JPH07166123A - Water-repellent coating material, its production and heat exchanger - Google Patents

Abstract

PURPOSE:To provide a coating film having fine ruggedness made up by water- repellent particles on the surface, exhibiting water repellency even to a fine water drop since the whole surface is made of a water-repellent material and excellent in duration of the water repellency. CONSTITUTION:A plating layer 2 in which water-repellent particles 3 are compounded is formed on a base 1 and a water-repellent coating film 4' having a melting point lower than that of the water-repellent particles 3 is placed thereon. The water-repellent particles 3 are partly projected above the coating film 4' in a state where they are partly buried in the coating film 4'.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coating used in electric appliances, automobile equipment, medical equipment and the like which require water repellency and a method for producing the coating.

[0002]

2. Description of the Related Art Conventionally, many coatings used for the purpose of water repellency are composed of a silicon-based or fluorine-based resin compound, and a method of applying a solution of these resin compounds is used as a manufacturing method thereof. . The contact angle of these coatings is often around 110 degrees. Also, the contact angle 170
As a coating film having a thickness of at least one degree, as described in JP-A-4-285199, there is a coating film in which a metal is used as a matrix and water-repellent particles are combined therewith.

Further, as a film forming method, Japanese Patent Publication No.
As described in JP-A-1560, there is known a method of forming a fluororesin film on a part or all of the surface of the plating film.

[0004]

However, in the case of a conventional coating having a contact angle of around 110 degrees, which is said to be water repellent, the diameter is about 1 m.
m water drops do not roll down, and about 3 m in diameter for water drops to fall
must be at least m. In addition, the contact angle 17 described above
A coating film of 0 degree or more also shows excellent water repellency for running water or water droplets having a diameter of about 1 mm or more, but the water repellency is reduced for water vapor, mist-like water droplets, or condensed water. This is shown in FIG.
It is considered that when the surface of the film is enlarged as shown in (3), the metal part 2 of the matrix exists on the surface of the film, and water vapor or mist-like water 10 adheres thereto. Once water adheres to the hydrophilic metal part 2 on the surface of the coating, the water repellency decreases, and unless the water is completely dried to remove the water, the water repellency greatly decreases.

Further, although they show excellent water repellency immediately after the treatment, the water repellency gradually decreases with the passage of time. This is due to the water remaining on the coating surface metal part,
It is also considered that the water-repellent particles fall off the surface.

Further, in the method for producing a coating film using such a composite plating, as in the above-mentioned conventional example, after the fluororesin particle composite plating is formed, particles are further supplied to the surface, and heat treatment is performed at a temperature at which the particles melt to form a coating film. There is a method of coating the entire surface, but these coatings are intended for non-stickiness,
It is used for molds with excellent mold release properties. However, in this coating, as shown in FIG. 11, the particles are melted by the heat treatment and the surface of the coating becomes a smooth surface 3 ′ having no unevenness, so that the contact angle is about 110 degrees.

Further, a method of treating the surface of the fins of the heat exchanger with a water-repellent coating to improve the heat exchange efficiency has been reported, but it is known that the effect decreases when continuously used. In the future, as a film compatible with products, a film that is compatible with all forms of moisture and that is durable is required.

It is an object of the present invention to provide a coating film which is water-repellent to water vapor and mist-like water drops and has durability, a method for producing the coating film, and a heat exchanger including the coating film.

[0009]

Means for Solving the Problems The above-mentioned object is to reduce the exposure of the hydrophilic matrix portion constituting the coating film, which is one of the causes of the decrease in water repellency, to the utmost while maintaining the unevenness of the surface. It is achieved by

Therefore, in the coating film of the present invention, a water-repellent coating film is arranged directly or indirectly on a substrate, and a part of the water-repellent coating film is buried in the coating film and a part of the water-repellent coating film is projected on the coating film. And the water repellent coating material and the water repellent particles have different melting points.

The water-repellent coating and the particles may be made of a substance having a hydrophobic group, and the hydrophobic group may be one having a fluorocarbon or hydrocarbon surface structure.

Further, the water-repellent coating and the particles may be composed of a substance having a group having a critical surface tension smaller than that of water. Further, the particles may be composed of a substance having a group having a critical surface tension smaller than that of polytetrafluoroethylene (hereinafter referred to as PTFE).

In order to achieve the above-mentioned object, the coating film of the present invention has a water- and oil-repellent coating disposed directly or indirectly on a substrate, a part of which is buried in the coating, and a single layer is formed on the coating. The water-repellent and oil-repellent particles are dispersed so that the parts protrude, and the water-repellent oil-repellent coating and the water-repellent oil-repellent particles have different melting points.

The water- and oil-repellent coating and the particles may be made of a fluororesin.

The water-repellent coating and the water- and oil-repellent coating are
It may be made of a material having a melting point lower than that of the material of the water-repellent particles and the water- and oil-repellent particles.

A further object of the present invention is to provide a heat exchanger having a group of tubes through which a cooled refrigerant flows, and a group of fins fixed to the group of tubes and allowing air to flow between them. It is achieved by directly or indirectly forming a water-repellent coating in which the water-repellent particles, which are partially buried in and are projected on the coating, have a melting point different from the melting point of the coating.

The water-repellent coating may have the above-mentioned structure.

Further, the above-mentioned object is to prepare a water-repellent coating by a first step of forming a coating on the surface of a substrate in which high-melting-point water-repellent particles are composited by an electric action, and a high-melting-point water-repellent coating on the surface of this coating. It is achieved by a method comprising a second step of supplying water-repellent particles having a melting point lower than that of the particles and a third step of heat-treating at a temperature at which the water-repellent particles of low melting point supplied to the surface of the coating are softened or melted. It

Further, the first step of forming a coating film, which is a composite of two or more kinds of water-repellent particles having different melting points, on the surface of the substrate by an electric action, and the low-melting point particles of the two or more kinds of water-repellent particles are A water-repellent film may be produced by a second step of heat treatment at a softening or melting temperature.

Further, the first step of forming a coating film on the surface of the substrate, which is composed of two or more kinds of water-repellent particles having different melting points, by an electric action, and a low melting point of the water-repellent particles of two or more kinds on the surface. The method for producing a water-repellent coating film may include a second step of supplying the water-repellent particles and a third step of performing heat treatment at a temperature at which the low-melting-point water-repellent particles are softened or melted.

In the above water-repellent coating manufacturing method, a metal plating method is used as a method for forming the coating by an electric action.
An electrodeposition coating method may be used.

The matrix of the plating film may be nickel or nickel alloy.

The method for producing the water-repellent coating is as follows: the first step of applying two or more kinds of water-repellent particles having different melting points to the substrate surface, and the low-melting-point water-repellent particles among the two or more kinds of water-repellent particles. May be softened or melted, and a heat treatment may be performed at a temperature equal to or lower than the melting point of the water-repellent particles having a high melting point. In this method, the first step is to form two or more kinds of water-repellent particles on the substrate surface. You may make it apply several times repeatedly.

The two or more types of water repellent particles having different melting points may have different particle sizes.

[0025]

According to the present invention, minute irregularities can be formed by water-repellent particles on the surface of the coating film. This makes it possible to maintain point contact with the water droplets, thus improving water repellency. By changing the particle size of the particles, the size of the surface irregularities can be easily changed.

Further, since the water-repellent coating is formed by softening or melting the particles having a low melting point, this coating plays a role of a binder for holding the particles having a high melting point attached to the surface. As a result, it is possible to prevent the particles from falling off from the surface of the coating film and obtain a durable coating film.

The water-repellent particles are PTFE, tetrafluoroethylene-hexafluoropropene copolymer (hereinafter referred to as PFA), tetrafluoroethylene-perfluoro (alkyl = vinyl = ether) copolymer (hereinafter referred to as FEP). Fluorine-based resins such as
There is no particular limitation as long as it exhibits water repellency such as polyethylene (PE). Since many of these particles have a wide range of melting points, heat treatment is easier for particles having a difference in melting point of 10 ° C. or more, preferably 20 ° C. or more. The average particle diameter of the water-repellent particles used is 0.1.
˜100 μm, and particularly preferably 0.2 to 20 μm. In this case, since the low melting point particles are supplied later to form the surface layer, it is desirable that the particle size of the low melting point particles is smaller than that of the high melting point particles in order to control the film thickness of the surface layer. . In addition, the high melting point particles always project and form irregularities on the surface layer composed of the softened or melted low melting point particles. Since the high melting point particles mainly determine the water repellency of the coating film, the high melting point particles are preferably made of a substance having a group having a critical surface tension smaller than that of polytetrafluoroethylene.

Further, a metal, a polymer or the like can be used as the matrix of the coating. For example, as a metal,
Nickel, nickel alloy, copper, iron, iron alloy, cobalt,
Metal plating such as silver or zinc can be used. Alternatively, as the polymer, a commercially available electrodeposition liquid such as an epoxy type or an acrylic type can be used.

The substrate is not particularly limited as long as it is electrically conductive because it forms a film by an electric action or has an electrically conductive substance on its surface.

According to the method for producing a water-repellent coating of the present invention, a conductive substrate is used as a cathode, positively charged high-melting-point water-repellent particles are dispersed in a solution, and the particles are electrically operated in the solution. An existing method can be used in the step of forming a composite film of, and a new function can be easily provided by supplying water-repellent particles having a low melting point and heat-treating the same.

The amount of the water-repellent particles dispersed in the solution used for forming the coating film in the above-mentioned manufacturing method is 3 to 15 wt.
%, Particularly 5 to 10 wt% is preferable, and in this case, the composite rate of particles in the coating is 35 to 45 vol%. When the amount is less than the above range, the amount of water-repellent particles on the surface of the coating decreases and the water repellency of the coating decreases, and when the amount exceeds the above range, the viscosity of the dispersion solution increases and liquid agitation during coating formation becomes difficult. This is because it becomes non-uniform, and the coating film to be formed is also more uneven and uneven.

As a method of supplying particles to the surface of the coating film, a method such as dipping, spray coating, spin coating or the like can be used. The amount of water-repellent particles dispersed in the solution used at this time varies depending on the particles, but is from 1 to 10
About wt%, it is possible to easily add by repeatedly applying the same operation repeatedly if necessary.

[0033]

EXAMPLES The present invention will be specifically described below with reference to examples.

In this example, nickel was used as the matrix of the coating film, and the film was formed by electroplating. In this example, a nickel sulfamate bath having the following composition was used as a base plating solution.

<Composition> Nickel sulfamate 350-450 g / l Nickel chloride 0-45 g / l Boric acid 30-40 g / l A conductive metal was used for the substrate, and pretreatment suitable for the substrate was performed. After the substrate was washed with an organic solvent, degreasing, etching and acid activation were performed. Note that aluminum or aluminum alloy was subjected to zincate (zinc substitution) treatment.

If the surface condition of the substrate is not stable, nickel strike plating is performed if necessary.

Table 1 shows the materials and their melting points as particles applicable to the present invention. If the particles used in the present invention are water-repellent and have different melting points, the particles in Table 1
It is not limited to those shown in.

[0038]

[Table 1]

Several kinds of particles were selected from Table 1 to form a film. As the particles having a high melting point, PTFE (manufactured by Central Glass Co., Ltd., trade name, Cefraral Lube I, average particle size 5 μm), PFA (manufactured by Asahi Glass Co., Ltd., trade name, Aflon P)
FA, average particle size 7 μm), PTF as particles with low melting point
E (manufactured by Central Glass Co., Ltd., trade name, Cefraral Lube V, average particle size 1 μm), FEP (manufactured by Mitsui DuPont Fluorochemical Co., Ltd., trade name, Teflon 120-J, average particle size 0.2 μm) were used. .

Examples of the present invention will be shown below.

Example 1 A particle composite plating solution having the following composition 1 was prepared and subjected to particle composite nickel plating under the following plating conditions. In this embodiment, the size of the sample is
An oxygen-free copper plate of 30 mm x 100 mm x 1 mm was used.

<Composition 1> Nickel sulfamate 350 g / l Nickel chloride 45 g / l Boric acid 40 g / l High melting point particles (high PTFE molecular weight or PFA) 140 g Cationic surfactant (1 wt% aqueous solution) 140 g << Plating treatment conditions >> pH 4.0 to 4.2 Treatment temperature 45 ± 2 ℃ Current density 5A / dm ² Treatment time 10min The plating thickness depends on the diameter of the composite particles in the plating film. Then, it was set to about 10 μm corresponding to the composite particle size. In addition, the particles of the present embodiment are mixed with the plating solution as compared with the case where the plating solution does not contain particles, so the plating current density, which is an important factor of the plating conditions, was examined. As a result, it was found that the content of water-repellent particles decreased at low current densities, aggregates of water-repellent particles were formed at high current densities, and rough portions were formed at the edges of the sample due to the edge effect, and the appropriate current A density of 5 ± 1 A / dm ² was used.

A schematic cross-sectional view of the coating after plating is shown in FIG. As is clear from the figure, the nickel plating layer 2 composited with water-repellent particles has a nickel-only layer at the boundary of the substrate 1. However, when nickel ions and particles are compared, the particles are about 10,000 times larger. Therefore, nickel ions are first deposited on the substrate, and then nickel ions and particles are combined and deposited, so that the cross-sectional structure shown in the figure is obtained.

This coating has a form in which nickel is used as a matrix on the substrate 1 and the water-repellent particles 3 are compounded in the coating. The coating of this cross-sectional shape is the same as that of the conventional water-repellent coating, and exhibits excellent water repellency against running water or water droplets having a diameter of 1 mm or more.

However, there are some particles 3 on the surface of the coating film which are not taken into the matrix and are merely attached to the surface, and the surface of the coating film is scratched or the water-repellent particles 3 fall off by only light contact with the surface. There is a problem in durability.

Next, a dipping treatment was applied to the coating having the cross-sectional shape shown in FIG.

The dipping treatment was carried out by mixing the water-repellent particles, the surfactant, the aqueous sodium hydroxide solution and ethanol, respectively, and then mixing both, as in the above-mentioned plating solution preparation method. In the dipping process, the dipping liquid is stirred so that the water-repellent particles are evenly dispersed, the sample is immersed in the dipping liquid, then slowly (about 5 to 50 mm / sec) is pulled up in the direction perpendicular to the liquid surface, and then dried. It was performed by the method.

The cross-sectional morphology of the coating portion at this stage is shown in FIG.
Shown in. The low-melting-point water-repellent particles 4 are adhered to the surface and between the water-repellent particles 3 shown in FIG. 2 by the dipping treatment.

<Composition 2> PTFE particles (mp242 to 255 ° C.) 5 g Cationic surfactant (1 wt% aqueous solution) 5 g Sodium hydroxide aqueous solution (0.01 M) 50 g Ethanol 50 g As a final treatment, the particles were attached to the coating surface by dipping. The heat treatment was performed at a temperature of 245 ± 2 ° C. at which the PTFE particles, which are the water-repellent particles 4 having a low melting point, melt.

As a result, a water-repellent coating having a cross-sectional shape as shown in the partial cross-sectional perspective view of FIG. 1 was obtained.

As shown in FIG. 3, the low-melting-point water-repellent particles 4 attached to the surface and between the high-melting-point water-repellent particles 3 in FIG. A coating 4'having a thickness of about 1 .mu.m is formed on the top of the coating 4 '. That is, the surface of the coating film has an uneven shape due to the high melting point particles 3, and the coating film 4 ′ formed by melting the low melting point particles 4 serves as a binder that holds the high melting point particles together. Since the high melting point particles 3 and the low melting point particles 4 are water-repellent and do not mix with each other, such a cross-sectional structure is formed.

As a result, as is apparent from comparison with the conventional coating structure shown in FIG. 2, the metal portion on the coating surface is not exposed. In this example, since the heat treatment temperature was set to the one having a lower melting point temperature range, the heat treatment time was set to 1 hour so that the low melting point particles 4 could sufficiently enter between the high melting point particles 3, but the heat treatment temperature was increased. If set to, heat treatment time can be shortened. When the difference between the melting points of the two types of particles is large, the processing time can be shortened by setting the temperature higher.
Needless to say, the heat treatment is required to raise the temperature of the coated portion, and the time must be adjusted depending on the heat capacity of the sample.

The same dipping process was performed using a dipping solution having the composition 3 shown below to obtain 260 ± 2.
The cross-sectional structure after heating at 1 ° C. for 1 hour was also the same as when the composition 2 was used as a solution.

<Composition 3> FEP particle dispersion (55% by weight, mp 254 to 270 ° C.) 5 g Ethanol 95 g In order to evaluate a film by the coating method shown in this example,
A steam condensation test was performed with different coating materials. As a typical conventional water-repellent coating for comparison, two types of coatings having different cross-sectional structures shown in FIG. 2 with different types of water-repellent particles and an uncoated copper material surface were evaluated.

An experimental test piece is an oxygen-free copper plate (30 mm × 40 mm).
The water repellent treatment described above was performed on one surface of the surface of the surface of the surface of the surface of the surface of the surface of the sheet.
As shown in Table 2, the coating formed on the test piece was prepared by changing the combination of the materials of the water-repellent particles to be combined with the plating layer.
To four test pieces 1-4 were prepared. The test piece is installed vertically in a thermostatic chamber in the following atmosphere and cooled from the back. After a lapse of a certain time (about 10 minutes), condensed water begins to attach to the surface of the film, gradually grows and becomes larger, and drops off as water droplets. The state of the water droplets flowing down was photographed to measure the particle size.

<< Condensation Conditions >> Ambient temperature 15 ± 1 ° C Cooling surface temperature 2 ± 2 ° C Dew point temperature 13 ± 0.5 ° C Humidity 70% Table 2 shows the evaluation test results. As is clear from the table, the minimum particle size that water vapor condenses and rolls into water droplets is:
The water-repellent coating of the present invention is about 0.3 mm to 1.0 mm, which is smaller than about 3 mm to 5 mm of the conventional coating and 4 mm of the bare surface of the copper material, which has a very large water-repellent effect on condensed water. There was found. In particular, the test piece of test piece 1-1 has a minimum particle diameter of 0.3 mm that rolls down as water droplets, and even if water vapor condenses, it drops with extremely small water droplets. Remarkably reduced compared to the one.

[0057]

[Table 2]

Example 2 Using the particle composite plating solution having the composition 4 shown below, particle composite electric nickel plating was performed under the same plating conditions as in Example 1 above. In this embodiment, both high-melting-point water-repellent particles and low-melting-point water-repellent particles are simultaneously mixed in the plating solution, and a coating film having substantially the same structure as that of the above-mentioned embodiment is formed without performing dipping treatment. Different from

In this embodiment, the mixing ratio of the high melting point water repellent particles and the low melting point water repellent particles in the plating solution was 10:
It was set to 2. This is because the low-melting point water-repellent particles used in this example are smaller in particle size than the high-melting point water-repellent particles and are therefore likely to be compounded in the coating film. As a result of various studies, the mixing ratio was 10: 1. It turns out that about 10: 4 is good.
That is, when there are many low-melting-point water-repellent particles, the content ratio of the high-melting-point water-repellent particles compounded in the plating film during the plating treatment to the low-melting-point water-repellent particles decreases, and the heat treatment causes the low-melting-point water-repellent particles to decrease. When water is dissolved, the uneven shape of the high melting point water repellent particles formed on the surface becomes sparse, and the water repellency decreases. Further, if the low-melting-point water-repellent particles are small, even if the low-melting-point water-repellent particles are dissolved, the amount thereof is small and the nickel surface of the plating film cannot be covered.

<Composition 4> Nickel sulfamate 350 g / l Nickel chloride 45 g / l Boric acid 40 g / l High melting point particles (PTFE molecular weight large or PFA) 120 g Low melting point particles (PTFE molecular weight small or FEP) 24 g Cationic surfactant (1 wt% aqueous solution) 144 g The cross-sectional morphology of the coating after plating is shown in FIG. As shown in the figure, both the high melting point water repellent particles 3 and the low melting point water repellent particles 4 are compounded in the nickel plating layer 2 formed on the substrate 1, and both are formed on the surface of the nickel plating layer 2. The particles are attached.

Next, heat treatment was performed under the conditions shown in the above Example 1 to obtain a coating film having a sectional structure shown in FIG. Only the low-melting water-repellent particles 4 are melted in the coating film, and are melted down on the metal matrix portion 2 between the high-melting-point water-repellent particles 3 to form a coating film 4 '. In contrast to the coating of Example 1 described above, a portion of the coating 4 ′ that digs into the surface of the nickel plating layer 2 is formed. The cause is the nickel plating layer 2
This is because some of the low melting point water-repellent particles 4 composited with the one that are partially exposed on the surface of the nickel plating layer 2 are integrated with those that have melted down from the surface, and the thickness of the coating film 4'is thin. Due to that.

According to this embodiment, the high melting point water-repellent particles 3 are used.
Since the heat treatment may be performed after the water-repellent particles 4 having a low melting point are simultaneously compounded in the coating film, the number of working steps may be reduced as compared with the steps of the above-described Example 1 because the dipping process is not performed.

Example 3 In this example, first, the film shown in FIG. 4 is formed by the same steps as the steps shown in Example 2 above. Next, dipping treatment was performed using the dipping solution having the composition 2 used in Example 1 above. The sectional structure of the coating film at this stage is as shown in FIG. Finally, heat treatment at 245 ± 2 ° C. was performed to obtain a film shown in FIG. The coating according to the present embodiment is different from the coating according to the second embodiment in that the thickness of the coating 4'is as thick as about 2 μm and the surface thereof is flat.

According to this embodiment, the coating film 4'formed on the surface of the coating film increases the anchoring effect for holding the high melting point water-repellent particles 3 and further improves the durability.

Example 4 This example is an example in which a water-repellent film was obtained by overcoating by dipping without the plating performed in the above example. In this example, since the substrate surface was directly coated with the low melting point water-repellent coating 4 ′, mechanical cutting marks were formed on the substrate surface in order to improve the adhesion between the substrate and the coating. After pretreating the substrate, dipping treatment was performed using a solution having the following composition 5.

<Composition 5> High melting point particles (large PTFE molecular weight or PFA) 10 g Low melting point particles (small PTFE molecular weight or FEP) 2 g Cationic surfactant (1 wt% aqueous solution) 12 g Sodium hydroxide aqueous solution (0.01 M) 100 g Ethanol The 24 g dipping treatment was performed three times using the same solution. After being sufficiently dried, heat treatment was performed at 245 ± 2 ° C. to obtain a film shown in FIG.

According to this embodiment, the plating process can be eliminated, so that the facility can be simplified. As a method for improving the adhesion between the substrate and the coating, other than the above, a chemical or electrochemical method may be used.

Example 5 FIG. 9 is a perspective view of the heat exchanger 5 having the surface treated with the water-repellent coating of the present invention. The heat exchanger 5 has a structure in which a tube 7 penetrates a plurality of aluminum plate fins 6, a refrigerant flows in the tube 7, and the heat of the refrigerant is transferred from the tube 7 to the plate fins 6.
And has a structure for exchanging heat with the air 9 flowing between the plate fins 6. In this example, this heat exchanger was used as a refrigerant evaporator.

The surface of the aluminum plate fin 6 was coated with the water-repellent coating 8 prepared under the conditions of Example 1. In the refrigerant evaporator, heat exchange between the refrigerant flowing in the tube 7 and the air 9 passing between the plate fins 6 lowers the surface temperature of the plate fins 6, and the water content in the air is condensed on the surface 8 of the plate fins. And attach. However, in this embodiment, since the surface of the plate fin is coated with a water-repellent coating, water droplets on the surface of the plate fin fell off from the surface of the plate fin with a small diameter as in the condensation test described above.
For this reason, there are few water droplets that cause frost on the surface, and because the water droplets that are attached have a small area of attachment with the fins, it is difficult for frost to form and the continuous operation time can be greatly extended. Became.

[0070]

EFFECTS OF THE INVENTION According to the present invention, it is possible to obtain a coating film which exhibits excellent water repellency even with respect to water vapor and mist-like water droplets and which has excellent durability.

Further, the heat exchanger using this coating has few water droplets adhering to the fin surface, and the continuous operation time can be greatly extended.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional perspective view of a water-repellent coating showing Example 1 of the present invention.

FIG. 2 is a cross-sectional view of a conventional water-repellent coating.

FIG. 3 is a cross-sectional view of a coating during a coating treatment process according to the first embodiment of the present invention.

FIG. 4 is a cross-sectional view of a coating film during a coating treatment process of Example 2 of the present invention.

FIG. 5 is a cross-sectional view of a water-repellent coating showing Example 2 of the present invention.

FIG. 6 is a cross-sectional view of a coating film during a coating treatment process of Example 3 of the present invention.

FIG. 7 is a cross-sectional view of a water-repellent coating showing Example 3 of the present invention.

FIG. 8 is a cross-sectional view of a water-repellent coating showing Example 4 of the present invention.

FIG. 9 is a perspective view of a heat exchanger showing Embodiment 5 of the present invention.

FIG. 10 is an enlarged cross-sectional view of the surface of a conventional water-repellent coating.

FIG. 11 is a cross-sectional view of a coating film of a conventional example.

[Explanation of symbols]

1 ... Substrate, 2 ... Plating layer, 3 ... High melting point water-repellent particles,
3 '... a film formed by melting high-melting-point water-repellent particles, 4 ...
... low melting point water-repellent particles, 4 '... coating formed by melting low melting point water-repellent particles, 5 ... heat exchanger, 6 ... plate fin, 7 ... tube, 8 ... water-repellent coating, 9 ... Air, 10 ... Water molecule.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location F28F 13/18 A (72) Inventor Hiroshi Kusumoto 502 Kandachicho, Tsuchiura-shi, Ibaraki Hiritsu Seisakusho Co., Ltd. Inside the Mechanical Research Laboratory (72) Inventor Nobuyoshi Watanabe 136 Uguisudai, Nagaokakyo, Kyoto Prefecture (72) Inventor ▲ Zheng ▼ Bao, 391-1 Nishijin Grand Heights, No. 39, 14 Sengen-dori, Senbon-dori, Kyoto City, Kyoto Prefecture

Claims (27)

[Claims] 1. A water-repellent coating which is directly or indirectly arranged on a substrate, wherein water-repellent particles are dispersed so that a part of the coating is embedded in the coating and a part of the coating is projected onto the coating. A water-repellent coating characterized in that the material of the water-repellent coating and the material of the water-repellent particles have different melting points. 2. The water-repellent coating according to claim 1, wherein the water-repellent coating is composed of a substance having a hydrophobic group. 3. The water-repellent coating according to claim 1, wherein the water-repellent coating is composed of a substance having a group having a critical surface tension smaller than the surface tension of water. Coating. 4. The water-repellent coating according to claim 1, wherein the water-repellent coating is composed of a substance having a group having a critical surface tension smaller than the surface tension of water, and the water-repellent particles are made of polytetrafluoroethylene. A water-repellent coating comprising a substance having a group having a critical surface tension equal to or lower than the critical surface tension. 5. The water-repellent coating according to claim 1, wherein the material of the water-repellent coating has a melting point lower than that of the material of the water-repellent particles. 6. A water- and oil-repellent coating is arranged directly or indirectly on a substrate, and water- and oil-repellent particles are dispersed so that a part of the water- and oil-repellent coating is embedded in the coating and a part of the water- and oil-repellent coating is projected on the coating. The water- and oil-repellent coating film, wherein the water- and oil-repellent coating material and the water- and oil-repellent particle material have different melting points. 7. The water- and oil-repellent coating according to claim 6, wherein the water- and oil-repellent coating is made of a fluororesin. 8. The water / oil repellent coating according to claim 6 or 7, wherein the melting point of the material of the water / oil repellent coating is lower than the melting point of the material of the water / oil repellent particles. Oil repellent coating. 9. A group of tubes in which a cooled refrigerant flows,
In a heat exchanger having a group of fins fixed to this tube group and through which air flows, a part of the fin group is buried in the coating on the surface of the fin group, and a part of the fin projects on the coating so that the melting point is the melting point of the coating. A heat exchanger characterized in that a water-repellent film in which different water-repellent particles are dispersed is directly or indirectly formed. 10. The heat exchanger according to claim 9, wherein the water repellent coating film is made of a substance having a hydrophobic group. 11. The heat exchanger according to claim 9, wherein the water-repellent coating is composed of a substance having a group having a critical surface tension smaller than the surface tension of water. vessel. 12. The heat exchanger according to claim 9, wherein the water repellent coating film is composed of a substance having a group having a critical surface tension smaller than the surface tension of water, and the water repellent particles are made of polytetrafluoroethylene. A heat exchanger comprising a substance having a group having a critical surface tension equal to or smaller than the critical surface tension. 13. The heat exchanger according to claim 9, wherein the material of the water-repellent coating has a melting point lower than that of the material of the water-repellent particles. 14. A heat exchanger having a group of tubes in which a cooled refrigerant flows, and a group of fins fixed to the group of tubes and allowing air to flow between them. A heat exchanger characterized by directly or indirectly forming a water- and oil-repellent coating in which water-repellent and oil-repellent particles in which a part is buried and a part of which projects above the coating and whose melting point is different from the melting point of the coating are dispersed. 15. The heat exchanger according to claim 14, wherein
The heat exchanger, wherein the water-repellent and oil-repellent coating is made of a fluororesin. 16. The heat exchanger according to claim 14, wherein the water-repellent and oil-repellent coating has a melting point lower than that of the water- and oil-repellent particles. 17. An air conditioner equipped with the heat exchanger according to any one of claims 9 to 16. 18. A refrigerating machine equipped with the heat exchanger according to any one of claims 9 to 16. 19. A first step of forming a composite film of water-repellent particles having a high melting point on the surface of a substrate by an electric action, and water-repellent particles having a melting point lower than that of the water-repellent particles having a high melting point on the surface of the film. And a third step of heat-treating at a temperature at which the low-melting-point water-repellent particles supplied to the surface of the coating are softened or melted. 20. A first step of forming a coating film, which is composed of two or more kinds of water repellent particles having different melting points, on the surface of a substrate by an electric action, and particles having a low melting point among the two or more kinds of water repellent particles. A second step of heat-treating at a temperature at which is softened or melted, and a method for producing a water-repellent coating film. 21. A first step of forming a coating film, which is composed of two or more kinds of water-repellent particles having different melting points, on the surface of a substrate by an electric action, and a low step of the two or more kinds of water-repellent particles on the surface. A method for producing a water-repellent coating, comprising a second step of supplying water-repellent particles having a melting point and a third step of heat-treating at a temperature at which the low-melting water-repellent particles are softened or melted. 22. The method for producing a water-repellent coating according to claim 19, wherein the method for forming the coating by the electric action is a metal plating method. 23. The method for producing a water-repellent coating according to claim 19, wherein the method for forming the coating by the electrical action uses an electrodeposition coating method. . 24. The method for producing a water-repellent coating according to claim 22, wherein the matrix of the plated coating is nickel or a nickel alloy. 25. A first step of applying two or more types of water-repellent particles having different melting points to a surface of a substrate, and the low-melting-point water-repellent particles of the two or more types of water-repellent particles are softened or melted, And a second step of performing a heat treatment at a temperature equal to or lower than the melting point of the water-repellent particles having a high melting point, and a method for producing a water-repellent film. 26. A method for producing a water-repellent coating according to claim 25, wherein in the first step, the surface of the substrate is coated with the water-repellent particles of two or more types repeatedly a plurality of times. Manufacturing method. 27. The method for producing a water-repellent coating according to claim 19, wherein the two or more types of water-repellent particles having different melting points have different particle sizes. Manufacturing method.