JP5998347B2 - Epoxy resin composition - Google Patents

Description

The present invention relates to an epoxy resin composition useful for paints, coating agents, printing inks, resist inks, adhesives, semiconductor sealing materials, optical semiconductor sealing materials, molding materials, electrical insulating materials and the like.

Epoxy resins are excellent in adhesiveness, insulation, heat resistance, workability, cost performance, etc., so they can be used in the fields of paints, adhesives, composites, etc. Widely used in the field of electronic materials. Among them, in the field of electrical and electronic materials, the characteristics required of materials are becoming more sophisticated with the passage of time.

With the recent downsizing and higher performance of electronic device parts, the number of modules that handle high-frequency signals has increased. In printed wiring board materials, when high-frequency signals are passed through conductors on the board, the current is caused by the skin effect It is thought that it concentrates on. However, since a metal such as copper, which is a conductor, and the resin are bonded by an anchor effect using a rough surface, a large transmission loss occurs. Therefore, in order to reduce transmission loss, metal foil with a reduced roughness of the metal surface is used, but peeling at the interface between the metal and the resin has become a problem, and the adhesion of the resin to the metal Improvement of power is desired.
Further, in the semiconductor sealing material, peeling at the interface between the copper lead frame or the gold-plated bonding wire and the resin has become a problem, and improvement of the adhesive strength of the resin to the metal is desired.

It has been found that for such metals used in the field of electrical and electronic materials, particularly copper, excellent affinity can be imparted by adding a compound containing a sulfur atom to the epoxy resin. For example, Patent Document 1 and Patent Document 2 disclose a method for improving the adhesion to copper by adding a compound having a disulfide bond to an epoxy resin, and Patent Document 3 discloses a cyclic structure having a disulfide bond. A method for improving the adhesion to copper by adding a compound (cyclic disulfide compound) to an epoxy resin is disclosed.

JP 2004-285316 A JP 2006-028476 A JP 2008-174711 A

In the methods disclosed in Patent Document 1 and Patent Document 2, the effect of improving the adhesive strength to copper is small, and yellowing occurs in the cured product, which limits the application.
In the method disclosed in Patent Document 3, there is a method in which the effect of improving the adhesion to copper is increased, but it is difficult to handle due to poor dispersibility of the cyclic disulfide compound in the epoxy resin, and it is hardened by introduction of a polar group. There was a problem that it adversely affected the water absorption of the later epoxy resin composition.
An object of the present invention is to provide an epoxy resin composition that is easy to handle, and has excellent adhesion to metal and excellent water absorption and transparency of a cured product.

The present invention is an epoxy resin composition containing an epoxy resin and a cyclic disulfide compound represented by the following formula (1).

In formula (1), m and n are each independently an integer of 2 to 3 . R ^{1 to} R ⁴ represent H. X represents O or S.
The present invention is described in detail below.

The present inventors have found that a cyclic disulfide compound having a specific structure is excellent in dispersibility in an epoxy resin and is easy to handle, and further, by adding the cyclic disulfide compound, adhesion to a metal, And it discovered that the epoxy resin composition excellent in the water absorption and transparency of hardened | cured material could be obtained, and came to complete this invention.

Since the cyclic disulfide compound represented by the formula (1) is excellent in dispersibility in an epoxy resin, the epoxy resin composition of the present invention is easy to handle, and further has adhesiveness to metal and cured product. It is excellent in water absorption and transparency.

In the formula (1), m and n are each independently an integer of 1 to 6. When at least one of m and n exceeds 6, the structure becomes flexible, adversely affects the heat resistance such as glass transition temperature and linear expansion coefficient of the resulting epoxy resin composition, and further provides low adhesion with low sulfur concentration. The effect may be reduced. A preferred upper limit for m and n is 3, and a more preferred upper limit is 2.

In the formula (1), R ^{1 to} R ⁴ represent OH, SH, COOH, NH ₂ , or a C 1-6 alkyl group having these substituents, or H, which are the same as each other It may be different or different. When R ^{1 to} R ⁴ are the alkyl group or H, the epoxy resin composition of the present invention is particularly excellent in adhesion to metal. Among these, R ^{1 to} R ⁴ are preferably H.

In the formula (1), X represents O, S, or NH. When X is O, S, or NH, the cyclic disulfide compound represented by the formula (1) has excellent dispersibility in the epoxy resin. Among these, X is preferably S because it is particularly excellent in adhesion to metal.

Since the cyclic disulfide compound represented by the formula (1) has an appropriate strained structure, the effect of improving the adhesion of the resulting epoxy resin composition to the metal is increased. Or it is preferable that it is a seven-membered ring, and it is more preferable that it is a seven-membered ring.

The cyclic disulfide compound represented by the formula (1) is preferably a cyclic disulfide compound represented by the following formula (2) because it is excellent in the effect of improving the adhesion to metal.

Specific examples of other cyclic disulfide compounds represented by the formula (1) include cyclic disulfide compounds represented by the following formula (3).

The cyclic disulfide compound represented by the formula (1) may be used alone or in combination of two or more.

The cyclic disulfide compound represented by the formula (1) is preferably liquid at room temperature in order to have excellent dispersibility in the epoxy resin. When the cyclic disulfide compound represented by the formula (1) is a solid or high viscosity at room temperature, the dispersibility in the epoxy resin may be inferior. In addition, the cyclic disulfide compound represented by the formula (1) preferably has a solubility parameter (SP value) of 9 to 12 in order to have excellent compatibility with the epoxy resin. If it is, the mechanical strength and heat resistance may be adversely affected without being uniformly dispersed.
The viscosity at room temperature of the cyclic disulfide compound represented by the formula (1) is not particularly limited, but is preferably less than 20,000 mPa · s, and more preferably less than 5000 mPa · s.
The boiling point of the cyclic disulfide compound represented by the formula (1) is not particularly limited, but is preferably 80 ° C. or higher. When the boiling point of the cyclic disulfide compound represented by the formula (1) is less than 80 ° C., molding defects such as voids may occur when the epoxy resin is cured. The boiling point of the cyclic disulfide compound represented by the formula (1) is more preferably 100 ° C. or higher.

Although the compounding quantity of the cyclic disulfide compound represented by the formula (1) is not particularly limited, the preferable lower limit is 0.01 part by weight and the preferable upper limit is 5 parts by weight with respect to 100 parts by weight of the epoxy resin. When the blending amount of the cyclic disulfide compound represented by the formula (1) with respect to 100 parts by weight of the epoxy resin is less than 0.01 parts by weight, the resulting epoxy resin composition may be inferior in adhesion to metal. . When the compounding quantity of the cyclic disulfide compound represented by Formula (1) with respect to 100 weight part of epoxy resins exceeds 5 weight part, it may have a bad influence on the toughness and heat resistance of the hardened | cured material of the obtained epoxy resin composition. The more preferable lower limit of the compounding amount of the cyclic disulfide compound represented by the formula (1) with respect to 100 parts by weight of the epoxy resin is 0.1 part by weight, and the more preferable upper limit is 3 parts by weight.

The content of the cyclic disulfide compound in the entire epoxy resin composition of the present invention is not particularly limited, but a preferable lower limit is 0.001% by weight and a preferable upper limit is 3% by weight. When the content of the cyclic disulfide compound represented by the formula (1) in the entire epoxy resin composition of the present invention is less than 0.001% by weight, the resulting epoxy resin composition has poor adhesion to metal. Sometimes. If the content of the cyclic disulfide compound represented by the formula (1) in the entire epoxy resin composition of the present invention exceeds 3% by weight, the toughness and heat resistance of the cured product of the resulting epoxy resin composition may be adversely affected. There is. The more preferable lower limit of the content of the cyclic disulfide compound represented by the formula (1) in the entire epoxy resin composition of the present invention is 0.005% by weight, and the more preferable upper limit is 2% by weight.

The epoxy resin composition of the present invention contains an epoxy resin.
The epoxy resin is not particularly limited. For example, bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, alicyclic epoxy resin, brominated epoxy resin, nitrogen-containing ring epoxy Resin triglycidyl isocyanurate, hydantoin type epoxy resin, hydrogenated bisphenol A type epoxy resin, aliphatic epoxy resin, glycidyl ether type epoxy resin, bisphenol S type epoxy resin, biphenyl type epoxy resin, dicyclo type epoxy resin, naphthalene A type epoxy resin or the like can be used. Among these, bisphenol A type epoxy resin, bisphenol F type epoxy resin, hydrogenated bisphenol A are widely used as sealing materials for optical semiconductors such as LED elements and are excellent in transparency, toughness, and heat resistance. A type epoxy resin is preferably used. In addition, novolak-type phenolic novolac-type epoxy resins and cresol novolak-type epoxy resins are also suitably used because they provide a hardened material that is in great demand as a semiconductor sealing material and has excellent heat resistance, chemical resistance, and electrical properties. . These epoxy resins may be used alone or in combination of two or more.

The epoxy resin composition of the present invention preferably contains a curing agent.
As the curing agent, for example, an amine curing agent, an acid anhydride curing agent, a polyamide curing agent, a boron trifluoride amine complex, dicyandiamide, or the like, which is a latent curing agent, is used according to each application. be able to. Also, phenolic resins such as novolac type phenolic resins widely used for semiconductor sealing materials can be used as a curing agent.
Examples of the amine curing agent include aliphatic polyamines such as diethylenetriamine and triethylenetetramine, and aromatic polyamines such as metaphenylenediamine, diaminodiphenylmethane, and diaminodiphenylsulfone. However, although the amine-based curing agent exhibits excellent adhesion to metals, it causes toxicity to the human body, high viscosity, and coloring.
Examples of the acid anhydride-based curing agent include succinic anhydride, maleic anhydride, phthalic anhydride, hexahydrophthalic anhydride, methyl hexahydrophthalic anhydride, methyl tetrahydrophthalic anhydride, nadic anhydride, and hydrogenated anhydride. Nadic acid, trimetic anhydride, pyromellitic anhydride, etc. can be used.
The acid anhydride curing agent is easy to handle with low viscosity, the pot life is relatively long, the cured product is excellent in electrical insulation, mechanical properties, heat stability, chemical resistance, It has advantages such as superior safety and hygiene compared to the amine curing agent, and is suitable for optical semiconductor sealing materials such as LED elements, semiconductor sealing materials, and electrical / electronic insulating materials. Can be used. Among these acid anhydride curing agents, phthalic anhydride, hexahydrophthalic anhydride, and methylhexahydrophthalic anhydride are preferably used.
These curing agents may be used alone or in combination of two or more.

Although the compounding quantity of the said hardening | curing agent is not specifically limited, it mix | blends so that the active group which can react with the epoxy group in a hardening | curing agent will be 0.5-1.5 equivalent with respect to 1 equivalent of epoxy groups in the said epoxy resin. It is preferable to mix, and it is more preferable to mix | blend so that it may become 0.7-1.2 equivalent.

Generally, a curing agent such as an acid anhydride curing agent has a long pot life and low toxicity, but on the other hand, the curing reaction proceeds relatively slowly, and thus curing may require a high temperature and a long time. Therefore, you may use a hardening | curing agent and a hardening accelerator together as needed.

Examples of the curing accelerator include benzyldimethylamine, cyclohexyldimethylamine, triethanolamine, 2- (dimethylaminomethyl) phenol, and 1,8-diazabicyclo (5,4,0) -undecene-7. Secondary amines, 2-methylimidazole, 2-ethylimidazole, 2-n-heptylimidazole, 2-n-undecylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2- Methylimidazole, 1-benzyl-2-phenylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 1- (2-cyanoethyl) -2-methylimidazole, 1- (2-cyanoethyl) -2 -N-undecylimidazole, 1- (2-cyanoe L) -2-phenylimidazole, 1- (2-cyanoethyl) -2-ethyl-4-methylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, 2-phenyl-4,5-di (hydroxy) Methyl) imidazole, 1- (2-cyanoethyl) -2-phenyl-4,5-di ((2′-cyanoethoxy) methyl) imidazole, 1- (2-cyanoethyl) -2-n-undecylimidazolium tri Melitate, 1- (2-cyanoethyl) -2-phenylimidazolium trimellitate, 1- (2-cyanoethyl) -2-ethyl-4-methylimidazolium trimellitate, 2,4-diamino-6- ( 2'-methylimidazolyl- (1 ')) ethyl-s-triazine, 2,4-diamino-6- (2'-n-undecylimidazolyl) Ethyl-s-triazine, 2,4-diamino-6- (2′-ethyl-4′-methylimidazolyl- (1 ′)) ethyl-s-triazine, isocyanuric acid adduct of 2-methylimidazole, 2-phenyl Imidazoles such as isocyanuric acid adduct of imidazole, isocyanuric acid adduct of 2,4-diamino-6- (2′-methylimidazolyl- (1 ′)) ethyl-s-triazine, and phosphines such as triphenylphosphine And metal compounds such as tin octylate.
Moreover, when using the phenol resin suitable for a semiconductor sealing material as said hardening | curing agent, as a preferable thing among the hardening accelerators mentioned above, 2- (dimethylaminomethyl) phenol, 1,8-diazabicyclo (5, 4, 0) -undecene-7, 2-methylimidazole, 2-ethylimidazole, 2-ethyl-4-methylimidazole, phosphines, metal compounds and the like.
These curing accelerators may be used alone or in combination of two or more.

Although the compounding quantity of the said hardening accelerator is not specifically limited, Since the epoxy resin composition excellent in the heat resistance and adhesiveness of hardened | cured material is obtained, a preferable minimum is 0.1 with respect to 100 weight part of said epoxy resins. Part by weight, the preferred upper limit is 5.0 parts by weight. A more preferable lower limit of the blending amount of the curing accelerator is 0.5 parts by weight, and a more preferable upper limit is 2 parts by weight.
Moreover, when using a phenol resin as the said hardening | curing agent, it is preferable to mix | blend the said hardening accelerator 0.1-5 weight part with respect to 100 weight part of said epoxy resins.

The epoxy resin composition of the present invention may contain an antioxidant as necessary.
Examples of the antioxidant include 2,6-di-tert-butyl-p-cresol, 2,6-di-tert-butyl-4-ethylphenol, butylated hydroxyanisole, stearyl-β- (3 , 5-di-tert-butyl-4-hydroxyphenyl) propionate, 2,2-methylenebis (4-methyl-6-tert-butylphenol), 2,2-methylenebis (4-ethyl-6) -Tert-butylphenol), 4,4'-thiobis (3-methyl-6-tert-butylphenol) and other bisphenols, 1,1,3-tris (2-methyl-4-hydroxy-5-tert-butyl) Phenyl) butane, 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert-butyl-4-hydroxy High molecular weight phenols such as benzyl) benzene, tetrakis [methylene-3- (3,5-tert-butyl-4-hydroxyphenyl) propionate] methane, 10- (3,5-di-tert-butyl-4 -Hydroxybenzyl) -9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, oxa such as 10-deloxy-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10 oxide Examples thereof include phosphaphenanthrene oxides.

The epoxy resin composition of the present invention may contain a thixotropic agent as necessary.
A commercially available agent can be used as the thixotropy-imparting agent, and examples thereof include Aerosil (manufactured by Nippon Aerosil Co., Ltd.) and Disparon (manufactured by Enomoto Kasei Co., Ltd.).

The epoxy resin composition of the present invention may contain a pigment as necessary.
Examples of the pigment include inorganic pigments such as titanium oxide, zinc oxide, ultramarine, bengara, lithopone, lead, cadmium, iron, cobalt, aluminum, hydrochloride, sulfate, azo pigment, phthalocyanine pigment, quinacridone pigment, quinacridone. Quinone pigment, dioxazine pigment, anthrapyrimidine pigment, anthanthrone pigment, indanthrone pigment, flavanthrone pigment, perylene pigment, perinone pigment, diketopyrrolopyrrole pigment, quinonaphthalone pigment, anthraquinone pigment, thioindigo pigment, benzimidazolone pigment, iso Organic pigments such as indoline pigments and carbon black are listed.

The epoxy resin composition of this invention may contain a ultraviolet absorber as needed.
Examples of the ultraviolet absorber include salicylic acid esters such as phenyl salicylate, benzotriazoles such as 2- (2′-hydroxy-5-methylphenyl) -benzotriazole, and hydroxybenzophenones such as 2-hydroxybenzophenone. And the like.

The epoxy resin composition of this invention may contain a mold release agent as needed.
Examples of the release agent include stearic acid, behenic acid, montanic acid, a polyethylene release agent, a polyethylene-polyoxyethylene release agent, and carnauba wax.

The epoxy resin composition of the present invention may contain a flame retardant as necessary.
Examples of the flame retardant include chloroalkyl phosphate, dimethylmethylphosphonate, brominated organic phosphorus compound, ammonium polyphosphate, neopentyl bromide polyether, brominated polyether, and the like.

Furthermore, the epoxy resin composition of the present invention may contain additives such as a film forming agent, a rubber modifier, a surfactant, a reactive diluent, various oligomers, and various polymers, if necessary. These additives may be used alone or in combination of two or more.

As a method for producing the epoxy resin composition of the present invention, for example, the epoxy resin, the cyclic disulfide compound represented by the formula (1), the curing agent, the curing accelerator and the like are used in three rolls, a kneader. And a method of mixing using a kneading apparatus such as an extruder.

The epoxy resin composition of the present invention has excellent 5% weight loss temperature, high glass transition temperature, and low linear expansion coefficient, in addition to excellent adhesion to metals and water absorption and transparency of cured products. For this reason, the cured product is stable to heat and has a higher dielectric constant, so that it can be suitably used as a semiconductor sealing material or the like.

According to the present invention, it is possible to provide an epoxy resin composition that is easy to handle and excellent in adhesion to metal and water absorption and transparency of a cured product. Since the epoxy resin composition of the present invention exhibits high adhesion to metals, it is useful in the field of electronic materials, particularly in the field of sealing materials.

Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these examples.

(Synthesis Example 1)
(Production of cyclic disulfide compound (1,2,5-trithiacycloheptane) represented by formula (2))
A four-necked flask with an internal volume of 500 mL was charged with 15.4 g (0.1 mol) of bis (mercaptoethyl) sulfide, 100 g of toluene, 80 g of water, and 0.7 g (0.05 mol) of a 30 wt% aqueous sodium hydroxide solution. After cooling to 10 ° C., 34.0 g (0.1 mol) of 10.0% by weight hydrogen peroxide was added dropwise. After completion of the dropping, the temperature was raised to room temperature and stirred for 2 hours, followed by filtration. The filtrate was separated and the organic phase was washed with 50.0 g of water. The organic phase was concentrated under reduced pressure to obtain 11.9 g of 1,2,5-trithiacycloheptane. The yield of 1,2,5-trithiacycloheptane obtained was 78% with respect to bis (mercaptoethyl) sulfide.

(Synthesis Example 2)
(Production of cyclic disulfide compound (1,4,5-oxadithiepan) represented by formula (4))
To a four-necked flask having an internal volume of 300 mL equipped with a stirrer, a thermometer, a dropping funnel and a condenser tube, 48.0 g (0.2 mol) of sodium sulfide (Na ₂ S) nonahydrate and 6.4 g of sulfur (0 mol) .2 mol) and 30 g of water were charged and dissolved at 70 ° C. with stirring. Next, after cooling to 30 ° C., 0.3 g (1.0 mmol) of tetrabutylammonium bromide and 50 g of toluene were added to the flask. Then, 23.2 g (0.1 mol) of bis (2-bromoethyl) ether was added dropwise to the flask over 1 hour while maintaining the temperature at 30 ° C., followed by stirring at 30 ° C. for 2 hours. Subsequently, it stirred for 2 hours, heating at 70 degreeC.
Then, it cooled to room temperature and liquid-separated the organic phase in a reaction liquid, Then, the obtained organic phase was wash | cleaned one by one by 10 weight% sodium hydroxide aqueous solution, 5 weight% hydrochloric acid water, and water. The organic phase after washing was concentrated under reduced pressure to obtain 10.9 g of a cyclic disulfide compound (1,4,5-oxadithiepan) represented by the following formula (4). The yield of the obtained 1,4,5-oxadithiepan was 77.6% with respect to bis (2-bromoethyl) ether, and the purity was 97.0%.

Example 1
2 parts by weight of the cyclic disulfide compound represented by the formula (2) is blended with 100 parts by weight of bisphenol A type epoxy resin (manufactured by Mitsubishi Chemical Corporation, “jER828”), and Ricacid MH-700 (Shin Nihon) is used as a curing agent. Rika, 90 parts by weight of 4-methylhexahydrophthalic anhydride / hexahydrophthalic anhydride = 70/30, 2-ethyl-4-methylimidazole (manufactured by Shikoku Kasei Co., Ltd., “Cureazole 2E4MZ”) 1 Part by weight was added and stirred using a fluororesin rotor to obtain an epoxy resin composition.

(Example 2)
An epoxy resin composition was obtained in the same manner as in Example 1 except that the amount of the cyclic disulfide compound represented by the formula (2) was changed to 0.5 parts by weight.

(Example 3)
An epoxy resin composition was obtained in the same manner as in Example 1 except that the cyclic disulfide compound represented by the formula (4) was used instead of the cyclic disulfide compound represented by the formula (2).

(Comparative Example 1)
An epoxy resin composition was obtained in the same manner as in Example 1 except that the cyclic disulfide compound represented by the formula (2) was not used.

(Comparative Example 2)
An epoxy resin composition was obtained in the same manner as in Example 1 except that a disulfide compound represented by the following formula (5) was used instead of the cyclic disulfide compound represented by the formula (2).

(Comparative Example 3)
An epoxy resin composition was obtained in the same manner as in Example 1 except that a disulfide compound represented by the following formula (6) was used instead of the cyclic disulfide compound represented by the formula (2).

(Comparative Example 4)
An epoxy resin composition was obtained in the same manner as in Example 1 except that a cyclic disulfide compound represented by the following formula (7) was used instead of the cyclic disulfide compound represented by the formula (2).

(Comparative Example 5)
An epoxy resin composition was obtained in the same manner as in Example 1 except that a cyclic disulfide compound represented by the following formula (8) was used instead of the cyclic disulfide compound represented by the formula (2).

<Evaluation>
The following evaluation was performed about the epoxy resin composition obtained by the Example and the comparative example. The results are shown in Table 1.

(90 degree peel strength test)
An electrolytic copper foil (manufactured by Fukuda Metal Powder Co., Ltd.) having a nominal thickness of 35 μm and a smooth surface roughness Rz = 0.25 μm was cut into a size of 5 cm to 5 cm and washed with acetone to wash the preservative. Etching with% nitric acid for 30 seconds, washing with distilled water, and drying at 60 ° C. gave a test piece.
The epoxy resin compositions obtained in Examples and Comparative Examples were each applied to an aluminum plate, and the smooth surfaces of the test pieces obtained from the same were superposed. After heating at 120 ° C. for 2 hours, the coating was further cured by heating at 170 ° C. for 2 hours, and after curing, a cut was made with a cutter by 1 cm width to obtain a 90-degree peel strength test piece. The aluminum plate was degreased with acetone, then polished with abrasive paper (No. 600), the polishing debris removed with acetone and dried.
About the obtained 90 degree peel strength test piece, 90 degree peel strength test was implemented on the conditions of the test speed of 25 mm / min using DAGE-SERISE4000 (made by an arc rack company).

(5% weight loss temperature)
The epoxy resin compositions obtained in Examples and Comparative Examples were heated at 120 ° C. for 2 hours, then cured by heating at 170 ° C. for 2 hours, and the cured product was finely pulverized to obtain test pieces.
About the obtained test piece, 5% weight reduction | decrease temperature was measured on 35-530 degreeC and temperature rising conditions of 10 degree-C / min using TG / DTA6200 (made by SII).

(Glass-transition temperature)
The epoxy resin compositions obtained in Examples and Comparative Examples were poured into a silicon rubber mold, heated at 120 ° C. for 2 hours, then cured by heating at 170 ° C. for 2 hours, and a test piece for measuring dynamic viscoelasticity. It was. About the obtained test piece for dynamic viscoelasticity measurement, using a viscoelasticity spectrometer ("DMS-110", manufactured by SII), the sample was moved by a three-point bending method at a frequency of 1 Hz and a heating rate of 2 ° C / min. The viscoelasticity was measured and the glass transition temperature was calculated.

(Linear expansion coefficient)
The epoxy resin compositions obtained in Examples and Comparative Examples were poured into a silicon rubber mold, heated at 120 ° C. for 2 hours, then cured by heating at 170 ° C. for 2 hours, and a linear expansion coefficient measurement specimen and did. About the obtained specimen for measuring the linear expansion coefficient, using a thermomechanical analyzer (“EXSTAR TMA / SS6000” manufactured by SII), in a compression mode under a temperature rising condition of 35 to 250 ° C. and 2 ° C./min. The linear expansion coefficient was measured.

(Water absorption rate)
The epoxy resin compositions obtained in the examples and comparative examples were poured into a silicon rubber disk mold, heated at 120 ° C. for 2 hours, then cured by heating at 170 ° C. for 2 hours, and a water absorption measurement test piece and did. The obtained water absorption rate measurement test piece was dried for 24 hours, then weighed once, then boiled in boiling water for 1 hour, cooled to room temperature with cold water, wiped the surface moisture with gauze, and reweighed. From the weight before boiling and the weight after boiling, the water absorption was calculated using the following formula.
Water absorption A (%) = {(W ₂ −W ₁ ) / W ₁ } × 100
However, W ₁ : weight before boiling, W ₂ : weight after boiling.

(Dielectric constant)
The epoxy resin compositions obtained in Examples and Comparative Examples were poured into a silicon rubber mold, heated at 120 ° C. for 2 hours, and then cured by heating at 170 ° C. for 2 hours to obtain a dielectric constant measurement specimen. .
About the obtained test piece for dielectric constant measurement, the dielectric constant was measured using a dielectric constant measuring apparatus (manufactured by Agilent, “RF Impedance Analyzer E4991A”).

(Hue)
The epoxy resin compositions obtained in Examples and Comparative Examples were poured into a silicon rubber disk mold and heated at 120 ° C. for 2 hours to be cured to obtain a hue confirmation test piece. The obtained hue confirmation test piece was visually observed, and the hue was evaluated with “◯” indicating that it was transparent and “×” indicating that it had a hue other than that.

(Dispersibility)
The epoxy resin compositions obtained in Examples and Comparative Examples were stirred for 10 minutes in a test tube at room temperature, and the dispersibility was visually observed. The dispersibility was evaluated as “◯” when the disulfide compound was uniformly dispersed, and “x” when the disulfide compound was non-uniformly dispersed.

From Table 1, in the Examples, the epoxy resin composition containing the cyclic disulfide compound represented by the formula (1) has an excellent adhesive force to copper, and further, water absorption, hue, cyclic disulfide compound. It turns out that it is excellent in the dispersibility of. On the other hand, the epoxy resin composition obtained in Comparative Example 1 does not have sufficient adhesive strength to copper, and the epoxy resin compositions obtained in Comparative Examples 2, 3, and 4 have an adhesive strength to copper of disulfide. It became low also compared with the comparative example 1 which did not add a compound. The epoxy resin composition obtained in Comparative Example 5 showed excellent adhesion to copper, but the water absorption was lowered, and furthermore, the color and the dispersibility of the cyclic disulfide compound were inferior. The SP values of the cyclic disulfide compounds represented by the formulas (2) and (4) are 11.0 and 10.2, respectively, and are considered to be excellent in dispersibility because they are close to the SP value of the epoxy resin. The SP values of the cyclic disulfide compounds represented by the formulas (5) to (7) are larger than 12, and it is considered that the dispersibility is poor.

According to the present invention, it is possible to provide an epoxy resin composition that is easy to handle and excellent in adhesion to metal and water absorption and transparency of a cured product.

Claims (4)

An epoxy resin composition comprising an epoxy resin and a cyclic disulfide compound represented by the following formula (1).

In formula (1), m and n are each independently an integer of 2 to 3 . R ^{1 to} R ⁴ represent H. X represents O or S. The epoxy resin composition according to claim 1, wherein the cyclic disulfide compound represented by the formula (1) is a cyclic disulfide compound represented by the following formula (2).

The epoxy resin composition according to claim 1 or 2, wherein the content of the cyclic disulfide compound represented by the formula (1) is 0.01 to 5 parts by weight with respect to 100 parts by weight of the epoxy resin. . The epoxy resin composition according to claim 1, 2 or 3, further comprising a curing agent.