JPH0822904B2 - Epoxy resin curing agent composition - Google Patents

Description

TECHNICAL FIELD The present invention relates to an acid anhydride-based epoxy resin curing agent composition.

[Prior Art] Conventionally, casting resins for electric parts and the like are composed of a resin component composed of an epoxy resin, an inorganic filler, a flame retardant and the like, and a curing agent component composed of a liquid acid anhydride and a curing accelerator. It has been commercialized as a liquid, and among these, amine compounds such as imidazoles and tertiary amines are widely used as the curing accelerator.

However, the viscosity of the acid anhydride-based curing agent composition containing such an amine-based curing accelerator is high, and in addition to increasing with time, carbon dioxide gas is generated and the container expands. It lacks storage stability as a curing agent component, such as bursting.

The present inventors have found that organic phosphine compounds do not have the drawbacks of amine-based curing accelerators and have an excellent curing-accelerating function, and have previously proposed it as a unique epoxy resin curing agent composition. (Japanese Patent Application No. 61-11
No. 1187).

[Problems to be Solved by the Invention] In recent years, it has been strongly desired to reduce the curing shrinkage rate and lower the curing temperature in order to improve the crack resistance, and to shorten the curing time in order to improve the productivity. It is rare.

In order to satisfy such a demand, the compounding amount of the curing accelerator may be increased, but when an amine compound is used, the viscosity of the system is increased and the tendency that carbon dioxide gas is generated becomes stronger. .

On the other hand, when the organic phosphine compound is applied as the curing accelerator, the viscosity of the curing agent composition is low, the storage stability is good, and the prepared epoxy resin composition also has a low viscosity, so that it is used as a casting resin. Although useful, when the obtained resin cured product is left for a long period of time, its moisture resistance tends to decrease.

The presence of water in the cured product lowers the electrical properties such as the dielectric constant, dielectric loss tangent, and insulation of the cured product, and further reduces the durability of the product, causing defective products. Therefore, the moisture resistance of the cured resin is an important characteristic in the field of various electric parts such as flyback transformers, capacitors, coils, and generating diodes.

The present inventors have conducted extensive studies to improve the long-term moisture resistance of the obtained cured product while maintaining the above excellent properties of the organic phosphine compound, and as a curing accelerator, an organic phosphine compound and an amine-based compound were obtained. By using in combination, it was found that long-term moisture resistance is synergistically improved, and a curing agent composition that can sufficiently satisfy the initial purpose can be obtained.
The present invention has been completed based on this finding.

That is, an object of the present invention is to provide an acid anhydride-based epoxy resin curing agent composition capable of preparing a cured product having improved long-term moisture resistance, and having low viscosity and excellent storage stability. .

[Means for Solving Problems] The acid anhydride-based epoxy resin curing agent composition according to the present invention is characterized by containing an organic phosphine compound and an amine compound as a curing accelerator.

The organic phosphine compound is represented by the general formula (1) [In the formula, R ¹ , R ² and R ³ represent a group represented by a hydrogen atom, an aryl group such as an alkyl group, a phenyl group and a tolyl group, a cycloalkyl group such as a cyclohexyl group, and the same or different. Good.

Also, the following equation (2) (In the formula, R represents an alkylene group, and R ′ and R ″ are
It represents a hydrogen atom, an alkyl group, an aryl group such as a phenyl group and a tolyl group, and a cycloalkyl group such as a cyclohexyl group, which may be the same or different. However, R'and R "
May be an organic group containing an organic phosphine. However, the case where R ¹ , R ² and R ³ are all hydrogen atoms is excluded. ] Is shown.

Specifically, a third phosphine compound such as triphenylphosphine, tributylphosphine, tricyclohexylphosphine and methyldiphenylphosphine, a second phosphine compound such as butylphenylphosphine and diphenylphosphine, a first phosphine compound such as phenylphosphine and octylphosphine. , And bis (diphenylphosphino) methane, 1,2-bis (diphenylphosphino) ethane and other third bisphosphine compounds are exemplified,
One or more selected from the group consisting of these are used. Among these, it is preferable to use an arylphosphine compound, and particularly preferable is a triarylphosphine such as triphenylphosphine.

When an organic phosphine compound is applied as a curing accelerator, the viscosity of the obtained epoxy resin composition is lower than when an amine compound is applied, and, for example, the impregnability into electric parts is improved.

The amount of such organic phosphine compound is preferably 0.2 to 5 parts by weight, and particularly preferably 0.5 to 3 parts by weight, based on 100 parts by weight of the epoxy resin. If it is less than this range, it is difficult to obtain a predetermined effect. On the other hand, when the content exceeds the above range, the moisture resistance of the obtained cured product cannot be neglected.

As the amine-based compound, those conventionally used as curing accelerators for epoxy resins are sufficient, for example, imidazoles and tertiary amines are recommended.

Specifically, 2-ethyl-4- as imidazoles
Methylimidazole (hereinafter referred to as "2E4MZ"), 2
-Methylimidazole, 1-benzyl-2-methylimidazole, 2-undecylimidazole, 2-phenylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole and the like are exemplified.

Further, as the tertiary amine, lauryldimethylamine, dicyclohexylamine, dimethylbenzylamine, dimeethylaminomethylphenol, 2,4,6-tris (N, N-dimethylaminomethyl) phenol (hereinafter referred to as "D
MP-30 ". ), 1,8-diazabicyclo (5,4,0)
Undecene-7 and the like are exemplified.

Modified products of these amine compounds by Lewis acid salts, organic acid salts, and adducts are also suitable compounds.

The compounding amount of such amine compound is 100% by weight of the epoxy resin.
It is preferably 0.2 to 5 parts by weight with respect to parts by weight,
It is particularly preferably 0.5 to 3 parts by weight. If it is less than this range, it is difficult to obtain a predetermined effect. On the other hand, for example, when compounded in an amount exceeding the above range in order to cure at low temperature for a short time, the generation of carbon dioxide gas cannot be ignored even when the organic phosphine compound is used in combination, and the long-term storage stability of the curing agent component is stable. Sex tends to decrease.

The curing agent component is mainly composed of a curing accelerator in an amount corresponding to the above predetermined amount, and a liquid carboxylic acid anhydride as an epoxy resin curing agent.

The liquid carboxylic acid anhydride is preferably liquid at 25 ° C.

Specifically, 3-methyltetrahydrophthalic anhydride,
Methyltetrahydrophthalic anhydride such as 4-methyltetrahydrophthalic anhydride (hereinafter referred to as "Me-THPA"),
Methylhexahydrophthalic anhydride such as 3-methylhexahydrophthalic anhydride and 4-methylhexahydrophthalic anhydride (hereinafter referred to as "Me-HHPA"), methyl nadic acid anhydride, dodecenyl succinic anhydride and those Including structural isomers or geometric isomers, hexahydrophthalic anhydride, tetrahydrophthalic anhydride, phthalic anhydride,
Examples thereof include trimellitic anhydride and benzophenonetetracarboxylic acid anhydride, which are liquefied by being mixed and modified with a solid acid anhydride at room temperature.

These carboxylic acid anhydrides may be used alone or in combination of two or more kinds.

The compounding amount is 0.5 per epoxy equivalent of the epoxy resin.
It is preferably about 1.5 equivalents.

The epoxy resin curing agent according to the present invention is applied to, for example, a flame-retardant epoxy resin containing an epoxy resin, an inorganic filler and a flame retardant as resin components.

The epoxy resin is not particularly limited, and specifically, glycidyl ether type epoxy resin such as bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, glycidyl ester type epoxy resin. Examples thereof include resins, glycidyl amine type epoxy resins, cycloaliphatic epoxy resins, heterocyclic epoxy resins, halogenated epoxy resins, etc. These may be used alone or in combination of two or more.

For example, in order to improve the impregnation property into electric parts and the like, an epoxy resin which is liquid at room temperature is preferable, and its epoxy equivalent is recommended to be about 300 at maximum. If the epoxy equivalent is more than this range, the viscosity becomes high and the desired effect tends to decrease. still,
A liquefied epoxy resin can also be used by using together with a diluent and the like within the allowable range of physical properties.

As the inorganic filler, hydrated alumina, silicon dioxide,
Kaolin clay, talc, glass fiber, calcium silicate, calcium carbonate, barium sulfate, magnesium oxide, titanium oxide, boron nitride and the like are exemplified.

The compounding amount of the inorganic filler is 8 per 100 parts by weight of the epoxy resin.
5 to 300 parts by weight, preferably 150 to 250 parts by weight. If it is less than this range, it is difficult to obtain a desired effect, and if it is too large, the viscosity of the composition increases, which is not preferable in product design.

Two or more kinds of inorganic fillers may be used in combination, and a preferable system is a mixed system of hydrated alumina, calcium carbonate and silicon dioxide. In this case, epoxy resin 100
With respect to parts by weight, 85 to 190 parts by weight of hydrated alumina, 75 to 150 parts by weight of calcium carbonate and / or 0 of silicon dioxide.
The composition of the inorganic filler is preferably 90 to 90 parts by weight and the total amount of the inorganic filler does not exceed 300 parts by weight.

Furthermore, if necessary, a flame retardant such as a halogen compound such as antimony trioxide, hexabromobenzene, decabromodiphenyl oxide, tetrabromobisphenol A, brominated cresol monoglycidyl ether, or a phosphorus compound such as red phosphorus is added. can do. In addition, release agents such as natural or synthetic waxes, metal soaps, fatty acid amides, esters and paraffins, colorants such as carbon black, silane coupling agents, diluents,
An anti-settling agent, a defoaming agent, a plasticizer, an antioxidant and the like can be appropriately used in combination.

The curing agent composition according to the present invention is generally prepared by stirring and mixing a predetermined amount of raw material components, that is, a carboxylic acid anhydride and a curing accelerator at room temperature or under heating.

Further, the resin component is prepared by mixing a predetermined amount of an epoxy resin and, if necessary, an inorganic filler at room temperature or under heating with a mixer such as a Henschel mixer, a Banbury mixer, an extruder, a heat roll, and a kneader. To do.

The mixing order of the raw material components does not matter for the curing agent composition and the resin composition. Further, if necessary, the system may be depressurized at normal temperature or under heating to reduce the pressure.

The epoxy resin composition obtained by appropriately blending the above two components is useful for casting of various electronic parts such as coils and capacitors, as well as casting of flyback transformers.

[Examples] The present invention is described in detail below with reference to Examples and Comparative Examples.

Example (1) A predetermined amount of triphenylphosphine and an amine compound were mixed with 82 parts by weight of Me-THPA, and the mixture was heated at 70 ° C.
The mixture was mixed for 30 minutes with stirring to obtain a curing agent composition. The viscosity of the curing agent composition was measured under a condition of 25 ° C. using a B-type viscometer. Further, a curing agent composition having the same composition as above was stored at 40 ° C. for 1 month, and the amount of carbon dioxide gas generated at that time was measured according to JIS K-2301. The results obtained are shown in Table 1.

(2) Bisphenol A type epoxy resin (epoxy equivalent
190), hydrated alumina as an inorganic filler (average particle size 3.5
μ) and calcium carbonate (average particle diameter 3.0 μ) by stirring and mixing a predetermined amount, and the curing agent component obtained above was mixed to obtain a resin composition.

The results of measuring the gelation time and the viscosity of the resin composition are shown in Table 2. Here, gelation time is JIS C-210
Measured at 75 ° C according to 5 and the viscosity is 25 ° C using a B-type viscometer.
It was measured at.

Furthermore, a completely cured product of the resin composition is treated at 121 ° C and 2.2 atm.
Left under the steam pressure of [pressure cooker test (hereinafter referred to as "PCT")], the water absorption rate of the cured product after 24 hours and 87 hours (measured from the weight increase of the test object) and the dielectric loss tangent (tan δ:%). (25 ℃, 10KHz; JIS K-691
The moisture resistance was evaluated according to 1). The results obtained are listed in Table 2.

Comparative Example The amount of carbon dioxide gas generated in a curing agent composition obtained by using an amine compound or triphenylphosphine alone as a curing accelerator and the moisture resistance of a completely cured product obtained by the curing agent component are the same as in the examples. Evaluated. The obtained results are listed in Tables 1 and 2, respectively.

Reference Example The moisture resistance of the cured product of the epoxy resin composition under conditions of low temperature and short time was evaluated. 75 ° C as a measure of curability
The curing agent composition required to make the gelling time 70 minutes when cured with is selected variously, and the moisture resistance of the completely cured product of the epoxy resin obtained by using it and the triphenylphosphine and 2E4MZ at that time The correlation with the fraction is shown in FIG.

Here, the compounding amounts of triphenylphosphine and 2E4MZ were changed, and other components were the same as in Example 2. The long-term moisture resistance of the cured resin product was evaluated using tan δ at PCT 87 hours.

[Effects of the Invention] An epoxy resin curing agent composition obtained by using an organic phosphine compound in combination with an amine compound as a curing accelerator has good storage stability while maintaining excellent curing promotion function, and has low temperature. It can be cured in a short time.

Furthermore, since the resin composition to which such a curing accelerator is applied has a low viscosity and thus maintains a high impregnating property, the resin cured product obtained is also excellent in long-term moisture resistance, and therefore particularly requires insulating properties. It is useful as a cast resin composition in the field.

[Brief description of drawings]

FIG. 1 shows the correlation between the composition of the curing accelerator and the moisture resistance of the cured product.

 ─────────────────────────────────────────────────── --- Continuation of the front page (56) References JP-A-6-6622 (JP, A) JP-A-62-58436 (JP, A) JP-A-61-221217 (JP, A) JP-A-61- 47724 (JP, A) JP-A-58-67051 (JP, A)

Claims (3)

[Claims] 1. An acid anhydride epoxy resin curing agent composition comprising an organic phosphine compound and an amine compound in combination as a curing accelerator. 2. The organic phosphine compound is an arylphosphine compound.
An acid anhydride-based epoxy resin curing agent composition according to the item. 3. The amine compound is an imidazole compound and / or
Alternatively, the acid anhydride-based epoxy resin curing agent composition according to claim 1, which is a tertiary amine.