JPS63249643A - Fin material for heat exchanger - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a fin material for a heat exchanger.

In this specification, aluminum includes aluminum and aluminum alloys.

2. Description of the Related Art In general, in heat exchangers, particularly in evaporators of air conditioners, the surface temperature of the fins is higher than the dew point of the atmosphere, so water droplets adhere to the surfaces of the fins.

Due to the adhesion of such water droplets, ventilation resistance increases, the air volume decreases, and heat exchange efficiency decreases. This becomes especially noticeable when the fin pitch is narrowed to improve the performance and downsize the heat exchanger.

Heat exchange efficiency is greatly influenced by the ability of water to get wet on the fin surface, and if the fin surface has good wettability, attached water will be less likely to become water droplets, which will reduce ventilation resistance and increase air volume. Heat exchange efficiency increases. In order to improve the wettability of the fin surface, a method has been proposed in which a film of water glass (alkali silicate) is formed on both surfaces of an aluminum fin (Japanese Patent Publication No. 53-48177).
(see publication). However, according to this conventional method, since the water glass film is hard, abrasion scratches occur on the die punch especially during ironing and burring of aluminum fins, and the punch with such scratches causes When the next fin is molded, the inner surface of the molded part of the fin may be scratched, or cracks may occur at the tip of the molded part, causing cracks in the fin when it is connected to the heat exchange tube. There was a problem.

Purpose of the Invention The present invention has been made in view of the above points, and includes a first hydrophilic film having excellent hydrophilicity and durability on one side.
By forming a soft hydrophilic second film on the other surface, which is slightly less hydrophilic than this, it is possible to exhibit excellent hydrophilicity and its sustainability, and the wear of the mold during fin molding is extremely low. It is an object of the present invention to provide a fin material for a heat exchanger that has less damage and does not cause scratches or cracks on the fins after molding.

Structure of the Invention In order to solve the above-mentioned problems, the present invention comprises forming a corrosion-resistant film made of a water-soluble synthetic resin on both sides of an aluminum plate, and coating a hydrophilic inorganic material and a carbonyl group on the surface of one of the corrosion-resistant films. A hydrophilic first film is formed, which is made of a low-molecular organic compound having a carbonyl group, and a water-soluble organic polymer compound, or a water-soluble organic polymer compound and a low-molecular organic compound having a carbonyl group, is formed on the surface of the other corrosion-resistant film. The gist is a heat exchanger fin material on which a hydrophilic second film is formed.

In the above, the aluminum plate can be treated and processed in the form of a flat plate having the required length, but it is especially preferable to continuously process and process it in the form of a coil material. As the water-soluble synthetic resin, at least one of water-soluble acrylic resins, water-soluble polyurethane resins and copolymers thereof, water-soluble alkyd resins, water-soluble polyester resins, and water-soluble amino resins is used. Here, the amino resin refers to a resin obtained by a condensation reaction between a compound containing an amino group and an aldehyde, and specifically includes melamine resin, urea resin, aniline amino resin, and the like.

The water-soluble synthetic resins include those that completely dissolve in water to form a solution and those that partially dissolve in water to form a dispersed solution.

The treatment for forming a corrosion-resistant film made of a water-soluble synthetic resin on the surface of an aluminum plate is carried out by dipping, spraying, or coating using an aqueous solution containing the water-soluble synthetic resin. The film thus formed has hydrophilicity and excellent corrosion resistance.

The thickness of the corrosion-resistant film made of such a water-soluble synthetic resin is preferably, for example, 1 to 50 μm. If the thickness of the corrosion-resistant film is less than 1 μm, there will be a problem in corrosion resistance, and if it exceeds 50 μm, the heat conduction of the aluminum plate will be inhibited and the formability will deteriorate.

Examples of the hydrophilic inorganic material (A) contained in the first hydrophilic film formed on the surface of one of the corrosion-resistant films on both sides of the aluminum plate include silicic acid, silicate, silica sol, and alumina sol. It will be done. Furthermore, it is necessary to use a silicate having a ratio of 5IO2/M20 (in the formula, M means an alkali metal such as lithium, sodium, potassium, etc.) of 1 or more. In particular, it is preferable to use an alkali silicate having a Sl 02 /M20 of 2 to 5. Here, if the ratio of 5102/M20 is less than 1, S10□
Since there is little oxidation, the corrosion effect of aluminum by alkaline components increases.

Further, the low-molecular organic compound (B) is a low-molecular organic compound having a carbonyl group (>C-0) in the molecule,
This stabilizes the film made of the hydrophilic inorganic material (A), further improves hydrophilicity, and gives flexibility to the film.

Specific examples of such low-molecular organic compounds (B) include aldehydes, esters, and amides.

Here, as the aldehydes, formaldehyde, acetaldehyde, glyoxal, malondialdehyde, succindialdehyde, glutardialdehyde, furfuraldialdehyde, etc. are used.

Examples of esters include fatty acid esters of monohydric alcohols such as methyl formate, ethyl acetate, methyl acetate, butyl acetate, amyl acetate, and methyl propionate, as well as ethylene glycol diacetate, glycerine triacetate, and ethylene glycol dipropionate. Fatty acid esters of polyhydric alcohols such as esters, intramolecular esters such as γ-butyrolactone and ε-caprolactone, ethylene glycol monoformate, ethylene glycol monoacetate, ethylene glycol monopropionate, glycerin monoformate, glycerin Polyhydric alcohol partial esters such as monoacetate, glycerine monopropionate, glycerine diformate, glycerine diacetate, sorbitol monoformate, sorbitol monoacetate, and glycose acid monoacetate, as well as dimethyl succinate and maleic acid. Monohydric alcohol esters of polybasic acids such as dimethyl acid, and cyclic carbonates such as ethylene carbonate, propylene carbonate, and glycerin carbonate are used.

Further, as the amides, formamide, dimethylformamide, acetamide, dimethylacetamide, propionamide, butyramide, acrylamide, malondiamide, pyrrolidone, caprolatam, and the like are used.

Among the low-molecular organic compounds (B), water-soluble compounds are preferably used in order to perform uniform treatment,
It is particularly preferred to use aldehydes and esters. Furthermore, it is desirable to use glyoxal because it forms a highly hydrophilic film.

The blending ratio of the hydrophilic inorganic material (A) and the low molecular weight organic compound (B) containing a carbonyl group is as follows.

That is, 0.1 to 1 part by weight of the low molecular weight organic compound (B) having a carbonyl group is added to 1 part by weight of the hydrophilic inorganic material (A).
It is blended in a proportion of 5 parts by weight.

In the above, if the amount of the hydrophilic inorganic material (A) is small, a sufficient hydrophilic film will not be formed on the surface of the aluminum. On the other hand, if the amount is too large, the film becomes too hard, resulting in poor moldability and mold wear resistance.

Further, the amount of the low-molecular organic compound (B) having a carbonyl group is 0.00% per 1 part by weight of the hydrophilic inorganic material (A). 1'ff1
If it is less than ffi parts, the effect of adding the low-molecular organic compound (B) will not be exhibited, and if it exceeds 5 parts by weight, the hydrophilic inorganic material (A) will be relatively small, so that sufficient hydrophilicity will not be exhibited. .

Here, the hydrophilic inorganic material (A) and the low molecular weight organic compound (B) having a carbonyl group are used after being diluted with water. The dilution ratio must be determined in consideration of the hydrophilicity, film thickness, and workability of the film.

After forming the above-mentioned corrosion-resistant film on the surface of the aluminum plate, treatment with the aqueous solution of the above-mentioned mixture can be carried out by spraying or brushing, or by dipping the aluminum plate with the corrosion-resistant film, which has a protective coating on one side, into the aqueous solution. Just soak it.

The fin material treated with the aqueous solution is heated and dried at a temperature of 50 to 200°C, preferably 150 to 180°C, for 30 seconds to 30 minutes to form a hydrophilic first film on the surface of the corrosion-resistant film. .

Here, if the heat drying temperature is less than 50°C, the composition will not form a film sufficiently, and if it exceeds 200°C, further heating will have no effect. Further, if the heating drying time is less than 30 seconds, the composition will not be formed into a film sufficiently, and if it exceeds 30 minutes, productivity will decrease. And the heat drying temperature is 16
When the temperature is as high as 0 to 200°C, the drying time may be as short as 30 seconds to 1 minute, but when the temperature is low, the drying time needs to be longer. If heat drying is insufficient, the composition will not form a film sufficiently.

In addition, the hydrophilic first film has a surface area of 0.1 to 1
It is formed at a rate of 0 g/l12, preferably 0.5 to 3 g/l112. Here, if the first coating is 0.1 g/m2 or more, the initial hydrophilicity is good, but in order to maintain even better hydrophilicity, the first coating should be 0.5 g/m" or more. It is preferable that the first film has a thickness of 10 g/m.
If it exceeds 2, it takes a long time to dry and has an adverse effect on press formability, which is not preferable.

In order to improve the adhesion between the above-mentioned corrosion-resistant film and the first film and to improve the hydrophilicity of the side film, a silane coupling agent or a titanium coupling agent is added to the aqueous solution for forming the corrosion-resistant film as necessary. Alternatively, a surfactant may be added to the aqueous solution for forming the first film. Here, as the surfactant, nonionic surfactants can be suitably used.

In addition, the aqueous solution for forming the first film contains conventionally known additives, such as inorganic rust preventives such as sodium nitrite, sodium polyphosphate, and sodium metaborate, benzoic acid and its salts, and paranitrobenzoic acid. Organic rust preventives such as and salts thereof, cyclohexylamine carbonate, and benzotriazole may also be blended.

In addition, after forming a hydrophilic corrosion-resistant film and a hydrophilic first film on the fin material, in the final step, in order to remove dirt on the surface of the fin material, a surfactant is added to an extent that does not attack the first film. It may be washed with an aqueous solution, a solvent, etc., or may be washed with hot water.

In addition, the water-soluble organic polymer compound (C) constituting the hydrophilic second film formed on the surface of the other corrosion-resistant film is as follows:
Specific examples include polysaccharide-based natural polymers, water-soluble protein-based natural polymers, anionic, nonionic or cationic addition polymerization-based water-soluble synthetic polymers, and polycondensation-based water-soluble polymers.

Here, the polysaccharide natural polymers include soluble starch,
Carboxymethyl cellulose, hydroxyethyl cellulose, guar gum, gum tragacanth, xanthan gum, sodium alginate, etc. are used. Gelatin or the like is used as the water-soluble protein-based natural polymer.

Examples of anionic or nonionic addition polymer water-soluble polymers include polyacrylic acid, sodium polyacrylate, polyacrylamide, partial hydrolysates thereof, polyvinyl alcohol, polyhydroxyethyl acrylate, polyvinylpyrrolidone, and acrylic acid copolymers. , maleic acid copolymers and their alkali metal, organic amine and ammonium salts.

Furthermore, water-soluble synthetic polymers modified by carboxymethylation or sulfonation of the above-mentioned addition polymerized water-soluble synthetic polymers can also be used. Examples of cationic addition-polymerized water-soluble synthetic polymers include polyalkylamino(meth)acrylates such as polyethyleneimine, Mannich-modified compounds of polyacrylamide, diacryldimethylaluminum chloride, polyvinylimidacillin, and dimethylaminoethyl acrylate polymers. etc.

Polycondensation water-soluble synthetic polymers include polyoxyethylene glycol, polyoxyethylene glycol, polyoxyethylene dipropylene glycol, and other alkylene polyols, polyamines such as ethylenediamine and hexamethyldiamine, and epichlorohydrin polycondensates, and water-soluble polyols. A water-soluble polyurethane resin made by polycondensation of ether and polyisocyanate, polyhydroxymethylurea resin, polyhydroxymethylmelamine resin, etc. are used.

Among the water-soluble organic polymer compounds (C), it is preferable to use an anionic addition-polymerized water-soluble polymer having a carboxylic acid or a carboxylic acid group, particularly polyacrylic acid, acrylic acid copolymer, maleic acid, etc. Preference is given to using acid copolymers and their alkali metal salts. Here, the acrylic acid copolymer and maleic acid copolymer include copolymers of acrylic acid and maleic acid, as well as acrylic acid or maleic acid and methacrylic acid, methyl methacrylate, and ethyl methacrylate. , hydroxyethyl methacrylate, itaconic acid, vinylsulfonic acid, copolymers with acrylamide are preferably used.

The above-mentioned water-soluble organic polymer (C) is used alone to form the second film;
) and a low-molecular organic compound (B) containing the carbonyl group
(crosslinking agent) may be used together to form the second film.

The water-soluble organic polymer compound (C) or the low-molecular organic compound (B) having a carbonyl group is used after being dissolved in water. The concentration of these compounds depends on the hydrophilicity of the film,
It is necessary to determine the film thickness and workability.

To treat the surface of the other corrosion-resistant coating of the aluminum plate with an aqueous solution of the above-mentioned compound, it can be applied by spraying or brushing, or the fin material with the protective coating applied to the surface of the first coating can be immersed in the aqueous solution. do it.

When the water-soluble organic polymer compound (C) and the low-molecular organic compound (B) having a carbonyl group are used in combination, the latter is added to the former in a weight ratio of 1:0.5 to 2 (weight ratio ) is preferably used. Here, if the low molecular weight organic compound (B) having a carbonyl group is less than 0.5,
The effect of the crosslinking reaction is insufficient, and if it exceeds 2, the total amount of compound (B) used is too large and does not contribute to the reaction.
It's a waste.

Further, the fin material after being treated with the aqueous solution containing the above compounds (C) and (B) is heated to a temperature of 100 to 200°C, preferably 150°C.
Heating at a temperature of ~180°C for a time of 30 seconds to 30 minutes,
A second hydrophilic film is formed on the surface of the other corrosion-resistant film.

Here, if the heating temperature is less than 100°C, the compound (C
) and (B) were not sufficiently reacted and formed into a film, and 200
If the temperature exceeds ℃, further heating will not only have no effect, but will also have a negative effect on the material of the aluminum plate. Further, if the heating time is less than 30 seconds, the above reaction and film formation will not be carried out sufficiently, and if it exceeds 30 minutes, productivity will decrease.

When the heating temperature is as high as 160 to 200°C, the heating time may be as short as 30 seconds to 1 minute, but when the temperature is low, the heating time needs to be longer.

When using the water-soluble organic polymer compound (C) alone,
and a low-molecular organic compound having this and a carbonyl group (
In any case where B) is used together with
The coating is coated on the surface of the other corrosion-resistant coating on the aluminum plate.
．． 1-10g/ll12, preferably 0.5-3g10
Formed in a ratio of 12. Here, the second film is 0.1 g/
If it is 112 or more, the initial hydrophilicity is good, but in order to maintain even better hydrophilicity, 0.5g, /+
It is preferable to form two or more films. Moreover, if the second film exceeds 10 g/a2, it is not preferable because heating takes a long time and press formability is adversely affected.

The aqueous solution for forming the second film may contain conventionally known additives, such as inorganic rust preventives such as sodium nitrite, sodium polyphosphate, and sodium metaborate, benzoic acid and its salts, and para-nitrochloride. Of course, organic rust preventives such as benzoic acid and its salts, cyclohexylamine carbonate, benzotriazole, etc. may also be blended.

The heat exchanger fin material having the corrosion-resistant film and the first and second hydrophilic films obtained as described above is finally pressed to produce a heat exchanger fin. Here, pressing is a process for forming plate-like fins having tube insertion holes from the film-coated fin material, and includes, for example, stretching, drawing, punching, curling, and tube insertion. This includes ironing, etc., to tighten and heighten the cylindrical rising wall around the hole. In addition, when the fin material is a coil material, the shearing process that is performed subsequent to these processes to cut the fin material into a predetermined length is also included.

Of the hydrophilic first film and the hydrophilic second film formed on both sides of the heat exchanger fin material, the former first film mainly contains the hydrophilic inorganic material (A). Although it is extremely hydrophilic, it is hard. The latter second film is a water-soluble organic polymer compound (C)
As the main component is, the hydrophilicity is slightly inferior to that of the first film, but it is relatively soft.

Therefore, in the above-mentioned pressing process, for example, during ironing (drawless forming), the side surface of the first film of the heat exchanger fin material is directed toward the die side of the ironing mold (ioning mold), which has a relatively low forming rate. The molding is performed with the second film side of the fin material facing the punch side. As a result, wear scratches are less likely to occur on the surface of the punch, and ironing can be performed very smoothly.There is little wear on the punches of the mold, and heat exchanger fins can be manufactured efficiently.

As described above, a first film having strong hydrophilic properties is formed on one side of the heat exchanger fin material through a corrosion-resistant film, and a second film having relatively weak hydrophilic properties is formed on the other side through a corrosion-resistant film. Therefore, it is sufficient to arrange the required number of heat exchanger fins so that the hydrophilic first coating and second coating of adjacent fins face each other and attach them to the heat exchanger. In a heat exchanger made of fins, water droplets adhering to both sides of the fins immediately lose their shape and spread as a film on the surface of the fins, where they flow down and are almost completely removed. Water remaining on the fins forms a thin film due to surface tension, so this does not impede ventilation. Therefore, the ventilation resistance does not increase due to adhesion of water droplets, and a heat exchanger with high heat exchange efficiency can be obtained.

Example Next, examples of the present invention will be described together with comparative examples.

J I 5A-1100H24 with a thickness of 1 n+m, a width of 50 mm and a length of 100 mm was used as the aluminum plate.

After forming a corrosion-resistant film made of the following water-soluble synthetic resin on both sides of this aluminum plate, an aqueous solution containing various components of the hydrophilic first film and second film as shown below was applied separately, and heated at 160°C. Heating for 10 minutes and drying to form a first hydrophilic film on the surface of one corrosion-resistant film and a second hydrophilic film on the surface of the other corrosion-resistant film,
Fin material for heat exchangers was manufactured. In addition, as the alkali silicate in the components of the hydrophilic first film, SiO2/
One with a Na2O ratio of 3 was used.

Evaluation test In order to evaluate the performance of the fin material obtained as described above, the film adhesion, corrosion resistance, alkali resistance, hydrophilicity,
The moldability and mold wear resistance were measured, and the results are shown in the table below.

Here, the adhesion was determined by measuring the adhesion between the corrosion-resistant film and the first hydrophilic film or the second hydrophilic film.

Corrosion resistance was determined by measuring the surface condition of the fin material 20 days after the salt spray test.

Alkali resistance was determined by measuring the state of pitting on the surface of the fin material after the fin material was immersed in saturated lime water with a pH of approximately 13 at 30° C. for 100 hours. .

Hydrophilicity is determined in the early stages and in the oleic acid contamination test (
The contact angle of water on the fin material was measured at the stage after a cycle test in which a test (14 hours) and a running water immersion test (8 hours) were alternately repeated three times.

In addition, for hydrophilicity evaluation, contact angle of 15° or less is ◎, 16@
-30° was indicated as 0131° - 50'' was indicated as △, and 51'' or more was indicated as X.

Formability and mold wear resistance are determined by ironing the fin material according to the present invention from the hydrophilic second film side and also by burring to improve the limit ironing rate and to prevent cracks from occurring at the bent portions during burring. Measure whether or not
The wear condition of the mold was also measured. Note that molds with less wear were rated as good.

The evaluation of adhesion, corrosion resistance, alkali resistance, moldability, and mold wear resistance tests was as follows.

◎: Very good, ○: Good, △: Slightly poor, ×: Poor.

For comparison, we manufactured fin materials having the following three types of coatings on the surface of the above aluminum plate, and conducted evaluation tests on these fin materials in the same manner as in the above case.The obtained results are shown in the table below. are summarized in the following.

(Left below) As is clear from the table above, the fin material according to the present invention has superior hydrophilicity compared to the fin material of the comparative example, and also has excellent alkali-resistant formability and mold wear resistance. It is excellent.

Effects of the Invention As described above, the fin material for a heat exchanger according to the present invention has the following features:
Corrosion-resistant films made of water-soluble synthetic resin are formed on both sides of the aluminum plate, and on the surface of one corrosion-resistant film,
A first hydrophilic film made of a hydrophilic inorganic material and a low-molecular organic compound having a carbonyl group is formed, and a water-soluble organic polymer compound, or a water-soluble organic polymer compound and a carbonyl group is formed on the surface of the other corrosion-resistant film. The second hydrophilic film is formed of a low-molecular organic compound with Therefore, these corrosion-resistant coatings and the hydrophilic first coating or the hydrophilic second coating have mutual affinity and have good adhesion. Moreover, while the first hydrophilic film has excellent hydrophilicity and durability, it is hard, and the second hydrophilic film has slightly inferior hydrophilicity and durability, but compared to During ironing and burring, the punch of the mold is applied to the surface of the second hydrophilic film on the soft side of the fin material to prevent wear of the punch. Moreover, since the punch does not easily get scratches due to abrasion, it has extremely good formability, and does not cause scratches on the fin surface or cracks on the fin molded part, making it suitable for high-quality heat exchangers. Fins can be manufactured very efficiently. Further, by arranging the required number of heat exchanger fins made from the heat exchanger fin material according to the present invention so that the hydrophilic first coating and hydrophilic second coating of adjacent fins face each other, excellent Since hydrophilicity and its sustainability can be maintained for a long period of time, condensed water on the fin surface will not form a bridge between the fins, increasing ventilation resistance in the humid environment of the heat exchanger. This has the effect of minimizing the

that's all

Claims (1)

[Claims] Corrosion-resistant films made of water-soluble synthetic resin are formed on both sides of the aluminum plate, and a hydrophilic first film made of a hydrophilic inorganic material and a low-molecular-weight organic compound having a carbonyl group is formed on the surface of one of the corrosion-resistant films. fin for a heat exchanger, wherein a hydrophilic second film made of a water-soluble organic polymer compound, or a water-soluble organic polymer compound and a low-molecular organic compound having a carbonyl group is formed on the surface of the other corrosion-resistant film. Material.