JPS6312095B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to thermosetting epoxy resin compositions. More specifically, the present invention relates to a thermosetting resin composition with excellent latent properties that allows epoxy resin to be polymerized in a short period of time to obtain a good cured product. Many catalysts for cationic polymerization of epoxy resins are known, including inorganic acids, Lewis acids, organic acids, and certain alkylating agents. An ideal epoxy resin catalyst would have good storage stability at room temperature and would cure in a short time, specifically within a few minutes, when heated, but to date, no satisfactory curing catalyst is known. First, in many cases, it was necessary to use a two-component method or to cure by heating at high temperatures for a long time. Furthermore, amine-BF ₃ complexes (for example, monoethylamine-BF ₃ ), which are well known as latent curing catalysts, start curing by heating, but in order to obtain a cured product with sufficient physical properties, it is necessary to
It is necessary to keep it for 8 hours. Also amine-BF ₃
Complexes are generally highly hygroscopic and difficult to handle, and the resulting cured product has poor water resistance and chemical resistance. Furthermore, if sufficient care is not taken during curing, the surface of the cured product will wrinkle. As a solution to these drawbacks of the amine-BF ₃ complex, WEWhite's U.S. patent no.
No. 3,565,861 describes an amine-PF ₅ complex, but similarly the curability at high temperatures cannot be said to be sufficient. Taking these current circumstances into consideration, the present inventors have developed a wide range of cationic polymerization catalysts that have a satisfactory pot life and high temperature curability, are non-hygroscopic, and have good water and chemical resistance for cured products. As a result, we found that the protonic acids have at least one electron-withdrawing group at the α- or β-position relative to the sulfur atom, and have corresponding protic acids such as PF ^- ₆ , AsF ^- ₆ , and SbF ^- ₆ in the anion moiety. discovered that a specific aliphatic or alicyclic sulfonium salt having a very strong acid and a non-nucleophilic ion could serve as a good latent cationic polymerization catalyst for epoxy resin, and completed the present invention. . By the way, aromatic, aliphatic or alicyclic sulfonium salts are known as curing accelerators with excellent latent properties in systems consisting of a combination of an epoxy resin and an acid anhydride curing agent or a dicyandiamide curing agent. However, in such a case, it is preferable to use a sulfonium salt having a nucleophilic anion such as Cl ^- , Br ^- , or carboxylate as the anion moiety, and do not use a curing agent such as an acid anhydride or dicyandiamide. Epoxy resins cannot be cured if only sulfonium salts and sulfonium salts are used. Sulfonium salts can be roughly divided into aromatic sulfonium salts and aliphatic or alicyclic sulfonium salts, but aromatic sulfonium salts generally have poor catalytic ability; for example, triphenylsulfonium salts contain PF ^- ₆ , AsF in the anion moiety. ^- No curing is observed even when heated with epoxy resin at 150°C to 200°C for about 1 hour using anion such as ₆ . On the other hand, unsubstituted alkylsulfonium salts have slightly higher activity than aromatic sulfonium salts, but still require a high temperature of 150°C or higher for curing. However, as in the present invention, α for the sulfur atom
Introducing an electron-withdrawing functional group into the position or β-position further increases the activity and provides an epoxy resin composition with a long pot life in a one-part state at room temperature. The thermosetting epoxy resin composition of the present invention comprises (1) an epoxy resin, (2) the general formula [] (In the formula, R ₁ and R ₂ are the same or different substituted or unsubstituted aliphatic or alicyclic groups, and R ₁ and R ₂ may form a ring, and there may be unsaturated bonds or alkoxy group, nitro group, halogen group, hydroxyl group, carboxyl group, ester group, ether group, cyano group,
It can contain functional groups such as carbonyl groups, sulfone groups, and thioether groups. A is an aliphatic group represented by the general formula [] or [] Here, R ₃ to _{R 6} are groups selected from hydrogen atoms, substituted or unsubstituted aliphatic groups, and R ₃ and R ₄ or R ₅ and R ₆
may be the same or different. X is an electron-withdrawing functional group. Also, MQm ^- is a non-nucleophilic anion, and M is B, P, Sb, As, Fe, Al, Sn, Zn, Ti or Cd
Q is a halogen atom, m is 1
~6 numbers. ) contains a sulfonium salt represented by: The epoxy resin (1) used in the present invention is a conventionally known aromatic epoxy resin, alicyclic epoxy resin,
Examples include aliphatic epoxy resins. Particularly preferred aromatic epoxy resins are polyglycidyl ethers of polyhydric phenols having at least one aromatic nucleus or their alkylene oxide adducts, such as bisphenol A or its alkylene oxide adducts and epichlorohydrin. Examples include glycidyl ether and epoxy novolac resin produced by reaction with Particularly preferable alicyclic epoxy resins include polyglycidyl ethers of polyhydric alcohols having at least one alicyclic ring, or compounds containing cyclohexene or cyclopentene rings, which are epoxidized with an appropriate oxidizing agent such as hydrogen peroxide or peracid. There are cyclohexene oxide- or cyclopentene oxide-containing compounds obtained by. Typical examples of polyglycidyl ethers include:
Examples include glycidyl ether produced by reacting hydrogenated bisphenol A or its alkylene oxide adduct with epichlorohydrin. Particularly preferable aliphatic epoxy resins include polyglycidyl ethers of aliphatic polyhydric alcohols or their alkylene oxide adducts; typical examples include diglycidyl ether of 1,6-hexanediol and triglycidyl ether of glycerin. , diglycidyl ether of polyethylene glycol, diglycidyl ether of polypropylene glycol, addition of one or more alkylene oxides (ethylene oxide, propylene oxide) to aliphatic polyhydric alcohols such as ethylene glycol, propylene glycol, and glycerin. Examples include polyglycidyl ethers of polyether polyols obtained by. Furthermore, monoglycidyl ethers of aliphatic higher alcohols, phenols, cresols, or monoglycidyl ethers of polyether alcohols obtained by adding alkylene oxide to these may also be blended as diluents. As the epoxy resin of the present invention, these aromatic epoxy resins, alicyclic epoxy resins, or aliphatic epoxy resins can be used alone, but
It is desirable to mix them appropriately depending on the desired performance. Further, the epoxy resin of the present invention may be used in combination with other cationically polymerizable organic substances, episulfide resins, cyclic ethers, lactones, vinyl ethers, phenol/formaldehyde resins, etc. The sulfonium salt (2) of the present invention is composed of one or more cationic sulfur atoms, a cation having an electron-withdrawing functional group at the alpha or beta position relative to the sulfur atom, and a non-nucleophilic anion. configured. Preferred examples of the sulfonium salt (2) are sulfonium salts represented by the following general formula []. Here, R ₁ and R ₂ are the same or different substituted or unsubstituted aliphatic or alicyclic groups, and R ₁ and R ₂ may form a ring, and there may be an unsaturated bond or an alkoxy group in the group. , nitro group, halogen group, hydroxyl group, carboxyl group, ester group, ether group, cyano group,
It can contain functional groups such as carbonyl groups, sulfone groups, and thioether groups. A is an aliphatic group having an electron-withdrawing functional group at the α-position or β-position with respect to the sulfur atom, and is preferably represented by the general formula [] or []. Here, R ₃ to _{R 6} are groups selected from hydrogen atoms, substituted or unsubstituted aliphatic groups, and R ₃ and R ₄ or R ₅ and R ₆
may be the same or different. X is an electron-withdrawing functional group. Here, the term "electron-withdrawing functional group" refers to a group that exerts an attractive effect on electrons of adjacent carbon atoms, and such groups include nitro groups, cyano groups, alkenyl groups, alkynyl groups, carboxyl groups, and carbonyl groups. group, hydroxyl group, ester group, sulfone group, halogen group, etc. Also, MQm ^- is a non-nucleophilic anion, and M is B, P, Sb, As, Fe, Al, Sn, Zn, Ti or Cd
Atoms selected from B, P, As or Sb are preferred. Q is a halogen atom, and m is a number from 1 to 6.
Preferred MQ ^- _n are BF ^- ₄ , PF ^- ₆ ,
Examples include AsF ^- ₆ and SbF ^- ₆ . Preferred compounds as the sulfonium salt include those shown below. CH ₃ −S ⁺ (−CH ₂ CO ₂ CH ₃ ) ₂・AsF ⁻ ₆ CH ₃ −S ⁺ (−
CH ₂ CH ₂ CO ₂ C ₁₂ H ₂₃ ) ₂・PF ^- ₆ (HOCH ₂ CH ₂ ―) ₂ S ⁺ ―CH ₂ CN・AsF ^- ₆
(H ₅ C ₂ O ₂ CCH ₂ ―) ₂ S ⁺ ―CH ₂ ―C≡C―CH ₂ ―S ⁺
(CH ₂ CO ₂ C ₂ H ₅ ) ₂・2AsF ^- ₆ (ClCH ₂ ―CH ₂ ―) ₃ S ⁺・
AsF ^- ₆ (CH ₃ -) ₂ S ⁺ - CH ₂ SO ₂ C ₂ H ₅・PF ^- ₆
(CH ₃ COCH ₂ −) ₂ S ⁺ ―CH ₃・SbF ^- ₆ etc. can be mentioned. The thermosetting epoxy resin composition of the present invention contains a special sulfonium salt per 100 parts by weight of the epoxy resin (1).
(2) is preferably used in an amount of 0.1 to 15 parts by weight, more preferably 0.5 to 10 parts by weight. Such compositions generally have a viscosity of 1 to 1 at 25°C.
1000000 centipoise liquid or powder or solid state that is fluid at high temperatures, but at 50℃
By heating to 250° C., a curing reaction occurs within 30 minutes, and a non-tacky cured product can be obtained. The composition of the present invention may further contain a solvent for dilution and a non-reactive resin or prepolymer for modification within a range that does not impair cationic polymerization. In addition, for example, organic carboxylic acids and acid anhydrides may be used for the purpose of improving electrical properties, etc.
Alternatively, a polyol may be mixed for the purpose of imparting rubber elasticity. The compositions of the present invention may further include pigments, dyes, extenders,
It can also be used in combination with flame retardants, antistatic agents, antigelation agents, adhesion improvers, flow control agents, surfactants, etc. Although the amount of these additives is determined by the balance between functionality and curability, these compositions can be used in metal, wood, rubber, plastics, glass, ceramic products, etc. Specific applications of the present invention include, for example, protection and
Mention may be made of gloss varnishes, inks, adhesives, insulating materials, molding materials, casting materials, glass fiber impregnated tapes, etc. The curing catalyst of the present invention has a long pot life at room temperature, is cured in a short time by heating, has excellent high temperature curing properties, is not hygroscopic, and has excellent water resistance and chemical resistance of the cured product. The effectiveness of the present invention will be explained in more detail with reference to Examples below, but the present invention is not limited to the following Examples unless the gist thereof is exceeded. Example 1 A blend consisting of 100 parts by weight of ERL-4221 (cycloaliphatic epoxy resin; manufactured by Union Carbide) and 3.0 parts by weight of various sulfonium salts was prepared, and 15 mg of each was prepared.
was placed on an aluminum pan, and heated from room temperature at a rate of 5° C. per minute using a differential thermal balance manufactured by Rigaku Denki Co., Ltd. to obtain a differential thermal curve. The peak temperature of this curve was defined as the curing temperature and is summarized in Table 1.

【table】

[Table] All of the above formulations are at room temperature (25℃)
No significant thickening was observed even after leaving it for one month. Example 2 Approximately 1 g of a mixture consisting of 100 parts by weight of ERL-4221 and 3 parts by weight of bis(carbomethoxymethyl)methylsulfonium hexafluoroarsenate was placed in a glass screw and heated in an oil bath at 145°C for approximately 1 minute and 30 seconds. It was cured and a strong solid product was obtained. The sulfonium salt of the present invention generally has good curability, and when cured near the curing temperature shown in Table 1 of Example 1, a strong solid product can be obtained within several minutes. Example 3 To an epoxy resin mixture consisting of 66 parts by weight of ERL-4221 and 33 parts by weight of EPPN-201 (epoxidized phenol novolac manufactured by Nippon Kayaku), 3 parts by weight of (A) carboethoxymethyltetramethylenesulfonium hexafluoroarsenate was added. (B) and 3 parts by weight of ethylamine-BF ₃ complex were prepared and poured between two glass plates with a gap of 6 mm. (A) was heated at 140°C for 1 hour, and (B) was 2 at 60℃~100℃
After time curing, post-curing was further carried out at 150°C for 2 hours to produce a plate-shaped cured product with a thickness of 6 mm, and its physical properties were investigated. Although the hardness was almost the same, the cured product of (B) collapsed after being left in methyl ethyl kent for one week, while the weight of the cured product of (A) increased by only 0.05%. Also, the heat distortion temperature of (B) is 140℃, while that of (A) is 190℃.
It was warm at ℃. Furthermore, when the one-component stability at room temperature was investigated, the formulation (B) significantly thickened after being left at room temperature for 3 days, but the formulation (A)
The formulation showed almost no thickening even after being left for one month.

Claims (1)

[Claims] 1 (1) Epoxy resin; (2) General formula [] (In the formula, R ₁ and R ₂ are the same or different substituted or unsubstituted aliphatic or alicyclic groups, and R ₁ and R ₂ may form a ring, and unsaturated bonds in the group, alkoxy group, nitro group, halogen group, hydroxyl group, carboxyl group, ester group, ether group, cyano group,
It can contain functional groups such as carbonyl groups, sulfone groups, and thioether groups. A is an aliphatic group represented by the general formula [] or [] Here, R ₃ to _{R 6} are groups selected from hydrogen atoms, substituted or unsubstituted aliphatic groups, and R ₃ and R ₄ or R ₅ and R ₆
may be the same or different. X is an electron-withdrawing functional group. Also, MQm ^- is a non-nucleophilic anion, and M is B, P, Sb, As, Fe, Al, Sn, Zn, Ti or Cd
Q is a halogen atom, m is 1
~6 numbers. ) A thermosetting epoxy resin composition containing a sulfonium salt represented by: