JP2003277510A - Manufacturing method of latent catalyst - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a latent catalyst capable of storing a resin composition for a long time at a room temperature, and capable of exerting an excellent catalytic activity during molding and giving a molding of good curability and high quality, from a material of a low price under a mild condition. <P>SOLUTION: This latent catalyst (D) represented by general formula (3) is manufactured by reacting in a solvent an onium salt (A) represented by the general formula (1): Q<SP>+</SP>X<SP>-</SP>, an n-valent (N≥2) proton donor (B) having at least two protons in its molecule which can be ejected outside the molecule and represented by the general formula (2): HY<SB>1</SB>-Z<SB>1</SB>-Y<SB>2</SB>H, and a boric ester (C). <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a latent catalyst. More specifically, the present invention provides
Blended with a thermosetting resin, particularly an epoxy resin and a maleimide resin, it is possible to stably store the resin composition for a long period of time without exhibiting a catalytic action at room temperature, and it is excellent when heated at the time of molding. The present invention relates to a method for producing a latent catalyst capable of exerting a catalytic action and providing good moldability and a high quality molded product.

[0002]

2. Description of the Related Art In recent years, as a curing catalyst for thermosetting resins such as epoxy resins and maleimide resins, research has been conducted on latent catalysts that exhibit favorable behavior in which both storage stability and curability during molding are compatible. No. 11-5829 and JP-A No. 11-171981 propose a tetra-substituted onium tetra-substituted borate having a chelate structure, and it is said that the latent catalyst exhibits favorable behavior in which both room temperature stability and curability during molding are compatible. ing. Conventionally, as a method for synthesizing tetra-substituted onium tetra-substituted borate having these chelate-type structures, i) tetra-substituted onium tetraphenyl borate is used as a starting material, and a proton donor such as an aromatic carboxylic acid or a phenol compound is used at high temperature. A method is known in which and are reacted under bulk conditions. However, in this synthetic method, it is necessary to carry out the reaction at a high temperature of 150 ° C. or higher, and since the tetra-substituted onium tetraphenyl borate as a raw material is expensive, there are problems in the thermal stability and cost of the raw material, and further during the reaction. There is a problem that benzene, which is harmful to the human body, is produced as a by-product.

Further, as a method for synthesizing a tetra-substituted onium tetra-substituted borate having a chelate type structure, i
i) Dealkalization in water or a mixed solvent of water and an organic solvent from an alkali metal or alkaline earth metal salt of a tetra-substituted borate substituted with a tetra-substituted phosphonium halide and a proton donor that releases two protons. A method of obtaining by halogenation (formula [I]) is known, but the tetra-substituted borate alkali salt as a starting material needs to be reacted in an anhydrous system using a Grignard reagent, which requires more complicated work. However, it is difficult to obtain easily because of high cost, which is a problem.

[Chemical 6] (However, in the formula, Q⁺Has an aromatic or heterocyclic ring
A monovalent organic cation having an organic group or an aliphatic group
Then X^-Represents a halogen atom. In the formula, M is monovalent or
Represents a divalent alkali or alkaline earth metal, Z_Four
Is a substituent Y₇, Y ₈Is an organic group having₇, Y
₈Is a monovalent proton-donating substituent that releases a proton.
Represents a group consisting of Substituent Y in the molecule₇, Y₈Is a boron atom
It is capable of binding to and forming a chelate structure. Well
In the formula, Z_FiveIs a substituent Y₉, Y_TenIs an organic group having
R, Y₉, Y_TenIs a monovalent proton-donating substituent.
Represents a group formed by releasing tons. Substituent Y in the molecule₉, Y
_TenCan bond with the boron atom to form a chelate structure
Of. Z_Four, Z_FiveMay be the same or different from each other
Ku, Y ₇, Y₈, Y₉, Y_TenAre the same or different
May be. n represents an integer of 1 or 2. )

[0004]

DISCLOSURE OF THE INVENTION According to the present invention, it is possible to stably store a resin composition for a long period of time without exhibiting a catalytic action at room temperature, and to obtain an excellent catalytic action when heated during molding. Latent catalyst that can be exerted to give good curability and high quality molded products,
It was made for the purpose of producing in high yield from inexpensive raw materials under mild conditions.

[0005]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors have found that a relatively inexpensive onium salt is used as a starting material and further reacted in an organic solvent. It was found that the onium tetra-substituted borate can be produced with high yield under industrially inexpensive and mild conditions, and the present invention has been completed based on these findings.

That is, the present invention is 1. General formula [1]

[Chemical 7] (However, in the formula [1], Q ⁺ represents a monovalent organic cation having an organic group having an aromatic ring or a heterocycle or an aliphatic group, and X ⁻ represents a halogen atom or a hydroxyl group.). Onium salt (A) and general formula [2]

[Chemical 8] (In the formula [2], Z ₁ represents an organic group having the substituents Y ₁ and Y ₂ , and Y ₁ and Y ₂ represent groups formed by releasing a proton from a monovalent proton-donating substituent. , A substituent Y in the same molecule
₁ , Y ₂ can bond with a boron atom to form a chelate structure. ) In the table, n having a proton capable of releasing the molecule outside of at least two or more in the molecule (n ≧ 2)
Valent proton donor (B) and borate esters (C)
And a reaction in a solvent, a method for producing a latent catalyst (D) represented by the general formula [3],

[Chemical 9] (However, in formula [3], Q ⁺ is an organic group having an aromatic ring or a heterocycle or an aliphatic group, and the central atom is a monovalent organic cation composed of phosphorus, nitrogen, sulfur, and a carbon atom. are shown. in addition, wherein Z ₂ represents an organic group having a substituent _{Y 3, Y 4, Y 3} , Y 4 represents a group monovalent proton donating substituent group releases a proton The substituents Y ₃ and Y ₄ in the same molecule can combine with a boron atom to form a chelate structure, wherein Z ₃ represents an organic group having the substituents Y ₅ and Y ₆ , ₅ and Y ₆ are groups formed by releasing a proton from a monovalent proton-donating substituent, and the substituents Y ₅ and Y ₆ in the same molecule can bond with a boron atom to form a chelate structure. Z ₂ and Z ₃ may be the same or different from each other, and Y ₃ , Y ₄ , Y ₅ and Y ₆ may be the same or different from each other. It may be.) 2. The onium salt (A) represented by the general formula [1] is a quaternary phosphonium salt represented by the general formula [4] or a quaternary ammonium salt represented by the general formula [5], 1
A method for producing a latent catalyst according to item,

[Chemical 10] (However, in the formula [4], R ₁ , R ₂ , R ₃ and R ₄ represent an organic group having a aromatic ring or a heterocycle or a monovalent aliphatic group, which may be the same or different from each other. X ₁ represents a halogen atom or a hydroxyl group.)

[Chemical 11] (However, in the formula [5], R ₅ , R ₆ , R ₇ , R ₈ , R ₉ and R
₁₀ represents an organic group having an aromatic ring or a heterocycle or a monovalent aliphatic group, which may be the same or different from each other. X ₁ represents a halogen atom or a hydroxyl group. ) 3. Proton donor (B) represented by the general formula [2]
Is an aromatic carboxylic acid having at least two carboxyl groups in the molecule, an aromatic carboxylic acid having at least one carboxyl group and at least one hydroxyl group in the molecule, or at least two hydroxyl groups in the molecule. A method for producing a latent catalyst according to claim 1 or 2, which is a phenol compound having a carboxyl group and not having a carboxyl group.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The onium salt (A) used in the present invention is represented by the general formula [1]. The cation Q ⁺ in the onium salt (A) is a monovalent organic cation having an organic group having an aromatic ring or a heterocycle or an aliphatic group, and as the onium cation forming such an onium salt (A), Examples thereof include phosphorus- or nitrogen-type onium cations such as tetra-substituted phosphonium, tetra-substituted ammonium, amidinium and imidazolium, and sulfur or carbon-type onium cations such as tri-substituted sulfonium and tri-substituted carbonium. Specific examples of the onium salt (A) include, for example, tetraphenylphosphonium bromide, benzyltriphenylphosphonium chloride, tetratolylphosphonium bromide, tetranaphthylphosphonium bromide, ethyltriphenylphosphonium bromide, n-butyltriphenylphosphonium chloride, Quaternary phosphonium salts such as tetra-n-butylphosphonium hydroxide, tetra-
Quaternary ammonium salts such as n-butylammonium hydroxide, tetra-n-octylammonium bromide, tributylbenzylammonium chloride and N-laurylpyridinium chloride, bis (triphenylphosphoranylidene) ammonium chloride, bis (tri (4-
Aryl such as methoxyphenyl) phosphoranylidene) ammonium chloride, bis (tri (2,6-dimethoxyphenyl) phosphoranylidene) ammonium chloride, bis (benzyldiphenylphosphoranylidene) ammonium chloride, bis (tris (dimethylamino) phosphoranylidene) ammonium chloride Or an alkyl-substituted phosphoranilidene ammonium salt, tri-n-
Butylsulfonium iodide, triphenylsulfonium bromide, tris (dimethylaminosulfonium) bromide and other sulfonium salts, triphenylmethylium chloride, bis (4-diethylaminophenyl) phenylmethylium chloride, tris (4-dimethylaminophenyl) methylium Examples include carbocation-type onium salts such as chloride. Among them, substituted or unsubstituted in the latent catalyst from the viewpoint of stability to light, heat, hydrolysis, and high temperature activity of the latent catalyst. Particularly preferred are quaternary phosphonium salts and quaternary ammonium salts, which are substituted phosphonium ions or substituted phosphoranilidene ammonium ions having an aryl group or an alkyl group as a substituent.

N (n ≧ 2) having at least two protons that can be released outside the molecule used in the present invention
The valent proton donor (B) is a compound represented by the general formula [2]. Examples of such a proton donor include a carboxylic acid, a phenol compound, and polyhydric alcohols. Among these proton donors, in particular, an aromatic carboxylic acid having at least two carboxyl groups in the molecule, an aromatic carboxylic acid having at least one carboxyl group and at least one hydroxyl group in the molecule, or at least two in the molecule. A phenol compound having one hydroxyl group and no carboxyl group is preferable, and the _two substituents Y ₁ and Y ₂ in the general formula [2] are each an organic group Z.
Relative to _1, more preferably they are adjacent to each other. Specific examples of such a proton donor include aromatic carboxylic acids having at least two carboxyl groups in the molecule, such as o-phthalic acid,
1,8-naphthalic acid, 2,3-pyridinecarboxylic acid, trimellitic acid, pyromellitic acid, 1,4,5,8-naphthalenetetracarboxylic acid, etc. are mentioned, and at least one carboxyl group and hydroxyl group are included in the molecule. Examples of the aromatic carboxylic acid having at least one are salicylic acid, 3-hydroxy-2-naphthoic acid, 1-hydroxy-2-naphthoic acid, 2-hydroxy-1-naphthoic acid and 3,5-dihydroxy-2-naphthoic acid. Acid, 2-hydroxybiphenyl-3-carboxylic acid, 4-hydroxybiphenyl-
Examples of 3-carboxylic acid, 2,2'-biphenol-4-carboxylic acid, protocatechuic acid, gallic acid, etc., and a phenol compound having at least two hydroxyl groups in the molecule and not having a carboxyl group As, catechol, resorcinol, 2,3-dihydroxynaphthalene, 2,2'-biphenol, 1,1'-bi-2-naphthol, pyrogallol, methyl gallate, ethyl gallate, gallic acid esters such as octyl gallate And the like, and as other proton donors, 2-hydroxybenzyl alcohol, thiosalicylic acid, 3-hydroxypicolinic acid, 2-
Hydroxynicotinic acid, 2,3-dihydroxypyridine, 2,
Examples thereof include, but are not limited to, 3-dihydroxyquinoxaline, 4-methyl-1,2-benzenedithiol, chloranilic acid, 2,5-dihydroxyterephthalic acid, and tannic acid. Among them, 3-hydroxy-2-naphthoic acid, 2,3-dihydroxynaphthalene, and 2,2 'are preferable from the viewpoint of heat, stability against hydrolysis, and latent heat of latent catalyst.
-Biphenol is particularly preferred.

Examples of the boric acid esters (C) used in the present invention include tri-substituted boric acid having a lower alkoxy group such as trimethyl borate, triethyl borate, tri-n-propyl borate and tri-n-butyl borate. Esters and the like are mentioned as examples, but the present invention is not limited thereto.
From the viewpoint of reactivity during production, trimethyl borate and triethyl borate are particularly preferable.

As the solvent used in the present invention, alcohols, ketone solvents, aprotic polar solvents, water and the like are preferable, and furthermore, a homogeneous mixed solvent of the above-mentioned solvents or a homogeneous mixed solvent of the above-mentioned solvent and other organic solvent can also be used. it can. Examples of alcohols include methanol, ethanol, n-propanol,
Isopropanol, n-butanol, isobutanol,
Benzyl alcohol, ethylene glycol, propylene glycol, butylene glycol, 2-methoxyethanol, 2-ethoxyethanol, 2- (methoxymethoxy) ethanol, 2-butoxyethanol, 1-methoxy-2-propanol, 1-ethoxy-2-propanol. , Diethylene glycol, dipropylene glycol,
Examples of the aprotic polar solvent include diacetone alcohol and triethylene glycol.
For example, N, N-dimethylformamide, N, N-dimethylacetamide, dimethyl sulfoxide, N-methyl-2-pyrrolidone, hexamethylphosphoamide, sulfolane and the like can be mentioned. Examples of the ketone-based solvent include, but are not limited to, methylpropylketone, diethylketone, butylmethylketone, methylisobutylketone, cyclohexanone, acetonylketone, cyclohexanone, methylcyclohexanone, acetophenone, and the like. Absent. In addition, by using a protic solvent such as water or methanol in combination with an alcohol, an aprotic polar solvent such as N, N-dimethylformamide, dimethylsulfoxide, or N-methyl-2-pyrrolidone in combination with alcohols as a solvent, It is possible to obtain better reactivity.

In the present invention, the latent catalyst comprising onium borate represented by the general formula [3] has a general formula [1].
And an n (n ≧ 2) -valent proton donor (B) represented by the general formula [2] having at least two protons capable of being released outside the molecule represented by the general formula [2]. )
And boric acid ester (C) are mixed in a solvent and neutralized with an alkali if necessary, whereby the compound can be easily synthesized. The mixing order is not particularly limited, but the proton donor (B) and the borate ester (C) are first mixed in a solvent and, if necessary, neutralized with an alkali, and then the onium salt (A). It is advantageous to mix the above in order to obtain the target onium borate catalyst in high yield.

In the present invention, an n (n ≧ 2) -valent proton donor (B) represented by the general formula [2] and having at least two protons that can be released outside the molecule in the molecule.
And a borate ester (C) in a solvent in which the proton is dissociated and the proton can be dissociated, the proton donor releases a proton to form a chelate structure with the boron atom of the borate ester, and a stable monovalent A borate anion complex is formed. Furthermore, the onium salt (A) represented by the general formula [1]
The onium borate represented by the general formula [3] is produced by forming a salt with the borate anion complex by the cation moiety of. This reaction can be allowed to proceed rapidly even under relatively mild conditions such as room temperature, and the reaction can be easily controlled.

The reaction conditions in the present invention are as follows:
Although it varies depending on conditions such as solvent and charged amount, for example, the charged molar ratio of the onium salt (A) represented by the general formula [1] and the borate ester (C) is 1: 0.5 to 1 : 2
Is preferable, and an n (n ≧ 2) -valent proton donor (B) having at least two protons that can be released outside the molecule represented by the general formula [2] and a borate ester The molar ratio charged with (C) is from 1: 0.5 to
A range of 1: 2 is preferred. If the charged molar ratio is out of these ranges, the yield and the purity may be significantly reduced. The concentration of the raw material in the solvent is 1 wt% to 30
The range of wt% is preferable, and more preferably 5 wt% to 2
It is charged in the range of 0 wt% and the reaction is carried out at a temperature in the range of room temperature to about 50 ° C. for about 0.5 to 2 hours. In order to recover the target catalyst, onium borate, from the reaction solution, a method of filtering precipitated crystals is generally adopted. It is also possible to increase the yield. When the presence of a trace amount of impurities poses a problem depending on the use, the recovered onium borate can be further washed with an organic solvent or pure water to prepare a product having a desired purity.

In the method for producing a latent catalyst comprising onium borate of the present invention, since inexpensive borate esters are used as the boron source on the borate side, conventional expensive tetra-substituted borate salts and tetra-substituted phosphonium tetra-substituted borate are used. It is also advantageous in terms of cost as compared with the manufacturing method used. Since boric acid esters are soluble in many organic solvents and can react in a homogeneous system even at room temperature,
It is more advantageous in terms of reactivity.

The latent catalyst comprising onium borate represented by the general formula [3] of the present invention does not show catalytic activity at room temperature when blended with a thermosetting resin such as epoxy resin or maleimide resin. The thermosetting resin can be highly cured by exhibiting catalytic activity at a high temperature during molding without the curing reaction of the thermosetting resin proceeding.

[0016]

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

(Example 1) Stirrer and Dimroth cooling
In a 100 ml 3-neck separable flask equipped with a tube,
3-Hydroxy-2-naphthoic acid 3.76 g (0.02
mol), trimethyl borate 1.04 g (0.01 mo)
l), 15 ml of methanol and N, N-dimethylform
Charge 5 ml of amide (DMF) and keep at 65 ° C for about 10 minutes.
Stirring was continued and uniform dissolution was achieved. Then, in advance,
Tetraphenylphosphonium bromide in tanol 4.
A solution in which 19 g (0.01 mol) was uniformly dissolved was stirred.
Drop it in a flask with stirring, and add 10% sodium hydroxide water.
To the solution 4.00 ml (0.01 mol) was added dropwise.
Was neutralized, yellowish white crystals were deposited. Deposited crystals
After filtration, wash with 100 ml of ethanol and cold water
It was Then, filtration and drying are performed, and the melting point is 272 to 274 ° C.
To obtain 6.64 g of yellow crystals. The product obtained ¹H-
Analysis by NMR, MS spectrum, elemental analysis, results
Was as follows: Elemental analysis of the product: (Experimental value) C: 76.3%, H: 4.6%, P: 4.
2%, B: 1.5%, (theoretical value) C: 76.5%, H:
4.5%, P: 4.3%, B: 1.5% Product¹The H-NMR spectrum is shown in FIG.
The tor is shown in FIG. From the analysis results, the obtained product is the formula
Target tetraphenylphosphonium bi represented by [7]
Su (3-oxy-2-naphthoyloxy) borate (T
PP-HNAB) was confirmed. (Yield 92%)

[0018]

[Chemical 12]

(Examples 2 to 8) The reaction raw materials, solvent and temperature of Example 1 were changed as shown in Table 1, synthesis was carried out in the same procedure as in Example 1, and the synthesis results and analysis results are shown in Table 1. Summarized. In Examples 2 to 8 as well, it was confirmed from the analysis results that the obtained products were various target onium borates represented by the formulas [8] to [14], respectively.

[0020]

[Table 1]

[0021]

[Chemical 13]

[0022]

[Chemical 14]

[0023]

[Chemical 15]

[0024]

[Chemical 16]

[0025]

[Chemical 17]

[0026]

[Chemical 18]

[0027]

[Chemical 19]

In each of Examples 1 to 8, the desired onium borate could be synthesized under mild conditions in a short time in a high yield.

(Comparative Example 1) In a 100 ml three-neck separable flask equipped with a stirrer and a Dimroth condenser,
3-Hydroxy-2-naphthoic acid 3.76 g (0.02
mol) and 6.58 g (0.01 mol) of tetraphenylphosphonium tetraphenylborate were charged, and
When a bulk reaction was carried out at 0 ° C., the reaction proceeded nonuniformly while benzene was by-produced, and the product crystals solidified and precipitated during the reaction, and the reaction stopped. 100m reaction product
When washed with 1 l of ethanol, yellowish white crystals were precipitated. The precipitated crystals were filtered and dried to obtain 2.53 g of yellow crystals having a melting point of 272-274 ° C. The obtained product is ¹ H--N
The product obtained by analysis by MR, MS spectrum and elemental analysis is the target tetraphenylphosphonium bis (3-oxy-2-naphthoyloxy) represented by the formula [7].
It was confirmed to be borate (abbreviated as TPP-HNAB).
(35% yield)

Comparative Example 2 A 100 ml three-neck separable flask equipped with a stirrer and a Dimroth condenser was used.
3-Hydroxy-2-naphthoic acid 3.76 g (0.02
mol) and 6.58 g (0.01 mol) of tetraphenylphosphonium tetraphenylborate were charged, and
When bulk reaction was carried out at 0 ° C., the reaction proceeded nonuniformly while benzene was by-produced, and crystals of the product solidified and precipitated during the reaction. When the temperature in the flask was raised to 280 ° C., which is higher than the melting point of the product, the reaction proceeded and turned yellowish brown. When the reaction product was washed with 100 ml of ethanol, yellowish white crystals were precipitated. The precipitated crystals are filtered and dried, melting point 27
5.49 g of yellow crystals of 2 to 274 ° C. were obtained. The obtained product was analyzed by ¹ H-NMR, MS spectrum, and elemental analysis, and the obtained product was represented by the formula 7. The desired tetraphenylphosphonium bis (3-oxy-2-naphthoyloxy) borate was obtained. (Abbreviated as TPP-HNAB). (Yield 78%)

Comparative Examples 1 and 2 were not preferable because the reaction was non-uniform and the yield was low, or a high reaction temperature was required, and benzene was produced as a by-product.

[0032]

EFFECTS OF THE INVENTION According to the present invention, a resin composition can be stably stored for a long period of time from an inexpensive raw material under mild conditions in a short time with a high yield without exhibiting a catalytic action at room temperature. It is possible to produce a latent catalyst that is capable of exhibiting excellent catalytic action at the molding temperature.

[Brief description of drawings]

1 is a ¹ H-NMR spectrum of the product of Example 1. FIG.

2 is an MS spectrum of the product of Example 1. FIG.

Front page continuation (51) Int.Cl. ⁷ Identification code FI theme code (reference) C07F 9/54 C07F 9/54 19/00 19/00 F term (reference) 4H006 AA02 AB40 AC52 AC60 4H048 AA02 AB40 BB14 BB20 VA20 VA45 VA75 VB10 4H050 AA02 AB40 BB14 BB20 4J031 CB06

Claims (3)

[Claims] 1. A general formula [1]: (However, in the formula [1], Q ⁺ represents a monovalent organic cation having an organic group having an aromatic ring or a heterocycle or an aliphatic group, and X ⁻ represents a halogen atom or a hydroxyl group.). Onium salt (A) and a general formula [2] (In the formula [2], Z ₁ represents an organic group having the substituents Y ₁ and Y ₂ , and Y ₁ and Y ₂ represent groups formed by releasing a proton from a monovalent proton-donating substituent. , A substituent Y in the same molecule
₁ , Y ₂ can bond with a boron atom to form a chelate structure. N having at least two protons that can be released to the outside of the molecule, represented by) (n ≧ 2)
Valent proton donor (B) and borate esters (C)
And a reaction in a solvent, a method for producing a latent catalyst (D) represented by the general formula [3]. [Chemical 3] (However, in formula [3], Q ⁺ is an organic group having an aromatic ring or a heterocycle or an aliphatic group, and the central atom is a monovalent organic cation composed of phosphorus, nitrogen, sulfur, and a carbon atom. are shown. in addition, wherein Z ₂ represents an organic group having a substituent _{Y 3, Y 4, Y 3} , Y 4 represents a group monovalent proton donating substituent group releases a proton The substituents Y ₃ and Y ₄ in the same molecule can combine with a boron atom to form a chelate structure, wherein Z ₃ represents an organic group having the substituents Y ₅ and Y ₆ , ₅ and Y ₆ are groups formed by releasing a proton from a monovalent proton-donating substituent, and the substituents Y ₅ and Y ₆ in the same molecule can bond with a boron atom to form a chelate structure. Z ₂ and Z ₃ may be the same or different from each other, and Y ₃ , Y ₄ , Y ₅ and Y ₆ may be the same or different from each other. It may be.) 2. An onium salt (A) represented by the general formula [1] is a quaternary phosphonium salt represented by the general formula [4] or a quaternary ammonium represented by the general formula [5]. The method for producing a latent catalyst according to claim 1, which is a salt. [Chemical 4] (However, in the formula [4], R ₁ , R ₂ , R ₃ and R ₄ represent an organic group having a aromatic ring or a heterocycle or a monovalent aliphatic group, which may be the same or different from each other. X ₁ represents a halogen atom or a hydroxyl group.) (However, in the formula [5], R ₅ , R ₆ , R ₇ , R ₈ , R ₉ and R
₁₀ represents an organic group having an aromatic ring or a heterocycle or a monovalent aliphatic group, which may be the same or different from each other. X ₁ represents a halogen atom or a hydroxyl group. ) 3. A proton donor (B) represented by the general formula [2] is an aromatic carboxylic acid having at least two carboxyl groups in the molecule, at least one carboxyl group and at least one hydroxyl group in the molecule. The method for producing a latent catalyst according to claim 1 or 2, which is an aromatic carboxylic acid having one or a phenol compound having at least two hydroxyl groups in the molecule and having no carboxyl group.