JP2003292581A - Curing accelerator for epoxy resin - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a curing accelerator for an epoxy resin having excellent curing characteristics equal to or higher than those of a conventional accelerator and producible for a short time without forming toxic benzene as a by-product. <P>SOLUTION: The curing accelerator for the epoxy resin comprises a product of a melt reaction of a phenolic resin with tetraphenylphosphonium tetra(4- methylphenyl)borate represented by formula (1) as an active component. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an epoxy resin curing accelerator.

[0002]

2. Description of the Related Art Epoxy resins have excellent mechanical, chemical and electrical properties, so that various electrical components such as coils and capacitors in the form of adhesives, paints and casting materials,
Alternatively, it is widely used for insulating and sealing semiconductor devices and integrated circuits.

Conventionally, in order to cure an epoxy resin,
Curing agents such as amine type, phenol type and acid anhydride type are used. Further, usually, the curing reaction is difficult to proceed with only the curing agent, so that the curing accelerator is added. As this curing accelerator, triphenylphosphine, imidazoles, etc. are known.

An epoxy resin composition is obtained by adding an epoxy resin, an inorganic filler and the like in addition to these curing agents and curing accelerators.

However, when the above-mentioned triphenylphosphine or imidazole is used as the curing accelerator, there is a problem that the storage stability of the epoxy resin composition deteriorates.

[0006] There are known some curing accelerators that solve this problem and do not reduce storage stability, and methods for using them.

First, in Japanese Patent Publication No. 56-45491 and Japanese Patent Publication No. 61-296019, tetraphenylphosphonium tetraphenylborate (hereinafter referred to as "T
Abbreviated as “PP-K”. "TPP-K" is a registered trademark of the applicant. Examples of the use of) as a curing accelerator are described.

However, since TPP-K has poor compatibility with resins, the curing accelerating action is not sufficient by simply adding it to the epoxy resin composition. Therefore, in recent years, a method has been disclosed in which TPP-K and a phenolic resin are melt-mixed or reacted and then used to improve the catalytic activity.

For example, in JP-A-10-251383, a phenolic resin and tetra (substituted phenyl) phosphonium tetra (substituted phenyl) borate are heated and mixed at 205 to 235 ° C. for 1 hour and then used as a curing accelerator. When used, the curability of the epoxy resin composition,
It is described that it has excellent storage stability. An example of TPP-K is shown therein as a curing accelerator.

Further, in Japanese Patent Laid-Open No. 2001-151863, when a reaction product of TPP-K and a phenol novolac compound is used as a curing accelerator, package voids after curing and mold stains during continuous molding are significantly caused. It is described that it can be reduced to.

However, (a) since the compatibility of TPP-K with the phenol novolac compound is poor, it actually takes a long time for the mixture of TPP-K and the phenolic resin to become uniformly transparent. And (b) Japanese Patent Laid-Open No.
As described in Japanese Patent Publication No. 001-151863, there is a drawback that benzene, which is a problem in terms of safety and health, is by-produced.

On the other hand, in JP-A-8-165331, tetraphenylphosphonium tetra (methylphenyl) borate is used as a curing accelerator in order to provide an epoxy resin composition having an excellent balance between curability and storage stability. Is described.

Further, JP-A-8-169892 describes that tetraphenylphosphonium tetra (4-methylphenyl) borate is useful as an industrial antiseptic / antifungal agent.

[0014]

[Problems to be Solved by the Invention] Under the above circumstances,
There is a demand for the development of a curing accelerator that has curing characteristics equivalent to or better than the reaction product of TPP-K and a phenolic resin, has good workability during production, and does not produce harmful benzene as a by-product. That is, the subject of the present invention is substantially T
It is a curing accelerator that has the same function as the reaction product of PP-K and phenolic resin, and in the melting reaction with phenolic resin, the reaction is completed in a short time without producing harmful benzene as a by-product. It is to provide an epoxy resin curing accelerator that can be produced.

[0015]

[Means for Solving the Problems] In view of such a situation,
The present inventors have conducted extensive studies to achieve the above-mentioned object. As a result, a specific tetraphenylphosphonium tetra (4-methylphenyl) borate (hereinafter abbreviated as compound (1)) represented by the formula (1) was selected from various phosphonium borates, and It has been found that when a phenolic resin is reacted, less harmful benzene is produced as a by-product and less harmful toluene is produced as a by-product.

Further, it has been found that the compound (1) completes the melting reaction with the phenolic resin in a short time. Furthermore, when the reaction product of the compound (1) and the phenolic resin is used as a curing accelerator, it exhibits exactly the same curing promoting action as when the reaction product of the TPP-K and the phenolic resin is used as the curing accelerator. It was confirmed. The present invention has been completed based on these findings.

That is, the present invention is summarized as follows. (1) Phenolic resin and the following formula (1)

[Chemical 4] An epoxy resin curing accelerator, characterized by containing as an active ingredient a product of a melt reaction with tetraphenylphosphonium tetra (4-methylphenyl) borate represented by

(2) It can be obtained by melt-reacting tetraphenylphosphonium tetra (4-methylphenyl) borate represented by the formula (1) in a ratio of 2 to 40 parts by weight with respect to 100 parts by weight of a phenolic resin. An epoxy resin curing accelerator comprising the product as an active ingredient.

(3) As a phenolic resin, the following formula (A)

[Chemical 5] An epoxy resin curing accelerator characterized by using a phenol novolac resin represented by (m is a positive integer including 0).

(4) The following formula (B) as a phenol resin

[Chemical 6] An epoxy resin curing accelerator characterized by using a phenol aralkyl resin represented by (n is a positive integer including 0).

Therefore, the present invention provides an epoxy resin curing accelerator containing as an active ingredient the product of the melt reaction between the compound (1) and the phenolic resin.

In the tetraphenylphosphonium tetra (methylphenyl) borate used as a raw material, the epoxy resin curing accelerator according to the present invention is a compound of the specific formula (1), that is, 4-phenyl group of borate.
It is essential to select tetraphenylphosphonium tetra (4-methylphenyl) borate (compound (1)) having a methyl group bonded to the position.

On the other hand, a reaction product of tetraphenylphosphonium tetra (3-methylphenyl) borate having a methyl group bonded at the 3-position (hereinafter abbreviated as compound (2)) and a phenol resin is used. When used as an epoxy resin curing accelerator, the curability is poor and tetraphenylphosphonium tetra (2-
Methylphenyl) borate is actually difficult to synthesize the compound itself.

The product of the melt reaction between the compound (1) and the phenolic resin can be used as an epoxy resin curing accelerator as it is, but other known curing accelerators may be used as necessary as long as the curing characteristics are not impaired. For example, it may contain triphenylphosphine or the like.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION (1) Method for Producing Epoxy Resin Curing Accelerator First, the compound (1) used in the present invention is a known compound. This compound can be synthesized based on the method described in JP-A-8-169892.

The mixing ratio of the compound (1) and the phenolic resin in the epoxy resin curing accelerator according to the present invention is not particularly limited, but 2 to 40 parts by weight of the compound (1) relative to 100 parts by weight of the phenolic resin. Is preferable, and more preferably 5 to 30 parts by weight.

The temperature for the melt reaction is 100 to
250 ° C. is preferable, and 180 to 220 is more preferable.
℃. On the other hand, when the reaction temperature is lower than 100 ° C, the rate of formation of the curing catalyst becomes slow, and conversely, the reaction temperature becomes 2
When it is higher than 50 ° C, the decomposition reaction of the compound (1) occurs.

The heating and mixing time is such that the mixture is stirred until it becomes uniform and transparent. The required time is 30 at 200 ℃
Minutes to 2 hours are required. The determination of the end point is clear because it becomes uniformly transparent as the heating and mixing time elapses. By this melting reaction, as described in JP-A-2000-80155, the aryl group bonded to the borate side of the tetraarylphosphonium tetraaryl borate is eliminated, and the phenolic hydroxyl group of the phenolic resin and boron are bonded. A curing accelerator can be obtained. here,
The elimination of the aryl group bonded to the borate side can be confirmed from the fact that the liquid distilled during the reaction treatment of the compound (1) and the phenolic resin is toluene and does not contain benzene.

In the present invention, when oxygen is present in the reaction system, the compound (1) may be oxidized by oxygen to cause a decomposition reaction. Therefore, the reaction may be performed in an atmosphere of an inert gas such as nitrogen. preferable. When mixing the compound (1) and the phenolic resin, a solvent can be used if necessary. As such a solvent, for example,
Examples thereof include alcohols such as ethanol and butanol, ketones such as methyl isobutyl ketone, and toluene.

The epoxy resin curing accelerator obtained by the present invention is used by blending it with an epoxy resin composition. The epoxy resin composition contains the epoxy resin curing accelerator, the epoxy resin, and a phenolic curing agent. As an epoxy resin composition, at least 1
There is no particular limitation as long as it is an epoxy resin having two or more epoxy groups in the molecule. Examples thereof include cresol novolac type epoxy resin, phenol novolac type epoxy resin, biphenyl type epoxy resin, bisphenol A type epoxy resin and alicyclic epoxy resin. The phenol-based curing agent is not particularly limited as long as it is a phenol-based resin having two or more hydroxyl groups in at least one molecule. Examples thereof include phenol novolac resin, cresol novolac resin, and phenol aralkyl resin.

The compounding ratio of the epoxy resin and the phenol resin-based curing agent is such that the phenolic hydroxyl group is 0.5 to 1.5 mol, particularly 0.8 to 1.2 mol, relative to 1 mol of the epoxy resin. Is preferred.

The phenolic hydroxyl group includes the phenolic hydroxyl group in the phenolic resin used in the production of the curing accelerator of the present invention.

(1) Method of Using Epoxy Resin Curing Accelerator The epoxy resin curing accelerator of the present invention is used as follows. That is, the compounding amount of the curing accelerator composed of the reaction product of the compound (1) of the present invention and the phenolic curing agent is as compound (1) with respect to 100 parts by weight of the total compounding amount of the epoxy resin and the phenolic curing agent. 0.1 to 20 parts by weight, particularly 0.5 to 10 parts by weight is preferable.

Furthermore, the epoxy resin composition can, if desired, contain flame retardants and inorganic fillers as additional components.

Such flame retardants can be metal hydrates, phosphine oxides, and the like.

As the inorganic filler, fused silica,
It can be crystalline silica, alumina, etc.

In order to produce an epoxy resin composition by blending the above composition, it is desirable to heat and knead the above-mentioned components including the curing accelerator of the present invention at, for example, 50 to 150 ° C., and kneader or roll. It can be obtained using a known kneading method using, for example.

[0038]

EXAMPLES Next, reference production examples for synthesizing the compound of the general formula (1) used in the present invention and known compounds similar thereto will be shown. Using these, examples and comparative examples will be shown. The utility will be specifically described, but the present invention is not limited to these examples.

(Reference Production Example 1) Tetraphenylphosphonium tetra (4-methylphenyl) borate: Synthesis of compound (1) Synthesis was carried out based on the description in JP-A-8-169892. The melting point of the obtained crystal was 247 ° C., which was in agreement with the physical properties described in the above publication (yield 85%).

(Reference Production Example 2) Tetraphenylphosphonium tetra (3-methylphenyl) borate: Synthesis of compound (2) Synthesis was carried out based on the description in JP-A-8-169892. The melting point of the obtained crystal was 195 ° C. (yield 71%).

(Reference Production Example 3) Synthesis of tetraphenylphosphonium tetra (2-methylphenyl) borate Synthesis was carried out based on the description in JP-A-8-169892. No intermediate sodium tetra (2-methylphenyl) borate was produced, and the target compound could not be synthesized.

Example 1 Compound (1) was added to a 500 ml separable flask in an amount of 10 times.
g, and phenol novolac resin [SHONOL B
RG-556 (Showa High Polymer Co., Ltd. trade name, phenol equivalent 103)] was added to 40 g, and under a nitrogen atmosphere, 200
The melt reaction was carried out at ° C. When the by-product distilled during this period was confirmed by gas chromatography, the by-product was toluene, and benzene was not detected at all. In addition, at the beginning of the reaction, the entire inside of the flask was clouded, but 3
After 0 minutes, the reaction mixture became a yellow, transparent and transparent melt.
The stirring was continued for another 1 hour and 30 minutes (total 2 hours). Then, residual toluene was removed at 120 ° C. under a reduced pressure of 2 mmHg. After cooling, the solidified product was pulverized to obtain 46 g of a reaction product of compound (1) and a phenol novolac resin (abbreviated as “reaction product (1-A)”). The results are shown in Table 1.

Example 2 Phenol aralkyl resin [M
EK-7800S (Meiwa Kasei Co., Ltd. trade name, phenol equivalent 175)] was used in the same manner as in Example 1 except that 40 g of the reaction product of the compound (1) and the phenol aralkyl resin (“reaction product (1- Abbreviated as "B)") 46 g was obtained (reaction time was 2 hours). Also in this case, the by-product distilled out was toluene, and benzene was not detected at all.
The results are shown in Table 1.

Comparative Example 1 A reaction product (abbreviated as “reaction product (2-A)” in the same manner as in Example 1 except that the compound (2) was used in place of the compound (1) used in Example 1). .) 46 g was obtained. The results are shown in Table 1.

Comparative Example 2 A reaction product (abbreviated as "reaction product (2-B)" in the same manner as in Example 2 except that the compound (2) was used in place of the compound (1) used in Example 2). .) 46 g was obtained. The results are shown in Table 1.

Comparative Example 3 Instead of the compound (1) used in Example 2, TPP was used.
The same operation as in Example 2 was performed except that -K was used.
In this case, it was not uniform even after heating and stirring at 200 ° C. for 2 hours, but after 2 hours, cooling and pulverization were performed to obtain 46 g of a reaction product (abbreviated as “reaction product (K-B2)”). The distillate by-product in this case was benzene. The results are shown in Table 1.

Comparative Example 4 The same operation as in Comparative Example 3 was performed. Although Comparative Example 3 was completed by the reaction for 2 hours, it was not completed here in 2 hours, and the inside of the flask became homogeneous and transparent at the time when the reaction time was 4 hours. Therefore, cooling and crushing was performed at that time. 46 g of a reaction product (abbreviated as “reaction product (K-B4)”) was obtained. The results are shown in Table 1.
Shown in.

[0048]

[Table 1]

Test Examples 1 and 2 and Comparative Test Examples 1 to 4 The components shown in Table 2 were uniformly melt-mixed at 120 ° C. and cooled,
It was pulverized to obtain an epoxy resin composition. For these compositions, the gelling time was 175 according to JIS K5059.
It was measured by the hot plate method at ℃. The results are shown in Table 2.

[0050]

[Table 2]

As shown in Table 2, when the reaction product of Example 1 [reactant (1-A)] and the reaction product of Comparative Example 1 [reactant (2-A)] are compared, a comparative example is obtained. The reaction product of No. 1 has a slow gel time (gelling time) and is inferior in curability. Similarly, the reaction product of Example 2 [reactant (1-B)] and Comparative Example 2
When compared with the reaction product [reactant (1-B)] of Example 1, the reaction product of Comparative Example 2 has a slow gel time and is inferior in curability.
That is, it is more excellent in curability that the methyl group on the borate side is bonded to the para position rather than the meta position.

Further, as shown in Table 1, comparing Example 2 with Comparative Examples 3 and 4, in the case of the compound (1) of Example 1, the conventional compounds of Comparative Example 3 and Comparative Example 4 were compared. TPP-
Compared with the case of K, the time required for synthesizing the curing accelerator is shorter.

Further, in Example 1 and Example 2 which are the methods of the present invention, the by-products are all toluene, and benzene, which has a serious problem of toxicity as in the conventional case, is not generated.

EFFECT OF THE INVENTION The specific epoxy resin curing accelerator of the present invention exhibits the same curability as the curing accelerators known at present, but the production time is short, and the by-product is toluene, which has low toxicity. Excellent in terms of work efficiency and health and safety.

Claims (4)

[Claims] 1. A phenolic resin and the following formula (1): An epoxy resin curing accelerator, characterized by containing as an active ingredient a product of a melt reaction with tetraphenylphosphonium tetra (4-methylphenyl) borate represented by 2. With respect to 100 parts by weight of the phenolic resin,
A product obtained by melting and reacting tetraphenylphosphonium tetra (4-methylphenyl) borate represented by the formula (1) at a ratio in the range of 2 to 40 parts by weight, as an active ingredient. Item 2. The epoxy resin curing accelerator according to Item 1. 3. A phenolic resin having the following formula (A): The epoxy resin curing accelerator according to claim 1, wherein a phenol novolac resin represented by (m is a positive integer including 0) is used. 4. A phenolic resin represented by the following formula (B): The epoxy resin curing accelerator according to claim 1, wherein a phenol aralkyl resin represented by (n is a positive integer including 0) is used.