JPH11192582A - Paste for brazing aluminum material, and aluminum material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve solvent resistance and storage stability without impairing brazing property. SOLUTION: The paste consists of brazing filler metal powder to braze an aluminum material, a binder resin, an organic solvent and/or water, the binder resin consists of a high molecule polymer having active hydrogen containing radicals and a crosslinking agent having a functional radical reactive with active hydrogen by heating.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a material made of an aluminum alloy, that is, an aluminum material brazing paste used for brazing an aluminum material, and an aluminum material to which the paste is applied. More specifically, the present invention relates to a brazing paste suitable for brazing when a heat exchanger such as an evaporator, a condenser, a radiator and the like made of aluminum alloys for automobiles and various industrial uses is joined, and an aluminum material to which the paste is applied.

[0002]

2. Description of the Related Art The assembly and manufacture of an aluminum alloy heat exchanger is generally performed as follows. That is, a brazing sheet in which a brazing material (brazing material) is clad on a base material is used for a tube formed of an extruded multi-hole tube,
Fins are brazed.

However, in recent years, in order to reduce the size and weight of the heat exchanger, as shown in Japanese Patent Application Laid-Open No. 9-85483, clad fins obtained by cladding a brazing material having a limit in thinning on a base material have been used. It has been proposed to replace the bare fin with a thinner wall, form a coating made of a brazing powder and a binder resin on the outer surface of the tube by coating, and braze the tube and the fin.

[0004]

A number of high molecular compounds have been proposed as the binder resin.
However, all of these polymer compounds were soluble in organic solvents. Therefore, in the manufacturing process of the heat exchanger, for some reason, when the organic solvent adheres to the coating, the polymer compound elutes, and the coating, that is,
The brazing filler metal powder was easily peeled from the tube. For this reason,
There was a problem that the brazing property was poor and the fin could not be brazed to the tube well.

The inventors of the present invention have conducted intensive studies to solve the above problems and storage stability (stability over time). As a result, a polymer which forms the basic skeleton of a binder resin is crosslinked with a specific crosslinking agent. Then, it has been found that by making the high-molecular polymer into a three-dimensional network, elution of the binder resin by the organic solvent can be prevented, and the present invention has been achieved.

[0006]

The paste for brazing an aluminum material according to the present invention is characterized by a brazing powder for brazing an aluminum material; a binder resin; an organic solvent and / or water; In the brazing paste made of aluminum, the binder resin comprises a polymer (A) having an active hydrogen-containing group (a) and a crosslinking agent having a functional group (b) capable of reacting with active hydrogen by heating ( B). In addition, high molecular polymer (A)
May be a polymer copolymer containing an ethylenically unsaturated monomer having an active hydrogen-containing group (a) and an alkyl (meth) acrylate monomer as essential constituent monomers. Further, the active hydrogen-containing group (a) may be one or more functional groups selected from the group consisting of a hydroxyl group, a carboxyl group, an amino group and a mercapto group. Further, the functional group (b) may be one or more functional groups selected from the group consisting of an amine imide group, a hydroxyalkylamide group, an alkoxyalkylamide group, a blocked isocyanate group and a blocked epoxy group. Further, the aluminum material of the present invention is characterized in that the aluminum material brazing paste is coated with a coating comprising a brazing filler metal powder and a binder resin, and the weight per 1 m ^{2 of} the coating is 10 to 100 g. It is in.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
The aluminum material brazing paste (brazing composition, brazing slurry) of the present invention comprises: a brazing material powder for brazing an aluminum material; and a binder resin:
An organic solvent and / or water;

As the brazing filler metal powder of the present invention, a metal which can be used alone as a brazing filler metal or a metal which reacts with the surface of an aluminum material to form a low melting point alloy layer and contributes as a brazing filler metal is used. However, various aluminum alloys are usually used. This aluminum alloy contains silicon (element)
Is larger than usual, that is, 10 to 50% by weight (% by weight)
What is contained is desirable. It is, as brazing powder
If an aluminum alloy containing more silicon than usual is used, the aluminum material to be brazed (work material,
This is because the amount of paste (that is, brazing powder, binder resin, etc.) applied to the material to be brazed can be reduced, and the effect of the present invention can be sufficiently exhibited. In some cases, the brazing filler metal powder is not used as an aluminum alloy containing silicon but is used as a silicon powder alone.

In addition, for the purpose of improving corrosion resistance, the brazing material powder contains elements other than silicon, such as zinc, iron, copper, manganese, tin, and indium, in an amount that does not adversely affect brazing properties. It may be added. For example, even if zinc is added up to about 40 wt%, there is no problem such as adverse effect on brazing properties.

The particle size of the brazing filler metal powder is preferably about 5 to 100 μm. If the particle size of the brazing filler metal powder is 5 μm or less, the production cost of the brazing filler metal powder is high, and an oxide film is easily formed on the brazing filler metal powder, which impairs brazing properties. Also, the particle size of the brazing filler metal powder has an upper limit of 100 μm.
When the above, in the drying step of substantially removing the organic solvent and / or water from the paste applied to the aluminum material,
The brazing material powder does not stay on the aluminum material, but easily falls along with the binder resin, and it becomes difficult to attach a predetermined amount of the brazing material powder on the aluminum material.

The binder resin of the present invention is for holding a brazing filler metal powder on an aluminum material and forming a uniform coating of the brazing filler metal powder and the binder resin on the aluminum material. In the brazing paste, the compounding amount of the binder resin is usually 2 to 200 parts by weight, preferably 5 to 100 parts by weight based on 100 parts by weight of the brazing material powder. The binder resin comprises a polymer (A) having an active hydrogen-containing group (a) and a crosslinking agent (B) having a functional group (b) capable of reacting with active hydrogen by heating. Active hydrogen-containing group (a) in polymer (A)
And the equivalent ratio (a) / of the functional group (b) in the crosslinking agent (B)
(B) is usually 0.2 to 5.0, and preferably 0.5 to 2.0 from the viewpoint of solvent resistance.

The weight average molecular weight of the polymer (A) is
From the viewpoint of applicability, 2,000 to 1,000,000 is preferable. The solubility parameter (hereinafter, simply referred to as SP value) of the polymer (A) is 50.0 from the viewpoint of corrosion resistance.
And preferably 8.5 to 30.0.
Note that the SP value is determined by the Fedors method [Polym. Eng. S
ci. 14 (2) 152, (1974)]. The polymer (A) is not particularly limited as long as it has an active hydrogen-containing group (a).
Preferably, it is a polymer copolymer containing an ethylenically unsaturated monomer having an active hydrogen-containing group (a) and an alkyl (meth) acrylate monomer as essential constituent monomers. The content of the active hydrogen-containing group (a) in the polymer (A) is preferably from 0.2 to 5.0 mmol / g, more preferably from the viewpoint of solvent resistance and blocking resistance.
0.4 to 2.0 mmol / g.

The active hydrogen-containing group (a) is not particularly limited, but is selected, for example, from the group consisting of a hydroxyl group, a carboxyl group, an amino group and a mercapto group (the above-mentioned optional constituents may be deleted). One or more functional groups. Among them, a hydroxyl group and a carboxyl group are preferable from the viewpoint of odor.

The method for introducing the active hydrogen-containing group (a) into the polymer (A) is not particularly limited.
The following methods are mentioned. That is, an ethylenically unsaturated monomer (α) having an active hydrogen-containing group (a) [for example, maleic acid, maleic anhydride, (meth) acrylic acid, 2-hydroxyethyl (meth) acrylate,
Hydroxypropyl (meth) acrylate, polyethylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, etc.) and other ethylenically unsaturated monomers (β), Grafting an ethylenically unsaturated monomer having an active hydrogen-containing group (a) using an organic hydrogen peroxide-based radical polymerization initiator [for example, tertiary butyl peroxy laurate, tertiary butyl peroxy acetate, etc.] And the like.

As the ethylenically unsaturated monomer (β),
For example, an olefin [e.g.
Olefin etc.], conjugated diene [for example, butadiene,
Isoprene, etc.], vinyl aromatic [eg, styrene,
α-methylstyrene and the like], vinyl esters [for example,
Vinyl acetate, etc.], alkyl (meth) acrylate [eg, (meth) acrylate having an alkyl group having 2 to 20 carbon atoms], vinyl pyridine [eg, N
-Vinyl pyridine and the like], vinyl lactam [for example, N
-Vinylpyrrolidone, 3-methyl-N-vinylpyrrolidone, etc.], vinylimidazole [eg, N-imidazole, 2-methyl-2-imidazole, etc.]; and mixtures of two or more of these. Of these, preferred from the viewpoint of low-temperature volatile decomposition properties are the above-mentioned alkyl (meth) acrylates, and more preferred are the alkyl methacrylates.

In the present invention, the use of the crosslinking agent (B) having a functional group (b) capable of reacting with active hydrogen by heating is as follows:
It is useful in terms of blocking resistance, storage stability and solvent resistance. The cross-linking agent (B) is not particularly limited. However, if a cross-linking agent (eg, polyisocyanate compound, polyepoxy compound, etc.) capable of reacting with active hydrogen even at a low temperature is used as the cross-linking agent (B), The storage stability (storage stability) and workability of the brazing paste are poor, which is not preferable.

The functional group (b) is not particularly limited as long as it is a functional group capable of reacting with active hydrogen by heating, and for example, a functional group which generates an isocyanate compound, an epoxy compound, a formalin compound, etc. by heating. Can be
From the viewpoint of solvent resistance and storage stability, as a functional group (b),
Preferably, an amine imide group [eg, 1,1-dimethyl-1- (2-hydroxypropyl) amine imide group, etc.], a blocked isocyanate group [eg, oxime block isocyanate, methanol block isocyanate, caprolactam block isocyanate, phenol block isocyanate, etc.] A group consisting of a block epoxy group [eg, a carbonate block epoxy group etc.], a hydroxyalkylamide group [eg, a methylolamide group etc.], an alkoxyalkylamide group [eg, a butyroxymethylamide group etc.] (The constituent element may be deleted.). The number of functional groups (b) contained in one molecule of the crosslinking agent (B) is usually 2 or more, preferably 3 or more, from the viewpoint of solvent resistance.

The compounding amount (content) of the organic solvent and / or water, which is a component of the brazing paste of the present invention, is as follows:
Although not particularly limited, the amount is adjusted so that the brazing paste has an appropriate viscosity for application (for example, brush application, spray application, roll coater application, dip coating, etc.). The organic solvent is not particularly limited,
From the viewpoint of drying properties, those having a boiling point of 250 ° C. or less are preferred.

The following may be added to the brazing paste of the present invention, depending on the functions imparted to the paste. For example, when imparting smoothness to the paste,
A low molecular lubricant [eg, methylpyrrolidone, isopropyl alcohol, etc.], a polymer lubricant [eg, polyacrylic acid, polyacrylamide, polyurethane, colloidal silica, etc.] may be added to the paste.

When a paste for brazing is imparted with a fungicidal or fungicidal property, the paste may be treated with a fungicide [for example,
1,2-benzisothiazolin-3-one or the like] or a fungicide [2-thiazol-4- (methylsulfonyl) pyridine or the like] may be added.

Further, when imparting a uniform coating property at the time of application to the brazing paste, a surfactant [for example, a nonionic surfactant such as polyoxyethylene alkyl phenyl ether, Anionic activators such as oxyethylene alkyl ether sulfates; cationic activators such as alkylamine salts;
Amphoteric activator such as N, N-trialkyl-N-sulfoalkylene ammonium betaine].

When the flux application step for the aluminum material is omitted during brazing, a flux such as a fluorine-based or cesium-based flux may be added to the brazing paste.

Further, when the workability of brazing is improved by increasing the curing speed of the brazing paste,
An acid catalyst [for example, an organic acid such as paratoluenesulfonic acid, dibutyl phosphate] or an alkali catalyst [for example, an organic amine such as tributylamine] may be added to the paste.

In producing the brazing paste of the present invention, a brazing filler metal powder, a binder resin and various additives to be added as necessary are dissolved in an organic solvent and / or water.
It can be easily produced by solubilizing, dispersing and suspending.

The method of using the brazing paste of the present invention includes a method of applying the paste to an aluminum material, substantially removing an organic solvent and / or water from the paste, and then curing the paste by heating. There is a method of simultaneously removing the organic solvent and / or water from the paste and curing the paste by heating. Methods for substantially removing organic solvents and / or water from brazing paste include:
There is no particular limitation, and examples thereof include heat removal, removal under reduced pressure, and removal by natural drying. The organic solvent and / or water from the paste upon substantially removed, on an aluminum material, although the film made of the brazing filler metal powder and a binder resin is formed, the weight per the coating 1 m ² is a 10~100g Is preferred. The heating temperature at the time of curing the brazing paste is such that the functional group (b) in the crosslinking agent (B) can react with the active hydrogen in the active hydrogen-containing group (a) of the polymer (A). The temperature may be higher than or equal to 80 ° C.
° C, preferably 100 to 200 ° C.

Using the brazing paste of the present invention,
Aluminum material, ie, a material made of an aluminum alloy, is brazed. The coating formed when the organic solvent and / or water is substantially removed from the brazing paste has good adhesion and adhesion to the aluminum material, the coating has a uniform thickness, and the coating is peeled off. In order to prevent the occurrence of local unattached parts (parts not brazed) after brazing due to unevenness or unevenness (variation) in the thickness of the coating, the surface of the aluminum material has irregularities of about 10 to 60 μm. It is desirable to have

The material of the aluminum alloy may be any material that can be brazed and that is compatible with the functions, uses, purposes, and the like required for products and parts made of the aluminum alloy. For example, in the case of an extruded tube, the material of the aluminum alloy constituting the tube may be one having good extrudability, and in the case of a heat exchanger, the material of the aluminum alloy constituting the heat exchanger Should have good corrosion resistance and the like.

[0028]

EXAMPLES Next, examples of the present invention will be described in detail in comparison with comparative examples, but the present invention is not limited to these examples.

<Production Example 1> 500 parts of methyl ethyl ketone was put into a four-necked colben equipped with a reflux condenser and stirred at 75 ° C. (item “Reaction temperature” in column “A-1” in Table 1). ) And maintained at this temperature. Next, the following reactive monomers (monomers) were selected as constituents of the unsaturated polymerizable polymer (A), and among these monomers, NBM and HEM were identified as “A” in Table 1. -1 "in the column of" Composition ", and
000 parts, 5 parts of 2,2-azobis (2-amidipropane) hydrochloride (hereinafter AHC) as a polymerization initiator (refer to the item “AHC amount” in the column “A-1” in Table 1),
500 parts of toluene were mixed to obtain a mixed solution. This mixed solution was dropped into the above-mentioned Kolben over 3 hours, stirred for 5 hours under the same conditions, added with 0.1 part of AHC, and further stirred for 3 hours. Next, methyl ethyl ketone was removed from the inside of the kolben under reduced pressure to obtain a polymer (A-1).

Next, as shown in the columns "A-2" to "A-5" in Table 1 and "B-1" and "B-2" in Table 2,
The same operation as described above was performed by changing only the type and the mixing ratio of the reactive monomer, the reaction temperature, and the mixing amount of the AHC (polymerization initiator), and the polymer (A-2 to A-5) and And a crosslinking agent (B-1, B-2).

[Reactive monomer] NBM: normal butyl methacrylate IBM: isobutyl methacrylate HEM: 2-hydroxyethyl methacrylate PPM: polypropylene glycol monomethacrylate [Blenmer PP500 manufactured by NOF Corporation] AMI: 1,1-dimethyl-1 -(2-Hydroxypropyl) amine methacrylamide [Imid-100 manufactured by Inui Corporation] MOA: Methylol acrylamide

[0032]

[Table 1]

[0033]

[Table 2]

<Production Example 2> 260 parts of methyl ethyl ketone oxime, 740 parts of isophorone diisocyanurate and 500 parts of methyl ethyl ketone were placed in a four-necked corben equipped with a reflux condenser, and heated to 60 ° C. with stirring. After stirring under the same conditions for 10 hours, methyl ethyl ketone and excess methyl ethyl ketone oxime were removed from the inside of the kolben under reduced pressure to obtain a crosslinking agent (B-3).

Example 1 An aluminum cylindrical billet specified by JIS A1050 was extruded into a multi-hole flat tube (height 1.8 mm, width 16 mm, 19 holes).
The surface was blasted to obtain a tube. next,
As shown in the column of "Example 1" in Table 3 below, the polymer (A) and the crosslinking agent (B) constituting the binder resin
As the components, the polymer (A-1) and the crosslinking agent (B-1) were selected, and the equivalent ratio (value of equivalent ratio) of the active hydrogen-containing group (a) and the functional group (b) was selected. 1.0 / 1.0
So that the polymer (A-1) and the crosslinking agent (B
-1) was blended, and a binder resin was produced without using a catalyst.

An Al-25Si-15Zn alloy powder having an average particle diameter of 40 μm, which is a brazing filler metal powder, and toluene, which is an organic solvent, were blended with the binder resin to prepare a brazing paste. The weight ratio of the aluminum alloy powder, binder resin, and toluene in the paste was 40:
6:54. After the tube was immersed in the paste and the paste was adhered to the tube, a heat treatment at 150 ° C. was performed for 5 minutes (see the item of “heating time” in the column of “Example 1” in Table 3). Then, toluene was substantially removed from the paste on the tube, and a film composed of the alloy powder of the paste and the binder resin was formed on the tube.
The weight per 1 m ^{2 of} the coating was 30 g.

<Embodiments 2 to 10> Next, Embodiment 2 in Table 3
As shown in the columns of Example 10 to Example 10, only the polymer (A) component, the crosslinking agent (B) component, and the heating time were changed, and the treatment was performed under the same conditions as in Example 1. Ten brazing pastes and the tubes of Examples 2 to 10 in which a coating of the paste was formed were obtained.

Example 11 The polymer (A-) was prepared such that the equivalent ratio (value of equivalent ratio) between the active hydrogen-containing group (a) and the functional group (b) was 0.8 / 1.2. 1) and a crosslinking agent (B-
A treatment was performed under the same conditions as in Example 9 except that 1) was blended (see the column of Example 11 in Table 3) to obtain a brazing paste and a tube on which a film of the paste was formed.

Example 12 The polymer (A-) was prepared so that the equivalent ratio (value of equivalent ratio) between the active hydrogen-containing group (a) and the functional group (b) became 1.2 / 0.8. 1) and a crosslinking agent (B-
A treatment was performed under the same conditions as in Example 9 except that 1) was blended (see the column of Example 12 in Table 3) to obtain a brazing paste and a tube on which a film of the paste was formed.

Example 13 A process was performed under the same conditions as in Example 9 except that 0.5 wt% of dibutyl phosphate was used as a catalyst during the production of the binder resin and that the heating time was set to 1 minute. (See the column of Example 13 in Table 3) to obtain a brazing paste and a tube on which a film of the paste was formed.

<Comparative Examples 1 to 5> As shown in Comparative Examples 1 to 5 in Table 3, the binder resin was prepared from the polymer (A-1)
To (A-4), except that the heating time was set to 1 minute, the same conditions as in Example 1 were applied, and the brazing pastes of Comparative Examples 1 to 5 were used. Tubes of Comparative Examples 1 to 5 on which a film of the paste was formed were obtained.

<Comparative Example 6> As shown in Comparative Example 6 in Table 3, Example 9 was repeated except that the binder resin was composed of the polymer (A-1) and the crosslinking agent (B-4). Under the same conditions as above, to obtain a brazing paste and a tube on which a film of the paste was formed. The crosslinking agent (B-
As 4), an isophorone diisocyanate nurate was used.

Next, the brazing pastes and tubes of the above Examples and Comparative Examples were as shown below.
Each test of brazing property, solvent resistance and storage stability was performed.
Table 3 shows the results.

<Test method> (1) Brazing properties The tube was cut out to 60 mm. Next, corrugated Al-0.5Si having a thickness of 0.07 mm
A mini core was prepared by combining 20 waves of a -1Fe-0.5Ni-2Zn alloy fin (one wave is composed of peaks and valleys) and the cut-out tube. After applying a fluorine-based flux to the core, under a nitrogen atmosphere, the core is heated at a temperature of 600 ° C. for 3 minutes to volatilize the binder resin from the coating of the alloy powder and the binder resin on the tube, The fin and the tube were brazed at 20 locations (ie, the ridges of the fin projecting toward the tube side of each wave). After that, the number of completely joined (brazed) portions out of the above 20 brazed portions is counted, and (the number of completely joined (brazed) portions) / 20 is defined as a fin joining ratio. ,evaluated. A sample having a fin joining ratio of 95% or more was evaluated as ○, and a sample having a fin bonding ratio of less than 95% was evaluated as ×.

(2) Solvent resistance After the tube was immersed in toluene at a temperature of 30 ° C. for 10 minutes to perform an “immersion test” to observe the elution state of the film on the tube, the tube was taken out of the toluene. In a state where toluene remained on the tube surface, a “peeling test” in which the tube was rubbed with gauze was performed, and the state of peeling of the coating film was observed. When no peeling of the film was observed even after the peeling test, ◎, when the film did not elute in the immersion test, but when the film partially peeled in the peeling test, ○, and when the film partially leached in the immersion test , And those in which the coating was completely eluted in the immersion test were rated as ×.

(3) Storage stability The brazing paste was stored at a temperature of 45 ° C., and the number of days until the paste became unusable was determined.

[0047]

[Table 3]

As can be seen from Table 3, all the test results are good in the example, but any test result is bad in the comparative example.

[0049]

As described above, according to the present invention,
By forming the binder resin from a high molecular polymer having an active hydrogen-containing group and a crosslinking agent having a functional group capable of reacting with active hydrogen by heating, solvent resistance and storage can be achieved without impairing brazing properties. Stability can be improved, and thereby, the handling of the brazing paste during manufacture and storage of the heat exchanger manufacturer can be extremely facilitated, and a remarkable industrial effect can be achieved.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor, Takenori Tsuchiki 500, Kiyotaki-cho, Nikko-shi, Tochigi Furukawa Electric Co., Ltd. Nikko Works (72) Inventor Yoshihisa Ota 1-11, Hitotsubashi Nohonmachi, Higashiyama-ku, Kyoto-shi Inside Sanyo Chemical Industries Co., Ltd. (72) Inventor Tomoji Nakano 1 at 11-11 Hitotsubashi Honcho, Higashiyama-ku, Kyoto City Inside Sanyo Chemical Industries Ltd.

Claims (5)

[Claims] An aluminum material brazing paste comprising: a brazing material powder for brazing an aluminum material; a binder resin; an organic solvent and / or water; wherein the binder resin comprises an active hydrogen-containing group (a). (A) and a cross-linking agent (B) having a functional group (b) capable of reacting with active hydrogen by heating. 2. A high molecular weight polymer (A) comprising an ethylenically unsaturated monomer having an active hydrogen-containing group (a) and an alkyl (meth) acrylate monomer as essential constituent monomers. The paste for brazing aluminum material according to claim 1, wherein the paste is a molecular copolymer. 3. The aluminum material brazing according to claim 1, wherein the active hydrogen-containing group (a) is at least one functional group selected from the group consisting of a hydroxyl group, a carboxyl group, an amino group and a mercapto group. For paste. 4. The functional group (b) is at least one functional group selected from the group consisting of an amine imide group, a hydroxyalkylamide group, an alkoxyalkylamide group, a blocked isocyanate group and a blocked epoxy group. 4. The paste for brazing an aluminum material according to any one of items 1 to 3. 5. The paste for brazing an aluminum material according to claim 1, wherein the aluminum brazing paste is coated with a coating comprising a brazing filler metal powder and a binder resin, and the weight per 1 m ^{2 of} the coating is 10 to 100 g. Aluminum material.