Transparent heat-resistant plastic substrate material with low thermal expansion and solution processability

Abstract

To provide a polyimide having all of solvent solubility, high transparency, high glass transition temperature and low linear thermal expansion coefficients.SOLUTION: A polyimide contains, in the main chain, a constitutional unit derived from a diamine represented by general formula (1): (R1 and R2 each denote a C1-12 alkyl group or a C1-12 aromatic group, R3 and R4 each denote a C1-12 alkyl group, a C1-12 aromatic group or a halogen atom, n1 and n2 each denote an integer of 0-3), and a constitutional unit derived from a tetracarboxylic acid dianhydride.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a polyimide that can be used as a transparent, heat-resistant plastic substrate material and has both low thermal expansion properties and solution processability (the ability to prepare a polyimide solution), as well as to a polyamic acid and diamines for producing the polyimide. [Background technology]

[0002] Glass substrates have traditionally been used in image display devices such as liquid crystal displays and organic electroluminescence (EL) displays. However, glass is heavy and cannot be bent. In recent years, there has been a demand for glass substitute materials to meet the demand for smaller, thinner, lighter, and more flexible screen display devices. As such materials, various polyimides with high heat resistance have been proposed.

[0003] On the other hand, polyimides are strongly colored due to intramolecular and intermolecular charge transfer interactions, making it difficult to use them as a replacement for current colorless, transparent glass substrates. Therefore, in recent years, there has been extensive research and development into polyimides that suppress coloration and turbidity of films while maintaining the excellent heat resistance of conventional polyimides (e.g., Non-Patent Documents 1 and 2).

[0004] Furthermore, when using colorless and transparent polyimide film as a replacement for glass substrates in image display devices, the polyimide film must have sufficient heat resistance (high glass transition temperature) to withstand the high-temperature processes used in device manufacturing. Furthermore, if the linear thermal expansion coefficient of polyimide film is large in the glass temperature range, i.e., below the glass transition temperature, the film will expand and contract significantly as it follows the temperature rise and fall cycles during device manufacturing, which could potentially trigger serious problems such as misalignment of electronic circuits on the substrate, warping of the substrate, and broken electrodes. Therefore, polyimide film as a glass replacement material must also have low thermal expansion properties.

[0005] Polyimide films can be rendered colorless by disrupting the charge-transfer interaction. A highly effective method for achieving this is to use an aliphatic (usually alicyclic from the viewpoint of heat resistance) monomer as at least one of the polyimide monomer components, tetracarboxylic dianhydride and diamine (see, for example, Non-Patent Document 1). Furthermore, for polyimide films to exhibit a low coefficient of linear thermal expansion, it is essential that the polyimide main chain has a linear and rigid structure throughout (see, for example, Non-Patent Document 2). However, because many alicyclic monomers have poor planarity and linearity in their three-dimensional structures, polyimides produced using alicyclic monomers often do not exhibit low thermal expansion and, furthermore, exhibit almost no solvent solubility. Therefore, it has been extremely difficult to provide polyimides that exhibit high heat resistance, excellent transparency, a low coefficient of linear thermal expansion, and excellent solvent solubility. [Prior art documents] [Non-patent literature]

[0006] [Non-Patent Document 1] Progress in Polymer Science, 26, 259-335 (2001). [Non-patent document 2] Polymers, 9, 520-550 (2017). Summary of the Invention [Problem to be solved by the invention]

[0007] An object of the present invention is to provide a polyimide that is solvent-soluble, yet has high transparency, a high glass transition temperature, and a low coefficient of linear thermal expansion. [Means for solving the problem]

[0008] As a result of extensive research into solving the above problems, the present inventors have found that a polyimide having the following structure can solve the above problems. Specifically, the present invention includes the following inventions.

[0009] [1] A polyimide containing a structural unit derived from a diamine represented by the following general formula (1) in the main chain:

[0010] [ka] (In the above general formula (1), R1 and R2 each independently represent an alkyl group having 1 to 12 carbon atoms which may have a substituent or an aromatic group having 1 to 12 carbon atoms which may have a substituent; R3 and R4 each independently represent an alkyl group having 1 to 12 carbon atoms which may have a substituent, an aromatic group having 1 to 12 carbon atoms which may have a substituent, or a halogen atom; n1 and n2 each independently represent an integer of 0 to 3; and when there are multiple R3s and / or R4s, they may be the same or different.)

[0011] [2] The polyimide according to [1], which has a repeating unit represented by the following general formula (P-1):

[0012] [ka] (In the above general formula (P-1), R 1、 R 2、 R 3、 R 4、 n1 and n2 are as defined above. A1 represents a tetravalent aliphatic group.

[0013] [3] The polyimide according to [1] or [2], wherein R1 and / or R2 is an alkyl group having 1 to 12 carbon atoms and having a fluorine atom or a substituent containing a fluorine atom, or an aromatic group having 1 to 12 carbon atoms and having a fluorine atom or a substituent containing a fluorine atom.

[0014] [4] The polyimide according to [3], wherein the substituent containing a fluorine atom is a trifluoromethyl group.

[0015] [5] The polyimide according to any one of [1] to [4], further comprising a repeating unit represented by the following general formula (P-2):

[0016] [ka] (In the above general formula (P-2), A1 is as defined above. A2 is a divalent aromatic group having a substituent containing a fluorine atom.)

[0017] [6] A polyamic acid containing, in its main chain, a structural unit derived from a diamine represented by the following general formula (1):

[0018] [ka] (In the above general formula (1), R1 and R2 each independently represent an alkyl group having 1 to 12 carbon atoms which may have a substituent or an aromatic group having 1 to 12 carbon atoms which may have a substituent; R3 and R4 each independently represent an alkyl group having 1 to 12 carbon atoms which may have a substituent, an aromatic group having 1 to 12 carbon atoms which may have a substituent, or a halogen atom; n1 and n2 each independently represent an integer of 0 to 3; and when there are multiple R3s and / or R4s, they may be the same or different.)

[0019] [7] Diamines represented by the following general formula (1):

[0020] [ka] (In the above general formula (1), R1 and R2 each independently represent an alkyl group having 1 to 12 carbon atoms which may have a substituent or an aromatic group having 1 to 12 carbon atoms which may have a substituent; R3 and R4 each independently represent an alkyl group having 1 to 12 carbon atoms which may have a substituent, an aromatic group having 1 to 12 carbon atoms which may have a substituent, or a halogen atom; n1 and n2 each independently represent an integer of 0 to 3; and when there are multiple R3s and / or R4s, they may be the same or different.)

[0021] [8] The following general formula (2):

[0022] [ka] (In the above general formula (2), R1 and R2 each independently represent an alkyl group having 1 to 12 carbon atoms which may have a substituent or an aromatic group having 1 to 12 carbon atoms which may have a substituent; R3 and R4 each independently represent an alkyl group having 1 to 12 carbon atoms which may have a substituent, an aromatic group having 1 to 12 carbon atoms which may have a substituent, or a halogen atom; n1 and n2 each independently represent an integer of 0 to 3; and when there are multiple R3s and / or R4s, they may be the same or different.) The method for producing diamines according to [7], wherein a dinitrodiester represented by the following formula (I) is reduced:

[0023] [9] Dinitrodiesters represented by the following general formula (2):

[0024] [ka] (In the above general formula (2), R1 and R2 each independently represent an alkyl group having 1 to 12 carbon atoms which may have a substituent or an aromatic group having 1 to 12 carbon atoms which may have a substituent; R3 and R4 each independently represent an alkyl group having 1 to 12 carbon atoms which may have a substituent, an aromatic group having 1 to 12 carbon atoms which may have a substituent, or a halogen atom; n1 and n2 each independently represent an integer of 0 to 3; and when there are multiple R3s and / or R4s, they may be the same or different.)

[0025]

[10] Dinitrobisphenols represented by the following general formula (3):

[0026] [ka] (In the above general formula (3), R3 and R4 each independently represent an alkyl group having 1 to 12 carbon atoms which may have a substituent, an aromatic group having 1 to 12 carbon atoms which may have a substituent, or a halogen atom. n1 and n2 each independently represent an integer of 0 to 3. When there are multiple R3s and / or R4s, they may be the same or different.)

[0027]

[11] A polyimide solution containing the polyimide according to any one of [1] to [5] and an organic solvent.

[0028]

[12] A polyimide film containing the polyimide according to any one of [1] to [5].

[0029]

[13] A plastic substrate material containing the polyimide according to any one of [1] to [5]. [Effects of the Invention]

[0030] The polyimide of the present invention (a polyimide containing a diamine-derived structural unit represented by the general formula (1) in its main chain) has excellent solvent solubility, making it possible to give a stable varnish (polyimide solution) at a high solids concentration. Furthermore, a cast film obtained from the varnish also exhibits high transparency, a high glass transition temperature, and a low coefficient of linear thermal expansion (high thermal dimensional stability). Furthermore, while a low coefficient of linear thermal expansion generally tends to result in high birefringence (a trade-off), the polyimide of the present invention is characterized by low birefringence despite its low coefficient of linear thermal expansion. [Brief explanation of the drawings]

[0031] [Figure 1] 1 shows the 1H-NMR spectrum of the diamine represented by the following formula (1-1), which is one of the amines represented by the general formula (1) produced in Example 3. [Figure 2]This is a 1H-NMR spectrum of the diamine represented by the following formula (1-1), one of the amines represented by the above general formula (1) produced in Example 3, with the area around 6.2-8.4 ppm enlarged. [Figure 3] 1 shows an FT-IR spectrum of a diamine represented by the following formula (1-1), which is one of the amines represented by the general formula (1) produced in Example 3. DETAILED DESCRIPTION OF THE INVENTION

[0032] <Polyimide of the present invention> The polyimide of the present invention is represented by the following general formula (1):

[0033] [ka] (In the above general formula (1), R1 and R2 each independently represent an alkyl group having 1 to 12 carbon atoms which may have a substituent or an aromatic group having 1 to 12 carbon atoms which may have a substituent; R3 and R4 each independently represent an alkyl group having 1 to 12 carbon atoms which may have a substituent, an aromatic group having 1 to 12 carbon atoms which may have a substituent, or a halogen atom; n1 and n2 each independently represent an integer of 0 to 3; and when there are multiple R3s and / or R4s, they may be the same or different.) and a tetracarboxylic dianhydride-derived structural unit in the main chain. (Hereinafter, this polyimide may be referred to as the "polyimide of the present invention.") Furthermore, the "diamine-derived structural unit represented by the above general formula (1)" refers to a structure in which two amino groups have been removed from the above general formula (1).

[0034] In the general formula (1), with respect to the alkyl group having 1 to 12 carbon atoms which may have a substituent in the substituents R1 and R2, examples of the alkyl group having 1 to 12 carbon atoms include linear or branched alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, iso-butyl, tert-butyl, n-pentyl, and n-hexyl, and cycloalkyl groups having 4 to 12 carbon atoms (preferably 5 to 8 carbon atoms) such as cyclopentyl and cyclohexyl. Among these alkyl groups, linear or branched alkyl groups having 1 to 8 carbon atoms are preferred, linear or branched alkyl groups having 1 to 6 carbon atoms are more preferred, and linear or branched alkyl groups having 1 to 3 carbon atoms are even more preferred.

[0035] With regard to the aromatic group having 1 to 12 carbon atoms which may have a substituent, examples of the aromatic group having 1 to 12 carbon atoms include a phenyl group and a naphthyl group, and a phenyl group is preferred.

[0036] Examples of the substituent in the alkyl group having 1 to 12 carbon atoms which may have a substituent or the aromatic group having 1 to 12 carbon atoms which may have a substituent include an alkyl group having 1 to 4 carbon atoms which may have a branch, a halogenated alkyl group having 1 to 4 carbon atoms which may have a branch, and a halogen atom. Among these substituents, a fluorine atom or a substituent containing a fluorine atom is preferred, and a trifluoromethyl group is more preferred.

[0037] R1 and R2 are preferably aromatic groups having 1 to 12 carbon atoms which may have a substituent, and the substituent is more preferably a fluorine atom or a substituent containing a fluorine atom. R1 and R2 may be the same or different, but from the viewpoint of simplicity of the production process of the diamine represented by general formula (1), it is preferred that R1 and R2 are the same.

[0038] In the above general formula (1), examples of the alkyl group having 1 to 12 carbon atoms, which may have a substituent, in the substituents R3 and R4 include linear or branched alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, n-pentyl, and n-hexyl, and cycloalkyl groups having 4 to 12 carbon atoms (preferably 5 to 8 carbon atoms), such as cyclopentyl and cyclohexyl. Among these alkyl groups, linear or branched alkyl groups having 1 to 8 carbon atoms are preferred, linear or branched alkyl groups having 1 to 6 carbon atoms are more preferred, and linear or branched alkyl groups having 1 to 3 carbon atoms are even more preferred.

[0039] Examples of the aromatic group having 1 to 12 carbon atoms which may have a substituent include a phenyl group and a naphthyl group, and a phenyl group is preferred.

[0040] Examples of the substituent in the alkyl group having 1 to 12 carbon atoms which may have a substituent or the aromatic group having 1 to 12 carbon atoms which may have a substituent include an alkyl group having 1 to 4 carbon atoms which may have a branch, a halogenated alkyl group having 1 to 4 carbon atoms which may have a branch, and a halogen atom.

[0041] Examples of halogen atoms include fluorine, chlorine, bromine, and iodine, with fluorine being preferred.

[0042] n1 and n2, which represent the numbers of R3 and R4, are usually integers of 0 to 3, preferably 0 or 1, and more preferably 0.

[0043] R3 and R4 may be the same or different, and when multiple R3 and / or R4 are present, they may be the same or different. However, from the viewpoint of simplicity of the production process of the diamine represented by general formula (1), it is preferable that R3 and R4 are the same.

[0044] Although n1 and n2 may be the same or different, it is preferable that n1 and n2 are the same from the viewpoint of simplicity of the production process of the diamine represented by general formula (1).

[0045] From the viewpoint of simplicity of the production process of the diamine represented by the above general formula (1), the bonding positions of the ester groups (-OCOR1 and -OCOR2) of the diamine are preferably the 3- and 6-positions or the 2- and 7-positions of the xanthene skeleton.

[0046] Specific examples of the diamines represented by the above general formula (1) include diamines represented by the following formula (1-1), but the present invention is not limited thereto.

[0047] [ka]

[0048] The polyimide of the present invention may contain one or more types of constitutional units derived from diamines represented by the above general formula (1).

[0049] Examples of the tetracarboxylic dianhydride (tetracarboxylic dianhydride constituting a tetracarboxylic dianhydride-derived structural unit) used in the polyimide of the present invention include 1,2,4,5-cyclohexanetetracarboxylic dianhydride, bicyclo[2.2.2]octane-2,3,5,6-tetracarboxylic dianhydride, bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxylic dianhydride, 5-(dioxotetrahydrofuryl-3-methyl)-3-cyclohexene-1,2-dicarboxylic anhydride, 4-(2,5-dioxotetrahydrofuryl)-3-cyclohexene-1,2-dicarboxylic anhydride, 5-(dioxotetrahydrofuryl)-3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride, 4-(2,5- ... aliphatic tetracarboxylic dianhydrides such as (furan-3-yl)-tetralin-1,2-dicarboxylic anhydride, tetrahydrofuran-2,3,4,5-tetracarboxylic dianhydride, bicyclohexyl-3,3',4,4'-tetracarboxylic dianhydride, 1,2,3,4-cyclopentanetetracarboxylic dianhydride, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, and 1,4-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride are examples. In addition to aliphatic tetracarboxylic dianhydrides, aromatic tetracarboxylic dianhydrides can also be selected, such as pyromellitic anhydride, 4,4'-oxydiphthalic dianhydride, biphenyl-3,4,3',4'-tetracarboxylic dianhydride, benzophenone-3,4,3',4'-tetracarboxylic dianhydride, diphenylsulfone-3,4,3',4'-tetracarboxylic dianhydride, 4,4'-(2,2-hexafluoroisopropylidene)diphthalic dianhydride, m-terphenyl-3,4,3',4'-tetracarboxylic dianhydride, p-terphenyl-3,4,3',4'-tetracarboxylic dianhydride, etc. These may be used alone or in combination (i.e., copolymerized) with two or more types as needed.

[0050] The inclusion of a diamine-derived structural unit represented by the general formula (1) above can impart solvent solubility and low thermal expansion to the polyimide. To further improve these properties, it is preferable to select an aliphatic tetracarboxylic dianhydride as the tetracarboxylic dianhydride used. Among aliphatic tetracarboxylic dianhydrides, 1,2,3,4-cyclobutanetetracarboxylic dianhydride (CBDA) is particularly preferred. In this case, the amount of the aliphatic tetracarboxylic dianhydride used is preferably 70 to 100 mol %, more preferably 90 to 100 mol %, of the total tetracarboxylic dianhydride. 100 mol %, i.e., using only aliphatic tetracarboxylic dianhydrides without using any aromatic tetracarboxylic dianhydride, is even more preferred.

[0051] Among the polyimides of the present invention described above, specifically, polyimides represented by the following general formula (P-1):

[0052] [ka] (In the above general formula (P-1), R 1、 R 2、 R 3、 R 4、 n1 and n2 are as defined above. A1 represents a tetravalent aliphatic group. In the general formula (P-1), A1 is derived from the aliphatic tetracarboxylic dianhydride described above. Therefore, by containing the repeating units represented by the general formula (P-1) in the polyimide of the present invention in an amount of usually 70 mol %, preferably 90 mol %, per mole of all repeating units in the polyimide of the present invention, the properties of the polyimide containing the aliphatic tetracarboxylic dianhydride described above can be more effectively exhibited.

[0053] The polyimide of the present invention may contain diamines other than the diamines of the present invention represented by the above general formula (1) (hereinafter, these may be referred to as "other diamines." The other diamines are structural units constituting the polyimide of the present invention) in the main chain, as necessary. Specific examples include 1,4-diaminobenzene, 1,3-diaminobenzene, 2,4-diaminotoluene, 4,4-diaminodiphenylmethane, 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 3,3'-dimethyl-4,4'-diaminobiphenyl, 2,2'-dimethyl-4,4'-diaminobiphenyl, 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl, 3,7-diamino-dimethyldibenzothiophene-5,5-dioxide, 4,4-Diaminobenzophenone, 3,3'-diaminobenzophenone, 4,4'-bis(4-aminophenyl) sulfide, 4,4'-diaminodiphenyl sulfone, 4,4'-diaminobenzanilide, 1,3-bis(4-aminophenoxy)propane, 1,4-bis(4-aminophenoxy)butane, 1,5-bis(4-aminophenoxy)pentane, 1,3-bis(4-aminophenoxy)-2,2-dimethylpropane, 1,2-bis[2-(4-aminophenoxy)ethoxy]ethoxy Tantalum, 9,9-bis(4-aminophenyl)fluorene, 1-(4-aminophenyl)-2,3-dihydro-1,3,3-trimethyl-1H-inden-5-amine, 1,4-bis(4-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,3-bis(3-aminophenoxy)benzene, 4,4'-bis(4-aminophenoxy)biphenyl, 4,4'-bis(3-aminophenoxy)biphenyl, 2,2-bis(4-aminophenoxyphenyl)propane , bis[4-(4-aminophenoxy)phenyl]sulfone, bis[4-(3-aminophenoxy)phenyl]sulfone, 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane, 3,3'-dicarboxy-4,4'-diaminodiphenylmethane, 4,6-dihydroxy-1,3-phenylenediamine, 3,3'-dihydroxy-4,4'-diaminobiphenyl, 2,2-bis(3-amino-4-hydroxyphenyl)-hexafluoropropane, 3,3',4,4'-Tetraaminobiphenyl, 1,6-diaminohexane, 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane, 1-amino-3-aminomethyl-3,5,5-trimethylcyclohexane, 4,4'-methylenebis(cyclohexylamine), 1,4-diaminocyclohexane, 2,5-bicyclo[2.2.1]heptanebis(methylamine), tricyclo[3.3.1.13.7]decane-1,3-diamine, 4-aminophenyl 4-aminobenzoate, 2-(4-aminophenyl)-5-aminobenzoxa azole, 9,9-bis[4-(4-aminophenoxy)phenyl]fluorene, 2,2'-bis(3-sulfopropoxy)-4,4'-diaminobiphenyl, 4,4'-bis(4-aminophenoxy)biphenyl-3,3'-disulfonic acid, 1,4-diamino-2-fluorobenzene, 1,4-diamino-2,3-difluorobenzene, 1,4-diamino-2,5-difluorobenzene, 1,4-diamino-2,6-difluorobenzene, 1,4-diamino-2,3,5-trifluorobenzene, 1,4-diamino-2,3,5,6-tetrafluorobenzene Benzene, 1,4-diamino-2-(trifluoromethyl)benzene, 1,4-diamino-2,3-bis(trifluoromethyl)benzene, 1,4-diamino-2,5-bis(trifluoromethyl)benzene, 1,4-diamino-2,6-bis(trifluoromethyl)benzene, 1,4-diamino-2,3,5-tris(trifluoromethyl)benzene, 1,4-diamino-2,3,5,6-tetrakis(trifluoromethyl)benzene, 2-fluorobenzidine, 3-fluorobenzidine, 2,3-difluorobenzidine, 2,5-difluorobenzidine benzidine, 2,6-difluorobenzidine, 2,3,5-trifluorobenzidine, 2,3,6-trifluorobenzidine, 2,3,5,6-tetrafluorobenzidine, 2,2'-difluorobenzidine, 3,3'-difluorobenzidine, 2,3'-difluorobenzidine, 2,2',3-trifluorobenzidine, 2,3,3'-trifluorobenzidine, 2,2',5-trifluorobenzidine, 2,2',6-trifluorobenzidine, 2,3',5-trifluorobenzidine, 2,3',6-trifluorobenzidine, 2,2',3,3'-Tetrafluorobenzidine, 2,2',5,5'-tetrafluorobenzidine, 2,2',6,6'-tetrafluorobenzidine, 2,2',3,3',6,6'-hexafluorobenzidine, 2,2',3,3',5,5',6,6'-octafluorobenzidine, 2-(trifluoromethyl)benzidine, 3-(trifluoromethyl)benzidine, 2,3-bis(trifluoromethyl)benzidine, 2,5-bis(trifluoromethyl)benzidine, 2,6-bis(trifluoromethyl)benzidine, 2,3,5-tris(trifluoromethyl)benzidine, 2,3,6-tris(trifluoromethyl)benzidine, 2,3,5,6-tetrakis(trifluoromethyl)benzidine Examples include 2,3'-tris(trifluoromethyl)benzidine, 2,3'-bis(trifluoromethyl)benzidine, 2,2',3-bis(trifluoromethyl)benzidine, 2,3,3'-tris(trifluoromethyl)benzidine, 2,2',5-tris(trifluoromethyl)benzidine, 2,2',6-tris(trifluoromethyl)benzidine, 2,3',5-tris(trifluoromethyl)benzidine, 2,3',6-tris(trifluoromethyl)benzidine, 2,2',3,3'-tetrakis(trifluoromethyl)benzidine, 2,2',5,5'-tetrakis(trifluoromethyl)benzidine, and 2,2',6,6'-tetrakis(trifluoromethyl)benzidine. These diamines may be used alone or in combination (i.e., copolymerized) with two or more types as needed.

[0054] Among other diamines (copolymerized diamine components) that can be used in combination with the diamine of the present invention, aromatic diamines containing fluorine atoms are preferred from the viewpoints of improving the transparency, solvent solubility, and low thermal expansion of the polyimide. Furthermore, among aromatic diamines containing fluorine atoms, it is more preferable to use aromatic diamines containing trifluoromethyl groups, and among aromatic diamines containing trifluoromethyl groups, 2,2'-bis(trifluoromethyl)benzidine (TFMB) is particularly preferred from the viewpoints of cost and availability.

[0055] From the viewpoints of maintaining the solvent solubility of the polyimide, high transparency of the film, high heat resistance, and low thermal expansion, the amount of other diamines used in combination with the diamines of the present invention is preferably 0 to 70 mol %, more preferably 0 to 50 mol %, of the total amount of diamines.

[0056] In addition to the above-mentioned structural units (repeating units), the polyimide of the present invention may also contain a unit represented by the following general formula (P-2):

[0057] [ka] (In the above general formula (P-2), A1 is as defined above. A2 is a divalent aromatic group having a substituent containing a fluorine atom.) In the above general formula (P-2), the tetravalent aliphatic group represented by A1 is derived from an aliphatic tetracarboxylic dianhydride, and the divalent aromatic group containing a fluorine atom represented by A2 is derived from the above-mentioned aromatic diamines having a fluorine atom, and specific examples thereof include a structure in which some of the hydrogen atoms on the aromatic ring are substituted with fluorine atoms, and a structure in which some or all of the hydrogen atoms of the alkyl group that is a substituent on the aromatic ring are substituted with fluorine atoms.

[0058] When the polyimide of the present invention has a repeating unit represented by the above general formula (P-2), the content of the repeating unit is usually 1 to 70 mol %, and preferably 1 to 50 mol %, per mol of all repeating units of the polyimide of the present invention.

[0059] The polyimide of the present invention may further contain structural units that can generally be contained in polyimides (for example, structural units derived from compounds having an amide group or an ester group).

[0060] <Physical Properties of the Polyimide of the Present Invention> (1) Weight average molecular weight The weight-average molecular weight of the polyimide of the present invention varies depending on its application, but is preferably in the range of 30,000 to 500,000, more preferably 40,000 to 300,000, and even more preferably 50,000 to 200,000. A weight-average molecular weight of 30,000 or more ensures sufficient flexibility when the polyimide is formed into a film. On the other hand, a weight-average molecular weight of 500,000 or less ensures good solubility, allowing for the formation of a coating or film with a smooth surface and uniform thickness. The molecular weight in the present invention refers to a value calculated in terms of polystyrene by gel permeation chromatography (GPC).

[0061] (2) Glass transition temperature A higher glass transition temperature means a higher physical heat resistance of the resin. The polyimide of the present invention preferably has a glass transition temperature of 250°C or higher, more preferably 300°C or higher, and even more preferably 330°C or higher. The method for measuring the glass transition temperature will be described in detail in the Examples section. The upper limit of the glass transition temperature is not particularly limited, but may be 500°C or lower.

[0062] (3) Linear thermal expansion coefficient When the length of a sample changes from L1 to L2 during the temperature increase process in which the temperature of the sample is changed from T1 to T2, the ratio of the change in length (ΔL = L2 - L1) to the initial length (L0) of the sample is called the coefficient of thermal expansion between temperatures T1 and T2. The value obtained by further dividing this by the temperature difference ΔT = T2 - T1 is called the average coefficient of linear thermal expansion between temperatures T1 and T2 (hereinafter sometimes referred to as "CTE"), and is expressed by the following formula. In the present invention, unless otherwise specified, CTE refers to the average coefficient of linear thermal expansion in the range of 100 to 200°C. CTE=(ΔL / L0) / ΔT

[0063] From the viewpoint of thermal dimensional stability, the CTE of the polyimide film of the present invention is preferably 1 to 30 ppm / K, more preferably 5 to 25 ppm / K. A specific method for measuring the CTE will be described in detail in the Examples section.

[0064] (4) Total light transmittance From the viewpoint of transparency, the total light transmittance of the polyimide of the present invention is preferably 80% or more, more preferably 85% or more, when the film thickness is 5 to 30 μm. Furthermore, the "film thickness" in the present invention refers to the thickness of the film formed from the polyimide of the present invention, and can be measured, for example, using a contact film thickness meter. The method for measuring the total light transmittance will be described in detail in the Examples section.

[0065] (5) Birefringence The polyimide of the present invention typically has a birefringence of 0.05 or less, preferably 0.045 or less. Generally, polyimides with a small linear thermal expansion coefficient tend to have a large birefringence. However, the polyimide of the present invention has the characteristics of having a small birefringence and, as will be described later, also having a small linear thermal expansion coefficient. Note that, in the present invention, birefringence refers to the "thickness direction birefringence" calculated from the difference between the in-plane refraction and the out-of-plane refraction of the polyimide film, and is measured under the conditions described in the Examples section below.

[0066] <Polyamic acid containing a structural unit derived from a diamine represented by the above general formula (1) in the main chain> The polyamic acid containing a diamine-derived structural unit represented by the general formula (1) in its main chain (hereinafter, sometimes referred to as the "polyamic acid of the present invention") is a polyamic acid containing a diamine-derived structural unit represented by the general formula (1) in its main chain and a tetracarboxylic dianhydride-derived structural unit in its main chain, and specific embodiments of the diamine represented by the general formula (1) and specific and preferred embodiments of the tetracarboxylic dianhydride are as described above in the section on the polyimide of the present invention. Furthermore, as with the polyimide of the present invention, it may contain other structural units that can be contained in polyimides (for example, structural units derived from compounds having an amide group or an ester group) as necessary.

[0067] The weight-average molecular weight of the polyamic acid of the present invention varies depending on its application, but is preferably in the range of 30,000 to 500,000, more preferably 40,000 to 300,000, and even more preferably 50,000 to 200,000. When the weight-average molecular weight of the polyamic acid is 30,000 or more, film formation is possible and good mechanical properties are easily maintained. Furthermore, when the weight-average molecular weight of the polyamic acid is 500,000 or less, gelation of the reaction solution during synthesis is easily avoided, and the solution viscosity is not so high that handling is significantly impaired. The viscosity (intrinsic viscosity) of the polyamic acid solution can be used as a guide to determine the weight-average molecular weight of the polyamic acid.

[0068] <Diamines represented by the above general formula (1)> Specific and preferred embodiments of the diamines represented by the general formula (1) above (hereinafter, sometimes referred to as "diamines of the present invention") are as described above in the section on the polyimide of the present invention.

[0069] <Method of producing diamine of the present invention> The diamine of the present invention represented by the above general formula (1) can be reacted with a compound represented by the following general formula (5):

[0070] [ka] and dinitrofluorenones represented by the following general formula (6):

[0071] [ka] (In the above general formula (6), R6 represents an alkyl group having 1 to 12 carbon atoms which may have a substituent, an aromatic group having 1 to 12 carbon atoms which may have a substituent, or a halogen atom. n3 represents an integer of 0 to 3. When there are multiple R6s, they may be the same or different.) to react a phenol represented by the following general formula (3):

[0072] [ka] (In the above general formula (3), R3 and R4 each independently represent an alkyl group having 1 to 12 carbon atoms which may have a substituent, an aromatic group having 1 to 12 carbon atoms which may have a substituent, or a halogen atom. n1 and n2 each independently represent an integer of 0 to 3. When there are multiple R3s and / or R4s, they may be the same or different.) After obtaining a dinitrobisphenol represented by the following general formula (4):

[0073] [ka] (In the above general formula (4), X1 represents a halogen atom, and R5 represents an alkyl group having 1 to 12 carbon atoms which may have a substituent or an aromatic group having 1 to 12 carbon atoms which may have a substituent.) The carboxylic acid halide represented by the following general formula (2):

[0074] [ka] (In the above general formula (2), R1 and R2 each independently represent an alkyl group having 1 to 12 carbon atoms which may have a substituent or an aromatic group having 1 to 12 carbon atoms which may have a substituent; R3 and R4 each independently represent an alkyl group having 1 to 12 carbon atoms which may have a substituent, an aromatic group having 1 to 12 carbon atoms which may have a substituent, or a halogen atom; n1 and n2 each independently represent an integer of 0 to 3; and when there are multiple R3s and / or R4s, they may be the same or different.) and reducing the nitro group of the dinitrodiester. The above production method will be described in detail below.

[0075] <Method for producing dinitrobisphenols represented by the above general formula (3)> The dinitrobisphenols represented by the general formula (3) can be obtained, for example, by reacting the dinitrofluorenones represented by the general formula (5) with the phenols represented by the general formula (6) in the presence of an acid (hereinafter, this reaction may be referred to as a xanthene reaction).

[0076] The dinitrofluorenones represented by the general formula (5) can be produced by a conventionally known method such as nitrating 9-fluorenone, or commercially available products can also be used. From the viewpoint of easy availability, the dinitrofluorenones represented by the general formula (5) are preferably 2,7-dinitro-9-fluorenone.

[0077] In the phenols represented by the general formula (6), the substituent R6 and the number of substituents n3 correspond to the substituents R3 and R4 and the number of substituents n1 and n2 in the diamines represented by the general formula (1). Therefore, specific aspects and preferred aspects of the substituent R6 and the number of substituents n3 are the same as those described in detail for the substituents R3 and R4 and the number of substituents n1 and n2.

[0078] The acid used in the xanthene reaction may be either an inorganic acid or an organic acid. Examples of inorganic acids include sulfuric acid, hydrochloric acid, and phosphoric acid, and examples of organic acids include paratoluenesulfonic acid, methanesulfonic acid, and acetic acid. Among these acids, sulfuric acid, hydrochloric acid, and paratoluenesulfonic acid are preferred. These acids may be used alone or in combination of two or more, if necessary. The amount of acid used is, for example, 0.01 to 10 mol, preferably 0.1 to 7 mol, and more preferably 0.4 to 5 mol, per mol of the dinitrofluorenone represented by the general formula (5). By using an amount of 10 mol or less, the purity of the resulting dinitrobisphenols can be improved and coloration can be reduced. Furthermore, by using an amount greater than 0.01 mol, a sufficient reaction rate can be obtained.

[0079] When carrying out the xanthene reaction, an inert organic solvent can be used as necessary. Usable organic solvents include, for example, aromatic hydrocarbons, halogenated aromatic hydrocarbons, and halogenated aliphatic hydrocarbons. Examples of aromatic hydrocarbons include toluene, xylene, and mesitylene. Examples of aliphatic hydrocarbons include pentane, hexane, and heptane. Examples of halogenated aromatic hydrocarbons include chlorobenzene and dichlorobenzene. Examples of halogenated aliphatic hydrocarbons include dichloromethane and 1,2-dichloroethane. Among these organic solvents, aromatic hydrocarbons and halogenated aromatic hydrocarbons are preferred, with toluene and xylene being particularly preferred. One organic solvent may be used, or two or more organic solvents may be used in combination as needed.

[0080] When an organic solvent is used, the amount used is usually 1 to 15 parts by weight, preferably 1.5 to 10 parts by weight, and more preferably 1.5 to 4 parts by weight, per part by weight of the dinitrofluorenone represented by the above general formula (5). By using an organic solvent in an amount of 1 part by weight or more, dinitrobisphenols can be produced more easily, and by using an amount of 15 parts by weight or less, dinitrobisphenols can be produced more economically and with better productivity.

[0081] The xanthene reaction is usually carried out at 80°C or higher, preferably 80 to 140°C, and more preferably 100 to 120°C. By setting the reaction temperature to 80°C or higher, the cyclization reaction after the condensation reaction of the dinitrofluorenones represented by the general formula (5) with the phenols represented by the general formula (6) proceeds efficiently, resulting in a sufficient reaction rate. Furthermore, by setting the reaction temperature to 140°C or lower, the formation of dimers or higher polymers can be suppressed, and the coloration of the resulting dinitrobisphenols can be reduced.

[0082] When carrying out the xanthene reaction, a thio compound may be used in combination as needed. Examples of thio compounds that can be used in combination include mercaptocarboxylic acids such as thioacetic acid, β-mercaptopropionic acid, α-mercaptopropionic acid, thioglycolic acid, thiooxalic acid, mercaptosuccinic acid, and mercaptobenzoic acid; alkyl mercaptans such as methyl mercaptan, ethyl mercaptan, propyl mercaptan, isopropyl mercaptan, butyl mercaptan, octyl mercaptan, decyl mercaptan, and dodecyl mercaptan; and aralkyl mercaptans such as benzyl mercaptan, as well as alkali metal salts thereof. One type of thio compound may be used, or two or more types may be used in combination as needed. Among these thio compounds, alkyl mercaptans are preferred, and alkyl mercaptans with an alkyl group containing 6 or more carbon atoms are preferred because of their low odor and ease of handling, with dodecyl mercaptan being particularly preferred. The amount of the thio compound used is, for example, 0.01 to 0.3 mol, preferably 0.01 to 0.1 mol, per 1 mol of the dinitrofluorenone represented by the above general formula (5).

[0083] After the xanthene reaction, the resulting reaction solution may be subjected to the esterification reaction described below as it is, or may be purified using a conventional purification method (extraction, washing, adsorption, steam distillation, crystallization, column purification, etc.) before use in the reaction. Furthermore, purification may be carried out once or multiple times.

[0084] <Method for producing dinitrodiesters represented by the above general formula (2)> The dinitrodiesters represented by the general formula (2) can be produced, for example, by reacting the dinitrobisphenols represented by the general formula (3) with the carboxylic acid halide represented by the general formula (4) in the presence of a base (hereinafter, this may be referred to as an esterification reaction).

[0085] In the carboxylic acid halide represented by the general formula (4), the substituent R5 corresponds to the substituents R1 and R2 in the diamine represented by the general formula (1). Therefore, specific and preferred aspects of the substituent R5 are the same as those detailed for the substituents R1 and R2. Examples of the halogen atom represented by X1 include fluorine, chlorine, bromine, and iodine, and chlorine is preferred from the viewpoint of easy availability of the carboxylic acid halide.

[0086] When carrying out the esterification reaction, the carboxylic acid halide represented by the above general formula (4) has high solubility and can be easily removed by washing after the reaction, so it can be used in excess of the reaction equivalent, and the amount used is, for example, usually 2 to 10 moles, and preferably 2 to 5 moles, per mole of the dinitrobisphenol represented by the above general formula (3). By using an amount of carboxylic acid halide of 2 to 10 moles, it becomes possible to completely remove the excess carboxylic acid halide while suppressing the production of a monoester in which the reaction is incomplete.

[0087] Examples of bases used in the esterification reaction include basic nitrogen-containing cyclic compounds such as pyridine, organic tertiary amines such as triethylamine and N,N-dimethylaniline, epoxies such as propylene oxide, and inorganic bases such as potassium carbonate and sodium hydroxide. Pyridine is preferably used from the viewpoints of production cost and ease of separation. The amount of base used is usually 2 to 10 moles, preferably 2 to 5 moles, and more preferably 2 to 4 moles, per mole of the dinitrobisphenol represented by the general formula (3). By using an amount of base of 2 to 10 moles, it is possible to completely remove excess base while suppressing the formation of an incompletely reacted monoester.

[0088] When carrying out the esterification reaction, an organic solvent can be used if necessary. Usable organic solvents include ketones, ethers, aromatic hydrocarbons, and halogenated aromatic hydrocarbons. Specific examples of ketones include acetone, methyl ethyl ketone, and methyl isobutyl ketone. Specific examples of ethers include 1,2-dimethoxyethane, tetrahydrofuran, and cyclopentyl methyl ether. Specific examples of aromatic hydrocarbons include benzene, toluene, and xylene. Specific examples of halogenated aromatic hydrocarbons include chlorobenzene and dichlorobenzene. Among these organic solvents, ethers are preferred. When an organic solvent is used, it is usually used in an amount of 2 to 50 parts by weight, preferably 5 to 20 parts by weight, per part by weight of the dinitrobisphenol represented by the general formula (3).

[0089] The esterification reaction is usually carried out by adding, intermittently or continuously, a solution of a dinitrobisphenol represented by the general formula (3) and a base in a solvent to a solution of a carboxylic acid halide represented by the general formula (4) above mixed with an organic solvent while stirring the solution, usually at −20° C. to 20° C., preferably −10 to 10° C., and then further carrying out the reaction at −10° C. to 50° C., preferably 0° C. to 40° C., more preferably 10° C. to 30° C. By carrying out the reaction using the above procedure and within the above temperature range, it is possible to increase the reaction rate while suppressing the production of by-products.

[0090] After the esterification reaction, for example, the resulting reaction mixture is cooled to precipitate crystals of the dinitrodiester represented by the general formula (2), and the crystals are filtered off to isolate the dinitrodiester represented by the general formula (2). The dinitrodiester represented by the general formula (2) thus obtained may be subjected to the reduction described below as is, or may be repurified using a conventional purification method (extraction, washing, adsorption, steam distillation, crystallization, column purification, etc.) before being subjected to the reduction. Furthermore, purification may be performed once or multiple times.

[0091] <Method for producing diamines represented by the above general formula (1)> Diamines represented by the general formula (1) can be obtained, for example, by reducing the nitro group of dinitrodiesters represented by the general formula (2). Examples of reduction methods include dissolving dinitrodiesters represented by the general formula (2) in methanol, ethanol, or the like, followed by reduction using a reducing agent such as tin chloride, or dissolving dinitrodiesters represented by the general formula (2) in an inert organic solvent, reducing the mixture in a hydrogen atmosphere using a catalyst in which transition metal atoms such as palladium or platinum are supported on activated carbon (hereinafter sometimes referred to as catalytic reduction). For industrial implementation, catalytic reduction is preferred because of the variety of solvents available for dissolving dinitrodiesters represented by the general formula (2), the wide range of applicable reaction temperatures, and ease of post-treatment. The catalytic reduction method is described in detail below.

[0092] The catalyst used in the catalytic reduction method is a catalyst in which transition metal atoms such as palladium or platinum are supported on activated carbon, and among these, a catalyst in which palladium is supported on activated carbon (palladium / carbon) or a catalyst in which platinum is supported on activated carbon (platinum / carbon) is preferably used because it is easy to improve the reaction rate. The amount of these catalysts used is usually 0.001 to 0.1 parts by weight, preferably 0.01 to 0.05 parts by weight, in terms of the weight of the transition metal atoms in the catalyst, per part by weight of the dinitrodiester represented by the general formula (2) above.

[0093] The organic solvent used in the catalytic reduction method may be any organic solvent that does not react with the dinitrodiesters represented by the general formula (2) above or the diamines represented by the general formula (1) above, which are the product, and that does not undergo reaction during catalytic reduction. Examples of such organic solvents include alcohols, ethers, esters, halogenated aliphatic hydrocarbons, aromatic hydrocarbons, phenols, amides, and also picoline, pyridine, dimethyl sulfoxide, 1,3-dimethyl-2-imidazolidinone, etc. Examples of alcohols include methanol and ethanol; ethers include tetrahydrofuran, 1,4-dioxane, diglyme, and triglyme; esters include ethyl acetate and γ-butyrolactone; halogenated aliphatic hydrocarbons include chloroform, dichloromethane, chloroform, and 1,2-dichloroethane; aromatic hydrocarbons include toluene and xylene; and amides include N-methyl-2-pyrrolidone, N,N-dimethylacetamide, N,N-diethylacetamide, and N,N-dimethylformamide. These organic solvents may be used alone or in combination, if necessary. Among these organic solvents, amides such as N-methyl-2-pyrrolidone, N,N-dimethylacetamide, and N,N-dimethylformamide are preferred. The amount of these organic solvents used is, for example, 2 to 10 parts by weight per part by weight of the dinitrodiester represented by the general formula (2).

[0094] The temperature when the catalytic reduction method is carried out is usually 20 to 160°C, and is preferably 20 to 100°C from the viewpoint of improving the reaction rate and suppressing the production of impurities.

[0095] When catalytic reduction is carried out, the hydrogen pressure in the reaction vessel is usually 101.3 kPa to 1013 kPa. A sufficient reduction rate can be obtained by setting the pressure at 101.3 kPa or higher, and the reaction rate can be controlled by setting the pressure at 1013 kPa or lower, making it possible to suppress unnecessary side reactions and gelation.

[0096] After carrying out the catalytic reduction method, the catalyst used in the catalytic reduction is removed by filtration, and for example, a part or all of the organic solvent is distilled off, and then a poor solvent is added as necessary to cause a precipitate to form, whereby the diamine represented by the above general formula (1) can be isolated.

[0097] The diamines represented by the general formula (1) thus obtained may be used as they are for the production of polyamic acids or polyimides, which will be described later, or may be purified using a conventional purification method (extraction, washing, adsorption, steam distillation, crystallization, column purification, etc.) and may be used afterwards. In addition, purification may be carried out once or multiple times.

[0098] <Method of producing polyamic acid of the present invention> As a method for producing the polyamic acid of the present invention, for example, the diamine represented by the above general formula (1) and the other diamines described above are dissolved in a polymerization solvent described below, and then the tetracarboxylic dianhydride powder described above is added thereto, usually at 10 to 30°C, and the mixture is stirred at 10 to 100°C, preferably 10 to 30°C, to obtain a solution in which the polyamic acid of the present invention is uniformly dissolved in the polymerization solvent (hereinafter, this may be referred to as a polyamic acid solution).

[0099] Examples of polymerization solvents used in producing the polyamic acid of the present invention include amides, linear esters, cyclic esters, carbonates, glycols, phenols, ethers, ketones, aromatic hydrocarbons, and sulfones. Examples of amides include N,N-dimethylformamide, N,N-dimethylacetamide, and N-methyl-pyrrolidone. Examples of linear esters include butyl acetate, ethyl acetate, and isobutyl acetate. Examples of cyclic esters include γ-butyrolactone, γ-caprolactone, and ε-caprolactone. Examples of carbonates include ethylene carbonate and propylene carbonate. Examples of glycols include triethylene glycol, ethyl cellosolve, butyl cellosolve, propylene glycol methyl acetate, 2-methyl cellosolve acetate, ethyl cellosolve acetate, and butyl cellosolve acetate. Examples of the polymerization solvent include ethanol, dimethoxyethane, diethoxyethane, and diethylene glycol. Examples of phenols include phenol, o-cresol, m-cresol, p-cresol, 3-chlorophenol, and 4-chlorophenol. Examples of ethers include tetrahydrofuran, dibutyl ether, and diethyl ether. Examples of ketones include methyl isobutyl ketone, diisobutyl ketone, cyclohexanone, methyl ethyl ketone, acetone, and acetophenone. Examples of aromatic hydrocarbons include xylene, toluene, and chlorobenzene. Examples of sulfones include dimethyl sulfoxide and sulfolane. Among these polymerization solvents, amides such as N,N-dimethylformamide, N,N-dimethylacetamide, and N-methylpyrrolidone are preferably used. These solvents may be used alone or in combination of two or more types, if necessary.

[0100] The amount of polymerization solvent used is such that the total concentration of the monomer components (tetracarboxylic dianhydride + diamines) in the reaction system is typically 5 to 40 wt %, preferably 10 to 30 wt %. By carrying out polymerization within this monomer concentration range, a uniform polyamic acid solution with a high degree of polymerization can be obtained. If polymerization is carried out at a concentration lower than the above-mentioned monomer concentration range, the degree of polymerization of the polyamic acid may not be sufficiently high, and the final polyimide film may be fragile. If polymerization is carried out at a concentration higher than the above-mentioned monomer concentration range, the monomer may not dissolve sufficiently or the reaction solution may become non-uniform (gelation may occur). The polyamic acid solution of the present invention obtained by the above-mentioned method is usually used directly or after being appropriately diluted with the same solvent as the polymerization solvent in the imidization reaction described below.

[0101] <Method of producing polyimide of the present invention> The polyimide of the present invention can be produced by subjecting the polyamic acid solution to a dehydration ring-closing reaction (imidization reaction). The imidization reaction can be carried out by a conventionally known method, such as a thermal imidization method or a chemical imidization method. Examples of the thermal imidization method and the chemical imidization method are shown below.

[0102] In the thermal imidization method, a polyamic acid polymer solution is first cast onto a support such as a glass plate, and then heated in vacuum, in an inert gas such as nitrogen, or in air to obtain a polyamic acid film. For example, the polyamic acid film can be obtained by drying in an oven, typically at 50 to 190°C, preferably 100 to 180°C.

[0103] Subsequently, the obtained polyamic acid film is heated on the support usually at 200 to 400°C, preferably 230 to 350°C, to carry out an imidization reaction (thermal imidization). By setting the heating temperature to 250°C or higher, the thermal imidization reaction can be sufficiently promoted, while by setting the heating temperature to 400°C or lower, polyimide can be obtained while suppressing thermal decomposition. The thermal imidization reaction is preferably carried out in a vacuum or in an inert gas, but may be carried out in air as long as the imidization reaction temperature is 300°C or lower.

[0104] On the other hand, in the chemical imidization method, the same solvent as used in polymerization is added to the polyamic acid solution of the present invention obtained by the above method to adjust the solution viscosity to an appropriate level for easy stirring, and then a dehydration ring-closing agent (chemical imidization agent) consisting of an organic acid anhydride and a tertiary amine as a basic catalyst is added dropwise while stirring, and the mixture is further stirred at 0 to 100°C, preferably 10 to 50°C, to complete the chemical imidization.

[0105] Examples of organic acid anhydrides that can be used in chemical imidization include acetic anhydride and propionic anhydride. Among these organic acid anhydrides, acetic anhydride is preferred due to its ease of handling and separation. Examples of basic catalysts that can be used in chemical imidization include pyridine, triethylamine, and quinoline. Among these basic catalysts, pyridine is preferred due to its ease of handling and separation. The amount of organic acid anhydride in the chemical imidization agent is 1 to 10 mol, more preferably 2 to 5 mol, per mol of the theoretical dehydration amount of polyamic acid. The amount of basic catalyst is 0.1 to 3 mol, more preferably 0.2 to 2 mol, per mol of organic acid anhydride.

[0106] The reaction solution of chemical imidization contains unreacted chemical imidizing agent, organic acid, by-products, etc. (hereinafter referred to as impurities), so these may be removed to isolate and purify the polyimide. A known purification method can be used. For example, the reaction solution of chemical imidization is dropped into a large amount of poor solvent while being stirred to precipitate the polyimide, and the polyimide powder is then recovered, washed repeatedly until the impurities are removed, and dried under reduced pressure to obtain the polyimide powder.

[0107] The poor solvent that can be used in the above method may be any solvent that can precipitate polyimide, efficiently remove impurities, and is easy to dry. For example, water and alcohols such as methanol, ethanol, and isopropanol are suitable, and these may be used in combination.

[0108] If the concentration of the polyimide solution when dropped into a poor solvent to precipitate the polyimide is too high, the precipitated polyimide may form agglomerates, and impurities may remain in the coarse particles, or it may take a long time to redissolve the resulting polyimide powder in a solvent. Therefore, the solids concentration of the polyimide solution when dropped into a poor solvent is usually 20% by weight or less, more preferably 10% by weight or less. The amount of poor solvent used is preferably 1 part by weight or more, more preferably 1.5 to 10 parts by weight, per part by weight of the polyimide solution.

[0109] The temperature at which the resulting polyimide powder is recovered and the residual solvent is removed by vacuum drying or hot air drying is not particularly limited as long as the polyimide is not altered, and is preferably 30 to 150°C.

[0110] The chemical imidization reaction can be carried out, for example, by coating a support such as a glass plate with a polyamic acid to form a film, and then immersing the film in a solution containing an organic acid anhydride such as acetic anhydride in the presence of a tertiary amine such as pyridine or triethylamine. This procedure can produce a partially or almost completely imidized polyimide film, which can then be further heat-treated, for example, in an oven at typically 200 to 400°C, preferably 250 to 350°C, to produce a completely imidized polyimide film.

[0111] <Polyimide Solution of the Present Invention> The polyimide of the present invention obtained by the above method can be dissolved in any organic solvent to form a polyimide solution.

[0112] Examples of organic solvents that can be used in preparing the polyimide solution of the present invention include amides, esters, carbonates, glycols, phenols, ketones, and ethers. Examples of amides include N,N-dimethylformamide, N,N-dimethylacetamide, and N-methyl-2-pyrrolidone. Examples of esters include γ-butyrolactone, γ-valerolactone, δ-valerolactone, γ-caprolactone, ε-caprolactone, α-methyl-γ-butyrolactone, butyl acetate, ethyl acetate, and isobutyl acetate. Examples of carbonates include ethylene carbonate and propylene carbonate. Examples of glycols include diethylene glycol dimethyl ether, triethylene glycol, and triethylene glycol dimethyl ether. Examples of phenols include phenol, m-cresol, p-cresol, o-cresol, 3-chlorophenol, and 4-chlorophenol. Examples of ketones include cyclopentanone, cyclohexanone, acetone, methyl ethyl ketone, diisobutyl ketone, and methyl isobutyl ketone. Examples of ethers include tetrahydrofuran, 1,4-dioxane, dimethoxyethane, diethoxyethane, dibutyl ether, methyl monoglyme (1,2-dimethoxyethane), methyl diglyme (bis(2-methoxyethyl)ether), and methyl triglyme (1,2-bis(2-methoxyethoxy)ethane). Other common solvents include acetophenone, 1,3-dimethyl-2-imidazolidinone, sulfolane, dimethyl sulfoxide, propylene glycol methyl acetate, ethyl cellosolve, butyl cellosolve, 2-methyl cellosolve acetate, ethyl cellosolve acetate, butyl cellosolve acetate, xylene, toluene, chlorobenzene, turpentine, mineral spirits, and petroleum naphtha. These organic solvents may be used alone or in combination of two or more kinds, if necessary.

[0113] Among these organic solvents, amides (N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), and N-methyl-2-pyrrolidone (NMP)), ketones (methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), cyclopentanone, and cyclohexanone), and ethers (methyl monoglyme (1,2-dimethoxyethane), methyl diglyme (bis(2-methoxyethyl)ether), and methyl triglyme (1,2-bis(2-methoxyethoxy)ethane)) are preferred. The concentration of the polyimide solution of the present invention is preferably 5 to 40 wt %, and more preferably 5 to 20 wt %, from the viewpoint of ensuring the smoothness of the film when the polyimide film is produced by the method described below.

[0114] <Method of manufacturing polyimide film> The polyimide of the present invention obtained by the above-mentioned method can be formed into a film by any method, for example, a method in which a polyamic acid film is produced by the above-mentioned method and then a polyimide film is formed by thermal imidization or chemical imidization, or a method in which the above-mentioned polyimide solution of the present invention is applied (also referred to as coating) onto a support, dried, and then peeled off from the support can be selected.

[0115] The support on which the polyimide solution is applied may be, but is not limited to, a glass substrate, a metal substrate such as stainless steel, a metal belt, or a plastic film such as polyethylene terephthalate, polycarbonate, polyacrylate, polyethylene naphthalate, or triacetyl cellulose. To accommodate current batch-type device manufacturing processes, a glass substrate is preferred.

[0116] After the polyimide solution is applied to the support, the conditions for drying the polyimide film can be appropriately selected according to the process. Specifically, for example, the polyimide solution can be applied to the support, followed by heat treatment at 150°C for 1 hour, and then further heat treatment at 250°C for 1 hour.

[0117] <Use of the polyimide of the present invention> The polyimide of the present invention can be used, for example, in circuit boards, color filters, printed materials, optical materials, electronic devices, image display devices, etc. Furthermore, it can be used as a substitute material for parts where glass or transparent materials are currently used.

[0118] Examples of the substrate include a TFT substrate, a flexible display substrate, and a transparent conductive film substrate. Examples of the electronic device include a touch panel and a solar cell. Examples of the image display device include a flexible display, a liquid crystal display, an organic electroluminescence (EL) display, an electronic paper display, and a 3D display.

[0119] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention. Furthermore, new technical features can be formed by combining the technical means disclosed in each embodiment. [Example]

[0120] Examples of the present invention are shown below, but the present invention is not limited to these. The values ​​shown in each example, synthesis example, and comparative example are values ​​obtained by the following analytical methods.

[0121] [1] 1 H-NMR measurement The compounds of the present invention 1 H-NMR spectra were measured with a JNM-ECP400 (manufactured by JEOL) using tetramethylsilane as an internal standard and deuterated dimethyl sulfoxide (DMSO-d6) as a solvent.

[0122] [2] Infrared absorption spectrum The infrared absorption spectrum of the diamine of the present invention was measured by the KBr plate method using a Fourier transform infrared spectrophotometer (FT-IR4100 manufactured by JASCO Corporation).

[0123] [3] Elemental analysis Elemental analysis was performed using an organic trace elemental analyzer (JM10) manufactured by J Science Labs, Inc.

[0124] [4] Differential scanning calorimetry (melting point measurement) The melting points of the compounds of the present invention were determined from the endothermic peak temperature of melting by measuring at a temperature rise rate of 5°C / min in a nitrogen atmosphere using a differential scanning calorimeter DSC3100 (manufactured by NETZSCH).

[0125] [5] Intrinsic viscosity The reduced viscosity of a polyamic acid or polyimide prepared as a solution in N,N-dimethylacetamide (DMAc) with a solute concentration of 0.5% by weight was measured at 30°C using an Ostwald viscometer (Shibata Scientific Viscometer No. 1). This value was considered to be the intrinsic viscosity.

[0126] [6] Coefficient of linear thermal expansion: CTE The polyimide film size was 5 mm wide and 20 mm long, and the load (static load) was set to film thickness (μm) x 0.5 g weight, using a NETZSCH TMA4000. The linear thermal expansion coefficient of the polyimide film was calculated by first heating the polyimide film to 150°C at 5°C / min (first heating), then cooling to 20°C, and then heating it again at 5°C / min (second heating), from the TMA curve at the second heating. The linear thermal expansion coefficient was calculated as the average value between 100 and 200°C.

[0127] [7] Total light transmittance: TT The total light transmittance (TT) of the polyimide film was determined in accordance with JIS K7361 using a Haze Meter NDH4000 (manufactured by Nippon Denshoku Industries Co., Ltd.).

[0128] [8] Glass transition temperature: T g A polyimide film with a width of 5 mm, a length of 20 mm, and a thickness of approximately 20 μm was used as a test piece. Dynamic viscoelasticity measurements were performed in a nitrogen atmosphere using a TA Instruments DMA-Q800 at a frequency of 0.1 Hz and a heating rate of 5°C / min. The temperature at which the loss modulus reached its maximum was determined as the glass transition temperature (T g ) was decided.

[0129] [9] Thickness direction birefringence: Δn Using an Abbe refractometer 4T (ATAGO) with a polarizing plate, NaD line (589.3 nm) as the light source, a solution saturated with sulfur in methylene iodide (nD = 1.72-1.80) as the intermediate solution, and a test piece (nD = 1.72), the in-plane refractive index n of the polyimide film was measured. in and the out-of-plane refractive index n out and the thickness direction birefringence Δn (= n in -n out ) was sought.

[0130] 1. Production examples of diamines represented by the above general formula (1)

[0131] Example 1 Among the dinitrobisphenols represented by the above general formula (3), a production example of dinitrobisphenol represented by the following formula (3-1)

[0132] [ka] A 300 mL three-neck flask was charged with 5.41 g (20.0 mmol) of 2,7-dinitro-9-fluorenone, 13.23 g (120.2 mmol) of resorcinol, 0.35 g (2.06 mmol) of p-toluenesulfonic acid monohydrate, and 150 mL of toluene. The resulting suspension was heated to reflux at 110 °C under a nitrogen atmosphere while stirring. After 6.5 hours of reaction, the disappearance of the starting material spot was confirmed by TLC, marking the end of the reaction. The reaction mixture was added dropwise to a large amount of water to precipitate a precipitate. This precipitate was filtered, thoroughly washed with water, and vacuum dried at 120 °C for 12 hours to obtain a yellowish-brown crude product (85% yield).

[0133] Next, this crude product was subjected to column purification as follows. 5.02 g of the crude product was dissolved in 63 mL of acetone, and 15 g of silica gel (Wakogel, C-300) was added to this solution and stirred thoroughly. The solvent was then completely removed using an evaporator, and the crude product was adsorbed onto the silica gel. This was charged to the top of a silica gel column, and a separation operation was carried out using ethyl acetate / hexane (volume ratio 1 / 1) as the developing solvent. The solvent in the eluate was removed using an evaporator, and the mixture was dried in vacuo at 100°C for 12 hours to obtain a yellow powder (column purification yield 45%, total yield 34%). The product was then washed with methanol and ethyl acetate and dried. The analytical results of the obtained product are shown below.

[0134] Melting point: 157°C (DSC), FT-IR spectrum (KBr plate method, cm -1 ):3483(OH stretching vibration), 3067(C arom -H), 1518 / 1340 (NO2), 1211 (xanthene group, COC), 1 H-NMR spectrum (400 MHz, DMSO-d6, δ, ppm): 9.82 (s, 2H (relative integrated intensity 2.00H), OH), 8.45 (d, 2H (2.08H), J = 8.4 Hz, 4,5-protons of fluorene group), 8.37 (dd, 2H (2.05H), J = 8.5, 2.1 Hz, 3,6-protons of fluorene group), 7.81 (sd, 2H (2 .09H), J = 2.0Hz, 1,8-proton of fluorene group), 6.67 (sd, 2H (2.08H), J = 2.4Hz, 4,5-proton of xanthene group), 6.31 (dd, 2H (2.03H), J = 8.6, 2.5Hz, 2,7-proton of xanthene group), 6.12 (d, 2H (2.06H), J = 8.6Hz, 1,8-proton of xanthene group), Elemental analysis (C 25 H 14 O7N2, molecular weight 454.40): Estimated values ​​(%) C: 66.08, H: 3.11, N: 6.17, Analytical values ​​C: 65.89, H: 3.29, N: 6.20.

[0135] <Example 2> Among the dinitrodiesters represented by the above general formula (2), a production example of a dinitrodiester represented by the following formula (2-1)

[0136] [ka]

[0137] A 100 mL three-neck flask was charged with 2.74 g (6.02 mmol) of dinitrobisphenol (3-1), 20 mL of dehydrated tetrahydrofuran (THF), and 1.12 mL of pyridine as a deoxidizer. The flask was then capped with a septum to form Solution A. Solution A was then immersed in an ice bath at 0°C, and 2.7 mL (18.25 mmol) of 4-(trifluoromethyl)benzoyl chloride (4-TFBC) was slowly added dropwise via syringe. The mixture was stirred for several hours and then at room temperature for 12 hours. The resulting white pyridine hydrochloride was separated by filtration, and the filtrate was slowly added dropwise to 1 L of hexane to precipitate. The precipitate was filtered, thoroughly washed with hexane and water, and then vacuum dried at 100°C for 12 hours (89% yield). The analytical results of the resulting product are shown below.

[0138] Melting point: 283°C (DSC), FT-IR spectrum (KBr plate method, cm -1 ):3091(C arom -H), 1749 (ester group, C=O), 1528 / 1325 (NO2), 1490 (1,4-phenylene), 1H-NMR spectrum (400 MHz, DMSO-d6, δ, ppm): 8.55 (d, 2H (2.07H), J = 8.5 Hz, 4,5-protons of the fluorene group), 8.46 (dd, 2H (2.02H), J = 8.5, 2.1 Hz, 3,6-protons of the fluorene group), 8.31 (d, 4H (4.21H), J = 8.2 Hz, 2,2',6,6'-protons of the terminal benzoate group), 8.07 (sd, 2H (2.02H), J = 2.1 Hz, 1,8-protons of the fluorene group), 7.99 (d, 4H (4.25H), J = 8.5 Hz, 3,3', 5,5'-protons of the terminal benzoate group), 7.50 (sd, 2H (2.00H), J = 2.4 Hz, 4,5-protons of the xanthene group), 6.93 (dd, 2H (2.00H), J = 8.6, 2.4 Hz, 2,7-protons of the xanthene group), 6.50 (d, 2H (1.96H), J = 8.6 Hz, 1,8-protons of the xanthene group), Elemental analysis (C 41 H 20 O9N2F6, molecular weight 798.61): Estimated values ​​(%) C: 61.66, H: 2.52, N: 3.51, Analytical values ​​C: 61.53, H: 2.68, N: 3.63.

[0139] Example 3 Among the diamines represented by the above general formula (1), a production example of a diamine represented by the following formula (1-1)

[0140] [ka] A 100 mL three-neck flask was charged with 3.21 g (4.01 mmol) of the dinitrodiester represented by formula (2-1), 30 mL of ethanol, 30 mL of N,N-dimethylformamide (DMF), and 0.34 g of Pd / C as a catalyst, and refluxed at 80 °C in a hydrogen atmosphere. After 5 hours of reaction, the reaction was terminated when the disappearance of the dinitrodiester was confirmed by TLC. After the reaction, the mixture was cooled to room temperature, and the Pd / C residue was separated by filtration. The filtrate was added dropwise to a large amount of water to precipitate a pale yellow powder. The precipitate was filtered and dried in vacuo at 100 °C for 12 hours, yielding a crude product as a pale yellow powder (83% yield). The obtained crude product was subjected to column purification (eluent: ethyl acetate / hexane = 1 / 2 volume ratio) in the same manner as in Example 1, and the eluate was concentrated using an evaporator to obtain an oily product. This was diluted with a small amount of ethanol and then added dropwise to a large amount of water to precipitate. The precipitate was filtered, washed thoroughly with water, and then vacuum dried at 40 °C for 12 hours to obtain a purified product (column purification yield 80%). The analytical results of the obtained product are shown below, and the composition of the obtained diamine is shown in Figure 1. 1 The H-NMR spectrum (solvent: DMSO-d6) of the obtained diamine is shown in Figure 2. 1 The 1 H-NMR spectrum (solvent: DMSO-d6) is shown enlarged around 6.2 to 8.4 ppm, and the FT-IR spectrum is shown in FIG.

[0141] FT-IR spectrum (KBr plate method, cm -1 ): 3467 / 3378 / 3219 (amino group, NH), 3071 / 3035 / 3008 (C arom -H), 1743 (ester group, C=O), 1489 (1,4-phenylene), 1326 (trifluoromethyl group, CF), 1262 (xanthene group, COC), 1 H-NMR spectrum (400 MHz, DMSO-d6, δ, ppm): 8.32 (d, 4H (4.36H), J = 8.2 Hz, 2,2',6,6'-protons of the terminal benzoate group), 8.00 (d, 4H (4.21H), J = 8.4 Hz, 3,3',5,5'-protons of the terminal benzoate group), 7.39 (d, 2H (2.01H), J = 8.1 Hz, 4,5-protons of the fluorene group), 7.34 (sd, 2H (2.00H), J = 2.4 Hz, 3,3',5,5'-protons of the terminal benzoate group). 4,5-protons), 6.91 (dd, 2H (2.19H), J = 8.6, 2.3 Hz, 2,7-protons of the xanthene group), 6.55 (dd, 2H (2.12H), J = 8.1, 2.0 Hz, 3,6-protons of the fluorene group), 6.49 (d, 2H (2.11H), J = 8.6 Hz, 1,8-protons of the xanthene group), 6.30 (sd, 2H (2.19H), J = 2.0 Hz, 1,8-protons of the fluorene group), 5.06 (s, 4H (3.95H), NH2), Elemental analysis (C41 H 24 O5N2F6, molecular weight 738.64): Estimated values ​​(%) C: 66.67, H: 3.28, N: 3.79, Analytical values ​​C: 66.22, H: 3.35, N: 3.75. <Synthesis Example 1> Preparation example of dinitro compound represented by the following formula (2-2)

[0142] [ka] A 300 mL three-neck flask was charged with 5.77 g (12.71 mmol) of dinitrobisphenol represented by formula (3-1) described in Example 1, 5.81 mL (63.54 mmol) of 1-bromopropane, 81 mL of DMF, and 4.22 g (30.52 mmol) of potassium carbonate, and refluxed at 65°C under a nitrogen atmosphere. After 4 hours, the disappearance of the raw material spot was confirmed by TLC, marking the end of the reaction. After cooling to room temperature, the reaction mixture was added dropwise to a large amount of water to precipitate a yellow powder, which was filtered, washed with water, and dried in vacuo at 80°C for 12 hours, yielding a yellow powder (94% yield). Next, to purify this product using a column, 3.77 g (7.00 mmol) of this product was dissolved in 80 mL of acetone, to which 12 g of silica gel (Wakogel, C-300) was added. After thorough stirring, the solvent was completely removed using an evaporator, and the product was adsorbed onto the silica gel. This was charged to the top of a silica gel column, and separation was performed using ethyl acetate / hexane (volume ratio 1 / 3) as the developing solvent. The solvent from the eluate was removed using an evaporator, and the mixture was dried in vacuum at 80 °C for 12 hours to obtain a yellow powder (column purification yield 63%). The analytical results of the obtained product are shown below.

[0143] Melting point: 232°C (DSC), FT-IR spectrum (KBr plate method, cm -1 ):3086(C arom -H), 2966 / 2878(C aliph -H), 1523 / 1340(NO2), 1261(C aliph -O), 1H-NMR spectrum (400 MHz, DMSO-d6, δ, ppm): 8.48 (d, 2H (2.06H), J = 8.5 Hz, 4,5-protons of the fluorene group), 8.39 (dd, 2H (2.11H), J = 8.4, 2.1 Hz, 3,6-protons of the fluorene group), 7.83 (sd, 2H (2.00H), J = 2.1 Hz, 1,8-protons of the fluorene group), 6.87 (sd, 2H (2.02H), J = 2.1 Hz, 4,5-protons of the xanthene group). -proton), 6.46 (dd, 2H(1.99H), J=8.7, 2.5 Hz, 2,7-proton of the xanthene group), 6.22 (d, 2H(2.02H), J=8.7 Hz, 1,8-proton of the xanthene group), 3.93 (t, 4H(4.06H), J=6.5 Hz, O-CH2), 1.70 (sextet, 4H(4.26H), J=6.9 Hz, OC-CH2), 0.95 (t, 6H(6.39H), J=7.4 Hz, O-C-CH3).

[0144] <Synthesis Example 2> Production example of diamine represented by the following formula (1-2)

[0145] [ka] A 100 mL three-neck flask was charged with 1.35 g (2.50 mmol) of the dinitro compound represented by formula (2-2), 33 mL of ethanol, 10 mL of DMF, and Pd / C (0.14 g), and refluxed at 70°C in a hydrogen atmosphere. After 2 hours of reaction, the reaction was terminated when TLC confirmed the disappearance of the dinitro compound. After the reaction, the mixture was cooled to room temperature, and the Pd / C residue was separated by filtration. The filtrate was added dropwise to a large amount of water to precipitate a pale pink powder. The precipitate was filtered and dried in vacuo at 45°C for 12 hours, yielding a pale pink powder (68% yield). The analytical results of the resulting product are shown below.

[0146] FT-IR spectrum (KBr plate method, cm -1 ): 3451 / 3371 (amino group, NH), 3032 (C arom -H), 2964 / 2934 / 2875(C aliph -H), 1254(C aliph -O), 1 H-NMR spectrum (400 MHz, DMSO-d6, δ, ppm): 7.31 (d, 2H (1.97H), J = 8.0 Hz, 4,5-proton of fluorene group), 6.71 (sd, 2H (2.00H), J = 2.2 Hz, 4,5-proton of xanthene group), 6.48-6.46 (m, 4H (4.12H), 1,8-+2,7-proton of xanthene group), 6.23 (d, 2H (2.06H), J = 8.7 Hz) , 3,6-protons of the fluorene group), 6.16 (sd (insufficiently resolved), 2H (1.98H), 1,8-protons of the fluorene group), 4.93 (s, 4H (3.83H), NH2), 3.91 (t, 4H (4.34H), J = 6.5 Hz, O-CH2), 1.70 (sextet, 4H (4.32H), J = 7.0 Hz, OC-CH2), 0.96 (t, 6H (6.43H), J = 7.4 Hz, OCC-CH3). <Synthesis Example 3> Preparation example of dinitro compound represented by the following formula (2-3)

[0147] [ka] Except for using 1-bromohexane instead of 1-bromopropane, the product was synthesized and purified in the same manner as in Synthesis Example 1. The analytical results of the obtained product are shown below.

[0148] Melting point: 135°C (DSC), FT-IR spectrum (KBr plate method, cm -1 ):3082(C arom -H), 2953 / 2928 / 2870(C aliph -H), 1522 / 1340(NO2), 1259(C aliph -O), 1H-NMR spectrum (400 MHz, DMSO-d6, δ, ppm): 8.47 (d, 2H(2.00H), J = 8.4 Hz, 4,5-protons of the fluorene group), 8.39 (dd, 2H(2.00H), J = 8.5, 2.1 Hz, 3,6-protons of the fluorene group), 7.83 (sd, 2H(2.07H), J = 2.1 Hz, 1,8-protons of the fluorene group), 6.87 (sd, 2H(2.08H), J = 2.5 Hz, 4,5-protons of the xanthene group), 6.47 (dd, 2H( 2.06H), J = 8.8, 2.5 Hz, 2,7-proton of xanthene group), 6.21 (d, 2H (2.02H), J = 8.7 Hz, 1,8-proton of xanthene group), 3.96 (t, 4H (4.02H), J = 6.4 Hz, O-CH2), 1.68 (quin, 4H (4.06H), J = 7.3 Hz, OC-CH2), 1.42-1.26 (m, 12H (12.12H), OCC-(CH2)3), 0.86 (t, 6H (6.01H), J = 7.0 Hz, OCCCCC-CH3), Elemental analysis (C 37 H 38 O7N2, molecular weight 622.72): Estimated values ​​(%) C: 71.37, H: 6.15, N: 4.50, Analytical values ​​C: 71.18, H: 6.21, N: 4.45.

[0149] <Synthesis Example 4> Production example of diamine represented by the following formula (1-3)

[0150] [ka] The dinitro compound represented by the above formula (2-3) was synthesized by hydrogen reduction in the same manner as described in Synthesis Example 2. The analytical results of the obtained product are shown below.

[0151] Melting point: 50°C (DSC), FT-IR spectrum (KBr plate method, cm -1 ): 3462 / 3374 / 3213 (amino group, NH), 3032 (C arom -H), 2953 / 2930 / 2859(C aliph -H), 1254(Caliph -O), 1 H-NMR spectrum (400 MHz, DMSO-d6, δ, ppm): 7.31 (d, 2H (2.00H), J = 8.1 Hz, 4,5-proton of fluorene group), 6.71 (sd, 2H (2.06H), J = 2.6 Hz, 4,5-proton of xanthene group), 6.48-6.44 (m, 4H (4.29H), 1,8-+2,7-proton of xanthene group), 6.22 (d, 2H (2.06H), J = 8.7 Hz, 3,6-proton of fluorene group). 6.15(sd, 2H(2.09H), =2.0Hz, fluorene group 1,8-proton), 4.93(s, 4H(4.02H), NH2), 3.93(t, 4H(4.57H), J=6.5Hz, O-CH2), 1.68(qu in, 4H(4.62H), J=7.3Hz, OC-CH2), 1.39-1.29(m, 12H(13.69H), OCC-(CH2)3), 0.87(t, 6H(6.70H), J=7.1Hz, OCCCCC-CH3), Elemental analysis (C 37 H 42 O3N2, molecular weight 562.75): Estimated values ​​(%) C: 78.97, H: 7.52, N: 4.98, Analytical values ​​C: 78.74, H: 7.61, N: 4.95.

[0152] <Synthesis Example 5> Preparation example of dinitro compound represented by the following formula (2-4)

[0153] [ka] Except for using 1-bromo-2-ethylhexane instead of 1-bromopropane, synthesis and purification were carried out in the same manner as in Synthesis Example 1. The analytical results of the obtained product are shown below.

[0154] Melting point: 114°C (DSC), FT-IR spectrum (KBr plate method, cm -1 ):3088(C arom -H), 2958 / 2929 / 2872(C aliph-H), 1523 / 1341(NO2), 1254(C aliph -O), 1 H-NMR spectrum (400 MHz, DMSO-d6, δ, ppm): 8.48 (d, 2H (2.10H), J = 8.5 Hz, 4,5-protons of the fluorene group), 8.39 (dd, 2H (2.02H), J = 8.5, 2.1 Hz, 3,6-protons of the fluorene group), 7.83 (sd, 2H (2.00H), J = 2.1 Hz, 1,8-protons of the fluorene group), 6.86 (sd, 2H (2.15H), J = 2.5 Hz, 4,5-protons of the xanthene group), 6.46 ( dd, 2H (2.06H), J = 8.8, 2.6 Hz, 2,7-protons of the xanthene group), 6.20 (d, 2H (2.10H), J = 8.8 Hz, 1,8-protons of the xanthene group), 3.84 (d, 4H (4.35H), J = 5.6 Hz, O-CH2), 1.65-1.60 (m, 2H (2.04H), OC-CH), 1.43-1.25 (m, 16H (20.24H), OCC-(CH2)4), 0.88-0.82 (m, 12H (14.85H), terminal CH3).

[0155] <Synthesis Example 6> Production example of diamine represented by the following formula (1-4)

[0156] [ka] The dinitro compound represented by the above formula (2-4) was synthesized by hydrogen reduction in the same manner as described in Synthesis Example 2. The analytical results of the obtained product are shown below.

[0157] FT-IR spectrum (KBr plate method, cm -1 ): 3464 / 3375 / 3213 (amino group, NH), 3029 (C arom -H), 2958 / 2927 / 2872(C aliph -H), 1255(C aliph -O), 1H-NMR spectrum (400 MHz, DMSO-d6, δ, ppm): 7.31 (d, 2H (2.06H), J = 8.0 Hz, 4,5-proton of fluorene group), 6.72 (sd, 2H (2.00H), J = 2.5 Hz, 4,5-proton of xanthene group), 6.49-6.46 (m, 4H (4.24H), 1,8-+2,7-proton of xanthene group), 6.23 (d, 2H (2.09H), J = 8.7 Hz, 3,6-proton of fluorene group). -proton), 6.16 (sd, 2H (2.14H), = 2.0 Hz, fluorene group 1,8-proton), 4.93 (s, 4H (4.27H), NH2), 3.84 (d, 4H (4.06H), J = 5.7 Hz, O-CH2), 1.67-1.63 (m, 2H (2.12H), OC-CH), 1.45-1.28 (m, 16H (18.18H), OCC-(CH2)4), 0.90-0.86 (m, 12H (14.02H), terminal CH3). Elemental analysis (C 41 H 50 O3N2, molecular weight 618.86): Estimated values ​​(%) C: 79.57, H: 8.14, N: 4.53, Analytical values ​​C: 79.15, H: 8.06, N: 4.55.

[0158] 2. Production Examples of Polyimides of the Present Invention

[0159] Example 4 A well-dried, sealed reaction vessel was charged with 0.7 mmol of the diamine represented by formula (1-1) and 0.3 mmol of 2,2'-bis(trifluoromethyl)benzidine (TFMB). N,N-dimethylacetamide (DMAc) thoroughly dehydrated with molecular sieves 4A was then added and dissolved. To this solution, 1 mmol of 1,2,3,4-cyclobutanetetracarboxylic dianhydride (CBDA) powder was added, initiating the polymerization reaction at an initial total solute concentration of 40 wt%. After the reaction started, the mixture was stirred at room temperature for 72 hours, resulting in a homogeneous, viscous polyamic acid solution. During the reaction, the solution viscosity increased excessively, so additional DMAc was added to achieve a final solute concentration of 36 wt%.

[0160] After the reaction was completed, the intrinsic viscosity of the polyamic acid was measured in DMAc at 30° C. at a concentration of 0.5% by weight using an Ostwald viscometer, and the intrinsic viscosity was found to be 0.75 dL / g.

[0161] Next, the polyamic acid solution obtained as described above was diluted with DMAc to a 10 wt% solution, and a chemical imidization agent (acetic anhydride / pyridine, volume ratio: 7 / 3) containing acetic anhydride in an amount five times the theoretical dehydration amount was added dropwise. The solution was stirred at room temperature for 24 hours to carry out the chemical imidization reaction. The reaction solution remained homogeneous throughout the chemical imidization. After chemical imidization was completed, the reaction solution was appropriately diluted with DMAc and slowly added dropwise to a large amount of methanol to precipitate a fibrous polyimide powder. This was filtered, washed, and vacuum-dried at 120°C for 12 hours to isolate a white fibrous polyimide powder. This polyimide powder was dissolved in DMSO-d6. 1 H-NMR spectroscopy revealed that the amide proton signal at approximately δ10 ppm and the COOH proton signal at approximately δ13 ppm derived from the polyamic acid had completely disappeared, confirming the completion of the chemical imidization reaction. The intrinsic viscosity of the resulting polyimide powder was 2.27 dL / g. The results of a solubility test of the resulting polyimide powder (dissolving approximately 10 mg of polyimide in 1 mL of each solvent) are shown in Table 1.

[0162] The resulting polyimide powder was then redissolved in DMAc to obtain a homogeneous polyimide solution with a solids concentration of 15 wt%. This solution was applied to a glass substrate and pre-dried in a hot air oven at 60°C for 2 hours. After that, the substrate was dried in a vacuum at 250°C for 1 hour. The film was then peeled off from the substrate and heat-treated at 275°C for 1 hour to remove residual strain, yielding a clear, free-standing film with a thickness of approximately 20 μm. The physical properties of the resulting polyimide film are shown in Tables 2 and 3.

[0163] <Example 5> Polymerization and chemical imidization were carried out in the same manner as in Example 4, except that the amounts of the diamine represented by the above formula (1-1) and TFMB used were each 0.5 mmol, to obtain a polyimide powder. The results of the solubility test of the obtained polyimide powder are shown in Table 1. Furthermore, a polyimide film was obtained from the obtained polyimide powder in the same manner as in Example 4. The physical properties of the obtained polyimide film are shown in Tables 2 and 3.

[0164] <Comparative Example 1> Polyamic acid was polymerized in the same manner as in Example 4, except that TFMB alone (0.1 mmol) was used as the diamine. Chemical imidization of the resulting polyamic acid was attempted in the same manner as in Example 4, but the reaction solution gelled and a partial precipitate formed, making chemical imidization impossible. Therefore, the polyamic acid solution was applied to a glass substrate, pre-dried at 60°C for 2 hours, and then heated in a vacuum at 200°C for 1 hour and then at 300°C for 1 hour for thermal imidization. The polyimide film was then peeled off from the glass substrate and heat-treated at 304°C to remove residual strain, yielding a polyimide film. The results of the solubility test of the resulting polyimide film are shown in Table 1, and its physical properties are shown in Table 2.

[0165] <Comparative Example 2> Polymerization and chemical imidization were carried out in accordance with Example 4, except that 1.0 mmol of the diamine represented by the above formula (1-2) and 1.0 mmol of TFMB were used as the diamine. The powder that had been chemically imidized had poor solubility in DMAc, and when it was dissolved in a large amount of solvent and formed into a film, turbidity was observed in some parts of the film, and some powder precipitation was also observed, making it difficult to obtain a uniform film by chemical imidization.

[0166] Therefore, a polyamic acid solution was applied to a glass substrate and dried in a hot air dryer at 150°C for 30 minutes, 200°C for 30 minutes, and 300°C for 1 hour to carry out thermal imidization separately, and a polyimide film was obtained by removing residual strain in the same manner as in Comparative Example 1. The physical properties of the obtained polyimide film are shown in Table 2.

[0167] <Comparative Example 3> Polymerization and chemical imidization were carried out in accordance with Example 4, except that 1.4 mmol of the diamine represented by the above formula (1-3) and 0.6 mmol of TFMB were used as the diamine. The powder that had been chemically imidized had poor solubility in DMAc, and when it was dissolved in a large amount of solvent and formed into a film, turbidity was observed in some parts of the film, and some powder precipitation was also observed, making it difficult to obtain a uniform film by chemical imidization.

[0168] Therefore, a polyamic acid solution was applied to a glass substrate and dried in a hot air dryer at 150°C for 30 minutes, 200°C for 30 minutes, and 300°C for 1 hour to carry out thermal imidization separately, and a polyimide film was obtained by removing residual strain in the same manner as in Comparative Example 1. The physical properties of the obtained polyimide film are shown in Table 2.

[0169] <Comparative Example 4> Polymerization and chemical imidization were carried out in accordance with Example 4, except that 1.4 mmol of the diamine represented by the above formula (1-4) and 0.6 mmol of TFMB were used as the diamine. The powder that had been chemically imidized had poor solubility in DMAc, and when it was dissolved in a large amount of solvent and formed into a film, turbidity was observed in some parts of the film, and some powder precipitation was also observed, making it difficult to obtain a uniform film by chemical imidization.

[0170] Therefore, a polyamic acid solution was applied to a glass substrate and dried in a hot air dryer at 150°C for 30 minutes, 200°C for 30 minutes, and 300°C for 1 hour to carry out thermal imidization separately, and a polyimide film was obtained by removing residual strain in the same manner as in Comparative Example 1. The physical properties of the obtained polyimide film are shown in Table 2.

[0171] [Table 1]

[0172] In Table 1, NMP stands for N-methyl-2-pyrrolidone, DMAc stands for N,N-dimethylacetamide, DMF stands for N,N-dimethylformamide, DMSO stands for dimethyl sulfoxide, GBL stands for γ-butyrolactone, CPN stands for cyclopentanone, and Tri-GL stands for triethylene glycol dimethyl ether. ++ stands for soluble at room temperature, + stands for soluble upon heating, and - stands for insoluble upon heating.

[0173] [Table 2]

[0174] [Table 3]

[0175] In Tables 2 and 3, the values ​​in parentheses indicate the film thickness when each property was measured.

Claims

1. A polyimide containing a diamine-derived structural unit represented by the following formula (1-1) in the main chain: 【Chemistry 1】

2. The polyimide according to claim 1, having a repeating unit represented by the following general formula (P-1-1): 【Chemistry 2】 (In the above general formula (P-1-1), A １ represents a tetravalent aliphatic group.

3. The polyimide according to claim 1 or 2, further comprising a repeating unit represented by the following general formula (P-2): 【Transformation 3】 (In the above general formula (P-2), A １ represents a tetravalent aliphatic group. ２ is a divalent aromatic group having a substituent containing a fluorine atom.

4. A polyamic acid containing a diamine-derived structural unit represented by the following formula (1-1) in the main chain: 【Chemistry 4】

5. A diamine represented by the following formula (1-1): 【Transformation 5】

6. The following formula (2-1): 【Transformation 6】 The method for producing a diamine according to claim 5, wherein a dinitrodiester represented by the following formula (I) is reduced.

7. A dinitrodiester represented by the following formula (2-1): 【Transformation 7】

8. Dinitrobisphenol represented by the following formula (3-1): 【Transformation 8】

9. A polyimide solution comprising the polyimide according to any one of claims 1 to 3 and an organic solvent.

10. A polyimide film comprising the polyimide according to any one of claims 1 to 3.

11. A plastic substrate material comprising the polyimide according to any one of claims 1 to 3.

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