JPS63289074A - Fin material for heat exchanger - Google Patents

Abstract

PURPOSE:To obtain the title fin material protected from formation of cracks during, e.g., bending and from stagnation of condensed water and excelling in hydrophilicity and durability, by forming a film containing a specified silicon compound on the surface of the body of a fin material. CONSTITUTION:The surface of the body of a light fin material (A) which is preferably excellent in heat transfer property and moldability, such as a thin aluminum sheet, is coated with a solution formed by dissolving 100pts.wt. film- forming composition (B) comprising a mixture of a film-forming substance such as an acrylic resin or a water-soluble melamine resin, a curing catalyst, PVA and a metal compound which forms a chelate compound of PVA by coordination and 10-40pts.wt. silicon compound (C), as a hydrophilicity-imparting agent, of the formula [wherein R1 is CH3, C2H5 or beta-methoxyethyl group, R2 is CH3 or OR1, and A is vinyl, beta-(3,4-epoxycyclohexyl)ethyl, gamma-glycidoxypropyl, gamma-methacryloxy, gamma-aminopropyl or the like] in water or an organic solvent and dried.

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 for making the surface hydrophilic, for example, a method of applying a mixture of a film-forming substance such as an acrylic resin and water glass is known. That is, this method attempts to make the surface of the fin hydrophilic by forming a film on the surface of the fin body and mixing water glass, which is a hydrophilic substance, into the film.

(c) Problems to be solved by the invention However, although this method is somewhat satisfactory in terms of hydrophilization,
Cracks occur when the fin material is subjected to drilling or bending, and the film on the surface of the fin material is easily damaged. This is thought to be because inorganic compounds are mixed in the film.

Therefore, the inventors of the present invention made extensive studies to solve this problem, and found that a specific organic hydrophilic agent was mixed into the film formed on the surface of the fin material (thereby, the occurrence of cranking could be prevented). The inventors discovered that it is possible to obtain a fin material that has a surface that is both hydrophilic and sufficiently hydrophilic, leading to the present invention.

(d) Means and effects for solving the problem, that is, the present invention is characterized in that a film containing a silicon compound represented by the following general formula (I) is formed on the surface of the fin material main body. This is a fin material related to heat exchangers.

General formula (I); represents a group selected from the group consisting of xy-ethyl group, R2
represents a methyl group or an OR group, and A is a vinyl group.

β-(3,4-epoxycyclohexyl)-ethyl group.

From the group consisting of γ-glycidoxypropyl group, γ-methacryloxypropyl group, N-β(aminoethyl)-γ-aminopropyl group, γ-aminopropyl group, γ-chloropropyl group and γ-mercaptopropyl group Represents a selected group. ) For the fin material body, any material can be used as long as it has good heat conductivity, but it is particularly important to have excellent heat conductivity, ease of various molding processes, and light weight. A thin aluminum plate is most preferred.

As the film-forming substance used to form the film, conventionally known resins such as acrylic acid resins, melamine resins, epoxy resins, phenol resins, and polyamide resins are used. Among these, acrylic acid resin is preferred because it has excellent adhesion to the aluminum fin material body.

In addition, as a film-forming substance, a mixture (hereinafter referred to as "
"Film-forming composition". ) is also preferable.

This is because the strength of the film is improved and the hydrophilicity of the film itself is also improved.

Here, the film-forming composition will be explained in some detail as follows.

As the water-soluble melamine resin, either a commercially available monomer resin or a multimer resin such as a dimer type resin with a certain degree of polycondensation may be used. Ammonium chloride is used as a curing catalyst for water/cold melamine resin.

Ammonium salt catalysts such as diammonium phosphate and ammonium sulfaminate, hydrochloric acid or sulfamate salts of organic amino alcohols, organic amine salt catalysts such as dimethylaniline hydrochloride, pyridine-hydrochloric acid, picoline-monochloroacetic acid, magnesium chloride , zinc chloride, zinc sulfate, and other inorganic metal catalysts. Among them, it is preferable to use an organic amine salt catalyst. The water-soluble melamine resin becomes a three-dimensional network polymer by its curing catalyst, and forms the main body of the film formed on the surface of the fin material main body.

As the polyvinyl alcohol, any commercially available completely saponified type, intermediately saponified type, or partially saponified type can be used, but it is preferable to use the completely saponified type for the purpose of manufacturing with good reproducibility of performance as a support in printing. Polyvinyl alcohol is insolubilized by a metal compound that is coordinated to the polyvinyl alcohol to form a chelate compound. Zirconium nitrate is generally used as this metal compound, but other zirconium salts can also be used. Polyvinyl alcohol mainly improves the hydrophilicity of the film.

The quantitative proportions of each component in this film-forming composition are preferably as follows. The amount of polyvinyl alcohol is
50 to 200 per 100 parts by weight of water-soluble melamine resin
Approximately 80 to 180 parts by weight, preferably 80 to 180 parts by weight. If the amount of polyvinyl alcohol is less than 50 parts by weight, the surface layer tends to lack hydrophilicity, and if it exceeds 200 parts by weight, the surface layer may dissolve and cause printing stains. The amount of the metal compound that is coordinated with polyvinyl alcohol to form a chelate compound is 2 to 10 parts by weight, preferably 4 to 7 parts by weight, per 100 parts by weight of polyvinyl alcohol. If the amount of the metal compound is less than 2 parts by weight, the insolubilization of polyvinyl alcohol tends to be incomplete, and if it exceeds 10 parts by weight, the hydrophilicity of the film tends not to improve.

Further, the amount of the curing catalyst for the water-soluble melamine resin may be any amount sufficient to cure the water-soluble melamine resin (for example, 0.1 to 100 parts by weight of the water-soluble melamine resin).
5 parts by weight.

The silicon compound that is the hydrophilizing agent used in the present invention is represented by the above general formula (I). Specifically, vinyltriethoxysilane, vinyltris(β-methoxy-ethoxy)silane, β-(3,4-epoxycyclohexyl)-ethyltrimethoxysilane, r-glycidoxyprobyltrimethoxysilane, T-methacrylate Roxypropyltrimethoxysilane, N-β(aminoethyl)-T-
Aminopropyltrimethoxysilane, N-β(aminoethyl)-di-aminopropylmethyldimethoxysilane,
T-aminopropyltriethoxysilane.

Examples include γ-chloropropyltrimethoxysilane and T-mercaptopropyltrimethoxysilane. Among these, it is particularly preferable to use N-β(aminoethyl)-7-aminopropyltriethoxysilane.

To form a film on the surface of the fin material, a solution of a film-forming substance and a silicon compound dissolved in water or an organic solvent is applied to the surface of the fin material, and then dried to evaporate the water or organic solvent. Just let it happen. Organic solvents include benzene, toluene, and xylene.

Ethylbenzene, ethylene glycol, propylene glycol, diethylene glycol, dimethylformamide, etc. are used.

The mixing ratio of the film-forming substance and the silicon compound is preferably about 10 to 40 parts by weight of the silicon compound per 100 parts by weight of the film-forming substance. If the amount of the silicon compound is less than 10 parts by weight, the degree of hydrophilicity of the formed film tends to be low, and if it exceeds 40 parts by weight, the strength of the film tends to decrease, resulting in the formation of cracks in the film or There is a tendency for the film to peel off. In addition, when preparing a solution by dissolving a film-forming substance and a silicon compound in water or an organic solvent, add 1 to 5 parts by weight of the film-forming substance and silicon compound to 100 parts by weight of water or organic solvent. Generally, it is melted to some extent.

(e) Examples Example 1 First, a solution having the following composition was prepared.

Polymethyl methacrylate 2 parts by weight N-β (
(aminoethyl)-T-aminopropyltrimethoxysilane 0.5 parts by weight xylene
100 parts by weight of this solution was added to 20cia
Coated on the surface of a thin aluminum plate of
A fin material was obtained by drying.

In order to evaluate the hydrophilicity of the surface of this fin material, the contact angle with water (measured with a goniometer) was measured. As a result, the contact angle was 20 degrees.

Example 2 First, a solution having the following composition was prepared.

Water-soluble melamine resin 1 part by weight Guanidine sulfamate 0.005 parts by weight Polyvinyl alcohol 1 ffi 1 part Zirconium nitrate 0.06 parts by weight N-β (aminoethyl)-T-aminopropyltrimethoxysilane
0.5 parts by weight water
100 parts by weight of this solution was applied to the surface of a 20 cm x 3 Q cm aluminum thin plate, and then dried at 100'C to obtain a fin material.

In order to evaluate the hydrophilicity of the surface of this fin material, the contact angle with water (measured with a goniometer) was measured. As a result, the contact angle was 15 degrees.

Example 3 A fin material was obtained in the same manner as in Example 2, except that T-glycidoxypropyltrimethoxysilane was used instead of N-β(aminoethyl)-γ-aminopropyltrimethoxysilane, and the same method was used. When hydrophilicity was evaluated using a method, the contact angle was 18 degrees.

Comparative Example 1 A fin material was obtained in the same manner as in Example 1, except that a solution having the following composition was used, and its hydrophilicity was tested.

Polymethyl methacrylate 2 parts by weight Xylene 100 parts by weight As a result, the contact angle with water was 35 degrees.

Comparative Example 2 A fin material was obtained in the same manner as in Example 2, except that a solution having the following composition was used, and its hydrophilicity was tested.

Water-soluble melamine resin 1 part by weight Guanidine sulfamate 0.005 part by weight Polyvinyl alcohol Lib part Zirconium nitrate
0.06 parts by weight water
100 parts by weight As a result, the contact angle with water is 30
It was degree.

As is clear from the above, the hydrophilicity of the surface of the fin materials obtained in Examples 1 to 3 was higher than that of Comparative Example 1 or 2.
It turns out to be excellent.

(F) Effects of the Invention The film formed on the surface of the fin material according to the present invention is mainly composed of an organic substance and has extremely excellent hydrophilicity. Therefore, it is not necessary to use an inorganic compound such as water glass in the film on the surface of the fin material in order to improve the hydrophilicity of the fin material. It is possible to prevent the occurrence of cranking and improve the durability of the film and, in turn, the durability of the fin material.

Claims (1)

[Scope of Claims] A fin material for a heat exchanger, characterized in that a film containing a silicon compound represented by the following general formula (I) is formed on the surface of the fin material main body. General formula (I); ▲Mathematical formulas, chemical formulas, tables, etc.▼(I) (In the formula, R_1 represents a group selected from the group consisting of methyl group, ethyl group, and β-methoxy-ethyl group, and R_2 represents Represents a methyl group or an OR_1 group, A is a vinyl group, β-(
3,4-epoxycyclohexyl)-ethyl group, γ-glycidoxypropyl group, γ-methacryloxypropyl group, N-β(aminoethyl)-γ-aminopropyl group, γ
- Represents a group selected from the group consisting of aminopropyl group, γ-chloropropyl group, and γ-mercaptopropyl group. )