Mold resin for power receiving and distributing devices, power receiving and distributing device, and method for manufacturing power receiving and distributing device

Abstract

A starting material liquid of a mold resin includes: a base agent liquid that mainly composed of an epoxy resin and a silica; a curing agent liquid that is mainly composed of an acid anhydride and the silica; and a reactive diluent liquid that is mainly composed of a radical monomer and a copolymerization agent.

Description

Molding resin for power receiving and distribution device, power receiving and distribution device, and method for manufacturing power receiving and distribution device

[0001] The present invention relates to a molding resin for a power receiving and distribution device, a power receiving and distribution device, and a method for manufacturing the power receiving and distribution device.

[0002] Thermosetting resins are preferred for molding resins used in power distribution equipment due to their heat resistance and durability. Thermosetting resins are molded into the desired shape by increasing the temperature, so they are usually in a liquid or gel state at room temperature. However, when the ambient temperature rises, the viscosity of liquid resins decreases, and the solid components (fillers) contained within can settle.

[0003] The settled filler was originally contained in the resin liquid, and should have been included in the cured resin when the resin liquid was cured.

[0004] Therefore, the physical properties of the cured product may differ from the original design values, causing problems in product performance. Furthermore, the settled filler is often silica or alumina, and once settled, it solidifies at the bottom of the container and becomes integrated with the container, which requires the container to be disposed of as industrial waste, increasing costs.

[0005] Therefore, measures are taken to suppress filler settling during storage by adjusting the viscosity of the resin liquid. Related techniques include, for example, Patent Documents 1, 2, and 3.

[0006] JP 2017-128621 A JP 2011-516373 A JP 2019-33021 A

[0007] However, with the recent trend of global warming leading to rising summer temperatures, it is becoming increasingly difficult to prevent settling in storage facilities that are not equipped with air conditioning, even when resin materials are formulated according to conventional resin design guidelines.Even if air conditioning is fully equipped, there are concerns about unexpected power outages and increased costs due to power consumption during peak power hours.

[0008] Patent Document 1 is intended for circuit breakers and uses a resin consisting of an epoxy base resin, a curing agent, and a reactive diluent, but the formulation does not take measures to prevent settling.

[0009] In Patent Document 2, fumed silica is added as a thickener to an epoxy resin material, but no curing agent or radical monomer containing silica is included, and the aim is simply to thicken the epoxy resin.

[0010] Patent Document 3 is intended for circuit breakers and has in common the point of adding rubber particles to an epoxy resin, but the rubber particles are used to improve crack resistance, and their size is 0.1 to 1 μm, and hydrophobic fumed silica is not added to improve thixotropy.

[0011] An object of the present invention is to improve the storage properties of molding resins for power receiving and distribution devices in high-temperature environments and to increase molding reliability.

[0012] A molded resin for a power receiving and distribution device according to one embodiment of the present invention is a molded resin for sealing the power receiving and distribution device, and the raw material liquid of the molded resin includes a base liquid containing epoxy resin and silica as its main components, a hardener liquid containing acid anhydride and silica as its main components, and a reactive diluent liquid containing a radical monomer and a copolymerization agent as its main components, and the hardener liquid contains at least one of (A) butadiene rubber or styrene-butadiene rubber having a diameter of less than 100 nm, and (B) fumed silica having a hydrophobic surface.

[0013] According to one aspect of the present invention, the storage properties of the mold resin of the power receiving and transforming equipment in a high-temperature environment can be improved, and the mold reliability can be increased.

[0014] FIG. 1 is a diagram showing the configuration of a power receiving and distribution device (vacuum circuit breaker); FIG. 2 is a diagram showing an example of mixing an epoxy base agent, a curing agent, and a reactive diluent, which are components of a molding material; FIG. 3 is a diagram showing an example of mixing an epoxy base agent, a curing agent, and a reactive diluent, which are components of a molding material; FIG. 4 is a diagram showing an example of mixing an epoxy base agent, a curing agent, and a reactive diluent, which are components of a molding material; and FIG. 5 is a diagram showing the properties of a cured product created by mixing a base agent, a curing agent, and a reactive diluent.

[0015] In an embodiment of the present invention, the resin raw materials constituting the molded portion of a power receiving / transforming device are three types of molded resin raw material liquids: a base liquid primarily composed of epoxy resin and silica, a hardener liquid primarily composed of acid anhydride and silica, and a reactive diluent liquid primarily composed of a radical monomer and a copolymer. A total of less than 2 weight percent of butadiene rubber or styrene-butadiene rubber with a diameter of less than 100 nm and fumed silica whose surface hydroxyl groups have been hydrophobized with methyl groups are added to the hardener liquid. The three raw material liquids are then mixed and hardened to form the molded portion.

[0016] The raw resin is an epoxy agent that crosslinks with acid anhydrides to form a strong solid. However, it contains a large amount of silica particles (70% by weight), which makes it highly viscous. To alleviate this, a mixture of radical monomers and copolymers is added as a reactive diluent.

[0017] Reactive diluents have low viscosity and do not contain fillers such as silica, which helps to lower the viscosity of the mixture of the base resin and hardener, improving casting properties. The viscosity of the base resin and hardener is high at around 15 Pa·s at room temperature (25°C), but with the recent rise in summer temperatures, temperatures can sometimes exceed 40°C in storage locations without air conditioning.

[0018] In such a temperature environment, the viscosity of the base resin and curing agent drops to about a few Pa·s when stored separately, causing the fillers contained therein to settle. If the fillers settle to the bottom of the container, the supernatant liquid remaining at the top of the container must be used during use, which may reduce the fillers contained in the cured resin and result in a decrease in strength and voltage resistance.

[0019] Therefore, in an embodiment of the present invention, butadiene rubber or styrene-butadiene rubber particles with a diameter of less than 100 nm are added. These particles do not settle due to the action of molecular Brownian motion in the liquid, and unlike the polar base resin (epoxy) and curing agent (acid anhydride), they are non-polar substances and therefore form a network structure in the liquid when stationary.

[0020] Due to this network structure, the viscosity of the liquid when stationary appears very high, and ideally it will become gel-like even at high temperatures of around 40°C. In this embodiment, it did not become gel-like, but it was viscous enough that pressing it with a finger left an indentation. This prevents the filler contained inside from settling.

[0021] On the other hand, once the liquid begins to move, this network structure is destroyed, causing a rapid drop in viscosity. Therefore, when the liquid begins to flow by tilting the container or stirring during use, the liquid viscosity drops to below 15 Pa s. The addition of a radical monomer further reduces the viscosity to about 7 Pa s, which does not impair handling during use.

[0022] Furthermore, due to the synergistic effect of the butadiene rubber and the styrene butadiene rubber with the hydrophobic fumed silica, it is possible to improve the viscosity at rest with a smaller amount added than when either of these rubbers is used alone, as will be described later.

[0023] As described above, this embodiment can improve storage properties so that the filler in the resin does not settle, and also has the effect of preventing an increase in handling properties (kinetic viscosity) during use.

[0024] Preferably, only butadiene rubber or styrene-butadiene rubber is added at a ratio of 5 weight percent or less. Both butadiene rubber and styrene-butadiene rubber are hydrophobic substances, and in polar epoxy resins or acid anhydrides, they have the effect of reducing the contact area with each other, similar to the separation of water and oil.

[0025] Furthermore, because these particles are minute particles, they are not affected by Brownian motion and do not settle, but instead bond together to form a network structure in the liquid. This network structure increases the viscosity of the liquid and inhibits the settling of the filler. The amount of filler added can be as low as 5% by weight, but if it is less than 3% by weight, the ability to form a network structure is significantly lost and the viscosity at rest does not increase.

[0026] Preferably, only the surface-hydrophobicized fumed silica is added, and the ratio may be 5 weight percent. The surface-hydrophobicized silica acts as a hydrophobic substance in the liquid.

[0027] Therefore, as mentioned above, in polar epoxy resins or acid anhydrides, there is an effect of reducing the contact area between them, just like the separation of water and oil. Furthermore, the BET diameter of fumed silica is very small, about 20 nanometers, and because these particles are fine particles, they do not settle due to the influence of Brownian motion.

[0028] As a result, they bond to each other, creating a network structure in the liquid. This network structure increases the viscosity of the liquid and inhibits the settling of the filler. The amount of filler added can be about 5% by weight, but if it is less than 3% by weight, the ability to form a network structure is significantly lost and the viscosity at rest does not increase.

[0029] Preferably, the hydrophobic groups of the fumed silica may be alkyl groups such as ethyl groups or isobutyl groups instead of methyl groups in place of hydroxyl groups on the surface of the fumed silica.

[0030] These alkyl groups have no polarity, so by replacing them with highly polar hydroxyl groups, the surface of the fumed silica can be made completely hydrophobic. This forms a network structure in the resin liquid, increasing the viscosity at rest and preventing filler sedimentation.

[0031] Preferably, the epoxy resin raw material has a bisphenol A skeleton or a bisphenol F skeleton. Epoxy resins with a bisphenol A skeleton are inexpensive and have high crack resistance and strength. Epoxy resins with a bisphenol F skeleton are more expensive than bisphenol A, but have a lower liquid viscosity than bisphenol A, so they may be added to adjust the viscosity.

[0032] Preferably, the curing agent for the resin raw material is an acid anhydride. Although amines are known as curing agents for epoxy resins in addition to acid anhydrides, acid anhydrides are preferred because of their mild reactivity.

[0033] Preferably, the radical monomer is styrene and the copolymerization agent is phenylmaleimide. By copolymerizing styrene with phenylmaleimide, island-like radical polymerization regions are formed in the epoxy resin, contributing to toughening of the cured product.

[0034] Preferably, an imidazole is contained as a reaction initiator for the epoxy resin and the acid anhydride. Imidazole has the effect of initiating polymerization using the epoxy ring of the epoxy resin as a reaction initiation point, and is one option for the reaction initiator.

[0035] Preferably, the reaction initiator for the radical monomer is an organic peroxide. Organic peroxides generate radical active sites when heated, and serve to initiate radical polymerization. Although there are various types of peroxides, organic peroxides that have mild reaction initiation properties and are highly safe are preferred.

[0036] According to an embodiment of the present invention, it is possible to improve the storage properties of the raw resin material of power distribution equipment, particularly vacuum circuit breakers, suppress the settling of fillers contained in the resin material even during hot seasons such as summer, and prevent deterioration of the characteristics of the finished molded product.

[0037] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0038] The configuration of the power receiving and distribution device (vacuum circuit breaker) will be described with reference to FIG.

[0039] The vacuum circuit breaker body is located inside the dashed line 12, connected to a conductor rod 11, and sealed with a hardened molded resin 10. The opening and closing of the vacuum circuit breaker 12 is controlled by an operating device 13. The role of the hardened molded resin 10 is to prevent the high electric field of the vacuum circuit breaker 12 from being directly exposed to the outside, to protect the circuit breaker from the surrounding environment, and to secure the various components. Therefore, it is necessary for the resin to exhibit various properties such as strength, temperature resistance, and voltage resistance as designed. Therefore, any changes in the composition of the resin material must be avoided.

[0040] However, the resin material (epoxy base, curing agent) contains as much as 70 weight percent of filler (silica), and a decrease in viscosity can cause the filler to settle. Silica, the main component of the filler, ensures the strength and dielectric breakdown strength of the cured molding resin. If this silica content decreases, the mold may be unable to withstand high electric fields and crack, or it may be unable to withstand weight or vibration. The viscosity of resin materials decreases exponentially as the temperature increases, and storing the resin at unexpected temperatures can impair the performance of the cured molding resin.

[0041] Therefore, in this example, the components of the molding material, namely, the epoxy base agent, the curing agent, and the reactive diluent, were mixed as shown in FIGS.

[0042] First, the components of the base resin will be described. In this example, the viscosity of the epoxy base resin was sufficiently high that it was thought that silica sedimentation would not occur, so in order to reduce the viscosity of the resin and improve handling, bisphenol F epoxy resin was also used in addition to bisphenol A type. Depending on the application, bisphenol A type alone may be sufficient. The components of the base resin are listed below. The amounts (ratios) of each added are shown in Figure 2. 1) Liquid bisphenol A type epoxy resin material, liquid bisphenol F type epoxy resin 2) Crystalline silica 3) Fused silica 4) Organic peroxide radical polymerization initiator

[0043] The base material had a sufficiently high viscosity that it did not settle even after 2,400 hours at 40°C. However, to prevent sedimentation over a longer period, 1 weight percent each of the fine styrene-butadiene rubber, butadiene rubber, and hydrophobic fumed silica described in this example was added. Additionally, 2 weight percent of surfactants and silane coupling agents were added to improve manufacturability.

[0044] The main components of the reactive diluent are listed below. The amounts of each component added are shown in Figure 3. 1) N-phenylmaleimide 2) Styrene 3) Polymerization inhibitor (4-tert-butylcatechol)

[0045] Reactive diluents do not contain silica. When mixed with a highly viscous base resin and hardener, reactive diluents reduce the viscosity of the entire liquid, improving casting properties. They also form islands of radical polymer hardened bodies within the epoxy resin, improving strength.

[0046] The main components of the curing agent are listed below. The amounts of each component added are shown in Figure 4. 1) Acid anhydride (3 or 4-methyl-1,2,3,6-tetrahydrophthalic anhydride) 2) Crystalline silica 3) Fused silica 4) Imidazole (reaction accelerator for epoxy resin)

[0047] The viscosity of the curing agent in the above composition was low, and 5% of the total weight of the silica settled to the bottom at 40°C for 2,400 hours. For this reason, in this example, 1% by weight of styrene-butadiene rubber with a diameter of 80 nm and 1% by weight of fumed silica, which was hydrophobized by substituting methyl groups for the surface hydroxyl groups, were added. Furthermore, to improve manufacturability, a total of 2% by weight of surfactants and silane coupling agents were added.

[0048] As described above, by adding fine hydrophobic rubber and hydrophobic fumed silica, no settling occurred even when testing at 40°C for 2,400 hours. Furthermore, when the dynamic viscosity was measured once flow had begun, it was found to be 12 Pa·s. While the viscosity was high and the filler was unlikely to settle when the liquid was stationary, once the liquid began to move, there was no problem with fluidity. To give the liquid an initial flow, the container was tilted while stirring with a stirring blade, and a specified amount was added to the mixing container, measured, and mixed.

[0049] The above-mentioned base resin, curing agent, and reactive diluent were mixed to prepare a cured product. The properties of the cured product will be explained using Figure 5.

[0050] FIG. 5 shows that the addition of 2 weight percent total of finely divided rubber and hydrophobic fumed silica had little effect on important physical properties.

[0051] As described above, this example confirmed that filler sedimentation did not occur in the resin liquid even in a high-temperature environment, and no adverse effects such as deterioration of physical properties due to the addition were observed.

[0052] In Example 2, when the viscosity of the epoxy base resin is low and sedimentation occurs, adding a total of 2 weight percent of fine rubber particles less than 100 nm in diameter and hydrophobic fumed silica produces the same effect. Also, when the viscosity of both the epoxy base resin and the curing agent is low, adding fine rubber particles and hydrophobic fumed silica to both produces the same effect.

[0053] In Example 3, the same effect was achieved when only fine rubber particles with a diameter of less than 100 nm were added at 5 weight percent. However, when the amount of rubber added reached 5 percent, the glass transition temperature tended to decrease. In Example 1, the glass transition temperature was 124°C, but in this example, it was 118°C. This is thought to be due to the influence of the added fine rubber.

[0054] In Example 4, the same effect was achieved when only 5 weight percent of hydrophobic fumed silica was added. However, when the amount of hydrophobic fumed silica added reached 5 percent, the kinematic viscosity increased to 20 Pa·s. This may make stirring impossible in equipment equipped with a stirring device that does not have sufficient power (motor torque). In addition, the time required for evacuation during degassing increased by about 20 percent.

[0055] In Examples 1 and 4, the same effect was achieved whether the chemical group introduced to hydrophobize the hydroxyl groups on the fumed silica surface was an isobutyl group or an ethyl group. As long as it is an alkyl group, it does not matter what group is used to substitute the hydroxyl groups.

[0056] In this way, the molding resin of the above embodiment is used to seal power receiving and distribution equipment (for example, a vacuum circuit breaker).

[0057] The molding resin raw material liquid includes a base liquid containing epoxy resin and silica as its main components, a hardener liquid containing acid anhydride and silica as its main components, and a reactive diluent liquid containing a radical monomer and a copolymerization agent as its main components. The hardener liquid includes at least one of (A) butadiene rubber or styrene-butadiene rubber having a diameter of less than 100 nm and (B) fumed silica having a hydrophobic surface.

[0058] In one aspect of the above example (mold resin), the curing agent liquid contains less than 2 weight percent in total of both (A) butadiene rubber or styrene-butadiene rubber having a diameter of less than 100 nm and (B) fumed silica having a hydrophobic surface.

[0059] In another aspect of the above embodiment (mold resin), the curing agent liquid contains less than 5 weight percent of only the butadiene rubber or the styrene-butadiene rubber (A) having a diameter of less than 100 nm.

[0060] In another aspect of the above embodiment (mold resin), the hardener liquid contains less than 5 weight percent of only (B) the fumed silica whose surface has been hydrophobized.

[0061] Furthermore, the manufacturing method of the above embodiment manufactures a power receiving and distributing device (for example, a vacuum circuit breaker) using a molded resin.

[0062] The raw material liquid for the molding resin includes a base liquid containing epoxy resin and silica as its main components, a curing agent liquid containing acid anhydride and silica as its main components, and a reactive diluent liquid containing a radical monomer and a copolymerization agent as its main components. The curing agent liquid includes at least one of (A) butadiene rubber or styrene-butadiene rubber having a diameter of less than 100 nm, and (B) fumed silica having a hydrophobic surface. The base liquid, the curing agent liquid, and the curing agent liquid are mixed and cured to form the molding resin.

[0063] In one aspect of the above-mentioned Example (production method), the curing agent liquid contains less than 2 weight percent in total of both (A) butadiene rubber or styrene-butadiene rubber having a diameter of less than 100 nm and (B) fumed silica having a hydrophobic surface.

[0064] In another aspect of the above embodiment (production method), the curing agent liquid contains less than 5 weight percent of only the butadiene rubber or the styrene-butadiene rubber (A) having a diameter of less than 100 nm.

[0065] In another aspect of the above embodiment (production method), the curing agent liquid contains less than 5 weight percent of only (B) the fumed silica whose surface has been hydrophobized.

[0066] According to the above embodiment, the settling of the filler contained in the resin material is prevented when the ambient temperature is high, such as in summer, thereby improving the storage properties of the resin material and ensuring the integrity of the hardened molded portion when the power receiving and distribution equipment is molded with the resin material.

[0067] 10 Hardened molding resin 11 Conductor rod 12 Vacuum circuit breaker 13 Operating device

Claims

1. A molding resin for sealing electric power distribution equipment, the raw material liquid of the molding resin comprising: a base liquid primarily composed of epoxy resin and silica; a hardener liquid primarily composed of acid anhydride and silica; and a reactive diluent liquid primarily composed of a radical monomer and a copolymerization agent, the hardener liquid comprising at least one of the following: (A) butadiene rubber or styrene butadiene rubber having a diameter of less than 100 nm; and (B) fumed silica having a hydrophobic surface.

2. The molding resin for the power distribution equipment described in claim 1, characterized in that the hardener liquid contains less than 2 weight percent in total of both: (A) butadiene rubber or styrene-butadiene rubber having a diameter of less than 100 nm, and (B) fumed silica having a hydrophobic surface.

3. The molding resin for power distribution equipment according to claim 1, characterized in that the hardener liquid contains (A) less than 5 weight percent of only the butadiene rubber or styrene-butadiene rubber having a diameter of less than 100 nm.

4. The molding resin for power distribution equipment according to claim 1, characterized in that the hardener liquid contains less than 5 weight percent of the fumed silica having a hydrophobic surface (B).

5. The molding resin for power distribution equipment according to claim 1, characterized in that the hydroxyl groups on the surface of the fumed silica are methyl groups.

6. The molding resin for power distribution equipment according to claim 1, characterized in that the hydroxyl groups on the surface of the fumed silica are alkyl groups.

7. The molding resin for electric power receiving and distributing equipment according to claim 6, characterized in that the alkyl group is an ethyl group or an isobutyl group.

8. The molding resin for power distribution equipment according to claim 1, characterized in that the epoxy resin has a bisphenol A type skeleton or a bisphenol F type skeleton.

9. The molding resin for power distribution equipment according to claim 1, characterized in that the hardener liquid is an acid anhydride.

10. The molding resin for electric power distribution equipment according to claim 1, characterized in that the radical monomer is styrene, and the copolymerization agent is phenylmaleimide.

11. The molding resin for power distribution equipment according to claim 1, characterized in that the raw material liquid of the molding resin contains an imidazole as a reaction initiator between the epoxy resin and the acid anhydride.

12. The molding resin for electric power distribution equipment according to claim 1, wherein the reaction initiator for the radical monomer is an organic peroxide.

13. A power receiving and distributing device sealed with the molding resin according to claim 1.

14. The power distribution device according to claim 13, wherein the power distribution device is a vacuum circuit breaker.

15. A method for manufacturing an electric power distribution device, comprising the steps of: manufacturing an electric power distribution device using a molded resin; a raw material liquid for the molded resin comprising: a base liquid having epoxy resin and silica as its main components; a hardener liquid having acid anhydride and silica as its main components; and a reactive diluent liquid having radical monomer and copolymerization agent as its main components; and the hardener liquid comprises at least one of: (A) butadiene rubber or styrene butadiene rubber having a diameter of less than 100 nm; and (B) fumed silica having a hydrophobic surface; and a manufacturing method for an electric power distribution device, comprising the steps of: mixing and hardening the base liquid, the hardener liquid, and the hardener liquid to form the molded resin.

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