JP3189520B2 - Method for producing high-purity polymaleimide - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for purifying a polymaleimide obtained by subjecting a polymaleamic acid to a dehydration and ring-closure reaction in the presence of acetic anhydride, in other words, a method for easily producing a high-purity polymaleimide by the same method. On how to do it. The polymaleimide 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, a polymaleimide produced by an addition reaction of a polyamine with maleic anhydride is subjected to a dehydration and ring-closing reaction. A polymaleimide is produced by a ketone solvent such as acetone or a polar solvent such as N, N-dimethylformamide. , A base such as triethylamine and a metal compound are added to a dehydrating ring-closing reaction using a dehydrating agent such as acetic anhydride (JP-B-59-52660;
-66164).

[0003]

However, in the above-mentioned method using acetic anhydride as a dehydrating agent, the ring-closure reaction does not proceed sufficiently, and the produced polymaleimide contains a considerable amount of unring-closed maleamic acid. Therefore, it is not preferable for applications such as a laminated material, a sealing material, an electric insulating material, and a conductive paste in terms of heat resistance due to moisture absorption, a decrease in strength, and occurrence of defective insulation. Further, a complicated process is required to completely remove acetic acid as a by-product, and there is a need for a method for easily producing high-purity polymaleimide by the same method.

[0004]

SUMMARY OF THE INVENTION The present invention provides a polymaleimide obtained by subjecting a polymaleamic acid produced by an addition reaction of a polyamine and maleic anhydride to a dehydration ring-closing reaction in the presence of acetic anhydride to obtain a polymaleimide obtained by adding a water-insoluble organic Dissolved in a mixed solvent of a solvent and an aprotic polar solvent, washed the solution with an aqueous alkali solution, and then precipitated polymaleimide, the purity of unringed maleamic acid and acetic acid by-produced were removed To provide a method for easily producing a polymaleimide having a high level.

(Polymaleimide) The polymaleimide used in the present invention can be prepared by a known method, that is, by subjecting a polyamine and maleic anhydride to an addition reaction in a solvent such as an alkyl ketone, without isolating the resulting polymaleamic acid. A polymaleimide obtained by a method in which acetic anhydride is added as a dehydrating agent to cause a dehydration ring-closing reaction.

(Polyamine) Examples of the polyamine used in the production of polymaleimide include compounds containing two or more amino groups in the molecule, for example, m-phenylenediamine, p-phenylenediamine, 4,4'-diaminodicyclohexylmethane. 1,4-diaminocyclohexane 2,6-diaminopyridine, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl ether,
4,4'-diaminodiphenyl sulfide, 4,4 '
-Diaminodiphenylsulfone, bis- (4-aminophenyl) diphenylsilane, 1,5-diaminonaphthalene, 2,2'-bis [4- (4-aminophenoxy) phenyl] propane, 1,1'-bis [4 -(4-aminophenoxy) phenyl] propane, bis [4- (4-aminophenoxy) phenyl] ether, bis [4- (4
-Aminophenoxy) phenyl] sulfone, ethylenediamine, hexamethylenediamine, 3,9-bis (3-
(Aminopropyl) -2,4,8,10-tetraoxaspiro [5,5] -undecane, polymers obtained from aniline or toluidines and formaldehyde, polymers obtained from aniline or toluidines and terephthalaldehyde, and the like. Can be The ratio of maleic anhydride and polyamine is such that maleic anhydride is used in an amount of from 0.8 to 2.0, preferably from 1.0 to 2.0, per equivalent of all amino groups of the polyamine.
Use 1.3 moles.

(Reaction solvent) As the reaction solvent, for example,
An alkyl ketone solvent such as acetone, methyl ethyl ketone, methyl isopropyl ketone, and methyl isobutyl ketone, and a polar solvent such as N, N-dimethylformamide, N, N-dimethylacetamide, dimethyl sulfoxide, and N-methylpyrrolidone are used. The amount of the solvent is usually 3 to 7 parts by weight, preferably 4 to 6 parts by weight based on 1 part by weight of the polyamine.

(Addition reaction) The polymaleamic acid formation reaction by the addition reaction of maleic anhydride and polyamine is generally performed by adding a predetermined amount of polyamine to the above-mentioned solvent solution of maleic anhydride and stirring at 20 to 40 ° C for 1 to 2 hours. This is done by:

(Dehydration Ring Closure Reaction) In the dehydration ring closure reaction of polymaleamic acid, a tertiary amine such as acetic anhydride and triethylamine and a soluble metal salt such as nickel acetate are added to a reaction solution containing polymaleamic acid obtained by the addition reaction. The reaction is carried out at a temperature of 20 to 100 ° C., preferably 40 to 70 ° C., under a pressure at which the reaction system maintains a liquid phase.

The amount of acetic anhydride is 1 to 5 mol, preferably 1.1 to 2.2 mol, per equivalent of maleamic acid group. The tertiary amine to be added is 0.01 to 2.0 mol, preferably 0.1 to 0.5 mol per equivalent of maleamic acid group.
In the molar range, the soluble metal salt is from 0.001 to 0.02
Mole, preferably in the range of 0.001 to 0.01 mole.

The polymaleimide used in the method of the present invention is
From the reaction product liquid obtained as above, water, methanol, precipitated by a poor solvent of polymaleimide such as ethanol, washed, filtered, obtained by drying, etc., usually, unringed maleamic acid Is 3 to 10%, the purity is 75 to 95%, and the acid value is 9 to 30 [mg · KOH / g]. The melting point range of the polymaleimide varies depending on the type of the polymaleimide, but generally shows a wide melting point at 60 to 160 ° C.

(Mixed solvent) In the method of the present invention, the polymaleimide obtained as described above is dissolved in a mixed solvent of a water-insoluble organic solvent and an aprotic polar solvent. The water-insoluble organic solvent is a solvent capable of completely dissolving the polymaleimide, and specifically, (1) benzene,
Aromatic hydrocarbons such as toluene, xylene, ethylbenzene, diethylbenzene, butylbenzene, cumene, mesitylene, (2) chloroform, dichloroethane, trichloroethylene, 1,2-dichloropropane, chlorobenzene, dichlorobenzene, chlorotoluene, trichloro Halogenated hydrocarbons such as ethane, 1,1,2,2-tetrachloroethane, (3) ethyl formate, n-butyl formate, ethyl acetate, propyl acetate, n-butyl acetate, isobutyl acetate, sec-hexyl acetate And esters such as 2-ethylhexyl acetate, ethyl propionate, n-butyl propionate, and ethyl isovalerate.

As the aprotic polar solvent, a solvent which easily dissolves polymaleamic acid, for example, N, N-dimethylformamide, N, N-dimethylacetamide, N-
Amide solvents such as methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, tetramethylurea acid,
Sulfur-based solvents such as dimethyl sulfoxide, phosphorus-based solvents such as hexamethylphosphoramide, and the like.
Amide solvents are preferably used.

The amount of the aprotic polar solvent in the mixed solvent is 0.1 to 30% by weight, preferably 1 to 20% by weight. The water-insoluble organic solvent is used in a proportion of 1 to 50 parts by weight, preferably 2 to 20 parts by weight, based on 1 part by weight of the polymaleimide. The dissolution of polymaleimide is usually 20 to
Heat and dissolve in a range of 95 ° C. until a homogeneous solution is obtained.

(Aqueous Alkaline Solution) As the alkaline aqueous solution used in the present invention, aqueous solutions of various basic substances can be used. However, an aqueous ammonia solution is used from the viewpoints of detergency, operability, economy, etc. preferable. The concentration of the aqueous alkali solution is in the range of 1 to 20% by weight, preferably 5 to 10% by weight. The amount of the aqueous alkali solution is not particularly limited, but may be 0.1% of the mixed organic solvent.
It is preferable to use about 1 part by weight.

(Washing) Washing is carried out by adding the aqueous alkali solution to the mixed organic solvent solution of the polymaleimide, stirring, and then allowing to stand, followed by oil-water separation. Stirring is generally performed by stirring at a rotation speed of 30 to 300 rpm for 3 to 30 minutes. Washing is carried out in a temperature range of 20 to 95 ° C.
Perform ~ 5 times.

After the washing, washing with water at least once gives a higher purity polymaleimide. To obtain a high-purity polymaleimide from the obtained organic layer, after distilling off the solvent,
There is a method of extracting or melting. The solvent is distilled off at a temperature equal to or higher than the evaporation temperature of the solvent, usually at 40 to 200 ° C. and at a pressure of 760 to 0.1 mmHg.

In the case of melt extraction, the temperature is finally raised to the melting point of the polymaleimide or higher, and the solvent is distilled off until the solvent is substantially eliminated, specifically, until the residual amount of the solvent becomes 2% by weight or less. Then, the maleimide is extracted in a molten state.

In the case of precipitation, usually, after distilling off a part of the solvent, an amount corresponding to 20 to 95% by weight of the charged amount, a poor solvent for the polymaleimide such as water, methanol and ethanol is removed. 1 to 1 part by weight
The polymaleimide is precipitated by adding 30 parts by weight, preferably 2 to 15 parts by weight, separated by filtration, dried and taken out in a crystalline state.

The resulting polymaleimide generally has a purity of 9%.
It has a high purity of 0% or more and an acid value of 0.1 to 5 [mg · KOH / g].

[0021]

The present invention will be described more specifically with reference to the following examples. The melting point of polymaleimide is determined by the capillary method.
The purity was measured by liquid chromatograph (differential refractive index detector) area percentage, and the acid value was measured by titration with an N / 10 KOH ethanol solution.

Reference Example 1 Maleic anhydride (21.6) was placed in a 300 ml four-necked flask equipped with a reflux condenser, a thermometer, a dropping funnel and a stirrer.
g and 13.2 g of acetone were dissolved by stirring. 4,4 '
19.8 g of diaminodiphenylmethane in acetone 6
After dissolving in 9.3 g and dripping into the flask maintained at 20 to 40 ° C. over 2 hours, the mixture was stirred at the same temperature for 1 hour. Next, 0.2 g of nickel acetate and triethylamine 5
g and acetic anhydride 25.5 g were added and reacted at 65 ° C. for 2 hours.

After cooling to room temperature, the mixture was dropped into 500 ml of water to obtain 32.2 g of yellow N, N '-(4,4'-diphenylmethane) bismaleimide (yield: 93).
%). This maleimide has a melting point of 144 to 151 ° C and a purity of 8
It was 9% and the acid value was 9.1 mg · KOH / g.

Reference Example 2 In Reference Example 1, 3,9-bis (3
-Aminopropyl) -2,4,8,10-tetraoxaspiro [5,5] -undecane, and a polymaleimide was obtained in the same manner as in Reference Example 1 except that the amount of acetone was doubled.

Reference Examples 3 to 5 Polymaleimides were obtained in the same manner as in Reference Example 1, except that the polyamine was changed as shown in Table 1. Table 1 shows the properties of the polymaleimides obtained in Reference Examples 2 to 5.

[0026]

[Table 1]

Example 1 In a 300 ml four-necked flask equipped with a condenser, a thermometer and a stirrer, 20 g of the bismaleimide obtained in Reference Example 1 was added.
80 g of chlorobenzene and 1 g of N-methyl-2-pyrrolidone were charged and dissolved by stirring while adjusting the internal temperature to 80 ° C. After dissolution, 5% aqueous ammonia 4
After adding 0 g, the mixture was stirred for 5 minutes, left standing for 2 minutes, and then separated into oil and water. Further, 40 g of pure water was added, and washing was performed in the same manner.

Next, the organic layer separated from oil and water was heated to a temperature of 8 ° C.
In an oil bath maintained at 0 ° C., under reduced pressure (100-20 mmH
In g), 40 g of chlorobenzene was distilled off (distillation rate: 50% by weight). After cooling the solution to 40 ° C.,
Was added to obtain a slurry liquid. This is filtered off, dried and
18.5 g of pale yellow bismaleimide powder was obtained. (Yield 92.5%) This bismaleimide has a melting point of 151 to 152 ° C and a purity of 9%.
The acid value was 2.2% and the acid value was 1.3 (mg · KOH / g).

Examples 2 to 5 In the same manner as in Example 1 except that the polymaleimide obtained in Reference Examples 2 to 5 was used and the solvents shown in Table 2 were used as the water-insoluble organic solvents. A polymaleimide was obtained. Table 2 shows the properties of the obtained polymaleimide.

[0030]

[Table 2]

Example 6 In Example 4, 1.2-dichloroethane was distilled off under normal pressure in an oil bath in which the washed organic layer was kept at 110 ° C., and when the outflow was reduced, the pressure was reduced (10 mmH).
g), and the procedure was carried out in the same manner as in Example 4 except that the pale yellow polymaleimide was taken out in a molten state after it was held until it did not completely flow out. 18. Polymaleimide obtained
8 g (94.0% yield) had a melting point of 60 to 69 ° C and an acid value of 2.8 (mg KOH / g).

Comparative Example 1 17.2 g of a pale yellow bismaleimide powder was prepared in the same manner as in Example 5 except that washing was performed twice with 40 g of pure water instead of using a 5% aqueous ammonia solution. Obtained. (Yield 86%) This bismaleimide has a melting point of 51 to 68 ° C. and an acid value of 8.0.
(Mg · KOH / g).

Comparative Example 2 In Example 4, 80 g of chlorobenzene was used as a solvent.
Poly (phenylmethylene) maleimide was dissolved in the same manner as in Example 4 except that only was charged. 5% after dissolution
When washed with 40 g of an aqueous ammonia solution in the same manner as in Example 5, a black tar was produced.

Continued on the front page (72) Inventor Kaoru Kanayama 8-3-1 Chuo, Ami-cho, Inashiki-gun, Ibaraki Pref. Tsukuba Research Laboratory, Mitsubishi Yuka Co., Ltd. (56) References JP-A-5-140097 (JP, A) ( 58) Field surveyed (Int.Cl. ⁷ , DB name) C07D 207/452 C08F 22/40 CA (STN) REGISTRY (STN)

Claims (1)

(57) [Claims] 1. A polymaleimide obtained by subjecting a polymaleamic acid formed by an addition reaction between a polyamine and maleic anhydride to a dehydration ring-closing reaction in the presence of acetic anhydride to obtain a mixture of a water-insoluble organic solvent and an aprotic polar solvent. A method for producing a high-purity polymaleimide, comprising dissolving in a solvent and washing with an aqueous alkaline solution.