JPH10197192A - Fin for heat exchanger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fin for a heat exchanger having a surface for maintaining water repellency for a long period. SOLUTION: In the fin for a heat exchanger, a surface of a base material is formed with a surface layer 2 containing photocatalytic particles, water repellent silicone and substance for preventing hydrophilizing of the silicone due to photo-exciting of the photocatalyst, or a layer containing the particles and the silicone is formed on the surface of the base material. Further, the substance for preventing the hydrophilizing of the silicone due to photo-exciting of the photocatalyst is fixed to at least part of the surface of the layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat exchanger incorporated in an air conditioner for cooling and heating.

[0002]

2. Description of the Related Art A general heat exchanger has a structure in which a plurality of aluminum plate fins having a high thermal conductivity are attached to a pipe through which a refrigerant or a heat medium flows to increase the efficiency of heat exchange. The greater the number of fins, the higher the efficiency. However, when the number of fins increases, the distance between adjacent fins becomes narrower, and moisture in the atmosphere adheres to the fins. Will be held by the Then, the water droplets become the resistance of the air flowing between the fins, and the heat exchange efficiency is rather reduced.

[0003]

Therefore, a fin for a heat exchanger to which water droplets are unlikely to adhere is desired.

[0004] As a method of preventing the adhesion of water droplets, it is known that it is better to impart water repellency to the surface of a substrate. As one of the methods, there is a method of forming a surface layer made of a water-repellent silicone on a substrate surface. However, with this structure, the contact angle with water is reduced to about 70 ° due to the adhesion of dirt over time, and the effect of water repellency is not maintained. Therefore, as another method for solving the above-mentioned problem, there is a method of forming a surface layer comprising a photocatalyst and a water-repellent silicone on the surface of a substrate. According to this method, it is possible to decompose the adhered dirt over time based on the oxidative decomposability of the photocatalyst. However, in this configuration, when exposed to sunlight outdoors, the silicone is hydrophilized by photoexcitation of the photocatalyst, so that the water repellency of the surface cannot be maintained. In view of the above circumstances, an object of the present invention is to provide a heat exchanger fin capable of maintaining surface water repellency for a long period of time, and to provide a heat exchanger that does not cause a decrease in heat exchange efficiency over a long period of time. .

[0005]

According to the present invention, in order to solve the above-mentioned problems, photocatalytic particles, water-repellent silicone, and hydrophilicity of the water-repellent silicone by photoexcitation of the photocatalyst are provided on a substrate surface. Or a layer containing photocatalyst particles and a water-repellent silicone is formed on the surface of the base material, and is further formed on at least a part of the surface of the layer. The present invention provides a fin for a heat exchanger, on which a substance for preventing the water-repellent silicone from becoming hydrophilic by photoexcitation of the photocatalyst is fixed. Preventing the silicon from becoming hydrophilic by photoexcitation of the photocatalyst by making the surface layer contain a substance such as cobalt or a cobalt compound for preventing the photocatalyst from becoming hydrophilic by photoexcitation. Can be. In addition, since the photocatalyst is contained, it is possible to decompose the dirt adhering with time based on the oxidative decomposability of the photocatalyst.
Therefore, the water repellency of the surface can be maintained permanently,
As a result, a state in which water droplets are held between the fins and resistance to the refrigerant and the heat medium does not occur does not occur, and a heat exchanger in which the heat exchange efficiency does not decrease for a long time can be provided.

[0006]

1 and 2 show one embodiment of the heat exchanger of the present invention. FIG. 1 is a perspective view, and FIG. 2 is an enlarged sectional view of a main part. In the heat exchanger, a number of fins 2 are attached to a pipe through which a heat medium flows so as to face each other. The fin 2 is made of an aluminum plate, and a surface layer 3 is formed on a surface of the fin 2. In one embodiment, as shown in FIG. 3, a surface layer containing photocatalyst particles, silicon, and a substance for preventing photocatalyst such as cobalt or a cobalt compound from becoming hydrophilic by photoexcitation is formed. . In another embodiment of the present invention, as shown in FIG. 4, a layer containing photocatalyst particles and a water-repellent silicone is formed on the surface of the fin 2, and at least a part of the surface of the layer contains cobalt. Alternatively, a substance for preventing hydrophilicity due to photoexcitation of a photocatalyst of a water-repellent silicone such as a cobalt compound is fixed.

A photocatalyst has an energy greater than the energy gap between the conduction band and the valence band of the crystal.
A substance capable of generating conduction electrons and holes by excitation of electrons in the valence band (photoexcitation) when irradiated with light (excitation light) having a short wavelength (excitation light).
Oxides such as zeta-type titanium oxide, zinc oxide, tin oxide, ferric oxide, bismuth trioxide, tungsten trioxide and strontium titanate can be suitably used. Illumination such as a fluorescent lamp, an incandescent lamp, a metal halide lamp, a mercury lamp, a xenon lamp, and a germicidal lamp can be used as a light source used for photoexcitation of the photocatalyst.

The silicone has an average composition formula R _p SiO _{(4-p) / 2} (where R is a functional group comprising one or more monovalent organic groups, or a monovalent organic group) A resin represented by the following formula: X is an alkoxy group or a halogen atom, and p is a number satisfying 0 <p <2. Is available.

As the cobalt compound, cobalt alloy, cobalt oxide, cobalt chloride, cobalt sulfate, cobalt iodide, cobalt bromide, cobalt acetate, cobalt chlorate, cobalt nitrate and the like can be suitably used.

The thickness of the surface layer is preferably set to 0.4 μm or less. Then, cloudiness due to irregular reflection of light can be prevented, and the surface layer becomes substantially transparent. Further, it is more preferable that the thickness of the surface layer be 0.2 μm or less. Then, it is possible to prevent the surface layer from being colored by light interference. Also, the thinner the surface layer, the better its transparency. Further, when the film thickness is reduced, the wear resistance of the surface layer is improved.

A metal such as Ag, Cu and Zn can be added to the surface layer. The surface layer to which the metal is added can kill bacteria and fungi attached to the surface even in a dark place.

Pt, Pd, Ru, Rh, I
A platinum group metal such as r or Os can be added.
The surface layer to which the metal is added can enhance the redox activity of the photocatalyst, and can improve the decomposability of organic contaminants and the decomposability of harmful gases and odors.

Next, a surface layer containing photocatalyst particles, water-repellent silicone, and a substance for preventing the water-repellent silicone from becoming hydrophilic by photoexcitation of the photocatalyst is formed on the surface of the substrate. The method of manufacturing the water-repellent member described above will be described. The production method in this case is basically based on applying a coating composition on the surface of a substrate and curing the coating composition.

Here, the coating composition contains a precursor of silicon as an essential component of a substance for preventing photocatalytic particles, cobalt or a cobalt compound or the like from becoming hydrophilic by photoexcitation of a photocatalyst. Solvents such as ethanol and propanol, catalysts that promote hydrolysis of silicone precursors such as hydrochloric acid, nitric acid, sulfuric acid, acetic acid and maleic acid, and basic compounds such as tributylamine and hexylamine Silicon compounds such as acidic compounds such as aluminum, aluminum triisopropoxide and tetraisopropyl titanate;
And a surfactant for improving the dispersibility of the coating liquid such as a silane coupling agent.

As cobalt or a cobalt compound, a water-soluble cobalt compound is preferably used. As the water-soluble cobalt compound, for example, cobalt chloride, cobalt sulfate, cobalt iodide, cobalt bromide, cobalt acetate, cobalt chlorate, cobalt nitrate and the like can be suitably used.

[0016] Here silicone - The precursor emissions in the average composition formula _{R p SiX q O (4-} pq) / 2 ( wherein, R consists of one or more organic groups monovalent functional X or a functional group comprising two or more selected from a monovalent organic group and a hydrogen group, X is an alkoxy group or a halogen atom, and p and q are 0 <p <2, 0 <
a film-forming element composed of a siloxane represented by the following formula: q <4) or a general formula R _p SiX _4-p (where R is one or more monovalent organic groups) Wherein X is an alkoxy group or a halogen atom, and p is 1 or 2. A film-forming element comprising a hydrolyzable silane derivative to be
Can be suitably used.

Here, as the coating film forming element comprising the hydrolyzable silane derivative, methyltrimethoxysilane,
Methyltriethoxysilane, methyltripropoxysilane, methyltributoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, ethyltripropoxysilane, ethyltributoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, phenyltripropoxysilane, Phenyltributoxysilane,
Dimethyldimethoxysilane, dimethyldiethoxysilane, dimethyldipropoxysilane, dimethyldibutoxysilane, diethyldimethoxysilane, diethyldiethoxysilane, diethyldipropoxysilane, diethyldibutoxysilane, phenylmethyldimethoxysilane, phenylmethyldiethoxysilane, phenyl Methyldipropoxysilane, phenylmethyldibutoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, n-propyltripropoxysilane, n-propyltributoxysilane, γ-glycoxydoxypropyltrimethoxysilane, γ -Acryloxypropyltrimethoxysilane and the like can be suitably used.

The film-forming element composed of the siloxane includes partial hydrolysis and dehydration-condensation polymerization of the hydrolyzable silane derivative, or partial hydrolyzate of the hydrolyzable silane derivative, tetramethoxysilane, tetramethoxysilane, It can be produced by dehydration polycondensation with a partial hydrolyzate such as ethoxysilane, tetrapropoxysilane, tetrabutoxysilane, diethoxydimethoxysilane and the like.

The coating method of the coating composition includes spray coating, dip coating, flow coating, spin coating, roll coating, brush coating, and sponge. A method such as coating can be suitably used. As a curing method, it can be carried out by polymerizing by heat treatment, standing at room temperature, ultraviolet irradiation, or the like.

Next, a layer containing photocatalyst particles and a water-repellent silicone is formed on the surface of the base material, and at least a part of the surface of the layer is formed by photoexcitation of the photocatalyst by the water-repellent silicone. A method for manufacturing a water-repellent member to which a substance for preventing hydrophilicity is fixed will be described. The production method in this case is basically based on the photo-excitation of a photocatalyst such as cobalt or a cobalt compound after coating and curing a coating composition containing photocatalyst particles and a water-repellent silicone precursor. By applying a solution containing a substance for preventing hydrophilization and fixing the solution to the surface.

Here, the coating composition has photocatalyst particles and a precursor of a water-repellent silicone as essential components, and in addition, a solvent such as water, ethanol, propanol, hydrochloric acid, nitric acid, and the like. Catalysts that promote the hydrolysis of silica precursors such as sulfuric acid, acetic acid and maleic acid, basic compounds such as tributylamine and hexylamine, and acidic compounds such as aluminum triisopropoxide and tetraisopropyl titanate Such as a catalyst for curing a precursor of silica,
A surfactant such as a silane coupling agent for improving the dispersibility of the coating liquid may be added.

[0022] Here silicone - The precursor emissions in the average composition formula _{R p SiX q O (4-} pq) / 2 ( wherein, R consists of one or more organic groups monovalent functional X or a functional group comprising two or more selected from a monovalent organic group and a hydrogen group, X is an alkoxy group or a halogen atom, and p and q are 0 <p <2, 0 <
a film-forming element composed of a siloxane represented by the following formula: q <4) or a general formula R _p SiX _4-p (where R is one or more monovalent organic groups) Wherein X is an alkoxy group or a halogen atom, and p is 1 or 2. A film-forming element comprising a hydrolyzable silane derivative to be
Can be suitably used.

Here, as the coating film forming element comprising the hydrolyzable silane derivative, methyltrimethoxysilane,
Methyltriethoxysilane, methyltripropoxysilane, methyltributoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, ethyltripropoxysilane, ethyltributoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, phenyltripropoxysilane, Phenyltributoxysilane,
Dimethyldimethoxysilane, dimethyldiethoxysilane, dimethyldipropoxysilane, dimethyldibutoxysilane, diethyldimethoxysilane, diethyldiethoxysilane, diethyldipropoxysilane, diethyldibutoxysilane, phenylmethyldimethoxysilane, phenylmethyldiethoxysilane, phenyl Methyldipropoxysilane, phenylmethyldibutoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, n-propyltripropoxysilane, n-propyltributoxysilane, γ-glycoxydoxypropyltrimethoxysilane, γ -Acryloxypropyltrimethoxysilane and the like can be suitably used.

The film-forming element composed of the siloxane includes partial hydrolysis and dehydration-condensation polymerization of the hydrolyzable silane derivative, or a partial hydrolyzate of the hydrolyzable silane derivative, tetramethoxysilane, tetramethoxysilane and tetramethoxysilane. It can be produced by dehydration polycondensation with a partial hydrolyzate such as ethoxysilane, tetrapropoxysilane, tetrabutoxysilane, diethoxydimethoxysilane and the like.

The coating method of the above coating composition includes spray coating, dip coating, flow coating, spin coating, roll coating, brush coating, and sponge. A method such as coating can be suitably used. As a curing method, it can be carried out by polymerizing by heat treatment, standing at room temperature, ultraviolet irradiation, or the like.

The method of applying a solution containing a substance for preventing the photocatalyst such as cobalt or a cobalt compound from being hydrophilized by photoexcitation and fixing it on the surface includes, for example, cobalt chloride, cobalt sulfate, cobalt iodide, bromide, and the like. cobalt,
Spray coating method, dip coating method, flow coating method, spin coating method, roll coating method, brushing water-soluble cobalt compounds such as cobalt acetate, cobalt chlorate and cobalt nitrate Coating, sponge coating, etc., photoreduction, heat treatment, alcohol
This is performed by fixing by a method such as reduction using a sacrificial oxidizing agent such as toluene.

[0027]

【Example】

Reference example. Anatase type titanium oxide sol (Nissan Chemical, TA
-15, nitric acid peptized type, pH = 1), silica sol (Nippon Synthetic Rubber, Glasca A solution, pH = 4), methyltrimethoxysilane (Nippon Synthetic Rubber, Glasca B solution) and ethanol are mixed. The coating liquid obtained by stirring for 2 to 3 hours was applied on a 5 × 10 cm square glazed tile base material (TOTOKIKI, AB02E11) by spray coating.
A heat treatment was performed at 200 ° C. for 15 minutes to obtain a # 1 sample having a surface layer formed of 11 parts by weight of anatase type titanium oxide particles, 6 parts by weight of silica, and 5 parts by weight of silicone. The contact angle of the # 1 sample with water was 92 °. Here, the contact angle with water was evaluated using a contact angle measuring device (Kyowa Interface Science, CA-X150) by the contact angle with water 30 seconds after a water droplet was dropped from the micro syringe. Next, the surface of the # 1 sample was irradiated for one day with an ultraviolet illuminance of 0.3 mW / cm ² using an ultraviolet light source (Sankyo Electric, Black Light Blue (BLB) fluorescent lamp) to obtain a # 2 sample. As a result, the contact angle with water of the # 2 sample was hydrophilized to 0 °. Next, # 1 sample and #
One sample was irradiated with a mercury lamp at an ultraviolet irradiance of 22.8 mW / cm ² for 2 hours, and the surface of each of the # 3 samples obtained was subjected to Raman spectroscopic analysis. As a result, a peak of methyl group observed on the surface of sample # 1 was not observed in sample # 3, but a peak of hydroxyl group was observed instead. From the above,
It can be seen that the organic group bonded to the silicon atom in the silicon molecule on the surface of the film by the photoexcitation of the anatase type titanium oxide which is a photocatalyst is replaced by a hydroxyl group and becomes hydrophilic.

Embodiment 1 FIG. Anatase type titanium oxide sol (Nissan Chemical, TA-15, peptized nitrate, pH = 1),
Silica sol (Nippon Synthetic Rubber, Glasca A solution, pH = 4)
And methyltrimethoxysilane (Nippon Synthetic Rubber, Glasca B solution), cobalt chloride hexahydrate, and ethanol, and stirred for 2-3 hours. -Applied on an aluminum substrate coated with silicone by a coating method, and heat-treated at 150 ° C for 15 minutes to obtain 11 parts by weight of anatase type titanium oxide particles, 6 parts by weight of silica, and 5 parts by weight of silicone. And a # 4 sample having a surface layer composed of 0.2 parts by weight of cobalt was obtained. The contact angle of the # 4 sample with water was 97 °. Here, the contact angle with water was evaluated using a contact angle measuring device (Kyowa Interface Science, CA-X150) by the contact angle with water 30 seconds after a water droplet was dropped from the micro syringe. Next, an ultraviolet light source (Sankyo Electric, Black Light Blue- (BLB) fluorescent lamp) was placed on the surface of the # 4 sample.
Was used for 1 day at an ultraviolet illuminance of 0.3 mW / cm ² to obtain a # 5 sample. As a result, the contact angle of the # 5 sample with water was still 95 °, maintaining water repellency. Therefore, it can be understood from the above that the hydrophilicity of the silicon on the surface of the coating film due to the photoexcitation of the anatase type titanium oxide as a photocatalyst is inhibited by cobalt. This is considered because the substitution of the hydroxyl group for the organic group bonded to the silicon atom in the silicon molecule on the surface of the coating is inhibited by cobalt. Further, when the # 5 sample was tilted, the water droplets fell while rolling.

Embodiment 2 FIG. Anatase type titanium oxide sol (Nissan Chemical, TA-15, peptized nitrate, pH = 1),
Silica sol (Nippon Synthetic Rubber, Glasca A solution, pH = 4)
And methyltrimethoxysilane (Nippon Synthetic Rubber, Glasca B solution) and ethanol were mixed, and the mixture was stirred for 2 to 3 hours to obtain a silicone coating by spray coating. 15 on the aluminum substrate coated with
Heat treatment was performed at 0 ° C. for 15 minutes to form a surface layer comprising 11 parts by weight of anatase type titanium oxide particles, 6 parts by weight of silica, and 5 parts by weight of silicone. Further, 0.3 g of an aqueous cobalt chloride hexahydrate solution having a cobalt metal concentration of 50 μmol / g was applied thereon, and the ultraviolet illuminance was set to 0.4 using an ultraviolet light source (Sankyo Electric, Black Light Blue (BLB) fluorescent lamp).
A # 6 sample was obtained by irradiating ultraviolet rays of mW / cm ² for 10 minutes to fix cobalt on the substrate. The contact angle of the # 6 sample with water was 96 °. Here, the contact angle with water was evaluated using a contact angle measuring device (Kyowa Interface Science, CA-X150) by the contact angle with water 30 seconds after a water droplet was dropped from the micro syringe. Next, the surface of the # 6 sample was irradiated with ultraviolet light of 0.3 mW / cm ² for one day using an ultraviolet light source (Sankyo Electric, Black Light Blue (BLB) fluorescent lamp) to obtain a # 7 sample. As a result, the contact angle of the # 7 sample with water was still 9
The water repellency was maintained at 4 °. Therefore, it can be understood from the above that the hydrophilicity of the silicon on the surface of the coating film due to the photoexcitation of the anatase type titanium oxide as a photocatalyst is inhibited by cobalt. This is considered because the substitution of the hydroxyl group for the organic group bonded to the silicon atom in the silicon molecule on the surface of the coating is inhibited by cobalt. Also,#
When the seven samples were tilted, the water droplets fell while rolling.

[0030]

According to the present invention, in a fin for a heat exchanger, photocatalyst particles, a water-repellent silicone,
A surface layer containing a substance for preventing the water-repellent silicone from becoming hydrophilic by photoexcitation of the photocatalyst is formed, or photocatalyst particles and a water-repellent silicone are formed on the surface of the base material. Is formed, and a material for preventing hydrophilicity of the water-repellent silicone by photoexcitation of the photocatalyst is fixed to at least a part of the surface of the layer. The surface can maintain the water repellency for a long period of time, so that it is possible to provide a heat exchanger in which the heat exchange efficiency does not decrease for a long period of time.

[Brief description of the drawings]

FIG. 1 is a perspective view of an embodiment of a heat exchanger of the present invention.

FIG. 2 is an enlarged sectional view of a main part of an embodiment of the heat exchanger of the present invention.

FIG. 3 is a diagram showing a surface structure of a heat exchanger fin of the present invention.

FIG. 4 is a diagram showing another surface structure of the heat exchanger fin of the present invention.

[Explanation of symbols]

 1: pipe 2: fin 3: surface layer 4: light source

Claims (3)

[Claims] 1. A surface layer containing photocatalyst particles, water-repellent silicone, and a substance for preventing the water-repellent silicone from becoming hydrophilic by photoexcitation of the photocatalyst is formed on the surface of a substrate. A fin for a heat exchanger. 2. A layer containing photocatalyst particles and a water-repellent silicone is formed on the surface of a base material, and at least a part of the surface of the layer is made hydrophilic by the photoexcitation of the photocatalyst of the water-repellent silicone. A fin for a heat exchanger, wherein a substance for preventing fining is fixed. 3. The heat exchanger fin according to claim 1, wherein the substance for preventing the photocatalyst from becoming hydrophilic by photoexcitation is cobalt or a cobalt compound.