JP2023077718A - Epoxy resin-based composition - Google Patents

Abstract

To provide an epoxy resin-based composition having fast curability in a field such as various coating materials, members for civil engineering, adhesive agents, fiber reinforcing composite materials, or optical components such as displays and lenses, and epoxy resin-based curing materials excellent in appearance.MEANS: An epoxy resin-based composition comprising an epoxy resin, an amine-based curing agent, and a curing accelerator, and the epoxy resin-based composition comprises a phosphonium compound represented by the following general formula (1) as the curing accelerator. [Chemical formula 1]. (Wherein, R1 to R4 and X have the same meaning as above.)SELECTED DRAWING: None

Description

The present invention relates to an epoxy resin composition comprising an epoxy resin, an amine curing agent, and a curing accelerator, and relates to a fast curing epoxy resin composition and an epoxy resin cured product having a good appearance.

Conventionally, thermosetting resin compositions, typified by epoxy resins, have been used as molding materials having excellent mechanical, chemical and electrical properties. , paints, and composite materials for aircraft and automobiles.

For example, for paint, it is common to use an epoxy resin-based composition obtained by mixing an epoxy resin and an epoxy resin curing agent before coating, and cure the composition at room temperature to obtain a coating film.

Among such epoxy resin compositions, an epoxy resin composition using amine as an epoxy resin curing agent is preferably used because it is easy to handle. However, it is known that the aforementioned epoxy resin-based composition requires a long time for curing at room temperature.

On the other hand, the curing accelerator contained as a component in the thermosetting resin composition accelerates the curing of the thermosetting resin composition by adding, Selection of a suitable curing accelerator is extremely important since it also affects various properties such as heat resistance and appearance.

In the above epoxy resin composition, salicylic acid (see Patent Document 1), p-toluenesulfonic acid, boron trifluoride, etc. are used as curing accelerators in order to shorten the curing time (Patent Document 2). See), it was known that the acid reacts with the amine, resulting in poor appearance of the cured product (see Non-Patent Document 1).

Under such circumstances, there is a demand for a curing accelerator for epoxy resins that gives the epoxy resin-based composition having rapid curing properties and an epoxy resin-based cured product with good appearance.

International Publication No. 2017/175740 JP 2007-126627 A

Kobunshi Ronbunshu Vol. 47, No. 2 (1990), p. 159-164 (Feb., 1990)

The present invention seeks to solve the problems associated with the prior art described above. That is, it is an object of the present invention to provide an epoxy resin composition having a fast curing property and an epoxy resin cured product having a good appearance in an epoxy resin composition using an amine as a curing agent for the epoxy resin.

In view of such circumstances, the present inventors have conducted extensive studies. As a result, they found that a fast-curing epoxy resin composition and an epoxy resin cured product with a good appearance can be obtained when a specific phosphonium compound is blended as a curing accelerator, thereby completing the present invention. reached.

（式中、Ｒ^１～Ｒ^４は、同一または異なって、炭素数１～１６の置換もしくは非置換の炭化水素基を示す。Ｘは、ハロゲン原子を示す。）で表されるホスホニウム化合物を含むことを特徴とするエポキシ樹脂系組成物。
〔２〕前記一般式（１）において、Ｒ^１～Ｒ^４が、同一または異なって、メチル基、フェニル基、メトキシメチル基、ベンジル基、および、カルボキシエチル基から選ばれる置換基である〔１〕に記載のエポキシ樹脂系組成物。
〔３〕前記一般式（１）が、メチルトリフェニルホスホニウムブロミド、メトキシメチルトリフェニルホスホニウムクロリド、ベンジルトリフェニルホスホニウムクロリド、および、カルボキシエチルトリフェニルホスホニウムブロミドからなる群から選ばれる１種のホスホニウム化合物であることを特徴とする〔１〕、〔２〕に記載のエポキシ樹脂系組成物。
〔４〕〔１〕～〔３〕のいずれかに記載のエポキシ樹脂系組成物を硬化して得られるエポキシ樹脂系硬化物。 That is, the gist of the present invention is as follows.
[1] An epoxy resin composition comprising an epoxy resin, an amine curing agent, and a curing accelerator, wherein the curing accelerator is represented by the following general formula (1)

(Wherein, R ¹ to R ⁴ are the same or different and represent a substituted or unsubstituted hydrocarbon group having 1 to 16 carbon atoms. X represents a halogen atom.) An epoxy resin composition characterized by:
[2] In the general formula (1), R ¹ to R ⁴ are the same or different and are substituents selected from a methyl group, a phenyl group, a methoxymethyl group, a benzyl group and a carboxyethyl group [1 ].
[3] The general formula (1) is one phosphonium compound selected from the group consisting of methyltriphenylphosphonium bromide, methoxymethyltriphenylphosphonium chloride, benzyltriphenylphosphonium chloride, and carboxyethyltriphenylphosphonium bromide. The epoxy resin composition according to [1] and [2], characterized in that
[4] A cured epoxy resin product obtained by curing the epoxy resin composition according to any one of [1] to [3].

The phosphonium compound of the present invention is an epoxy resin composition using an amine as a curing agent for epoxy resins. It is useful for giving an epoxy resin-based cured product.

The present invention will be described in detail below.
In the present invention, a substituted or unsubstituted hydrocarbon group is a hydrocarbon group having 1 to 16 carbon atoms, an aliphatic hydrocarbon group which may have a substituent, and a It contains aromatic hydrocarbon groups that are also good. When the hydrocarbon group has a substituent, the number of carbon atoms in the hydrocarbon group does not include the number of carbon atoms in the substituent.

In the present invention, the aliphatic hydrocarbon group which may have a substituent is a linear or branched saturated aliphatic hydrocarbon group, or a linear or branched unsaturated aliphatic hydrocarbon group. It may be a hydrocarbon group. Specific examples of aliphatic hydrocarbon groups include alkyl groups such as methyl group, ethyl group, n-propyl group, isopropyl group, 1,1-dimethylpropyl group, 1,2-dimethylpropyl group, 1-ethylpropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, 1-methylbutyl group, 2-methylbutyl group, 3-methylbutyl group, 1-ethylbutyl group, 2-ethylbutyl group, 1,1-dimethylbutyl group , 2,2-dimethylbutyl group, 1,2-dimethylbutyl group, 2,3-dimethylbutyl group, 3,3-dimethylbutyl group, 2-ethyl-2-methylbutyl group, n-pentyl group, neopentyl group, 2-pentyl group, 3-pentyl group, tert-pentyl group, 1-methylpentyl group, 2-methylpentyl group, 3-methylpentyl group, 4-methylpentyl group, 1-ethylpentyl group, 2-ethylpentyl group , n-hexyl group, isohexyl group, 2-hexyl group, 3-hexyl group, 1-methylhexyl group, 2-methylhexyl group, 1-ethylhexyl group, 2-ethylhexyl group, n-heptyl group, n-octyl group , n-nonyl group, n-decyl group, n-undecyl group, n-dodecyl group, n-tridecyl group, n-tetradecyl group, n-pentadecyl group, saturated aliphatic hydrocarbon groups such as n-hexadecyl group, Examples of alkenyl groups include allyl groups and vinyl groups, and examples of alkynyl groups include unsaturated aliphatic hydrocarbon groups such as ethynyl groups and propargyl groups.

In the present invention, the optionally substituted aliphatic hydrocarbon group may be an alicyclic hydrocarbon group. Also, the alicyclic hydrocarbon group may be either an alicyclic saturated hydrocarbon group or an alicyclic unsaturated hydrocarbon group. Specific examples of alicyclic hydrocarbon groups include cycloalkyl groups such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, norbornyl, and adamantyl groups. Cycloalkenyl groups include alicyclic unsaturated hydrocarbon groups such as cyclobutenyl, cyclopentenyl, and cyclohexenyl groups.

In the present invention, the optionally substituted aromatic hydrocarbon group may be a monocyclic or polycyclic aromatic hydrocarbon group. Specific examples of aromatic hydrocarbon groups include phenyl groups, naphthyl groups, and anthracenyl groups as aryl groups.

In the present invention, the substituents that may be substituted on the aliphatic hydrocarbon group include alkoxy groups having 1 to 4 carbon atoms, aryl groups, aryloxy groups, hydroxyl groups, carboxy groups, acyl groups, amino groups, halogen atoms, and the like. are mentioned. As the aliphatic hydrocarbon group having a substituent, examples of alkoxy-substituted alkyl groups include methoxymethyl group and ethoxymethyl group, and examples of aryl-substituted alkyl groups include benzyl group.

In the present invention, the substituent which may be substituted on the aromatic hydrocarbon group includes an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, an aryl group, an aryloxy group, a hydroxyl group, a carboxy group, An acyl group, an amino group, a halogen atom and the like are included. Examples of aromatic hydrocarbon groups having substituents include, specifically, alkyl group-substituted aryl groups such as tolyl group, dimethylphenyl group, ethylphenyl group, propylphenyl group, n-butylphenyl group, t-butylphenyl group, Alkoxy-substituted aryl groups include methoxyphenyl, ethoxyphenyl, n-butoxyphenyl and t-butoxyphenyl groups.

When the aliphatic hydrocarbon group or aromatic hydrocarbon group has a substituent, the position of the substituent and the number of substituents are not particularly limited. Moreover, when having two or more substituents, they may be the same or different.

The present invention is an epoxy resin composition containing at least an epoxy resin, an amine curing agent, and an epoxy resin curing accelerator. Hereinafter, this is sometimes referred to as "the epoxy resin composition of the present invention".

The epoxy resin, the amine curing agent, and the epoxy resin curing accelerator, which are components of the epoxy resin composition of the present invention, are described below.

（式中、Ｒ^１～Ｒ^４は、同一または異なって、炭素数１～１６の置換もしくは非置換の炭化水素基を示す。Ｘは、ハロゲン原子を示す。）で表されるホスホニウム化合物が挙げられる。 <Curing accelerator for epoxy resin>
The phosphonium compound used as an epoxy resin curing accelerator in the epoxy resin composition of the present invention has the following general formula (1)

(Wherein, R ¹ to R ⁴ are the same or different and represent a substituted or unsubstituted hydrocarbon group having 1 to 16 carbon atoms. X represents a halogen atom.) be done.

R ¹ to R ⁴ in the phosphonium compound of general formula (1) are the same or different and represent a substituted or unsubstituted hydrocarbon group having 1 to 16 carbon atoms.

In the phosphonium compound of general formula (1), the substituent represented by R ¹ to R ⁴ is a substituted or unsubstituted hydrocarbon group having 1 to 16 carbon atoms, and from the viewpoint of curability, 1 to 12 carbon atoms. are preferred, and those having 1 to 6 carbon atoms are more preferred. Examples of the hydrocarbon group include the substituents described above, and specific examples include methyl group, ethyl group, propyl group, n-butyl group, octyl group, decyl group, dodecyl group, cyclohexyl group, phenyl group, methoxymethyl group, and benzyl. group, hydroxymethyl group, carboxyethyl group, carboxypentyl group and carboxydecyl group, and particularly methyl group, ethyl group, propyl group, n-butyl group, phenyl group, methoxymethyl group, benzyl group, hydroxymethyl group and carboxy Ethyl group, carboxypentyl group and carboxydecyl group are preferred.

X in the phosphonium compound of general formula (1) represents a halogen atom. Specific examples include a fluorine atom, a chlorine atom, a bromine atom and an iodine atom, and a chlorine atom, a bromine atom and an iodine atom are preferred.

The above phosphonium compound can be easily produced by a known method based on the description of this specification.
For example, a quaternary phosphonium compound can be obtained by reacting 1 mol of an organic halogen compound with 1 mol of a tertiary phosphine in an organic solvent. In this case, the tertiary phosphine and the organic halogen compound may be used alone or in combination of two or more to obtain the above compound. When two or more types are mixed, the quaternary phosphonium compound may be obtained after first mixing two or more types of tertiary phosphine and organic halogen compound, or two or more types of quaternary phosphonium compounds may be mixed. good too.

For the purpose of precipitating high-purity crystals from the obtained reaction product and removing unreacted raw materials, the obtained reaction product is treated with water, an alcoholic organic solvent (methanol, ethanol, propanol, butanol, etc.), Ketone organic solvents (acetone, methyl ethyl ketone, methyl isobutyl ketone, diethyl ketone, etc.), ether organic solvents (tetrahydrofuran, diethyl ether, dibutyl ether, 2-methyltetrahydrofuran, cyclopentyl methyl ether, dioxane, etc.), non-polar solvents (benzene, Toluene, xylene, hexane, heptane, etc.) or a mixed solvent thereof may be used for washing and recrystallization for purification.

As the tertiary phosphine, the organic halogen compound, and the solvent, commercially available products may be used.

（式中、Ｒ^１～Ｒ^４は、同一または異なって、炭素数１～１６の置換もしくは非置換の炭化水素基を示す。Ｘは、ハロゲン原子を示す。） Phosphonium compounds obtained by these methods are usually composed mainly of a 1:1 (molar ratio) salt of a phosphonium cation and a halogen anion, and are represented by the general formula (1).

(Wherein, R ¹ to R ⁴ are the same or different and represent a substituted or unsubstituted hydrocarbon group having 1 to 16 carbon atoms. X represents a halogen atom.)

An epoxy resin composition containing, as a component, the epoxy resin curing accelerator containing the phosphonium compound of the present invention has a fast curing property at room temperature, and contains the epoxy resin curing accelerator containing the phosphonium compound of the present invention as a component. The contained epoxy resin-based cured product has a good appearance.

The curing accelerator for epoxy resins of the present invention may further contain, in addition to the phosphonium compound, solvents, fillers, additives, etc. that are commonly used for curing accelerators for epoxy resins, as long as they do not affect the effect.

In addition to the phosphonium compound, the epoxy resin curing accelerator of the present invention may be used in combination with an appropriate epoxy resin curing accelerator.

Typical examples of the phosphonium compound represented by the general formula (1) are listed in Table 1, but are not limited to these.

The following descriptions in the table indicate functional groups as follows. Me: methyl group, Et: ethyl group, Pr: propyl group, Bu: butyl group, Ph: phenyl group, _MeOCH2 : methoxymethyl group, Bn: benzyl group, _HOCH2 : hydroxymethyl group, HOOC( _CH2 ) ₂ : carboxyethyl group, HOOC(CH ₂ ) ₅ : carboxypentyl group, HOOC(CH ₂ ) ₁₀ : carboxydecyl group

<Epoxy resin>
The epoxy resin is not particularly limited, and general-purpose epoxy resins having two or more epoxy groups in one molecule can be used. Examples include phenol, cresol, xylenol, catechol, resorcinol, bisphenol A, Phenols such as bisphenol F and/or naphthols such as naphthol and dihydroxynaphthalene are condensed or co-condensed with a compound having an aldehyde group such as formaldehyde, acetaldehyde, propionaldehyde, benzaldehyde and salicylaldehyde in the presence of an acidic catalyst. Phenol novolac type epoxy resin obtained by epoxidizing the obtained novolac resin, ortho cresol novolac type epoxy resin; Resins, biphenyl-type epoxy resins, stilbene-type epoxy resins; epoxidized phenol aralkyl resins, naphthol aralkyl resins, biphenyl aralkyl resins, etc. synthesized from phenols and/or naphthols and dimethoxyparaxylene or bis(methoxymethyl)biphenyl Phenol aralkyl type epoxy resin, naphthol aralkyl type epoxy resin, biphenyl aralkyl type epoxy resin; glycidyl ether type epoxy resin of alcohols such as butanediol, polyethylene glycol, polypropylene glycol; carboxylic acids such as phthalic acid, isophthalic acid, tetrahydrophthalic acid Glycidyl ester type epoxy resins; aniline, isocyanuric acid, metaxylylenediamine, 1,3-bis(aminomethyl)cyclohexane, diaminodiphenylmethane, etc. Glycidylamine type epoxy resins in which active hydrogens bonded to nitrogen atoms are substituted with glycidyl groups ;vinylcyclohexene diepoxide obtained by epoxidizing intramolecular olefin bond, 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, 2-(3,4-epoxy)cyclohexyl-5,5-spiro Alicyclic epoxy resins such as (3,4-epoxy)cyclohexane-m-dioxane; glycidyl ethers of para-xylylene and/or meta-xylylene-modified phenolic resins; glycidyl ethers of terpene-modified phenolic resins; phenols and/or naphthols and dicyclo Dicyclopentadiene-modified phenolic resin synthesized from pentadiene, glycidyl ether of dicyclopentadiene-type naphthol resin; glycidyl ether of cyclopentadiene-modified phenolic resin; glycidyl ether of polycyclic aromatic ring-modified phenolic resin; glycidyl of naphthalene ring-containing phenolic resin Ether; halogenated phenol novolac type epoxy resin; hydroquinone type epoxy resin; trimethylolpropane type epoxy resin; linear aliphatic epoxy resin obtained by oxidizing olefin bond with peracid such as peracetic acid; diphenylmethane type epoxy resin; sulfur Atom-containing epoxy resins and the like are included.

These epoxy resins may be used alone or in combination of two or more, may be used as they are, may be added with appropriate solvents and additives, or may be commercially available products. good.

<Amine curing agent>
The amine-based curing agent is not particularly limited, and it is possible to use a general-purpose polyamine having two or more amino groups in one molecule. Aliphatic polyamines such as xylenediamine, trimethylhexamethylenediamine, 2-methylpentamethylenediamine, isophoronediamine, 1,3-bisaminomethylcyclohexane, bis(4-aminocyclohexyl)methane, norbornenediamine, 1,2-diamino Alicyclic polyamines such as cyclohexane, piperazine-type polyamines such as N-aminoethylpiperazine, 1,4-bis(2-amino-2-methylpropyl)piperazine, diethyltoluenediamine, dimethylthiotoluenediamine, 4,4'-diamino-3,3'-diethyldiphenylmethane, bis(methylthio)toluenediamine, diaminodiphenylmethane, m-phenylenediamine, diaminodiphenylsulfone, trimethylenebis(4-aminobenzoate), polytetramethylene oxide-di-p-amino benzoate, polyoxytetramethylene bis(p-aminobenzoate) and the like.

Modified reaction products of these polyamines and epoxy resins, modified reaction products of polyamines and monoglycidyl compounds, modified reaction products of polyamines and epichlorohydrin, and modified reaction products of polyamines and alkylene oxides having 2 to 4 carbon atoms. modified reactants, amide oligomers obtained by reacting polyamines with polyfunctional compounds having at least one acyl group, polyamines, polyfunctional compounds having at least one acyl group, and monovalent carboxylic acids and Amide oligomers obtained by reaction with/or derivatives thereof can also be used as epoxy resin curing agents.

These amine-based curing agents may be used alone or in combination of two or more, or may be used as they are. Solvents, additives, etc. may be added as appropriate and used as a curing agent composition. You can also use a commercially available product.

<Epoxy resin composition>
The epoxy resin composition of the present invention comprises an epoxy resin, an amine curing agent, and an epoxy resin curing accelerator. In addition, it may further contain solvents, fillers, additives and the like that are commonly used in epoxy resin compositions as long as they do not affect the effect.
The epoxy resin-based composition of the present invention can contain various known solvents in order to form a varnish. Examples of solvents include 2-methoxyethanol, 2-ethoxyethanol, 2-propoxyethanol, 2-butoxyethanol, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, 1-propoxy-2-propanol, and the like. alcohols such as methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, benzyl alcohol, N,N-dimethylformamide, N,N-dimethylacetamide, dimethylsulfoxide, N aprotic polar solvents such as -methylpyrrolidone; ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone; and water-insoluble solvents such as toluene, xylene and ethyl acetate.

The epoxy resin composition of the present invention can contain various known inorganic fillers in order to improve various performances such as impact resistance. Examples of inorganic fillers include silica, alumina, mica, talc, aluminum flakes, glass flakes and the like. When these are added, they are preferably added in a range of 0.01% to 10.0% by weight based on the total weight of the cured reaction product.

In addition, an antifoaming agent, a wetting agent, an antioxidant, an antirust additive, a pigment, etc. may be added to the epoxy resin composition, and a resin other than the epoxy resin may also be included.

The content of the amine-based curing agent in the epoxy resin-based composition of the present invention is determined in consideration of the equivalent ratio between the epoxy equivalent in the epoxy resin and the equivalent of the amine-based curing agent. Specifically, the ratio of the number of active amine hydrogens in the amine curing agent to the number of epoxy groups in the epoxy resin is preferably 0.5 to 5.0. More preferably, the ratio is between 0.8 and 3.0.

If the content of the phosphonium compound in the epoxy resin-based composition of the present invention is less than 0.5 parts by weight, the composition may not exhibit sufficient curing power. Since the storage stability and the appearance of the cured product may deteriorate, it is preferably 0.5 to 10 parts by weight with respect to 100 parts by weight of the epoxy resin. is more preferably 0.7 to 5 parts by weight.

The method for preparing the thermosetting resin composition is not particularly limited, and it can be prepared by uniformly mixing the respective components. A preferable preparation method is a method of uniformly stirring and mixing an epoxy resin, an amine-based curing agent, and an epoxy resin curing accelerator at a temperature of about 20 to 150°C. You may use the solvent illustrated as.

In addition, each component of the epoxy resin, the amine-based curing agent, and the curing accelerator may be mixed at once in each mixing step, or may be mixed little by little in multiple batches. Similarly, when the solvent, additive, inorganic filler, etc. are mixed, they can be mixed once or in multiple batches at any time.

When mixing each component, a kneader such as a roll, a kneader, a bead mill, or a mixer may be used in order to facilitate uniform stirring and mixing.

<Epoxy resin-based cured product>
In the present invention, the epoxy resin-based cured product means a solid product obtained by heating an epoxy resin-based composition under specific conditions according to the epoxy resin-based composition so that the epoxy resin loses fluidity and is cured. say. Hereinafter, the solid material obtained by curing the epoxy resin-based composition of the present invention may be referred to as "the epoxy resin-based cured product of the present invention".

The epoxy resin-based cured product of the present invention can be obtained by heating the above-described epoxy resin-based composition of the present invention under ordinary curing conditions for epoxy resin-based compositions. It can be usually obtained by heating at a curing temperature of about 20 to 150° C. for a curing time of 10 minutes to 10 days, and the conditions can be changed as appropriate.

EXAMPLES The thermosetting resin composition of the present invention will be described in detail below with reference to examples and test examples, but the present invention is not limited to these.

<Example 1>
2 parts by weight of methoxymethyltriphenylphosphonium chloride (Compound No. 13) (hereinafter referred to as "TPP-MOC") and 2 parts by weight of methanol were placed in a sample bottle and dissolved at room temperature. To this, 20 parts by weight of 1,3-bisaminomethylcyclohexane (manufactured by Tokyo Chemical Industry Co., Ltd.), an amine-based curing agent, was added, and after mixing at room temperature, a liquid bisphenol A type epoxy resin, jER828EL (epoxy equivalent: 186, Mitsubishi Chemical Co., Ltd.) was added. (manufacturer) was added and stirred and mixed at room temperature to obtain an epoxy resin composition.

<Example 2>
An epoxy resin composition was prepared in the same manner as in Example 1, except that 2 parts by weight of benzyltriphenylphosphonium chloride (Compound No. 14) (hereinafter referred to as "TPP-ZC") was used instead of 2 parts by weight of TPP-MOC. Obtained.

<Example 3>
An epoxy resin composition was prepared in the same manner as in Example 1, except that 2 parts by weight of methyltriphenylphosphonium bromide (Compound No. 27) (hereinafter referred to as "TPP-MB") was used instead of 2 parts by weight of TPP-MOC. Obtained.

<Example 4>
Epoxy resin composition in the same manner as in Example 1 except that 2 parts by weight of carboxyethyltriphenylphosphonium bromide (Compound No. 34) (hereinafter referred to as "TPP-PAB") was used instead of 2 parts by weight of TPP-MOC. got

<Comparative Example 1>
An epoxy resin composition was obtained in the same manner as in Example 1, except that 2 parts by weight of triphenylphosphine (hereinafter referred to as "TPP") was used instead of 2 parts by weight of TPP-MOC.

<Comparative Example 2>
An epoxy resin composition was obtained in the same manner as in Example 1, except that 2 parts by weight of salicylic acid was used instead of 2 parts by weight of TPP-MOC.

<Comparative Example 3>
An epoxy resin composition was obtained in the same manner as in Example 1, except that 2 parts by weight of p-toluenesulfonic acid monohydrate (hereinafter referred to as "TsOH") was used instead of 2 parts by weight of TPP-MOC.

<Comparative Example 4>
An epoxy resin composition was obtained in the same manner as in Example 1 without adding a curing accelerator.

[Curability evaluation]
The resulting epoxy resin composition was evaluated for curability by a tack-free method according to JIS A-1439-5-19.

In the tack-free method, the sample is stored at 23 ± 2°C, and the surface of the sample is lightly touched with a fingertip at regular intervals to measure the time required for the sample to stop adhering to the fingertip, and the superiority or inferiority of the curability is evaluated. It is something to do.

Test and evaluation methods are described below.
The obtained epoxy resin-based composition was placed in an incubator set at 24° C., evaluated by the tack-free method every 30 minutes, and the time until it became tack-free was measured. The shorter the time until tack-free, the better the curability. It can be said that the curability is good when the time is 3 hours or less, preferably 2 hours or less, more preferably 1 hour or less.

[Appearance evaluation]
The cured samples were visually observed and evaluated according to the following criteria.
◯: The cured product is smooth and no foaming is observed. ×: The cured product is uneven and foaming is observed. Tables 2 and 3 show the results.

As shown in Tables 2 and 3, the epoxy resin composition according to the present invention takes less time to become tack-free, and the appearance of the epoxy resin cured product is good.
That is, the epoxy resin-based composition containing the phosphonium compound of the present invention is useful because it has a faster curing property and gives an epoxy resin-based cured product with a good appearance as compared with the case where a conventional curing accelerator is used. .

The epoxy resin-based composition and cured product of the present invention are excellent in rapid curing and appearance. It is also extremely useful in fields such as parts.

Claims (4)

An epoxy resin composition comprising an epoxy resin, an amine curing agent, and a curing accelerator, wherein the curing accelerator is represented by the following general formula (1)

(Wherein, R ¹ to R ⁴ are the same or different and represent a substituted or unsubstituted hydrocarbon group having 1 to 16 carbon atoms. X represents a halogen atom.) An epoxy resin composition characterized by: 2. The formula according to claim 1, wherein R ¹ to R ⁴ in general formula (1) are the same or different and are substituents selected from methyl, phenyl, methoxymethyl, benzyl and carboxyethyl groups. epoxy resin-based composition. The general formula (1) is one phosphonium compound selected from the group consisting of methyltriphenylphosphonium bromide, methoxymethyltriphenylphosphonium chloride, benzyltriphenylphosphonium chloride, and carboxyethyltriphenylphosphonium bromide. 3. The epoxy resin composition according to claim 1 or 2. An epoxy resin-based cured product obtained by curing the epoxy resin-based composition according to any one of claims 1 to 3.