comparative Example 3 The same aluminum-zinc alloy-plated metal plate as in Example 3 was subjected to a degreasing treatment and was used as a test material without a resin film. This is a so-called untreated metal plate. Comparative Example 4 On the surface of the metal plate obtained in Comparative Example 3, 20 g / l of chromic acid chromate treatment liquid (ZM3360H manufactured by Nippon Parker Rising Co., Ltd.) was spray-coated, and the coating amount was adjusted by a roll squeeze to dry the sample. It was made of wood. When the amount of chromium deposited on this test material was measured by a fluorescent X-ray device, the amount of Cr was 20 mg.
Was / m ² . Comparative Example 5 The surface of the metal plate obtained in Comparative Example 4 was coated with a mineral oil lubricant, Rustylo DW924HF (produced by Castrol Co., Ltd.) in an amount of 10 ml /
The test material was sprayed with m ² and dried.

For the test materials obtained in Examples 1 to 3 and Comparative Examples 1 to 5, (a) roll formability, (b) chemical resistance,
(c) Corrosion resistance, (d) Blocking property, (e) Post-paintability, (f)
Performance comparison tests of spot weldability were performed.

Next, a test method for each performance test will be described. (a) Roll Formability Test In this test, each test material was passed through a forming roll at a forming speed of 20 m / min while unwinding a length of 1700 m, and the appearance change degree of the forming site was observed and evaluated. The molded cross-sectional shape and evaluation site are shown in FIG. Molding was carried out while thoroughly cleaning all stages of the molding rolls and inspecting for adhesion of foreign matter for each type of test material. Table 2 shows the evaluation criteria of roll formability.

[0027]

[Table 2]

(B) Chemical resistance performance test This was carried out according to the following test method by preparing a test piece from each test material. (1) Immersion test 1. After sealing the four end faces of the test piece (50 mm × 200 mm) with polyester tape, 1% -NaOH aqueous solution (liquid temperature 20
C)). After 1 hour and 5 hours, the color was raised, and the hue change (blackness degree = ΔL value) was measured with a color meter (SM-5 manufactured by Suga Test Instruments Co., Ltd.) for evaluation. 2. A test piece similar to (1) -1. Was immersed in a 1% NaClO ₃ aqueous solution (solution temperature 20 ° C.), and after 240 hours, pulled up and evaluated. (2) Contact test A slate piece (same size as the test piece) is sandwiched between two test pieces (70 mm x 150 mm) of each test material, and four sides are fastened with strong clips. This was immersed in water at 20 ° C. for 24 hours to evaluate the degree of blackening.

(C) Corrosion resistance test This test was carried out by a salt spray tester based on JIS Z2371. (b) Chemical resistance performance test ((1) Immersion test and
The evaluation criteria for (2) contact test) and (c) corrosion resistance test are shown in Table 3.

[0030]

[Table 3]

(D) Blocking property test The blocking property is the presence or absence of a sounding phenomenon due to over-adhesion (blocking) between resin coatings when unwinding a coil-shaped test material, and 914 mm after unwinding. 1829
Stack 1000 pieces cut into mm sheet materials,
It was determined by judging the degree of close contact between the sheet materials after 3 days.

(E) Post-paintability test This is a test material in which a baking type 1-coat melamine alkyd resin paint (Olga Select 200, manufactured by Nippon Paint Co., Ltd.) is applied to a dry coating film thickness of 30 μm, and the temperature is 110 ° C. In 2
It was baked in a hot air drying oven for 0 minutes to obtain a test material. A cutter knife is used to reach the base material at 1 mm intervals on this test material 10
Zero grids were made, and cellophane adhesive tape (LP18 Nichiban Co., Ltd.) was pressure-bonded onto the surface of the grid. After that, the film was rapidly peeled off and evaluated by counting the number of the remaining coating films.

(F) Spot Weldability Test In this test, suitable welding conditions for the coated surface-treated aluminum-zinc alloy-plated metal sheet were found in advance, and the continuous welding spot number under the conditions was evaluated. Table 4 shows the test results of the above performance comparison tests.

[0034]

[Table 4]

[0035]

INDUSTRIAL APPLICABILITY The coated surface-treated metal sheet of the present invention is blended with a resin coating to form a monomer and an emulsifier of an acrylic emulsion resin, and a coating composition to form a coating composition.
By finding the above conditions regarding the type and compounding ratio of the valent chromium, the wax solids, the hydrophilic solvent, the resin acid value of the acrylic emulsion resin in the compounding, the PH of the coating composition, etc., All have excellent performance in terms of a) roll formability, (b) chemical resistance, (c) corrosion resistance, (d) blocking property, (e) post-coating property, and (f) spot weldability. ing.

[Brief description of drawings]

FIG. 1 is a view showing a molding cross-sectional shape and an evaluation site in roll molding of a metal plate.

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Claims (2)

[Claims] 1. A coated surface-treated metal sheet having a resin coating on the surface of a metal sheet, wherein the resin coating contains an anionic and / or nonionic reactive emulsifier capable of radical polymerization in a resin solid content of 0.5. Resin acid value of 0 ~ 9
To obtain an acrylic emulsion resin obtained by emulsion-polymerizing an α, β-ethylenically unsaturated monomer, and 0.1 to 2 parts by weight of hexavalent chromium with respect to 100 parts by weight of the resin solid content, Film formation using a coating composition prepared by mixing 0.5 to 5 parts by weight of a wax solid component and 5 to 50 parts by weight of a hydrophilic solvent and adjusting the liquidity to PH = 6 to 8. A coated surface-treated metal plate characterized by being 2. The dry film weight of the resin film is 0.5 to 5 g.
The coated surface-treated metal sheet according to claim 1, wherein the coated surface-treated metal sheet is / m ² .