JP3089963B2 - Trimellitic anhydride-modified imidazole compound, production method thereof and curing accelerator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an epoxy which is used as a curing accelerator to give a cured product having good storage stability and fluidity and excellent properties such as fast curing, moisture resistance and adhesiveness. The present invention relates to a trimellitic anhydride-modified imidazole compound capable of obtaining a resin composition, a method for producing the same, and a curing accelerator for an epoxy resin composition.

[0002]

2. Description of the Related Art
In the semiconductor industry, resin-sealed diodes, transistors, ICs, LSIs, and ultra-LSIs are the mainstream. Among them, epoxy resins, curing agents, and epoxy resin compositions containing various additives are generally used as other components. It has excellent moldability, adhesiveness, electrical properties, mechanical properties, and moisture resistance as compared with thermosetting resins.

[0003] For this reason, semiconductor devices are often sealed with an epoxy resin composition. However, recently, the degree of integration of these semiconductor devices has been increasing, and the chip size has been increasing accordingly.
On the other hand, package external dimensions have been reduced in size and thickness in response to demands for smaller and lighter electronic devices. Further, as for the method of attaching the semiconductor component to the circuit board, the surface mounting of the semiconductor component has been often performed to increase the density of the components on the board.

[0004] When a semiconductor device is surface-mounted, it is common to immerse the entire semiconductor device in a solder bath or to pass the semiconductor device through a high-temperature zone in which the solder melts. Cracks occur, and peeling occurs at the interface between the lead frame or chip and the sealing resin. Such cracks and peeling become more remarkable when the sealing resin layer of the semiconductor device absorbs moisture before the thermal shock at the time of surface mounting. However, in the actual work process,
Moisture absorption of the sealing resin layer is inevitable, and thus the reliability of the semiconductor device sealed with the epoxy resin composition after mounting may be significantly impaired. For this reason, as a countermeasure against such popcorn, low moisture absorption has been performed by filling a high amount of filler into the epoxy resin composition. Further, in order to improve the moldability of the thin package, the viscosity of the epoxy resin composition has been reduced, and in order to further improve the productivity, a fast-curing catalyst has been studied for improving the molding cycle.

However, when a conventional curing catalyst, for example, a tertiary amine compound, a tertiary phosphine compound, or a derivative thereof is used, there is a problem that the viscosity increases during kneading.

On the other hand, imidazole derivatives are disclosed in JP-A-58-76420 and JP-A-58-103525.
JP-A-57-100128, Japanese Patent Publication No.
No. 18853 discloses that a curing agent having good storage stability and excellent moisture resistance is provided by using a curing agent for epoxy resin obtained by reacting 2-methylimidazole with pyromellitic anhydride and trimellitic anhydride. Epoxy resin compositions have been proposed.

However, these curing catalysts are inadequate in rapid-curing properties and must be used in large quantities, which degrades the storage stability of the epoxy resin composition. In addition, if these curing agents and curing accelerators are simply used in combination, an epoxy resin composition which gives a cured product having good storage stability, good fluidity, and excellent properties such as fast curing and moisture resistance. It was difficult to get things.

[0008] The present invention has been made in view of the above circumstances,
Trimellitic anhydride modified which can be used as a curing accelerator to obtain an epoxy resin composition which gives a cured product with good storage stability, good fluidity, and excellent properties such as fast curing and moisture resistance. An object of the present invention is to provide an imidazole compound, an industrially advantageous production method of the compound, and a curing accelerator effective for an epoxy resin composition.

[0009]

Means and Action for Solving the Problems The present inventors have
As a result of intensive studies to solve the above problems, as shown in the following reaction formula, by reacting trimellitic anhydride and 2-phenyl-4-methyl-5-hydroxymethylimidazole in methyl cellosolve, An epoxy resin composition comprising a trimellitic anhydride-modified imidazole compound represented by the following structural formula (1) and an epoxy resin, a curing agent, and an inorganic filler as required. When blended as a curing accelerator, it is possible to obtain an epoxy resin composition which has good storage stability and fluidity, and is excellent in fast curing property and moisture resistance and which gives a cured product having excellent adhesion. They have found what they can do and accomplished the present invention.

[0010]

Embedded image

Accordingly, the present invention provides a method for producing a trimellitic anhydride-modified imidazole compound represented by the above formula (1), which comprises reacting trimellitic anhydride with 2-phenyl-4-methyl-5-hydroxymethylimidazole in methyl cellosolve. Provided are a method for producing a trimellitic anhydride-modified imidazole compound represented by the formula (1) and a curing accelerator for an epoxy resin composition comprising the trimellitic anhydride-modified imidazole compound represented by the formula (1).

Hereinafter, the present invention will be described in more detail. The trimellitic anhydride-modified imidazole compound of the present invention is represented by the following structural formula (1).

[0013]

Embedded image

The compound of the formula (1) can be obtained by reacting trimellitic anhydride with 2-phenyl-4-methyl-5-hydroxymethylimidazole in a methyl cellosolve solvent, especially 2-phenyl -4-
Methyl-5-hydroxymethylimidazole is heated and dissolved in methyl cellosolve, and thereafter, excess trimellitic anhydride is added thereto and reacted, and the obtained reactant is poured into a large amount of acetone to precipitate the reactant. ,Obtainable.

More specifically, 2-phenyl-4-methyl-5-hydroxymethylimidazole is hardly soluble at room temperature in methyl cellosolve, and requires heating for dissolution. The heating temperature is preferably from 70 to 130 ° C, more preferably from 100 to 120 ° C. In this case, the amount of methyl cellosolve is 300 to 400 parts by weight, preferably 300 parts by weight, based on 188 parts by weight (1 mol) of 2-phenyl-4-methyl-5-hydroxymethylimidazole. If less than 300 parts by weight, 2-phenyl-4
-Methyl-5-hydroxymethylimidazole may not be sufficiently dissolved, and the reaction may not proceed uniformly. Also, 4
If the amount is more than 00 parts by weight, the yield of a reaction product when precipitated in acetone may decrease. In addition, as a solvent, methylcellosolve is used alone, and if necessary, a solvent such as dimethylsulfoxide, dimethylformamide, diethylene glycol, pyridine and the like can be used together within a range not to impair the object of the present invention.

On the other hand, the amount of trimellitic anhydride is 100 to 200 parts by weight (1.0 to 1.2 times) based on 188 parts by weight (1 mol) of 2-phenyl-4-methyl-5-hydroxymethylimidazole. Mol), preferably 193
It is about part by weight (1.1 times mol). The reason for adding trimellitic anhydride in an amount larger than that of 2-phenyl-4-methyl-5-hydroxymethylimidazole is that trimellitic anhydride has good solubility in methyl cellosolve and acetone at room temperature.

This trimellitic anhydride can be removed by precipitating the compound obtained by the reaction in acetone and then washing the precipitate several times with acetone. The amount of acetone required to precipitate this compound is from 600 ml to 300 ml based on 188 parts by weight (1 mol) of 2-phenyl-4-methyl-5-hydroxymethylimidazole.
0 ml is preferable, and more preferably 1000 ml to 15
00 ml. If the amount of acetone is less than 600 ml, the yield of the reaction product may be deteriorated.
When the number is more than 1, the process cost increases and the cost may increase. In the washing step, it is necessary to pay attention to the absorption of moisture. Upon absorbing moisture, the anhydride reactant opens the ring to a dicarboxylic acid derivative. When this ring-opened dicarboxylic acid derivative is used as a curing catalyst for an epoxy resin composition, it is difficult to use it because it is incompatible.

In order to confirm the compound of the formula (1), it is effective to measure the melting point by instrumental analysis. The melting point of this compound is between 253 ° C and 258 ° C.

The trimellitic acid-modified imidazole compound of the above formula (1) of the present invention is effectively used particularly as a curing accelerator for an epoxy resin composition.

The epoxy resin composition containing the compound of the formula (1) will be described in detail. The epoxy resin composition contains an epoxy resin, a curing agent and, if necessary, an inorganic filler. In this case, any epoxy resin may be used as long as it has at least two epoxy groups in one molecule. For example, bisphenol A type epoxy resin, novolak type epoxy resin, alicyclic epoxy resin, glycidyl type epoxy resin, biphenyl type epoxy resin, naphthalene ring containing epoxy resin, cyclopentadiene containing epoxy resin, polyfunctional epoxy resin and the like can be mentioned. . Further, these epoxy resins may be appropriately combined. Of these, a biphenyl type epoxy resin or a naphthalene ring-containing epoxy resin is desirable for highly filling an inorganic filler. These epoxy resins preferably have a softening point of 50 to 100 ° C. and an epoxy equivalent of 100 to 400. Further, a brominated epoxy resin can be used for flame retardation.

On the other hand, as the curing agent, a known curing agent for an epoxy resin is used, and for example, a phenol resin can be used. Phenol resins include phenol novolak resin, triphenol methane resin, phenol aralkyl resin, naphthalene ring-containing phenol resin,
Examples thereof include those having two or more phenolic hydroxyl groups, such as a cyclopentadiene-containing phenol resin and a terpene ring-containing phenol resin. Among the phenol resins, those having a softening point of 60 to 120 ° C are preferable. The hydroxyl equivalent is preferably from 90 to 150. The amount of the curing agent used is a curing effective amount.For example, when a phenol resin is used, the amount of the phenol resin may be any amount as long as the equivalent ratio of the epoxy group to the hydroxyl group is in the range of 0.5 to 2.0. Although good, it is usually 30 to 100 parts by weight, preferably 40 to 70 parts by weight, per 100 parts by weight of the epoxy resin. If the amount is 30 parts by weight, sufficient strength cannot be obtained, while 100 parts by weight and unreacted phenol resin remain to lower the moisture resistance.

The inorganic filler is indispensable especially when the epoxy resin composition is used for semiconductor encapsulation, and is used for reducing the expansion coefficient of the encapsulant and reducing the stress applied to the semiconductor element. It is. As a specific example, fused silica or crystalline silica having a crushed or spherical shape is mainly used. In addition, alumina, silicon nitride, aluminum nitride and the like can also be used.

The average particle size of the inorganic filler is 5 to 40.
Micron ones are preferred. Particularly preferably, 10 to 30
Of micron. This kind of inorganic filler is desirably used after surface treatment with a silane coupling agent in advance. The compounding amount of the inorganic filler is preferably 200 to 900 parts with respect to 100 parts of the total amount of the resin components.
If the amount is less than 0 part, the expansion coefficient increases, the stress applied to the semiconductor element increases, and the element characteristics may deteriorate. If the amount exceeds 900 parts, the viscosity at the time of molding becomes high and the moldability deteriorates. There is.

Further, when the epoxy resin composition is used as a sealing material for semiconductors, it is preferable to add a silicone-based flexibility-imparting agent in order to reduce stress. Examples of the flexibility-imparting agent include silicone rubber powder, silicone gel, and a block polymer of an organic resin and a silicone polymer. Instead of adding such a flexibility-imparting agent, the surface of the inorganic filler may be treated with a two-pack type silicone rubber or silicone gel. The use amount of the above-mentioned flexibility imparting agent is preferably 0.5 to 10% by weight, particularly preferably 1 to 5% by weight of the whole composition, and when the use amount is less than 0.5% by weight, sufficient impact resistance is obtained. May not be provided, and if it exceeds 10% by weight, the mechanical strength may be insufficient.

[0025] The epoxy resin composition may contain other optional components, if necessary, as long as the effects of the present invention are not impaired. Such optional components include, for example, hardeners such as carnauba wax, higher fatty acids, and synthetic waxes, silane coupling agents, antimony oxide, and phosphorus compounds.

The compound of the formula (1) of the present invention described above can be used as a curing accelerator (curing catalyst) in such an epoxy resin composition.
In this case, when the compound of the formula (1) is mixed with the epoxy resin compound, a method of using the compound of the formula (1) as fine powder or a method of dispersing it in a phenol resin is used. is there. As the compounding amount,
The amount is 0.1 to 10 parts by weight, preferably 0.3 to 5.0 parts by weight, based on 100 parts by weight of the total amount of the resin components. 0.1
If the amount is less than 10 parts by weight, it cannot be cured in a short time.
If the amount is more than 10 parts by weight, the curing rate is too high to obtain a good molded product, and the storage stability may be reduced.

The epoxy resin composition contains, in addition to the curing catalyst of the present invention, imidazole or a derivative thereof, a phosphine derivative such as triphenylphosphine, trisP-methoxyphenylphosphine, tricyclohexylphosphine, or diazabicycloundecene. It can also be blended with a catalyst such as a cycloamidine derivative such as (DBU).

In the production of the above epoxy resin composition, predetermined amounts of the above-mentioned components are uniformly stirred and mixed, and kneaded and cooled with a kneader, roll, extruder or the like which has been previously heated to 70 to 95 ° C. , Pulverization and the like. There is no particular limitation on the order of mixing the components.
Such an epoxy resin composition can be suitably used for encapsulating semiconductor devices such as ICs, LSIs, transistors, thyristors, and diodes, and can be effectively used for manufacturing printed circuit boards. Here, when the semiconductor device is sealed, the molding temperature of the resin composition for semiconductor sealing is 150.
~ 180 ° C, post cure at 150 ~ 180 ° C 2-1
It is preferably performed for 6 hours.

[0029]

According to the trimellitic anhydride-modified imidazole compound and the process for producing the same of the present invention, the reaction between trimellitic anhydride and 2-phenyl-4-methyl-5-hydroxymethylimidazole is carried out in methyl cellosolve. Can be produced industrially advantageously, and this trimellitic anhydride and 2-phenyl-4-methyl-5
When an epoxy resin is prepared by using a reaction product with -hydroxymethylimidazole (compound of the formula (1)) as a curing catalyst, storage stability and fluidity are good, and fast curing and moisture resistance are excellent. An epoxy resin composition giving a cured product can be obtained.

[0030]

EXAMPLES The present invention will be described in detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples. The parts in each example are parts by weight.

Example 1 188 parts of 2-phenyl-4-methyl-5-hydroxymethylimidazole [manufactured by Shikoku Chemicals Co., Ltd., trade name 2P4MHZ] was placed in a 1 L four-necked flask equipped with a thermometer, stirrer and reflux condenser. ] And 300 parts of methyl cellosolve. While stirring, place the flask in 12
Heat to 0 ° C. to dissolve 2-phenyl-4-methyl-5-hydroxymethylimidazole. After heating and dissolving, a solution prepared by dissolving 193 parts of trimellitic anhydride (manufactured by Tokyo Chemical Industry Co., Ltd.) in 100 parts of methyl cellosolve was dropped from a dropping funnel, and reacted with 2-phenyl-4-methyl-5-hydroxymethylimidazole. I let it. After dropping, 120
The reaction was carried out for 1 hour at 50 ° C, and then cooled to 50 ° C. Then 3
1000 ml of acetone was put into a L beaker, and the above reaction mixture was charged with stirring, and a precipitate was collected by filtration. The filter residue was washed three times with 500 ml of acetone, stirred for 30 minutes, and filtered. Subsequently, the solvent was removed from the filtered residue at 100 ° C. under reduced pressure to remove methyl cellosolve, thereby obtaining a light red solid compound A (compound represented by the above formula (1)). The melting point of the obtained compound A was 255 ° C.

The results of elemental analysis of Compound A are shown below.

CH N Compound A Calculated value (%) 63.16 4.21 7.37 Actual value (%) 63.34 4.53 7.51 The infrared absorption spectrum of Compound A is shown in FIG. Show.

[Examples 2 to 5] In the same manner as in Example 1, 2-phenyl-4-methyl-5-hydroxymethylimidazole, trimellitic anhydride, methyl cellosolve used in the reaction, methyl used in the dropping were used. Using cellosolve and acetone required for precipitation in parts by weight in Table 1, compounds B, C, D and E as pale red solids were obtained.

[Comparative Examples 1 and 2] Light yellow solid compounds F and G were obtained in the same manner as in Example 1 except that dimethyl sulfoxide and dimethylformamide were used as a solvent in parts by weight in Table 1.

[0036]

[Table 1]

From the results shown in Table 1, trimellitic anhydride and 2
It was confirmed that in a system using methyl cellosolve as a reaction solvent for -phenyl-4-methyl-5-hydroxymethylimidazole, the compound of the formula (1) can be synthesized with high yield.

Examples 6 to 9, Comparative Examples 3 to 5 As shown in Table 2, an epoxy resin, a phenol resin, the compound A obtained in Example 1 were used, and the wax E 1.5
Part, 1 part of carbon black, brominated epoxy resin 6
Parts, 7 parts of antimony trioxide, 500 parts of fused quartz powder and 2 parts of γ-glycidoxypropyltrimethoxysilane were uniformly melt-mixed with a hot two roll, cooled and pulverized to prepare an epoxy resin composition. . As a comparative example, unreacted 2
Epoxy resin compositions were similarly prepared using -phenyl-4-methyl-5-hydroxymethylimidazole (2P4MHZ), and their physical properties were compared.

Various tests shown in the following (a) to (e) were conducted on these epoxy resin compositions. Table 2 shows the results.

(A) Spiral flow Using a mold conforming to the EMMI standard, 175 ° C., 70 k
g / cm ² .

(B) Hot hardness The hardness at the time of forming a 10 × 4 × 100 mm bending rod under the conditions of 175 ° C., 70 kg / cm ² and a forming time of 90 seconds was measured with a Barcol hardness meter.

(C) Storage stability The number of days when the spiral flow value was 80% of the initial value when each material was left at 25 ° C. was shown.

(D) Gelation time The gelation time of the composition was measured at 175 ° C.

(E) Melt viscosity 175 using a Koka type flow tester (manufactured by Shimadzu Corporation)
Measured in ° C.

[0045]

[Table 2]

From the results shown in Table 2, trimellitic anhydride and 2
A salt with -phenyl-4-methyl-5-hydroxyimidazole (compound of formula (1)) as a curing accelerator (curing catalyst)
The epoxy resin composition used as the resin has less increase in viscosity at the time of kneading than the epoxy resin composition using unreacted 2-phenyl-4-methyl-5-hydroxymethylimidazole, and has fluidity and storage. It was confirmed that the composition had good stability and provided a composition excellent in curability and the like.

[Brief description of the drawings]

FIG. 1 is an infrared absorption spectrum of a trimellitic anhydride-modified imidazole compound of the present invention.

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Claims (3)

(57) [Claims] 1. A trimellitic anhydride-modified imidazole compound represented by the following structural formula (1). Embedded image 2. Trimellitic anhydride and 2-phenyl-4
2. The reaction of -methyl-5-hydroxymethylimidazole with methyl cellosolve.
A process for producing the trimellitic anhydride-modified imidazole compound as described above. 3. A curing accelerator for an epoxy resin composition comprising the trimellitic anhydride-modified imidazole compound according to claim 1.