JP3477854B2 - Method for bonding pre-coated adhesive composition - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for bonding components which need to be bonded at the time of assembling mechanical, electric or electronic components .
Epoxy adhesive composition
And a method for bonding a precoat adhesive comprising: Examples of assembly parts to which the present invention can be applied include a magnet bonded to a yoke of a motor, a heat sink bonded to an IC chip or a CPU, packages for holding a printed circuit board itself, and exterior parts of an electric product. And a housing case. [0003] Conventionally, various small parts in the fields of machinery, electricity, and electronics which need to be bonded at the time of assembly (various small parts and their packages, etc. are hereinafter referred to as assembled parts or simply parts). It has been widely practiced to provide a pre-coat adhesive layer in (1). Conventionally, the method mainly performed is to apply a hot-melt adhesive by melting and applying the adhesive, cooling it into a pre-coated state, and reheating at the time of assembling. However, in this method, the heat resistance temperature of the adhesive member becomes the melting point of the adhesive, and high heat resistance cannot be expected. Therefore, a reactive material such as an epoxy resin is precoated by the following method. [0004] 1. A liquid epoxy resin containing a curing agent is applied, heated to a B stage, and rapidly cooled to a pre-coated state. 2. The solid epoxy resin containing the latent curing agent is heated to a temperature higher than the softening point of the epoxy resin and lower than the activation temperature of the latent curing agent, and cooled after application to obtain a pre-coated state. [0005] When the reactive material is pre-coated by the above-described method, there are the following problems. In the case of 1, the parts must be heated,
Heating and cooling required a long time and energy depending on the heat capacity of the parts. In addition, since it is stored in the B-stage state, long-term storage at room temperature cannot be performed. In the case of 2, the latent curing agent partially reacts because of the heating step in the coating step,
There was a problem with storage stability. [0006] It is an object of the present invention to overcome such disadvantages of the prior art. That is, excellent in storage stability after the precoated state, and bonding the bonding process during the assembling cold, precoat adhesive that can be performed in a short time
It is about the method. [0007] SUMMARY OF THE INVENTION The present invention comprises a second component of the epoxy composition to an epoxy resin and a powder curing agent as essential components, an isocyanate group, an alkoxysilane group, A
A compound having a functional group selected from a setoxysilane group and a ketoxime silane group and having a skeleton selected from a polyurethane skeleton, a polysiloxane skeleton, and a polyether skeleton, and polymerization initiation for reacting the compound with water in the air A step of preliminarily mixing and applying a first component consisting of an agent to the surface to be bonded, curing the first component by moisture in the air, and curing the first component in the cured coating film of the first component on the surface to be bonded. A step of precoating the epoxy composition with the second component remaining unreacted, and a step of heating and curing the second component by heating until the powdery curing agent in the second component is compatible with the epoxy resin. This is a method for bonding a pre-coated adhesive. In the present invention, the epoxy resin of the second component includes bisphenol A type epoxy resin,
Either liquid or solid epoxy resin can be used. As the powdery curing agent, a curing agent generally called a latent curing agent such as dicyandiamides, dibasic dihydrazides, imidazoles, imidazole / epoxy adducts, and boron trifluoride amine complex is used. . As the first component , a compound having a functional group that reacts with water in the air to polymerize can be used . Examples of the functional group, isocyanate group, alkoxysilane group, acetoxysilane group, also selected from ketoxime silane group
And than, polyurethane skeleton, a polysiloxane skeleton, a compound selected from polyether backbone can be used as the main chain skeleton. Further, an organotin such as dibutyltin laurate or a platinum catalyst may be added as a polymerization initiator. In the present invention, the ratio of the first component to the second component is usually 10 to 50%, preferably 20 to 50%.
40%. If the amount of the first component is small, it is difficult to perform pre-coating. If the amount of the first component is 50% or more, the adhesion of the second component may be reduced due to heating and curing of the second component. In the present invention, these components are mixed to form a precoatable composition. At this time, an elastomer component, a tackifier and the like may be added as necessary. Various fillers can be added. As the elastomer component, a homopolymer or a copolymer of two or more monomers selected from (meth) acrylates, (meth) acrylamides, vinyl monomers, etc., natural rubber, Butadiene rubber, butyl rubber, polyisoprene rubber, polyisobutylene rubber, styrene-butadiene rubber, styrene-isoprene-styrene block copolymer, and the like. Examples of the tackifier include a rosin resin, a terpene phenol resin, a terpene resin, a hydrocarbon-modified terpene resin, a petroleum resin, a cumarone / indene resin, a styrene resin, a phenol resin, and a xylene resin. As the filler, known fillers such as calcium carbonate and talc can be used. The liquid composition is applied to the surface to be bonded of the assembly component by an appropriate method such as screen printing, spray coating, tensil printing, brushing, and the like, and then left to cure by moisture in the atmosphere. One component is selectively cured, and the uncured second component is fixed in the cured coating film of the first component to form a precoat. The bonding between the assembly component precoated with the epoxy composition of the present invention and the adherend is performed by heating the assembly component until the cured coating of the first component softens, fluidizes, or liquefies. To make contact with the adherend. Next, heating is performed until the powdery curing agent in the second component is compatible with the epoxy resin, and the second component is heated and cured, so that the assembly component is bonded. Alternatively, the assembling component and the adherend may be temporarily fixed in advance, and in the temporarily fixed state, the powdered curing agent may be heated and adhered until it is compatible with the epoxy resin. The present invention will be described in detail below with reference to examples and comparative examples. The present invention is not limited to each of these examples. A precoat composition was prepared by using a planetary mixer with the composition (parts by weight) shown in Table 1. [Table 1] The components in Table 1 are as follows. Epicoat 828: bisphenol A type liquid epoxy resin (manufactured by Yuka Shell Epoxy), Epicoat 872: dimer acid-modified flexible liquid epoxy resin (manufactured by Yuka Shell Epoxy), Epicoat 1001: bisphenol A type solid epoxy resin (oil) Shellate Epoxy Co., Ltd.), Takenate A-439: Isocyanate group-containing polyurethane (Takeda Pharmaceutical Co., Ltd.), Novacure HX-3722: Epoxy resin latent curing agent (Asahi Kasei Corp.), Dicyandiamit: Epoxy resin latent curing agent, 2E4MZ: imidazole [epoxy resin curing accelerator]
(Shikoku Kasei Co., Ltd.), Hughe Rex E2: fused silica [filler] (Tatsumori Co., Ltd.), Adjustment of the precoat composition was carried out at room temperature in Example 1, and heated to 80 ° C. in Comparative Example 1. I went there. The above-mentioned precoat composition was applied to 1.6 × 25 ×
It was applied on a 100 (mm) mild steel plate by screen printing, and allowed to stand at room temperature for 3 days to be moisture-cured to obtain a precoated cured film layer having a thickness of about 0.3 mm. In Comparative Example 1, a coating film was obtained by coating on the above mild steel sheet while being heated to 80 ° C. and cooling to room temperature. [Adhesion Test Method] A mild steel sheet of the same kind is superimposed on a stet piece having a precoated adhesive layer obtained as described above, and pressed at 80 ° C. for 60 minutes with a clip.
Cured at 0 ° C x 30 minutes and 150 ° C x 30 minutes,
The shear bond strength according to JIS K 6850 was measured. Table 2 shows the results. [Table 2] From the results, it can be seen that the adhesive composition of the present invention has a low temperature,
Clearly, it can be cured in a short time. [Test Method for Storage Stability] The test piece having the pre-coated cured coating film obtained as described above was stored in a thermostat at 40 ° C., taken out after 7, 14, and 30 days, respectively. Was measured for shear bond strength. However, the curing conditions were 100 ° C. × 30 minutes for Example 1, and 150 ° C. for Comparative Example 1.
X 30 minutes. Table 3 shows the results. [Table 3] From the results, it is clear that the precoat adhesive layer of the present invention has excellent storage stability. As described above, the method for bonding a pre-coated adhesive according to the present invention not only allows the bonding step to be performed at a low temperature and in a short time, but also has excellent storage stability, so that it is practically useful. It is. In addition, since the surface of the precoat adhesive layer is at least apparently solid, it is easy to handle at the time of storage, and can be manufactured and stored in large quantities at a time, thereby greatly improving production efficiency. be able to.

────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-8-53655 (JP, A) JP-A-3-58493 (JP, A) JP-A-3-84026 (JP, A) JP-A-4- 76081 (JP, A) JP-A-2-289609 (JP, A) JP-A-52-21100 (JP, A) JP-A-2-173749 (JP, A) JP-A-7-109333 (JP, A) JP-A-6-102668 (JP, A) JP-A-7-164414 (JP, A) JP-A-7-10964 (JP, A) JP-B-48-41706 (JP, B1) (58) Fields investigated (Int.Cl. ⁷ , DB name) C09J 163/00-163/10 C08G 59/00-59/72 C09J 5/06

Claims (1)

(57) [Claims] A second component of an epoxy composition containing an epoxy resin and a powdery curing agent as essential components, and an isocyanate group, an alkoxysilane group, an acetoxysilane group , or a ketoximesilane group. And a compound having a skeleton selected from a polyurethane skeleton, a polysiloxane skeleton, and a polyether skeleton, and reacting the compound with water in the air.
Pre-mixing and applying a first component comprising a polymerization initiator to the surface to be bonded, curing the first component with moisture in the air, and curing the first component on the surface to be bonded. A step of precoating the epoxy composition with the second component remaining unreacted in the coating film; heating the second component by heating until the powdery curing agent in the second component is compatible with the epoxy resin; A method of bonding a pre-coated adhesive.