JP3196245B2 - One-part type thermosetting epoxy resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to sealing of electronic and electric parts,
The present invention relates to a one-pack type thermosetting epoxy resin composition that can be cured in a range of 70 to 150 ° C. and can be widely used in various electronic components such as molding materials for impregnation and industrial equipment.

[0002]

2. Description of the Related Art In recent years, epoxy resins have been widely used in paints, cast products, adhesives, etc. due to their excellent physical properties after curing.
2. Description of the Related Art Conventionally, so-called two-pack type epoxy resin compositions in which two components consisting of a main agent and a curing agent are mixed at the time of use are often used. Although the two-part epoxy resin composition can be cured at room temperature, it has the disadvantage of requiring precise work such as measurement and mixing or stirring of the main agent and the curing agent, and has a short pot life after mixing the main agent and the curing agent. However, there is a problem that work must be performed quickly after mixing. Accordingly, a one-pack type thermosetting epoxy resin composition in which a curing agent and an epoxy resin are previously mixed without these defects has been developed.

[0003] The one-part type thermosetting epoxy resin composition is provided with a latent curing agent such as dicyandiamide, melamine, imidazole or the like and a microcapsule which is physically destroyed by pressure, heat or the like. For example, those containing a highly reactive curing agent therein are used.

[0004]

However, in the above-mentioned conventional structure, the former requires a high curing temperature and a long curing time, and requires a separate use of a curing accelerator or the like in order to enhance the curability. There was a point. In addition, when a curing accelerator is used, it hardens in a short time after mixing the main agent and the curing agent, so that it has to be used quickly after mixing, and it is difficult to handle. In the case of the latter, it is difficult to obtain microcapsules having good breaking characteristics, and no satisfactory storage stability and physical properties of the cured product have yet been obtained. In general, a cured product of an epoxy resin has very good electrical properties and physical properties, but has a drawback of being hard and weak in thermal heat cyclability.
As a countermeasure, the use of a reactive diluent such as a long-chain alkyl group epoxide can somewhat improve the heat cycle property, but on the other hand, there is a problem in that the reactivity of thermosetting is reduced.

The present invention solves the above-mentioned conventional problems. It cures at a high curing rate at a low temperature, has excellent storage stability, is easy to handle, and significantly improves the workability of the sealing operation of electronic equipment. It is an object of the present invention to provide a one-part type thermosetting epoxy resin composition which can be improved.

[0006]

According to the present invention, there is provided a one-part type thermosetting epoxy resin composition according to the present invention, comprising a bifunctional epoxy resin having an epoxy equivalent of 125 to 250.
100 parts by weight of a resin, 2 to 35 parts by weight of a latent curing agent,
30 to 115 parts by weight of an acid anhydride type curing agent and trialkyl
0.1 to 40 parts by weight of a phosphoric ester and mercaptoben
Zothiazole or a derivative thereof or a mixture thereof
0.1 to 10 parts by weight.
Ri, one-part type thermosetting epoxy resin composition according to claim 2,
Bifunctional epoxy resin 1 having an epoxy equivalent of 166 to 194
00 parts by weight, 5 to 25 parts by weight of a latent curing agent, and acid anhydride
50-90 parts by weight of a solid curing agent and trialkyl phosphate
1 to 30 parts by weight of stell and mercaptobenzothiazole
Or 1 to 5 parts by weight of a derivative thereof or a mixture thereof
And a configuration comprising:

Here, as the bifunctional epoxy resin,
In particular, bisphenol types such as bisphenol A type and bisphenol F type are preferable. This is because mechanical and electrical properties are particularly excellent when the electronic component is sealed. When the epoxy equivalent is less than 125, there is a disadvantage that the breaking strength of the cured product becomes weak, and when it exceeds 250, there is a disadvantage that the reactivity decreases. Particularly, the range of 164 to 194 is preferable in view of reactivity and mechanical / electrical properties.

The latent curing agent is preferably an amine adduct type. As the amine adduct type, Amicure manufactured by Ajinomoto Co., Inc. or the like is used. If the amount of the latent curing agent is less than 2 parts by weight, the reactivity decreases, and if it exceeds 35 parts by weight, the residual stress at the time of curing by reaction heat increases, which is not preferable. Particularly, the range of 5 to 25 parts by weight is preferable from the viewpoint of reactivity and physical properties.

As the acid anhydride type curing agent, phthalic anhydride, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, nadic anhydride, methylnadic anhydride, chlorene Dick acid anhydride, dodecinyl succinic anhydride, methyl succinic anhydride, pyromellitic anhydride, maleic anhydride, benzophenone tetracarboxylic anhydride and the like. These are used alone or as a mixture of two or more. From the viewpoint of workability, monohydric acid anhydrides or liquid acid anhydrides are sufficient, but if heat resistance and mechanical properties are particularly important, use polyhydric acid anhydrides alone or in liquid form. It is desirable to use it in a mixture with an acid anhydride.

[0010] Trialkyl phosphates include C
₅ may be any one having an alkyl group of -C ₁₀ but, trioctyl phosphate _{(C 8 H 17 O) 3} PO is preferred. This is because the workability is excellent and the safety is high. The addition amount is 0.1 to 40 parts by weight, preferably 1 to 30 parts by weight.
This is because flexibility is provided and reactivity is not reduced. 0.
If the amount is less than 1 part by weight, the effect of addition is low, and if it exceeds 40 parts by weight, the reactivity is undesirably reduced. Particularly when a high curing speed is required at a low temperature, a general formula C is used as a curing accelerator.
It is advisable to add 0.1 to 10 parts by weight, preferably 1 to 5 parts by weight of mercaptobenzothiazole represented by 7H5 NS2 or a derivative thereof alone or in a mixture thereof. If the amount is less than 0.1 part by weight, there is no elasticity-imparting effect, and if it exceeds 10, the viscosity increases and the workability deteriorates.

As mercaptobenzothiazole, α
-Mercaptobenzothiazole, dimers and mixtures thereof are preferred. This is because the elasticity can be appropriately imparted to the cured product. Other inorganic fillers such as zeolite and quartz powder may be added according to the intended use.

[0012]

With this structure, a high-speed curing rate at a low temperature (curing at 70 ° C. for one hour), which cannot be achieved by the conventional one-pack type thermosetting epoxy resin composition which has generally been composed mainly of dicyandiamide, is used. Can be realized.

[0013] In addition, storage stability at room temperature (25
℃) stability of 6 months or more and workability can be remarkably improved. In addition, the obtained cured product has excellent heat cycle properties, and can significantly improve the durability of a sealed portion of an electronic / electric device.

[0014]

Embodiments of the present invention will be described below in detail.

(Examples 1 to 7, Comparative Examples 1 to 3) <Preparation of Sample> a. Epoxy resin Bisphenol A type epoxy resin Epoxy equivalent 184 to 194 (Epicoat 828, manufactured by Shell Chemical Co., Ltd.) Bisphenol F type epoxy resin Epoxy equivalent 166 to 175 (Epicoat 807, manufactured by Shell Chemical Co., Ltd.) b. Latent amine adduct type curing agent Amicure PN-23 (manufactured by Ajinomoto Co.) as amine adduct curing agent (1) Amicure MY-24 (manufactured by Ajinomoto Co.) as amine adduct curing agent (2) c. Acid anhydride type curing agent HN-2200 containing phthalic anhydride as a main component (manufactured by Hitachi Chemical Co., Ltd.) d. Trialkyl phosphoric acid ester trioctyl phosphate (TOHACHI CORPORATION, TO
P) e. Curing accelerator α-mercaptobenzothiazole represented by the formula (1) as a curing accelerator (1) (Axel M, manufactured by Kawaguchi Chemical Co., Ltd.)

[0016]

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As a curing accelerator (2), a dimer of α-mercaptobenzothiazole represented by the formula (Axel DM, manufactured by Kawaguchi Chemical Co., Ltd.)

[0018]

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F. Curing agent Dicyandiamine (manufactured by Nippon Carbide Co., Ltd.) 2-Methylimidazole (manufactured by Shikoku Chemicals Co., Ltd.) <Preparation of sample> Using the above raw materials, mix with a planetary mixer at the mixing ratio shown in (Table 1). Then, a one-pack type thermosetting epoxy resin composition was prepared and cured at 70 to 120 ° C. for 1 hour.

[0020]

[Table 1]

Next, the following characteristics were evaluated. The results are shown in (Table 2).

[0022]

[Table 2]

(1) Measurement of Gelation Time 1.5 g of the above-mentioned sample was collected on an aluminum hot plate kept at a predetermined temperature in advance, and stirred with a steel needle until the fluidity of the resin was lost. The time was defined as the gel time.

(2) Measurement of Glass Transition Temperature The cured product cured at 100 ° C. for 1 hour was subjected to thermomechanical analysis (TM
The inflection point of the coefficient of linear expansion was determined as the glass transition temperature.

(3) Measurement of Usable Temperature The sample prepared as described above was initially measured for viscosity in a 25 ° C. atmosphere using a viscometer, and then placed in a container kept at 25 ° C. and allowed to stand every week. The viscosity was measured, and a period until the value became twice the initial value was defined as a usable time.

(4) Shear bond strength A test piece having a bond area of 15 mm × 30 mm was prepared and subjected to JIS K
It was measured according to 6850.

As is clear from Table 2, in the case of this example, the pot life was more than 6 months when stored at 25 ° C., whereas in the comparative example, less than 10 days were observed. Was. During the curing reaction, it showed a rapid curing reaction at a low temperature such that it was cured at 70 ° C. to 100 ° C. in 1 hour, and was found to be a one-part epoxy resin composition having a potential not seen before. .

Further, the obtained cured product was found to have excellent effects on electrical properties and physical properties (particularly heat cycle properties).

[0029]

As described above, the one-part type thermosetting epoxy resin composition of the present invention has a high curing rate at low temperature and excellent storage stability. It is easier to handle as compared with the case where the main agent and the curing agent must be mixed and used immediately, and when used as a sealing material for precision electronic parts and electric parts, workability can be significantly improved.

Further, the one-part thermosetting epoxy resin composition of the present invention has very excellent adhesive strength, such as adhesion of advanced composite materials such as metal-metal, metal-plastic, metal-ceramic, and hybrid IC. The present invention can be applied to a field such as a potting material, and can realize an excellent one-part type thermosetting epoxy resin composition which can greatly improve the reliability and durability of various parts and the like.

Continuation of front page (56) References JP-A-64-40516 (JP, A) JP-A-63-183920 (JP, A) JP-A-63-72722 (JP, A) JP-A-61-197623 (JP, A) , A) (58) Field surveyed (Int. Cl. ⁷ , DB name) C08G 59/22 C08G 59/42 C08G 59/40

Claims (2)

(57) [Claims] 1. Bifunctionality having an epoxy equivalent of 125 to 250
100 parts by weight of epoxy resin and 2 to 35 layers of latent curing agent
Parts by weight, 30 to 115 parts by weight of an acid anhydride type curing agent,
0.1 to 40 parts by weight of an alkyl phosphate,
Putbenzothiazole or its derivative or their
A one-part type thermosetting epoxy resin composition, comprising 0.1 to 10 parts by weight of a mixture . 2. Bifunctionality having an epoxy equivalent of 166 to 194.
100 parts by weight of epoxy resin and 5 to 25 layers of latent curing agent
Parts by weight, 50 to 90 parts by weight of an acid anhydride type curing agent,
1 to 30 parts by weight of alkyl phosphate
Nzothiazole or a derivative or mixture thereof
1 to 5 parts by weight of the one-part type thermosetting epoxy resin composition.