JP4969341B2 - Metal coating material and manufacturing method thereof - Google Patents

Description

  The present invention is a metal coating material in which a film that exhibits water repellency is formed on the surface of a metal, particularly an aluminum material or an aluminum alloy material (hereinafter simply referred to as an aluminum material).

The water-repellent aluminum resin-coated plate has been proposed for various uses. In this specification, an air conditioner is taken as an example to describe the case of the fin material of the heat exchanger.
Recent heat exchangers for air conditioners are required to have improved thermal efficiency and compactness in order to reduce the weight, and a design to make the fin spacing as narrow as possible has been adopted. In the heat exchanger for an air conditioner, moisture in the air adheres to the surface of the aluminum fin as condensed water during the cooling operation. Since the surface of the metal material is generally poor in hydrophilicity, this condensed water exists on the fin surface in a semicircular shape or a bridge shape between the fins. This hinders the flow of air between the fins, increases the airflow resistance, and significantly reduces the heat exchange efficiency. In order to improve the heat efficiency of the heat exchanger, it is necessary to quickly remove condensed water on the fin surface.
As a solution, (1) a highly hydrophilic film is formed on the surface of the aluminum alloy fin, and the condensed water is allowed to flow down as a thin water film. (2) a water-repellent film is formed on the surface of the aluminum alloy fin, and the condensed water is exposed to the surface. It is conceivable to prevent it from adhering to the surface.

As a method for imparting a highly hydrophilic coating, a method of applying a composition containing carboxymethyl cellulose and polyethylene glycol to form a hydrophilic coating (see Patent Document 1) has been proposed.
However, in indoor units, we were satisfied with the hydrophilic coating, but in outdoor units in winter there was a problem that the condensed water became frozen and became frost, which reduced the heating performance. There was a proposal for a coating, but it was still not satisfactory.
In addition, there are silicone-based or fluorine-based water-repellent coatings containing inorganic fillers (see Patent Documents 2 and 3), and electrodeposition paints containing water-repellent coatings containing silica or titania in the shape of tufts. In the techniques of Patent Documents 2 and 3, the particles in the water-repellent coating are likely to fall off, and in the technique of Patent Document 4, there is a problem that there is no sufficient water repellency or the manufacturing method is complicated.
Japanese Patent Laid-Open No. 2000-028291 JP-A-3-244680 Japanese Patent Laid-Open No. 5-222339 JP 2003-238947 A

  Therefore, in view of the problems in the prior art, the present inventors can prevent the particles from falling off, have a high water repellency by a relatively easy method, and in particular by making the shape of the fine particles special. An object of the present invention is to provide a metal coating material that can be water-based and can eliminate condensed water on the fin surface of the heat exchanger.

The present invention has been made to achieve the above object, and comprises the following inventions.
(1) A base film made of an organic resin containing organic or inorganic fine particles (A) is formed on at least one surface of a metal material, and a finish film showing water repellency is formed on the base film, and the fine particles The average particle diameter of (A) is 1.5 times or more larger than the film thickness of the said organic resin base film, The water repellent metal coating material characterized by the above-mentioned.
(2) From an organic resin containing organic or inorganic fine particles (A) and organic or inorganic fine particles (B) having an average particle size of 1/4 or less of the fine particles (A) on at least one surface of the metal material An at least part of the fine particles (B) adheres to the surface of the fine particles (A), and a finish film showing water repellency is formed on the undercoat. The average of the fine particles (A) A water repellent metal coating material characterized in that the particle diameter is 1.5 times or more larger than the film thickness of the organic resin undercoat, and the average particle diameter of the fine particles (B) is larger than the thickness of the finished film.
(3) An underlayer made of an organic resin containing organic or inorganic fine particles (A) is formed on at least one surface of the metal material, and an average of 1/4 or less of the fine particles (A) is formed on the underlayer. An undercoat made of an organic resin containing organic or inorganic fine particles (B) having a particle size is formed, and at least a part of the fine particles (B) is attached to the surface of the fine particles (A). A finish film showing water repellency is formed on the surface, and the average particle diameter of the fine particles (A) is 1.5 times or more larger than the total film thickness of the organic resin undercoat, and the average particle diameter of the fine particles (B) is the finish film Water repellent metal coating material characterized in that it is larger than the thickness.

(4) Organic or inorganic fine particles (A) and (B) are silicate, metal oxide, diatomaceous earth, glass, acrylic resin, styrene resin, benzoguanamine / melamine resin, urethane resin, phenol resin, polyethylene The water-repellent metal coating material according to any one of the above (1) to (3), which is at least one selected from a base resin and a fluororesin.
(5) The water repellent metal coating material according to any one of the above (1) to (4), wherein the film thickness of the organic resin undercoat is 0.5 to 10 μm.
(6) The water repellent metal coating material according to any one of the above (1) to (5), wherein the average particle diameter of the fine particles (A) is 1.5 to 15 μm of the film thickness of the organic resin undercoat.
(7) The above-mentioned characterized in that the base film contains 3.5 to 20 parts by mass of fine particles A and 0.4 to 3.5 parts by mass of fine particles B with respect to 100 parts by mass of the organic resin. The water repellent metal coating material according to any one of 2) to (6).

(8) The water repellent metal coating material according to any one of (1) to (7), wherein the organic resin is an epoxy resin.
(9) The water repellent metal coating material according to any one of the above (1) to (8), wherein the finish film is at least one selected from fluorine and silicone.
(10) The water repellent metal coating material according to any one of (1) to (9), wherein the metal is aluminum or an alloy thereof.
(11) Organic or inorganic fine particles (B) having an average particle diameter of 1/4 or less of organic or inorganic fine particles (A) or fine particles (A) and the fine particles (A) on at least one surface of the metal material A base film is formed by a drying or baking process, a water-repellent coating is applied on the base film, and a final film is formed by a drying or baking process. ) Is 1.5 times larger than the film thickness of the organic resin, and the average particle diameter of the fine particles (B) is larger than the thickness of the finished film.
(12) An organic resin paint containing organic or inorganic fine particles (A) is applied to at least one surface of the metal material, and a first base film is formed by a drying or baking process, and the first base film is formed on the base film. An organic resin paint containing organic or inorganic fine particles (B) having an average particle size equal to or smaller than 1/4 of the fine particles (A) is applied, and a second undercoat is formed by a drying or baking process. A method of applying a water-repellent paint on a film and forming a finished film by a drying or baking process, wherein the average particle diameter of the fine particles (A) is 1.5 times or more larger than the total thickness of the organic resin, A method for producing a water-repellent metal coating material, characterized in that the average particle diameter of the fine particles (B) is larger than the thickness of the finished film.

  The metal coating material of the present invention has high water repellency and can also be super water repellant. In the air conditioner heat exchanger, moisture in the air adheres to the surface of the aluminum fins as condensed water during the cooling operation, but if the metal coating material of the present invention is used, condensed water can be eliminated, The heat exchange rate can be improved.

The present invention will be described in detail below.
The metal coating material of the present invention is obtained by forming a base film made of an organic resin containing specific particles on at least one surface of a metal material, and forming a water-repellent finish film thereon.
The metal material can be applied to aluminum and other metals, but an aluminum material is particularly preferable.
It is known that the water repellency of a plate material or the like is generally correlated with the surface of the plate material, and the water repellency increases as the surface area increases. Thus, as a method of increasing the surface area of the plate surface, there is a method of providing irregularities on the water-repellent coating itself to increase the surface area, but it is difficult to impart irregularities to the water-repellent coating. Therefore, in the present invention, it is possible to form a film having water repellency by forming fine irregularities on the base film with fine particles and forming a water-repellent finish film on the surface. .

  The organic resin of the base coating in the present invention may be a resin used in general paints, for example, epoxy resin, alkyd resin, acrylic resin, urethane resin, phenol resin, melamine resin, polyvinyl butyral resin, polyester resin, etc. Is mentioned. Among them, the epoxy resin is optimal as a resin to be used for molding because it has a good balance of flexibility, water resistance, corrosion resistance, and coating film adhesion. Examples of the epoxy resin include cyclic aliphatic types such as bisphenol type, novolac type, and glycidyl type, and non-cyclic aliphatic types, but are not particularly limited. The epoxy equivalent of the epoxy resin is not particularly limited. Among these, an epoxy resin obtained by reacting bisphenols is particularly preferable from the viewpoint of good industrial versatility and corrosion resistance. Examples of the bisphenols include bisphenol A, bisphenol F, bisphenol S, tetrabromobisphenol A and the like, and only one kind may be used alone, or two or more kinds may be used as a mixture. Among these, bisphenol A type epoxy resin is preferable from the industrial versatility.

As the fine particles contained in the undercoating film, fine particles (A) having an average particle size 1.5 times larger than the film thickness of the organic resin portion of the undercoating film are used. If the average particle size of the fine particles (A) is less than 1.5 times the film thickness of the organic resin portion, a sufficiently large effect on the surface shape cannot be obtained, and sufficient water repellency cannot be imparted. Further, the average particle diameter of the fine particles (A) is preferably 15 μm or less because if the average particle diameter is too large, the coating cannot hold the fine particles. The average particle diameter is measured with a laser diffraction / scattering particle size distribution meter.
In the present invention, in order to improve the water repellent effect, the fine particles (A) plus the fine particles (B) are used. The fine particles (B) have an average particle size of ¼ or less of the average particle size of the fine particles (A). At least a part of the fine particles (B) adheres to the surface of the fine particles (A), and the surface area of the fine particles can be increased. If the average particle size of the fine particles (B) is larger than ¼ of the average particle size of the fine particles A, the fine particles (B) are likely to fall off when attached to the periphery of the fine particles A, and the surface effect is not exerted around the fine particles A. Therefore, the effect of improving water repellency is lowered. By forming small irregularities with the fine particles (B), the number of convex portions as the starting point of frost formation increases, and the frost is removed before it sufficiently develops.

In the present invention, when the fine particles (A) and the fine particles (B) are contained, the underlayer is composed of two layers in order to further enhance the effect. That is, an organic resin base film containing fine particles (A) is formed on the surface of a metal material as a first base film, and a second organic resin base film containing fine particles (B) is formed thereon. . By forming the second base film after drying or baking the first base film, the fine particles (B) can be efficiently attached to the surface of the fine particles (A) protruding from the surface of the resin film. .
The fine particles (B) appearing above the surface of the finished film is effective in increasing the surface area, and therefore the fine particles (B) have an average particle size larger than the thickness of the finished film.
The type of fine particles is selected from silicate, metal oxide, diatomaceous earth, glass, acrylic resin, styrene resin, benzoguanamine / melamine resin, urethane resin, phenol resin, polyethylene resin, and fluorine resin. It is preferably composed of one or more kinds. Of these, silica, alumina, and organic are preferably acrylic based on the inorganic system from the viewpoint of adhesion to the film and shape effect.

In the case of the fine particles (A) alone, the content of the fine particles A in the undercoat is preferably 5 to 30 parts by mass when the organic resin is 100 parts by mass. When the content is less than 5 parts by mass, the effect of the surface shape is small, and the effect of improving water repellency is low.When the content exceeds 30 parts by mass, the amount of fine particles A in the resin is excessively increased, and the coating film adhesion is reduced. It becomes difficult to keep. Moreover, when using together microparticles | fine-particles (A) and microparticles | fine-particles B, as for those content, with respect to 100 mass parts of organic resins, microparticles | fine-particles (A) are 3.5-20 mass parts, and microparticles | fine-particles B are 0.4-3.5 mass parts. It is preferable to do this. The reason for limiting the numerical value of the fine particles (A) is the same as described above. When the content of the fine particles B is less than 0.4 parts by mass, the effect of improving water repellency is reduced. On the contrary, it becomes smooth and the improvement effect decreases.
The film thickness of the organic resin portion of the undercoat is preferably 0.5 to 10 μm. When the film thickness is less than 0.5 μm, it is difficult to hold the fine particles (A), and when it is thicker than 10 μm, the effect is saturated and uneconomical.
As the type of the finish coating film, a general water-repellent coating film may be processed. Among them, as the water repellency treatment, fluorine type or silicone type is preferable because both water repellency and adhesion are good.

  Moreover, designability can be provided by making a base resin composition contain a pigment or dye. The pigment or dye is not particularly limited as long as it is generally used in the paint field. Examples of pigments include inorganic pigments such as titanium dioxide, zinc oxide, chromium oxide, cadmium sulfide, calcium carbonate, barium carbonate, barium sulfate, clay, talc, yellow lead, iron oxide, and carbon black, azo series, diazo series, and condensed azo. And organic pigments such as thioindigo, indanthrone, quinacridone, anthraquinone, benzimidazole, perylene, perinone, phthalocyanine, halogenated phthalocyanine, anthrapyridine, and dioxazine. Examples of the dye include direct dyes, reactive dyes, acid dyes, cationic dyes, vat dyes, and mordant dyes. The above pigments or dyes may be contained alone or in combination of two or more.

As the coating material in the present invention, both water-based and solvent-based coatings may be used as long as they are formed with the above-mentioned coating film.
And there is no restriction | limiting in particular about the method of apply | coating the base resin composition for hydrophilic coating of this invention to the surface of various hard materials.
Examples of the coating method for forming the coating include a roll squeeze method, a chemicoater method, a roll coater method, an air knife method, a dipping method, a spray method, an electrostatic coating method, etc., and drying is a general heating method or dielectric heating method. This can be done by law. Among these methods, the roll coater method is preferable from the viewpoint of coating uniformity and productivity. As the roll coater method, a method using a gravure roll that is convenient for coating amount management, a natural coating method that is convenient for thick coating, a reverse coating method that is advantageous for beautifully finishing the coated surface, etc. are adopted. be able to.

  In the method of forming the base film, after applying a coating material containing, for example, an epoxy resin containing fine particles A or fine particles (A) and fine particles (B), drying or baking is performed. In the case of two layers of the undercoat, first, a paint containing fine particles (A) is applied, followed by drying or baking, and then a paint containing fine particles B is applied, followed by drying or baking (two-coat two-baking Process). In the case of two layers of the undercoat, it is possible to apply the paint continuously and dry or bake at once (2 coats 1 bake), but in order to make the fine particles (B) easily adhere around the fine particles (A). For this, an undercoat film forming method by two coats and two bake is more effective.

As for the baking heating conditions performed when forming the base film, the baking temperature (reached surface temperature) is preferably 150 ° C. or higher, more preferably 170 to 300 ° C., and the baking time is preferably 1 to 60 seconds. .
When the baking temperature in coating is less than 150 ° C. or the baking time is less than 1 second, the coating film is not sufficiently formed, and the coating film adhesion and the corrosion resistance are significantly reduced. On the other hand, when the baking temperature exceeds 300 ° C. or the baking time exceeds 60 seconds, discoloration or deterioration of the adhesion of the coating film occurs, which causes a problem on the product.
The finish film is formed by applying a water-repellent composition to the base coat aluminum coating material formed by the above method, drying or baking, and forming a water-repellent film on the surface.

Hereinafter, preferred embodiments of the present invention will be described in detail based on examples and comparative examples.
In the following examples, Examples 1 and 3 to 15 are shown as reference examples.
〔Example〕
The production methods of Examples and Comparative Examples were as follows.
About resin of each Example and a comparative example, an aluminum alloy plate (1100-H24 material, 0.100 mm thickness) is weakly alkaline degreased, washed with water and dried, and then an organic resin coating is applied with a roll coater, and a predetermined reaching plate is obtained. Baking was performed at the surface temperature (PMT) for a time to obtain a base coating aluminum alloy plate having a predetermined coating amount. Each water-repellent treatment agent was applied and baked on the obtained base-coated aluminum alloy plate with a roll coater to obtain a water-repellent coated aluminum alloy plate. The baking condition for the base film is 240 ° C. for 20 seconds, and the baking condition for the water-repellent film is 80 ° C. for 60 seconds. About the obtained water-repellent coating aluminum alloy plate, water repellency, coating-film adhesiveness, and defrosting property were measured with the following method.
The epoxy resin of the paint shown in Table 1 is an ester type epoxy resin obtained by adding an acrylic resin to a bisphenol A epoxy resin, and the weight average molecular weight is about 3,800.
The fluororesin is Fluorosurf FS-3030TH-2.0 manufactured by Fluro Technology.

In Example 1, a paint containing fine particles A was applied and baked, and then a water repellent treatment agent (finish paint) was applied and baked.
In Example 2, a paint containing fine particles A and B was applied and baked, and then a water repellent treatment agent was applied and baked with a roll coater.
In Examples 3 to 15, a coating containing fine particles A was applied and baked, and then a coating containing fine particles B was applied and baked, and a water repellent treatment agent was applied and baked onto the base coated aluminum alloy plate.
In Comparative Example 1, a water-repellent treatment agent was applied and baked on an aluminum alloy plate that had not been subjected to a base treatment.
In Comparative Example 2, a water-repellent treatment agent was applied and baked after applying and baking a paint not containing fine particles.
In Comparative Example 3, a coating containing fine particles A having a small particle size was applied and baked, and then a water repellent treatment agent was applied and baked.
In Comparative Example 4, a base-coated aluminum alloy plate was used in which a coating containing fine particles A was applied and baked, and then a coating containing fine particles B was applied and baked.

[Water repellency]
The contact angle of pure water was measured with a goniometer.
A: Contact angle is 130 ° or more ○: Contact angle is 100 ° or more and less than 130 Δ: Contact angle is 80 ° or more and less than 100 ° X: Contact angle is less than 80 ° [Coating film adhesion]
Using the adhesion test in JIS H4001, the number of remaining pieces after tape peeling at the grid was measured.
[Defrosting]
A sample cooled to −10 ° C. was placed in a constant temperature bath of 10 ° C. × RH 60%, and the surface frost formation state was visually observed.
●: No frosting △: Partial frosting ×: With frosting

As shown in Table 1, in all of the examples, no problems were observed in water repellency, coating film adhesion, and frost formation, and the examples were fully or partially satisfied. Table 2 is data showing the basis of the composition in Table 1.
Example 1 is an undercoating film containing only fine particles A and does not contain fine particles B, Example 2 is an undercoating film formed by a single-layer coating in which fine particles A and fine particles B are mixed, and Example 7 is a fine particle A. In Example 9, since the addition amount of the fine particles B was small, fine convex portions could not be formed and frost was partially generated, but the performance was almost satisfied. Among them, Examples 3 to 6, 8, and 10 to 15 sufficiently satisfied any performance.
However, Comparative Example 1 is a material having only a water-repellent film, Comparative Example 2 is a material in which a finish film is formed on an undercoat that does not contain fine particles, and Comparative Example 3 is a finish film on an undercoat that contains fine particles having a particle size that is too small. Comparative Example 4 was a material in which an undercoat containing fine particles A and B was formed, but since a finish coat was not formed, sufficient irregularities could not be formed, and the water repellency and defrosting properties were not formed. Both were not satisfied.

The metal coating material of the present invention has high water repellency, can eliminate the condensed water on the surface of the aluminum fin in the heat exchanger for an air conditioner, and can improve the heat exchange rate.
It is a recent heat exchanger for an air conditioner that is compact in order to reduce the weight and improve the thermal efficiency, and can also be used for a heat exchanger that is designed as narrow as possible with a fin interval.

Claims (9)

  An undercoat comprising an organic resin containing organic or inorganic fine particles (A) and organic or inorganic fine particles (B) having an average particle size of ¼ or less of the fine particles (A) on at least one surface of a metal material The surface of the fine particles (A) has at least a part of the fine particles (B) attached thereto, and a finish film showing water repellency is formed on the base film. The average particle diameter of the fine particles (A) is A water repellent metal coating material characterized in that it is 1.5 times or more larger than the film thickness of the organic resin undercoating and the average particle size of the fine particles (B) is larger than the thickness of the finished coating. Organic or inorganic fine particles (A) and (B) are silicate, metal oxide, diatomaceous earth, glass, acrylic resin, styrene resin, benzoguanamine / melamine resin, urethane resin, phenol resin, polyethylene resin, The water repellent metal coating material according to claim 1 , which is at least one selected from fluorine-based resins. The water-repellent metal coating material according to claim 1 or 2 , wherein the organic resin base film has a thickness of 0.5 to 10 µm. The water repellent metal coating material according to any one of claims 1 to 3 , wherein an average particle diameter of the fine particles (A) is 1.5 to 15 µm of a film thickness of the organic resin undercoat. Wherein relative to 100 parts by weight of the organic resin in the undercoat in the coating, according to claim 1 to 4 fine particles A contain from 3.5 to 20 parts by mass, the fine particles B, characterized by containing 0.4 to 3.5 parts by weight The water-repellent metal coating material according to any one of the above. The water-repellent metal coating material according to any one of claims 1 to 5 , wherein the organic resin is an epoxy resin. The water repellent metal coating material according to any one of claims 1 to 6 , wherein the finish film is at least one selected from fluorine and silicone. The water repellent metal coating material according to any one of claims 1 to 7 , wherein the metal is aluminum or an alloy thereof. An organic resin coating containing organic or inorganic fine particles (A) and organic or inorganic fine particles (B) having an average particle size of 1/4 or less of the fine particles (A) is applied to at least one surface of the metal material. , a base film is formed by drying or baking step, the water-repellent coating material is applied on the lower ground coating, a method of forming a finished coating by drying or baking step, the surface of the microparticle (a) fine particles (B ) Are attached, the average particle size of the fine particles (A) is 1.5 times or more larger than the film thickness of the organic resin, and the average particle size of the fine particles (B) is larger than the thickness of the finished film. A method for producing a water-repellent metal coating material.