JP2002284873A - Method for producing polyamic acid solution - Google Patents

Abstract

PROBLEM TO BE SOLVED: To dissolve a polyamic acid having a high degree of polymerization and suppressed generation of a branch in a solvent, which can obtain a polyimide having various mechanical properties, for example, high tensile strength at break and high extensibility. The present invention provides a method for producing a polyamic acid solution. SOLUTION: A compound having a water content of 300 ppm or less and having two or more acid anhydride groups per molecule is suspended in a solvent to form a suspension. A method for producing a polyamic acid solution, characterized in that a compound having at least one amino group is dropped at 10 to 100 equivalent% per hour, and the reaction is carried out while maintaining the temperature of the reaction system at 50 ° C. or lower.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a polyamic acid solution in which a polyamic acid, which is a precursor of a polyimide resin known as a heat-resistant resin, is dissolved in a solvent.

[0002]

2. Description of the Related Art Polyimide resins are known to have high heat resistance, chemical resistance, electrical properties, mechanical properties, and other excellent properties. It is very useful for various applications including film and wire coating, and is widely used.

Conventionally, as a method for producing a polyimide resin, an organic tetracarboxylic dianhydride component and an organic amine component are usually combined with N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2 A method in which a polyamic acid is obtained by reacting in a solvent such as pyrrolidone and the polyamide acid is heated or dehydrated and closed using a dehydrating agent such as acetic anhydride to obtain a polyimide.

In order to obtain a polyamic acid having a high degree of polymerization, various precautions are required, such as completely purifying the raw materials, dehydrating the solvent, and performing the reaction in a substantially anhydrous system. . In addition, in order for the polyimide obtained by dehydrating and ring-closing the polyamic acid to have excellent mechanical properties such as tensile strength and extensibility, a solution of an organic amine is required in the polycondensation reaction when obtaining the polyamic acid. It was necessary to pay attention to the fact that it was necessary to sequentially add powdered organic tetracarboxylic dianhydride therein and to set specific addition conditions.

For example, when powdered organic tetracarboxylic dianhydride is successively added, all of the necessary amount of organic tetracarboxylic dianhydride relative to the organic amine must be introduced into the reaction system. However, in order to do so, it is necessary to sufficiently wash the vessel for charging powder with a solvent and to flow all of the powder into the reaction system. Otherwise, the amount of the organic tetracarboxylic dianhydride component added to the organic amines is less than the reaction equivalent, resulting in a polyamic acid having a low degree of polymerization. In this case, a large amount of solvent must be used, or it is very complicated.

In addition, when the organic tetracarboxylic dianhydride is suspended in a solvent first and the solution of the organic amine is dropped, the suspended solution of the organic tetracarboxylic dianhydride is absorbed in moisture. As a result, there is a problem that the organic tetracarboxylic dianhydride causes a ring-opening reaction due to moisture to become an organic tetracarboxylic acid, which makes it difficult to react with the organic amine component.

[0007]

SUMMARY OF THE INVENTION In view of the above circumstances, it is an object of the present invention to provide a polyimide having a high degree of polymerization and a high degree of branching which can obtain polyimide having various mechanical properties, for example, high tensile strength at break and high extensibility. It is an object of the present invention to provide a method for producing a polyamic acid solution in which a polyamic acid in which is suppressed is dissolved in a solvent.

[0008]

Means for Solving the Problems The inventors of the present invention have made intensive studies to solve these problems, and as a result, polycondensation of a compound having an acid anhydride group and a compound having an amino group will be described later. When the reaction is performed to produce a polyamic acid solution, a polyamic acid having a high degree of polymerization and suppressed generation of branches can be obtained. The present inventors have found that they have good mechanical properties such as the above, and have reached the present invention.

That is, according to the present invention, the water content is 300 ppm
A compound having two or more acid anhydride groups per molecule is suspended in a solvent to form a suspension, and a compound having two or more amino groups per molecule is contained in the suspension. (1) A method for producing a polyamic acid solution, characterized in that the reaction is performed while maintaining the temperature of the reaction system at 50 ° C. or less by dropping at 10 to 100 equivalent% per hour.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, as a compound having two or more, usually two to three, and preferably two acid anhydride groups per molecule, a known compound used for a polyamic acid forming reaction is used. It can be used, for example, 1,2,4,5-benzenetetracarboxylic dianhydride, benzophenone tetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 3,3 ′, 4 And aromatic tetracarboxylic dianhydrides such as 4,4'-diphenyltetracarboxylic dianhydride. These may be used alone or in combination of two or more.

In addition, two or more per molecule, usually 2-3
As the compound having two, preferably two amino groups, known compounds used for a polyamic acid-forming reaction can be used. For example, 4,4′-diaminodiphenylmethane, 4,4 ′
Aromatic diamines such as diaminodiphenyl ether, 4,4'-diaminodiphenylsulfone, silicone diamines such as dimethylpolysiloxane capped at both ends with aminopropyl groups, 3,4,4'-triaminodiphenyl ether, 3,4,4 '
-Aromatic triamines such as triaminodiphenylmethane and the like. These may be used alone or in combination of two or more.

Examples of the reaction solvent include aprotic polar solvents such as N, N'-dimethylformamide, N, N'-dimethylacetamide, N-methyl-2-pyrrolidone, dimethylsulfoxide and hexamethylphosphoramide. It is desirable to use them alone or as a mixture, but it is also possible to use aromatic hydrocarbons such as xylene and toluene.

In the above reaction solvent, a compound having two or more acid anhydride groups per molecule is suspended to form a suspension,
In this suspension, a compound having two or more amino groups per molecule is dropped and reacted at 10 to 100 equivalent% per hour, more preferably 20 to 80 equivalent% per hour. If the dropping rate is less than 10 equivalent% per hour, the amino group concentration in the reaction system will be low, and the amino group will not be excessively large relative to the effective concentration of the acid anhydride group.
The reaction between the acid anhydride group and the water in the reaction system occurs, and a large amount of carboxyl groups are generated, which hinders the sequential generation of polyamic acid. In addition, drop rate is 1 per hour
If it exceeds 00 equivalent%, the temperature of the reaction system rises due to reaction heat generated by the reaction between the compound having an acid anhydride group and the compound having an amino group, and the compound having an acid anhydride group in a suspended state Increases the concentration of the effective acid anhydride group, the relative amino group concentration in the reaction system decreases, and the reaction between the acid anhydride group and the water in the reaction system occurs, and Groups are generated in a large amount, which hinders the sequential generation of polyamic acid.

It is necessary to keep the temperature of the reaction system at 50 ° C. or lower, and preferably at 40 ° C. or lower. When the temperature of the reaction system is higher than 50 ° C., the solubility of the compound having an acid anhydride group in a suspended state increases, the concentration of the effective acid anhydride group increases, and the relative amino group in the reaction system increases. The concentration decreases,
The reaction between the acid anhydride group and the water in the reaction system occurs, and a large amount of carboxyl groups are generated, which hinders the sequential generation of polyamic acid. The lower limit of the temperature of the reaction system is not particularly limited as long as it is a temperature equal to or higher than the freezing point of the reaction solvent, but from the viewpoint of the reaction rate and the like, is usually 0 ° C or higher, preferably 5 ° C or higher, more preferably 10 ° C or higher. And

According to the present invention, even if a small amount of water is contained in the compound having an acid anhydride group, generation of branching and side reactions are suppressed by the above-mentioned mechanism, and a polyamic acid solution having a high degree of polymerization can be obtained. can get. It was also found that the polyimide obtained from the polyimide had excellent mechanical properties such as tensile breaking strength and extensibility. At this time, the water content in the compound having an acid anhydride group is 300 ppm by weight.
Or less (ie, 0-300 ppm),
0 ppm or less (0 to 200 ppm) is preferable, and 150 ppm or less (0 to 150 ppm).
ppm) is more preferred. Similarly, according to the present invention, a solution of polyamic acid having a high degree of polymerization is obtained even if the solvent contains 150 ppm or less (i.e., 0 to 150 ppm) of water, and a polyimide film obtained therefrom is obtained. It shows excellent properties as above.

In the present invention, the compounding ratio of the compound having two or more acid anhydride groups per molecule and the compound having two or more amino groups per molecule is determined based on the compound having the acid anhydride group. The molar ratio of the amino group in the amine compound to 1 mol of the acid anhydride group (-COOCO-) is usually
0.95 to 1.05, preferably 0.98 to 1.02, more preferably 0.
99 to 1.01, more preferably 1.00. If the molar ratio is too large or too small, it may be difficult to obtain a polyamic acid solution having a high degree of polymerization.

The solid content concentration of the polyamic acid solution after the polycondensation reaction is 5 to 50% by weight, preferably 10 to 25% by weight.
It is desirable from the viewpoint of handling that the content be set to% by weight. Also,
During the polycondensation reaction, in order to obtain a polyimide having good mechanical properties, it is preferable to control the solution viscosity range of the polyamic acid solution, and the solution viscosity is preferably 1,000 to 20,000 mPa.
-S (millipascal-second), more preferably 2,000 to 10,000
It is preferable to control so as to be 0 mPa · s.

According to the present invention, the generation of a branch and the side reaction are suppressed, and a solution containing an amic acid having a high polymerization degree can be obtained. This is because, as described above, during the polycondensation reaction of the polyamic acid, the compound having an acid anhydride group is in a suspended state, so that the effective concentration of the acid anhydride group is small, and the excess amino acid in the reaction system. The group inhibits the generation of carboxyl groups generated by the acid anhydride groups and the water in the system, and the sequential reaction between the compound having an acid anhydride group and the compound having an amino group becomes dominant, and the occurrence of branching occurs It is considered that the side reaction is suppressed and the polyamic acid can be made higher in molecular weight.

In the present invention, the polyimide is obtained by removing the solvent from the polyamic acid solution, dehydrating and closing the ring. The imidization of polyamic acid is carried out at 100-220 ° C, especially at 150
It is carried out by heating at ~ 200 ° C for 1 to 10 hours or using a ring-closing agent such as acetic anhydride (acetic anhydride / pyridine), acetylene chloride, trifluoroacetic anhydride and the like.

[0020]

EXAMPLES The present invention will be described below in detail with reference to examples, but the present invention is not limited to these examples. The tensile strength at break and the degree of elongation were measured according to JIS K 6249.

Example 1 In a 500 ml four-necked flask, 3,3 ′, 4,3 containing 130 ppm of water was added.
4'-benzophenonetetracarboxylic dianhydride (hereinafter BTD
(Abbreviated as A) 65.0 g (202 mmol) was added and N containing 20 ppm of water
-Methyl-2-pyrrolidone (hereinafter abbreviated as NMP) 275 g was added,
Suspended in an oil bath at 22.5 ° C. On the other hand, 40.0 g (202 mmol) of 4,4′-diaminodiphenylmethane (hereinafter abbreviated as DDM) was placed in a 100 ml dropping funnel, dissolved in 40 g of NMP, and dissolved in the NMP suspension of BTDA kept at 22.5 ° C. Was added at a rate of 50 equivalent% per hour so that the temperature in the reaction system did not exceed 30 ° C. Further, DDM remaining on the wall surface of the 100 ml dropping funnel was poured into the reaction system (four-neck flask) with 10 g of NMP. The time required during this time was about 3 hours. Subsequently, stirring was continued for 16 hours while controlling the temperature in the reaction system (that is, the temperature in the reaction vessel) at 22.5 ° C., to obtain a polyamic acid 25% by weight solution. However, the inside of the reaction system was kept under a dry nitrogen stream by the above operation. The solution viscosity at 25 ° C. of the polyamic acid solution thus obtained is
It was 4300 mPa · s. However, the solution viscosity used here refers to a cone and plate E-type viscometer.
Solution viscosity in m.

Next, this 25% polyamic acid solution is applied by casting onto a glass plate, and dried, dehydrated, and closed with hot air at 80 ° C. for 1 hour, 150 ° C. for 1 hour, and then at 200 ° C. for 1 hour. Then, the coating film was peeled off from the glass plate to obtain a polyimide film having a thickness of 20 to 30 μm. This film exhibited the following properties: Tensile breaking strength 127.5MPa (1300kg / cm ² ) Extensibility 30%

Example 2 A polyamic acid solution was obtained and the solution viscosity was measured in the same manner as in Example 1 except that the dropping rate of DDM was changed to 10 equivalent% per hour, and a polyimide film was further obtained. The degree of extension was measured. Table 1 shows the results.

Example 3 A polyamic acid solution was obtained and the solution viscosity was measured in the same manner as in Example 1 except that the dropping rate of DDM was changed to 100 equivalent% per hour, and a polyimide film was obtained. The degree of extension was measured. Table 1 shows the results.

Example 4 A polyamic acid solution was obtained and the solution viscosity was measured in the same manner as in Example 1 except that the temperature of the reactor was set at 10 ° C., and a polyimide film was further obtained. Tensile breaking strength and elongation were measured. did. Table 1 shows the results.

Example 5 A polyamic acid solution was obtained and the solution viscosity was measured in the same manner as in Example 1 except that the temperature of the reactor was 35 ° C. Further, a polyimide film was obtained, and the tensile strength at break and elongation were measured. did. Table 1 shows the results.

Example 6 A polyamic acid solution was obtained and the solution viscosity was measured in the same manner as in Example 1 except that the water content of BTDA was changed to 90 ppm. Further, a polyimide film was obtained, and the tensile strength at break and the elongation were measured. . Table 1 shows the results.

Example 7 A polyamic acid solution was obtained and the solution viscosity was measured in the same manner as in Example 1 except that the water content of BTDA was changed to 170 ppm. Further, a polyimide film was obtained, and the tensile strength at break and extensibility were measured. . Table 1 shows the results.

Comparative Example 1 A polyamic acid solution was obtained and the solution viscosity was measured in the same manner as in Example 1 except that the dropping rate of DDM was changed to 5 equivalent% per hour, and a polyimide film was obtained.
The degree of extension was measured. Table 1 shows the results.

Comparative Example 2 A polyamic acid solution was obtained and the solution viscosity was measured in the same manner as in Example 1 except that the dropping rate of DDM was changed to 200 equivalent% per hour, and a polyimide film was obtained. The degree of extension was measured. Table 1 shows the results.

Comparative Example 3 A polyamic acid solution was obtained and the solution viscosity was measured in the same manner as in Example 1 except that the temperature of the reactor was set at 60 ° C., and a polyimide film was further obtained, and the tensile strength at break and extensibility were measured. did. Table 1 shows the results.

Comparative Example 4 A polyamic acid solution was obtained in the same manner as in Example 1 except that the water content of BTDA was changed to 400 ppm, the solution viscosity was measured, a polyimide film was further obtained, and the tensile strength at break and extensibility were measured. . Table 1 shows the results.

The results of Examples 1 to 7 and Comparative Examples 1 to 4 are shown in Tables 1 and 2.

[0034]

[Table 1]

[0035]

[Table 2]

[0036]

According to the present invention, it is possible to obtain a polyamic acid solution in which a polyamic acid having a high degree of polymerization and in which the generation of branches is suppressed is dissolved, and a polyimide resin obtained from this polyamic acid is excellent. It has mechanical properties such as high tensile strength at break and high extensibility.

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Claims (1)

[Claims] A compound having a water content of 300 ppm or less and having two or more acid anhydride groups per molecule is suspended in a solvent to form a suspension. Compounds having two or more amino groups per hour
A method for producing a polyamic acid solution, characterized in that the reaction is carried out while dropping at 10 to 100% by weight while maintaining the temperature of the reaction system at 50 ° C or lower.