JP2888661B2 - Casting resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[Object of the Invention]

[0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a casting resin composition, and more particularly to a casting resin composition suitable as an insulating material or a structural material for electric equipment and components.

[0003]

2. Description of the Related Art Among resins used as insulating materials or structural materials for electric devices and parts, epoxy resins are more likely to be used than other thermosetting resins or thermoplastic resins.
It has excellent insulating and mechanical properties, and is widely used as various electrical insulating materials.

In particular, bisphenol A diglycidyl ether (DGEBA) having an average epoxy equivalent of 350 to 550
Molded epoxy resins (hereinafter referred to as solid epoxy resins) are tough and have excellent insulating properties, and thus have a long-term track record as casting resins for large electrical components and structures. However, since these epoxy resins are solid at room temperature, they need to be heated and mixed in order to mix a curing agent and a filler, and there is a problem in workability because the pot life at the mixing temperature is short. Furthermore, since the molecular weight is large, the physical heat resistance (glass transition temperature Tg) of the cured product is low even when a curing agent having high heat resistance is used. Can not meet the demand for improved performance.

In order to improve the heat resistance of the cured product, a low-molecular-weight epoxy resin which is liquid at room temperature (hereinafter referred to as a liquid epoxy resin) may be used. Therefore, it is difficult to produce a large casting without defects. For this reason, based on solid epoxy resin, alicyclic epoxy resin, polyfunctional epoxy resin, cresol novolak resin, etc. are blended as a heat-resistance imparting agent to suppress curing shrinkage,
A method for improving heat resistance is generally used.
(Reference: Epoxy resin, edited by Hiroshi Kakiuchi, Shokodo)
On the other hand, an epoxy resin represented by the following general formula (I)
It is known to have excellent heat resistance and low elastic modulus,
As disclosed in Japanese Patent Application Laid-Open No. 2-102217, there has been an example of studying as a modifier in a molding compound for semiconductor encapsulation. Has not been done.

[0006]

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[0007]

By the way, as described above, when a method of blending a heat resistance imparting agent with a solid epoxy resin to improve the heat resistance of a cured product is adopted,
There are very few types of materials that are excellent in compatibility with solid epoxy resins and suitable as a heat-resistance imparting agent so that good mechanical properties can be obtained in a cured product. Moreover, many of the materials having such properties suitable as a heat-resistance imparting agent increase the reactivity of the resin and shorten the pot life,
Workability often deteriorates.

[0008] In general, an epoxy resin becomes brittle with an increase in heat resistance. In particular, a method of blending a heat-resistance imparting agent with a solid epoxy resin uses a low-molecular-weight epoxy resin. The rate of increase in brittleness in the cured product is greater than in the method for improving the hardness. That is, in a heat-resistant resin composition based on a solid epoxy resin, the cured product has excellent heat resistance, toughness, and mechanical properties, and in particular, an excellent composition that can achieve both high levels of properties regarding the heat resistance and toughness of the cured product. Things have not been realized previously.

As described above, the conventional method, that is, a solid epoxy resin is used as a base, and an alicyclic epoxy resin, a polyfunctional epoxy resin, a cresol novolak resin, etc. are blended as a heat-resistance imparting agent to improve heat resistance. In such a method, the reactivity of the resin is increased and the pot life is shortened, so that the workability is often deteriorated. In addition, compared to a method of improving heat resistance using a low-molecular-weight epoxy resin, the rate of increase in brittleness of the cured product is large, and in particular, it is possible to achieve both high-level properties regarding the heat resistance and toughness of the cured product. There was a problem of not being able to do so.

The present invention has been proposed to solve the above-mentioned problems of the prior art, and its object is to reduce the curing shrinkage, to be suitable for the production of large cast products, and to cure It has excellent heat resistance, toughness, and mechanical properties, and can achieve both high levels of heat resistance and toughness, and has a long pot life, good workability, and excellent solid properties. An epoxy resin-based casting resin composition is provided.

[Structure of the Invention]

[0012]

The resin composition for casting according to the present invention comprises a first epoxy resin having an epoxy equivalent of 350 to 550 having at least two epoxy groups in one molecule, and the following general formula: It is characterized by being compounded with a second epoxy resin represented by (I) and a curing agent for epoxy resin.

[0013]

Embedded image

Further, in addition to the above constitution, a particulate or fibrous filler, alone or in combination, may be blended at 50% by volume or less based on the whole composition.

Further, in the present invention, it is possible to specifically use various components as shown below.

First, as the first epoxy resin used in the present invention, any epoxy resin having at least two epoxy groups in one molecule can be appropriately used, and the type thereof is limited. However, examples thereof include bisphenol A type epoxy resin, bisphenol F type epoxy resin, alicyclic epoxy resin, hydrogenated bisphenol A type epoxy resin, and heterocyclic epoxy resin such as triglycidyl isocyanate and hydantoin epoxy. These resins are used alone or as a mixture of two or more.

Next, the second epoxy resin used in the present invention preferably has an average epoxy equivalent of about 180 to 400. Particularly, the mixing ratio of the first epoxy resin to the first epoxy resin is preferably as follows. 2 moles per 1 mole of resin
It is preferable to mix 0.02 to 0.5 mol of the epoxy resin in terms of balance of heat resistance, toughness, and mechanical properties of the cured product.

Further, as the curing agent for epoxy resin used in the present invention, generally used are aliphatic or aromatic acid anhydrides, carboxylic acids, amines, phenol compounds and novolak resins used for epoxy resins. Can be used alone or in the form of a mixture of two or more. In particular, phthalic anhydride, hexahydrophthalic anhydride, hexahydrophthalic anhydride methylate, tetrahydrophthalic anhydride, which have a long pot life and generate less heat during curing,
Acid anhydrides such as methyltetrahydrophthalic anhydride, nadic anhydride, and methyl nadic anhydride are desirable. Among them, phthalic anhydride and methyl nadic anhydride have a long pot life and a fast curing, so that workability is low. And its cured product properties are also better than when other curing agents are used. The amount of the curing agent for these epoxy resins is 0.7 to 1.
It is preferably in the range of 1 equivalent, and if it is less than this range, the effect of improving the heat resistance of the cured product cannot be sufficiently obtained. On the other hand, if the amount is more than this range, the cured product will have reduced chemical heat resistance and electrical properties.

On the other hand, in the resin composition of the present invention, any kind of filler can be blended as long as the workability is not hindered. For example, as a particulate filler, silica, alumina, talc, calcium carbonate, aluminum hydroxide, kaolin, clay, dolomite, mica powder, silicon carbide, glass powder, carbon, graphite, barium sulfate, titanium dioxide, boron nitride, Silicon nitride or the like can be used. As the fibrous filler, wollastonite, potassium titanate whisker, glass fiber, alumina fiber, silicon carbide fiber, boron fiber,
Carbon fibers, aramid fibers, phenol fibers, metal whiskers and the like can be used. These fillers
Used alone or as a mixture of two or more. Among them, alumina is excellent in adhesiveness to the epoxy resin used in the present invention. In particular, by using alumina having an average particle diameter of 1.0 to 20 μm as a filler, acid resistance, thermal conductivity, and mechanical properties are improved. A heat-resistant resin with excellent strength can be obtained. The total amount of the filler was 35% by volume based on the whole composition.
As described above, it is desirable to mix as needed, and if it becomes 35% by volume or less, it becomes impossible to obtain a necessary elastic modulus as a structure. On the other hand, when the total amount of the filler exceeds 55% by volume, the viscosity is significantly increased, and the casting operation becomes difficult.

Incidentally, in the resin composition of the present invention, various additives can be blended as required.
For example, additives such as a flame retardant, an antioxidant, a pigment, and a dye can be blended.

[0021]

The resin composition of the present invention having the above-mentioned constitution can be easily produced by mixing and stirring the above-mentioned components in a usual manner. In addition, the resin composition of the present invention has a longer pot life at a temperature of 100 to 120 ° C. than a conventional solid epoxy resin-based resin composition, and at a rate equal to or higher than that of the conventional resin composition. Workability is very good because of curing. further,
The mechanical strength, insulation properties, and crack resistance levels with respect to heat resistance of the cured product exceed the levels of conventional solid epoxy resins in all aspects. In addition, the resin composition of the present invention has a low viscosity of the clear resin and a high filling of the filler, so that the curing shrinkage can be extremely small, and as a sealing material for a large casting or semiconductor. Useful.

[0022]

EXAMPLES Examples of the resin composition for casting according to the present invention and comparative examples according to the prior art are shown below, and the effects of the present invention will be described in more detail by comparative evaluation of these examples and comparative examples. explain. In all Examples and Comparative Examples, the first epoxy resin (solid epoxy resin) as a base was a bisphenol A type epoxy resin (manufactured by Ciba Geigy: CT200, epoxy equivalent 3
90) was used. Further, as the second epoxy resin as a heat resistance imparting agent and the curing agent for the epoxy resin, those individually described in each column of the following Examples and Comparative Examples were used. And, these materials, basically, 100 ℃ ~
After vacuum-mixing at 120 ° C., the test piece was cast into a mold, vacuum degassed again, primary cured in a mold under predetermined conditions, and secondary cured after release to obtain a test piece.

Example 1 Solid epoxy resin (CT20)
0) 25 parts by weight of an epoxy resin (trade name: YX4000, manufactured by Yuka Shell Epoxy Co., Ltd.) having a structure of n = 0 in the general formula (I) is used as the second epoxy resin with respect to 100 parts by weight. As a curing agent, methyl hexahydrophthalic anhydride (trade name: HN-5500, manufactured by Hitachi Chemical Co., Ltd.)
0.9 equivalent was used with respect to the whole epoxy resin. In addition, 0.005 mol of tris-2,4,6-dimethylaminomethylphenol (trade name: K-54, manufactured by Yuka Shell Co., Ltd.) was used as a curing accelerator. Primary curing at 110 ° C for 1
The test was performed for 5 hours, and the secondary curing was performed at 150 ° C. for 15 hours.

Example 2 Solid epoxy resin (CT20)
0) 25 parts by weight of an epoxy resin (trade name: YX4000, manufactured by Yuka Shell Epoxy Co., Ltd.) having a structure of n = 0 in the general formula (I) is used as the second epoxy resin with respect to 100 parts by weight. As a curing agent, phthalic anhydride (HT901, manufactured by Ciba Geigy) was used in an amount of 0.8 equivalent to the entire epoxy resin. The primary curing was performed at 120 ° C. for 15 hours, and the secondary curing was performed at 150 ° C. for 15 hours to produce a test piece.

Example 3 Solid epoxy resin (CT20)
0) With respect to 100 parts by weight, 15 parts by weight of an epoxy resin (average epoxy equivalent: 340) having a structure of n = 1 in the general formula (I) is used as a second epoxy resin, and anhydrous is used as a curing agent. Phthalic acid (HT901, manufactured by Ciba-Geigy)
Was used in an amount of 0.9 equivalent to the entire epoxy resin. The primary curing was performed at 120 ° C. for 15 hours, and the secondary curing was performed at 150 ° C. for 15 hours to produce a test piece.

Example 4 The resin composition described in Example 1 was mixed with 350 parts by weight of particulate alumina (manufactured by Showa Denko KK; average particle size: 12 μm) as a filler, and cured under the same curing conditions as in Example 1. A test piece was prepared.

Example 5 320 parts by weight of particulate alumina (manufactured by Taiheiyo Random Co., Ltd., average particle size: 10 μm) were added to the resin composition described in Example 2 as a filler, and the same curing conditions as in Example 2 were used. A test piece was prepared.

Example 6 To the resin composition described in Example 3, 250 parts by weight of particulate alumina (manufactured by Taiheiyo Random Co., Ltd., average particle size: 10 μm) was blended as a filler, and cured under the same curing conditions as in Example 3. A test piece was prepared.

On the other hand, a composition generally used as a large-sized cast insulating resin is adopted as a comparative example according to the prior art with respect to the embodiment according to the present invention as described above.
Test pieces were prepared under the following conditions.

Comparative Example 1 As an epoxy resin, bisphenol A type epoxy resin (CT2, manufactured by Ciba-Geigy)
85 parts by weight of epoxy equivalent (390) and 15 parts by weight of an alicyclic epoxy resin (CY175, manufactured by Ciba-Geigy), and 30 parts by weight of phthalic anhydride (HT901, manufactured by Ciba-Geigy) as a curing agent. . The primary curing was performed at 120 ° C. for 15 hours, and the secondary curing was performed at 150 ° C. for 15 hours to produce a test piece.

Comparative Example 2 As an epoxy resin, a bisphenol A type epoxy resin (CT2, manufactured by Ciba-Geigy)
90, 90 parts by weight of epoxy equivalent (390), and 10 parts by weight of an alicyclic epoxy resin (CY179, manufactured by Ciba-Geigy), and 30 parts by weight of phthalic anhydride (HT901, manufactured by Ciba-Geigy) as a curing agent. . The primary curing was performed at 120 ° C. for 15 hours, and the secondary curing was performed at 140 ° C. for 15 hours to produce a test piece.

Comparative Example 3 320 parts by weight of particulate alumina (manufactured by Taiheiyo Random Co., Ltd., average particle size: 10 μm) were blended with the resin composition described in Comparative Example 1 as a filler, and the mixture was mixed with a universal mixer to form 110 to 110 parts by weight. The resin composition vacuum-mixed at 120 ° C. is cast into a mold preheated to 120 ° C., and primary curing is performed for 1 hour.
The test was performed at 20 ° C. for 15 hours, and the secondary curing was performed at 150 ° C. for 15 hours.

(Comparative Example 4) 250 parts by weight of particulate alumina (manufactured by Taiheiyo Random Co., Ltd., average particle size: 10 μm) was blended with the resin composition described in Comparative Example 2 as a filler, and the mixture was mixed with a universal mixer to form 110 to 110 parts by weight. The resin composition vacuum-mixed at 120 ° C. is cast into a mold preheated to 120 ° C., and primary curing is performed for 1 hour.
A test piece was prepared by performing the curing at 20 ° C. for 15 hours and the secondary curing at 140 ° C. for 15 hours.

The evaluation results of the test pieces of the resin compositions prepared in Examples 1 to 6 and Comparative Examples 1 to 4 are shown in Tables 1 to 3.
Shown in Among the various properties shown in these tables, the glass transition temperature was measured using a differential scanning calorimeter (DSC).
The thermal shock resistance was measured by the M20 flat washer method. Further, the mechanical properties were measured according to JIS-K-6911, and the fracture toughness value was measured according to ASTM E3.
It was determined according to 99-83.

[0035]

[Table 1]

[0036]

[Table 2]

[0037]

[Table 3]

As is clear from the above table, the examples of the present invention are superior to the comparative example according to the prior art in heat resistance, toughness, and mechanical properties. It is possible to achieve a high level of compatibility in heat resistance and toughness that could not be obtained, and to obtain an excellent casting resin composition having a long pot life and good workability.

It should be noted that the resin composition according to the present invention is not limited to the above-mentioned examples, and various kinds of materials can be selectively used as described in the section of means for solving the problems. Also in this case, excellent operational effects can be obtained as in the above embodiment.

[0040]

As described above, in the present invention,
As the epoxy resin for the heat resistance imparting agent, the above-mentioned general formula (I)
By using a certain epoxy resin as represented by, compared with the conventional, less curing shrinkage, suitable for the production of large cast products, and heat resistance, toughness, and mechanical properties of the cured product Excellent solid epoxy resin-based casting resin composition with excellent properties, especially high heat resistance and toughness, can achieve both high levels of properties, long pot life, and good workability Can be provided.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masafumi Takei 2-1 Ukishima-cho, Kawasaki-ku, Kawasaki-shi, Kanagawa Prefecture Inside the Hamakawasaki Plant, Toshiba Corporation (72) Inventor Ichiro Ichikawa 21-4 Hiromasa-cho, Tsurumi-ku, Yokohama-shi, Kanagawa Toshiba Chemical Corporation Irifune Office (72) Inventor Yasuhisa Kanashi 21-4 Kanseicho, Tsurumi-ku, Yokohama-shi, Kanagawa Prefecture Toshiba Chemical Corporation Irifune Office (56) References JP-A-2-103220 (JP, A) JP-A-2-255828 (JP, A) JP-A-61-47725 (JP, A) JP-A-2-91118 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) ) C08G 59/20-59/38 C08L 63/00-63/10 B29C 39/00-39/44

Claims (2)

(57) [Claims] 1. A first epoxy resin having an epoxy equivalent of 350 to 550 having at least two epoxy groups in one molecule, a second epoxy resin represented by the following general formula (I), A resin composition for casting, comprising a curing agent for a resin. Embedded image 2. The casting resin according to claim 1, wherein a particulate or fibrous filler is compounded alone or in a composite at 50% by volume or less based on the whole composition. Composition.