JPS61151228A - Epoxy resin composition for casting - Google Patents

Abstract

PURPOSE:To improve the heat resistance, heat shock resistance, strength, low shrinkage, etc., of a cured product, by mixing an epoxy resin containing a curing agent with a combination of a chopped fiber of a specified shape with inorganic particles of a specified particle diameter distribution. CONSTITUTION:The following two fillers are prepared: a chopped fiber (A) having a diameter of 3-15mum and a length in the range of 3-300mum and inorganic particles (B) having such a particle diameter distribution that the content of particles of a particle diameter <=10mum is equal to or greater than 90wt%, the content of particles of a particle diameter <=5mum is equal to or greater than 50wt%, and the average particle diameter is equal to or greater than 0.5mum, so that the volumes of the fillers may satisfy relationships I and II. Examples of the components A include chopped glass fiber and chopped carbon fiber. Examples of components B include silica and alumina. These two fillers are added to 100pts.vol. epoxy resin containing a curing agent (e.g., phthalic anhydride).

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention This invention relates to an epoxy resin composition for casting (more specifically, the resistance and strength of a cured product, and The present invention relates to an epoxy resin composition for casting which has extremely low shrinkage and good fluidity.

[Technical background of the invention and its problems]

Today, epoxy resin compositions are attracting attention for their low shrinkage during casting and good strength of the cured product, and are widely used as cast or molded products. High viscosity epoxy resin compositions are in demand.

General C: The strength etc. of the casting material increases in proportion to the fiber content, but on the other hand, adding fiber (=therefore, an increase in viscosity is unavoidable) and fluidity decreases.

Therefore, as a result of research and development in the field of plastics (2) of resins that simultaneously have the strength of the material and the low viscosity of the composition, the following proposals have been made.

In the field of thermoplastic resins, resins containing chopped strands (which have shorter fiber length than the commonly used resins) are known in order to improve the supply characteristics during molding. However, this supply characteristic refers to the so-called feedability from a hopper during injection molding, and is completely different from the concept of flowability of the casting material.In addition, in the field of thermosetting resins, for example, No. 168619 (=[
Cut glass fibers have a function of improving flowability during heat curing compared to high viscosity rubbery polymers (2), giving good results in sealing performance9 and workability, and also eliminating air bubbles at the adhesive interface. It is disclosed that C2 is effective (bi-functional) in preventing the occurrence of epoxy resin C2 and eliminating defects that cause peeling of the membrane.However, when epoxy resin C2 alone is blended with cut glass fibers, the blended amount In other words, the viscosity of cut glass fibers increases significantly in proportion to the length of the fibers (even though they are short, since they are still fibers, even a small amount added causes a considerable increase in viscosity, making it difficult to use for ordinary casting materials). It cannot be expected to be used as such.

Therefore, there has been a strong desire in the art for an epoxy resin composition for casting that has a high viscosity and a large amount of fiber while improving workability during casting operations.

As a result of intensive research in view of the above circumstances, the present inventors found that the combination of cut fibers with a certain shape and granules with a specific particle size distribution (cuts of short fibers with a higher density (two fillings) I discovered that this could be done and completed this invention.

[Purpose of the invention]

The purpose of the present invention is to fill fibers and inorganic particles with high density (to improve the heat resistance and thermal shock resistance of secondarily cured products).

(1) To provide an epoxy resin fiber for casting with excellent mechanical strength; and (2) low shrinkage.

[Summary of the invention]

The epoxy resin composition for casting of the present invention has a diameter of 3 to 15 μm per 100 parts by volume C' of epoxy resin and curing agent.

Cut fibers with a length distribution of 3 to 300 μm (A)
.

Particles with a particle size of 10 μm or less are 90 East tS or more and 5 μin or less are 50 times or more in diameter.
2 of inorganic powder (B) having a particle size distribution of 5 μm or more
1! 150 parts by volume of Class I filler < A + B < 22
3 Capacity part, 0.003(A+B)-0.17≦-
i-knee〇, t)03 (A0B)+he10B 1.17 A high-density short fiber-filled epoxy resin composition for casting (
Two matters.

The epoxy resin used for the C2 side of the present invention is not particularly limited, and one or two types of epoxy resins having an epoxy equivalent of 140 to 450 such as bisphenol disk epoxy resin, novolac type epoxy resin, and B'# cyclic epoxy resin are preferable. A combination of the above can be used.

The curing agent used in the present invention (second side) may be any curing agent as long as it is generally known as an epoxy resin curing agent. Specific examples of this curing agent include phthalic anhydride, hexahydrophthalic anhydride, , tetrahydroheptalic anhydride,
Methyl-hexahydrophthalic anhydride, methyl-tetrahydrophthalic anhydride.

Acid anhydrides such as methyl-nadic anhydride, dodecenylsuccinic anhydride, and pyromellitic anhydride; amines such as nitriethylenetetramine, metaphenylenediamine, and tris(dimethylaminomethyl)phenol; dicyandiamide;
Examples include boron trifluoride-amine complex; imidazole, etc., and one type or a mixture of two or more types from the group consisting of these can be used.

The present invention (= the fiber cut material (A) used has a diameter of 3 to 15 μm)
Preferably, cut fibers having a distribution of 9 to 13 μm and a length of 3 to 300 μm are used, but cut fibers having a diameter of 3 to 15 μm and a length of 300 μm or more may be used within a range that does not impair the effects of the present invention. Also good.

Examples of the cut fibers include milled fiber (trade name, manufactured by Asahi Fiberglass Co., Ltd.), microglass surf strand (trade name 0, manufactured by Nippon Sheet Glass Co., Ltd.), and glass cut fiber (trade name).

(manufactured by Fuji Fiber Glass Co., Ltd.), alumina fibers, boron fibers, silicon carbide fibers, metal whiskers, carbon fibers, and other cut fibers.

The present invention (the inorganic powder (B) used on the second side has a particle size of 10 μm)
The following particles rarely contain more than 90% by weight of particles and 5 μm or less and have a particle size distribution with an average particle size of 0.5 μm or more.

Powder having a particle size distribution different from that of the present invention, even if the average particle size is large or small, if mixed with cut fibers, the viscosity will increase excessively and the effects of the present invention cannot be obtained.

The inorganic powder of the present invention may be any known inorganic powder, such as silica, alumina, talc, calcium carbonate, clay, aluminum hydroxide, barium sulfate, titanium dioxide, etc. It will be done.

In the present invention (for second side use), the amount of the cut fibers (A) and powder (B) filled is 100 parts by volume of the epoxy resin and the curing agent (
2 and 150 < A + B < 223 parts by volume. High-density filling of 150 parts by volume or more (heat resistance (heat distortion temperature)) heat resistance (# impact resistance is significantly improved. Also, if 223 parts by volume or more is filled with light, the viscosity increases and vacuum degassing is difficult (
= Become.

The mixing ratio of the cut two-cell fiber (A) and the inorganic powder (B) is 0.003 (A+B)≦-to 1≦-0.003 (
A composition that falls within the range of +1.17A+B and does not satisfy this distribution condition has a high viscosity and is not suitable for the usual molding method (=== not suitable for casting in a gold molding method), and is difficult to vacuum degas even when cast in a molded mold.

The epoxy resin composition for casting of the present invention may be further mixed with silica, alumina, talc, etc. of the particle size used in the epoxy resin composition for casting of the present invention (2). Fillers such as organic and inorganic colorants, light surface treatment agents such as silane coupling agents, imidazole type, third
Additives such as hardening accelerators such as grade amine type and metal complex type curing accelerators may be added.

The present invention will be explained in further detail below with examples and comparative examples.

[Embodiments of the invention]

Examples-1 to 3 Epicoat 828 (Evokiku equivalent weight 184 to 1, manufactured by Shell Co., Ltd.)
94) Epoxy resin composition consisting of HN-2200 (manufactured by Hitachi Chemical Co., Ltd., acid anhydride curing agent) and N-N dimethylbenzylamine (curing accelerator) and cut glass fiber (
13μ diameter, average length 50-60μ) Silica (average particle size 0
．． Example 1
~30 An epoxy resin composition for casting according to the present invention was prepared. Next (= This casting resin was vacuum degassed at 100'C for 10 minutes.
~3) Pour into a mold and heat at 120℃ for 3 hours, then 1 hour.
A sample for measuring crack resistance, tensile strength, shrinkage rate, and heat distortion temperature was prepared by heating and curing at 50° C. for 15 hours. The results are shown in Table 2.

Comparative Example-1 A resin composition was prepared using the cut glass fiber alone at the composition ratio shown in Table 1 (Table 1), and a test sample was prepared in the same manner as in the example. The results are shown in Table C-2.

Comparative Example 2 When cut glass fiber (A) was used alone and 92 parts by volume was filled into 100 parts by volume of the epoxy resin composition shown in Example C2, the fluidity was poor and a test sample could not be prepared.

Comparative Example 3 Silica powder (B) was used alone and blended in the composition ratio shown in Figure 2 to prepare a resin composition, and a test sample was prepared in the same manner as in the example. The results are shown in 2.

Comparative Example-4 When silica powder (B) was used alone and filled in 154 parts by volume to 100 parts by volume of the resin composition shown in Example (1), the viscosity increased significantly and it was difficult to prepare the resin composition. could not.

Comparative Example-5, 6 Cut glass fiber (A) and silica powder (B) were mixed into A/
A blending ratio of B=2/8 and A/B=8/2 (2 to 100 parts by volume of the resin composition shown in Example 2), respectively.
64 parts by volume (Comparative example-5) 163 parts by volume (Comparative example-6)
Although a filled resin composition was prepared, it did not have fluidity and a test sample could not be prepared. [Effects of the Invention] As detailed above, the epoxy resin composition for casting of the present invention has a cured product with a resistance of 2 times. Its industrial value is extremely high as a casting resin with excellent properties such as hardness, heat resistance, mechanical strength, and low shrinkage.

Margin below

Claims (1)

[Claims] Diameter 3 to 1 per 100 parts by volume of epoxy resin and curing agent
Cut fibers having a distribution of 5 μm and a length of 3 to 300 μm (A) 90% by weight or more of particles with a particle size of 10 μm or less, 5
Two types of fillers, inorganic particles (B) having a particle size distribution of 50% by weight or more and an average particle diameter of 0.5 μm or more, were mixed in 150 parts by volume < A + B < 223 parts by volume, 0. 003(A+B)-0.17≦A/(A+B)≦
An epoxy resin composition for casting, characterized in that it is blended to satisfy the relational expression -0.003(A+B)+1.17.