JPH03157420A - Thermosetting epoxy resin composition, casting material of epoxy resin and mold coil - Google Patents

Abstract

PURPOSE:To obtain the title composition providing mold coil by molding, having excellent crack resistance, resin strength, high-voltage characteristics, fluidity and storage stability, comprising an epoxy resin, acid anhydride and epsilon- caprolactone monomer. CONSTITUTION:The objective composition comprising (A) an epoxy resin (e.g. bisphenol A type epoxy resin), (B) an acid anhydride (e.g. tetramethylene maleic anhydride) and (C) an epsilon-caprolactone monomer. The composition is mixed with an inorganic filler (preferably inorganic powder having 0.05-5mum average particle diameter or inorganic short fiber having 3-20mum diameter and 3-300mum length) to give a casting material, which is molded to give mold coil.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a thermosetting epoxy resin composition, an epoxy resin casting material, and a molded coil.

(Prior Art) Epoxy resin compositions are particularly important for electrical insulation due to their excellent characteristics such as mechanical properties, electrical insulation properties, and adhesive properties. Furthermore, in recent years, with the increase in the size of electrical equipment and the increase in the number of products integrally molded with complex components, there has been an increasing demand for improved crack resistance, especially for insulation of high-voltage electrical equipment. In particular, for high-voltage bushings and high-voltage coils, it is essential that corona discharge does not occur below the specified voltage, so void-free, adhesion, or adhesive properties are required, and in addition, repeated cooling and heating cycles without operation are required. Scratch resistance, peeling resistance, etc. are required to withstand thermal distortion caused by heat distortion.

Although various methods for improving crack resistance and the like are known, the methods are limited to cast molding methods using liquid resin.

Namely, these methods include (1) lowering the glass transition temperature by adding a flexibility-imparting material, (2) using a flexible epoxy resin, and (2) increasing the filler content.

However, these methods have not yet resulted in a satisfactory solution due to problems such as a decrease in heat resistance, a decrease in molded product strength, and a decrease in fluidity, which is important for manufacturability.

On the other hand, regarding curing agent components, amine-based curing agents were traditionally used frequently, but in recent years, acid anhydride-based curing agents have been increasingly used due to toxicity issues. Since the cured product is hard and has lower crack resistance than amine-based products, further improvement has been desired.

(Problems to be Solved by the Invention) The present invention was made to solve the above problems, and is effective when an acid anhydride is used as a curing agent.
We provide thermosetting epoxy resin compositions and epoxy resin casting materials that have excellent crack resistance, toughness, and excellent manufacturability, and we also provide high-voltage products molded using this epoxy resin casting material. The purpose is to provide molded coils.

[Structure of the invention] (Means and effects for solving the problem) The present invention has been made to achieve the above-mentioned objects, and includes (a) an epoxy resin, (b) an acid anhydride, ( c) ε-caprolactone monomer.

In addition, the present invention provides the above (a), (b), and (c),
Furthermore, it is an epoxy resin casting material characterized by adding <d) an inorganic filler.

Furthermore, the present invention is a molded coil characterized by being molded using the above-mentioned epoxy resin casting material.

The epoxy resin used in the present invention may be any resin commonly known as epoxy, such as bisphenol A type epoxy resin, bisphenol F type epoxy resin, etc.
type epoxy resins, novolac type epoxy resins, alicyclic epoxy resins, hydrogenated bisphenol A type epoxy resins, and heterocyclic epoxy resins such as triglycidyl isocyanate and hydantoin epoxy, but in particular 30
It is preferable to use an epoxy resin that is liquid at °C.

As a specific example, in the case of bisphenol A type epoxy resin, Ep:cote815.819 manufactured by Shell Chemical Co., Ltd.
827°828, GY250.252.28 manufactured by Ciba
0, DER330, 331, 332 manufactured by Dow, R-140 manufactured by Mitsui Oil Company. Examples include R-140P.

In addition, in the case of alicyclic epoxy resin, Tisonox 2
01,221,21119, Araldite CY175
, 178.179, etc. These resins may be used alone or as a mixture of several types.

- The acid anhydride that is the hardening agent used in the strength wood invention may be of any kind, but is preferably an acid anhydride that is liquid at 30°C. Specific examples include tetramethylene maleic anhydride, methyltetrahydrophthalic anhydride (B-570 manufactured by Dainippon Ink, HN-2200 manufactured by Hitachi Chemical),
Methylendomethylenetetrahydrophthalic anhydride (Kayahard MCD manufactured by Nippon Kapaku Co., Ltd., HMA manufactured by Hitachi Chemical Co., Ltd.)
C) In addition to methylnadic anhydride (HY9013'' manufactured by Nippon Ciba-Geigi Co., Ltd.) and 4-methylhexahydrophthalic anhydride (Ml-700 manufactured by Shin-Nippon Chemical Co., Ltd.), HY905 manufactured by Nippon Ciba-Geigi Co., Ltd. as a modified acid anhydride. ,915
, 917, 919, 920, and Ebicure 103, 121.136 manufactured by Yuka Shell Co., Ltd. These acid anhydrides may be used alone or as a mixture of several types.

Further, the ε-caprolactone monomer used in the present invention is obtained by oxidizing cyclohexanone with hydrogen peroxide, peracetic acid, etc. by Bayer pyrolysis reaction, and is also manufactured and sold industrially. (For example, Daicel Chemical Co., Ltd., Plaxel-Set, etc.) The ε-caprolactone used in the present invention particularly needs to be a monomer. In the case of monomers, they have excellent compatibility with acid anhydrides and epoxy resins, have low viscosity, and can stably exist until the acid anhydride and epoxy begin to react.

The relationship among these (a) epoxy resin, (b) acid anhydride, and (c) ε-caprolactone monomer, which are essential components of the thermosetting epoxy resin of the present invention, can be considered as follows. In other words, if ε-caprolactone monomer has a hydroxyl group, it easily opens the ring and reacts, but acid anhydrides and liquid epoxy resins do not react because they have almost no hydroxyl groups, and remain stable in the resin for a long period of time. Can be done. During curing, hydroxyl groups are first generated by the reaction between acid anhydride and epoxy, and ε-caprolactone undergoes a ring-opening reaction with the generated hydroxyl groups, extending in a straight line and having a hydroxyl group at the end. It is thought to react with substances and epoxy. Therefore, as the amount of ε-caprolactone monomer added increases, the average molecular weight between crosslinking points increases and the second-order transition temperature decreases, but at the same time thermal stress is alleviated, resulting in the effect of improving crack resistance. On the other hand, this ε
-Caprolactone monomer has a low viscosity (6 to 6 at 20°C)
7 cp), and has excellent compatibility with acid anhydrides and epoxy resins, and also has the function of lowering the viscosity of the entire resin and making it possible to increase the amount of filler.

In the present invention, (a) per mole of epoxy resin, (b) acid anhydride is 0.3 to 1.5 mole, (c) ε-caprolactone monomer is 0.05 to 0.8 mole, and , (b) acid anhydride in a proportion of 0.5 to 1.2 mole, and (c) ε-caprolactone monomer in a proportion of preferably 0.1 to 0.5 mole. This is 0.05 for ε-caprolactone.
This is because if the amount is less than 0.8 mol, the effect on crack resistance will be poor, and if it exceeds 0.8 mol, the glass transition temperature will be extremely lowered and the strength will be lowered.

Although boric anhydride is related to the ε-caprolactone monomer, if the amount is less than 0.3 mol, the glass transition temperature decreases by 1 mol.
．． If the amount is more than 5 moles, the strength will be significantly lowered, so it is preferable to keep it within the above-mentioned range.

Furthermore, in addition to the above three essential components, a catalyst may be added to promote the curing reaction. The catalyst used may be any compound that is generally used as a catalyst for epoxy resins, such as 2-methylimidazole, 2-ethyl-4-methylimidazole, 1-cyanoethyl-2-ethylmethylimidazole. , imidazole compounds such as benzyldimethylamine, amine compounds such as trisdimethylaminomethylphenol, organic phosphine compounds such as triphenylphosphine, tricyclohexylphosphine, tributylphosphine, diazabicycloundecene and its salts, metal acetyl Examples include acetonatochelate compounds.

In addition, by adding (d) an inorganic filler to the above-mentioned (a) epoxy resin, (b) acid anhydride, and (c) ε-caprolactone monomer, we have created an epoxy resin suitable for use in high-voltage electrical equipment insulation. A resin casting material is obtained.

Examples of the inorganic filler (d) used in the present invention include various known inorganic fillers such as quartz powder, fused silica powder, glass powder, glass fiber, various whiskers, and ceramic powders such as talc, silicon nitride, and aluminum nitride. Can be used.

Particularly from the viewpoint of crack resistance and electrical insulation, it is preferable to use a composite filler consisting of a combination of inorganic short fibers, especially glass short fibers, and inorganic powder, especially silica powder (crystalline or fused type).

It is particularly preferable to use short glass fibers having a distribution of 3 to 20 μm in diameter, 3 to 300 μm in length, and 2 to 20 in average aspect ratio as the inorganic short fibers that are a component of the composite filler. Specific examples include Micro Glass Surf Knee Strand REV-1 and REV-4 manufactured by Nippon Sheet Glass Co., Ltd.
, REV-6, REV-7, REV-8, etc. In addition, inorganic powders such as silica powder have an average particle size of 0.
．． The thickness is preferably 0.05 to 5 μm.

The blending ratio of these inorganic short fibers (x) and inorganic powder (y) is x/x+y-0.2 to 0.7, preferably 0.4
~0.6. The reason for this is that within this range, the viscosity is low and the fluidity is excellent.

In the present invention, the compounding amount of the composite filler is 100 parts by weight per 100 parts by weight of the total amount of resin components (a+b+c).
00 parts by weight, more preferably 100 to 400 parts by weight. If it is less than 100 parts by weight, the mechanical properties and crack resistance of the cured product will be insufficient, while if it exceeds 500 parts by weight, the viscosity of the resin composition will be high and fluidity will be reduced, which is not desirable. In addition to the composite filler used in the present invention, an appropriate amount of inorganic filler such as alumina, talc, and wollastonite, or coarse particle silica with an average particle size exceeding 5 μm may be added to the extent that fluidity is not impaired. You may also use it.

Furthermore, in the epoxy resin casting material of the present invention, a latent catalyst may be used as a curing accelerator. This latent catalyst has its surface treated chemically or physically, or its functional groups are chemically blocked so that its catalytic function becomes activated at a certain temperature or higher. Specifically, Asahi Kasei Co., Ltd. (7) IIX-3722, llX-374
1,llX-3742, manufactured by Ajinosakusha (7) MY-24
etc. can be mentioned. The amount of the curing accelerator used is preferably 0.1 to 5 parts by weight per 100 parts by weight of the epoxy resin.

In addition, in the present invention, colorants, surfactants,
Additives such as coupling agents may also be used.

(Example) Examples 1 to 10. Comparative Examples 1 to 2 The materials shown in Table 1 were blended in the proportions (parts by weight) shown in the table and mixed uniformly in a vacuum (1 to 3 a+ml 1 g) stirring vessel to produce a thermosetting epoxy resin composition of the present invention. and an epoxy resin casting material was prepared. Here, the epoxy resin is bisphenol A type EP82g (manufactured by Shell Chemical Co., Ltd.),
Acid anhydride is 4-methylhexahydroic anhydride M11-7
00 (manufactured by Shin Nihon Rika Co., Ltd.), the ε-caprolactone monomer was Plaxel-M (manufactured by Daicel Chemical Co., Ltd.), and the catalyst was microencapsulated to form a latent catalyst! ! X-3
741 (manufactured by Asahi Kasei Corporation) and benzyldimethylamine (BDMA).

In addition, as Comparative Example 1.2, a composition containing no ε-caprolactone monomer was also prepared in the same manner. After measuring the viscosity of these compositions, they were poured into a mold preheated to 100°C, defoamed under reduced pressure (1 to 3 mm/g), and then heated to 120°C.
The mixture was cured at 150° C. for 2 hours and then at 150° C. for 10 hours to obtain a molded product.

Using these cured products, bending strength, secondary transition point, crack resistance, etc. were evaluated. The results are also listed in Table 1. The evaluation methods for each are as follows.

(1) Viscosity After adjusting the resin temperature in a Nigarasu tall beaker, measure the value for 1 minute using a B-type viscometer.

(2) Gelation time: A test tube with an inner diameter of 18 mm and a length of 180 mm was filled with resin to a height of 100 am, and the test tube was immersed in oil adjusted to 120°C to measure the gelation time of the resin.

(3) Storage stability The resin was sealed in a Nigarasu tall beaker and immersed in a 40°C water tank, and the end point was determined to be the time when the viscosity reached twice its initial value.

(4) Secondary transition point: Approximately 4mm x 4mm x 1 from the molded product
A test piece of g+om was cut out, annealed at 150°C for 10 minutes, and the thermal expansion was measured at a heating rate of 5°C/min under a load of 3g to determine the point of inflection.

(5) Bending strength: 100X10X Four test pieces were prepared and measured according to JIS K 6911. (Average of 10 samples) (6) Crack resistance index Measured according to the Niori lift washer method (Industrial Materials VO1129, N [L5°P59.1981). (Average of 5 samples) (7) Model coil: Major axis 50cm, minor axis 26cIIl
A model coil made of an All conductor (space factor: 80%) was molded.

(8) Cold-thermal cycle: liquid phase θ'CX1h-too℃
(9) Ten cycles of Xlh were performed.

Corona starting voltage: Charge up to 33kV and discharge charge (C
8V) I PC temperature setting.

(Leaving space below) Looking at the Examples and Comparative Examples in Table 1, Examples 3 to 5 in which ε-caprolactone monomer was blended had a particle composite filler and were almost the same as the Comparative Examples, but the viscosity decreased, Furthermore, both bending strength and crack resistance index have been significantly improved. Further, when the filler is composited with short glass fibers and silica particles, Examples 6 to 1 are obtained.
It exhibits high strength and excellent crack resistance as shown in (o).

In particular, when the short glass fiber is 180 parts by weight or more, the crack resistance index is 18 or more (170"C - 75°C liquid phase) and no cracks occur. Also, the corona 13F of the model coil
The J-voltage was evaluated based on the value of the discharge charge m1Pc, and in the example, no corona was generated up to 33 kV, which is excellent. This can be presumed to be because the resin has high toughness and Ap adhesion is also excellent.

On the other hand, in the comparative example, the corona initiation voltage was low due to peeling or fine cracks, and cracks occurred during the cooling/heating cycle.

Furthermore, in order to confirm the effect of the composite filler in the present invention, tests were conducted under the following conditions.

First, 100 parts by weight of EP828 (product name: Nigel Chemical Co., Ltd.) as an epoxy resin, silica 5X (product name: wr1, manufactured by Morisha) with an average particle size of 1 μm as a filler, and a diameter of 13 μm.
250 parts by weight of a composite filler consisting of short glass fibers (prototype manufactured by Nippon Sheet Glass Co., Ltd.) with an average fiber length of 70 μm was added. By changing the blending ratio of both fillers, the viscosity at 80℃ is B.
The results measured using a type viscometer are shown in FIG. Compared to a single filler, a composite filler causes a greater decrease in viscosity, with a minimum value at about 50%, and a particularly stable low viscosity region exists within this wide range of about 50±1O%.

The curing accelerator in the present invention can be any one that can be used for epoxy resins and acid anhydrides, but latent curing accelerators (for example, microcapsule type (IIX-3741, etc.) manufactured by Asahi Kasei Co., Ltd.) can be used. By using , it is possible to provide a liquid casting resin that has long-term storage stability, excellent workability, crack resistance, and high strength.

Further, the application is not limited to high voltage molded coils, etc., but considering the excellent characteristics of the present invention, it can also be applied to liquid semiconductor sealing resin, surface mounting resin, etc.

[Effects of the Invention] As detailed above, the thermosetting epoxy resin composition and epoxy resin casting material of the present invention improve physical properties such as crack resistance and resin strength, as well as improve partial discharge inception voltage. It also has good high voltage characteristics. In addition, it has excellent fluidity and storability related to productivity, so it can be widely applied to applications such as complex-shaped objects and integrally cast products containing metal, etc.
Its industrial value is extremely large. Moreover, a molded coil molded using these materials has the above-mentioned characteristics and has high performance.

[Brief explanation of the drawing]

FIG. 1 is a characteristic diagram showing the relationship between the compounding ratio of the composite filler and the viscosity of the resin composition. Figure 1

Claims (5)

[Claims] (1) (a) epoxy resin; (b) an acid anhydride; (c) ε-caprolactone monomer A thermosetting epoxy resin composition characterized by: (2) An epoxy resin casting material characterized by adding (d) an inorganic filler to the thermosetting epoxy resin composition according to claim (1). (3) (d) Inorganic filler has an average particle size of 0.05 to 5 μm
inorganic powder and diameter 3-20μm length 3-300μ
The epoxy resin casting material according to claim 2, wherein the epoxy resin casting material is a composite filler made of inorganic short fibers having a distribution of m. (4) The epoxy resin casting material according to claim (2), characterized in that a latent catalyst is added as a curing accelerator. (5) A molded coil characterized by being molded using the epoxy resin casting material according to claim (3).