JPH0237924B2 - NETSUKOKASEISOSEIBUTSU - Google Patents

Description

[Detailed description of the invention]

The present invention relates to thermosetting resin compositions. Specifically, the present invention relates to a thermosetting resin composition that polymerizes a cationically polymerizable organic substance such as an epoxy resin in a short period of time and has excellent retention properties in order to obtain a good cured product. Many catalysts for cationic polymerization of cationically polymerizable organic substances such as epoxy resins are known to date, including inorganic acids, Lewis acids, organic acids, and certain alkylating agents. An ideal 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. In many cases, it was necessary to use a two-component method or to cure by heating at high temperatures for long periods of time. Furthermore, amine-BF ₃ complexes (for example, monoethylamine-BF ₃ ), which are well known as retentive 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,
Moreover, the storage stability cannot be said to be sufficient. Furthermore, amine-BF ₃ complexes are generally highly hygroscopic and difficult to handle, and the resulting cured product has poor physical properties such as water resistance, chemical resistance, and electrical properties. 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-PE ₅ complex, but it cannot be said that the curability at high temperatures is sufficient. By the way, aromatic, aliphatic or alicyclic sulfonium salts are known as curing accelerators with excellent retention properties in systems consisting of a combination of epoxy resins and acid anhydride curing agents or dicyandiamide curing agents. 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 dicyanamide. Epoxy resins cannot be cured if only sulfonium salts and sulfonium salts are used. Furthermore, EF ₄ ^-salt , which is well known as a non-nucleophilic anion, can cure epoxy resins, unlike the above-mentioned anions, but it is used as an anion component of the special sulfonium salt of the present invention. In this case, it is not preferable for the purpose of the present invention from both the curability and the physical properties of the cured product. Sulfonium salts can be broadly classified into aromatic sulfonium salts and aliphatic or alicyclic sulfonium salts. Aromatic sulfonium salts generally have poor curing properties when heated; for example, triphenylsulfonium salts, which have moieties such as PF ₆ ^- , AsF ₆ ^- and SbF ₆ ^- in their anion moieties, must be cured at temperatures of 200°C or higher. I need. Therefore, as a method of utilizing such aromatic sulfonium salts as a curing catalyst for epoxy resin, (A) Japanese Patent Publication No. 14278/1987 describes a method of generating a Lewis acid catalyst using light energy, and another method (B ) JP-A-54-102394 describes a method for reducing the cationicity of sulfonium cations using a certain reducing agent to release Lewis acids; A method of combining a salt and an oxidizing agent is described. It goes without saying that when a sulfonium salt decomposes due to heat, the mechanism is different from when using radiant energy such as light energy, and the decomposition products are usually different, but for general photosensitive sulfonium catalysts, the decomposition product is only equivalent to light energy. It is possible to release a Lewis acid by applying thermal energy of . However, when used as a thermosetting resin,
At least the first stage of curing is preferably carried out at 150°C or lower, and sulfonium salts with strong photosensitivity tend to undergo gradual gelation even under light conditions in a normal atmosphere, shortening the pot life. . Furthermore, the method of using such an aromatic sulfonium salt together with a third substance in the methods (B) to (C) above not only shortens the pot life and may cause problems with foaming during curing, but also There is a possibility that the physical properties of the epoxy resin may be impaired. On the other hand, aliphatic sulfonium salts are relatively stable to light and sensitive to heat. However, simple sulfonium salts such as trimethylsulfonium salts require heating at 150° C. or higher during curing, and therefore cannot necessarily be said to be preferable. Taking these current circumstances into consideration, the present inventors have achieved satisfactory storage stability (for example, at room temperature for 6 months or more) and fast curing at high temperatures (for example, gelation time at 150°C within 5 minutes).
While conducting extensive research on cationic polymerization catalysts that are non-hygroscopic and have good physical properties such as water resistance, chemical resistance, and electrical properties of the cured product, we found that one of the aliphatic groups is at the α-position relative to the sulfur atom. has an aromatic group, and the anion part contains PF ₆ ^- , AsF ₆ ^- , SbF ₆ ^- , Sb
The present invention was completed based on the discovery that a sulfonium salt having (OH)F ₅ ^- can serve as a good residence cationic polymerization catalyst for cationically polymerizable organic substances. The thermosetting resin composition of the present invention includes (1) one or more cationically polymerizable organic substances selected from epoxy resins, episulfide resins, cyclic ethers, lactones, vinyl ethers, and phenol/formaldehyde resins as essential components; (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. A is α to the cationic sulfur atom. A hydrocarbon group having one monovalent aromatic group having 6 to 20 carbon atoms in position, X is
PF ₆ , AsF ₆ , SbF ₆ , Sb(OH)F ₅ ). Cationic polymerizable organic substance used in the present invention (1)
As the material, acid-polymerizable or acid-curable organic substances, especially epoxy resins, are preferably used. The epoxy resins used in the present invention include conventionally known aromatic epoxy resins, alicyclic epoxy resins, and aliphatic epoxy resins. Here, particularly preferable aromatic epoxy resins are polyglycidyl ethers of polyvalent phenols having at least one aromatic nucleus or their alkylene oxide adducts, such as bisphenol A or its alkylene oxide adducts. Examples include glycidyl ether and epoxy novolac resin produced by reaction with epichlorohydrin. 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 polydiglycidyl 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. As such an epoxy resin, one having an epoxy equivalent of 60 to 1000 is particularly preferable. Further, other cationically polymerizable organic substances of the present invention include episulfide resins, cyclic ethers, lactones, vinyl ethers, phenol/formaldehyde resins, and the like. Such cationically polymerizable organic substances can be used alone or as a mixture of two or more. The sulfonium salt of the present invention is 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. Further, A is a hydrocarbon group having one monovalent aromatic group having 6 to 20 carbon atoms at the alpha position to the cationic sulfur atom.
These aliphatic groups, alicyclic groups, and hydrocarbon groups contain unsaturated bonds, alkoxy groups, nitro groups, halogen groups, hydroxyl groups, carboxyl groups, ester groups, ether groups, cyano groups, carbonyl groups, and sulfone groups. , thioether groups, and the like. Further, the aromatic group may be substituted with a group including an aliphatic group, an alkoxy group, a nitro group, a halogen group, a hydroxyl group, a carboxyl group, an ester group, a cyano group, a carbonyl group, a sulfone group, a thioether group, etc. From the viewpoint of curing speed, electron-withdrawing groups such as A, carboxyl, ester, cyano, carbonyl, and sulfone groups are not preferred. Conversely, electron-donating groups such as methoxy and methyl groups shorten the pot life, but are sometimes preferred because they can increase the curing rate. As the aromatic group, a substituted or unsubstituted phenyl group is preferable, and when the aromatic group has a large number of carbon atoms or when the phenyl group has three or more substituents, the photosensitivity becomes strong and the resistance under normal light increases. The usage time is shortened, which is not desirable. For the same reason as above
It is also undesirable for R ₁ and R ₂ to contain highly photosensitive aromatic groups. X ^- is PF ₆ ^- , AsF ₆ ^- , SbF ₆ ^- , Sb
(OH)F ₅ ^- , more preferably AsF ₆ ^- and SbF ₆ ^- . BF ₄ ^- and other non-nucleophilic anions may also be used, but are not preferred from the viewpoint of curability and physical properties. Unlike general aromatic sulfonium salts, these sulfonium salts are relatively easily synthesized; for example, a sulfonium salt having a halogen anion is synthesized by reacting the corresponding sulfide with an alkyl halide, and then the corresponding Lewis acid (salt) is synthesized. It can also be obtained by performing anion exchange with sulfide, or it can be synthesized in good yield by directly reacting a reagent such as triethyloxonium hexafluorophosphate with sulfide. Preferred examples of such sulfonium salts include benzyltetramethylenesulfonium hexafluorophosphate, benzyltetramethylenesulfonium hexafluoroarsenate, benzyltetramethylenesulfonium hexafluoroantimonate, p-methoxybenzyltetramethylenesulfonium hexafluoroantimonate, and p-methoxybenzyltetramethylenesulfonium hexafluoroantimonate.
-Methoxybenzyltetramethylenesulfonium hexafluoroarsenate, p-nitrobenzyltetramethylenesulfonium hexafluoroarsenate, o-nitrobenzyltetramethylenesulfonium hexafluoroarsenate, benzyldimethylsulfonium hexafluoroantimonate, benzyldiethylsulfonium hexafluoroantimonate etc. The thermosetting composition of the present invention preferably contains 0.05 parts by weight of the special sulfonium salt (2) represented by the above general formula [] per 100 parts by weight of the cationically polymerizable organic substance (1).
It contains from 15 parts by weight, more preferably from 0.1 to 10 parts by weight. In addition, except when the anion is SbF ₆ ^- or Sb(OH)F ₅ ^- , the cationic polymerizable organic substance (1) must contain at least 10 parts by weight of an alicyclic epoxy resin. is preferred. Such compositions of the invention generally have a viscosity of 1 at 25°C.
It is in a liquid state with a centipoise range of 1,000,000 centipoise, or in a powder or solid state that is fluid at high temperatures.
A curing reaction occurs within 30 minutes by heating to 50°C to 130°C, and a non-tacky cured product can be obtained within 1 second to 5 minutes at 150°C or higher. 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. Furthermore, it is also possible to use organic carboxylic acids or acid anhydrides for the purpose of improving physical properties such as electrical properties, or to mix polyols for the purpose of imparting physical properties such as rubber elasticity. Furthermore, for the production of prepregs and other purposes, it is also possible to blend a curing agent or a curing catalyst that can be used in combination with the sulfonium salt of the present invention to carry out a curing reaction at other temperatures. The compositions of the present invention may further include pigments, dyes, fillers,
It can also be used in combination with flame retardants, antistatic agents, curing accelerators, adhesion improvers, flow control agents, surfactants, etc. It may also be useful in some cases to add small amounts of weakly basic compounds to the formulation to extend the pot life. 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 uses of the composition of the present invention include, for example, protection, gloss varnish, ink, paint, adhesive, insulating material, laminate, structural material, prepreg, impregnation material for reinforcing fibers such as glass fiber, molding material, among others. Examples include high-speed liquid molding, casting materials, sealing materials for various parts, and bonding materials. The composition of the present invention has a long pot life at room temperature, is cured in a short time by heating below 150°C, has excellent high temperature curability, is not hygroscopic, and has good water resistance, chemical resistance, and electrical properties of the cured product. can provide excellent cured products. 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 about 300 parts by weight of each sulfonium salt was prepared.
mg was taken and the gelation time was measured on a hot plate heated to 150°C (Nissin Scientific Co., Ltd., gelation tester model GT-D). The results are summarized in a table.

[Table] Example 2 A small amount of a composition consisting of 100 parts by weight of Ep-4100 (bisphenol A type epoxy resin manufactured by Asahi Denka) and 3 parts by weight of benzyltetramethylenesulfonium salt was placed in a glass pin and heated in an oil bath at 150°C. However,
The anion component is halogen (Cl ^- , Br ^- )
In this case, it remained a free-flowing liquid even after 1 hour. When the anion was BF ₄ ^-, thickening was observed after 1 hour, but the film remained uncured. However, when the anion was SbF ₆ ^-, gelation occurred in about 2 minutes and a strong solid was obtained. Example 3 1 part by weight of benzyltetramethylenesulfonium hexafluoroantimonate and ERL-4221100
The composition consisting of parts by weight shows excellent thermosetting properties with a gelation time of 19 seconds at 150°C, but no significant increase in viscosity is observed even when stored in a glass bottle and left at room temperature in an atmosphere of normal light for more than 3 months. Nakatsuta. However, a similar composition containing 1 part by weight of triphenylsulfonium hexafluoroantimonate or the photosensitive aromatic sulfonium salt described in JP-A-54-151936 was completely cured after a few days at room temperature under an atmosphere of normal light. Thickening was observed and in some cases complete gelation occurred. Example 4 1 part by weight of benzyltetramethylenesulfonium hexafluoroantimonate and ERL-4221100
When the composition containing this part by weight was cured at 100°C for 2 hours, a strong cured product was obtained. Further 160℃
Cured products that have been post-cured for more than 2 hours at
It had excellent water resistance, chemical resistance, and electrical properties at temperatures above 160°C. However, a similar composition consisting of 3 parts by weight of benzyltetramethylenesulfonium tetrafluoroborate and 100 parts by weight of ERL-4221 had poor curability and was cured at high temperatures (140°C).
However, the physical properties of the obtained cured product were not good in terms of heat resistance, chemical resistance, water resistance, mechanical strength, and high-temperature electrical properties even after post-curing at 160°C for several hours. Example 5 A composition consisting of 3 parts by weight of benzyltetramethylene sulfonium hexafluoroarsenate, 170 parts by weight of ERL-422, and 30 parts by weight of EPPN-201 (epoxidized phenol novolak manufactured by Nippon Kayaku) was prepared by 105 parts by weight.
C. for 2 hours and then at 160.degree. C. for 4 hours, a hardened product with a heat distortion temperature of 190.degree. C. and excellent electrical properties was obtained. The storage stability of this composition at room temperature was over 3 months. Example 6 The composition of Example 4 containing 1 part by weight of benzyltetramethylene sulfonium hexafluoroantimonate was applied to a mild steel plate and cured in the same manner. The tensile shear adhesive strength was measured and found to be 220 Kg/cm ² . As described above, the composition of the present invention exhibits excellent curability and storage stability, and a cured product having excellent physical properties can be obtained. Example 7 Cationically polymerizable organic substances as shown in the table
The gelation time was measured in the same manner as in Example 1 using 100 parts by weight and the amounts of various sulfonium salts shown in the table. The results are shown in the table.

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Claims (1)

[Claims] 1. As essential components: (1) one or more cationically polymerizable organic substances selected from epoxy resins, episulfide resins, cyclic ethers, lactones, vinyl ethers, and phenol/formaldehyde resins; (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. A is a cationic sulfur atom. a hydrocarbon group having one monovalent aromatic group having 6 to 20 carbon atoms in the α position,
PF ₆ , AsF ₆ , SbF ₆ , Sb(OH)F 5 , an anion selected from Sb(OH)F ₅ ). 2. The thermosetting resin composition according to claim 1, wherein the sulfonium salt is dialkylbenzylsulfonium hexafluoroantimonate (the two alkyl groups may form a ring). 3. Claim 2, wherein the sulfonium salt is a dialkyl-substituted benzylsulfonium hexafluoroantimonate having an electron-donating substituent on the benzyl group (the two alkyl groups may form a ring) thermosetting resin composition.