JPH06212058A - Epoxy resin composition for sealing - Google Patents

Abstract

PURPOSE:To obtain the subject composition providing a light-weight sealed product having low water absorption characteristics, suitable for sealing by transfer molding, having excellent mechanical performances by blending an epoxy resin with a curing agent, an inorganic filler and specific fibers. CONSTITUTION:(A) An epoxy resin (e.g. cresol novolak type epoxy resin or bisphenol A type epoxy resin) is blended with (B) a curing agent (e.g. aliphatic amine or acid anhydride), (C) an inorganic filler (e.g. silica or alumina) and (D) wholly aromatic polyester fibers to give the objective composition. Short fibers comprising a wholly aromatic polyester composed of >=50mol% of a unit of formula I and having the ratio of the unit of formula I to a unit of formula II of 60:40-90:10 (mol%), having 1-3mm length are preferable as the component D. The amount of the component D blended is preferably 1-7wt.% based on the total of the components A to C.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an epoxy resin composition for encapsulation and an encapsulation product produced by using the composition.
Specifically, the present invention has a good moldability, is lightweight, has excellent mechanical properties such as impact resistance, and can provide a sealing product with low water absorption (low moisture absorption), and an epoxy resin composition for sealing. And a sealed product produced using the composition.

[0002]

2. Description of the Related Art For electronic and electric parts, lightness, thinness, shortness, miniaturization, multi-functionality, high reliability, etc. are required more and more, and under such circumstances, electronic elements and a plurality of electronic elements are required. As a sealing material for electronic / electrical parts such as substrates, coils, small transformers, small motor armatures, etc., on which epoxy resin with low water absorption is excellent in terms of heat resistance, electrical characteristics, light weight, etc. It is also widely used.

In a sealing technique using an epoxy resin, a transfer molding method with a low molding pressure or a potting method in which a liquid epoxy resin is poured is adopted. In both cases, shrinkage due to curing of the epoxy resin, and epoxy resin There are problems such as an increase in internal stress due to an unbalanced difference in the coefficient of thermal expansion with the parts to be sealed, the occurrence of cracks, deformation of the wiring, etc.There are various ways to improve the reliability of the sealed product. Being tried. As one of such attempts, a large amount of an inorganic filler is added to the epoxy resin to reduce the curing / shrinkage of the epoxy resin and the difference in coefficient of thermal expansion between the epoxy resin and the parts to be encapsulated. However, there is a problem that mechanical performance such as impact resistance of the encapsulation product obtained by compounding a large amount of inorganic filler is deteriorated, and the weight of the product is increased, etc. Is required.

Further, in the case of encapsulating electronic / electrical parts and the like by the potting method described above, a liquid resin is poured into a container made of a metal or the like in a state where it is molded and solidified to form an encapsulated part. Generally, a method of manufacturing a sealed product in which a container made of resin, a metal, or the like is integrally bonded is used. However, the potting method has a drawback that the molding process is more complicated than the transfer molding, and the entire product becomes heavy due to the presence of the outer container (outer shell) made of metal or the like. Therefore, it is desirable to easily manufacture a sealed product that has excellent mechanical performance such as impact resistance, even though it has no outer shell and is lightweight, by transfer molding or the like. The development of compositions has been sought.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is that it is excellent in moldability and can be easily and smoothly molded for sealing by transfer molding or the like, and is lightweight.
An epoxy resin composition for sealing, which has excellent mechanical properties such as impact resistance and low water absorption (low moisture absorption), and a sealed product.

[0006]

As a result of continued research by the present invention, it has been found that a wholly aromatic polyester fiber is further contained in a sealing epoxy resin composition containing an epoxy resin, a curing agent and an inorganic filler. The present invention has been completed by finding that the above problems can be solved.

That is, the present invention is an epoxy resin composition for sealing which is characterized by containing a wholly aromatic polyester fiber together with an epoxy resin, a curing agent and an inorganic filler. And this invention includes the sealing product manufactured using the said epoxy resin composition for sealing.

By the way, a wholly aromatic polyamide fiber is widely known as a synthetic fiber reinforcing material for a synthetic resin molded article. However, when a wholly aromatic polyamide fiber is blended in an epoxy resin composition for encapsulation, Since the water absorption of the composition is increased, high electrical insulation is required, and therefore, it is completely unsuitable for encapsulation of electronic / electrical parts and the like in which moisture must be avoided as much as possible. On the other hand, in the encapsulating epoxy resin composition of the present invention containing a wholly aromatic polyester fiber, the problem of increased water absorption does not occur, and while keeping the composition low in water absorption, its impact resistance It was possible to greatly improve the mechanical performance such as sex,
It can be said that such an excellent effect in the present invention is completely unexpected from the conventionally well-known reinforced plastic technology using wholly aromatic polyamide fibers.

In the present invention, any epoxy compound having two or more epoxy groups in the molecule can be used as the epoxy resin, and its chemical structure, molecular weight and epoxy equivalent are not particularly limited. Among them, the epoxy resin conventionally used for sealing is desirable, and the one particularly suitable for the transfer molding method is preferable, but of course, a cast type or other one can also be used. Examples of the epoxy resin usable in the present invention include cresol novolac type epoxy resin, phenol novolac type epoxy resin, bisphenol A type epoxy resin, alicyclic epoxy resin,
Examples thereof include brominated epoxy resin, glycidyl ester type epoxy resin, glycidyl amine type epoxy resin, hydantoin type epoxy resin, etc. These epoxy resins may be used alone or in combination of two or more kinds. Good. The epoxy resin composition of the present invention
When used for electrical encapsulation, it is preferable that the epoxy resin contains as little ionic impurities and hydrolyzable substances as possible.

In the present invention, any curing agent for epoxy resin can be used as the curing agent. For example, phenol resin type curing agents such as phenol novolac resin and cresol novolac resin, aliphatic amine, alicyclic polyamine, Examples include amine curing agents such as aromatic polyamines, acid anhydrides, and the like. The amount of the curing agent used is preferably such that the ratio of the epoxy groups of the epoxy resin and the epoxy reactive groups of the curing agent are balanced. It is preferable to combine the epoxy resin and the curing agent in consideration of the type of the material forming the component to be sealed and the use of the sealed product.

As the inorganic filler used in the present invention, any of the inorganic fillers used for epoxy resins can be used, for example, silica, alumina, calcium carbonate, calcium silicate, talc, barium sulfate. ,
Examples thereof include glass and the like, and these inorganic fillers may be powdery or fibrous. The inorganic filler may be used alone or in combination of two or more.

In the epoxy resin composition of the present invention, the inorganic filler is added in an amount of 150 to 45 per 100 parts by weight of the epoxy resin.
It is preferably used in a proportion of 0 parts by weight, 175-42
It is more preferable to use 5 parts by weight. When the amount of the inorganic filler used is less than 150 parts by weight, the shrinkage of the epoxy resin composition at the time of curing becomes large, or the difference in the heat shrinkage ratio between the component to be sealed and the epoxy resin becomes large, and thus the sealing In some cases, the internal stress of the final product increases, cracks and other problems easily occur in the sealed product, and the reliability decreases. On the other hand, if the amount exceeds 450 parts by weight, the flowability of the epoxy resin composition may be deteriorated and the sealing moldability may be deteriorated, or the wear of the mold during molding may be increased.

The epoxy resin composition of the present invention contains wholly aromatic polyester fiber as an essential component,
The "whole aromatic polyester" used herein mainly has a repeating unit containing an aromatic dicarboxylic acid component and an aromatic diol component, and / or a repeating unit containing an aromatic hydroxycarboxylic acid component. The wholly aromatic polyester is a small amount (usually 20 mol% or less) in some cases.
It may have other repeating units of.

Typical examples of the repeating units constituting the wholly aromatic polyester include the units represented by the following formulas (I) to (VII).

[0015]

[Chemical 3]

[0016]

[Chemical 4]

[0017]

[Chemical 5]

[0018]

[Chemical 6]

[0019]

[Chemical 7]

[0020]

[Chemical 8]

[0021]

[Chemical 9]

However, the units are not limited to the repeating units of the above formulas (I) to (VII), and include other aromatic dicarboxylic acid units, aromatic diol units and / or aromatic hydroxycarboxylic acid units. You can leave.

The most typical wholly aromatic polyester suitable for constituting the wholly aromatic polyester fiber used in the present invention is a wholly aromatic polyester mainly composed of repeating units of the above formulas (I) and (II). Mention may be made of polyester. From the viewpoint of mechanical performance such as impact resistance and thermal characteristics of the sealed product obtained in that case, 50 mol% or more of the wholly aromatic polyester constituting the fiber is composed of the repeating unit of the formula (I). It preferably contains less than 50 mol% of recurring units of formula (II) and optionally small amounts of other aromatic ester units, in particular recurring units of formula (I): ) Repeat unit is 60:40 to 90:10
A wholly aromatic polyester in a proportion of 1 mol% of

The wholly aromatic polyester fiber used in the present invention can be produced by melt spinning the above-mentioned wholly aromatic polyester, and as a typical example of such wholly aromatic polyester fiber. "Vectran fiber" (trade name) manufactured by Kuraray Co., Ltd. can be mentioned.

As the wholly aromatic polyester fiber, it is preferable to use a short fiber having a length of 0.5 to 6 mm.
3 mm short fibers are more preferred. When short fibers having a length of less than 0.5 mm are used, mechanical properties such as impact resistance tend to be insufficient, while when using wholly aromatic polyester fibers having a length of 6 mm or more, In addition, it becomes difficult to uniformly disperse the wholly aromatic polyester fibers in the epoxy resin composition, and it becomes difficult to achieve improvement in mechanical performance.

In the epoxy resin composition of the present invention, the content of wholly aromatic polyester fiber is based on the total weight of the epoxy resin, the curing agent and the inorganic filler.
It is preferably in the range of 0.5 to 10% by weight from the viewpoint of mechanical properties such as moldability of the composition and impact resistance of the obtained sealed product, and more preferably in the range of 1 to 7% by weight. If the proportion of wholly aromatic polyester fiber is less than 0.5% by weight, the effect of improving mechanical properties such as impact resistance is not sufficient, while if it exceeds 10% by weight, the dispersibility of the fiber is impaired and molding is performed. Property is likely to decrease.

The epoxy resin composition of the present invention may contain optional components such as a curing accelerator, a release agent, a flame retardant, a coloring material, and a flexibility-imparting agent, in addition to the above components. You can For example, curing accelerators include imidazoles, tertiary amines, organic phosphines, BF ₃ · amine complex, etc., release agents such as carnauba wax and montan wax, stearic acid, and flame retardants. Examples include halogenated epoxy resins and antimony trioxide, carbon black as a colorant, and silicone compounds for surface treatment such as a silane coupling agent as a flexibility-imparting agent.

In the preparation of the epoxy resin composition of the present invention, a mixer, a heat roll, a kneader, a universal mixing stirrer, a melt extruder, etc., depending on the type, mixing ratio, properties, etc. of each component constituting the composition. Any device and method such as the melt-kneader can be used and is not particularly limited.

The epoxy resin composition of the present invention can be used for encapsulating various electronic devices, electronic / electrical components, or any other articles, and the kind and structure of the article to be encapsulated. The shape and the like are not particularly limited. And as the sealing method at that time, depending on the properties of the epoxy resin composition (for example, liquid or solid), the type and use of the article to be sealed,
A transfer molding method, a potting method, or another method can be adopted, and it is particularly suitable for sealing by the transfer molding method.

[0030]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited thereto. The water absorption and notched Izod impact strength of the molded plates obtained in the following examples and comparative examples are measured according to JIS K691.
It carried out according to 1.

Example 1 (1) Cresol novolac type epoxy resin (epoxy equivalent 205; "180H" manufactured by Yuka Shell Epoxy Co., Ltd.)
100 parts by weight, novolac type phenolic resin ("Tamanol 759" manufactured by Arakawa Chemical Industry Co., Ltd.) 51.2 parts by weight, triphenylphosphine 1.3 parts by weight, silica powder 353 parts by weight, carnauba wax 1 part by weight, and wholly aromatic. Polyester fiber [Vectran fiber manufactured by Kuraray Co., Ltd .;
After mixing 15 parts by weight of a fiber length of 1 mm), 65 to 70 ° C
After kneading and aging, the obtained kneaded product was pulverized to prepare an epoxy resin composition. (2) Using the mold obtained by heating the epoxy resin composition obtained in (1) above to 180 ° C. by the transfer molding method,
After molding for 3 minutes, remove from the mold and have a thickness of 3m
A molded plate having m, a width of 150 mm and a length of 200 mm was obtained. This was heated at 180 ° C. for 2 hours to be post-cured. (3) A test piece of a predetermined size was cut out from the molded plate produced in (2) above, and its water absorption and notched Izod impact strength were measured. The results are shown in Table 1 below.

Example 2 (1) 100 parts by weight of inorganic filler-containing epoxy resin (“XNR5002” manufactured by Ciba-Geigy Japan; inorganic filler silica powder; inorganic filler content 53.5% by weight), inorganic filler content Modified alicyclic acid anhydride ("Ciba Geigy""X
NH5002 "; inorganic filler silica powder; inorganic filler content 65% by weight) 90 parts by weight, carnauba wax 0.5 parts by weight, and wholly aromatic polyester fiber [" Vectran fiber "manufactured by Kuraray Co., Ltd .; fiber length 3 mm ) 3.9 parts by weight was mixed with a universal mixing stirrer at room temperature for 2 minutes to prepare an epoxy resin composition. (2) The epoxy resin composition obtained in (1) above was molded by transfer molding for 4 minutes using a mold heated to 140 ° C., and then taken out from the mold and a molding plate of the same size as in Example 1 Got This molded plate was heated at 150 ° C. for 3 hours to be post-cured. (3) A test piece of a predetermined size was cut out from the molded plate produced in (2) above, and its water absorption and notched Izod impact strength were measured. The results are shown in Table 1 below.

Comparative Example 1 An epoxy resin composition was produced in the same manner as in Example 1 except that the wholly aromatic polyester fiber was not added, and a molded plate was produced in the same manner as in Example 1, The water absorption and the Izod impact strength with notch were measured and found to be as shown in Table 1 below.

Comparative Example 2 An epoxy resin composition was produced in the same manner as in Example 2 except that the wholly aromatic polyester fiber was not added, and a molded plate was produced in the same manner as in Example 1, The water absorption and the Izod impact strength with notch were measured and found to be as shown in Table 1 below.

[0035]

[Table 1]  Water absorption Notched Izod impact strength (wt%) (kg-cm / cm²)  Example 1 0.02 3.5 Comparative Example 1 0.02 1.6  Example 2 0.02 9.3 Comparative Example 2 0.02 1.7

From the results shown in Table 1 above, in Examples 1 and 2 in which the wholly aromatic polyester fiber was blended in the epoxy resin composition, the impact resistance of the molded product was significantly improved while maintaining low water absorption. You know you will get. Also, for reference, an epoxy resin composition was prepared in the same manner as in Example 2 except that the compounding amount of the wholly aromatic polyester fiber in Example 2 was changed to 135 parts by weight. It was difficult to obtain a good epoxy resin composition because it was not carried out uniformly.

<Embodiment 3> As an electrical component, a diameter of 14
mm and 40 mm in length, a magnetic sensing element was previously mounted in a mold for transfer molding (mold cavity volume: about 31 cm ³ ), and the epoxy resin composition prepared in Example 2 was transfer molded therein, and the weight was 7 g. It was possible to extremely easily and smoothly manufacture a light-sealed product having good impact resistance capable of withstanding practical use. On the other hand, when the magnetic sensing element was similarly sealed and molded using the epoxy resin composition of Comparative Example 2, the impact resistance of the obtained sealed product was extremely low, and it was practically used. I didn't get it.
Therefore, in order to impart impact resistance to the sealed product, an iron outer shell container is manufactured in advance, the above magnetic sensing element is mounted in the container, and the epoxy resin composition of Comparative Example 2 is injected therein. When a process of manufacturing a sealed product was performed, the sealing molding operation was extremely complicated and time-consuming, and the weight of the obtained sealed product was heavy.

[0038]

The encapsulating epoxy resin composition of the present invention containing the wholly aromatic polyester fiber together with the inorganic filler is extremely excellent in moldability. When used to manufacture sealed products by transfer molding or other methods, it is lightweight, has low water absorption (low moisture absorption), has excellent mechanical performance such as impact resistance, and has small internal stress and cracking. It is possible to smoothly manufacture a highly reliable encapsulation product that does not cause troubles such as deformation and deformation by an extremely simple operation, and the encapsulation epoxy resin composition of the present invention is particularly an encapsulation molding technique by a transfer molding method. Suitable for

Claims (4)

[Claims] 1. An epoxy resin composition for encapsulation, which comprises wholly aromatic polyester fibers together with an epoxy resin, a curing agent and an inorganic filler. 2. The epoxy resin composition for encapsulation according to claim 1, which contains the wholly aromatic polyester fiber in a proportion of 0.5 to 10% by weight based on the total weight of the epoxy resin, the curing agent and the inorganic filler. . 3. The wholly aromatic polyester fiber has the following formula:
(I); And the following formula (II); The epoxy resin composition for encapsulation according to claim 1 or 2, which is a fiber mainly composed of a wholly aromatic polyester composed of repeating units represented by 4. A sealed product produced using the epoxy resin composition for sealing according to claim 1.