JPH0650691A - Aluminum fin material for heat exchanger - Google Patents

Abstract

PURPOSE:To obtain an aluminum film material for a heat exchanger which is covered with a lubricating film which does not need press oil at the time of molding the material and hence not need a press oil cleaning step after a core is assembled. CONSTITUTION:An aluminum fin material for a heat exchanger comprises an aluminum or an aluminum alloy thin plate coated on both side surfaces with resin composition containing 100 pts.wt. of resin having hydroxyl group and/or carboxyl group and 1.0-20 pts.wt. of fluorine series resin and/or polyolefin wax in a coating amount of 0.1-3g/m<2> per one side surface of drying weight.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention does not require application of press oil during press forming by forming a lubricious film on the surface of aluminum or aluminum alloy thin plate (hereinafter simply referred to as aluminum thin plate) before press forming. The present invention relates to an aluminum fin material for a heat exchanger.

[0002]

2. Description of the Related Art Aluminum fins having excellent heat conductivity are used as fins of heat exchangers such as evaporators and condensers of air conditioners. In order to form an aluminum thin plate into fins, it is usually carried out by applying it to a fin press machine in the state of a strip and continuously forming it at high speed. This molding is a combination of overhanging, squeezing, ironing, punching, hole expanding, bending, corrugating, slitting, louvering, etc., and requires extremely high formability. For this reason, the aluminum material itself is of course required to have excellent formability, but in order to provide lubricity during the fin material forming process, aluminum thin plates have conventionally been coated with press oil. Molded fins are usually combined with copper tubes to form the core of evaporators and condensers, but if press oil remains on the fins, smoke will be generated due to heating during U-bend brazing, and surface treatment of the core It cannot be done or emits an offensive odor during use. Therefore, degreasing after core assembly is essential. A solvent such as trichloroethane, trichloroethylene or freon, or an aqueous detergent is used for this cleaning and degreasing. Cleaning with a solvent has a problem of environmental pollution, and cleaning with an aqueous detergent complicates the process.

[0003]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a heat-resistant coating of a lubricating film which has good moldability and does not require press oil at the time of press molding, and therefore does not require a press oil washing step after core assembly. It is to provide an aluminum fin material for a exchanger.

[0004]

Means for Solving the Problems The inventors of the present invention have made intensive studies to solve the above problems. It is necessary to provide a thin aluminum plate with a lubricating film of a resin composition having a specific composition to a predetermined thickness. They have found that they are extremely effective in improving their moldability, and have completed the present invention. That is, the present invention provides a resin 1 having (a) a hydroxyl group and / or a carboxyl group on both sides of an aluminum or aluminum alloy thin plate.
A resin composition containing 1.0 to 20 parts by weight of (b) a fluorine-based resin and / or a polyolefin wax per 100 parts by weight is 0.1 to 3 g / m ² on a dry weight side.
The present invention provides an aluminum fin material for a heat exchanger, characterized by being coated with the coating amount of In the present invention, it is preferable to add a predetermined amount of silica to the resin composition.

The aluminum thin plate used as the substrate in the present invention is not particularly limited in the standard of pure aluminum or the aluminum alloy composition, and any one generally used as an aluminum fin material can be used, but JIS A1050 is preferred. , A1100 and A3
003 or their equivalents.
The thickness of this aluminum sheet is usually 0.1-0.2 mm
However, it is not limited to this. In the present invention, a film of the resin composition is formed on this aluminum thin plate. The film of this resin composition comprises (a) a resin having a hydroxyl group and / or a carboxyl group, and the resin 100
(B) 1.0 to 20 parts by weight of a fluorine-based resin and / or a polyolefin wax as a solid lubricant, and the coating amount thereof is 0.1 to 3 g / m ² on one side in dry weight.
It is a resin film of. The base resin of the component (a) used in the lubricating resin composition used in the present invention is a resin having a hydroxyl group and / or a carboxyl group. Examples of such a resin include an epoxy resin, an alkyd resin, and an acrylic resin. Resin, urethane resin, phenol resin, melamine resin, polyvinyl butyral resin, etc. are mentioned. General additives such as a reaction accelerator, a stabilizer, and a dispersant can be appropriately added to the base resin as long as the effects intended by the present invention are not impaired.

Next, the fluororesin and the polyolefin wax as the component (b) will be described. Known dry lubricants include wax, molybdenum disulfide, graphite, carbon fluoride, metallic soap, boron nitride, and fluororesin, which are used as lubricants for bearings, plastics, oils, and greases. Etc. to improve lubricity. Therefore, various studies were conducted to form a resin film having excellent lubricity on an aluminum thin plate using these lubricants.
As a result, it has been found that a fluorine resin and a polyolefin wax, which are organic lubricants having a high melting point and a small specific gravity, are effective.

Specific examples of the fluorine-based resin that can be used in the present invention include polytetrafluoroethylene resin, polyvinyl fluoride resin, polyvinylidene fluoride resin, and polyfluoroethylene resin. Also,
As the polyolefin wax, one having a melting point of 70 ° C. or higher is effective, and for example, a wax having a melting point of 70 ° C. or higher made of an olefinic hydrocarbon polymer such as polyethylene, polypropylene or polybutene can be mentioned. The fluororesin and the polyolefin wax of the present invention are used alone,
Alternatively, two or more kinds can be mixed and used. Further, in the present invention, it is preferable to use the fluororesin as a powder. The fluororesin and the polyolefin wax may have a particle size of about 0.1 μm or more, and particularly when they stick out from the resin film, they may absorb frictional impact with the mold during press working. It is thought to work effectively. The particle size of the fluororesin powder and the polyolefin wax is more preferably 0.1 to 7 μm.

In the present invention, the fluorine resin powder and / or the polyolefin wax as the component (b) are contained in an amount of 1.0 to 20 parts by weight based on 100 parts by weight of the base resin having a hydroxyl group and / or a carboxyl group. Let
When the amount of the component (b) is less than 1.0 part by weight, the lubricating effect is not sufficient, and when it exceeds 20 parts by weight, the cohesive force and the adhesive force of the resin are deteriorated, so that the resin film is likely to be peeled off during processing.
In the present invention, in the resin composition, 100 parts by weight of the component (a) and 1.0 to 20 parts by weight of the component (b) are added, and further, silica is contained as the component (c) in an amount of 80 parts by weight or less. It is more preferable to contain 10 to 80 parts by weight. The addition of this silica can further improve the corrosion resistance of the resin-coated fin. It is considered that this effect is due to the reaction of the hydroxyl groups or carboxyl groups in the base resin with the hydroxyl groups on the silica surface to form a highly corrosion-resistant inorganic-organic composite coating of silica-resin. As such silica, colloidal silica,
Examples thereof include organosilica sol, silica powder and organic silicate, and the particle size of silica is preferably 5 to 70 nm in order to uniformly disperse silica.

When silica is contained, a silane coupling agent may be used as a reaction accelerator for the base resin and silica. As a silane coupling agent,
Examples include γ- (2-aminoethyl) aminopropyltrimethoxysilane and γ-glycidoxypropyltrimethoxysilane. It is preferable to add 10 parts by weight or more of the above silica to 100 parts by weight of the resin having a hydroxyl group and / or a carboxyl group in order to improve the corrosion resistance, but if it exceeds 80 parts by weight, the film hardness increases. ,
Mold galling occurs during molding, deteriorating press moldability.
In the present invention, the coating amount of such a lubricating resin film is 0.1 to 3 g / m ² on one side in dry weight. 0.1 g / m
^If it is less than ² , the lubricity is not sufficient, and if it exceeds 3 g / m ² , the film becomes thick and press formability deteriorates, which is not economical.

Next, an example of the method for producing the aluminum fin material for a heat exchanger of the present invention will be described. Degrease the aluminum thin plate of the substrate. Next, a predetermined amount of each component of the resin composition is prepared, and they are mixed and dispersed to make them physically uniform. The above-mentioned reaction accelerator, stabilizer, dispersant, diluent and the like may be appropriately added to this composition. This resin composition is coated by a usual method such as roll coating, spray coating, dip coating, and brush coating so that the aluminum thin plate has a predetermined thickness.
It is dried at 80 to 180 ° C. for 3 to 90 seconds. In this way, the aluminum fin material for a heat exchanger having excellent lubricity of the present invention is manufactured.

[0011]

EXAMPLES Next, the present invention will be described in more detail based on examples. Example 1 Industrial pure aluminum (JIS A1100-H26,
A strip having a thickness of 0.10 mm was used to continuously degrease both surfaces of the strip, and then the lubricating resin composition of the present invention was applied and dried. A commercially available weak alkaline detergent was used for degreasing. The lubricating resin composition according to the present invention was applied with a roll coater and dried in a hot air drying oven at 150 ° C for 15 seconds. The component composition of the resin film is as shown in Table 1. Apply the lubrication coated strip obtained in this way to the fin forming press,
After 100,000 consecutive shots, the wear condition of the molding tool and the moldability were examined. Molding workability was evaluated by the rate of occurrence of reflaring cracks. For comparison, similar press working tests and evaluations were performed using uncoated strips of the same material, with or without pressing oil.

The above results are shown in Table 2. From the results of Table 2, in Experiment Nos. 14 to 17, if a resin composition outside the scope of the present invention is used, or if the resin composition is coated too much or too little, molding without press oil is performed. Refractory cracks may occur, increasing the defect rate and causing tool wear (Experiment No. 14, 16, 1).
8). On the other hand, in Experiment Nos. 1 to 13, it can be seen that the occurrence rate of the flare cracks is low and tool wear does not occur even without using the press oil. Also, as can be seen from Experiment Nos. 18 to 19, in the unpainted material, the rate of occurrence of reflaring cracks was extremely large unless press oil was used, and it can be reduced only by using press oil, but cleaning degreasing is necessary. Become.

[0013]

[Table 1]

[0014]

[Table 2]

Example 2 A coated strip was prepared in exactly the same manner as in Example 1 except that coating was carried out using a resin composition containing silica as shown in Table 3. This was subjected to a formability test in the same manner as in Example 1. In addition, a corrosion resistance test is performed by a salt spray test (JIS Z237
According to 1), the time until the occurrence of corrosion of the fin was evaluated. For comparison, experiments Nos. 18 and 19 were conducted on the uncoated material as in the comparative example of Example 1. From the results of Experiment Nos. 1 to 15 in Table 4, not only the moldability of the fin material was improved by coating the resin composition further containing silica, but the corrosion resistance was improved as compared with Experiment Nos. 18 and 19. It can be seen that it can be significantly improved. In Experiments Nos. 16 and 17, the coverage was too small or too large, and the rate of occurrence of flare cracks was high.

[0016]

[Table 3]

[0017]

[Table 4]

[0018]

EFFECTS OF THE INVENTION The aluminum fin material for a heat exchanger having excellent lubricity of the present invention has excellent formability by forming a lubricating film on an aluminum thin plate, and can be continuously formed without using press oil during fin forming. In addition, it has an excellent effect that the fin forming process can be performed at high speed. Furthermore, when a predetermined amount of silica is contained in the lubricous film,
Has excellent corrosion resistance and withstands long-term use. Further, when the aluminum fin material for a heat exchanger of the present invention is assembled to the core, press oil is not used, so degreasing after assembling the core is not necessary, and there is no problem of drainage treatment and no complicated cleaning. Furthermore, it is extremely effective in terms of preventing environmental pollution and improving productivity by omitting the washing step.

Front page continued (72) Inventor Ito Martial Arts 3-22 Takaida Hondori, Higashi-Osaka City, Osaka Prefecture Matsushita Refrigerator Co., Ltd. (72) Inventor Kenji Fujino 3-22 Takaida Hon-dori, Higashi Osaka City, Osaka Matsushita Cold Machine Co., Ltd. In-house (72) Inventor Nobuo Totsuka No. 1 Kawasaki-cho, Chiba-shi, Chiba Kawasaki Steel Co., Ltd. In-house (72) Inventor Mitsuya Miyamoto 2-6-1, Marunouchi, Chiyoda-ku, Tokyo Inside Furukawa Aluminum Co., Ltd.

Claims (2)

[Claims] 1. A (b) fluororesin and / or 100 parts by weight of a resin having a hydroxyl group and / or a carboxyl group on both surfaces of an aluminum or aluminum alloy thin plate.
Alternatively, a resin composition containing 1.0 to 20 parts by weight of a polyolefin wax may be used in an amount of 0.1 to 3 on a dry weight side.
An aluminum fin material for a heat exchanger, which is coated with a coating amount of g / m ² . 2. A (b) fluororesin and / or 100 parts by weight of a resin having (a) a hydroxyl group and / or a carboxyl group on both sides of an aluminum or aluminum alloy thin plate.
Alternatively, a resin composition containing 1.0 to 20 parts by weight of a polyolefin wax and 10 to 80 parts by weight of (c) silica is coated at a coating amount of 0.1 to 3 g / m ^{2 on} one side in dry weight. Aluminum fin material for heat exchangers, which is characterized in that