JPH10182794A - Fast-curing epoxy resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject composition suitable for copper-clad laminated boards used for electronic circuit substrates and excellent in low water absorption, heat resistance, adhesiveness, etc., by including a specific epoxy resin, a dicyandiamide curing agent and a dimethylurea curing promoter. SOLUTION: This composition capable of shortening molding time without impairing workability, etc., of impregnation property, etc., and suitable for epoxy resin laminated boards comprises (A) an epoxy resin having 300-700g/eq epoxy equivalent and 500-3,000g/eq phenolic hydroxyl group equivalent, (B) a dicyandiamide curing agent and (C) a dimethylurea-based curing accelerator.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copper-clad laminate used for an electronic circuit board, which has low water absorption, excellent heat resistance and excellent adhesiveness, without impairing workability such as impregnation. And an epoxy resin composition capable of shortening the molding time.

[0002]

2. Description of the Related Art Epoxy resins are excellent in adhesiveness, heat resistance and moldability, so that they are used in electronic parts, electric equipment, automobile parts,
Widely used such as FRP and sports equipment. In the manufacture of copper-clad laminates used for electronic components and electrical equipment, a base material such as a glass cloth is impregnated with an epoxy resin composition dissolved in a solvent, heated and dried to prepare a prepreg,
This can be obtained by laminating several sheets and a copper foil to form them.
The curing agent currently used for this purpose is mainly dicyandiamide, and has a low reactivity with the epoxy resin, and therefore uses a curing accelerator. When the amount of the curing accelerator is increased to shorten the molding time, the storage stability of the prepreg deteriorates, and there is a limit. Since the molding time requires a long time including the time for heating and cooling, improvement in productivity has been desired.

[0003]

The present inventors have studied various epoxy resin compositions in order to improve the productivity of copper-clad laminates. As a result, the phenolic hydroxyl groups and epoxy groups were contained in the epoxy resin in specific amounts. By mixing epoxy resin, dicyandiamide and dimethylurea-based curing accelerator, it has lower water absorption than conventional copper-clad laminates, excellent heat resistance and adhesiveness, and has no adverse effect on workability such as impregnation. An epoxy resin composition capable of shortening the molding time can be obtained, and it has been found that this composition is suitably used for a copper-clad laminate used for an electronic circuit board, etc., and the present invention has been completed. The purpose is to have a lower water absorption than conventional copper-clad laminates, excellent heat resistance and adhesion,
An object of the present invention is to provide an epoxy resin composition that can reduce molding time by a method that does not adversely affect workability such as impregnation.

[0004]

The present invention relates to an epoxy resin having an epoxy equivalent in the range of 300 to 700 g / eq and a phenolic hydroxyl equivalent in the range of 500 to 3000 g / eq, a dicyandiamide curing agent, and dimethylurea. An epoxy resin composition characterized by containing a system curing accelerator.

That is, the epoxy equivalent used in the present invention is 3
The epoxy resin having a range of from 00 to 700 g / eq and a phenolic hydroxyl group equivalent of from 500 to 3000 g / eq has been previously described by the present applicant as an epoxy resin having a low water absorption rate and excellent heat resistance and adhesiveness. (Japanese Patent Application No. 4-195272, JP-A-6-412).
No. 77). The present invention uses the epoxy resin, combines a dicyandiamide curing agent as a curing agent, and a dimethylurea-based curing accelerator as a curing accelerator to provide a low water absorption rate, excellent heat resistance and adhesion, and molding time. , A short-curing epoxy resin composition having a short curing time was obtained.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The epoxy resin used in the present invention comprises a compound having an average of 2.5 or more phenolic hydroxyl groups in one molecule, tetrabromobisphenol A or bisphenol A, and a low molecular weight epoxy resin. Is obtained by reacting This is disclosed by the present applicant in Japanese Patent Laid-Open No. 6-412.
Since it is the epoxy resin proposed in No. 77, the epoxy resin composition of the present invention is an epoxy resin having low water absorption, excellent heat resistance, excellent adhesiveness, and excellent workability such as impregnation. Also,
In the present invention, the epoxy equivalent obtained by reacting a compound having two phenolic hydroxyl groups in one molecule with an epoxy resin having a bifunctional or more epoxy group is 300 to 7;
An epoxy resin having a range of 00 g / eq and a phenolic hydroxyl equivalent of 500 to 3000 g / eq may be used. Further, by mixing an epoxy resin having no phenolic hydroxyl group in the molecule and a phenol compound having two or more functional phenolic hydroxyl groups in one molecule, the epoxy equivalent is in the range of 300 to 700 g / eq, and Hydroxyl equivalent is 500-3000g
An epoxy resin having a range of / eq may be obtained.

In the present invention, an epoxy resin is reacted with a phenol compound to give an epoxy equivalent of 300 to 700.
Although a polyfunctional epoxy resin having a g / eq range and a residual phenolic hydroxyl group equivalent of 500 to 3000 g / eq is obtained, a known catalyst can be used in the reaction. Conventional catalysts such as metal oxides, inorganic bases, organic bases and salts thereof, onium compounds and phosphines may be used.

However, in the present invention, in order to leave a part of the phenolic hydroxyl group in the epoxy resin unreacted in the epoxy resin, the amount of the catalyst and the reaction temperature need to be adjusted depending on the raw materials used. Also, with certain catalysts, the catalyst can be deactivated by various methods,
The desired epoxy resin can be produced by this method. As a method for deactivating the catalyst, there are methods such as lowering the reaction temperature, adding a deactivator, or raising the temperature to thermally decompose the catalyst. The desired epoxy resin can also be produced by a continuous synthesis method represented by a mixing device such as a uniaxial co-kneader or a biaxial ruder. Further, in the present invention, a desired epoxy resin may be obtained by mixing a phenol compound with the epoxy resin.
In short, any method may be used as long as the terminal groups of the epoxy resin are a specific number of epoxy groups and phenolic hydroxyl groups.

When the epoxy equivalent in the epoxy resin composition of the present invention is 300 g / eq or less, the amount of the curing agent used is large, resulting in poor water resistance. When the epoxy equivalent is 700 g / eq or more, The impregnating property is deteriorated by the increase in the resin viscosity. And also about the residual phenolic hydroxyl group equivalent, 500 g / eq
Below, the compounding ratio of the specific polyfunctional epoxy resin is reduced to deteriorate heat resistance. At 3000 g / eq or more, the amount of the curing agent used is increased. It gets worse.

Although the curing agent of the composition of the present invention is dicyandiamide, a commonly used curing agent for epoxy resins such as phenol curing agents, acid anhydrides and amines can be used in combination.

The dimethylurea curing accelerator used in the present invention has a structure in which a hydrogen atom of a carbamide group derived from urea is substituted with a methyl group.
Specifically, U-CAT 3502T (manufactured by aromatic dimethylurea San Apro Co., Ltd.), U-CAT 3502T
3N (alicyclic dimethylurea manufactured by San Apro Co., Ltd.) and the like. These curing accelerators may be used singly or as a mixture of two or more kinds. The mixing ratio of the curing agent and the curing accelerator to the epoxy resin is not different from the conventional one, and is usually based on 100 parts by weight of the epoxy resin. 0.5-3.0 parts by weight of a curing agent, 0.02-curing accelerator
1.00 parts by weight.

In the composition of the present invention, various organic solvents and inorganic fillers, reinforcing materials such as glass cloth and aramid fibers, fillers, pigments, and the like can be used as necessary.

[0013]

Next, the present invention will be described specifically with reference to examples and comparative examples, but the present invention is not limited to these examples. The epoxy equivalent of the synthesized epoxy resin is J
The measurement was performed according to IS K7236. Further, the phenolic hydroxyl group equivalents of Synthesis Examples 1 and 2 were obtained by measuring the acid value with potassium hydroxide and converting the value to the phenolic hydroxyl group equivalent.

Synthesis Example 1 In a four-necked flask equipped with a stirrer, a thermometer, a cooling tube, and a nitrogen gas introducing device, 1055 parts of Epototo YD-128 (bisphenol A type epoxy resin epoxy equivalent 186 g / eq, manufactured by Toto Kasei Co., Ltd.) , ZX-1236
(Tohoku Kasei Co., Ltd. paracresol-dicyclopentadiene condensate Number of phenolic hydroxyl groups in one molecule
3) 163 parts were charged and melted by heating while flowing a nitrogen gas, and 0.15 part of triphenylphosphine was added thereto.
The reaction was performed at 0 ° C. for 2.5 hours. Thereafter, 702 parts of tetrabromobisphenol A was charged and melted by heating. To this, 0.04 part of triphenylphosphine was added to add 160 parts.
The reaction was performed at 4 ° C. for 4 hours to obtain an epoxy resin. The epoxy equivalent of the obtained epoxy resin was 622.2 g / eq. The phenolic hydroxyl equivalent was 2516 g / eq.

Synthesis Example 2 Using the same apparatus as in Synthesis Example 1, YD-128 314
Part, YDCN-702 (Orthocresol novolak epoxy resin manufactured by Toto Kasei Co., Ltd. Epoxy equivalent 204
g / eq) of 300 parts and bisphenol A (62 parts) were charged and melted by heating while flowing a nitrogen gas. Thereafter, 0.05 parts of triphenylphosphine was added and the mixture was reacted at 160 ° C. for 2.5 hours. Then, tetrabromobisphenol A
324 parts was added and melted. To this, 0.01 part of triphenylphosphine was added and reacted at 160 ° C. for 4 hours to obtain an epoxy resin. The epoxy equivalent of the obtained epoxy resin was 421.0 g / eq, and the phenolic hydroxyl equivalent was 1
It was 311 g / eq.

Example 1 Epotote Y was added to 90 parts of the epoxy resin obtained in Synthesis Example 1.
DCN-704 (orthocresol novolak epoxy resin manufactured by Toto Kasei Co., Ltd., epoxy equivalent: 211 g / eq)
10 parts, and 1.6 parts of dicyandiamide as a curing agent.
4 parts, U-CAT 3503N as a hardening accelerator was added to 0.1 part.
Forty parts were compounded and the laminate was evaluated. Table 1 shows the performance of the obtained laminate.

Example 2 U-CAT 3503N was used as a curing accelerator in an amount of 0.20.
Parts, and 2 parts of ethyl 4-methylimidazole were mixed in the same manner as in Example 1 except that 0.05 part of the compound was mixed, and the laminate was evaluated. Table 1 shows the performance of the obtained laminate.

Example 3 1.69 parts of dicyandiamide as a curing agent and 0.35 part of U-CAT 3503N as a curing accelerator were added to 100 parts of the epoxy resin obtained in Synthesis Example 2, and the laminate was evaluated. Was. Table 1 shows the performance of the obtained laminate.

Example 4 Epotote YDB-500 (a brominated epoxy resin manufactured by Toto Kasei Co., Ltd., epoxy equivalent: 50 as an epoxy resin)
4 g / eq) 73 parts of Epotohto YD-901 (BPA type epoxy resin manufactured by Toto Kasei Co., Ltd., epoxy equivalent 4)
62 g / eq) 12 parts, epotote YDCN-704
15 parts and 10 parts of tetrabromobisphenol A were mixed, 2.15 parts of dicyandiamide was used as a curing agent, and 0.15 part of U-CAT 3503N was used as a curing accelerator.
0.08 parts of ethyl 4-methylimidazole was blended, and the laminate was evaluated. Table 1 shows the performance of the obtained laminate. DSC measurement was performed on this epoxy resin composition, and the results are shown in FIG. (Refer to the evaluation section for the measurement method.)

[0020]

[Table 1]

Comparative Example 1 90 parts of Epotote YDB-500 as an epoxy resin was mixed with 10 parts of Epotote YDCN-704, 2.33 parts of dicyandiamide as a curing agent, and 0.05 parts of 2-ethyl-4-methylimidazole as a curing accelerator. And
The laminate was evaluated. Table 2 shows the performance of the obtained laminate.

Comparative Example 2 A laminate was evaluated in the same manner as in Comparative Example 1 except that 0.23 part of U-CAT 3503N was blended as a curing accelerator. Table 2 shows the performance of the obtained laminate.

COMPARATIVE EXAMPLE 3 2-ethyl 4-methylimidazole was used as a hardening accelerator in 0.1 mL.
A laminate was evaluated in the same manner as in Example 1 except that 10 parts were blended, and the laminate was evaluated. Table 2 shows the performance of the obtained laminate.

[0024]

[Table 2]

The evaluation method is as follows. The impregnating property was evaluated by visually impregnating a glass cloth with the compounded resin varnish. Those with very good impregnation are indicated by a, and those with slightly better impregnation are indicated by b. The water absorption was measured by removing the copper foil by etching in accordance with JIS C 6481 3.2, and then leaving it under a condition of 90% humidity × 60 ° C. for 96 hours with reference to JIS C 5023. It was measured. The determination of the molding time was performed by using a resin powder obtained by kneading and loosening the prepreg as a sample, and using EXTER DSC6200 manufactured by Seiko Denshi Kogyo Co., Ltd., the temperature was raised from 20 ° C. to 180 ° C. at a rate of 5 ° C./min. The integrated value of the curing exothermic curve obtained by holding for 70 minutes was calculated, and the molding time was determined by obtaining the time at which 90% and 95% of the total heat generation was completed. It can be seen that the shorter this time is, the shorter the reaction heat generation is, and the shorter the molding time is.

The glass transition temperature of the sample after the measurement of the heat of curing was measured at a heating rate of 10 ° C./min. The copper foil peel strength was measured according to JIS C 6486 7.7. The interlaminar bond strength was measured by measuring the bond strength between one layer on the surface of the glass cloth and the seven lower layers in the same manner as the copper foil peel strength with the copper foil still attached.

From the above results, the products of Examples were good in all respects, but Comparative Examples 1 and 2 had good glass transition temperatures, but water absorption and impregnation were higher than those of Examples 1 to 4. It turns out that the molding time is long and bad. In Comparative Example 3, the water absorption and impregnation were good, but the molding time was long.

[0028]

As described above, the epoxy equivalent is 300 to
The use of an epoxy resin having a phenolic hydroxyl group equivalent in the range of 700 g / eq and a phenolic hydroxyl equivalent in the range of 500 to 3000 g / eq and dicyandiamide and a dimethylurea-based curing accelerator as a curing agent enhances workability such as impregnation. The heat resistance, the moisture resistance, and the adhesiveness are good and the effect that the molding time can be shortened is improved.

[Brief description of the drawings]

FIG. 1 shows the results of DSC measurement in Example 4.

Claims (2)

[Claims] 1. An epoxy equivalent of 300 to 700 g / eq.
And the phenolic hydroxyl equivalent is from 500 to
An epoxy resin composition containing an epoxy resin in a range of 3000 g / eq, a dicyandiamide curing agent, and a dimethylurea-based curing accelerator. 2. An epoxy resin laminate comprising the epoxy resin composition according to claim 1.