JPH0198628A - Polyimide of excellent thermal dimensional stability - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a polyimide resin known as a heat-resistant resin. Specifically, the present invention relates to a novel polyimide copolymer that has both excellent thermal dimensional stability and excellent tensile properties.

(Prior Art) Polyimide is well known as a polymer having excellent heat resistance. This polymer has even better chemical resistance,
It has electrical and mechanical properties. A typical polyimide is, as is well known, a polymer obtained from 4,4'-diaminodiphenyl ether and pyromellitic dianhydride, which is produced commercially on a large scale. This polymer is used as an electrical material that requires heat resistance, such as flexible printed circuit boards. Although this polymer has excellent mechanical properties such as tensile properties, it has the disadvantage of poor thermal dimensional stability (large coefficient of linear thermal expansion on the order of 3xlO-s''c-1). An example of a problem caused by poor dimensional stability is the warping or curling of flexible printed circuit boards.Flexible printed circuit boards are made by laminating polyimide film and metal.
Since the coefficient of linear thermal expansion of metal is smaller than that of polyimide film, warping and curling occur due to temperature changes during processing and use of flexible printed circuit boards.

Another example of a problem caused by poor thermal dimensional stability is warping or curling of magnetic recording materials. Modern high-density magnetic recording materials may be manufactured by depositing metal onto a base film. Heat resistant polymers such as polyimide are preferred as the base film since metal deposition is done at high temperatures. However, since the linear thermal expansion coefficient of polyimide film is larger than that of metal, warping and curling occur.

Since polyimide has heat resistance, it is often subject to large temperature changes. Therefore, polyimides with excellent thermal dimensional stability are desired. In particular, such demands are increasing with the recent development of electronics.

An example of a polyimide film with excellent thermal dimensional stability is disclosed in JP-A-61-158025.61-181828.61-2.
No. 41325°61-264028. The polyimides disclosed in JP-A-61-158025 and JP-A-61-264028 use biphenyltetracarboxylic dianhydride as the tetracarboxylic dianhydride and pyromellitic dianhydride as necessary, and paraphenylene diamine as the diamine. This is a polyimide obtained by polycondensation using 4,4'-diaminophenyl ether if necessary. The polyimide disclosed in JP-A-61-181828 is a polyimide obtained by polycondensation with an aromatic tetracarboxylic anhydride using a specific heterocyclic diamine such as 2,5-diaminopyridine as the diamine. The polyimide disclosed in JP-A-61-241325 uses 9,9-bis(4-aminophenyl)anthracene and paraphenylenediamine as diamines,
This is a polyimide obtained by polycondensation using biphenyltetracarboxylic dianhydride as the aromatic tetracarboxylic dianhydride. All of these polyimides use special and expensive compounds such as biphenyltetracarboxylic dianhydride, heterocyclic diamine, or 9,9-bis(4-aminophenyl)anthracene as raw materials.

(Problem to be Solved by the Invention) The object of the present invention is to obtain a novel polyimide having excellent thermal dimensional stability and excellent mechanical properties.

Another object of the present invention is to obtain a polyimide that does not warp or curl when laminated with metal and has excellent mechanical properties.

Another object of the invention is to obtain a polyimide with excellent thermal dimensional stability obtained from common inexpensive raw materials.

(Means for Solving the Problems) The above object is the general formula (I) group or CH:I CI+3 group, and R8 and R2 are never the same group. Ro is a tetravalent aromatic group, and m is a positive integer. ] This is achieved by a polyimide copolymer having a repeating unit represented by:

The polyimide copolymer of the present invention has excellent heat resistance, mechanical properties such as tensile properties, and thermal dimensional stability. Furthermore, it has excellent alkali hydrolysis resistance and excellent dimensional stability when absorbing moisture.

The copolymer of the present invention has a linear thermal expansion coefficient of 2.5 x 10-"C-' or less in the temperature range from 50°C to 300°C and a tensile property of elongation of 30% or more. Furthermore, it is also possible to have a value of 2.0X10-'''C'-1C'-1 or less and a value of 40% or more, particularly a value of 1.5X10-'''C'-1C'-1 or more. Furthermore, it has excellent alkali hydrolysis resistance and does not dissolve during etching treatment, etc., so it can be suitably used for printed circuit boards. For example, in a 5% aqueous sodium hydroxide solution, 50
The heavy BltN fraction after 5 minutes at °C was less than 4.0%, which is smaller than that of conventional polyimide resins.

Furthermore, the copolymer of the present invention has excellent dimensional stability upon moisture absorption. (The humidity coefficient of linear expansion is small.) Therefore, dimensional changes are small even under high humidity.

Although the reason why this polyimide copolymer has the above-mentioned characteristics is not clear, the polyimide copolymer of the present invention has a block unit [where R0, R, , m are the same as above]. ] is one repeating unit [where Re and Rz are the same as above. ] Since it has a regularly arranged structure in which the repeating units are connected by There is. Therefore, it is assumed that thermal dimensional stability and elongation are simultaneously significantly improved.

The polyimide of the present invention is a random copolymer polyimide using 3,3'-dimethylbenzidine and 4,4'-diaminodiphenyl ether as a diamine, or a 3,3'
- Both thermal dimensional stability and mechanical properties are superior compared to a mixture of a polyimide homopolymer using dimethylbenzidine as the diamine and a polyimide homopolymer using 4,4'-diaminodiphenyl ether as the diamine. There is.

In the polymer of the present invention - in the hole (1) and (III)
t cannot have the same basis.

Ro is a tetravalent aromatic group in which carbon atoms forming an aromatic ring participate in bonding, and representative examples include the following. Among these, preferred.

The repeating unit represented by general formula (I) may contain other repeating units as long as they are contained in the polymer chain to an extent that achieves the effects of the present invention.

Preferred examples of other repeating units do not have the same general formula. Ro, m are the same as above, ] can be mentioned.

Usually, a polymer in which the repeating unit represented by the general formula (I) is the main component, that is, an average of 50 times % in one polymer molecule.
or more, preferably 80% or more, more preferably 90%
Polymers in which the repeating units are as follows are preferred.

In addition, when repeating units represented by -Momona (1) and -Momona (If) are included, the total amount of these repeating units is 50% by weight or more on average in one polymer molecule, Preferably, the polymer has a content of 80% or more, more preferably 90% or more.

The number of repetitions m in block units is 1 to 9, preferably 1 to 7, and more preferably 1 to 4.

This is because if the repetition number m exceeds 9, the copolymerization ratio will be biased and the effect of copolymerization will be reduced. Further, although units having different values of m may exist in one molecule of the polymer, it is preferable that the value of m is constant. The molecular weight of this copolymer is not particularly restricted, but in order to maintain the strength of the polyimide resin produced, the number average molecular weight must be 50,000 or more, further 80,000 or more, especially 100,000 or more, and is preferably 120,000 or more.

It is often difficult to directly measure the molecular weight of polyimide copolymers. In such cases, inferential measurements are made using indirect methods. For example, when a polyimide copolymer is synthesized from polyamic acid, the molecular weight of the polyimide is a value corresponding to the molecular weight of the polyamic acid.

The polyimide copolymer of the present invention can be obtained by various methods, including -Momona (III) or -Momona (III)
It is desirable to obtain it from a polyamic acid copolymer having repeating units represented by and (rV).

- Monna (III) [In the formula, R,, R,, R2, and m are the same as above. ] General pattern hole IV) [In the formula, Re r R+ + R3+ m is the same as above. ] Next, an example of a method for producing this polyimide copolymer or polyamic acid copolymer will be explained.

- Monna [In the formula, R0 is the same as above. ] Organic tetracarboxylic dianhydride (A) represented by the general formula % Formula % in a minor molar amount, preferably 50 to 90 mol % [In the formula, R8 is the same as above. ] The organic diamine compound (B) represented by is reacted in an organic polar solvent to obtain a prepolymer having acid anhydride groups at both ends, and then - Monana H, N-R, - In the NH2C formula, R2 is the same as above. ] If necessary, the general formula % formula % [In the formula, R3 is the same as above. ] The organic diamine compound (C) represented by the total organic diamine! i ((B) + (C)) is added and reacted with the organic tetracarboxylic dianhydride (A) in substantially equimolar amounts, and -Momone (III) or -Momone (III) and ( IV
) A polyamic acid copolymer having a repeating unit represented by: A polyimide copolymer can be obtained by thermally or chemically dehydrating and ring-closing this copolymer. For example, pyromellitic dianhydride is suspended and dissolved in an organic polar solvent, and 50 to 90
Mol%, preferably 50 to 87.5 mol%, more preferably 50 to 80 mol% of 4,4'-diaminodiphenyl ether is added and reacted to obtain a prepolymer having acid anhydride groups at both ends. However, in the reaction for obtaining this prepolymer, the order of addition of pyromellitic dianhydride and 4,4'-diaminodiphenyl ether may be reversed. Next, 3,3'-dimethylbenzidine is added thereto so that the amount of pyromellitic dianhydride and the total amount of diamines are substantially equimolar, and after stirring, a polyamic acid copolymer solution is obtained. The concentration of the polyamic acid copolymer in the organic polar solvent is 5~
35% by weight, especially 10 to 25% by weight is desirable. still,
In order for the above polymerization reaction to proceed stably, in a substantially anhydrous system at a temperature of 60°C or lower, preferably 30°C or lower, more preferably 10°C or lower, within 10 hours, preferably 5 It is desirable to complete the reaction within hours, more preferably within 3 hours. This is because, as mentioned above, during the reaction, the reaction passes through the prepolymer at the end of the acid anhydride group, so this acid anhydride group reacts with moisture in the system and becomes a dicarboxylic acid, inhibiting the growth of the polymer chain length. This is because there is.

Next, in order to obtain a polyimide copolymer from the solution of the polyamic acid copolymer which is the precursor, a method of thermal dehydration and ring closure or a method of chemical dehydration and ring closure may be used. Next, an example will be given and explained.

In the method of thermally dehydrating and ring-closing (imidization), a solution of the above-mentioned polyamic acid copolymer is cast or coated onto a support such as a support plate, drum, or endless belt to form a film, which is self-supporting after drying. obtain a film of Preferably, drying is carried out at a temperature of 150° C. or less for about 5 to 90 minutes. Next, this is heated to dry imide, and after cooling, it is removed to obtain a polyimide film made of the polyimide copolymer of the present invention. The temperature during heating is preferably in the range of 200 to 500°C, more preferably 300 to 500°C, particularly 400 to 500°C.
°C is preferred. There are no particular limitations on the heating rate during heating, but it is preferable to heat gradually so that the maximum temperature is the above temperature. The heating time varies depending on the film thickness and maximum temperature, but is generally preferably in the range of 10 seconds to 5 minutes after reaching the maximum temperature.When heating a self-supporting film, the film is held on a support. It can be left as is, or it can be peeled off from the support, but it can be peeled off from the support,
It is preferable to fix the ends and heat in this state because a copolymer with a small coefficient of linear thermal expansion can be obtained.

In the method of chemically dehydrating and ring-closing (imidization), a stoichiometric or higher dehydrating agent and a catalytic amount of tertiary amine are added to the solution of the polyamic acid copolymer, and the same method as thermal dehydration is used. A polyimide film is obtained. When heating a self-supporting membrane, the membrane can be held on the support or peeled off from the support, but it is better to peel it off the support and fix the ends in that state. Heating is preferred because a copolymer with a small coefficient of linear thermal expansion can be obtained. When comparing the thermal imidization method and the chemical imidization method, the mechanical strength of the polyimide is greater in the chemical method.
Moreover, the coefficient of linear thermal expansion becomes small.

Next, to explain the raw materials used in the present invention, when obtaining the polyamic acid copolymer which is the precursor of the polyimide copolymer of the present invention, pyromellitic dianhydride is used as the aromatic tetracarboxylic dianhydride. It is most preferable to use it alone to obtain the effects of the present invention, but for example, 3.3
', 4,4'-biphenyltetracarboxylic dianhydride, 3.3', 4,4'-benzophenonetetracarboxylic dianhydride, naphthalene-L2,5,6-tetracarboxylic dianhydride, and other acids. It is also possible to use dianhydrides,
A mixture of these may also be used.

It is most preferable to use two types of diamines, 4,4'-diaminodiphenyl ether and 3,3'-dimethylbenzidine, as the aromatic diamine component in order to obtain the effects of the present invention. is a divalent organic group] Other diamine compounds represented by, for example, 4,4'-bis(4-aminophenoxy)biphenyl, 4,4'-diaminodiphenylsulfone, 3,3'-diaminodiphenylsulfone, Bis(4-(4-aminophenoxy)
phenyl]sulfone, bis[4-(3-aminophenoxy)phenyl]sulfone, bis(4-(2-aminophenoxy)phenyl)sulfone, 1,4-bis(4-aminophenoxy)benzene, 1,3-bis (4-aminophenoxy)benzene, 1,3-bis(3-aminophenoxy)benzene, l,4-bis(4-aminophenyl)
Benzene, bis(4-(4-aminophenoxy)phenyl ether, 4,4'-diaminodiphenylmethane,
Bis(3-ethyl-4-aminophenyl)methane, bis(3-methyl-4-aminophenyl)methane, bis(3
-chloro-4-aminophenyl)methane, 3,3'-dimethoxy-4,4' -diaminodiphenyl, 3,3'
-dichloro-4,4'-diaminobiphenyl, 2.2
', 5,5'-tetrachloro-4,4'-diaminobiphenyl, 3,3'-dicarboxy-4,4'-diaminobiphenyl, 3,3'-dihydroxy-4,4'
-Diaminotoluene/L/, 4.4'-diaminodiphenyl sulfide, 3.3'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4
．． 4'-diaminobiphenyl, 4,4'-diaminoctafluorobiphenyl, 2,4-diaminotoluene,
metaphenylenediamine, 2,2-bis(4-(4-aminophenoxy)phenyl)propane, 2,2-bis(
4-(4-aminophenoxy)phenyl]hexafluoropropane, 2,2-bis(4-aminophenyl)propane, 2,2-bis(4-aminophenyl)hexafluoropropane, 2,2-bis( 3-hydroxy-4-aminophenyl)propane, 2,2-bis(3-hydroxy-4-aminophenyl)hexafluoropropane, 9
．． 9-bis(4-aminophenyl)-10-hydroxy-anthracene, orthotolidine sulfone can be used. Also, 3.3'.

4.4'-biphenyltetraamine, 3.3', 4.
It is also possible to use some polyvalent amine compounds such as 4'-tetraaminodiphenyl ether.

When using three or more of these diamine compounds, 4,
A system using 4'-diaminodiphenyl ether, 3,3'-dimethylbenzidine and para-phenylenediamine is suitable for exerting the effects of the present invention.

Examples of organic solvents used in the production reaction of the polyamic acid copolymer include sulfoxide-based solvents such as dimethyl sulfoxide and diethyl sulfoxide, formamide-based solvents such as N,N-dimethylformamide, and chloroformamide. Acetamide solvents such as N-dimethylacetamide and N,N-diethylacetamide; pyrrolidone solvents such as N-methyl-2-pyrrolidone and N-vinyl-2-pyrrolidone; phenol;

Examples include phenolic solvents such as m- or p-cresol, xylenol, halogenated phenol, and catechol, hexamethylphosphoramide, and γ-butyrolactone, and it is preferable to use these alone or as a mixture. Furthermore, it is also possible to use aromatic hydrocarbons such as xylene and toluene.

Chemical dehydration ring closure (imidization) of polyamic acid copolymer
Examples of dehydrating agents used in this process include aliphatic acid anhydrides such as acetic anhydride, aromatic acid anhydrides, and the like. Examples of the catalyst include aliphatic tertiary amines such as triethylamine, aromatic tertiary amines such as dimethylaniline, and heterocyclic tertiary amines such as pyridine, picoline, and isoquinoline.

The polyimide copolymer of the present invention has excellent thermal dimensional stability,
It has dimensional stability when absorbing moisture, mechanical properties, and appropriate tensile modulus, and is used in film form for magnetic recording materials such as flexible printed circuit boards, magnetic tapes for general magnetic recording and perpendicular magnetic recording, and magnetic disks. Base, IC, LSI
It is extremely useful as a passivation film for semiconductor devices such as solar cells.

Example 1 10.31 g of 4,4'-diaminodiphenyl ether (hereinafter referred to as ODA) was collected in a 500 d four-loop flask, and 145. OOg of N,N-dimethylacetamide was added and dissolved. On the other hand, 16.90 g of pyromellitic dianhydride (hereinafter referred to as PMDA) was collected in a 50-Eggplant flask and added in solid form to the ODA solution. Furthermore, PMD remaining on the wall of this 50m2 eggplant flask
A to 10. OOg of N,N-dimethylacetamide was poured into the reaction system (four-bottle flask), and the mixture was further stirred for 1 hour to obtain an acid anhydride group amic acid prepolymer. on the other hand,
Collect 5.48 g of 3.3'-dimethylbenzidine (hereinafter referred to as DMB) in a 50IIrl Erlenmeyer flask, and
24 g of N,N-dimethylacetamide was added and dissolved. Add this solution to the reaction system (four-loop flask),
A copolymerized polyamic acid solution was obtained. In the above reaction preparations, the reaction temperature was 5 to 10°C, and the handling of PMDA and DMB and the inside of the reaction system were carried out under a stream of dry nitrogen.

Next, these polyamic acid solutions were cast onto a glass plate, and after drying at about 100°C for about 60 minutes, the polyamic acid coating was peeled off from the glass plate, and the coating was fixed on a support frame. Heated at ``C for about 30 minutes, at about 200℃ for about 60 minutes, and at about 360℃ for about 60 minutes, and after dehydration and ring closure drying,
A polyimide film with a thickness of 0-25 microns was obtained.

This film exhibited the linear expansion coefficient, tensile elongation, alkali resistance weight loss rate, and humidity expansion coefficient shown in Table 1. The coefficient of linear expansion in Table 1 is the value at 200°C, and the alkali weight loss rate is the value at 50°C in a 5% NaOH aqueous solution.
The weight loss rate after being immersed for minutes is shown.

Example 2 8.07 g ODA, 17.58 g SPMDA,
A copolymerized polyimide film was obtained according to the method of Example 1, except that 8.54 g of tlMB was used. This film is shown in Table 1
It showed the properties shown in .

Example 3 88.54 g of 0M was collected in a 500 ml four-loop flask, and 110. OOg of N,N-dimethylacetamide was added and dissolved. On the other hand, 17.58 g of PMOA was collected in a 50 m eggplant flask and added in solid form to the DMB solution. Furthermore, this 50ad! The PMDA remaining on the wall of the eggplant flask was poured into the reaction system (four-bottle flask) with 10.00 g of N,N-dimethylacetamide, and the mixture was stirred for an additional hour. Obtained. Meanwhile, 0DA in the 100d Erlenmeyer flask
8.07g was collected, and 50.00g of N,N-dimethylacetamide was added and dissolved.

This solution was added to a reaction system (four-walled flask) to obtain a polyamic acid copolymer solution. In the above reaction operation, the reaction temperature was 5 to 10°C, and the handling of PMOA and ODA and the inside of the reaction system were carried out under a dry nitrogen stream.Next, according to the method of Example 1, a copolymerized polyimide membrane was formed. Obtained.

This film exhibited the properties shown in Table 1.

Example 4 12.02 g ODA, 16.36 g PMOA
A copolyimide film was obtained according to the method of Example 1, except that 3.18 g of DMB was used. This film exhibited the properties shown in Table 1.

Example 5 11.90 g of DMB, 18.33 g of PMOA
A copolymerized polyimide film was obtained according to the method of Example 3, except that 5.61 g of ODA was used. , this film exhibited the properties shown in Table 1.

Example 6 To the polyamic acid solution obtained by the method of Example 2, 33.88' g of acetic anhydride and 5.32 g of pyridine were added.

Next, this polyimide acid solution composition was cast-coated onto a glass plate, and after drying at about 100°C for about 10 minutes, the semi-cured coating film was peeled off from the glass to obtain a polyimide film of 15 to 25 microns. This film exhibited the properties shown in Table 1.

Example 7 0DA25.13g in 500 rrdl fourth flask
was collected and dissolved by adding 336.0 g of N,N-dimethylformamide. Add PMDA to the other 50d eggplant flask.
36,4' 9 g was collected and added in solid form to the ODA solution. Furthermore, the PMDA remaining on the wall of this 50 d eggplant flask was poured into the reaction system (four-round flask) with 10 g of N,N-dimethylformamide, and further 3
After stirring for 0 minutes, an acid anhydride group-terminated amic acid prepolymer was obtained.

On the other hand, 50m! 2.26 g of p-PDA in an Erlenmeyer flask
An additional 4.44 g of DMB was collected, 23.3 g of N,
N-dimethylformamide was added and dissolved. This solution was added to a reaction system (four-bottle flask) to obtain a copolymerized polyamic acid solution. In the above counter-operation, the reaction temperature is 5~
At 10 °C, PMDA, p-PDA, ODA, D
Handling of MB and reaction operations were performed under a stream of dry nitrogen. A polyimide film having a thickness of 25 μm was produced from this by a known method.

This film exhibited the properties shown in Table 1.

Comparative Example 1 21.54 g of ODA was collected in a 5001e four-loop flask, and 245 g of ODA was collected. OOg of N,N-dimethylacetamide was added and dissolved. On the other hand, 23.46 g of PMDA was collected in a 100 ml eggplant flask and added in solid form to the ODA solution. Furthermore, PMDA remaining attached to the wall of this 100In1 eggplant flask was removed by 10. N of OOg
, N-dimethylacetamide into the reaction system (four-neck flask). Continue stirring for another hour,
A weight % polyamic acid solution was obtained. Reaction temperature is 5~10''
I kept it at C. However, in the above operations, PMOA was handled and the inside of the reaction system was placed under a stream of dry nitrogen.

Next, according to the method of Example 1, a polyimide film was obtained from this polyamic acid solution. This film exhibited the properties shown in Table 1.

Comparative Example 2 87.58 g of 0M and 15 g of OD were collected in a 500 d four-bottle flask, 161.5 g of N,N-dimethylacetamide was added and dissolved, and 15.58 g of PMDA was added according to the method of Comparative Example 1. The reaction was carried out to obtain a 15 weight polyamic acid solution. However, the PMDA remaining attached to the final wall was poured into the i o, o o g N,N-dimethylacetamide reaction system (four-loop flask),
A copolyamic acid was obtained by random copolymerization. Next, according to the method of Example 1, a polyimide film was obtained from this polyamic acid solution. This film exhibited the properties shown in Table 1.

Comparative Example 3 83.53 g of 0M and 9.98 g of OD were collected in a 500 d four-loop flask, and 148.70 g of N,N-dimethylacetamide was added and dissolved, and 14.49 g of PMDA was added according to the method of Comparative Example 1. were reacted to obtain a polyamic acid solution of 15 weight by random copolymerization. however,
PMDA attached to the final wall is 10.00 g of N, N
- Dimethylacetamide was poured into the reaction system (four-necked flask). Next, according to the method of Example 1, a polyimide film was obtained from this polyamic acid solution. This film is shown in Table 1
It showed the properties shown in .

Comparative Example 4 20.70 g of 0DA was collected in a 500M 1-four-loop flask, and 245.00 g of N,N-dimethylacetamide was added and dissolved. On the other hand, add PMD to a 100d eggplant flask.
22.54 g of A was collected and added in solid form to the ODA solution. Continue stirring for another 1 hour, and 15% by weight
A polyamic acid solution N) was obtained.

On the other hand, 0MB20.41 in 500I11 four-roof flask
224.50 g of N,N-dimethylacetamide was added and dissolved, followed by the same method as above.
97 g PMOA was reacted to obtain a 1.5% by weight polyamic acid solution (If). However, PMDA remaining attached to the final wall was poured into the reaction system (four-bottle flask) with 1 O, OOg of N,N-dimethylacedeamide. In either case, the reaction temperature was maintained at 5 to 10°C, and in the above operations, PMOA was handled and the reaction system was placed under a stream of dry nitrogen.

Separately, 112.35 g of the polyamic acid solution (1) obtained by the above method was collected in a 500 d four-loop flask, and 115.58 g of the polyamic acid solution (II) was further mixed therein for 5 to 50 minutes under a stream of dry nitrogen. Stirred at 10°C for about 10 minutes.

Next, according to the method of Example 1, a polyimide film was obtained from this polyamic acid solution. This film exhibited the properties shown in Table 1.

(Effects of the invention) The copolyamide of the present invention has excellent thermal dimensional stability,
It has dimensional stability and mechanical properties when absorbing moisture.

Claims (1)

[Claims] 1. General formula ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (I) [In the formula, R_1 and R_2 are ▲ Numerical formulas, chemical formulas, tables, etc. ▼ groups or ▲ Numerical formulas, chemical formulas, tables, etc. There is a ▼ group, and R_1 and R_2 cannot be the same group. R_0 is a tetravalent aromatic group, m is a positive integer. ] A polyimide copolymer having a repeating unit represented by: 2. The polyimide copolymer according to claim 1, wherein R_0 is ▲a numerical formula, a chemical formula, a table, etc.▼. 3. Claim 1 states that R_1 is ▲There are mathematical formulas, chemical formulas, tables, etc.▼, R_2 is ▲There are mathematical formulas, chemical formulas, tables, etc.▼ and R_0 is ▲There are mathematical formulas, chemical formulas, tables, etc.▼ polyimide copolymer. 4. Claim 1 states that R_1 is ▲There are mathematical formulas, chemical formulas, tables, etc.▼, R_2 is ▲There are mathematical formulas, chemical formulas, tables, etc.▼ and R_0 is ▲There are mathematical formulas, chemical formulas, tables, etc.▼ polyimide copolymer. 5. The polyimide copolymer according to claim 1, which contains repeating units represented by formula (I) in an average amount of 50% by weight or more in one polymer molecule. 6. General formula ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (II) [In the formula, R_1 and R_3 are ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ groups or ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ groups, and R_1 and R_3 are never the same base. R_0,
m is the same as above. ] The polyimide copolymer according to claim 1, further comprising a repeating unit represented by: 7. The polyimide copolymer according to claim 1, wherein m is an integer of 1 to 9. 8. Claim 1 whose number average molecular weight is 50,000 or more when converted to the molecular weight of the corresponding polyamic acid copolymer
The polyimide copolymer described in . 9. General formula ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (III) [In the formula, R_1 and R_2 are ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ groups or ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ groups, and R
_1 and R_2 cannot be the same base. R_0 is a tetravalent aromatic group m is a positive integer. ] A polyamic acid copolymer having a repeating unit represented by: 10. The polyimide copolymer according to claim 9, wherein R_0 is ▲a numerical formula, a chemical formula, a table, etc.▼. 11. Claim 9 states that R_1 is ▲There are mathematical formulas, chemical formulas, tables, etc.▼, R_2 is ▲There are mathematical formulas, chemical formulas, tables, etc.▼ and R_0 is ▲There are mathematical formulas, chemical formulas, tables, etc.▼ polyamic acid copolymer. 12. Claim 9 states that R_1 is ▲There are mathematical formulas, chemical formulas, tables, etc.▼, R_2 is ▲There are mathematical formulas, chemical formulas, tables, etc.▼ and R_0 is ▲There are mathematical formulas, chemical formulas, tables, etc.▼ polyamic acid copolymer. 13. General formula ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (IV) [In the formula, R_1 and R_3 are ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ groups or ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ groups, and R_1 and R_3 are never the same base. R_0,
m is the same as above. ] The polyamic acid copolymer according to claim 9, further comprising a repeating unit represented by the following. 14. The polyamic acid copolymer according to claim 9, wherein m is an integer of 1 to 9. 15. The polyamic acid copolymer according to claim 9, which has a number average molecular weight of 50,000 or more.