JPH06128360A - Liquid epoxy resin composition - Google Patents

Abstract

PURPOSE:To provide the title compsn. which has a low viscosity and gives a cured article excellent in adhesiveness, water resistance, electrical properties, heat resistance, etc., and high in reliability. CONSTITUTION:The compsn. contains an epoxy resin which is liq at normal temp. and has at least two epoxy groups in the molecule and a phenolic curative comprising an arom. compd. having at least three phenolic hydroxyl groups in the molecule and a phenolic hydroxyl equivalent of 60 or lower.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid epoxy resin composition used for various applications in the electric and electronic fields, such as adhesives, casting materials, encapsulating materials, and laminated products.

[0002]

2. Description of the Related Art Epoxy resin compositions have excellent electrical performance and adhesive strength, and are therefore used in various applications in the electric and electronic fields. It is known that the epoxy resin composition uses various curing agents at the time of curing, and that the performance of the cured product greatly varies depending on the type of the curing agent, and the curing agent is properly used depending on the application. For example, amine-based curing agents are used because adhesiveness is the most important for adhesives and laminated products, and acid anhydride-based curing agents are used for casting materials in terms of electrical performance and low viscosity. A phenolic curing agent is used from the viewpoint of water resistance in the encapsulating material application.

However, when an amine curing agent is used, hygroscopicity and electrical insulation are poor, and when an acid anhydride curing agent is used, adhesion and long-term water resistance are poor. When a phenol-based curing agent is used, a high-molecular weight and large phenolic hydroxyl group equivalent is usually used as the phenol-based curing agent, so that the fluidity of the epoxy resin composition is deteriorated and a molding material is used. There is a problem that it can only be used for its intended purpose.

It is considered that these problems occur due to the following reasons. When an amine-based curing agent is used, the hygroscopicity is inevitably high because a tertiary amine structure exists in the crosslinked structure of the cured product. When an acid anhydride-based curing agent is used, the long-term water resistance is poor because the ester structure in the crosslinked structure of the cured product is easily chemically hydrolyzed.
It is essential that the cured product is inferior in adhesiveness because the reaction between the acid anhydride group of the curing agent and the epoxy group of the epoxy resin makes it difficult for an alcoholic hydroxyl group that contributes to adhesion to be produced as a by-product. When using a phenolic curing agent,
As the curing agent, a phenol novolac resin is generally used, and since the molecular weight thereof is large and the addition equivalent of the phenol novolac resin curing agent to the epoxy resin is large (50 PHR or more), the viscosity of the composition is very high. It becomes too high to be practical. However, in terms of the balance of physical properties such as adhesiveness, water resistance, and electrical performance, the phenolic curing agent is the most excellent curing agent.

Since recent electronic parts tend to be higher in density and thinner, a so-called chip-on-board or TAB in which a bare chip is mounted and sealed with a liquid sealing material from a conventional transfer-molded package. The method is being replaced. As a conventional liquid encapsulating material, an epoxy resin composition using an amine-based or acid anhydride-based curing agent is predominant because of its limited viscosity. However, the liquid encapsulant composed of an epoxy resin composition using an amine-based or acid anhydride-based curing agent is compared to a transfer molding material composed of the epoxy resin composition using the above-mentioned phenol novolac resin curing agent. Poor overall reliability. Therefore, it is strongly desired to improve the reliability of the liquid sealing material. As described above, an epoxy resin composition using a phenolic curing agent can theoretically exhibit the highest degree of reliability. Therefore, it is necessary to apply this composition to a liquid encapsulant or a die bond adhesive. If possible, its industrial value will be extremely high.

Conventionally, the following methods (1) to (4) have been proposed in order to make up for the drawback of high viscosity of the epoxy resin composition using a phenolic curing agent. A method using a solvent (for example, "Nikkei Microdevice", April 1989, p. 97-103, JP-A-3).
(See Japanese Patent Publication No. 181547). A method in which an amine curing agent is used in combination (see, for example, JP-A-62-124117).

A method in which an acid anhydride curing agent is used in combination.

[0008]

However, although the above-mentioned method is easy to handle, it is necessary to prevent the solvent from remaining at the time of curing, so that it can be applied only to a very thin film-like application. In the above methods and, since a phenolic curing agent and another curing agent are used in combination,
Of the curing of the epoxy resin, the curing with the phenolic curing agent can be performed only on a part of the epoxy resin, and the above-mentioned improvement in reliability due to the use of the phenolic curing agent cannot be said to be sufficient.

Therefore, the present invention can improve the above-mentioned drawbacks of the prior art and provide a highly reliable cured product having excellent adhesiveness, adhesion, water resistance, electrical characteristics, heat resistance, etc. An object is to provide a liquid epoxy resin composition having a viscosity.

[0010]

In order to solve the above-mentioned problems, the inventors of the present invention have conducted various studies and, as a result, confirmed the following by experiments and completed the present invention. A phenol novolac resin, which is a typical phenolic curing agent used in conventional epoxy resin compositions, has a high hydroxyl equivalent of about 100 to 110. Therefore, for example, in order to compound this in an equivalent amount with bisphenol A diglycidyl ether, which is the most standard liquid epoxy resin, 5
It is necessary to add a large amount of 0 to 60 PHR, and the average molecular weight of the phenol novolac resin is 4
Since it is more than 00, the viscosity of the composition tends to increase. Therefore, as a phenolic curing agent, it has a low molecular weight, and
It has 3 or more hydroxyl groups (phenolic hydroxyl groups) bonded to an aromatic ring in one molecule, and the equivalent of phenolic hydroxyl groups is 6
By using an aromatic compound as low as 0 or less, the addition equivalent of the phenolic curing agent to the epoxy resin can be reduced, and the increase in the viscosity of the composition at the time of addition can be suppressed. Moreover, the effect of lowering the viscosity is
That is, when the composition is cured, it can be obtained without impairing the formation of a crosslinked structure that exhibits desired performance.

Therefore, the present invention provides a liquid epoxy resin composition which has two or more epoxy groups in one molecule and which contains, as essential components, an epoxy resin which is liquid at room temperature and a phenolic curing agent. The liquid epoxy resin composition is characterized in that the phenol-based curing agent is an aromatic compound having 3 or more phenolic hydroxyl groups in one molecule and having a phenolic hydroxyl group equivalent of 60 or less.

The epoxy resin used in the present invention, which has two or more epoxy groups in one molecule and is liquid at room temperature, is not particularly limited. For example, bisphenol A diglycidyl ether and other bisphenols. A
Type epoxy resin; glycidyl amine type epoxy resin;
Examples thereof include alicyclic epoxy resins; polyglycidyl ethers such as trimethylolpropane and glycerol; glycidyl esters such as phthalic acid. These may use only 1 type and may use 2 or more types together. The epoxy resin is not limited to the above. For example,
Even if it is an epoxy resin that is solid at room temperature, it can be used as an epoxy resin if the mixture thereof exhibits a liquid state by being used in combination with the liquid epoxy resin, and, if necessary, A monofunctional epoxy resin having only one epoxy group in one molecule may be used as a diluent.

The phenolic curing agent used in the present invention has three or more phenolic hydroxyl groups in one molecule,
Moreover, it is an aromatic compound having a phenolic hydroxyl group equivalent of 60 or less. Here, the phenolic hydroxyl group means a hydroxyl group bonded to an aromatic ring, and the phenolic hydroxyl group equivalent (g / eq.) Is a value obtained by dividing the molecular weight by the number of phenolic hydroxyl groups in one molecule. means. The type of aromatic ring is not limited to a benzene ring, and may be, for example, a naphthalene ring.
The number of aromatic rings in one molecule of the aromatic compound is not limited to one, and may be two or more.

The aromatic compound having 3 or more phenolic hydroxyl groups in one molecule and having a phenolic hydroxyl group equivalent of 60 or less is not particularly limited, but specific examples thereof include
For example, compounds such as pyrogallol and phloroglucin having 3 or more hydroxyl groups bonded to the benzene ring and their alkyl-substituted compounds, compounds having 4 or more hydroxyl groups bonded to the naphthalene ring, and alkyls thereof Examples thereof include substituted compounds, condensates of pyrogallol with formalin, acetone or methylethylketone (MEK), and compounds in which three hydroxyl groups are bonded to both benzene rings of benzophenone. They are,
You may use only 1 type and may use 2 or more types together. Among these, it is most preferable to use at least one of pyrogallol and phloroglucin because of easy synthesis and easy availability of industrial chemicals.

In the present invention, it is not always necessary to cure the epoxy resin only with the above-mentioned phenolic curing agent, and a phenolic curing agent and another curing agent may be used in combination. However, in order to obtain a cured product having desired physical properties, the ratio of phenolic hydroxyl groups to the total curing groups that reacts with the epoxy groups in the epoxy resin and cures the epoxy resin is stoichiometrically 50% or more. It is preferable to use a phenolic curing agent.

Other curing agents that can be used in combination with the phenol type curing agent are not particularly limited, but liquid acid anhydrides are preferable from the viewpoint of low viscosity and high heat resistance. The liquid acid anhydride is not particularly limited, but examples thereof include methyltetrahydrophthalic anhydride and methylhexahydrophthalic anhydride. These may use only 1 type and may use 2 or more types together.

With respect to the total amount of the curing agent used in the present invention, all curing groups containing a phenolic hydroxyl group in the curing agent are stoichiometrically 0.7 to 1. It is preferably 3 equivalents, and 0.8 to
It is more preferably 1.1 equivalents. The liquid epoxy resin composition of the present invention, if necessary, a curing accelerator,
Various additives such as a filler, a flame retardant, a coupling agent, a surfactant and a colorant can be added.

The method for producing the liquid epoxy resin composition according to the present invention, the method for curing the liquid epoxy resin composition, etc. are not particularly limited, and for example, the method similar to the conventional liquid epoxy resin composition can be used.

[0019]

In a liquid epoxy resin composition having two or more epoxy groups in one molecule and containing, as essential components, an epoxy resin that is liquid at room temperature and a phenol-based curing agent, When an aromatic compound having 3 or more phenolic hydroxyl groups in one molecule and having a phenolic hydroxyl group equivalent of 60 or less is used, the addition equivalent of the phenolic curing agent to the epoxy resin can be reduced. At the same time, since the molecular weight of the phenol-based curing agent is low, the viscosity increase of the composition due to the addition of the phenol-based curing agent is reduced. Moreover, this effect of lowering the viscosity can be obtained without impairing the formation of a crosslinked structure that exhibits desired performance when the composition is cured.

Further, in this invention, a polyfunctional epoxy resin having two or more epoxy groups in one molecule is always used as the epoxy resin component. If,
When only a monofunctional epoxy resin having only one epoxy group in one molecule is used as the epoxy resin component,
Hardening does not occur easily.

[0021]

EXAMPLES Examples and comparative examples of the present invention will be shown below, but the present invention is not limited to the following examples. In the following Examples and Comparative Examples, "part" means "part by weight". -Example 1-Bisphenol A type epoxy resin (YD8125, Toto Kasei, epoxy equivalent 175) 1 as an epoxy resin
00 parts and pyrogallol as a phenol-based curing agent (Wako Chemical Reagent, phenolic hydroxyl group equivalent 42) 24
Parts (1.0 equivalent to epoxy resin),
By stirring at 0 ° C, the solid component pyrogallol was dissolved. The obtained homogeneous solution-form epoxy resin composition was cooled to room temperature, but no precipitation of pyrogallol was observed, and a uniform solution state was maintained.

The viscosity of this epoxy resin composition at 25 ° C. was measured by a block field type rotational viscometer,
The results are shown in Table 1. Next, 1 wt% of SA102 (DBA salt manufactured by San-Apro Co., Ltd.) as a curing accelerator was added to the epoxy resin composition, and the obtained mixture was cast between glass plates and dried at 120 ° C. in a drier. Heated for 1 hour. Then, a cured product was obtained by heat treatment at 160 ° C. for 6 hours.

The glass transition temperature (Tg) of the obtained cured product was measured with a viscoelasticity spectrometer (DMS110 type, manufactured by Seiko Denshi KK), and the results are shown in Table 1.
It was shown to. -Example 2-In Example 1, as the phenol-based curing agent, instead of pyrogallol, phloroglucin (a water-containing product of a reagent manufactured by Wako Chemical Co., Ltd., dried and dehydrated at 150 ° C for 24 hours was used. Phenolic hydroxyl group equivalent 42, solid state) A uniform solution type epoxy resin composition was obtained in the same manner as in Example 1 except that 24 parts (1.0 equivalent to the epoxy resin) was used. When this epoxy resin composition was cooled to room temperature,
No precipitation of phloroglucin was observed, and a uniform solution state was maintained.

The viscosity of this epoxy resin composition at 25 ° C. was measured in the same manner as in Example 1, and the results are shown in Table 1. Next, a curing accelerator was added to this epoxy resin composition in the same manner as in Example 1 and cast-cured to obtain a cured product. The glass transition temperature (Tg) of the obtained cured product was measured in the same manner as in Example 1,
The results are shown in Table 1.

Comparative Example 1 In Example 1, 60 parts of phenol novolac resin (manufactured by Gunei Chemical Industry Co., Ltd., phenolic hydroxyl group equivalent 105) instead of pyrogallol as the phenol-based curing agent (1.0 equivalent to the epoxy resin). An epoxy resin composition was obtained in the same manner as in Example 1 except that But,
The epoxy resin composition showed no fluidity when cooled to room temperature.

This epoxy resin composition was heated and cast-cured in a fluid state to obtain a cured product. The glass transition temperature (Tg) of the obtained cured product was measured in the same manner as in Example 1, and the results are shown in Table 1.

[0027]

[Table 1]

-Examples 3 to 7-Each epoxy resin was prepared in the same manner as in Example 1 except that the addition equivalent of pyrogallol to the epoxy resin was changed from 1.0 to the value shown in Table 2. A composition was obtained. The viscosity of each obtained epoxy resin composition and the glass transition temperature (Tg) of a cured product obtained by curing these compositions in the same manner as in Example 1 were measured by the same method as in Example 1. did. The results are shown in Table 2.

[0029]

[Table 2]

FIG. 1 shows the first embodiment and the third to seventh embodiments.
Based on the results of measuring the viscosity of the epoxy resin composition obtained in Example 1 and the glass transition temperature (Tg) of the cured product (see Tables 1 and 2), the addition equivalent of pyrogallol to the epoxy resin and the viscosity of the epoxy resin composition And a relationship between the addition equivalent of pyrogallol to the epoxy resin and the glass transition temperature (Tg) of the cured product.

As shown in this figure, if the addition equivalent of pyrogallol is too large, the viscosity is increased and Tg is lowered. Conversely, if the addition equivalent of pyrogallol is too small, the viscosity is lowered but Tg is extremely lowered. It was also confirmed that it is preferable to use pyrogallol at around 0.7 to 1.3 equivalents. —Example 8— In Example 1, the amount of the bisphenol A type epoxy resin used was changed to 80 parts, and the bisphenol A type epoxy resin and the alicyclic epoxy resin represented by the following formula 1 were used as the epoxy resin. (Celoxide 2021,
An epoxy resin composition was obtained in the same manner as in Example 1 except that 15.7 parts of an epoxy equivalent 137) manufactured by Daicel was used in combination.

[0032]

[Chemical 1]

Example 9 In Example 1, the amount of the bisphenol A type epoxy resin used was changed to 40 parts, and this bisphenol A type epoxy resin and the above formula 1 were used as the epoxy resin.
An epoxy resin composition was obtained in the same manner as in Example 1 except that 47 parts of the alicyclic epoxy resin represented by (the same as that used in Example 8) was used in combination.

The viscosity of each epoxy resin composition obtained in Examples 8 and 9 and the glass transition temperature (Tg) of the cured product obtained by curing these compositions in the same manner as in Example 1 were measured. The measurement was performed in the same manner as in Example 1. The results are shown in Table 3.

[0035]

[Table 3]

-Examples 10 to 17-Each epoxy resin composition was obtained by blending the components in the types and amounts shown in Tables 4 and 5 in the same manner as in Example 1. In these epoxy resin compositions, pyrogallol and an acid anhydride are used together as a curing agent. The viscosity of each of the obtained epoxy resin compositions and the glass transition temperature (Tg) of a cured product obtained by curing these compositions in the same manner as in Example 1.
Was measured in the same manner as in Example 1. The results are shown in Tables 4 and 5.

[0037]

[Table 4]

[0038]

[Table 5]

The notes to Tables 4 and 5 above are as follows: YD8125: Bisphenol A type epoxy resin (manufactured by Tohto Kasei, epoxy equivalent 175). Celoxide 2021: An alicyclic epoxy resin represented by Formula 1 (manufactured by Daicel, epoxy equivalent 137).

Triglycidyl isocyanurate: Compound represented by the following formula (2) (manufactured by Mitsubishi Gas Chemical Co., Ltd., epoxy equivalent 9
9).

[0041]

[Chemical 2]

EX321: trimethylolpropane polyglycidyl ether (manufactured by Nagase Kasei Co., Ltd., epoxy equivalent 145). Pyrogallol: Wako chemical reagent, phenolic hydroxyl group equivalent 42. Epicron B-650: Methylhexahydrophthalic anhydride (manufactured by Dainippon Ink and Chemicals, Inc., acid anhydride equivalent 168).

Epicron B-4400: acid anhydride represented by the following formula 3 (manufactured by Dainippon Ink and Chemicals, Inc., acid anhydride equivalent 1
32).

[0044]

[Chemical 3]

[0045]

The liquid epoxy resin composition according to the present invention can give a highly reliable cured product having excellent adhesiveness, adhesion, water resistance, electrical characteristics, heat resistance and the like, and has a low viscosity. is there. Therefore, this composition has various applications in the electric and electronic fields, such as adhesives, casting materials, encapsulating materials,
It is suitable for laminated products and is very useful.

[Brief description of drawings]

FIG. 1 shows the viscosity of the epoxy resin compositions obtained in Example 1 and Examples 3 to 7 and the glass transition temperature (T
Based on the result of measuring g), the relationship between the addition equivalent of pyrogallol to the epoxy resin and the viscosity of the epoxy resin composition, and the relationship between the addition equivalent of pyrogallol to the epoxy resin and the glass transition temperature (Tg) of the cured product. It is the graph which also showed.

Claims (3)

[Claims] 1. A liquid epoxy resin composition having, as essential components, an epoxy resin which has two or more epoxy groups in one molecule and is liquid at room temperature, and a phenolic curing agent, wherein the phenolic curing is performed. A liquid epoxy resin composition, wherein the agent is an aromatic compound having 3 or more phenolic hydroxyl groups in one molecule and having a phenolic hydroxyl group equivalent of 60 or less. 2. The liquid epoxy resin composition according to claim 1, wherein the phenol-based curing agent is at least one of pyrogallol and phloroglucin. 3. The liquid epoxy resin composition according to claim 1, wherein a liquid acid anhydride is also used as a curing agent.