JPH07188585A - Fine fiber-containing hydrophilic treating agent, and fin material made of al or al alloy treated with the same treating agent for heat exchanger - Google Patents

Abstract

PURPOSE:To provide a hydrophilic treating agent providing a coating film capable of maintaining excellent water wetting properties even in the case of long-term repetition of moisture condensation operation and drying operation of a heat exchanger and a fin material made of Al or an Al alloy capable of providing high heat exchange efficiency with small pressure loss in use by forming a hydrophilic coating film with the treating agent on the surface of the fin. CONSTITUTION:This hydrophilic treating agent contains hydrophilic fine fibers, one or more of water-soluble or water-dispersible resins and a surfactant or further one or more cross-linking agents selected from the group consisting of a cross-linkable reactive group-containing resin, an isocyanate compound and a coordinating metal element-containing compound and is capable of providing the surface of a substrate with hydrophilic nature by coating. A fin material made of Al or an Al alloy is obtained by applying the hydrophilic treating agent to the surface of the fin material.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a hydrophilic treatment agent containing fine fibers and a hydrophilic film formed on the surface by using this agent to improve the water film forming property, thereby improving the heat exchange efficiency due to the adhesion of water droplets. Al or A for heat exchangers that prevents deterioration
The present invention relates to a fin material made of an alloy.

[0002]

2. Description of the Related Art Since Al or Al alloy is excellent in heat conductivity, formability and corrosion resistance, it is widely used as a fin material for heat exchangers. It has been pointed out that when used, the adherence and retention of condensed water reduces ventilation resistance, which lowers heat exchange efficiency. Therefore, the surface of the Al or Al alloy material in the state of the plate before being formed as the fins for the heat exchanger is subjected to a hydrophilic treatment to improve the water wettability so that the condensed water forms a water film and easily flows downward. To reduce the ventilation resistance when assembled and used as a heat exchanger, improve heat exchange efficiency, and prevent power loss, noise, and splashes of water droplets. There is.

As a method for hydrophilizing the surface, (1) a method of applying water glass (for example, JP-A-58-12698).
No. 9, etc.), (2) Organic resin such as silica, water glass,
A method for forming a film containing aluminum hydroxide, calcium carbonate, titania or the like, or a hydrophilic film containing a surfactant added thereto (for example, JP-A-55-99).
976, JP-A-60-101156, etc.),
(3) A method of applying boehmite or alumina treatment (for example, JP-A-56-20971), (4) a water-soluble or water-dispersible organic resin such as a hydrophilic acrylic resin or water-soluble cellulose, and a crosslinking agent or A method of applying a coating solution containing a surfactant, a chelating agent, etc. (see, for example, JP-A-62-62).
-186198) and the like are known, and some of them have already been put to practical use.

However, the above method has the following drawbacks. That is, in the above methods (1) to (3), since the main component that exhibits hydrophilicity is an inorganic hydrophilic coating, the ductility of the coating is poor, and overhang molding or ironing molding during fin-shaped molding is performed. Sometimes, a crack is formed in the film, which may propagate to the material and cause a crack in the Al or Al alloy substrate. That is, as compared with the untreated material which is not surface-treated, the inorganic surface treatment significantly deteriorates the moldability.

On the other hand, as shown in (4) above, an organic hydrophilic surface prepared by blending a surfactant with a water-soluble or water-dispersible resin such as acrylic or cellulose-based, vinyl alcohol-based or urethane-based resin. If a treatment agent is used,
Since the organic film has ductility, it does not adversely affect the formability of the material like the inorganic film.

However, although this organic film has a good initial hydrophilicity, when the heat exchanger is continuously used, dew condensation on the fins causes water to gradually elute the hydrophilizing agent due to flowing water, or during dry operation. Adhesion of oil in the air causes water repellency, making it impossible to maintain a hydrophilic surface. That is, in order to maintain the hydrophilicity for a long period of time, it is necessary to establish a surface treatment method capable of exhibiting excellent water wettability even when the dew condensation operation and the drying operation are repeated.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and its purpose is to provide excellent wettability even when the condensation operation and the drying operation are repeated for a long period of time. It is intended to provide a hydrophilic treatment agent capable of forming a film capable of sustaining the above, and an Al or Al alloy fin material for a heat exchanger having a hydrophilic film formed on the surface by the treatment agent.

[0008]

The constitution of the hydrophilic treatment agent according to the present invention which has been able to solve the above-mentioned problems is as follows: hydrophilic fine fibers (P), at least one water-soluble or water-dispersible resin (Q). ) And a surfactant (R), or in addition to these, at least one cross-linking agent selected from the group consisting of a cross-linkable reactive group-containing resin, an isocyanate compound and a coordinating metal element-containing compound ( S) is contained in the gist of the present invention, and by applying these hydrophilic treatment agents to the surface of the base material to form a hydrophilic film, Al or Al for a heat exchanger having excellent performance is formed. An alloy fin material can be obtained.

[0009]

The present invention is constituted as described above, but in short, by applying it to various substrate surfaces, it is possible to obtain excellent hydrophilicity and its durability on the surface without adversely affecting the moldability of the substrate. It is capable of forming a coating provided, and particularly Al or Al alloy for heat exchangers (hereinafter represented by Al).
By applying to the surface of the fin-making material, a fin material having excellent heat exchange efficiency can be obtained.

The hydrophilizing agent in the present invention contains hydrophilic fine fibers (P), at least one water-soluble or water-dispersible resin (Q) and a surfactant (R) as essential components, or In addition to these, crosslinkable reactive group-containing resin,
It contains at least one crosslinking agent (S) selected from the group consisting of an isocyanate compound and a compound containing a coordinating metal element.

The fine fibers (P) used here have the effect of roughening the surface of the hydrophilic film and increasing the apparent surface area to enhance hydrophilicity and physically enhance water wettability. . That is, they are 2
Secondary aggregation occurs, and it is difficult to obtain a fine hydrophilic film having surface irregularities, but fine fibers do not move freely in the treatment liquid due to the entanglement of fibers, and secondary aggregation does not occur. As a result, the surface of the hydrophilic film can be uniformly roughened, and the surface area increasing effect can be more effectively exhibited, and the hydrophilic film strengthening effect by the fine fibers is also exhibited, and cracks during processing It also has the effect of suppressing the occurrence.

The preferred hydrophilic fine fibers (P) used herein include fine fibers which are hydrophilic and excellent in flexibility such as cellulose, polyvinyl alcohol, polyacrylamide and the like, and these are used alone. Besides, it is also possible to mix and use two or more kinds.
The fiber diameter should be selected to be 3 μm or less, preferably 1 μm or less and to be well dispersed in water.

Incidentally, organic fibers having poor hydrophilicity such as polyester, nylon and polyolefin are not preferable because they deteriorate the hydrophilicity of the hydrophilic film and hinder water wettability. In addition, inorganic fine fibers or whiskers such as metal or ceramics are not recommended because they usually have high rigidity and tend to impair the moldability of the substrate.

The water-soluble or water-dispersible resin (Q) acts as a matrix component or a binder component of the fine fibers (P), and is a main component that imparts hydrophilicity to the film, and its adhesiveness to the substrate is high. From the viewpoint of good and moldability, those capable of forming a film having excellent flexibility are preferable, and examples thereof include poly (meth) acrylic acid, alkali metal salts of poly (meth) acrylic acid, and poly (meth).
A copolymer of acrylic acid and polyvinyl acetate, a copolymer of poly (meth) acrylic acid and polyvinyl alcohol,
Copolymer of poly (meth) acrylic acid and polyethylene oxide, Copolymer of poly (meth) acrylic acid and cellulose, Copolymer of poly (meth) acrylic acid and starch, Cellulosic resin (hydroxypropyl cellulose , Carboxymethyl cellulose, water-soluble cellulose such as methyl cellulose), poly (meth) acrylamide,
Examples include poly (meth) acrylamidomethylpropane sulfonic acid, polyvinyl alcohol, partially saponified polyvinyl acetate, water-soluble urethane, water-dispersible urethane resin, polyamide, and copolymers of (meth) acrylic acid and polyamide. These can be used as a homopolymer or a copolymer, or as a mixture of two or more kinds.

The surfactant (R) mainly serves to improve the initial hydrophilicity and to prevent the hydrophilicity from being deteriorated by the adsorption of the press oil applied during the fin-shaped forming process. Therefore, as long as it is used as a fin material, the initial hydrophilicity can be increased, and if the press oil or the like adsorbed when flowing out together with the water condensed on the fins can be accompanied and discharged, there is no limitation on the kind. Alternatively, anionic, nonionic, cationic, or amphoteric surfactants may be used. Typical examples are anionic sulfonates such as alkyl sulfonates and polyoxyethylene alkylphenyl ether sulfates; nonionics are polyoxyethylene alkylphenyl ethers and polyoxyethylene / polyoxypropylene copolymer fatty acids. Examples include esters and the like; cationic amines such as alkylamine salts and alkylmethyltrimethylammonium chloride; amphoteric examples include alkylaminopropionate and alkyldimethylbetaine.

The essential components of the hydrophilizing agent in the present invention are the above-mentioned three components, and it is also effective to add a crosslinking agent (S) in addition to these to further enhance the characteristics. That is, the cross-linking agent has the effect of further enhancing the hydrophilicity sustainability of the film. Therefore, it is important for the hydrophilic film to have durability of hydrophilicity, that is, long-term hydrophilic lasting at the same time as initial hydrophilicity, and in order to obtain a film having long-term hydrophilic lasting, Adhesion to the substrate should be good. In order to secure long-term adhesion between the hydrophilic film and the substrate (Al material, etc.), the molecular weight of the water-soluble or water-dispersible resin (Q) is increased so that it is entrained in the condensed water on the fin surface. It is necessary to prevent the outflow. Further, it is also effective to improve the adhesiveness by bonding the hydrophilic film and the substrate or, if necessary, the corrosion resistant film formed as the undercoat layer. In order to enhance such an increase in molecular weight and / or an improvement in adhesion to the substrate,
It is extremely effective to add an appropriate amount of the crosslinking agent (S).

The crosslinking agent (S) used here is
Amino resins such as melamine, isocyanate compounds, organic resins having crosslinkable reactive groups such as epoxy resins, metal salts or metal complexes containing organic chelates such as Ti, Zr, Al, Zn, or ionomer-forming metals, organic compounds. Examples include alkoxide compounds and the like known as coordination compounds,
These may be used alone or in combination of two or more if necessary. These cross-linking agents cause a cross-linking reaction or coordinate bond with the water-soluble or water-dispersible resin (Q) to increase the molecular weight of the film-constituting resin, thereby enhancing the hydrophilic sustainability as described above and forming a base film. Adhesion is further enhanced.

The mixing ratio of the above components (P) to (S) is not particularly limited, but the ratio is preferably the ratio of the fine fiber-containing hydrophilic treatment agent in the total solid component, and the component (P) is 6%.
-84% by weight, more preferably 9-66% by weight, component (Q) is 12-85% by weight, more preferably 25-82%.
% By weight, component (R) is 0.1-46% by weight, more preferably 0.5-30% by weight, component (S) is 0.1-46% by weight, more preferably 0.5-30% by weight Is the range. Further, if necessary, a fungicide, an antibacterial agent, a deodorant, etc., for the purpose of preventing the corrosion of fin material and the generation of unpleasant odor,
It is also effective to add it within a range that does not impair the hydrophilicity and its durability.

The fin material made of Al or Al alloy for heat exchanger of the present invention is formed by coating the surface of the fin material with the above-described hydrophilic treatment agent containing fine fibers, and usually heat-treating at about 150 to 230 ° C. Can be obtained by doing. The thickness of the coating varies depending on the conditions of use as a heat exchanger and the like, but is generally about 0.5 to 5 μm, preferably about 0.5 to 2 μm. The Al material is
Although it may be a flat plate having an arbitrary length, it is preferable to continuously process and process using a long product wound in a coil shape in consideration of productivity and the like. At this time, Al
It is preferable to form a chromate film, an organic resin film, a chromium compound-containing organic film, or the like as the first layer having corrosion resistance on the surface of the material in advance, since a fin material having both corrosion resistance and hydrophilicity can be obtained.

[0020]

EXAMPLES Hereinafter, the constitution and working effects of the present invention will be described more specifically with reference to examples, but the present invention is not limited by the following examples, and is applicable to the gist of the preceding and the following. It is also possible to carry out appropriate modifications within the range to be obtained, and all of them are included in the technical scope of the present invention.

EXAMPLE As an Al material, JI of 0.1 ^t × 100 ^w × 200 ^l mm
Using SA-1100H204, the Al plate was degreased and washed according to a conventional method before use. A first undercoating layer is provided on the Al material, and various fine fiber-containing hydrophilic treatment agents are applied thereon as shown in Tables 1 and 2, followed by heating and drying at 200 ° C. for 30 seconds to give a thickness of about 1 μm. A hydrophilic film having fine surface irregularities was formed to obtain test pieces of Examples 1-18. The obtained test pieces were subjected to various performance evaluation tests to evaluate their usefulness as fin materials for heat exchangers. Further, after providing a first undercoating layer on the surface of an Al plate that has been degreased and washed with water in the same manner as above, a surface coating is formed in the same manner as above to obtain test pieces of Comparative Examples 1-9. Similarly, the usefulness as a fin material for a heat exchanger was evaluated.

Each test piece was coated with a press oil (press oil kinematic viscosity 9.0 cSt / 40 ° C.) → solvent degreasing (1, 1, 1
-Trichloroethane cold bath 1 minute-> steam 1 minute)-> hydrophilicity persistence evaluation is performed in this order, and hydrophilicity persistence is evaluated by running water (running water 5
Liter / Hr × 8Hr → heat drying (80 ° C × 16H)
The cycle of r) was evaluated by hydrophilicity after repeating 8 cycles. The hydrophilicity was evaluated by the water repellent state after spraying water, the corrosion resistance was evaluated by the surface state after 10 days of the salt spray test, and the moldability evaluation was evaluated by the presence or absence of cracking in the bent portion when burned. .

The results are shown in Tables 1 and 2. The symbols used in the columns of Tables 1 and 2 have the following meanings. First layer treatment column A: Phosphoric acid chromate coating B: Acrylic resin coating C: Epoxy resin coating D: Acrylic melamine resin coating Resin column for hydrophilic coating A: Polyacrylic acid-polyvinyl alcohol copolymer B: Polyvinyl alcohol C: CMC (carboxymethyl cellulose Na salt) D: polyacrylic acid E: hydroxypropyl cellulose F: polyamide additive column A: cellulose fine fiber B: polyvinyl alcohol fine fiber C: nylon fine fiber D: tyranno fine fiber E: silicon carbide whiskers F : Polyacrylic acid fine particles G: Zeolite fine particles H: Silica fine particles Surfactant column A: Polyoxyethylene alkylphenyl ether B: Sodium benzenesulfonate C: Polyoxyethylene / polyoxypropylene copolymer D: Maleic acid modified po Lioxyethylene cross-linking agent column A: Ammonium zirconium carbonate

[0024]

[Table 1]

[0025]

[Table 2]

[0026]

As described above, according to the present invention, even when the condensation operation and the drying operation of the heat exchanger are repeated for a long period of time, a hydrophilization that gives a film that can maintain excellent water wettability is obtained. By forming a treatment agent and a hydrophilic film on the surface by the treatment agent, it is possible to provide an Al or Al alloy fin material for a heat exchanger, which has less pressure loss during use and can obtain high heat exchange efficiency. It was

Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display area C09D 7/12 PSL PSM F28F 1/12 G

Claims (3)

[Claims] 1. A hydrophilic fine fiber (P), at least one water-soluble or water-dispersible resin (Q) and a surfactant (R).
A hydrophilizing agent containing fine fibers, which comprises: 2. One or more cross-linking agents (S) selected from the group consisting of a cross-linkable reactive group-containing resin, an isocyanate compound and a coordinating metal element-containing compound as other components.
The hydrophilic treatment agent according to claim 1, which comprises: 3. A fin material made of Al or an Al alloy for a heat exchanger, characterized in that a hydrophilic film is formed on the surface of the treatment agent according to claim 1 or 2.