JP3050728B2 - Aluminum fin material for heat exchanger - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aluminum or aluminum alloy sheet (hereinafter simply referred to as an aluminum sheet).
No need to apply press oil at the time of press molding, and to expose a hydrophilic film from which a lubricious film can be easily removed by washing with water. The present invention relates to a dexterous hydrophilic aluminum fin material.

[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 a fin, usually, it is applied to a fin press machine in a state of a strip, and is continuously formed at a high speed. This forming is a combination of stretching, drawing, ironing, punching, hole expanding, bending, corrugating, louvering, etc., and requires a very high formability. For this reason, it is of course necessary that the aluminum material itself be excellent in formability,
Conventionally, press oil is applied to the surface of a thin aluminum plate in order to provide lubrication during the forming of the fin material. The molded fin is usually combined with a copper tube to form a core for an evaporator or a condenser. Or occur. Therefore, cleaning and degreasing after core assembly is indispensable.
However, for cleaning and degreasing, chlorine-based solvents such as chlorofluorocarbons, trichloroethane, and trichloroethylene or aqueous detergents (surfactants) are used. Cleaning with chlorine-based solvents has a problem of environmental pollution, The washing used complicates the process. In recent years, petroleum-based volatile press oils that do not require cleaning and degreasing are also used, but due to the low viscosity oil, processing conditions have become strict, requiring frequent mold maintenance and risk of ignition. There are many problems such as deterioration of workability and work environment.

[0003]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an aluminum fin material for a heat exchanger which has excellent moldability and does not require application of press oil.
Furthermore, an object of the present invention is to provide an aluminum fin material for a heat exchanger in which a lubricating film is formed, thereby exhibiting excellent moldability, and the film can be easily removed by washing with neutral or acidic water. It is in.

[0004]

Means for Solving the Problems The present inventors have intensively studied to solve the above-mentioned problems, and as a result, after forming a hydrophilic film on an aluminum sheet, a lubricating film having a specific composition is formed thereon. It has been found that the object can be achieved by forming the above formula, and the present invention has been accomplished based on this finding. That is, the present invention forms a hydrophilic film formed on an aluminum or aluminum alloy substrate with a treating agent containing at least one silicon compound selected from silica and silicate, and then forms a hydrophilic film thereon by washing with water. An object of the present invention is to provide an aluminum fin material for a heat exchanger, which is formed by forming a lubricating film of a resin composition which is easily desorbed. The aluminum thin plate used as the base material in the present invention is not particularly limited in the specification of the pure aluminum or the aluminum alloy composition, and any one generally used as an aluminum fin material can be used, but JIS A1050, A1100 and A30 are preferable.
03 or their equivalents. The thickness of this aluminum thin plate is usually 0.1 to 0.2 mm
, But is not limited to this.

[0005] Drawless molding is the mainstream for forming aluminum fin materials for heat exchangers. This method employs a piercing burring (b) and a first ironing as shown in Figs. (C), the second ironing (d), and the refrea (e) steps. In this case, the molding conditions in the second ironing step (d) are strict, and the second ironing punch (d) is particularly susceptible to wear. In the present invention, the lubricating film easily detached by washing with water is preferably a resin composition containing a resin having a hydroxyl group and / or a carboxyl group and at least one selected from a polyolefin wax and a fluororesin. A lubricious film is formed. The base resin used in the lubricating resin composition is a resin having a hydroxyl group and / or a carboxyl group. Examples of such a resin include an acrylic resin, an alkyd resin, a urethane resin, an epoxy resin, a cellulose resin, and a phenol. Resins, melamine resins, polyvinyl butyral resins, and the like. General additives such as a reaction accelerator, a stabilizer, and a dispersant may be appropriately added to these base resins as long as the effects intended by the present invention are not impaired. Next, the polyolefin wax and the fluorine resin are organic resin agents having a high melting point and a small specific gravity. Specifically, the polyolefin wax that can be used in the present invention preferably has a melting point of 70 ° C. or higher, and includes, for example, a wax having a melting point of 70 ° C. or higher made of an olefin polymer such as polyethylene, polypropylene, and polybutene. Can be Examples of the fluorine-based resin include polytetrafluoroethylene resin, polyvinyl fluoride resin, polyvinylidene fluoride resin, and polyfluoroethylene resin. The polyolefin wax and the fluororesin can be used alone or in combination of two or more. The polyolefin wax and / or the fluorine-based resin is preferably used in an amount of 2 to 40% by weight, more preferably 5 to 30% by weight, based on the resin having a hydroxyl group or a carboxyl group.

The thickness of the lubricating resin film is not particularly limited, but is preferably 0.05 to 5.0 μm. If the film thickness is too small, the lubricity is not sufficient, and if the film is too thick, the press formability decreases, which is not economical. In the present invention, this lubricating film is coated on a hydrophilic film composed of silica and / or silicate to obtain a sufficient lubricating effect, and press molding is possible without press oil. The thickness of the hydrophilic film is not particularly limited, but is applied to a thickness in which a sufficient amount of silicon for imparting hydrophilicity is present, and is appropriately set in a range of usually 30 to 300 mg / m ^{2 in} silicon application amount. Is done. The lubricating film laminated on the hydrophilic film composed of silica and / or silicate is washed with water by immersing the film in a neutral or acidic solution or spraying. Easily detached at the interface with the lower hydrophilic film, and the hydrophilic film is exposed, and sufficient hydrophilic performance can be obtained. Neutral or acidic solutions used for such washing include distilled water, ion-exchanged water, nitric acid, which do not corrode and do not affect the hydrophilic film.
Acetic acid, phosphoric acid and the like can be mentioned. In particular, when an acidic solution is used, the desorption of the lubricating film is accelerated, and the line speed can be increased. Also, desorption of the lubricating film can be accelerated by raising the temperature of pure water or ion-exchanged water.

[0007]

Next, the present invention will be described in more detail with reference to examples. Industrial pure aluminum (JIS A1100
-H26, 0.10 mm thick), the surfaces of which are continuously degreased, then subjected to a phosphoric acid chromate treatment, and then a hydrophilic treatment agent of silica and / or silicate is applied. After application and baking, a lubricating resin composition was applied thereon and baked. Degreasing was performed using a commercially available weak alkaline detergent, and phosphoric acid chromate treatment was performed using Alsurf 401-45 manufactured by Nippon Paint Co., Ltd., with a Cr content of 20 mg / deg.
I was treated to be m ^2. The hydrophilic treatment agent and the lubricating resin composition are applied respectively by a roll coater, and the hydrophilic treatment agent is baked at 230 ° C. for 15 seconds and the lubricating resin composition is baked at 150 ° C. for 15 seconds in a hot air drying oven. Was done.
Table 1 shows the component composition of the resin film and the silicon content of the hydrophilic film.

[0008]

[Table 1]

The strip material thus obtained was applied to a fin forming press, and the abrasion state and forming workability of the forming tool after continuous 100,000 shots were examined. The moldability was evaluated based on the incidence of refrea cracking. For comparison, similar press working tests and evaluations were performed using uncoated strips of the same material, with or without press oil. Also, the formed fins are laminated, a copper tube is inserted and expanded to form a core. The core is immersed in a neutral or acidic solution shown in Table 1 at a predetermined temperature for a predetermined time, and then the core is atomized. , Water was sprayed, and the presence or absence of water pools and bridges (cross-linking phenomenon due to water between the fins) was examined to evaluate the hydrophilicity performance. Table 2 shows the results.

[0010]

[Table 2]

As is clear from the results in the table, the N
o. In Nos. 1 to 6, the occurrence rate of refrea cracking is low even without using press oil, the tool does not wear, and the hydrophilicity is good. On the other hand, in reference example No. In No. 7, the fin material is that of the present invention, but the lubricating film is not removed, so that the fin has poor hydrophilicity. Also,
No. of the comparative example. Without applying a lubricating film as in 8,
It can be seen that when pressed without using press oil, the rate of occurrence of refrea cracks is remarkably high, and tool wear also occurs. Comparative Example No. The use of press oil as in No. 9 can reduce the rate of occurrence of refrea cracks, but requires cleaning and degreasing.

[0012]

The lubricating hydrophilic aluminum fin material of the present invention can be continuously and rapidly formed at a high speed without using press oil at the time of forming the fin. Since the coating is immersed in a neutral or acidic solution or sprayed, that is, easily removed by washing with water, the hydrophilic coating is exposed and sufficient hydrophilic performance can be provided. When the aluminum fin material for a heat exchanger of the present invention is assembled into a core, press oil is not used, so that degreasing after assembling the core is unnecessary, and there is no problem of drainage treatment and no complicated cleaning. Further, it is extremely effective in terms of preventing environmental pollution and improving productivity by omitting a washing step.

[Brief description of the drawings]

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1A to 1E are explanatory views of a drawless forming process of an aluminum fin material for a heat exchanger, wherein FIG.
(C) shows the first ironing process, (D) shows the second ironing process, and (E) shows the refrea process.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Aluminum thin plate 2 2nd ironing punch 3 2nd ironing die

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-281722 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) F28F 1/32

Claims (2)

(57) [Claims] 1. An aluminum or aluminum alloy substrate having at least one selected from the group consisting of silica and silicate.
An aluminum fin material for a heat exchanger, comprising: forming a hydrophilic film containing a kind of silicon compound, and coating thereon a film of a lubricating resin composition which is easily detached by washing with water. 2. The film of the lubricating resin composition is a film of a resin composition of a resin having a hydroxyl group and / or a carboxyl group and at least one selected from a polyolefin wax and a fluororesin. The aluminum fin material for a heat exchanger according to claim 1.