DE69312808T2 - Polyimide and its manufacturing process - Google Patents

Description

The present invention relates to a novel polyimide, a production process for the polyimide, a novel aromatic diamino compound used for producing the polyimide, and a production process for the aromatic diamino compound. In particular, the invention relates to a novel thermoplastic and amorphous polyimide which is readily soluble in organic solvents, and a production process for the polyimide.

The novel aromatic diamino compound of the invention is suitable for producing the polyimide of the invention and can also be used as a starting material for other polyimides, polyamides, polyamideimides, bismaleimides and epoxy resins and as a hardener for other maleimide compounds and epoxy compounds.

Recently, heat-resistant resin materials for use in a composite have been required to have good thermal and mechanical properties, as well as flexibility and other properties such as processability.

It turned out that polyimide resins meet these requirements.

Typically, polyimides have excellent mechanical properties, chemical resistance, flame retardancy and electrical properties in addition to their excellent heat resistance. Therefore, polyimides have been used in numerous fields, e.g. as processing and composite materials and for electrical and electronic devices.

Although polyimide resins have high performance, their processability is poor. A typical known polyimide is, for example, an aromatic polyimide formed from 4,4'-diaminodiphenyl ether and pyromellitic dianhydride and having repeating structural units of the formula (A):

(Brand products: Kapton and Vespel, manufactured by E.I. Dupont de Nemours & Co.) The polyimide is insoluble and infusible and must be molded by special processes such as sintering of powder. Molded parts with complex shapes are difficult to obtain by this process, and sintered products must be finished by cutting or other processes to obtain satisfactory articles. Thus, the polyimide has a major disadvantage of high processing costs and cannot be used for polyimide varnishes. Therefore, extensive research and development activities have been carried out on soluble and fusible (thermoplastic) polyimides to provide processable polyimides.

EP-A-0.047.501 discloses polyimides obtained from bis(aminobenzoyl)benzene compounds and said to have good processability.

It is expected that soluble polyimides will be used in the future for heat-resistant paints, coatings and sealants. Solubilization methods are summarized, for example, in "Polyimide Resin" published by the Technical Information Association (1991). The methods include increasing molecular chain flexibility by incorporating a flexible bond or by copolymerization and increasing interactions with solvents by incorporating an alkyl group. However, most soluble polyimides are soluble only in high boiling point solvents such as N-methyl-2-pyrrolidone, N,N-dimethylacetamide and cresol (see, for example, JP-A-61-130342). The soluble polyimides also suffer from problems in that they contain sulfonyl groups which have high moisture absorption. Some recent Japanese patents disclose polyimides which are soluble in low boiling point solvents such as acetone, toluene and dichloromethane. Such However, polyimides have the disadvantage that alkyl groups with poor heat resistance are present in the molecular chain (see, for example, JP-A-1-263116, 1- 263117 and 2-160832).

Various soluble (thermoplastic) polyimides have also been developed. For example, improving the diamine component used as a starting material should help to solve the above problem.

It is known that the glass transition temperature and melt flowability of polyimides can be controlled by changing a bonding group in the monomer units or by incorporating a folded structure into the molecule. For example, NASA's polyimide LARC TPI is formed from 3,3'-diaminobenzophenone and benzophenonetetracarboxylic dianhydride and has a basic skeleton of the formula (B) shown below. The polyimide was further improved and a thermoplastic polyimide was developed by reacting 1,3-bis(3-aminobenzoyl)benzene with various tetracarboxylic dianhydrides (JP-A-03-223930).

Such polyimides have excellent heat resistance and adhesive properties. However, the melt flow properties are still inadequate and the polyimides are mainly used in the form of polyamic acid varnish. Such an application as a varnish is associated with problems in dealing with the moisture formed in the heat in the last step of the ring closure of the polyamic acid to form the polyimide and leads to the problem of the formation of voids in the adhesive layer.

As a result, the desired properties are unfortunately difficult to achieve and the application as an adhesive becomes complicated.

The applicants have determined the molecular weight of the polymer having the basic skeleton of formula (B):

controlled by capping the reactive end of the polymer chain and obtained polyimides that can be injection molded and extruded (see JP-A-2-018419).

However, the polyimide powder obtained in this way has a melting point of about 340ºC and must be made more amorphous in order to be able to use the powder for processing or bonding.

In addition, the polyimide of the above formula (B) can be used for adhesives having excellent heat resistance and is currently mainly used for bonding metals, prepregs, ceramics and FPC-based polyimide films, and it is expected that these applications will develop into a wide range of adhesives by taking advantage of their excellent thermoplasticity.

Polyimides have been commonly used as adhesives by the following processes:

1) A polyamic acid precursor varnish is applied to an adhesion surface and hot pressed to achieve adhesion by solvent removal and imidization.

2) A polyimide film is inserted between adhesive surfaces and hot pressed to achieve adhesion.

3) Polyimide powder is suspended in a volatile solvent, then applied to the adhesion surface, the solvent is removed by evaporation and hot pressed to achieve adhesion.

Method 3) is particularly advantageous due to its simple procedure and is widely used. It is desirable to develop a polyimide for this purpose.

Of course, adhesion can only be achieved in the process if the melting point of the polyimide powder is exceeded.

In many research projects, polyimide powder was suspended in a solvent, a prepreg was produced by impregnating the suspension into a carbon fiber fabric, a composite was produced from the prepreg and used as a structured material. In these processes, as in process 3 above, a processing temperature above the melting point of the polyimide is required.

Therefore, the development of a polyimide with good solubility and meltability in terms of processing and bonding temperature is highly desirable.

The provision of polyimides with better solubility in organic solvents or lower melting point - by converting the structure of the polyimide powders from crystalline to amorphous - as a substitute for polyimide of formula (B) which has various excellent properties while being insoluble in almost all organic solvents, contributes greatly to improving the processability and adhesiveness of polyimides, expanding their uses, and improving and increasing the efficiency of application processes.

Embodiments of the invention provide a thermoplastic and amorphous polyimide which, in addition to its essentially excellent heat resistance, has good solubility in organic solvents and good processability. In particular, Embodiments, an amorphous polyimide powder which substantially has the excellent heat resistance of the polyimide of the above formula (B) and in addition can be processed at a lower temperature than usual, that is, at a temperature below the melting point of 340 °C of the polyimide of the formula (B).

In preferred embodiments, the invention provides a heat-resistant adhesive and an adhesive method, wherein the polyimide of formula (B) has excellent heat resistance and the adhesion can be effected at lower temperatures than usual, i.e., at a temperature below the melting point of 340°C of the polyimide of formula (B).

In preferred embodiments, the invention provides a polyimide with good solubility in low boiling point organic solvents.

In preferred embodiments, the invention provides a novel aromatic diamino compound that provides processability and flexibility of the resulting polyimide and is useful as a starting material for a polyimide for adhesives.

The applicants have found that polyimides of aromatic diamines having a specific structure as a monomer component are thermoplastic and amorphous polyimides which can have good solubility and excellent processability without impairing the essential properties of polyimides. This constitutes the basis of the present invention.

The applicants further discovered a new aromatic diamino compound suitable as a monomer for polyimides having these properties and were able to prepare this compound, thereby completing the present invention.

One aspect of the invention therefore relates to:

1) A polyimide comprising a required structural unit consisting of one or more repeating structural units of the formula (I):

where m and n are each an integer of 0 or 1 and R

wherein R₁, R₂, R₃ and R₄ are each a hydrogen atom, a halogen atom, alkyl having 1 to 8 carbon atoms, aryl, alkenyl, aralkyl or alkoxy having 1 to 5 carbon atoms; R₅, R₆ and R₇ are each a hydrogen atom, alkyl having 1 to 8 carbon atoms, aryl, alkenyl, aralkyl or ω-alkyloxyoligo(alkyleneoxy)alkyl having 1 to 10 carbon atoms and 1 to 3 oxygen atoms; and Ar is a tetravalent radical having 2 to 27 carbon atoms selected from the group consisting of aliphatic, alicyclic, monoaromatic, condensed polyaromatic and non-condensed aromatic radicals which are linked to one another via a direct bond or via a bridging element.

2) A polyimide comprising a required structural unit consisting of one or more repeating structural units of the formula (I):

wherein m, n, R and A are the same as above, wherein the polyimide has at its polymer chain end an aromatic ring which is unsubstituted or substituted with a radical which does not react with amines and/or dicarboxylic anhydrides.

3) A polyimide according to 1) or 2), wherein the polyimide having repeating structural units of the formula (1) is derived from a precursor polyamic acid having an inherent viscosity of 0.01 to 3.0 dl/g in a dimethylacetamide solution having a concentration of 0.5 g/dl at 35°C.

4) A polyimide according to 1) or 2), wherein the polyimide having repeating structural units of the formula (1) has an inherent viscosity of 0.01 to 3.0 dl/g in a solvent mixture of 9 parts by weight of p-chlorophenol and 1 part by weight of phenol in a concentration of 0.5 g/dl at 35°C.

5) A polyimide comprising a required structural unit consisting of one or more repeating structural units of the formula (2): wherein m and n are each an integer of 0 or 1, R�8 is a hydrogen atom, a halogen atom, alkyl having 1 to 4 carbon atoms, alkoxy or phenyl, and Ar is a tetravalent radical having 2 to 27 carbon atoms selected from the group consisting of aliphatic, alicyclic, monoaromatic, condensed polyaromatic and non-condensed aromatic radicals which are linked to one another via a direct bond or via a bridging element.

6) A polyimide comprising a required structural unit consisting of one or more structural units of the formula (2):

wherein m, n, R₈ and Ar are the same as above and which has at its polymer chain end an aromatic ring which is unsubstituted or substituted with a radical which does not react with amines and/or dicarboxylic anhydrides.

7) A polyimide comprising a required structural unit consisting of one or more repeating structural units selected from the group consisting of 1 units of the formula (3);

where R&sub9;

and Ar is a tetravalent radical having 2 to 27 carbon atoms, selected from the group consisting of aliphatic, alicyclic, monoaromatic, condensed polyaromatic and non-condensed aromatic radicals which are linked to one another via a direct bond or via a bridging element,

2 units of formula (4);

wherein R�9 and Ar are the same as above, and

3 units of formula (5):

wherein R�9 and Ar are the same as above, or this polyimide having an aromatic ring at the polymer chain end which is unsubstituted or substituted with a radical which does not react with amines and/or dicarboxylic anhydrides.

8) A polyimide copolymer comprising a required structural unit consisting of 1 to 99 mol% of repeating structural units of the formula (1):

wherein m, n, R and Ar are the same as above, and 99 to 1 mol% of repeating structural units of the formula (6):

wherein n is an integer from 0 to 6, Q is a direct bond, -O-, -S-, -CO-, -SO₂, -CH₂-, -C(CH₃)₂- or -C(CF₃)₂- and can be the same or different when aromatic rings are linked to one another via two or more linking radicals Q, and wherein Ar' is a tetravalent radical having 2 to 27 carbon atoms, selected from the group consisting of aliphatic, alicyclic, monoaromatic, condensed polyaromatic and non-condensed aromatic radicals, which are linked to one another via a direct bond or via a bridging element, or this polyimide copolymer having an aromatic ring at its polymer chain end which is unsubstituted or substituted with a radical which does not react with amines and/or dicarboxylic anhydrides.

9) A polyimide copolymer comprising a required structural unit consisting of 1 to 99 mol% of repeating structural units of the formula (2):

wherein m and n are each an integer of 0 or 1, R₈ is a hydrogen atom, a halogen atom, alkyl having 1 to 4 carbon atoms, alkoxy or phenyl, and Ar is a tetravalent radical having 2 to 27 carbon atoms selected from the group consisting of aliphatic, alicyclic, monoaromatic, condensed polyaromatic and non-condensed aromatic radicals linked to one another via a direct bond or a bridging element, and 99 to 1 mol% of repeating structural units of the formula (6):

wherein n, Q and Ar' are the same as above, or this polyimide copolymer having an aromatic ring at its polymer chain end which is unsubstituted or substituted with a group which does not react with amines and/or dicarboxylic anhydrides.

10) A polyimide copolymer comprising two or more repeating structural units of the formula (1) described in claim 1, or said polyimide copolymer having an aromatic ring at its polymer chain terminal which is unsubstituted or substituted with a group which does not react with amines and dicarboxylic anhydrides.

Another aspect of the present invention is a manufacturing process for these polyimide homopolymers and copolymers, namely:

11) A manufacturing process for a polyimide having a required structural unit consisting of one or more repeating structural units of the formula (1)

wherein m, n, R and Ar have the same meaning as above, comprising the reaction of aromatic diamine consisting essentially of one or more aromatic diamino compounds of the formula (7)

wherein m, n and R have the same meaning as above, with a tetracarboxylic acid dianhydride which primarily has the formula (8)

wherein Ar is a tetravalent radical having 2 to 27 carbon atoms selected from the group consisting of aliphatic radicals, alicyclic radicals, monoaromatic radicals, condensed polyaromatic radicals and non-condensed aromatic radicals which are linked to one another via a direct bond or a bridging element, and thermally or chemically imidizing the resulting polyamic acid.

12) A production process for a polyimide having a required structural unit consisting of one or more of the repeating structural units of the formula (1)

wherein m, n, R and Ar have the same meaning as above, with a radical at the polymer chain end which is essentially unsubstituted or substituted with a radical which does not react with amines and/or dicarboxylic acid anhydrides, comprising the reaction of aromatic diamine which consists essentially of one or more aromatic diamino compounds of the formula (7)

where m, n and R have the same meaning as above, with tetracarboxylic acid dianhydride, which primarily has the formula (8)

wherein Ar has the same meaning as above, in the presence of aromatic dicarboxylic acid anhydride of the formula (9)

wherein Z is a divalent radical having 6 to 15 carbon atoms selected from the group consisting of monoaromatic radicals, condensed polyaromatic radicals and non-condensed aromatic radicals which can be directly bond or a bridge element, and/or aromatic monoamine of the formula (10):

Z₁-NH₂ (10)

wherein Z₁ is a monovalent radical having 6 to 15 carbon atoms selected from the group consisting of monoaromatic radicals, condensed polyaromatic radicals and non-condensed aromatic radicals linked together by a direct bond or a bridging element, and thermally or chemically imidizing the resulting polyamic acid.

In these processes, the preferred aromatic dicarboxylic anhydride is phthalic anhydride and the preferred aromatic monoamine is aniline. The amount of aromatic dicarboxylic anhydride (phthalic anhydride) is 0.001 to 1.0 mole per mole of aromatic diamine. The amount of aromatic monoamine (aniline) is 0.001 to 1.0 mole per mole of aromatic tetracarboxylic dianhydride.

Another aspect of the present invention is:

13) A composition, a film and a solution comprising a polyimide according to the present invention.

Yet another aspect of the present invention is a novel aromatic diamino compound and the starting aromatic dinitro compound, namely:

14) An aromatic dinitro compound of formula (11):

where m, n and R have the same meaning as in formula (1).

15) An aromatic diamino compound of formula (7):

where m, n and R have the same meaning as in formula (1).

16) An aromatic diamino compound of formula (12):

wherein n = 0 or 1 and Ra is a hydrogen atom, a halogen atom, alkyl having 1 to 4 carbon atoms, alkoxy or phenyl.

17) An aromatic diamino compound of formula (13):

where R&sub9;

18) An aromatic diamino compound of formula (14):

wherein R�9 has the same meaning as above.

19) An aromatic diamino compound of formula (15):

wherein R�9 has the same meaning as above.

Yet another aspect of the present invention relates to a production process for these aromatic diamino compounds.

20) A production process for an aromatic diamino compound of the formula (7):

where m and n are each equal to 0 or 1 and R

wherein R₁, R₂, R₃ and R₄ are each a hydrogen atom, a halogen atom, alkyl having 1 to 8 carbon atoms, aryl, alkenyl, aralkyl or alkoxy having 1 to 5 carbon atoms; R₅, R₆ and R₇ are each a hydrogen atom, alkyl having 1 to 8 carbon atoms, aryl, alkenyl, aralkyl or ω-alkyloxyoligo(alkyleneoxy)alkyl having 1 to 10 carbon atoms and 1 to 3 oxygen atoms; and Ar is a tetravalent radical having 2 to 27 carbon atoms selected from the group consisting of aliphatic radicals, alicyclic radicals, monoaromatic radicals, condensed polyaromatic radicals and non-condensed aromatic radicals linked to one another via a direct bond or a bridging element, comprising carrying out the condensation of a dinitro compound of the formula (16):

wherein X is a halogen atom and m and n are each 0 or 1, with a hydroxy compound of the formula (17):

R-OH (17)

wherein R has the same meaning as above, in an aprotic polar solvent in the presence of a base to give an aromatic dinitro compound of the formula (11):

wherein m, n and R have the same meaning as above, and the subsequent reduction of the aromatic dinitro compound.

The polyimide of the present invention is substantially amorphous, has excellent melt flow stability at reduced temperature compared with conventional known polyimides, has greatly improved processability, and can be used for structural materials because of high elastic modulus. That is, with the polyimide of the present invention obtained by using a novel aromatic diamino compound as a monomer, various properties such as melt flowability and solvent solubility can be controlled via the side chains rather than the polyimide main chain. Thus, excellent melt flow properties and solvent solubility can be achieved while maintaining high heat resistance and adhesive properties resulting from the benzophenone structure of the diamino compound of the present invention.

Furthermore, the polyimide of the present invention can exhibit satisfactory adhesive strength at relatively reduced temperatures and can therefore be used for adhesives. The polyimide is soluble in general-purpose organic solvents such as chloroform and can therefore also be used in the form of polyimide varnish. In the case of use as an adhesive, the polyimide is ring-closed in advance and can therefore be used as a varnish in the imide state. As a result, the conventional disadvantage of the generation of voids due to moisture can also be eliminated. Hot-press bonding can also be carried out using a polyimide film.

Embodiments of the invention will now be described by way of example with reference to the drawings, in which:

Fig. 1 illustrates the IR spectrum of 3,3'-dinitro-4-phenoxybenzophenone obtained in Example 3.

Fig. 2 illustrates the IR spectrum of 3,3'-diamino-3-phenoxybenzophenone obtained in Example 3.

Fig. 3 illustrates the IR spectrum of 3,4'-dinitro-4-biphenoxybenzophenone obtained in Example 4.

Fig. 4 illustrates the IR spectrum of 3,4'-diamino-4-biphenoxybenzophenone obtained in Example 4.

Fig. 5 illustrates the IR spectrum of 1,3-bis-(3-nitro-4-phenoxybenzoyl)benzene obtained in Example 5.

Fig. 6 illustrates the IR spectrum of 1,3-bis(3-amino-4-phenoxybenzoyl)benzene obtained in Example 5.

Fig. 7 illustrates the IR spectrum of 1,3-bis-(3-amino-4-biphenoxybenzoyl)benzene obtained in Example 6.

Fig. 8 illustrates the IR spectrum of 3,3'-diamino-4,4'-dimethoxybenzophenone obtained in Example 7.

Fig. 9 illustrates the IR spectrum of the polyimide powder obtained in Example 8.

Fig. 10 is a drawing illustrating the relationships between the viscosity and the residence time of the polyimide powder obtained in Example 8 in the cylinder of a flow tester.

Fig. 11 illustrates the IR spectrum of the polyimide powder obtained in Example 31.

Fig. 12 is a drawing illustrating the relationships between the viscosity and the residence time of the polyimide powder obtained in Example 31 in a cylinder of a flow tester.

The polyimide of the present invention comprises a required structural unit consisting of one or more repeating structural units of the formula (1):

where m and n are each 0 or 1, Lind R

wherein R₁, R₂, R₃ and R₄ are each a hydrogen atom, a halogen atom, alkyl having 1 to 8 carbon atoms, aryl, alkenyl, aralkyl or alkoxy having 1 to 5 carbon atoms, and R₅, R₆ and R₇ are are each a hydrogen atom, alkyl having 1 to 8 carbon atoms, aryl, alkenyl, aralkyl or ω-alkyloxyoligo(alkyleneoxy)alkyl having 1 to 10 carbon atoms and 1 to 3 oxygen atoms and Ar is a tetravalent radical having 2 to 27 carbon atoms selected from the group consisting of aliphatic radicals, alicyclic radicals, monoaromatic radicals, condensed polyaromatic radicals and non-condensed aromatic radicals which are connected to one another via a direct bond or a bridging element.

That is, the invention is based on a polyimide comprising a required structural unit having repeating structural units of the formula (1), and may specifically be a homopolymer of one of the repeating structural units of the formula (1) or a copolymer of two or more of the repeating structural units. The polyimide of the invention may also be a copolymer of repeating structural units of the formula (1) and other polyimide repeating structural units within the range that does not adversely affect the properties of the polyimide of the invention. Furthermore, the polyimide of the invention may have an aromatic ring at the polymer chain end which is substantially unsubstituted or substituted with a group which does not react with amines and dicarboxylic anhydrides. That is, the polyimide of the invention may have an aromatic dicarboxylic anhydride of the formula (9) at its polymer chain end.

wherein Z is a divalent radical having 6 to 15 carbon atoms selected from the group consisting of monoaromatic radicals, condensed polyaromatic radicals and non-condensed aromatic radicals linked to one another via a direct bond or a bridging element, and/or with aromatic monoamine of formula (16):

Z₁-NH₂ (16)

wherein Z₁ is a monovalent radical having 6 to 15 carbon atoms selected from the group consisting of monoaromatic radicals, fused polyaromatic radicals and non-fused aromatic radicals linked to one another via a direct bond or a bridging element.

A preferred aromatic polyimide is capped at its polymer chain end with phthalic anhydride and/or aniline.

The polyimide of the present invention includes a polyimide homopolymer of one of the above repeating structural units, a polyimide copolymer of two or more of the above repeating structural units, a mixture of two or more polyimide homopolymers and/or polyimide copolymers, a polyimide copolymer of the repeating structural units of the formula (1) and other repeating structural units contained in a proportion that does not have a negative effect on the essential polyimide properties, and a mixture of polyimide having one or more repeating structural units of the formula (1) and polyimide having the other repeating structural units.

Accordingly, when the polyimide according to the present invention is a polyimide copolymer of two or more repeating structural units of the formula (1) or a polyimide mixture, it has two or more repeating structural units in which one or more of the parameters m, n, Ar and R in the formula (1) are different from each other.

The polyimide of the present invention can be prepared by reacting the starting monomers, the aromatic diamine and the aromatic tetracarboxylic dianhydride in the absence or presence of aromatic dicarboxylic anhydride and/or aromatic monoamine and by thermally or chemically imidizing the resulting polyamic acid.

The aromatic diamine used to prepare these polyimides consists essentially of one or more aromatic diamino compounds of the formula (7):

where m and n are each 0 or 1, and R

wherein R₁, R₂, R₃ and R₄ are each a hydrogen atom, a halogen atom, alkyl having 1 to 8 carbon atoms, aryl, alkenyl, aralkyl or alkoxy having 1 to 5 carbon atoms and R₅, R₆ and R₇ are each a hydrogen atom, alkyl having 1 to 8 carbon atoms, aryl, alkenyl, aralkyl or ω-alkyloxyoligo(alkyleneoxy)alkyl having 1 to 10 carbon atoms and 1 to 3 oxygen atoms. A preferred aromatic diamine is an aromatic diamine compound of the formula (12):

wherein n = 0 or 1, R�8 is hydrogen atom, a halogen atom, alkyl having 1 to 4 carbon atoms, alkoxy and phenyl.

The most preferred aromatic diamines are aromatic diamino compounds of the formula (13):

where R&sub9;

the formula (14):

wherein R�9 has the same meaning as above, and the formula (15):

wherein R�9 has the same meaning as above.

Examples of usable aromatic diamino compounds are:

3,3'-diamino-4,4'-diphenoxybenzophenone,

4,4'-diamino-5,5'-diphenoxybenzophenone,

3,4'-diamino-4,5'-diphenoxybenzophenone,

3,3'-diamino-4-phenoxybenzophenone,

4,4'-diamino-5-phenoxybenzophenone,

3,4'-diamino-4-phenoxybenzophenone,

3,4'-diamino-5'-phenoxybenzophenone,

3,3'-diamino-4,4'-dibiphenoxybenzophenone,

4,4'-diamino-5,5'-dibiphenoxybenzophenone,

3,4'-diamino-4,5'-dibiphenoxybenzophenone,

3,3'-diamino-4-biphenoxybenzophenone,

4,4'-diamino-5-biphenoxybenzophenone,

3,4'-Diamino-4-biphenoxybenzophenone and

3,4'-Diamino-5'-biphenoxbenzophenone.

These aromatic diamino compounds can be used individually or as a mixture.

These aromatic diamino compounds can be prepared, for example, by the following process.

An aromatic dinitro compound of formula (16):

wherein X is a halogen atom and m and n are each 0 or 1, is reacted in an aprotic polar solvent in the presence of a base with a hydroxy compound of the formula (17)

R-OH (17)

condensed, where R

wherein R₁, R₂, R₃ and R₄ are each a hydrogen atom, a halogen atom, alkyl having 1 to 8 carbon atoms, aryl, alkenyl, aralkyl or alkoxy having 1 to 5 carbon atoms, and R₅, R₆ and R₇ are each a hydrogen atom, alkyl having 1 to 8 carbon atoms, aryl, alkenyl, aralkyl or ω-alkyloxyoligo(alkyleneoxy)alkyl having 1 to 10 carbon atoms and 1 to 3 oxygen atoms, so that an aromatic dinitro compound of the formula (11):

where m, n and R have the same meaning as above. The dinitro compound thus obtained is then reduced to give the aromatic diamino compound of formula (7)

where m, n and R have the meaning given above.

Preferably, the following aromatic halogenodinitro compounds of the formula (16) are used to prepare the aromatic dinitro compound of the formula (11) used in the process.

Dihalodinitrobenzophenone of formula (16-1):

wherein X is a halogen atom includes, for example, 4,4'-dihalogeno-3,3'-dinitrobenzophenone.

Monohalodinitrobenzophenone of formula (16-2):

wherein X is a halogen atom, includes for example

4-Halogen-3,3'(or 4')-dinitrobenzophenone, such as

4-chloro-3,3'-dinitrobenzophenone,

4-chloro-3,4'-dinitrobenzophenone,

4-Brom-3,3'-dinitrobenzophenone,

4-Brom-3,4'-dinitrobenzophenone,

4-fluoro-3,3'-dinitrobenzophenone,

4-fluoro-3,4'-dinitrobenzophenone,

4-iodo-3,3'-dinitrobenzophenone and

4-iodine-3,4'-dinitrobenzophenone.

Preferably, 4-chloro-3,3'-dinitrobenzophenone or 4-chloro-3,4'-dinitrobenzophenone is used.

1,3-(or 1,4-)bis-(3-nitro-4-halogenobenzoyl)benzene of formula (16-3)

wherein X is a halogen atom, includes for example

1,3-Bis-(3-nitro-4-chlorobenzoyl)benzene,

1,4-Bis-(3-nitro-4-chlorobenzoyl)benzene,

1,3-bis-(3-nitro-4-fluorobenzoyl)benzene,

1,4-bis-(3-nitro-4-fluorobenzoyl)benzene,

1,3-bis-(3-nitro-4-bromobenzoyl)benzene,

1,4-bis-(3-nitro-4-bromobenzoyl)benzene,

1,3-bis-(3-nitro-4-iodobenzoyl)benzene and

1,4-Bis-(3-nitro-4-iodobenzoyl)benzene.

More preferably, 1,3-bis-(3-nitro-4-chlorobenzoyl)benzene or 1,3-bis-(3-nitro-4-chlorobenzoyl)benzene is used.

The aromatic dinitro compound of formula (11) can be prepared in high yield by reacting these aromatic halogen dinitro compounds with phenols or alcohols in an aprotic polar solvent in the presence of a base.

The aromatic halogen dinitro compound used as starting material for the process, for example 4,4'-dihalogen-3,3'-dinitrobenzophenone, can be prepared by nitration of 4,4'-dihalogen benzophenone according to the process known from JP-A-58-121256 can be obtained without any problems. Other aromatic dinitro compounds can also be prepared by similar processes.

Examples of phenols that can be used include phenol, cresol, dimethylphenol and other alkylphenols; guaiacol, dimethoxyphenol and other alkoxyphenols; chlorophenol, fluorophenol, dichlorophenol, difluorophenol and other halophenols; phenylphenol, diphenylphenol and other arylphenols; phenoxyphenol, diphenoxyphenol and other aryloxyphenols; and naphthol, anthrol and other polycyclic phenols and alkyl, alkoxy, halogen and aryl derivatives of these polycyclic phenols. Phenols and polycyclic phenols with two or more types of substituents, such as haloalkylphenols and haloarylphenols, can also be used.

Examples of alcohols that can be used are methanol, ethanol, isopropyl alcohol, t-butyl alcohol and other alkyl alcohols; ethylene glycol monomethyl ether, diethylene glycol monomethyl ether, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether and other oligoalkylene glycol monoalkyl ethers; benzyl alcohol and other arylalkyl alcohols; as well as propenyl alcohol, isopropenyl alcohol and other alkenyl alcohols. The phenols and alcohols are not limited to the compounds listed here.

The amount of these phenols or alcohols is 1.0 to 1.5 mol, preferably 1.03 to 1.3 mol, per mol of the aromatic halodinitro compound of the formula (16) when an aromatic monohalodinitro compound is used, and 2.0 to 3.0 mol, preferably 2.05 to 2.6 mol, when an aromatic dihalodinitro compound is used.

Bases that can be used are carbonates, hydrogen carbonates, hydroxides and alkoxides of alkali metals, including potassium carbonate, potassium hydrogen carbonate, potassium hydroxide, sodium carbonate, sodium hydroxide, sodium hydrogen carbonate, lithium carbonate, lithium hydroxide, sodium methoxide and potassium isopropoxide.

The amount of these bases is superstoichiometric, in practice 1 to 2 equivalents per equivalent of halogen residues in the aromatic halogen dinitro compound of the formula (16), (16-1), (16-2) or (16-3).

Examples of the aprotic polar solvents used are N,N-dimethylformamide, N,N-diethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, 1,3-dimethyl-2-imidazolidinone, dimethyl sulfoxide, sulfolane and tetrahydrofuran. The amount of these solvents is not particularly limited, and an amount of 1 to 10 times the weight of the starting materials is usually sufficient.

Catalysts that can be used to accelerate the reaction are copper powder, copper compounds and phase transfer catalysts such as crown ethers, polyethylene glycol, quaternary ammonium bases and quaternary phosphonium bases.

The reaction temperature is in the range of -10ºC to 250ºC, preferably -5ºC to 180ºC. The reaction time is in the range of 0.5 to 30 h, preferably 1 to 10 h.

The reaction can generally be carried out by the following procedures.

(1) Prescribed amounts of a phenol or alcohol, a base and a solvent are charged to form an alkali metal salt of the phenol or alcohol, whereupon the aromatic dinitro compound of the formula (16), for example, 4,4'-dihalo-3,3'-dinitrobenzophenone is added for reaction.

(2) The aromatic dinitro compound of formula (16), for example 4,4'-dihalo- 3,3'-dinitrobenzophenone, is introduced into a solvent and then a preliminarily formed alkali metal salt of phenol or alcohol is added to the mixture to carry out the reaction.

(3) First, all the materials including the aromatic dinitro compound of the formula (16), for example, 4,4'-dihalo-3,3'-dinitrobenzophenone, are charged at once and the mixture is heated in this form to carry out the reaction. However, the methods are not limited to these embodiments, but other suitable methods can be used.

If water is present in the reaction system, it is removed from the reaction system by introducing nitrogen gas during the reaction.

However, a commonly used method is the azeotropic distillation of water by adding a small amount of benzene, toluene, xylene or chlorobenzene.

The end point of the reaction can be determined by the decrease of the starting materials by TLC or HPLC. After completion of the reaction, the reaction mixture is poured into water as is or after concentration to obtain the dinitro compound as a crude product. The crude product can be purified by recrystallization from or slurrying in a solvent.

The aromatic dinitro compound of formula (11)

wherein m, n and R have the same meaning as above and which is obtained by the above reaction, is, for example, a compound of the formula (11-1):

the formula (11-2):

or the formula (11-3):

In formula (11-1), (11-2) and (11-3), R is the same as above, preferably

The aromatic dinitro compound obtained above is reduced to give the aromatic diamino compound.

That is, the aromatic diamino compound of the present invention can be produced by reducing the corresponding aromatic dinitro compound obtained by the above process.

The reduction process for the dinitro compound is not subject to any special restriction.

Usually, a method for reducing a nitro residue to an amino residue can be used, for example, as described in Shin Jikken Kagaku Koza, Vol. 15, "Oxidation and Reduction II", published by Maruzen (1977). In industry, catalytic reduction is preferred. Examples of reduction catalysts that can be used are metal catalysts, such as those generally used for catalytic reduction. such as nickel, palladium, platinum, rhodium, ruthenium, cobalt and copper. Palladium catalysts are preferred in industry.

Although they can also be used in metallic form, these catalysts are generally supported on the surface of a carrier such as activated carbon, barium sulfate, silica gel, alumina and cerite, or in the form of a Raney catalyst of nickel, cobalt or copper.

The amount of these catalysts is not subject to any particular restriction. It is in the range of 0.01 to 10 wt.%, usually 2 to 8 wt.%, in metallic form, based on the starting dinitro compound, and 0.1 to 5 wt.% on a carrier.

In the case of reduction with iron powder, the reaction temperature is in the range of 0ºC to 150ºC, preferably 0ºC to 70ºC.

The reaction can be carried out by gradually adding iron powder to a solution or suspension of the starting material and a catalytic amount of hydrochloric acid, or by previously placing the starting materials containing iron powder in a solvent to carry out the reaction.

The solvents used in the reduction are not subject to any special restrictions as long as they are inactive with respect to the reaction.

Preferred solvents include methanol, ethanol, isopropyl alcohol and other alcohols; ethylene glycol, propylene glycol and other glycols; ether, dioxane, tetrahydrofuran, methyl cellosolve and other ethers. Other solvents that may be used in some cases include hexane, cyclohexane and other aliphatic hydrocarbons; benzene, toluene, xylene and other aromatic hydrocarbons; ethyl acetate, butyl acetate and other esters; dichloromethane, chloroform, carbon tetrachloride, 1,2-dichloroethane, 1,1,2-trichloroethane, tetrachloroethane and other halogenated Hydrocarbons; and N,N-dimethylformamide. The amount of these solvents is not subject to any particular restriction. They are used in an amount sufficient to suspend or completely dissolve the starting materials, ie usually 0.5 to 10 times the weight of the starting materials.

The reaction temperature is not particularly limited. It is usually in the range of 20-200ºC, preferably 20-100ºC. The reaction pressure is in the range of atmospheric pressure to 50 atm.

The reduction reaction is usually carried out by suspending or dissolving the dinitro compound in a solvent, adding the catalyst and introducing hydrogen into the reaction system while stirring at a certain temperature. The end point of the reaction can be determined by the amount of hydrogen, TLC or HPLC. After the reaction is complete, the catalyst is removed by filtration and the solvent is distilled off from the filtrate to obtain the desired product.

The polyimide of the present invention can be prepared from the above aromatic diamino compound.

The most preferred repeating structural units of the polyimide include, for example, units of the formula (2):

wherein m and n are each 0 or 1, R₈ is a hydrogen atom, a halogen atom, alkyl having 1 to 4 carbon atoms, alkoxy or phenyl and Ar is a tetravalent radical having 2 to 27 carbon atoms, selected from the group consisting of aliphatic radicals, alicyclic radicals, monoaromatic radicals, condensed polyaromatic radicals and non-condensed aromatic radicals linked together by a direct bond or a bridging element;

Units of formula (3):

where R&sub9;

and Ar is the same as in formula (2);

Units of formula (4):

wherein R�9 and Ar are the same as in formula (3), and

Units of formula (5):

wherein R�9 and Ar are the same as in formula (3).

Another preferred polyimide is a copolymer having required structural units consisting of 1 to 99 mol% of the repeating structural units of the above formulas (1), (2), (3), (4) or (5) and 99 to 1 mol% of the repeating structural units of the formula (6):

wherein n is an integer from 0 to 5, Q is a direct bond, -O-, -S-, -CO-, -SO₂-, -CH₂-, -C(CH₃)₂- or -C(CF₃)₂- and can be the same or different when aromatic rings are connected to one another via two or more connecting radicals Q, and Ar' is a tetravalent radical having 2 to 27 carbon atoms selected from the group consisting of aliphatic radicals, alicyclic radicals, monoaromatic radicals, fused polyaromatic radicals and non-fused aromatic radicals which are connected to one another via a direct bond or a bridging element.

The polyimide of the present invention is prepared using the above aromatic diamines as a required starting monomer.

Other aromatic diamines can also be used in combination with these diamines, as long as this does not result in any negative effects on the good properties of the polyimide.

Other aromatic diamines that can be used in combination are, for example, m-phenylenediamine, o-phenylenediamine, p-phenylenediamine, m-aminobenzylamine, p-aminobenzylamine, 4,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, bis-(3-aminophenyl) sulfide, (3-aminophenyl)-(4-aminophenyl) sulfide, bis-(4-aminophenyl) sulfide, bis-(3-aminophenyl) sulfoxide, (3-aminophenyl)-(4-aminophenyl) sulfoxide, Bis-(3-aminophenyl)sulfone, (3-aminophenyl)-(4-aminophenyl)sulfone, bis-(4-aminophenyl)sulfone, 3,3'-diaminobenzophenone, 3,4'-diaminobenzophenone, 4,4'-diaminobenzophenone, 3,3'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 4,4'-dia minodiphenylmethane, bis-[4-(3-aminophenoxy)phenyl]methane, bis-[4-(4-aminophenoxy)phenyl]methane, 1,1-bis-[4-(3-aminophenoxy)phenyl]ethane, 1,1-bis-[4-(4-aminophenoxy)phenyl]ethane, 1,2-bis-[4-(3-aminophenoxy)phenyl]ethane, 1,2- Bis-[4-(4-aminophenoxy)phenyl]ethane, 2,2-bis-[4-(3-aminophenoxy)phenyl]propane, 2,2-bis-[4-(4-aminophenoxy)phenyl]propane, 2,2-bis-[4-(3-aminophenoxy)phenyl]butane, 2,2-bis-[4-(3-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane, 2,2-bis-[4-(4-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane, 1,3-bis-(3-aminophenoxy)benzene, 1,3-bis-(4-aminophenoxy)benzene, 1,4-bis-(3-aminophenoxy)benzene, 1,4-bis-(4-aminophenoxy)benzene, 1,3-bis-(3-aminobenzoyl)benzene, 1,3-Bis-(4-aminobenzoyl)benzol, 1,4-Bis-(3-aminobenzoyl)benzol, 1,4-Bis-(4-aminobenzoyl)benzol, 1,3-Bis-(3-amino-α,α- dimethylbenzyl)benzol, 1,3-Bis-(4-amino-α,α-dimethylbenzyl)benzol, 1,4-Bis-(3-amino- α,α-dimethylbenzyl)benzol, 1,4-Bis-(4-amino-α,α-dimethylbenzyl)benzol, 4,4'-Bis-(3- aminophenoxy)biphenyl, 4,4'-Bis-(4-aminophenoxy)biphenyl, Bis-[4-(3-aminophenoxy)phenyl]keton, Bis-[4-(4-aminophenoxy)phenyl]keton, Bis-[4-3-aminophenoxy)phenyl]sulfide, bis-[4-(4-aminophenoxy)phenyl]sulfide, bis-[4-(3-aminophenoxy)phenyl]sulfoxide, bis-[4-(4-aminophenoxy)phenyl]sulfoxide, bis-[4-(3-aminophenoxy)phenyl]sulfone, bis-[4-(4-aminophenoxy)phenyl]sulfone, bis-[4 -(3-aminophenoxy)phenyl]ether, bis-[4-(4-aminophenoxy)phenyl]ether, 1,4-bis-[4-(3-aminophenoxy)benzoyl]benzene, 1,3-bis-[4-(3-aminophenoxy)benzoyl]benzene, 4,4'-bis-[3-(4-aminophenoxy)benzoyl]diphenyl ether, 4,4'-Bi s-[3-(3-aminophenoxy)benzoyl]diphenyl ether, 4,4'-Bis-[4-(4-amino-α,α-dimethylbenzyl)phenoxy]benzophenon, 4,4'-Bis-[4-(4-amino-α,α-dimethylbenzyl)phenoxy]diphenylsulfon, Bis-{4-[4-(4-aminophenoxy)phenoxy]phenyl}sulfon, 1,4-Bis-[4-(4-aminophenoxy)- α,α-dimethylbenzyl]benzol, 1,4-Bis-[4-(3-aminophenoxy)-α,α-dimethylbenzyl]benzol, 1,3-Bis-[4-(4-aminophenoxy)-α,α-dimethylbenzyl]benzol, 1,3-Bis-[4-(3-aminophenoxy)- α,α-dimethylbenzyl]benzol, 3,3'-Diamino-4,4'-difluorobenzophenone, 3,3'-diamino-5,5'-bis(trifluoromethyl)diphenyl ether and 4,4'-diamino-5,5'-bis(trifluoromethyl)diphenyl ether.

These aromatic diamines can be used individually or as mixtures.

Aromatic tetracarboxylic acid dianhydrides which can be used according to the present invention consist of one or more of the compounds of formula (8):

wherein Ar is a tetravalent radical having 2 to 27 carbon atoms selected from the group consisting of aliphatic radicals, alicyclic radicals, monoaromatic radicals, fused polyaromatic radicals and non-fused aromatic radicals linked together by a direct bond or a bridging element.

In the aromatic tetracarboxylic acid dianhydride of formula (8), Ar is specifically a tetravalent radical selected from the group consisting of aliphatic radicals having 2 to 10 carbon atoms, alicyclic radicals having 4 to 10 carbon atoms, monoaromatic radicals of formula (a):

condensed polyaromatic radicals of the formula (b):

and non-condensed aromatic radicals which are linked to one another via a direct bond or a bridging element and have the formula (c):

where X is a direct bond, -CO-, -O-, -S-, -SO₂-, -CH₂-, -C(CH₃)₂-, -C(CF₃)₂-,

wherein Y is a direct bond, -CO-, -O-, -S-, -SO₂-, -CH₂-, -C(CH₃)₂- or -C(CF₃)₂-.

Examples of tetracarboxylic acid dianhydrides of the formula (8) which can be used according to the present invention are ethylenetetracarboxylic acid dianhydride, cyclopentanetetracarboxylic acid dianhydride, pyromellitic acid dianhydride, 3,3',4,4'-benzophenonetetracarboxylic acid dianhydride, 2,2',3,3'-benzophenonetetracarboxylic acid dianhydride, 3,3',4,4'-biphenyltetracarboxylic acid dianhydride, 2,2',3,3'-biphenyltetracarboxylic acid dianhydride, 2,2-bis-(3,4-dicarboxyphenyl)propane dianhydride, 2,2-bis-(2,3-dicarboxyphenyl)propane dianhydride, bis-(3,4-dicarboxyphenyl)ether dianhydride, bis-(3,4-dicarboxyphenyl)sulfone dianhydride, 1,1-bis-(2,3-dicarboxyphenyl)ethanedianhydride, Bis-(2,3-dicarboxyphenyl)methandianhydrid, Bis-(3,4-dicarboxyphenyl)methandianhydrid, 2,2-Bis- (3,4-dicarboxyphenyl)-1,1,1,3,3,3-hexafluorpropandianhydrid, 2,2-Bis-(2,3-dicarboxyphenyl)-1,1,1,3,3,3-hexafluorpropandianhydrid, 1,3-Bis-[(3,4-dicarboxy)benzoyl]benzoldianhydrid, 1,4-Bis-[(3,4-dicarboxy)benzoyl]benzoldianhydrid, 2,2-Bis-{4[4-(1,2-dicarboxy)benzoyl]phenyl}propandianhydrid, 2,2-Bis-{4[3-(1,2-dicarboxy)phenoxy]phenyl}propandianhydrid, Bis-{4-[4-(1,2-dicarboxy)phenoxy]phenyl}ketone dianhydride, bis-{4-[3-(1,2-dicarboxy)phenoxy]phenyl}ketone dianhydride, 4,4'-bis-[4-(1,2-dicarboxy)phenoxy]biphenyl dianhydride, 4,4'-bis-[3-(1,2-dicarboxy)phenoxy]biphenyl dianhydride id, Bis-{4-[4-(1,2-dicarboxy)phenoxy]phenyl}ketone dianhydride, Bis-{4-[3-(1,2-dicarboxy)phenoxy]phenyl}ketone dianhydride, Bis-{4-[4-(1,2-dicarboxy)phenoxy]phenyl}sulfone dianhydride, Bis-{4-[3-(1,2-dicarboxy)phenoxy]phenyl}sulfone dianhydride, Bis -{4-[4-(1,2-dicarboxy)phenoxy]phenyl}sulfide dianhydride, bis-{4-[3-(1,2-dicarboxy)phenoxy]phenyl}sulfide dianhydride, 2,2-bis-{4-[4-(1,2-dicarboxy)phenoxy]phenyl}-1,1,1,3,3,3-hexafluoropropane dianhydride, 2,2-bis-{4-[3-(1,2-dicarboxy)phenoxy]phenyl}-1,1,1,3,3,3-hexafluoropropane dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 1,2,3,4-benzenetetracarboxylic dianhydride, 3,4,9,10-perylenetetracarboxylic dianhydride, 2,3,6,7-anthracenetetracarboxylic dianhydride and 1,2,7,8-phenanthrenetetracarboxylic dianhydride.

These dianhydrides can be used individually or as mixtures.

The polyimide of the present invention prepared by using the above aromatic diamine and aromatic tetracarboxylic dianhydride as monomer components comprises a required structural unit consisting primarily of repeating structural units of the formula (1). That is, the invention includes a polyimide derived from a specific aromatic diamine and a specific aromatic tetracarboxylic dianhydride as the above-mentioned starting materials of the invention and having repeating structural units of the formulas (1) - (5), a polyimide copolymer derived from one or more specific aromatic diamines and one or more specific aromatic tetracarboxylic dianhydrides (excluding one of each) as the above-mentioned starting materials of the invention, and a polyimide copolymer derived from one or more specific aromatic diamines and one or more specific aromatic tetracarboxylic dianhydrides as the above-mentioned starting materials according to the present invention in combination with other diamines added in such a range that the properties of the resulting polyimide are not adversely affected.

The aromatic polyimide copolymer having a basic skeleton consisting of repeating structural units of the formula (1) and repeating structural units of the formula (6) can be prepared by reacting an aromatic diamino compound of the formula (7):

in the presence of one or more diamines of formula (6-1):

H₂N - X - NH₂ (6-1)

where X

wherein n is an integer from 0 to 5; Q is a direct bond, -O-, -S-, -CO-, -SO₂-, -CH₂-, -C(CH₃)₂- or -C(CF₃)₂- and may be the same or different when two or more Q radicals connect three or more aromatic rings to each other; with one or more aromatic tetracarboxylic dianhydrides selected from the above formula (8) or the formula (6-2):

wherein Ar' is a trivalent radical selected from the group consisting of

wherein M is a divalent radical selected from the group consisting of

consists.

Examples of aromatic diamines of the formula (6-1) used in the reaction are m-phenylenediamine, o-phenylenediamine and p-phenylenediamine, benzidine, 3,3'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl sulfide, 3,4'-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl sulfone, 3,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfone, 3,3'-diaminobenzophenone, 3,4'-diaminobenzophenone, 4,4'-diaminobenzophenone, 3,3'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, 2,2'-bis-(4-aminophenyl)propane, 2,2-bis-(3-aminophenyl)propane, 2-(3-aminophenyl)-2-(4-aminophenyl)propane, 2,2-bis-(3-aminophenyl)-1,1,1,3,3,3-hexafluoropropane, 2,2-bis-(4-aminophenyl)-1,1,1,3,3,3-hexafluoropropane and 2-(3-aminophenyl)-2-(4-aminophenyl)propane, 1,3-bis-(3-aminophenoxy)benzene, 1,3-bis-(4-aminophenoxy)benzene, 1,4-bis-(3-aminophenoxy)benzene, 1,4-bis-(4-aminophenoxy)benzene, 1,3-bis-(3-aminobenzoyl)benzene, 1,3-bis-(4-aminobenzoyl)benzene, 1,4-bis-(4-aminobenzoyl)benzene, 1,3-bis-(3-amino-α,α-dimethylbenzyl)benzene, 1,4-bis-(3-amino-α,α-dimethylbenzyl)benzene and 1,4-bis-(4-amino-α,α-dimethylbenzyl)benzene, 4,4'-bis-(4-aminophenoxy)biphenyl, 3,3'-bis-(4-aminophenoxy)biphenyl, 3,4'-bis-(3-ami nophenoxy)biphenyl, bis-[4-(4-aminophenoxy)phenyl]ketone, bis-[4-(3-aminophenoxy)phenyl]ketone, bis-[3-(3-aminophenoxy)phenyl]ketone, bis-[4-(4-aminophenoxy)phenyl] sulfide, bis-[4-(3-aminophenoxy)phenyl] sulfide, bis-[3-(4-aminophenoxy)phenyl] sulfide, Bis-[3-(3-aminophenoxy)phenyl] sulfide, Bis-[4-(4-aminophenoxy)phenyl]sulfone, bis-[4-(3-aminophenoxy)phenyl]sulfone, bis-[3-(4-aminophenoxy)phenyl]sulfone, bis-[3-(3-aminophenoxy)phenyl]sulfone, bis-[4-(3-aminophenoxy)phenyl]ether, bis-[4-(4-aminophenoxy)phenyl]ether, bis-[3-(4 -aminophenoxy)phenyl]ether, bis-[3-(3-aminophenoxy)phenyl]ether, bis-[4-(3-aminophenoxy)phenyl]methane, bis-[4-(4-aminophenoxy)phenyl]methane, bis-[3-(3-aminophenoxy)phenyl]methane, bis-[3-(4-aminophenoxy)phenyl]methane, 2,2-bis-[4-(3-aminophenoxy)phenyl]methane, phenyl]propane, 2,2-bis-[4-(4-aminophenoxy)phenyl]propane, 2,2-bis-[3-(3-aminophenoxy)phenyl]propane, 2,2-bis-[3-(4-aminophenoxy)phenyl]propane, 2,2-bis-[4-(3-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane, 2,2-bis-[4-(4-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane, 2,2-bis-[3-(3-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane and 2,2-bis-[3-(4-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane.

These aromatic diamines can be used individually or as mixtures.

Examples of aromatic tetracarboxylic acid dianhydrides of formula (6-2) include:

Pyromellitic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 3,3,4,4'-benzophenonetetracarboxylic dianhydride, bis-(3,4-dicarboxyphenyl)ether dianhydride, 2,2-bis-(3,4-dicarboxyphenyl)propane dianhydride, 2,2-bis-(3,4-dicarboxyphenyl)1,1,1,3,3,3-hexafluoropropane dianhydride, 1,3-bis-[4-(1,2-dicarboxy)phenoxy]benzene dianhydride, 1,4-bis-[4-(1,2-dicarboxy)phenoxy]benzene dianhydride, 4,4'-bis-[4-(1,2-di carboxy)phenoxy]biphenyl dianhydride, 4,4'-bis-[4-(1,2-dicarboxy)phenoxy]benzophenone dianhydride, bis-{4-[4-(1,2-dicarboxy)phenoxy]phenyl}sulfone dianhydride, 2,2-bis-{4-[4-(1,2-dicarboxy)phenoxy]phenyl}sulfone dianhydride and 2,2-Bis-{4-[4-(1,2-dicarboxy)phenoxy]phenyl}-1,1,1,3,3,3-hexafluoropropane dianhydride.

The aromatic polyimide copolymer, which consists of 99 to 1 mol% of the basic skeleton of repeating structural units of formula (1), (2), (3), (4) or (5) and 1 to 99 mol% of the basic skeleton of repeating structural units of formula (6), is prepared from the corresponding monomers above. In addition to the required aromatic diamine and aromatic dicarboxylic acid dianhydride, other aromatic diamines or aromatic tetracarboxylic acid dianhydrides can be used in combination as long as this does not adversely affect the good properties of the resulting aromatic polyimide homo- and copolymer.

The invention also includes capped polyimide having at its polymer chain end an aromatic ring which is unsubstituted or substituted with a radical which does not react with amines and dicarboxylic anhydrides.

The invention further includes a composition of these polyimides. Compositions in some cases have better properties than the polyimides themselves.

The polyimide having at its polymer chain terminal an aromatic ring which is unsubstituted or substituted with a group which does not react with amines and/or dicarboxylic anhydrides can be obtained by reacting the terminal group of the polymer chain derived from aromatic amine of the above formula (7) and tetracarboxylic dianhydride primarily having the above formula (8) with aromatic dicarboxylic anhydride of the formula (9)

wherein Z is a divalent radical having 6 to 15 carbon atoms selected from the group consisting of monoaromatic radicals, condensed polyaromatic radicals and non-condensed aromatic radicals linked to one another via a direct bond or a bridging element and/or with aromatic monoamine of formula (10)

Z₁-NH₂ (10)

wherein Z₁ is a monovalent radical having 6 to 15 carbon atoms selected from the group consisting of monoaromatic radicals, fused polyaromatic radicals and non-fused aromatic radicals linked to one another via a direct bond or a bridging element, preferably capped with phthalic anhydride and/or aniline.

The polyimide can be prepared by reacting an aromatic diamine component with aromatic tetracarboxylic dianhydride in the presence of aromatic dicarboxylic anhydride of formula (9) and/or aromatic monoamine of formula (10) and then thermally or chemically imidizing the resulting polyamic acid.

Examples of aromatic dicarboxylic anhydrides of the formula (9) are phthalic anhydride, 2,3-benzophenonedicarboxylic anhydride, 3,4-benzophenonedicarboxylic anhydride, 2,3-dicarboxyphenylphenyl ether anhydride, 3,4-dicarboxyphenylphenyl ether anhydride, 2,3-biphenyldicarboxylic anhydride, 3,4-biphenyldicarboxylic anhydride, 2,3-dicarboxyphenylphenylsulfone anhydride, 3,4-dicarboxyphenylphenylsulfone anhydride, 2,3-dicarboxyphenylphenyl sulfide anhydride, 3,4-dicarboxyphenylphenyl sulfide anhydride, 1,2-naphthalenedicarboxylic anhydride, 2,3-naphthalenedicarboxylic anhydride, 1,8-naphthalenedicarboxylic anhydride, 1,2-anthracene dicarboxylic anhydride, 2,3-anthracene dicarboxylic anhydride and 1,9-anthracene dicarboxylic anhydride.

These dicarboxylic acid anhydrides can be substituted with a radical that does not react with amines and dicarboxylic acid anhydrides.

Phthalic anhydride is most preferred in view of the properties of the resulting polyimide and practical use. Polyimide prepared in the presence of phthalic anhydride has excellent thermal stability at high temperatures and is very useful as a material for space and aeronautical instruments and electrical and electronic devices. Part of phthalic anhydride can be replaced by other dicarboxylic anhydrides within a range where the good properties of polyimide are not impaired.

The amount of dicarboxylic anhydride is suitably 0.001 to 1.0 mol per mol of aromatic diamine of formula (7). If the amount is less than 0.01 mol, the viscosity increases in high-temperature processing. On the other hand, an amount exceeding 1.0 mol deteriorates the mechanical properties of the product. Therefore, the preferred amount is in the range of 0.01 to 0.5 mol.

The aromatic monoamines that can be used include, for example, aniline, o-toluidine, m-toluidine, p-toluidine, 2,3-xylidine, 2,6-xylidine, 3,4-xylidine, 3,5-xylidine, o-chloroaniline, m-chloroaniline, p-chloroaniline, o-bromoaniline, m-bromoaniline, p-bromoaniline, m-nitroaniline, p-nitroaniline, o-aminophenol, m-aminophenol, p-aminophenol, o-anisidine, m-anisidine, p-anisidine, o-phenetidine, m-phenetidine, p-phenetidine, o-aminobenzaldehyde, m-aminobenzaldehyde, p-aminobenzaldehyde, o-aminobenzonitrile, m-aminobenzonitrile, p-aminobenzonitrile, 2-aminobiphenyl, 3-aminobiphenyl, 4-aminobiphenyl, 2-aminophenylphenyl ether, 3-aminophenylphenyl ether, 4-aminophenylphenyl ether, 2-aminobenzophenone, 3-aminobenzophenone, 4-aminobenzophenone, 2-aminophenylphenyl sulfide, 3-aminophenylphenyl sulfide, 4-aminophenylphenyl sulfide, 2-Aminophenylphenylsulfone, 3-aminophenylphenylsulfone, 4-aminophenylphenylsulfone, α-naphthylamine, β-naphthylamine, 1-amino-2-naphthol, 2-amino-1-naphthol, 4-amino-1-naphthol, 5-amino-1-naphthol, 5-amino-2-naphthol, 7-amino-2-naphthol, 8-amino-1-naphthol, 8-amino-2-naphthol, 1-aminoanthracene, 2-aminoanthracene and 9-aminoanthracene. These aromatic monoamines may be substituted with a residue that does not react with amines and dicarboxylic anhydrides.

The amount of aromatic monoamine is suitably 0.001 to 1.0 mol per mol of the aromatic tetracarboxylic dianhydride component. An amount of less than 0.001 mol leads to an increase in viscosity in high-temperature processing and causes a reduction in processability. On the other hand, an amount of more than 1.0 mol reduces the mechanical strength of the product. Therefore, the preferred range is 0.001 to 0.5 mol.

Therefore, the production of capped polyimide according to the present invention, having a terminal unsubstituted or substituted aromatic ring, is carried out using 0.9 to 1.0 mole of aromatic diamine and 0.001 to 1.0 mole of dicarboxylic anhydride or aromatic monoamine per mole of tetracarboxylic dianhydride.

In polyimide production, the molar ratio between tetracarboxylic dianhydride and aromatic diamine is usually regulated in order to adjust the molecular weight of the polyimide formed. In order to obtain polyimide with good melt flowability in the process of the invention, the molar ratio between aromatic diamine and tetracarboxylic dianhydride is suitably in the range of 0.9 to 1.0.

Any method for producing polyimide, including known methods, can be used to produce polyimide according to the present invention. A particularly The preferred method is to carry out the reaction in an organic solvent.

Examples of solvents that can be used for the reaction are N,N- dimethylformamide, N,N-dimethylacetamide, N,N-diethylacetamide, N, N-dimethylmethoxyacetamide, N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, N-methylcaprolactam, 1,2-dimethoxyethane, bis-(2-methoxyethyl)ether, 1,2-bis-(2-methoxyethoxy)ethane, bis-[2-(2-methoxyethoxy)ethyl]ether, tetrahydrofuran, 1,3-dioxane, 1,4-dioxane, pyridine, picoline, dimethyl sulfoxide, dimethyl sulfone, tetramethylurea, hexamethylphosphoramide, phenol, o-cresol, m-cresol, p-cresol, m-cresylic acid, p-chlorophenol and Anisole. These organic solvents can be used individually or as mixtures.

In the process of the invention, the reaction is carried out by adding aromatic diamine, aromatic tetracarboxylic dianhydride and aromatic dicarboxylic anhydride or aromatic monoamine to the organic solvent according to the following procedures.

(A) After the reaction of aromatic tetracarboxylic dianhydride with aromatic diamine, aromatic dicarboxylic anhydride or aromatic monoamine is added and the reaction is continued.

(B) After the reaction of aromatic diamine with aromatic dicarboxylic anhydride, aromatic tetracarboxylic dianhydride is added and the reaction is continued.

(C) After the reaction of aromatic tetracarboxylic dianhydride with aromatic monoamine, aromatic diamine is added and the reaction is continued.

(D) Aromatic tetracarboxylic dianhydride, aromatic diamine and aromatic dicarboxylic anhydride or aromatic monoamine are added simultaneously, following which reaction takes place.

Any of the above addition methods can be used.

The reaction temperature is usually 250°C or less, preferably 50°C or less. The reaction pressure is not particularly limited. Atmospheric pressure is sufficient to carry out the reaction. The reaction time differs depending on the tetracarboxylic dianhydride, solvent and reaction temperature; usually 4 to 24 hours is sufficient to carry out the reaction.

Furthermore, polyamic acid thus obtained is thermally imidized by heating to 100°C to 400°C or chemically imidized using an imidizing agent such as acetic anhydride to obtain a polyimide having repeating structural units corresponding to those of the polyamic acid.

The desired polyimide can also be prepared, in the case of terminating the polyimide with an aromatic ring, by suspending or dissolving aromatic diamine and aromatic tetracarboxylic dianhydride and additionally aromatic dicarboxylic anhydride and/or aromatic monoamine in an organic solvent and then heating the mixture to carry out simultaneous formation and imidization of the polyamic acid as a polyimide precursor.

Polyamic acids which are precursors for polyimides according to the present invention have an inherent viscosity of 0.01 to 3.0 dl/g in an N,N-dimethylacetamide solution with a concentration of 0.5 g/dl at 35°C. The polyimide according to the invention has an inherent viscosity of 0.01 to 3.0 dl/g in a solvent mixture of 9 parts by weight of p-chlorophenol and 1 part by weight of phenol at a concentration of 0.5 g/dl at 35°C.

The polyimides of the present invention are soluble in generally used solvents. Representative solvents include, for example, halogenated hydrocarbon solvents such as dichloromethane, chloroform, carbon tetrachloride, dichloroethane, trichloroethane, tetrachloroethane, dibromomethane, trifluoromethane, tetrabromomethane, dibromoethane, tribromoethane and tetrabromoethane; amide solvents such as N,N-dimethylacetamide, N,N-dimethylformamide, N,N-diethylacetamide, N,N-dimethoxyacetamide and N-methyl-2-pyrrolidone; phenolic solvents such as phenol, cresol, halogenated cresol and xylenol; and aromatic hydrocarbon solvents such as benzene, toluene and xylene. These solvents can be used individually or as mixtures.

The polyimide varnishes obtained by dissolving polyimides according to the invention in these solvents can be used for heat-resistant clear coats, coatings and sealants.

Furthermore, polyimide films of the present invention can be prepared by casting a varnish of a polyamic acid precursor of the polyimide on a glass plate and heating it for imidization, by hot-pressing the polyimide powder in an intact state to form a film, or by removing by heating an organic solvent from the solution in which the polyimide is dissolved to form a film.

This means that films and powders made of polyimides can be produced using known processes.

In the case of melt processing the polyimides according to the present invention, other thermoplastic resins may be blended in an appropriate amount depending on the application objective, as long as the good properties of the polyimides are not adversely affected.

Thermoplastic resins that can be blended include polyethylene, polypropylene, polycarbonates, polyarylates, polyamides, polysulfones, polyethersulfones, polyetherketones, polyphenylene sulfides, polyamideimides, polyetherimides, modified polyphenylene oxide and other types of polyimides.

Fillers used for conventional resin compositions can be added within a range not affecting the object of the invention. Examples of fillers are graphite, carborundum, silica powder, molybdenum disulfide, fluororesin and other abrasion resistance improvers; glass fibers, carbon fibers and other reinforcing agents; antimony trioxide, magnesium carbonate, calcium carbonate and other flame resistance improvers; clay, mica and other electrical property improvers; asbestos, silica, graphite and other tracking resistance improvers; barium sulfide, silica, calcium metasilicate and other acid resistance improvers; iron powder, zinc powder, aluminum powder, copper powder and other thermal conductivity improvers; and other miscellaneous materials such as glass beads, glass balloons, talc, diatomaceous earth, alumina, silicate balloons, hydrated alumina, metal oxides and colorants.

The invention is illustrated in detail below using examples. However, these examples are not intended to limit the scope of the invention.

example 1

In a four-necked flask equipped with a thermometer, reflux condenser and stirrer were placed 150 g of N,N-dimethylformamide (DMF), 20 g of toluene, 80 g (0.235 mol) of 4,4'-dichloro-3,3'-dinitrobenzophenone, 45.5 g (0.483 mol) of phenol and 39 g (0.282 mol) of potassium carbonate. The mixture was heated to 130°C with stirring and then aged at 130°C for 5 h.

After completion of the reaction, the reaction mixture was cooled to 80ºC and filtered to remove inorganic salts. The filtrate was washed with 60 g of water and cooled to room temperature to crystallize the desired product. The precipitated crystals were filtered and slurried in methanol to obtain 92 g (86% yield) of the desired 3,3'-dinitro-4,4'-diphenoxybenzophenone.

Mp.: 111.0-112.8ºC

'H-NMR ? (CDCl3 , ppm):

7.175 (d, 4H (1)), 7.19 7.69 (m, 6H (2)), 7.57 (d, 2H (3)) 8.06 (dd, 2H (4)), 8.52 (d, 2H (5))

(1) - (5) represents the positions in the following formula:

Elemental analysis (C25 H16 N2 O7 ):

C H N

Calculated (%): 65.79 3.53 6.13

found(%): 65.81 3.43 6.01

Example 2

A reactor equipped with a thermometer, reflux condenser and stirrer was charged with 60 g (0.131 mol) of 3,3'-dinitro-4,4'-diphenoxybenzophenone, 150 g of methyl cellosolve and 3.0 g of 5% Pd/C (50% moisture content) and reacted in a hydrogen atmosphere at 70-80°C for 4 h. After completion of the reaction, the catalyst was filtered off and the filtrate was concentrated under reduced pressure to give 45 g (86% yield) of 3,3'-diamino-4,4'-diphenoxybenzophenone as bright yellow crystals.

Mp.: 153.3-154.0ºC

¹H-NMR ? (CDCl3 , ppm):

4.17 (s, 4H (1)), 6.96 (d, 4H (2)), 7.12 7.63 (m, 6H (3)) 7.21 7.25 (m, 4H (4)), 7.43 (d, 2H (5))

(1) - (5) denotes the positions in the following formula:

Elemental analysis (C25 H20 N2 O3 ):

C H N

Calculated (%): 75.74 5.18 7.07

found(%): 75.62 5.20 7.01

Example 3

A glass reaction vessel equipped with a stirrer, thermometer and reflux condenser was charged with 61.3 g (0.2 mol) of 4-chloro-3,3'-dinitrobenzophenone, 19.7 g (0.21 mol) of phenol, 16.6 g (0.12 mol) of potassium carbonate, 220 g of N,N-dimethylformamide and 15 g of toluene. The mixture was heated to 140°C with stirring and aged at 140°C for 3 h.

After completion of the reaction, the reaction mixture was cooled to 100°C and filtered to remove inorganic salts. The filtrate was mixed with 200 g of water and 50 g of methanol and cooled to room temperature. The precipitated crystals were filtered off and washed with isopropyl alcohol to give 69.1 g (94.8% yield) of 3,3'-dinitro-4-phenoxybenzophenone.

The purity measured by HPLC was 99.7%. The melting point was 135.1-136.0ºC.

The IR spectrum is shown in Fig. 1.

[Second reaction step]

Into a tightly sealed glass reaction vessel equipped with a stirrer, thermometer and reflux condenser were charged 54.6 g (0.15 mol) of the 3,3'-dinitro-4-phenoxy-benzophenone obtained above, 1.1 g of 5% palladium/alumina catalyst (N.E. Chemcat Co.) and 270 g of N,N-dimethylformamide. Hydrogen was introduced into the reaction vessel at a temperature of 40-50°C while stirring, whereby 19.9 l of hydrogen was absorbed in about 8 h.

After completion of the reaction, the reaction mixture was filtered at the same temperature to remove the catalyst. The filtrate was concentrated under reduced pressure to give 37.0 g (81.2% yield) of 3,3'-diamino-4-phenoxybenzophenone as light yellow crystals.

The purity was 99.1% according to HPLC. The melting point was 111.6-113.0ºC. The IR spectrum is shown in Fig. 2.

Elemental analysis (C19 H16 N2 O2 ):

C H N

Calculated (%): 75.0 5.3 9.2

found(%): 73.9 5.6 10.1

Example 4 [First reaction step]

Into a glass reaction vessel equipped with a stirrer, thermometer and reflux condenser were charged 61.3 g (0.2 mol) of 4-chloro-3,4'-dinitrobenzophenone, 35.7 g (0.21 mol) of p-phenylphenol, 16.6 g (0.12 mol) of potassium carbonate and 235 g of N,N-dimethylformamide. The mixture was heated to 140°C with stirring and aged at 140-150°C for 1.5 h.

After completion of the reaction, the reaction mixture was cooled to 100°C and filtered to remove inorganic salts. The filtrate was mixed with water and cooled to room temperature. The precipitated crystals were filtered off and washed with isopropyl alcohol to give 73.8 g (83.8% yield) of 3,4'-dinitro-4-biphenoxybenzophenone.

The purity measured by HPLC was 99.5%. The melting point was 139.6-140.6ºC.

The IR spectrum is shown in Fig. 3

[Second reaction step]

In a tightly sealed glass reaction vessel equipped with a stirrer, thermometer and reflux condenser were charged 44.0 g (0.1 mol) of the above 3,4t-dinitro-4-biphenoxybenzophenone, 3.5 g of 5% palladium/alumina catalyst (N.E. Chemcat Co.) and 220 g of N,N-dimethylformamide. Hydrogen was introduced into the reaction vessel at a temperature of 40-50°C with stirring, whereby 12.2 L of hydrogen was absorbed in about 9 h.

After completion of the reaction, the reaction mixture was filtered at the same temperature to remove the catalyst. The filtrate was mixed with 70 g of water to give 31.8 g (83.6% yield) of 3,4'-diamino-4-biphenoxybenzophenone as light brown crystals.

The purity was 99.1% according to HPLC. The melting point was 244.8-245.1ºC. The IR spectrum is shown in Fig. 4.

Elemental analysis (C25 H20 N2 O2 ):

C H N

Calculated (%): 78.9 5.3 7.4

found(%): 78.0 5.4 7.9

Example 5 [First reaction step]

Into a glass reaction vessel equipped with a stirrer, thermometer and reflux condenser were charged 89.0 g (0.2 mol) of 1,3-bis(3-nitro-4-chlorobenzoyl)benzene, 59.3 g (0.63 mol) of phenol, 33.2 g (0.24 mol) of potassium carbonate and 450 g of N,N-dimethylformamide. The mixture was heated to 110°C with stirring and aged at 110-120°C for 1.5 h.

After completion of the reaction, the reaction mixture was filtered at the same temperature to remove inorganic salts. The filtrate was cooled to 80°C, 225 g of water was added dropwise, and the mixture was cooled to room temperature. The precipitated crystals were filtered off and recrystallized from 2-methoxy alcohol to give 103.7 g (92.5% yield) of 1,3-bis-(3-nitro-4-phenoxybenzoyl)benzene.

The purity was 99.8% according to HPLC. The melting point was 162.3-163.8ºC. The IR spectrum is shown in Fig. 5.

[Second reaction step]

In a tightly sealed glass reaction vessel equipped with a stirrer, thermometer and reflux condenser were charged 56.1 g (0.1 mol) of the above 1,3-bis-(3-nitro-4-phenoxybenzoyl)benzene, 2.0 g of 5% palladium/alumina catalyst (NE Chemcat Co.) and 200 g of N,N-dimethylformamide. Hydrogen was introduced into the reaction vessel at a temperature of 25°C, whereby 12.2 l of hydrogen was absorbed within about 20 h. became.

After completion of the reaction, the reaction mixture was filtered at the same temperature to remove the catalyst. The filtrate was mixed with 150 g of water to give light brown crystals. The crystals were recrystallized from toluene to give 39.1 g (78.1% yield) of 1,3-bis-(3-amino-4-phenoxybenzoyl)benzene. The purity was 98.8% by HPLC. The melting point was 128-129.0 °C.

The IR spectrum is shown in Fig. 6.

Elemental analysis:

C H N

Calculated (%): 76.8 4.8 5.6

found(%): 74.0 4.9 6.1

Example 6 [First reaction step]

Into a glass reaction vessel equipped with a stirrer, thermometer and reflux condenser were charged 44.5 g (0.1 mol) of 1,3-bis-(3-nitro-4-chlorobenzoyl)benzene, 35.7 g (0.21 mol) of p-phenylphenol, 16.6 g (0.12 mol) of potassium carbonate and 220 g of N,N-dimethylformamide. The mixture was heated to 90°C with stirring and aged at this temperature for 3 h.

After completion of the reaction, the reaction mixture was filtered at the same temperature to remove inorganic salts. The filtrate was mixed with water. The precipitated crystals were filtered off and recrystallized from toluene to obtain 64.7 g (90.5% yield) of 1,3-bis(3-nitro-4-phenoxybenzoyl)benzene.

The purity measured by HPLC was 99.2%. The melting point was 190.6-191.6ºC.

[Second reaction step]

In a tightly sealed glass reaction vessel equipped with a stirrer, thermometer and reflux condenser, 35.7 g (0.05 mol) of the above 1,3-bis-(3-nitro-4-biphenoxybenzoyl)benzene, 33.5 g (0.06 mol) of iron powder and 400 g of a 90% aqueous 2-methoxyethanol solution were charged and heated to 50°C. A solution containing 1.1 g of 35% hydrochloric acid in 30 g of 90% 2-methoxyethanol was added dropwise to the mixture over 2 hours and further stirred at 50-60°C for 15 hours. After completion of the reaction, the reaction mixture was mixed with 250 g of water and cooled to 25°C and filtered. The residue was dissolved in 230 g of N,N-dimethylformamide at 110ºC and filtered. The filtrate was mixed with water and cooled to 25ºC. The precipitated crystals were recrystallized from toluene to give 26.2 g (80.2% yield) of 1,3-bis-(3-amino-4-biphenoxybenzoyl)benzene. The purity was 98.8% by HPLC. The melting point was 186.7-187.8ºC.

The IR spectrum is shown in Fig. 7.

Elemental analysis:

C H N

Calculated (%): 81.0 4.9 4.3

found(%): 79.9 5.0 4.5

Example 8 [First reaction step]

In a glass reaction vessel equipped with a stirrer, thermometer and reflux condenser were charged 500 g of tetrahydrofuran and 100 g (0.293 mol) of 4,4'-dichloro-3,3'-dinitrobenzophenone. The mixture was cooled to 0°C with stirring and then 34.8 g of sodium methoxide (28% solution in methanol, 0.645 mol) was added dropwise to the mixture over 2 h. The mixture was then aged at 20°C for 3 h.

After completion of the reaction, the reaction mixture was filtered at the same temperature to remove insoluble matter. The filtrate was heated to 60°C, mixed with 990 ml of water and cooled to room temperature to crystallize the desired product.

The above insoluble product obtained by filtration was slurried in 300 g of water to give the desired product.

These products obtained by the above procedures were combined and recrystallized from 1,2-dichloroethane (EDC) to give 84 g (86% yield) of 3,3'-dinitro-4,4'-dimethoxybenzophenone. Melting point was 189.0-189.9°C.

¹H-NMR ? (DMSO-d6 , ppm):

4.05 (S, 6H(1)), 7.53 (d, 2H(2)), 8.06(dd, 2H(3)), 8.26 (d, 2H(4))

(1) - (4) denote the positions in the following formula:

Elemental analysis (C15 H12 N2 O7 ):

C H N

Calculated (%): 54.2 3.6 8.4

found(%): 53.6 3.8 8.6

[Second reaction step]

In a tightly sealed glass reaction vessel equipped with a stirrer, thermometer and reflux condenser, 84 g (0.253 mol) of the above 3,3'-dinitro-4,4'-dimethoxybenzophenone, 420 g of N,N-dimethylformamide and 2.52 g of 5% palladium/alumina catalyst (NE. Chemcat Co.) were charged and reacted under hydrogen atmosphere at 45-55°C for 3 hours. After completion of the reaction, the Catalyst was filtered off. The filtrate was heated to 80 °C, and then 1,275 g of water was added and cooled to room temperature to crystallize the desired product. The precipitated crystals were filtered off and recrystallized from isopropyl alcohol (IPA) to give 27 g (39% yield) of 3,3'-diamino-4,4'-dimethoxybenzophenone as light yellow crystals.

The melting point was 128.2-129.2ºC.

The IR spectrum is shown in Fig. 8.

Elemental analysis (C15 H16 N2 O3 ):

C H N

Calculated (%): 66.2 5.9 10.3

found (%): 65.9 5.8 10.1

The polyimide properties in the examples below were measured using the following methods:

Tg, Tc and Tm: Measured in air by DTG with a DSC-4019 of the Shimadzu DT-40 series.

Temperature at 5% weight loss: Measured using DTA-Tg (Shimazu DT-40 series, DSC-40M) in air.

Melt viscosity: Measured with a Shimadzu Koka type flow tester (CFT-500A) under 100 kg load.

Melt flow initiation temperature: Measured with a Shimadzu Koka flow tester (SFT-500A) under 100 kg load with a temperature increase rate of 5ºC/min.

Adhesion test (lap shear strength): Pastes were prepared by suspending polyimide powder in ethanol, respectively, and applied to two cold-rolled steel plates (JIS G-3141, SPCC, SD) measuring 1.6 x 25 x 100 mm. The coated plates were hot-pressed under a pressure of 21 kg/cm2 at a temperature of 280ºC, 300ºC, and 350ºC, respectively. The lap shear strength of the adhered samples were measured according to JIS K-6848.

Intrinsic viscosity: The polyamide acids were dissolved in N,N-dimethylformamide. The polyimides were dissolved in a solvent mixture of p-chlorophenol/phenol (weight ratio: 9:1). The viscosity was measured at 35ºC at a concentration of 0.5 g sample/100 ml solvent.

Example 8

Into a reaction vessel equipped with a stirrer, reflux condenser and nitrogen inlet tube were charged 39.65 g (0.1 mol) of 3,3'-diamino-4,4'-diphenoxybenzophenone, 31.58 g (0.098 mol) of 3,3',4,4'-benzophenonetetracarboxylic dianhydride, 0.592 g (0.04 mol) of phthalic anhydride, 1.40 g of γ-picoline and 284.92 g of m-cresol. The mixture was heated to 150°C with stirring in a nitrogen atmosphere and kept at this temperature for 4 h, distilling off about 3.6 ml of water.

After completion of the reaction, the reaction mixture was cooled to room temperature and poured into about 2 L of methyl ethyl ketone. The precipitated powder was filtered off, washed with methyl ethyl ketone and dried at 50°C for 24 hours in air and then at 230°C for 4 hours under nitrogen atmosphere to give 66.25 g (97.1% yield) of polyimide powder.

The polyimide powder had an inherent viscosity of 0.56 dl/g, a glass transition temperature of 246ºC and a 5% weight loss temperature of 524ºC.

The X-ray diffraction pattern (XRD) of the polyimide powder indicated amorphous form.

The IR absorption spectrum of the polyimide powder is shown in Fig. 9. The spectrum atlas clearly showed characteristic absorption bands of imide at about 1,780 cm⁻¹ and 1,720 cm⁻¹.

The elemental analysis of the polyimide powder yielded the following results:

C H N

Calculated (%): 73.89 3.25 4.10

found (%): 73.59 3.19 4.15

The melt flow initiation temperature measured with a Koka flow tester was 325ºC. The processing stability of the polyimide powder was also measured by changing the residence time in the cylinder of the flow tester. The results at 380ºC under 100 kg load are shown in Fig. 10.

The melt viscosity is almost constant, although the residence time in the cylinder is longer, and indicates good stability during processing of the polyimide powder.

An adhesion test (lap shear strength measurement) was conducted using the polyimide powder. The lap shear strength was 152 kg/cm² at a pressing temperature of 280ºC, 230 kg/cm² at 300ºC and 332 kg/cm² at 350ºC, respectively.

Furthermore, the solubility of the polyimide powder was investigated at room temperature. The polyimide powder dissolved in a concentration of 20 wt.% in chloroform, dichloromethane, carbon tetrachloride, N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone and o-, m- and p-cresol.

Comparison example 1

In the same apparatus as in Example 7, 21.23 g (0.1 mol) of 3,3'-diaminobenzophenone, 31.58 g (0.098 mol) of 3,3',4,4'-benzophenonetetracarboxylic dianhydride, 0.592 g (0.004 mol) of phthalic anhydride, 1.40 g of γ-picoline and 211 g of m-cresol were charged. The mixture was heated to 150°C with stirring in a nitrogen atmosphere and reacted at that temperature for 4 hours, during which about 3.6 ml of water was distilled off.

After completion of the reaction, the reaction mixture was cooled to 110ºC and 200 g of toluene was added dropwise to precipitate polyimide powder. The powder was filtered off, washed with 300 g of toluene and dried at 50 °C for 24 h in air and then at 250 °C for 4 h under nitrogen atmosphere to give 47.68 g (95.7% yield) of polyimide powder.

The polyimide powder thus obtained had an inherent viscosity of 0.55 dl/g, a glass transition temperature of 243°C, a melting point of 315°C and a 5% weight loss temperature of 537°C. The X-ray diffraction pattern of the polyimide powder indicated crystalline polyimide.

Furthermore, the polyimide powder had a melt flow initiation temperature of 335ºC and a lap shear strength of 0 kg/cm² at 280ºC, 21 kg/cm² at 300ºC and 328 kg/cm² at 350ºC, respectively.

The polyimide powder was only partially soluble in cresol at a concentration of 10 wt.% at room temperature and was largely insoluble in other organic solvents listed in Example 9.

Examples 9 to 21, Comparative Examples 2 and 3

Various types of polyimide powders were prepared from the diamine components shown in Table 1 using the same procedures as in Example 8.

Table 1 shows the diamine components, the acid anhydride components, the yield, basic properties such as inherent viscosity and Tg, and lap shear strength of these examples together with the results of Example 8 and Comparative Example 1.

Table 2 shows the results of the polyimides of these examples when dissolved in various organic solvents together with the results of Example 8 and Comparative Example 1.

Example 22

In a flask equipped with a stirrer, reflux condenser and nitrogen inlet tube, 39.65 g (0.1 mol) of 3,3'-diamino-4,4'-diphenoxybenzophenone and 287.5 g of N,N- dimethylacetamide were charged, and 32.22 g (0.1 mol) of 3,3',4,4'-benzophenonetetracarboxylic dianhydride were added portionwise under nitrogen atmosphere and carefully to prevent a rise in the temperature of the solution.

Then, the mixture was stirred at room temperature for about 30 hours. The polyamic acid thus obtained had an inherent viscosity of 0.74 dl/g. A portion of the polyimide solution was poured onto a glass plate and heated at 100°C, 200°C, and 300°C for 1 hour to obtain a film.

The polyimide film thus obtained had a Tg of 250°C, a tensile strength of 11.35 kg/cm2, a tensile elongation of 3.2% and a tensile elastic modulus of 384 kg/cm2. The polyimide film dissolved in all of the organic solvents listed in Example 8 at a concentration of 20 wt%.

Examples 23 to 30, Comparative Examples 4 and 5

Various types of polyimide films were prepared from the diamine components shown in Table 3 using the same procedures as in Example 22.

Table 3 shows the diamine components, the acid anhydride components, the inherent viscosity of the polyamic acids, the Tg and mechanical properties of these films together with the results of Example 8.

Table 3 also shows the results of dissolving these films at a concentration of 20 wt.% in chloroform, N,N-dimethylacetamide and m-cresol. Table 1

Remarks:

*1: Temperature at 5% weight loss

*2: Unit: kg/mm²

*3: 3,3'-diamino-4,4'-diphenoxybenzophenone

*4: 3,3'-diamino-4-phenoxybenzophenone

*5: 3,4'-diamino-4-phenoxybenzophenone

*6: 3,3'-diamino-4,4'-dibiphenoxybenzophenone

*7: 3,3'-diamino-4-biphenoxybenzophenone

*8: 3,4'-diamino-4-biphenoxybenzophenone

*9:3,3',4,4'-Benzophenonetetracarboxylic acid hydride Table 1 (continued)

*10: Pyromellitic acid dianhydride

*11: 3,3',4,4'-Biphenyltetracarboxylic dianhydride

*12: 1,1,1,3,3,3-hexafluoro-2,2-bis-(dicarboxyphenyl)dianhydride

*13: 2,3,6,7-Naphthalenetetracarboxylic dianhydride

*14: 3,3'-diamino-4,4'-dimethoxybenzophenone Table 2

Notes: O: soluble

X: insoluble Table 2 (continued)

Notes: O: soluble

X: insoluble Table 3

Remarks:

*1: Ts: Tensile strength

El: tensile strain

Tm: Tensile modulus of elasticity

*2: N,N-Dimethylacetamide

*3: 3,3'-diamino-4,4'-diphenoxybenzopheneon

*4: 3,3'-diamino-4-phenoxybenzophenone

*5: 3,4'-diamino-4-phenoxybenzophenone

*6: 3,3'-diamino-4,4'-dibiphenoxybenzophenone

*7: 3,3'-diamino-4-biphenoxybenzophenone

*8: 3,4'-diamino-4-biphenoxybenzophenone

*9: 3,3'4,4'-Benzophenonetetracarboxylic acid dianhydride

*10: O: soluble, X: insoluble

Example 31

Into a reaction vessel equipped with a stirrer, reflux condenser and nitrogen inlet tube were charged 25.03 g (0.05 mol) of 1,3-bis-(3-amino-4-phenoxybenzoyl)benzene, 15.47 g (0.048 mol) of 3,3',4,4'-benzophenonetetracarboxylic dianhydride, 0.592 g (0.004 mol) of phthalic anhydride, 0.70 g of γ-picoline and 162.0 g of m-cresol. The mixture was heated to 150°C with stirring in a nitrogen atmosphere and then reacted at this temperature for 4 hours, during which about 1.8 ml of water was distilled off.

After completion of the reaction, the reaction mixture was cooled to room temperature and poured into about 1 L of methyl ethyl ketone. Precipitated powder was filtered off, washed with methyl ethyl ketone and dried at 50°C for 24 hours in air and then at 220°C for 4 hours under nitrogen atmosphere to give 37.88 g (96.4% yield) of polyimide powder.

The polyimide powder had an inherent viscosity of 0.51 dl/g, a glass transition temperature of 233ºC and a 5% weight loss temperature of 522ºC.

The X-ray diffraction pattern (XRD) of the polyimide powder showed amorphous form.

The IR absorption spectrum of the polyimide powder is shown in Fig. 11. The spectrum atlas clearly showed characteristic absorption bands of imide at about 1,780 cm⁻¹ and 1.72 cm⁻¹.

The elemental analysis of the polyimide powder gave the following results:

Calculated (%): 74.80 3.34 3.56

found (%): 73.55 3.38 3.67

The melt flow initiation temperature measured with a Koka flow tester was 330ºC. The processing stability of the polyimide powder was also measured, by changing the residence time in the flow tester cylinder. The results at 380ºC under 100 kg load are shown in Fig. 12.

The melt viscosity is almost constant, although the residence time in the cylinder is longer, and indicates good stability during processing of the polyimide powder.

Furthermore, the solubility of the polyimide powder was investigated at room temperature. The polyimide powder dissolved in a concentration of 20 wt.% in chloroform, dichloromethane, carbon tetrachloride, 1,1,2-trichloroethane, N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone and o-, m- and p-cresol.

Comparison example 6

Into the same apparatus as in Example 31 were charged 15.82 g (0.05 mol) of 1,3-(3-aminobenzoyl)benzene, 15.47 g (0.048 mol) of 3,3',4,4'-benzophenonetetracarboxylic dianhydride, 0.592 g (0.004 mol) of phthalic anhydride, 0.70 g of γ-picoline and 125.2 g of m-cresol. The mixture was heated to 150°C with stirring in a nitrogen atmosphere and reacted at that temperature for 4 hours, during which about 1.8 ml of water was distilled off.

After completion of the reaction, the reaction mixture was worked up according to the same procedure as in Example 31.

Thus, 28.96 g (96.3% yield) of polyimide powder was obtained, which had an inherent viscosity of 0.49 dl/g and a 5% weight loss temperature of 529 °C.

Furthermore, the polyimide powder had an initial flow temperature of 325ºC.

The polyimide powder was only partially soluble in cresol at a concentration of 20 wt.% at room temperature and was largely insoluble in other organic solvents as shown in Example 31.

Examples 32 to 34 and Comparative Example 7

Various kinds of polyimide powders were prepared from the diamine components shown in Table 4 using the same procedures as in Example 31.

Table 4 shows the diamine components, the acid anhydride components, the yield, basic properties such as inherent viscosity and Tg of these examples, along with the results of Example 31 and Comparative Example 6.

Table 5 further shows the results of dissolving the polyimides of these examples in various organic solvents together with the results of Example 31 and Comparative Example 6.

Example 35

In a flask equipped with a stirrer, reflux condenser and nitrogen inlet tube, 25.03 g (0.05 mol) of 1,3-bis-(3-amino-4-phenoxybenzoyl)benzene and 164.6 g N,N-dimethylacetamide were charged, and 16.11 g (0.05 mol) of 3,3',4,4'-benzophenonetetracarboxylic dianhydride were added portionwise under nitrogen atmosphere and carefully to prevent a rise in the temperature of the solution.

Then, the mixture was stirred at room temperature for about 30 hours. The polyamic acid thus obtained had an inherent viscosity of 0.92 dl/g. A portion of the polyimide solution was poured onto a glass plate and heated successively at 100°C, 200°C, and 300°C for 1 hour to obtain a film.

The polyimide film thus obtained had a Tg of 231°C, a tensile strength of 11.70 kg/cm2, a tensile elongation of 3.9% and a tensile elastic modulus of 336 kg/cm2. The polyimide film dissolved in all of the organic solvents listed in Example 31 at a concentration of 20 wt%.

Example 36 and Comparative Example 8

Various types of polyimide films were prepared from the diamine components shown in Table 6 using the same procedures as in Example 35.

Table 6 shows the diamine components, the acid anhydride components, the inherent viscosity of the polyamic acids, the Tg and the mechanical properties of these films together with the results of Example 35.

Table 6 also illustrates the results of dissolving these films at a concentration of 20 wt.% in chloroform, N,N-dimethylacetamide and m-cresol. Table 4

Remarks:

*1: Temperature at 5% weight loss

*2: 1,3-Bis-(3-amino-4-phenoxybenzoyl)benzene

*3: 1,3-Bis-(3-amino-4-biphenoxybenzoyl)benzene

*4: 1,3-bis-(3-aminobenzoyl)benzene

*5: 3,3'4,4'Benzophenonetetracarboxylic acid dianhydride

*6: Pyromellitic dianhydride Table 5

Remarks:

O: soluble

X: insoluble Table 6

Remarks:

*1: Ts: Tensile strength

El: tensile strain

Tm: Tensile modulus of elasticity

*2: N,N-Dimethylacetamide

*3: 1,3-Bis-(3-amino-4-phenoxybenzoyl)benzene

*4: 1,3-Bis-(3-amino-4-biphenoxybenzoyl)benzene

*5: 1,3-bis-(3-aminobenzoyl)benzene

*6: 3,3'4,4'-Benzophenonetetracarboxylic acid dianhydride

*7: O: soluble, X: insoluble

Example 37

Into a reaction vessel equipped with a stirrer, reflux condenser and nitrogen inlet tube were charged 35.69 g (0.09 mol) of 3,3'-diamino-4,4'-diphenoxybenzophenone, 2.13 g (0.01 mol) of 3,3'-diaminobenzophenone, 31.58 g (0.098 mol) of 3,3',4,4'-benzophenonetetracarboxylic dianhydride, 0.592 g (0.0045 mol) of phthalic anhydride, 1.40 g of γ-picoline and 284.82 g of m-cresol. The mixture was heated to 150°C with stirring in a nitrogen atmosphere and then reacted at that temperature for 4 hours, during which about 3.6 ml of water was distilled off.

After completion of the reaction, the reaction mixture was cooled to room temperature and poured into about 2 L of methyl ethyl ketone.

Precipitated powder was filtered off, washed with methyl ethyl ketone, and dried at 50 °C for 25 h in air and then at 230 °C for 4 h under nitrogen atmosphere to give 65.18 g (98.0% yield) of polyimide powder.

The polyimide powder thus obtained had an inherent viscosity of 0.55 dl/g, a glass transition temperature of 244°C and a 5% weight loss temperature of 520°C.

The X-ray diffraction pattern (XRD) of the polyimide powder showed amorphous form.

The flow initiation temperature of the polyimide measured with a Koka flow tester was 325ºC.

In an adhesion test, the polyimide powder exhibited a lap shear strength of 152 kg/cm² at a pressing temperature of 280ºC, 230 kg/cm² at 300ºC and 332 kg/cm² at 350ºC.

Furthermore, the solubility of the polyimide powder was investigated at room temperature. The polyimide powder dissolved in a concentration of 20 wt.% in chloroform, Dichloromethane, carbon tetrachloride, N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone and o-, m- and p-cresol.

Examples 38 to 40

Using the same procedures as in Example 37, various kinds of polyimide powders having the composition ratio shown in Table 7 were prepared. The same evaluation as in Example 37 was carried out. The results are shown in Table 7 together with the results of Example 37. The results of the solubility test are shown in Table 8. Table 7

Remarks:

*1: 3,3'-diamino-4,4'diphenoxybenzophenone

*2: 3,3'-Diaminobenzophenone

*3: 3,3'4,4'-benzophenonetetracarboxylic acid dianhydride

*4: Temperature at 5% weight loss Table 8

Notes: O: soluble

X: insoluble

Examples 41 to 61

Using the same procedures as in Example 37, various types of copolyimides were prepared from different diamine components and different tetracarboxylic acid dianhydrides as shown in Tables 9 and 12.

The same evaluation was carried out as in Example 37. The results are shown in Tables 10 and 13. The results of the solubility test are shown in Tables 11 and 14.

Example 62

In a container, 3 kg of polyimide powder obtained by the same method as in Example 8, 3 kg of polyethersulfone VICTREX 4100G (trademark of I.C.I. Ltd.) and 54 kg of m-cresol were charged and mixed at room temperature for 24 hours to obtain a polymer solution. To the polymer solution was added 100 kg of methanol with vigorous stirring.

Precipitated polymer powder was filtered off, washed with methanol and dried at 150°C for 8 hours in a nitrogen atmosphere. The polyimide powder thus obtained was pelleted by melt extrusion at 380°C using a single screw extruder with a bore diameter of 30 mm.

The pellets thus obtained were injection molded at a cylinder temperature of 370-380ºC, an injection pressure of 500 kg/cm² and a mold temperature of 180ºC to obtain tensile test specimens. The tensile test was carried out according to ASTM D-638. The results are shown in Table 15. Table 9

Notes: The abbreviations in Table 9 are the same as in Tables 1 and 4 Table 10

Note: *1: Temperature at 5% weight loss Table 11

Notes: O: soluble

X: insoluble Table 12

Notes: *1: 4,4'-Diaminodiphenyl ether

*2: 4,4'-bis-(3-aminophenoxy)biphenyl

*3: 1,3-bis-(3-aminophenoxy)benzene

The remaining abbreviations correspond to those in Table 1 TABLE 13

Note: The abbreviations in Table 9 correspond to those in Tables 1 and 4 TABLE 14

Notes: O: soluble

X: insoluble

Examples 63 - 67

Blends were prepared as shown in Table 15 using the same procedures as described in Example 62.

The evaluation was carried out according to the same procedures as described in Example 62. The results are presented in Table 15 together with Example 62.

Comparison example 9

A mixture of 3 kg of the polyimide powder obtained by the same method as in Example 8 and 3 kg of the polyethersulfone powder used in Example 62 was prepared by mixing these two materials as they were. The mixture was pelletized by extrusion as described in Example 62. The pellets thus obtained were re-pelletized by melt-kneading with an extruder and injection-molded to obtain tensile test specimens. The tensile properties were tested by the same methods as described in Example 62, and the results are shown in Table 15.

Comparison example 10 and 11

Blends were prepared as shown in Table 15 following the same procedures as in Comparative Example 9. The properties of the blends were evaluated and the results are shown in Table 15. TABLE 15

Notes: *1 ULTEM T-1000 (brand name of G E CO.)

*2 Tensile strength

*3 Tensile elongation

Claims (26)

1. A polyimide comprising a required structural unit consisting of one or more repeating structural units of the formula (1): where m and n are each an integer of 0 or 1 and R wherein R₁, R₂, R₃ and R₄ are each a hydrogen atom, a halogen atom, alkyl having 1 to 8 carbon atoms, aryl, alkenyl, aralkyl or alkoxy having 1 to 5 carbon atoms; R₅, R₆ and R₇ are each a hydrogen atom, alkyl having 1 to 8 carbon atoms, aryl, alkenyl, aralkyl or ω-alkyloxyoligo(alkyleneoxy)alkyl having 1 to 10 carbon atoms and 1 to 3 oxygen atoms; and Ar is a tetravalent radical having 2 to 27 carbon atoms selected from the group consisting of aliphatic, alicyclic, monoaromatic, condensed polyaromatic and non-condensed aromatic radicals which are linked to one another via a direct bond or via a bridging element, wherein the polyimide optionally has an aromatic ring at its polymer chain end which is unsubstituted or substituted with a radical which does not react with amines and/or dicarboxylic anhydrides. 2. Polyimide according to claim 1, wherein the polyimide having repeating structural units of the formula (1) is derived from a precursor polyamic acid having an inherent viscosity of 0.01 to 3.0 dl/g in a dimethylacetamide solution having a concentration of 0.5 g/dl at 35°C. 3. Polyimide according to claim 1, wherein the polyimide having repeating structural units of the formula (1) has an inherent viscosity of 0.01 to 3.0 dl/g in a solvent mixture consisting of 9 parts by weight of p-chlorophenol and 1 part by weight of phenol at a concentration of 0.5 g/dl at 35°C. 4. A polyimide comprising a required structural unit consisting of one or more repeating structural units of the formula (2): wherein m and n are each an integer of 0 or 1, R8 is a hydrogen atom, a halogen atom, alkyl having 1 to 4 carbon atoms, alkoxy or phenyl and Ar is a tetravalent radical having 2 to 27 carbon atoms selected from the group consisting of aliphatic, alicyclic, monoaromatic, condensed polyaromatic and non-condensed aromatic radicals which are linked to one another via a direct bond or via a bridge element, the polyimide optionally having an aromatic ring at its polymer chain end which is unsubstituted or substituted with a radical which does not react with amines and/or dicarboxylic anhydrides. 5. A polyimide comprising a required structural unit consisting of one or more structural units selected from the group consisting of 1) the units of formula (3): where R&sub9; and Ar is a tetravalent radical having 2 to 27 carbon atoms selected from the group consisting of aliphatic, alicyclic, monoaromatic, condensed polyaromatic and non-condensed aromatic radicals which are linked to one another via a direct bond or via a bridging element; 2) the units of formula (4): wherein R�9 and Ar are as defined above; and 3) the units of formula (5): wherein R�9 and Ar are as defined above; wherein the polyimide optionally has at its polymer chain end an aromatic ring which is unsubstituted or substituted with a radical which does not react with amines and/or dicarboxylic anhydrides. 6. A polyimide copolymer comprising a required structural unit consisting of 1 to 99 mol% of repeating structural units of formula (1) where m and n are each an integer from 0 to 1 and R wherein R₁, R₂, R₃ and R₄ are each a hydrogen atom, a halogen atom, alkyl having 1 to 8 carbon atoms, aryl, alkenyl, aralkyl or alkoxy having 1 to 5 carbon atoms; R₅, R₆ and R₇ are each a hydrogen atom, alkyl having 1 to 8 carbon atoms, aryl, alkenyl, aralkyl or ω-alkyloxyoligo(alkyleneoxy)alkyl having 1 to 10 carbon atoms and 1 to 3 oxygen atoms and Ar is a tetravalent radical having 2 to 27 carbon atoms selected from the group consisting of aliphatic, alicyclic, monoaromatic, condensed polyaromatic and non-condensed aromatic radicals which are linked to one another via a direct bond or via a bridge element, and 99 to 1 mol% of repeating structural units of the formula (6): wherein n is an integer from 0 to 5, Q is a direct bond, -O-, -S-, -CO-, -SO₂-, -CH₂-, -C(CH₃)₂- or -C(CF₃)₂- and can be the same or different when aromatic rings are linked to one another via two or more linking radicals Q, and wherein Ar' is a tetravalent radical having 2 to 27 carbon atoms, selected from the group consisting of aliphatic, alicyclic, monoaromatic, fused polyaromatic and non-fused aromatic radicals which are linked to one another via a direct bond or via a bridging element; wherein the polyimide copolymer optionally has at its polymer chain end an aromatic ring which is unsubstituted or substituted with a radical which does not react with amines and/or dicarboxylic anhydrides. 7. A polyimide copolymer comprising a required structural unit consisting of 1 to 99 mol% of repeating structural units of the formula (2): wherein m and n are each an integer from 0 to 1, R8 is a hydrogen atom, a halogen atom, alkyl having 1 to 4 carbon atoms, alkoxy or phenyl and Ar is a tetravalent radical having 2 to 27 carbon atoms selected from the group consisting of aliphatic, alicyclic, monoaromatic, condensed polyaromatic and non-condensed aromatic radicals which are linked to one another via a direct bond or via a bridge element, and 99 to 1 mol% of repeating structural units of the formula (6): wherein n is an integer from 0 to 5, Q is a direct bond, -O-, -S-, -CO-, -SO₂-, -CH₂-, -C(CH₃)₂- or -C(CF₃)₂- and can be the same or different when aromatic rings are linked to one another via two or more linking radicals Q, and wherein Ar' is a tetravalent radical having 2 to 27 carbon atoms, selected from the group consisting of aliphatic, alicyclic, monoaromatic, condensed polyaromatic and non-condensed aromatic radicals which are linked to one another via a direct bond or via a bridging element; wherein the polyimide optionally has an aromatic ring at its polymer chain end which is unsubstituted or substituted with a radical which does not react with amines and/or dicarboxylic anhydrides. 8. A polyimide copolymer comprising two or more repeating structural units of the formula (1) described in claim 1, wherein the polyimide copolymer optionally has at its polymer chain end an aromatic ring which is unsubstituted or substituted with a radical which does not react with amines and/or dicarboxylic anhydrides. 9. Production process for a polyimide having a required structural unit consisting of one or more repeating structural units of the formula (1): where m and n are each an integer from 0 to 1, and R wherein R₁, R₂, R₃ and R₄ are each a hydrogen atom, a halogen atom, alkyl having 1 to 8 carbon atoms, aryl, alkenyl, aralkyl, or alkoxy having 1 to 5 carbon atoms; R₅, R₆ and R₇ are each a hydrogen atom, alkyl having 1 to 8 carbon atoms, aryl, alkenyl, aralkyl, or ω-alkyloxyoligo(alkyleneoxy)alkyl having 1 to 10 carbon atoms and 1 to 3 oxygen atoms, and Ar is a tetravalent radical having 2 to 27 carbon atoms selected from the group consisting of aliphatic, alicyclic, monoaromatic, condensed polyaromatic and non-condensed aromatic radicals which are linked to one another via a direct bond or via a bridge element, comprising reacting aromatic diamine consisting essentially of one or more aromatic diamino compounds of the formula (7): wherein m, n and R are as defined above, with tetracarboxylic acid dianhydride which predominantly has the formula (8): wherein Ar is a tetravalent radical having 2 to 27 carbon atoms, selected from the group consisting of aliphatic, alicyclic, monoaromatic, condensed polyaromatic and non-condensed aromatic radicals which are linked to one another via a direct bond or via a bridge element, and thermal or chemical imidization of the resulting polyamic acid. 10. A production process for a polyimide having a required structural unit consisting of one or more repeating structural units of the formula (1): where m and n are each an integer from 0 to 1 and R wherein R₁, R₂, R₃ and R₄ are each a hydrogen atom, a halogen atom, alkyl having 1 to 8 carbon atoms, aryl, alkenyl, aralkyl or alkoxy having 1 to 5 carbon atoms; R₅, R₆ and R₇ are each a hydrogen atom, alkyl having 1 to 8 carbon atoms, aryl, alkenyl, aralkyl or ω-alkyloxyoligo(alkyleneoxy)alkyl having 1 to 10 carbon atoms and 1 to 3 oxygen atoms and Ar is a tetravalent radical having 2 to 27 carbon atoms selected from the group consisting of aliphatic, alicyclic, monoaromatic, condensed polyaromatic and non-condensed aromatic radicals which are linked to one another via a direct bond or via a bridge element, wherein the polyimide at its polymer chain end having an aromatic ring which is unsubstituted or substituted with a radical which does not react with amines and/or dicarboxylic acid anhydrides, comprising reacting aromatic diamine consisting essentially of one or more aromatic diamino compounds of the formula (7): wherein m, n and R are as defined above, with tetracarboxylic acid dianhydride which predominantly has the formula (8): wherein Ar is a tetravalent radical having 2 to 27 carbon atoms selected from the group consisting of aliphatic, alicyclic, monoaromatic, condensed polyaromatic and non-condensed aromatic radicals which are linked to one another via a direct bond or via a bridging element, in the presence of aromatic dicarboxylic anhydride of the formula (9): wherein Z is a divalent radical having 6 to 15 carbon atoms selected from the group consisting of monoaromatic, condensed polyaromatic and non-condensed aromatic residues which are linked to one another via a direct bond or via a bridging element, and/or aromatic monoamine of the formula (10): Z₁-NH₂ (10) wherein Z₁ is a monovalent radical having 6 to 15 carbon atoms, selected from the group consisting of monoaromatic, condensed polyaromatic and non-condensed aromatic radicals which are linked to one another via a direct bond or via a bridging element, and thermal or chemical imidization of the resulting polyamic acid. 11. The manufacturing process according to claim 10, wherein the aromatic dicarboxylic anhydride is phthalic anhydride. 12. A manufacturing process according to claim 10, wherein the aromatic monoamine is aniline. 13. The production process according to claim 10, wherein the amount of aromatic dicarboxylic anhydride is 0.001 to 1.0 mole per mole of aromatic diamine. 14. The production process according to claim 11, wherein the amount of phthalic anhydride is 0.001 to 1.0 mole per mole of aromatic diamine. 15. The production process according to claim 10, wherein the amount of aromatic monoamine is 0.001 to 1.0 mole per mole of tetracarboxylic dianhydride. 16. The manufacturing process according to claim 12, wherein the amount of aniline is 0.001 to 1.0 mole per mole of tetracarboxylic dianhydride. 17. A composition comprising the polyimide of claim 1. 18. A polyimide film comprising the polyimide of claim 1. 19. A solution comprising the polyimide of claim 1. 20. Aromatic nitro compound of formula (11): where m and n are each an integer from 0 to 1 and R wherein R₁, R₂, R₃ and R₄ are each a hydrogen atom, a halogen atom, alkyl having 1 to 8 carbon atoms, aryl, alkenyl, aralkyl or alkoxy having 1 to 5 carbon atoms, and R₅, R₆ and R₇ are each a hydrogen atom, alkyl having 1 to 8 carbon atoms, aryl, alkenyl, aralkyl or ω-alkyloxyoligo(alkyleneoxy)alkyl having 1 to 10 carbon atoms and 1 to 3 oxygen atoms. 21. Aromatic diamino compound of formula (7): where m and n are each an integer from 0 to 1 and R wherein R₁, R₂, R₃ and R₄ each is a hydrogen atom, a halogen atom, alkyl having 1 to 8 carbon atoms, aryl, alkenyl, aralkyl or alkoxy having 1 to 5 carbon atoms, and R₅, R₆ and R₇ each is a hydrogen atom, alkyl having 1 to 8 carbon atoms, aryl, alkenyl, aralkyl or ω-alkyloxyoligo(alkyleneoxy)alkyl having 1 to 10 carbon atoms and 1 to 3 oxygen atoms. 22. An aromatic diamino compound according to claim 21, wherein the aromatic diamino compound of formula (7) is represented by formula (12): wherein n is an integer from 0 to 1 and R₈ is a hydrogen atom, a halogen atom, alkyl having 1 to 4 carbon atoms, alkoxy and phenyl. 23. An aromatic diamine compound according to claim 21, wherein the aromatic diamine compound of formula (7) is represented by formula (13): wherein R�9; is. 24. An aromatic diamine compound according to claim 21, wherein the aromatic diamine compound of formula (7) is represented by formula (14): wherein R�9; is. 25. An aromatic diamine compound according to claim 21, wherein the aromatic diamine compound of formula (7) is represented by formula (15): wherein R�9; is. 26. Preparation process of an aromatic diamino compound of formula (7): where m and n are each an integer from 0 to 1 and R wherein R₁, R₂, R₃ and R₄ are each a hydrogen atom, a halogen atom, alkyl having 1 to 8 carbon atoms, aryl, alkenyl, aralkyl or alkoxy having 1 to 5 carbon atoms, and R₅, R₆ and R₇ are each a hydrogen atom, alkyl having 1 to 8 carbon atoms, aryl, alkenyl, aralkyl or ω-alkyloxyoligo(alkyleneoxy)alkyl having 1 to 10 carbon atoms and 1 to 3 oxygen atoms, comprising carrying out a condensation of a dinitro compound of formula (16): wherein X is a halogen atom and m and n are each an integer from 0 to 1, with a hydroxy compound of the formula (17): R-OH (17) wherein R is as defined above, in an aprotic polar solvent in the presence of a base to give an aromatic dinitro compound of formula (11): where R, m and n are as defined above, and the subsequent reduction of the aromatic dinitro compound.