JPS63173632A - 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 (a) Field of Industrial Application The present invention relates to a fin material for a heat exchanger, and more particularly to a fin material for a heat exchanger that prevents condensed water from accumulating on its surface.

(b) Conventional technology Some heat exchangers are equipped with aluminum fins that have excellent heat conductivity in order to improve heat exchange efficiency. When performing air conditioning using this heat exchanger, warm air is cooled between the fins, but condensed water may adhere to the surfaces of the fins. This adhering and stagnant condensed water may narrow the air passage between the fins, reducing the amount of ventilation or causing noise. Furthermore, this condensed water sometimes scatters in the direction of ventilation, staining various parts of the air conditioner and the house.

For this reason, a method has conventionally been used in which the surface of the fin is made hydrophilic so that the condensed water flows down as a thin water film. As a method of making the material hydrophilic, for example, a method of applying a mixture of acrylic acid resin and water vitrification is known.

However, this flow-down method treats condensed water at the interface between the fins and the atmosphere (i.e., the surface of the fins), so changes in the surface condition of the fins (for example, accumulation of dust or adhesion of water-repellent substances) can cause condensed water to It had the inherent disadvantage that the flow of water was impeded. Furthermore, when an inorganic compound such as water glass is used for hydrophilic treatment, the presence of this inorganic compound tends to cause cracks and peeling of the coating when drilling or bending the fin. There were drawbacks.

Therefore, the inventors of the present invention made extensive studies to solve this problem, and in Japanese Patent Application No. 60-221645, they developed a fin material for heat exchangers in which a mixed layer of adhesive and superabsorbent resin powder was formed on the surface of the fin material body. Proposed. The proposed heat exchanger fin material absorbs condensed water into the surface layer of the fin (mixed layer of adhesive and super absorbent resin powder), and processes the condensed water in that layer. Moreover, since the surface layer is composed only of organic compounds, all of the above-mentioned drawbacks can be solved.

(c) Problems to be Solved by the Invention However, the super water-absorbing resin powder used in the proposal of Japanese Patent Application No. 60-221645 has an excessive ability to absorb and retain water, so the condensed water is The drawback was that it was difficult to flow down inside.

Furthermore, when a large amount of water is retained, the swollen super absorbent resin powder may fall off from the surface layer of the fin due to ventilation.

Therefore, the present invention eliminates the above drawbacks by applying a certain organic compound to the fin material body, which absorbs condensed water but has little ability to retain it, and the fins absorb condensed water quickly. The aim is to cause water to flow down into the surface layer of the surface.

(d) Means for Solving the Problems, That is, the present invention relates to a fin material for a heat exchanger characterized in that a mixed layer of adhesive and cellulose powder is formed on the surface of the fin material body. be.

Any material can be used for the fin body as long as it has good heat conductivity, but it is particularly suitable for its excellent heat conductivity, ease of various molding processes, and light weight. Aluminum sheet is most preferred.

As the adhesive, conventionally known adhesives, especially paint adhesives, can be used, such as thermosetting resin adhesives such as phenol resin, resorcinol resin, polyurethane resin, and epoxy resin, polyvinyl acetate, polyvinyl alcohol,
Thermoplastic resin adhesives such as polyvinyl butyral and polyacrylic esters can be used. Among these, copolymers consisting of acrylic acid and acrylic acid esters are particularly preferred because they have carboxylic acid groups in their side chains and are highly hydrophilic, and copolymers with hydroxyl groups in their side chains, such as polyvinyl alcohol and polyvinyl butyral, are particularly preferred. It is also preferable because it is highly hydrophilic.

As cellulose powder, powdered cellulose fibers such as bulbs and rayon are used. For example, microcrystalline cellulose obtained by steaming cellulose fibers in hydrochloric acid or cellulose fibers are swollen with an aqueous alkaline solution and diluted with water. Thereafter, a tsuka floc etc. obtained by spraying and drying is used. Among these, loin is particularly suitable for microcrystalline cells having a small particle size. this is,
This is because unevenness is less likely to occur on the surface of the mixed layer formed on the fin material main body. From this point of view, the particle size of cellulose powder, especially microcrystalline cellulose, is 0.1 to 2μ.
degree is preferred. The particle size of microcrystalline cellulose is measured by a sedimentation method.

The following method is used to form a mixed layer of adhesive and cellulose powder on the surface of the fin material main body.

First, an organic solvent (typically toluene or β-oxyethyl ether (hereinafter simply referred to as "cellosolve") is used to dissolve the adhesive.
Say. ). ), put cellulose powder and an adhesive (which may be in solid or liquid form) into it, and disperse the cellulose powder using a sand mill. Through this treatment, the cellulose powder is dispersed into fine particles having a particle size of about 1 μm or less. For example, in the case of microcrystalline cellulose, if the above treatment is performed using particles with a particle size of 3 to 10 microns, the particle size of the microcrystalline cellulose will be about 1 micron or less. The mixing ratio of the cellulose powder and the adhesive may be any desired as desired, but it is preferably about 50 to 1000 parts by weight of the adhesive to 100 parts by weight of the cellulose powder. Cellulose powder absorbs water, but organic solvents do not and are dispersed in their original form. The adhesive then becomes a solution.

In this way, a dispersion liquid in which cellulose powder and adhesive are uniformly mixed is obtained. Note that it is preferable to use a surfactant for dispersing the cellulose powder, since this improves the dispersibility. Thereafter, by applying the dispersion liquid to the surface of the fin material main body and drying it, a mixed layer of the adhesive and cellulose powder can be formed.

(E) Function When the fin material according to the present invention is used as a fin for a heat exchanger, condensed water is absorbed into the cellulose powder in the mixed layer formed on the surface of the fin.

The absorbed water gradually flows down due to its own weight and is removed from the surface of the fins.

Furthermore, when a mixed layer is formed using a high molecular weight polymer having a carboxylic acid group or a hydroxyl group in the side chain as an adhesive, since the adhesive is relatively hydrophilic, water moves through the adhesive and eventually through the mixed layer. It becomes easier to do.

(f) Example: Acrylic acid-acrylic acid ester copolymer (manufactured by NOF ■, trade name: Model Pearl) in 500 g of cellosolve 10
Microcrystalline cellulose with an average particle size of 0g and 7μ (
Add 50g of Asahi Kasei Kogyo (product name: Avicel),
A dispersion was obtained by stirring. This dispersion liquid was applied to a fin material body made of a thin aluminum plate with dimensions of 200 m x 300 m and 0.13 mm thick, and dried to form a mixed layer of adhesive and microcrystalline cellulose. The thickness of the mixed layer was 0.002 vxx.

A predetermined perforation process was performed on this fin material and it was attached as a fin of a heat exchanger. As a result, condensed water was immediately absorbed into the microcrystalline cellulose of the mixed layer without any water appearing on the surface of the fins. Furthermore, the excess water formed a thin film and continued to flow down, and no microcrystalline cellulose was observed to fall off.

(G) Effects of the Invention The fin material according to the present invention has only an organic polymer coated on its surface, and no inorganic compound is present. It is possible to prevent cracks from occurring in the coating film (mixed layer of adhesive and superabsorbent resin powder) of the fin material, and it is possible to improve the durability of the coating film and, in turn, the durability of the fin material.

Furthermore, the fins obtained using the fin material according to the present invention are
Rather than treating condensate on its surface, the surface layer (
Since this is carried out in the fin surface (mixed layer), even if dust or water-repellent substances adhere to the fin surface, condensed water can be quickly removed from the fin surface.

Moreover, the surface layer of the fin material according to the present invention is
Since cellulose powder is used instead of the super absorbent resin powder used in the proposal related to No. 21645, even if it absorbs condensed water, its ability to retain it is small, and the water quickly flows down due to its own weight. Therefore, condensed water can be quickly removed from the fin surface. Furthermore, cellulose powder has a lower swelling degree than superabsorbent resin powder,
It is less likely to fall off the fin surface due to ventilation.

When a high molecular weight polymer having a carboxylic acid group or a hydroxyl group in the side chain is used as the adhesive in the mixed layer, water absorbed by the cellulose powder on the surface of the mixed layer easily moves into the mixed layer, and the inside of the mixed layer The water absorption capacity of the cellulose powder present in the mixed layer can be fully utilized, and therefore the water absorption capacity of the mixed layer can be improved. Furthermore, since the flowability of water in the mixed layer due to its own weight is improved, condensed water can be removed more quickly.

Claims (4)

[Claims] (1) A fin material for a heat exchanger, characterized in that a mixed layer of adhesive and cellulose powder is formed on the surface of the fin material body. (2) The fin material for a heat exchanger according to claim (1), wherein a high molecular weight polymer having a carboxylic acid group or a hydroxyl group in the side chain is used as the adhesive. (3) The fin material for a heat exchanger according to claim (1), which uses microcrystalline cellulose powder as the cellulose powder. (4) The particle size of the microcrystalline cellulose powder is 0.
The fin material for a heat exchanger according to claim (3), which has a particle diameter of 1 to 2μ.