JP3335285B2 - Pre-coated 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 a fin material for a heat exchanger of a room air conditioner and the like and a paint used therefor.
In particular, the present invention relates to a heat exchanger plate fin material excellent in hydrophilicity and lubricity and a paint used therefor.

[0002]

2. Description of the Related Art In a heat exchanger used for a room air conditioner or the like, an aluminum fin material is used to enhance heat radiation. In recent years, along with downsizing and energy saving of room air conditioners and the like, various studies have been made on improving the heat exchange rate, and fins are required to be hydrophilic. this is,
If water droplets adhere to the fin surface during the cooling operation and a bridge is formed between the fins, the resistance of gas such as air passing between the fins increases, and the cooling efficiency decreases. In order to solve this problem, the contact angle of the water droplet on the fin surface is made very small, and the water is allowed to flow down as a water film to prevent the formation of the water droplet. Further, in order to increase productivity, instead of the conventional post-coat which is subjected to a hydrophilic treatment after forming and assembling the fins, a pre-coating in which an aluminum coil is subjected to a hydrophilic treatment in advance and molded is being advanced. As a result, aluminum fin materials have been required to have moldability as well as hydrophilicity.

[0003] Regarding hydrophilicity, the surface of an aluminum fin material is subjected to a chemical conversion treatment (chromate treatment, boehmite treatment, etc.), and then an inorganic hydrophilic material such as water glass or colloidal silica, mainly silicic acid or silicate. It is widely practiced to form a hydrophilic film by coating, baking or dipping treatment to enhance the hydrophilicity of the fin surface.

[0004] However, such inorganic coatings are hard and difficult to mold due to the lack of elongation of the coating, and the molds are severely worn. For this reason, the following various improvements have been made to achieve both hydrophilicity and moldability.

JP-A-4-198287: Organic resin 10
0.1 to 5 μm of a coating material containing 5 to 200 parts by weight of silica particles having a particle size of 0.05 to 2 μm and 2 to 100 parts by weight of organic resin particles having a particle size of 0.1 to 10 μm with respect to 0 part by weight. Apply to thickness. JP-A-5-31123: 100 parts by weight of a resin other than the water-soluble amino resin, 5 to 50 parts by weight of the water-soluble amino resin, 5 to 150 parts by weight of silica fine particles having a particle size of 0.05 to 2 μm,
A coating containing 20 to 150 parts by weight of a surfactant having an HLB of 8 to 18 is applied to a thickness of 0.1 to 5 μm. In the methods of these inventions, silica particles and organic resin particles are mixed and arranged on the surface of the coating film, or the silica particles are dispersed in the base resin, the silica particles are exposed on the surface of the base resin, and the silica particles A surfactant is present in the form of covering the surface of the exposed base resin layer, and the silica particles exposed on the surface provide hydrophilicity, and the organic resin particles or the surfactant also exposed on the surface provide mold abrasion or lubricity. Has been improved. But,
Hard silica particles are easily exposed on the surface of the coating film, and the wear of the mold cannot be prevented. In addition, the area occupied by the silica particles having hydrophilicity occupying the coating film surface is reduced, so that the hydrophilicity is not sufficiently exhibited. In addition, when the mixing ratio of the organic resin component is increased to improve the moldability, the coating film tends to burn when the copper pipe of the heat exchanger is brazed, and the working environment is deteriorated due to the burning smell, and the hydrophilic property is deteriorated. Problems, such as a decrease in the surface area.

JP-B-2-42389: 0.1 to 5 parts by weight of a low molecular weight organic compound having a carbonyl group such as an aldehyde, or 1 part by weight of an alkali silicate, or polyacrylic acid or polyvinyl alcohol; A water-soluble organic high molecular compound such as polyoxyethylene glycol is used in 0.1.
A coating material in an amount of from 1 to 5 parts by weight is applied. Japanese Patent Publication No. 48875/1992: A coating material containing 0.1 to 5 parts by weight of an inorganic curing agent and 0.5 to 5 parts by weight of a water-soluble organic polymer compound is applied to 1 part by weight of an alkali silicate. In these methods, the silicate disperses in the coating film and comes into contact with the mold, preventing the abrasion of the mold, and increasing the proportion of the organic polymer in order to increase the flexibility of the film. Since the amount of elution increases and the silicate dispersed at the same time elutes, the hydrophilicity tends to decrease, so-called "hydrophilic persistence".
Decrease occurs.

[0007] Japanese Patent Publication No. 1-2785: A mixture of wax and a water-soluble polymer compound is applied on a hydrophilic film.
Further, a lubricating layer based on a liquid surfactant is provided. JP-B-2-25692: A water-soluble sodium or potassium salt of a higher fatty acid is applied on a hydrophilic surface-treated film. JP-A-4-68300: A mixture obtained by mixing a surfactant or an organic polymer and an alkali silicate in a weight ratio of solid content of 5: 1 to 1: 1 is applied on an inorganic hydrophilic film. JP-A-6-39347: hydrophilic lubricant (polyethylene glycol, polyoxyethylene alkyl ether, polyoxyethylene alkyl ester, etc.) on a hydrophilic film
Is applied. According to these methods, since a sufficient amount of the hydrophilic lubricating layer is formed on the outermost layer, it is possible to satisfy both moldability and hydrophilicity. However, multi-stage processing is required to provide a large number of coating layers, and the number of steps is increased, resulting in poor productivity. In addition, when a liquid having lubricity is provided on the hydrophilic film layer, repelling may occur, or the thickness of the lubricating layer may easily vary, so that sufficient moldability may not be ensured.

[0008]

SUMMARY OF THE INVENTION The present invention is excellent in lubricity and formability, and has good hydrophilicity and long-lasting property even when a volatile press oil having a low viscosity is used. It is an object of the present invention to provide a fin material for a heat exchanger free of cost.

[0009]

Means for Solving the Problems The inventors of the present invention have conducted various studies to solve the above problems, and as a result, have arrived at the present invention. The present invention is a silicate, a water-soluble organic material, by baking coating of a specific composition of an organic resin on an aluminum plate, the outer surface of the film is formed of a water-soluble organic material, the film adhesion, hydrophilicity, lubricity and It is an aluminum plate for pre-coated fins provided with a film having excellent moldability, and is a paint and a coating method. That is, the present invention relates to a method in which A.I. B. Silicic acid or alkali metal silicate 8 to 500 mg / m ² , -OH group, -COOH
Having one or more of a group, an epoxy group, a phosphoric acid group, a sulfonic acid group, a metal salt thereof, a neutralized product with monoethanolamine or the like, or an ester.
0 to 5000 water-soluble organic matter 20 to 3125 mg / m
² , C.I. A film comprising ⁵ to 125 mg / m ^{2 of} an organic resin comprising at least one of polyacrylic acid, polymethacrylic acid, polyhydroxyacrylic acid or a salt or ester thereof or a copolymer thereof; It is a precoated fin material for heat exchangers having excellent hydrophilicity and lubricity. Further, in the second invention, the concentration of the water-soluble organic substance (B) in the film gradually increases from the surface of the aluminum plate, and the outermost surface of the film is composed only of the water-soluble organic substance. And a precoated fin material for heat exchangers having excellent lubricity. Further, the third invention is described in A.I. Silicic acid or alkali metal silicate, B. -O
Having a molecular weight of 100 to 5,000 having at least one of an H group, a -COOH group, an epoxy group, a phosphoric acid group, a sulfonic acid group, a metal salt thereof, a neutralized product with monoethanolamine, or an ester; Water-soluble organic substances, C.I. One of polyacrylic acid or polymethacrylic acid or polyhydroxyacrylic acid or a salt or ester thereof
Organic resin consisting of at least one kind or a copolymer thereof,
Silicic acid or alkali metal silicate (A) is converted to silicic acid content of 150 to 50 parts by weight with respect to 100 parts by weight of organic resin (C).
It is a paint for a heat exchanger plate fin excellent in hydrophilicity and lubricity, comprising 0 parts by weight and 3 to 5000 parts by weight of a water-soluble organic substance (B). Further, in the fourth invention, the paint according to claim 3 is applied to an aluminum material,
This is a method for producing a precoated fin for a heat exchanger having excellent hydrophilicity and lubricity, which is characterized by performing hot air drying at 50 ° C. for 4 to 120 seconds.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described.

First, the inorganic component of the coating composition will be described. The inorganic component is added to impart long-term hydrophilicity to the film. As the inorganic component, silicic acid or an alkali metal silicate, more specifically, water glass is preferable. When an alkali metal silicate is used, the ratio of silicic acid to alkali metal is preferably (silicic acid / alkali metal) ≧ 1, preferably 2 to 5. If it is less than 1, the alkali metal content is too large for silicic acid, and the erosive action of aluminum increases. However, if it exceeds 5, the silicic acid content becomes too large and the film becomes brittle, which is not preferable.

Next, the organic resin will be described. In order to improve the water resistance of the film, a resin component which is compatible with the alkali metal silicate and does not float on the air side during application and baking of the paint is added. Specific examples of the resin component include polyacrylic acid, polymethacrylic acid, polyhydroxyacrylic acid, one of salts or esters thereof, and copolymers thereof.

Next, the water-soluble resin will be described. A water-soluble organic substance which floats on the silicate film at the time of baking paint and uniformly covers the silicate film is added to the above-mentioned components mainly composed of the alkali metal silicate and the organic resin. Examples of the water-soluble organic substance to be added include an anionic or nonionic surfactant, particularly, a molecular weight of 100 to 500.
A surfactant of 0 is preferred. Examples of the anionic surfactant include a phosphoric acid ester such as lauryl phosphate, or a phosphoric acid ester neutralized product obtained by neutralizing a phosphoric acid ester with monoethanolamine, triethanolamine, or the like, a sulfonic acid ester, or a sulfonic acid ester Neutralized substances are raised. In particular, a phosphoric acid ester and a neutralized product are preferable because the effect of reducing the dynamic friction coefficient is large. Examples of the nonionic surfactant include polyoxyethylene nonyl phenyl ether, polyoxyethylene alkyl phenyl ethers such as polyoxyethylene octyl phenyl ether, polyoxyethylene alkyl allyl ether, polyoxyethylene oleyl ether, and polyoxyethylene lauryl ether. Polyoxyethylene alkyl ethers, polyoxyethylene polyoxypropylene block polymers, polyoxyethylene sorbitan monolaurate, sorbitans or derivatives such as sorbitan monolaurate, polyoxyethylene lanolin fatty acid ester, polyoxyethylene lanolin alcohol Examples include polyoxyethylene derivatives such as ethers and sucrose fatty acid esters. Among them, polyoxyethylene alkylphenyl ether is preferable because the dynamic friction coefficient reduction effect is large.

As for the amount of the coating to be provided, if the silicic acid content in the coating is in the range of 8 to 500 mg / m ² , the performance required as a fin material is satisfied, but more preferably the silicic acid content is 24 to 400 mg / m 2. The range of ² is good.

[0015] As described above, silicic acid or a silicate and a water-soluble organic substance or organic resin are mixed and applied. During baking, the water-soluble organic material floats on the silicate film (air side) as shown in FIG. Since the water-soluble organic layer floated in this way has a high lubricating effect, it prevents direct contact between the mold and the silicate coating layer during molding, and a low-pressure press such as a volatile press oil. Good molding is possible even if oil is used. In particular, the conditions for baking paint are selected, and a layer consisting of only a water-soluble organic substance is 20 to 1000 mg.
/ M ² , lubricity is improved and a film having excellent moldability when formed into a fin shape can be obtained.
If it is less than 20 mg / m ² , a portion where the silicate film comes into direct contact with the mold is formed because it is too thin, and molding defects such as seizure, buckling, and color jump, and an increase in mold wear are likely to occur. On the other hand, even if it exceeds 1000 mg / m ² , no improvement in performance can be expected. The thickness of the layer composed of only the water-soluble organic material layer is somewhat non-uniform depending on the production conditions. However, there is no particular problem if the difference between the maximum value and the minimum value is 30% or less of the average value.

When a layer in which fatty acid metal salts and waxes (paraffin wax, etc.) are dispersed is provided on the outermost surface as in the prior art, only the water-soluble portion flows due to condensed water or the like, and the hydrophobic substance is removed from the surface. And the hydrophilicity may decrease during use. Further, since the hydrophobic substance is also adsorbed on the silicate film, the high hydrophilicity inherent to the silicate film cannot be exhibited. On the other hand, in the present invention, since there is no alienation effect as described above because it does not contain a hydrophobic substance, and since the hydrophilicity of the water-soluble organic substance itself is high,
Good hydrophilicity is realized.

Further, in the conventional material, metal soap or resin, particularly thermosetting resin is applied for lubrication.
Heating residue of organic matter remains on the fins
It causes yellowing and burning odor, and furthermore, adheres in large amounts to the silicate coating layer, and reduces the hydrophilicity. However, according to the present invention, since the boiling point of the water-soluble organic substance used is low,
When the fin is heated at the time of brazing a copper pipe or the like, the water-soluble organic substance volatilizes and does not remain on the fin surface, so that problems such as yellowing and burning smell do not occur. In addition, there is no residue from heating of organic matter, or a very small amount of clean silicate covers the fin surface, so that the hydrophilicity does not decrease.

Further, according to the present invention, since the silicate film layer is formed under the water-soluble organic material layer on the surface (on the aluminum side), the water-soluble organic material layer on the surface layer becomes condensed water or the like after many years of use. , The silicate coating layer exhibits hydrophilicity, and thus maintains high hydrophilicity for a long period of time. That is, the hydrophilicity is excellent.

Next, the composition of the paint will be described.
With respect to the coating composition, the silicic acid content is 150 to 500 parts by weight in terms of silicic acid in the case of an alkali metal silicate, and the water-soluble organic substance is 3 to 5000 parts by weight, based on 100 parts by weight of the resin. If the silicic acid content is less than 150 parts by weight, the resin content becomes too large, and the resin covers the silicic acid film,
Hydrophilicity is reduced, and scorching easily occurs when brazing copper pipes. On the other hand, if it exceeds 500 parts by weight, the water resistance becomes poor, and the silicate flows early, and the hydrophilicity, especially the hydrophilicity persistence, becomes poor. If the amount of the water-soluble organic substance is less than 3 parts by weight, there is no effect of the addition, and even if the amount exceeds 5000 parts by weight, the performance is saturated and it is useless. Further, as a more preferable mixing ratio, a silicic acid content is 160 to 400 parts by weight, and a water-soluble organic substance is 400 to 2 parts by weight with respect to 100 parts by weight of the resin.
500 parts by weight. By this blending, excellent film adhesion, hydrophilicity and hydrophilic durability can be stably obtained. In addition, in order to suppress foaming at the time of coating, a surfactant having a low HLB may be separately added in an appropriate amount in addition to the above components. Specifically, sorbitan monooleate, sorbitan sesquiolate,
Fatty acid-based surfactants and the like are included. The addition amount may be appropriately determined, but is preferably 5% or less in terms of solid content. If it exceeds 5%, the hydrophilicity may decrease, which is not preferable.

Next, production conditions for forming the coating film of the present invention will be described. The baking temperature may be appropriately selected according to the composition of the coating material.
Dry with hot air for 0 seconds. More preferably 150 to 230
7 to 60 seconds is desirable in a temperature range of ° C. When the temperature is lower than 120 ° C., drying takes a long time, the productivity is low, and the polymerization of the silicate hardly proceeds, so that the water resistance is insufficient. 3
If the temperature exceeds 50 ° C., the added water-soluble organic matter will be wasted due to a large amount of evaporation.

According to the present invention, unlike the conventional two-step process in which a lubricating layer is further provided after the application of a silicate, two layers can be formed with one coat. Since a thick lubricating layer (water-soluble organic material layer) is obtained, stable molding is possible. In addition, since the manufacturing process is shorter than in the two-stage process, the productivity can be increased and the cost can be reduced. In the two-step process, when a lubricating substance is applied on the silicate coating layer, repelling or the like is generated, and application unevenness is likely to occur. Even when a roll coater or the like is used, it is difficult to uniformly apply a thin film of about ²⁰ to 1000 mg / m ² over the entire length of the coil, and the thickness of the lubricating layer varies. In such a state, stable moldability cannot be obtained. However, according to the present invention, such a problem does not occur.

[0022]

Embodiments of the present invention will be described below.

Example 1 An aluminum plate was degreased, a water glass (Na ₂ SiO ₃ ) was used as an alkali metal silicate as a composition of a paint, and an acrylic resin was used as a resin component [“SAT131” manufactured by Nippon Paint Co., Ltd.] And a water-soluble organic substance, a phosphate ester as an anionic surfactant [“ELENON 19M” manufactured by Daiichi Kogyo Seiyaku Co., Ltd.], and a polyoxyethylene alkyl phenyl ether as a nonionic surfactant [Daiichi Kogyo Seiyaku Co., Ltd.] "Emulgit 25"] was applied as shown in Table 1 so that the amount of silicic acid in the coating film was 100 mg / m ^2, and baked at 200 ° C. for 15 seconds to obtain a test material. . The initial hydrophilicity was measured by measuring the water contact angle immediately after painting and baking. In addition, hydrophilic sustainability is 200 in pure water.
The water contact angle after immersion for hours was measured. The coefficient of friction was measured using a 3 / 16φ steel ball with a Bowden tester, and the load was 500
gf, measured without lubrication. Formability is determined by volatile press oil RF190 (Showa Shell Sekiyu) using actual machine fin press
Ironing rate 50%, molding speed 250 spm
Drawless molding was carried out (at every stroke), and evaluation was made in terms of scratches and the like after molding. Evaluation: ◎: very good,
：: good, △: scratches occurred on the inner surface of the color portion, ×: poor (buckling, color jump occurred).

[0024]

[Table 1]

As shown in Table 1, all of the invention examples satisfying the conditions of the present invention have excellent initial hydrophilicity, excellent hydrophilicity persistence after long-time use, low friction coefficient and excellent lubricity. Also, the moldability is good. In particular, even more excellent characteristics are shown in the limited condition range of the present invention. On the other hand, in the comparative examples out of the conditions of the present invention, the initial hydrophilicity is inferior, or even if the initial hydrophilicity is good, the hydrophilicity persistence is inferior. Or hydrophilic
If the hydrophilic sustainability is good, there is a problem in any of the properties, such as poor lubricity, a high coefficient of friction, and poor moldability.

Example 2 After the aluminum plate was degreased, the coatings having the composition of Example 1-4 were used to vary the thickness of the coating film and various coatings were applied, and baked at 200 ° C. for 15 seconds. And used as test materials. The initial hydrophilicity, hydrophilicity persistence, coefficient of friction, and moldability were tested and evaluated under the same conditions as in Example 1. Table 2 shows the results.

[0027]

[Table 2]

As shown in Table 2, even when the coating material of the present invention is used, if the coating amount is extremely thin, the initial properties are excellent, but the coating cannot withstand long-time use and the hydrophilicity persistence is reduced. are doing. However, 8 to 500 mg /
With a coating amount of m ² , it can sufficiently withstand practical use.

Example 3 After degreasing an aluminum plate, a silicic acid component, a resin component,
The same water-soluble organic substance as in Example 1 was used, and a coating material in which the amount of the water-soluble organic substance was variously changed was applied while changing the film amount, and baked at 200 ° C. for 15 seconds to obtain a test material. The initial hydrophilicity, hydrophilicity persistence, coefficient of friction, and moldability were tested and evaluated under the same conditions as in Example 1. Table 3 shows the results.

[0030]

[Table 3]

As shown in Table 3, in the case where a layer consisting of only a water-soluble organic resin layer was provided as a surface layer in an amount of 20 to 1000 mg / m ² , the initial hydrophilicity, hydrophilicity persistence, friction coefficient, and moldability were improved. In each case, excellent characteristics are shown. If the amount exceeds 1,000 mg / m ² , the performance is saturated, which leads to another problem such as an increase in cost.

[0032]

As described in detail above, the fin material provided by the present invention is obtained by adding silicic acid or an alkali metal silicate to an -OH group, -COOH group, epoxy group, phosphoric acid group, sulfonic acid group or A water-soluble organic material having a molecular weight of 100 to 5,000 having at least one of neutralized products or esters thereof with metal salts or monoethanolamine, and further polyacrylic acid or polymethacrylic acid or polyhydroxyacrylic acid or a salt thereof, or Of the ester
A lacquer that has been applied and baked with a paint that is a mixture of one or more of these or an organic resin consisting of a copolymer of them.The silicate and water-soluble organic substances are separated during baking, and the water-soluble organic substances are raised to the air side. To precipitate silicate at the interface between the aluminum and the paint, on which 20 to 1000 mg
/ m ² provided with a layer composed of only a water-soluble organic substance. According to the present invention, even when a volatile press oil having a low viscosity is used, the lubricating property and moldability are excellent, and the hard silica particles are not exposed on the surface of the coating film. A fin material that can be prevented can be provided. In addition, the water-soluble organic material layer provided on the surface shows high hydrophilicity, and even if the water-soluble organic material layer of the surface layer is washed away by condensed water or the like due to long-term use, the lower silicate layer becomes hydrophilic. As shown, it is excellent in long-term hydrophilicity, so-called hydrophilic persistence. And since such two hydrophilic layers can be provided by one-time baking of paint, a hydrophilic fin material can be provided efficiently and at low cost. Furthermore, since less resin is required during painting, even when exposed to high temperatures during brazing of the copper pipe of the heat exchanger, problems such as generation of burning odor and yellowing do not occur, deterioration of the working environment, hydrophilicity. There is no problem such as deterioration of performance.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a precoated fin material of the present invention.

[Description of symbols] 1 {aluminum 2} coating 3} layer composed of only water-soluble organic substance 4} silicic acid or alkali metal silicate

────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Nobuyoshi Sasaki 4-3-1-18 Nihonbashi Muromachi, Chuo-ku, Tokyo Examiner at Sky Aluminum Co., Ltd. Mayumi Koishi (56) References JP-A-5-125555 (JP, A) JP-A-6-39347 (JP, A) JP-A-61-246059 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B32B 15/08 B05D 7/14 101

Claims (4)

(57) [Claims] 1. A silicic acid or an alkali metal silicate salt of 8 to 500 mg / m.
² , B-OH group, -COOH group, epoxy group, phosphate group,
A water-soluble organic substance having a molecular weight of 100 to 5000 and having one or more of a sulfonic acid group, a neutralized product thereof with a metal salt thereof, monoethanolamine, or the like;
0 to 3125 mg / m ² , C polyacrylic acid, polymethacrylic acid, polyhydroxyacrylic acid, or a salt or ester thereof, or an organic resin composed of at least one of them or a copolymer thereof, or from 5 to 125 mg / m ² . A precoated fin material for heat exchangers having excellent hydrophilicity and lubricity, characterized by having a coating formed thereon. 2. The hydrophilicity and hydrophilicity according to claim 1, wherein the concentration of the water-soluble organic substance (B) in the coating gradually increases from the surface of the aluminum plate, and the outermost surface of the coating consists only of the water-soluble organic substance. Pre-coated fin material for heat exchanger with excellent lubricity. 3. A silicic acid or an alkali metal silicate. B—OH group, —COOH group, epoxy group, phosphate group,
Water-soluble organic substances having a molecular weight of 100 to 5000 and having at least one of a sulfonic acid group, a metal salt thereof, a neutralized product thereof with monoethanolamine, or an ester C polyacrylic acid, polymethacrylic acid, or polyhydroxyl An organic resin composed of at least one of acrylic acid, a salt thereof, or an ester thereof, or a copolymer thereof is added to silicic acid or an alkali metal silicate (A) with respect to 100 parts by weight of the organic resin (C). Converted to 15
0-500 parts by weight, water-soluble organic substance (B) is 3-5000
A paint for heat exchanger plate fins with excellent hydrophilicity and lubricity, composed as parts by weight. 4. A pre-coated fin for a heat exchanger having excellent hydrophilicity and lubricity, wherein the paint according to claim 3 is applied to an aluminum material and dried at 120 to 350 ° C. for 4 to 120 seconds. Manufacturing method.