JPH0344094B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a highly reliable, fast-curing curing agent for epoxy resins and a compounded composition thereof, which is characterized by the use of a resin having nitrogen atoms in its skeleton. In recent years, metal and ceramic parts have been rapidly replaced with plastic to reduce weight and cost. These plastics include phenolic resins, polyester resins, epoxy resins, etc. Initially, phenolic resins were used for general purposes, polyester resins were used for electrical purposes, and epoxy resins were used for high-grade insulation. However, in the past few years, with the shift to plastic for high-quality parts and the demand for higher quality plastics, epoxy resins have come into use in large quantities and have become more important as general-purpose resins. In the field of epoxy resin molding materials, in order to respond to this generalization (mass production and lower costs), rationalization is being carried out by shortening molding cycles and automating molding. For example, in the case of low-pressure sealing molding materials, there has been a shift to faster-curing materials and consideration has been given to fully automated systems by introducing multi-plunger molding machines. Currently, a problem in semiconductor encapsulation applications is that reliability decreases when materials are made to harden quickly. Normally, the measure taken to improve the curability of a material is to increase the amount of curing catalyst, but this curing catalyst is considered a low-molecular impurity in terms of material purity and is a cause of reduced reliability. It is considered. It is also believed that as the material hardens faster, the internal stress of the molded product increases and the adhesion with the insert weakens, reducing reliability. The present invention provides a curing agent for epoxy resins that enables a significant reduction in processing cycles, and an epoxy resin composition containing the curing agent that has particularly excellent reliability. The gist of the present invention is (1) a curing agent for epoxy resin characterized by being composed of a co-condensate of a phenol such as phenol, cresol, xylenol or resorcin, aniline and formaldehyde, and a curing agent compounded with the curing agent. It is an epoxy resin composition. The average structural formula of the curing agent for epoxy resin of the present invention is as follows. R ₁ :H, -CH ₃ , (-CH ₃ ) ₃ , OH, etc. The curing agent for epoxy resin of the present invention has a nitrogen atom fixed in its skeleton, which is recognized to be effective as a curing catalyst for epoxy resin. In addition, by increasing the distance between the phenol nuclei, it was possible to achieve both rapid curing and low stress. This is because the curing agent itself is a curing catalyst that is not harmful as an impurity and has a stress-relaxing structure. Further, in the case of a curing agent, the higher the nitrogen atom/hydroxyl group molar ratio, the better the curability becomes. The nitrogen atomic ratio of the curing agent and the composition properties are summarized in the table below.

[Table] ○: Excellent.
◎: Particularly excellent.
The curing agent for epoxy resins of the present invention can be used alone or in combination with other curing agents as appropriate in an epoxy resin. Furthermore, if necessary, other curing agents, curing accelerators, fillers, pigments, surface treatment agents, mold release agents, etc. can be added. The epoxy resin used in the present invention can be any one having an epoxy group, such as bisphenol type epoxy resin, phenol novolak type epoxy resin, cresol novolak type epoxy resin,
Examples include triazine core-containing epoxy resins. Other curing agents that can be used in combination with the curing agent of the present invention may be anything that reacts with epoxy resins, such as phenol novolaks such as phenol novolak and orthocresol novolak, tetrachlorophthalic anhydride ( TCPA),
Acid anhydrides such as hexahydrophthalic anhydride (HHPA) and tetrahydrophthalic anhydride (THPA),
Examples include amines such as dicyandiamide (DDA) and diaminodiphenylmethane (DDM). If you want to further accelerate curing, use dimethylaminomethylphenol, piperazine, 2,
3,4,6,7,8,9,10-octahydro-
Tertiary amines such as pyramide (1,2-a) azepine; organic phosphine compounds such as octylphosphine, diphenylphosphine, butylphenylphosphine, tricyclohexylphosphine, triphenylphosphine; Enylimidazole (2PZ), 2ethyl4methylimidazole (2E4MZ), 1-benzylimidazole (1BZ),
Curing accelerators such as imidazoles such as 2-methylimidazole (2MZ) may also be used. The compositions of the present invention include other fillers of the above formulation,
Pigments, flame retardants, mold release agents, etc. can be blended, and fillers used include inorganic fillers such as silica, glass, calcium carbonate, mica, clay, alumina, asbestos, aluminum hydroxide, magnesium hydroxide, etc. Examples include organic fillers such as wood flour, pulverized cloth, and pulp, and if necessary, the surface of these fillers may be modified with a surface treatment agent such as a silane coupling agent or a titanium coupling agent. Also, mold release agents such as carnauba wax, stearic acid, stearates, polyethylene wax, etc. can be used. Examples and Comparative Examples To prepare the curing agent of the present invention, formaldehyde (37% formalin) and a catalyst such as oxalic acid are first mixed in a reaction vessel, and then aniline is added dropwise while cooling. Thereafter, phenols are added and heated to about 100°C to carry out a reflux reaction, and then heated to 150 to 300°C for dehydration to obtain a resinized co-condensate. The curing agent for the cocondensate used in the examples obtained by the above method is A: Aniline-modified phenol cocondensate (N/OH
=0.3) B: Aniline-modified phenol cocondensate (N/OH
= 0.6) Their number average molecular weight is approximately 600. Ortho-cresol novolak type epoxy resin Epicron N-670 (manufactured by Dainippon Ink Chemical Co., Ltd., number average molecular weight 1000), curing agents A, B, C, and filler:
70 parts by weight of crystalline silica (Tatsumori Sunrex #200),
Curing accelerator: 2E4MZ (manufactured by Shikoku Kasei), surface treatment agent: Silane coupling agent A-187 (manufactured by Nippon Unicar) 0.5 parts by weight, mold release agent: Hoechstwax OP0.5
Several types of molding materials were manufactured using a heated roll using compositions having the compounding ratios shown in Table 1 by combining parts by weight, pigments, etc. As a comparative example, the other formulations were the same as in the examples, except that phenol novolac PN-100 (manufactured by Nippon Kayaku, number average molecular weight 600) was used as a curing agent. The evaluation results are shown in Table 1, and all of them are superior in curability and reliability compared to the comparative examples.

[Table] The numbers are relative comparison scores when the comparison example is set as 100.
Reliability testing is determined by the corrosion rate of aluminum when a molded product incorporating a simulated aluminum element is left in an atmosphere of 2 atm, 121°C, and 100% humidity.

Claims (1)

[Claims] 1. A curing agent for epoxy resin, characterized by comprising a co-condensate of phenols, aniline, and formaldehyde.