KR950006637B1 - Epoxy resin composition - Google Patents

Abstract

The epoxy resin for the insulating filling material in electric/electronic device to have good casting workability, moisture resistance, cracking resistance and thermal shock resistance is composed of 100 wt% bisphenol a type epoxy resin, 3-10 wt% polyethylene glycol of 750-1,500 molecular weight against epoxy resin and 2-50 wt% diglycidyl ether mixture of polypropylene glycol of 170-350 epoxy equivalent weight, 100-350 wt% an inorganic filler, 85-125 wt% an acid anhydride based curing agent and 0.5-10 wt% a curing accelerator.

Description

Epoxy resin composition

The present invention relates to an epoxy resin composition that can be used as an insulating filler for electrical and electronic devices, and particularly, has excellent electrical insulating properties and excellent resistance to periodic external temperature changes, and maintains excellent electrical insulating properties even under severe use conditions. In general, the present invention relates to an epoxy resin composition which is excellent in adhesion to a conductor inserted together in an electric and electronic product and impregnation between the conductor coils, and which can be used for the production of highly reliable electric and electronic products.

The method of applying a thermosetting resin as an electrical insulating material of electric and electronic products has been known for a long time. Among them, the epoxy resin-based composition is capable of producing a grade product of the form required by the reactivity of the epoxy functional group of the epoxy resin, It is most widely applied because it exhibits a wide variety of properties depending on the type of the compound blended in the composition.

However, as the range of use of electric and electronic devices has been expanded and the types of electric and electronic device parts that apply thermosetting resins as electric insulators have been diversified, the environment used for the parts has also become very wide.

Accordingly, there is a need for a thermosetting resin composition having improved moisture resistance, thermal shock resistance and the like, which can maintain basic electrical insulation properties and mechanical properties even under severe external use conditions, thereby providing high reliability to electric and electronic devices.

Conventional techniques for meeting such demands include a method of adding an epoxy-modified rubber compound to improve thermal shock resistance, but in this case, there is a problem in that the viscosity is increased and the impregnation is poor as the molecular weight is increased.

In addition, there is a method of adding a silicone-based compound. In this case, it is possible to improve moisture resistance, crack resistance, impact resistance, etc. There is a problem such as a decrease in adhesive strength.

An object of the present invention is to improve the moisture resistance, crack resistance, thermal shock resistance and impregnation that can be given a high reliability by solving the above-mentioned problems in manufacturing the epoxy resin composition that can be used as an insulating filler of electrical and electronic devices, It is to provide an epoxy resin composition that is easy to work during the molding operation by low viscosity of the composition.

Accordingly, in order to achieve the above object, in the present invention, a bisphenol-A type epoxy resin is used as a base resin, and a mixture of diglycidyl ether-based diluents of polyethylene glycol and polypropylene glycol is used as a main component, and an inorganic filler and an acid anhydride An epoxy resin composition was prepared by blending a curing agent and a curing accelerator.

In more detail, in the composition, polyethylene glycol has a molecular weight in the range of 700 to 1500, the most advantageous in terms of processability, cured product properties, moisture resistance, etc., and the content is 3 to 100 parts by weight of bisphenol-A epoxy resin. The diglycidyl ether of 10 parts by weight of polypropylene glycol is suitably in the range of 170 to 350 epoxy equivalents, and the amount of addition is preferably in the range of 5 to 20 parts by weight based on 100 parts by weight of the bisphenol-A epoxy resin.

When the content of polyethylene glycol is less than the above-mentioned range, the improvement of moisture resistance and impact resistance desired in the present invention is insufficient, and when more than the above range, it may adversely affect the curability, mechanical properties, heat resistance, etc. of the cured product. In addition, when the diglycidyl ether content of the polypropylene glycol is smaller than the above defined range, the improvement of permeability is insufficient. If the diglycidyl ether content of the polypropylene glycol is larger than the above range, the heat resistance and mechanical properties may be lowered.

The hardener is an acid anhydride hardener which is liquid at room temperature in terms of working process, and specific examples thereof include methyl hexahydro phthalic anhydride, phthalic anhydride of methylcyclopentadiene, methyl tetrahydrophthalic anhydride and Mixtures and modified substances thereof can be used, and the addition amount thereof is most advantageous in terms of general properties in the range of 85 to 125 parts by weight based on 100 parts by weight of the epoxy resin mixture.

As the curing catalyst, general curing accelerators such as tertiary amine compounds, imidazole compounds, and boron trifluoride-amine complex salt compounds may be applied. The content of these curing accelerators is 0.5 to 10 weight parts based on 100 parts by weight of the epoxy resin mixture. The range of parts is appropriate, and 0.5 parts by weight or less, the curing speed is slow, productivity may decrease, or the heat resistance and moisture resistance of the cured product may be lowered. At 10 parts by weight or more, the pot life of the product is short, or heat generation during curing There is a fear that the characteristics of the product by.

In the composition of the present invention, inorganic fillers are blended for controlling heat generation during curing and improving properties of the cured product.Inorganic materials include crystalline silicon oxide, molten silicon oxide, talc powder, calcium carbonate, mica, alumina, alumina hydroxide and kaolin. Although fillers such as powders can be used, they should be selected according to the content of impurity, particle size and particle size distribution according to the use of molded product, environment of use, processing method, size and shape.

The amount of addition is preferably in the range of 100 to 350 parts by weight with respect to 100 parts by weight of the epoxy resin in terms of processability, mechanical properties, linear expansion coefficient and thermal conductivity.

In addition, additives such as an antifoaming agent, a coupling agent, a diluent, a dispersant, a pigment, and a concern may be added to the composition of the present invention depending on the characteristics of the manufacturing process and the characteristics of the product.

The curing conditions of the resin composition of the present invention may vary depending on the size of the molded article and the required properties, but generally after the first curing for 2 to 6 hours at 95 ~ 115 ℃, the desired curing by 120 to 150 ℃ 5 to 15 hours Hardened | cured material can be obtained.

Polyethylene glycol in the epoxy resin composition provides flexibility to the cured product by the long aliphatic chain in the molecule, and serves as a mitigating layer of thermal stress caused by mechanical shock or temperature change, and also to improve the moisture resistance of the cured product. Contribute. In addition, diglycidyl ether of polypropylene glycol facilitates work during mold work by lowering the viscosity of the composition, improves permeability, and serves as a shock absorber.

In addition, since these two additives are chemically bonded to the epoxy resin or the curing agent, they are completely chemically bonded in the curing structure, so that there is no problem such as poor surface leaching permeability of the aforementioned additive.

Therefore, the present epoxy resin composition is resistant to external periodic temperature changes, and thus maintains excellent electrical insulation properties even under severe use conditions, and generally has a high degree of adhesion between conductors and conductor coils inserted together in electrical and electronic products. It is excellent in the impregnation of the composition, the composition is easy to work by low viscosity, and is useful for the production of highly reliable electric and electronic products.

In the following examples, specific application methods and effects thereof will be described. However, the following examples do not limit the scope of the invention.

[Examples 1-2 and Comparative Examples 1-3]

Each compound was mixed by a conventional method by the formulation of Table 1 to prepare an epoxy resin composition, and the composition thus prepared was cured by curing the mixture at 110 ° C. for 3.5 hours and then curing at 145 ° C. for 6 hours. Manufacture the cargo.

This cured product was evaluated for the following items, and the results are shown in Table 2.

In addition, compositions outside the scope of the present invention were prepared in the formulations described in Table 1 and Comparative Examples, and evaluated in the same manner as in the above Examples, described in Table 2. (Comparative Examples 1, 2, 3)

Evaluation of Cured Product

1) Impregnation

After winding 350 ~ 400 times of enameled copper wire with a diameter of 0.05 mm on a 12-slit coil bobbin made of polybutylene telephthalate per slits, the center was cut after the impregnation of the above composition, and the cut surface was unfilled by a microscope. The presence of internal voids (VDID) was determined.

2) Thermal shock resistance

50 specimens were prepared for each composition using the THERMAL SHOCK RESISTANCE TEST specimens as defined in ASTM D 1674. The number of specimens where cracks were generated was repeated 30 times at 155 ° C and 30 minutes at -55 ° C. It was.

3) Electrical characteristics and moisture resistance

Volume resistivity was measured as a representative value of electrical characteristics. In order to evaluate the electrical insulation properties at high temperature and the electrical insulation properties after moisture absorption, the volume resistivity after drying at 150 ° C. and after 24 hours treatment in boiling water was measured. The voltage is 500 volts (JIS K 6911).

4) mechanical properties

Flexural strengths were measured and compared as representative values of mechanical properties.

TABLE 1

* Note: (1) Epoxy equivalent 185 ~ 190

(2) diglycidyl ether of polypropylene glycol of epoxy equivalent 175-205

(3) Polyethylene glycol: Polyethylene glycol having a molecular weight of 700 to 750

(4) Curing agent: methyl hexahydrophthalic anhydride

TABLE 2

Claims (2)

In the epoxy resin composition which can be used as an insulation filler of electrical and electronic equipment, a bisphenol-A epoxy resin is composed of a diglycidyl ether mixture of polyethylene glycol and polypropylene glycol as a main component, and an inorganic filler and an acid anhydride curing accelerator are used. Epoxy resin composition characterized by mixing. The molecular weight of polyethylene glycol is in the range of 750-1500, the compounding quantity is 3-10 weight part with respect to 100 weight part of epoxy resins, and the diglycidyl ether of polypropylene glycol has an epoxy equivalent of 170-350. The addition amount is 5-20 weight part with respect to 100 weight part of epoxy resins, 85-125 weight part of acid anhydride type hardeners, 0.5-10 weight part, and an inorganic substance based on 100 weight part of epoxy resin compositions The filler is an epoxy resin composition, characterized in that 100 to 350 parts by weight is added.