JPH05320479A - Epoxy resin composition - Google Patents

Abstract

PURPOSE:To provide an epoxy resin composition which is lowly viscous and easily workable and can give a uniform product of excellent cracking resistance without forming any settlings during curing. CONSTITUTION:This composition comprises an epoxy resin, a diluent, an acid anhydride, a cure accelerator and a filler which comprises a mixture of silica (A) of a mean particle diameter of 5-20mum with short glass fibers (B) of an average diameter of 20mum or below and an average length of 100mum or below in a weight ratio B/(A+B) of 0.05-0.20 and is added in an amount of 200-400 pts.wt. per 100 pts.wt. epoxy resin or the total of the epoxy resin and the diluent.

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, and more particularly to an epoxy resin composition suitable as an insulating material for electric equipment.

[0002]

2. Description of the Related Art Conventionally, epoxy resin compositions have excellent insulating and mechanical properties and are widely used as various electrical insulating materials. In recent years, however, electrical equipment has become smaller and lighter and operating temperature has risen. Therefore, the epoxy resin composition is required to have improved injection workability and crack resistance. In order to improve the crack resistance, a method of increasing the compounding amount of the filler and decreasing the coefficient of thermal expansion is used, but the viscosity of the epoxy resin composition remarkably increases, so that the injection workability decreases. .. Recently, inorganic short fibers are sometimes used as a filler to improve crack resistance, but the storage stability is poor and the inorganic short fibers settle, so it is necessary to disperse them before use. In addition, since the inorganic short fibers also settle during heat curing, the thermal expansion coefficients of the upper part and the lower part differ, and the crack resistance decreases.

[0003]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned drawbacks of the prior art and provides an epoxy resin composition having excellent injection workability and crack resistance.

[0004]

The present invention is an epoxy resin composition containing an epoxy resin, a diluent, an acid anhydride, a curing accelerator and a filler, and a silica having an average particle diameter of 5 to 20 μm as a filler. (A) and average diameter 20μ
Short glass fibers (B) with an average length of 100 μm or less at m or less
Is a weight ratio, and (B) / {(A) + (B)} is 0.05 to
The present invention relates to an epoxy resin composition obtained by mixing 200 to 400 parts by weight of a filler compounded in a range of 0.20 with 100 parts by weight of an epoxy resin or an epoxy resin and a diluent.

The epoxy resin used in the present invention is not particularly limited and has at least one epoxy group in one molecule. For example, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol AD type epoxy resin. Examples thereof include resins and polyglycidyl esters of polyhydric alcohols. As these resins, those that are liquid at room temperature are preferable, and as commercially available products, Epicoat 828 (trade name, manufactured by Shell Chemical Co., Ltd.), GY-260 (trade name, manufactured by Ciba-Geigy Co., Ltd.), DER-331 (manufactured by Dow Chemical Co., Ltd.). Product name) and the like. You may use these together. As the diluent, monoglycidyl ether, diglycidyl ether, polypropylene glycol or the like is used. The diluent is 5-4 with respect to 100 parts by weight of the epoxy resin.
0 parts by weight is preferred.

The acid anhydride used in the present invention is not particularly limited, but those which are liquid at room temperature are preferable, for example, methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, methylendomethylenephthalic acid and dodecenylanhydride. Phthalic acid or the like is used. As a commercial product, HN-
2200 (trade name of Hitachi Chemical Co., Ltd.), QH-200 (trade name of Nippon Zeon Co., Ltd.) and the like. You may use these together. The amount of the acid anhydride compounded is 50 to 15 with respect to 100 parts by weight of the epoxy resin or the epoxy resin and the diluent.
0 parts by weight is preferred.

The curing accelerator used in the present invention includes
For example, 2-ethyl-4-methylimidazole, 1-cyanoethyl-4-methylimidazole, 1-benzyl-2
-Imidazole and its derivatives such as ethylimidazole, and tertiary amines such as trisdimethylaminophenol and benzenmethylamine are used. As a commercial product, 2E4MZ (trade name of Shikoku Kasei Co., Ltd.), BDMA
(Product name manufactured by Kao Co., Ltd.) and the like. The compounding amount of the curing accelerator is preferably 0.1 to 5.0 parts by weight with respect to 100 parts by weight of the acid anhydride.

The filler (silica (A)) used in the present invention has an average particle size of 5 to 20 μm. When the average particle size is less than 5 μm, the viscosity is remarkably increased, thixotropic property is increased, and the workability is deteriorated. If it exceeds 20 μm,
The storage stability of the composition decreases, the inorganic filler precipitates during curing, and a cured product having different upper and lower thermal expansion coefficients is obtained, and crack resistance decreases. Commercially available CR
T-AA, CRT-AI, CRT-C66, RD-8
(Both products are manufactured by Tatsumori Co., Ltd.). The short glass fiber (B) used as the filler in the present invention has an average diameter of 20 μm or less and an average length of 100 μm or less. When the average diameter exceeds 20 μm and the average length exceeds 100 μm, the storage stability of the composition decreases, and the glass fibers settle out during curing, so that a cured product having different upper and lower thermal expansion coefficients is obtained. Crack resistance is reduced.
As commercially available products, MF-A (manufactured by Asahi Fiber Glass Co., Ltd.), REV-1, REV-4, REV-6, REV-
7, REV-8, REV-9 (trade name of Nippon Glass Board Co., Ltd.)
Etc.

In the filler used in the present invention,
Silica (A) and short glass fibers (B) are in a weight ratio of (B) /
{(A) + (B)} = 0.05 to 0.20. If it is less than 0.05, the crack resistance is inferior and is 0.20.
If it exceeds the range, the composition is inferior in settability during storage and curing.

The amount of the filler used in the present invention is
The amount is 200 to 400 parts by weight based on 100 parts by weight of the epoxy resin or the epoxy resin and the diluent. If it is less than 200 parts by weight, the cured product has a large thermal expansion coefficient and the crack resistance is inferior. If it exceeds 400 parts by weight, the viscosity of the composition remarkably increases and thixotropy increases to deteriorate workability.

In the epoxy resin composition of the present invention, a flame retardant such as red phosphorus, hexabromobenzene, dibromophenyl glycidyl ether, dibromocresyl glycinyl ether, antimony trioxide, red iron oxide, and ferric oxide may be added, if necessary. , Carbon, a coloring agent such as titanium white, a silane coupling agent, a defoaming agent such as a silicone agent, and the like can be added.

[0012]

EXAMPLES The present invention will be described below with reference to examples. "Parts" in the following examples means parts by weight. Epoxy resin compositions were prepared with the formulations and amounts shown in Table 3, respectively, and poured into a predetermined mold and cured at 80 ° C. for 3 hours and then at 140 ° C. for 3 hours to obtain a cured product. The viscosity of the prepared composition, the linear expansion coefficient of the cured product, the crack resistance, and the sedimentation property of the filler during curing were measured as follows, and the results are shown in Table 1. (1) Viscosity: The viscosity of the epoxy resin composition in a thermostat at 25 ° C. according to JIS C 2105, B manufactured by Tokyo Keiki Co., Ltd.
It was measured by using a rotational viscometer. (2) Coefficient of linear expansion: The epoxy resin composition is cured at 80 ° C. for 3 hours and then at 140 ° C. for 3 hours to prepare a cured product having a diameter of 50 mm and a length of 80 mm, and a test piece of 5 mm × 5 mm × 5 mm is cut out and rigged. It was measured with a thermophysical tester manufactured by the company. (3) Crack resistance: 1 on a metal dish having a diameter of 60 mm
A 1/2 inch iron spring washer was set, and the epoxy resin composition was injected to the upper end of the washer and cured to obtain a test piece. After that, remove the metal petri dish and JI
Heat cycle conditions of S C 2105 (shown in Table 1)
A heat cycle test was conducted according to the above, and the state of crack generation was observed, and the number of cycles in which cracks occurred was shown. (4) Sedimentability of filler during curing: An epoxy resin composition having a height of 10 cm was injected into a test tube having an inner diameter of 16 mm and cured.
The ash content (%) remaining after burning the test piece was determined, and the difference between the upper part and the lower part was taken. The larger the difference, the greater the sedimentation property.

[0013]

[Table 1]

Examples 1 to 5 Silica (A) (CRT-D, shown in Table 2 as a filler)
CRT-AA) and short glass fiber (B) (MF3A, RE
V-7) was used to examine various properties according to the above-mentioned test method using an epoxy resin composition prepared by the formulation shown in Table 3,
The results are shown in Table 3. It is shown that all the examples are excellent in workability (low viscosity), crack resistance, and settability of the cured product.

[0015]

[Table 2]

Comparative Examples 1 to 8 Silica (A) (CRT-5) shown in Table 2 as a filler.
X, EC-40) and short glass fibers (B) (MF-DP,
MF-S) and epoxy resin compositions prepared according to the formulations shown in Table 1 were used to examine various properties according to the above test methods, and the results are shown in Table 3. Comparative Example 1 in which (B) / {(A) + (B)} is less than 0.05 as a filler
The crack resistance is inferior, and Comparative Example 2 exceeding 0.20 is inferior in sedimentation and crack resistance. In Comparative Example 3 in which the average diameter exceeds 20 μm and Comparative Example 4 in which the average length exceeds 100 μm as the short glass fibers (B), the sedimentation property and crack resistance are both poor. In Comparative Example 5 in which the content of the filler is less than 200 parts with respect to 100 parts of the epoxy resin and the diluent, crack resistance is poor, and in Comparative Example 6 where it exceeds 400 parts, workability is poor. Silica (A) cannot be compounded in Comparative Example 7 having an average particle size of less than 5 μm, and in Comparative Example 8 having an average particle size of more than 20 μm, sedimentation and crack resistance are poor.

[0017]

[Table 3]

[0018]

Industrial Applicability The epoxy resin composition of the present invention has a low viscosity, excellent workability and no sedimentation during curing, whereby a uniform cured product having excellent crack resistance can be obtained.

Claims (1)

[Claims] 1. An epoxy resin composition containing an epoxy resin, a diluent, an acid anhydride, a curing accelerator and a filler, wherein silica (A) having an average particle diameter of 5 to 20 μm and an average diameter of 20 μm or less are used as the filler. With an average length of 100 μm
The weight ratio of the following glass short fibers (B) is (B) / {(A +
An epoxy resin composition obtained by mixing 200 to 400 parts by weight of a filler having (B)} in the range of 0.05 to 0.20 with 100 parts by weight of an epoxy resin or an epoxy resin and a diluent.