JPH11123588A - Binder for brazing aluminum - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the adverse effect to brazing so as not to develop the detachment and the crack at the time of working to a base material and also, the blocking between the base materials by using binder consisting essentially of esters methacrylate polymer having a specific value or higher of acid value. SOLUTION: In a reaction device provided with a stirring device, cooling pipe, dripping funnel and nitrogen introducing pipe, e.g. after preparing 70 wt.% isopropyl alcohol as solvent, the temp. in the system under gaseous nitrogen flow is raised to e.g. 80 deg.C. Successively, solution composed of each monomer and polimerization initiator of 27 wt.% 2-ethyl hexyl methacrylate, 3 wt.% 2-hydroxyethyl methacrylate and 2.5 wt.% methacrylic acid as the monomer composition and 0.9 wt.% benzoil peroxide as the polymerization initiator, is dripped into the system, e.g. for about 3 hr. Further, the polimerizing reaction is completed by keeping to the same temp. for 1-10 hr to obtain the binder for brazing an aluminum. In such a case, the acid value is made to >=50.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a binder used for applying a flux or a mixture of a flux and a brazing material to a brazing portion for use in brazing aluminum or an aluminum alloy. .

[0002]

2. Description of the Related Art Conventionally, when brazing aluminum or an aluminum alloy, it is necessary to apply a brazing flux or a mixture of a flux and a brazing material to a brazing portion. And the like have been mixed and applied to a binder.

As a binder for this purpose, a conventional thermoplastic acrylic or methacrylic resin has been used. And these binders, flux or a mixture of flux and brazing material, dissolved in alcohol to brazing composition, the brazing composition,
It has been applied to a brazing point in an aluminum or aluminum alloy base material.

[0004]

However, before the brazing is carried out, it is general that the base material is subjected to various processes such as press working for bending thickness and bending and tension. When the brazing composition is applied to the base material, the brazing composition may fall off from the base material during these processes,
In many cases, cracks are generated on the surface or blocking occurs between the base materials, which has a problem of adversely affecting brazing.

The present invention has been made in view of the above circumstances, and has as its object to provide a binder which does not cause these problems and can perform good brazing.

[0006]

Means for Solving the Problems The present invention is characterized in that a methacrylate polymer having an acid value of 50 or more is mainly used.

In the present invention, the methacrylic acid ester-based polymer comprises at least one of the monomers represented by the following chemical formula 6, acrylic acid, methacrylic acid, It is suitable that the copolymer is a copolymer containing the monomer such as an acid, maleic acid, and itaconic acid and at least one component of a copolymerizable monomer having a carboxyl group.

[0008]

Embedded image CH ₂ ＣC (CH ₃ ) COOR (where R is an alkyl group having 4 to 12 carbon atoms)

Further, as the methacrylic acid ester-based polymer, a monomer component constituting the polymer is
And at least one component of a monomer containing a carboxyl group copolymerizable with the monomer such as acrylic acid, methacrylic acid, maleic acid, and itaconic acid; And a copolymer containing at least one of the following monomers represented by Chemical Formulas 7, 8 and 9:

[0010]

Embedded image CH ₂ ＣC (CH ₃ ) COO (CH ₂ ) _n OH (where n is an integer of 2 or more and 4 or less)

[0011]

Embedded image CH ₂ ＣC (CH ₃ ) COO (C ₂ H ₄ O) _n OH (wherein n is an integer of 2 or more and 12 or less)

[0012]

Embedded image CH ₂ ＣC (CH ₃ ) COO (C ₃ H ₆ O) _n OH (where n is an integer of 2 or more and 12 or less)

In the binder of the present invention, a water-soluble binder in which the carboxyl group in the polymer is saponified with an amino alcohol represented by the following chemical formula 10 can be used.

[0014]

Embedded image

Further, depending on the case, not limited to amino alcohols, it is also possible to use those saponified with a compound having cationic properties in an aqueous solution, such as ammonia, diethylamine or triethylamine.

The binder of the present invention is preferably prepared by dissolving the above polymer in water or alcohol.

The binder of the present invention contains a methacrylate polymer as a main component. In developing a new binder for applying aluminum brazing flux, we studied the suitability of various chemical substances as the binder for applying the brazing flux.As a result, thermoplastic acrylic or methacrylic resins were suitable as binders. It turned out that.

However, when the suitability of various acrylic or methacrylic resins was further examined,
Particularly in brazing under a nitrogen atmosphere, in the case of a polymer containing only acrylic acid or an acrylic acid derivative as a monomer,
The binder carbonizes to form carbide residues and often causes poor brazing.

Generally, acrylic or methacrylic polymers are often treated as substantially equivalent to acrylic acid derivatives and methacrylic acid derivatives as constituent monomer components. Is required to be a methacrylate polymer, and an acrylate polymer cannot be used in place of the methacrylate polymer.

The methacrylic acid ester monomer in the present invention is an ester of methacrylic acid and a monohydric alcohol, and the alcohol has 4 to 12 carbon atoms. When composed of a single monomer, the glass transition temperature tends to be high when the number of carbon atoms is small, so that it is preferably about 6 or more, but when a plurality of monomers are used in combination, Esters of alcohols with lower carbon numbers can also be used.

The acid value of the polymer which is the main component of the binder of the present invention is determined by copolymerizing a monomer containing a copolymerizable carboxyl group such as acrylic acid, methacrylic acid, maleic acid or itaconic acid with the methacrylic acid ester described above. It needs to be 50 or more by copolymerization with the system monomer.

If the acid value of the methacrylic acid ester-based polymer of the binder of the present invention is low, the adhesion between the welding base material and the brazing composition is reduced, and hydrocarbon-based organic materials such as cutting oil and press working oil are used. When the solvent comes in contact, the brazing material may fall off.

The addition of a methacrylic acid ester-based polymer as a binder of the present invention having a hydroxyl group as a monomer constituting the binder further improves the adhesion between the welding base material and the brazing composition. Can be done.
Examples of the monomer having a hydroxyl group include the chemical formulas (7), (8) and (9).
Is preferably represented by

The methacrylic acid ester polymer in the present invention is obtained by radical polymerization by a known polymerization method such as bulk polymerization, solution polymerization and suspension polymerization.
Preferably, various polymers can be obtained by a solution polymerization method using alcohol as a solvent.

[0025]

The binder of the present invention mixes the methacrylate polymer with a mixture of a brazing filler metal such as silicon and a flux such as potassium fluoride aluminate with a solvent such as isopropyl alcohol. This mixture is then applied to an aluminum brazing material and dried,
The brazing is performed by heating to about 600 ° C. in a nitrogen atmosphere.

In the binder of the present invention, at a temperature considerably lower than the brazing furnace temperature of 600 ° C. in a nitrogen atmosphere, the polymer instantaneously depolymerizes and becomes a volatile monomer. Sometimes, the binder disappears, and the binder does not remain at the brazing portion or the carbide does not remain.

[0027]

According to the present invention, in brazing aluminum, there is no occurrence of peeling or cracking during processing of the base material, and the brazing material can be brought into contact with a hydrocarbon-based organic solvent such as cutting oil or pressing oil. Since there is no dropout and no blocking between the base materials occurs, there is no adverse effect on brazing.

[0028]

The present invention will be described in more detail with reference to the following Examples and Comparative Examples, but the present invention is not limited to these Examples. In each example, all parts and percentages are by weight unless otherwise specified.

[Production Examples 1 to 8] As shown in Table 1, each solvent was charged into a reactor equipped with a stirrer, a cooling pipe, a dropping funnel and a nitrogen introduction pipe, and then the system temperature was reduced under a nitrogen stream. 8
The temperature was raised to 0 ° C. Next, a solution composed of each monomer and each polymerization initiator was dropped into the system over about 3 hours, and the temperature was kept at the same temperature for 1 to 10 hours to complete the polymerization reaction.

[0030]

[Table 1]

[Examples and Comparative Examples] 10 parts (in terms of solid content) of the polymer obtained in the production example and 90 parts of a mixture of a silicon brazing material and a potassium aluminate flux were mixed. Isopropyl alcohol as a diluting solvent was added thereto and dissolved so that the solid content became 50% to obtain a solution.

The above solution was applied to an aluminum alloy tube material containing 0.4% of copper and 0.15% of manganese using a bar coater so that the solid coating amount was 12 ± 3 g / m ² , Dried in a gear oven at about 5 minutes. An evaluation test was performed using the obtained aluminum material.

[Evaluation Test] The aluminum materials obtained in Examples and Comparative Examples were evaluated by the following test methods. Table 2 shows the evaluation test results.

(Adhesion): The exfoliated state of the brazing composition when the obtained aluminum material was exposed to running water for 1 minute was observed. ；: Not dropped off △: slightly dropped ×: all dropped

(Peeling resistance): The falling state of the brazing composition when the obtained aluminum material was dropped on concrete from a height of 30 cm was observed. ；: Not dropped off △: slightly dropped ×: all dropped

(Blocking resistance): The coated surfaces of the obtained aluminum materials were adhered to each other at a pressure of 100 kg / cm ² for 1 minute, and immediately after peeling, the surface states of the mutually applied surfaces were observed. ○: Same as the initial state ×: Different from the initial state

(Solvent resistance): The obtained aluminum material was immersed in hexane for 8 hours, and then exposed to running water for 1 minute.
The weight after drying for 1 hour in a gear oven at 0 ° C. was measured, and the change from the initial weight was calculated. ；: Reduction of less than 30% from initial weight Δ: reduction of 30% or more and less than 70% from initial weight ×: reduction of 70% or more from initial weight

(Decomposition under nitrogen gas): About 10 mg (in terms of solid content) of only the polymer obtained in Production Examples 1 to 6 was inserted into an aluminum cup having a diameter of 5 mm and a height of 5 mm, and the mixture was placed under a nitrogen gas atmosphere. After the temperature was raised from room temperature to 600 ° C. over about 30 minutes, the residue in the aluminum cup was observed. ；: No residue △: very small amount of carbide residue ×; large amount of carbide residue

(Brazing A method): A fin made of an aluminum alloy containing 1.2% of manganese, 0.15% of copper and 2.5% of zinc was combined with the obtained aluminum material, and the mixture was placed in a nitrogen gas atmosphere. And a state of fillet at the joint was observed. ；: Good fillet △: small fillet ×: no fillet formed

(Brazing property B method): 15 parts (solid content) of the polymer obtained in the production example and 85 parts of a potassium aluminate flux were mixed, and isopropyl alcohol was added thereto as a diluting solvent. The solution was added and dissolved to a solid content of 50% to obtain a solution.

The above solution was applied to an aluminum alloy tube material containing 0.4% of copper and 0.15% of manganese using a bar coater so that the solid coating amount was 3 ± 1 g / m ² , and then 200%. Dried in a gear oven at about 5 minutes.

The obtained aluminum material was combined with a fin composed of a brazing sheet in which a silicon-aluminum alloy was clad on an aluminum alloy containing 1.2% of manganese, 0.15% of copper and 2.5% of zinc. A brazing test was performed in an atmosphere, and the state of the fillet at the joint was observed. ；: Good fillet △: small fillet ×: no fillet formed

[0043]

[Table 2]

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Satoshi Nohira 1-1-1, Showa-cho, Kariya-shi, Aichi Prefecture Inside Denso Co., Ltd. (72) Inventor Hiroshi Ikeda 3-1-1-12, Sennen, Minato-ku, Nagoya-shi, Aichi Prefecture Sumitomo Within Light Metal Industry Co., Ltd. (72) Inventor Hikaru Shibata 671, Mizuhashi, Noguchi-cho, Kakogawa City, Hyogo Prefecture Inside (72) Inventor Ichiro Yanaka 4, 671 Mizuhashi, Noguchi-cho, Kakogawa City, Hyogo Prefecture Inside the corporation

Claims (4)

[Claims] 1. A binder for aluminum brazing, comprising a methacrylate polymer having an acid value of 50 or more as a main component. 2. The methacrylic acid ester-based polymer,
As a monomer component constituting the polymer, at least one component of a monomer represented by the following chemical formula 1 and one component of a monomer containing a carboxyl group copolymerizable with the monomer characterized in that it is a copolymer containing more than, for aluminum brazing binder embedded image according to claim _{1 CH 2 = C (CH 3} ) COOR ( wherein, R 4 to 12 carbon atoms Is an alkyl group of 3. The methacrylic acid ester-based polymer,
As a monomer component constituting the polymer, at least one component of the monomer represented by the above formula 1 and at least one component of a monomer containing a carboxyl group copolymerizable with the monomer. 2. The binder for aluminum brazing according to claim 1, wherein the copolymer is a copolymer containing at least one of the following monomers represented by the following chemical formulas (2), (3) and (4). CH ₂ ＣC (CH ₃ ) COO (CH ₂ ) _n OH (wherein n is an integer of 2 or more and 4 or less) CH ₂ ＣC (CH ₃ ) COO (C ₂ H ₄ O) _n OH (where n is an integer of 2 or more and 12 or less) CH ₂ ＣC (CH ₃ ) COO (C ₃ H ₆ O) _n OH (where n is 2 Is an integer not less than 12 and not more than 12) 4. The carboxyl group in the polymer according to claim 2 or 3, wherein the carboxyl group is saponified with an amino alcohol represented by the following formula 5, and is soluble in water.
Aluminum brazing binder