JP2012197400A - Epoxy resin composition and cured material thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an epoxy resin composition having sufficiently excellent hardening characteristics even when a phenolic resin having an allyl-etherized phenolic hydroxyl group is used as a hardening agent, and a cured material thereof.SOLUTION: The epoxy resin composition contains an epoxy resin, a phenolic hardening agent, and a hardening accelerator. The phenolic hardening agent contains an allyl-etherized phenolic hydroxyl group. The hardening accelerator contains at least one compound selected from the group consisting of aryl borate salts and triarylborane amine complexes.

Description

  The present invention relates to an epoxy resin composition and a cured product thereof.

  Epoxy resins are excellent in heat resistance, moisture resistance, electrical properties, and adhesiveness, and are used in a wide range of fields such as electrical insulating materials, paints, and adhesives. When an epoxy resin is used for electronic parts, a phenol resin-based curing agent is used from the viewpoint of electrical insulation and heat resistance.

  The phenolic resin used as a curing agent introduces a rigid skeleton to improve heat resistance (increase the glass transition temperature) and a skeleton that exhibits crystallinity and liquid crystallinity to improve thermal conductivity. There is a need to do. However, a phenol resin having such a structure tends to be difficult to handle because it has a high melting temperature, a high melt viscosity, and a low solubility in a solvent or an epoxy resin.

  Therefore, attempts have been made to improve the solubility and melt viscosity of the phenolic resin by introducing a fat-soluble substituent into the phenolic resin or by protecting the phenolic hydroxyl group to suppress intermolecular hydrogen bonding. For example, Patent Document 1 discloses a curing agent for epoxy resins made of a phenol polymer in which a part of a phenolic hydroxyl group is allyl etherified.

JP 2000-234008 A

  Allyl etherification of a phenolic hydroxyl group is useful as a protective group for the phenolic hydroxyl group because the phenolic hydroxyl group is regenerated without a catalyst by the Claisen rearrangement reaction. Since it becomes low, it exists in the tendency for the sclerosis | hardenability of an epoxy resin composition to fall.

  The present invention has been made in view of the above circumstances, and an epoxy resin composition that is sufficiently excellent in curability even when a phenol resin having an allyl etherified phenolic hydroxyl group is used as a curing agent, and a cured product thereof. The purpose is to provide.

  As a result of intensive studies, the present inventors have obtained an epoxy resin composition that is sufficiently excellent in curability by combining a phenolic curing agent having an allyl etherified phenolic hydroxyl group and a specific curing accelerator. It was found that can be obtained.

  That is, the present invention contains an epoxy resin, a phenolic curing agent, and a curing accelerator, the phenolic curing agent has an allyl etherified phenolic hydroxyl group, and the curing accelerator is an aryl borate salt. And an epoxy resin composition comprising at least one compound selected from the group consisting of triarylborane-amine complexes.

  From the viewpoint of further improving the curability of the epoxy resin composition, the aryl borate salt is preferably a compound represented by the following general formula (I).

［式（Ｉ）中、Ｒ^１、Ｒ^２、Ｒ^３及びＲ^４はそれぞれ独立に、置換基を有していてもよい炭化水素基を示し、Ｒ^１、Ｒ^２、Ｒ^３及びＲ^４のうち少なくとも一つはアリール基であり、Ｍは、アルカリ金属、アルキルアンモニウム塩、イミダゾリウム塩、テトラアリールホスホニウム塩又はテトラアルキルホスホニウム塩を示す。］

[In formula (I), R ¹ , R ² , R ³ and R ⁴ each independently represents a hydrocarbon group which may have a substituent, and R ¹ , R ² , R ³ and R ⁴ At least one of them is an aryl group, and M represents an alkali metal, alkylammonium salt, imidazolium salt, tetraarylphosphonium salt or tetraalkylphosphonium salt. ]

  Further, when the triarylborane-amine complex is a compound represented by the following general formula (II), the curability of the epoxy resin composition can be further improved.

［式（ＩＩ）中、Ｒ^５、Ｒ^６及びＲ^７はそれぞれ独立に、置換基を有していてもよいアリール基を示し、Ｘは窒素原子を有するアミン化合物を示す。］

[In formula (II), R ⁵ , R ⁶ and R ⁷ each independently represents an aryl group which may have a substituent, and X represents an amine compound having a nitrogen atom. ]

  Furthermore, since the compatibility with an epoxy resin improves more that the allyl etherification rate of the phenolic hydroxyl group which a phenol type hardening | curing agent has exceeds 50 mol%, the handleability of an epoxy resin composition becomes easy.

  The present invention also provides a cured product formed by curing the epoxy resin composition by heating. Since the cured product is sufficiently excellent in heat resistance and electrical insulation, it is useful as a member for an electronic component device.

  According to the present invention, it is possible to provide an epoxy resin composition that is sufficiently excellent in curability even when a phenol resin having an allyl etherified phenolic hydroxyl group is used as a curing agent, and a cured product thereof.

  The epoxy resin composition of the present invention comprises an epoxy resin (hereinafter referred to as “component (A)”), a phenolic curing agent (hereinafter referred to as “component (B)”), and a curing accelerator (hereinafter referred to as “(C ) Component)). The phenolic curing agent according to the present invention has an allyl etherified phenolic hydroxyl group. Furthermore, the curing accelerator according to the present invention contains at least one compound selected from the group consisting of aryl borate salts and triarylborane-amine complexes.

<(A) component: epoxy resin>
There is no restriction | limiting in particular as (A) component, A well-known epoxy resin can be used. Epoxy resins include glycidyl ethers of phenols such as bisphenol A, bisphenol F, bisphenol S, phenol novolak, cresol novolak, resorcinol novolak, glycidyl ethers of alcohols such as butanediol, polyethylene glycol, polypropylene glycol, phthalic acid, isophthal Glycidyl type (including methyl glycidyl type) epoxy resins such as glycidyl esters of acids, glycidyl esters of carboxylic acids such as tetrahydrophthalic acid, active hydrogen bonded to nitrogen atoms such as aniline and isocyanuric acid, etc. 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate obtained by epoxidizing the olefinic bonds of , Alicyclic epoxy resins such as 2- (3,4-epoxy) cyclohexyl-5,5-spiro (3,4-epoxy) cyclohexane-m-dioxane, epoxidized bis (4-hydroxy) thioether, paraxylylene Glycidyl ether of modified phenolic resin, glycidyl ether of metaxylylene / paraxylylene modified phenolic resin, glycidyl ether of terpene modified phenolic resin, glycidyl ether of dicyclopentadiene modified phenolic resin, glycidyl ether of cyclopentadiene modified phenolic resin, polycyclic aromatic ring modified phenol Resin glycidyl ether, naphthalene ring-containing phenol resin glycidyl ether, stilbene epoxy resin, biphenyl epoxy resin, halogenated phenol novolac epoxy Resins. An epoxy resin can be used individually or in mixture of 2 or more types.

<(B) component: phenolic curing agent>
There is no restriction | limiting in particular as (B) component, The phenol type hardening | curing agent which made the ether ether of at least one part of the hydroxyl group of a well-known phenol resin can be used. Examples of the phenol resin include phenols such as phenol, cresol, xylenol, resorcinol, catechol, bisphenol A, and bisphenol F, or naphthols such as α-naphthol, β-naphthol, and dihydroxynaphthalene, and formaldehyde, acetaldehyde, propionaldehyde, and benzaldehyde. Resins obtained by condensation or cocondensation with aldehydes such as salicylaldehyde in the presence of an acidic catalyst, biphenyl skeleton type phenol resins, paraxylylene modified phenol resins, metaxylylene / paraxylylene modified phenol resins, melamine modified phenol resins, terpene modified phenol resins Dicyclopentadiene modified phenolic resin, cyclopentadiene modified phenolic resin, polycyclic aromatic ring modified phenolic resin and key Examples include silylene-modified naphthol resins. A phenol type hardening | curing agent can be used individually or in mixture of 2 or more types.

  The allyl etherification rate of the phenolic hydroxyl group in the phenol resin is preferably more than 50 mol%, more preferably 70 to 100 mol% from the viewpoint of fast curability, solubility, melt viscosity, storage stability. It is more preferable that it is 80-100 mol% from a viewpoint of property. When the allyl etherification rate of the phenolic hydroxyl group is more than 50 mol%, the compatibility with the component (A) is improved, and the handling property of the epoxy resin composition becomes easy. Moreover, since the phenolic hydroxyl group is allyl etherified, the reaction between the phenolic curing agent and the epoxy resin during storage can be suppressed, and deterioration of the resin composition and increase in viscosity can be prevented. Furthermore, coloring of the hardened | cured material by oxidation of a phenolic hydroxyl group can also be suppressed. Further, by protecting the phenolic hydroxyl group and suppressing intermolecular hydrogen bonding, the melting point of the phenol-based curing agent can be lowered (further liquefied), the melt viscosity can be lowered, and the handleability can be improved.

  The blending ratio of the epoxy resin and the phenolic curing agent is such that the ratio of the hydroxyl equivalent of the phenol resin before allyl etherification to the epoxy equivalent of the epoxy resin is set in the range of 0.5 to 2.0. More preferably, it is 0.7-1.5, More preferably, it is 0.8-1.3. If the blending ratio is less than 0.5, curing of the epoxy resin is insufficient, and the heat resistance, strength, etc. of the cured product tends to be inferior, and if it exceeds 2.0, the phenol resin component remains, so the heat resistance, strength, etc. of the cured product are low. Inferior.

<(C) component: hardening accelerator>
The curing accelerator as component (C) includes at least one compound selected from the group consisting of aryl borate salts and triarylborane-amine complexes.

  In the epoxy resin composition of the present embodiment, the component (C) needs to be stable up to around 200 ° C. where allyl ether causes a Claisen rearrangement reaction. On the other hand, when an amine-based or imidazole-based curing accelerator is used, the epoxy resin alone easily causes a curing reaction before the Claisen rearrangement proceeds. In addition, when a phosphine-based curing accelerator is used, although the epoxy resin is not cured alone, the catalytic activity may be deactivated before the Claisen rearrangement reaction proceeds due to the reaction between the epoxy resin and the phosphine. In contrast, the aryl borate salt and the triarylborane-amine complex have low catalytic activity for single curing of the epoxy resin and do not lose catalytic activity until around 200 ° C. at which the Claisen rearrangement reaction proceeds. And can be suitably used in combination.

  As the aryl borate salt, for example, a compound represented by the following general formula (I) can be used.

In formula (I), R ¹ , R ² , R ³ and R ⁴ each independently represents a hydrocarbon group which may have a substituent, and among R ¹ , R ² , R ³ and R ⁴ At least one is an aryl group. Preferably R ^{1, R} 2, ^{R 3} and at least three of the ^{R 4} is an aryl ^group, more preferably R ^1, R 2, ^{R 3} and ^{R 4} is an aryl ^group, R 1, ^{R 2} More preferably, R ³ and R ⁴ are phenyl groups. M represents an alkali metal, alkylammonium salt, imidazolium salt, tetraarylphosphonium salt or tetraalkylphosphonium salt, and is preferably a tetraarylphosphonium salt or imidazolium salt from the viewpoint of availability and cost.

  Specific examples of aryl borate salts include sodium tetraphenylborate, tetraphenylphosphonium tetraphenylborate, tetraphenylphosphonium tetra-p-tolylborate, tri-tert-butylphosphonium tetraphenylborate, and tetra-n-butylphosphonium tetraphenyl. Examples include borate, 2-ethyl-4-methylimidazolium tetraphenylborate and lithium triphenyl (n-butyl) borate. Aryl borate salts can be used alone or in admixture of two or more.

  As the triarylborane-amine complex, for example, a compound represented by the following general formula (II) can be used.

In formula (II), R ⁵ , R ⁶ and R ⁷ each independently represent an aryl group which may have a substituent, and is preferably a phenyl group. X represents an amine compound having a nitrogen atom.

  As the amine compound (X) constituting the triarylborane-amine complex, a known compound can be used without particular limitation as long as it is a compound having Lewis basicity. Examples of the amine compound include aliphatic or aromatic primary amines, secondary amines, and tertiary amine compounds, and nitrogen-containing heterocyclic compounds such as pyridine, imidazole, and pyrazole. X is preferably an imidazole compound from the viewpoint of the thermal decomposition temperature of the borane complex and the curing promoting action of the amine compound to be formed.

  As the triarylborane-imidazole complex, specifically, a complex represented by the following general formula (III) or the following general formula (IV) can be used.

In the formula, R ⁸ , R ⁹ , R ¹⁰ , R ¹¹ , R ¹² , R ¹³ , R ¹⁴ and R ¹⁵ each independently represent a hydrogen atom, a halogen atom, an alkyl group, an aryl group or an alkoxy group. Y ¹ , Y ² and Y ³ each independently represent a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group or an amino group, and are preferably a hydrogen atom from the viewpoint of cost and availability. Further, from the viewpoint of storage stability, a halogen atom is preferable, and a fluorine atom is more preferable. Furthermore, an alkyl group is preferable from the viewpoint of solubility.

  It is preferable that the compounding quantity of a hardening accelerator is 0.1-20 mass parts with respect to a total of 100 mass parts of (A) component and (B) component, and it is more preferable that it is 0.5-15 mass parts. The amount is preferably 1 to 8 parts by mass. By setting it as the said range, coexistence of latency and quick curability becomes easy especially. On the other hand, if the blending amount of the curing accelerator is less than 0.1 parts by mass, it is difficult to obtain a sufficient curing accelerating action, and if it exceeds 20 parts by mass, phase separation with the epoxy resin tends to occur. The curing accelerator may be used alone or in admixture of two or more kinds. Moreover, well-known hardening accelerators other than an aryl borate salt and a triaryl borane-amine complex can also be used together.

  In the epoxy resin composition of the present embodiment, a thermoplastic resin can be blended for the purpose of adjusting the film formability and the crosslinking density. Specifically, polyimide, polyamide, phenoxy resins, poly (meth) acrylates, polyimides, polyurethanes, polyesters, polyester urethanes, polyvinyl butyrals, and the like can be used as the thermoplastic resin. These can be used alone or in admixture of two or more.

  In the epoxy resin composition of the present embodiment, a rubber component may be used in combination for the purpose of stress relaxation and adhesion improvement. Specific examples of rubber components include polyisoprene, polybutadiene, carboxyl-terminated polybutadiene, hydroxyl-terminated polybutadiene, 1,2-polybutadiene, carboxyl-terminated 1,2-polybutadiene, hydroxyl-terminated 1,2-polybutadiene, acrylic rubber, and styrene. -Butadiene rubber, hydroxyl-terminated styrene-butadiene rubber, acrylonitrile-butadiene rubber, carboxyl group, hydroxyl group, (meth) acryloyl group or morpholine group-containing acrylonitrile-butadiene rubber, carboxylated nitrile rubber, hydroxyl-terminated poly (oxy) Propylene), alkoxysilyl group-terminated poly (oxypropylene), poly (oxytetramethylene) glycol, polyolefin glycol, and poly-ε-caprolactone. You may use a rubber component individually or in mixture of 2 or more types.

  In the epoxy resin composition of the present embodiment, an inorganic filler may be used in combination for the purpose of adjusting the viscosity, reducing the linear expansion coefficient, and improving the thermal conductivity. Specific examples of inorganic fillers include fused silica, crystalline silica, glass, alumina, calcium carbonate, zirconium silicate, calcium silicate, silicon nitride, aluminum nitride, boron nitride, graphite and the like, with no particular limitations. Can be used. Inorganic fillers may be used alone or in admixture of two or more.

  The epoxy resin composition of the present invention is sufficiently excellent in curability even when a phenol resin having an allyl etherified phenolic hydroxyl group is used as a curing agent. By curing the epoxy resin composition by heating, a cured product having excellent heat resistance and electrical insulation can be formed. The epoxy resin composition of the present invention can be used as an electrical insulating material, paint, molding material, laminated board material, adhesive, and the like, and is suitably used for general electronic component devices. With the epoxy resin composition of the present invention, an electronic component device including a cured product that is sealed, molded, or connected is manufactured.

  Hereinafter, the present invention will be specifically described based on examples, but the present invention is not limited thereto.

(Synthesis of phenol resin 1)
In a three-necked flask, hydroquinone (Wako Pure Chemical Industries, Ltd., special grade reagent) 110 g (1.0 mol), formalin (Wako Pure Chemical Industries, Ltd., special grade reagent) 50 g, water (Wako Pure Chemical Industries, Ltd., special grade reagent) 50 g And 0.6 g of oxalic acid (Wako Pure Chemical Industries, Ltd., special grade reagent) were added and heated under reflux at 90 ° C. for 2 hours, and then subjected to vacuum distillation at 150 ° C. and 200 Pa for 2 hours to obtain phenol resin 1 in a yield of 50 %.

(Synthesis of phenol resin 2)
50 g of the above phenol resin 1, 120 g (1.0 mol) of allyl bromide and 140 g (1.0 mol) of potassium carbonate were dissolved in 200 g of ethanol and heated to reflux at 80 ° C. for 2 hours. A mixture was obtained. The reaction mixture was dissolved in butanone and washed with water three times, followed by drying under reduced pressure at 150 ° C. and 200 Pa for 2 hours to obtain phenol resin 2 which is an allyl etherified product of hydroquinone novolac in a yield of 50%. The allyl etherification rate of the phenol resin 2 was 100 mol%.

(Synthesis of borane complex 1)
In a three-necked flask, 3.4 g (10 mmol) of tetraphenylborate sodium salt (manufactured by Hokuko Chemical Co., Ltd., product name: Hokuboron Na), 10 g of tetrahydrofuran (Wako Pure Chemical Industries, Ltd., special grade reagent) and 5 g of toluene (Wako Pure) Yakugyo Co., Ltd., special grade reagent) was added and dissolved. Next, a three-way cock and a dropping funnel were attached to the three-necked flask, and the vacuum in the flask was repeated four times using a diaphragm pump (ULVAC, Inc., product name: DTU-20) and the nitrogen substitution four times. The dissolved oxygen was degassed and replaced with nitrogen. Next, 3.7 g (10 mmol) of a 10% hydrochloric acid aqueous solution was added to the dropping funnel, and the mixture was added dropwise at 25 ° C. over 1 hour, followed by stirring at 25 ° C. for 2 hours. Furthermore, a solution obtained by diluting 1.1 g (10 mmol) of 2-ethyl-4-methylimidazole (manufactured by Shikoku Kasei Kogyo Co., Ltd., product name: 2E4MZ) with 10 g of toluene was added dropwise at 25 ° C. over 30 minutes. After dropping, the mixture was stirred at 25 ° C. for 2 hours, and then the reaction solution was extracted with toluene and washed with water four times. The toluene phase was recovered, concentrated and dried with a rotary evaporator, and the resulting white solid was washed with a small amount of toluene to obtain borane complex 1 as a triphenylborane-imidazole complex in a yield of 58%.

<Preparation of epoxy resin composition>
Epoxy resin compositions of Examples and Comparative Examples were prepared at the blending ratios shown in Table 1.

Example 1
Biphenyl type epoxy resin (product name: YL-6121, epoxy equivalent 160 g / eq.) As epoxy resin, phenol resin as phenolic curing agent and tetraphenylborate salt as curing accelerator (Hokuko Chemical Co., Ltd.) (Product name: EMZ-K, manufactured by company) was mixed and ground in a mortar to prepare a powdery epoxy resin composition.

(Example 2)
An epoxy resin composition was prepared in the same manner as in Example 1 except that the curing accelerator was changed to tetraphenylborate salt (product name: TPPMK, manufactured by Hokuko Chemical Co., Ltd.).

(Example 3)
An epoxy resin composition was prepared in the same manner as in Example 1 except that the curing accelerator was changed to borane complex 1.

(Comparative Example 1)
Only the phenol resin 2 was used without blending an epoxy resin and a curing accelerator.

(Comparative Example 2)
An epoxy resin composition was prepared in the same manner as in Example 1 except that the curing accelerator was changed to triphenylphosphine (Hokuko Chemical Co., Ltd., product name: TPP).

(Comparative Example 3)
An epoxy resin composition was prepared in the same manner as in Example 1 except that the curing accelerator was changed to an imidazole compound (manufactured by Shikoku Kasei Kogyo Co., Ltd., product name: 2PZ-CN).

  The following evaluation was performed using the said epoxy resin composition. The results are shown in Table 2.

(1) Reaction temperature and heat of reaction The thermal properties of the epoxy resin composition were measured using a differential scanning calorimeter (manufactured by PERKIN ELMER, trade name: DSC7) under nitrogen at a heating rate of 10 ° C./min. The peak temperature was the reaction temperature, and the exotherm was the reaction heat.

(2) Reaction Rate of Epoxy Resin The reaction heat of the epoxy resin composition according to the present invention includes a curing reaction heat of epoxy resin and a reaction heat of Claisen rearrangement of allyl ether. Therefore, the reaction heat ΔH2 (J / g) and reaction temperature of the rearrangement reaction of allyl ether were calculated from the measurement results of the reaction heat and reaction temperature of the phenol resin 2 alone in Comparative Example 1. Next, the reaction heat ΔH (J / g) derived from the curing of the epoxy resin in the epoxy resin composition, the reaction heat ΔH1 (J / g) of the entire epoxy resin composition, the reaction heat ΔH2 of the phenol resin 2 (J / g) ) And the compounding ratio (% by mass) of the phenol resin 2 in the resin composition.
ΔH = ΔH1−ΔH2 × w / 100 (2)

Moreover, epoxy reaction rate (alpha) was computed by Formula (3) using the value of (DELTA) H3 = 230J / g computed from the reaction heat of a well-known general epoxy-phenol hardening system.
α = ΔH / ΔH3 × 100 (3)

  In Comparative Example 1 using only the phenol resin 2, heat generation due to Claisen rearrangement was observed at around 236 ° C. From the calorific value 471 J / g at this time, the calorific value derived from the Claisen rearrangement in Comparative Examples 2 and 3 and Examples 1 to 3 was calculated as 161 J / g. Further, Comparative Example 2 using a phosphine compound as a curing accelerator showed a calorific value almost equal to the calorific value derived from the Claisen rearrangement, and the curing reaction of the epoxy resin hardly proceeded. Furthermore, in Comparative Example 2 using an imidazole compound as a curing accelerator, heat generation derived from curing of the epoxy resin was observed at around 161 ° C. separately from heat generation resulting from the Claisen rearrangement at around 237 ° C., before the Claisen rearrangement. Since the epoxy resin is cured, the allyl etherified phenol resin is not involved in the curing, and the curing with the epoxy resin alone has progressed.

  On the other hand, in Examples 1 to 3 using an aryl borate salt or a triarylborane-amine complex as a curing accelerator, the calorific value is higher than the calorific value derived from the Claisen rearrangement. The curing reaction was in progress and showed a good epoxy cure rate.

  From the above, it was confirmed that the epoxy resin composition of the present invention was sufficiently excellent in curability when a phenol resin having an allyl etherified phenolic hydroxyl group was used as a curing agent.

Claims (5)

Containing an epoxy resin, a phenolic curing agent, and a curing accelerator,
The phenolic curing agent has an allyl etherified phenolic hydroxyl group,
An epoxy resin composition, wherein the curing accelerator includes at least one compound selected from the group consisting of an aryl borate salt and a triarylborane-amine complex. The epoxy resin composition according to claim 1, wherein the aryl borate salt is a compound represented by the following general formula (I).

[In formula (I), R ¹ , R ² , R ³ and R ⁴ each independently represents a hydrocarbon group which may have a substituent, and R ¹ , R ² , R ³ and R ⁴ At least one of them is an aryl group, and M represents an alkali metal, alkylammonium salt, imidazolium salt, tetraarylphosphonium salt or tetraalkylphosphonium salt. ] The epoxy resin composition according to claim 1, wherein the triarylborane-amine complex is a compound represented by the following general formula (II).

[In formula (II), R ⁵ , R ⁶ and R ⁷ each independently represents an aryl group which may have a substituent, and X represents an amine compound having a nitrogen atom. ]   The epoxy resin composition as described in any one of Claims 1-3 whose allyl etherification rate of the said phenolic hydroxyl group is more than 50 mol%.   Hardened | cured material formed by hardening | curing the epoxy resin composition as described in any one of Claims 1-4 by heating.