JPH041785B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an aromatic polyimide solution composition. More particularly, the present invention relates to aromatic polyimide solution compositions with high concentrations and low solution viscosity that are particularly useful as polyimide varnishes.

As a method for producing an aromatic polyimide solution composition, a tetracarboxylic acid component and a diamine component are polymerized in a specific solvent to produce an aromatic polyamic acid solution, which is a precursor of aromatic polyimide, and then the polyamic acid is heated or imidized with a dehydrating agent to form an aromatic polyimide solution (two-step method), and a tetracarboxylic acid component and a diamine component are reacted at high temperature in a specific solvent to polymerize and imidize to form an aromatic polyimide solution. A method of forming a polyimide solution (one-step method) has been well known.

Among these, in the former method (two-step method), the solubility of the intermediate polyamic acid is poor, and expensive and highly hygroscopic solvents such as N-methylpyrrolidone, dimethylacetamide, and dimethylformamide must be used. Furthermore, since viscosity increases and gelation occurs when stored at room temperature, it has the disadvantage that it must be stored under cooling. Furthermore, during imidization, desorbed substances such as water are generated, so when this aromatic polyamic acid solution is used as a varnish for purposes such as covering electric wires, it tends to cause defects called "blisters". It has drawbacks such as:

On the other hand, in the latter method (one-step method), a soluble aromatic polyimide can only be obtained when a specific aromatic tetracarboxylic acid component and an aromatic diamine are used, so the selection of these raw materials and solvent is important. becomes.

Regarding this one-step method, for example,
Publication No. 113597 discloses that a soluble polymer is produced by polymerizing and imidizing an aromatic tetracarboxylic acid component mainly composed of biphenyltetracarboxylic acids and an aromatic diamine component in an approximately equimolar organic polar solvent at high temperature. A method for producing aromatic polyimides is described. This method addresses the previously known problems of soluble polyimides produced using benzophenone tetracarboxylic acids as acid components, namely, when the polymerization reaction temperature exceeds 160°C, the resin becomes cloudy or gels, and the solution (described in Japanese Patent Publication No. 44-9576), and because it is necessary to use a special diamine with an asymmetric or side chain as the diamine component, heat resistance and mechanical properties are low (for example, Special Publication No. 17145, Showa 46-17145,
Special Publication No. 47-26878, Special Publication No. 49-18639, Special Publication No.
No. 49-19119, Special Publication No. 1971-30717, Special Publication No. 1977-
30718 and Japanese Patent Publication No. 49-106599).

However, in the method disclosed in JP-A No. 50-113597, since the polymerization/imidization reaction is carried out at high temperatures, the reaction proceeds rapidly and the resulting aromatic polyimide has an extremely high degree of polymerization. There was a problem. Therefore, with this method, it is difficult to produce an aromatic polyimide solution having a desired solution viscosity with good reproducibility.

Particularly when using an aromatic polyimide solution as a varnish, a high polymer concentration is desired from the viewpoint of productivity and cost. A solution with a low viscosity of about 30°C (poise) is desired. In order to obtain such a high concentration and low viscosity solution, it is necessary to appropriately suppress the degree of polymerization of polyimide produced in the polymerization/imidization reaction.

The polymerization/imidization reaction that makes it possible to suppress the degree of polymerization of polyimide is described in JP-A-56-
38324 and JP-A-57-34127, an aromatic tetracarboxylic acid component containing biphenyltetracarboxylic acid and an aromatic diamine are used in approximately equal moles, the polymerization reaction system is a closed system, and the necessary if there is,
By adding water to the reaction system, the water pressure of the reaction system and/or
Alternatively, a method is disclosed in which the viscosity of the solution is adjusted by polymerizing at a polymerization temperature of 100 to 300° C. until the moisture content of the polymerization solution or the moisture content of the polymerization solution reaches a constant value.

However, these methods require the reaction system to be a closed system, and the effect of inhibiting the heavy reaction of water is relatively small. In order to obtain this, there is the inconvenience that the water pressure of the reaction system and the water content of the polymerization solution must be kept extremely high.

Furthermore, Japanese Patent Publication No. 55-11696 describes a method of reacting an aromatic tetracarboxylic acid component containing benzophenonetetracarboxylic acid with an aromatic diamine component in an organic solvent containing a polyhydric alcohol; No. 56-4587 discloses a similar method in which an aromatic diamine having a side chain is used as the aromatic diamine component. However, aromatic polyimide solutions produced by these methods also
Similar to the above, there are problems in that the stability of the solution and the heat resistance and mechanical properties of the resulting varnish are insufficient.

Furthermore, in Japanese Patent Publication No. 56-5466, pyromellitic anhydride, 3,
Polymerized/imidized product obtained by reacting an aromatic tree or aromatic tetracarboxylic acid anhydride such as 3',4,4'-benzophenone tetracarboxylic anhydride, or a derivative thereof with a molar excess of aromatic diamine. A solution for forming a heat-resistant polymer (aromatic polyimide solution) made by blending an oligomer with a polyhydric alcohol ester of 1,2,3,4-butanetetracarboxylic acid or an aromatic tri- or aromatic tetracarboxylic acid anhydride. is disclosed. In this aromatic polyimide solution, the presence of polyhydric alcohol during polymerization and formation of imidized oligomers causes ester bonds to be included in the polyimide main chain, so that solubility is improved.
On the other hand, the heat resistance due to the introduction of the ester group,
Problems such as a decrease in mechanical strength arise.

As a result of research aimed at resolving the above-mentioned drawbacks of the aromatic polyimide solution compositions known so far, the present inventors discovered that carbon dioxide containing a specific aromatic tetracarboxylic dianhydride Taking advantage of the fact that the polymerization/imidization reaction product oligomer obtained from the acid component and the aromatic diamine component in excess of the carboxylic acid component has high solubility in a phenolic solvent, this polymerization/imidization product oligomer is By blending an aromatic tetracarboxylic acid component as an ester of monohydric alcohol in an amount corresponding to the amount of excess aromatic diamine forming the amine terminal, a low viscosity can be stably maintained despite the high concentration. The inventors have now discovered that it is possible to obtain a polyimide solution composition that has excellent properties such as heat resistance and mechanical strength, and has arrived at the present invention.

That is, the present invention provides (A) aromatic diamine and the diamine component.
Polymerized/imidized oligomer with aromatic tetracarboxylic dianhydride containing 65 to 98 mol% of 2,3,3',4'-biphenyltetracarboxylic dianhydride at 40 mol% or more, and ( B) An aromatic compound obtained by dissolving monohydric alcohol diester of aromatic tetracarboxylic acid in a phenolic solvent in an amount such that the acid component and diamine component in the polymerized/imidized oligomer are substantially equimolar. A polyimide solution composition is provided.

According to the present invention, the polymerization/imidization reaction can be easily controlled without impairing the excellent properties of aromatic polyimide, and the drawback that the aromatic polyimide solution composition becomes highly viscous can be overcome, and it can be used for a long period of time. It becomes possible to obtain an aromatic polyimide solution composition with improved storage stability.

Furthermore, according to the present invention, an inexpensive phenolic solvent such as cresol, which is a general-purpose solvent for electric wire varnish, is used, and the polymer concentration is as high as 15 to 40% by weight, but is less than several hundred poise/30°C. It is possible to obtain an aromatic polyimide solution composition having a low solution viscosity extremely easily and with good reproducibility. The aromatic polyimide solution composition of the present invention is also characterized by excellent long-term storage stability as described above. Furthermore, when the aromatic polyimide solution composition of the present invention is used for applications such as electric wire coating, coating, and film formation, coatings with excellent heat resistance, electrical insulation, mechanical properties, abrasion resistance, and solvent resistance can be obtained. A layer, coating or film is obtained.
Therefore, the aromatic polyimide solution composition of the present invention is extremely useful, especially as a varnish.

Next, the present invention will be explained in detail.

The present invention is an aromatic polyimide solution composition in which a specific polymerized/imidized oligomer (A) and an aromatic tetracarboxylic acid monohydric alcohol diester (B) are dissolved in a phenolic solvent as described above. . The above polymerized/imidized oligomer (A) is
It is a polymerized/imidized oligomer of aromatic diamine and aromatic tetracarboxylic dianhydride containing 40 mol% or more of 2,3,3',4'-biphenyltetracarboxylic dianhydride. However, in producing the above polymerized/imidized oligomer, the aromatic tetracarboxylic dianhydride is used in an amount of 65 to 98 mol % based on the diamine component.

This polymerized/imidized oligomer (A) can be produced by heating an aromatic diamine and an aromatic tetracarboxylic dianhydride to a high temperature in a phenolic solvent to polymerize and imidize them according to a known method. I can do it. However, in the present invention, the aromatic tetracarboxylic dianhydride used in the reaction is 65 to 98 mol% based on the aromatic diamine component.
The amount must be insufficient within a certain range. Furthermore, 40 mol% or more of the aromatic tetracarboxylic dianhydride must be 2,3,3',4'-biphenyltetracarboxylic dianhydride. In the present invention, by using aromatic tetracarboxylic dianhydride in such a composition and amount, it is soluble in a phenolic solvent and imparts excellent properties to an aromatic polyimide solution that is later formed as a compound. Polymerized/imidized oligomers can be obtained.

The above polymerization/imidization reaction may be carried out in accordance with known methods, such as polymerizing/imidizing each component in a phenolic solvent at a temperature in the range of 100 to 300°C, particularly in the range of 130 to 250°C. This can be done using .

Among the above-mentioned aromatic tetracarboxylic dianhydrides, 2,3,3',4'-biphenyltetracarboxylic dianhydride is preferably used in combination with other aromatic tetracarboxylic dianhydrides. Examples of aromatic tetracarboxylic dianhydrides that are preferably used in combination include 3,3',4,4'-biphenyltetracarboxylic dianhydride and 3,3',4,4'-benzophenone. Mention may be made of tetracarboxylic dianhydride. However, in small amounts, pyromellitic dianhydride, bis(3,4-dicarboxyphenyl)methane dianhydride, 2,2-bis(3,4-dicarboxyphenyl)propane dianhydride, bis( 3,4
Other carboxylic acid components such as -dicarboxyphenyl)ether dianhydride and bis(3,4-dicarboxyphenyl)sulfone dianhydride can also be used in combination. Moreover, a mixture of three or more types of acid anhydrides may be used as the carboxylic acid component.

The aromatic tetracarboxylic dianhydride used in the preparation of the polymerized/imidized oligomer (A) of the present invention is:
Preferably, it consists essentially of 40 to 80 mol% of 2,3,3',4'-biphenyltetracarboxylic dianhydride and 60 to 20 mol% of other aromatic tetracarboxylic dianhydride. 50 mol% or more of the other aromatic tetracarboxylic dianhydrides are 3,3',4,
Preferably, it is 4'-biphenyltetracarboxylic dianhydride or 3,3',4,4'-benzophenonetetracarboxylic dianhydride. Particularly preferred is substantially 40 to 80 mol% of 2,3,3',4'-biphenyltetracarboxylic dianhydride and 3,3',
4,4'-biphenyltetracarboxylic dianhydride 60
The composition consists of ~20 mol%.

The aromatic diamine used in the present invention may be any aromatic diamine as long as the resulting aromatic polyimide is soluble. Examples of preferred aromatic diamines include 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl thioether,
Mention may be made of 4,4'-diaminodiphenylsulfone, o-tolidine and o-dianisidine. These aromatic diamines may be used alone or in combination of two or more. Further, the above-mentioned aromatic diamines include, for example, p-phenylenediamine, m-phenylenediamine, 3,
It may be used in combination with 5-diaminobenzoic acid, diaminonaphthalene (1,5-diaminonaphthalene, 2,6-diaminonaphthalene), etc.

The blending ratio of aromatic tetracarboxylic dianhydride and aromatic diamine for preparing the polymerized/imidized oligomer (A) of the present invention is as follows: for
The content should be 65 to 98 mol%. Aromatic tetracarboxylic dianhydride has 98
If it exceeds 65 mol%, polymerization of the oligomer (A) will easily occur, making it difficult to reduce the viscosity, and if it is less than 65 mol%, the monomer component will increase, making it difficult to obtain coatings and films with sufficient performance. etc. becomes difficult to obtain.

The amounts of aromatic tetracarboxylic dianhydride and aromatic diamine added to the solvent can be appropriately selected depending on the desired degree of polymerization, solution viscosity, and form of use, but basically the resulting aromatic polyimide solution composition The aromatic polyimide concentration inside is about 15-40
It is desirable to adjust the amount to be % by weight. If the concentration of aromatic polyimide in the aromatic polyimide solution composition exceeds 40% by weight, the aromatic polyimide solution composition will have too high a viscosity and will be difficult to use, for example, as a varnish for coating electrical materials. It cannot be used for this purpose, and it is difficult to use it practically for other purposes as well. Further, when the aromatic polyimide concentration in the aromatic polyimide solution composition is less than 15% by weight, the solution viscosity becomes sufficiently low, but such a dilute solution has low practical utility value.

Examples of the phenolic solvent used in the preparation of the polymerized/imidized oligomer (A) of the present invention include cresol, xylenol, etc., and these can be used alone or in combination. In addition, cresol, xylenol, etc.
Other phenolic solvents such as phenol and halogenated phenols may be mixed in part.

The polymerized/imidized oligomer (A) of the present invention prepared by the method described above is an oligomer having amino groups at both ends of the molecule and substantially only imide bonds in the main chain of the molecule. .

The above polymerized/imidized oligomer (A) contains an aromatic tetracarboxylic acid monohydric alcohol diester in an amount such that the acid component and diamine component in the polymerized/imidized oligomer are substantially equimolar.
(B) is blended to form the polyimide solution composition of the present invention.

In place of the monohydric alcohol diester of aromatic tetracarboxylic acid (B), aromatic tetracarboxylic acid, aromatic tetracarboxylic dianhydride, aromatic tetracarboxylic acid tetraester, etc. are added to the polymerized/imidized oligomer (A). If a polyimide solution composition is blended with polyimide, the solubility may be poor, the viscosity of the polyimide solution composition may become high, or even if a low viscosity solution can be obtained, sufficient physical properties (especially elongation properties) may be obtained. It is not possible to obtain an aromatic polyimide solution composition that gives a poor performance (tends to be inferior).

The monohydric alcohol diester (B) of the aromatic tetracarboxylic acid used in the present invention can be obtained by reacting the aromatic tetracarboxylic acid, its salt or anhydride with a monohydric alcohol.

Even if the aromatic tetracarboxylic acid monohydric alcohol diester (B) to be blended is isolated,
Further, it may be a solution, and even if it contains unreacted alcohol, it can be used without any problem.

The aromatic tetracarboxylic acid component constituting the monohydric alcohol diester (B) of aromatic tetracarboxylic acid blended in the present invention is important for long-term storage stability and solubility of the aromatic polyimide in the resulting aromatic polyimide solution composition. There is no particular limitation as long as it does not impair heat resistance, mechanical strength, etc., but preferred are 2,3,3'4'-biphenyltetracarboxylic acid and 3,3',4,4'-biphenyl. Tetracarboxylic acid, 3,3',4,4'-benzophenonetetracarboxylic acid, pyromellitic acid, bis(3,4-dicarboxyphenyl)methane, 2,2-bis(3,4-dicarboxyphenyl) enyl)propane, bis(3,4-dicarboxyphenyl)ether,
Mention may be made of aromatic tetracarboxylic acids such as bis(3,4-dicarboxyphenyl)sulfone.

Examples of monohydric alcohols that can be used in the present invention include lower aliphatic monohydric alcohols, aromatic monohydric alcohols, alicyclic monohydric alcohols, and monohydric alcohols having an ether group. Among these, examples of lower aliphatic alcohols include aliphatic alcohols having 1 to 6 carbon atoms such as methanol, ethanol, propanol, and butanol, and examples of aromatic monohydric alcohols include benzyl alcohol and α-(or β). -) Examples of alicyclic monohydric alcohols such as phenethyl alcohol include pentanol and cyclohexanol, and examples of monohydric alcohols having an ether group include methyl cellosolve and ethyl cellosolve.

The monohydric alcohol diester (B) of aromatic tetracarboxylic acid is preferably polymerized and blended into the imidized oligomer (A) at a temperature of 140°C or lower,
In particular, it is preferable to carry out the reaction at a temperature of 80°C or lower. If the blending temperature is set to 140°C or higher and maintained at this temperature for a long time, a polymerization reaction will start during this period and the solution viscosity will increase. This makes it difficult to use it for various purposes, and it is also disadvantageous in other uses.

Next, Examples and Comparative Examples of the present invention will be shown.

In each of the following examples, the solution viscosity was measured as rotational viscosity using an E-type viscometer manufactured by Tokyo Keiki Co., Ltd. The tensile strength of the produced film was measured using an Autograph DSS-5000 manufactured by Shimadzu Corporation, with a sample width of 10 mm, chuck distance of 50 mm, and a tensile speed of 50 mm/min.
I did it in minutes.

Example 1 Into the separable flask 1, 2, 3, 3',
4′-biphenyltetracarboxylic dianhydride 16.78
g (0.057 mol), 3,3',4,4'-biphenyltetracarboxylic dianhydride 16.78 g (0.057 mol),
4,4'-diaminodiphenyl ether 24.02g
(0.120 mol) and 230.30 g of m-cresol were added, and this was heated and stirred in an oil bath at 170°C for 3 hours to obtain a polymerized/imidized oligomer solution () having a solution viscosity of 101 poise/30°C.

The acid component of the polymerized/imidized oligomer in this solution () is 95 mol% relative to the diamine component.

Separately, in a 100 ml flask, add 3,3',4,4'-
Biphenyltetracarboxylic dianhydride 2.94g
(0.010 mol), 2.77 g (0.060 mol) of ethyl alcohol, and 13.63 g of m-cresol,
Heat and stir for 1.5 hours in an oil bath at ℃, 3.
A solution of 3',4,4'-biphenyltetracarboxylic acid ethyl alcohol diester () was obtained.

Solution () 95.98g (diamine component 0.040mol,
(contains 0.038 mole of acid component), 3.86 g of solution ()
(containing 0.002 mol of acid component) was added at room temperature and stirred for 5 hours to obtain an aromatic polyimide solution composition ().

This aromatic polyimide solution composition (2) was a homogeneous solution, and the solution viscosity was 90 poise/30°C. This solution () was stored at 30° C. for 3 months, but maintained a uniform solution state.

The aromatic polyimide solution composition () was applied onto a glass plate and heated at 80° C. for 30 minutes, then raised to 300° C. for 1 hour to obtain a film with a thickness of about 20 μm. When the tensile strength of this film was measured, the strength at break was 14.3 Kg/mm ² and the elongation was 60%.

Example 2 2.94 g (0.010 mol) of 3,3',4,4'-biphenyltetracarboxylic dianhydride, 2.19 g (0.020 mol) of benzyl alcohol, and 20.63 g of m-cresol were placed in a 100 ml flask. Heat and stir for 1.5 hours in an oil bath at 140°C.
A 4'-biphenyltetracarboxylic acid benzyl alcohol diester solution (a) was obtained.

4.61 g of this solution (a) (containing 0.0018 mol of acid component) was mixed with 85.82 g of the polymerized/imidide oligomer solution () obtained in Example 1 (containing 0.0358 mol of diamine component).
mol, containing 0.0340 mol of acid component) at room temperature 5
Stir for hours. The obtained aromatic polyimide solution composition (a) was uniform and had a solution viscosity of 158 poise/30
It was warm at ℃.

Example 3 In a 300ml separable flask, 2, 3, 3',
4′-biphenyltetracarboxylic dianhydride 9.42g
(0.032 mol), 3,3',4,4'-biphenyltetracarboxylic dianhydride 9.42 g (0.032 mol), 4,
4′-diaminodiphenyl ether 16.02g (0.080
mol), and 81.76 g of m-cresol,
This was stirred for 2 and a half hours in an oil bath at 170°C.
A polymerized/imidized oligomer solution (b) having a solution viscosity of 42 poise/30°C was obtained.

The acid component of the polymerized/imidized oligomer of this solution (b) is 80 mol % based on the diamine component.

Separately, in a 100 ml flask, 2.94 g of 3,3',4,4'-biphenyltetracarboxylic dianhydride.
(0.010 mol), ethyl alcohol 1.87 g (0.041 mol), and m-cresol 8.12 g, and heated to 140°C.
Heat and stir for 1.5 hours in an oil bath of 3,3′,
An ethyl alcohol diester solution (b) of 4,4'-biphenyltetracarboxylic acid was obtained.

Solution (b) in 57.88g (contains 0.040 mol of diamine component and 0.032 mol of acid component)
10.28g (containing 0.008 mol of acid component) was added at room temperature and stirred for 4 hours to form an aromatic polyimide solution composition (
b) was obtained. This solution (b) was uniform and had a solution viscosity of 41 poise/30°C.

The aromatic polyimide solution composition (b) was applied onto a glass plate and heated at 80° C. for 30 minutes, then raised to 300° C. for 1 hour to obtain a film with a thickness of about 20 μm.
When the tensile strength of this film was measured, the strength at break was 16.3 Kg/mm ² and the elongation was 73%.

Example 4 In a 300ml separable flask, 2, 3, 3',
4′-biphenyltetracarboxylic dianhydride 7.95g
(0.027 mol), 8.70 g (0.027 mol) of benzophenonetetracarboxylic dianhydride, 12.01 g (0.060 mol) of 4,4'-diaminodiphenyl ether, and 114.84 g of m-cresol were heated at 170°C.
Heat and stir for 2 hours in an oil bath to reduce the solution viscosity to 59.
A poise/30°C polymerized/imidide oligomer solution (c) was obtained.

The polymerized/imidized oligomer acid component of this solution (c) was 90 mol % based on the diamine component.

Separately, put 3.22 g (0.010 mol) of benzophenonetetracarboxylic dianhydride, 3.05 g (0.040 mol) of methyl cellosolve, and 17.47 g of m-cresol in a 100 ml flask and heat in an oil bath at 140°C for 2 hours. The mixture was stirred to obtain a benzophenonetetracarboxylic acid methyl cellosolve diester solution (c).

Solution (c) in 90.78 g (contains 0.038 mol of diamine component and 0.034 mol of acid component)
Add 9.01 g (containing 0.004 mol of acid component) at room temperature.
Stirred for 16 hours. The resulting aromatic polyimide solution composition (c) was uniform and had a solution viscosity of 101 poise/30°C.

Example 5 In a 300ml separable flask, 2, 3, 3',
4'-biphenyltetracarboxylic dianhydride 6.18g
(0.021 mol), 3,3',4,4'-biphenyltetracarboxylic dianhydride 6.18 g (0.021 mol), 4,
4′-diaminodiphenyl ether 12.03g (0.060
mol) and m-cresol (45.09 g) were added, and this was heated and stirred in an oil bath at 180°C for 2.5 hours to obtain a polymerized/imidized oligomer solution (d) with a solution viscosity of 80 poise/30°C.

The acid component of the polymerized/imidized oligomer of this solution (d) is 70 mol % based on the diamine component.

Separately, in a 100 ml flask, 8.82 g of 3,3',4,4'-biphenyltetracarboxylic dianhydride.
(0.030 mol), ethyl alcohol 5.55 g (0.120 mol), and m-cresol 24.42 g,
Heat and stir for 2 hours in an oil bath at ℃,
An ethyl alcohol diester solution (d) of 4,4'-biphenyltetracarboxylic acid was obtained.

Solution (d) in 62.40g (contains 0.054 mol of diamine component and 0.038 mol of acid component)
20.37 g (containing 0.016 mol of acid component) was added at room temperature and stirred for 5 hours. The obtained aromatic polyimide solution composition (d) was uniform and had a solution viscosity of 47 poise/
It was 30 degrees Celsius.

Example 6 In a 300ml separable flask, 2, 3, 3',
4′-biphenyltetracarboxylic dianhydride 10.59
g (0.036 mol), 3,3',4,4'-biphenyltetracarboxylic dianhydride 3.54 g (0.012 mol),
4,4'-diaminodiphenyl ether 11.91g
(0.060 mol) and 61.05 g of m-cresol were added, and the mixture was heated and stirred for 1.5 hours in an oil bath at 170°C to obtain a polymerized/imidized oligomer solution (e) at 25 poise/30°C.

The acid component of the polymerized/imidized oligomer of this solution (e) is 80 mol % based on the diamine component.

Separately, in a 100 ml flask, add 6.54 g (0.030 mol) of pyromellitic dianhydride and ethyl alcohol.
5.52 g (0.120 mol) and m-cresol 18.99
g, and heated and stirred in an oil bath at 140° C. for 1.5 hours to obtain a pyromellitic acid ethyl alcohol diester solution (e).

Solution (e) in 81.48g (contains 0.056 mol of diamine component and 0.045 mol of acid component)
11.64 g (containing 0.011 mol of acid component) was added at room temperature and stirred for 5 hours. The obtained aromatic polyimide solution composition (e) was uniform and had a solution viscosity of 25 poise/
It was 30 degrees Celsius.

Example 7 In a 300ml separable flask, 2, 3, 3',
4′-biphenyltetracarboxylic dianhydride 5.59g
(0.019 mol), 3,3',4,4'-biphenyltetracarboxylic dianhydride 5.59 g (0.019 mol), m-phenylenediamine 3.02 g (0.028 mol), 4,4'-
Add 2.40 g (0.012 mol) of diaminodiphenyl ether and 66.58 g of m-cresol, heat and stir in an oil bath at 170°C for 2 hours to obtain a polymerized/imidide oligomer solution with a solution viscosity of 51 poise/30°C ( f) was obtained.

The acid component of the polymerized/imidized oligomer of this solution (f) is 95 mol % based on the diamine component.

Separately, in a 100 ml flask, add 2.18 g (0.010 mol) of pyromellitic dianhydride and ethyl alcohol.
1.97 g (0.042 mol) and m-cresol 11.53
g was added thereto, and the mixture was heated and stirred in an oil bath at 140° C. for 1.5 hours to obtain a pyromellitic acid ethyl alcohol diester solution (f).

Solution (f) in 76.98g (contains 0.037 mol of diamine component and 0.035 mol of acid component)
Add 2.98 g (containing 0.02 mol of acid component) at room temperature 5
Stir for hours. The obtained aromatic polyimide solution composition (f) was uniform and had a solution viscosity of 47 poise/30
It was warm at ℃.

Example 8 In a 300ml separable flask, 2, 3, 3',
4′-biphenyltetracarboxylic dianhydride 5.59g
(0.019 mol), 5.59 g (0.019 mol) of 3,3',4,4'-biphenyltetracarboxylic dianhydride, 8.49 g (0.040 mol) of o-tolidine, 55.07 g of m-cresol, and 23.64 g of phenol. put this
The mixture was heated and stirred in an oil bath at 170°C for 2.5 hours to obtain a polymerized/imidized oligomer solution (g) having a solution viscosity of 63 poise/30°C.

The acid component of the polymerized/imidized oligomer in this solution (g) is 90 mol % based on the diamine component.

This solution (g) 53.47g (diamine component 0.022
1.70 g of the solution (f) obtained in Example 7 (containing 0.001 mole of acid component) was added to the solution (containing 0.021 mole of acid component) at room temperature, and the mixture was stirred for 5 hours. The obtained aromatic polyimide solution composition (g) was uniform and had a solution viscosity of 60 poise/30°C.

Comparative Example 1 In a 300ml separable flask, 2, 3, 3',
4'-biphenyltetracarboxylic dianhydride 8.83g
(0.030 mol), 3,3',4,4'-biphenyltetracarboxylic dianhydride 8.83 g (0.030 mol), 4,
4′-diaminodiphenyl ether 12.01g (0.060
mol) and m-cresol (118.02 g) were added, and the mixture was heated and stirred in an oil bath at 170° C. for 2 hours to effect polymerization and imidization.

The acid component of the polymerized/imidized product in this polymerized/imidized product solution is 100% by mole based on the diamine component.

As described above, the aromatic polyimide solution obtained by simply polymerizing and imidizing equimolar amounts of the acid component and the diamine component without using the monohydric alcohol diester of the aromatic tetracarboxylic acid can contain about 20% of the polyimide.
Although it was a uniform polyimide solution with a polyimide content of % by weight, it exhibited a very high solution viscosity of 10,000 poise/30°C or more.

Comparative Example 2 The polymerized/imidide oligomer solution () obtained in Example 1 was applied onto a glass plate and heated at 80°C for 30 minutes.
Next, raise the temperature to 300℃ and heat it for 1 hour to about 20~25μ
A thick film was obtained. Breaking point strength of this film
The weight was 12.6Kg/mm ² and the elongation was 10%.

Comparative Example 3 The polymerized/imidized oligomer solution (a) obtained in Example 3 was applied onto a glass plate, heated at 80°C for 30 minutes, and then heated at 300°C for 1 hour. The resulting product was damaged by slight contact and could hardly be called a film.

Claims (1)

[Scope of Claims] 1 (A) An aromatic diamine and 40 mol% of 2,3,3',4'-biphenyltetracarboxylic dianhydride, which is 65 to 98 mol% based on the diamine component. A polymerized/imidized oligomer with an aromatic tetracarboxylic dianhydride containing the above, and (B) an aromatic amount such that the acid component and diamine component in the polymerized/imidized oligomer are substantially equimolar. An aromatic polyimide solution composition comprising a monohydric alcohol diester of a group tetracarboxylic acid dissolved in a phenolic solvent. 2 The monohydric alcohol diester of aromatic tetracarboxylic acid is one type selected from the group consisting of lower aliphatic monohydric alcohol, aromatic monohydric alcohol, alicyclic monohydric alcohol, and monohydric alcohol having an ether group. The aromatic polyimide solution composition according to claim 1, which is a monohydric alcohol diester of the aromatic tetracarboxylic acid mentioned above. 3 The aromatic tetracarboxylic dianhydride forming the polymerized/imidized oligomer of (A) above is substantially 40 to 80 mol% of 2,3,3',4'-biphenyltetracarboxylic dianhydride. and 60 to 20 mol% of another aromatic tetracarboxylic dianhydride, the aromatic polyimide solution composition according to claim 1. 4. Claim No. 4, characterized in that 50 mol% or more of the other aromatic tetracarboxylic dianhydrides is 3,3',4,4'-biphenyltetracarboxylic dianhydride. The aromatic polyimide solution composition according to item 3. 5. Claim 4, characterized in that the other aromatic tetracarboxylic dianhydride consists essentially of 3,3',4,4'-biphenyltetracarboxylic dianhydride. aromatic polyimide solution composition. 6 Claims characterized in that 50 mol% or more of the other aromatic tetracarboxylic dianhydrides is 3,3',4,4'-benzophenonetetracarboxylic dianhydride 4. Aromatic polyimide solution composition according to item 3. 7. The aromatic polyimide solution composition according to claim 1, wherein the aromatic diamine is 4,4'-diaminodiphenyl ether.