WO2012042796A1 - Cationic polymerization initiator and thermosetting epoxy resin composition - Google Patents

Abstract

Provided are: a cationic polymerization initiator which exhibits excellent curing properties for an epoxy resin composition; and a thermosetting epoxy resin composition. The cationic polymerization initiator is represented by general formula (I) [wherein R¹ is a hydroxyl group, an R⁴O group, an R⁴COO group, an R⁴NHCOO group or an R⁴OCOO group; R² is a C_1-6 alkyl group; R³ is a hydrogen atom or an alkyl group; R⁴ is an optionally substituted, aromatic or aliphatic hydrocarbon group; and X is a compound represented by formula (1)].

Description

Cationic polymerization initiator and thermosetting epoxy resin composition

The present invention relates to a cationic polymerization initiator and a thermosetting epoxy resin composition.

A sulfonium borate complex is known as a cationic polymerization initiator for epoxy resins. As a sulfonium borate complex, for example, a counter anion containing a tetrakis (pentafluorophenyl) borate anion represented by the following formula is known as a counter anion (see, for example, Patent Document 1).

JP-A-9-176112

It is known that an epoxy resin composition containing the sulfonium borate complex as a cationic polymerization initiator is excellent in curability. However, the curing time of the epoxy resin composition is constantly required to be shorter.
An object of the present invention is to provide a cationic polymerization initiator and a thermosetting epoxy resin composition excellent in curability of the epoxy resin composition.

As a result of earnest research to solve the above problems, the present inventor has obtained an epoxy resin composition excellent in curability by using a sulfonium borate complex represented by the following general formula (I) as a cationic polymerization initiator. As a result, the present invention was completed.

（式（Ｉ）において、Ｒ^１は、水酸基、Ｒ^４Ｏ基、Ｒ^４ＣＯＯ基、Ｒ^４ＮＨＣＯＯ基、Ｒ^４ＳＯ_２ＮＨＣＯＯ基又はＲ^４ＯＣＯＯ基であり、Ｒ^２は、炭素数１～６のアルキル基であり、Ｒ^３は、水素原子またはアルキル基である。Ｒ^４は、置換基を有してもよい芳香族または脂肪族炭化水素基である。Ｘは、下記式（１）で表される化合物である。）

(In the formula (I), R ¹ is a hydroxyl group, an R ⁴ O group, an R ⁴ COO group, an R ⁴ NHCOO group, an R ⁴ SO ₂ NHCOO group or an R ⁴ OCOO group, and R ² is a group having 1 to And R ³ is a hydrogen atom or an alkyl group, R ⁴ is an aromatic or aliphatic hydrocarbon group which may have a substituent, and X is represented by the following formula (1): It is a compound represented by.)

That is, the present invention provides a cationic polymerization initiator represented by the formula (I). Moreover, this invention provides the thermosetting epoxy resin composition containing the cationic polymerization initiator represented by Formula (I), and the monomer or polymer which has an epoxy group.

According to the present invention, an epoxy resin composition having excellent curability can be obtained.

Hereinafter, the cationic polymerization initiator and thermosetting epoxy resin composition of the present invention will be described in detail.
The cationic polymerization initiator of the present invention is represented by the general formula (I). Hereinafter, this cationic polymerization initiator is also referred to as cationic polymerization initiator 1.

(Cationic polymerization initiator 1)
In the formula (I), R ¹ is a hydroxyl group, an R ⁴ O group, an R ⁴ COO group, an R ⁴ NHCOO group, an R ⁴ SO ₂ NHCOO group or an R ⁴ OCOO group. R ⁴ is an aromatic or aliphatic hydrocarbon group which may have a substituent.

Examples of the aromatic hydrocarbon group include an aryl group, an aralkyl group, and an arylene group. Examples of the aryl group include those having 6 to 14 carbon atoms, preferably 6 to 10 carbon atoms. Examples thereof include a phenyl group, a naphthyl group, an anthryl group, a phenanthryl group, and a biphenyl group. Of these, a phenyl group is preferably used.
Examples of the aralkyl group include those having 7 to 13 carbon atoms, preferably 7 to 11 carbon atoms. For example, benzyl group, phenethyl group, phenylpropyl group and the like can be mentioned. Of these, a benzyl group is preferably used.
Examples of the arylene group include those having 6 to 14 carbon atoms, preferably 6 to 10 carbon atoms. Examples thereof include a phenylene group, a naphthylene group, an anthrylene group, a phenanthrylene group, and a biphenylene group. Of these, a phenylene group is preferably used. The arylene group constitutes R ⁴ by bonding with a monovalent group such as an aryl group or an aralkyl group.

The aromatic hydrocarbon group further has at least one substituent such as a lower alkyl group having 1 to 4 carbon atoms, a hydroxyl group, an amino group, a nitro group, or a halogen atom at an arbitrary carbon atom position. Also good. Examples of the aromatic hydrocarbon group having a substituent include an aryl group having a substituent such as a tolyl group, a xylyl group, and a phenoxy group; and a substituent such as a methylbenzyl group, an ethylbenzyl group, and a methylphenethyl group. An arylene group having an aralkyl group; a substituent such as a methylphenylene group, a dimethylphenylene group, or a methylnaphthylene group; Of these, a phenoxy group is preferably used.

Examples of the aliphatic hydrocarbon group include an alkyl group, a cycloalkyl group, an alkenyl group, an alkenylene group, and an alkoxy group. Examples of the alkyl group include linear or branched ones having 1 to 18 carbon atoms, preferably 1 to 6 carbon atoms. Examples include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, and a tert-butyl group. Of these, a methyl group is preferably used.
Examples of the cycloalkyl group include those having 3 to 10 carbon atoms, preferably 3 to 6 carbon atoms. Examples thereof include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, and a cyclohexyl group.
Examples of the alkenyl group include linear or branched groups having 2 to 18 carbon atoms, preferably 2 to 6 carbon atoms. Examples thereof include a vinyl group, 1-propenyl group, allyl group, isopropenyl group, 1-butenyl group and 2-butenyl group.
Examples of the alkenylene group include straight-chain or branched groups having 2 to 18 carbon atoms, preferably 2 to 6 carbon atoms. For example, vinylene group, propenylene group, butadienylene group can be mentioned. The alkenylene group constitutes R ⁴ by bonding with a monovalent group such as an alkyl group or a cycloalkyl group.
Examples of the alkoxy group include linear or branched groups having 1 to 18 carbon atoms, preferably 1 to 6 carbon atoms. Examples thereof include a methoxy group, an ethoxy group, an n-propoxy group, an isopropoxy group, an n-butoxy group, a sec-butoxy group, and a tert-butoxy group. Of these, a methoxy group is preferably used.

In the R ⁴ O group, preferred R ⁴ includes a methyl group, a methoxy group, a phenyl group, and a phenoxy group, and among them, a methyl group is more preferably used.
In the R ⁴ COO group, preferred R ⁴ includes a methyl group, a benzyl group, and a phenyl group, and among them, a methoxy group is more preferably used.
In the R ⁴ NHCOO group, preferred R ⁴ includes a methyl group, a methoxy group, a phenyl group, a phenoxy group, and a phenylene group, and among them, a phenyl group is more preferably used.
In the R ⁴ SO ₂ NHCOO group, preferred examples of R ⁴ include a methyl group, a methoxy group, a phenyl group, a phenoxy group, a phenylene group, and a tolyl group. Among them, a tolyl group is more preferred, and a p-tolyl group is more preferred. Used.
In the R ⁴ OCOO group, preferred R ⁴ includes a methyl group, a phenyl group, and a phenylene group, and among them, a phenyl group is more preferably used.

Among R ⁴ O group, R ⁴ COO group, R ⁴ NHCOO group, R ⁴ SO ₂ NHCOO group and R ⁴ OCOO group, R ⁴ COO group, R ⁴ NHCOO group, R ⁴ SO ₂ NHCOO group and R ⁴ OCOO group Is preferably used in that it has an electron-withdrawing group, so that the cationic property of the sulfonium ion is increased and the curability is excellent. In particular, the higher the electron-withdrawing property of the electron-withdrawing group, the better the curability and the more preferable it is used.
From the viewpoint of excellent curability, R ¹ is preferably a hydroxyl group, an R ⁴ COO group, an R ⁴ NHCOO group, an R ⁴ SO ₂ NHCOO group, or an R ⁴ OCOO group, and more preferably a hydroxyl group.
The arrangement of R ¹ may be any of ortho-position, meta-position, and para-position with respect to the sulfonium ion, and is preferably para-position from the viewpoint of excellent curability.

R ² is an alkyl group having 1 to 6 carbon atoms, preferably 1 to 3 carbon atoms. Examples include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, and a tert-butyl group. Of these, a methyl group is preferably used.

R ³ is a hydrogen atom or an alkyl group. The alkyl group is the same as the alkyl group described above for R ⁴ . As R ³ , a hydrogen atom is preferably used from the viewpoint of excellent curability. The arrangement of R ³ may be any of the ortho, meta, and para positions relative to the vinylene group, and is preferably the ortho or para position from the viewpoint of excellent curability.
X is a compound represented by Formula (1).

Specific examples of the cationic polymerization initiator 1 represented by the formula (I) include a compound represented by the following formula (Ia).

　カチオン重合開始剤１は、それぞれ、単独でまたは２種以上を組み合わせて用いることができる。

Each of the cationic polymerization initiators 1 can be used alone or in combination of two or more.

The production of the cationic polymerization initiator 1 is not particularly limited. For example, it can be obtained by reacting 4-methylthiophenol and cinnamilk chloride to obtain a chloride intermediate, and further mixing and reacting the chloride intermediate and an aqueous sodium salt solution of tetrakis (pentafluorophenyl) borate.

The thermosetting epoxy resin composition of the present invention contains a cationic polymerization initiator 1 and a monomer or polymer having an epoxy group.
(Monomer having an epoxy group)
The monomer having an epoxy group is not particularly limited, and examples thereof include monofunctional glycidyl ethers, polyfunctional aliphatic glycidyl ethers, polyfunctional aromatic glycidyl ethers, glycidyl esters, and alicyclic epoxy compounds. .

Examples of monofunctional glycidyl ethers include allyl glycidyl ether, butyl glycidyl ether, phenyl glycidyl ether, 2-ethylhexyl glycidyl ether, sec-butylphenyl glycidyl ether, tert-butylphenyl glycidyl ether, and 2-methyloctyl glycidyl ether. Can be mentioned.

Examples of the polyfunctional aliphatic glycidyl ethers include 1,6-hexanediol glycidyl ether, trimethylolpropane triglycidyl ether, neopentyl glycol diglycidyl ether, glycerol diglycidyl ether, glycerol triglycidyl ether, and ethylene glycol diglycidyl ether. Polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, and the like.

Examples of the polyfunctional aromatic glycidyl ethers include bisphenol A glycidyl ether, bisphenol F glycidyl ether, brominated bisphenol A glycidyl ether, biphenol glycidyl ether, tetramethylbiphenol glycidyl ether, resorching glycidyl ether, hydroquinone glycidyl ether, and dihydroxynaphthalene glycidyl ether. Examples include ether, bisphenol novolac resin glycidyl ether, phenol novolac resin glycidyl ether, cresol novolac resin glycidyl ether, dicyclopentadiene phenol resin glycidyl ether, terpene phenol resin glycidyl ether, and naphthol novolac resin glycidyl ether.

Examples of the glycidyl esters include glycidyl acrylate, glycidyl methacrylate, diglycidyl phthalate, diglycidyl hexahydrophthalate, diglycidyl tetrahydrophthalate, dimethyldiglycidyl hexahydrophthalate, and the like.

Examples of the alicyclic epoxy compound include 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, 3,4-epoxycyclohexylethyl-3,4-epoxycyclohexanecarboxylate, vinylcyclohexene dioxide, allyl Cyclohexene dioxide, 3,4-epoxy-4-methylcyclohexyl-2-propylene oxide, 2- (3,4-epoxycyclohexyl-5,5-spiro-3,4-epoxy) cyclohexane-m-dioxane, bis ( 3,4-epoxycyclohexyl) adipate, bis (3,4-epoxycyclohexylmethyl) adipate, bis (3,4-epoxycyclohexyl) ether, bis (3,4-epoxycyclohexylmethyl) ether, bis (3,4 Epoxycyclohexyl) diethyl siloxane, and the like.
The monomer which has an epoxy group can be used individually or in mixture of 2 or more types.

(Polymer having epoxy group)
The polymer having an epoxy group is not particularly limited as long as it has two or more epoxy groups. For example, bisphenol A type epoxy resin, dicyclopentadiene type epoxy resin, diaminodiphenylmethane type epoxy resin, aminophenol type epoxy resin, Naphthalene type epoxy resins, phenol novolac type epoxy resins, biphenyl type epoxy resins, hydrogenated biphenol type epoxy resins, and alicyclic epoxy resins are used.
The polymer which has an epoxy group can be used individually or in combination of 2 or more types, respectively.

The blending amount of the cationic polymerization initiator 1 is 0.1% with respect to 100 parts by weight of the monomer or polymer having all epoxy groups from the viewpoint of sufficiently exhibiting quick curability and having a high glass transition point of the cured product. It is preferably ˜10 parts by weight, more preferably 0.1 to 5 parts by weight.

(Cationic polymerization initiator 2)
The epoxy resin composition of the present invention may further contain a cationic polymerization initiator represented by the following general formula (II) (hereinafter also referred to as cationic polymerization initiator 2). Since a cured product having a high glass transition point is obtained without impairing curability, the cationic polymerization initiator 2 can be appropriately blended with the cationic polymerization initiator 1 depending on its use.

In the formula (II), R ⁵ is a hydroxyl group, an R ⁴ O group, an R ⁴ COO group, an R ⁴ NHCOO group, an R ⁴ SO ₂ NHCOO group or an R ⁴ OCOO group, and the R of the cationic polymerization initiator 1 described above ^Same as ¹ .
R ⁶ is a hydrogen atom or an alkyl group. The alkyl group is the same as the alkyl group described above for R ⁴ of the cationic polymerization initiator 1 described above. As R ⁶ , a hydrogen atom is preferably used from the viewpoint of excellent curability. The arrangement of R ⁶ may be any of the ortho, meta, and para positions with respect to the methylene group, and is preferably the ortho or para position from the viewpoint of excellent curability.
X is a compound represented by the following formula (2).

Specific examples of the cationic polymerization initiator 2 represented by the formula (II) include, for example, a compound represented by the following formula (IIa).

　カチオン重合開始剤２は、それぞれ、単独でまたは２種以上を組み合わせて用いることができる。

The cationic polymerization initiators 2 can be used alone or in combination of two or more.

The production of the cationic polymerization initiator 2 is not particularly limited. For example, it can be obtained according to a conventionally known method (for example, see Reference Example 3 in Japanese Patent Publication No. 2008-308596). Some cationic polymerization initiators 2 can be obtained as commercial products.
The amount of the cationic polymerization initiator 2 is 0 for 100 parts by weight of the monomer or polymer having all the epoxy groups from the viewpoint of sufficiently increasing the glass transition point of the cured product when used in the application of an adhesive for electronic materials. The amount is preferably 1 to 10 parts by weight, more preferably 0.1 to 5 parts by weight.
The blending ratio of the cationic polymerization initiator 1 to the cationic polymerization initiator 2 is, when used in the application of an adhesive for electronic materials, from the viewpoint of obtaining a cured product having sufficiently high curability and a sufficiently high glass transition point. The ratio is preferably a value in the range of 0.1 to 10, more preferably a value in the range of 0.2 to 5.

The epoxy resin composition of the present invention may further contain other conventionally known cationic polymerization initiators in addition to the cationic polymerization initiator 1 or the cationic polymerization initiator 1 and the cationic polymerization initiator 2 as a curing agent. . In addition to the epoxy resin and the cationic polymerization initiator, the epoxy resin composition of the present invention may further contain a conventionally known curing accelerator such as a Lewis acid as long as the effects of the invention are not impaired.

Moreover, the epoxy resin composition of the present invention may further contain additives as necessary in addition to the above-described components. Examples of additives include fillers (fillers), silane coupling agents, reactive diluents, plasticizers, thixotropic agents, pigments, dyes, anti-aging agents, antioxidants, antistatic agents, flame retardants, Adhesiveness imparting agents, dispersants, and solvents can be mentioned. Examples of the filler include silica and mica.

The composition of the present invention is not particularly limited for its production. For example, the above-described monomer or polymer having an epoxy group, a cationic polymerization initiator and a curing accelerator added as necessary, and each component of the additive are used under a reduced pressure or in a nitrogen atmosphere using a stirring device such as a mixing mixer. By sufficiently kneading and uniformly dispersing, a one-pack type epoxy resin composition can be obtained.

The composition of the present invention can be used, for example, for adhesives, paints, civil engineering and construction, electricity, transportation equipment, medical use, packaging use, textile use, and sports / leisure use. The composition of the present invention has excellent curability, improved productivity, and a circuit pattern formed by processing an electronic material (for example, a metal thin film) from the viewpoint of obtaining a high quality product having excellent physical properties. It is preferably used for adhesives used by applying to the surface of various display devices on the substrate. Among these, it is more preferably used as a composition of ACF (anisotropic conductive film).

The temperature at which the composition of the present invention is cured is superior in curability and has a higher glass transition point of the cured product. For example, ADEKA's bisphenol A type epoxy resin EP4100E is used as a polymer having an epoxy group. If it is, it is preferably 100 to 250 ° C, more preferably 120 to 200 ° C.
In this invention, sclerosis | hardenability is evaluated by the gelation time (gel time) of an epoxy resin composition, and is specifically measured by the method of using the Yasuda-type gel time tester mentioned later. The gelation time of the composition of the present invention is, for example, less than 30 seconds at 150 ° C., preferably less than 20 seconds when bisphenol A type epoxy resin EP4100E manufactured by ADEKA is used as the polymer having an epoxy group.
Moreover, in this invention, a glass transition point is specifically evaluated by measuring a storage elastic modulus about hardened | cured material so that it may mention later. The glass transition point of the cured product obtained by curing the composition of the present invention preferably exceeds 80 ° C., more preferably, when ADEKA bisphenol A type epoxy resin EP4100E is used as the polymer having an epoxy group. Exceeds 100 ° C.

Hereinafter, the present invention will be specifically described with reference to examples.
(Manufacture of epoxy resin composition)
As Examples 1 to 8, Comparative Examples 1 to 4, and Reference Examples, the components shown in Tables 1 and 2 below were mixed in the mixing ratios shown in the same table to produce epoxy resin compositions. The numerical value of each component in the table is expressed in parts by weight.

Details of each component shown in Tables 1 and 2 are as follows.
・ Epoxy resin: Bisphenol A type epoxy resin (trade name EP4100E, manufactured by ADEKA)
Curing agent (1): cationic polymerization initiator represented by formula (Ia) Curing agent (1) was prepared as follows. 4.59 g of 4-methylthiophenol and 5 g of cinnamilk chloride were reacted in a 1: 1 mixed solvent of methanol and methylcyclohexane at room temperature for 24 hours to obtain a chloride intermediate. Further, 9 g of the intermediate and 215.8 g of a tetrakis (pentafluorophenyl) borate sodium salt aqueous solution (solid content 10%) were mixed and reacted at room temperature for 24 hours to obtain a compound. As a result of ¹ H-NMR analysis, this compound was confirmed to be a curing agent (1).
Curing agent (2): cationic polymerization initiator represented by formula (IIa) Curing agent (2) was prepared as follows. 10 g of benzyl chloride and 11.07 g of 4-methylthiophenol were reacted in methanol at room temperature for 24 hours to obtain a chloride intermediate. Further, 10 g of the intermediate and 263 g of tetrakis (pentafluorophenyl) borate sodium salt aqueous solution (solid content 10%) were mixed to obtain a curing agent (2).
Curing agent (3): cationic polymerization initiator represented by the following formula

　硬化剤（１）２gを乾燥したγブチロラクトン２．４gに溶解させ、その溶液中にp-トルエンスルホニルイソシアネート０．４gを添加し、蒸留水中に沈殿させ、硬化剤（３）を得た。

2 g of curing agent (1) was dissolved in 2.4 g of dried γ-butyrolactone, 0.4 g of p-toluenesulfonyl isocyanate was added to the solution, and precipitated in distilled water to obtain curing agent (3).

　硬化剤（４）は次のようにして調製した。４－メチルチオフェノール４．５９ｇとシンナミルクロリド５ｇをメタノールとメチルシクロヘキサンの１：１混合溶媒中で室温で２４時間反応させ、クロライド中間体を得た。さらに中間体１０ｇとＮａＳｂＦ_６　８．８４ｇを混合し、硬化剤（４）を得た。
・　硬化剤（５）：下記式で表されるカチオン重合開始剤 Curing agent (4): cationic polymerization initiator represented by the following formula

The curing agent (4) was prepared as follows. 4.59 g of 4-methylthiophenol and 5 g of cinnamilk chloride were reacted in a 1: 1 mixed solvent of methanol and methylcyclohexane at room temperature for 24 hours to obtain a chloride intermediate. Further, 10 g of the intermediate and 8.84 g of NaSbF ₆ were mixed to obtain a curing agent (4).
Curing agent (5): cationic polymerization initiator represented by the following formula

　硬化剤（５）は次のようにして調製した。４－メチルチオフェノール４．５９ｇとシンナミルクロリド５ｇをメタノールとメチルシクロヘキサンの１：１混合溶媒中で室温で２４時間反応させ、クロライド中間体を得た。さらに中間体１０ｇとＮａＢＦ_４　３．７５ｇを混合し、硬化剤（５）を得た。

The curing agent (5) was prepared as follows. 4.59 g of 4-methylthiophenol and 5 g of cinnamilk chloride were reacted in a 1: 1 mixed solvent of methanol and methylcyclohexane at room temperature for 24 hours to obtain a chloride intermediate. Further, 10 g of the intermediate and 3.75 g of NaBF ₄ were mixed to obtain a curing agent (5).

Curing agent (6): cationic polymerization initiator represented by the following formula

　硬化剤（６）は次のようにして調製した。４－メチルチオフェノール４．５９ｇとシンナミルクロリド５ｇをメタノールとメチルシクロヘキサンの１：１混合溶媒中で室温で２４時間反応させ、クロライド中間体を得た。さらに中間体１０ｇとＮａＰＦ_６　５．７３ｇを混合し、硬化剤（６）を得た。
・　硬化剤（７）：下記式で表されるカチオン重合開始剤

The curing agent (6) was prepared as follows. 4.59 g of 4-methylthiophenol and 5 g of cinnamilk chloride were reacted in a 1: 1 mixed solvent of methanol and methylcyclohexane at room temperature for 24 hours to obtain a chloride intermediate. Further mixing the intermediate 10g and NaPF ₆ 5.73 g, was obtained curing agent (6).
Curing agent (7): cationic polymerization initiator represented by the following formula

　硬化剤（７）は次のようにして調製した。１－（クロロメチル）ナフタレン１０ｇと４－メチルチオフェノール７．９ｇをメタノール中で室温２４時間反応させ、クロライド中間体を得た。さらに中間体１０ｇとテトラキス（ペンタフルオロフェニル）ボレートのナトリウム塩水溶液（固形分１０％）２２０．１６ｇを混合し、硬化剤（７）を得た。

The curing agent (7) was prepared as follows. 10 g of 1- (chloromethyl) naphthalene and 7.9 g of 4-methylthiophenol were reacted in methanol at room temperature for 24 hours to obtain a chloride intermediate. Further, 10 g of the intermediate and 220.16 g of an aqueous sodium salt solution of tetrakis (pentafluorophenyl) borate (solid content 10%) were mixed to obtain a curing agent (7).

(Evaluation)
About each obtained epoxy resin composition, the gel time and the storage elastic modulus were measured with the following method, respectively, and sclerosis | hardenability and a glass transition point were evaluated. The results are shown in Tables 1 and 2.
(1) Gel time About each obtained composition, the gel time in 150 degreeC was measured using the Yasuda-type gel time tester (The Yasuda Seiki Seisakusho make, No.153 gel time tester). The Yasuda-type gel time tester is a device that rotates a rotor in a test tube containing a sample in an oil bath, and when the gelation proceeds and a certain torque is applied, the rotor is dropped by a magnetic coupling mechanism and the timer is stopped.
(2) Storage elastic modulus Each of the obtained compositions was cured in an oven at 150 ° C for 1 hour. For each cured product, dynamic viscoelasticity measurement (Dynamic Mechanical Analysis) was performed at a strain of 0.01%, a frequency of 10 Hz, and a heating rate of 5 ° C./min in a temperature range from room temperature to 200 ° C. And the storage modulus was measured. The peak value of tan δ was defined as the glass transition point Tg of each composition.

As is apparent from the results shown in Tables 1 and 2, the epoxy resin compositions (Comparative Examples 1 to 4) that do not contain the cationic polymerization initiator 1 as the curing agent have a gel time of 30 seconds or more and are cured. The nature was bad.
Among these, the epoxy resin composition (Comparative Example 4) containing no cationic polymerization initiator 1 and no cationic polymerization initiator 2 as a curing agent had a glass transition point of the cured product exceeding 100 ° C. The gelation time was 30 seconds or more and the curability was poor.
In addition, the epoxy resin composition (reference example) which does not contain the cationic polymerization initiator 1 as a curing agent and contains the curing agent (7) had a gelation time of less than 30 seconds, but it was a cured glass. The transition point was 80 ° C. or lower. For this reason, it is thought that the epoxy resin composition of a reference example is not suitable for use as an adhesive for electronic materials.

In contrast, the epoxy resin compositions (Examples 1 to 8) containing the cationic polymerization initiator 1 as a curing agent had a gelation time of less than 30 seconds and were confirmed to have excellent curability. .
Among these, the epoxy resin compositions (Examples 4 to 7) containing both the cationic polymerization initiator 1 and the cationic polymerization initiator 2 as curing agents have a gelation time of less than 30 seconds and are excellent in curability. At the same time, the glass transition point of the cured product exceeded 100 ° C. Therefore, the epoxy resin compositions of Examples 4 to 7 are considered to be particularly suitable for use as an adhesive for electronic materials.

Claims (5)

Cationic polymerization initiator represented by the following general formula (I).

(In the formula (I), R ¹ is a hydroxyl group, an R ⁴ O group, an R ⁴ COO group, an R ⁴ NHCOO group, an R ⁴ SO ₂ NHCOO group or an R ⁴ OCOO group, and R ² is a group having 1 to And R ³ is a hydrogen atom or an alkyl group, R ⁴ is an aromatic or aliphatic hydrocarbon group which may have a substituent, and X is represented by the following formula (1): It is a compound represented by.)

A thermosetting epoxy resin composition comprising the cationic polymerization initiator according to claim 1 and a monomer or polymer having an epoxy group. The thermosetting epoxy resin according to claim 2, wherein the cationic polymerization initiator represented by the general formula (I) is contained in an amount of 0.1 to 10 parts by weight with respect to 100 parts by weight of the monomer or polymer having an epoxy group. Composition. The thermosetting epoxy resin composition according to claim 2 or 3, further comprising a cationic polymerization initiator represented by the following general formula (II).

(In the formula (II), R ⁵ is a hydroxyl group, an R ⁴ O group, an R ⁴ COO group, an R ⁴ NHCOO group, an R ⁴ SO ₂ NHCOO group or an R ⁴ OCOO group, and R ⁶ is a hydrogen atom or an alkyl group. R ⁴ is an aromatic or aliphatic hydrocarbon group which may have a substituent, and X is a compound represented by the following formula (2).

The thermosetting epoxy resin composition according to claim 4, comprising 0.1 to 10 parts by weight of the cationic polymerization initiator represented by the general formula (II) with respect to 100 parts by weight of the monomer or polymer.