JPH1112554A - Adhesive for metal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an adhesive for metal capable of manifesting excellent rust preventing functions and maintaining a high bonding power for a long period. SOLUTION: This adhesive for metal for mutually joining aluminum consists essentially of a one part epoxy thermosetting type adhesive such as a bisphenol type epoxy resin containing a latent curing agent and further contains a particulate ABS resin compounded therewith. The adhesive is coated, temporarily bonded, then heated and cured. Since the particulate ABS resin is compounded in the adhesive, the resin is melted by heat when heated. Thereby, the viscosity of the adhesive is temporarily reduced to improve the wettability for the metallic surface. As a result, water, etc., are hardly admitted into the interface between the adhesive after curing and the metallic surface to suppress the corrosion.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal adhesive, and more particularly, to a metal adhesive which is interposed between opposing metal surfaces so as to join the metal surfaces to each other, and then cured by heating. It relates to an adhesive.

[0002]

2. Description of the Related Art In recent years, in large passenger vehicles such as buses and trucks, from the viewpoints of improving fuel efficiency and securing load capacity,
There is a strong demand for lighter vehicles. As a means of reducing the weight, replacement of a steel sheet material with a material having a relatively low specific gravity, such as resin or aluminum, is being studied.

[0003] For example, it is effective to reduce the weight of an outer panel of a large passenger car, which has conventionally been formed of a steel plate, of aluminum (or an alloy thereof). By the way, conventionally, when steel outer panel is joined to each other or when a steel outer panel is joined to a steel frame material, welding is mainly employed. However, when the aluminum outer panel is joined to each other, or when the aluminum outer panel is joined to the steel frame material, the following problem occurs when the same welding process as the related art is employed. That is, when aluminum is welded, welding marks and thermal distortion are likely to occur. Therefore, in the case where a final product is to be finished, a finishing process of repairing the welding trace and the thermal distortion is required. As a result, the number of processing steps is significantly increased.

[0004] On the other hand, it is conceivable that bonding is performed using an adhesive instead of the above-mentioned welding. In other words, when joining aluminum outer panels, or
In the case where an aluminum outer panel is joined to a steel frame material, if both can be firmly joined with an adhesive, the weight of the vehicle can be reduced and the number of processing steps can be reduced.

[0005]

However, in adopting an adhesive method in which metals are bonded to each other using an adhesive, it is important to ensure reliability over a long period of use, and particularly to ensure a rustproof function. It is becoming. This is because there is a possibility that corrosion of the metal is promoted due to long-term use or that a snow-melting agent such as calcium chloride adheres to the metal, and the durability is reduced.

Various techniques have been disclosed as techniques for preventing such metal corrosion (for example, Japanese Patent Application Laid-Open Nos. 60-20688 and 62-53387). However, in these techniques, depending on the conditions, a local battery is formed, and the rust prevention function is rather deteriorated. In addition, all of these technologies relate to an adhesive for a steel material, and in fact, no technology has been proposed for aluminum.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a method for joining metal surfaces by interposing the metal surfaces between the opposed metal surfaces and then heating the metal surfaces. It is an object of the present invention to provide a metal adhesive which exhibits an excellent rust prevention function and can maintain a high bonding strength for a long period of time.

[0008]

In order to achieve the above object, according to the first aspect of the present invention, in order to join the surfaces of the metals, they are interposed between the surfaces of the opposing metals and then heated. The gist is that a fine-grain component made of a thermoplastic resin material is blended with a one-part epoxy thermosetting adhesive containing a latent curing agent, which is a hardening metal adhesive.

According to the present invention, the adhesive is interposed between the surfaces of the opposing metals and then heated. The adhesive is cured by this heating, and at this time, the fine particle component made of the thermoplastic resin material is melted by heat. Therefore, the viscosity of the adhesive temporarily decreases, and the "wetability" of the metal surface is improved. Therefore, water and the like do not easily enter the interface between the cured adhesive and the metal surface, and corrosion is suppressed.

Further, in the invention according to claim 2, in the metal adhesive according to claim 1, the one-part epoxy thermosetting adhesive is a bisphenol-type epoxy resin, a glycol-modified epoxy resin, and a dimer. The gist of the invention is that it contains at least one component of an acid-modified epoxy resin.

According to the present invention, in addition to the effect of the first aspect of the present invention, the viscosity when applied to a metal surface is relatively low due to the inclusion of the above components. For this reason, the falling-off and peeling of the adhesive after the application of the adhesive is suppressed.

Further, in the invention according to claim 3, in the metal adhesive according to claim 1 or 2, the one-part epoxy thermosetting adhesive contains a rubber-modified epoxy resin. This is the gist.

According to the present invention, in addition to the effects of the first and second aspects of the present invention, the flexibility of the adhesive after thermosetting is ensured by the inclusion of the rubber-modified epoxy resin. Therefore, the peel strength of the adhesive is improved.

In addition, according to the invention described in claim 4, in the metal adhesive according to any one of claims 1 to 3,
The gist of the one-component epoxy thermosetting adhesive is that it contains an epoxy resin component in a solid state at room temperature.

According to the present invention, the solid epoxy resin component is further melted by heat when heated. for that reason,
The viscosity of the adhesive is temporarily reduced, and the effect of the invention described in claim 1 is more reliably achieved.

According to a fifth aspect of the present invention, in the metal adhesive according to any one of the first to fourth aspects, at least one of the metals is aluminum or an aluminum alloy. I have.

According to the present invention, in addition to the effects of the above-mentioned first to fourth aspects, the weight of the product after bonding can be reduced, and the number of processing steps can be reduced because welding can be omitted. Reduction is achieved.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below. (Example 1 and Comparative Examples 1 to 4) First, adhesive samples of Example 1 and Comparative Examples 1 to 4 were prepared. The mixing ratio is as shown in Table 1 below.

[0019]

[Table 1] Each numerical value in the above Table 1 indicates a blending ratio (parts by weight). The epoxy resin A is a bisphenol A type epoxy resin (average molecular weight 380; liquid at ordinary temperature), the epoxy resin B is a bisphenol A type epoxy resin (average molecular weight 1000; solid at ordinary temperature), and the epoxy resin C
Is a bisphenol F type epoxy resin (average molecular weight 35
2), and epoxy resin D is a glycol-modified epoxy resin (trade name: DER73 manufactured by Dow Chemical Co., Ltd.)
2), epoxy resin E is a dimer acid-modified epoxy resin (product name: Epicoat 872 manufactured by Yuka Shell Epoxy Co., Ltd.), and epoxy resin F is a rubber-modified epoxy resin (product of Dainippon Ink Industries, Ltd.) Name: Epicron TSR-601).

In addition, the ABS resin component is an ABS resin component.
A resin (paste) in which 15 parts by weight of a resin (trade name: Blendex, manufactured by BorgWarner Chemicals) is dispersed at 120 ° C. in 100 parts by weight of the epoxy resin A is shown.

Incidentally, dicyandiamide and imidazole are solid at room temperature and employed as a latent curing agent.
Further, silica was used to prevent the adhesive from dripping during coating.

First, the adhesive of the first embodiment is characterized in that a particulate ABS resin is blended. Secondly, the adhesive of Example 1 is mainly composed of a one-component epoxy thermosetting adhesive (epoxy resins A, B, D, E, F). In particular, the adhesive of Example 1 contains a bisphenol-type epoxy resin, a glycol-modified epoxy resin, and a dimer-acid-modified epoxy resin.
The adhesive of Example 1 contains a rubber-modified epoxy resin, and further contains an epoxy resin component which is solid at room temperature.

In Comparative Example 4, conventional spot welding is employed. (Confirmation Experiment) A test piece was prepared using the adhesives of Example 1 and Comparative Examples 1 to 4. As the test piece, two plates made of 5052 material, which has a high track record of use, from 5000 series (Al-Mg series), which have sufficient strength and are excellent in press formability, for automobile outer panels, were used in the above Examples. The adhesive samples of Example 1 and Comparative Examples 1 to 3 were temporarily joined and then heated at a high temperature of 170 ° C. (JIS K6850). In Comparative Example 4,
A test piece obtained by joining the two plates by spot welding was used. Each of the test pieces was subjected to a composite corrosion test (CCT). In CCT, salt spray (35 ° C., 5% NaCl aqueous solution × 4 hours) →
Dry (60 ° C x 2 hours) → wet (50 ° C, RH 95% x
4 hours) → drying (60 ° C. × 2 hours) was defined as one cycle.

First, a tensile shear strength test (tensile speed: 5 mm / min) after CCT deterioration was performed. Table 2 shows the results. In the table, each numerical value in Example 1 and the like indicates a tensile shear strength (unit: kN / cm ² ).

[0025]

[Table 2] As shown in Table 2 above, the initial tensile shear strength is not so different between Example 1 and Comparative Examples 1 to 3, but after 400 CCT cycles, Comparative Examples 1 to 3 It can be seen that all of the test pieces have significantly reduced tensile shear strength. On the other hand, the test piece of Example 1 shows that the tensile shear strength hardly decreases even after passing through 400 CCT cycles. From this, it can be said that the adhesive of Example 1 has excellent corrosion resistance (rust prevention). This is the glue
After application and temporary bonding, the adhesive is heated and cured in an electrodeposition drying oven or the like. At this time, the adhesive of Example 1 contains a particulate ABS resin, and the resin is melted by heat. Is done. Therefore, the viscosity of the adhesive temporarily decreases, and the "wetability" of the metal surface is improved. Therefore, it is considered that water and the like hardly enter the interface between the cured adhesive and the metal surface, thereby suppressing corrosion.

Next, for each sample of Example 1, Comparative Example 3 and Comparative Example 4 at the initial stage and after the CCT deterioration, a repeated durability test (frequency: 30 Hz, stress ratio:
Test to give vibration at 0.1). The number of times until breaking with respect to the applied load at that time was evaluated. Table 3 shows the results.

[0027]

[Table 3] As shown in Table 3 above, the adhesive of Example 1 has excellent durability both at the initial stage and after 400 cycles of CCT.

The adhesive of Example 1 has the following functions and effects in addition to the above functions and effects. That is, since the adhesive of Example 1 contains a bisphenol-type epoxy resin, a glycol-modified epoxy resin, and a dimer-acid-modified epoxy resin, the viscosity when the adhesive is applied to the metal surface is compared. Target lower. For this reason, it is possible to suppress the adhesive from falling off and peeling after the application of the adhesive.

The adhesive of Example 1 contains a rubber-modified epoxy resin, which ensures the flexibility of the adhesive after thermosetting. For this reason, the peel strength of the adhesive can be improved.

Further, the adhesive of Example 1 contains an epoxy resin component which is solid at room temperature. Therefore, the solid epoxy resin component is melted by heat at the time of heating.
For this reason, the viscosity of the adhesive is temporarily reduced in combination with the action of the ABS resin, so that the "wettability" can be drastically improved. As a result, it becomes difficult for water or the like to enter the interface between the cured adhesive and the metal surface, so that corrosion (generation of rust) can be suppressed.

At the same time, the adhesive of Example 1 contains a latent curing agent. For this reason, the viscosity at the time of being applied to the metal surface becomes relatively low, and as in the above, it is possible to suppress the adhesive from dropping and peeling after the adhesive is applied.
After the heating, the curing of the adhesive can be further promoted.

In addition, when the adhesive as in Embodiment 1 is used for bonding aluminum or aluminum alloy, the weight of the product after bonding can be reduced. In addition, the number of processing steps can be reduced because welding processing need not be employed.

It should be noted that the present invention is not limited to the above-described embodiment, and may be implemented as follows, with a part of the configuration being appropriately changed without departing from the spirit of the invention. (1) In the above-described embodiment, only the adhesive shown in Example 1 is given as a specific adhesive. However, basically, a one-part epoxy thermosetting adhesive is compared with fine particles made of a thermoplastic resin material. It may have any configuration as long as the components are blended.

For example, any one of the epoxy resins A to F of the one-component epoxy thermosetting adhesive may be omitted, or the mixing ratio may be appropriately changed. Also, the thermoplastic resin material is not limited to ABS, and any material having a hot-melt property, such as vinyl chloride, vinyl acetate, polystyrene, and polyethylene, can be used.

(2) In the above embodiment, the present invention has been embodied in the case where aluminum is joined to each other. However, the present invention can be applied to the case where any metal is joined, for example, the joining between aluminum and steel, the joining between iron and the like. You.

[0036]

As described in detail above, according to the present invention,
In order to join the metal surfaces, the metal adhesive that is interposed between the opposing metal surfaces and then cured by heating can exhibit excellent rust-prevention function and achieve high bonding strength for a long time. It has an unprecedented superior effect that it can be maintained.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Akira Mabuchi 1 Ochiai, Nagahata, Kasuga-cho, Nishi-Kasugai-gun, Aichi Prefecture Toyota Gosei Co., Ltd. (72) Inventor Takahiro Onishi 3-1-1, Hinodai, Hino-shi, Tokyo Hino, Tokyo (72) Inventor Nobuyuki Hamano 3-1-1, Hinodai, Hino-shi, Tokyo Inside Hino Automotive Industry Co., Ltd.

Claims (5)

[Claims] 1. An adhesive for a metal which is interposed between the surfaces of opposing metals so as to join the surfaces of the metals, and is then cured by being heated, comprising a latent curing agent. An adhesive for metals, wherein a fine-grained component made of a thermoplastic resin material is mixed with a liquid epoxy thermosetting adhesive. 2. The one-part epoxy thermosetting adhesive comprises at least one component of a bisphenol-type epoxy resin, a glycol-modified epoxy resin, and a dimer-acid-modified epoxy resin. 2. The metal adhesive according to 1. 3. The metal adhesive according to claim 1, wherein the one-part epoxy thermosetting adhesive contains a rubber-modified epoxy resin. 4. The metal adhesive according to claim 1, wherein the one-part epoxy thermosetting adhesive contains an epoxy resin component in a solid state at room temperature. 5. The metal adhesive according to claim 1, wherein at least one of the metals is aluminum or an aluminum alloy.