WO2014006855A1 - Epoxy resin curing accelerator - Google Patents

Description

Epoxy resin curing accelerator

The present invention relates to an epoxy resin curing accelerator. More specifically, the present invention relates to an epoxy resin curing accelerator made of a quaternary phosphonium sulfone salt, which is suitable for producing an epoxy resin-based transparent sealing material for electronic parts such as semiconductors.

As a resin for sealing optical semiconductor elements (light-emitting diodes, optical sensors, light-emitting elements for optical communication, light-receiving elements), it requires colorless and transparent properties, epoxy and acid anhydride curing agents, and curing accelerators. A composition comprising:

Conventionally, as epoxy resin curing accelerators, amines, imidazoles, phosphine, DBU and organic acid salts thereof, ammonium or phosphonium compounds have been widely used (for example, see Patent Documents 1 to 3).

In the case of acid anhydride curing, the hue varies greatly depending on the type of curing accelerator. Since triphenylphosphine (TPP) and imidazole, which are often used as epoxy resin curing accelerators, are likely to be colored during high-temperature curing, they can be said to be easily colored accelerators (see Non-Patent Document 1).

In addition, when an ammonium or phosphonium bromide salt that is relatively less colored is used as a curing accelerator, under high-temperature and high-humidity conditions, Br ions contained in the curing accelerator cause an optical semiconductor element, There is a problem in that an electrode such as aluminum, copper or silver or a wiring is corroded to cause a decrease in electrical performance or failure of a semiconductor device sealed with the resin composition.

In order to solve these problems, for example, a liquid epoxy resin composition using tetrabutylphosphonium non-halogen salt as a curing accelerator has been proposed (see Patent Document 4).
However, it is difficult for the phosphonium non-halogen compounds as described above to contain no water, halogen, or alkali metal ions, which have an effect on the curing of the epoxy resin composition or the moisture absorption of the cured product after curing, depending on the production method.

JP 58-128756 A Japanese Unexamined Patent Publication No. 63-77929 Japanese Patent Laid-Open No. 11-269253 JP 7-196774 A

A complete collection of encapsulating technologies and materials in the latest semiconductors and LEDs

In the above background, the present invention is a composition comprising an epoxy resin, a curing agent and a curing accelerator, which is difficult to color with time after curing or after curing, while containing impurities such as halogen, alkali metal, and water. In addition, since it has excellent moisture resistance, it is an object of the present invention to provide a curing accelerator that reduces the corrosion of metals even under high temperature and high humidity.

As a result of intensive studies to solve the above-described problems, the present inventors have found a curing accelerator capable of solving the above-mentioned problems and have completed the present invention. That is, the present invention is an epoxy resin curing accelerator comprising a quaternary phosphonium sulfonate represented by the general formula (1).

[Wherein R1 to R5 are each independently a hydrogen atom, a linear or branched alkyl group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms, and R6 has 1 to 16 carbon atoms. Represents an alkyl group. X ⁻ represents an anion residue of organic sulfonic acid. ]

According to the present invention, a composition containing an epoxy resin, an acid anhydride, and the curing accelerator of the present invention is difficult to be colored at the time of curing or to be colored with time after curing. Excellent corrosivity. It is particularly suitable for transparent applications such as semiconductor encapsulants.

Hereinafter, embodiments of the present invention will be described in detail.

One of the characteristics of the quaternary phosphonium sulfonate represented by the general formula (1) is that it has a specific quaternary phosphonium cation structure in which three aryl groups are bonded to the phosphorus element on the cation side. This specific structure imparts high chemical stability and low water absorption performance as an accelerator. In the above three aryl groups, R1 to R5 are each independently a hydrogen atom, a linear or branched alkyl group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms. Preferred as R1 to R5 are hydrogen, methyl group, and methoxy group.

In the sulfonate salt of quaternary phosphonium represented by the general formula (1), another feature on the cation side is that an alkyl group R6 is bonded to this phosphorus element in addition to three aryl groups. Due to this feature, the curing accelerator of the present invention is also excellent in light resistance. The alkyl group R6 represents an alkyl group having 1 to 16 carbon atoms. Preferred as R6 is an alkyl group having 1 to 4 carbon atoms, and most preferred is an ethyl group. This triarylethylphosphonium salt imparts high curing acceleration performance.

Preferred as the quaternary phosphonium of the present invention are triphenylmethylphosphonium, triphenylethylphosphonium, triphenylbutylphosphonium, tris (m-methylphenyl) ethylphosphonium, tris (m-methylphenyl) propylphosphonium, tris (o -Methoxyphenyl) ethylphosphonium, particularly preferred is triphenylethylphosphonium {in the general formula (1), R ¹ to R ⁵ are all hydrogen atoms and R6 is an ethyl group}.

In the sulfonate of quaternary phosphonium represented by the general formula (1), X ⁻ is an anion residue of sulfonic acid that has lost one proton. Examples of the organic sulfonic acid in the anionic residue of the sulfonic acid include methanesulfonic acid, ethanesulfonic acid, 1-propanesulfonic acid, 2-propanesulfonic acid, 1-butanesulfonic acid, 1-pentanesulfonic acid, 1 -Aliphatic sulfonic acids such as hexanesulfonic acid, 1-octanesulfonic acid, 1-decanesulfonic acid, 1-dodecanesulfonic acid (eg, aliphatic sulfonic acids having 1 to 16 carbon atoms); benzenesulfonic acid, p- Toluenesulfonic acid, 4-ethylbenzenesulfonic acid, 3- (linear or branched octyl) benzenesulfonic acid, 4- (linear or branched octyl) benzenesulfonic acid, 3- (linear or branched) Linear dodecyl) benzenesulfonic acid, 4- (linear or branched dodecyl) benzenesulfonic acid, 2,4-dimethyl Le benzenesulfonic acid, 2,5-dimethylbenzene sulfonic acid, 4-methoxy benzenesulfonic acid, 4-ethoxy-benzenesulfonic acid, 4-chlorobenzene sulfonic acid.

The epoxy resin curing accelerator of the present invention preferably does not contain impurities such as halogen, alkali metal, and water.
The content of halogen ions or alkali metal ions is preferably 5 ppm or less based on the weight of the epoxy resin curing accelerator.

As a method for producing a quaternary phosphonium sulfonate as a curing accelerator of the present invention, for example, the following [I] to [IV]
The method of] is mentioned. The method [I] or [II] is preferred from the viewpoint that the content of impurities such as water that has a harmful effect on curing and the cause of moisture absorption, such as halogen and alkali metal ions, can be reduced and further reduced.

[I] A dialkyl ester carbonate that is equivalent to or more than the tertiary phosphine (preferably 1.1 to 5.0 equivalents) is added to a solvent (for example, ethanol: the amount used is 10 to 1 based on the weight of the tertiary phosphine). , 000 wt%) in the presence or absence of a reaction temperature of 40 to 200 ° C., preferably 80 to 150 ° C. to form a quaternary phosphonium salt, and further adding a sulfonic acid (quaternary phosphonium And 1.0-1 to 1.05 equivalents), and salt exchange is performed by stirring at 10 to 150 ° C. for 1 hour. Excess diethyl ester and solvent are stripped at 80 to 150 ° C. under normal pressure or reduced pressure to obtain the desired curing accelerator. In the following, the unit of decompression MPa represents the gauge pressure.

[II] A tertiary phosphine, a carbonic acid dialkyl ester, and the phenol resin (B) are mixed in the same amount as used in the method of [I], and the reaction temperature is 40 to 200 ° C. in the presence or absence of a solvent. Preferably, after reacting at 80 to 150 ° C., an excess of diethyl carbonate and a solvent are stripped at 80 to 150 ° C. under normal pressure or reduced pressure to obtain the desired curing accelerator.

Since the method [I] or [II] does not use water, halogen compounds, or alkali metal compounds, the content of the obtained quaternary phosphonium salt water is 0.5% or less, and halogen or alkali metal ions are present. It is a method of making it 5 ppm or less.

[III] Tertiary phosphine and 1.0 to 1.5 equivalents of ethyl halide in the presence of a solvent (for example, toluene: 10 to 1,000% by weight based on the weight of the tertiary phosphine) To a quaternary phosphonium salt by reaction at a reaction temperature of 10 to 100 ° C., preferably 40 to 100 ° C. The quaternary phosphonium salt is salt exchanged with 1 equivalent of sodium hydroxide and 1.0 to 1.05 equivalent of sulfonic acid, and 50 to 400% water is added based on the weight of the mixture. The organic layer after salt exchange at 10 to 100 ° C. is taken out, and the solvent is stripped at 80 to 150 ° C. under normal pressure or reduced pressure to obtain the desired curing accelerator.

[IV] 0.7 to 2 mol, more preferably 1.0 to 1.3 mol of sulfonic acid is used per 1 mol of a quaternary phosphonium hydroxide solution (solvent is water, methanol, etc.). A salt can be manufactured by adding. From the reaction mixture containing the obtained salt, the solvent is removed by an appropriate method such as distillation under reduced pressure to separate the target salt.

The blending amount of the curing accelerator is usually 0.3 to 5.0 parts by mass, preferably 0.5 to 3.0 parts by mass with respect to 100 parts by mass of the epoxy resin. When the blending amount of the curing accelerator is less than 0.1 parts by mass, the heat curing rate becomes slow and the productivity becomes worse. On the other hand, if it exceeds 5.0 parts by mass, heat generation during curing is intense, and the temperature of the cured product is excessively increased, which may cause coloring.

The epoxy resin composition of the present invention contains an epoxy resin, a curing agent and the epoxy resin curing accelerator.

Examples of the epoxy resin include those having excellent transparency such as bisphenol A type epoxy resin, bisphenol F type epoxy resin, and alicyclic epoxy resin, and these can be used alone or in combination of two or more. . In addition to these, other epoxy resins, for example, phenol novolac type epoxy resins, heterocyclic epoxy resins, hydrogenated bisphenol A type epoxy resins, aliphatic epoxy resins, and spiro rings are included within the scope of the present invention. An epoxy resin or the like can be used in combination.

Examples of the curing agent include phthalic anhydride, trimellitic anhydride, pyromellitic anhydride, maleic anhydride, benzophenone tetracarboxylic anhydride, hexahydrophthalic anhydride, tetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, methyltetrahydro Conventionally known colorless or light yellow acid anhydrides such as phthalic anhydride and polyazeline acid anhydride can be used, and these can be used alone or in combination of two or more.
The amount of the acid anhydride curing agent used is usually 0.7 to 1.5 equivalents, preferably 0.8 to 1.2 equivalents, relative to 1 equivalent of the epoxy group of the epoxy resin. Outside this range, the physical properties of the cured product may deteriorate or the cured product may be colored.

Moreover, you may use together conventionally well-known various hardening accelerators in the range which does not impair the characteristic of this invention with the hardening accelerator of this invention. Examples of the conventionally known various curing accelerators include, for example, imidazoles such as triarylphosphines, tetraphenylphosphonium / tetraphenylborate, 2-methylimidazole, 1,8-diazabicyclo (5,4,0) undecene-7. Etc. These may be used alone or in combination of two or more.

The epoxy resin composition using the curing accelerator according to the present invention includes an anti-discoloration agent such as a phenolic antioxidant, a light scattering agent such as fine silica powder, a colorant such as a dye, an epoxy silane, and a vinyl silane. Coupling agents that improve the compatibility with silica powders such as those based on titanate and titanate, and internal mold release agents that facilitate demolding from molding dies such as stearic acid and its metal salts may be blended.

When the epoxy resin composition using the curing accelerator of the present invention is a liquid epoxy resin composition for casting, it is obtained, for example, by dissolving the curing accelerator of the present invention in a liquid acid anhydride curing agent. A liquid epoxy resin and other additives are added to the solution and mixed uniformly with a high-speed stirring device such as a homomixer.
Further, when the epoxy resin composition using the curing accelerator of the present invention is a solid epoxy resin composition for pressure molding, for example, a solid epoxy resin, a solid acid anhydride curing agent and a curing accelerator. And other additives are mixed with powder, uniformly mixed at a temperature of 50 to 150 ° C. using a kneading apparatus such as a three-roll mill, and the resulting mixture is cooled and solidified, and then pulverized. If necessary, it can be produced by tableting.

Curing of the epoxy resin composition using the curing accelerator of the present invention is usually performed at a temperature of 80 to 180 ° C. In the case of a liquid epoxy resin composition, for example, after pouring into a molding die, it is cured in advance at a temperature of 80 to 150 ° C. for 1 to 2 hours, then taken out from the die, and further at 120 to 180 ° C. for 1 to 5 hours. A cured product can be obtained by an after-curing method or the like. In the case of a solid epoxy resin composition, for example, it is filled under pressure at a temperature of 120 to 180 ° C. by a pressure molding machine such as a transfer molding machine and cured for 1 to 10 minutes, and then from the mold. The cured product can be obtained by taking it out and further after-curing at 120 to 180 ° C. for 1 to 5 hours.
By using the epoxy resin composition for semiconductor encapsulation of the present invention to seal semiconductor elements such as transistors and diodes, a semiconductor device protected from the external atmosphere and mechanical shock can be obtained.

Hereinafter, the present invention will be further described with reference to examples, but the present invention is not intended to be limited thereto. In the examples, “parts” represents parts by weight.

Production Example 1
[Curing accelerator A1]
Triphenylmethylphosphonium methanesulfonate Agitated autoclave was charged with 120 parts of dimethyl carbonate, 120 parts of methanol, and 262 parts of triphenylphosphine and reacted at a reaction temperature of 120 ° C. for 10 hours to obtain triphenylethylphosphonium monomethyl. A methanolic solution of carbonate was obtained.
To a reaction vessel containing 98 parts of methanesulfonic acid (manufactured by Wako Pure Chemical Industries, Ltd.), 24 parts of the methanol solution of triphenylmethylphosphonium monomethyl carbonate obtained above was gradually added to remove the generated carbon dioxide, The remaining methanol was removed under reduced pressure to prepare a curing accelerator [A1].

Production Example 2
[Curing accelerator A2]
A triphenylethylphosphonium methanesulfonate stirred autoclave was charged with 150 parts of diethyl carbonate, 262 parts of triphenylphosphine, and 98 parts of methanesulfonic acid (manufactured by Wako Pure Chemical Industries, Ltd.) at a reaction temperature of 140 ° C. for 30 hours. The reaction was carried out to remove the remaining solvent and the generated carbon dioxide gas to prepare a curing accelerator [A2].

Example 1
In the epoxy resin composition, the curing accelerator A1 obtained in Production Example 1 was dissolved in acid anhydride (20 to 60 ° C.) according to the blending amount shown in Table 1, and the epoxy resin was added and mixed to uniformity. Can be made by degassing at 50-60 ° C under reduced pressure. The obtained epoxy resin composition was placed at a distance of 4 mm between two glasses, cured by heating at 120 ° C. for 1 hour, and then aftercured at 150 ° C. for 3 hours to obtain a cured sample 1.

Example 2
A cured sample 2 was obtained in the same manner as in Example 1 except that the curing accelerator A2 obtained in Production Example 2 was used instead of the curing accelerator A1.

Comparative Example 1
A cured sample was prepared in the same manner as in Example 1 except that the curing accelerator [A3] (1,8-diazabicyclo (5.4.0) undecene-7.octylate) was used instead of the curing accelerator A1. 3 was obtained.

Comparative Example 2
A cured sample 4 was obtained in the same manner as in Example 1 except that the curing accelerator [A4] (tetrabutylphosphonium bromide) was used instead of the curing accelerator A1.

<Discoloration test>
The initial coloring degree (coloring at the time of hardening) of the obtained cured sample having a thickness of 4 mm was evaluated with a transmittance of 400 nm. The cured sample was allowed to stand in an oven at 150 ° C. for 72 hours, and then the thermal coloration degree of the cured sample was evaluated with a transmittance of 400 nm.

The results of each example and comparative example are shown in Table 1.

In the table above,
Epoxy resin component B1: Bis-A type epoxy resin (Japan Epoxy Resin, JER828, epoxy equivalent 186)
B2: Alicyclic epoxy resin (Daicel Industrial, Celoxide 2021P, epoxy equivalent 137)
Acid anhydride component C1: Methyl HHPA (Hitachi Chemical Industries, HN5500E, hydroxyl equivalent 176)

From the results shown in Table 1, the following can be understood.

In Examples 1 and 2, a quaternary phosphonium sulfonate was used as the curing accelerator of the present invention, and it was found that the coloring immediately after curing was less than the coloring in Comparative Examples 1 and 2.

Further, in Examples 1 and 2, a quaternary phosphonium sulfonate was used as the curing accelerator of the present invention, and it was found that the results of the high temperature discoloration test were better than those of Comparative Examples 1 and 2.

From the above, since the curing accelerator of the present invention shown in the examples was used, it can be seen that the epoxy resin composition is hardly colored at the time of curing at high temperature, and further, the obtained epoxy cured product has little discoloration with time.

The epoxy resin curing composition containing the curing accelerator of the present invention does not contain a halogen atom or an alkali metal, and is excellent in moisture resistance, so that it is particularly a sealing material for optical semiconductor elements such as light emitting elements and light receiving elements. Thus, it is useful for applications requiring transparency, heat discoloration with time, and high electrical properties under high temperature and high humidity conditions. The epoxy resin composition of the present invention is also suitable for epoxy resin-based artificial marble and the like that are also required to have transparency and characteristics that do not yellow even when used for a long time.

Claims (5)

An epoxy resin curing accelerator comprising a quaternary phosphonium sulfonate represented by the general formula (1).

[Wherein R1 to R5 are each independently a hydrogen atom, a linear or branched alkyl group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms, and R6 has 1 to 16 carbon atoms. Represents an alkyl group. X ⁻ represents an anion residue of organic sulfonic acid. ] The epoxy resin curing accelerator according to claim 1, wherein R6 in the general formula (1) is an ethyl group. The epoxy resin curing accelerator according to claim 1 or 2, wherein the weight of halogen ions or alkali metal ions based on the weight of the epoxy resin curing accelerator is 5 ppm or less, respectively. An epoxy resin composition comprising an epoxy resin, a curing agent, and the epoxy resin curing accelerator according to any one of claims 1 to 3. Hardened | cured material formed by hardening | curing the epoxy resin composition of Claim 4.