JP6002366B2 - Aluminum fin material for heat exchanger - Google Patents

Description

  The present invention relates to an aluminum fin material for a heat exchanger provided with a lubricant.

Aluminum and aluminum alloys (hereinafter also referred to as aluminum materials) are widely used as constituent materials for fins of heat exchangers such as room air conditioners in terms of lightness, workability, and thermal conductivity. This fin for heat exchangers made of aluminum material is formed with a corrosion-resistant undercoat and a hydrophilic film on the surface in this order in advance, and is excellent in the adhesion of the hydrophilic film in a long-term moisture-resistant environment, and has the desired hydrophilicity and corrosion resistance. A structure that can be maintained for a long time is adopted. Moreover, the precoat fin for heat exchangers having a structure having this kind of hydrophilic film is used as a precoat fin for heat exchangers compatible with various air conditioners after being pressed into a fin shape corresponding to various applications.
This precoat fin for a heat exchanger usually needs to prevent water droplets condensed on the surface of the fin from blocking the fin gap, resulting in an increase in ventilation resistance and a decrease in heat exchange efficiency. A protective coating is provided.

As an example of a pre-coated fin having such a hydrophilic film, a structure in which a water glass-based hydrophilic film is formed by applying a mixture of a water-soluble organic polymer compound and an inorganic silicate is known.
In addition, there is known a fin for a heat exchanger having a type of film structure in which a water-based hydrophilic film is formed after a base film made of an organic polymer resin is formed instead of the above-described inorganic corrosion-resistant film. It has been. (See Patent Documents 1 and 2)

However, since this type of pre-coated fin has an inorganic corrosion-resistant film on its surface, there is a problem that the press die is likely to be worn during fin molding due to the hardness of the inorganic corrosion-resistant film.
That is, the conventional pre-coated fin is desired to have a structure that can reduce the wear of the processing mold after solving the above-mentioned dew condensation problem.
In addition, as a pre-coated fin for heat exchangers, a corrosion-resistant film containing polyhydric alcohol as a main component and a hydrophilic film are formed in this order, and after the formation of the hydrophilic film, it is subjected to water washing or pickling treatment to provide corrosion resistance and hydrophilicity. Those having an excellent film structure are known. (See Patent Document 3)

Japanese Examined Patent Publication No. 2-42389 Japanese Patent Publication No. 3-77440 JP-A-11-83384

From the above background, in the case of pre-coated fin material, when press workability and hydrophilicity are taken into account, a hydrophilic film is applied to the surface of the aluminum material and then a lubricating layer is further applied to produce a product. Yes. If this lubrication layer is coated on the hydrophilic film before press working, the lubricity of the fin material can be improved with respect to the mold during press working, and the object can be obtained without seizure or knitted meat. Precoated fins with dimensional accuracy can be formed.
However, there is a lubricating layer on the surface of the pre-coated fin material, and pressing the fin material using a mold also means that the lubricating layer is rubbed against the mold being processed, so the lubricating layer is slippery. If the lubricant that constitutes the lubricating layer is a component that can be easily transferred to the mold, the lubricant gradually accumulates on the mold side and repeats the press work, resulting in excessive lubricant. Tend. As a result, the fin material becomes more slippery in the mold, and the feed pitch of the fin material may be disturbed during press working. If the feed pitch at the time of pressing is disturbed, the pitch and shape of each part of the fin material will be disturbed and the molding accuracy of the fin material will decrease.As a result, a heat transfer tube such as a copper tube for refrigerant circulation is inserted into the fin material insertion hole, When assembling as an exchanger, there is a possibility that problems such as difficulty in inserting the heat transfer tube may occur.

As a result of studying the forming behavior of the fin material during the above-described press working, the present inventor found that the lubricant for the aluminum fin of the heat exchanger is important for the processing of the fin, but if the lubricant is too soft, the press It has been found that the lubricant is excessively transferred to the processing mold and is easily over-lubricated, and the amount of feed to the mold becomes unstable in the aluminum material for forming the aluminum fin, causing the above-mentioned problems.
The present invention has been made in view of the above-described background, and has a structure in which a lubricating layer is formed on the outer surface, and includes a lubricating layer that is difficult to transfer to a mold even if processed into a desired shape by pressing. An object of the present invention is to provide an aluminum fin material for a heat exchanger that does not cause over-lubrication and can improve molding accuracy.

The aluminum fin material for a heat exchanger of the present invention has a hydrophilic film formed on the outer surface of a fin material body made of aluminum or an aluminum alloy and having a thickness of 0.04 mm or more and 0.10 mm or less. consists ether, molecular weight of 6 000 above, 150,000, penetration, characterized in that 10 or less of the lubricating layer is formed.
The aluminum fin material for a heat exchanger according to the present invention is characterized in that the lubricating layer is made of a water-soluble polyether having a molecular weight of 20,000 to 150,000 and a penetration of 4 or less.
The aluminum fin material for a heat exchanger of the present invention is characterized in that the hydrophilic film is made of a water-soluble acrylic resin having a film thickness of 0.5 μm or more and 3 μm or less.

Thickness 0.04mm or more, the molecular weight through the hydrophilic film on the outer surface of the fin material body consisting of aluminum or aluminum alloy 0.10mm 6 000 or more, penetration comprising a lubricating layer of 10 or less at 150,000 If it is pressed and formed into aluminum fins for heat exchangers, the amount of lubricant transferred to the mold for press molding can be suppressed to an appropriate amount, and excess lubricant can be removed from the mold side. Therefore, when the aluminum fin material is formed by press working, the aluminum material can be sent and pressed with high accuracy without disturbing the pitch. Therefore, since an aluminum fin material having a target dimensional accuracy can be processed into a target shape, there is no processing unevenness, and assembly can be performed without causing problems when a heat transfer tube such as a copper tube is inserted and assembled as a heat exchanger.

Further, if the outer surface has a lubricating layer having a molecular weight of 20,000 or more and 150,000 or less and a penetration of 4 or less, it can be applied uniformly without pulling the thread when applying the lubricant. A uniform lubricating layer can be formed. By providing the lubricating layer, it becomes possible to lubricate without impairing the hydrophilicity of the underlying hydrophilic film, and has excellent hydrophilicity even after press working , in terms of transfer rate during press working A particularly advantageous heat exchanger aluminum fin material is obtained.

The perspective view which shows one structural example of the aluminum fin for heat exchangers which consists of an aluminum fin material which concerns on this invention. FIG. 2 is a perspective view showing an example structure of a heat exchanger that includes a plurality of aluminum fins shown in FIG. 1. The fragmentary sectional view which shows an example of the aluminum fin material which concerns on this invention. The fragmentary sectional view which shows the positional relationship of the aluminum fin material and holding member shown in FIG. FIG. 4 is a partial cross-sectional view showing an example of a state in which the lubricant on the surface of the aluminum fin material shown in FIG. 3 is transferred to the suppressing member side.

Hereinafter, the lubricant, the aluminum fin material, and the heat exchanger of the present invention will be described in detail.
FIG. 1 is a perspective view showing an example of an aluminum fin made of an aluminum fin material according to the present invention, FIG. 2 is a perspective view showing an example of a heat exchanger having a plurality of the aluminum fin material, and FIG. It is a fragmentary sectional view.
The aluminum fin 10 of this embodiment has a long and narrow strip shape, and trumpet-like flares 11 for passing a copper heat transfer tube are arranged in a single row or a plurality of rows at predetermined intervals in the length direction. . Moreover, the slit 12 is provided in the surface of the aluminum fin 10 for the purpose of the improvement of heat-transfer performance.
As an example, the aluminum fin 10 shown in FIG. 1 includes a fin material 16 in which a hydrophilic film 14 and a lubricating layer 15 are formed in this order on both surfaces of a fin material body 13 made of aluminum or an aluminum alloy, as shown in FIG. The fin material 16 is prepared and subjected to press working using a mold, and the flare 11 and the slit 12 are press-molded.

FIG. 2 is a perspective view showing an example of a heat exchanger provided with the aluminum fin 10.
A heat exchanger 20 shown in FIG. 2 includes the aluminum fin 10 shown in FIG. 1 and a plurality of heat transfer tubes 30. The aluminum fins 10 are arranged in parallel at regular intervals, and air flows through the gaps between the plurality of aluminum fins 10. The heat transfer tubes 30 are provided so as to penetrate through the flares 11 of the plurality of aligned aluminum fins 10, and the refrigerant flows through the inside thereof.
Since the heat exchanger 20 shown in FIG. 2 includes a plurality of the aluminum fins 10 shown in FIG. 1, water attached to the surface of the aluminum fin 10 (the surface of the hydrophilic film 14 or the surface of the lubricating layer 15) can be easily obtained. It spreads wet and flows down, and water drops are unlikely to occur. For this reason, it is suppressed that the bridge of water is formed in the gap between the adjacent wall surfaces of the aluminum fin 10, and the ventilation resistance of air can be reduced. Therefore, even if it is a case where it is used over a long period of time, the heat exchanger which a heat exchange capability cannot fall easily can be provided.

  As the fin material main body 13 constituting the aluminum fin 10, an aluminum or aluminum alloy plate or the like that has been subjected to a surface treatment such as a phosphoric acid chromate treatment or an anodizing treatment to improve the corrosion resistance is preferably used. The shape of the fin material main body 13 is not particularly limited, and is appropriately selected according to the form of the heat exchanger to which the fin material is applied. For example, in this embodiment, the fin material body 13 has a flat plate shape, but the fin material body 13 is pressed into a shape necessary for a heat exchanger to be applied, such as a corrugated plate shape or a bellows shape. Therefore, the shape of the fin body 13 is not limited in the present invention.

  Further, the aluminum alloy material constituting the fin material body 13 is not particularly limited, and aluminum or an aluminum alloy having a composition generally applied to fins for heat exchangers may be appropriately used. In addition, if illustrated, JIS regulation A1050, A1200 material, etc. can be illustrated.

  Although the thickness of the fin material main body 13 is not particularly limited, it is desirable to make it as thin as possible in order to cope with the downsizing of the heat exchanger and to ensure heat exchange efficiency. As an example, the thickness can be set to 0.10 mm or less, and by setting the plate thickness of the fin material body 3 to 0.10 mm or less, the heat exchanger can be made thinner and smaller. In order to maintain sufficient strength as the fin material main body 13, the plate thickness of the fin material main body 13 is preferably 0.04 mm or more.

It is desirable that the hydrophilic film 14 coated on both surfaces of the fin material body 13 is a film whose coating film adhesion is enhanced by applying a coating film containing a polymer compound and then baking the coating film.
As an example of the hydrophilic film | membrane 14, resin which has hydrophilic functional groups, such as 1 type, or 2 or more types, among a hydroxyl group, a carboxyl group, an ester group, and an ether group can be illustrated. More specifically, examples thereof include, but are not limited to, acrylic resins mainly composed of polyacrylic acid, polyvinyl alcohol resins, cellulose resins, and urethane resins.

  The thickness of the coating film forming the hydrophilic coating 14 is not particularly limited, but is desirably 3 μm or less. When the thickness of the coating film exceeds 3 μm, the thickness of the hydrophilic coating film 14 obtained by baking the coating film also increases. As a result, when the fin material 10 is incorporated in the heat exchanger, the tube and the fin are connected via the relatively thick hydrophilic film 14, and the heat transfer resistance between the tube and the fin may increase. is there. If the hydrophilic film 14 is too thin, the effect of providing the hydrophilic film 14 may not be sufficiently obtained. From the above viewpoint, it is desirable to set the thickness of the coating film to about the lower limit of the thickness range where necessary hydrophilicity is obtained. Specifically, the thickness of the hydrophilic coating 14 is about 0.5 μm or more. It can be.

The lubricating layer 15 formed on the hydrophilic film 14 is a layer coated with a lubricant having a molecular weight of 5000 or more and 200,000 or less and a penetration of 10 or less, which will be described later. Specifically, water-soluble polyether, polyethylene glycol, polyoxyethylene alkyl ether, polyoxyethylene hydrogenated castor oil ether, or the like can be used as the lubricant constituting the lubricating layer 15.
Further, when the lubricating layer is formed using polyethylene oxide (PEO) whose molecular weight of the lubricant constituting the lubricating layer 15 is 300,000, the friction coefficient can be suppressed and a surface that is not slippery can be obtained. However, if the lubricant is applied by a general roll coater as equipment for mass production, threading occurs due to the excessively large molecular weight, making it difficult to apply the lubricant, but lubrication with a molecular weight of 200,000 or less. Such a problem does not occur in the agent. In view of this, it is preferable that the upper limit of the molecular weight of the lubricant is 200,000. Furthermore, the upper limit of the molecular weight of a preferable lubricant is 150,000 or less.

If the molecular weight of the lubricant is less than 5000, there is a high possibility that the lubricating layer 15 will not become a coating film, and there is a problem that the tactile sensation remains sticky. Considering these, the molecular weight of the lubricant needs to be 5000 or more and 200,000 or less.
Further, the lubricant needs to be water-soluble. If the lubricant is not water-soluble, it adversely affects the hydrophilicity of the hydrophilic coating 14, and the contact angle increases and the hydrophilicity decreases. When the contact angle increases, the water droplets close the gaps between the plurality of fins arranged, the ventilation resistance when the heat exchanger is used increases, and the heat exchange efficiency decreases.

For the penetration that indicates the hardness of the lubricating layer 15, the value defined in JIS K2235 is applied. A needle having a weight of 100 g is placed on a lubricating layer formed by dissolving and solidifying the lubricant at one end, left for 5 seconds, and a value obtained by multiplying the length (mm) stuck in the lubricating layer after 5 seconds by 10 times is adopted. It is necessary that the penetration is 10 or less. If the penetration is 10 or less, the lubricating layer 15 is reasonably hard, so that the ratio of the lubricant that constitutes the lubricating layer 15 to the mold is reduced.
If the penetration exceeds 10 and the lubrication layer 15 becomes too soft, the amount of lubricant that constitutes the lubrication layer is transferred to the mold, and the fin material slips too much in the mold. Therefore, as a result of variation in the feeding accuracy of the aluminum material to be sent to the mold and a result of the aluminum material slipping in the mold, press work tends to be defective, and the fin material may cause irregular shapes.

  As described above, if the fin material 16 is provided with the hydrophilic film 14 and the lubricating layer 15, the lubricant constituting the lubricating layer 15 is made of gold even when the pressing is performed with a mold during the pressing. Since the rate of transfer to the mold side is low and excessive lubricant does not accumulate on the mold side, the aluminum material does not slip excessively through the mold even when repeated pressing is performed. Since the aluminum fin material can be fed into the mold at a pitch, high-precision pressing can be performed. As a result, the aluminum fin 10 for a heat exchanger with a well-formed shape can be obtained by press working. Therefore, when the heat exchanger 20 is configured by assembling a plurality of aluminum fins 10 with the heat transfer tube 30 as shown in FIG. The heat transfer tube 30 can be reliably inserted into the flare 11 of the aluminum fin 10 and assembled, and no assembly failure occurs.

In the above description, the reason for providing the lubrication layer 15 in the fin material 16 has been described for the purpose of imparting lubricity to the mold. However, as shown in FIGS. The same over-lubrication prevention effect is also obtained when the fin member 16 slides in a state where the attached plate holding member 18 is pressed and the surface portion of the lubricant 15 is scraped off by the plate holding member 18. Can be obtained.
That is, in a state where the fin material 16 is being fed while being horizontally moved with respect to the mold, when the fin material 16 is to be fed into the mold in a stable state while suppressing the upper and lower shakes of the fin material 16, the fin material 16 A configuration in which the plate holding member 18 presses the upper surface of 16 may be employed. Here, when the fin material 16 moves under the plate holding member 18, a part of the surface of the lubricant 15 is partially transferred to the bottom surface side of the plate holding member 18. If the fin material has a structure, only a part of the surface side of the lubricant 15 can be suppressed to a level that is thinly transferred to the bottom surface side of the plate holding member 18 as indicated by reference numeral 15a in FIG. The lubricant 15 is not deposited on the plate holding member 18 side.
For this reason, when the fin material 16 is fed, over-lubrication does not occur at the portion held by the plate pressing member 18, so that the fin material 16 can be accurately fed to the mold side and a precise press in the mold. There is an effect that can be processed.

Specific examples of the present invention will be described below, but the present invention is not limited to these examples.
A 0.10 mm-thick aluminum fin material made of JIS A1050 alloy aluminum was subjected to phosphoric acid chromate treatment, and then a hydrophilic coating film made of acrylic resin was applied and formed at a coating amount of 1 g / m ^2. After the hydrophilic coating film was baked at 220 ° C. to make a hydrophilic coating film, the following various tests were performed using the aluminum fin material with the hydrophilic coating film.

<Paintability test>
When a 10% aqueous solution is prepared using the type of lubricant shown in Table 1, an aluminum fin material is immersed in the aqueous solution and pulled out from the aqueous solution, the thread is pulled out from the pulled-up state, and the stringing is performed. If the portion extends 30 mm or more or the stringing state is connected from the fin material to the aqueous solution, it is judged that stringing is likely to occur, and the paintability test was rejected. (Indicated in the column of thread pullability in Table 1 by x)
<Mold transferability test: Bowden dynamic friction coefficient measurement>
A mold transferability test was performed using a test piece of each lubricating layer shown in Table 1 on the aluminum fin material provided with the hydrophilic film, with an application amount of 0.1 g / m ² . A test was carried out in which the surface of the lubricant was rubbed by putting Kim Towel (Nippon Paper Crecia Co., Ltd., trade name) on the steel ball of the contact of the friction coefficient measuring device. The lubricant is transferred onto the surface of the Kim towel. The friction coefficient is measured with a contactor covered with a Kim towel after rubbing the lubricating layer on the surface of an aluminum fin material to which no lubricant is applied, and whether or not the friction coefficient is reduced by the influence of the lubricant is evaluated. did. The rate of decrease was evaluated with respect to the friction coefficient measured when there was no transfer of the lubricant.

<Contact angle>
A 10% water-soluble acrylic resin is applied to an aluminum fin material treated with phosphoric acid chromate (about 1 g / cm ² ), and each of the above-mentioned 3% aqueous lubricants is used, and about 0.1 g / m by a bar coater. The film of No. ² was applied and the water droplet contact angle was evaluated.
<Penetration>
As specified in JIS K2335, place a needle with a weight of 100 g on the one-melted lubricant and let it stand for 5 seconds, then multiply the length (mm) that the needle is stuck after 5 seconds by 10 times. Asked.
The above results are shown in Table 1 below. Table 1 lists the lubricant components used, their molecular weights, the names of the lubricants corresponding to each molecular weight notation, and the name of the manufacturer, as well as the measurement results of the penetration, the test results of the stringiness test, the mold transfer rate A measurement result and a contact angle measurement result are shown.

From the results shown in Table 1, the comparative sample with a molecular weight of 1000, 4000 has a large penetration, the result of the mold transferability test deteriorates, and the comparative sample with a molecular weight of 300,000 has poor stringiness and paintability. Worsened. Moreover, the results of the mold transferability test deteriorated in Comparative Examples 12 and 15 where the penetration was over 10.
From the results shown in Table 1, it was found that the range of 5000 to 200,000 is preferable for the molecular weight of the lubricant. Moreover, it was proved that all the characteristics were excellent in the molecular weight range of 6000 to 150,000. Furthermore, it can be seen that when the molecular weight is in the range of 60,000 to 150,000 and the penetration is particularly low, the transfer rate is particularly advantageous, and the contact angle is maintained at a low value and is more excellent.
In addition, the contact angle increased with a polyvinyl alcohol lubricant.
From the above, it has been found that the purpose can be achieved if the lubricant is composed of a water-soluble resin and has a molecular weight of 5000 or more and 200,000 or less and a penetration of 10 or less.

  DESCRIPTION OF SYMBOLS 10 ... Fin, 11 ... Flare, 12 ... Slit, 13 ... Fin material main body, 14 ... Hydrophilic film, 15 ... Lubrication layer, 16 ... Fin material, 18 ... Plate restraining member, 20 ... Heat exchanger, 30 ... Heat transfer tube .

Claims (3)

Aluminum or an aluminum alloy plate thickness 0.04mm or more, the outer surface of the following fin material body 0.10 mm, the hydrophilic film is formed, thereon, made from water-soluble polyether, molecular weight of 6 000 or more, 15 An aluminum fin material for a heat exchanger, wherein a lubricating layer having a penetration of 10 or less and a penetration of 10 or less is formed.   The aluminum fin material for a heat exchanger according to claim 1, wherein the lubricating layer is made of a water-soluble polyether having a molecular weight of 20,000 to 150,000 and a penetration of 4 or less.   The aluminum fin material for a heat exchanger according to claim 2, wherein the hydrophilic film is made of a water-soluble acrylic resin having a film thickness of 0.5 µm or more and 3 µm or less.

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