JPS58217517A - Epoxy resin composition - Google Patents

Abstract

PURPOSE:A low-stress epoxy resin composition excellent in cracking resistance, moisture and heat resistance, containing a dimethylene ether-bonded phenol novolak epoxy resin alone or both of this resin and an epoxy resin. CONSTITUTION:A composition comprising a phenol novolak epoxy resin having benzene rings and dimethylene ether groups for bonding the benzene rings, for example, a resin having an average structural formula of I or II (wherein R is -H, -CH3, formula III, -OH or formula IV, a different alkyl, and an alkyl derivative), a curing agent, a cure accelerator, a filler, a mold release, a surface treating agent, etc. In the dimethylene ether-bonded phenol novolak epoxy resin, it is preferred that at least 30% of the bonding groups for connecting the benzene rings are dimethylene ether groups. The effect of lowering stress becomes smaller as the proportion of dimethylene ether groups decreases.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a low-stress epoxy resin composition that has excellent crack resistance, moisture resistance, and heat resistance. It uses a phenol novolac type epoxy resin that has a base.

In recent years, the development of electronic devices has been remarkable and they have been widely incorporated into not only computers but also home appliances, automobiles, etc. Epoxy resin compositions such as epoxy resin molding materials and epoxy resin laminates are mainly used for insulating materials, protective materials, and exterior materials for electronic devices, as well as substrates on which electronic devices are attached. Recent demands for electronic equipment include miniaturization of ultra-large (large capacity) computers, miniaturization of microcomputers (97:'7), miniaturization of VTRs, and reduction in weight of automobiles, as shown by the miniaturization and weight reduction of automobiles. It is also resistant to environmental changes and rough handling.

These demands have led to thinner and more compact insulating materials, protective materials, exterior materials, and substrates for electronic devices. In other words, the epoxy resin compositions (molding materials, laminates) used in these applications must have crack resistance, such as not cracking when subjected to impact or temperature changes, and retaining pus in parts. Heat resistance and moisture resistance against changes in humidity are becoming necessary.

The present invention provides a low stress epoxy resin composition with excellent crack resistance that satisfies these requirements. The present invention is an epoxy resin comprising a phenol novolac type epoxy resin [1] having a dimethylene ether group as a bonding group between benzene rings, a curing agent, a curing accelerator, a filler, a mold release agent, a surface treatment agent, etc. The composition [IJ average structural formula example R: -H, -0H3, (-OH3)2. -OH.

Other Alkyl Groups and Alkyl Derivatives In the present invention, a phenol novolac type epoxy resin having a dimethylene ether group as a bonding group between benzene rings is referred to as a dimethylene ether bonded phenol novolac type epoxy resin. Moreover, the name phenol shall be used as a general term for all phenols (phenol, alkylphenol, resorcinol, etc.).

Conventionally, bisphenol A type epoxy resin has been commonly used as an epoxy resin. Since this resin has a large epoxy equivalent weight, the crosslinking density does not become high. Therefore, it has the advantage of low stress (having flexibility as a 1f1 fat), but has the disadvantage of poor heat resistance and moisture resistance. Therefore, phenol novolac type epoxy resins are used for applications in which these drawbacks cannot be ignored, such as molding materials for encapsulating electronic components. This resin has a small epoxy equivalent weight and a stable structure of a benzene ring, so it has excellent heat resistance and moisture resistance, but on the other hand, the resin is brittle and has poor crack resistance.

All resins have advantages and disadvantages, and low stress, heat resistance, and moisture resistance were not compatible. The present invention is based on the discovery that low stress, heat resistance, and moisture resistance can be achieved by using a dimethylene ether-bonded phenol novolac type epoxy resin.

Dimethylene ether-bonded phenol novolac type epoxy resin has a high crosslinking density because its epoxy equivalent is close to that of phenol novolac type epoxy resin, and it also has a nomethylene/ether group, that is, three atoms, between the be/zene ring and the be/ze/ring. Because they are bonded, if stress is applied, the stress can be absorbed by the twisting motion of the three atoms. In other words, it is possible to achieve both low stress, heat resistance, and moisture resistance.

In the dimethylene ether bonded phenol novolak type epoxy resin, it is desirable that 30 or more of the bonding groups connecting benzene rings are dimethylene ether groups. As the proportion of dimethylene ether groups decreases, the stress-reducing effect diminishes.

Furthermore, the features of the dimethylene ether-bonded phenol novolac-type epoxy resin can be utilized even if the dimethylene ether-bonded phenol novolac-type epoxy resin is used in combination with other epoxy resins (biphenol A-type epoxy resin, phenol novolac-type epoxy resin, etc.). However, since the effects vary depending on the amount of this resin used, it is necessary to determine the amount used depending on the purpose. Preferably, 30% or more of the epoxy 4tt resin is a zomethylene ether bonded phenol tuborac type epoxy resin.

The following is an explanation using an experimental example using a molding material.

Comparative Example 1 Bisphenol A type epoxy resin Saebe phenol novolac 6 parts, crystalline silica 70 parts, silane cutting agent 1
1 part, 0.5 part of curing accelerator, and 1 part of mold release agent were kneaded for 3 minutes with heated rolls at 120°C to obtain a molding material. The Percoll hardness (hereinafter abbreviated as Percoll hardness) of this material when cured for 60 seconds was Shu. Also, the bending strength of the molded product is u Ky/m
j, flexural modulus is 1200 Ky/d, impact strength is 3.2
The Kyα quotient and glass transition point were 97°C. and,
The resin decomposition temperature (hereinafter abbreviated as decomposition temperature) determined by differential thermal analysis was 238°C.

Furthermore, the water absorption rate by the pressure cooker is 1.1%, and the pressure cooker moisture resistance test (hereinafter abbreviated as pc'r) using simulated work 0 td 1
It was 40 yen.

Comparative Example 2 A molding material was obtained in the same manner as in Comparative Example 1 except for 20 g of cresol nogolac type epoxy resin and 10 parts of phenol nogolac.

This material has a Percoll hardness of 60 and a bending strength of 15 to 9/9.
l17, flexural modulus 16ooKy/d, impact strength 2.7
Kfα/cA, glass transition point 155℃, decomposition temperature 320
℃, water absorption rate 0.85%, PCT' 70Q hr.

Example A molding material was obtained in the same manner as in Comparative Example 1, except that 21 parts of methylene ether-bonded resol novilac type I xy resin and 9 parts of phenol nodelac were used.

This material has a Percoll hardness of 60. Bending strength 16
Kf//ff, flexural modulus 1200 Kf/d, impact strength 3.2 Kgcm/-, glass transition temperature 155°C, decomposition temperature 320°C, water absorption 0.85%, PUT 7QQ
It was hr.

Table 1 summarizes the results of the comparative examples and examples.

It can be seen that the bisphenol A type epoxy resin material has a small bending modulus and low stress, but has low Percoll hardness, glass transition point, and decomposition temperature, and is inferior in crosslinking properties. For this reason, water easily enters, resulting in a high water absorption rate. In other words, it has advantages in terms of stress, but has major drawbacks in heat resistance and moisture resistance.

Furthermore, the cresol black type epoxy resin material has excellent crosslinking properties, high Percoll hardness, high glass transition point, high decomposition temperature, and low water absorption. However, the bending modulus is large,
It has low impact strength, that is, it is hard and brittle, and is inferior in terms of stress.

Compared to the above two types of epoxy resin materials, the dimethylene ether bonded cresol no black type epoxy resin material according to the present invention utilizes the strong structure of the epoxy resin, which has the features of high crosslinking density and low stress. It has the contradictory properties of being both hard and soft.

Claims (3)

[Claims] (1) Phenol novolak type epoxy resin having a dimethylene ether group as a bonding group of a benzene ring and a pen/zene ring alone or in combination with an epoxy resin, a curing agent, a curing accelerator, a filler, a mold release agent, and a surface treatment. An epoxy resin composition consisting of agents, etc. (2) The epoxy resin composition according to claim (1), wherein dimethylene ether groups account for 30% or more of the bonding groups. (3) The epoxy resin composition according to claim (1), wherein the nomethylene ether bonded phenol nogelac type epoxy resin accounts for 30 or more parts of the entire epoxy resin.