JPS61221216A - Epoxy resin composition - Google Patents

Abstract

PURPOSE:To obtain a resin composition which gives a cured article having excellent flow, cracking resistance and dielectric breakdown strength, by mixing an epoxy resin and a curing agent with an inorganic fiber surface-treated with a vinylsilane compound and an inorganic powder or particles. CONSTITUTION:100pts.vol. epoxy resin and curing agent are mixed with 40-200 pts.vol. total of an inorganic fiber diameter of 3-20mu and a length of 3-150mu, surface-treated with a vinylsilane compound and an inorganic powder or particle having a particle size distribution containing at least 90wt% component of a particle diameter <=10mu and at least 50wt% component of a particle diameter <=5mu. As the vinylsilane compound used for surface treatment, vinyltri-beta- methoxyethoxysilane is desirable for obtaining a remarkable effect on fluidity. Examples of said inorganic fibers include inorganic oxide fibers (e.g., Al2O3) and inorganic non-oxide fibers (e.g., Si3N4).

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an epoxy resin composition, and more particularly to an epoxy resin composition that has excellent crack resistance and dielectric breakdown strength in a cured product and also has good fluidity during casting. The present invention relates to a resin composition.

[Technical background of the invention and its problems]

Today, epoxy resin compositions are attracting attention for their low shrinkage during casting and the high strength of the cured product, and are widely used as cast or molded products. There is a need for epoxy resin compositions.

Furthermore, in order to improve the heat resistance, strength, and tracking resistance of the epoxy resin composition, a method has been adopted in which the epoxy resin composition is filled with inorganic powder. For example, epoxy resin compositions filled with inorganic powder such as alumina are used for mold insulation, insulators, bushings, spacers, etc. of electrical equipment.

However, it is true that filling an epoxy resin composition with inorganic powder can improve heat resistance, strength, tracking resistance, etc., but on the other hand, filling an epoxy resin composition can increase viscosity and reduce fluidity, which is a serious problem. A problem occurs.

Due to the increase in viscosity and decrease in fluidity, it becomes difficult to cast and mold the epoxy resin composition, and voids are likely to occur in the molded product, resulting in problems with mechanical strength, electrical insulation, and precision of dimensions and shape. This is a cause of deterioration of various qualities of molded products such as.

For this reason, it has been desired to develop an epoxy resin composition that exhibits excellent heat resistance, dielectric breakdown strength, and crack resistance of the cured product, as well as good fluidity during casting.

[Purpose of the invention]

An object of the present invention is to provide an epoxy resin composition in which a cured product has excellent crack resistance and dielectric breakdown strength as well as good fluidity.

[Summary of the Invention] The epoxy resin composition of the present invention comprises inorganic fibers having a diameter of 3 to 20 JMt1 and a length of 3 to 1500 p, which have been surface-treated with a vinyl silane compound, and a particle size of 10 to 1500 p, to 100 parts by volume of an epoxy resin and a curing agent. -The following ingredients are 90% by weight or more and 5
This is an epoxy resin composition characterized in that it contains a total of 40 to 200 parts by volume of the following components and an inorganic powder having a particle size distribution of 50% by weight or more.

The epoxy resin used in the present invention may be of any type as long as it is generally known as an epoxy resin. Specific examples of this resin include bisphenol A diglycidyl ether, warped dimer, trimer, epoxy resin obtained from novolac type phenol resin and epichlorohydrin, and epoxy resin obtained from polyhydric alcohol polyalkylene oxide and epichlorohydrin. resin,
Examples include epoxy resins containing cyclohexene oxide groups.

The curing agent used in the present invention may be any known curing agent for epoxy resins. Specific examples of this curing agent include phthalic anhydride, hexahydrophthalic anhydride, tetrahydrophthalic anhydride,
Acid anhydrides such as methyl-hexahydrophthalic anhydride, methyl-tetrahydrophthalic anhydride, methyl-nadic anhydride, dodecenylsuccinic anhydride, pyromellitic anhydride; triethylenetetramine, metaphenylenediamine, tris(dimethylaminomethyl)phenol Amines such as;
Examples include dicyandiamide; boron trifluoride-amine imidazole; one type or a mixture of two or more types selected from the group consisting of these are used.

Furthermore, the vinyl silane compound used in the surface treatment according to the present invention may be any vinyl silane compound;
Vinyltri-β-methoxyethoxysilane is particularly preferred in order to obtain a remarkable effect on fluidity.

Myriad fibers used in the present invention usually have a diameter of 3 to 20-
1 is preferably 9 to 13/J#l, and the length is usually 3 to
1500JJIn1 preferably 10-1000JJ! 1
It is an i-free fiber of No. 1. If the diameter and length of the inorganic fibers are outside the above-mentioned ranges, no viscosity reduction phenomenon is observed, which is not preferable.

In addition, inorganic fibers include MzO3, Mqo, S! Oxide-based inorganic fibers such as Oz, S! 3N4. SiC,B.

Any non-oxide inorganic fiber such as C or the like may be used as long as it is fibrous, such as milled fiber (trade name, manufactured by Asahi Fiberglass Co., Ltd.), microglass fiber (trade name, (manufactured by Nippon Sheet Glass Co., Ltd.), glass cut fiber (trade name, manufactured by Fuji Fiber Glass Co., Ltd.), alumina fiber, boron fiber, glass fiber, and the like.

The powder and granular material used in the present invention has a particle size of 10JJIft or less at 90% by weight or more and a particle size of 5JJII! The following is 50% by weight
It is a powder having the above particle size distribution (integrated distribution). If the particle size and ratio of the powder or granular material is outside the above range,
Because it does not have the effect of reducing viscosity that occurs when used in combination with fibers,
Undesirable. The inorganic powder may be any known inorganic powder, such as silica, alumina, talc, calcium carbonate, clay, aluminum hydroxide, barium sulfate, titanium dioxide, and the like.

The amount of inorganic PLI fibers and inorganic powder used in the present invention is the total amount of epoxy resin and curing agent ijA 1
00 parts by volume, 40 to 200 parts by volume, preferably 60 to 100 parts by volume. If the inorganic fibers and inorganic powder are below the lower limit of the above range, the effect of addition will be weak in terms of crack resistance and dielectric breakdown strength, which is not preferred. Further, if the upper limit is exceeded, the viscosity becomes too high and it is not suitable as a material for casting.

Furthermore, the mixing ratio of inorganic tij & fiber and inorganic powder is (0
The viscosity of the composition is at its lowest within the range shown by the formula, which is preferable from the viewpoint of workability and the like. However, it is generally weak.

As described above, the epoxy resin composition of the present invention has excellent crack resistance, by containing inorganic fibers of a specific shape and size and inorganic powder particles of a specific size, which have been surface-treated with a vinyl silane compound, in an epoxy resin. This epoxy resin composition has excellent dielectric breakdown strength and good fluidity, which cannot be obtained with epoxy resin compositions in which epoxy resin contains inorganic fibers or inorganic powder.

The epoxy resin composition for casting of the present invention may optionally contain a reactive diluent containing one epoxy group in its molecule in order to improve workability. A curing accelerator may also be used to shorten the curing time. For example, 2-ethyl-4-methyl-imidazole, 2.
4.6-tris(dimethylaminomethyl)phenol,
Examples include benzyldimethylamine, tetradecyldimethylbenzylammonium chloride, etc., and one type or a mixture of two or more types selected from the group consisting of these are used.

[Embodiments of the invention]

Examples 1 to 7 and Comparative Examples 1 to 4: A 1 to iowt% aqueous solution of vinyltri-β-methoxyethoxysilane was prepared as a vinyl silane compound, and per 200 g of this aqueous solution, alumina fiber HA (diameter 3u, diameter 24IJIn), alumina Fiber B (diameter 3K, length 61O
NK), shi')jy fiber rdIC (diameter 131JIIt
, length;! 50 cicada), and alumina powder F (particle size 2JJ
II), alumina powder G (particle size 0.5-), and silica powder ■ (particle size 10 ka) were each immersed at a ratio of 1003 for 15 hours (usually with stirring), and then the supernatant After removing the liquid, it was dried at a temperature of 120° C. for 24 hours to prepare 10 types of inorganic fibers and inorganic powder. Note that the diameter and length of the fibers and the particle size of the powder and granular material herein are average values. Next, epoxy resin compositions of Examples of the present invention and epoxy resin compositions of Comparative Examples 1 to 4 were prepared by blending them in the composition ratios shown in the table. After comparing the fluidity of these epoxy resin compositions by visual measurement, they were cured at a temperature of 130°C for 3 hours and then at a temperature of 150°C for 15 hours to create test pieces with embedded oliphant washers and insulators with a distance between electrodes of 2 m. . A thermal shock was applied to this Oliphant washer-embedded test piece, and the crack resistance index was determined by the Oliphant method. Further, a direct current voltage of 100 KV was applied to the insulator, and then a reverse polarity impulse of 350 KV was applied, and the percentage (%) of the insulator that suffered dielectric breakdown at these times was determined.

Comparative Examples 5-11 Vinyltri-β-methoxyethoxysilane 5-10wt
Alumina fiber D (surface treated in the same manner as above with a % aqueous solution)
Diameter 3JJ, length 510->, alumina fiber ME (diameter 3JJ!It1 length 6 periods), and alumina particles H1 (
The epoxy resin compositions of Comparative Examples 5 to 11 were prepared by adjusting the inorganic fibers and inorganic powder particles with a particle size of 70JJIft) in the same manner as in the examples, and the fluidity, crack resistance index, and dielectric breakdown were determined in the same manner as above. The percentage (%) of each was determined. These results are summarized in the table.

As shown in the table, the epoxy resin compositions of Examples 1 to 7 of the present invention produced as described above have a high crack resistance index, excellent crack resistance, almost no dielectric breakdown, and excellent fluidity. It can be seen that

〔Effect of the invention〕

According to the present invention, it is possible to obtain an epoxy resin composition which is excellent for use in casting, and has a cured product having excellent crack resistance and dielectric breakdown strength as well as good fluidity.

1, ゛　7, Ten ministers or ten people

Claims (1)

[Scope of Claims] 1. Inorganic fibers having a diameter of 3 to 20 μm and a length of 3 to 1,500 μm that have been surface-treated with a vinyl silane compound, and 90% of components having a particle size of 10 μm or less per 100 parts by volume of the epoxy resin and curing agent. An epoxy resin composition comprising a total of 40 to 200 parts by volume of an inorganic powder having a particle size distribution of 50% by weight or more and a component of 5 μm or less in size by weight or more. 2. The epoxy resin composition according to claim 1, wherein the vinyl silane compound is vinyltri-β-methoxyethoxysilane. 3. The epoxy resin composition according to claim 1, wherein the inorganic fiber is Al_2O_3 fiber. 4. The epoxy resin composition according to claim 1, wherein the inorganic powder is Al_2O_3 particles.