JP2007059335A - Electrical insulation material and cast molding - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electric insulating material capable of improving electric characteristics such as breakdown voltage characteristics, and a cast molding molded by using the material. <P>SOLUTION: The electric insulating material comprises a thermoset matrix resin 1 constituted of a thermoset resin and a hardening agent, inorganic filling materials 2, 3 of an oval shape having particle size distributions of two kinds or more, and rubber particles 4 having a core shell structure. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electrical insulating material capable of improving electrical characteristics and a cast product cast using the material.

  Epoxy resins have excellent mechanical properties, electrical properties, chemical properties, thermal properties, and the like, and are therefore used as electrical insulating materials in heavy electrical fields, semiconductor fields, and the like. Examples thereof include an epoxy resin casting material for producing a casting such as a bushing used for an electrical device such as a switch gear, an epoxy resin sealing material for sealing an electrical component, and the like.

Conventionally, an electrical insulating material using this kind of epoxy resin material is filled with an optimal amount of spherical particles having a diameter of about 10 μm and a diameter of several μm and rubber particles having a core-shell structure in an epoxy resin. It is known that the material has a balanced property. Of these, materials filled with spherical silica having two or more types of particle size distributions are less likely to increase in viscosity even when mixed at a high filling rate in an epoxy resin, facilitating the manufacture of cast products. it can. In addition, filling rubber particles tends to improve toughness, but tends to reduce mechanical strength such as bending strength. However, filling with spherical silica having two or more particle size distributions increases this mechanical strength. (See, for example, Patent Document 1).
JP 2002-15621 A (pages 3 to 6, FIG. 1)

  In the above-mentioned conventional electrical insulating material, it is a material that is well-balanced in each characteristic such as mechanical characteristics, electrical characteristics, chemical characteristics, and thermal characteristics. Further, it has been desired to further improve the breakdown voltage characteristics. If the breakdown voltage characteristics are improved, the insulation thickness can be reduced particularly for cast products used in high voltage electrical equipment, leading to miniaturization.

  The present invention has been made to solve the above-described problem, and an object thereof is to provide an electrically insulating material capable of improving electrical characteristics such as breakdown voltage characteristics and a cast product cast using the material. To do.

  In order to achieve the above object, the electrical insulating material of the present invention includes a thermosetting matrix resin composed of a thermosetting resin and a curing agent, and an elliptical inorganic filler having two or more types of particle size distributions. And rubber particles having a core-shell structure.

  According to the present invention, since the thermosetting matrix resin is filled with the elliptical silica having two or more kinds of particle size distributions, the breakdown voltage characteristics can be improved and manufactured using the electrically insulating material. It is possible to reduce the size of cast products.

  Embodiments of the present invention will be described below with reference to the drawings.

  An electrical insulating material according to an embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a conceptual diagram showing a configuration of an electrical insulating material according to an embodiment of the present invention. FIG. 2 is an electrode arrangement diagram for determining a breakdown voltage of the heat-cured electrical insulating material according to the embodiment of the present invention. These are the figures explaining the destruction path | route of the destruction voltage calculated | required in FIG.

  As shown in FIG. 1, the electrical insulating material includes a thermosetting matrix resin 1 composed of a thermosetting epoxy resin and a curing agent such as a modified acid anhydride or an amine curing agent. Filled with elliptical (egg-like) large-diameter silica 2 and small-diameter silica 3 having two or more types of particle size distribution as inorganic filler, and rubber particles 4 having a core-shell structure with special chemical modification on the outside Have been mixed. The composition of this electrically insulating material was prepared as follows.

(Example)
(1) Bisphenol epoxy resin (100 parts by weight)
Breakdown: Bisphenol A epoxy resin (epoxy equivalent 180, 50 parts by weight)
Bisphenol F epoxy resin (epoxy equivalent 180, 50 parts by weight)
(2) Methyl nadic acid anhydride (curing agent, 95 parts by weight)
(3) Elliptical silica (Silane coupling treatment completed, 380 parts by weight)
Breakdown: Large particle size silica (average particle size 15 μm, long diameter / short diameter = 1 over 2 or less, 360 parts by weight)
Small particle size silica (average particle size 0.8μm, major axis / minor axis = 1 over 2 and under 20 parts by weight)
(4) Rubber particles (styrene-butadiene-methacrylic acid copolymer having an average particle size of 0.3 μm, 10 parts by weight)
Here, the large particle diameter silica 2 has a particle diameter of 0.5 to 30 μm on the long diameter side (this range is defined as an average particle diameter of 15 μm) and can be filled in 50 to 80 wt%. The small particle size silica 3 has a long particle size of 0.1 to 3 μm (this range is defined as an average particle size of 0.8 μm) and can be filled in an amount of 2 to 20% by weight. As shown in FIG. 1, both the large particle size silica 2 and the small particle size silica 3 have the longer elliptical shape (egg-like) as the major axis, the shorter one as the minor axis, and the major axis / minor axis = 1 exceeding. It does not become a true sphere. In addition, when the major axis / minor axis = 2 or more, when mixed in the epoxy resin, the major axis side may break, and the broken part becomes an acute angle, which is not preferable. Such an elliptical shape can be obtained, for example, by changing the rate (time and temperature) of cooling silica melted at a high temperature when producing fused silica by a gas phase method.

  The rubber particles 4 have a particle size of 0.2 to 1.2 μm (this range is an average particle size of 0.3 μm) and can be filled at 5 to 20% by weight.

  For comparison, an electrical insulating material having the following composition was used. This is similar to the conventional electrical insulating material.

(Comparative example)
(1) Bisphenol epoxy resin (100 parts by weight)
Breakdown: Bisphenol A epoxy resin (epoxy equivalent 180, 50 parts by weight)
Bisphenol F epoxy resin (epoxy equivalent 180, 50 parts by weight)
(2) Methyl nadic acid anhydride (95 parts by weight)
(3) Spherical silica (Silane coupled, 380 parts by weight)
Breakdown: Large particle size silica (average particle size 15 μm, 360 parts by weight)
Small particle size silica (average particle size 0.8μm, 20 parts by weight)
(4) Rubber particles (styrene-butadiene-methacrylic acid copolymer having an average particle size of 0.3 μm, 10 parts by weight)
The breakdown voltage characteristics of the above-described examples and comparative examples were examined. Samples were added to each electrical insulating material with an amine-based curing accelerator used in general epoxy resin casting materials, injected into a mold, first cured at a temperature of 80 ° C. for 15 hours, and then heated to a temperature of 150 The secondary curing was performed at 15 ° C. for 15 hours.

  As shown in FIG. 2, the breakdown voltage is measured between the spherical electrode 5 having a diameter φ1 = 25 mm and the cylindrical electrode 6 having a diameter φ2 = 35 mm (the end is processed to have a radius of curvature R = 2 mm) by the method described above. The test insulation plate 7 having an insulation thickness t = 1 mm was sandwiched between the electrodes 5 and 6 and an AC voltage was applied between the electrodes. The pressure increase rate is 600 V / second, and the number of samples is 10 each.

The results are shown in Table 1.

  From Table 1, in the example, the breakdown voltage was 64 kV / mm, which was higher than the breakdown voltage 61 kV / mm of the comparative example. The standard deviation was almost the same as 3 to 4 kV / mm in both Examples and Comparative Examples.

  When the dielectric breakdown surface of the sample filled with elliptical silica is observed, as shown in FIG. 3, the breakdown path A follows the interface between the large particle size silica 2, the small particle size silica 3 and the thermosetting matrix resin 1. Is progressing as well. This is probably because the fracture path A is extended by the elliptical large particle size silica 2 and the small particle size silica 3 to improve the breakdown voltage.

  By using the elliptical silica as described above, the breakdown voltage characteristics can be improved. Therefore, the breakdown voltage characteristics can be improved even in cast products such as bushings manufactured using this material. And in the electrical equipment using this cast product, the overall shape can be reduced.

  In addition, those filled with elliptical silica have similar mechanical properties such as tensile properties and bending properties, and properties such as glass transition temperature, which is an index of heat resistance, compared to conventional ones (comparative examples). there were.

  According to the electrical insulating material of the above embodiment, the inorganic filler to be filled in the thermosetting matrix resin 1 is the large particle size silica 2 and the small particle size silica 3 having two or more kinds of particle size distributions having an elliptical shape. The breakdown voltage characteristics can be improved, and the cast product manufactured using this material can be reduced.

  In addition, this invention is not limited to the said Example, In the range which does not deviate from the summary of invention, it can implement in various deformation | transformation. In the above embodiment, the epoxy resin is used for the thermosetting matrix resin 1. However, even if a thermosetting resin such as a phenol resin, a urethane resin, or a polyamide resin is used, it is destroyed by filling with elliptical silica. The voltage characteristics can be improved.

The conceptual diagram which shows the structure of the electrically insulating material which concerns on the Example of this invention. The electrode arrangement | positioning figure which calculates | requires the breakdown voltage of the heat-hardened electrically insulating material which concerns on the Example of this invention. The figure explaining the destruction path | route of the destruction voltage calculated | required in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Thermosetting matrix resin 2 Large particle size silica 3 Small particle size silica 4 Rubber particle 5 Spherical electrode 6 Cylindrical electrode 7 Test insulation board

Claims (5)

A thermosetting matrix resin composed of a thermosetting resin and a curing agent;
An elliptical inorganic filler having two or more particle size distributions;
An electrically insulating material comprising a rubber particle having a core-shell structure. The inorganic filler is made of fused silica,
2. The electrical insulating material according to claim 1, wherein the ratio of the major axis / minor axis of the ellipse is more than 1 and 2 or less.   3. The electrical insulating material according to claim 1, wherein the inorganic filler has a particle size distribution with an average particle size of 15 μm and an average particle size of 0.8 μm.   The electrically insulating material according to any one of claims 1 to 3, wherein the thermosetting resin is a bisphenol-based epoxy resin. A thermosetting matrix resin composed of a thermosetting resin and a curing agent;
An elliptical inorganic filler having two or more particle size distributions;
A cast product characterized by being cast with an electrically insulating material having a rubber particle having a core-shell structure.

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