TWI687449B - Epoxy resin hardening accelerator - Google Patents

Abstract

The present invention provides an epoxy resin hardening accelerator that is excellent in fluidity, high in catalyst activity, and excellent in curability when filled in a mold. The present invention is an epoxy resin hardening accelerator (Q), which is characterized by comprising: a fourth-order phosphonium (A) represented by the general formula (1) and an organic carboxylic acid (B) represented by the general formula (2) The anionic phosphonium salt (S) and the organic phenol compound (C) represented by the general formula (3).

Description

Epoxy resin hardening accelerator

The invention relates to an epoxy resin hardening accelerator. More specifically, it relates to an epoxy resin hardening accelerator containing a quaternary phosphonium salt suitable for manufacturing an epoxy resin-based sealing material for electronic components such as semiconductors.

Previously, epoxy resins have been used for sealing materials for electronic parts such as semiconductor sealing materials due to their excellent moldability and electrical characteristics of cured products. As a sealing material resin, phenol novolaks are used as hardeners, and epoxy resins prepared with a large amount of fillers are widely used. In recent years, as semiconductors have become more integrated, thinner, or improved in mounting methods, there has been a strong demand for moldability of sealing materials and improvement in reliability of sealed semiconductors. In response to this expectation, the role of the hardening accelerator as a component of the sealing material also becomes greater. The hardening accelerators of these epoxy resins usually use tetraphenylphosphonium tetraphenylborate (hereinafter abbreviated as TPP-K).

However, when TPP-K is used alone, the catalyst activity is low. Therefore, if it is solely formulated in epoxy resin and hardener, the curing will not proceed sufficiently. It is necessary to prepare in advance in phenol resin and heat to heat tetraphenylboronic acid When the ester salt is converted to a phenol resin salt, toxic benzene is generated at this time, and although it is trace, it becomes a problem. As an improvement of this problem, the salt of TPP alkyl quaternary phosphonium and a phenol resin is proposed (refer patent document 1 and patent document 2).

However, if the sealing material composition is prepared with an inorganic filler at a high concentration, when TPP alkyl quaternary phosphonium phenol resin salt is used as a hardening accelerator, the epoxy resin, hardener and hardening are accelerated The viscosity of the formulation liquid obtained by heating and melting the mixture of the agents is increased, which causes the so-called poor liquid flowability: when the mold is filled, it will impact the wiring of the semiconductor wafer, or the viscosity will increase before the formulation reaches all corners. Fill part. [Prior Art Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2004-256643 [Patent Document 2] Japanese Patent Laid-Open No. 2005-162944

[Problems to be solved by the invention]

Therefore, an object is to provide an epoxy resin hardening accelerator that is excellent in fluidity during mold filling, high in catalyst activity, and excellent in curability. [Means to solve the problem]

The inventors of the present invention have conducted studies to achieve the above-mentioned object, and as a result, have achieved the invention. That is, the present invention is an epoxy resin hardening accelerator (Q), which is characterized by comprising: a fourth-order phosphonium (A) represented by the general formula (1) and an organic carboxylic acid (B) represented by the general formula (2) ), the anion phosphonium salt (S), and the organic phenol compound (C) represented by the general formula (3).

[Chemical 1]

[In formula (1), R ¹ to R ³ represent an aryl group having 6 to 12 carbon atoms, and R ⁴ represents an alkyl group having 1 to 8 carbon atoms or an aryl group having 6 to 12 carbon atoms]

[Chem 2]

[In formula (2), R ⁵ to R ^{7 are the} same or different, and each represents a hydroxyl group, a carboxyl group, hydrogen, or a C 1-4 alkyl group, and R ⁸ represents a hydroxyl group or a carboxyl group]

[Chemical 3]

[In formula (3), R ⁹ to R ^{11 are the} same or different, and each represents a hydroxyl group, a carboxyl group, hydrogen, or a C 1-4 alkyl group] [Effect of the invention]

Since the present invention includes the fourth-order phosphonium (A), it can be hardened to accelerate the reaction between the epoxy resin and the hardener. In addition, the anion of the organic carboxylic acid (B) and the organic phenol compound (C) have hydrogen-bonding substituents (hydroxyl group and carbonyl group) at the respective 1,3 positions. Therefore, the anion of the organic carboxylic acid (B) and The intermolecular interaction of the organic phenol compound (C) works strongly. By this, the acid strength of the anion of the organic carboxylic acid (B) becomes apparently strong, and the phosphonium salt (S) becomes difficult to dissociate. With this, at a temperature at which the mixture of the epoxy resin, the hardener, and the hardening accelerator is heated and melted, the phosphonium salt (S) is difficult to dissociate and the hardening reaction can be suppressed, and the fluidity during mold filling is excellent. On the other hand, at the curing temperature after the mold is filled, the hydrogen bond of the anion of the organic carboxylic acid (B) and the organic phenol compound (C) is weakened, and the phosphonium salt (S) dissociates and the curability is excellent.

Therefore, the epoxy resin hardening accelerator (Q) of the present invention is excellent in fluidity at the time of mold filling, and has high catalyst activity and excellent curability, so it is suitable for manufacturing epoxy resin-based sealing materials for electronic components such as semiconductors.

The epoxy resin hardening accelerator (Q) of the present invention is characterized by including a phosphonium salt (S) containing a cation of a fourth-order phosphonium (A) and an anion of an organic carboxylic acid (B), and an organic phenol compound (C).

The cation of the fourth-order phosphonium (A) is an essential component for promoting the reaction of the epoxy resin and the hardener, and is represented by the following general formula (1).

[Chemical 4]

[In formula (1), R ¹ to R ³ represent an aryl group having 6 to 12 carbon atoms, and R ⁴ represents an alkyl group having 1 to 8 carbon atoms or an aryl group having 6 to 12 carbon atoms]

Examples of the C 6-12 aryl groups constituting R ¹ to R ⁴ in the general formula (1) include phenyl, naphthyl, biphenyl, methylphenyl, ethylphenyl, and propylphenyl , Butylphenyl, methylnaphthyl, ethylnaphthyl and so on.

Examples of the alkyl group having 1 to 8 carbon atoms constituting R ⁴ include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, second butyl, third butyl, and n-pentyl Group, isopentyl, neopentyl, tertiary pentyl, n-hexyl, 1-methylpentyl, 4-methyl-2-pentyl, 3,3-dimethylbutyl, 2-ethylbutyl Group, n-heptyl group, 1-methylhexyl group, n-octyl group, third octyl group, 1-methylheptyl group, 2-ethylhexyl group, 2-propylpentyl group and the like.

From the viewpoint of fluidity after melt-kneading and the viewpoint of ease of obtaining raw materials, R ¹ to R ^{3 are} preferably phenyl, methylphenyl, and naphthyl, and particularly preferably phenyl. From the viewpoint of curability and ease of synthesis, R ^{4 is} preferably a C 1-4 alkyl group and a C 6-12 aryl group, and particularly preferably a methyl group, an ethyl group, and a phenyl group , Particularly preferred are methyl and ethyl.

The organic carboxylic acid (B) of the present invention is an essential component for improving fluidity after melt-kneading and curing at a curing temperature after mold filling, and is represented by the following general formula (2). [Chem 5]

[In formula (2), R ⁵ to R ^{7 are the} same or different, and each represents a hydroxyl group, a carboxyl group, hydrogen, or a C 1-4 alkyl group, and R ⁸ represents a hydroxyl group or a carboxyl group]

Examples of the C 1-4 alkyl groups constituting R ⁵ to R ⁷ in the general formula (2) include, for example, methyl, ethyl, n-propyl, isopropyl, n-butyl, second butyl, and Tributyl, etc.

From the viewpoint of the ease of acquisition of the organic carboxylic acid (B) and the ease of interaction with the organic phenol compound (C), R ⁵ and R ^{7 are} preferably hydrogen, and R ^{6 is} preferably a hydroxyl group and a carboxyl group.

The synthesis method of the phosphonium salt (S) is not particularly limited. For example, the salt exchange reaction between the alkyl carbonate (A1) of the fourth-order phosphonium (A) and the organic carboxylic acid (B) and the fourth-order phosphonium (A) can be used. Obtained by the salt exchange reaction of the hydroxide (A2) and the organic carboxylic acid (B).

The alkyl carbonate (A1) of the quaternary phosphonium (A) is obtained, for example, by reacting the corresponding tertiary phosphine with carbonic acid diesters. As production conditions, the reaction is carried out in an autoclave at a temperature of 50° C. to 150° C. for 10 hours to 200 hours. In order to complete the reaction quickly and with good yield, it is preferable to use a reaction solvent. The reaction solvent is not particularly limited, but methanol, ethanol and the like are preferred. The amount of solvent is not particularly limited.

Examples of corresponding tertiary phosphines include triphenylphosphine, tri(4-methylphenyl)phosphine, and 2-(diphenylphosphino)biphenyl. The diester carbonate is not particularly limited as long as it is well-known, and specifically, diethyl carbonate, dimethyl carbonate, dibutyl carbonate, diphenyl carbonate, and the like can be used.

The quaternary phosphonium (A) hydroxide (A2), for example, by reacting the corresponding tertiary phosphine with a halogenated (bromo or chloro) alkyl group or a halogenated (bromo or chloro) aryl group, using an inorganic base Obtained by salt exchange. As the production conditions, the reaction is carried out at a temperature of 20°C to 150°C for 1 hour to 20 hours. In order to complete the reaction quickly and with good yield, it is preferable to use a reaction solvent. The reaction solvent is not particularly limited, but methanol, ethanol and the like are preferred. The amount of solvent is not particularly limited.

The corresponding tertiary phosphine may be the same as described above. Examples of the halogenated alkyl group include bromoethane, chlorobutane, 2-ethylhexyl bromide, 2-butylethanol, and 2-chloropropanol. Examples of the halogenated aryl group include bromobenzene, bromonaphthalene, and brominated biphenyl. . Examples of inorganic bases include sodium hydroxide, potassium hydroxide, calcium hydroxide, barium hydroxide, and aluminum hydroxide.

From the viewpoint of hardenability and fluidity, the molar ratio of the salt exchange reaction between the alkyl carbonate (A1) or hydroxide (A2) of the fourth-order phosphonium (A) and the organic carboxylic acid (B) is usually It is 10/90 to 90/10, preferably 20/80 to 80/20. As production conditions, by-product alcohol, water, carbon dioxide, and a reaction solvent etc. are removed while performing the reaction at a temperature of 30°C to 170°C for 1 to 20 hours.

As a method of synthesizing the phosphonium salt (S), from the viewpoint of preventing the mixing of ionic impurities that deteriorate electrical reliability, the alkyl carbonate (A1) of the fourth-order phosphonium (A) and the organic carboxylic acid (B )'S salt exchange reaction.

The organic phenol compound (C) is an essential component to improve the fluidity by interacting with the anion of the organic carboxylic acid (B) in the phosphonium salt (S), suppressing dissociation during melt kneading, and is represented by the following general formula (3) Said.

[化6]

[In formula (3), R ⁹ to R ^{11 are the} same or different, and each represents a hydroxyl group, a carboxyl group, hydrogen, or a C 1-4 alkyl group]

Examples of the C 1-4 alkyl groups constituting R ⁹ to R ¹¹ in the general formula (3) include, for example, methyl, ethyl, n-propyl, isopropyl, n-butyl, second butyl, and Tributyl, etc.

From the viewpoint of the ease of interaction with the anion of the carboxylic acid (B), the organic phenol compound (C) is preferably R ⁹ to R ¹¹ being a hydroxyl group, a carboxyl group and hydrogen, particularly preferably R ⁹ and R ¹¹ being Hydrogen and R ¹⁰ are hydroxy and carboxy, particularly preferably R ⁹ and R ¹¹ are hydrogen and R ¹⁰ is hydroxy.

From the viewpoint of the ease of interaction with the anion of the carboxylic acid (B), the molar ratio of the organic carboxylic acid (B) and the organic phenol compound (C) is usually 10/90 to 90/10, preferably 20/80～80/20, especially 30/70～70/30.

The epoxy resin hardening accelerator (Q) is usually obtained by uniformly mixing the phosphonium salt (S) and the organic phenol compound (C) at a temperature of 50°C to 200°C for 1 hour to 20 hours. In order to complete the mixing quickly, a solvent may also be used. After uniform mixing, the solvent is removed at a temperature of 50°C to 200°C under reduced pressure to normal pressure. The solvent is not particularly limited, but methanol, ethanol and the like are preferred. The blending ratio of the phosphonium salt (S) to the organic phenol compound (C) is appropriately determined according to the molar ratio of the organic carboxylic acid (B) to the organic phenol compound (C).

In order to facilitate mixing with the epoxy resin composition, the epoxy resin hardening accelerator (Q) can be subjected to the following methods: a method of reducing the softening point by using a low viscosity phenol resin as a masterbatch, and pulverizing it into a powder Like method. Examples of the low-viscosity phenol resin include bisphenol A, bisphenol F, phenol novolak resin, cresol novolak resin, and phenol aralkyl resin. The method of masterbatch can use a well-known method. The softening point of the epoxy resin hardening accelerator (Q) is usually 70°C to 140°C, preferably 80°C to 120°C, and more preferably 90°C to 100°C. The reason is that if the temperature is lower than 70°C, welding at the time of pulverization or blocking of the powdered accelerator in storage is likely to occur, which is not good. In addition, if it exceeds 140°C, the hardening accelerator cannot be combined with the ring Oxygen resins are melt-mixed and become non-uniform, which is likely to cause poor curing.

As a method of pulverizing and turning into a powder, for example, pulverization using an impact mill or the like can be performed to obtain a powdery hardening accelerator. In use, the particle size of the powdery hardening accelerator is preferably 100 mesh pass (measured by an air jet sieve method or the like) of 95% or more. The reason is that if it is less than 95%, it becomes easy to prevent uniform dissolution in the epoxy resin composition, and it becomes a cause of poor curing.

The epoxy resin hardening accelerator (Q) of the present invention is added to a mixture prepared with other additives as needed, such as epoxy resin, hardener and filler, to be used, and finally a hardened epoxy resin is obtained. The blending amount of the epoxy resin hardening accelerator (Q) is adjusted according to the reactivity of the epoxy resin or hardener, and is generally 1 to 25 parts by mass, preferably 2 parts by mass relative to 100 parts by mass of the epoxy resin. Parts ~ 20 parts by mass. The optimal blending amount can be set according to the required hardening characteristics and the like. [Example]

Hereinafter, the present invention will be further described by Examples and Comparative Examples, but the present invention is not limited to these examples. Hereinafter, unless otherwise specified,% means weight%, and parts means parts by weight.

<Production Example 1> <Production method of quaternary phosphonium base (A-Be1)> In a stirred autoclave, 180 parts of dimethyl carbonate (manufactured by Tokyo Chemical Industry Co., Ltd.) and 224 parts of solvent methanol are added 262 parts of triphenylphosphine (manufactured by Tokyo Chemical Industry Co., Ltd.) was added thereto, and the reaction was carried out at a reaction temperature of 125°C for 80 hours. After 120 parts of methanol was removed under reduced pressure, 1200 parts of toluene was added to precipitate crystals. The crystals were separated and dissolved in methanol again to obtain a solution of triphenylmethylphosphonium monomethyl carbonate (solid content concentration of 50%) as a quaternary phosphonium base (A-Be1).

<Production Example 2> <Production method of quaternary phosphonium base (A-Be2)> In addition to 262 parts of triphenylphosphine in Production Example 1, 304 parts of tris(4-methylphenyl)phosphine (Tokyo Chemical Industrial Co., Ltd.), instead of dimethyl carbonate, diethyl carbonate (manufactured by Tokyo Chemical Industry Co., Ltd.) was used, and the reaction temperature was set to 130° C., and the reaction time was set to other than 150 hours. In the same manner, a solution of tris(4-methylphenyl)ethylphosphonium monoethyl carbonate (solid content concentration 50%) was obtained as a quaternary phosphonium base (A-Be2).

<Manufacturing Example 3> <Manufacturing method of quaternary phosphonium base (A-Be3)> In a glass round bottom three-necked flask equipped with a dropping funnel and a reflux tube, 262 parts of triphenylphosphine and 1000 parts of isopropanol are added After uniformly dissolving, 157 parts of bromobenzene (manufactured by Tokyo Chemical Industry Co., Ltd.) was added dropwise and reacted at 60°C for 2 hours. Then, 40 parts of sodium hydroxide was added, and the reaction was carried out at 60°C for 2 hours to remove the precipitated salt, thereby obtaining a tetraphenylphosphonium hydroxide solution (solid content concentration of 25%) as a quaternary phosphonium base ( A-Be3).

<Comparative Production Example 1> <Production method of quaternary phosphonium base (A-Be'1)> 180 parts of dimethyl carbonate and 224 parts of solvent methanol were added to a stirred autoclave, and 202 was added dropwise Three parts of tributylphosphine were reacted at a reaction temperature of 125°C for 20 hours to obtain a solution of tributylmethylphosphonium monomethyl carbonate (solid content concentration 50%) as a quaternary phosphonium base (A-Be'1).

<Example 1> A glass round bottom three-necked flask equipped with a dropping funnel and a reflux tube was charged with 640 parts of quaternary phosphonium base (A-Be1) produced in Production Example 1, and the batch was adjusted while adjusting the temperature at 50°C. After inputting 210 parts of trimellitic acid (manufactured by Tokyo Chemical Industry Co., Ltd.), 126 parts of 1,2,4-trihydroxybenzene (manufactured by Tokyo Chemical Industry Co., Ltd.) were added in batches. After adding 200 parts of phenol novolak resin ("H-4" manufactured by Meiwa Chemical Industry Co., Ltd.), the temperature was raised to 175°C while distilling off the solvent (methanol), and the residual solvent was removed under reduced pressure. Obtained epoxy resin hardening accelerator (Q-1).

<Example 2> 5-hydroxyisophthalic acid (made by Tokyo Chemical Industry Co., Ltd.) was changed to 182 parts instead of 210 parts of trimellitic acid in Example 1 instead of 1,2,4-trihydroxy The benzene was changed to resorcinol (manufactured by Tokyo Chemical Industry Co., Ltd.), and an epoxy resin hardening accelerator (Q-2) was obtained in the same manner as in Example 1.

<Example 3> The quaternary phosphonium base (A-Be2) manufactured in Production Example 2 was replaced by the quaternary phosphonium base (A-Be1) in Example 1 instead of trimellitic acid, and was changed to 1, 3,5-benzenetricarboxylic acid (manufactured by Tokyo Chemical Industry Co., Ltd.), and replaced with 126 parts of 1,2,4-trihydroxybenzene to 70 parts of resorcinol (manufactured by Tokyo Chemical Industry Co., Ltd.) ) Except for 70 parts, an epoxy resin hardening accelerator (Q-3) was obtained in the same manner as in Example 1.

<Example 4> Instead of 640 parts of quaternary phosphonium base (A-Be1) in Example 1, it was changed to 1200 parts of quaternary phosphonium base (A-Be3) produced in Production Example 3, instead of trimellitic acid Changed to 180 parts of 5-methylisophthalic acid (manufactured by Tokyo Chemical Industry Co., Ltd.) and replaced 1,2,4-trihydroxybenzene to 5-methylresorcinol (Tokyo Chemical Industry Co., Ltd.) Except manufactured by Co., Ltd., an epoxy resin hardening accelerator (Q-4) was obtained in the same manner as in Example 1.

<Example 5> An epoxy resin hardening accelerator (Q-5) was obtained in the same manner as in Example 1, except that 1,2,4-trihydroxybenzene was replaced with resorcinol in Example 1. .

<Example 6> An epoxy resin hardening accelerator (Q-6) was obtained in the same manner as in Example 1 except that resorcinol was replaced by resorcinol in Example 3.

<Comparative Example 1> The same as Example 1 except that the fourth-order phosphonium base (A-Be1) in Example 1 was replaced with the fourth-order phosphonium base (A-Be'1) manufactured in Comparative Manufacturing Example 1. Way to obtain epoxy resin hardening accelerator (Q'-1).

<Comparative Example 2> An epoxy resin hardening accelerator (Q′) was obtained in the same manner as in Example 2 except that the resorcinol in Example 2 was not used and the phenol novolac resin was changed from 200 parts to 326 parts. -2).

<Comparative Example 3> A ring was obtained in the same manner as in Example 3, except that instead of 1,3,5-benzenetricarboxylic acid in Example 3 was changed to terephthalic acid (manufactured by Tokyo Chemical Industry Co., Ltd.) Oxygen resin hardening accelerator (Q'-3).

<Comparative Example 4> An epoxy resin hardening promotion was obtained in the same manner as in Example 4, except that the 5-methylisophthalic acid in Example 4 was not used and the phenol novolac resin was changed from 200 parts to 480 parts. Agent (Q'-4).

<Comparative Example 5> Except that 210 parts of trimellitic acid in Example 1 was changed to 420 parts of a 50% aqueous solution of 4-sulfophthalic acid (manufactured by Tokyo Chemical Industry Co., Ltd.), the same as Example 4 The epoxy resin hardening accelerator (Q'-5) was obtained in the same way.

<Performance Evaluation> The epoxy resin hardening accelerator (Q-1) to epoxy resin hardening accelerator (Q-6) of the present invention prepared in Examples 1 to 6 and the comparative example were prepared by the following methods The flowability and curability of the epoxy resin hardening accelerators (Q'-1) to epoxy resin hardening accelerators (Q'-5) prepared in Comparative Examples 5 to 5 were evaluated.

<Flowability (flow value)> 100 parts of biphenyl type epoxy resin (softening point 105°C, epoxy equivalent 192), 78 parts by weight of p-xylylphenol resin (softening point 80°C, hydroxyl group) Equivalent to 174), 1000 parts of fused silica powder treated with 1% by weight of silane coupling agent, 1.5 parts of carnauba wax, 4 parts of antimony trioxide and 1 part of carbon black, uniformly crushed and mixed After 12 parts of the epoxy resin hardening accelerator (Q) obtained in each example, it was melt-kneaded using a hot roll at 110° C. for 5 minutes, cooled, and then pulverized to obtain a sealing material. Regarding this sealing material, the flow value (in cm) of the spiral flow at 175°C (70 kg/cm ² ) was measured according to the method of EMMI 1-66 as an index of fluidity.

<Curability (hardening torque)> Use the Curelastometer V type (manufactured by Nippon Trading Co., Ltd., brand name) at a temperature of 175°C, a resin Pice (Dice) P-200, and an amplitude angle of ±1° The sealant measures the hardening torque, the rise time of the hardening torque is taken as the gel time (in seconds), and the value of the hardening torque (in kgf·cm) after 90 seconds from the start of the measurement is taken as the hardenability (mold release) Strength and hardness).

The evaluation results of the epoxy resin hardening accelerator (Q) obtained in Examples 1 to 6 and Comparative Examples 1 to 5 are shown in Table 1.

[Table 1]

As clearly shown in Table 1, it can be seen that the flow rate of the sealant after melt-kneading of the epoxy resin hardening accelerators (Q) of Examples 1 to 6 of the present invention is high, the fluidity is excellent, and the hardening torque is also high , Excellent curability. On the other hand, in Comparative Example 1 containing tetraalkylphosphonium cations, it is known that since the stability of phosphonium cations is low, the flow value of the sealant after melt-kneading becomes very low, and the formability deteriorates. In addition, in Comparative Example 2 that does not include the organic phenol compound (C) and Comparative Example 3 that does not include a hydrogen-bondable group at the meta position of the organic carboxylic acid (B), it is known that the organic carboxylic acid (B ) The interaction with the organic phenol compound (C) is insufficient, so the reaction at the time of melt-kneading cannot be suppressed, and the flow value decreases. In Comparative Example 4 that does not contain the organic carboxylic acid (B), it is known that the catalyst dissociates at the temperature of melt-kneading, so the flow value decreases. In Comparative Example 5 in which the sulfonic acid group as a strong acid was contained in the organic carboxylic acid compound (B), since the catalyst was also difficult to dissociate at the curing temperature, the curability was insufficient. [Industry availability]

The epoxy resin hardening accelerator (Q) of the present invention is excellent in fluidity and curability after melt-kneading, and therefore can be used for manufacturing epoxy resin-based sealing materials for electronic components such as semiconductors.

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Claims (5)

An epoxy resin hardening accelerator, characterized by comprising: a fourth-order phosphonium (A) represented by the general formula (1), and a phosphonium salt (S) containing an anion of the organic carboxylic acid (B) represented by the general formula (2) ), and the organic phenol compound (C) represented by the general formula (3),

[In formula (1), R ¹ to R ³ represent an aryl group having 6 to 12 carbon atoms, and R ⁴ represents an alkyl group having 1 to 8 carbon atoms or an aryl group having 6 to 12 carbon atoms]

[In formula (2), R ⁵ to R ^{7 are the} same or different, and each represents a hydroxyl group, a carboxyl group, hydrogen, or a C 1-4 alkyl group, and R ⁸ represents a hydroxyl group or a carboxyl group]

[In formula (3), R ⁹ to R ^{11 are the} same or different, and each represents a hydroxyl group, hydrogen, or a C 1-4 alkyl group]. The epoxy resin hardening accelerator as described in item 1 of the patent application scope, wherein in the general formula (3), R ⁹ and R ¹¹ are hydrogen, and R ¹⁰ is a hydroxyl group. The epoxy resin hardening accelerator as described in Item 1 or Item 2 of the patent application scope, wherein in the general formula (2), R ⁵ and R ⁷ are hydrogen, and R ⁶ is a hydroxyl group or a carboxyl group. The epoxy resin hardening accelerator as described in item 1 or 2 of the patent application range, wherein the molar ratio of the organic carboxylic acid (B) to the organic phenol compound (C) is 80/20 to 20/80. The epoxy resin hardening accelerator as described in item 1 or item 2 of the patent application scope, wherein the phosphonium salt is synthesized by the salt exchange reaction between the alkyl carbonate of the fourth-order phosphonium (A) and the organic carboxylic acid (B) (S).