JP5436482B2 - Heat exchanger and manufacturing method thereof - Google Patents

Description

  The present invention relates to a heat exchanger and a method of manufacturing the same, and more specifically, in addition to general buildings, metal processing sites such as welding and cutting, establishments handling metal dust, vehicles such as railways, and other related The present invention relates to a heat exchanger for an air conditioner used in a facility and a method for manufacturing the same.

  The heat exchanger has a structure in which a large number of fins (for example, aluminum fins) are attached to a pipe through which a refrigerant passes, and heat exchange efficiency is enhanced by fins having a large surface area. Condensed water tends to adhere to the surface of the fins during cooling and heating, and the resistance to heat exchange is reduced due to the phenomenon that the fins are blocked by condensed water (hereinafter referred to as “bridge phenomenon”). There is. In particular, since the bridging phenomenon is likely to occur when dirt such as dust adheres to the surface of the fin, the bridging phenomenon is caused by forming an organic or inorganic hydrophilic film having excellent antifouling performance on the surface of the fin. Is generally prevented. Here, the “antifouling performance” in the present specification means performance in which dirt is difficult to adhere and performance in which attached dirt is easily removed.

However, when the inorganic hydrophilic coating contains a large amount of inorganic components such as water glass and boehmite, the organic hydrophilic coating is often used because odor adsorption is likely to occur. On the other hand, organic hydrophilic coatings are likely to decompose, deteriorate, or dissolve in condensed water over time, and the antifouling performance and hydrophilicity of the hydrophilic coatings are reduced.
Therefore, in order to prevent such antifouling performance and hydrophilicity of the hydrophilic coating, techniques for forming the hydrophilic coating using various paints have been proposed. For example, Patent Document 1 proposes a method of forming a hydrophilic film using a paint containing modified polyvinyl alcohol and a crosslinking agent. Patent Document 2 proposes a method of forming a hydrophilic film using a paint containing carboxymethyl cellulose, polyethylene glycol, and a crosslinking agent.

JP 10-36757 A JP-A-8-261688

  Generally, since the fin surface is exposed to condensed water, heat, light, air, etc., the antifouling performance and hydrophilicity of the hydrophilic coating formed on the fin surface are reduced by these various factors. The fins may be corroded due to deterioration of the hydrophilic film. Air conditioners are often used in various environments, especially when there are many contaminants in the air (for example, metal particles of iron, copper or their alloys, especially iron powder). Contaminants adhere to the surface. This adhesion of contaminants also causes the antifouling performance and hydrophilicity of the hydrophilic coating and causes corrosion of the fins. Patent Documents 1 and 2 do not deal with problems related to the antifouling performance and hydrophilicity deterioration of the hydrophilic coating and the corrosion of the fins due to the adhesion of the contaminants.

  That is, the hydrophilic coatings of Patent Documents 1 and 2 can maintain antifouling performance and hydrophilicity in an ordinary environment with few contaminants in the air, but in an environment with many contaminants in the air. In (for example, metal processing sites such as welding and cutting, establishments handling metal dust, vehicles such as railways, and other related facilities), the antifouling performance and hydrophilicity gradually decrease due to the adhesion of contaminants. Specifically, since the hydrophilic coatings of Patent Documents 1 and 2 are organic, the metal ion component generated when the contaminant is dissolved in the condensed water acts as a catalyst to promote the deterioration of the organic component. . As a result, the antifouling performance and hydrophilicity of the hydrophilic coating are lowered, and fin corrosion and the like also occur.

  The present invention has been made to solve the above-described problems, and is a coating film that can maintain antifouling performance and hydrophilicity even in an environment where there are many pollutants in the air and can prevent corrosion of fins. It aims at providing the heat exchanger provided with, and its manufacturing method.

  As a result of intensive studies to solve the above problems, the present inventors have formed a hydrophilic organic film on the fin, and then added one or more metals selected from the group consisting of Ti, Zr and Al. By treating the surface layer of the hydrophilic organic coating using the metal alkoxy compound and / or metal chelate compound, the hydrophilic organic coating prevents the entry of metal ion components due to contaminants into the hydrophilic organic coating. It has been found that the deterioration of the resin can be suppressed, the antifouling performance and hydrophilicity can be maintained even in an environment where there are many pollutants in the air, and the corrosion of the fins can be prevented.

That is, the present invention is a method of manufacturing a heat exchanger having a fin on which a film is formed, wherein a hydrophilic organic film is formed on the fin and then selected from the group consisting of Ti, Zr and Al. A method for producing a heat exchanger, comprising reacting a metal alkoxy compound and / or a metal chelate compound having at least one kind of metal with a surface layer of the hydrophilic organic coating.
The present invention is also a heat exchanger having a fin on which a film is formed, wherein the film includes a hydrophilic organic film formed on the fin, and Ti, Zr and a surface layer of the hydrophilic organic film. A heat exchanger comprising: a reaction layer obtained by reacting a metal alkoxy compound having at least one metal selected from the group consisting of Al and / or a metal chelate compound.

  According to the present invention, there are provided a heat exchanger provided with a coating capable of maintaining antifouling performance and hydrophilicity even in an environment where there are many pollutants in the air and preventing corrosion of fins, and a method for manufacturing the same. Can do.

3 is a cross-sectional view of a coating formed on the surface of the fin of the heat exchanger according to Embodiment 1. FIG. It is a perspective view of a general heat exchanger.

Embodiment 1 FIG.
Hereinafter, the heat exchanger and the manufacturing method thereof according to the present embodiment will be described with reference to the drawings.
FIG. 1 is a cross-sectional view of a coating formed on the surface of a fin of a heat exchanger. In FIG. 1, a hydrophilic organic coating 2 and a reaction layer 3 are sequentially formed on the surface of the fin 1.

  The hydrophilic organic coating 2 formed on the fin 1 is a coating that bears the hydrophilicity of the coating formed on the surface of the fin 1. The hydrophilic organic coating 2 is not particularly limited as long as it is a hydrophilic organic coating generally used in the technical field. Specifically, what has a polar group (for example, a hydroxyl group, a carboxy group, etc.) and does not melt | dissolve in water should just be. Examples of the hydrophilic organic coating 2 include polyvinyl alcohol, polyvinyl pyrrolidone or polyacrylamide homopolymer, copolymer or modified body; acrylic acid or methacrylic acid homopolymer, copolymer or salt thereof; Examples thereof include a film formed from a urethane resin or the like. Moreover, even if it is resin, such as a fluororesin and a silicone resin, if it has a polar group, it can be used. These may be used alone or in combination of two or more components. When two or more components are used in combination, two or more components may be uniformly mixed or phase separated. The hydrophilic organic coating 2 may contain an inorganic material such as silica or titania.

  The thickness of the hydrophilic organic coating 2 is not particularly limited, but is preferably 0.1 μm or more and 15 μm or less. When the thickness of the hydrophilic organic coating 2 is less than 0.1 μm, corrosion of the fin 1 may not be sufficiently prevented. On the other hand, if the thickness of the hydrophilic organic coating 2 exceeds 15 μm, the heat exchange efficiency may decrease.

The hydrophilic organic coating 2 can be formed by applying and drying a coating containing a component that gives the hydrophilic organic coating 2 on the fin 1 as described above. From the viewpoint of insolubilizing the hydrophilic organic coating 2 and improving the strength, the coating material may contain known additives such as a crosslinking agent, a radical initiator, and a reactive component. The compounding quantity of these each component is not specifically limited, What is necessary is just to adjust suitably according to a kind.
The method for applying the paint is not particularly limited, and can be performed according to a method known in the art. Examples of the method for applying the paint include brush coating, spray coating, dipping, and coating with a roll coater.
The method for drying the paint is not particularly limited and may be left at room temperature. Further, drying may be promoted by heating.

The reaction layer 3 formed on the hydrophilic organic coating 2 is composed of a metal alkoxy compound and / or a metal chelate compound having one or more metals selected from the group consisting of Ti, Zr and Al. It is a layer formed by reacting with the surface layer.
In general, polar groups (for example, hydroxy groups and carboxy groups) in the hydrophilic organic coating 2 are formed by the dissolution of contaminants (for example, metal particles of iron, copper, or alloys thereof) in condensed water. It reacts with and binds to an ionic component to promote the decomposition of the hydrophilic organic coating 2. Therefore, by reacting the metal alkoxy compound and / or the metal chelate compound with the polar group on the surface layer of the hydrophilic organic coating 2 in advance, the reaction between the polar group, the metal ion and the component in the hydrophilic organic coating 2 is achieved. To prevent. Thereby, the penetration | invasion into the hydrophilic organic film 2 of the metal ion component resulting from a contaminant can be prevented, and deterioration of the hydrophilic organic film 2 can be suppressed. The reaction layer 3 can also increase the strength and water resistance of the surface layer of the hydrophilic organic coating 2.

  Further, after forming the hydrophilic organic coating 2, only the surface layer of the hydrophilic organic coating 2 is reacted with a metal alkoxy compound and / or a metal chelate compound to form the reaction layer 3, thereby cracking the hydrophilic organic coating 2 Such a defect can be prevented, and the flexibility of the hydrophilic organic coating 2 can be ensured. Therefore, the adhesion between the fin 1 and the hydrophilic organic coating 2 is not lowered.

  The metal alkoxy compound is not particularly limited as long as it has one or more metals selected from the group consisting of Ti, Zr and Al. Examples of the alkoxy group of the metal alkoxy compound include ethoxy group, butoxy group, n-propoxy group, isopropoxy group, butoxy group, pentoxy group, octoxy group, benzoxy group, phenoxy group and the like. In addition, the same kind of alkoxy group may be bonded to the metal atom of the alkoxy compound, or a different kind of alkoxy group may be bonded. Examples of the metal alkoxy compound include tetrabutoxy titanium, tetrapropoxy titanium, tetrabutoxy zirconium and the like. These metal alkoxy compounds can be used alone or in combination of two or more.

  The metal chelate compound is not particularly limited as long as it has one or more metals selected from the group consisting of Ti, Zr and Al. Examples of metal chelate compound ligands include: organic acids such as citric acid, oxalic acid and lactic acid; amines such as triethanolamine and diethanolamine; various amino acids; triethylenetetraminehexaacetic acid (TTHA); dihydroxyethylglycine ( DHEG); ethylenediaminetetraacetic acid (EDTA); nitrilotriacetic acid (NTA); gluconic acid; 1,3-propanediaminetetraacetic acid; 1,3-diamino-2-propanoltetraacetic acid. Examples of the metal chelate compound include titanium acetylacetonate, zirconium acetylacetonate, acetoalkoxyaluminum diisopropylate, dihydroxybis (ammonium lactate) titanium, diisopropoxytitanium bis (triethanolaminate) and the like. These metal chelate compounds can be used individually or in combination of 2 or more types.

  The method for reacting the metal alkoxy compound and / or metal chelate compound having at least one metal selected from the group consisting of Ti, Zr and Al with the surface layer of the hydrophilic organic coating 2 is not particularly limited. A compound and / or a metal chelate compound may be brought into contact with the surface layer of the hydrophilic organic coating 2. Specifically, the metal alkoxy compound and / or the metal chelate compound is vaporized and brought into contact with the surface layer of the hydrophilic organic coating 2, or a solution containing the metal alkoxy compound and / or the metal chelate compound is contacted with the surface layer of the hydrophilic organic coating 2. Or just touch it. Among these, it is preferable that a solution containing a metal alkoxy compound and / or a metal chelate compound is brought into contact with the surface layer of the hydrophilic organic coating 2 from the viewpoint of uniformly forming the reaction layer 3 on the hydrophilic organic coating 2. Moreover, if this method is used, the residue of the unreacted metal alkoxy compound and / or metal chelate compound on the hydrophilic organic coating 2 can also be reduced.

  When using a solution containing a metal alkoxy compound, an organic solvent such as an alcohol can be used as the solvent of the solution, and an alcohol having the same carbon number as the alkoxy group of the metal alkoxy compound is preferably used. Although content of the metal alkoxy compound in this solution is not specifically limited, Preferably it is 0.2 mass% or more and 10 mass% or less, More preferably, it is 0.25 mass% or more and 5 mass% or less. When the content of the metal alkoxy compound is less than 0.2% by mass, the metal alkoxy compound cannot be sufficiently reacted with the surface layer of the hydrophilic organic coating 2, and the reaction layer 3 may not be sufficiently formed. On the other hand, when the content of the metal alkoxy compound exceeds 10% by mass, a large amount of unreacted metal alkoxy compound tends to remain in the reaction layer 3 and the production cost increases. In addition to alcohol, this solution may contain a known solvent other than alcohol from the viewpoint of adjusting the evaporation rate and flammability.

When a solution containing a metal chelate compound is used, water can be used as the solvent of the solution in addition to an organic solvent such as alcohol. The water is not particularly limited, but from the viewpoint of dispersion stability of the inorganic fine particles, it is preferable that there are few divalent or higher ionic impurities such as calcium and magnesium ions, and deionized water is more preferable. Although content of the metal chelate compound in this solution is not specifically limited, Preferably it is 0.2 to 10 mass%, More preferably, it is 0.25 to 5 mass%. When the content of the metal chelate compound is less than 0.2% by mass, the metal chelate compound cannot be sufficiently reacted with the surface layer of the hydrophilic organic coating 2, and the reaction layer 3 may not be sufficiently formed. On the other hand, when the content of the metal chelate compound exceeds 10% by mass, a large amount of unreacted metal chelate compound remains in the reaction layer 3 and the manufacturing cost increases.
In particular, when using a metal chelate compound, unlike the case of a metal alkoxy compound, it is not necessary to use an organic solvent such as alcohol. Therefore, the risk of ignition and the environmental load can be reduced.

The solution containing the metal alkoxy compound and / or the metal chelate compound can form the reaction layer 3 by coating and drying on the surface layer of the hydrophilic organic coating 2.
The method for applying the solution is not particularly limited, and the solution can be applied in accordance with a method known in the technical field in the same manner as the method for applying the paint.
The method for drying the solution is not particularly limited, and the solution may be left at room temperature in the same manner as the coating method described above. Further, drying may be promoted by heating.

  From the viewpoint of sufficiently forming the reaction layer 3 after applying and drying the solution, heat treatment may be performed as necessary. Although the method of heat processing is not specifically limited, It is preferable to carry out by 40 degreeC or more and 180 degrees C or less oven, or blowing of warm air. If the heating temperature is less than 40 ° C., the effect of the heat treatment may not be sufficiently obtained. On the other hand, when the heating temperature exceeds 180 ° C., the hydrophilicity of the coating film may be lowered. The heating time is not particularly limited, but is preferably 30 seconds or longer and 15 minutes or shorter. If the heating time is less than 30 seconds, the effect of the heat treatment may not be sufficiently obtained. On the other hand, when the heating time exceeds 15 minutes, the mass productivity is insufficient and the hydrophilicity of the coating film may be lowered.

FIG. 2 is a perspective view of a general heat exchanger. As shown in FIG. 2, the heat exchanger has a large number of fins 10 attached to a pipe 11 through which a refrigerant passes. The heat exchanger having such a structure is manufactured by punching a material to be a fin (hereinafter referred to as “fin material”), press-molding the fin, and then inserting the fin 10 into the pipe 11. The
In the manufacturing method of the present embodiment, since the coating film is formed on the fin 1, the coating film may be damaged during the manufacturing process of the heat exchanger. Therefore, from the viewpoint of preventing the reaction layer 3 on the outermost surface from being damaged, the reaction layer 3 is formed on the fin 1 after the heat exchanger is assembled by joining the fin 1 to the pipe 11 through which the refrigerant passes. Is preferred. In this case, the application of the solution is preferably performed by spray application or immersion from the viewpoint of uniform application. Moreover, after apply | coating each coating material, it is preferable to rotate a heat exchanger or to remove an excess coating material by airflow.

  The coating formed on the fin 1 as described above can maintain antifouling performance and hydrophilicity even in an environment where there are many pollutants in the air, and can prevent corrosion of the fin. It can suppress that exchange efficiency falls.

Hereinafter, although an Example and a comparative example demonstrate the detail of this invention, this invention is not limited by these.
Example 1
A paint was prepared by blending and mixing 5 parts by mass of glyoxal with 100 parts by mass of an aqueous solution containing 3% by mass of polyvinyl alcohol (polyvinyl alcohol Z-200 manufactured by Nippon Synthetic Chemical Industry Co., Ltd.).
Next, a butanol solution containing 5% by mass of tetrabutoxytitanium was prepared.
Next, after spray-coating the above-mentioned paint onto aluminum fins, a hydrophilic organic coating (film thickness 0.8 μm) was formed by heating at 140 ° C. for 5 minutes. Next, after spray-applying the above solution to this hydrophilic organic coating, it was heated at 60 ° C. for 1 hour to form a reaction layer on the surface of the hydrophilic organic coating.

(Example 2)
The content of tetrabutoxytitanium in the butanol solution was adjusted to 2% by mass, and the hydrophilic organic film was immersed in this solution at 40 ° C. for 10 minutes, and then heated at 60 ° C. for 1 hour to react with the surface layer of the hydrophilic organic film. A film was formed on the aluminum fin in the same manner as in Example 1 except that the layer was formed.
(Example 3)
A film was formed on the aluminum fin in the same manner as in Example 1 except that the content of tetrabutoxytitanium in the butanol solution was 3% by mass.
Example 4
A film was formed on the aluminum fin in the same manner as in Example 1 except that the content of tetrabutoxytitanium in the butanol solution was 8% by mass.

(Example 5)
Instead of the butanol solution containing 5% by mass of tetrabutoxytitanium, a butanol solution containing 1.5% by mass of tetrabutoxyzirconium was used, and the hydrophilic organic coating was immersed in this solution at 40 ° C. for 10 minutes. A film was formed on the aluminum fin in the same manner as in Example 1 except that the reaction layer was formed on the surface of the hydrophilic organic film by heating at ° C for 1 hour.
(Comparative Example 1)
A hydrophilic organic coating was formed in the same manner as in Example 1, but no reaction layer was formed on the surface layer of the hydrophilic organic coating.

  The coatings obtained in Examples 1 to 5 and Comparative Example 1 were wetted with water, and then iron powder with an average particle size of 45 μm was sprayed and left for 3 days while maintaining the wet state. Next, after drying this film and spraying a water stream, the fixed state of iron powder (iron rust) on the surface of the film was visually observed. Next, the iron powder was removed by immersing in a 1% aqueous sodium hydroxide solution for 1 minute, and the presence or absence of peeling of the coating film at the portion where the iron powder was fixed was observed. The results of these observations are shown in Table 1.

As shown in Table 1, the coatings of Examples 1 to 5 had less iron powder fixation and little degradation of the coating caused by the iron powder. In addition, although the film of Example 1 and 4 was partly peeled, it was a thing practically usable.
On the other hand, since the coating film of Comparative Example 1 had many iron powders adhered, it is considered that contaminants such as iron powders are likely to adhere. Moreover, since the film dissolved and peeled after being immersed in the sodium hydroxide aqueous solution, it is considered that the film was deteriorated by iron ions generated from the iron powder.

(Example 6)
A 2-propanol solution containing 3% by mass of titanium acetylacetonate was prepared.
Next, after forming a hydrophilic organic film (film thickness 0.8 μm) on the aluminum fin in the same manner as in Example 1, it was joined to a copper pipe, and a heat exchanger having a width of 25 mm, a height of 150 mm, and a fin pitch of 2 mm. Was made. Next, this heat exchanger is dipped in the above 2-propanol solution for about 10 seconds and pulled up. After removing the excess 2-propanol solution with an air stream, it is heated in an oven at 140 ° C. for 10 minutes. A reaction layer was formed on the surface layer.

(Example 7)
A film was formed on the aluminum fin in the same manner as in Example 6 except that a 2-propanol solution containing 2% by mass of zirconium acetylacetonate was used instead of the 2-propanol solution containing 3% by mass of titanium acetylacetonate. Was formed.

(Example 8)
Instead of the 2-propanol solution containing 3% by mass of titanium acetylacetonate, a 2-propanol solution containing 3% by mass of acetoalkoxyaluminum diisopropylate was used, and the heat treatment was performed in an oven at 200 ° C. for 10 minutes. Except this, a heat exchanger having a coating film formed on an aluminum fin was produced in the same manner as in Example 6.

Example 9
Aluminum fin was used in the same manner as in Example 6 except that an aqueous solution containing 10% by mass of diisopropoxytitanium bis (triethanolaminate) was used instead of the 2-propanol solution containing 3% by mass of titanium acetylacetonate. A heat exchanger having a film formed thereon was produced.

(Example 10)
Aluminum fin was used in the same manner as in Example 6 except that an aqueous solution containing 5% by mass of diisopropoxytitanium bis (triethanolaminate) was used instead of the 2-propanol solution containing 3% by mass of titanium acetylacetonate. A heat exchanger having a film formed thereon was produced.

(Example 11)
Instead of the 2-propanol solution containing 3% by mass of titanium acetylacetonate, an aqueous solution containing 5% by mass of diisopropoxytitanium bis (triethanolaminate) was used, and heat treatment was performed in an oven at 200 ° C. for 10 minutes. A heat exchanger having a film formed on an aluminum fin was produced in the same manner as in Example 6 except that.

(Example 12)
Other than using an aqueous solution containing 3% by mass of dihydroxybis (ammonium lactate) titanium instead of a 2-propanol solution containing 3% by mass of titanium acetylacetonate, and performing the heat treatment in an oven at 200 ° C. for 10 minutes Produced a heat exchanger in which a film was formed on an aluminum fin in the same manner as in Example 6.

(Comparative Example 2)
Heat exchange in which a film was formed on an aluminum fin in the same manner as in Example 6 except that a hydrophilic organic film was formed in the same manner as in Example 6 and no reaction layer was formed on the surface of the hydrophilic organic film. A vessel was made.

  For the coatings formed on the aluminum fins of the heat exchangers of Examples 6 to 12 and Comparative Example 2, after immersing the heat exchanger in water, the water was shaken off and an average particle size of 45 μm was passed while flowing an air flow of about 20 m / sec. The iron powder was adhered to the aluminum fins by spraying the iron powder. Then, it was left for 3 days while keeping the wet state. Next, after drying the film and spraying a water stream, the state of fixation of iron powder (iron rust) on the surface of the film was visually observed. Next, the iron powder was removed by immersing in a 1% aqueous sodium hydroxide solution for 1 minute, and the presence or absence of peeling of the coating film on the portion where the iron powder was adhered was observed. The results of these observations are shown in Table 2.

As shown in Table 2, the coatings of Examples 6 to 12 had less iron powder sticking and little degradation of the coating due to the iron powder. In addition, although the film of Examples 6, 8-10, and 12 was partly peeled, it was a thing of a practical grade.
On the other hand, since the coating film of Comparative Example 2 had many iron powders adhered, it is considered that contaminants such as iron powders are likely to adhere. Moreover, since the film dissolved and peeled after being immersed in the sodium hydroxide aqueous solution, it is considered that the film was deteriorated by iron ions generated from the iron powder.

  As can be seen from the above results, according to the present invention, a heat exchanger provided with a coating that can maintain antifouling performance and hydrophilicity even in an environment where there are many pollutants in the air, and can prevent corrosion of fins. And a manufacturing method thereof.

  1 fin, 2 hydrophilic organic coating, 3 reaction layer, 10 fin, 11 pipe.

Claims (5)

A method of manufacturing a heat exchanger having fins with a coating formed thereon,
After forming the hydrophilic organic coating on the fin, a metal alkoxy compound and / or a metal chelate compound having one or more metals selected from the group consisting of Ti, Zr and Al are applied to the surface layer of the hydrophilic organic coating. A method for producing a heat exchanger, characterized by reacting.   2. A solution containing a metal alkoxy compound and / or a metal chelate compound having at least one metal selected from the group consisting of Ti, Zr and Al is brought into contact with the surface layer of the hydrophilic organic coating. A method for producing the heat exchanger according to 1.   The method for producing a heat exchanger according to claim 2, wherein the content of the metal alkoxy compound and / or metal chelate compound in the solution is 10% by mass or less.   The said fin is joined to the pipe through which a refrigerant | coolant passes after forming the said hydrophilic organic film on the said fin and before making the said solution contact with the said hydrophilic organic film. A method for producing a heat exchanger according to claim 1. A heat exchanger having fins with coatings formed thereon,
The coating comprises: a hydrophilic organic coating formed on the fin; and a metal alkoxy compound having at least one metal selected from the group consisting of Ti, Zr and Al on the surface of the hydrophilic organic coating and / or A heat exchanger comprising a reaction layer obtained by reacting a metal chelate compound.

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