JPH08259670A - Epoxy resin composition for laminated board - Google Patents

Abstract

PURPOSE: To obtain an epoxy resin composition comprising an epoxy resin, a specific hardening agent, a hardening accelerator and a solvent, and capable of maintaining curability and simultaneously obtaining prepregs largely improved in storage stability without precipitating the curing accelerator. CONSTITUTION: This composition comprises (A) an epoxy resin (e.g. a bisphenol A type epoxy resin, a bisphenol F type epoxy resin), (B) a curing agent comprising dicyandiamide, (C) a compound of the formula (R is a divalent organic group; m, n are respectively 1-4) [e.g. 1-methyl-2,3-bis(N,N-dimethylureido) cyclohexane, 2,3-bis(N,N-dimethylureido)toluene], and (D) a solvent (e.g. methanol, methoxypropanol) for dissolving the component C.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an epoxy resin composition for a laminate used for producing a laminate used as a material for a printed wiring board.

[0002]

2. Description of the Related Art Conventionally, a laminated board used as a material for a printed wiring board is obtained by impregnating a base material such as a glass cloth with a varnish made of an epoxy resin composition and drying it to laminate a prepreg. It is manufactured by arranging copper foil on the top and bottom and molding it. As the curing agent for the epoxy resin composition used for this purpose, it is common to use dicyandiamide because the resulting laminate has a good balance of performance, and in this case, an imidazole-based compound is used to accelerate curing. It is widely practiced to add a curing accelerator such as a compound. However, a prepreg produced using an epoxy resin composition using dicyandiamide as a curing agent and an imidazole compound as a curing accelerator has insufficient storage stability, and its improvement is required. Therefore, by using microencapsulation or a compound with low solubility as a curing accelerator, it becomes incompatible with the epoxy resin composition at room temperature or only a trace amount (dissolve), and the storage stability of the prepreg. There are suggestions to improve. However, in this case, the varnish containing the curing accelerator (epoxy resin composition) is opaque with the curing accelerator dispersed, and if the varnish is stored for a long time (about 1 week), the varnish is dispersed. There is a problem that the curing accelerator thus precipitated precipitates to form a varnish having a non-uniform composition, and the resulting prepreg has variations in performance.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object thereof is to provide an epoxy resin composition using dicyandiamide as a curing agent, which has good curability. It is an object of the present invention to provide an epoxy resin composition which can produce a prepreg having good storage stability while maintaining it, and in which a curing accelerator is dissolved and no precipitation occurs.

[0004]

The epoxy resin composition for laminated boards of the invention according to claim 1 is (a) an epoxy resin,
It is characterized by containing (b) a curing agent composed of dicyandiamide, (c) a curing accelerator composed of a urea compound derivative represented by the following general formula, and (d) a solvent dissolving the curing accelerator.

[0005]

[Chemical 4]

The epoxy resin composition for laminated boards according to the second aspect of the present invention is characterized in that the curing accelerator (c) is a compound represented by the following formula.

[0007]

Embedded image

The epoxy resin composition for laminated boards according to the third aspect of the present invention is characterized in that the curing accelerator (c) is a compound represented by the following formula.

[0009]

[Chemical 6]

The present invention will be described in detail below. The epoxy resin (a) in the present invention may be a compound having two or more epoxy groups in the molecule and may be a mixture. Examples of the epoxy resin (a) include, but are not limited to, bisphenol A type epoxy resin, bisphenol F type epoxy resin, novolac type epoxy resin, and halogenated epoxy resin.

The curing agent (b) in the present invention may be any agent containing dicyandiamide as an essential component,
It does not matter if it contains components other than dicyandiamide. However, in order to obtain well-balanced performance, it is desirable to contain dicyandiamide as a main component in the curing agent.

The curing accelerator (c) in the present invention is a compound represented by the above general formula. Specifically, the compound represented by the above formula and the compound represented by the above formula can be exemplified, and these may be used alone or in combination of two or more kinds.

The solvent (d) in the present invention is a solvent that dissolves the curing accelerator (c), and specific examples thereof include alcohol solvents such as methanol and methoxypropanol, water and the like, but are not limited thereto. It is not something that will be done. A mixed solvent with another solvent (for example, a ketone solvent such as methyl ethyl ketone or dimethylformamide) that dissolves the epoxy resin (a) and the curing agent (b) is preferable.

The epoxy resin composition for laminated boards of the present invention comprises
The above-mentioned epoxy resin (a), curing agent (b), curing accelerator (c) and solvent (d) are contained as essential components, but other components such as fillers and additives may be added according to the present invention. It can be contained in a range that does not impair the purpose.

[0015]

The epoxy resin composition of the present invention contains the curing accelerator (c) represented by the general formula as a curing accelerator so that a prepreg having good storage stability can be obtained. In addition, the fact that the epoxy resin composition of the present invention contains the solvent (d) that dissolves the curing accelerator (c) does not cure even if the epoxy resin composition (varnish) is stored for a long time. It acts to prevent precipitation of the accelerator.

[0016]

EXAMPLES The present invention will be described below based on Examples and Comparative Examples. (Examples 1 to 4 and Comparative Examples 1 to 3) As the epoxy resin (a), the following three kinds of epoxy resins were blended in the proportions shown in Table 1 and used. (1) Epoxy resin 1 --- Tetrabromobisphenol A type epoxy resin having an epoxy equivalent of 400 [Product number ESB400 manufactured by Sumitomo Chemical Co., Ltd.] (2) Epoxy resin 2--Tetrabromobisphenol A type having an epoxy equivalent of 500 Epoxy resin [manufactured by Dow Chemical Co., product number DER511] (3) Epoxy resin 3 --- Epoxy equivalent of 200 cresol novolac type epoxy resin [manufactured by Toto Kasei Co., Ltd.,
Part number YDCN702]

As the curing agent (b), dicyandiamide as a reagent was mixed and used in the ratio shown in Table 1. The molecular weight of dicyandiamide is 84, and the theoretical active hydrogen equivalent is 21 / eq.

As the curing accelerator (c), the following four types of curing accelerators were mixed and used in the proportions shown in Table 1. (1) Curing accelerator 1 --- Compound represented by the above formula [melting point: about 200 ° C., manufactured by San-Apro Co., Ltd., trade name Uca
t3503N] (2) Curing accelerator 2 --- Compound represented by the above formula [melting point of about 190 ° C., manufactured by San-Apro Co., Ltd., trade name Uca
t3502T] (3) Curing accelerator 3--2-ethyl 4-methylimidazole

As the solvent (d) for dissolving the curing accelerator, there are methoxypropanol, which is a solvent for dissolving the curing accelerator 1 and the curing accelerator, and methyl ethyl ketone and dicyandiamide, which are solvents for dissolving the epoxy resin (a). Table 1 shows dimethylformamide, which is a solvent that dissolves
The mixed solvent mixed in the ratio shown in was used.

The above epoxy resin, curing agent, curing accelerator and solvent were mixed in the proportions shown in Table 1 and stirred to prepare an epoxy resin composition (varnish). When the transparency of the obtained varnish was visually observed and evaluated, all the varnishes of Examples 1 to 4 and Comparative Examples 1 to 3 were transparent.

The epoxy resin composition (varnish) prepared above was used as a glass cloth [manufactured by Asahi Schwebel KK, product number 762.
8 W] and then dried at 150 ° C. to prepare a prepreg having a resin content of about 45% by weight and a thickness of about 0.2 mm. The drying time at this time is 130 ° C. melt viscosity of the resin component (130
It was set for each epoxy resin composition (varnish) so that the minimum melt viscosity (measured at ° C) was in the range of 300 to 500 poise. About the obtained prepreg 170
Measure the curing time at ℃ and the number of days that can be stored at 40 ℃,
The curability of the prepreg and the storage stability of the prepreg were evaluated, and the evaluation results are shown in Table 1.

The test method for each evaluation item is shown below. (Curing property of prepreg: curing time at 170 ° C.) The resin content adhering to the prepreg is rubbed off, and the resin is placed on a hot platen at 170 ° C., and the resin is gel-like (state in which fluidity is lost). Measure the time until. (Storage stability of prepreg) The prepreg was stored in a constant temperature bath at 40 ° C, the melt viscosity at 130 ° C was measured at regular intervals, and its change over time was examined. The change rate from the initial value was 50%.
40 days less than (excluding days with 50% or more)
The number of days that can be stored at ℃ was set. In addition, the measurement of the melt viscosity,
The resin content adhering to the prepreg was rubbed off and measured using a Koka type flow tester. [Change rate (%) of melt viscosity = (melt viscosity after aging−initial melt viscosity) × 100
/ (Initial melt viscosity)]

[0023]

[Table 1]

From the results shown in Table 1, it was confirmed that, in comparison with the comparative example, in the example of the present invention, no precipitate was generated in the varnish and the storage stability of the prepreg was good.

[0025]

EFFECTS OF THE INVENTION According to the epoxy resin composition for laminates of the inventions of claims 1 to 3, dicyandiamide is used as a curing agent, and the curing accelerator is dissolved, so that precipitation of the curing accelerator is prevented. It is an epoxy resin composition that does not occur, and while maintaining good curability, it is possible to obtain an epoxy resin composition capable of producing a prepreg with significantly improved storage stability compared to conventional ones. it can.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Eiji Motobu 1048, Kadoma, Kadoma, Osaka Prefecture Matsushita Electric Works Co., Ltd. In the company

Claims (3)

[Claims] 1. A curing agent comprising (a) an epoxy resin, (b) a dicyandiamide, (c) a curing accelerator comprising a urea compound derivative represented by the following general formula, and (d) a solvent in which the curing accelerator is dissolved. An epoxy resin composition for a laminate, comprising: Embedded image 2. The epoxy resin composition for a laminate according to claim 1, wherein the curing accelerator (c) is a compound represented by the following formula. Embedded image 3. The epoxy resin composition for a laminate according to claim 1, wherein the curing accelerator (c) is a compound represented by the following formula. Embedded image