JP5319952B2 - Resin-coated aluminum fin material - Google Patents

Description

  The present invention is a fin material made of aluminum or an aluminum alloy (hereinafter abbreviated as aluminum) used in a heat exchanger for an air conditioner, and has hydrophilicity and contamination resistance even when used for a long time as well as corrosion resistance. The present invention relates to a fin material that has been subjected to surface treatment with a resin coating layer that can be sustained and can suppress odor generation.

  The heat exchanger of an air conditioner is designed so that heat exchange is performed in a compact and efficient manner by installing aluminum fin materials with excellent thermal conductivity, workability and corrosion resistance at narrow intervals. However, in such an assembly structure of the fin material, the temperature of the fin material surface tends to be below the dew point of air during the operation of the air conditioner, so that condensed water condenses and closes adjacent fins. In this case, the lower the hydrophilicity of the surface of the aluminum fin material, the condensed water becomes hemispherical, which deteriorates the closed state, impairs the heat exchange function, or the condensed water is scattered outside the air conditioner.

  In order to solve this problem, it is necessary to hydrophilize the surface of the aluminum plate itself so that the removal and discharge of condensed water is promoted when processed into fins and used. A method has been developed. One group is a method of forming an inorganic coating layer mainly composed of a hydrophilic inorganic compound such as alkali silicate or alumina sol on the surface of an aluminum plate as a method for hydrophilizing an aluminum plate using silica (described below). Patent Documents 1 and 2).

  For example, the following Patent Document 1 improves the absorption capacity of condensed water by adding synthetic silica to the base water-soluble paint for the purpose of suppressing the adhesion of condensed water from increasing the ventilation resistance and noise of the heat exchanger. Is the way to try.

  Patent Document 2 attempts to solve the problem by blending alumina sol as a non-silica or non-glass high hydrophilic paint in order to avoid odor derived from a silica component and tool wear during fin processing.

  The illustrated hydrophilic coatings of these inorganic coating layers are excellent in hydrophilicity, but due to the high hardness of the coating, the tool wear during fin material forming processing is remarkable, and the unique cement odor of silica contained in the coating is also present. There is a problem in that odors estimated to be caused by dust odor, substances adsorbed on silica, or silica fine particles are scattered.

  Another group is a method of applying an organic resin coating layer instead of these inorganic coating layers (Patent Documents 3 and 4 below).

  For example, in Patent Document 3 below, in order to prevent prolonged residence of condensed water on the surface of the fin material from inducing a hydration reaction and promoting corrosion of aluminum, an alkali salt, ammonium salt of carboxymethyl cellulose (CMC), A surface treatment with a hydrophilic promotion film of N-methylolacrylamide is proposed.

  Patent Document 4 is a method for forming an organic resin coating layer mainly composed of polyvinyl alcohol, water-soluble nylon, water-soluble phenol, polyacrylic acid, polyethylene glycol, or the like, for the same problem. These resin coating layers can maintain hydrophilicity without generating an unpleasant odor.

  The hydrophilic coatings of these organic resin coating layers are excellent in processability, have no problems such as tool wear, and do not generate odor due to silica, but will be described below even if they are not as inorganic. Thus, it cannot be denied that there is a slight odor originating from the organic resin.

  In general, an organic resin coating layer is formed on an aluminum plate by applying a paint containing the components of the resin coating layer on the aluminum plate with a roll coater and then heating and drying. And the manufactured hydrophilic aluminum fin material turns into a heat exchanger through processes, such as press processing, copper pipe insertion, pipe expansion, and brazing. In this series of manufacturing processes, it is conceivable that a part of the resin coating layer is thermally decomposed and deteriorated due to heat applied at the time of forming the resin coating layer or manufacturing the heat exchanger.

Patent Document 5 below proposes a method in which a polyhydroxyphenol compound is used in addition to an organic resin in order to suppress odor caused by degradation of a thermal decomposition product of the organic resin coating layer. In other words, the combined use of organic hydrophilic treatment agents and antibacterial agents leads to the re-generation of odorous substances and deterioration of hydrophilicity in addition to toxicity, and a phenol compound is mixed with a water-soluble polymer compound containing a carboxyl group, etc. And attempt to control malodors. However, if the heat exchanger is used for a long period of time even if it is treated in this way, the contaminants in the air adhere to it, thereby degrading the hydrophilicity and impairing the stain resistance. However, the present situation is that the generation of odors with time cannot be prevented, and there still remains a problem with odor generation.
JP-A-55-164264, Japanese Patent Laid-Open No. 10-168381 JP-A-2-258874 JP-A-5-302042 JP 2002-88348 A

  The present invention reliably prevents tool wear and odor generation from inorganic components contained during molding in inorganic coated aluminum fin materials, and also prevents the generation of odors peculiar to organic matter remaining in organic resin-coated fin materials. In addition, an object of the present invention is to provide an aluminum fin material for a heat exchanger that can secure sufficient hydrophilicity and can maintain stain resistance.

  The present invention is a resin-coated aluminum fin material for a heat exchanger that can maintain hydrophilicity and stain resistance even after long-term use and can suppress odor generation, and has the following structures. .

(1) The surface of the aluminum plate or aluminum alloy plate is selected from dibutylhydroxytoluene, carbazide compound, L-ascorbic acid, sodium L-ascorbate, L-ascorbic acid stearate, erythorbic acid, sodium erythorbate, sodium sulfite It is characterized in that it is coated with a resin layer based on a resin containing 0.1 to 20% by weight of one or more compounds (hereinafter referred to as “compound (A)”). Resin-coated aluminum fin material.

  (2) Polyacrylic acid, polyacrylic acid salt, polyvinyl alcohol, polyacrylamide, polyethylene glycol, carboxymethylcellulose, polyvinylpyrrolidone in which the resin layer contains one or more of carboxyl group, hydroxyl group, sulfone group, amide group, and ether bond 1 or a hydrophilic resin layer based on a copolymer or mixture thereof (hereinafter referred to as “hydrophilic resin layer (B)”). Fin material.

  (3) Between the aluminum plate and the hydrophilic resin layer (B), a corrosion-resistant resin layer (hereinafter referred to as “corrosion-resistant resin”) based on a resin comprising an epoxy resin, a polyester resin, a urethane resin, or a mixture thereof. The resin-coated aluminum fin material according to (1) or (2) above, with a layer (C) ") interposed therebetween.

(4) dibutylhydroxytoluene, carbazide compounds, L- ascorbic acid, L- sodium ascorbate, L- ascorbyl stearate, erythorbic acid, sodium erythorbate, one or two or more selected sulfite sodium or al The resin-coated aluminum fin material according to (3), which is a corrosion-resistant resin layer (C) containing the compound (A).

  The aluminum fin material of the present invention is obtained by coating one or both sides of an aluminum plate with a single-layer or multiple-layer resin layer, and the basic feature is that the resin layer contains the compound (A). It is composed of resin.

That is, the compound (A), dibutylhydroxytoluene, carbazide compounds, L- ascorbic acid, L- sodium ascorbate, L- ascorbyl stearate, erythorbic acid, sodium erythorbate, sulfite sodium or it made compounds 1 type or 2 types or more are selected. Since these compounds are both water-soluble or have a certain hydrophilicity, when a resin containing this compound is deposited on an aluminum plate, the hydrophilicity of the resin layer is not deteriorated. Therefore, the condensed water generated during the operation of the heat exchanger is easy to flow with familiarity with the hydrophilicity of the fin material surface, its removal / discharge is accelerated, and the fins are not sealed with condensed water. Therefore, deterioration of heat exchange efficiency can be effectively prevented.

  Further, in the manufacturing process of the resin-coated aluminum plate and the heat exchanger, the resin-coated aluminum plate or the heat exchanger may be exposed to a high temperature environment when forming the resin coating layer, pressing the fin material, or brazing the copper pipe. At this time, a part of the resin component is thermally decomposed to have a low molecular weight and is likely to volatilize. In this case, if the above compound (A) is blended in the resin base, this compound (A) immediately captures radicals generated by the thermal decomposition reaction and suppresses further progress of the radical chain reaction. can do. Therefore, the oxidative decomposition of the resin can be suppressed to prevent the molecular weight from being lowered, and as a result, the generation of odor can be continuously suppressed.

  The effect of this compound (A) is particularly effective because it can suppress the generation of low molecular weight compounds that tend to volatilize when a low molecular weight compound such as a surfactant having a relatively low molecular weight is used in combination with the resin. .

  In order to expect such an odor suppressing effect at the same time, the amount of the compound (A) added is 0.1% by weight or more in the resin coating layer, and if it is 20% by weight or more, the hydrophilicity and productivity are lowered. Therefore, it is not preferable. More preferably, it is 0.25% to 10%, and most preferably 0.5% to 5%.

  Next, the present invention provides a polyacrylic acid or polyacrylic acid containing at least one of a carboxyl group, a hydroxyl group, a sulfone group, an amide group, and an ether bond as a resin base material to which the compound (A) is to be blended. It is characterized by using a resin of a salt, polyvinyl alcohol, polyacrylamide, polyethylene glycol, carboxymethyl cellulose, polyvinyl pyrrolidone or a copolymer or mixture thereof.

  Thus, the hydrophilic resin layer (B) which consists of resin selected can give a better deodorizing effect and the lasting hydrophilic property to an aluminum fin material by mix | blending a compound (A). . Actually, all of the resins constituting the hydrophilic resin layer (B) are water-soluble or hydrophilic resins, and by using these alone or as a mixture or as a copolymer thereof, a suitable hydrophilic property is obtained. Can be granted. A compound having a sulfone group is particularly preferred from the viewpoint of water solubility.

  The preferred film thickness of the hydrophilic resin layer (B) is 0.3 μm or more and 2.0 μm or less, more preferably 0.5 μm micron or more and 1.5 μm or less. When the film thickness is not more than the lower limit value, the hydrophilicity is lowered, and when it is not less than the upper limit value, the heat exchange efficiency is lowered.

  Next, in the present invention, when two or more resin layers are formed, between the aluminum plate and the hydrophilic resin layer (B), a polyolefin resin, a polyester resin, an epoxy resin, a urethane resin. Another feature is that a corrosion-resistant resin layer (C) made of a mixture of these is interposed.

  Originally, aluminum is a highly corrosion-resistant material, but the fin material for air conditioners is in a moist atmosphere due to the presence of condensed water, so it is exposed to an environment where corrosion is likely to occur. When the coating is made only with the hydrophilic resin layer without providing any corrosion-resistant resin layer, the aluminum material under the hydrophilic resin layer tends to corrode, and the odor due to this tends to increase over time. I found out that

  Therefore, it is practical to reinforce the corrosion resistance function by forming an appropriate corrosion resistance resin layer (C) between the hydrophilic resin layer (B) and the aluminum material. By forming a corrosion-resistant resin layer and imparting a corrosion resistance function, the corrosion resistance of the aluminum material can be reliably maintained, and at the same time, the generation of odor can be significantly reduced even after the air conditioner has been used for a long time.

  In addition, the preferable film thickness of a corrosion-resistant resin layer (C) is 0.3 micrometer or more and 2.0 micrometers or less, More preferably, they are 0.5 micrometer or more and 1.5 micrometers or less. When the film thickness is less than or equal to this lower limit value, the corrosion resistance is lowered, and when it is greater than or equal to the upper limit value, the heat exchange efficiency is lowered.

  In practicing the present invention, the method for forming each resin layer is not limited. For example, a coating material in which components for forming the resin layer are dissolved or dispersed in a solvent is prepared, applied to an aluminum plate, and then heated. A known method may be used. Further, in the practice of the present invention, the coating method is not limited, but from the viewpoint of productivity, the coiled aluminum plate is continuously degreased, painted, heated and wound by applying a roll coater or the like. It is good to go and manufacture.

  In addition, the paint for forming the resin layer may be used in combination with various paint additives for the purpose of improving the paintability and workability within the range not impeding the performance of the present invention. Surfactants, surface conditioners, crosslinking agents, defoaming agents, leveling agents, rheology control agents, antibacterial agents, other antifungal agents and the like may be optionally applied.

  Further, the aluminum material may be subjected to a chemical conversion treatment such as a phosphoric acid chromate treatment or a coating type zirconium treatment before the resin layer is provided in order to further improve the corrosion resistance.

(Example)
One type of pure aluminum-based A1200 (JIS H4000) aluminum plate was produced by a conventionally known production method. First, an ingot of pure aluminum is prepared, and the ingot is subjected to a homogenization heat treatment, followed by hot rolling, followed by an annealing treatment, followed by a cold rolling treatment to obtain an aluminum having a thickness of 0.10 mm. A board was produced.

  The aluminum plate was degreased using an alkaline agent (Surf Cleaner 360 manufactured by Nippon Paint Co., Ltd.), and then subjected to phosphoric acid chromate treatment (or coating type zirconium treatment). The target value of the adhesion amount in this phosphoric acid chromate treatment / coating-type zirconium treatment was 30 mg / m 2 in terms of Cr or Zr.

  Using this aluminum plate as a test material, 27 types of separately prepared paints were used, and 31 types of aluminum fin materials having a two-layer or one-layer structure for forming a corrosion-resistant resin layer and a hydrophilic resin layer thereon. Got.

  The corrosion-resistant resin layer is prepared by preparing a water-based paint in the configuration described in Tables 20 to 24 in Table 1, and applying this to each aluminum plate surface-treated as described above with the adhesion amount and heating conditions described in Table 2. It was formed by heating.

  Next, the hydrophilic resin layer is prepared by preparing a water-based paint in the configuration described in Tables 1 to 19 and 25 to 27 on the corrosion-resistant resin layer previously formed on the aluminum plate. It was formed by coating and heating with the adhesion amount and heating conditions described in Table 2.

  In addition, the coating of each coating material in these two stages used a bar coater, heating was performed using a hot air drying furnace, and the heating temperature was confirmed with a heat seal tape.

  The following various performance evaluations were carried out on each prototype aluminum fin material.

[Hydrophilicity evaluation]
The aluminum fin material was immersed in tap water with a flow rate of 1 liter / min for 8 hours and then dried at 80 ° C. for 16 hours, and 5 cycles were performed as one cycle. Thereafter, about 0.5 microliter of water droplets were dropped on the surface of the aluminum fin material, and the contact angle was measured using a contact angle measuring device (Kyowa Interface Science Co., Ltd., CA-05 type).

  And the hydrophilicity evaluation of the aluminum fin material based on the measured values of these contact angles was based on the following criteria.

◎ (Particularly good): Contact angle of less than 20 ° ○ (Good): Contact angle of 20 ° or more and less than 40 ° △ (Generally good): Contact angle of 40 ° or more and less than 60 ° × (Bad): Contact angle Is over 60 °
[Contamination resistance evaluation]
Each prototype aluminum fin material was immersed in tap water with a flow rate of 1 liter / min for 16 hours, and then enclosed in a glass desiccator with a capacity of 5 liters together with 0.5 g each of palmitic acid, stearic acid, and dioctyl phthalate. The process of heating at 0 ° C. for 8 hours was carried out for 3 cycles. Thereafter, about 0.5 microliter of water droplets were dropped on the surface of the aluminum fin material, and the contact angle was measured with the same contact angle measuring device as described above.

  And pollution resistance evaluation was performed according to the following evaluation criteria.

◎ (Particularly good): Contact angle is less than 30 ° ○ (Good): Contact angle is 30 ° or more and less than 50 ° △ (Generally good): Contact angle is 50 ° or more and less than 70 ° × (Bad): Contact angle Is 70 ° or more
[Evaluation of corrosion resistance]
Corrosion resistance evaluation was carried out on each of the trial aluminum fin materials, namely, a salt spray test (JIS Z2371) and a wet exposure test (40 ° C., relative humidity 98% atmosphere).

  After performing these tests, the appearance of each test piece was visually observed, the ratio of the area of the corroded portion to the total surface area of the aluminum fin material was counted, and the degree of corrosion of the aluminum fin material was evaluated according to the following criteria. .

○ (Good): Corrosion area ratio of 0% to less than 10% △ (Generally good): Corrosion area ratio of 10% to less than 50% × (Poor): Corrosion area ratio of 50% or more
[Odor evaluation]
Odor evaluation was performed by sensory tests for each of the aluminum fin materials made in trial, divided into three stages immediately after coating, after hydrophilicity evaluation and after corrosion resistance evaluation. This sensory evaluation was performed by a method in which the researcher himself exhaled the test material, brought his nose closer to 2 to 3 cm, and sniffed the odor, and was ranked according to the following evaluation criteria.

○ Even if the odor cannot be detected or can be detected slightly, the judgment of the type can be made.
Not possible △ Odor can be felt × Obvious odor can be detected or bad odor can be felt Table 3 lists these evaluation results for 5 items of hydrophilicity, stain resistance, corrosion resistance, initial odor and odor over time. . The evaluation results are considered as follows.

Experiment numbers 1 to 23 and 28
In any case, a hydrophilic resin layer containing a compound (A) such as a carbazide compound, which is also an essential feature of the present invention, is formed on a corrosion-resistant resin layer made of an epoxy resin or the like, which is a feature of the present invention. It is a layered aluminum fin material.

  In these examples, as shown in Table 3, none of the evaluation items has a characteristic defect corresponding to the “x” mark, and the majority of evaluation items are “◯” or more. That is, it is clear that these are aluminum fin materials that are excellent in hydrophilicity, stain resistance, and corrosion resistance, and that retain hydrophilicity and corrosion resistance over a long period of time, and thus have less odor generation.

  Among them, in Experiment No. 10, since the amount of compound (A) · dibutylhydroxytoluene added is small, hydrophilicity and contamination resistance are slightly lowered. On the contrary, in Experiment No. 14, since the amount of the compound added is large, only an initial odor is generated. In Experiment No. 19, on the contrary, the amount of dibutylhydroxytoluene added is close to the upper limit, so that the corrosion resistance is slightly insufficient.

・ Experiment number 24
This example is an aluminum fin material having a single-layer structure in which only the hydrophilic resin layer containing the compound (A) is formed. However, since the corrosion-resistant resin layer is lacking, the corrosion resistance and the odor over time are compared with the above-mentioned example group. Although slightly inferior, the hydrophilicity and stain resistance are very good regardless of the single layer structure. Therefore, the aluminum fin material of the present invention is also characterized by a single layer structure of a hydrophilic resin layer containing such a compound (A).
・ Experiment number 25-27
These examples are aluminum fin materials having a resin structure of two layers of corrosion resistance and hydrophilicity. Unlike the examples of the experiment numbers 1 to 23 and 28, the corrosion resistance resin layer is a compound (A). It is the example comprised only with the corrosion-resistant resin which is not mix | blended. Nevertheless, as can be seen from Table 3, all of these three types satisfy all the characteristics of the aluminum fin material.

In contrast to the above examples of the present invention, in the comparative examples of the experimental conditions 29 to 31 in which the configuration of the resin layer does not satisfy the conditions characteristic of the present invention, some of the evaluation items are judged as “x”. It turns out that it is unsuitable as an aluminum fin material for heat exchangers.
Experiment numbers 29-31 (comparative examples)
These are aluminum fin materials each having a corrosion-resistant / hydrophilic two-layer resin structure, and the corrosion-resistant resin layer is an epoxy resin emulsion common to the present invention. ) Is not blended. In Experiment No. 29, the hydrophilic resin layer on the surface does not contain the compound (A), the corrosion resistance is slightly insufficient, and the odor is not eliminated.

  Experiment numbers 30 and 31 are those in which the hydrophilic resin layer on the surface is blended with butylhydroxyanisole or t-butylhydroquinone different from the compound (A) of the present invention, and the odor is not eliminated.

  From the above, the aluminum fin material of the present invention has a hydrophilic resin layer blended with a specific compound (A) in either a single layer or multiple layers, and on the other hand, a corrosion-resistant resin layer is superimposed. In some cases, it is obvious that hydrophilicity, contamination resistance, and odor suppression can be reliably maintained over a long period of time by using a specific corrosion-resistant resin.

Claims (4)

1 The surface of the aluminum plate or aluminum alloy plate is selected from dibutylhydroxytoluene, carbazide compound, L-ascorbic acid, sodium L-ascorbate, L-ascorbic acid stearate, erythorbic acid, sodium erythorbate, sodium sulfite 1 A resin coating characterized by being coated with a resin layer based on a resin containing 0.1 to 20% by weight of a seed or two or more compounds (hereinafter referred to as "compound (A)") Aluminum fin material.   1 of polyacrylic acid, polyacrylic acid salt, polyvinyl alcohol, polyacrylamide, polyethylene glycol, carboxymethylcellulose, polyvinylpyrrolidone containing one or more of a carboxyl group, a hydroxyl group, a sulfone group, an amide group, and an ether bond. 2. A resin-coated aluminum product according to claim 1, which is a hydrophilic resin layer (hereinafter referred to as “hydrophilic resin layer (B)”) based on a seed or a copolymer or a mixture thereof. Fin material.   Between the aluminum plate or aluminum alloy plate and the hydrophilic resin layer (B), a corrosion-resistant resin layer (hereinafter referred to as “corrosion resistance”) based on a resin comprising an epoxy resin, a polyester resin, a urethane resin or a mixture thereof. The resin-coated aluminum fin material according to claim 1, wherein a resin layer (C) ”is interposed.   One or more compounds selected from dibutylhydroxytoluene, carbazide compounds, L-ascorbic acid, sodium L-ascorbate, L-ascorbic acid stearate, erythorbic acid, sodium erythorbate, sodium sulfite (A) The resin-coated aluminum fin material according to claim 3, wherein the resin-coated aluminum fin material contains a corrosion-resistant resin layer (C).