JPS618598A - Fin material for heat exchanger whose surface hydrophilic nature is excellent - Google Patents

Abstract

PURPOSE:To carry out degreasing after press molding thereby removing completely a press oil, by providing a mixture coating of a special water-soluble organic high-molecular compound and a silicate compound on an aluminium or aluminium alloy surface. CONSTITUTION:As a mixture coating to be provided on an aluminium or aluminium alloy surface, a mixture of a silicate compound having the formula 1 wherein M=Li, Na or K, and y/x>=2 dispersed in one or more water-soluble organic high-molecular compounds selected from styrene/maleic acid copolymers, polyacrylamides, butylene/maleic acid copolymers, polyacrylic acids and their salts can be designated. After the mixture has been applied, it becomes a porous coating by gelling in a drying stage. The water-soluble organic high-molecular compound facilitates the dissolving of a press oil into a degreasing solvent, and as the mixture coating is porous, if the coating surface is polluted with oil constituents in the atmosphere during the drying operation, it exhibits wettability in the dewing operation due to the hydrophilic nature of the porous surface.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a fin material for a heat exchanger with excellent surface hydrophilicity, and more specifically, to a fin material for heat exchangers that has excellent degreasing properties and sustained hydrophilicity for aluminum or aluminum alloys for heat exchangers. The present invention relates to a fin material for a heat exchanger having a coating layer with excellent surface hydrophilicity.

[Prior Art] In general, aluminum or aluminum alloys are widely used as fin materials for heat exchangers because of their excellent thermal conductivity, formability, and corrosion resistance.

By imparting hydrophilicity to the heat exchanger fin material made of aluminum or aluminum alloy and improving water wettability, ventilation resistance when used as a heat exchanger is reduced, resulting in thermal efficiency. In some cases, it may be possible to improve noise levels and reduce noise.

Examples of such hydrophilic treatment include silicate treatment and boehmite treatment, and a representative example of these conventional techniques is the one described in JP-A-58-106397. , this prior art has two problems as described below. That is, (1) if the treatment is performed before molding, the press oil during molding will not be removed during solvent degreasing and will remain, resulting in blistering properties.

(2) During long-term use, oil in the air may adhere and cause water to be thrown.

It is.

These two problems will be explained.

The first problem is that if hydrophilic treatment is performed before molding,
Press oil is applied for processing lubrication during molding, and is washed away during the degreasing process during molding, but degreasing tends to be insufficient during this degreasing process, and press oil remains on the fin surface, causing water to leak. Therefore, in order to perform hydrophilic treatment before molding and to obtain hydrophilic properties after assembling the heat exchanger, press oil must be sufficiently removed during the degreasing process. Hydrophilic treatment such as degreasing is required.

(2) The second problem is that when dew condenses on the fin surface while operating a heat exchanger that has been treated to make it hydrophilic (usually indoor units in cooling operation and outdoor units in heating operation), the fin surface is hydrophilic. However, if oil in the air adheres during drying operation where the fin surface does not condense, water spots may occur due to contamination by oil on the fin surface even if the fin surface is subsequently operated with dew condensation. A hydrophilic surface cannot be obtained. That is,
In order to maintain hydrophilicity over a long period of time, a high level of hydrophilicity is required that allows water wettability even after the fin surface is contaminated due to repeated dew condensation and drying operations.

[Problem to be Solved by the Invention 1] The present invention has been made in view of the problems in the prior art as explained above, and it is possible to completely remove press oil by degreasing after press molding, and The present invention provides a fin material for a heat exchanger that has a highly hydrophilic coating layer that does not reduce its hydrophilicity even after repeated dew condensation and drying operations when used as a heat exchanger, and has an excellent surface hydrophilicity.

[Means for Solving the Problems 1] The features of the heat exchanger fins according to the present invention with excellent surface hydrophilicity include: styrene-maleic acid copolymer, polyacrylamide, butylene on the aluminum or aluminum alloy surface; One or more water-soluble organic polymer substances selected from a maleic acid copolymer, polyacrylic acid, or a salt thereof;
The reason is that a mixture coating layer with a silicate compound represented by the following formula % is provided.

Note that a coating layer selected from chrome-F, boehmite, and a silicate organic coating can be provided as a base for the mixture coating layer.

The fin structure for heat exchangers with excellent surface hydrophilicity according to the present invention will be described in detail below.

In the heat exchanger fin material with excellent surface hydrophilicity according to the present invention, the mixture coating layer provided on the aluminum or aluminum alloy surface is made of styrene-maleic acid copolymer, polyacrylamide, butylene-maleic acid copolymer, polyester, etc. XM20 in one or more water-soluble organic polymer substances of acrylic acid or salts thereof.
-ysio2 (M=Li, Na, K) is a mixture of dispersed silicate compounds in which y/x is 2 or more, and this mixture gels during the drying process after application. This results in a porous coating layer.

Even when an organic solvent such as 1.1°1 trichloroethane, which has a weak degreasing property, is used in the degreasing process, the above-mentioned water-soluble organic polymer substances promote the elution of press oil into the degreasing solvent. Even if a mixture coating layer is provided beforehand and press oil is applied during molding, the press oil is easily removed by solvent degreasing and a hydrophilic surface is obtained.

In addition, since the mixture coating layer is porous, even if the surface of the coating layer is contaminated by oil in the atmosphere during drying operation, the mixture coating layer has a porous hydrophilic surface inside, so it will not cause dew condensation during operation. It exhibits water wettability, and when contaminated areas are wetted with water, oil is washed away and the hydrophilicity is restored. That is,
It maintains its hydrophilicity for a long period of time even after repeated cycles of dew condensation and drying operations, and exhibits excellent parent tree sustainability.

In addition, in order to make the coating mixture provided on the heat exchanger fin material with excellent surface hydrophilicity according to the present invention porous, it is limited by the above-mentioned water-soluble organic polymer substance and the formula described above. It is necessary to mix both the silicate compound and the silicate compound, and it is not possible to obtain a porous mixture coating layer with either one of them.

Therefore, the mixing ratio of the water-soluble organic polymer substance and the silicate compound is preferably in the range of 2:1 to 1:4 in terms of weight ratio.

In addition, silicate compound XM2O-ySio2 (M=Li,
y/x of x and y in the formula (Na, K) must be 2 or more; if it is less than 2, a porous mixture coating layer cannot be obtained.

The concentration when applying this mixture to the needle aluminum or aluminum alloy coating layer may be appropriately selected depending on the coating method, and is 0.5 to 10% for the industrially common roll coating method, and 0.5 to 10% for the dip method. 2-10
% concentration is preferable.

The coating thickness of this mixture coating layer is preferably 0.05 to 2μ; if it is less than 0.05μ, excellent tree parent performance cannot be obtained, and if it exceeds 2μ, the hydrophilic effect is saturated.
This results in uneven appearance and is uneconomical.

In addition, by providing a coating layer selected from chromate, boehmite, or silicate as a base for the mixture coating layer detailed above, a layer having both corrosion resistance and hydrophilicity can be obtained.

[Example] An example of a fin material for a heat exchanger having excellent surface hydrophilicity according to the present invention will be described.

Examples 1 to 6 shown in Table 1 are fin materials for heat exchangers with excellent hydrophilicity on the surface of the present invention, in which a mixture coating layer is provided on a degreased aluminum material, and Examples 7 to 10 are aluminum This is a fin shell for a heat exchanger with excellent surface hydrophilicity according to the present invention, in which a base treatment material is provided on the material and a mixture coating layer is provided on the material. Comparative Example 4 has only a silicate coating, and Comparative Example 5 has only a boehmite coating.

Table 2 shows the results of a survey on degreasability and parent tree persistence.

Section A is a degreasing property evaluation, Examples 1 to 10, Comparative Examples 1 to
5, each coating layer was provided before molding, and press oil was applied (press oil kinematic viscosity 9.Qcst/4 (1'c) →
Molding→solvent degreasing (1,1,1) hot bath in lychloroethane for 1 minute→cold bath for 1 minute→steam for 1 minute)→hydrophilicity evaluation.

Hydrophilicity evaluation method 1) Water wettability: Immerse it in water, take it out and observe the outside of the condensate.

2) Water contact angle; measured with a goniometer.

Section B is an evaluation of parent tree sustainability, and Examples 1 to 10 and Comparative Examples 1 to 5 are aluminum fin materials each provided with a coating layer. A sex evaluation was performed.

Running water → drying cycle; running water 51/HrX 8 Hrs
→ Heating at 80°C for 16 hours is one cycle, and this is repeated.

[Effect of the invention 1 As explained above, since the fin material for a heat exchanger according to the present invention having an excellent surface hydrophilicity has the above-mentioned structure, press oil can be removed by degreasing after press molding. This is a fin material for heat exchangers that has excellent degreasing properties that can be completely removed, and excellent persistence of parent wood that does not reduce its hydrophilicity even after repeated dew condensation and drying operations.

Claims (2)

[Claims] (1) One or more water-soluble organic polymer substances selected from styrene-maleic acid copolymer, polyacrylamide, butylene-maleic acid copolymer, polyacrylic acid, or their salts on the surface of aluminum or aluminum alloy. and a silicate compound represented by the following formula xM_2O-ySiO_2 (where M=Li, Na, K) (y/x≧2). Excellent fin material for heat exchangers. (2) The surface hydrophilicity of claim 1 is characterized in that a coating layer selected from chromate, boehmite, and silicate organic coatings is provided as a base of the mixture coating layer. Excellent fin material for heat exchangers.