JPH0126371B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an aromatic polyamic acid solution composition. More particularly, the present invention relates to an aromatic polyamic acid solution composition particularly suitable for use as an insulating coating. Aromatic polyimides obtained by imidizing aromatic polyamic acids are known to be particularly excellent in heat resistance, insulation, and mechanical properties.
For this reason, for example, for the purpose of coating various materials, especially insulating coating of electrical materials such as electric wires,
A commonly used method is to apply a polyamic acid solution to the surface of a material to be coated and then heat imidization to form an aromatic polyimide film. Aromatic polyamic acid can be prepared by a polymerization reaction of a tetracarboxylic acid component and a diamine component, and among these, the following are known as representative examples of the tetracarboxylic acid component and the diamine component. Tetracarboxylic acid component Pyromellitic dianhydride 3,3',4,4'-benzophenonetetracarboxylic dianhydride 3,3',4,4'-biphenyltetracarboxylic dianhydride Diamine component 4, 4'-Diaminodiphenylmethane 4,4'-Diaminodiphenyl ether m-phenylenediamine p-phenylenediamine In other words, aromatic polyamic acids include the above-mentioned tetraaromatic carboxylic acid component and aromatic diamine component. Those obtained by polymerizing are generally used. Among them, aromatic polyamic acid obtained by polymerizing pyromellitic dianhydride and aromatic diamine has been known for a relatively long time and has been used for various purposes. However, aromatic polyamic acid obtained by polymerizing pyromellitic dianhydride and aromatic diamine has drawbacks in its properties and workability. For example, when aromatic polyamic acid is used as an insulating coating, a method is generally used in which a solution of aromatic polyamic acid is applied to the surface to be coated as described above. The problem with aromatic polyamic acid is that its storage stability in a solution state is extremely poor.
In other words, a solution of aromatic polyamic acid may start to rapidly increase in viscosity at ambient temperature and cause gelation, or conversely cause a significant decrease in viscosity and require immediate application. becomes unsuitable for Therefore, to prevent extreme viscosity fluctuations of such solutions, aromatic polyamic acid solutions are usually stored in a refrigerator. However, such industrial materials that require storage in a refrigerator are extremely disadvantageous in practical terms, and aromatic polyamic acid obtained from pyromellitic dianhydride can be stored for a long time even if stored in a refrigerator. However, there is a problem in that the above-mentioned viscosity fluctuations are likely to occur. In addition, for aromatic polyamic acid obtained from other known tetracarboxylic acid components (for example, 3,3',4,4'-biphenyltetracarboxylic dianhydride) and aromatic diamine components, insulation paint It has drawbacks such as turbidity when baked on electric wires and insufficient salt water resistance, so it cannot be said to be practically satisfactory, especially when used as an insulating paint. On the other hand, aromatic polyamic acid obtained from benzophenonetetracarboxylic dianhydride and an aromatic amine component is not satisfactory for practical purposes, especially since the resulting polyimide does not have sufficient mechanical strength. do not have. The present invention is particularly useful as an insulating paint that has improved the drawbacks of the conventional insulating paints, such as unstable viscosity, turbidity when baked on electric wires, and insufficient salt water resistance. The present invention provides a highly useful aromatic polyamic acid solution. The present invention relates to 3,3',4,4'-biphenyltetracarboxylic dianhydride and/or its derivatives and 3,3',4,4'-benzophenonetetracarboxylic dianhydride and/or 30:70 with its derivatives
The acid component (aromatic tetracarboxylic acid or its derivative) containing at a molar ratio of ~75:25 and in which these compounds account for 80 mol% or more of the total acid component, and the aromatic diamine are substantially The logarithmic viscosity obtained by polymerization is 0.1 to 1.5 [30
C, 0.5 g/100 ml (N-methyl-2-pyrrolidone)] of aromatic polyamic acid dissolved in an organic polar solvent in an amount of 5 to 40% by weight. The aromatic polyamic acid solution composition of the present invention is
Although it contains a high concentration of the polymer component, ie, aromatic polyamic acid, its solution viscosity is low, and it is particularly excellent in storage stability. moreover,
The aromatic polyimide resin formed from the aromatic polyamic acid solution composition of the present invention not only has high heat resistance and insulation properties, but also has mechanical strength and salt water resistance at a practically sufficient level. In particular, the excellent storage stability of the aromatic polyamic acid solution composition of the present invention is not only superior to aromatic polyamic acid obtained by polymerizing pyromellitic dianhydride and aromatic diamine. , aromatic polyamic acid obtained by polymerization of 3,3',4,4'-benzophenonetetracarboxylic dianhydride and aromatic diamine, and 3,
The present invention is superior in this respect to any aromatic polyamic acid obtained by polymerizing 3',4,4'-biphenyltetracarboxylic dianhydride and aromatic diamine. This is particularly advantageous in practice. Therefore, the aromatic polyamic acid solution composition of the present invention is particularly useful for use as an insulating coating (for example, a varnish for manufacturing enameled wire), which is coated on the surface of electrical materials to form a polyimide insulating coating. It is. In addition, since the aromatic polyamic acid solution composition of the present invention has the above-mentioned excellent properties, it can be used as a coating material for various materials, a dope solution for molding polyimide films, a main component of adhesives, and various organic or inorganic materials. It can be widely used for applications such as varnish for impregnating fibrous substrates. Next, the present invention will be explained in detail. The aromatic polyamic acid of the present invention has 3,3′,
An acid whose main components are 4,4'-biphenyltetracarboxylic dianhydride and/or its derivatives and 3,3',4,4'-benzophenonetetracarboxylic dianhydride and/or its derivatives. component and an aromatic diamine (for example, 4,4'-diaminodiphenyl ether). (A) 3,3',4,4'-biphenyltetracarboxylic dianhydride and/or its derivative, which is the main acid component of the aromatic polyamic acid of the present invention, and (B) 3,3',4,4'-benzophenonetetracarboxylic dianhydride and/or its derivatives, the molar ratio of A:B must be in the range of 30:70 to 75:25, and the molar ratio of A and B must be in the range of 30:70 to 75:25. The total must account for 80 mol% or more of the total acid components. However, A:
The molar ratio of B is preferably in the range of 45:55 to 75:25, and the total of A and B is preferably 90 mol% or more of the total acid component, so that the acid component is substantially 45:55 to 75:25. It is particularly preferable to consist of only In the display of each aromatic tetracarboxylic acid above, ``derivative'' includes tetracarboxylic acid,
Includes diacids/anhydrides, diesters/anhydrides, diacid diesters, tetraesters, etc. Further, the aromatic diamine used as the diamine component in the present invention preferably consists essentially only of 4,4'-diaminodiphenyl ether, but as long as the diamine component is less than 20 mol%, other diamines (aromatic Preferably it is a diamine). Examples of aromatic diamines that can be used in conjunction with 4,4'-diaminodiphenyl ether include aromatic diamine compounds represented by the following general formulas [], [], and []. In the general formula [], [], [], R ¹ , R ² ,
R ³ is hydrogen, lower alkyl group, carboxyl group,
Represents a substituent such as a lower alkoxy group, and A
-S-, -CO-, _-SO2- , -SO-, _-CH2-
Represents a divalent linking group such as. Among the aromatic diamine compounds represented by the general formulas [], [], and [], compounds preferably used in conjunction with 4,4'-diaminodiphenyl ether include 4,4'-diaminodiphenyl Methane, 4,4'-diaminodiphenylthioether, 4,4'-diaminodiphenylbenzophenone, 4,4'-diaminodiphenyl sulfone,
Examples include o-tolidine, o-dianisidine, 3,5-diaminobenzoic acid, m- or p-phenylenediamine, and the like. In the present invention, the aromatic diamines exemplified above can be used alone without being used in combination with 4,4'-diaminodiphenyl ether as described above. The aromatic polyamic acid of the present invention is obtained by polymerizing substantially equimolar amounts of the acid component and diamine component as described above. In this specification, "substantially equimolar" means that one component is within about 3 mol% (preferably about 1 mol%) of the other component, unless both components are in a completely equimolar relationship. (within) but also includes cases where it is in excess. Methods for obtaining polyamic acid by polymerizing various acid components and diamine components are already known, and the aromatic polyamic acid of the present invention can be obtained using known methods. That is, for example, a method in which substantially equimolar amounts of an acid component and a diamine component are polymerized in an organic polar solvent such as N-methyl-2-pyrrolidone; A method of polymerizing in an organic polar solvent in the presence of water; an acid component and a diamine component are reacted with an excess of the diamine component to obtain an intermediate such as an oligomer, and then the acid component and diamine component are added to this as a whole. A method in which an acid component is added and the reaction is carried out so that the amount of the diamine component is substantially equimolar to obtain polyamic acid; an intermediate such as an oligomer is obtained by reacting an acid component and a diamine component with the acid component in excess. Thereafter, a diamine component is added to this so that the acid component and diamine component are substantially equimolar as a whole, and a reaction is carried out to obtain polyamic acid; An amine-based intermediate such as an oligomer obtained by reacting an acid component and a diamine component, and an acid-based intermediate such as an oligomer obtained by reacting an acid component and a diamine component with an excess amount of the acid component are separately produced, Then,
Use a method such as mixing these so that the acid component and diamine component are substantially equimolar as a whole (diamine component or acid component may be added if necessary) and reacting to form polyamic acid. can do. The aromatic polyamic acid of the present invention is a polymer having a relatively low average molecular weight and has a logarithmic viscosity of 0.1 to 1.5 [measured value at 30°C, 0.5 g/100 ml (N-methyl-2-pyrrolidone)]. Must. However, aromatic polyamic acids with even lower average molecular weights, such as those whose logarithmic viscosity shows a value lower than 0.1 under the above measurement conditions, are not suitable because they do not form a polyimide film with sufficient mechanical strength; Aromatic polyamic acid with a high molecular weight that exhibits a value higher than 1.5 under measurement conditions has an extremely high solution viscosity when a solution containing polyamic acid at a high concentration like the solution composition of the present invention is prepared. This is not suitable because the solution becomes difficult to handle and workability decreases. The aromatic polyamic acid solution composition of the present invention is
The above aromatic polyamic acid is present in an organic polar solvent at a high concentration, specifically 5 to 40% by weight (preferably 6% by weight).
~35% by weight, particularly preferably 10~35% by weight). Such a highly concentrated solution can also be prepared by removing the polyamic acid produced as described above from the reaction solvent and then adding it to a polar solvent and dissolving it. By using the organic polar solvent of the polyamic acid solution composition of the present invention as a reaction solvent when producing polyamic acid by polymerizing the polyamic acid solution composition of the present invention, the polyamic acid solution composition of the present invention can be produced without taking out the polyamic acid from the reaction solution. You can also get it directly. The organic polar solvent used in the aromatic polyamic acid solution composition of the present invention has a boiling point of 300°C at normal pressure.
Below, those below 250°C are particularly preferred, and examples thereof include N-methyl-2-pyrrolidone, dimethylsulfoxide, N,N-dimethylacetamide, N,N-dimethylformamide, N,N-diethylacetamide, N, N-diethylformamide and dimethylsulfone can be mentioned. Particularly preferred organic polar solvents for use in the aromatic polyamic acid solution composition of the present invention are N-methyl-2-pyrrolidone, dimethyl sulfoxide, N,N-dimethylacetamide and N,N-dimethylformamide. Note that these organic polar solvents can also be used in combination with other organic solvents such as benzene, toluene, benzonitrile, xylene, solvent naphtha, and dioxane. Although it is desirable to have a small amount of water (e.g., about 10% by weight or less) present when producing the composition of the present invention, the resulting composition cannot be washed by conventional methods such as vacuum water distillation. It is desirable to remove as much of the mixed water as possible using water removal operations. However, for water that cannot be removed by normal water removal operations such as distillation of water under reduced pressure (the amount of water can be determined by using the Karl-Fitschier method), 3% by weight of the water in the composition. There is no problem even if it remains as long as it is below (preferably 2% by weight or below). The aromatic polyamic acid solution composition of the present invention exhibits a relatively low viscosity despite containing a high concentration of polyamic acid, and the viscosity remains relatively stable even at room temperature. For example, when the aromatic polyamic acid solution composition of the present invention is stored at a storage temperature of about 30° C., it generally does not show a large change in viscosity over a period of about 6 months or more. Further, even when the storage temperature is about 50°C, the viscosity does not show a large change for more than about 3 months. Furthermore, the aromatic polyamic acid solution composition of the present invention has the advantage that it is difficult to gel even when stored at room temperature for a long period of time. Therefore, the aromatic polyamic acid solution composition of the present invention does not require refrigeration equipment for its preservation as long as it is used under normal conditions. Note that, in consideration of practical workability, the aromatic polyamic acid solution composition of the present invention preferably exhibits a rotational viscosity of 0.1 to 10,000 poise as measured at 30°C. A more preferable rotational viscosity value is 0.5~
5000 poise, particularly preferably 1 to 2000 poise. Next, Examples and Comparative Examples of the present invention will be shown. Example 1 3, 3', 4,
4'-Diphenyltetracarboxylic dianhydride 14.71
g (0.05 mol), 3,3',4,4'-benzophenonetetracarboxylic dianhydride 16.11 g (0.05 mol),
4,4'-diaminodiphenyl ether 20.02g
(0.1 mol), N-methyl-2-pyrrolidone 197.3 g
and 6.10 g of water were added. This mixture was stirred at a reaction temperature of 30°C for 44 hours under normal pressure to perform a polymerization reaction, and the logarithmic viscosity was 0.56 [30°C, 0.5 g/100 ml (N-
Methyl-2-pyrrolidone) measurement value, the same applies hereinafter]
A reaction solution containing aromatic polyamic acid was obtained. Next, this reaction solution was left under reduced pressure (0.01 atm) for 2 hours while maintaining it at 50°C to evaporate and remove free water, and the water content was 1.1% by weight (measured by Karl-Fitscher titration method). A polyamic acid solution composition having the following values (hereinafter the same) was obtained. The polymer concentration (polyamic acid concentration, hereinafter the same) of this polyamic acid solution composition was 22.0% by weight,
The solution viscosity was 52 Boaz (rotational viscosity at 30°C, the same applies hereinafter). The obtained polyamic acid solution composition was heated at 50°C.
After storage for 60 days, the solution viscosity was measured and showed 54 poise, and after storage at 50°C for 120 days, the solution viscosity was measured and found to be 58 poise. However, after being stored at 50°C for 140 days, a rapid increase in viscosity was observed and the product became non-fluid. On the other hand, when the storage condition was changed to 30°C and the change in solution viscosity of the above polyamic acid solution composition over time was investigated, it showed a low value of 66 poise even after 180 days. Under any of these storage conditions, the polyamic acid solution composition exhibited a uniform solution state before gelation, and no precipitation was observed. When the polyamic acid solution composition obtained here was evaluated as a varnish for manufacturing enameled wire, various mechanical properties,
In addition to showing sufficient levels of heat resistance and electrical properties, it also showed excellent results in salt water resistance. Example 2 The reaction raw materials and solvent were 20.59 g (0.07
mol), 3,3',4,4'-benzophenonetetracarboxylic dianhydride 9.67g (0.03 mol), 4,4'-
Diaminodiphenyl ether 20.02g (0.10mol), N-methyl-2-pyrrolidone 180.40g, and water 5.6g, reaction temperature and reaction time were 50℃,
The polymerization reaction was carried out in the same manner as in Example 1, except that the reaction time was changed to 20 hours, to obtain a reaction solution containing aromatic polyamic acid having a logarithmic viscosity of 0.55. Next, a water removal operation was carried out in the same manner as in Example 1 to obtain a polyamic acid solution composition having a water content of 1.0% by weight. The polymer concentration of this polyamic acid solution composition was 22.5% by weight, and the solution viscosity was 60 poise. The obtained polyamic acid solution composition was heated at 50°C and 60°C.
The solution viscosity after storage for one day was 67 poise. Under storage conditions of 50°C, gelation occurred after storage for 130 days. Under the above storage conditions and before gelation, the above polyamic acid solution composition exhibited a uniform solution state, and no precipitation was observed. When the polyamic acid solution composition obtained here was evaluated as a varnish for manufacturing enameled wire, various mechanical properties,
In addition to showing sufficient levels of heat resistance and electrical properties, it also showed excellent results in salt water resistance. Example 3 The reaction raw materials and solvent were 17.65 g (0.06
mol), 3,3',4,4'-benzophenonetetracarboxylic dianhydride 12.89g (0.04 mol), 4,
20.02 g (0.1 mole) of 4'-diaminodiphenyl ether, 190.7 g of dimethylacetamide, and water
A polymerization reaction was carried out in the same manner as in Example 1, except that the amount was 5.9 g, and the reaction temperature and reaction time were 50°C and 20 hours.
A reaction solution containing a derivative polyamic acid having a logarithmic viscosity of 0.53 was obtained. Next, water was removed in the same manner as in Example 1 to obtain a polyamic acid solution composition having a water content of 0.9% by weight. The polymer concentration of this polyamic acid solution composition was 22.0% by weight, and the solution viscosity was 45 poise. The obtained polyamic acid solution composition was heated at 50°C and 60°C.
The solution viscosity after storage for one day was 52 poise. Under storage conditions of 50°C, gelation occurred after storage for 140 days. Under the above storage conditions and before gelation, the above polyamic acid solution composition exhibited a uniform solution state, and no precipitation was observed. When the polyamic acid solution composition obtained here was evaluated as a varnish for manufacturing enameled wire, various mechanical properties,
In addition to showing sufficient levels of heat resistance and electrical properties, it also showed excellent results in salt water resistance. Example 4 The reaction raw materials and solvent were 8.83 g (0.03 mol) of 3,3',4,4'-biphenyltetracarboxylic dianhydride and 3,3',4,4'-benzophenonetetracarboxylic acid. 22.56 g (0.07 mol) dianhydride, 4,4'-
Diaminodiphenyl ether 20.02g (0.1mol),
A polymerization reaction was carried out in the same manner as in Example 1, except that 189.5 g of dimethyl sulfoxide and 5.9 g of water were used, to obtain a reaction solution containing aromatic polyamic acid having a logarithmic viscosity of 0.46. Next, a water removal operation was carried out in the same manner as in Example 1 to obtain a polyamic acid solution composition having a water content of 1.1% by weight. The polymer concentration of this polyamic acid solution composition was 22.4% by weight, and the solution viscosity was 43 poise. The obtained polyamic acid solution composition was heated at 50°C and 60°C.
The solution viscosity after storage for one day was 44 poise. Under storage conditions of 50°C, gelation occurred after storage for 130 days. Under the above storage conditions and before gelation, the above polyamic acid solution composition exhibited a uniform solution state, and no precipitation was observed. When the polyamic acid solution composition obtained here was evaluated as a varnish for manufacturing enameled wire, various mechanical properties,
It also showed excellent results in terms of salt water resistance. Example 5 The reaction raw materials and solvent were 14.71 g (0.05
(mol), 3,3',4,4'-benzophenonetetracarboxylic dianhydride 16.11g (0.05mol), m-phenylenediamine 10.81g (0.1mol), N-methyl-2-pyrrolidone 151.3g , and 4.7 g of water, and a polymerization reaction was carried out in the same manner as in Example 1, except that the reaction temperature and reaction time were 30° C. and 20 hours, to obtain a reaction solution containing aromatic polyamic acid with a logarithmic viscosity of 0.43. . Next, a water removal operation was carried out in the same manner as in Example 1 to obtain a polyamic acid solution composition having a water content of 0.8% by weight. The polymer concentration of this polyamic acid solution composition was 22.1% by weight, and the solution viscosity was 38 poise. The obtained polyamic acid solution composition was heated at 50°C and 60°C.
The solution viscosity after storage for one day was 36 poise. Under storage conditions of 50°C, gelation occurred after storage for 130 days. Under the above storage conditions and before gelation, the above polyamic acid solution composition exhibited a uniform solution state, and no precipitation was observed. When the polyamic acid solution composition obtained here was evaluated as a varnish for manufacturing enameled wire, various mechanical properties,
It also showed excellent results in terms of salt water resistance. Example 6 The reaction raw materials and solvent were 14.71 g (0.05
mol), 3,3',4,4'benzophenonetetracarboxylic dianhydride 16.11g (0.05 mol), 4,4'-
Diaminodiphenylmethane 19.83g (0.1mol),
188.0g of N-methyl-2-pyrrolidone and water
A polymerization reaction was carried out in the same manner as in Example 1, except that the amount was 5.8 g, and the reaction temperature and reaction time were 30°C and 20 hours.
A reaction solution containing aromatic polyamic acid with a logarithmic viscosity of 0.49 was obtained. Next, water was removed in the same manner as in Example 1 to obtain a polyamic acid solution composition having a water content of 0.9% by weight. The polymer concentration of this polyamic acid solution composition was 22.0% by weight, and the solution viscosity was 43 poise. The obtained polyamic acid solution composition was heated at 50°C and 60°C.
The solution viscosity after storage for one day was 41 poise. Under storage conditions of 50°C, gelation occurred after storage for 140 days. Under the above storage conditions and before gelation, the above polyamic acid solution composition exhibited a uniform solution state, and no precipitation was observed. When the polyamic acid solution composition obtained here was evaluated as a varnish for manufacturing enameled wire, various mechanical properties,
It also showed excellent results in terms of salt water resistance. Example 7 (1) Synthesis of oligomer A In a cylindrical polymerization tank with an internal volume of 300ml, 3, 3', 4,
4′-biphenyltetracarboxylic dianhydride 11.77
g (0.04 mol), 4,4'-diaminodiphenyl ether 4.00 g (0.02 mol), and N-methyl-
63.09 g of 2-pyrrolidone was added. this mixture
The reaction was carried out with stirring for 3 hours at a reaction temperature of 50° C. and under normal pressure. The reaction solution contains unreacted 3,3',4,4'-
The dispersion contained biphenyltetracarboxylic dianhydride. (2) Synthesis of oligomer B 3, 3', 4,
4′-Benzophenonetetracarboxylic dianhydride
19.33 g (0.06 mol), 18.02 g (0.09 mol) of 4,4'-diaminodiphenyl ether, and 149.4 g of N-methyl-2-pyrrolidone were added. This mixture was stirred for 3 hours at a reaction temperature of 30° C. and under normal pressure to carry out the reaction. The reaction solution was a homogeneous polymer solution (polymer concentration 20% by weight, solution viscosity 3.5 poise). (3) Production of polyamic acid solution composition Oligomer A (78.86g) and oligomer B
(124.51 g) was added and stirred at 50° C. for 3 hours to carry out a polymerization reaction, thereby obtaining a polyamic acid solution composition containing aromatic polyamic acid having a logarithmic viscosity of 0.63. The polymer concentration of this polyamic acid solution composition is 20.0% by weight, and the solution viscosity is 38
It was Poise. The obtained polyamic acid solution composition was heated at 50°C and 60°C.
The solution viscosity after storage for 1 day and 120 days is respectively
They were 43 and 49 poise. Under storage conditions of 50°C, gelation occurred after storage for 140 days. Under the above storage conditions and before gelation, the above polyamic acid solution composition exhibited a uniform solution state, and no precipitation was observed. When the polyamic acid solution composition obtained here was evaluated as a varnish for manufacturing enameled wire, various mechanical properties,
It also showed excellent results in terms of salt water resistance. Comparative Example 1 The reaction raw materials and solvent were 29.42 g (0.1 mol) of 3,3',4,4'-biphenyltetracarboxylic dianhydride and 20.02 g of 4,4'-diaminophenyl ether.
(0.1 mol), N-methyl-2-pyrrolidone 183.7
g, and 20.4 g of water, and the reaction temperature and reaction time are
A polymerization reaction was carried out in the same manner as in Example 1, except that the temperature was 50° C. for 60 hours, to obtain a reaction solution containing aromatic polyamic acid with a logarithmic viscosity of 0.45. Next, a water removal operation was carried out in the same manner as in Example 1 to obtain a polyamic acid solution composition having a water content of 1.1% by weight. The polymer concentration of this polyamic acid solution composition was 22.3% by weight, and the solution viscosity was 41 poise. The obtained polyamic acid solution composition was heated at 50°C and 60°C.
The solution viscosity after storage for one day was 63 poise. However, under the storage condition of 50°C, gelation occurred after storage for 70 days. Comparative Example 2 The reaction raw materials and solvent were 23.54 g (0.08
mol), 3,3',4,4'-benzophenonetetracarboxylic dianhydride 6.44g (0.02 mol), 4,4'-
Diaminodiphenyl ether 20.02g (0.1mol),
174.2g N-methyl-2-pyrrolidone and water
A polymerization reaction was carried out in the same manner as in Example 1, except that the amount was 19.36 g and the reaction temperature and reaction time were 50° C. and 20 hours to obtain a reaction solution containing aromatic polyamic acid with a logarithmic viscosity of 0.49. Next, a water removal operation was carried out in the same manner as in Example 1 to obtain a polyamic acid solution composition having a water content of 1.0% by weight. The polymer concentration of this polyamic acid solution composition was 23.2% by weight, and the solution viscosity was 60 poise. The obtained polyamic acid solution composition was heated at 50°C and 60°C.
The solution viscosity after storage for one day was 85 poise. However, when stored at 50°C for 80 days, it became an insoluble gel. Comparative Example 3 The reaction raw materials and solvent were 5.88 g (0.02 mol) of 3,3',4,4'-biphenyltetracarboxylic dianhydride and 3,3',4,4'-benzophenonetetracarboxylic acid. Dianhydride 25.78g (0.08mol), 4,4'-
Diaminodiphenyl ether 16.02 g (0.08 mol), m-phenylenediamine 2.16 g (0.02 mol), N-methyl-pyrrolidone 176.2 g and water
A polymerization reaction was carried out in the same manner as in Example 1, except that the amount was 5.45 g, and the reaction temperature and reaction time were 30°C and 20 hours.
A reaction solution containing aromatic polyamic acid with a logarithmic viscosity of 0.56 was obtained. Next, water was removed in the same manner as in Example 1 to obtain a polyamic acid solution composition having a water content of 0.9% by weight. The polymer concentration of this polyamic acid solution composition was 22.8% by weight, and the solution viscosity was 61 poise. The obtained polyamic acid solution composition was heated at 50°C and 60°C.
The solution viscosity after storage for one day was 59 poise. However, when stored at 50°C for 80 days, it became an insoluble gel. Comparative Example 4 32.22 g of 3,3',4,4'-benzophenonetetracarboxylic dianhydride was used as the reaction raw material and solvent.
(0.1 mol), 20.02 g (0.1 mol) of 4,4'-diaminodiphenyl ether, 223.2 g of N-methyl-2-pyrrolidone, and 6.90 g of water. A reaction solution containing aromatic polyamic acid having a viscosity of 0.50 was obtained. Next, water was removed in the same manner as in Example 1 to obtain a polyamic acid solution composition having a water content of 0.9% by weight. The polymer concentration of this polyamic acid solution composition was 20.0% by weight, and the solution viscosity was 30 poise. The obtained polyamic acid solution composition was heated at 50°C and 60°C.
The solution viscosity after storage for one day was 29 poise. However, when stored at 50°C for 70 days, it became an insoluble gel. Comparative Example 5 The reaction raw materials and solvent were 23.54 g (0.08
3,3',4,4'-benzophenonetetracarboxylic dianhydride 6.44g (0.02mol), m-phenylenediamine 10.81g (0.1mol), N-methyl-2-pyrrolidone 151.5g A polymerization reaction was carried out in the same manner as in Example 1, except that 4.74 g of water was added to obtain a reaction solution containing aromatic polyamic acid having a logarithmic viscosity of 0.41. Next, a water removal operation was carried out in the same manner as in Example 1 to obtain a polyamic acid solution composition having a water content of 0.8% by weight. The polymer concentration of this polyamic acid solution composition was 21.9% by weight, and the solution viscosity was 32 poise. The obtained polyamic acid solution composition was heated at 50°C and 60°C.
The solution viscosity after storage for one day was 29 poise. However, when stored at 50°C for 80 days, it became an insoluble gel. Comparative Example 6 The reaction raw materials and solvent were 5.88 g (0.02 mol) of 3,3',4,4'-biphenyltetracarboxylic dianhydride and 3,3',4,4'-benzophenonetetracarboxylic acid. A polymerization reaction was carried out in the same manner as in Example 1, except that 25.78 g (0.08 mol) of dianhydride, 10.81 g (0.1 mol) of m-phenylenediamine, 153.4 g of N-methyl-2-pyrrolidone, and 4.74 g of water were used. A reaction solution containing aromatic polyamic acid with a logarithmic viscosity of 0.39 was obtained. Next, a water removal operation was carried out in the same manner as in Example 1 to obtain a polyamic acid solution composition having a water content of 0.8% by weight. The polymer concentration of this polyamic acid solution composition was 22.3% by weight, and the solution viscosity was 35 poise. The obtained polyamic acid solution composition was heated at 50°C and 60°C.
The solution viscosity after storage for one day was 33 poise. However, after being stored at 50°C for 80 days, it became an insoluble gel. Comparative Example 7 The reaction raw materials and solvent were 23.54 g (0.08
mol), 3,3',4,4'-benzophenonetetracarboxylic dianhydride 6.44g (0.02 mol), 4,4'-
Diaminodiphenylmethane 19.83g (0.1mol),
173.3g N-methyl-2-pyrrolidone and water
A polymerization reaction was carried out in the same manner as in Example 1, except that the amount was changed to 5.36 g, to obtain a reaction solution containing aromatic polyamic acid having a logarithmic viscosity of 0.45. Next, water was removed in the same manner as in Example 1 to obtain a polyamic acid solution composition having a water content of 0.9% by weight. The polymer concentration of this polyamic acid solution composition was 23.1% by weight, and the solution viscosity was 45 poise. The obtained polyamic acid solution composition was heated at 50°C and 60°C.
The solution viscosity after storage for one day was 43 poise. However, when stored at 50°C for 80 days, it became an insoluble gel state. Example 8 The reaction raw materials and solvent were 5.88 g (0.02 mol) of 3,3',4,4'-biphenyltetracarboxylic dianhydride and 3,3',4,4'-benzophenonetetracarboxylic acid. Dianhydride 25.78g (0.08mol), 4,4'-
Diaminodiphenylmethane 19.83g (0.1mol),
185.6g N-methyl-2-pyrrolidone and water
A polymerization reaction was carried out in the same manner as in Example 1, except that the amount was changed to 5.74 g, to obtain a reaction solution containing aromatic polyamic acid with a logarithmic viscosity of 0.43. Next, a water removal operation was carried out in the same manner as in Example 1 to obtain a polyamic acid solution composition having a water content of 0.8% by weight. The polymer concentration of this polyamic acid solution composition was 22.4% by weight, and the solution viscosity was 41 poise. The resulting polyamic acid solution composition was heated at 50°C and 60°C.
The solution viscosity after storage for one day was 37 poise. However, when stored at 50°C for 80 days, it became an insoluble gel. [Evaluation of aromatic polyamic acid solution compositions as varnishes for manufacturing enameled wires] Evaluation of the aromatic polyamic acid solution compositions of Examples 1 to 7 and Comparative Examples 1 to 2 as varnishes for manufacturing enameled wires was carried out by the following method. (1) Manufacture of enameled wire Enameled wire was manufactured in accordance with a conventional method using a rigid enameled wire baking furnace in which the furnace temperature was maintained at 400° C. and a wire speed of 5 m/min. The copper wire used as the material had a diameter of 1.0 mm, and the number of applications was 8 times. (2) Evaluation of enameled wire The appearance and salt water resistance of the coating on the enameled wire were evaluated. Note that salt water resistance was evaluated as follows. Salt water resistance (salt water dielectric breakdown resistance) According to JISC3003 11.1, two test pieces were made.
Cut the joints, bend the whole thing into a U-shape, immerse the twisted part for 10 cm in a 0.4% by weight sodium chloride aqueous solution kept at 30℃, and apply 200V AC to these two conductor tubes. , the time required for a 0.1A current to flow was measured.

[Table] [Evaluation of mechanical strength of polyimide films obtained from aromatic polyamic acid solution compositions] Polyimide films were produced from the polyamic acid solution compositions of Examples 1 to 7 by the following method, and their mechanical strength was evaluated. The strength was evaluated. The polyamic acid solution composition was applied onto a glass plate in the form of a thin film of uniform thickness using a doctor knife. This thin film was dried and solidified at 80°C for 30 minutes in a nitrogen atmosphere to form a film. This film was heated to 300°C over 1 hour, and then heat-treated at 300°C for 30 minutes to form a 25 μm thick polyimide film. Obtained. For the above polyimide film, tensile strength (unit: Kg/mm ² ) and elongation at break (unit: %)
was measured on a sample having a length of 100 mm and a width of 10 mm using an Autograph DSS-5000 (manufactured by Shimadzu Corporation) at a chuck distance of 50 mm and a pulling speed of 50 mm/min. The measurement results are shown in Table 2.

【table】

Claims (1)

[Scope of Claims] 1 3,3',4,4'-biphenyltetracarboxylic dianhydride and/or its derivative and 3,3',
4,4′-benzophenonetetracarboxylic dianhydride and/or its derivatives in a ratio of 30:70 to 75:25
An aromatic tetracarboxylic acid or a derivative thereof containing at a molar ratio of 80 mol% or more and an aromatic diamine in substantially equimolar amounts, obtained by polymerization. Logarithmic viscosity 0.1 to 1.5 [30℃, 0.5g/100ml (N-methyl-
2-pyrrolidone)] aromatic polyamic acid,
A polyamic acid solution composition obtained by dissolving 5 to 40% by weight in an organic polar solvent. 2 3,3',4,4'-biphenyltetracarboxylic dianhydride and/or its derivative and 3,3',
The molar ratio with 4,4′-benzophenonetetracarboxylic dianhydride and/or its derivatives is 45:55
The polyamic acid solution composition according to claim 1, characterized in that the ratio is 75:25. 3 At least 90 mol% of the aromatic tetracarboxylic acid or its derivative is 3,3',4,4'-biphenyltetracarboxylic dianhydride and 3,3',4,4'-benzophenonetetracarboxylic acid. The polyamic acid solution composition according to claim 1 or 2, characterized in that the polyamic acid solution composition comprises an acid dianhydride. 4 The aromatic tetracarboxylic acid or its derivative is substantially composed of 3,3',4,4'-biphenyltetracarboxylic dianhydride and 3,3',4,4'-benzophenonetetracarboxylic dianhydride. The polyamic acid solution composition according to claim 3, characterized in that it consists of an anhydride. 5. The polyamic acid solution composition according to any one of claims 1 to 4, wherein the aromatic diamine consists essentially of 4,4'-diaminodiphenyl ether. 6. The aromatic diamine according to any one of claims 1 to 4, characterized in that the aromatic diamine consists of an aromatic diamine mixture containing 70% by weight or more of 4,4'-diaminodiphenyl ether. Polyamic acid solution composition. 7 Aromatic polyamic acid in organic polar solvent
The polyamic acid solution composition according to claim 1, characterized in that 10 to 35% by weight is dissolved in the polyamic acid solution composition. 8. The organic polar solvent is selected from the group consisting of N-methyl-2-pyrrolidone, dimethylsulfoxide, N,N-dimethylacetamide, and N,N-dimethylformamide, or a mixture thereof. A polyamic acid solution composition according to claim 1.