JP2014029249A - Fin material for heat exchanger, and heat exchanger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fin material for a heat exchanger provided with a uniform hydrophilic inorganic film having proper lubricity so as to have high hydrophilic property on its surface, and capable of suppressing condensation of dew condensation water, and further suppressing processing failure and cutting failure in press workability, and drying failure of press oil, and to provide a heat exchanger including the fin material.SOLUTION: A fin material 1 for a heat exchanger has a base 2 composed of aluminum or aluminum alloy, and a hydrophilic inorganic film 4 disposed on the base 2 with a deposition quantity of 80-600 mg/m. The hydrophilic inorganic film 4 is formed by using a hydrophilic coating including 5-50 pts.wt. of nonionic surface active agent in which 10C or more alkyl group is introduced, to 100 pts.wt. of the film.

Description

  The present invention relates to a heat exchanger fin material and a heat exchanger that are used in a heat exchanger such as an air conditioner and have excellent hydrophilicity and press workability, and are less likely to cause cutting failure during a slit process during press work.

  In the air conditioner, when the heat exchanger is used on the cooling side, condensed water may aggregate to form water droplets, and a water bridge may be formed between adjacent fins. When such a phenomenon occurs, the air passage becomes narrower, the ventilation resistance increases, and the heat exchange efficiency decreases. For this reason, in the fin material for heat exchangers, a hydrophilic film that imparts wettability (hydrophilicity) to the surface is generally provided.

  Conventionally, hydrophilic inorganic films mainly composed of alkali silicates and hydrophilic resin films mainly composed of water-soluble resins such as acrylic resins are known as hydrophilic films used for fin materials. Patent Document 1 proposes a two-layer structure in which a hydrophilic resin film is laminated on a hydrophilic inorganic film. Patent Document 2 discloses chemicals in the environment by adding an alkali metal salt or the like to the hydrophilic film. There has been proposed a structure that prevents water repellency of the film due to substance adhesion.

The fin material can be obtained by pressing an aluminum plate that has been previously provided with these hydrophilic films. However, the hydrophilic film as described above has a poor sliding property against the mold surface used in the pressing process. Due to the above, there are problems such as processing defects such as collar jumping and cracking in which the collar of the fin breaks, and die wear.
In particular, when sodium silicate (water glass) is used as the material for the hydrophilic inorganic coating, during press processing, Na in the coating component is deposited on the surface and transferred to the mold surface, which deteriorates the lubricity. Processing defects such as color skipping are likely to occur. Further, in the hydrophilic film made of sodium silicate, there is a problem that the press oil applied at the time of pressing is repelled on the surface of the film to form oil droplets, which causes a problem of poor drying of the press oil.

  To prevent slipping of the film against the mold, lubrication can be achieved by applying a water-soluble lubricant such as polyethylene glycol to the surface of the hydrophilic film or by providing a lubricating film containing a siloxane compound having a hydrophilic group. (For example, refer to Patent Document 3).

Japanese Patent Laid-Open No. 7-316837 JP 2006-213859 A JP-A-6-172777

However, when a lubricating film made of a water-soluble lubricant or the like is provided on the hydrophilic film, there is a problem that the surface of the film is slipped too much in the slit process at the time of press working, resulting in poor cutting of the plate material. As a measure for preventing this cutting failure, a method of thinly coating a water-soluble lubricant is conceivable, but since the amount of the water-soluble lubricant is very small, it is difficult to accurately adjust the coating thickness.
Polyethylene glycol is often used as a lubricant component for hydrophilic coatings. When a coating for forming a coating is prepared by mixing polyethylene glycol with lithium silicate, sodium silicate, etc., only polyethylene glycol is applied after painting and baking. There is a problem that repelling occurs and the film cannot be formed uniformly.

  The present invention has been made to solve these problems, and can uniformly form a hydrophilic inorganic film having appropriate lubricity, has high hydrophilicity, and suppresses condensation of condensed water. An object of the present invention is to provide a heat exchanger fin material and a heat exchanger provided with the fin material that can suppress processing defects and cutting defects at the time of press processing and suppress press oil drying defects.

  As a result of the inventor's extensive studies to solve the above problems, the use of a nonionic surfactant as a lubricant to be contained in the hydrophilic inorganic film makes the film thickness uniform and appropriate lubricity. It came to the knowledge that the hydrophilic inorganic membrane | film | coat which has can be obtained. This invention is made | formed based on this knowledge, Comprising: It has the following structures.

The fin material for a heat exchanger of the present invention has a substrate made of aluminum or an aluminum alloy, and a hydrophilic inorganic film provided on the substrate with a deposition amount of 80 to 600 mg / m ^2. The film is formed using a hydrophilic paint containing 5 to 50 parts by weight of a nonionic surfactant into which an alkyl group having 10 or more carbon atoms is introduced with respect to 100 parts by weight of the film. To do.

The hydrophilic inorganic film is made of lithium silicate containing 5 to 15 parts by weight of Li ₂ O with respect to 100 parts by weight of SiO ₂ .
The hydrophilic inorganic film is made of sodium silicate containing 10 to 40 parts by weight of Na ₂ O with respect to 100 parts by weight of SiO ₂ .
The heat exchanger of the present invention comprises a plurality of fin materials for heat exchangers of the present invention.

According to the fin material for a heat exchanger of the present invention, a hydrophilic inorganic film containing a nonionic surfactant having an alkyl group having 10 or more carbon atoms introduced thereon is provided on a substrate made of aluminum or an aluminum alloy. Aggregation of condensed water on the surface of the fin material is suppressed, and a phenomenon in which a bridge of water is formed between adjacent fins to increase ventilation resistance can be avoided.
Since the nonionic surfactant contained in the hydrophilic inorganic film imparts lubricity to the surface of the film, the hydrophilic inorganic film is formed when the plate material pre-coated with the hydrophilic inorganic film is pressed into a fin shape. And the mold can be reduced in friction, and good press workability can be obtained.

  Further, in the present invention, since the nonionic surfactant as a lubricant is contained in the hydrophilic inorganic film, the lubricity depends on the content of the lubricant as compared with the case where the lubricant is applied to the film surface. Can be controlled with high accuracy. For this reason, lubricity can be imparted to the hydrophilic inorganic film without excess and deficiency, and friction between the hydrophilic inorganic film and the mold can be reduced, and at the same time, cutting failure in the slit process due to excessive sliding can be suppressed. It is.

  By using a nonionic surfactant having a predetermined number of carbons as a lubricant, the repelling of the lubricant can be suppressed and a hydrophilic inorganic coating can be uniformly formed when a hydrophilic coating for coating formation is applied to a plate material. be able to. For this reason, hydrophilicity and lubricity can be uniformly provided to the fin material.

  Further, when the material of the hydrophilic inorganic film is sodium silicate, the transfer of the Na component to the mold is suppressed by adding a nonionic surfactant to the hydrophilic inorganic film. Deterioration can be reduced. For this reason, processing defects such as color skipping are effectively suppressed, and good press workability can be obtained. Moreover, the repelling of the press oil on the surface of the hydrophilic inorganic coating is suppressed, and it is possible to suppress the drying failure of the press oil.

  Moreover, according to the heat exchanger of this invention, since the fin material for heat exchangers mentioned above is provided, ventilation resistance can be suppressed low and high heat exchange efficiency can be obtained. In addition, since the fin material has high productivity, it is possible to improve productivity as a heat exchanger and reduce costs.

Sectional drawing which expands and partially shows embodiment of the fin material for heat exchangers which concerns on this invention. The perspective view which shows an example of the heat exchanger provided with two or more fins for heat exchange shown in FIG.

Hereinafter, the present invention will be described in detail based on embodiments shown in the accompanying drawings.
FIG. 1 is a partially enlarged cross-sectional view showing an embodiment of a fin material for a heat exchanger according to the present invention.
The heat exchanger fin material 1 shown in FIG. 1 has a phosphoric acid chromate film 3 and a hydrophilic inorganic film 4 sequentially formed on the surface of a fin substrate 2 made of aluminum or an aluminum alloy.

  The board | substrate 2 consists of a board | plate material which consists of aluminum or aluminum alloy, for example, After forming the membrane | film | coat 3 and the membrane | film | coat 4 on the board | substrate 2, a fin is shape | molded by pressing into a fin shape. The aluminum or aluminum alloy is not particularly limited, and an aluminum material having a composition generally applied to a base material for a heat exchanger may be appropriately used. In addition, if illustrated, JIS regulation A1050, A1200 material, etc. are mentioned.

The phosphoric acid chromate film 3 is a chemical conversion film that is chemically generated on the surface of the substrate 2 by immersing the substrate 2 in an aqueous solution of chromic acid or dichromic acid containing phosphate. Provided.
The phosphoric acid chromate film 3 imparts corrosion resistance to the fin material 1, suppresses the generation of corrosion products on the surface of the fin material 1 when using a heat exchanger, and coats the hydrophilic inorganic film 4 provided thereon. Has a function to improve adhesion.
When the phosphate chromate film 3 is provided, the deposition amount is not particularly limited, but is preferably 10 to 30 mg / m ² . When the coating amount of the phosphate chromate film 3 is less than 10 mg / m ² , the corrosion resistance of the fin material 1 is insufficient, and the adhesion of the films 3 and 4 provided on the fin material 1 becomes insufficient. There is a possibility that the function of will not be sufficiently obtained. Moreover, problems such as generation of corrosion products when using a heat exchanger, insufficient lubrication during press working, and color cracking are likely to occur. On the other hand, even if the deposition amount of the phosphoric acid chromate film 3 is larger than 30 mg / m ² , no further effect can be obtained and the material cost is increased.

The hydrophilic inorganic coating 4 is composed of a hydrophilic inorganic material and a nonionic surfactant having an alkyl group having 10 or more carbon atoms.
The hydrophilic inorganic coating 4 has a function of imparting hydrophilicity to the fin material 1. Thereby, aggregation of condensed water on the surface of the fin material 1 is suppressed, and a phenomenon in which a bridge of water is formed between adjacent fins to increase ventilation resistance can be avoided.

Further, the hydrophilic inorganic coating 4 has appropriate lubricity by containing a predetermined amount of a nonionic surfactant. For this reason, when the plate material precoated with the hydrophilic inorganic coating 4 is pressed into a fin shape, the friction between the hydrophilic inorganic coating 4 and the mold can be reduced, and good press workability can be obtained. .
Further, in the present invention, since a predetermined amount of the nonionic surfactant as a lubricant is contained in the hydrophilic inorganic coating 4, the lubricity is controlled with higher accuracy than the configuration in which the lubricant is applied to the coating surface. be able to. For this reason, moderate lubricity can be imparted to the hydrophilic inorganic film 4 without excess or deficiency, and friction between the hydrophilic inorganic film 4 and the mold can be reduced, and at the same time, cutting failure in the slit process due to excessive slipping. It is possible to suppress.
In addition, by using a nonionic surfactant having a predetermined number of carbons as a lubricant, when applying a hydrophilic coating for film formation described later to a plate material, the repelling of the lubricant is suppressed, and the film thickness is uniform. A hydrophilic inorganic coating 4 can be obtained. For this reason, hydrophilicity and lubricity can be uniformly provided to the fin material.

  Furthermore, when the material of the hydrophilic inorganic coating 4 is sodium silicate, it is possible to prevent the Na component from being transferred to the mold by containing the nonionic surfactant in the hydrophilic inorganic coating 4. , Deterioration of lubricity can be reduced. For this reason, processing defects such as color skipping can be effectively suppressed, and good press workability can be obtained. Moreover, the repelling of the press oil on the surface of the hydrophilic inorganic coating 4 is suppressed, and it is possible to suppress the drying failure of the press oil.

  Examples of the hydrophilic inorganic material contained in the hydrophilic inorganic coating 4 include alkali silicates such as sodium silicate, potassium silicate, and lithium silicate. These alkali silicates form siloxane bonds (Si—O—Si) in which OH groups or OM groups (wherein M represents an alkali metal such as lithium or sodium) are bonded by evaporation of moisture, and OH groups Exhibits hydrophilicity when exposed to the surface.

When using a lithium silicate or sodium silicate as an alkali silicate, preferably comprise 5 to 15 parts by weight of Li ₂ O with respect to lithium silicate _SiO 2 100 parts by weight of sodium silicate is Na respect _SiO 2 100 parts by weight preferably it contains 10 to 40 parts by weight of ₂ O. If the ratio of the amount of Li ₂ O or Na ₂ O to the amount of SiO ₂ deviates from the above range, each alkali silicate is dispersed as a powder in the hydrophilic paint, and the paintability may deteriorate. There is sex.

  The nonionic surfactant contained in the hydrophilic inorganic coating 4 is not particularly limited as long as it has an alkyl group having 10 or more carbon atoms. Specifically, polyoxyethylene alkyl ether, sulvidan fatty acid ester, Examples include glycerin fatty acid ester, sucrose fatty acid ester, polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene myristyl ether, sorbitan tristearate, glycerol monostearate, etc., one or more of these Can be used in combination. Nonionic surfactants have the advantage of being easier to disperse in paints than anionic surfactants and cationic surfactants.

  For example, the hydrophilic inorganic coating 4 is formed by applying a hydrophilic paint containing an alkali silicate and a nonionic surfactant on a surface of the substrate 2 on which the phosphate chromate coating 3 is formed using a coating apparatus such as a bar coater or a roll coater. After coating, it can be formed by heating and drying.

  In this embodiment, a nonionic surfactant is contained in a ratio of 5 to 50 parts by weight with respect to 100 parts by weight of the hydrophilic coating. If the content of the nonionic surfactant in the hydrophilic coating is less than 5 parts by weight, the lubricity of the plate material becomes insufficient at the time of pressing, resulting in problems such as processing defects, die wear, and press oil drying defects. . On the other hand, when the content of the nonionic surfactant exceeds 50 parts by weight, the lubricity of the plate material becomes too high, and cutting failure occurs in the slit process during press working.

Moreover, the hydrophilic inorganic membrane | film | coat 4 is provided with the deposition amount of 80-600 mg / m < ² >. When the coating amount of the hydrophilic inorganic coating 4 is less than 80 mg / m ² , the hydrophilicity of the fin material becomes insufficient, and there arises a problem that the ventilation resistance increases due to the condensation of condensed water on the surface of the fin material. On the other hand, even if the deposition amount of the hydrophilic inorganic coating 4 is larger than 600 mg / m ² , no further effect can be obtained and the material cost is increased.

In addition to the alkali silicate and nonionic surfactant, a resin component that does not inhibit hydrophilicity can be added to the coating material for forming a film for the purpose of improving adhesion to the film. Specific examples include acrylic resins mainly composed of polyvinyl alcohol and polymethacrylic acid.
In addition, it is preferable that the hydrophilic inorganic film containing alkali silicate is sufficiently washed after coating and sufficiently dried after washing.

  The fin material for a heat exchanger according to the present embodiment is provided with a hydrophilic inorganic film 4 on a substrate 2 via a phosphate chromate film 3, and an alkyl group having 10 or more carbon atoms is introduced as the hydrophilic inorganic film 4. Since it contains a nonionic surfactant, it suppresses the condensation of condensed water on the surface of the fin material 1, prevents the formation of a water bridge between adjacent fins, and avoids the phenomenon of increased ventilation resistance. Can do. In addition, during press processing, the plate material exhibits appropriate lubricity, good press workability is obtained, and cutting defects and press oil drying defects are suppressed, so that productivity of the fin material can be improved. Is possible.

FIG. 2 is a perspective view showing an example of a heat exchanger provided with the fin material 1 of the present invention.
A heat exchanger 20 shown in FIG. 2 includes the fin material 1 shown in FIG. 1 and a plurality of heat transfer tubes 30. The aluminum fin materials 10 are arranged in parallel at regular intervals, and air flows between the aluminum fin materials 10. The heat transfer tube 30 penetrates the flare 11 of the aluminum fin material 10, and the refrigerant flows through the inside.
Since the heat exchanger 20 having such a configuration includes the fin material 1 described above, the ventilation resistance can be suppressed low, and high heat exchange efficiency can be obtained. Moreover, since the productivity of the fin material 1 is high, productivity improvement as the heat exchanger 20 and cost reduction can be achieved.

  As mentioned above, although the fin material for heat exchangers and the heat exchanger of this invention were demonstrated based on each embodiment, this invention is not limited to these, It can change suitably in the range which does not deviate from the scope of this invention. it can.

The present invention will be further described below based on examples.
1. Creation of fin material (Examples 1 to 16)
A substrate made of JIS A1050 aluminum was prepared. This substrate was subjected to a phosphoric acid chromate treatment to form a phosphoric acid chromate film.
Next, a hydrophilic paint containing alkali silicate and polyoxyethylene alkyl ether (nonionic surfactant) is prepared, and this hydrophilic paint is applied to the surface of the substrate on which the phosphate chromate film is formed using a bar coater. A hydrophilic inorganic film was formed by coating and drying by heating.
In the hydrophilic paint, the type of alkali silicate, the content of polyoxyalkyl ether (lubricant content), and the amount of hydrophilic inorganic coating deposited are set as shown in Table 1 below, and the fin material of each example Got.

(Comparative Examples 1-6)
A fin material was prepared by the same method as the manufacturing method of Example 1 except that the lubricant content in the hydrophilic paint was adjusted.
(Comparative Examples 7 to 10)
A fin material was prepared by the same method as the manufacturing method of Example 1 except that the amount of the hydrophilic inorganic coating applied was adjusted.

2. Evaluation About the fin material created in each Example and each comparative example, it evaluated as follows.
(1) Paintability Evaluate the coating state after painting and heat baking with a bar coater ○ Good paintability, Δ repellency, x surface repellency (2) Hydrophilic Each fin material was washed with water for 24 hours The water contact angle was measured after (pretreatment). Here, the case where the water contact angle was 20 ° or less was evaluated as an appropriate hydrophilic range.
(3) Corrosion resistance About each fin material, the salt spray test prescribed | regulated to JISZ2371 was performed for 240 hours, and the corrosion area rate after a test was evaluated by the rating number (RN). Here, in the salt spray test, R.I. The case where N was 9.8 or more was defined as an allowable range of corrosion resistance.
(4) Coefficient of dynamic friction Using a Bowden friction tester, a one-cycle test was conducted without applying press oil to the sliding surface of the tester, and the coefficient of dynamic friction on the surface of each fin material was measured. Here, the case where the dynamic friction coefficient was 0.2 to 0.5 was evaluated as an appropriate range.

(5) Press workability The press workability was evaluated under the following conditions (a) to (c).
(A) About each board | plate material (state in which each membrane | film | coat was formed) before performing press molding, press work was performed to 5000 shots, and the color jump generation | occurrence | production condition was visually observed. The observation results were evaluated according to the following criteria.
(Circle): No color jump, x: Color jump (b) About each board | plate material before performing press molding, press work was performed to 5000 shots and the occurrence condition of the cutting defect in a slit process was investigated. This result was evaluated according to the following criteria.
(Circle): There is no cutting defect, x: There is a cutting defect (c) About each board | plate material before performing press molding, press processing was performed to 1 million shots, and the abrasion state of the subsequent metal mold | die was observed visually. The observation results were evaluated according to the following criteria.
○: Almost no mold wear, △: Slight mold wear, x: High mold wear

(6) Oil repellency The oil droplet contact angle was measured for each fin material. Here, the case where the oil droplet contact angle was 20 ° or less was evaluated as an allowable range.
The above evaluation results are summarized in Table 1.

As shown in Table 1, the fin materials of Examples 1 to 16 are all excellent in hydrophilicity, corrosion resistance, lubricity and press workability, and press oil repellency is suppressed.
On the other hand, the fin materials of Comparative Examples 1, 2, 4, and 5 had a relatively large dynamic friction coefficient, and color skipping, cracking, and die wear occurred during press working. In particular, the fin material of Comparative Example 1 had a large oil droplet contact angle, resulting in poor drying of the press oil. On the other hand, in Comparative Examples 3 and 6, the coefficient of dynamic friction was too small, and cutting failure occurred in the slit process during press working.
Since the fin materials of Comparative Examples 7 and 8 have a large water contact angle and a low hydrophilicity, there is a concern about an increase in ventilation resistance due to condensation of condensed water. On the other hand, the fin materials of Comparative Examples 9 and 10 had a relatively large dynamic friction coefficient, and die wear occurred during press working.
From the results shown in Table 1, since the SiO ₂ amount of the films of Comparative Examples 7 to 10 is too large or too small, the hydrophilicity is inferior or mold wear occurs, so the SiO ₂ amount of the film is 80 mg / m ^2. As described above, it can be seen that it is preferably 600 mg / m ² or less.
When the content of Comparative Examples 1 to 6 is too large or too small with respect to the lubricant content, the dynamic friction coefficient falls outside the desirable range of 0.2 to 0.5, which is not too slippery, or color skipping or cracking occurs. The lubricant content is preferably 5% or more and 50% or less because it may occur, cause a problem in slit machining, or cause a problem in mold wear.

Incidentally, if the Na ₂ O to _SiO 2 100 parts by weight with sodium silicate 5 parts by weight or 50 parts by weight, or, Li ₂ O with respect to _SiO 2 100 parts by weight 2.5 parts by weight or 20 weight When a part of lithium silicate was used, each alkali silicate was dispersed as a powder in the hydrophilic paint and could not be applied.

  DESCRIPTION OF SYMBOLS 1 ... Fin material (fin material for heat exchangers), 2 ... Substrate, 3 ... Phosphate chromate film, 4 ... Hydrophilic inorganic film, 20 ... Heat exchanger, 30 ... Heat transfer tube

Claims (4)

A substrate made of aluminum or an aluminum alloy, and a hydrophilic inorganic film provided on the substrate with a deposition amount of 80 to 600 mg / m ² ;
The hydrophilic inorganic coating is formed using a hydrophilic coating containing 5 to 50 parts by weight of a nonionic surfactant having an alkyl group having 10 or more carbon atoms introduced in 100 parts by weight of the coating. A fin material for a heat exchanger, characterized in that there is. The hydrophilic inorganic _coating, heat exchanger fin stock according to claim 1, characterized in that it comprises 5 to 15 parts by weight of Li ₂ O with respect to SiO 2 100 parts by weight. The hydrophilic inorganic _coating, heat exchanger fin stock according to claim 1, characterized in that it comprises 10 to 40 parts by weight of Na ₂ O with respect to SiO 2 100 parts by weight.   A heat exchanger comprising a plurality of fin materials for heat exchangers according to any one of claims 1 to 3.

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