JP2009269043A - Coating material for aluminum alloy brazing, excellent in moisture resistant brazing, and aluminum alloy plate for brazing, aluminum alloy member for automobile heat exchanger using the plate, and automobile heat exchanger - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coating material for aluminum alloy brazing, which is prevented from deterioration during the storage under a high humidity atmosphere, prevents lowering of brazing property, and is excellent in moisture resistant brazing property, and also to provide an aluminum alloy plate for brazing, an aluminum alloy member for automobile heat exchangers using the plate, and an automobile heat exchanger. <P>SOLUTION: In the coating material for aluminum alloy brazing, a flux powder and an oxide compound are blended, wherein the oxide compound consists essentially of silicon oxide and/or aluminum oxide and includes a micropore structure. A filler metal powder and/or an acrylic resin based binder are also blended as necessary, with the balance a solvent. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention is used for an automotive heat exchanger manufactured by a brazing method, and is an aluminum alloy brazing paint excellent in moisture brazing resistance, an aluminum alloy plate for brazing, and an aluminum alloy member for an automotive heat exchanger using the same. As well as an automotive heat exchanger.

Conventionally, in aluminum members used in water-cooled automobile heat exchangers such as radiators and heater cores, for example, an Al-Si brazing material is provided on one side of a tube material or a header material, and a JIS standard 7072 alloy is provided on the other side. A brazing sheet clad with a sacrificial anode skin material is used, combined with a bare fin material and brazed.
Further, in car air conditioner materials such as capacitors, an extruded multi-hole tube and a so-called clad fin material in which a brazing material is clad on both surfaces are combined and brazed. Such a member for an automobile heat exchanger is molded and assembled into a shape as a heat exchanger, and then a fluoride-based flux (mainly KAlF ₄ ) is applied, and it will be in an inert gas atmosphere such as nitrogen gas. It is attached.

  However, when the conventional brazing method as described above is used, the aluminum alloy clad material is very expensive, and the flux is non-uniform and surplus, resulting in an increase in manufacturing cost. In addition, since flux is scattered in the coating process, environmental measures such as health management for workers are required, and maintenance costs are required for equipment management, resulting in a significant increase in manufacturing costs. . Furthermore, there is a problem that brazing failure occurs in the joining between members due to the flux falling off.

  For this reason, recently, a technique for brazing without using a clad material as described above has been developed, for example, a composition comprising Si, Cu, Ge and a flux on the surface of aluminum, copper, brass, steel or the like. A technique for applying an object and brazing the metal and an aluminum member has been proposed (for example, Patent Document 1). The technique described in Patent Document 1 is applied to a condenser of a car air conditioner, and a heat exchanger in which a brazing material composition applied to an extruded multi-hole pipe and a bare fin are joined in combination is put into practical use. According to Patent Document 1, it is possible to braze an aluminum member without using an expensive clad material.

  However, the technique described in Patent Document 1 has a problem that, as in the case of using the clad material, the amount of flux applied becomes non-uniform, resulting in excessive flux and an increase in manufacturing cost. In addition, since there are many cases in which a binder is not used when brazing by such a method, a coating film (flux) may be lost in a process treatment performed after coating as described above, and there is a possibility that poor brazing may occur. is there. Further, similarly to the above, since the flux is scattered in the coating process, it is necessary to take environmental measures, and there is a problem that the manufacturing cost increases.

  In addition, a heat exchanger has been proposed in which a brazing filler metal or flux powder is applied to an aluminum alloy base material before processing, and this is formed by a method such as pressing (for example, Patent Document 2). According to the aluminum heat exchanger described in Patent Document 2, it is possible to prevent the flux from being excessively applied without using an expensive aluminum alloy clad material, and to perform a coating process using a binder. Thus, the coating film can be prevented from falling off in the subsequent process, and a heat exchanger can be efficiently obtained by the brazing method.

However, in the heat exchanger described in Patent Document 2, since the adhesion of the coating film to the aluminum alloy base material is not so high, the coating film is peeled off when the aluminum alloy material is processed with a large deformation. May occur. For this reason, although the above-described coating film is used by applying it to an extruded material that is hardly subjected to molding processing, there is no problem, but a material that is subjected to large molding processing such as a plate material. When used by applying to the surface, there is a risk that the adhesion will be insufficient and the coating film will peel off, resulting in poor brazing.
In addition, a film in which a coating film as described in Patent Document 2 is formed on the plate material may be used. In such a case, the coating film is formed only on a portion that does not come into contact with the mold during molding. Therefore, there is a problem that it cannot be applied to a complicated product shape.

  As described above, in the brazing method described in Patent Document 1 in which the coating film is formed on the molded member, the coating film is peeled off when the heat exchanger is assembled, and is made of the above components in advance. In the heat exchanger brazing method described in Patent Document 2 in which a heat exchanger is configured using a pre-coated plate on which a coating film is formed, the coating film is peeled off during the molding process of the member, which is high in any case. There was a problem that the attachment strength could not be obtained.

  In addition, for the purpose of improving coating film adhesion at the time of processing an aluminum alloy material, a structural unit derived from a monoacrylate of ethylene glycol substituted with a specific group and a structural unit derived from an acid group-containing ethylenically unsaturated monomer Brazing binder comprising a binder for brazing made of an acrylate copolymer containing a binder and 0.1 to 50 parts by weight of a crosslinking agent per 100 parts by weight of the brazing binder Compositions have been proposed (for example, Patent Document 3).

However, when the brazing composition described in Patent Document 3 is applied to an aluminum alloy material, sufficient peel resistance can be obtained when subjected to strong processing such as pressing or roll forming. There is no problem.
Japanese National Patent Publication No. 6-504485 Japanese Patent Laid-Open No. 9-029477 JP 2005-028400 A

  Usually, flux or brazing powder is coated with a resin such as an acrylic binder, and an aluminum alloy material with a brazed coating layer formed is usually temporarily stored in a warehouse or process after the coating layer is formed. Although it is stored, depending on the storage state at this time, the coating layer may be exposed to high humidity. In the aluminum alloy material on which a coating film made of a brazing composition having a conventional composition as described in Patent Documents 1 to 3 is formed, when stored or left in a high humidity environment as described above Even if the period is a short period, the coating layer is deteriorated by moisture, so that there is a problem that the brazing property is remarkably lowered during use in the subsequent manufacturing process. As a mechanism for causing such deterioration of the coating layer, for example, the following explanation can be considered.

  FIGS. 5A and 5B show a state where the flux 110 and the Si powder 120 as the brazing material are fixed on the aluminum alloy base material 100 by the binder resin 130 and formed as the brazed coating layer 101. It is a schematic diagram. Here, when the brazed coating layer 101 fixed on the aluminum alloy substrate 100 as shown in FIG. 5A is stored in a state exposed to high humidity, it is shown in FIG. 5B. Thus, it is considered that moisture enters along the interface between the flux 110 and the Si powder 120 and the binder resin 130 (see the moisture intrusion 200 in FIG. 5B). This is because, as shown in FIGS. 6A and 6B, the flux 110 and the Si powder 120 or the aluminum alloy substrate 100 are inorganic, and generally there are many hydroxyl groups on the surface. This is considered to be due to forming a hydrogen bond or the like with the hydroxyl group in the binder resin 130 when the coating layer is formed. In addition, since hydroxyl groups have a strong affinity for water, it is considered that one of the causes is that water is easily taken into the coating film.

  And, since moisture permeates through the above mechanism, moisture present in the coating layer promotes oxidation (corrosion) of the aluminum alloy substrate 100, the flux 110, and the Si powder 120, and the oxide film increases, thereby brazing. The oxide film removal action by the flux 110 at the time is obstructed. Moreover, in the temperature rising process at the time of brazing, the moisture present in the coating film evaporates and the dew point in the brazing furnace is raised, which is a cause of inhibiting good brazing properties.

  In order to prevent the above-described problems, for example, a method of suppressing the exposure to a high-humidity atmosphere by storing a member in a location where air-conditioning management is well-known can be considered. There has been a problem that a great deal of cost is required for the management of the members after the film formation, resulting in an increase in manufacturing costs. For this reason, in an aluminum alloy brazing coating material containing flux, brazing powder, etc., even when exposed to a high-humidity atmosphere after the formation of a coating layer, the brazing property may decrease in the subsequent steps. There has been a demand for an aluminum alloy brazing coating material that has high moisture resistance and excellent brazing properties.

  The present invention has been made in view of the above problems, and even when stored in a high-humidity atmosphere after the coating film layer is formed, deterioration does not occur and it is possible to prevent a decrease in brazing performance. An object of the present invention is to provide an aluminum alloy brazing paint excellent in moisture brazing resistance, an aluminum alloy plate for brazing, an aluminum alloy member for an automobile heat exchanger using the same, and an automobile heat exchanger.

In order to solve the above problems, the present inventors have conducted intensive research on components to be added to the aluminum alloy brazing coating material. As a result, silica gel compounds, zeolite compounds, etc., silicon oxide and / or aluminum oxide as a main component. In addition, an oxide compound having a microporous structure is excellent in hygroscopicity because water molecules are effectively taken into the pores by capillary action, and such an oxide compound is appropriately added to the brazing paint. By doing so, it has been found that it is possible to preferentially adsorb the moisture and brazing powder that contribute to brazing, or the moisture present on the surface of the aluminum alloy substrate. In addition, since such an oxide compound has a large surface area due to a microporous structure and has many functional groups, hydrogen bonding or bonding with a binder, an inorganic powder group, or a silane coupling agent in the film is difficult. It was found that the cross-linking between the molecules increases the crosslink density of the brazed coating film and prevents moisture in the atmosphere from entering the brazed coating film. And by these actions, it was found that excellent moisture brazing resistance can be obtained by suppressing the increasing action of the oxide film, which is a cause of lowering brazing, during the brazing treatment, and the present invention was completed. .
That is, the present invention relates to the following.

(1) Invention according to claim 1 The flux powder and an oxide compound containing silicon oxide and / or aluminum oxide as a main component and having a microporous structure are blended. An aluminum alloy brazing paint excellent in moisture brazing resistance, characterized in that an acrylic resin binder is blended and the balance is a solvent.
(2) Invention of Claim 2 The said oxide compound is either the silica gel type compound which has silicon oxide as a main component, and the aluminum oxide and / or the zeolite type compound which has silicon oxide as a main component. The paint for brazing aluminum alloy having excellent moisture brazing resistance according to claim 1, comprising: or both.
(3) Invention of Claim 3 The total content of the said silica gel type compound and / or the said zeolite type compound shall be 6% or less of mixture ratio by mass ratio with respect to content of the said flux powder. The aluminum alloy brazing paint having excellent moisture brazing resistance according to claim 2.

(4) Invention of Claim 4 The brazing coating layer consisting of the coating composition for aluminum alloy brazing excellent in moisture brazing resistance according to any one of claims 1 to 3, wherein the brazing coating layer is at least of an aluminum alloy substrate. An aluminum alloy plate for brazing, which is formed on any surface.
(5) Invention of Claim 5 The aluminum alloy member for motor vehicle heat exchangers using the aluminum alloy plate for brazing of Claim 4.
(6) Invention of Claim 6 The automobile heat exchanger formed by using the aluminum alloy member for automobile heat exchangers of Claim 5.

  According to the aluminum alloy brazing coating material excellent in moisture brazing resistance of the present invention, as described above, the oxidation is mainly composed of flux powder and silicon oxide and / or aluminum oxide and has a fine pore structure. According to the composition in which a moisture absorbing component of the compound is blended and, if necessary, a brazing filler metal powder and / or an acrylic resin binder, a flux powder, a brazing filler metal powder, an acrylic resin binder, or a brazing paint Moisture present on the surface of the aluminum alloy substrate to be applied can be absorbed effectively, and the crosslink density of the brazing coating film is increased, preventing moisture from entering the brazing coating film. it can. An aluminum alloy for brazing excellent in moisture brazing resistance and strength characteristics after brazing by forming a brazing coating layer on an aluminum alloy substrate using such a brazing paint excellent in moisture resistance. A plate can be obtained, and further, an aluminum alloy member for an automobile heat exchanger using the brazed aluminum alloy plate can be constituted. Therefore, the assembly efficiency when manufacturing the automobile heat exchanger by the brazing method is improved, and the brazing strength after the automobile heat exchanger is assembled can be improved.

  Hereinafter, the aluminum alloy brazing paint excellent in moisture brazing resistance according to the present invention (hereinafter may be abbreviated as “brazing paint”), the brazing aluminum alloy plate (hereinafter abbreviated as “aluminum alloy board”). 1), and an aluminum alloy member for an automobile heat exchanger (hereinafter sometimes abbreviated as “aluminum alloy member”) and an embodiment of the automobile heat exchanger in which it is used, refer to FIGS. While explaining.

[Aluminum alloy brazing paint]
The brazing coating material of this embodiment (see also the brazing coating layer 3 shown in FIG. 1) is an oxide having a fine pore structure while containing flux powder and silicon oxide and / or aluminum oxide as main components. A compound is blended, and if necessary, a brazing filler metal powder and / or an acrylic resin binder is blended, and the remainder is used as a solvent, and is roughly configured.

"Flux powder"
The flux powder is blended with a silica gel compound and / or a zeolite compound to form the brazing paint of this embodiment.
The flux powder used in the present embodiment forms the flux powder when brazing the aluminum alloy plate 1 on which the brazing coating layer 3 made of a brazing paint as illustrated in FIG. 1 is formed. KAlF ₄ or the like melts to break the aluminum alloy plate 1 and the oxide film of the brazing material powder, thereby improving the brazing property.
As the flux powder, a commonly used fluoride-based flux such as KAlF ₄ , KZnF ₃ , K ₂ SiF ₆ is appropriately selected, and any one of them is used alone or two or more kinds are mixed. Therefore, it can be used without any problem. At this time, even when two or more kinds of fluxes are mixed and used, the characteristics as the flux powder are not affected.

The particle size of the flux powder is limited to, for example, the entire thickness of the brazing coating layer 3 formed by applying the brazing paint of the present embodiment on the aluminum alloy substrate 2 as shown in FIG. However, there is essentially no effect on adhesion and coating strength. Moreover, it is preferable that the average particle diameter of all the particles of the component composition is 1-5 micrometers or less. By setting the particle size of all the particles of the flux powder to the above, the brazing property can be improved.
When the particle size of the flux powder exceeds 5 μm, for example, when the radiator 20 in which a plurality of tubes are aligned as shown in FIG. 3 is assembled, the tubes (aluminum alloy members for automobile heat exchanger) 10 and the fins 22 It will be in the state assembled | attached by the flux powder with a large particle size interposing in a junction part. When the heat brazing process is performed in this state, the flux powder having a large particle size is dissolved, and the tube 10 and the fins 22 are reduced in size and brazed. When the tube 10 and the fins 22 are assembled with, for example, several tens of layers, the reduction in each joint is accumulated, and the dimensions in the radiator core may be greatly shifted by several millimeters, resulting in poor brazing. There is.
In addition, the minimum of the particle size of the flux powder normally used is 1 micrometer.

"Hygroscopic components (oxidized compounds: silica gel compounds, zeolite compounds)"
The aluminum alloy brazing paint according to the present invention contains silicon oxide having a hygroscopic action and / or an oxide compound containing aluminum oxide as a main component and having a microporous structure. In the present embodiment, the oxide compound having a microporous structure described above is a silica gel-based compound containing silicon oxide as a main component and an aluminum oxide and / or a zeolite compound containing silicon oxide as a main component. An example of either one or both will be described.

When a silica gel compound is added to the brazing paint, the type of the silica gel compound is not particularly limited, and any conventionally known silica gel compound having a hygroscopic action can be used without any limitation. For example, silicon oxide (SiO ₂ ) Can be used as a main component.
In addition, when a zeolite compound is added to the brazing paint, the type of the zeolite compound is not particularly limited, and a conventionally known zeolite compound having a hygroscopic action, such as aluminum oxide (Al ₂ O ₃ ) or it can be used as the SiO ₂ is a main component.
The silica gel compound and the zeolite compound used in the present invention can constitute a brazing coating material having sufficient moisture resistance by having the above components as the main component chemical composition. Moreover, each said component may be obtained by processing a natural product, or may be industrially rigid.

  The particle size of the silica gel compound or zeolite compound added to the brazing paint is not particularly limited, and is formed on the aluminum alloy substrate 2 in the same manner as the particle size of the flux powder described above. Although it is limited by the overall thickness of the brazed coating layer 3, it does not essentially affect the adhesion or coating strength. In addition, the particle size of the silica-based compound or the zeolite-based compound is preferably 100 μm or less in each case, considering practicality in the manufacturing process, such as a painting operation on the aluminum alloy substrate 2. It is more preferable that

In the brazing paint of this embodiment, the total content of the silica gel compound and / or the zeolite compound is 6% or less by mass ratio with respect to the flux powder content. Is preferred.
As for the mixing ratio of the silica gel-based compound and the zeolite-based compound that are moisture-absorbing components, Al ₂ O ₃ and SiO ₂ that are the main components are applied to the brazing powder and brazing paint that are the coating layer constituent components. Since it is a component equivalent to the oxide film of the aluminum alloy substrate, excessive addition becomes a factor that hinders the action of removing the oxide film by the flux powder at the time of brazing, so it is necessary to add it in an appropriate range.

  As a result of intensive studies on the optimum blending ratio of silica gel compounds and zeolite compounds into the brazing paint, the present inventors have determined that the total blending amount of these moisture-absorbing components is contained in the flux powder blended into the brazing paint. It has been found for the first time that excellent initial brazing property and moisture brazing resistance can be achieved by controlling the blending ratio to be 6% or less by mass with respect to the amount.

  In addition, the compounding ratio of the silica gel compound or the zeolite compound with respect to the content of the flux powder as described above is an optimum value when a silica gel compound or a zeolite compound having a practical particle size of 10 μm or less is used. It is. On the other hand, for example, when a silica gel compound or a zeolite compound having a particle diameter exceeding 10 μm is used, it is considered that the mass specific surface area of the silica gel compound or the zeolite compound is changed. The blending ratio is not limited to the above range (6% or less).

  In general, an acrylic resin binder is used as a binder in an aluminum alloy brazing paint. And when blending a monosilane silane coupling agent as a general silane coupling agent into the paint for brazing, as shown in the schematic diagram shown in FIG. 4, between the acrylic resin binder and the aluminum alloy substrate, The bonding strength between the brazing filler metal powder and the acrylic resin binder and between the flux powder and the acrylic resin binder is improved. In this case, for example, the moisture adhesion resistance evaluation of the coating layer made of the paint for brazing after being stored in a high humidity atmosphere in which the temperature is 30 ° C., the humidity is 90% RT, the test time is 1 month, and the like. It has been confirmed by experiments of the present inventors that adhesion equivalent to the initial state (initial adhesion) can be obtained. However, the present inventors have conducted intensive research and formed a coating layer using a brazing paint containing a monosilane silane coupling agent as described above, and moisture brazing resistance after storage in a high humidity atmosphere. As a result, it was found that the residue after brazing tends to increase compared to the brazing property when brazing is performed in the initial state, and that sufficient and practical moisture brazing resistance is not necessarily obtained. became.

  For this reason, the present inventors blended a brazing paint with a silica gel compound, a zeolite compound, etc., an oxide compound having a microporous structure with silicon oxide and / or aluminum oxide as a main component, By effectively taking water molecules into the pores by the capillary phenomenon of this oxidized compound, the moisture existing on the surface of the flux, brazing powder, or aluminum alloy substrate that contributes to brazing is preferentially absorbed. Focused on that. Furthermore, the oxidized compounds as described above have a large surface area due to the microporous structure and have many functional groups, and therefore, hydrogen exists between the binder in the film, the inorganic powder group, or the silane coupling agent. We focused on the fact that bonding and intermolecular bonding increase the cross-linking density of the film and prevent moisture in the atmosphere from entering the film. And by these actions, by suppressing the increase action of the oxide film during the brazing treatment, even when brazing after storage in a high-humidity atmosphere, which is the above conditions, when brazing in the initial state In the same manner as above, a coating layer having excellent brazability without residue was obtained.

"Brass powder"
The brazing material powder is a selected component in the present invention, and is a brazing material contained in the brazing paint together with the flux powder, the silica gel-based compound, the zeolite-based compound, and the like. (See reference 2) A wax is formed by diffusing inside.
As the brazing filler metal powder, for example, conventionally known ones such as Si powder, Al—Si alloy powder, Al—Cu alloy powder, etc. can be used, and any one of these may be used alone or in combination of two or more. It can be used by mixing, and further contains inevitable impurities.

The particle size of the brazing filler metal powder is limited by the overall thickness of the brazing coating layer 3 formed on the aluminum alloy substrate 2 as in the case of the above-described flux powder. It does not affect the film strength.
In addition, when the aluminum alloy plate by which the coating material for brazing of this embodiment is applied as a coating film layer is used for a radiator tube material or the like, and the coating film coating amount is 20 g / m ² or less, a relatively thin film is applied. In order to suppress erosion, the particle size of the brazing filler metal powder is preferably 10 μm or less. However, if the main particle size is less than 1 μm, the surface area of the powder increases and it is necessary to increase the flux. Therefore, the particle size of the brazing powder is more preferably in the range of 1 to 10 μm. On the other hand, when an aluminum alloy plate is used as a radiator header plate material and a relatively thick film is applied with an application amount of 40 g / m ² or more, in order to suppress an increase in oxide film due to the particle size, it is 10 μm or more. It is preferable to use a particle size, and it is more preferable to use a particle size of 20 μm or more. However, since the allowable erosion depth is limited by the plate thickness of the member, for example, in a header member of 1 mmt or more, the upper limit of the particle size is preferably about 75 μm.

"Acrylic resin binder"
The acrylic resin binder is a selective component in the present invention, and is contained in the brazing paint together with the flux powder, the silica gel compound, the zeolite compound and the like, and the brazing filler powder and the flux powder are made of aluminum. It has the effect | action fixed to the alloy base material 2.
Generally, an acrylic resin binder is used as a binder for brazing, and phosphoric acid is used as a group for imparting adhesion and coating strength to an aluminum alloy substrate of a coating layer for brazing made of a brazing coating. Functional groups such as a group, a carboxylic acid group, a sulfonic acid group, and a hydroxyl group are employed, and the blending ratio thereof is determined in consideration of the residual carbon property during brazing.

  As the acrylic resin binder to be blended in the brazing paint of this embodiment, any conventionally known one can be used without any limitation, and any resin can be used as long as it is a general acrylic resin. However, a fixed effect can be obtained, and a greater effect can be obtained if the molecular weight is in the range of about 20,000 to 500,000. Further, when an acrylic resin obtained by copolymerizing each of an methacrylic acid alkyl ester monomer, an acrylic acid alkyl ester monomer, and an ethylenically unsaturated monomer containing a hydroxyl group is used as the main skeleton Is more preferable in that the adhesion of the coating film is further improved by using a silane coupling agent described later in combination.

"Silane coupling agent"
In the brazing paint of this embodiment, in addition to the above components, the coating strength and the base material are applied by a dehydration condensation reaction when the coating film is dried after being applied to the aluminum alloy base material 2 as shown in FIG. It can be set as the structure which mix | blended the silane coupling agent which contributes to the improvement of adhesiveness. In general, monosilane silane coupling agents may be used as the silane coupling agent to be blended in the brazing paint.

In the monosilane silane coupling agent described above, as shown in the schematic diagram of FIG. 4, one end group becomes an inorganic functional group composed of an alkoxyl group that causes a dehydration condensation reaction, and the other end group is an organic functional group. In addition, there is an effect of increasing the bonding force between the aluminum alloy base material and the acrylic resin binder and between the brazing filler metal powder and the acrylic resin binder. Usually, an alkoxyl group causing a dehydration condensation reaction of a silane coupling agent is bonded to an inorganic substance (aluminum alloy base material 2, flux powder, brazing powder), while an organic reactive group is bonded to an acrylic resin binder. The effect is obtained. By such an action, when a monosilane silane coupling agent is blended in the brazing paint, it becomes possible to improve the moisture-resistant adhesion of the brazing paint to the aluminum alloy substrate.
Moreover, even when a silane coupling agent is blended together with a silica gel compound or a zeolite compound, which is a moisture absorption component, for the purpose of improving moisture resistance adhesion, the moisture absorption action is not hindered. The effect of the present invention that improves the properties can be sufficiently obtained.

  According to the aluminum alloy brazing paint excellent in moisture brazing resistance of the present embodiment as described above, as described above, the flux powder and silicon oxide and / or aluminum oxide are the main components. The composition contains a moisture absorption component of an oxide compound having a microporous structure and, if necessary, a brazing filler metal powder and / or an acrylic resin binder, so that flux powder, brazing filler metal powder, acrylic resin binder Alternatively, moisture present on the surface of the aluminum alloy substrate to which the brazing paint is applied can be effectively absorbed, and the crosslink density of the brazing coating film is increased, so that moisture in the atmosphere can be brazed. Intrusion into the paint film can be prevented. An aluminum alloy for brazing excellent in moisture brazing resistance and strength characteristics after brazing by forming a brazing coating layer on an aluminum alloy substrate using such a brazing paint excellent in moisture resistance. A plate can be formed.

[Aluminum alloy plate for brazing]
Below, the aluminum alloy plate (aluminum alloy plate) 1 for brazing concerning this invention is demonstrated, referring FIGS. 1-3 suitably.
The aluminum alloy plate 1 of the present embodiment is formed by forming the aluminum alloy brazing paint excellent in moisture brazing resistance according to the present invention as described above on at least one surface of the aluminum alloy substrate 2. In the aluminum alloy plate 1 of the embodiment shown in FIG. 1, a brazing coating layer 3 made of the above-mentioned brazing paint is formed on the one surface 2 a side of the aluminum alloy substrate 2.

(Aluminum alloy base material)
The aluminum alloy substrate 2 is a substrate of the aluminum alloy plate 1 of the present embodiment, and any conventionally known aluminum alloy material can be used without any problem. For example, Si, Mn, the remaining Al and inevitable impurities can be used. The component composition is contained, and other elements are added as necessary to improve strength characteristics, erosion resistance, and the like.
In the example shown in FIG. 1, the brazing coating layer 3 made of the above-described brazing paint is formed only on one surface 2a of the aluminum alloy substrate 2, but the other surface 2a is also brazed. A configuration in which the film layer 3 is provided may be employed. Moreover, it can also be set as the structure which provided the brazing coating-film layer 3 in the 1st surface 2a side, and provided the sacrificial material coating-film layer containing Zn for improving the corrosion resistance of an aluminum alloy board in the other surface 2b side.

(Method of forming a brazed coating layer)
The solvent used when the above-mentioned brazing paint is applied to the one surface 2a of the aluminum alloy substrate 2 to form the brazed coating layer 3 is not particularly limited, and the resin used for the binder is organic. Uses a conventionally known organic solvent, and in the case of a water-soluble resin, water can be used as a solvent. As the organic solvent, 3-methoxy-3-methyl-1-butanol can be suitably used from the viewpoint of ease of handling during work and environmental aspects.

The method for applying the brazing paint to the one surface 2a of the aluminum alloy substrate 2 may be selected as appropriate in consideration of the member to be applied, the amount of application, and the like. For example, roll coating, die coating, flow coating, spraying Various means such as shower, dipping, brush, and bar coat can be selected and used. Due to the difference in the coating methods, there is no difference in the characteristics of the brazed coating layer 3. However, since there is an optimum value such as viscosity in each coating method, it is preferable to optimize the solvent blending ratio as appropriate. Moreover, the material of the aluminum alloy substrate 2 to be used does not affect properties such as coating film adhesion.
The brazed coating layer 3 may be formed on the entire surface 2a of the aluminum alloy substrate 2, but may be configured to be formed only at a location where brazing is performed on the aluminum alloy plate 1, for example. .

  In addition, as mentioned above, when a silane coupling agent is blended in a brazing paint for the purpose of improving moisture-resistant adhesion, the brazing coating layer 3 is formed by application to the aluminum alloy substrate 2. Before, hydrolysis on the alkoxyl group side is required, but even when an organic solvent is used, hydrolysis proceeds due to moisture contained in the air, so even if water is not actively added, the silane coupling agent The effect of adding is obtained. However, the amount of moisture in the air may vary greatly, and sufficient hydrolysis may not always be obtained. Since the alkoxyl group remaining without being hydrolyzed has low reactivity with an inorganic material such as an aluminum alloy base material, it does not sufficiently contribute to the improvement of adhesion. In addition, it is not preferable that the alkoxyl group remains without being hydrolyzed because it may be a source of harmful gas in a brazing atmosphere. For this reason, when a silane coupling agent is blended in the brazing paint, it is not possible to use a structure in which an amount of water necessary for hydrolysis is added in advance as a hydrolysis accelerator for the silane coupling agent. It is preferable from the point that it can suppress that the alkoxyl group of hydrolysis remains, and the outstanding coating-film adhesiveness is obtained.

(Sacrificial coating layer)
In the aluminum alloy plate 1 of the present embodiment, as described above, a sacrificial material made of a composition containing Zn-containing flux powder and the above-described binder on the other surface 2b side of the aluminum alloy substrate 2. It is good also as a structure provided with the coating-film layer.
Here, as the flux powder containing Zn, for example, a fluoride-based flux such as ZnF ₂ or KZnF ₃ can be used, and KAlF ₄ or the like may be mixed and used.

By providing a sacrificial material coating layer containing Zn on the other surface 2b side of the aluminum alloy substrate 2, the corrosion resistance on the other surface 1b (the other surface 2b of the aluminum alloy substrate 2) side of the aluminum alloy plate 1 is improved. It becomes possible.
Moreover, when forming the tube 10 (aluminum alloy member for brazing) which consists of the aluminum alloy board 1 like the example shown in FIG. 2, the other surface 1b (other surface 2b) in which a sacrificial material coating film layer is provided. By forming the tube so that the side is on the inside, the corrosion resistance of the inner surface of the flow hole 10a formed on the inner side of the tube 10 is improved, and the progress of corrosion due to the coolant flowing in the flow hole 10a can be prevented.

[Aluminum alloy member for brazing for automobile heat exchanger and automobile heat exchanger]
The brazing aluminum alloy plate 1 of the present embodiment as described above is an alloy that forms, for example, a radiator tube (aluminum alloy member for automobile heat exchanger: hereinafter sometimes abbreviated as a tube) 10 as shown in FIG. It can be used as a plate material, and the tube 10 is used by being incorporated in a radiator (heat exchanger) 20 as shown in FIG.
The tube 10 is formed as a hollow flat tube material having a flow hole 10a inside by bending the aluminum alloy plate 1 so that the other surface 1b side is inside and joining both ends (not shown). can get.

A radiator 20 shown in FIG. 3 is used, for example, in a radiator of an automobile, and is generally configured by a tube 10, a header 21, fins 22, and side supports 23. The radiator 20 is manufactured by integrating the tube 10, the header 21, and the fins 22 by brazing and further attaching a resin tank by mechanical joining (caulking).
In the radiator 20, the header 21 and the tube 10 are arranged around the insertion portion by inserting the end portion of each tube 10 into a plurality of slots (insertion holes) 21 a formed on the lower surface of the header 21. The tubes 10 and the fins 22 are brazed to each other using a material, and the composition applied to the surface of the tube 10, that is, one surface 1 a side of the aluminum alloy plate 1 (one surface 2 a of the aluminum alloy substrate 2). It is assembled by brazing each other using the brazed coating layer 3 provided on the side).

(Brazing method)
As shown in FIG. 3, when assembling and brazing the radiator 20 including the tube 10 made of the aluminum alloy plate 1 of the present embodiment, the brazing coating layer 3 was provided on the surface of the header 21. After assembling the tube 10 and the fins 22, the brazing material is dissolved by heating to an appropriate temperature in an appropriate atmosphere such as a nitrogen atmosphere.
The brazing heat treatment is preferably performed at about 580 ° C. to 610 ° C., and the holding time is preferably about 1 minute to 10 minutes. If the temperature during brazing is less than 580 ° C., partial melting of the brazing material and the aluminum alloy base material will not proceed, and it will be difficult to perform good brazing. Moreover, when the temperature at the time of brazing exceeds 610 degreeC, there exists a possibility that remarkable erosion may arise.

  According to the structure of the radiator 20 described above, since the tube 10 is joined to the header 21 provided with the slot 21a for inserting the tube 10 on the lower surface, the strength of the entire assembly after brazing can be increased. it can.

  As described above, according to the brazing aluminum alloy plate 1 of the present embodiment, the brazing coating layer 3 made of the brazing paint according to the present invention is provided. The brazing aluminum alloy plate 1 having improved moisture brazing resistance and adhesion of the coating layer 3 and excellent strength characteristics after brazing is obtained. Further, a tube (aluminum alloy member for an automobile heat exchanger) 10 can be configured using the aluminum alloy plate 1 for brazing of the present embodiment, and further, a radiator (an automobile heat exchanger) 20 can be formed using the tube 10. When configured, the assembly efficiency when the radiator 20 is manufactured by the brazing method can be improved, and the strength of the radiator 20 after the assembly can be improved. Therefore, the assembly efficiency when manufacturing the automobile heat exchanger by the brazing method is improved, and the brazing strength after the automobile heat exchanger is assembled can be improved.

Examples The aluminum alloy brazing paint excellent in moisture brazing resistance of the present invention will now be described in more detail with reference to examples, but the present invention is not limited to these examples.
Below, the preparation process and evaluation test item of an aluminum alloy plate are demonstrated.

[Production process]
First, 3003-H14 was used as an aluminum alloy material, and an aluminum alloy base material having a plate thickness of 0.25 mmt was produced.
Moreover, as a coating material for brazing applied as a brazing coating layer, a coating composition having a composition ratio shown in Table 1 below was prepared.
And as shown in FIG. 1, after apply | coating the composition which makes the brazing coating-film layer of each component composition on the one surface side of an aluminum alloy base material in the quantity of about 20 g / m < ² >, The brazed coating layer 3 was formed by drying at a temperature of 150 ° C. for 5 minutes, and the aluminum alloy plate 1 according to the present invention and the conventional aluminum alloy plate were obtained for each production condition shown in Table 1.

In addition, as an acrylic resin-type binder mix | blended with the coating material for brazing of the composition shown in following Table 1, conventionally well-known general acrylic resin is used, and as a solvent, 3-methoxy-3methyl-1- Butanol was used.
In addition, silica gel compounds and zeolite compounds used in each example were those having a particle size of 10 μm or less.

[Evaluation test]
About the aluminum alloy plate obtained by the said preparation process, two items of "initial brazing property" and "moisture brazing resistance" demonstrated below were evaluated and determined.

(Initial brazing)
Using the brazing paint of each composition shown in Table 1 below, using the same method as in the above production process, the aluminum alloy plates having the following specifications are used in the Examples and Comparative Examples shown in Table 1 below. Obtained for each production condition.
(A) Brazing material coating alloy: A3003 bare material, 0.25 mmt, tempered H14
(B) Flux coating alloy: A3003 / A4343 clad material, 0.25 mmt, clad rate 10% (both sides), tempered H14

Then, immediately, as shown in FIG. 2, the aluminum alloy plate was bent and both ends were joined and processed, and a hollow flat electric resistance tube material was manufactured for each aluminum alloy plate condition shown in Table 1.
Then, the tube material obtained by the above method is attached to a radiator (heat exchanger) as shown in FIG. 3, and after brazing heat treatment at a temperature of 600 ° C. for 3 minutes in a nitrogen atmosphere, the tube material is applied. The fin bonding rate was investigated. At this time, A3003 bare material (0.1 mmt) was used as the fin.
At this time, the fin bonding rate (%) was obtained by the following equation (1).
(Wax formation area / Installation area of tubes and fins) × 100 (1)

And from the fin joint rate calculated | required by the said (1) formula, the brazing property of each sample was evaluated and it determined with the following evaluation criteria.
(1) ○: The fin bonding rate was 90% or more.
(2) Δ: Fin bonding rate was 80% or more and less than 90%.
(3) x: The fin joint rate was less than 80%.

(Moisture brazing resistance)
Using the paint for brazing of each composition shown in Table 1 below, using the same materials and methods as described in the evaluation of the initial brazing property, the aluminum alloy plates were used in the Examples and Comparative Examples shown in Table 1 below. Obtained for each production condition.
Thereafter, the aluminum alloy plate samples of each Example and Comparative Example were stored for 1 month (30 days) in an environment of a temperature of 30 ° C. and a relative humidity of 90% RT.
Next, in the same manner as described in the evaluation of the initial brazing property, the aluminum alloy plate is bent and processed by joining both ends as shown in FIG. After manufacturing the aluminum alloy plate conditions shown, the obtained tube material was attached to a radiator (heat exchanger) as shown in FIG. 3 and subjected to brazing heat treatment at a temperature of 600 ° C. for 3 minutes. The fin bonding rate was investigated.
At this time, the fin was used in the same manner as described in the evaluation of the initial brazing property, and the brazing property of each sample was evaluated and determined by obtaining the fin joint rate in the same manner.

  Table 1 below shows a list of production conditions and evaluation test results for each example and comparative example.

[Evaluation results]
As shown in Table 1, an aluminum alloy brazing plate obtained by applying an aluminum alloy brazing coating material having the composition defined in the present invention to an aluminum alloy material has initial brazing resistance and moisture brazing resistance. All were evaluated as “◯”, and it was revealed that even when stored or left in a high humidity atmosphere, high brazing properties were exhibited.

On the other hand, in Comparative Example 1 in which neither the silica gel-based compound or the zeolite-based compound as the hygroscopic component was added, although the initial brazing property was evaluated as “◯”, the evaluation of the moisture brazing resistance was “×”. "
Further, in Comparative Example 2 in which neither a silica gel compound nor a zeolite compound was added, and no brazing powder was added, the initial brazing property was evaluated as “◯”, but the moisture brazing resistance Was evaluated as “×”.

  Based on the above results, the brazing aluminum alloy plate formed with the brazing coating layer made of the aluminum alloy brazing coating material having excellent moisture brazing resistance according to the present invention can be stored in any moisture resistant atmosphere. It was revealed that it was excellent in moisture brazing resistance.

It is sectional drawing which shows an example of the aluminum alloy board for brazing in which the coating material for aluminum alloy brazing which is excellent in the moisture brazing resistance which concerns on this invention was apply | coated, and the brazing coating-film layer was formed. 1 shows an example of a tube (aluminum alloy member for an automobile heat exchanger) made of an aluminum alloy plate for brazing coated with an aluminum alloy brazing coating material excellent in moisture brazing resistance according to the present invention and formed with a brazing coating layer. It is a perspective view. It is a perspective view which shows an example of the radiator (automobile heat exchanger) using the tube (aluminum alloy member for motor vehicle heat exchangers) which consists of an aluminum alloy plate for brazing concerning this invention. FIG. 6 is a schematic diagram for explaining another example of an aluminum alloy plate for brazing in which an aluminum alloy brazing coating material excellent in moisture brazing resistance according to the present invention is applied and a brazing coating layer is formed; It is the schematic which shows the coupling | bonding structure between a ring agent and an acrylic resin binder, and between a monosilane silane coupling agent and an inorganic substance. It is a schematic diagram explaining the aluminum alloy plate for brazing by which the coating material for conventional aluminum alloy brazing was apply | coated and the brazing coating-film layer was formed. It is a schematic diagram explaining the aluminum alloy plate for brazing by which the coating material for conventional aluminum alloy brazing was apply | coated and the brazing coating-film layer was formed.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Aluminum alloy plate for brazing, 1a ... One side, 1b ... Other side, 2 ... Aluminum alloy base material, 2a ... One side, 2b ... Other side, 3 ... Brazing coating layer (aluminum alloy brazing coating material), DESCRIPTION OF SYMBOLS 10 ... Tube, 10a ... Distribution hole, 20 ... Radiator (automobile heat exchanger), 21 ... Header, 22 ... Fin

Claims (6)

  Flux powder and silicon oxide and / or aluminum oxide as the main component and an oxide compound with a microporous structure are blended, and brazing powder and / or acrylic resin binder is blended as needed. An aluminum alloy brazing paint having excellent moisture brazing resistance, wherein the balance is a solvent.   The oxide compound is composed of one or both of a silica gel-based compound containing silicon oxide as a main component and an aluminum oxide and / or a zeolite compound containing silicon oxide as a main component. The aluminum alloy brazing paint excellent in moisture brazing resistance according to claim 1.   The total content of the silica gel-based compound and / or the zeolite-based compound is set to a blending ratio of 6% or less by mass ratio with respect to the content of the flux powder. Aluminum alloy brazing paint with excellent moisture brazing resistance.   The brazing coating layer made of the aluminum alloy brazing paint excellent in moisture brazing resistance according to any one of claims 1 to 3 is formed on at least one surface of the aluminum alloy substrate. An aluminum alloy sheet for brazing.   The aluminum alloy member for motor vehicle heat exchangers using the aluminum alloy plate for brazing of Claim 4.   An automobile heat exchanger using the aluminum alloy member for an automobile heat exchanger according to claim 5.

Images