JP2781108B2 - Epoxy resin curing agent - Google Patents

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 which exhibits good curability when cured with an epoxy resin, and gives a cured product having excellent heat resistance, low stress and excellent moisture resistance.

[0002]

2. Description of the Related Art Conventionally, for sealing electronic components such as transistors and integrated circuits, inorganic fillers such as ortho-cresol novolak epoxy resin and / or phenol novolak epoxy resin novolak type phenol resin hardener, silica powder and the like have been used. An epoxy resin sealing material composed of additives and the like is used. However, in recent years, chips have become larger in size with higher integration of integrated circuits, the mounting method has changed from insertion mounting 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 package cracking occurs, and further improvement in heat resistance, lower stress, and moisture resistance of the sealing material is required. It has been.

[0003] To improve the heat resistance of the encapsulant, a maleimide resin is being studied in place of the epoxy resin. However, although the heat resistance is improved, the water absorption rate is increased and it is satisfactory as an encapsulant for electronic parts. Has not been obtained. Further, in order to reduce the stress and improve the moisture resistance of the epoxy resin encapsulant, a xylene-modified phenol resin is used as a curing agent (Japanese Patent Application Laid-Open
No. 9-105017), use of a fluorinated novolak (JP-A-64-74215), use of a phenol-dicyclopentadiene resin (JP-A-62-104830).
Gazette) was considered. However, in these cases, even if the stress is reduced, the strength is also reduced, or even if the moisture resistance is improved, the curing with the epoxy resin is slow, and the moldability of the sealing material is deteriorated. It was not sufficiently satisfactory as a hardener for a stop material.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide an epoxy resin curing agent which provides a cured product having excellent heat resistance, low stress and excellent moisture resistance without deteriorating the curability in curing with an epoxy resin. To provide.

[0005]

SUMMARY OF THE INVENTION The present invention is an epoxy resin curing agent containing a phenol / benzaldehyde resin represented by the formula [I] as an essential component.

Embedded image (R: a hydrogen atom or an alkyl group having 1 to 9 carbon atoms, n: an integer of 0 to 10)

[0006] The phenol-benzaldehyde resin used in the present invention is phenol and C1-C1.
9 or more phenols selected from alkylphenols having an alkyl group as a substituent and benzaldehyde in the presence of an acid catalyst at 80 to 200 ° C for 1 to 10
After reacting for an hour, it is obtained by removing condensed water and unreacted phenols formed by distillation and / or washing under normal pressure or reduced pressure. Phenols include phenol, o-cresol, m-cresol, p
-Cresol, butylphenol, octylphenol, nonylphenol and the like can be used, but phenol, o-cresol and m-cresol are preferred from the viewpoint of curability. Oxalic acid, p-toluenesulfonic acid,
Organic acids such as xylene sulfonic acid and phenol sulfonic acid, and inorganic acids such as hydrochloric acid, sulfuric acid and boron trifluoride can be used.

[0007]

The epoxy resin curing agent of the present invention comprising a phenol / benzaldehyde resin as an essential component gives a cured product having excellent heat resistance, low stress and excellent moisture resistance by curing with an epoxy resin. The reason for this is that, in phenol / benzaldehyde resin, the distance between hydroxyl groups involved in the curing reaction with the epoxy resin is short and the crosslink density of the cured product is high, so that the heat resistance is excellent, and the benzene ring by benzaldehyde is interposed between the phenol nucleus. It is presumed that a cured product having low stress and high moisture resistance can be obtained because it has a pendant group.

[0008]

The present invention will be described below with reference to examples, but the present invention is not limited to these examples. “Parts” and “%” described herein indicate “parts by weight” and “% by weight”, respectively. (Production Example 1) 940 parts of phenol, benzaldehyde 3
A mixture of 71 parts and 9 parts of paratoluenesulfonic acid was mixed with 120 parts of
After reacting at 4 ° C. for 4 hours, 1000 parts of methyl isobutyl ketone was added and dissolved. After washing twice with 500 parts of distilled water, methyl isobutyl ketone and unreacted phenol were removed by distillation under reduced pressure to obtain 720 parts of a phenol / benzaldehyde resin having a softening point of 113 ° C.

(Production Example 2) 827 parts of o-cresol / benzaldehyde resin having a softening point of 95 ° C was obtained in the same manner as in Production Example 1 except that 1080 parts of o-cresol was used instead of 940 parts of phenol. (Production Example 3) 188 parts of phenol, 37% formalin 1
After reacting a mixture of 21.6 parts and 0.5 part of 35% hydrochloric acid at 100 ° C. for 2 hours, the mixture was distilled under reduced pressure until the internal temperature reached 170 ° C. to remove water and unreacted phenol.
There were obtained 191 parts of a phenol resin at a temperature of .degree.

<< Examples 1 and 2 and Comparative Examples >> Production Examples 1 and 2
Orthocresol novolak type epoxy resin (Nippon Kayaku EOCN-1020-65) to the phenol / benzaldehyde resin obtained in the above or the phenol resin obtained in Production Example 3,
Roll-kneading 2-methylimidazole, fused silica and stearic acid according to the composition shown in Table 1 was performed, and 100 kg / cm ² , 175
Press molding at 10 ° C for 10 minutes
After curing for a time, a cured molded product was obtained. The glass transition temperature, flexural strength, flexural modulus, and water absorption of the molded product were measured, and the results are shown in Table 1.

[0011]

[Table 1] * 1: Measured using a thermomechanical analyzer. * 2: Value after treatment at 120 ° C., 100% relative humidity and 80 hours.

[0012]

As is clear from Table 1, 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 rate without a decrease in flexural strength. It is greatly reduced, and is suitable as an epoxy resin sealing material for electronic components, an epoxy resin powder coating, and an epoxy resin curing agent for epoxy resin laminates.

Continuation of the front page (56) References JP-A-5-259315 (JP, A) JP-A-5-259316 (JP, A) JP-A-4-258624 (JP, A) JP-A-3-296521 (JP) JP-A-3-296522 (JP, A) JP-A-4-91121 (JP, A) JP-A-3-139519 (JP, A) JP-A-3-88818 (JP, A) 2-209948 (JP, A) JP-A-2-173923 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) C08G 59/62 C08G 8/04-8/24 H01L 23 / 29

Claims (1)

(57) [Claims] 1. An epoxy resin curing agent comprising a phenol / benzaldehyde resin represented by the formula [I] as an essential component. Embedded image (R: a hydrogen atom or an alkyl group having 1 to 9 carbon atoms, n: an integer of 0 to 10)