JP2000290351A - Epoxy resin curing agent - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a curing agent used to give a cured product being excellent in heat resistance and humidity resistance and having low stress properties by using a phenol/alkylbenzene/aldehyde resin prepared by reacting an alkylbenzene/aldehyde resin with a phenol and reacting the obtained product with a difunctional aldehyde. SOLUTION: An alkylbenzene of formula I (wherein R1 is a 1-8C alkyl; and m is 1-4) is reacted with an aldehyde of formula II (wherein R2 is H or a 1-7C hydrocarbon group) in the presence of an acid to obtain an alkylbenzene/ aldehyde resin (A). Resin A is reacted with a phenol (Z) represented by formula III (wherein R3 is H, a 1-8C alkyl, an alkenyl, or a halogen; and n is 1-3) in a weight ratio in the range: 1<=Z/A<=20 in the presence of an acid catalyst. The obtained product is reacted with difunctional aldehydes (Y) represented by formula IV (wherein p is 0-3) and/or formula V in an amount to give a molar ratio Y/Z in the range of 0.1<=Y/Z<=0.8 to obtain an epoxy resin curing agent comprising a phenol/alkylbenzene/aldehyde resin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an epoxy resin curing agent, and more particularly to a cured epoxy resin having heat resistance, low stress,
The present invention relates to an epoxy resin curing agent composed of a phenol / alkylbenzene / aldehyde resin which has excellent moisture resistance and is suitable for use as a sealing material for semiconductors.

[0002]

2. Description of the Related Art Conventionally, acid anhydrides, amine compounds, imidazole compounds,
Novolak type phenolic resin has been used, but as a curing agent for epoxy resin for semiconductor encapsulants, novolak type epoxy resin is excellent because of its excellent moldability, heat resistance, moisture resistance and electrical properties after curing. Phenolic resins are widely used.

In recent years, chips have become larger due to higher integration of integrated circuits, the mounting method has changed from the insertion method to surface mounting, and packages have become smaller and thinner. That is, since a large chip is exposed to a higher temperature than before in a state in which it is sealed in a thin package, a problem of a package crack occurs, and further reduction in stress and improvement in moisture resistance of the sealing material have been required.

In order to lower the stress and improve the moisture resistance of the sealing material, use of a xylene-modified phenol resin as a curing agent (Japanese Patent Application Laid-Open No. 59-105017) and use of a fluorine-containing novolak (Japanese Patent Application Laid-Open No. 64-74215). No.) was considered.
Also disclosed is a method for producing a polyhydroxy compound for an epoxy resin curing agent by condensing a phenol with a dimethylol derivative of a 4-alkylphenol or a 4-arylphenol (JP-A-62-119220).
No.). However, the strength of these curing agents decreased with the decrease in stress, and none of them was sufficiently satisfactory as a curing agent for an epoxy resin sealing material. Recently, the combination of biphenyl-type epoxy compound and xylylene-type phenol resin has made it possible to reduce the viscosity of the material and increase the filling rate of the filler, realizing apparently low water absorption and improvement in mechanical strength, This method has become mainstream. However, the glass transition temperature (Tg)
However, there is a problem in heat resistance, and low elasticity cannot be achieved because of high elastic modulus.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a phenol / alkylbenzene which is a cured product of an epoxy resin and has excellent heat resistance, low stress and moisture resistance, and is suitable as a curing agent for semiconductor encapsulants. -To provide an epoxy resin curing agent composed of an aldehyde resin.

[0006]

According to the present invention, there is provided a compound represented by the general formula (1):
An alkylbenzene-aldehyde resin (A) obtained by reacting an alkylbenzene represented by the general formula (2) with an aldehyde represented by the general formula (2) in the presence of an acid catalyst, and a phenol (Z) represented by the general formula (3) ) With a weight ratio of 1 ≦ (Z) /
(A) After reacting in the presence of an acid catalyst at ≦ 20, the bifunctional aldehyde represented by the general formula (4) is reacted with the phenol (Z) at a molar ratio of 0.1 ≦ (Y). / (Z) <0.
An epoxy resin curing agent comprising a phenol / alkylbenzene / aldehyde resin blended and reacted in step 8.

[0007]

Embedded image

Examples of the alkylbenzenes used in the present invention include toluene, xylene, mesitylene, cumene and the like, and m-xylene having good reactivity with aldehydes is preferred. Aldehydes are hydrocarbons having one aldehyde group and usually have 0 to 0 carbon atoms other than the aldehyde group.
7, from the viewpoint of reactivity with alkylbenzenes, formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde, isobutyraldehyde, isovaleraldehyde, and the like are preferable, and formaldehyde having high reactivity with alkylbenzenes is particularly preferable. If the number of carbon atoms other than the aldehyde group is 8 or more, steric hindrance is large, inhibiting the curing reaction between the epoxy group and the phenolic hydroxyl group,
It is not preferable because the curability of the resin composition decreases or the glass transition temperature of the cured product decreases.

Examples of phenols include phenol, cresol, t-butylphenol, t-octylphenol, allylphenol and the like. Phenol is particularly preferred because it gives a resin having a good balance between hydroxyl equivalent, softening point and solution viscosity. Examples of the bifunctional aldehyde include glyoxal, glutaraldehyde, terephthalaldehyde, isophthalaldehyde, and the like.Glyoxal and terephthalaldehyde are industrially produced, and it is possible to synthesize a target resin with high yield. It is preferable because it can be performed. The above-mentioned alkylbenzenes, aldehydes, phenols and bifunctional aldehydes are merely examples, and are not limited thereto. These may be used alone or as a mixture during the reaction.

In the present invention, the alkylbenzene-aldehyde resin (A) can be easily obtained by reacting an alkylbenzene with an aldehyde in the presence of an acid catalyst such as sulfuric acid. As an example, m-xylene-formaldehyde resin and the like are commercially available from Mitsubishi Gas Chemical Co., Ltd. under the trade name "Nicanol" and can be easily obtained. The phenol-alkylbenzene-aldehyde resin of the present invention is obtained by polycondensing the above-mentioned alkylbenzene-aldehyde resin (A) and phenol (Z) in the presence of an acid catalyst, and then difunctional aldehyde (Y).
Is reacted. As an example, a resin obtained by polycondensing m-xylene-formaldehyde resin with phenol in the presence of an acid catalyst and then reacting with glyoxal is represented by the general formula (5)
However, the present invention is not limited to this exemplified structure.

[0011]

Embedded image

In the present invention, the weight ratio of the alkylbenzene-aldehyde resin (A) to the phenol (Z) is 1 ≦
If (Z) / (A) ≦ 20, desired characteristics can be obtained, and particularly preferably 1.2 ≦ (Z) / (A) ≦ 8.0. When (Z) / (A) <1, the ratio of phenols in the phenol / alkylbenzene / aldehyde resin decreases, and the curability and moldability of the epoxy resin composition deteriorate. In the case of (Z) / (A)> 20, the ratio of the alkylbenzene / aldehyde resin in the phenol / alkylbenzene / aldehyde resin becomes small, and the cured product has a low elastic modulus, a low water absorption, a metal such as a lead frame and a silicon chip. The effects of the alkylbenzene / aldehyde resin such as high adhesiveness cannot be sufficiently exhibited. The molar ratio of the phenols (Z) to the bifunctional aldehydes (Y) is 0.1
≦ (Y) / (Z) ≦ 0.8 is preferable, and it is more preferable that 0.1 ≦ (Y) / (Z) ≦ 0.6. When (Y) / (Z)> 0.8, the weight-average molecular weight and the softening point may be too large to obtain the desired properties. The effect of reacting the functional aldehyde is poor, the weight average molecular weight and softening point of the product are too low, and when used as an epoxy resin curing agent, the heat resistance of the cured product tends to be insufficient.

In the present invention, the phenol / alkylbenzene / aldehyde resin has a hydroxyl equivalent of 100 to 200.
g / eq is preferable, and 120 to 150 g / eq is particularly preferable. If the hydroxyl group equivalent is less than 100 g / eq, the softening point and solution viscosity are low, and the composition is liquid or semi-solid at room temperature, which may cause problems in workability and a decrease in the room temperature storage property of a resin composition using the same. If it exceeds 200 g / eq, the distance between the crosslinking points between the epoxy group and the phenolic hydroxyl group will increase, and the curability of the resin composition may decrease, or the glass transition temperature of the cured product may decrease.

The softening point of the phenol / alkylbenzene / aldehyde resin is preferably from 60 to 110 ° C., more preferably from 75 to 110 ° C.
~ 95 ° C is more preferred. If the softening point is less than 60 ° C., the composition is liquid or semi-solid at room temperature, and there is a possibility that the workability may deteriorate, the curability of the resin composition may decrease, or the glass transition temperature of the cured product may decrease. If the temperature exceeds 110 ° C., the mixture does not melt sufficiently during the heating and mixing with the epoxy resin, and uniform mixing cannot be easily performed.

The solution viscosity of the phenol / alkylbenzene / aldehyde resin is preferably 20 to 90 μm ² / s,
In particular, 30 to 60 μm ² / s is more preferable. If the solution viscosity is less than 20 μm ² / s, there are many low molecular weight components not involved in the curing reaction in the resin, and the curability of the resin composition may be reduced, or the glass transition temperature of the cured product may be lowered. If it exceeds 90 μm ² / s, the melt viscosity is high and the fluidity is reduced, and poor moldability such as poor filling may occur.

The weight average molecular weight of the phenol / alkylbenzene / aldehyde resin is preferably from 400 to 3000, and more preferably from 600 to 1500. If the weight-average molecular weight is less than 400, the composition is liquid or semi-solid at room temperature, and there is a possibility that workability problems, curability of the resin composition may decrease, or glass transition temperature of the cured product may decrease. 3
If it exceeds 000, the melt viscosity is high and the fluidity is reduced, and poor moldability such as poor filling may occur.

These properties are determined by appropriately selecting the mixing ratio of alkylbenzenes and aldehydes, the reaction temperature and the reaction time, the mixing ratio of alkylbenzene aldehyde resin and phenols and bifunctional aldehydes, the reaction temperature and the reaction time. This can be adjusted.

The phenol / alkylbenzene of the present invention
The epoxy resin curing agent composed of an aldehyde resin may be used alone, or may be used in combination with one or more other epoxy resin curing agents. As other epoxy resin curing agents,
Phenol-formaldehyde resin, cresol-formaldehyde resin, phenol-dicyclopentadiene resin, phenol-alkylbenzene resin and the like are mentioned, but are not particularly limited, and the addition ratio can be appropriately set according to desired characteristics. .

The phenol / alkylbenzene of the present invention
For the aldehyde resin, the measurement of the characteristic values described above was performed according to the following method. 1. Hydroxyl equivalent: A sample was acetylated with pyridine and an excess amount of acetic anhydride, and acetic acid generated from acetic anhydride consumed by the sample was determined by titration with an aqueous sodium hydroxide solution. 2. Softening point: determined by a ring and ball method described in JIS K 7234. 3. Solution viscosity: A solution of sample / ethanol = 5/5 was prepared and determined at 25 ° C. by the method described in JISZ8803. 4. Weight average molecular weight: GPC column (G
1000HXL: 1, G2000HXL: 2, G3
000HXL: 1), using a differential refractometer as a detector under the analysis conditions of a flow rate of 1.0 ml / min, an elution solvent of tetrahydrofuran, and a column temperature of 40 ° C., and a conversion by standard polystyrene. The method for measuring these characteristics is the same for the following examples.

[0020]

The present invention will be described below with reference to examples. The present invention is not limited by these examples,
"Parts" and "%" described in Examples and Comparative Examples
Represents "parts by weight" and "% by weight".

Production Example 1 In a four-necked flask equipped with a thermometer and a stirrer, a mixture of 100 parts of xylene / formaldehyde resin (Nicanol G manufactured by Mitsubishi Gas Chemical Co., Ltd.), 600 parts of phenol and 6 parts of paratoluenesulfonic acid was used. After gradually heating and reacting at 100 ° C. for 2 hours, 255 parts of 40% glyoxal was further added, the temperature was raised to 140 ° C., and the reaction was carried out for 2 hours. After cooling to 80 ° C., 100 parts of methyl isobutyl ketone was added to make a uniform solution, 200 parts of ion-exchanged water was added, and the mixture was stirred for 15 minutes and allowed to stand to separate into an organic layer and an aqueous layer. The aqueous layer containing ionic impurities was removed. 425 parts of a phenol / alkylbenzene / aldehyde resin having a hydroxyl equivalent of 144 g / eq, a softening point of 92 ° C., a solution viscosity of 51 μm ² / s and a weight average molecular weight of 2,500 by removing condensed water, unreacted phenol and the like by a distillation step. I got

Production Examples 2 to 5 The desired phenol / alkylbenzene / aldehyde resin was obtained in the same manner as in Production Example 1 with the composition shown in Table 1.

[0023]

[Table 1]

Production Example 6 188 parts of phenol, 121 parts of 37% formalin and 3
After reacting a mixture of 0.5 parts of 5% hydrochloric acid at 100 ° C. for 2 hours,
Distillation was performed under reduced pressure until the internal temperature reached 170 ° C. to remove water and unreacted phenol, and 190 parts of a phenol resin having a hydroxyl equivalent of 104 g / eq, a softening point of 110 ° C., a solution viscosity of 88 μm ² / s, and a weight average molecular weight of 2910. I got

Examples 1 to 5 and Comparative Examples 1 to 4 Phenols / alkylbenzene / aldehyde resins obtained in Production Examples 1 to 5, phenol resins obtained in Production Example 6, orthocresol novolac type epoxy resin (Nippon Kagaku) EOCN-1020-65 (manufactured by Yakuhin), 2-methylimidazole, fused silica, and stearic acid were roll-kneaded in the composition shown in Table 2 to obtain a molding material. 100k of this molding material
g / cm ² , press molding at 175 ° C for 10 minutes,
Further, post-curing was performed at 180 ° C. for 6 hours to obtain a cured molded product. The glass transition temperature, bending strength,
Table 2 shows the results of measuring the flexural modulus and the water absorption.

[0026]

[Table 2]

(Measurement method) 1. Glass transition temperature: measured using a thermomechanical analyzer (TMA) 2. Flexural strength and flexural modulus: JIS K6911 Water absorption: The size of the test piece is 50 mm in diameter and 3 m in thickness
It was determined from the weight change before and after the treatment at 120 ° C., 100% RH and 80 hours for a circular plate of m.

[0028]

As is apparent from Table 2, the epoxy resin molded product using the epoxy resin curing agent of the present invention has excellent heat resistance and has a flexural modulus and a water absorption without a decrease in flexural strength. Is a very small value, indicating that the material has low stress and excellent moisture resistance. Therefore, the epoxy resin curing agent of the present invention is suitable for applications such as epoxy resin sealing materials for high-performance electronic components, epoxy resin powder coatings, and epoxy resin laminates, and contributes to improving the performance of electronic components. It is expected to do.

Claims (3)

[Claims] An alkylbenzene-aldehyde resin (A) obtained by reacting an alkylbenzene represented by the general formula (1) with an aldehyde represented by the general formula (2) in the presence of an acid catalyst; Phenols (Z) represented by 3)
Is reacted in the presence of an acid catalyst at a weight ratio of 1 ≦ (Z) / (A) ≦ 20, and then a bifunctional aldehyde (Y) represented by the general formula (4) is added to a phenol An epoxy resin curing agent comprising a phenol / alkylbenzene / aldehyde resin reacted at a molar ratio with (Z) of 0.1 ≦ (Y) / (Z) ≦ 0.8. Embedded image 2. The phenol / alkylbenzene / aldehyde resin has a hydroxyl equivalent of 100 to 200 g / eq, a softening point of 60 to 110 ° C. and a solution viscosity of 20 to 90 μm ² / eq.
s, the weight average molecular weight is 400-3000.
The epoxy resin curing agent as described. 3. An alkylbenzene represented by the general formula (1) is m-xylene; an aldehyde represented by the general formula (2) is formaldehyde;
The epoxy resin curing agent according to claim 1 or 2, wherein the bifunctional aldehyde represented by the formula is at least one selected from the group consisting of glyoxal, glutaraldehyde, terephthalaldehyde, and isophthalaldehyde.