JPS6035926B2 - epoxy resin composition - Google Patents

Description

Detailed Description of the Invention The present invention relates to an epoxy resin composition used for insulating electrical parts such as coils, transformers, capacitors, resistors, etc. The present invention aims to provide an epoxy resin composition.

There are many types of electrical parts used in various electronic and electrical equipment, and epoxy resin is a versatile insulating material that can be tailored to the specific requirements and working conditions of each application.

Regardless of the required characteristics, coils, transformers,
A common insulation characteristic of electrical devices such as capacitors and resistors is that they are uniformly filled with insulating material and have no voids. For this purpose, it is necessary that at least the epoxy resin compound before insulation treatment does not contain air bubbles that cause voids.
That is, the ability to easily remove air bubbles from the epoxy resin compound is important. Epoxy resins are blended to suit the use and work of each electrical device, and the basic ingredients are epoxy resin and a curing agent.

It is extremely rare that this is used alone, and in addition, fillers with particle sizes of several r to several tens of microns, flame-enhancing agents, accelerators to accelerate the reaction, diluents to adjust the viscosity, and appropriate A luster-improving agent that imparts softness and other pigments are used. Since these resin components and auxiliary materials are mixed to make an epoxy resin compound for electrical insulation, it contains a large amount of air bubbles when mixed, and if left as is, it will foam when it hardens, making it difficult to work with. Or, even if it looks good from the outside, it may have a large amount of air bubbles inside.
This may cause dielectric breakdown such as corona discharge. Usually, the formulation is degassed in a vacuum and a formulation with few bubbles is used. The defoaming and the ease with which the foam disappears vary depending on the types of ingredients in the blend, and the defoaming work is also significantly influenced by the viscosity of the blend. Conventionally, a small amount of an antifoaming agent is added because a compound alone cannot be used satisfactorily, no matter how good the defoaming and antifoaming components are selected.

Silicone oil is used as an antifoaming agent. Although silicone oil has very excellent defoaming performance, it also has the following drawbacks, and the present invention was developed to address these drawbacks. One drawback is that silicone oil has very good template properties, so it does not adhere well to insulated surfaces. The second is a small amount, for example several 10
The effect is shown by the amount of PM, and it is difficult to control that amount. If a large amount is blended, the force of defoaming will be strong and it will scatter, which is not a desirable property when injecting in a vacuum, for example. The present invention is based on devising a formulation that does not cause such drawbacks such as poor adhesion, has appropriate defoaming performance, and is not affected by the amount.

The present invention is based on the discovery that high molecular weight 1.4 liquid polybutadiene rubber has excellent defoaming and defoaming properties for epoxy resin compounds. There are various types of liquid polybutadiene rubber as shown in Table 1.

Table 1 Types of liquid rubber Defoaming properties ○Good △Slightly poor ×Very K poor Out of these, the defoaming property is No. 1. Only M.1, 2, and 3 are good, and M. No. 3 was not preferred because it separated when the epoxy resin was cured, which caused practical problems.

The gunwale. If 1 and 2 are simply mixed with epoxy resin, they will separate when the epoxy resin hardens, so we researched a method of mixing them without separating them, and found that using about 0.2% tin octylate as a catalyst in epoxy resin. When added and reacted for 5 hours at 70°C, a reactant with low viscosity at 7000°C and slightly rubbery at room temperature is obtained. By adding this, a composition with good defoaming properties without separating during curing can be obtained. I was able to get it.
Naturally, the amount and temperature of the catalyst should be selected depending on the reactivity of the epoxy resin, and the above conditions are 1:1 of 1:1 polyMR4 mark T from Idemitsu Petrochemical Co., Ltd. as 1.4 polybutadiene and 1:4 polybutadiene (epicote 828 from Shell Chemical Co., Ltd.) as the epoxy resin. It is mixed in the ratio of Of course, in the case of a resin whose reactivity is slower than that of Epiquat, it is appropriate to increase the amount of catalyst or raise the reaction temperature. In this case, if the reaction progresses too much and reaches the point of gelation, it cannot be mixed. It is preferable for the reaction to proceed to such an extent that the resin composition does not separate when cured. 1. Having an OH group at the end which has been reacted in advance.
4 polybutadiene was added to various epoxy resins and their defoaming and antifoaming properties were investigated. The ease with which the resin could be defoamed was evaluated by the following method. 100 ml of various epoxy resin formulations were placed in a polypropylene container with an outer diameter of 6◇ and placed in a desiccator and degassed using a vacuum pump. In one method, the foaming height was evaluated, and in the other method, the foaming height was kept constant, the vacuum was stopped, and the time for defoaming was evaluated.

It is difficult to distinguish between defoaming and antifoaming properties, but it also indicates the difficulty of practical workability.These characteristics can be shown quantitatively such as height and time, but their The values also vary widely, and are shown here as extremely good ◎, good ◎, and poor ×. Examples of the present invention will be described below with reference to comparative examples.

An epoxy resin composition was prepared by blending an epoxy resin, a diluent, an antifoaming agent, and a filler and kneading with a three-roll roll. This is generally referred to as a base material, and a curing agent is mixed therein and mixed to form an insulating layer by impregnating electrical parts or by casting, dipping, etc. Conditions such as viscosity at this time vary depending on the part, but here, the viscosity when the curing agent is added is 1 to 2 x 1 cp for acid anhydride.
The experiment was conducted by selecting a value around 1 cps for the amine curing agent and around 1 cps for the amine curing agent. The epoxy resin mixed with the curing agent was placed in a 6◇-sized polypropylene container at room temperature, and immediately defoamed in a vacuum desiccator. When the vacuum was reached, the vacuum was stopped and the time taken for the bubbles to disappear was measured to evaluate the defoaming property. Table 2 summarizes the results of the minimum antifoaming agent required for antifoaming properties. Himokkoi Sogo Ryousen Mimi Tsubasa Soru Homo Iso Iso Sankama 轡 Renki Gunshin. K... Kesa 5 m "〇Kiki≧ Room member sound ○m Small ZI〆mi≦gsaHH toda!"

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DER 28 also has good defoaming properties and is a diluent and softening agent.
-736 was mixed in to make the viscosity 150 ps, and Crystallite RD-8, which also has good antifoaming properties, was mixed in.
The viscosity was set to 4×1 picps.

Generally, it has a relatively low viscosity composition, making it suitable for Western-style electrical parts. In addition, liquid HN-2 was added as an acid anhydride curing agent.
200 was added and vacuum defoaming was performed, and as a result, the defoaming performance was extremely poor.

In order to facilitate defoaming, use silicone oil.
0.05 part is required as shown in 2. Further, in the case of the 1.4 polybutadiene/epoxy resin reactant having a terminal hydroxyl group of the present invention, 1 part needs to be added. M. 4 to 5 are the results for Epicoat 815, a low-viscosity epoxy resin widely used as an epoxy resin.

This resin is already formulated with a diluent and has a viscosity of 15% at room temperature.
0 ratio ps. M. 7 and 8 are hydrated alumina used as a filler, which significantly improves anti-tracking properties and pyrolysis.
This is an example of one in which defoaming is somewhat difficult, probably due to the small particle size. No. 9 is an example in which different types of diluents were selected. M. In No. 10, 10% of solid PAPA was added to the acid anhydride curing agent for the purpose of imparting flexibility.

Defoaming became quite difficult and the amount of antifoaming agent increased. M.
Nos. 11 and 12 are the results of examining the defoaming properties of high viscosity, with Epomate selected as a typical amine-based curing agent and having a viscosity on the order of 1 picps after the curing agent is added. No. 17-1
No. 8 was the result of blending a large amount of PAPA, which is difficult to defoam, and in this case, defoaming was difficult even if a fairly large amount of antifoaming agent was blended. However, the 1.4 polybutadiene of the present invention showed considerable effectiveness. As mentioned above, epoxy resin and
It has been found that a mixed reaction product of 1.4 polybutadiene liquid rubber or 1.4 polybutadiene/styrene copolymer liquid rubber and tin octylate is easy to produce and has a remarkable defoaming effect even when added in a relatively small amount. In addition, unlike silicone oil antifoaming agents, it has good adhesion to the surface of cast electrical components. A further characteristic property is that while it is difficult to control the amount of silicone oil defoaming agents, the antifoaming performance of the epoxy resin composition of the present invention does not change at all even if the amount thereof is increased.

Claims (1)

[Claims] 1. For 100 parts by weight of epoxy resin, 0.5 parts by weight or more of 1.4 polybutadiene liquid rubber or 1.4 polybutadiene/styrene copolymer liquid rubber having a hydroxyl group at the end and about 0.2% tin octylate. An epoxy resin composition characterized by adding and reacting.