JPH0717720B2 - Bismaleimide composition - Google Patents

Description

TECHNICAL FIELD OF THE INVENTION The present invention has the general formula (I) [In the formula, R is Indicates a group.

Wherein X is a lower alkylene _{group, -O -, - SO 2 -} , - CO
− ] The present invention relates to a bismaleimide composition having a bismaleimide as a main component and having excellent thermosetting properties.

Bismaleimide typified by N, N ′-(4,4′-diphenylmethane) bismaleimide is a thermosetting resin that is particularly required to have heat resistance and dimensional stability, such as impregnated laminated sheet molded products in the electrical and mechanical fields. It is a compound useful as an imide resin raw material that is widely used.

Problems to be Solved by Conventional Techniques and Inventions Conventionally, for example, N, N ′-(4,4′-diphenylmethane)
Bismaleimide has the following formula According to the procedure, 1 mol of 4,4'-diaminodiphenylmethane and maleic anhydride were used in excess of 2 mol or more, and acetone or
In an organic solvent such as N, N′-dimethylformamide,
Ring-opening addition reaction N, N '-(4,4'-diphenylmethane)
Bismaleimidic acid, followed by dehydration cyclization using acetic anhydride as a dehydrating agent in the presence of a basic catalyst such as triethylamine and a metal salt catalyst such as cobalt acetate to give N, N ′.
-(4,4'-Diphenylmethane) bismaleimide has been obtained.

However, bismaleimide generally has two imide groups having a double bond in the molecule, but its polymerization activity is very low. Therefore, when the bismaleimide is molded into a thermosetting resin, the fact that the polymerization and curing reaction thereof progresses rapidly and uniformly sufficiently, in order to improve the productivity of the molded product production and to impart good heat resistance of the molded product. Is also required.

In addition, unless it has a uniform curing rate, the yield of the molded product is deteriorated and quality control becomes difficult.

Therefore, in order to obtain a bismaleimide having a high polymerization activity and a uniform cured molded product, it is modified with a diamine having an unsaturated group as a raw material, or a functional group compound serving as a crosslinking agent is added to the bismaleimide. A method of using the modified composition as a modified composition is known. Further, from the viewpoint of quality control, the crude bismaleimide after completion of the reaction is usually used as a resin raw material after being washed with water and purified by recrystallization.

However, these methods are costly, and if bismaleimide is purified and used, good moldings can be obtained with less impurities, but not only the yield loss due to refining loss but also the curing rate decreases and productivity is reduced. However, the curing time also greatly changes depending on the refining conditions.

In the work of the bismaleimide molding process, not only a simple treatment method is required, but also it is an important problem from the viewpoint of the performance of the obtained product that it has a certain appropriate heat curing rate.

As a result of intensive studies to solve the above problems, the present inventors have found that the bismaleimide compound represented by the general formula (I) has the following formula (II): [R is the same as R in the general formula (I). ] The curing rate can be freely adjusted by including the compound represented by the following in an amount of 0.8 to 5% by weight, and the composition containing the compound within a specific range has an appropriate curing rate and is heat cured. The inventors of the present invention have found that molding can be performed easily and with good reproducibility, and have reached the present invention.

Means for Solving the Problems The present invention provides a compound represented by the general formula (I): [In the formula, R is Indicates a group.

Wherein X is a lower alkylene _{group, -O -, - SO 2 -} , - CO
− ] In addition to the bismaleimide represented by the general formula (II) as a curing accelerator [In the formula, R is Indicates a group.

Wherein X is a lower alkylene _{group, -O -, - SO 2 -} , - CO
-, Which has the same meaning as R in formula (I). ] The bismaleimide composition which contains the compound represented by these from 0.8 to 5 weight% of the total amount is provided.

In the present invention, the compound represented by the general formula (II) is
It is a novel bismaleimide compound, for example, R is methylenedi p-phenylene. Is yellow, and the NMR spectrum is as shown in FIG.

The mass spectrum is shown by EI m / e = 358,278,155,105 CI m / e = 636 (parent ion), 557,358,278,105.

Although the compound represented by the general formula (II) can be synthesized, it can also be obtained as a by-product of the bismaleimide represented by the formula (I) by appropriately selecting the synthesis conditions. Therefore, after the preparation of the bismaleimide, the compound of the formula (II) can be isolated from the bismaleimide and then added in an amount necessary to adapt to the desired gelation time. Further, by appropriately selecting the synthesis conditions, if the content of the above-mentioned formula (II) compound by-produced during the production of bismaleimide is such that it can be adapted to the desired gelling time, the bismaleimide produced can be purified without repurification. The composition can be used as it is for the curing reaction. However, separately synthesizing the formula (II) compound is disadvantageous in terms of productivity, and the content of the formula (II) is changed due to subtle differences in the synthesis conditions during the production of bismaleimide. Strict synthesis conditions are required for the curing reaction without repurification. Therefore, after the bismaleimide is produced, the compound of the formula (II) is isolated from the bismaleimide, and then a necessary amount is added so as to adapt to the desired gelation time, thereby obtaining a resin composition having a stable gelation time. Is the preferred method.

The composition of the present invention is required to contain the compound of the general formula (II) in an amount of 0.8 to 5% by weight based on the whole bismaleimide. By maintaining the content in this range, the curing time is 1 to 8%. It can be controlled within minutes.

If the content of the compound of general formula (II) exceeds 5% by weight, the curing time will be less than 1 minute. If the curing time is less than 1 minute, not only the work during molding becomes difficult, but also the quality varies. Further, when the content of the compound of the general formula (II) is less than 0.8% by weight, the curing time exceeds 8 minutes and the productivity during the curing reaction is deteriorated. Therefore, in the present invention, it is optimal to provide a curing time of about 4 to 5 minutes, and the content of the compound of formula (II) is appropriately determined according to the curing time.

As described above, the composition of the present invention can be obtained by a method according to a conventional method for producing a bismaleimide, but in that case, the compound of the formula (II) is contained in the bismaleimide composition within a specific range. For this purpose, it is necessary to synthesize it under specific reaction conditions and use it without performing recrystallization purification.

In the method for producing the composition of the present invention, 2.0 to 2.4 mol of maleic anhydride is used per 1 mol of diamine, and bismaleamide is prepared by a ring-opening addition reaction in an organic solvent such as acetone or N, N'-dimethylformamide according to a conventional method. Acid and then acetic anhydride as a dehydrating agent in the presence of a basic catalyst such as triethylamine and a metal salt catalyst such as cobalt acetate.
Cyclodehydrate at ~ 80 ° C. Then, the obtained reaction liquid is dropped into a non-solvent such as water, or the reaction liquid is dropped into a non-solvent to precipitate crystals, followed by filtration, washing with water and drying.

If the content of the compound of the formula (II) contained in the crude bismaleimide obtained at this stage is suitable for the desired gelling time, the composition is directly subjected to the curing reaction. Usually, the crude bismaleimide thus obtained is recrystallized, the compound of the formula (II) obtained from the filtrate is isolated and purified, and added to the recrystallized purified bismaleimide so as to adapt to the gelation time. And subject to curing reaction.

In the preparation of the bismaleimide composition of the present invention, not only the compound of the general formula (II) but also about 3 to 4 as a by-product.
% Formula (III) compound [In formula, R is the same as R of general formula (I). ] Is also generated and is contained in the bismaleimide composition, but this compound does not affect the gelation time and can be used without removal.

The composition ratio of the compound of the formula (II), which is one of the by-products, and the compound of the formula (III) contained in the bismaleimide composition of the compound of the formula (I) is as follows. It is possible to use within a specific range,
It can be slightly increased or decreased depending on the time and temperature during the dehydration cyclization reaction in the production process.

Usually, in the dehydration cyclization reaction, a reaction time of about 2 hours is provided, but in the present invention as well, it is preferable that the reaction time is 2 to 3 hours. When the time exceeds, the number of compounds of formula (III) increases,
The amount of the compound of the formula (II) tends to decrease slightly. The reaction time is usually in a wide range of 20 to 100 ° C, but in the present invention, it is preferable to carry out the reaction at 30 to 80 ° C, preferably 50 to 60 ° C. When the reaction time becomes shorter, unreacted substances remain, and when the reaction temperature becomes higher, the amount of the compound of formula (III) increases and
I) The compound tends to decrease slightly. Therefore, a desired compound of formula (II) can be contained by appropriately determining these reaction conditions according to the amount of maleic anhydride used.

In the present invention, as the diamine used as the raw material of the bismaleimide, metaphenylenediamine, 2,4-diaminotoluene, 4,4'-diaminodiphenylmethane, 3,3-diaminodiphenylsulfone, 4,4'-diaminodiphenyl ether. , 3,3-diaminobenzophenone and the like, bismaleimide obtained using these diamines, for example, since all peaks of the same pattern can be obtained by liquid chromatography analysis method, the formula in bismaleimide ( The qualitative and quantitative determination of the by-products corresponding to II) and formula (III) can be confirmed.

Examples 1 to 5 In a flask, 41.5 g (0.423 mol) of maleic anhydride was dissolved in 120 g of acetone and stirred while keeping the internal temperature at 25 to 30 ° C.
A solution prepared by dissolving 40.0 g (0.202 mol) of 4,4'-diaminodiphenylmethane in 80 g of acetone was added dropwise over 1 hour.
Yellow crystals were deposited at the same time as the dropping, and 3 more after the dropping was completed.
After stirring the reaction solution at 25 ° C. for an hour, 9.6 g of triethylamine was added, and the mixture was stirred for 30 minutes. Further, 0.04 g of cobalt acetate, 0.40 g of magnesium oxide and 52.0 g of acetic anhydride were added, and the internal temperature was raised to 55 ° C over 15 minutes. After the temperature had risen, the mixture was stirred for 2 hours while maintaining the temperature at 55 ° C, the reaction solution was cooled to 35 ° C, and 500 ml of water was added dropwise over 20 minutes while continuing stirring. Then, stirring was continued for 1 hour to cause precipitation, and the precipitate was filtered, sludge was performed twice with 500 ml of water, and dried at 60 ° C. for 2 hours to obtain the desired bismaleimide powder.

The bismaleimide powder thus obtained [N, N'-
The compositional analysis of (4,4′-diphenylmethane) bismaleimide] and the thermal curing time (gelling time) at 200 ° C. were measured as follows.

Analyzing Method of Composition The composition was analyzed by high performance liquid chromatography (HLC) under the following conditions.

Column: JASCO Corporation Fine Gel 101 φ6mm × 500mm Moving layer: Terahydrofuran Flow rate: 0.5ml / min Detector: JASCO Corporation UV spectrophotometer (Absorbance 254n
From this, a chart as shown in FIG. 1 was obtained, and the retention time and the content were calculated from this.

Measuring method for gelation time Approximately 1 g of bismaleimide is placed on a stainless steel heating plate kept at 200 ° C ± 1 ° C and kneaded with a spatula of stainless steel. It was time.

The results are shown in Table 1 together with the compositions (Examples 2 to 5) produced by changing the amount of maleic anhydride used.

The chart is shown by NMR (solvent CDC1 ₃₎ of the compounds of the obtained isolated from in composition (II) in Figure 2.

For comparison, after the reaction, the bismaleimide powder obtained in Example 1 was recrystallized twice with methyl ethyl ketone.
In this purified bismaleimide composition, the (II) compound is 0.00
1% was included. It took more than 20 minutes to gel this.

Further, 20 mg each of the bismaleimide powder obtained in Example 1 and the purified bismaleimide powder obtained by recrystallizing the powder were collected, and the temperature was raised to 10 ° C./min in the open air and the DTA sensitivity was 250 μVFS.
As a result of measuring the differential thermal behavior under the conditions of, the respective 5% thermal loss (at 200 ° C base point) was 503 ° C and 505 ° C, there was almost no difference, and the heat resistance was higher than that of the pure bismaleimide. It was as good as that.

Example 6 The crude bismaleimide powder obtained in Example 5 was recrystallized twice with methyl ethyl ketone. The purified bismaleimide contained 0.001% of the compound (II).

In addition, volatilize the methyl ethyl ketone of the recrystallization filtrate,
It was washed twice with warm water at ℃ and once with methanol and dried to obtain a powder. The composition of this powder is 65 (II) compounds.
% (35%) of the compound (III) (analysis value from high performance liquid chromatography).

The compound (II) and the compound (II
The mixture of I) was mixed with the above purified bismaleimide at the ratio shown in Table 2 and the gelation time was measured.

Example 7 A diamine was prepared in the same manner as in Example 1 except that 3,4′-diaminodiphenylmethane was used instead of 4,4′-diaminodiphenylmethane and 4,4′-diaminodiphenyl ether was used. The gelling times of the obtained bismaleimide powder and those obtained by recrystallizing these bismaleimide powder in the same manner as in Example 1 were measured. The results are shown in Table-3.

Example 8 In exactly the same manner as in Example 1 except that the diamines in Table 3 were used,
Various bismaleimides were obtained, which are described in Example 1.
The composition was analyzed under the same conditions as the HLC analysis.

The chart showed a pattern similar to the chart shown in FIG. 1, other impurities were not confirmed, and the content of the by-product (II) compound calculated from this was almost the same as in Example 1. . The HLC retention time is shown in Table 4.

[Brief description of drawings]

FIG. 1 shows N, N′-obtained by Example 1 of the present invention.
1 is a chart when a (4,4′-diphenylmethane) bismaleimide reaction composition is analyzed by high performance liquid chromatography. FIG. 2 is a component of the composition of the present invention. 1 is a chart obtained by NMR analysis of a by-product of N, N ′-(4,4′-diphenylmethane) bismaleimide contained in the bismaleimide of Example 1 [compound (II)].

Claims (1)

[Claims] 1. A general formula (I) [In the formula, R is Indicates a group. Wherein X is a lower alkylene _{group, -O -, - SO 2 -} , - CO
− ] To the bismaleimide represented by the general formula (II) [In the formula, R is Indicates a group. Wherein X is a lower alkylene _{group, -O -, - SO 2 -} , - CO
-, Which has the same meaning as R in formula (I). ] A bismaleimide composition containing 0.8-5 wt% of the compound represented by the following.