JPH09292197A - Hydrophilic treating agent for heat exchanger, method of treatment and treated aluminum material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable retention of hydrophilic property even after contamination with lubricant oil used in forming by making a hydrophilic resin contain a specified amount of an oil absorbing material having a specified oil absorbing capacity and a specified average particle size. SOLUTION: This hydrophilic treatment agent for a heat exchanger contains an oil absorbing material having an oil absorbing capacity of at least 10ml/100g and an average particle size of not more than 1μm. The oil absorbing material is, preferably, alumina particles and 1 to 20wt.% of alumina particles is preferred to be contained in a hydrophilic coating film. A hydrophilic resin is selected from the group consisting of unsaturated polymerized monomers or unsaturated polymerized high-molecular compound containing carboxyl group and/or hydroxyl group, natural high-molecular compound containing carboxyl group and/or hydroxyl group and its derivative, monomer or aqueous resin containing polyalkylenoxide, aqueous alkyd resin, aqueous polybutadien resin, aqueous polyamid resin, aqueous epoxy resin aqueous polyurethane resin, aqueous phenol resin, aqueous amino resin and the like.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydrophilic treatment agent for heat exchangers, a treatment method and a treated aluminum material, and in particular, hydrophilicity is retained even if lubricating oil is attached to the surface during molding, and it has excellent stain resistance. And a hydrophilic surface treating agent for heat exchangers.

[0002]

2. Description of the Related Art Aluminum and its alloys are lightweight, have excellent workability and thermal conductivity, and are widely used in heat exchangers. With the spread of air conditioning systems, the number of air conditioners for cooling, dehumidification, and cooling / heating is increasing, and fins made of aluminum alloy are generally used for a heat exchange part of these air conditioners.

In this heat exchanger, it is necessary to maximize the surface area of the heat radiating portion and the cooling portion in order to improve the heat radiating property and the cooling property. For this reason, a structure in which the gap between the fins is extremely narrow is adopted. .

During the cooling operation of the air conditioner, the water content in the air tends to adhere to the fin surface as condensed water. In order to prevent this, it is conceivable to make the fin surface water-repellent, but in such a case, the condensed water adheres hemispherically on the fins or exists in a bridge shape between the fins, so that the intake air is smooth. Flow, and the ventilation resistance is increased. Making the fin surface water-repellent in this way lowers the heat exchange efficiency.

Further, usually, aluminum and its alloys are originally excellent in corrosion resistance, but when condensed water stays on the fin surface for a long time, an oxygen concentration battery is formed or pollutants in the atmosphere are gradually deposited and concentrated. Hydration reaction and corrosion reaction are accelerated. This corrosion product, of course, accumulates on the fin surface and impairs the heat exchange properties, but is discharged as white fine powder together with warm air by the blower during the heating operation in winter.

Therefore, in recent years, various surface treatment methods for imparting hydrophilicity, water wettability and corrosion resistance have been proposed.

For example, in the "air-cooling type evaporator" disclosed in Japanese Patent Laid-Open No. 56-59172, the average particle size on the fin surface is about 100.
It is disclosed to coat a synthetic resin in which a powder material which is insoluble in a resin coating liquid at a size of micron (μm) or less is mixed and dispersed. Here, the synthetic resin is a synthetic resin having a hydrophilic amide group, and the powder material is about 10
~ About 200% by volume is used.

According to the synthetic resin film described in the above publication,
The fin surface is roughened by the powder material-containing resin coating, and the water wettability is improved. Further, when aluminum powder is used as the powder material, the heat exchange rate increases and the durability improves.

[0009] Further, in Japanese Unexamined Patent Publication No. 59-229197, "Method of Surface Treatment of Aluminum Heat Exchanger", after forming a corrosion-resistant upper surface treatment film, alumina fine particles alone, or alumina fine particles and silica fine particles, and A method of applying a suspension aqueous solution containing / or tannin to a fin is disclosed. Here, it is described that the alumina fine particles are high molecular weight colloidal alumina having OH groups and the particle diameter thereof is 1 to 100 millimicrons. Further, it is described that the silica fine particles also have a high molecular weight which is insoluble in water and have a particle diameter of 1 to 100 millimicrons.

According to the surface treatment method of the above publication, white rust on the fins can be prevented and the hydrophilicity can be further improved.

Further, in "Hydrophilic fin material for heat exchanger" of JP-A-2-22047, (a) at least one of styrene-modified acrylic-melamine resin, epoxy resin and styrene-methacrylic acid ester resin is used. Fifty
And 100 parts by weight of (b) 60 to 50 parts by weight of activated alumina fine particles, a hydrophilic fin material having a hydrophilic coating film in which the upper part of the activated alumina particles is projected from the coating film surface. Is proposed. Here, it is described that the particle diameter of the activated alumina fine particles is preferably 5 μm or less and about 3 μm on average.

The fin material for the heat exchanger described in the above publication is
Since the coating film itself has excellent hydrophilicity, it is possible to prevent aggregated water from forming water droplets and clogging between the fins.

[0013]

However, when forming an aluminum fin material or the like, usually, a lubricating oil is used for forming. Therefore, the lubricating oil remains on the hydrophilic film such as the aluminum fin material and is contaminated, so that there is a problem that the hydrophilicity is deteriorated.

Therefore, even if a film having excellent hydrophilicity is formed on the surface of the bent fin by using the surface treatment methods of the above-mentioned three publications, the hydrophilicity may be deteriorated by lubricating oil contamination after molding. There was a nature. In this case, as described above, condensed water adheres to the fin surfaces, causing clogging or corrosion between the fins.

The present invention has been made in view of the above-mentioned conventional problems, and an object thereof is a hydrophilic treatment agent for a heat exchanger, which is kept hydrophilic even by contamination of lubricating oil used during molding.
It is to provide a treatment method and a treated aluminum material or aluminum alloy material treated using the above-mentioned hydrophilic treatment agent for heat exchangers.

[0016]

In order to achieve the above-mentioned object, the surface treating agent for a heat exchanger of the present invention has an oil absorption of at least 10 ml / 100 g and an average particle size of 1 μm.
Contains an oil absorbing material that does not exceed

Fine oil-absorbing materials having an average particle size of not more than 1 μm are scattered in the hydrophilic coating on the fin surface, and the oil-absorbing material having a large oil absorption amount of at least 10 ml / 100 g absorbs the lubricating oil remaining on the fin surface. Therefore, the hydrophilicity of the hydrophilic film is ensured even after the molding process.

The oil absorbing material is alumina particles. Since the alumina particles are lipophilic, they have high oil absorbency, a high heat exchange rate, and improved durability.

The treatment method of the present invention is a treatment method of forming a film by treating an aluminum material or an aluminum alloy material with the above-mentioned hydrophilic treatment agent for heat exchangers.

Furthermore, the aluminum material or aluminum alloy material according to the present invention has a film formed by using the above-mentioned hydrophilic treatment agent for heat exchangers.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION The hydrophilizing agent for a heat exchanger according to the present invention contains an oil-absorbing material having an oil absorption of at least 10 ml / 100 g and an average particle size not exceeding 1 μm. Also,
The average particle diameter of the oil absorbing material is preferably 0.05 to 0.5 μm, and the oil absorbing amount is preferably 20 ml / 100 g or more. The treatment agent is a water-solvent type having a hydrophilic resin content of 1 to 30% by weight, preferably 3 to 15% by weight.

When the oil absorption of the oil absorbing material is less than 10 ml / 100 g, the hydrophilicity after molding deteriorates. Further, when the average particle size of the oil absorbing material exceeds 1 μm, the dispersion stability in the treatment liquid decreases. In addition, there is a disadvantage that the oil absorbing material sticks out from the film and the oil absorbing material is removed during the molding process.

Here, the oil absorbing material is at least one kind of particles such as carbon black, talc, silica, ash, clay, powdered silicic acid, aluminum silicate, aluminosilicate, and alumina. Alumina particles are preferable.
Among them, activated alumina, which is amorphous aluminum oxide, has a strong adsorption activity and is particularly excellent as an oil absorbing material.

Further, the oil-absorbing material is contained in the hydrophilic treatment film at 1 to
The content is preferably 20% by weight, and more preferably 5 to 15% by weight. When the content of the oil-absorbing material is less than 1% by weight in the hydrophilic treatment film, the hydrophilicity after molding is lowered, while when it exceeds 20% by weight, moldability is deteriorated as a result of abrasion of molds and dies. Inconvenience occurs.

The amount of the hydrophilization film coated on the surface of the aluminum material or aluminum alloy material using the above-mentioned hydrophilic treatment agent for heat exchanger is preferably 0.1 to ² g / m ^2. . If the coating amount is less than 0.1 g / m ² , the hydrophilicity will decrease. On the other hand, the coating amount is 2 g / m ²
If it exceeds, the cost becomes high and the quality becomes excessive.

Further, the hydrophilic treatment agent for heat exchanger according to the present invention contains a hydrophilic resin. The hydrophilic resin is
(A) unsaturated polymerizable monomer or unsaturated polymerizable aqueous polymer compound containing a carboxyl group and / or a hydroxyl group,
(B) A natural polymer compound having a carboxyl group and / or a hydroxyl group or a derivative thereof, (c) a monomer or an aqueous resin having a polyalkylene oxide, (d) an aqueous alkyd resin, (e) an aqueous maleated oil, ( f) aqueous polyester resin, (g) aqueous polybutadiene resin,
(H) aqueous polyamide resin, (i) aqueous epoxy resin,
It is at least one selected from (j) water-based polyurethane resin, (k) water-based phenol resin, and (l) water-based amino resin.

For example, (a) the unsaturated polymerizable monomer or unsaturated polymerizable aqueous polymer having a carboxyl group and / or a hydroxyl group is poly (meth) acrylic acid,
(Meth) acrylic acid- (meth) acrylic acid ester copolymer, polyvinyl alcohol partially saponified polyvinyl acetate resin, polyvinylpyrrolidone, polymer of (meth) acrylamide derivative such as N-methylol (meth) acrylamide, etc. Is mentioned. Here, the poly (meth) acrylic acid and the (meth) acrylic acid- (meth) acrylic acid ester copolymer contribute to the improvement of alkali resistance and corrosion resistance. In addition, polyvinyl alcohol obtained by partially saponifying polyvinyl acetate resin has an effect of preventing odor and imparting hydrophilicity. In addition, polyvinylpyrrolidone has a function of slightly improving the durability of hydrophilicity. Further, N-methylol (meth) acrylamide has the effect of improving the adhesiveness of the hydrophilic film and improving the water resistance.
In addition, polyvinyl acetate resin, polyvinyl chloride resin, vinyl chloride-vinyl acetate copolymer, styrene- (meth) acrylic copolymer, polymer of (meth) acrylamide, etc. may be used as long as the effects of the present invention are not impaired. You may add.

(B) The natural polymer compound or its derivative containing a carboxyl group and / or a hydroxyl group,
For example, carboxymethyl cellulose (CMC), hydroxyethyl cellulose (HEC), hydroxypropyl cellulose (HPC), methyl cellulose (MC),
Examples thereof include cellulose derivatives such as ethyl cellulose (EC) and ethyl hydroxyethyl cellulose (EHEC), and methyl cellulose derivatives, and gums and polysaccharide derivatives may also be used. In addition, polyglutamic acid (hereinafter "P
Abbreviated as "GA") can also be used. This PGA
Include γ-PGA and α-PGA, and more preferably γ-PGA. Note that γ-PGA is produced by microorganisms (bacteria), and α-PGA is produced by chemical synthesis.

Examples of the (c) polyalkylene oxide-containing monomer or aqueous resin include polyethylene oxide, ethylene oxide-propylene oxide copolymer, ethylene oxide-methylene oxide copolymer, and terminal methylated products thereof. .

(D) The aqueous alkyd resin is glycerin,
It is obtained by condensing a polyol such as pentaerythritol, ethylene glycol, or trimethylolethane with a higher fatty acid obtained from fats and oils, for example, palmitic acid and a dibasic acid such as phthalic anhydride and maleic anhydride.

(F) Aqueous polyester resin is a water-soluble polyester resin obtained by half-esterifying a hydroxyl group in a polyester resin with an anhydride of trimellitic acid and neutralizing the remaining carboxylic acid group with an amine or the like. . Moreover, what made the polyester resin aqueous by making polyethylene glycol react with a polybasic acid is also included.

(G) As the aqueous polybutadiene resin,
It is obtained by polymerizing butadiene using a catalyst, and includes 1,2-bond type and 1,4-bond type, which can be used together. These can be formed into a film by heat, peroxide, sulfur or the like.

(H) As the aqueous polyamide resin, ε
-By ring-opening polymerization of caprolactam, by condensation polymerization of hexamethylenediamine and adipic acid, by condensation polymerization of hexamethylenediamine and sebacic acid,
By polycondensation of 11-aminoundecanoic acid, ω
Examples thereof include those obtained by solubilizing ring-opening polymerization of laurolactam or condensation polymerization of 12-aminododecanoic acid.

Examples of the water-soluble epoxy resin (i) include water-soluble epoxy resins such as di- or polyglycidyl ethers of aliphatic polyhydric alcohols, dicarboxylic acid diglycidyl esters, and epoxy compounds containing a nitrogen-containing heterocycle.
Further, as the water-dispersible epoxy resin, a suitable emulsifier is added to water or a mixed solution of water and an organic solvent to disperse and emulsify the epoxy resin, and the epoxy resin is modified to dissolve or disperse in water. One, specifically, a hydrophilic group is introduced into an epoxy resin, or an anion group such as a carboxyl group or a cation group such as an amino group is introduced, which is neutralized with a hydroxyl group or an acid, and made into an aqueous solution as a polymer electrolyte. There is something I did.

(J) Aqueous polyurethane resins include those prepared by introducing an anion or a cationic group into the molecule to make them aqueous. Further, a bisulfite salt is added to a urethane prepolymer having an isocyanate group as an end group, Some of them are blocked with isocyanate groups and are made water-based due to the hydrophilicity of sulfonate. In addition, there is a polyurethane prepolymer which is forcibly emulsified and dispersed after being blocked with a blocking agent.

(K) Aqueous phenolic resins include phenol, xylenol, p-alkylphenol, p-
Examples thereof include those having a phenolic-OH group such as phenylphenol, chlorophenol, bisphenol-A, phenolsulfonic acid, and resorcin, and a water-soluble polymer obtained by adding and condensing aldehydes such as formalin and furfural. . These are generally classified as phenol-formalin resin, cresol-formalin resin, phenol-furfural resin, resorcin resin and the like. The water-soluble phenol resin contributes to the improvement of film-forming property as a crosslinking agent.

Examples of the (l) aqueous amino resin include, for example:
Examples include water-soluble melamine resins such as n-butylated melamine resins and isobutylated melamine resins, and urea resins. These resins are usually obtained by subjecting an amino compound such as melamine or benzoguanamine to an addition reaction or an addition condensation reaction of an aldehyde such as formaldehyde or paraformaldehyde with an ether compound with a monohydric alcohol having 1 to 4 carbon atoms. . The amino resin forms a cross-link between the resins and contributes to the improvement of the film-forming property. Specific examples of the melamine resin include alkoxymethylmelamine resins having an alkoxy group such as a methoxy group, an ethoxy group, an n-butoxy group, and an i-butoxy group.

The hydrophilizing agent for heat exchangers of the present invention is applied to an aluminum material or an aluminum alloy material which has been subjected to anticorrosion pretreatment by the following treatment method. And
The applied aluminum material is dried at around 200 ° C., and a hydrophilic treatment coating containing an oil absorbing material is formed on the surface of the aluminum material or aluminum alloy material.

In the anticorrosive pretreatment, the aluminum material or aluminum alloy material is first degreased. Next, chemical conversion treatment, which is rust prevention treatment, is performed. The degreasing treatment may be either solvent degreasing with trichloroethylene, perchlorethylene, gasoline, normal hexane or the like, or alkaline degreasing with an alkaline solution of sodium hydroxide, sodium carbonate, sodium silicate, sodium phosphate or the like. Examples of the subsequent chemical conversion treatment include phosphoric acid chromate treatment, coating type chromate treatment, phenol or urethane resin primer treatment, non-chromate treatment and the like.

Usually, the anticorrosive pretreatment is carried out by a combination of degreasing treatment and any one of the above chemical conversion treatments.

In the hydrophilic surface treatment method, first, an aqueous solution of hydrophilic surface treatment is applied to the aluminum or aluminum alloy which has been subjected to the above-mentioned anticorrosion pretreatment through a chemical conversion treatment layer. Examples of the coating method include a roll coating method, a bar coating method, a dipping method, a spraying method, and a brush coating method, which may be precoating or postcoating. For example, in the case of the roll coating method, the hydrophilic film can be obtained by drying at a temperature of 150 to 270 ° C. for 10 seconds to 1 minute after coating. If the baking temperature is below 150 ° C,
On the other hand, the film does not form a film, and the hydrophilicity above 270 ° C is insufficient.

Further, the hydrophilizing agent for heat exchangers of the present invention may be added with a necessary amount of the following depending on the function to be added thereto.

For example, a surfactant may be added in order to improve workability such as stability, foaming property and coating property of the treatment liquid. The surfactant is appropriately selected from nonionic, anionic, cationic, and amphoteric surfactants depending on the desired function.

When coloring is applied, pigments and / or dyes may be added. The pigment may be an inorganic pigment or an organic pigment.

When imparting antifungal properties and antibacterial properties, antifungal agents and antibacterial agents may be added.

The treated aluminum material or aluminum alloy material of the present invention can be obtained by the above treatment method using the above-mentioned hydrophilic treatment agent for heat exchangers.

Further, another preferred embodiment of the present invention will be shown below.

1. In the hydrophilic treatment agent for a heat exchanger according to the present invention, the oil absorbing material is at least one kind of particles such as carbon black, talc, silica, ash, clay, powdered silicic acid, aluminum silicate, aluminosilicate, and activated alumina.

2. The oil absorbing material is activated alumina particles.

3. The oil absorbing material has 1 in the hydrophilic treatment film.
˜20% by weight.

4. The coating amount of the hydrophilic coating formed on the surface of the aluminum material or the aluminum alloy material using the above-mentioned hydrophilic treatment agent for heat exchanger is 0.1 to ² g / m ² .

5. The hydrophilic treatment agent for heat exchangers according to the present invention contains a hydrophilic resin.

6. The hydrophilic resin is (a) an unsaturated polymerizable monomer or an unsaturated polymerizable aqueous polymer compound containing a carboxyl group and / or a hydroxyl group, and (b) a natural polymer compound containing a carboxyl group and / or a hydroxyl group. Or a derivative thereof, (c) a monomer or aqueous resin having a polyalkylene oxide, (d) an aqueous alkyd resin,
(E) aqueous maleated oil, (f) aqueous polyester resin, (g) aqueous polybutadiene resin, (h) aqueous polyamide resin, (i) aqueous epoxy resin, (j) aqueous polyurethane resin, (k) aqueous phenol resin, (L) At least one selected from aqueous amino resins.

[0054]

EXAMPLES Next, the present invention will be specifically described with reference to Examples and Comparative Examples. The present invention is not limited to these examples.

Examples 1 to 12 and Comparative Examples 1 to 8 The following hydrophilic surface treatment method and film performance evaluation test were conducted in common with Examples and Comparative Examples.

Hydrophilic Surface Treatment Method The aluminum plate was degreased and then subjected to chemical conversion treatment, if necessary, and a hydrophilic surface treatment aqueous solution (resin concentration: 5% by weight) having the composition of Examples and Comparative Examples shown in Table 1 was used. , Bar Coater # 1
No. 0 and then dried at 200 ° C. for 20 seconds to form a hydrophilic film. The following tests were performed on the obtained film. The degreasing was performed on an aluminum plate using "Surf Cleaner 322N-8 (trade name of Nippon Paint Co., Ltd.," Surf Cleaner "is a registered trademark of Nippon Paint Co., Ltd.).

For the phosphoric acid chromate treatment as the chemical conversion treatment, "Alsurf 407/47" (trade name of Nippon Paint Co., Ltd., "Alsurf" is a registered trademark of Nippon Paint Co., Ltd.) was used. The coating was performed so that the coating amount (as Cr amount) was 20 mg / m ² .

Performance evaluation test (1) Water contact angle measurement test: A sample of each aluminum plate subjected to hydrophilic treatment was dipped in a lubricating oil, Proformer 7K18B (manufactured by Showa Shell Sekiyu KK) for 1 minute, and allowed to stand for 30 minutes for 150 minutes.
Dry at 5 ° C for 5 minutes. 8 after putting it in running water for 8 hours
The process of drying at 0 ° C. for 16 hours was set as one cycle, and this cycle was repeated 5 times (heat cycle), and then the contact angle with water droplets was measured. This test evaluates the hydrophilic durability, and the smaller the contact angle, the better the hydrophilic durability. Table 2 shows the evaluation results. When the water contact angle is less than 30 °, the treated aluminum material or the like has desired hydrophilicity and can be used without any problem.

<Measurement method> The aluminum plate sample subjected to the above thermal cycle was laid horizontal, 5 μl of water was dropped, and FACE automatic contact angle meter (CA-Z: manufactured by Kyowa Interface Science Co., Ltd.) was used: The contact angle was measured at room temperature at 30 seconds after dropping).

<Evaluation> ◎: Contact angle is less than 20 ° ○: Contact angle is 20 ° or more and less than 30 ° ×: Contact angle is 30 ° or more (2) Sliding property (workability) of coating base coating film: hydrophilic A sample of the treated aluminum plate is "HEIDON-14"
Type tester, load 50 g, stylus speed 300 mm / min.
The dynamic friction coefficient was obtained from. Table 2 shows the evaluation results. If the coefficient of kinetic friction is less than 0.2, normal processing can be performed without problems.

<Evaluation> ◎: Friction coefficient is less than 0.1 ○: Friction coefficient is 0.1 or more and less than 0.2 ×: Friction coefficient is 0.2 or more

[Table 1] Note) PVA: Polyvinyl alcohol (weight average molecular weight M
w; 20,000) PEO: polyethylene oxide (Mw; 500,00)
0) PAA: polyacrylic acid (Mw; 1,000,000) PGA: polyglutamic acid (Mw; 300,000) CMC: carboxymethyl cellulose (Mw; 20,0)
00) Oil absorbing material A: activated alumina (average particle size; 0.1μ
m, oil absorption amount 90 ml / 100 g) Oil absorption material B: activated alumina (average particle diameter; 0.7 μ)
m, oil absorption amount 70 ml / 100 g) Oil absorption material C: activated alumina (average particle size: 1.5 μ)
m, oil absorption amount 40 ml / 100 g) Oil absorption material D: silica (average particle diameter; 0.3 μ)
m, oil absorption amount 50 ml / 100 g) Oil absorption material E: carbon black (average particle diameter; 0.08 μ)
m, oil absorption 30ml / 100g)

[Table 2] From these results, it was found that the hydrophilic treatment agent for a heat exchanger of the present invention improves hydrophilicity (water wettability) and workability.

[0062]

As described above, according to the hydrophilizing agent for heat exchangers and the treating method of the present invention, the fine oil-absorbing material having an average particle size of not more than 1 μm is scattered on the hydrophilizing film on the fin surface. In addition, since the oil absorbing material having a large oil absorption amount of at least 10 ml / 100 g absorbs the lubricating oil remaining on the fin surface, the hydrophilicity of the hydrophilic film is secured even after the molding process. Furthermore, when the oil absorbing material is alumina particles, since the alumina particles are lipophilic, the oil absorbing property is high,
Further, the heat exchange rate is increased and the durability is improved.

Among them, activated alumina, which is amorphous aluminum oxide, has a strong adsorption activity and is particularly excellent as an oil absorbing material.

Claims (4)

[Claims] 1. Oil absorption of at least 10 ml / 100 g
The hydrophilizing agent for heat exchangers as described above, which comprises 1 to 20% by weight of the oil absorbing material having an average particle size not exceeding 1 μm with respect to the hydrophilic resin. 2. The hydrophilizing agent for heat exchangers according to claim 1, wherein the oil absorbing material is alumina particles. 3. A treatment method comprising forming a hydrophilic resin film by treating an aluminum material or an aluminum alloy material with the hydrophilic treatment agent for a heat exchanger according to claim 1. 4. An aluminum material or an aluminum alloy material, wherein a hydrophilic resin film is formed by using the hydrophilizing agent for a heat exchanger according to claim 1.