WO2017159224A1

WO2017159224A1 - Water-based-resin-coated metal plate

Info

Publication number: WO2017159224A1
Application number: PCT/JP2017/006159
Authority: WO
Inventors: 徹江口; 哲也山本; 大輝酒井
Original assignee: 株式会社神戸製鋼所
Priority date: 2016-03-17
Filing date: 2017-02-20
Publication date: 2017-09-21
Also published as: TW201738328A; JP2017165026A

Abstract

The present invention relates to a water-based-resin-coated metal plate having a first layer containing a water-based resin and colloidal silica on at least one side of a metal plate and having, on the first layer, a second layer containing a water-based resin and carbon black, the water-based-resin-coated metal plate being characterized in that the first layer has a film thickness of 0.1-0.4 µm and contains 70-95 mass% of the resin component and 5-30 mass% of the colloidal silica with respect to 100 mass% in total of the resin component and the colloidal silica, the second layer has a film thickness of 0.3-0.7 µm, may contain colloidal silica, and contains 50-85 mass% of the resin component, 0-20 mass% of the colloidal silica, and 15-30 mass% of the carbon black with respect to 100 mass% in total of the resin component, the colloidal silica, and the carbon black, and the total film thickness of the first layer and the second layer is 0.4-0.8 µm.

Description

Water-based resin-coated metal plate

The present invention relates to a water-based resin-coated metal plate excellent in all of heat dissipation, conductivity, and corrosion resistance, in which a thin-film carbon black-containing layer is laminated on a metal plate having a thin clear coating film (first layer). Is.

The water-based resin-coated metal plate of the present invention can be used for casings and interior / exterior parts of household electric appliances, outer plate materials such as metal furniture, and building materials.

Conventionally, many galvanized steel sheets have been used for interior parts and exterior parts of electrical appliances, and steel sheets on which a coating film with corrosion resistance and fingerprint resistance is formed are often used. In addition, as electric appliances are miniaturized and improved in performance, it is necessary to install a fan, a heat sink, or the like as a heat dissipation measure, which increases the cost. In view of this, steel plates having heat dissipation properties that can reduce costs by omitting fans and heat sinks have been developed (Patent Document 1, Patent Document 2, etc.).

In order to improve the heat dissipation of the steel sheet, it is effective to form a thick film on the steel sheet to which a material having a high emissivity such as carbon black is added. However, when the film is thickened, the conductivity required to ensure spot weldability and electromagnetic wave shielding properties is reduced, and the level of conductivity required for steel sheets for electrical appliances cannot be reached. It becomes indispensable and the cost becomes high.

On the other hand, when the film is thinned to ensure conductivity and the amount of carbon black is increased to ensure heat dissipation, the corrosion resistance may be greatly reduced. *

After all, it was difficult to develop a steel sheet that is inexpensive and satisfies all of heat dissipation, conductivity, and corrosion resistance.

In light of the above-described present situation, the present invention has been aimed at providing a resin-coated metal plate that is inexpensive and satisfies all of heat dissipation, conductivity, and corrosion resistance.

JP 2004-74145 A JP 2014-111322 A

One aspect of the present invention is an aqueous resin having a first layer containing an aqueous resin and colloidal silica on at least one surface of a metal plate, and an aqueous resin and a second layer containing carbon black on the first layer. A coated metal plate, wherein the first layer has a film thickness of 0.1 to 0.4 μm, and the resin component is 70 to 95% by mass in a total of 100% by mass of the resin component and colloidal silica. The second layer has a film thickness of 0.3 to 0.7 μm and may contain colloidal silica. The total amount of the resin component, colloidal silica and carbon black is 100% by mass. Among them, the resin component is 50 to 85% by mass, the colloidal silica is 0 to 20% by mass, the carbon black is 15 to 30% by mass, and the total film thickness of the first layer and the second layer is 0.4 to 0. .8 μm An aqueous resin coated metal plate, wherein the door.

The inventors of the present invention have studied the cause of the corrosion resistance of resin-coated metal plates that are greatly reduced when the film is thinned to ensure conductivity and the amount of carbon black is increased to ensure heat dissipation. As a result, it was found that the deterioration of the corrosion resistance was not caused mainly by the deterioration of the film due to the addition of carbon black, but because it was a corrosion site because carbon black had conductivity. And, by providing an extremely thin film (first layer) that does not contain carbon black between the metal plate and the carbon black-containing film, the corrosion resistance was successfully improved, and the present invention was completed. . According to the present invention, it is possible to provide an inexpensive resin-coated metal plate that has a thin carbon black-containing film (second layer) that exhibits electrical conductivity and that is excellent in corrosion resistance and heat dissipation.

The aqueous resin-coated metal plate of the present invention has a first layer containing an aqueous resin and colloidal silica on at least one surface of the metal plate, and a second layer containing an aqueous resin and carbon black is formed on the first layer. A water-based resin-coated metal plate having a film thickness of 0.1 to 0.4 μm, and the resin component is 70 to 95% by mass in a total of 100% by mass of the resin component and colloidal silica. The colloidal silica is 5 to 30% by mass, and the second layer has a film thickness of 0.3 to 0.7 μm and may contain colloidal silica. The total of the resin component, colloidal silica and carbon black In 100% by mass, the resin component is 50 to 85% by mass, colloidal silica is 0 to 20% by mass, carbon black is 15 to 30% by mass, and the total film thickness of the first layer and the second layer is 0.00. 4-0. It is 8 μm.

With the above configuration, it was possible to provide a water-based resin-coated metal plate that is inexpensive and satisfies all of heat dissipation, conductivity, and corrosion resistance.

[Metal plate]
It does not specifically limit as a metal plate used by this embodiment, For example, a cold-rolled steel plate, a hot-rolled steel plate, an electrogalvanized steel plate (EG), a hot-dip galvanized steel plate (GI), an alloyed hot-dip galvanized steel plate (GA), 5% Al—Zn plated steel sheets, 55% Al—Zn plated steel sheets, various plated steel sheets such as aluminum plates (Al), steel sheets such as stainless steel sheets, known metal plates, and the like can all be applied.

The metal plate may be subjected to surface treatment such as chromate treatment or phosphate treatment for the purpose of improving the corrosion resistance, improving the adhesion of the coating film, etc. A chromated metal plate may be used, and any embodiment is included within the scope of the present invention.

[First layer]
The first layer essentially contains an aqueous resin and colloidal silica. As the water-based resin, polyolefin-based resins, polyurethane-based resins, and polyester-based resins are preferable, and among them, polyolefin-based resins are preferable. In the present embodiment, the aqueous resin refers to a resin that is an aqueous dispersion or a water-soluble resin.

As the polyolefin resin, an ethylene-unsaturated carboxylic acid copolymer is preferable. As the ethylene-unsaturated carboxylic acid copolymer, those described in JP-A-2005-246953 and JP-A-2006-43913 can be used.

Examples of the unsaturated carboxylic acid include (meth) acrylic acid, crotonic acid, isocrotonic acid, maleic acid, fumaric acid, itaconic acid, and the like. A copolymer can be obtained by polymerization using a legal method or the like.

The copolymerization ratio of unsaturated carboxylic acid to ethylene is preferably 10 to 40% by mass of unsaturated carboxylic acid when the total amount of monomers is 100% by mass. If the unsaturated carboxylic acid content is less than 10% by mass, the carboxyl group that is the starting point of intermolecular association by ion clusters is small, so that the film strength effect is not exhibited and the emulsion composition is inferior in emulsion stability. A more preferable lower limit of the unsaturated carboxylic acid is 15% by mass. On the other hand, when unsaturated carboxylic acid exceeds 40 mass%, the corrosion resistance and water resistance of a 1st layer may be inferior. A more preferred upper limit is 25% by mass.

Since the ethylene-unsaturated carboxylic acid copolymer has a carboxyl group, it can be emulsified (aqueous dispersion) by neutralization with an organic base or metal ion. In the present embodiment, examples of the organic base include primary, secondary, and tertiary amines (preferably triethylamine). An amine having a low boiling point (preferably an amine having a boiling point of 100 ° C. or lower under atmospheric pressure; for example, triethylamine) does not significantly reduce the corrosion resistance of the film. Monovalent metal ions are also preferably used in combination with amines. The amine is preferably used in an amount of 0.2 to 0.8 mol (20 to 80 mol%) with respect to 1 mol of the carboxyl group in the ethylene unsaturated carboxylic acid copolymer. It can be seen that the amount of monovalent metal ions affects the water vapor permeability, and if the amount of monovalent metal compound used increases, the affinity between the resin and water increases, and the water vapor permeability increases. The amount is preferably 0.02 to 0.2 mol (2 to 20 mol%) based on 1 mol of the carboxyl group in the ethylene-unsaturated carboxylic acid copolymer. In addition, since excessive alkali content causes deterioration of corrosion resistance, the total amount of amines and metal ions used is 0.3 to 1 per mol of the carboxyl group in the ethylene-unsaturated carboxylic acid copolymer. It is good to set it as the range of 0 mol. The metal compound for imparting monovalent metal ions is preferably NaOH, KOH, LiOH or the like, and NaOH is most preferable because of its best performance.

In emulsification (emulsification), an appropriate amount of a compound having a surfactant function such as tall oil fatty acid may be added. The above-mentioned ethylene-unsaturated carboxylic acid copolymer can be stirred at high speed in a container capable of high temperature (about 150 ° C.) and high pressure (about 5 atm) in the presence of the carboxylic acid polymer described below, if necessary. Emulsify after 1-6 hours. Further, a hydrophilic organic solvent such as a lower alcohol having about 1 to 5 carbon atoms may be partially added to water.

The mass average molecular weight (Mw) of the ethylene-unsaturated carboxylic acid copolymer is preferably 1,000 to 100,000, more preferably 3,000 to 70,000, and still more preferably 5,000 to 30,000 in terms of polystyrene. It is. This Mw can be measured by GPC using polystyrene as a standard.

In the first layer, a carboxylic acid polymer can also be used as a resin component. As the carboxylic acid polymer, any polymer having an unsaturated carboxylic acid as a constituent unit exemplified as one that can be used for the synthesis of the ethylene-unsaturated carboxylic acid copolymer can be used. Among these, acrylic acid and maleic acid are preferable, and maleic acid is more preferable. The carboxylic acid polymer may contain a constituent unit derived from a monomer other than the unsaturated carboxylic acid, but the constituent unit amount derived from the other monomer is 10% by mass or less in the polymer. More preferably, it is 5 mass% or less, and a carboxylic acid polymer composed only of an unsaturated carboxylic acid is more preferable. Preferred examples of the carboxylic acid polymer include polyacrylic acid, polymethacrylic acid, acrylic acid-maleic acid copolymer, polymaleic acid and the like. Among these, polymaleic acid is preferred from the viewpoint of resin film adhesion and corrosion resistance. More preferred. Although the exact mechanism by which the corrosion resistance is improved by using polymaleic acid is unknown, the adhesion between the resin film and the metal plate is improved due to the large amount of carboxyl groups. It is done. However, the present invention is not limited to this estimation. The Mw of the carboxylic acid polymer used in the present embodiment is preferably from 500 to 30,000, more preferably from 800 to 10,000, still more preferably from 900 to 3,000, most preferably from 1,000 to 2, in terms of polystyrene. 000. This Mw can be measured by GPC using polystyrene as a standard.

The content ratio of the ethylene-unsaturated carboxylic acid copolymer and the carboxylic acid polymer is 1,000: 1 to 10: 1, preferably 200: 1 to 20: 1 in terms of mass ratio. If the content ratio of the carboxylic acid polymer is too low, the effect of combining the olefin-acid copolymer and the carboxylic acid polymer is not sufficiently exhibited. Conversely, if the content ratio of the carboxylic acid polymer is excessive, There is a possibility that the olefin-acid copolymer and the carboxylic acid polymer may be phase-separated in the first layer-forming coating solution, and a uniform resin film may not be formed.

[Colloidal silica]
When colloidal silica is present in the first layer, it dissolves and dissolves at the film defects in a corrosive environment, and suppresses dissolution / elution of the metal plate by pH buffering and passive film formation, thus improving corrosion resistance. . However, the state of dispersion in the film changes depending on the surface area (particle diameter) of the colloidal silica, which greatly affects mechanical properties such as hardness and brittleness of the film. In order to form a dense film and improve the toughness of the film, it is desirable to uniformly disperse colloidal silica having a small particle diameter in the film. In this respect, colloidal silica has an average particle diameter of 4 to It is preferably 20 nm. When it exceeds 20 nm, the dispersibility tends to decrease. For this reason, there is a possibility that a dense film cannot be formed, and the toughness of the film is insufficient, or the corrosion resistance improving effect is lowered. On the other hand, if the thickness is less than 4 nm, the storage stability of the first layer-forming coating solution may be deteriorated and gelation may occur. The average particle size of colloidal silica is more preferably 4 to 6 nm. The average particle diameter of silica can be measured by the Sears method when the average particle diameter is about 1 to 10 nm and by the BET method when it is about 10 to 100 nm.

Colloidal silica is commercially available. For example, if it has an average particle size of 4 to 6 nm, “Snowtex (registered trademark) XS” manufactured by Nissan Chemical Industries, Ltd. "Snowtex (registered trademark) 40", "Snowtex (registered trademark) N", "Snowtex (registered trademark) SS", "Snowtex (registered trademark) O" manufactured by Nissan Chemical Industries, Ltd., and ADEKA “Adelite (registered trademark) AT-30”, “Adelite (registered trademark) AT-30A”, and the like manufactured by the same company can be used. Since the first layer forming coating solution is aqueous, it is preferable to select the type of colloidal silica according to the pH of the coating solution in order to disperse the colloidal silica well.

The resin component (ethylene-unsaturated carboxylic acid copolymer and carboxylic acid polymer) and colloidal silica in the first layer have a resin component of 70 to 95 when the total of the resin component and colloidal silica is 100% by mass. % By mass and 5-30% by mass of colloidal silica. Outside this range, corrosion resistance may be insufficient.

[Silane coupling agent]
The first layer forming coating solution may contain a silane coupling agent. When a silane coupling agent is used, the adhesion between the metal and the first layer is improved, and the corrosion resistance is also improved accordingly. Moreover, there exists an effect which improves the bond strength of a resin component and colloidal silica, and the toughness of a film | membrane improves. Among them, the glycidoxy-based silane coupling agent has high reactivity and has a large effect of improving corrosion resistance. Glycidyl group-containing silane coupling agents include γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxymethyldimethoxysilane, β- (3,4-epoxycyclohexyl) Examples include ethyltrimethoxysilane.

The amount of the silane coupling agent in the first layer forming coating liquid is preferably 0.1 to 10 parts by mass with respect to 100 parts by mass in total of the resin component and colloidal silica. When the amount is less than 0.1 parts by mass, the adhesion between the metal plate and the resin film and the bonding force between the resin component and colloidal silica are insufficient, and the toughness and corrosion resistance of the film may be insufficient. However, even if it exceeds 10 parts by mass, the effect of improving the adhesion between the metal plate and the resin film is saturated, and the coatability may be reduced because the functional groups in the resin are reduced. Moreover, silane coupling agents cause a hydrolysis condensation reaction, the stability of the coating liquid is lowered, and there is a possibility of causing gelation and precipitation of colloidal silica. The amount of the silane coupling agent is more preferably 3 to 9 parts by mass, and further preferably 5 to 7 parts by mass.

[Carbodiimide group-containing compound]
The first layer forming coating solution of the present embodiment may further contain a carbodiimide group-containing compound. The carbodiimide group reacts with the carboxyl group in the ethylene-unsaturated carboxylic acid copolymer and the carboxylic acid polymer. Therefore, by using a carbodiimide group-containing compound, the amount of carboxyl groups in the first layer can be reduced and water resistance can be improved. In the present embodiment, one or more carbodiimide group-containing compounds can be used.

Since the first layer forming coating solution is aqueous, an aqueous carbodiimide group-containing compound is preferable. A compound containing a plurality of carbodiimide groups in one molecule is preferable. When a plurality of carbodiimide groups are contained in one molecule, corrosion resistance and the like can be further improved by a crosslinking reaction with a carboxyl group in the resin component.

Examples of commercially available polycarbodiimide compounds are N, N-dicyclohexylcarbodiimide, N, N-diisopropylcarbodiimide and the like, and polycarbodiimides (polymers having a plurality of carbodiimide groups in one molecule) manufactured by Nisshinbo. Mention may be made of the “Carbolite®” series. “Carbolite (registered trademark)” grades include water-soluble “SV-02”, “V-02”, “V-02-L2”, “V-04” and emulsion type “E-01”. , “E-02” and the like are preferable.

The amount of the carbodiimide group-containing compound is set according to the amount of carboxyl groups in the resin component. For example, when the total of the resin components is 100 parts by mass, the amount of the carbodiimide group-containing compound is preferably 0.3 parts by mass or more, more preferably 0.5 parts by mass or more, further preferably 100 parts by mass. It is 8 parts by mass or more. On the other hand, when the amount of the carbodiimide group-containing compound is excessive, the effect of the combination of the ethylene-unsaturated carboxylic acid copolymer and the carboxylic acid polymer is lowered. Moreover, when an aqueous carbodiimide group-containing compound is excessively used in the aqueous first layer forming coating solution, it may adversely affect water resistance and corrosion resistance. From such a viewpoint, the amount of the carbodiimide group-containing compound is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, and further preferably 16 parts by mass or less with respect to 100 parts by mass.

The first layer forming coating solution preferably has a solid content of about 15 to 25% by mass. The thickness of the first layer is preferably 0.1 to 0.4 μm, more preferably 0.2 to 0.3 μm. If it is thinner than 0.1 μm, the corrosion resistance is insufficient. Further, even if the thickness exceeds 0.4 μm, the corrosion resistance improving effect is saturated. In the first layer forming coating solution, a wax, a crosslinking agent, a diluent, an anti-skinning agent, a surfactant, an emulsifier, a dispersant, a leveling agent, an antifoaming agent, as long as the effect of the present invention is not impaired Penetration agents, film-forming aids, dyes, pigments, thickeners, lubricants, and the like can also be included.

[Second layer]
The second layer includes a resin component and carbon black. Among these, carbon black is added for heat dissipation. The carbon black is not particularly limited. For example, it is recommended to use SA black DY-6 manufactured by Mikuni Dye Co., Ltd. The carbon black is preferably 15 to 30% by mass when the resin component constituting the second layer and the carbon black (including colloidal silica described later also includes colloidal silica) are 100% by mass. More preferably, it is 20 to 30% by mass, and further preferably 25 to 30% by mass. If the amount of carbon black is small, sufficient heat dissipation cannot be exhibited. If carbon black is added in an amount exceeding 30% by mass, the corrosion resistance tends to decrease, which is not preferable. The heat dissipation in this embodiment is a wavelength of 4.5 to 15 when a resin-coated metal plate is heated to 100 ° C. using a Fourier transform infrared spectrophotometer (manufactured by JEOL Ltd., JIR-5500). The spectral radiant intensity of a 4 μm sample and a black body was measured, and the value obtained by dividing the spectral radiant intensity of the sample by the spectral radiant intensity of the black body was used as an index. The emissivity is preferably 0.3 or more. A more detailed method for measuring the emissivity will be described later.

As the resin forming the second layer, any one or more of polyolefin resin, polyurethane resin, and polyester resin is preferable. As the polyolefin resin, polyolefin resins exemplified as suitable for the first layer can be used. As the polyurethane resin, for example, Adekabon titer (registered trademark; water-based polyurethane) series manufactured by ADEKA is used. Moreover, as a polyester-type resin, the Toyobo Co., Ltd. baironal (trademark; water-dispersed polyester) series can be used, for example.

Colloidal silica may not be added to the second layer. However, in order to improve the hardness of the film and improve the corrosion resistance, it is preferable to contain colloidal silica in the range of 20% by mass or less. . When silica is used in excess of 20% by mass, the corrosion resistance may be reduced. Therefore, when the total amount of the resin component, colloidal silica, and carbon black is 100% by mass, the resin component is 50 to 85% by mass, the colloidal silica is 0 to 20% by mass, and the carbon black is 15 to 30% by mass. It is preferable.

The second layer forming coating solution preferably has a solid content of about 15 to 25% by mass. You may mix | blend the various components mix | blended with the coating liquid for 1st layer formation in the coating liquid for 2nd layer formation. The thickness of the second layer is preferably 0.3 to 0.7 μm, more preferably 0.4 to 0.7 μm. If it is thinner than 0.3 μm, the heat dissipation is insufficient, but if it exceeds 0.7 μm, the heat dissipation effect is saturated. The total film thickness of the first layer and the second layer is 0.4 to 0.8 μm. If it exceeds 0.8 μm, the conductivity is insufficient.

Next, the infrared integrated emissivity will be described.

In other words, infrared integrated emissivity means the ease of releasing (easy absorption) of infrared (thermal energy). Therefore, the higher the infrared integrated emissivity, the greater the amount of heat energy released (absorbed). For example, when 100% of the thermal energy given to an object (in this embodiment, a resin-coated metal plate) is emitted, the infrared integrated emissivity is 1.

In this embodiment, the infrared integrated emissivity when heated to 100 ° C. is determined. This is because the coated laminate metal plate in the present embodiment is applied to electrical equipment applications (although it differs depending on the members, etc., the normal atmospheric temperature is approximately 50 to 70 ° C., and maximum is about 100 ° C.). In consideration of this, the heating temperature is set to 100 ° C. in order to match the temperature of the practical level.

The measuring method of the infrared integrated emissivity in this embodiment is as follows.
Equipment: “JIR-5500 type Fourier transform infrared spectrophotometer” manufactured by JEOL Ltd. and radiation measurement unit “IRR-200”
Measurement wavelength range: 4.5 to 15.4 μm
Measurement temperature: set the sample heating temperature to 100 ° C. Integration count: 200 times Resolution: 16 cm ⁻¹

Using the above apparatus, the spectral radiant intensity (measured value) of the sample in the infrared wavelength region (wavelength: 4.5 to 15.4 μm) was measured. In addition, since the measured value of the above sample is measured as a numerical value obtained by adding / adding the background radiation intensity and the instrument function, an emissivity measurement program [JEOL emissivity measurement program manufactured by JEOL Ltd.] ] To calculate the integral emissivity.

Details of the calculation method are as follows.

Where
ε (λ): Spectral emissivity of sample at wavelength λ (%)
E (T): integrated emissivity (%) of sample at temperature T (° C.)
M (λ, T): Spectral radiant intensity of the sample at wavelength λ and temperature T (° C.) (actual measurement value)
A (λ): Instrument function KFB (ν): Spectral radiant intensity KTB (λ, TTB) of fixed background (background that does not vary with the sample) at wavelength ν: Trap black body at wavelength λ, temperature TTB (° C.) Spectral radiant intensity KB (λ, T): Spectral radiant intensity of black body at wavelength λ and temperature T (° C) (calculated value from blank theoretical formula)
λ1, λ2: Means the range of wavelengths to be integrated.

Here, A (λ: instrument function) and KFB (ν: spectral radiant intensity of fixed background) are measured values of spectral radiant intensity of two blackbody furnaces (80 ° C., 160 ° C.), and Based on the spectral radiant intensity of the black body in the temperature range (calculated value from the theoretical formula of the blank), it is calculated by the following formula.

Where
M160 ° C. (λ, 160 ° C.): Spectral radiant intensity of 160 ° C. blackbody furnace at wavelength λ (actual measured value)
M80 ° C. (λ, 80 ° C.): Spectral radiation intensity of 80 ° C. blackbody furnace at wavelength λ (actual measured value)
K 160 ° C. (λ, 160 ° C.): Spectral radiant intensity of a black body furnace at a wavelength λ of 160 ° C. (calculated from the theoretical formula of the blank)
K80 ° C. (λ, 80 ° C.): Spectral radiant intensity of a black body furnace at a wavelength λ of 80 ° C. (calculated from the theoretical formula of the blank)
Means each.

In calculating the integral emissivity E (T = 100 ° C.), KTB (λ, TTB) is taken into account because a water-cooled trap black body is arranged around the sample in measurement. is there. By installing the trap black body, variable background radiation (meaning background radiation that varies depending on the sample. Since the radiation from the periphery of the sample is reflected on the sample surface, the measured value of the spectral radiant intensity of the sample is Spectral radiation intensity (which appears as a numerical value with background radiation added) can be controlled low. The trap black body uses a pseudo black body with an emissivity of 0.96, and the KTB [(λ, TTB): spectral radiant intensity of the trap black body at a wavelength λ and a temperature TTB (° C.)] is: Calculate as follows.
KTB (λ, TTB) = 0.96 × KB (λ, TTB)
In the formula, KB (λ, TTB) means the spectral radiant intensity of a black body at a wavelength λ and a temperature TTB (° C.).

[Production method]
The water-based resin-coated metal plate of this embodiment can be manufactured by the following method. First, the first layer forming coating solution prepared by mixing the above components at a predetermined ratio and stirring for several minutes with a stirrer is applied to the surface of the metal plate by a known coating method and dried. Subsequently, the above components are mixed at a predetermined ratio, and stirred for several minutes with a stirrer to apply the second layer forming coating solution to the surface of the metal plate by a known coating method, followed by drying. be able to. The coating method is not particularly limited, but for example, the coating liquid is applied to the surface of a long metal strip that has been cleaned and galvanized using the bar coater method, roll coater method, spray method, curtain flow coater method, etc. Examples of the method include coating and drying through a hot-air drying furnace. The roll coater method is preferable in practical use in consideration of film thickness uniformity, processing cost, coating efficiency, and the like.

This specification discloses various modes of technology as described above, and the main technologies are summarized below.

The first layer preferably contains a polyolefin resin.

The second layer preferably contains at least one of a polyolefin resin, a polyurethane resin, and a polyester resin.

Hereinafter, the present invention will be described in more detail by way of examples. However, the following examples are not intended to limit the present invention, and modifications that do not depart from the spirit of the present invention are included in the present invention. In addition, unless otherwise indicated, a part means a mass part.

Experimental Examples 1 to 33
[Preparation of first layer forming coating solution]
To an autoclave having an emulsification facility equipped with a stirrer, a thermometer, and a temperature controller, an ethylene-acrylic acid copolymer ("Primacol (registered trademark) 5990I" manufactured by Dow Chemical Co., Ltd., a structural unit derived from acrylic acid: 20% by mass , Mass average molecular weight (Mw): 20,000, melt index: 1300, acid value: 150, 200.0 parts, polymaleic acid aqueous solution (“NOPOL (registered trademark) PMA-50W manufactured by NOF Corporation), Mw: about 1100 (Polystyrene equivalent), 50 mass% product) 8.0 parts, 35.5 parts triethylamine (0.63 equivalents relative to the carboxyl group of the ethylene-acrylic acid copolymer), 6.9 parts 48% NaOH aqueous solution (ethylene -0.15 equivalent to the carboxyl group of the acrylic acid copolymer), tall oil fatty acid ("Hartol" manufactured by Harima Kasei Co., Ltd.) A3 ") 3.5 parts, and sealed with ion exchange water 792.6 parts, after 3 hours stirred at high speed 0.99 ° C. and 5 atm, and cooled to 30 ° C..

Next, 10.4 parts of a glycidoxy group-containing silane coupling agent (“TSL8350” manufactured by Momentive Performance Materials, γ-glycidoxypropyltrimethoxysilane), a carbodiimide group-containing compound (“Carbodilite (registered trademark)” manufactured by Nisshinbo Co., Ltd. SV-02 ", polycarbodiimide, Mw: 2,700, solid content 40% by mass) 31.2 parts and ion-exchanged water 72.8 parts were added and stirred for 10 minutes to obtain an ethylene-acrylic acid copolymer. An emulsion emulsified and mixed with each component was obtained (solid content 20.3% by mass, measured according to JIS K6833; hereinafter referred to as aqueous polyolefin resin solution).

Table 1 shows the amount of colloidal silica ("Snowtex (registered trademark) XS" manufactured by Nissan Chemical Industries Ltd., solid content 20 mass%, average particle size (catalog value): 4 to 6 nm) in the aqueous polyolefin resin solution. As described above, the mixture was diluted with ion-exchanged water and stirred to obtain a coating solution for forming a first layer. Sample 33 of Experimental Example 33 is an example in which carbon black (“SA Black DY-6” manufactured by Mikuni Dye Co., Ltd., solid content: 30.5 mass%) was added to the first layer.

[Coating]
For forming the first layer with a bar coater on the surface of electrogalvanized steel sheet (plate thickness 0.8mm; plating coverage 20g / m2 on each side) so that the film thickness after drying is 0.03-0.43μm The coating solution was applied and dried by heating at a plate temperature of 90 to 100 ° C. (furnace temperature 220 ° C. × 12 seconds) to form a first layer on the steel plate.

[Second layer forming coating solution and coating]
The amount of colloidal silica and carbon black shown in Table 1 was added to the aqueous polyolefin resin solution, diluted with ion-exchanged water, and stirred well to obtain a coating solution for forming a second layer. On the first layer of the steel sheet on which the first layer has been formed, a coating solution for forming the second layer with a bar coater so that the thickness of the second layer after drying is 0.28 to 0.9 μm. Was applied and dried at a plate temperature of 90 to 100 ° C. (furnace temperature 220 ° C. × 12 seconds) to form a second layer on the steel plate. In Experimental Example 15, a polyester resin (“Vironal (registered trademark) MD-1200, manufactured by Toyobo Co., Ltd., solid content: 34 mass% (water dispersion type), Tg 67 ° C.)” was used as the second layer resin. Is an example using a polyurethane resin (“ADEKA BONTITER (registered trademark) HUX-522” manufactured by ADEKA, solid content of 30% by mass).

Experimental Example 34
Polyester resin (“Vironal (registered trademark) MD-1200, manufactured by Toyobo Co., Ltd.), solid content 34% by mass (water dispersion type, Tg 67 ° C.) 80% by mass (solid content), and the colloidal silica 20% by mass (solid content) ) After mixing, diluting with ion-exchanged water and stirring, apply to the steel plate with a bar coater so that the film thickness after drying is 0.27 μm, plate temperature 90-100 ° C. (furnace temperature 220 ° C. × 12 seconds) The first layer was formed on the steel plate.

Using the aqueous polyolefin resin solution obtained above, blended so as to be 70% by mass of polyolefin resin, 5% by mass of colloidal silica, and 25% by mass of carbon black in terms of solid content, and diluted with ion-exchanged water and stirred. And the coating liquid for 2nd layer formation was obtained. On the first layer of the steel sheet on which the first layer is formed, a coating solution for forming a second layer is applied with a bar coater so that the thickness of the second layer after drying is 0.48 μm. Heat drying was performed at a temperature of 90 to 100 ° C. (furnace temperature 220 ° C. × 12 seconds) to form a second layer on the steel plate.

Experimental Example 35
Polyurethane resin (“ADEKA BONTITER (registered trademark) HUX-522” manufactured by ADEKA Co., Ltd., solid content: 30% by mass) and the above colloidal silica in 80% by mass of polyurethane resin in terms of solid content. It mix | blended so that it might become 20 mass% of colloidal silica, diluted with ion-exchange water, and stirred, and the coating liquid for 1st layer formation was obtained. The first layer forming coating solution is applied to the steel plate with a bar coater so that the film thickness after drying is 0.27 μm, and is heated and dried at a plate temperature of 90 to 100 ° C. (furnace temperature 220 ° C. × 12 seconds). A first layer was formed on the steel plate.

Except for applying the second layer forming coating solution with a bar coater on the first layer of the steel sheet on which the first layer is formed so that the thickness of the second layer after drying is 0.43 μm. In the same manner as in Experimental Example 34, a second layer was formed on the steel plate.

The corrosion resistance, conductivity, and emissivity of each of the resin-coated metal plates (samples 1 to 35) were evaluated according to the following evaluation criteria.

[Corrosion resistance]
According to JIS Z2371, a 5% salt spray test was performed in an atmosphere of 35 ° C., and the surface white rust generation rate was evaluated.
When the first layer was a polyolefin resin, the case where the white rust occurrence rate exceeded 10% was rated as x, and the case where it was 10% or less was marked as ◯.
When the first layer was a polyester resin or a polyurethane resin, the case where the white rust occurrence rate exceeded 20% was evaluated as x, and the case where it was 20% or less was evaluated as ◯.

[Emissivity]
As described above, using a Fourier transform infrared spectrophotometer (JIR-5500, manufactured by JEOL Ltd.), when the resin-coated metal plate is heated to 100 ° C., the sample having a wavelength of 4.5 to 15.4 μm and black The spectral radiant intensity of the body was measured, and the value obtained by dividing the spectral radiant intensity of the sample by the spectral radiant intensity of the black body was used as an index. An emissivity of 0.3 or more was evaluated as ◯, and an emissivity of less than 0.3 was evaluated as x.

[Conductivity]
Using a tester, the electrical resistance value was measured by sliding the terminal on the surface of the sample.

This application is based on Japanese Patent Application No. 2016-054212 filed on Mar. 17, 2016, the contents of which are included in the present application.

In order to express the present invention, the present invention has been described appropriately and sufficiently through the embodiments with reference to specific examples and the like. However, those skilled in the art can easily change and / or improve the above-described embodiments. It should be recognized that this is possible. Therefore, unless the modifications or improvements implemented by those skilled in the art are at a level that departs from the scope of the claims recited in the claims, the modifications or improvements are not limited to the scope of the claims. To be construed as inclusive.

According to the present invention, it is possible to provide a water-based resin-coated metal plate that is inexpensive and satisfies all of heat dissipation, conductivity, and corrosion resistance. The water-based resin-coated metal plate of the present invention can be used for casings and interior / exterior parts of household electrical appliances, outer plate materials such as metal furniture, and building materials.

Claims

A water-based resin-coated metal plate having a first layer containing a water-based resin and colloidal silica on at least one surface of the metal plate, and having a second layer containing a water-based resin and carbon black on the first layer,
The first layer has a thickness of 0.1 to 0.4 μm, and the resin component is 70 to 95% by mass and the colloidal silica is 5 to 30% by mass in a total of 100% by mass of the resin component and colloidal silica. Yes,
The second layer has a film thickness of 0.3 to 0.7 μm and may contain colloidal silica, and the resin component is 50 to 85 mass in a total of 100 mass% of the resin component, colloidal silica and carbon black. %, Colloidal silica is 0 to 20% by mass, carbon black is 15 to 30% by mass,
A water-based resin-coated metal sheet, wherein a total film thickness of the first layer and the second layer is 0.4 to 0.8 μm.
The water-based resin-coated metal plate according to claim 1, wherein the first layer contains a polyolefin-based resin.
The said 2nd layer is a water-system resin coating metal plate of Claim 1 or 2 containing at least one of polyolefin resin, polyurethane resin, and polyester resin.