WO2021215504A1 - Hydrophilic coating composition, aluminum member, aluminum plate material, aluminum tube and heat exchanger - Google Patents

Abstract

This hydrophilic coating composition contains: one or more substances that are selected from among phosphoric acid-based glass, boric acid-based glass, vanadium-based glass and bismuth-based glass, said substances serving as a glass component; one or more substances that are selected from among an alumina sol, a basic aluminum chloride, an aluminum alkoxide, boric acid, metaboric acid, tetraboric acid, a borate salt, a metaborate salt, a tetraborate salt, a water-soluble zirconium compound, a water-soluble titanium compound, PVA, PEG, CMC, HEC, HPMC, MC, a polyacrylic acid, a polyacrylate salt, a polymethacrylic acid, a polymethacrylate salt and a water-soluble acrylic resin, said substances serving as an inorganic or organic binder component; and water that serves as a solvent.

Description

Hydrophilic paint compositions, aluminum components, aluminum plates, aluminum tubes, and heat exchangers

The present invention relates to hydrophilic coating compositions, aluminum members, aluminum plates, aluminum tubes, and heat exchangers.
The present application claims priority based on Japanese Patent Application No. 2020-07162 filed in Japan on April 22, 2020, the contents of which are incorporated herein by reference.

Aggregated water adheres to the fins of heat exchangers used in commercial and household air conditioners, in-vehicle air conditioners, etc. as water droplets when the air conditioner operates. In heat exchangers, a technique for forming a film made of a hydrophilic resin has been applied for a long time in order to prevent the coagulated water from becoming a ventilation resistance.

For example, Patent Document 1 below discloses a precoated fin having a coating film on the surface of an aluminum alloy plate containing 1 to 5% by mass of Si, and the amount of Si in the coating film is 1 to 300 mg / m ^2. Has been done. This coating film contains at least one of a silicate such as lithium silicate and amorphous silica, and further contains a fluoride flux.

JP-A-2018-0446994

Conventionally, in heat exchangers made of copper and aluminum, precoated fins in which the fins are pre-painted with an organic paint are generally used in order to improve the hydrophilicity of the surface of the aluminum alloy fin material.
On the other hand, in a heat exchanger made of only aluminum, it is necessary to perform a brazing heat treatment of heating to about 600 ° C. for joining members. However, when a hydrophilic film made of an organic paint is used, there is a problem that the hydrophilic film is deteriorated or decomposed in the brazing heat treatment, and sufficient hydrophilicity cannot be maintained after brazing.

In addition, by applying an inorganic paint containing water glass to the surface of the aluminum fin in advance instead of the organic paint to form a film, it is possible to maintain the hydrophilicity of the fin surface even after brazing heat treatment. Become. However, the above-mentioned film has a problem that a substance or the like that causes an odor is adsorbed, so that an odor is generated due to desorption of the odorous substance during use of the air conditioner.

According to the present invention, an aluminum member, an aluminum plate material, and an aluminum tube provided with a hydrophilic coating composition capable of forming a hydrophilic film applicable to a heat exchanger having a brazed structure and a coating film of the hydrophilic coating composition. , And the purpose is to provide a technology capable of improving the drainage property of dew condensation water adhering to the heat exchanger.

(1) The hydrophilic coating composition of the present invention contains one or more of phosphoric acid-based glass, boric acid-based glass, vanadium-based glass, and bismuth-based glass as glass components, and is inorganic or organic. As binder components, alumina sol, basic aluminum chloride, aluminum alkoxide, boric acid, metaboric acid, tetraboric acid, borate, metaborate, tetraborate, water-soluble zirconium compound, water-soluble titanium compound, PVA (polyvinyl). Alcohol), PEG (polyethylene glycol), CMC (carboxymethyl cellulose), HEC (hydroxyethyl cellulose), HPMC (hydroxypropyl methyl cellulose), MC (methyl cellulose), polyacrylic acid, polyacrylic acid salt, polymethacrylic acid, and polymethacrylic acid. It contains one or more of the salt and the water-soluble acrylic resin, and is characterized by containing water as a solvent.
(2) In the hydrophilic coating composition according to (1), it is preferable that the softening point is 620 ° C. or lower as the thermophysical characteristics of the glass component.
(3) The hydrophilic coating composition according to (1) or (2) may contain a surfactant and a rheology adjuster.
(4) In the hydrophilic coating composition according to any one of (1) to (3), alkali metals, boron, aluminum, silicon, zinc, titanium, and as a flux agent for improving brazing property, and It may contain a fluorine compound containing any one or more of zirconium.

(5) In the hydrophilic coating composition according to any one of (1) to (4), the borate, the metaborate, and the tetraborate are lithium borate, sodium borate, and the like. Potassium borate, calcium borate, barium borate, ammonium borate, lithium metaborate, sodium metaborate, potassium metaborate, calcium metaborate, barium metaborate, ammonium metaborate, lithium tetraborate, sodium tetraborate, Of potassium tetraborate, calcium tetraborate, barium tetraborate, and ammonium tetraborate, one or more are preferable.

(6) The aluminum member according to the present invention is described in any one of (1) to (5) on a base material made of aluminum or an aluminum alloy and a part or the entire surface of the base material. It is characterized by comprising a coating film coated with ^{a coating film amount of 0.1 to 3 g / m 2} after drying in which the solvent of the hydrophilic coating composition of No. 1 is volatilized.
(7) In the aluminum member according to (6), it is preferable that the coating film is coated with a water-soluble lubricant layer having a coating ^{film amount of 0.05 to 1 g / m 2.}

(8) In the aluminum plate material according to the present invention, the aluminum member according to any one of (6) or (7) has a plate-like shape, and the coating film is applied to either one side or both sides thereof. It is characterized by being provided.
(9) The aluminum tube according to the present invention has a tube shape in which the aluminum member according to any one of (6) or (7) has one or more holes, and a part of the outer surface thereof or It is characterized in that the coating film is provided on the entire surface.
(10) The heat exchanger according to the present invention is made of a tube made of aluminum or an aluminum alloy having a single or a plurality of holes, or a tube made of an aluminum or an aluminum alloy having a single or a plurality of holes, and an aluminum or an aluminum alloy. In a heat exchanger composed of fins, the amount of the coating film after drying in which the solvent of the hydrophilic coating composition according to any one of (1) to (5) is volatilized is 0.1 to 3 g / m ² . It is characterized in that a coated coating film or a film after the coating film is brazed is provided on a part or the entire surface.
(11) The heat exchanger according to the present invention includes fins having a corrugated shape made of aluminum or an aluminum alloy, and a tube made of aluminum or an aluminum alloy having a single or a plurality of holes, and the tube made of the aluminum or the aluminum alloy. (1) to (5) in a heat exchanger in which a plurality of aluminum or aluminum alloy tubes are arranged in parallel and fins having a corrugated shape are brazed between the tubes made of aluminum or an aluminum alloy. ^{A coating film coated with a coating film amount of 0.1 to 3 g / m 2} after drying in which the solvent of the hydrophilic coating composition according to item 1 is volatilized, or a coating film after the coating film is brazed. It is characterized in that it is provided on a part or the entire surface.
(12) The heat exchanger according to the present invention is the heat exchanger according to (10) or (11), and is the aluminum member according to (6) and (7), and the aluminum plate material according to (8). It is characterized in that at least one selected from the fins formed from, and the aluminum tube according to (9) is used.

Since the hydrophilic coating composition according to the present invention contains any of the above-mentioned glass components, hydrophilicity can be imparted to the film after brazing, and odor resistance can be imparted. Further, since it contains an inorganic or organic binder component, the coating film of the hydrophilic coating composition can be fixed to the substrate after drying, and peeling of the coating film from the substrate can be prevented.
Further, since the hydrophilic coating composition according to the present invention contains a rheology adjusting agent, coating stability can be ensured for an aluminum member even when various coating films are used, and a desired coating film thickness can be ensured. Can be provided with a hydrophilic coating composition capable of obtaining the above.
Further, in the hydrophilic coating composition according to the present invention, since the solvent is water, the problem of air pollution does not occur even if the solvent volatilizes in the drying step.

As a result, excellent hydrophilicity can be exhibited even after brazing heat treatment, drainage can be ensured even after brazing heating by applying in advance before brazing heat treatment, and excellent surface drainage is provided, resulting in a brown color. Aluminum members, aluminum plates, aluminum tubes, and heat exchangers with a hydrophilic coating that is not colored can be provided.

It is a front view which made the example of the heat exchanger according to the invention a partial cross section. FIG. 5 is a partially enlarged cross-sectional view showing a state in which a header pipe, a tube and fins are brazed in the heat exchanger according to the present invention. FIG. 5 is a partially enlarged cross-sectional view showing a state in which a header pipe, a tube and fins are assembled before brazing in the heat exchanger according to the present invention, and a coating film for brazing is applied to the surface of the tube.

Hereinafter, an example of the embodiment of the present invention will be described in detail based on the attached drawings. In addition, in the drawing used in the following description, in order to make the feature easy to understand, the feature portion may be enlarged and shown for convenience.

"First embodiment"
FIG. 1 is a perspective view showing an example of a heat exchanger configured by using fins formed from a plate material provided with a coating film coated with the hydrophilic coating composition according to the present embodiment.
The heat exchanger 30 of this example is used as a heat exchanger for indoor / outdoor units of a room air conditioner, an outdoor unit for HVAC (Heating Ventilating Air Conditioning), a heat exchanger for automobiles, and the like. It is an aluminum heat exchanger.
The heat exchanger 30 shown in FIG. 1 has header pipes 31 and 32 arranged upright in parallel to the left and right at a distance from each other, and is parallel to each other with a distance between the header pipes 31 and 32. It is mainly composed of a plurality of tubes 33 joined at right angles to the header pipes 31 and 32, and corrugated fins 34 attached to each tube 33. The header pipes 31, 32, tubes 33 and fins 34 are all made of aluminum alloy.

More specifically, a plurality of slits 36 are formed on the facing side surfaces of the header pipes 31 and 32 at regular intervals in the length direction of each pipe, and the tube 33 is formed in the facing slits 36 of the header pipes 31 and 32. A plurality of tubes 33 are erected between the header pipes 31 and 32 through the end portions. Further, corrugated fins 34 are arranged between a plurality of tubes 33, 33 erected between the header pipes 31 and 32 at predetermined intervals, and these fins 34 are located on the upper surface 33A side of the tube 33, for example, as shown in FIG. Alternatively, it is brazed to the lower surface 33B side.

As shown in FIG. 2, in the portion where the end portion of the tube 33 is inserted into the slit 36 of the header pipe 31, the first fillet 38 is formed by the brazing material so as to fill the gap of the insertion portion, and the header pipes 31 and 32. The tube 33 is brazed to the tube 33. Further, in the corrugated fin 34, a second fillet 39 is formed by a brazing material formed in a portion between the upper surface 33A or the lower surface 33B of the tube 33 adjacent to the apex portion of the wave so as to face the upper surface 33A or the lower surface 33B, and the tube 33 is formed. Corrugated fins 34 are brazed to the upper surface 33A side and the lower surface 33B side, respectively.
The tube 33 is a flat multi-hole tube made of an aluminum alloy, and a plurality of refrigerant passages 33C are formed inside the tube 33.

As shown in FIG. 3, the heat exchanger 30 of the present embodiment forms a heat exchanger assembly 41 by assembling header pipes 31 and 32, a plurality of tubes 33 erected between them, and a plurality of fins 34. It is manufactured by heating and brazing this. The Zn melt diffusion layer 42 shown in FIG. 2 is formed on the upper surface 33A side and the lower surface 33B side of the tube 33 by heating during brazing.

The aluminum alloy constituting the header pipes 31 and 32 is made of an aluminum alloy applied to a general heat exchanger header pipe, and for example, an aluminum alloy based on an Al—Mn system is applied.
For example, it is preferable to contain Mn: 0.05 to 1.50% in mass%, and Cu: 0.05 to 0.8% and Zr: 0.05 to 0.15% as other elements. Can be contained. In the following description, when a range such as a component or a coating film amount is indicated by using "-", it means a range including an upper limit and a lower limit unless otherwise specified. Therefore, for example, 0.05 to 1.50% means 0.05% or more and 1.50% or less, and 1 to 5 g / m ² means 1 g / m ² or more and 5 g / m ² or less. In the present embodiment, the header pipes 31 and 32 having a brazing material layer formed on the outer surface of the pipe-shaped core material made of the above-mentioned aluminum alloy are applied. In FIGS. 2 and 3, the core material is indicated by reference numeral 31A, and the brazing material layer is indicated by reference numeral 43.

The tube 33 is a flat tube having a large width ratio to its thickness, and a plurality of (several to several tens) refrigerant passages 33C are adjacent to each other in the width direction of the tube 33 in a state of being partitioned by a partition wall. It is formed.
The aluminum alloy constituting the tube 33 is not particularly limited as long as it is a flat multi-hole tube for a heat exchanger and an aluminum alloy applied to the tube. As an example, an aluminum alloy containing Si: 0.05 to 1.0%, Mn: 0.1 to 1.5%, and Cu: less than 0.1% by mass, and the balance is unavoidable impurities and aluminum. And so on. The tube 33 is manufactured by extruding an aluminum alloy. The number of refrigerant passages 33C formed in the tube 33 may be any number as long as it is one or more, but a structure in which a plurality of refrigerant passages 33C are formed is preferable in terms of improving heat exchange efficiency.

As the aluminum alloy constituting the fin 34, a general aluminum alloy used for fins for heat exchangers can be widely applied. For example, in mass%, Zn: 0.3 to 5.0%, It contains Mn: 0.5 to 2.0%, Fe: 1.0% or less, and Si: 1.5% or less, and is composed of an aluminum alloy composed of unavoidable impurities and aluminum.
The fin 34 is formed by melting an aluminum alloy having the above composition by a conventional method, and passing through a hot rolling step, a cold rolling step, and the like to form a desired fin shape, for example, a corrugated shape. The manufacturing method of the fin 34 is not particularly limited, and a known manufacturing method can be appropriately adopted.

In this embodiment, as shown in FIG. 3, on the upper surface and the lower surface of the tube 33 before brazing, for example, Si powder: 1 to 5 g / m ² , Zn-containing flux (KZnF ₃ powder, etc.): 3.0. A brazing coating film 37 containing up to 20 g / m ² and resin: 0.2 to 8.3 g / m ² and to which a solvent is added is formed.

The fin 34 (aluminum plate material) has a plate-shaped base material 34a made of aluminum or an aluminum alloy, and a hydrophilic film 35a attached to the front and back surfaces (front and back surfaces) of the base material 34a. That is, a hydrophilic film 35a after heat treatment is provided on both the front and back surfaces of the base material 34a.

<Hydrophilic coating>
In the heat exchanger assembly 41 before the brazing heat treatment shown in FIG. 3, the hydrophilic coating film 35 according to the present embodiment is formed on the front and back surfaces (both front and back surfaces) of the fins 34 (note that the hydrophilic coating film is It may be abbreviated as a coating film).
The heat exchanger assembly 41 corresponds to the heat exchanger before brazing, and the left and right header pipes 31 and 32, the tubes 33, and the fins 34 are assembled so as to have an approximate shape shown in FIG. The heat exchanger 30 shown in FIG. 1 can be obtained by heating the heat exchanger assembly 41 to a brazing heat treatment temperature as described later. The hydrophilic coating film 35 may be formed on only one of the front surface and the back surface of the fin 34.

The hydrophilic coating film 35 formed on the fins 34 of the heat exchanger assembly 41 is coated with the hydrophilic coating composition described below and dried at 200 to 260 ° C., for example, 250 ° C. for 0.2 to 5 minutes. This is a coating film obtained so that the solvent is volatilized and the coating film amount is 0.1 to 3 g / m ² .
When the amount of the coating film after drying of the hydrophilic coating composition is ^{less than 0.1 g / m 2} , sufficient hydrophilicity cannot be obtained in the film after brazing. Further, if the amount of the coating film after drying ^{exceeds 3 g / m 2} , the brazing property is deteriorated, and there is a possibility that bonding failure may occur at the time of brazing.
The hydrophilic coating composition of the present embodiment is characterized by being a hydrophilic coating composition containing a glass component, an inorganic or organic binder component, and a rheology modifier, and these are mixed with water as a solvent.

"Glass component"
The hydrophilic coating composition (1) contains one or more of phosphoric acid-based glass, boric acid-based glass, vanadium-based glass, and bismuth-based glass as the glass component.
The glass component is preferably contained in the hydrophilic coating composition as a solid content in an amount of 0.1 to 20% by mass, more preferably 0.5 to 15% by mass.
The softening point of phosphoric acid glass is 300 to 550 ° C, the softening point of boric acid glass is 400 to 550 ° C, the softening point of vanadium glass is 350 to 550 ° C, and the softening point of bismuth glass is 400 to 550 ° C. In each case, the softening point is 620 ° C. or lower, preferably 550 ° C. or lower.
For a hydrophilic coating film containing glass having a softening point of 620 ° C. or lower, preferably 550 ° C. or lower, the viscosity of the hydrophilic coating film becomes sufficiently low during brazing heating. Therefore, the hydrophilic film after brazing has the effect of imparting hydrophilicity to the coating film and preventing odor as a result of covering the surface of the aluminum fin with the glass component. The softening point of the glass is preferably in the range of 300 to 550 ° C, more preferably in the range of 300 to 520 ° C.
In the hydrophilic coating composition, if the content of the glass component is less than 0.1% by mass, the hydrophilicity and odor resistance are insufficient, and if the content exceeds 20% by mass, the brazing property is lowered.

"Inorganic binder component or organic binder component"
The hydrophilic coating composition of the present embodiment has (2) alumina sol, basic aluminum chloride, aluminum alkoxide, boric acid, metaboric acid, tetraboric acid, borate, metaborate as an inorganic binder component or an organic binder component. , Tetraborate, water-soluble zirconium compound, water-soluble titanium compound, PVA (polypoly alcohol), PEG (polyethylene glycol), CMC (carboxymethyl cellulose), HEC (hydroxyethyl cellulose), HPMC (hydroxypropyl methyl cellulose), MC (methyl cellulose) ), Polyacrylic acid, polyacrylic acid salt, polymethacrylic acid, polymethacrylate, and water-soluble acrylic resin, including one or more.
The borate is preferably one or more of lithium borate, sodium borate, potassium borate, calcium borate, barium borate, and ammonium borate. The metaborate is preferably one or more of lithium metaborate, sodium metaborate, potassium metaborate, calcium metaborate, barium metaborate, and ammonium metaborate. The tetraborate may be one or more of lithium tetraborate, sodium tetraborate, potassium tetraborate, calcium tetraborate, barium tetraborate, and ammonium tetraborate. preferable.

In the hydrophilic coating composition, the inorganic binder component or the organic binder component is preferably contained in the hydrophilic coating composition as a solid content in an amount of 0.5 to 5% by mass, preferably 0.5 to 4.5% by mass. % Is more preferable.
If the content of the inorganic binder component or the organic binder component is less than 0.5% by mass, the adhesion of the coating film of the hydrophilic coating composition to the surface of the plate-shaped aluminum base material is lowered. If the content of the inorganic binder component or the organic binder component exceeds 5% by mass, there is a problem that the brazing property is lowered.

"Rheology adjuster"
In the hydrophilic coating composition, the rheology adjusting agent is contained in the hydrophilic coating composition in an amount of 0.02 to 3% by mass, more preferably 0.1 to 2% by mass.
Specific examples of the rheology modifier include synthetic or natural swellable layered mineral particles (hectrite, vermiculite, halosite, swellable mica, etc.), ultrafine oxide particles (alumina, titania, zirconia, etc.), PVA, PVP. , Polyacrylic acid or polyacrylic acid salt, polymethacrylic acid or polymethacrylate, water-soluble cellulose derivative, and cellulose nanofiber, one or more of them can be selected and used.
If the content of the rheology adjuster is less than 0.02% by mass, the effect of preventing the precipitation of the glass component and the coloring component cannot be obtained, and the hydrophilic coating composition will settle during storage, causing uneven coating and coating. If it exceeds 3% by mass, the properties of the hydrophilic coating film itself will change, and sufficient hydrophilicity will not be obtained, and the viscosity of the paint will increase, making coating difficult. There is.

"Surfactant"
In the hydrophilic coating composition, the surfactant is contained in the hydrophilic coating composition in an amount of 0.01 to 1% by mass, more preferably 0.1 to 1% by mass.
Specifically, as a surfactant, one or more selected from a carboxylate, a sulfonate, a sulfate ester salt, and a phosphoric acid ester salt can be applied as an anionic surfactant. LAS known as an alkylbenzene sulfonate, MES known as an α-sulfo fatty acid methyl ester salt, AOS known as an α-olefin sulfonate, and the like may be used. As the sulfate ester salt, AS of an alkyl sulfate ester salt, AES known as a polyoxyethylene alkyl sulfate ester salt, or the like may be used.

In addition, a benzalkonium salt, a quaternary ammonium salt, or an imidazoline compound can be used as the cationic surfactant.
In addition, as the nonionic surfactant, glycerin fatty acid ester, sorbitan fatty acid ester, sucrose fatty acid ester, polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene polyoxypropylene glycol and the like may be used. Further, as the amphoteric surfactant, alkyl betaine, fatty acid amide propyl betaine, alkylamine oxide or the like may be used.
Of the above-mentioned surfactants, one type or two or more types can be selected and used. If the content of the surfactant is less than 0.01% by mass, sufficient wettability cannot be obtained depending on the surface condition of the base material, the coatability deteriorates, and coating defects such as paint repelling occur during coating. There is a problem that if it exceeds 1% by mass, the adhesion of the coating film is lowered.

"Flux agent"
In the hydrophilic coating composition, the flux agent is any one of an alkali metal, an alkaline earth metal, boron, aluminum, silicon, zinc, titanium, zirconium, and a fluorine compound containing two or more of cesium. Includes species or two or more.
The fluorine compounds are K _1-3 AlF _4-6 , Cs _1-3 AlF _4-6 , Cs _0.02 K _1-2 AlF _4-5 , AlF ₃ , KF, KZnF ₃ , K ₂ SiF ₆ , Li. ₃ AlF ₆ , NaF, NaSiF ₆ , KSiF ₆ , MgF ₂ , CaF ₂ , CsF, NaBF ₄ , KBF ₄ , K ₂ TiF ₆ , K ₂ ZrF ₆ may be one or more. preferable.
If the content of the flux agent is less than 0.1% by mass, the brazing property may be lowered, and if it exceeds 1% by mass, the properties such as coating film adhesion, corrosion resistance and odor resistance may be lowered. Therefore, the content of the flux agent is preferably 0.1 to 1% by mass.

<Water-soluble lubricant layer>
As a material capable of forming a water-soluble lubricant layer formed on the coating film of the hydrophilic coating composition, acrylic resin, epoxy resin, polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene alkyl fatty acid amide , Polyoxyethylene alkyl stearic acid ester, polyoxyethylene alkyl fatty acid ester, polyoxyethylene-12-hydroxystearic acid ester, polyoxyethylene trimethylpropanalkyl fatty acid mono or diester, polyoxyethylene pentaerythritol alkyl fatty acid mono or diester, And nonionic polymer in which ethylene oxide is added to a compound selected from the group of polyoxyethylene polyoxyalkyl ether.

It is desirable that a water-soluble lubricant layer is formed on the surface of the hydrophilic coating film 35. The amount of the coating film of this water-soluble lubricant layer is preferably ^{0.05 to 1 g / m 2.}
When the coating film amount of the water-soluble lubricant layer is ^{less than 0.05 g / m 2} , when the plate material is processed into corrugated fins, the fins are liable to be partially cracked due to friction with the mold. Further, when the ^{coating film amount exceeds 1 g / m 2} , there are problems that cutting and feeding defects are likely to occur during fin processing and brazing property is lowered.

In the heat exchanger assembly 41 shown in FIG. 3, a brazing coating film 37 is formed on the upper surface 33A and the lower surface 33B of the tube 33, and the heat exchanger assembly 41 is heated to a temperature of about 580 to 620 ° C. for several minutes. The brazing coating film 37 can be melted by heating for about several tens of minutes.
After the heat treatment, when cooled, the tubes 33 and fins 34 are brazed by the fillets 38 and 39 as shown in FIG. 2, and the tube 33 is brazed to the header pipes 31 and 32 by the fillets 30 to obtain a heat exchanger 30. can.
The hydrophilic coating film 35 formed on the fins 34 before brazing becomes a hydrophilic film 35a after the brazing heat treatment, and remains on the front surface and the back surface of the fins 34.

When the brazing coating film 37 contains a Zn-containing flux, Zn diffuses to the upper surface 33A and the lower surface 33B of the tube 33 to form a Zn diffusion layer 42 during the brazing heat treatment, and the Zn diffusion layer 42 is corrosion-proof. It is effective.
The brazing coating film 37 may be composed of other generally known brazing paints or a general brazing material layer applied to a clad material such as a brazing sheet.
Further, it can be used even in a configuration in which a brazing material layer is formed on the fin 34 side and the brazing paint 37 is not formed on the tube 33. At this time, a Zn sprayed layer or a flux layer may be formed on the front and back surfaces of the tube 33.

Since the hydrophilic coating film 35 of the present embodiment has the above-mentioned composition before brazing, after the brazing heat treatment, the rheology adjusting agent composed of the organic binder component, the surfactant and the organic substance is removed, and then the remaining components. Aggregates to form a hydrophilic film 35a, thereby exhibiting hydrophilicity.

In particular, one or more of the phosphoric acid-based glass, boric acid-based glass, vanadium-based glass, and bismuth-based glass, which are included in the above range as glass components, are heated to the above-mentioned brazing heat treatment temperature. Even after that, it develops excellent hydrophilicity.
Further, by containing the above-mentioned substance, the adhesiveness of the aluminum alloy to the surface is ensured, the adhesiveness of the hydrophilic film is improved, and peeling is prevented.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.
<Preparation of sample>
A plate containing Si: 0.4 to 1.0% by mass, Mn: 1.0 to 2.0% by mass, Zn: 0.5 to 3.5% by mass, and having a composition of the balance Al and unavoidable impurities. A plurality of aluminum base materials were prepared, and these base materials were subjected to degreasing treatment.
After the degreasing treatment, the surface of each base material was coated with the hydrophilic coating composition described below by bar coater coating.

<Preparation of hydrophilic paint composition>
A hydrophilic coating composition containing boric acid-based glass, phosphoric acid-based glass, vanadium-based glass, and bismuth-based glass shown in Table 1 below was prepared as a glass component.
Table 1 shows the types of glass components, inorganic or organic binder components, rheology adjusters, surfactants, and flux agents used in the hydrophilic coating film, and Tables 2 to 17 below show the blending amounts of each component. do. Table 1 shows the types of materials for the water-soluble lubricant layer formed on the surface of the hydrophilic coating film.

"Glass component"
A1: Boric acid-based glass (softening point: 515 ° C)
A2: Phosphoric acid-based glass (softening point: 485 ° C)
A3: Vanadium-based glass (softening point: 500 ° C)
A4: Bismuth glass (softening point: 500 ° C)
A5: Amorphous silica (softening point: 1500 ° C)

"Inorganic binder or organic binder"
B1: Sodium tetraborate / decahydrate B2: Boric acid B3: Ammonium tetraborate / tetrahydrate B4: Polysodium methacrylate B5: PVA (polyvinyl alcohol)
B6: Sodium silicate

"Rheology agent"
C1: Synthetic hectorite C2: Alumina ultrafine particles

"Surfactant"
D1: Anionic surfactant (sulfonate)
D2: Cationic surfactant (ammonium salt)
D3: Nonionic surfactant (polyoxyethylene alkyl ether)
D4: Amphoteric surfactant (alkyl betaine)

"Flux agent"
E1: K _1-3 AlF _4-6
E2: KZnF ₃
E3: K ₂ SiF ₆

After applying these hydrophilic coating compositions to the surface of a plate-shaped base material of an aluminum alloy by bar coater coating, the solvent is volatilized and dried by heating this hydrophilic coating at 250 ° C. for 0.5 minutes. As shown in Tables 18 to 33 below, an aluminum plate material having a hydrophilic coating film in which the amount of coating film after drying was adjusted was obtained. Further, a water-soluble lubricating layer adjusted to the amount of the coating film shown in Tables 18 to 33 below was formed by bar coater coating.

Next, an aluminum alloy for tubes containing Si: 0.3 to 0.5% by mass and Mn: 0.2 to 0.4% by mass and composed of the balance Al and unavoidable impurities was melted and extruded from this alloy. An aluminum alloy tube for a heat exchanger having a flat cross-sectional shape (thickness 0.26 mm × width 17.0 mm × height 1.5 mm) was formed.
Further, a coating film of a brazing material layer was formed on the flat upper surface and the lower surface of these tubes. The coating film of the brazing filler metal is 3 g of Si powder (D (99) particle size 10 μm), 6 g of Zn-containing flux (KZnF ₃ powder: D (50) particle size 2.0 μm), 1 g of acrylic resin binder, and as a solvent. A solution consisting of 16 g of a mixture of 3-methoxy-3-methyl-1butanol and isopropyl alcohol was applied with a bar coater and dried (heated in an atmosphere of 150 ° C. for 5 minutes) to form a solution.

The aluminum plate material was corrugated by corrugating to obtain aluminum fins having a total length of 100 mm. A mini-core test piece having a 10-stage structure similar to the shape of the heat exchanger shown in FIG. 1 was assembled by combining 11 of the tubes with the 10 aluminum fins.
Brazing heat treatment was performed under the condition that these mini-core specimens were kept in a furnace in a nitrogen atmosphere at 600 ° C. for 3 minutes. By this brazing heat treatment, a sacrificial anode layer is formed on the upper surface and the lower surface of the tube on which the brazing coating film was formed, and a heat exchanger in which fins and tubes having a hydrophilic film are brazed and joined. A test piece was obtained.

The paintability evaluation, the adhesion after drying, the contact angle after washing with water, the brazing property evaluation, the corrosion resistance evaluation, the odor evaluation, and the press workability were measured or evaluated based on the following conditions.

<Evaluation test>
[Paintability evaluation]
After the above-mentioned hydrophilic coating composition was applied to the surface of a plate-shaped substrate and dried at 250 ° C., the coating property was evaluated visually in the coated state of the surface of the plate material. D is the one in which the paint is repelled and cannot be painted, and B is the one in which the paint repellent or streaky unevenness is slightly observed but there is no problem in terms of visual appearance. Those without a repellent were designated as A.

[Coating film adhesion test]
The above-mentioned hydrophilic coating composition is applied to the surface of a plate-shaped substrate, dried at 250 ° C., and then rubbed 10 times while pressing a felt contact terminal with a load of 500 g. The test was carried out. On the surface of the plate material after the test, significant friction marks are observed, and when the coating film is peeled off, D, friction marks, etc. are observed, and there are some places where the coating film is peeled off, but there are some characteristics in use. C was designated as having no problem, and B was designated as a state in which friction marks were observed but the coating film was not peeled off, or a state in which no change in appearance was observed and the coating film was not peeled off.

[Evaluation of hydrophilicity: Measurement of water contact angle after washing with water]
The above-mentioned hydrophilic coating composition was applied to the surface of a plate-shaped substrate and dried at 250 ° C., and the plate sample before the brazing heat treatment and the plate sample after the brazing addition heat treatment were immersed in running water for 24 hours and then contacted with water. The corners were measured respectively. In these measurement results, those with a water contact angle greater than 30 ° have a hydrophilicity of D, those with a contact angle of 30 ° or less to greater than 25 ° have a hydrophilicity of C, and those with a water contact angle of 25 ° or less to 20 °. The one larger than the above was designated as B for hydrophilicity, and the one having a water contact angle of 20 ° or less was designated as A for hydrophilicity.

[Brazing property evaluation]
After brazing heat at 600 ° C for 3 minutes, the fins were peeled off from the tube for each brazed-bonded fin of each heat exchanger test piece obtained, and the fin bonding marks remaining on the tube surface were observed and unbonded. The number of locations (where brazing was performed but no joint traces remained) was measured. For one sample, 100 joints were measured, and those with 69 or less normal joints (where traces of joints remained after brazing) were D, those with 70 to 79 were C, 80. Those with ~ 89 locations were designated as B, and those with 90 or more locations were designated as A.
[Corrosion resistance evaluation]
After brazing heat at 600 ° C for 3 minutes, each heat exchanger test piece obtained was subjected to the SWAAT test planned by ASTM G85-A3, and the number of days until a through hole was formed in the tube was evaluated. bottom. If it is 200 days or more, it is judged to pass.

[Odor]
After brazing heat at 600 ° C. for 3 minutes, the odor from each heat exchanger test piece obtained was subjected to a sensory test by 5 testers and evaluated according to the following criteria. The case where the average score was 1.5 points or less was regarded as the allowable range (pass).
1 point: does not smell, 2 points: faintly smells, 3 points: smells, 4 points: smells well

[Press workability]
The above-mentioned hydrophilic coating composition is applied to the surface of a plate-shaped substrate, dried at 250 ° C., and then the dynamic friction coefficient of the surface is subjected to a Bowden-type dynamic friction coefficient test on a coating film on which a water-soluble lubricant layer is further formed. Was measured. A sample with a dynamic friction coefficient of more than 0.3 is judged to be a sample with large damage to the mold during press working, and is designated as D. A sample with a dynamic friction coefficient of 0.3 or less to more than 0.2 is C, and a dynamic friction coefficient is 0. The sample of .2 or less was designated as B.

As shown in Tables 2 to 15, Examples 1 to 344 include a glass component and an inorganic binder or an organic binder, and, if necessary, a rheology adjuster, a surfactant, and a flux agent. Therefore, as shown in Tables 18 to 31, all the evaluation items were passed or A, B or C.

As shown in Tables 2 to 4, in Examples 10 to 14, 28 to 32, 46 to 50, and 64 to 68, any of the glass component and the inorganic / organic binder is out of the most desirable range. As shown in Tables 18 to 20, either the adhesion after drying or the brazing evaluation was B or C.

As shown in Tables 18 to 31, Examples 18-21, 33-36, 51-54, 69-72, 77-80, 85-88, 93-96, 101-104, 117-120, 133- 136, 141-144, 149-152, 157-160, 165-168, 173-176, 181-184, 189-192, 197-200, 205-208, 213-216, 229-232, 237-240, 253 to 256, 261 to 264, 269 to 272, 277 to 280, 285 to 288, 293 to 296, 301 to 304, 309 to 312, 316 to 319, 325 to 328, 333 to 336, 341 to 344 are hydrophilic. Since the amount of the coating film of the sex-based paint or the amount of the coating film of the water-soluble lubricating layer is out of the more desirable range, any one of the water contact angle after washing with water, the brazing property evaluation, and the press workability was C.

As shown in Tables 16 to 17, Comparative Examples 1 to 48 contain either or both of amorphous glass and sodium silicate as a glass component or an inorganic / organic binder component, and therefore Tables 32 to 33. As shown in, the odor evaluation failed.

30 ... heat exchanger, 31, 32 ... header pipe, 33 ... tube, 33A ... top surface, 33B ... bottom surface, 33C ... refrigerant passage, 34 ... fins, 35 ... brazing hydrophilic coating before heat treatment, 35a ... brazing Hydrophilic film after heat treatment, 37 ... sacrificial anode layer, 38 ... first fillet, 39 ... second fillet, 41 ... heat exchanger assembly.

Claims (12)

1. As a glass component, one or more of phosphoric acid-based glass, boric acid-based glass, vanadium-based glass, and bismuth-based glass are contained.
   As inorganic or organic binder components, alumina sol, basic aluminum chloride, aluminum alkoxide, boric acid, metaboric acid, tetraboric acid, borate, metaborate, tetraborate, water-soluble zirconium compound, water-soluble titanium compound, PVA (polyvinyl alcohol), PEG (polyethylene glycol), CMC (carboxymethyl cellulose), HEC (hydroxyethyl cellulose), HPMC (hydroxypropyl methyl cellulose), MC (methyl cellulose), polyacrylic acid, polyacrylic acid salt, polymethacrylic acid, poly Contains one or more of methacrylates and water-soluble acrylic resins.
   A hydrophilic coating composition comprising water as a solvent.
2. The hydrophilic coating composition according to claim 1, wherein the glass component has a softening point of 620 ° C. or lower as a thermal property.
3. The hydrophilic coating composition according to claim 1 or 2, which comprises a surfactant and a rheology adjuster.
4. Claims 1 to 1, wherein the flux agent for improving the brazing property contains a fluorine compound containing any one or more of alkali metals, boron, aluminum, silicon, zinc, titanium, and zirconium. The hydrophilic coating composition according to any one of claims 3.
5. The borate, the metaborate, and the tetraborate are lithium borate, sodium borate, potassium borate, calcium borate, barium borate, ammonium borate, lithium metaborate, sodium metaborate, metaboric acid. Calcium acid, barium metaborate, ammonium metaborate, lithium tetraborate, sodium tetraborate, potassium tetraborate, calcium tetraborate, barium tetraborate, ammonium tetraborate, one or more The hydrophilic coating composition according to any one of claims 1 to 4, wherein the hydrophilic coating composition is provided.
6. The solvent of the hydrophilic coating composition according to any one of claims 1 to 5 volatilized on a base material made of aluminum or an aluminum alloy and a part or the entire surface of the base material. An aluminum member comprising a coating film coated with a coating film amount of 0.1 to 3 g / m ^{2 after drying.}
7. The aluminum member according to claim 6, wherein a water-soluble lubricant layer having a coating film amount of 0.05 to 1 g / m ^{2 is coated on the coating film.}
8. An aluminum plate material according to claim 6 or 7, wherein the aluminum member has a plate-like shape, and the coating film is provided on either one side or both sides thereof.
9. The aluminum member according to any one of claims 6 or 7 has a tube shape having one or a plurality of holes, and the coating film is provided on a part or the entire surface of the outer surface thereof. An aluminum tube featuring.
10. Claimed in a tube made of aluminum or an aluminum alloy having one or more holes, or a heat exchanger made of a tube made of aluminum or an aluminum alloy having one or more holes and a fin made of aluminum or an aluminum alloy. ^{The coating film or the coating film coated with a coating film amount of 0.1 to 3 g / m 2} after drying in which the solvent of the hydrophilic coating composition according to any one of 1 to 5 is volatilized is brazed. A heat exchanger characterized in that the film after being alloyed is partially or entirely provided.
11. A fin having a corrugated shape made of aluminum or an aluminum alloy and a tube made of aluminum or an aluminum alloy having a single or a plurality of holes are provided, and a plurality of the tubes made of the aluminum or the aluminum alloy are arranged in parallel, and further arranged in parallel. The hydrophilic coating composition according to any one of claims 1 to 5, in a heat exchanger in which fins having a corrugated shape are brazed between tubes made of the aluminum or the aluminum alloy. It is characterized in that a coating film coated with a coating film amount of 0.1 to 3 g / m ² after drying in which the solvent is volatilized or a film after the coating film is brazed is provided on a part or the entire surface. Heat exchanger.
12. The heat exchanger according to claim 10 or 11.
    It is characterized in that at least one selected from the aluminum member according to claims 6 and 7, the fin formed from the aluminum plate material according to claim 8, and the aluminum tube according to claim 9 is used. Heat exchanger.

Images