JP2003261650A - Epoxy resin composition, its pre-cured product and cured product - Google Patents

Abstract

(57) [Problem] To provide an epoxy resin composition which gives a low dielectric loss tangent of 3 × 10 ⁻³ or less and a high curing speed even at a high frequency of 1 GHz and has excellent storage stability, and a precured product and a cured product thereof. provide. A curable epoxy resin composition comprising an epoxy resin, an active ester compound and a curing accelerator as essential components, wherein the curing accelerator comprises an imidazole compound and a tertiary amine compound, wherein the imidazole compound and the tertiary amine compound are combined. (A) Epoxy resin 1
The epoxy resin composition is 0.2 to 1.5 parts by mass with respect to 00 parts by mass, and the content of the tertiary amine compound is 0.1 to 0.3 parts by mass. Pre-cured and cured products.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an epoxy resin composition having excellent storage stability while maintaining a low dielectric loss tangent and a fast curing rate, a pre-cured product and a cured product thereof. INDUSTRIAL APPLICABILITY The epoxy resin composition of the present invention, its pre-cured product and cured product are useful as an electronic / electrical material, a coating material, or a construction material, and particularly preferably used as an electronic / electrical material or a composite material.

[0002]

2. Description of the Related Art In the recent information society, in order to transmit and process a huge amount of information, 100 MHz band or GHz band
The high frequency band has been used, and the low dielectric property of the insulator has become important. Particularly in the field of information and communication, it is important to reduce the dielectric loss, and various insulator materials exhibiting excellent low dielectric properties are being developed.

Generally, an epoxy resin composition is widely used as an electric / electronic insulating material, but for the reasons described above, it is required to develop a low dielectric epoxy resin composition for high frequency.

When an epoxy resin is cured with a general curing agent such as an amine compound or a novolac resin, a hydroxyl group is generated due to ring opening of the epoxy group, and this hydroxyl group increases the dielectric property and water absorption of the epoxy resin. It is known. Therefore, in JP-B-4-8444 and Organic Synthetic Chemistry Journal, Vol. 49, No. 3, pp. 218-233, an epoxy resin composition which does not form a hydroxyl group is obtained by using an active ester compound as a curing agent. Proposed.

However, an epoxy resin composition using such an active ester compound as a curing agent has a problem that the curing rate is slow. Therefore, in order to improve the curing rate of an epoxy resin composition using such an active ester compound as a curing agent, it is indispensable to use a curing accelerator in combination, for example, Japanese Patent Publication No. 4-8444. Various curing accelerators to be used in combination are described in Journal of Synthetic Chemistry, "Vol. 49, No. 3, pages 218 to 233", abstracts of discussions on thermosetting resin lectures, "42, 85, 1992". Has been done.

However, if the amount of any curing accelerator added is increased in order to improve the curability of the epoxy resin composition, there is a problem that the storage stability of the pre-cured product is significantly reduced.

Further, in JP-A No. 11-349666, the curability of an epoxy resin composition using an active ester compound as a curing agent is proposed by using an active ester compound and an acid anhydride together as a curing agent for an epoxy resin. Although the curing rate is improved by using an acid anhydride together, as described above, the hydroxyl groups produced adversely affect the dielectric properties and hygroscopicity of the epoxy resin.

[0008]

The problem to be solved by the present invention is to provide an epoxy resin composition which gives a low dielectric loss tangent of 3 × 10 ⁻³ or less and a high curing rate even at a high frequency of 1 GHz and which is excellent in storage stability. Object, its pre-cured product, and its cured product.

[0009]

Means for Solving the Problems In order to solve the above-mentioned problems, the present inventors have earnestly studied the curability of an epoxy resin composition containing an active ester compound and various curing accelerators, and as a result, By containing two specific types of curing accelerators in specific proportions in an epoxy resin composition using an ester compound as a curing agent, the curing rate is fast and the storage stability is good while maintaining a low dielectric loss tangent. The inventors have found that an epoxy resin composition and its pre-cured product can be obtained, and completed the present invention.

That is, the present invention relates to (A) epoxy resin,
An epoxy resin composition comprising (B) an active ester compound and (C) a curing accelerator as essential components, wherein the (C) curing accelerator comprises an imidazole compound and a tertiary amine compound, and the imidazole compound and the above-mentioned 3 The sum of the content of the tertiary amine compound is 0.2 to 1.5 parts by mass with respect to 100 parts by mass of the (A) epoxy resin, and the content of the tertiary amine compound is 0.1 to 0.3 part by mass. The present invention provides an epoxy resin composition, a pre-cured product thereof, and a cured product thereof.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is described in detail below. If the epoxy resin (A) used in the present invention is an epoxy resin having two or more epoxy groups in one molecule,
It is not particularly limited, for example, bisphenol A
Type epoxy resin, bisphenol F type epoxy resin,
2,2 ', 6,6'-tetrabromobisphenol A type epoxy resin, 2,2', 6,6'-tetramethylbisphenol A type epoxy resin, bisphenol S type epoxy resin and other bisphenol type epoxy resins,

Naphthalene type epoxy resins such as 1,6-diglycidyloxynaphthalene type epoxy resin, 1,5-diglycidyloxynaphthalene type epoxy resin and 2,6-diglycidyloxynaphthalene type epoxy resin, phenol novolac type epoxy resin Resin, brominated phenol novolac type epoxy resin, orthocresol novolac type epoxy resin, bisphenol A novolac type epoxy resin, α-naphthol novolac type epoxy resin, β-naphthol novolac type epoxy resin and other novolac type epoxy resins,

A cycloaliphatic epoxy resin represented by an epoxy resin obtained by copolymerizing the bisphenol type epoxy resin and a novolac type epoxy resin through bisphenol, and an epoxidized product of a polyaddition product of dicyclopentadiene and phenol. Other examples include biphenol type epoxy resins, resorcinoid diglycidyl ethers, glycidyl ester type epoxy resins, glycidyl amine type epoxy resins, and heterocyclic epoxy resins. The above epoxy resins may be used alone or in combination of two or more kinds or modified epoxy resins.

The epoxy resin composition of the present invention also comprises
Further, an epoxy reactive diluent may be used in combination. In this case, an epoxy resin having less than 2 epoxy groups in one molecule such as butyl glycidyl ether and phenyl glycidyl ether can be used together.

The active ester compound (B) used in the present invention may be a compound having two or more active ester groups in one molecule, and may be a carboxylic acid ester or a thiocarboxylic acid ester of polyhydric phenol or polyhydric thiol. Examples thereof include phenyl esters of polyvalent carboxylic acids and polyvalent thiocarboxylic acids, thiophenyl esters and naphthyl esters.

More specifically, for example, adipic acid, sebacic acid, succinic acid, maleic acid, itaconic acid, 1,
2,3,4-butanetetracarboxylic acid, phthalic acid, isophthalic acid, terephthalic acid, benzenetricarboxylic acid, benzenetetracarboxylic acid, and their corresponding thiocarboxylic acid phenyl esters, chlorophenyl esters,
Dichlorophenyl ester, nitrophenyl ester,
Dinitrophenyl ester, methylphenyl ester,
Methoxyphenyl ester, bromophenyl ester,
Examples thereof include esters of aromatic or heterocyclic hydroxyl compounds such as fluorophenyl ester, thiophenyl ester, thiobenzothiazole ester, thiobenzoxazole ester, thiobenzimidazole ester, benzotriazole ester, and naphthyl ester.

Further, hydroquinone, resorcin, bisphenol A, bisphenol F, bisphenol S, 2,2 ', 6,6'-tetrabromobisphenol A, 2,2', 6,6'-tetramethylbisphenol A, 4 , 4'-Dihydroxybenzophenone, trihydroxybenzophenone, tetrahydroxybenzophenone, phloroglucin, 1,2,4-benzenetriol and other acetic acid esters, propionic acid esters, fluoroacetic acid esters, benzoic acid esters, nitrobenzoic acid esters, chlorobenzoic acid Examples thereof include esters and thiobenzoic acid esters.

As polyhydric phenols and polyhydric naphthols, phenol, o-cresol, m-cresol, p-cresol, bisphenol A, catechol,
Phenols such as hydroquinone, or naphthols such as α-naphthol, β-naphthol, 1,5-dihydroxynaphthalene, 1,6-dihydroxynaphthalene and 2,6-dihydroxynaphthalene, and formaldehyde, acetaldehyde, propionaldehyde, benzaldehyde, Phenol resins or naphthol resins obtained by reacting with aldehydes such as salicylaldehyde and polyvinylphenol may be used.

Known curing accelerators for epoxy resins when an active ester compound is used as a curing agent include tertiary amine compounds, quaternary ammonium salts, imidazole compounds, organic acid metal salts, Lewis acids and quaternary phosphonium salts. However, in order to achieve both fast curability and storage stability of the epoxy resin composition of the present invention and its pre-cured product, the (C) curing accelerator used is an imidazole compound and a tertiary amine compound. Must be used together.

The content of the (C) curing accelerator in the epoxy resin composition of the present invention is such that the combined amount of the imidazole compound and the tertiary amine compound is 0.1% with respect to 100 parts by weight of the (A) epoxy resin. It is preferably from 2 to 1.5 parts by mass. If the compounding amount of the (C) curing accelerator is less than 0.2 parts by mass, the effect as a curing accelerator will be poor, and addition of more than 1.5 parts by mass will not improve the curing promoting action. .

Further, the compounding amount of the tertiary amine compound in the (C) curing accelerator is preferably 0.1 to 0.3 parts by mass, and 0.1 to 100 parts by mass of the (A) epoxy resin. ~
0.2 parts by mass is more preferable. If the compounding amount of the tertiary amine compound is less than 0.1 part by mass, the curing acceleration effect is poor,
On the other hand, if it exceeds 0.3 parts by mass, the storage stability of the epoxy resin composition and its pre-cured product will be significantly reduced.

Examples of the imidazole compound used as a curing accelerator include 2-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole and 2-imidazole.
Ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 1-
Benzyl-2-methylimidazole, 1-benzyl-2
-Phenylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-ethyl-4-
Methyl imidazole,

1-Cyanoethyl-2-undecylimidazole, 1-cyanoethyl-2-phenylimidazole, 2-phenyl-4,5-dihydroxymethylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole and the like can be mentioned. To be Among them, 2-methylimidazole and 2-ethyl-4-methylimidazole are particularly preferable in order to achieve both fast curability and storage stability of the epoxy resin composition and its pre-cured product.

As the tertiary amine compound used in the present invention, tributylamine, tri-n-octylamine, N-methyl-di-n-octylamine and tri- (2
-Ethylhexyl) amine, N, N-dibutyl-2-ethylhexylamine, triallylamine, N, N-dimethyl-2-ethylhexylamine, N, N-diisopropyl-2-ethylhexylamine, N, N-diisopropylethylamine, N- Isobutyl ethanolamine,
3-dimethylamino-1-propanol, tetramethylethylenediamine, tetramethyl-1,3-diaminopropane, N, N, N ', N'-tetramethylhexamethylenediamine,

N-methylmorpholine, pentamethyldiethylenetriamine, N-ethylpiperidine, N-methyl-3-piperidinemethanol, N-methyl-3-piperidinol, N-benzyl-3-piperidinol, N-methyl-4-pipedinol, N-benzyl-4-piperidinol, N-methyl-4-piperidone, N-benzyl-
4-piperidone, 1,3, -dimethyl-4-piperidone, N- (benzyloxycarbonyl) -4-piperidone, dipiperazinomethane, N-isobutyl-4-piperidone, dimethylbenzylamine, N-benzyl-N -Methylaminoethanol, N, N-dibenzylethanolamine,

Tribenzylamine, N, N-dimethylcyclohexylamine, N-butylpyrrolidine, N-octylpyrrolidine, N-benzyl-3-pyrrolidone, N-
Benzyl-3-pyrrolidinol, 1,4, -dimethylpiperazine, 4-dimethylaminopyridine, 4-pyrrolidinopyridine, 4-piperidinopyridine, 4- (2-piperidinoethyl) pyridine, 4- (2- (4- Methylpiperidino) ethyl) pyridine and the like can be mentioned. Among them, 4-dimethylaminopyridine is particularly preferable in order to achieve both fast curability and storage stability of the epoxy resin composition and its pre-cured product.

The epoxy resin composition of the present invention may appropriately contain silica such as a conventional filler, a pigment, a glass fiber and an aramid fiber, if necessary.

The epoxy resin composition and the pre-cured product of the present invention can be prepared by a conventional method. For example,
Examples include a method of sufficiently uniform mixing with a mixer or the like, and then melt-kneading with a hot roll, a kneader or the like, and pressure molding, injection molding or cast molding.

The epoxy resin composition and the pre-cured product of the present invention are prepared by dissolving and mixing them in an organic solvent once,
After that, the solvent may be removed for preparation. The organic solvent that can be used is not particularly limited, but ketones such as methyl ethyl ketone and cyclohexanone, aromatic hydrocarbons such as toluene and xylene, esters such as ethyl acetate, tetrahydrofuran, ethylene glycol monomethyl ether, Ethers such as anisole, N,
Examples thereof include amides such as N-dimethylformamide. These organic solvents can also be used as a mixed solvent of two or more kinds.

The cured product of the epoxy resin composition of the present invention is
It is obtained by further heat-curing the pre-cured product of the present invention. The heating and curing conditions for obtaining a cured product differ depending on the type of epoxy resin or active ester compound used, the molding and curing method, etc. and cannot be specified unconditionally, but the molded precured product is usually heated at a temperature of 150 to 300 ° C. And 1-2
Heat for 4 hours to cure. Further, in order to facilitate solvent removal, the pre-cured product may be heat-cured while the atmosphere is depressurized, or the pre-cured product may be press-heated and molded with a mold. If necessary, the cured product after pressure heat molding may be further heated to complete the curing.

[0031]

EXAMPLES The present invention will be specifically described below with reference to Examples and Comparative Examples. However, these are merely representative examples of the present invention, and the scope of the present invention is not limited thereto. In addition, unless otherwise specified, parts and percentages representing proportions are based on mass.

The measuring methods were as follows. (Method for measuring gelation time of epoxy resin composition) The time until gelation measured by the cure stroke method on a hot plate having a surface temperature of 170 ° C was taken as the gelation time. That is, the epoxy resin composition was placed on a hot plate heated to 170 ° C. and measurement was started at the same time, while stirring the whole with a pencil-shaped pointed Teflon (registered trademark) rod having a diameter of 1 cm, The time to cure was measured.

(Measurement Method of Gelation Time of Epoxy Resin Composition and Precured Product) Similar to the measurement method of the gelation time of the epoxy resin composition, a cure stroke method was performed on a hot plate heated to a surface temperature of 170 ° C. The time until gelation measured by the above was taken as the gelation time. That is, the preliminary cured product of the epoxy resin composition is placed on a hot plate heated to 170 ° C., and at the same time, the measurement is started, and the preliminary preparation of the epoxy resin composition which is melted by a Teflon rod having a diameter of 1 cm and sharpened like a pencil. The time required for curing was measured while stirring the cured product evenly.

(Measurement method of glass transition point) Using a dynamic viscoelasticity measuring instrument "DMS200" (manufactured by Seiko Denshi Kogyo Co., Ltd., bending mode, 1 kHz), the temperature was raised at 3 ° C / min to obtain tan δ. The peak temperature of the curve was taken as the glass transition point (Tg) of the cured epoxy resin composition.

(Method of measuring dielectric loss tangent) "impedance /
Using a device (both manufactured by Agilent Technology Co., Ltd.) in which “Test Fixture 16453A” is connected to “Material Analyzer HP4291B”, 25 ° C.
The dielectric loss tangent of the cured epoxy resin composition at 1 GHz was measured.

(Production Example 1) (Production of active ester compound) 33.2 parts by mass of isophthalic acid (manufactured by AJ International Chemical Co., Ltd.) in a flask equipped with a stir bar, cooling tube and nitrogen introducing tube, α -Add 57.7 parts by mass of naphthol (manufactured by Sugai Chemical Co., Ltd.) and 49.0 parts by mass of acetic anhydride (manufactured by Wako Pure Chemical Industries, Ltd.), and add 3
Nitrogen was circulated for 0 minutes to replace the inside of the system with nitrogen. Then, the temperature was raised with stirring while flowing nitrogen, and the temperature was maintained at 145 ° C. for 3 hours to acetylate the hydroxyl group of α-naphthol.

When the temperature is further increased to 230 ° C., 1
The temperature was maintained, and then the temperature was raised to 250 ° C. over 3 hours to remove acetic acid and the esterification reaction was carried out. The obtained product was washed with boiling methanol three times and then vacuum dried at 60 ° C. for 17 hours to obtain the target active ester compound. The ester equivalent of this active ester compound is 20.
It was 9 g / eq.

Example 1 A dicyclopentadiene type epoxy resin EPICLON HP-7 as an epoxy resin
200H (manufactured by Dainippon Ink and Chemicals, Inc., epoxy equivalent 278 g / eq) 100 parts by mass, 75 parts by mass of the active ester compound (ester equivalent 209 g / eq) synthesized according to Preparation Example 1 as a curing agent, and 2 as a curing accelerator. 0.5 parts by mass of -ethyl-4-methylimidazole (manufactured by Shikoku Chemicals Co., Ltd.) and 0.2 parts by mass of 4-dimethylaminopyridine (manufactured by Koei Chemical Industry Co., Ltd.) were dissolved in 580 parts by mass of tetrahydrofuran to prepare an epoxy resin. A composition was prepared.

To evaluate the curability of this epoxy resin composition, the gelling time at 170 ° C. was measured. Then 50
After removing the solvent at 0 ° C, further solvent removal and precuring were performed on a hot plate at 170 ° C to obtain a precured product having a gelling time of about 2 minutes. In order to evaluate the storage stability of this pre-cured product, the gelation time after storage at 30 ° C. for 1 month was measured again, and the gelation time of the pre-cured product after storage was defined as the initial value of the gelation time. The retention rate obtained by dividing was calculated.

The pre-cured product was put into a mold, heated and pressure-molded under vacuum at 170 ° C. and 3 MPa for 1 hour, and further heated under vacuum at 210 ° C. and 0 MPa for 10 hours to 1 mm.
A thick resin plate was prepared. Heat resistance of the obtained resin plate (T
g) and electrical characteristics (dielectric loss tangent) were measured.

Example 2 Example 1 except that 0.5 parts by mass of 2-ethylimidazole (manufactured by Shikoku Chemicals Co., Ltd.) and 0.2 parts by mass of 4-dimethylaminopyridine were used as curing accelerators. An epoxy resin composition and a pre-cured product were prepared in the same manner as in.

Example 3 As Example 1, except that 1.0 part by mass of 2-ethyl-4-methylimidazole and 0.2 part by mass of 4-dimethylaminopyridine were used as curing accelerators. An epoxy resin composition and a pre-cured product were prepared.

Comparative Example 1 An epoxy resin composition and a pre-cured product were prepared in the same manner as in Example 1 except that only 1.0 part by mass of 2-ethyl-4-methylimidazole was used as a curing accelerator. .

Comparative Example 2 An epoxy resin composition and a pre-cured product were prepared in the same manner as in Example 1 except that 3.0 parts by mass of 2-ethyl-4-methylimidazole was used as a curing accelerator. .

Comparative Example 3 An epoxy resin composition and a pre-cured product were prepared in the same manner as in Example 1 except that 0.2 part by mass of 4-dimethylaminopyridine was used as the curing accelerator.

Comparative Example 4 An epoxy resin composition and a pre-cured product were prepared in the same manner as in Example 1 except that 0.5 part by mass of 4-dimethylaminopyridine was used as the curing accelerator.

Comparative Example 5 0.5 parts by mass of 1-benzyl-2-phenylimidazole (manufactured by Shikoku Chemicals Co., Ltd.) and 0.2 parts by mass of 4-dimethylaminopyridine were used as curing accelerators. In the same manner as in Example 1, an epoxy resin composition and a pre-cured product were prepared.

(Comparative Example 6) As a curing accelerator, 0.5 parts by mass of 2-ethyl-4-methylimidazole and N, N-
Dimethylbenzylamine (made by Koei Chemical Industry Co., Ltd.)
An epoxy resin composition and a pre-cured product were prepared in the same manner as in Example 1 except that 0.2 part by mass was used.

Comparative Example 7 An epoxy resin composition and a pre-cured product were prepared in the same manner as in Example 1 except that 1.5 parts by mass of tributylbenzyl ammonium chloride (manufactured by Koei Chemical Industry Co., Ltd.) was used as a curing accelerator. Was prepared.

Comparative Example 8 An epoxy resin was prepared in the same manner as in Example 1 except that 1.0 part by mass of 2-ethyl-4-methylimidazole and 0.2 part by mass of tributylbenzylammonium chloride were used as curing accelerators. A composition and a pre-cured product were prepared.

Comparative Example 9 Tetra n-butylphosphonium bromide (manufactured by Nippon Chemical Industry Co., Ltd.) as a curing accelerator
An epoxy resin composition and a pre-cured product were prepared in the same manner as in Example 1 except that 1.5 parts by mass was used.

Comparative Example 10 38 parts by mass of the active ester compound synthesized in Production Example 1 as a curing agent and EPIC
Example 1 except that 30 parts by mass of LON B-570 (manufactured by Dainippon Ink and Chemicals, Inc., methyltetrahydrophthalic anhydride, acid anhydride equivalent 166 g / eq) was used in combination.
An epoxy resin composition and a pre-cured product were prepared in the same manner as in.

Table 1 summarizes the gelling times of the epoxy resin compositions of the above Examples and Comparative Examples, the gelling time and the retention rate during the preparation and storage of the pre-cured product, Tg and the dielectric loss tangent. The results are shown in Table 2.

The epoxy resin compositions of the examples were cured within 10 minutes and showed excellent curability, and the pre-cured product had a retention rate after storage of 95% or more and was excellent in storage stability of the pre-cured product, and Dielectric loss tangent is 3 × even at high frequency of 1 GHz
It was 10 ⁻³ or less.

On the other hand, most of the comparative examples did not cure even after 15 minutes. Further, the epoxy resin composition of Comparative Example cured within 10 minutes has a retention rate of less than 95% after storage of the pre-cured product, or has a dielectric loss tangent of 3 ×.
It was higher than 10 ^-3 .

[0056]

[Table 1]

[0057]

[Table 2]

[0058]

The present invention provides a low dielectric loss tangent of 3 × 10 ⁻³ or less and a high curing rate even at a high frequency of 1 GHz,
Also provided are an epoxy resin composition having excellent storage stability, a pre-cured product thereof, and a cured product thereof. INDUSTRIAL APPLICABILITY The epoxy resin composition of the present invention, its pre-cured product and cured product are useful as an electronic / electrical material, a coating material, or a construction material, and particularly preferably used as an electronic / electrical material or a composite material.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Fumihiko Maekawa             2-3-6-A22 Ojidai, Sakura City, Chiba Prefecture F-term (reference) 4F072 AA07 AD23 AE01 AE02 AF26                       AF27 AF28 AG04 AL11 AL17                 4J036 AA01 DA06 DB23 DC05 DC40                       DC48 DD03 FB01 FB07 JA01                       JA11

Claims (5)

[Claims] 1. An epoxy resin composition comprising (A) an epoxy resin, (B) an active ester compound and (C) a curing accelerator as essential components, wherein the (C) curing accelerator is an imidazole compound and a tertiary compound. It is composed of an amine compound, and the sum of the contents of the imidazole compound and the tertiary amine compound is 0.2 to 1.
The epoxy resin composition is 5 parts by mass, and the content of the tertiary amine compound is 0.1 to 0.3 parts by mass. 2. The epoxy resin composition according to claim 1, wherein the imidazole compound is 2-ethylimidazole or 2-ethyl-4-methylimidazole. 3. The epoxy resin composition according to claim 1, wherein the tertiary amine compound is 4-dimethylaminopyridine. 4. A pre-cured product of the epoxy resin composition according to claim 1. 5. A cured product of the epoxy resin composition according to claim 1.