JP3433482B2 - Method for producing bismaleimide - Google Patents

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing bismaleimide. The bismaleimide obtained by the method of the present invention is useful as a laminate material, a sealing material, an electric insulating material, a conductive paste, an adhesive and a structural material.

[0002]

2. Description of the Related Art Conventionally, as a method for producing polymaleimide, a dehydrating agent such as acetic anhydride is used in the presence of a ketone solvent such as acetone or a polar solvent such as N, N-dimethylformamide, and a base and a metal such as triethylamine. A method of adding a compound and performing a dehydration ring closure reaction (Japanese Patent Publication No. 59-52660).
JP-A-63-66164), but the ring-closing reaction does not proceed sufficiently by this method, and the polymaleimide produced has a considerable amount of unringed maleamic acid. Furthermore, the method using acetic anhydride as a dehydrating agent requires a complicated step of removing acetic acid by-produced by the reaction.

On the other hand, as a method without using a dehydrating agent, polyamine and maleic anhydride are reacted in a mixed solvent of an aromatic solvent and an aprotic polar solvent to obtain a polyamic acid, and then an acid catalyst is used. A method for obtaining a highly pure polymaleimide by carrying out a dehydration ring closure reaction using the same (JP-A-60-26062).
3, 63-301226, etc.) is known. However, the method of reacting in a mixed solvent of these aromatic solvents and an aprotic polar solvent gives 2,2-bis [4-
When an etherimide type bismaleimide is produced from an aromatic diamine such as (4-maleimidophenoxy) phenyl] propane, the solvent is included in the crystal when crystallized in an aromatic solvent.

According to Japanese Patent Laid-Open No. 1-211563,
As a method for producing an etherimide type bismaleimide, benzene, toluene, ethylbenzene, in a mixed solvent of an aromatic solvent such as chlorobenzene and an aprotic polar solvent, after an addition reaction at a low temperature, a ring closure reaction is carried out, An example is given in which crystals of bismaleimide are precipitated in a state where unreacted bismaleamic acid remains considerably, and the obtained crystals are washed with methanol to obtain high-purity bismaleimide that does not include a solvent.

However, when trying to obtain a bismaleimide from a reaction solution containing little or no maleamic acid in a mixed solvent of the above aromatic solvent and aprotic polar solvent, the reaction conditions are optimized. Aromatic solvent is included in the crystal, it is not possible to completely remove the included solvent from the precipitated crystal by a normal drying method, and if this is used for the curing reaction as it is, the problem of foaming occurs. Occurs. Therefore, in order to obtain a high-purity product which does not include a solvent, a method of recrystallizing it with a low boiling point halogenated hydrocarbon solvent (see JP-A-1-238568) or a bismaleimide obtained by drying is used in tetrahydrofuran or acetone. It is necessary to use a method of dissolving in water and reprecipitating with water (JP-A-3-145462), which complicates the manufacturing process.

[0006]

DISCLOSURE OF THE INVENTION The present invention provides a method for producing an etherimide bismaleimide using an aromatic hydrocarbon and an aprotic polar solvent, which is industrially advantageous for producing a high purity bismaleimide containing no solvent. , Is intended to provide a simple way to get.

[0007]

That is, the present invention has the general formula [I]

[0008]

[Chemical 3]

(In the formula, R ^{1 to} R ⁴ represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, R ⁵ represents a hydrogen atom or a methyl group, and R ⁶ represents a hydrogen atom or a methyl group. Or a phenyl group) and a maleic anhydride represented by the general formula [II]

[0010]

[Chemical 4]

(In the formula, X and Y are halogen atoms and have 1 carbon atom.
~ 2 alkyl group, n is an integer of 1-3, n
In the case of = 1, X and Y are in the para-positional relation), and the addition reaction is carried out at 70 to 150 ° C. in a mixed solvent of an aromatic solvent selected from substituted benzenes represented by After obtaining bismaleamic acid, dehydration ring closure reaction is carried out in the presence of an acid catalyst to azeotropically remove water by-produced with an aromatic solvent, and the reaction solution is cooled to precipitate and separate maleimide formed, and a high solvent-free solvent is included. Industrially advantageous general formula [III] characterized by obtaining pure bismaleimide

[Chemical 6] [III] A method for producing a bismaleimide represented by the formula ( wherein R ^{1 to} R ⁶ are as defined above) is provided.

(Reaction Solvent) The aromatic solvent represented by the above general formula [II] used as the mixed solvent is a solvent which is not included in bismaleimide and is capable of completely dissolving bismaleimide. Since these have 2 to 4 substituents on the benzene ring and are p-substitutes in the case of two, the environment around the benzene ring is crowded and sterically hinders inclusion. There is something. Specific examples include p-xylene, p-diethylbenzene, p-chlorotoluene, mesitylene and the like. Among these, p-xylene is particularly preferable because it has an appropriate boiling point and solubility with respect to bismaleimide.

As the aprotic polar solvent, a solvent which easily dissolves maleamic acid produced in the addition reaction, for example,
N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, amide solvents such as tetramethylureaic acid, and sulfur such as dimethyl sulfoxide. Examples of the solvent include phosphorus solvents such as hexamethylphosphoramide. The aprotic polar solvent preferably has a boiling point of 150 ° C. or higher and does not easily azeotrope with water, and among them, amide solvents are preferably used. The amount of the aprotic polar solvent in all the solvents is preferably small in terms of precipitation and separation of bismaleimide, and is usually 0.1 to 30% by weight,
It is preferably 1 to 20% by weight. The mixed solvent is 1 to 50 parts by weight, preferably 2 to 2 parts by weight with respect to 1 part by weight of amines.
Used in a proportion of 0 parts by weight.

The aromatic diamine represented by the above general formula [I] used for the production of (aromatic diamine) bismaleimide includes 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 2-bis [3-methyl-
4- (4-aminophenoxy) phenyl] propane,
2,2-bis [3-butyl-4- (4-aminophenoxy) phenyl] propane, 2,2-bis [3,5-dimethyl-4- (4-aminophenoxy) phenyl] propane, 1-phenyl- 1,1-bis [4- (4-aminophenoxy) phenyl] ethane, 1-phenyl-1,1-
Examples thereof include bis [3,5-dimethyl-4- (4-aminophenoxy) phenyl] ethane. Among these diamines, 2,2-bis [4- (4-
Aminophenoxy) phenyl] propane.

(Maleic anhydride) The ratio of maleic anhydride to the aromatic diamine is 0.9 to 5 mol, preferably 1.0 to 1. mol of maleic anhydride to 1 equivalent of all amino groups of the aromatic diamine. 3 mol is used.

(Addition reaction) The addition reaction between the aromatic diamine and maleic anhydride is carried out in the mixed solvent at 70 to 150 ° C.
To produce bismaleamic acid. If the addition reaction temperature is lower than 70 ° C., the reaction does not proceed sufficiently, and if it exceeds 150 ° C., the amount of the polymer increases, and the purity of the bismaleimide decreases. Specifically, maleic anhydride is dissolved in an aromatic solvent or a mixed solvent and heated to a predetermined temperature. After the aromatic diamine is dissolved in an aromatic solvent or a mixed solvent, it is dropped into the maleic anhydride solution. The dripping time is 0.5 to 5 hours, and after the dripping is finished, the reaction is continued by further heating for 0.1 to 5 hours to produce a slurry liquid of bismaleamic acid, and the point at which the diamine is exhausted is the end point. The addition reaction product liquid is then
An acid catalyst is added and the dehydration ring closure reaction is performed.

(Acid catalyst) As the acid catalyst used in the dehydration ring-closing reaction, inorganic acid catalysts such as sulfuric acid, sulfuric anhydride, phosphoric acid, polyphosphoric acid, metaphosphoric acid and condensed phosphoric acid, and p-toluenesulfonic acid, Trichloroacetic acid, trifluoroacetic acid,
Examples thereof include organic acid catalysts such as trifluoromethanesulfonic acid, and organic acid catalysts are preferably used. The amount of these acid catalysts used is 0.0 with respect to 1 equivalent of amino groups of amines.
001 to 1 mol, preferably 0.001 to 0.5 mol.

(Dehydration ring-closing reaction) The dehydration ring-closing reaction is carried out at a temperature of 80 to 200 ° C., preferably 80 to 1 after addition of the acid catalyst.
It is carried out at 50 ° C. and while azeotropically distilling off the produced water with the reaction solvent at a pressure in the range of 760 to 0.1 mmHg. The solvent azeotropically distilled with the produced water is returned to the reaction system after cooling and phase separation. The reaction is terminated at the point where the bismaleamic acid disappears, specifically, the point at which the heterogeneous system changes to a homogeneous system.
If the dehydration ring-closing temperature is lower than 80 ° C, the dehydration reaction is difficult to proceed, and if it exceeds 200 ° C, a large amount of polymer is produced.

(Post-Treatment Method) The reaction solution obtained as described above is washed with water and then left as it is, or concentrated and cooled to precipitate bismaleimide. The washing was performed with 0.1 part by weight of the produced bismaleimide contained in the reaction solution.
-20 parts by weight, preferably 0.3-10 parts by weight of water is added, and after stirring, the mixture is allowed to stand, separated from oily water, and washed. Stirring is generally performed by stirring at a rotation speed of 30 to 300 rpm for 3 to 30 minutes. Washing is performed 1 to 5 times, preferably 2 or more times, in a temperature range of 20 to 95 ° C.

Crystallization is performed at 60 ° C. or lower, particularly preferably 50.
It is carried out at a temperature of not more than 0 ° C. under agitation, and the agitation is continued for 30 minutes or more, preferably 1 hour or more after the first crystal precipitation. The precipitated bismaleimide is filtered off and dried to obtain the desired product. The drying is performed at a temperature of 50 ° C. to the melting point or lower for 1 to 100 hours, preferably 3 to 50 hours. The bismaleimide obtained by such a method is an oligomer and polymer component of 5% or less measured by the area percentage of a liquid chromatograph (differential refractive index detector), and a residual solvent measured by an absolute calibration curve method of a gas chromatograph (FID). It is a highly pure product with an amount of 1% by weight or less and an acid value titrated with an N / 10 KOH ethanol solution of 2.5 (mg · KOH / g) or less.

[0021]

The present invention will be described in detail below with reference to examples. Example 1 500 with cooler, thermometer, stirrer and water separator
A 3.5-mL four-necked flask was charged with 23.5 g of maleic anhydride and 140 g of p-xylene, and the internal temperature was adjusted to 100 ° C. Next, a solution of 41.0 g of 2,2-bis [4- (4-aminophenoxy) phenyl] propane dissolved in 90 g of p-xylene and 8.2 g of N-methyl-2-pyrrolidone was adjusted to an internal temperature of 100 ° C. While the solution was added dropwise over 1 hour, after completion, the mixture was further stirred at the same temperature for 1 hour to carry out an addition reaction.

Subsequently, 1.9 g of paratoluenesulfonic acid
Was added and the temperature was raised, and under normal pressure, under reflux of p-xylene (13
The ring-closing reaction was carried out by keeping the temperature at 8 ° C. for 2.4 hours. The water generated during this time was distilled out of the system together with p-xylene. After completion of the reaction, 100 g of pure water and a temperature of 90 to 95 ° C. for 4 hours
Washed twice. After washing with water, the reaction solution was heated to 70 to 80 ° C. under reduced pressure (200 to 10 mmHg) to give 135 g of p-xylene.
(Distillation rate to charged p-xylene 58.7%, residual p
-Xylene (95 g) was distilled off, and the mixture was cooled with stirring to precipitate bismaleimide (deposition temperature 52 ° C).
Stir for hours. The precipitate was filtered off and dried under reduced pressure at 50 ° C. for 24 hours and at 60 ° C. for 24 hours to obtain 51.9 g of a pale yellow bismaleimide powder (yield 91.1% based on the theoretical amount of bismaleimide). .

The melting point of this bismaleimide by the capillary method is 140 to 144 ° C., and the purity measured by the area percentage of a liquid chromatograph (differential refractive index detector) is 9
8.8%, residual solvent amount measured by gas chromatograph (FID) absolute calibration curve method is 0.8% by weight, N / 10K
The acid value titrated with OH-ethanol solution is 2.1 (mg
KOH / g).

Example 2 The aromatic solvent was replaced with mesitylene, and the reaction was carried out under reduced pressure and under reflux of mesitylene (temperature 110 ° C., reduced pressure 140 mmH).
g), and the same operation as in Example 1 was performed except that the concentration after washing with water was not carried out to obtain 47.8 g of a pale yellow bismaleimide powder (yield 83.9%). This bismaleimide has a melting point of 149 to 154 ° C., a purity of 97.4%, a residual solvent amount of 0.5% by weight, and an acid value of 2.0 (mg · KOH /
g).

Example 3 The aromatic solvent was changed to p-chlorotoluene, the reaction was carried out under reduced pressure and under reflux of p-chlorotoluene (temperature 110 ° C., reduced pressure 160 mmHg), and no concentration was carried out after washing with water. Other than that, the same operation as in Example 1 was carried out to obtain 46.3 g of a pale yellow bismaleimide powder (yield 81.2%).
This bismaleimide has a melting point of 126 to 148 ° C. and a purity of 9
8.4%, residual solvent amount 0.6% by weight and acid value 1.0
(Mg · KOH / g).

Comparative Example 1 A light yellow bismaleimide (55.4 g) was obtained in the same manner as in Example 1 except that the aromatic solvent was changed to toluene and concentration after washing with water was not carried out. Apparent yield 97.2%). This bismaleimide is toluene 1
Contains 3.1% by weight (purity excluding toluene is 9
8.2%), melting point 140-145 ° C, acid value 2.48 (m
g · KOH / g).

[0027]

According to the present invention, when an aromatic diamine and maleic anhydride are reacted in a mixed solvent of an aromatic solvent selected and an aprotic polar solvent, a high-purity bismaleimide containing no solvent is obtained. be able to.

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-5-230017 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C07D 207/452 CA (STN) REGISTRY (STN )

Claims (2)

(57) [Claims] 1. A compound represented by the general formula [I]: (In the formula, R ^{1 to} R ⁴ represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, R ⁵ represents a hydrogen atom or a methyl group, and R ⁶ represents a hydrogen atom, a methyl group or a phenyl group. Of the aromatic diamine and maleic anhydride represented by the general formula [II] (In the formula, X and Y represent a halogen atom and an alkyl group having 1 to 2 carbon atoms, n represents an integer of 1 to 3, and in the case of n = 1,
X and Y are in the para-positional relationship) and a bismaleamic acid is obtained by addition reaction at 70 to 150 ° C. in a mixed solvent of an aromatic solvent selected from substituted benzenes represented by a substituted benzene and an aprotic polar solvent. After that, in the presence of an acid catalyst, dehydration ring-closing reaction is carried out to azeotropically remove by-produced water, and the reaction solution is cooled to precipitate and separate the produced bismaleimide, thereby obtaining a high-purity bismaleimide . III] [Chemical Formula 3] (In the formula, R ^{1 to} R ⁶ have the same meanings as described above.) A method for producing a bismaleimide. 2. The method according to claim 1, wherein the aromatic diamine represented by the formula [I] is 2,2-bis [4- (4-aminophenoxy) phenyl] propane.