JP5781726B2 - Heat exchange fin material - Google Patents

Description

  The present invention relates to a fin material used for a heat exchanger such as an air conditioner.

  Generally, a heat exchanger of an air conditioner is constituted by a copper tube and a plurality of fins attached to the tube, and performs heat exchange between the refrigerant flowing in the tube and the outside air. In such a heat exchanger, it is advantageous that the distance between the fins is narrow in order to achieve both the miniaturization of the heat exchanger and the heat exchange performance.

  However, when the heat exchanger is used on the cooling side, water may condense on the fins 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 rate decreases. For this reason, the process which provides wettability (hydrophilicity) to the surface of a fin is given.

  As the hydrophilization treatment method, a method of applying and baking sodium silicate (water glass) on the fin material surface (see Patent Document 1), inorganic particles such as water glass, silica, aluminum hydroxide, titania (titanium dioxide) ( There is known a method of applying a paint containing a hydrophilic resin mixed with an inorganic filler to form a hydrophilic film in which the inorganic filler is dispersed (see Patent Documents 2 to 5). In this case, the inorganic filler forms an irregular shape on the surface of the film, thereby imparting hydrophilicity to the film.

  There is also known a method of forming a hydrophilic polymer film (hydrophilic film) by appropriately combining hydrophilic polymers such as acrylic resin, polyvinyl alcohol, and carboxymethyl cellulose and applying them to the surface of the fin material. In this method, hydrophilicity is obtained only with an organic material without using an inorganic material.

  In the fin material provided with these hydrophilic films, the water adhering to the surface spreads wet, so that water droplets are hardly generated, water bridges are hardly formed between the fins, and the airflow resistance can be suppressed.

  On the other hand, corrosion resistance is also required for fin materials of heat exchangers used outdoors such as for air conditioners. For example, in a beach area and the like, it is easily corroded because it is greatly affected by chloride ions and is in contact with a copper tube to form a corrosion cell. In order to achieve both hydrophilicity and corrosion resistance in such a fin material, a corrosion-resistant film (for example, epoxy paint, acrylic-amino resin paint, polyester-amino resin paint, etc.) is applied to the first layer, and then It is necessary to form a hydrophilic film as described above.

Japanese Patent Publication No.55-1347 Japanese Patent Publication No.57-46000 Japanese Patent Publication No.59-8372 JP-A-61-225044 Japanese Examined Patent Publication No. 62-61078

  However, when sodium silicate is applied to form a hydrophilic film as described above, the adhesion to the resin film having corrosion resistance is remarkably inferior, causing delamination between the corrosion resistant film and the hydrophilic film. Cheap.

  In addition, when forming a hydrophilic film in which inorganic fillers are dispersed and disposed on the corrosion-resistant film, in order to provide sufficient hydrophilicity, the size of the unevenness is set to 0.5 μm or more, and the average particle size is 1 μm or more. It is necessary to add particles. In order to hold particles of 1 μm or more in the coating film, a film thickness of about 1 μm or more is required. In order to form a coating film having a film thickness of 1 μm or more, although it depends on the solid content at the time of coating, it is generally necessary to dry and bake a coating film having a wet film thickness of 5 μm or more. That is, since the coating process of two times of corrosion-resistant coating and a hydrophilic film is needed, the enlargement of an installation etc. becomes a problem. On the other hand, if the coating film is too thin, the added filler tends to fall off, and there is a risk that problems such as mold clogging may occur during the pressing process.

  In the case of a hydrophilic polymer film made of an organic material, generally a polymer body mainly composed of acrylic acid is used. In the case of such a hydrophilic polymer film, sufficient hydrophilicity cannot be obtained unless a film thickness of 1 μm is formed, and this series of resins needs to be baked at 200 ° C. or higher. There arises a problem that the equipment needs to be enlarged.

  The present invention has been made in view of such circumstances, and an object of the present invention is to realize a heat exchange fin material that has both corrosion resistance and hydrophilicity, and that hardly increases ventilation resistance even in a heat exchanger with a small fin pitch. And

In the present invention, a fin body made of an aluminum material and plate-like inorganic particles formed on the surface of the fin body and having an average particle diameter of 1 μm or more and 10 μm or less are dispersedly arranged, and the thickness is 0.3 μm or more and 3 μm or less. A corrosion-resistant film and a hydrophilic film formed on the corrosion-resistant film, a part of the plate-like inorganic particles are exposed on the hydrophilic film, and the surface of the hydrophilic film is formed in an uneven shape. The heat exchange fin material.

  According to the fin material for heat exchange, by disposing and arranging plate-like inorganic particles of an appropriate size, an uneven shape that realizes sufficient hydrophilicity is formed on the surface of the coating film, and the hydrophilic coating film is a plate. Since the surface is covered so as to expose the fibrous inorganic particles, it has sufficient hydrophilicity and can suppress water droplets adhering in a bridge shape between the fins. Also, by setting the corrosion-resistant film relatively thick and holding the plate-like inorganic particles in this corrosion-resistant film, the thickness of the hydrophilic film can be kept small, so the drying process of the hydrophilic film can be done with a simple device It can be carried out.

  In this heat exchange fin material, it is preferable that the hydrophilic film has a thickness of 0.01 μm or more and 0.5 times or less of the average particle diameter of the plate-like inorganic particles. When the film thickness is less than 0.01 μm, it is difficult to obtain sufficient hydrophilicity. Moreover, when the film thickness exceeds 0.5 times the average particle diameter of the plate-like inorganic particles, the particles are easily buried in the hydrophilic film, and sufficient hydrophilicity is difficult to be obtained.

  Moreover, it is preferable that the said hydrophilic film | membrane contains either the acrylic resin containing polyvinyl alcohol or methacrylic acid. When these resins are used, the hydrophilicity is good, and necessary adhesion and hardness can be obtained only by drying, and coating film peeling and coating film collapse do not occur during processing.

  According to the present invention, both the corrosion resistance and the hydrophilicity are achieved without the need for a large drying apparatus, and the filler is prevented from falling off, so that the manufacturing cost is suppressed, and the draft resistance due to the water droplet bridge between the fins is suppressed. Therefore, it is possible to realize a heat exchange fin material that has an excellent heat exchange rate and can prevent the occurrence of problems due to the falling off of the filler.

It is sectional drawing which shows the fin material for heat exchange of this invention.

Hereinafter, the fin material for heat exchange according to the present invention will be described.
As shown in FIG. 1, the heat exchange fin material 10 is formed on a fin main body 11 made of an aluminum material and the surface of the fin main body 11, and plate-like inorganic particles having an average particle diameter of 1 μm or more and 10 μm or less (hereinafter, A portion of the inorganic filler 12, comprising a corrosion-resistant coating 13 having a thickness of 0.3 μm or more and 3 μm or less, and a hydrophilic coating 14 formed on the corrosion-resistant coating 13. Is exposed on the hydrophilic film 14.

  The aluminum material forming the fin body 11 may be a non-treated one that has been degreased or a surface treatment such as phosphoric acid chromate.

  As the inorganic filler 12, talc, mica, kaolinite and the like can be suitably used. Although it does not specifically limit as an addition amount of the inorganic filler 12, It is preferable that it is about 30-200 weight part with respect to 100 resin solid content.

  If the average particle size of the inorganic filler 12 is less than 1 μm, the surface exposure is small and the hydrophilicity is low, and if it exceeds 10 μm, the particles exposed on the surface easily peel off. Here, the average particle diameter of the inorganic filler 12 is the average value of the longest diameter of the particle and the longest diameter in the direction perpendicular to the longest diameter direction when the flat portion of the particle is observed from above with a microscope. Measured for individual particles and refers to the average value of them. The aspect ratio of the cross section in the plate thickness direction of the inorganic filler 12 is 10 or more on average.

When the inorganic filler 12 is set to have an average particle size of 1 μm to 10 μm and the thickness of the corrosion-resistant film to be 0.3 μm to 3 μm, the surface of each particle is oriented parallel to the surface of the fin body 11 in the coating film. It's easy to do. For this reason, since the area of the inorganic filler 12 occupying the surface of the fin material for heat exchange is large compared with the case where spherical, needle-like, and irregular shaped powders are added, it is hydrophilic even if the amount of particles added is small. Sex is easy to express.
Further, since the inorganic filler 12 is a plate-like particle and is easily oriented in parallel to the surface of the fin main body 11, moisture permeation from the coating film surface to the lower layer can be suppressed. Corrosion resistance is improved compared to additive-free products.

  The corrosion-resistant film 13 is not particularly limited, but an epoxy-based, acrylic-based, polyurethane-based paint or the like is preferably used and holds the inorganic filler 12. The corrosion-resistant film that holds the inorganic filler 12 is formed by baking and curing the inorganic filler 12 after the paint is in a liquid state.

  If the film thickness of the corrosion-resistant film 13 is less than 0.3 μm, sufficient corrosion resistance cannot be obtained, and the inorganic filler 12 is not sufficiently fixed to the coating film. Is easy to peel off. On the other hand, if the film thickness of the corrosion-resistant film 13 exceeds 3 μm, the inorganic filler 12 is difficult to be exposed on the surface and is difficult to be oriented in parallel, so that sufficient hydrophilicity cannot be obtained.

  The corrosion-resistant film 13 is essentially made of a water-repellent resin, and even if the inorganic filler 12 is added thereto, a certain degree of hydrophilicity can be imparted. However, if the fin pitch is narrow, sufficient hydrophilicity cannot be obtained with only the corrosion-resistant film 13 in which the inorganic filler 12 is dispersed and held. Therefore, in this heat exchange fin material 10, a hydrophilic film 14 having higher hydrophilicity is formed on the surface layer.

  In the hydrophilic film 14, the inorganic filler 12 protruding from the surface of the corrosion-resistant film 13 is not completely covered with a hydrophilic resin such as an acrylic resin containing polyvinyl alcohol or methacrylic acid on the corrosion-resistant film 13 holding the inorganic filler 12. It is formed by coating with a thickness and improves the hydrophilicity of the surface. These hydrophilic resins do not require baking, and a certain degree of film strength can be obtained simply by drying the solution. In addition, these hydrophilic resins alone cannot obtain sufficient hydrophilicity, but the hydrophilic film 14 has sufficient hydrophilicity due to the uneven shape formed by the inorganic filler 12 protruding from the surface.

  In order to form the hydrophilic film 14, roll coating is generally used as a coating method of the hydrophilic resin, but it is only necessary to apply a very thin coating, so that coating is performed by dipping, spraying, or the like. You can also. Moreover, since these resins can obtain a certain degree of film strength simply by drying, they can be dried even by air at room temperature.

  When slipperiness is required on the surface of the hydrophilic film 14 in order to improve processability, it is possible to apply a water-soluble and slippery substance such as polyethylene glycol or various solid surfactants. . By applying these substances, even if the inorganic filler 12 is covered, it flows out due to condensed water during use, so that the inorganic filler 12 is exposed to the surface and the hydrophilicity can be recovered.

Here, the Example and comparative example which concern on the fin material for heat exchange of this invention are demonstrated.
(Creation of corrosion-resistant film in which plate-like inorganic particles are dispersed)
First, as shown in Table 1, the corrosion-resistant film of each example and comparative example was formed. Specifically, various plate-like inorganic particles having different average particle diameters are dispersed in various corrosion-resistant resins in various addition amounts, and coated on an aluminum plate of A1050 subjected to phosphoric acid chromate treatment with various coating thicknesses, and an atmosphere at 240 ° C. The film was held for 1 minute and baked to prepare corrosion-resistant films A to G, s, and t. In addition, various corrosion-resistant resins were coated with various coating thicknesses on an aluminum plate of A1050 that was subjected to phosphoric acid chromate treatment without adding plate-like inorganic particles, and kept in an atmosphere at 240 ° C. for 1 minute for baking. Corrosion resistant films p to r were prepared.

  Among these corrosion-resistant films A to G and p to t, A to G are sizes within a range in which the film thickness is included in the present invention. On the other hand, p to r are out of the scope of the present invention because no plate-like inorganic particles are added, and s and t are out of the scope of the present invention in terms of film thickness.

(Creation of hydrophilic film)
Next, a hydrophilic film was formed by applying various hydrophilic resins on each of the corrosion-resistant films A to G and p to t prepared as described above and blowing them at room temperature to dry them. Each hydrophilic resin of the plate-like inorganic particles in the heat exchange fin materials of Examples 1 to 18 and Comparative Examples 1 to 7 according to combinations of various hydrophilic resins, coating methods, film thicknesses and respective corrosion-resistant coatings. Table 2 shows the presence or absence of protrusion from the surface of the film.

(Evaluation of film)
And about the contact angle, water wettability, corrosion resistance, and abrasion resistance about the heat exchange fin material of Examples 1-18 and Comparative Examples 1-7 which formed the film | membrane as mentioned above, as shown in Table 3. Each was evaluated.

  Regarding the contact angle, after 24 hours of washing as a pretreatment, the water contact angle is measured, the evaluation value 1 is less than 30 °, the evaluation value 2 is 30 ° or more and less than 40 °, and the evaluation value 3 is 40 ° or more. did. In the heat exchange fin material, if the evaluation values are 1 and 2, it can be judged as a practically good level.

  Regarding water wettability, the heat exchange fin material kept at 10 ° C. by a cooler in an environment of 100% humidity and 40 ° C. was left to stand for 10 minutes to visually observe the dew condensation state, and the entire surface was wet. An evaluation value of 5, an evaluation value of 4 for a slightly repelled state, an evaluation value of 3 for a half-wet area, an evaluation value of 2 for a slightly wet state, and an evaluation value of 1 for an almost entirely repelled state did. In the heat exchange fin material, if the evaluation values are 4 and 5, it can be determined that the heat exchanger can be used even in a heat exchanger having a narrow fin pitch.

  For corrosion resistance, the corrosion state after 1000 hours of JIS Z2371 salt spray test was visually observed. N. 9.8 or higher is evaluated value 1, R.V. N. 9.0 or higher is evaluated value 2, R.I. N. An evaluation value of 3 was set to less than 9.0. An evaluation value of 1 is required for the corrosion-resistant heat exchange fin material.

  Regarding the abrasion resistance, the tissue paper and the steel ball were reciprocated 10 times on the coating film of each heat exchange fin material with a load of 100 g applied to a steel ball having a diameter of 7 mm through four pieces of tissue paper. After coating, the surface condition of the coating film is visually observed. If there is no change, the evaluation value is 1. If the coating film is slightly scraped, the evaluation value is 2. If the base is reached (the surface of the fin body is exposed). In the case), the evaluation value was 3. In the heat exchange fin material, if the evaluation values are 1 and 2, it can be determined that there is no practical problem. In all the heat exchange fin materials of the examples and comparative examples, the abrasion resistance was at a practical level.

  As shown in Table 3, in the heat exchange fin materials according to Examples 1 to 18 of the present invention, all of the contact angle, water wettability, corrosion resistance, and abrasion resistance were good.

  On the other hand, it was confirmed that the heat-exchange fin materials of Comparative Examples 1 and 2 that did not form a hydrophilic film within the scope of the present invention with respect to the corrosion-resistant film were inferior in contact angle and water wettability.

  Moreover, it has confirmed that the heat exchange fin material of Comparative Examples 3-5 which formed the hydrophilic film | membrane on the corrosion-resistant film | membrane which has not disperse | distributed plate-like inorganic particle is also inferior to a contact angle and water wettability.

  Further, the heat exchange fin material of Comparative Example 6 in which the hydrophilic film is formed on the corrosion resistant film whose thickness is smaller than the range of the present invention has good contact angle and water wettability, but may have poor corrosion resistance. It could be confirmed.

  In addition, the heat exchange fin material of Comparative Example 7 in which the hydrophilic film was formed on the corrosion resistant film having a film thickness larger than the range of the present invention had good corrosion resistance and abrasion resistance, but the contact angle was relatively large. Moreover, it was confirmed that the wettability was inferior.

  As described above, according to the fin material for heat exchange of the present invention, since the hydrophilic film is thin, a large-sized drying apparatus is not required, and it can be manufactured at low cost. In addition, since it has both corrosion resistance and hydrophilicity, it can be used outdoors, and resistance to ventilation caused by a bridge of water droplets between fins is suppressed, and heat exchange is excellent. Furthermore, since the inorganic filler is held by the relatively thick corrosion-resistant film, the drop of the inorganic filler is suppressed and the occurrence of problems due to the drop of the inorganic filler can be prevented.

  In addition, this invention is not limited to the thing of the structure of the said embodiment, In a detailed structure, it is possible to add a various change in the range which does not deviate from the meaning of this invention.

10 Heat exchange fin material 11 Fin body 12 Plate-like inorganic particles (inorganic filler)
13 Corrosion resistant coating 14 Hydrophilic coating

Claims (3)

A fin body made of an aluminum material;
Corrosion-resistant film formed on the surface of the fin body, in which plate-like inorganic particles having an average particle size of 1 μm or more and 10 μm or less are dispersed and having a thickness of 0.3 μm or more and 3 μm or less,
With a hydrophilic film formed on this corrosion-resistant film,
A part of the plate-like inorganic particles is exposed on the hydrophilic film, and the surface of the hydrophilic film is formed in a concavo-convex shape .   2. The fin material for heat exchange according to claim 1, wherein the hydrophilic film has a thickness of 0.01 μm or more and 0.5 times or less of the average particle diameter of the plate-like inorganic particles.   The fin material for heat exchange according to claim 1 or 2, wherein the hydrophilic film contains either polyvinyl alcohol or an acrylic resin containing methacrylic acid.

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