polyimide resin

Abstract

A polyimide resin having a constituent unit A derived from a tetracarboxylic acid dianhydride and a constituent unit B derived from a diamine, wherein constituent unit A includes a constituent unit (A1) derived from a compound represented by the following formula (a1) and a constituent unit (A2) derived from a compound represented by the following formula (a2), and constituent unit B includes a constituent unit (B1) derived from a compound represented by the following formula (b1), wherein the ratio of constituent unit (A2) in constituent unit A is 27 mol% or less, and the polyimide resin does not include the following structural element (c). (In formula (c), X is a fluorine atom, a hydrogen atom, or a carbon atom.)

Description

Technology Field

[0001] The present invention relates to a polyimide resin. Background Technology

[0002] Generally, polyimide resins are obtained by polycondensing aromatic tetracarboxylic anhydrides with aromatic diamines. Due to their structure, polyimide resins possess molecular rigidity, resonance stabilization, and strong chemical bonding. For this reason, polyimide resins have excellent heat resistance, chemical resistance, mechanical properties, and electrical properties, and are widely used in fields such as molding materials, composite materials, electrical and electronic components, optical materials, displays, and aerospace.

[0003] Recently, applications are progressing as materials for image display devices among optical and electronic materials, and properties such as colorless transparency and solvent solubility of polyimide resins are required. However, conventional polyimides have problems such as high haze values ​​and yellow index (YI: yellowness). As a solution to this problem, for example, Patent Document 1 proposes a film characterized by including a fluorinated polyimide layer having an overall haze value of 4 or less, a yellow index of 3 or less, and an total light transmittance of 90% or more. Prior art literature

[0004] Japanese Patent Publication No. 2016-027146 The problem to be solved

[0005] Fluorinated polyimides can improve colorlessness, transparency, and solubility. However, some compounds belonging to the group of perfluoroalkyl substances and polyfluoroalkyl substances (PFAS) are restricted substances under the European REACH (Registration, Evaluation, Authorization and Restriction of Chemicals) regulations due to concerns regarding environmental burden and health hazards, and it is expected that such regulations will become stricter in the future. Against this backdrop, the use of perfluoroalkyl substances and polyfluoroalkyl substances in electronic components is sometimes restricted.

[0006] If the goal is simply to improve transparency, transparency can be improved by using aliphatic or alicyclic raw materials. However, mechanical properties are degraded, making it difficult to achieve both transparency and mechanical properties of polyimide resins. Therefore, there was a demand for polyimide resins that have excellent transparency and mechanical properties without being classified as PFAS.

[0007] The present invention has been made in consideration of these circumstances, and the objective of the present invention is to provide a polyimide resin that has excellent transparency, high elastic modulus and high strength, excellent elongation, and is soluble in solvents. In particular, the objective is to provide a polyimide resin having the above properties without including a perfluoroalkyl structure or a polyfluoroalkyl structure. means of solving the problem

[0008] The inventors have discovered that a polyimide resin comprising a combination of specific constituent units can solve the above problem, and have thus completed the invention.

[0009] That is, the present invention relates to the following [1] to

[12] .

[0010] [1] A polyimide resin having a constituent unit A derived from a tetracarboxylic acid dianhydride and a constituent unit B derived from a diamine, wherein constituent unit A comprises a constituent unit (A1) derived from a compound represented by the following formula (a1) and a constituent unit (A2) derived from a compound represented by the following formula (a2), and constituent unit B comprises a constituent unit (B1) derived from a compound represented by the following formula (b1), wherein the ratio of constituent unit (A2) in constituent unit A is 27 mol% or less, and the polyimide resin does not include the following structural element (c).

[0011] [Chemical Formula 1]

[0012]

[0013] (In formula (c), X is a fluorine atom, a hydrogen atom, or a carbon atom.)

[0014] [2] Polyimide resin described in [1] above, wherein the proportion of constituent unit (A1) in constituent unit A is 10 to 99 mol%.

[0015] [3] Polyimide resin described in [1] or [2], wherein the molar ratio [(A1) / (A2)] of the constituent unit (A1) to the constituent unit (A2) in constituent unit A is 73 / 27 to 99 / 1.

[0016] [4] Polyimide resin described in any one of [1] to [3], wherein the proportion of constituent unit (B1) in constituent unit B is 40 to 100 mol%.

[0017] [5] A polyimide resin described in any one of [1] to [4], wherein the constituent unit B comprises at least one selected from the group consisting of a constituent unit (B2) derived from a compound represented by the following formula (b2), a constituent unit (B3) derived from a compound represented by the following formula (b3), a constituent unit (B4) derived from a compound represented by the following formula (b4), a constituent unit (B5) derived from a compound represented by the following formula (b5), and a constituent unit (B6) derived from a compound represented by the following formula (b6).

[0018] [Chemical Formula 2]

[0019]

[0020] (In formula (b6), R is independently a hydrogen atom or a methyl group, Y is a divalent group having 12 to 30 carbon atoms containing an aromatic ring, and n is 0 or 1.)

[0021] [6] Polyimide resin described in [5] above, wherein the sum of the ratios of constituent unit (B2), constituent unit (B3), constituent unit (B4), constituent unit (B5) and constituent unit (B6) in constituent unit B is 50 mol% or less.

[0022] [7] Polyimide resin described in [5] or [6], wherein the molar ratio of constituent unit (B1) to the sum of constituent unit (B2), constituent unit (B3), constituent unit (B4), constituent unit (B5) and constituent unit (B6) [(B1) / ((B2)+(B3)+(B4)+(B5)+(B6))] is 50 / 50 to 99 / 1.

[0023] [8] A polyimide resin described in any one of [1] to [7], wherein the proportion of a trans-type structure derived from (1R,2S,4S,5R)-cyclohexanetetracarboxylic acid dianhydride included in the constituent unit (A1) is 30 mol% or more of the constituent unit (A1).

[0024] [9] A polyimide varnish formed by dissolving the polyimide resin described in any one of [1] to [8] above in an organic solvent.

[0025]

[10] A polyimide film comprising a polyimide resin described in any one of [1] to [8] above.

[0026]

[11] A polyimide film described in

[10] , having a thickness of 50 μm, a YI of 7.5 or less, a total light transmittance of 80% or more, a haze of 1.0% or less, and a tensile fracture point elongation of 5% or more when a tensile test is performed under conditions of 23°C and 50% RH, a test specimen of 50 μm × 10 mm × 120 mm, a tensile speed of 20 mm / min, and a chuck distance of 50 mm, and a tensile modulus of 3.7 GPa or more calculated by the slope of the least squares method in the stress-strain curve obtained by the tensile test from 0.1 mm to 0.5 mm of strain.

[0027]

[12] Polyimide film described in

[10] or

[11] above, having a thickness of 5 to 100 μm. Effects of the invention

[0028] According to the present invention, a polyimide resin is provided that has excellent transparency, high elastic modulus and high strength, excellent elongation, and is soluble in solvents. In particular, a polyimide resin having the above properties can be provided without including a perfluoroalkyl structure or a polyfluoroalkyl structure. Therefore, the polyimide resin of the present invention is useful as an optical material or an electronic material, particularly as a material for displays. Specific details for implementing the invention

[0029] [Polyimide Resin]

[0030] The polyimide resin of the present invention is a polyimide resin having a constituent unit A derived from a tetracarboxylic acid dianhydride and a constituent unit B derived from a diamine, wherein constituent unit A comprises a constituent unit (A1) derived from a compound represented by the following formula (a1) and a constituent unit (A2) derived from a compound represented by the following formula (a2), and constituent unit B comprises a constituent unit (B1) derived from a compound represented by the following formula (b1), wherein the ratio of constituent unit (A2) in constituent unit A is 27 mol% or less, and the polyimide resin does not include the following structural element (c).

[0031] The polyimide resin of the present invention has excellent transparency, high elastic modulus and high strength, excellent elongation, and is soluble in solvents.

[0032] [Chemical Formula 3]

[0033]

[0034] (In formula (c), X is a fluorine atom, a hydrogen atom, or a carbon atom.)

[0035] Meanwhile, although it is not certain why the polyimide resin of the present invention has excellent transparency, high elastic modulus and high strength, excellent elongation, and is soluble in solvents, it is thought to be as follows.

[0036] The polyimide resin of the present invention is thought to possess excellent transparency, excellent solubility, and good elongation by having a cyclohexane structure which is an alicyclic structure. Furthermore, it is thought to possess high elastic modulus, high strength, and good elongation by having a rigid structure such as a biphenyl structure having substituents. Moreover, the imide ring adjacent to the cyclobutane structure is thought to provide good packing, and by including a small amount of this structure, it is thought to maintain the above performance while also possessing high elastic modulus, high strength, and good elongation. Based on the above, the polyimide resin of the present invention is thought to possess excellent transparency, high elastic modulus and high strength, excellent elongation, and solubility in solvents.

[0037] <Constituent Unit A>

[0038] Constituent unit A is a constituent unit derived from the tetracarboxylic acid dianhydride that occupies the polyimide resin.

[0039] Constituent unit A includes a constituent unit (A1) derived from a compound represented by the following formula (a1) and a constituent unit (A2) derived from a compound represented by the following formula (a2), and the proportion of the constituent unit (A2) in constituent unit A is 27 mol% or less. In addition, it does not include the following structural element (c).

[0040] [Chemical Formula 4]

[0041]

[0042] (In formula (c), X is a fluorine atom, a hydrogen atom, or a carbon atom.)

[0043] By including constituent unit A as constituent unit (A1) and constituent unit (A2), the transparency of the polyimide resin can be improved without including a perfluoroalkyl structure or a polyfluoroalkyl structure represented by structural element (c), while increasing the elastic modulus and high strength, improving elongation, and improving solvent solubility.

[0044] The compound represented by formula (a1) is 1,2,4,5-cyclohexanetetracarboxylic acid dianhydride (HPMDA).

[0045] By including constituent unit A as constituent unit (A1), the transparency of the polyimide resin can be improved, and the elongation can also be improved. In addition, solvent solubility can also be improved.

[0046] The constituent unit (A1) preferably comprises a trans-type structure derived from (1R,2S,4S,5R)-cyclohexanetetracarboxylic acid dianhydride.

[0047] A trans-type structure derived from (1R,2S,4S,5R)-cyclohexanetetracarboxylic acid dianhydride refers to the structure of formula (1) below within the framework of a polyimide resin. Meanwhile, the structure of formula (2) below is a cis-type structure and is not included in the trans-type structure.

[0048] Meanwhile, the raw material for obtaining the structure of formula (1) is preferably (1R,2S,4S,5R)-cyclohexanetetracarboxylic acid dianhydride, but is not limited to (1R,2S,4S,5R)-cyclohexanetetracarboxylic acid dianhydride and may be a raw material other than (1R,2S,4S,5R)-cyclohexanetetracarboxylic acid dianhydride, such as (1S,2R,4S,5R)-cyclohexanetetracarboxylic acid dianhydride having a cis-type structure. That is, the structure of formula (1) is a trans-type structure derived from (1R,2S,4S,5R)-cyclohexanetetracarboxylic acid dianhydride.

[0049] [Chemical Formula 5]

[0050]

[0051] The proportion of the trans-type structure derived from (1R,2S,4S,5R)-cyclohexanetetracarboxylic acid dianhydride included in the constituent unit (A1) is preferably 30 mol% or more of the constituent unit (A1). The proportion of the trans-type structure derived from (1R,2S,4S,5R)-cyclohexanetetracarboxylic acid dianhydride included in the constituent unit (A1) is preferably 35 to 100 mol%, more preferably 40 to 100 mol%, even more preferably 50 to 100 mol%, even more preferably 55 to 100 mol%, even more preferably 60 to 100 mol%, even more preferably 70 to 100 mol%, even more preferably 75 to 100 mol%, even more preferably 80 to 100 mol%, even more preferably 85 to 100 mol%, even more preferably 90 to 100 mol%, and even more preferably 95 to 100 mol%, and the constituent unit (A1) may consist only of the trans-type structure derived from (1R,2S,4S,5R)-cyclohexanetetracarboxylic acid dianhydride. It is more preferable that the constituent unit (A1) consists solely of a trans-type structure derived from (1R,2S,4S,5R)-cyclohexanetetracarboxylic acid dianhydride. By including a trans-type structure in the constituent unit (A1), the transparency of the polyimide resin obtained can be improved, and the elastic modulus and high strength can be increased.

[0052] That is, the proportion of the structure of formula (1) included in the constituent unit (A1) is preferably 30 mol% or more of the constituent unit (A1). The proportion of the structure of formula (1) included in the constituent unit (A1) is more preferably 35 to 100 mol%, even more preferably 40 to 100 mol%, even more preferably 50 to 100 mol%, even more preferably 55 to 100 mol%, even more preferably 60 to 100 mol%, even more preferably 70 to 100 mol%, even more preferably 75 to 100 mol%, even more preferably 80 to 100 mol%, even more preferably 85 to 100 mol%, even more preferably 90 to 100 mol%, and even more preferably 95 to 100 mol%, and the constituent unit (A1) may be composed only of the structure of formula (1), and it is more preferable that the constituent unit (A1) be composed only of the structure of formula (1). By including a trans-type structure in the constituent unit (A1), the transparency of the polyimide resin obtained can be improved, and the elastic modulus and high strength can be increased.

[0053] The compound represented by formula (a2) is 1,2,3,4-cyclobutanetetracarboxylic acid dianhydride (CBDA).

[0054] By including constituent unit A as constituent unit (A2), the elastic modulus of the polyimide resin can be increased, in particular.

[0055] The proportion of the constituent unit (A2) in constituent unit A is 27 mol% or less.

[0056] The ratio of constituent unit (A2) in constituent unit A is preferably 25 mol% or less, more preferably 23 mol% or less, and even more preferably 22 mol% or less. The lower limit of the ratio of constituent unit (A2) in constituent unit A is preferably 0.5 mol% or more. The ratio of constituent unit (A2) in constituent unit A is preferably 0.5 to 27 mol%, more preferably 1 to 27 mol%, even more preferably 3 to 27 mol%, even more preferably 5 to 27 mol%, even more preferably 10 to 27 mol%, even more preferably 10 to 25 mol%, even more preferably 15 to 25 mol%, even more preferably 15 to 23 mol%, and even more preferably 15 to 22 mol%. By setting the ratio of the constituent unit (A2) among the constituent unit A to the above range, it is possible to achieve high elastic modulus, strength, and excellent elongation while improving the transparency of the polyimide resin obtained.

[0057] The molar ratio [(A1) / (A2)] of constituent unit (A1) to constituent unit (A2) in constituent unit A is preferably 73 / 27 to 99 / 1, more preferably 73 / 27 to 97 / 3, even more preferably 73 / 27 to 95 / 5, even more preferably 73 / 27 to 90 / 10, even more preferably 75 / 25 to 90 / 10, even more preferably 75 / 25 to 85 / 15, even more preferably 77 / 23 to 85 / 15, and even more preferably 78 / 22 to 85 / 15. By using the above molar ratio, it is possible to achieve high elastic modulus or strength and excellent elongation while improving the transparency of the polyimide resin obtained.

[0058] The ratio of the constituent unit (A1) in constituent unit A is preferably 99.5 mol% or less, more preferably 10 to 99.5 mol%, even more preferably 10 to 99 mol%, even more preferably 50 to 99 mol%, even more preferably 73 to 99 mol%, even more preferably 73 to 97 mol%, even more preferably 73 to 95 mol%, even more preferably 73 to 90 mol%, even more preferably 75 to 90 mol%, even more preferably 75 to 85 mol%, even more preferably 77 to 85 mol%, and even more preferably 78 to 85 mol%. By setting the ratio of the constituent unit (A1) in constituent unit A to the above range, it is possible to achieve high elastic modulus or strength and excellent elongation while improving the transparency of the polyimide resin obtained.

[0059] The ratio of the total of constituent units (A1) and constituent units (A2) in constituent unit A is preferably 50 mol% or more, more preferably 70 mol% or more, even more preferably 90 mol% or more, and also preferably 100 mol% or less. Constituent unit A may consist only of constituent unit (A1) and constituent unit (A2), and it is more preferable that constituent unit A consists only of constituent unit (A1) and constituent unit (A2). That is, the ratio of the total of constituent units (A1) and constituent units (A2) in constituent unit A may be 100 mol%, and it is more preferable that it be 100 mol%.

[0060] Constituent unit A may include constituent units other than constituent unit (A1) and constituent unit (A2). The tetracarboxylic acid dianhydrides that impart such constituent units are not particularly limited, but may include aromatic tetracarboxylic acid dianhydrides, alicyclic tetracarboxylic acid dianhydrides, and aliphatic tetracarboxylic acid dianhydrides, excluding compounds represented by formula (a1) and compounds represented by formula (a2).

[0061] Examples of aromatic tetracarboxylic acid dianhydrides other than the above compounds include 4,4'-oxydiphthalic anhydride (ODPA), 3,3',4,4'-diphenylsulfonetetracarboxylic acid dianhydride (DSDA), 3,3',4,4'-benzophenonetetracarboxylic acid dianhydride (BTDA), hydroquinone diphthalic anhydride (HQDEA), ethylene glycol bis(trimellitate) dianhydride (TMEG), 2,2',3,3',5,5'-hexamethyl[1,1'-biphenyl]-4,4'-diyl=bis(1,3-dioxo-1,3-dihydro-2-benzofuran-5-carboxylate) (TMPBP-TME), and 2,2-bis(3,4-dicarboxyphenyl)-propane dianhydride.

[0062] Alicyclic tetracarboxylic acid dianhydrides include cyclohexane-1,2,3,4-tetracarboxylic acid dianhydride, 1,2,3,4-cyclopentanetetracarboxylic acid dianhydride, 1,2,4,5-cyclopentanetetracarboxylic acid dianhydride, 3,3',4,4'-bicyclohexyltetracarboxylic acid dianhydride, 1,2,3,4-tetramethyl-1,2,3,4-cyclobutanetetracarboxylic acid dianhydride, decahydro-1,4:5,8-dimethanonaphthalene-2,3,6,7-tetracarboxylic acid dianhydride (DNDA), 5,5'-(1,4-phenylene)-bis[hexahydro-4,7-methanoisobenzofuran-1,3-dione], 5,5'-bis-2-norbornene-5,5',6,6'-tetracarboxylic acid-5,5',6,6'-dianhydride, norbonan-2-spiro-α-cyclopentanone-α'-spiro-2''-norbonan-5,5',6,6'-tetracarboxylic acid anhydride (CpODA), 2,2-propylidene-4,4'-bis(cyclohexane-1,2-dicarboxylic acid) dianhydride, oxy-4,4'-bis(cyclohexane-1,2-dicarboxylic acid) dianhydride, bicyclo[2.2.2]oct-7-en-2,3,5,6-tetracarboxylic acid dianhydride, bicyclo[2.2.2]octane-2,3:5,6-tetracarboxylic acid dianhydride (BODA), Examples include bicyclo[4.4.0]decan-2,3,6,7-tetracarboxylic acid dianhydride.

[0063] Examples of aliphatic tetracarboxylic acid dianhydrides include 1,2,3,4-butanetetracarboxylic acid dianhydride.

[0064] Meanwhile, in the present specification, an aromatic tetracarboxylic acid dianhydride means a tetracarboxylic acid dianhydride containing one or more aromatic rings, an alicyclic tetracarboxylic acid dianhydride means a tetracarboxylic acid dianhydride containing one or more alicyclic rings and not an aromatic ring, and an aliphatic tetracarboxylic acid dianhydride means a tetracarboxylic acid dianhydride containing neither aromatic rings nor alicyclic rings.

[0065] The constituent units optionally included in constituent unit A may be of one type or two or more types.

[0066] <Constituent Unit B>

[0067] Constituent unit B is a constituent unit derived from the diamine that occupies the polyimide resin.

[0068] Constituent unit B includes a constituent unit (B1) derived from a compound represented by the following formula (b1). Additionally, it does not include the following structural element (c).

[0069] [Chemical Formula 6]

[0070]

[0071] (In formula (c), X is a fluorine atom, a hydrogen atom, or a carbon atom.)

[0072] By including the constituent unit B as a constituent unit (B1), the elastic modulus or strength can be increased while maintaining the transparency or solvent solubility of the polyimide resin without including the perfluoroalkyl structure or polyfluoroalkyl structure represented by the structural element (c).

[0073] The compound represented by formula (b1) is 2,2'-dimethylbenzidine (mTB).

[0074] The proportion of constituent unit (B1) in constituent unit B is preferably 40 to 100 mol%, more preferably 50 to 100 mol%, even more preferably 70 to 100 mol%, even more preferably 80 to 100 mol%, even more preferably 85 to 100 mol%, and even more preferably 85 to 95 mol%. The proportion of constituent unit (B1) in constituent unit B may be 100 mol%, and constituent unit B may consist only of constituent unit (B1).

[0075] The constituent unit B may consist only of the constituent unit (B1) or may include constituent units other than the constituent unit (B1). Preferably, as a constituent unit other than the constituent unit (B1), it includes at least one selected from the group consisting of a constituent unit (B2) derived from a compound represented by the following formula (b2), a constituent unit (B3) derived from a compound represented by the following formula (b3), a constituent unit (B4) derived from a compound represented by the following formula (b4), a constituent unit (B5) derived from a compound represented by the following formula (b5), and a constituent unit (B6) derived from a compound represented by the following formula (b6).

[0076] [Chemical Formula 7]

[0077]

[0078] (In formula (b6), R is independently a hydrogen atom or a methyl group, Y is a divalent group having 12 to 30 carbon atoms containing an aromatic ring, and n is 0 or 1.)

[0079] The constituent unit B preferably comprises at least one selected from the group consisting of a constituent unit (B2) derived from a compound represented by formula (b2), a constituent unit (B3) derived from a compound represented by formula (b3), a constituent unit (B4) derived from a compound represented by formula (b4), a constituent unit (B5) derived from a compound represented by formula (b5), and a constituent unit (B6) derived from a compound represented by formula (b6); more preferably, it comprises at least one selected from the group consisting of a constituent unit (B2) derived from a compound represented by formula (b2), a constituent unit (B3) derived from a compound represented by formula (b3), and a constituent unit (B6) derived from a compound represented by formula (b6); even more preferably, it comprises a constituent unit (B6) derived from a compound represented by formula (b6).

[0080] The compound represented by formula (b2) is diaminodiphenylsulfone. Examples of compounds represented by formula (b2) include 4,4'-diaminodiphenylsulfone (4,4'-DDS), in which all amino groups are at the 4th position, and 3,3'-diaminodiphenylsulfone (3,3'-DDS), in which all amino groups are at the 3rd position, and 4,4'-diaminodiphenylsulfone (4,4'-DDS) is preferred.

[0081] By including the constituent unit B (B2), the transparency of the polyimide resin can be improved.

[0082] The compound represented by formula (b3) is octafluorobenzidine (8FBZ).

[0083] By including the constituent unit B (B3), the elastic modulus and elongation of the polyimide resin can be improved.

[0084] The compound represented by formula (b4) is 2,3,5,6-tetrafluorobenzene-1,4-diamine.

[0085] By including the constituent unit B (B4), the elastic modulus and elongation of the polyimide resin can be improved.

[0086] The compound represented by formula (b5) is 2,4,5,6-tetrafluorobenzene-1,3-diamine.

[0087] By including the constituent unit B (B5), the elastic modulus and elongation of the polyimide resin can be improved.

[0088] In formula (b6), R is independently a hydrogen atom or a methyl group, Y is a divalent group having 12 to 30 carbon atoms containing an aromatic ring, and n is 0 or 1.

[0089] R is independently a hydrogen atom or a methyl group, preferably a hydrogen atom, and more preferably both Rs are hydrogen atoms.

[0090] n is 0 or 1, preferably 0.

[0091] In formula (b6), when both Rs are hydrogen atoms and n is 0, the compound represented by formula (b6) is 4,4'-diaminobenzanilide (DABA).

[0092] By including a constituent unit B derived from 4,4'-diaminobenzanilide (DABA) among the constituent units (B6), it is possible to improve transparency and elongation while maintaining the high elastic modulus or strength of the polyimide resin.

[0093] In formula (b6), when n is 1, the compound represented by formula (b6) includes Y, a divalent group having 12 to 30 carbon atoms.

[0094] Y is a divalent group having 12 to 30 carbon atoms containing an aromatic ring, and preferably a divalent group having 12 to 26 carbon atoms containing an aromatic ring.

[0095] Among the compounds represented by formula (b6), preferred compounds when n is 1 include the compound represented by the following formula (b61), the compound represented by the following formula (b62), the compound represented by the following formula (b63), and the compound represented by the following formula (b64).

[0096] The compound represented by formula (b6) is preferably at least one selected from the group consisting of the compound represented by the following formula (b61), the compound represented by the following formula (b62), the compound represented by the following formula (b63), and the compound represented by the following formula (b64); more preferably, it is at least one selected from the group consisting of the compound represented by the following formula (b61), the compound represented by the following formula (b62), and the compound represented by the following formula (b63); even more preferably, it is at least one selected from the group consisting of the compound represented by the following formula (b61) and the compound represented by the following formula (b63); and even more preferably, it is the compound represented by the following formula (b61).

[0097] [Chemical Formula 8]

[0098]

[0099] The compound represented by formula (b61) is N,N'-(2,2'-dimethyl[1,1'-biphenyl]-4,4'-diyl)bis[4-amino-3-methylbenzamide](AMB-mTOL).

[0100] By including a component unit B derived from a compound represented by formula (b61) among the component units (B6), it is possible to improve transparency and elongation while maintaining the high elastic modulus or strength of the polyimide resin.

[0101] The compound represented by formula (b62) is N,N'-[(octahydro-1,3,5,7-tetraoxobenzo[1,2-c:4,5-c']dipyrrole-2,6(1H,3H)-diyl)bis(3-methoxy-4,1-phenylene)]bis[4-amino-benzamide](AB-MP-HPMDI).

[0102] By including a component unit B derived from a compound represented by formula (b62) among the component units (B6), it is possible to improve transparency and elongation while maintaining the high elastic modulus or strength of the polyimide resin.

[0103] The compound represented by formula (b63) is N,N'-(2,2'-dimethyl[1,1'-biphenyl]-4,4'-diyl)bis[4-amino-benzamide](AB-mTOL).

[0104] By including a component unit B derived from a compound represented by formula (b63) among the component units (B6), it is possible to improve transparency and elongation while maintaining the high elastic modulus or strength of the polyimide resin.

[0105] The compound represented by formula (b64) is N,N'-(oxydi-4,1-phenylene)bis[4-amino-benzamide](AB-44ODA).

[0106] By including a component unit B derived from a compound represented by formula (b64) among the component units (B6), it is possible to improve transparency and elongation while maintaining the high elastic modulus or strength of the polyimide resin.

[0107] As described above, by including the constituent unit B (B6), the transparency and elongation can be improved while maintaining the high elastic modulus or strength of the polyimide resin.

[0108] The sum of the ratios of constituent units (B2), constituent unit (B3), constituent unit (B4), constituent unit (B5) and constituent unit (B6) in constituent unit B is preferably 50 mol% or less.

[0109] The sum of the ratios of constituent unit (B2), constituent unit (B3), constituent unit (B4), constituent unit (B5) and constituent unit (B6) in constituent unit B is more preferably 1 to 50 mol%, even more preferably 1 to 40 mol%, even more preferably 1 to 30 mol%, even more preferably 3 to 25 mol%, even more preferably 3 to 20 mol%, even more preferably 5 to 20 mol%, and even more preferably 5 to 15 mol%. By setting the sum of the ratios of constituent unit (B2), constituent unit (B3), constituent unit (B4), constituent unit (B5) and constituent unit (B6) in constituent unit B to the above range, transparency and elongation can be improved while maintaining the high elastic modulus or strength of the polyimide resin obtained.

[0110] The molar ratio of constituent unit (B1) to the sum of constituent unit (B2), constituent unit (B3), constituent unit (B4), constituent unit (B5) and constituent unit (B6) in constituent unit B [(B1) / ((B2)+(B3)+(B4)+(B5)+(B6))] is preferably 50 / 50 to 99 / 1, more preferably 60 / 40 to 99 / 1, even more preferably 70 / 30 to 99 / 1, even more preferably 75 / 25 to 97 / 3, even more preferably 80 / 20 to 97 / 3, even more preferably 80 / 20 to 95 / 5, and even more preferably 85 / 15 to 95 / 5. By setting the molar ratio of constituent unit (B1) to the sum of constituent unit (B2), constituent unit (B3), constituent unit (B4), constituent unit (B5) and constituent unit (B6) in constituent unit B to the above range, the transparency and elongation can be improved while maintaining the high elastic modulus and strength of the polyimide resin obtained.

[0111] The sum of the ratios of constituent units (B1), constituent unit (B2), constituent unit (B3), constituent unit (B4), constituent unit (B5) and constituent unit (B6) in constituent unit B is preferably 70 mol% or more, more preferably 80 mol% or more, even more preferably 90 mol% or more, and also preferably 100 mol% or less. The constituent units included in constituent unit B may be only constituent unit (B1), constituent unit (B2), constituent unit (B3), constituent unit (B4), constituent unit (B5) and constituent unit (B6).

[0112] Constituent unit B may include constituent units other than constituent unit (B1), constituent unit (B2), constituent unit (B3), constituent unit (B4), constituent unit (B5) and constituent unit (B6). The diamines imparting such constituent units are not particularly limited, but may include aromatic diamines, alicyclic diamines, and aliphatic diamines, excluding the compound represented by formula (b1), the compound represented by formula (b2), the compound represented by formula (b3), the compound represented by formula (b4), the compound represented by formula (b5), and the compound represented by formula (b6).

[0113] Aromatic diamines other than the above compounds include bis(4-aminophenyl)terephthalate (APTP), 1,4-bis(4-aminobenzoyloxy)benzene, 4,4'-diaminodiphenyl ether (4,4'-ODA), 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane (DDM), 9,9-bis(4-aminophenyl)fluorene (BAFL), 4,4'-diaminobiphenyl (benzidine), 4,4'-diamino-3,3'-dimethylbiphenyl, 4,4'-diaminodiphenyl sulfide, 4,4'-diaminobenzophenone, 2,2-bis(3-aminophenyl)propane, 2,2-bis(4-aminophenyl)propane, 5-amino-1,3,3-trimethyl-1-(4-aminophenyl)-indane (5-TMDM), 6-amino-1,3,3-trimethyl-1-(4-aminophenyl)-indane(6-TMDM), 1,3-bis(3-amino-α,α-dimethylbenzyl)benzene, 1,3-bis(4-amino-α,α-dimethylbenzyl)benzene (BisAM), 1,4-bis(4-amino-α,α-dimethylbenzyl)benzene (BisAP), 4,4'-bis(3-aminophenoxy)biphenyl, 4,4'-bis(4-aminophenoxy)biphenyl (BODA), 1,1-bis[4-(4-aminophenoxy)phenyl]cyclohexane, 2,2-bis[4-(4-aminophenoxy)phenyl]propane (BAPP), 1,4-bis(3-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene, Examples include 1,3-bis(3-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, bis[4-(3-aminophenoxy)phenyl]ketone, bis[4-(4-aminophenoxy)phenyl]ketone, bis[4-(3-aminophenoxy)phenyl]sulfide, bis[4-(4-aminophenoxy)phenyl]sulfide, bis[4-(3-aminophenoxy)phenyl]ether, bis[4-(4-aminophenoxy)phenyl]ether, bis[4-(3-aminophenoxy)phenyl]sulfone, bis[4-(4-aminophenoxy)phenyl]sulfone, 4,4-diaminobenzanilide, 4-aminobenzoic acid-4-aminophenyl, 3,4-diaminobenzanilide, etc.

[0114] Examples of alicyclic diamines include 1,3-bis(aminomethyl)cyclohexane (1,3-BAC), 1,4-bis(aminomethyl)cyclohexane, 1,3-cyclohexyldiamine, 1,4-cyclohexyldiamine, isophoronediamine, bis(aminomethyl)norbonane, 4,4'-diaminodicyclohexylmethane, 4,4'-diaminodicyclohexyl ether, 2,2-bis(4-aminocyclohexyl)propane, etc.

[0115] Examples of aliphatic diamines include ethylenediamine and hexamethylenediamine.

[0116] Meanwhile, in this specification, an aromatic diamine means a diamine containing one or more aromatic rings, a diamine alicyclic means a diamine containing one or more alicyclic rings and not an aromatic ring, and an aliphatic diamine means a diamine that does not contain either an aromatic ring or alicyclic rings.

[0117] The constituent units optionally included in constituent unit B may be of one type or two or more types.

[0118] Structure and Properties of Polyimide Resin

[0119] The polyimide resin of the present invention does not include the following structural element (c).

[0120] [Chemical Formula 9]

[0121]

[0122] (In formula (c), X is a fluorine atom, a hydrogen atom, or a carbon atom.)

[0123] The structural element (c) in the present invention is described in detail below. Meanwhile, the structural element (c) in the polyimide resin, the method of manufacturing the same, the polyimide varnish, and the polyimide film of the present invention all have the same meaning.

[0124] The carbon atom bonded to the CF2 group other than X in formula (c) may be a secondary carbon, a tertiary carbon, or a quaternary carbon, may be a carbon atom constituting an aromatic ring, or may be substituted with a hydrogen atom and an atom other than a carbon atom. Examples of atoms other than hydrogen and carbon atoms include halogens, nitrogen atoms, oxygen atoms, etc.

[0125] When X is a carbon atom, the carbon atom X is a primary carbon, secondary carbon, tertiary carbon, or quaternary carbon, and may be a carbon atom that constitutes an aromatic ring, or may be substituted with a hydrogen atom and an atom other than a carbon atom. Examples of atoms other than hydrogen and carbon atoms include halogens, nitrogen atoms, oxygen atoms, etc.

[0126] The structural element (c) is a perfluoroalkyl structure or a polyfluoroalkyl structure. As a polyimide resin comprising the above structural element, for example, a polyimide resin having a constituent unit derived from the tetracarboxylic acid dianhydride given below and a constituent unit derived from the diamine given below may be cited. That is, the polyimide resin of the present invention does not have both the constituent unit derived from the tetracarboxylic acid dianhydride given below and the constituent unit derived from the diamine given below.

[0127] Examples of the above tetracarboxylic acid dianhydrides include 9,9-bis(trifluoromethyl)-9H-xanthen-2,3,6,7-tetracarboxylic acid dianhydride (6FCDA), 2,2-bis[4-(3,4-dicarboxyphenoxy)phenyl]hexafluoropropane dianhydride, 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA), etc.

[0128] Examples of the above diamines include 2,2'-bis(trifluoromethyl)-4,4'-diaminodiphenyl ether (6FODA), 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl (2,2'-TFMB), 3,3'-bis(trifluoromethyl)-4,4'-diaminobiphenyl, 2,2'-bis(trifluoromethyl)-5,5'-diaminobiphenyl, 2,2-bis(4-aminophenyl)hexafluoropropane (HFDA), 2,2-bis(3-amino-4-methylphenyl)hexafluoropropane, and 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane (HFBAPP).

[0129] The number average molecular weight of the polyimide resin is preferably 5,000 to 300,000 in terms of the mechanical strength of the polyimide film obtained. Meanwhile, the number average molecular weight of the polyimide resin can be obtained, for example, from the standard polymethyl methacrylate (PMMA) equivalent value by gel filtration chromatography measurement.

[0130] Polyimide resins may include structures other than polyimide chains (structures formed by imide bonds between constituent unit A and constituent unit B). Examples of structures other than polyimide chains that may be included in polyimide resins include structures containing amide bonds. However, structures other than polyimide chains do not include structural elements (c).

[0131] It is preferable that the polyimide resin contains polyimide chains (a structure formed by imide bonding of constituent unit A and constituent unit B) as the main structure. Accordingly, the proportion of polyimide chains in the polyimide resin is preferably 50 mass% or more, more preferably 70 mass% or more, even more preferably 90 mass% or more, and even more preferably 99 mass% or more. Additionally, it is preferably 100 mass% or less. Even more preferably 100 mass%, and the polyimide resin may consist only of polyimide chains.

[0132] Method for manufacturing polyimide resin

[0133] There are no particular limitations on the method for manufacturing the polyimide resin of the present invention, but it is preferable to obtain a polyimide resin by reacting a tetracarboxylic acid dianhydride imparting the constituent unit A described above with a diamine imparting the constituent unit B described above. According to this method, a polyimide resin is obtained directly from the tetracarboxylic acid dianhydride and the diamine. Among these, the manufacturing method described below is preferred.

[0134] A method for manufacturing a polyimide resin preferably comprises a process of imidizing a tetracarboxylic acid dianhydride containing a compound represented by formula (a1) and a compound represented by formula (a2), and a diamine containing a compound represented by formula (b1), in the presence of a base catalyst and an organic solvent containing a lactone-based solvent. A preferred manufacturing method is described below.

[0135] (Tetracarboxylic acid dianhydride)

[0136] The above tetracarboxylic acid dianhydride includes a compound represented by the following formula (a1) and a compound represented by the following formula (a2).

[0137] In addition, it is preferable not to include the following structural element (c).

[0138] [Chemical Formula 10]

[0139]

[0140] (In formula (c), X is a fluorine atom, a hydrogen atom, or a carbon atom.)

[0141] By including a tetracarboxylic acid dianhydride with a compound represented by formula (a1) and a compound represented by formula (a2), the transparency of the polyimide film (polyimide resin) can be improved, while increasing the elastic modulus and strength, improving elongation, and improving solvent solubility, without including a perfluoroalkyl structure or a polyfluoroalkyl structure represented by structural element (c).

[0142] By including a compound represented by formula (a1) with tetracarboxylic acid dianhydride, the transparency of the polyimide film (polyimide resin) can be improved, and the elongation can also be improved. Additionally, solvent solubility can also be improved.

[0143] The compound represented by formula (a1) preferably contains the compound represented by the following formula (a11). The compound represented by the following formula (a11) is (1R,2S,4S,5R)-cyclohexanetetracarboxylic acid dianhydride.

[0144] (1R,2S,4S,5R)-cyclohexanetetracarboxylic acid dianhydride has a trans-type structure. The compound represented by the following formula (a12) has a cis-type structure and is not included in the compound represented by the following formula (a11).

[0145] [Chemical Formula 11]

[0146]

[0147] The proportion of the compound represented by formula (a11) included in the compound represented by formula (a1) is preferably 30 mol% or more of the compound represented by formula (a1).

[0148] The proportion of the compound represented by formula (a11) included in the compound represented by formula (a1) is preferably 30 to 100 mol%, more preferably 35 to 100 mol%, even more preferably 50 to 100 mol%, even more preferably 60 to 100 mol%, even more preferably 70 to 100 mol%, even more preferably 80 to 100 mol%, even more preferably 90 to 100 mol%, even more preferably 95 to 100 mol%, and may be 100 mol%, and is more preferably 100 mol%. The compound represented by formula (a1) may consist only of the compound represented by formula (a11), and it is more preferable that the compound represented by formula (a1) consists only of the compound represented by formula (a11).

[0149] By including the compound represented by formula (a1) as the compound represented by formula (a11), the transparency of the polyimide film (polyimide resin) obtained can be improved and the elastic modulus can be increased. Meanwhile, even if only the compound represented by formula (a12) is used as the compound represented by formula (a1), a trans-type structure can be introduced into the polyimide resin obtained depending on the manufacturing conditions; however, it is preferable to use the compound represented by formula (a11) because a trans-type structure can be introduced into the polyimide resin obtained more reliably.

[0150] By including a compound represented by formula (a2) with tetracarboxylic acid dianhydride, the elastic modulus of the polyimide film (polyimide resin) can be increased in particular.

[0151] The proportion of the compound represented by formula (a2) in the tetracarboxylic acid dianhydride is preferably 27 mol% or less.

[0152] The proportion of the compound represented by formula (a2) in the tetracarboxylic acid dianhydride is more preferably 25 mol% or less, more preferably 23 mol% or less, and even more preferably 22 mol% or less. The lower limit of the proportion of the compound represented by formula (a2) in the tetracarboxylic acid dianhydride is preferably 0.5 mol% or more. The proportion of the compound represented by formula (a2) in the tetracarboxylic acid dianhydride is preferably 0.5 to 27 mol%, more preferably 1 to 27 mol%, even more preferably 3 to 27 mol%, even more preferably 5 to 27 mol%, even more preferably 10 to 27 mol%, even more preferably 10 to 25 mol%, even more preferably 15 to 25 mol%, even more preferably 15 to 23 mol%, and even more preferably 15 to 22 mol%. By setting the ratio of the compound represented by formula (a2) in the tetracarboxylic acid dianhydride to the above range, it is possible to achieve high elastic modulus, strength, and excellent elongation while improving the transparency of the polyimide film (polyimide resin) obtained.

[0153] The molar ratio [(a1) / (a2)] of the compound represented by formula (a1) to the compound represented by formula (a2) in the tetracarboxylic acid dianhydride is preferably 73 / 27 to 99 / 1, more preferably 73 / 27 to 97 / 3, even more preferably 73 / 27 to 95 / 5, even more preferably 73 / 27 to 90 / 10, even more preferably 75 / 25 to 90 / 10, even more preferably 75 / 25 to 85 / 15, even more preferably 77 / 23 to 85 / 15, and even more preferably 78 / 22 to 85 / 15. By using the above molar ratio, it is possible to achieve high elastic modulus or strength and excellent elongation while improving the transparency of the polyimide resin obtained.

[0154] The proportion of the compound represented by formula (a1) in the tetracarboxylic acid dianhydride is preferably 99.5 mol% or less, more preferably 10 to 99.5 mol%, even more preferably 10 to 99 mol%, even more preferably 50 to 99 mol%, even more preferably 73 to 99 mol%, even more preferably 73 to 97 mol%, even more preferably 73 to 95 mol%, even more preferably 73 to 90 mol%, even more preferably 75 to 90 mol%, even more preferably 75 to 85 mol%, even more preferably 77 to 85 mol%, and even more preferably 78 to 85 mol%. By setting the proportion of the compound represented by formula (a1) in the tetracarboxylic acid dianhydride to the above range, it is possible to achieve high elastic modulus or strength and excellent elongation while improving the transparency of the polyimide resin obtained.

[0155] The ratio of the total of the compound represented by formula (a1) and the compound represented by formula (a2) in the tetracarboxylic acid dianhydride is preferably 50 mol% or more, more preferably 70 mol% or more, even more preferably 90 mol% or more, and also preferably 100 mol% or less. The tetracarboxylic acid dianhydride may consist only of the compound represented by formula (a1) and the compound represented by formula (a2), and it is preferable that the tetracarboxylic acid dianhydride consists only of the compound represented by formula (a1) and the compound represented by formula (a2).

[0156] Tetracarboxylic acid dianhydrides may include tetracarboxylic acid dianhydrides other than the compound represented by formula (a1) and the compound represented by formula (a2). Such tetracarboxylic acid dianhydrides are not particularly limited, but may include aromatic tetracarboxylic acid dianhydrides, alicyclic tetracarboxylic acid dianhydrides, and aliphatic tetracarboxylic acid dianhydrides, excluding the compound represented by formula (a1) and also excluding the compound represented by formula (a2).

[0157] Examples of aromatic tetracarboxylic acid dianhydrides other than the above compounds include 4,4'-oxydiphthalic anhydride (ODPA), 3,3',4,4'-diphenylsulfonetetracarboxylic acid dianhydride (DSDA), 3,3',4,4'-benzophenonetetracarboxylic acid dianhydride (BTDA), hydroquinone diphthalic anhydride (HQDEA), ethylene glycol bis(trimellitate) dianhydride (TMEG), 2,2',3,3',5,5'-hexamethyl[1,1'-biphenyl]-4,4'-diyl=bis(1,3-dioxo-1,3-dihydro-2-benzofuran-5-carboxylate) (TMPBP-TME), and 2,2-bis(3,4-dicarboxyphenyl)-propane dianhydride.

[0158] Alicyclic tetracarboxylic acid dianhydrides include cyclohexane-1,2,3,4-tetracarboxylic acid dianhydride, 1,2,3,4-cyclopentanetetracarboxylic acid dianhydride, 1,2,4,5-cyclopentanetetracarboxylic acid dianhydride, 3,3',4,4'-bicyclohexyltetracarboxylic acid dianhydride, 1,2,3,4-tetramethyl-1,2,3,4-cyclobutanetetracarboxylic acid dianhydride, decahydro-1,4:5,8-dimethanonaphthalene-2,3,6,7-tetracarboxylic acid dianhydride (DNDA), 5,5'-(1,4-phenylene)-bis[hexahydro-4,7-methanoisobenzofuran-1,3-dione], 5,5'-bis-2-norbornene-5,5',6,6'-tetracarboxylic acid-5,5',6,6'-dianhydride, norbonan-2-spiro-α-cyclopentanone-α'-spiro-2''-norbonan-5,5',6,6'-tetracarboxylic acid anhydride (CpODA), 2,2-propylidene-4,4'-bis(cyclohexane-1,2-dicarboxylic acid) dianhydride, oxy-4,4'-bis(cyclohexane-1,2-dicarboxylic acid) dianhydride, bicyclo[2.2.2]oct-7-en-2,3,5,6-tetracarboxylic acid dianhydride, bicyclo[2.2.2]octane-2,3:5,6-tetracarboxylic acid dianhydride (BODA), Examples include bicyclo[4.4.0]decan-2,3,6,7-tetracarboxylic acid dianhydride.

[0159] Examples of aliphatic tetracarboxylic acid dianhydrides include 1,2,3,4-butanetetracarboxylic acid dianhydride.

[0160] Meanwhile, in the present specification, an aromatic tetracarboxylic acid dianhydride means a tetracarboxylic acid dianhydride containing one or more aromatic rings, an alicyclic tetracarboxylic acid dianhydride means a tetracarboxylic acid dianhydride containing one or more alicyclic rings and not an aromatic ring, and an aliphatic tetracarboxylic acid dianhydride means a tetracarboxylic acid dianhydride containing neither aromatic rings nor alicyclic rings.

[0161] The tetracarboxylic acid dianhydride optionally included may be one type or two or more types.

[0162] (Diamine)

[0163] The above diamine comprises a constituent unit (B1) derived from a compound represented by the following formula (b1). Additionally, it is preferable not to include the following structural element (c).

[0164] [Chemical Formula 12]

[0165]

[0166] (In formula (c), X is a fluorine atom, a hydrogen atom, or a carbon atom.)

[0167] By including a compound represented by formula (b1) in the diamine, the elastic modulus or strength can be increased while maintaining the transparency or solvent solubility of the polyimide resin without including a perfluoroalkyl structure or a polyfluoroalkyl structure represented by structural element (c).

[0168] The proportion of the compound represented by formula (b1) in the diamine is preferably 40 to 100 mol%, more preferably 50 to 100 mol%, even more preferably 70 to 100 mol%, even more preferably 80 to 100 mol%, even more preferably 85 to 100 mol%, and even more preferably 85 to 95 mol%. The diamine may consist only of the compound represented by formula (b1).

[0169] The diamine may consist solely of the compound represented by formula (b1) or may include a diamine other than the compound represented by formula (b1). Preferably, as a diamine other than the compound represented by formula (b1), it further comprises at least one selected from the group consisting of the compound represented by formula (b2), the compound represented by formula (b3), the compound represented by formula (b4), the compound represented by formula (b5), and the compound represented by formula (b6).

[0170] [Chemical Formula 13]

[0171]

[0172] (In formula (b6), R is independently a hydrogen atom or a methyl group, Y is a divalent group having 12 to 30 carbon atoms containing an aromatic ring, and n is 0 or 1.)

[0173] The diamine preferably comprises at least one selected from the group consisting of a compound represented by formula (b2), a compound represented by formula (b3), a compound represented by formula (b4), a compound represented by formula (b5), and a compound represented by formula (b6); more preferably, it comprises at least one selected from the group consisting of a compound represented by formula (b2), a constituent unit (B3) derived from a compound represented by formula (b3), and a compound represented by formula (b6); more preferably, it comprises at least one selected from the group consisting of a compound represented by formula (b2) and a compound represented by formula (b6); and even more preferably, it comprises a compound represented by formula (b6).

[0174] Examples of compounds represented by formula (b2) include 4,4'-diaminodiphenylsulfone (4,4'-DDS) in which all amino groups are at the 4th position and 3,3'-diaminodiphenylsulfone (3,3'-DDS) in which all amino groups are at the 3rd position, and 4,4'-diaminodiphenylsulfone (4,4'-DDS) is preferred.

[0175] The transparency of the polyimide resin can be improved by including a compound represented by formula (b2) in the diamine.

[0176] By including a compound represented by formula (b3) in the diamine, the elastic modulus, strength, and elongation of the polyimide resin can be improved.

[0177] By including a compound represented by formula (b4) in the diamine, the elastic modulus, strength, and elongation of the polyimide resin can be improved.

[0178] By including a compound represented by formula (b5) in the diamine, the elastic modulus, strength, and elongation of the polyimide resin can be improved.

[0179] In formula (b6), R is independently a hydrogen atom or a methyl group, Y is a divalent group having 12 to 30 carbon atoms containing an aromatic ring, and n is 0 or 1.

[0180] R is independently a hydrogen atom or a methyl group, preferably a hydrogen atom, and more preferably both Rs are hydrogen atoms.

[0181] n is 0 or 1, preferably 0.

[0182] In formula (b6), when both Rs are hydrogen atoms and n is 0, the compound represented by formula (b6) is 4,4'-diaminobenzanilide (DABA).

[0183] By including a constituent unit derived from 4,4'-diaminobenzanilide (DABA) among the compounds represented by formula (b6), the colorless transparency and elongation can be improved while maintaining the high elastic modulus or strength of the polyimide resin.

[0184] In formula (b6), when n is 1, the compound represented by formula (b6) includes Y, a divalent group having 12 to 30 carbon atoms.

[0185] Y is a divalent group having 12 to 30 carbon atoms containing an aromatic ring, and preferably a divalent group having 12 to 26 carbon atoms containing an aromatic ring.

[0186] Among the compounds represented by formula (b6), preferred compounds when n is 1 include the compound represented by the following formula (b61), the compound represented by the following formula (b62), the compound represented by the following formula (b63), and the compound represented by the following formula (b64).

[0187] The compound represented by formula (b6) is preferably at least one selected from the group consisting of the compound represented by the following formula (b61), the compound represented by the following formula (b62), the compound represented by the following formula (b63), and the compound represented by the following formula (b64); more preferably, it is at least one selected from the group consisting of the compound represented by the following formula (b61), the compound represented by the following formula (b62), and the compound represented by the following formula (b63); even more preferably, it is at least one selected from the group consisting of the compound represented by the following formula (b61) and the compound represented by the following formula (b63); and even more preferably, it is the compound represented by the following formula (b61).

[0188] [Chemical Formula 14]

[0189]

[0190] The compound represented by formula (b61) is N,N'-(2,2'-dimethyl[1,1'-biphenyl]-4,4'-diyl)bis[4-amino-3-methylbenzamide](AMB-mTOL).

[0191] By including a compound represented by formula (b61) in the diamine, transparency and elongation can be improved while maintaining the high elastic modulus or strength of the polyimide resin.

[0192] The compound represented by formula (b62) is N,N'-[(octahydro-1,3,5,7-tetraoxobenzo[1,2-c:4,5-c']dipyrrole-2,6(1H,3H)-diyl)bis(3-methoxy-4,1-phenylene)]bis[4-amino-benzamide](AB-MP-HPMDI).

[0193] By including a compound represented by formula (b62) in the diamine, transparency and elongation can be improved while maintaining the high elastic modulus or strength of the polyimide resin.

[0194] The compound represented by formula (b63) is N,N'-(2,2'-dimethyl[1,1'-biphenyl]-4,4'-diyl)bis[4-amino-benzamide](AB-mTOL).

[0195] By including a compound represented by formula (b63) in the diamine, transparency and elongation can be improved while maintaining the high elastic modulus or strength of the polyimide resin.

[0196] The compound represented by formula (b64) is N,N'-(oxydi-4,1-phenylene)bis[4-amino-benzamide](AB-44ODA).

[0197] By including a compound represented by formula (b64) in the diamine, transparency and elongation can be improved while maintaining the high elastic modulus or strength of the polyimide resin.

[0198] As described above, by including a compound represented by formula (b6) in the diamine, it is possible to improve transparency and elongation while maintaining the high elastic modulus or strength of the polyimide resin.

[0199] The sum of the proportions of the compound represented by formula (b2), the compound represented by formula (b3), the compound represented by formula (b4), the compound represented by formula (b5), and the compound represented by formula (b6) in the diamine is preferably 50 mol% or less.

[0200] The sum of the proportions of the compound represented by formula (b2), the compound represented by formula (b3), the compound represented by formula (b4), the compound represented by formula (b5), and the compound represented by formula (b6) in the diamine is more preferably 1 to 50 mol%, even more preferably 1 to 40 mol%, even more preferably 1 to 30 mol%, even more preferably 3 to 25 mol%, even more preferably 3 to 20 mol%, even more preferably 5 to 20 mol%, and even more preferably 5 to 15 mol%. By making the sum of the proportions of the compound represented by formula (b2), the compound represented by formula (b3), the compound represented by formula (b4), the compound represented by formula (b5), and the compound represented by formula (b6) in the diamine within the above range, it is possible to improve transparency and elongation while maintaining the high elastic modulus and strength of the polyimide resin obtained.

[0201] The molar ratio of the compound represented by formula (b1) to the sum of the compound represented by formula (b2), the compound represented by formula (b3), the compound represented by formula (b4), the compound represented by formula (b5) and the compound represented by formula (b6) in the diamine [(b1) / ((b2)+(b3)+(b4)+(b5)+(b6))] is preferably 50 / 50 to 99 / 1, more preferably 60 / 40 to 99 / 1, even more preferably 70 / 30 to 99 / 1, even more preferably 75 / 25 to 97 / 3, even more preferably 80 / 20 to 97 / 3, even more preferably 80 / 20 to 95 / 5, and even more preferably 85 / 15 to 95 / 5. By setting the molar ratio of the compound represented by formula (b1) to the sum of the compound represented by formula (b2), the compound represented by formula (b3), the compound represented by formula (b4), the compound represented by formula (b5), and the compound represented by formula (b6) in the diamine to the above range, the transparency and elongation can be improved while maintaining the high elastic modulus and strength of the polyimide resin obtained.

[0202] The sum of the proportions of the compound represented by formula (b1), the compound represented by formula (b2), the compound represented by formula (b3), the compound represented by formula (b4), the compound represented by formula (b5), and the compound represented by formula (b6) in the diamine is preferably 70 mol% or more, more preferably 80 mol% or more, even more preferably 90 mol% or more, and also preferably 100 mol% or less. The diamine may be only the compound represented by formula (b1), the compound represented by formula (b2), the compound represented by formula (b3), the compound represented by formula (b4), the compound represented by formula (b5), and the compound represented by formula (b6).

[0203] Diamines may include diamines other than the compound represented by formula (b1), the compound represented by formula (b2), the compound represented by formula (b3), the compound represented by formula (b4), the compound represented by formula (b5), and the compound represented by formula (b6). Such diamines are not particularly limited but may include aromatic diamines, alicyclic diamines, and aliphatic diamines, excluding the compound represented by formula (b1), the compound represented by formula (b2), the compound represented by formula (b3), the compound represented by formula (b4), the compound represented by formula (b5), and the compound represented by formula (b6).

[0204] Aromatic diamines other than the above compounds include bis(4-aminophenyl)terephthalate (APTP), 1,4-bis(4-aminobenzoyloxy)benzene, 4,4'-diaminodiphenyl ether (4,4'-ODA), 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane (DDM), 9,9-bis(4-aminophenyl)fluorene (BAFL), 4,4'-diaminobiphenyl (benzidine), 4,4'-diamino-3,3'-dimethylbiphenyl, 4,4'-diaminodiphenyl sulfide, 4,4'-diaminobenzophenone, 2,2-bis(3-aminophenyl)propane, 2,2-bis(4-aminophenyl)propane, 5-amino-1,3,3-trimethyl-1-(4-aminophenyl)-indane (5-TMDM), 6-amino-1,3,3-trimethyl-1-(4-aminophenyl)-indane(6-TMDM), 1,3-bis(3-amino-α,α-dimethylbenzyl)benzene, 1,3-bis(4-amino-α,α-dimethylbenzyl)benzene (BisAM), 1,4-bis(4-amino-α,α-dimethylbenzyl)benzene (BisAP), 4,4'-bis(3-aminophenoxy)biphenyl, 4,4'-bis(4-aminophenoxy)biphenyl (BODA), 1,1-bis[4-(4-aminophenoxy)phenyl]cyclohexane, 2,2-bis[4-(4-aminophenoxy)phenyl]propane (BAPP), 1,4-bis(3-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene, Examples include 1,3-bis(3-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, bis[4-(3-aminophenoxy)phenyl]ketone, bis[4-(4-aminophenoxy)phenyl]ketone, bis[4-(3-aminophenoxy)phenyl]sulfide, bis[4-(4-aminophenoxy)phenyl]sulfide, bis[4-(3-aminophenoxy)phenyl]ether, bis[4-(4-aminophenoxy)phenyl]ether, bis[4-(3-aminophenoxy)phenyl]sulfone, bis[4-(4-aminophenoxy)phenyl]sulfone, 4,4-diaminobenzanilide, 4-aminobenzoic acid-4-aminophenyl, 3,4-diaminobenzanilide, etc.

[0205] Examples of alicyclic diamines include 1,3-bis(aminomethyl)cyclohexane (1,3-BAC), 1,4-bis(aminomethyl)cyclohexane, 1,3-cyclohexyldiamine, 1,4-cyclohexyldiamine, isophoronediamine, bis(aminomethyl)norbonane, 4,4'-diaminodicyclohexylmethane, 4,4'-diaminodicyclohexyl ether, 2,2-bis(4-aminocyclohexyl)propane, etc.

[0206] Examples of aliphatic diamines include ethylenediamine and hexamethylenediamine.

[0207] Meanwhile, in this specification, an aromatic diamine means a diamine containing one or more aromatic rings, a diamine alicyclic means a diamine containing one or more alicyclic rings and not an aromatic ring, and an aliphatic diamine means a diamine that does not contain either an aromatic ring or alicyclic rings.

[0208] The diamine optionally included may be one type or two or more types.

[0209] (Base catalyst)

[0210] Examples of the above base catalysts include organic base catalysts such as pyridine, quinoline, isoquinoline, α-picoline, β-picoline, 2,4-rutidine, 2,6-rutidine, trimethylamine, triethylamine (TEA), tripropylamine, tributylamine, triethylenediamine, imidazole, N,N-dimethylaniline, N,N-diethylaniline, etc., and inorganic base catalysts such as potassium hydroxide, sodium hydroxide, potassium carbonate, sodium carbonate, potassium bicarbonate, sodium bicarbonate, etc.

[0211] The above base catalyst may be used alone or in combination of two or more types.

[0212] Among the above, from the perspective of handling, an organic base catalyst is more preferable, at least one selected from the group consisting of triethylamine and triethylenediamine is more preferable, and using both triethylamine and triethylenediamine is more preferable.

[0213] The amount of base catalyst used in the process is preferably 100 mol% or less with respect to the amount of tetracarboxylic acid dianhydride, more preferably 1 to 100 mol%, even more preferably 1 to 60 mol%, even more preferably 5 to 60 mol%, even more preferably 10 to 60 mol%, even more preferably 30 to 60 mol%, and even more preferably 40 to 60 mol%.

[0214] In order to increase the proportion of the trans-type structure derived from (1R,2S,4S,5R)-cyclohexanetetracarboxylic acid dianhydride of the constituent unit (A1) derived from the compound represented by formula (a1) of the obtained polyimide resin, it is preferable to use at least 30 mol% of the amount of base catalyst relative to the amount of tetracarboxylic acid dianhydride.

[0215] The amount of triethylamine used in the process is preferably 100 mol% or less with respect to the amount of tetracarboxylic acid dianhydride, more preferably 1 to 90 mol%, even more preferably 1 to 60 mol%, even more preferably 5 to 60 mol%, even more preferably 10 to 60 mol%, even more preferably 10 to 55 mol%, even more preferably 30 to 55 mol%, and even more preferably 40 to 55 mol%.

[0216] When both triethylamine and triethylenediamine are used, the amount of triethylenediamine is preferably 50 mol% or less with respect to the amount of tetracarboxylic acid dianhydride, more preferably 1 to 50 mol%, even more preferably 1 to 20 mol%, even more preferably 1 to 10 mol%, even more preferably 1 to 7 mol%, even more preferably 1 to 6 mol%, even more preferably 2 to 6 mol%, and even more preferably 3 to 6 mol%.

[0217] In this process, it is preferable that the amount of base catalyst used is equal to the amount of tetracarboxylic acid dianhydride with respect to the amount of diamine.

[0218] Accordingly, the amount of base catalyst used in the process is preferably 100 mol% or less with respect to the amount of tetracarboxylic acid dianhydride and the diamine, more preferably 1 to 100 mol%, even more preferably 1 to 60 mol%, even more preferably 5 to 60 mol%, even more preferably 10 to 60 mol%, even more preferably 30 to 60 mol%, and even more preferably 40 to 60 mol%.

[0219] In order to increase the proportion of the trans-type structure derived from (1R,2S,4S,5R)-cyclohexanetetracarboxylic acid dianhydride of the constituent unit (A1) derived from the compound represented by formula (a1) of the obtained polyimide resin, it is preferable to use at least 30 mol% of the amount of base catalyst with respect to the amount of the tetracarboxylic acid dianhydride and the diamine.

[0220] The amount of triethylamine used in the process is preferably 100 mol% or less with respect to the amount of tetracarboxylic acid dianhydride and the diamine, more preferably 1 to 90 mol%, even more preferably 1 to 60 mol%, even more preferably 5 to 60 mol%, even more preferably 10 to 60 mol%, even more preferably 10 to 55 mol%, even more preferably 30 to 55 mol%, and even more preferably 40 to 55 mol%.

[0221] When both triethylamine and triethylenediamine are used, the amount of triethylenediamine is preferably 50 mol% or less with respect to the amount of tetracarboxylic acid dianhydride and the diamine, more preferably 1 to 50 mol%, even more preferably 1 to 20 mol%, even more preferably 1 to 10 mol%, even more preferably 1 to 7 mol%, even more preferably 1 to 6 mol%, even more preferably 2 to 6 mol%, and even more preferably 3 to 6 mol%.

[0222] Meanwhile, "regarding the amount of the tetracarboxylic acid dianhydride and the diamine" means "regarding the amount of the tetracarboxylic acid dianhydride and the same with respect to the amount of the diamine."

[0223] (Organic solvent)

[0224] The organic solvent used in the present manufacturing method preferably includes a lactone-based solvent.

[0225] Examples of lactone-based solvents include γ-butyrolactone (GBL) and γ-valerolactone, and γ-butyrolactone (GBL) is preferred.

[0226] The proportion of the lactone-based solvent included in the above organic solvent is preferably 10 to 100 mass% with respect to the total amount of organic solvent, more preferably 30 to 100 mass%, even more preferably 50 to 100 mass%, even more preferably 70 to 100 mass%, even more preferably 90 to 100 mass%, even more preferably 95 to 100 mass%, and even more preferably 99 to 100 mass%, and the above organic solvent may consist only of the lactone-based solvent.

[0227] The above organic solvent may include organic solvents other than lactone-based solvents. Such organic solvents are not particularly limited, but examples include aprotic solvents other than lactone-based solvents, phenolic solvents, etc.

[0228] Examples of non-protonic solvents other than lactone solvents include amide solvents, glycol solvents, phosphorus-containing amide solvents, sulfur-containing solvents, ketone solvents, amine solvents, ester solvents, ether solvents, carbonate solvents, etc.

[0229] Examples of amide solvents include N,N-dimethylformamide, N,N-dimethylacetamide, N-methylcaprolactam, 1,3-dimethylimidazolidinone, tetramethylurea, 3-methoxy-N,N-dimethylpropanamide, 3-butoxy-N,N-dimethylpropanamide, etc.

[0230] Examples of glycol-based solvents include diethylene glycol dimethyl ether, triethylene glycol, and triethylene glycol dimethyl ether.

[0231] Examples of phosphorus-containing amide solvents include hexamethylphosphoricamide and hexamethylphosphintriamide.

[0232] Examples of sulfur-containing solvents include dimethyl sulfone, dimethyl sulfoxide, and sulfolane.

[0233] Examples of ketone solvents include acetone, cyclopentanone, cyclohexanone, and methylcyclohexanone.

[0234] Examples of amine-based solvents include picoline and pyridine.

[0235] Examples of ester-based solvents include acetic acid (2-methoxy-1-methyl ethyl).

[0236] Examples of ether-based solvents include 1,2-dimethoxyethane, bis(2-methoxyethyl)ether, 1,2-bis(2-methoxyethoxy)ethane, bis[2-(2-methoxyethoxy)ethyl]ether, tetrahydrofuran, 1,4-dioxane, etc.

[0237] Examples of carbonate-based solvents include diethyl carbonate, methyl ethyl carbonate, ethylene carbonate, propylene carbonate, etc.

[0238] Examples of phenolic solvents include phenol, o-cresol, m-cresol, p-cresol, 2,3-xylenol, 2,4-xylenol, 2,5-xylenol, 2,6-xylenol, 3,4-xylenol, 3,5-xylenol, etc.

[0239] Among organic solvents other than the above-mentioned lactone-based solvents, aproton-based solvents are preferred, and amide-based solvents are more preferred. In addition, the above-mentioned organic solvents may be used alone or in a mixture of two or more types.

[0240] By including an amide solvent in addition to a lactone solvent in the organic solvent, the proportion of the trans-type structure derived from (1R,2S,4S,5R)-cyclohexanetetracarboxylic acid dianhydride of the constituent unit (A1) derived from the compound represented by formula (a1) of the polyimide resin obtained can be increased.

[0241] Examples of lactone-based solvents include γ-butyrolactone (GBL) and γ-valerolactone, and γ-butyrolactone (GBL) is preferred.

[0242] Examples of amide-based solvents include N,N-dimethylformamide, N,N-dimethylacetamide, N-methylcaprolactam, 1,3-dimethylimidazolidinone, tetramethylurea, 3-methoxy-N,N-dimethylpropanamide, 3-butoxy-N,N-dimethylpropanamide, etc., and N,N-dimethylacetamide is preferred.

[0243] (Imidization condition)

[0244] The present manufacturing method comprises a process of imidizing the tetracarboxylic acid dianhydride and the diamine in the presence of the base catalyst and the organic solvent, and it is preferable to carry out the imidization reaction under the following conditions.

[0245] In this process, the input ratio of tetracarboxylic acid dianhydride to diamine is preferably 0.9 to 1.1 moles of diamine per 1 mole of tetracarboxylic acid dianhydride.

[0246] In addition, in this process, in addition to tetracarboxylic acid dianhydride and diamine, a terminal encapsulant may be used. Monoamines or dicarboxylic acids are preferred as terminal encapsulants. The amount of terminal encapsulant introduced is preferably 0.0001 to 0.1 mole per 1 mole of tetracarboxylic acid dianhydride, and more preferably 0.001 to 0.06 mole. Examples of monoamine terminal encapsulants include methylamine, ethylamine, propylamine, butylamine, benzylamine, 4-methylbenzylamine, 4-ethylbenzylamine, 4-dodecylbenzylamine, 3-methylbenzylamine, 3-ethylbenzylamine, aniline, 3-methylaniline, 4-methylaniline, etc., and benzylamine and aniline are preferred. As for dicarboxylic acid terminal encapsulants, dicarboxylic acids are preferred, and a portion thereof may be ring-closed. Examples include phthalic acid, phthalic anhydride, 4-chlorophthalic acid, tetrafluorophthalic acid, 2,3-benzophenone dicarboxylic acid, 3,4-benzophenone dicarboxylic acid, cyclohexane-1,2-dicarboxylic acid, cyclopentane-1,2-dicarboxylic acid, 4-cyclohexene-1,2-dicarboxylic acid, etc., and phthalic acid and phthalic anhydride are preferred.

[0247] There are no particular restrictions on the method of reacting tetracarboxylic acid dianhydride with diamine, and known methods can be used.

[0248] Specific reaction methods include: (1) a method of introducing a tetracarboxylic acid dianhydride, a diamine, and an organic solvent into a reactor, stirring at 0 to 80°C for 0.5 to 30 hours, and then raising the temperature to carry out an imidation reaction; (2) a method of introducing a diamine and an organic solvent into a reactor and dissolving them, then introducing a tetracarboxylic acid dianhydride, stirring at 0 to 80°C for 0.5 to 30 hours as needed, and then raising the temperature to carry out an imidation reaction; and (3) a method of introducing a tetracarboxylic acid dianhydride, a diamine, and an organic solvent into a reactor and immediately raising the temperature to carry out an imidation reaction.

[0249] In the imidation reaction, it is preferable to carry out the reaction while removing water generated during manufacturing using a Dean Stark apparatus or the like. By performing such operations, the degree of polymerization and the imidation rate can be further increased.

[0250] The temperature of the imidation reaction is preferably 120 to 250°C, more preferably 160 to 200°C, in terms of the reaction rate and inhibition of gelation. In addition, the reaction time is preferably 0.5 to 10 hours after the start of the discharge of the generated water.

[0251] [Polyimide Varnish]

[0252] The polyimide varnish of the present invention is formed by dissolving the polyimide resin of the present invention in an organic solvent. That is, the polyimide varnish of the present invention comprises the polyimide resin of the present invention and an organic solvent, wherein the polyimide resin is dissolved in the organic solvent.

[0253] The organic solvent may be any solvent that dissolves the polyimide resin and is not particularly limited, but it is preferable to use the compounds described above as an organic solvent used in the manufacture of the polyimide resin, either alone or in a mixture of two or more.

[0254] The polyimide varnish of the present invention may be the solution of a polyimide resin obtained by polymerizing and imidizing in an organic solvent as described above, or it may be a solution diluted by adding an organic solvent to the said polyimide solution.

[0255] Since the polyimide resin of the present invention has solvent solubility, it can be made into a high-concentration varnish that is stable at room temperature. The polyimide varnish of the present invention preferably contains 5 to 40 mass% of the polyimide resin of the present invention, more preferably contains 8 to 30 mass%, and even more preferably contains 10 to 20 mass%. The viscosity of the polyimide varnish is preferably 1 to 200 Pa·s, and more preferably 1 to 100 Pa·s. The viscosity of the polyimide varnish is a value measured at 25°C using an E-type viscometer.

[0256] In addition, the polyimide varnish of the present invention may include various additives such as inorganic fillers, adhesion promoters, release agents, flame retardants, UV stabilizers, antioxidants, surfactants, leveling agents, defoaming agents, fluorescent whitening agents, crosslinking agents, polymerization initiators, and photosensitizers, to the extent that the required properties of the polyimide resin and polyimide film are not impaired.

[0257] The method for manufacturing the polyimide varnish of the present invention is not particularly limited, and known methods may be applied.

[0258] The organic solvent may be any solvent that dissolves the polyimide resin and is not particularly limited; however, it is preferable to use the compounds described above, either alone or in a mixture of two or more, as the organic solvent used for the manufacture of the polyimide resin. Among these, at least one selected from the group consisting of lactone-based solvents and amide-based solvents is preferred, a lactone-based solvent is more preferred, and it is even more preferable to include both a lactone-based solvent and an amide-based solvent. At least one selected from the group consisting of γ-butyrolactone (GBL) and N,N-dimethylacetamide is more preferred, γ-butyrolactone (GBL) is more preferred, and it is even more preferable to include both γ-butyrolactone (GBL) and N,N-dimethylacetamide. By including the above solvent, the solubility and coating properties of the polyimide resin are improved.

[0259] As an organic solvent included in the polyimide varnish, only γ-butyrolactone may be included. The polyimide varnish preferably contains γ-butyrolactone in an amount of 20 mass% or more based on the total amount of the polyimide varnish, more preferably 20 to 90 mass%, even more preferably 20 to 70 mass%, more preferably 20 to 60 mass%, more preferably 20 to 50 mass%, more preferably 30 to 50 mass%, and more preferably 30 to 45 mass%.

[0260] In addition, the organic solvent included in the polyimide varnish preferably contains γ-butyrolactone in an amount of 30 mass% or more relative to the total amount of the organic solvent, more preferably 30 to 95 mass%, even more preferably 30 to 80 mass%, more preferably 30 to 70 mass%, more preferably 35 to 60 mass%, and more preferably 35 to 50 mass%.

[0261] As an organic solvent included in the polyimide varnish, it is preferable to include an amide-based solvent in an amount of 1% or more based on the total amount of the polyimide varnish, more preferable to include 5 to 70% by weight, even more preferable to include 20 to 70% by weight, even more preferable to include 25 to 70% by weight, even more preferable to include 35 to 70% by weight, even more preferable to include 35 to 60% by weight, and even more preferable to include 40 to 60% by weight.

[0262] In addition, the organic solvent included in the polyimide varnish preferably contains an amide-based solvent in an amount of 1 mass% or more relative to the total amount of organic solvent, more preferably 5 to 70 mass%, even more preferably 20 to 70 mass%, more preferably 30 to 70 mass%, more preferably 40 to 65 mass%, and more preferably 50 to 65 mass%.

[0263] [Polyimide Film]

[0264] The polyimide film of the present invention comprises the polyimide resin. Accordingly, the polyimide film of the present invention does not include a perfluoroalkyl structure or a polyfluoroalkyl structure, has excellent colorless transparency, high elastic modulus, and excellent elongation.

[0265] The suitable physical properties of the polyimide film of the present invention are as follows.

[0266] The polyimide film of the present invention, preferably, when the thickness is 50 μm, has a YI of 7.5 or less, a total light transmittance of 80% or more, and a haze of 1.0% or less; a tensile fracture elongation of 5% or more when subjected to a tensile test under conditions of 23°C and 50% RH, a test specimen of 50 μm × 10 mm × 120 mm, a tensile speed of 20 mm / min, and a chuck spacing of 50 mm; and a tensile modulus of elasticity calculated by the slope of the least squares method in the stress-strain curve obtained by the tensile test from 0.1 mm to 0.5 mm of strain is 3.7 GPa or more. This will be explained in more detail below.

[0267] When the thickness is 50 μm, the YI is preferably 7.5 or less, more preferably 7.2 or less, even more preferably 5.0 or less, even more preferably 4.0 or less, and even more preferably 3.0 or less.

[0268] The total light transmittance when the thickness is 50 μm is preferably 80% or more, more preferably 85% or more, even more preferably 86% or more, even more preferably 87% or more, and even more preferably 88% or more.

[0269] When the thickness is 50 μm, the haze is preferably 1.0% or less, more preferably 0.9% or less, even more preferably 0.6% or less, even more preferably 0.5% or less, and even more preferably 0.4% or less.

[0270] The tensile fracture point elongation by a tensile test performed under conditions of 23℃ and 50% RH, a test specimen of 50μm×10mm×120mm, a tensile speed of 20mm / min, and a chuck distance of 50mm is preferably 5% or more, more preferably 6% or more, even more preferably 7% or more, even more preferably 8% or more, even more preferably 9% or more, even more preferably 10% or more, and even more preferably 11% or more.

[0271] The tensile modulus calculated by the slope of the least squares method in the strain range from 0.1 mm to 0.5 mm in the stress-strain curve obtained by a tensile test performed under conditions of 23℃ 50% RH environment, a test specimen of 50 μm × 10 mm × 120 mm, a tensile speed of 20 mm / min, and a chuck distance of 50 mm is preferably 3.7 GPa or higher, more preferably 3.8 GPa or higher, even more preferably 3.9 GPa or higher, and even more preferably 4.0 GPa or higher.

[0272] Meanwhile, the physical property values ​​described above in the present invention can be specifically measured by the method described in the examples.

[0273] The polyimide film of the present invention comprises the polyimide resin and, without including a perfluoroalkyl structure or a polyfluoroalkyl structure, exhibits excellent colorless transparency, high elastic modulus, and excellent elongation. Accordingly, the polyimide film of the present invention is suitably used as an optical material or an electronic material, particularly as a material for displays.

[0274] There are no particular limitations on the thickness of the polyimide film of the present invention, but it is preferably 1 to 250 μm, more preferably 5 to 100 μm, even more preferably 8 to 80 μm, and even more preferably 10 to 80 μm. If the thickness of the film is within the above range, it can be suitably used as an optical material or an electronic material, particularly as a material for a display.

[0275] The thickness of the polyimide film can be easily controlled by adjusting the solid content concentration or viscosity of the varnish.

[0276] Method for manufacturing polyimide film

[0277] There are no particular limitations on the method for manufacturing the polyimide film of the present invention, and known methods may be used. For example, it can be obtained by applying a polyimide varnish onto a support and drying it. Among such methods, the manufacturing method described below is preferred.

[0278] That is, a method for manufacturing a polyimide film is preferred, comprising: a coating process of applying the above-mentioned polyimide varnish onto a support to obtain a coating film; a first drying process of drying the coating film and peeling it off from the support to obtain a self-supporting film; and a second drying process of drying the self-supporting film at 210°C or higher, preferably 220°C or higher.

[0279] The coating process is a process of obtaining a coating film by applying polyimide varnish onto a support.

[0280] As a support, a glass plate, metal plate, metal drum, metal belt, or plastic film having a smooth surface is preferred, and a glass plate or plastic film is more preferred. In addition, from the perspective of improving productivity, it is preferable to use an endless support such as a metal drum or metal belt, or a long plastic film, as a support, and to manufacture a polyimide film by roll-to-roll.

[0281] Known coating methods include spin coating, slit coating, blade coating, and die coating. Glass rods or coaters may also be used.

[0282] It is preferable to apply the coating such that the thickness of the polyimide film after drying is preferably 1 to 250 μm, more preferably 5 to 100 μm, even more preferably 8 to 80 μm, and even more preferably 10 to 80 μm.

[0283] If necessary, a release agent may be applied to the surface of the above support in advance.

[0284] The first drying process is a process of drying the coating film and peeling it off from the support to obtain a self-supporting film.

[0285] The first drying is a process of removing a portion of the organic solvent to obtain a self-supporting film, and the organic solvent is removed by heating the coating film on the support.

[0286] The temperature for removing the organic solvent is preferably 50 to 140°C, and more preferably 50 to 120°C. To prevent prolonged heating, the temperature may be gradually increased. In that case, the temperature for the first step is preferably 50 to 90°C, and more preferably 50 to 70°C. The final temperature is preferably 80 to 140°C, and more preferably 90 to 120°C. It is preferable to remove the organic solvent under a nitrogen atmosphere. The removal of the organic solvent may be performed under reduced pressure, atmospheric pressure, or pressurized pressure.

[0287] The obtained film is peeled off from the support. The film after peeling is self-supporting.

[0288] The second drying process is a process of drying the self-supporting film at 210°C or higher.

[0289] The ends of the self-supporting film obtained in the previous process are fixed and dried at 210°C or higher.

[0290] The temperature of the second drying is preferably 210 to 300°C, more preferably 210 to 280°C, even more preferably 210 to 260°C, even more preferably 220 to 260°C, and even more preferably 220 to 240°C. By setting the temperature of the second drying to the above range, the elastic modulus can be increased, and furthermore, colorless transparency and high elastic modulus can be achieved simultaneously.

[0291] It is preferable to perform the second drying under a nitrogen atmosphere. The second drying may be performed at any pressure, such as reduced pressure, atmospheric pressure, or increased pressure.

[0292] In addition, the time for the second drying can be appropriately adjusted according to the above temperature, preferably 3 to 60 minutes, more preferably 5 to 60 minutes, even more preferably 5 to 30 minutes, and even more preferably 5 to 20 minutes.

[0293] From the perspective of further improving colorless transparency, it is preferable to have it for 3 to 30 minutes, more preferable to have it for 3 to 20 minutes, even more preferable to have it for 3 to 15 minutes, and even more preferable to have it for 5 to 15 minutes.

[0294] Meanwhile, from the perspective of further improving the elastic modulus, it is more desirable to have it for 10 to 50 minutes, more desirable to have it for 15 to 40 minutes, and more desirable to have it for 17 to 28 minutes.

[0295] After the second drying, cooling may be performed, and annealing may be carried out.

[0296] Examples

[0297] The present invention will be specifically explained below by way of examples. However, the present invention is not limited in any way by these examples.

[0298] [Structure of Polyimide Resin]

[0299] Structural analysis of the polyimide resins obtained in the examples and comparative examples was performed by the method shown below.

[0300] (1) Proportion of trans-type structures derived from cyclohexanetetracarboxylic acid dianhydride

[0301] The proportion of the trans-type structure derived from cyclohexanedetatecarboxylic acid dianhydride in polyimide resin is the polyimide resin's 1 The following was calculated by measuring the H-NMR spectrum.

[0302] 1 H-NMR spectrum measurement is performed using an NMR spectrophotometer (ASCEnd TM 500 (manufactured by BRUKER CORPORATION) was used, and measurements were taken using a deuterated dimethyl sulfoxide solution of polyimide resin. From the integrated value of the peak originating from the cyclohexanetetracarboxylic acid portion below, the ratio of the trans-type structure originating from the cyclohexanetetracarboxylic acid dianhydride was calculated.

[0303] 1H NMR(DMSO-d6)

[0304] A = Integral value of the peak in the range δ 2.179 ppm to δ 2.279 ppm (trans-cyclohexanetetracarboxylic acid proton (3rd position, 6th position), 4H)

[0305] Integrated value of the peak in the range B=δ2.279 ppm to δ2.391 ppm (cis-cyclohexanetetracarboxylic acid proton (3rd position, 6th position), 4H)

[0306] Proportion of trans structure (mol%) = A / (A + B) × 100

[0307] [Evaluation of Polyimide Film (Polyimide Resin)]

[0308] The measurement and evaluation of each physical property of the polyimide film (polyimide resin) obtained in the examples and comparative examples were performed by the method shown below.

[0309] (1) Polyimide film thickness

[0310] The thickness of the polyimide film was measured using a micrometer manufactured by Mitutoyo Corporation.

[0311] (2) Tensile modulus, tensile strength, and tensile elongation at break

[0312] Tensile modulus, tensile strength, and tensile elongation at break were measured in accordance with JIS K7127:1999 using a tensile testing machine "Strograph VG-1E" manufactured by Toyo Seiki Co., Ltd. The chuck distance was 50 mm, the specimen size was 10 mm × 120 mm, the test speed (tensile speed) was 20 mm / min, and the measurement temperature was 23℃.

[0313] The tensile modulus was calculated as the slope of the stress-strain curve obtained by the above tensile test, in the range from strain 0.1 mm to 0.5 mm using the least squares method.

[0314] The higher the value of the tensile modulus, the higher the modulus of elasticity of the polyimide film (polyimide resin) and the more desirable it is. The higher the value of the tensile strength, the better the strength of the polyimide film (polyimide resin) and the more desirable it is. Furthermore, the higher the value of the tensile elongation at break, the better the elongation of the polyimide film (polyimide resin) and the more desirable it is.

[0315] (3) Haze, total light transmittance, and yellow index (YI)

[0316] Haze was measured in accordance with JIS K7136:2000, total light transmittance in accordance with JIS K7361-1:1997, and YI in accordance with ASTM E313-05 (D light source, 65°), all using a color and turbidity simultaneous measuring instrument (COH7700, manufactured by Nippon Color Industry Co., Ltd.).

[0317] The smaller the haze value, the better the transparency of the polyimide film (polyimide resin). The larger the total light transmittance value, the better the transparency of the polyimide film (polyimide resin). The smaller the YI value of the polyimide film, the better the colorlessness of the polyimide film (polyimide resin).

[0318] <Abbreviations for ingredients, etc.>

[0319] The tetracarboxylic acid dianhydrides and diamines used in the examples and comparative examples, and their abbreviations, are as follows.

[0320] (Tetracarboxylic acid dianhydride)

[0321] HPMDA: 1,2,4,5-cyclohexanetetracarboxylic acid dianhydride (compound represented by formula (a1), manufactured by Mitsubishi Gas & Chemical Corporation)

[0322] CBDA: 1,2,3,4-cyclobutanetetracarboxylic acid dianhydride (compound represented by formula (a2))

[0323] (Diamine)

[0324] mTB: 2,2'-dimethylbenzidine (compound represented by formula (b1), manufactured by Seika Corporation)

[0325] 4,4'-DDS: 4,4'-diaminodiphenylsulfone (compounds represented by formula (b2), all amino groups at the 4th position)

[0326] 3,3'-DDS: 3,3'-diaminodiphenylsulfone (compound represented by formula (b2), all amino groups at the 3rd position, manufactured by Seika Corporation)

[0327] 8FBZ: Octafluorobenzidine (compound represented by formula (b3))

[0328] DABA: 4,4'-diaminobenzanilide (compound represented by formula (b6), n=0, R are all hydrogen atoms, manufactured by Seika Corporation)

[0329] AMB-mTOL: N,N'-(2,2'-dimethyl[1,1'-biphenyl]-4,4'-diyl)bis[4-amino-3-methylbenzamide](compound represented by formula (b61))

[0330] The abbreviations of the solvents and catalysts used in the examples and comparative examples are as follows.

[0331] GBL: γ-butyrolactone (Mitsubishi Chemical Corporation)

[0332] DMAc: N,N-dimethylacetamide

[0333] TEA: Triethylamine (manufactured by Kanto Chemical Co., Ltd.)

[0334] TEDA: Triethylenediamine

[0335] <Manufacture of Polyimide Resin, Polyimide Varnish, and Polyimide Film>

[0336] Example 1

[0337] 16.938 g (0.0798 mol) of the diamine mTB and 64.17 g of GBL were added to a 500 mL five-necked round-bottom flask equipped with a stainless steel crescent-shaped stirring blade, a nitrogen inlet tube, a cooling tube, a Dean Stark, a thermometer, and a glass end cap, and a solution was obtained by stirring at a rotation speed of 200 rpm under a nitrogen atmosphere at an internal temperature of 70°C.

[0338] To this solution, 14.308 g (0.0638 mol) of the tetracarboxylic acid dianhydride HPMDA, 3.129 g (0.0160 mol) of CBDA, and 8.02 g of GBL were added in a batch, followed by the addition of 4.04 g (0.0399 mol) of TEA and 0.447 g (0.0040 mol) of TEDA as imidization catalysts, and GBL as a solvent. The mixture was heated with a mantle heater, and the temperature inside the reaction system was raised to 190°C over approximately 20 minutes. While collecting the evaporating components, the temperature inside the reaction system was maintained at 190°C and refluxed for 1 hour to obtain a solution containing polyimide resin. DMAc was added to achieve a solid content concentration of 15 mass%, and the temperature in the reaction system was cooled to 50°C to obtain a polyimide varnish containing polyimide resin (solvent composition (mass) in the varnish GBL / DMAc=38 / 47).

[0339] The obtained polyimide varnish was subsequently applied onto a PET (polyethylene terephthalate) substrate, maintained at 60°C for 20 minutes using a hot plate, then maintained at 80°C for 20 minutes, and subsequently heated in a hot air dryer at 220°C for 20 minutes under an air atmosphere to evaporate the solvent, thereby obtaining a polyimide film. The physical properties and evaluation results of the film are shown in Table 1.

[0340] Examples 2–7 and Comparative Examples 1–5

[0341] In Example 1, a polyimide varnish containing a polyimide resin was obtained by performing the same procedure as in Example 1, except that the types and amounts of the diamine and tetracarboxylic acid dianhydride were changed to the types and amounts of the diamine and tetracarboxylic acid dianhydride shown in Table 1. Furthermore, a polyimide film was obtained by performing the same procedure as in Example 1. The physical properties and evaluation results of the film are shown in Table 1.

[0342] [Table 1]

[0343]

[0344] As shown in Table 1, the polyimide resin (polyimide film) of the example has a high tensile modulus and, in addition to its high tensile strength, a high elongation at the tensile break point and excellent mechanical properties. Furthermore, the polyimide resin (polyimide film) of the example has excellent haze and, in addition, a high total light transmittance.

[0345] In this regard, it can be seen that the polyimide resin of the present invention has excellent transparency, high elastic modulus and high strength, and excellent elongation. Furthermore, it can be seen that the polyimide resin of the present invention is soluble in solvents, as it is dissolved in a solvent as a varnish. In particular, it can be seen that the polyimide resin of the present invention possesses the above properties even though it does not contain a perfluoroalkyl structure or a polyfluoroalkyl structure.

Claims

Claim 1 A polyimide resin having a constituent unit A derived from a tetracarboxylic acid dianhydride and a constituent unit B derived from a diamine, wherein constituent unit A comprises a constituent unit (A1) derived from a compound represented by the following formula (a1) and a constituent unit (A2) derived from a compound represented by the following formula (a2), and constituent unit B comprises a constituent unit (B1) derived from a compound represented by the following formula (b1), wherein the ratio of constituent unit (A2) in constituent unit A is 27 mol% or less, and the polyimide resin does not include the following structural element (c). [Chemical Formula 1] (In formula (c), X is a fluorine atom, a hydrogen atom, or a carbon atom.) Claim 2 A polyimide resin according to claim 1, wherein the proportion of constituent unit (A1) among constituent unit A is 10 to 99 mol%. Claim 3 A polyimide resin according to claim 1 or 2, wherein the molar ratio [(A1) / (A2)] of the constituent unit (A1) to the constituent unit (A2) in constituent unit A is 73 / 27 to 99 / 1. Claim 4 A polyimide resin according to any one of claims 1 to 3, wherein the ratio of the constituent unit (B1) among the constituent units B is 40 to 100 mol%. Claim 5 A polyimide resin according to any one of claims 1 to 4, wherein the constituent unit B further comprises at least one selected from the group consisting of a constituent unit (B2) derived from a compound represented by the following formula (b2), a constituent unit (B3) derived from a compound represented by the following formula (b3), a constituent unit (B4) derived from a compound represented by the following formula (b4), a constituent unit (B5) derived from a compound represented by the following formula (b5), and a constituent unit (B6) derived from a compound represented by the following formula (b6). [Chemical Formula 2] (In formula (b6), R is independently a hydrogen atom or a methyl group, Y is a divalent group having 12 to 30 carbon atoms containing an aromatic ring, and n is 0 or 1.) Claim 6 A polyimide resin according to claim 5, wherein the sum of the ratios of constituent unit (B2), constituent unit (B3), constituent unit (B4), constituent unit (B5) and constituent unit (B6) in constituent unit B is 50 mol% or less. Claim 7 A polyimide resin according to claim 5 or 6, wherein the molar ratio of constituent unit (B1) to the sum of constituent units (B2), constituent unit (B3), constituent unit (B4), constituent unit (B5) and constituent unit (B6) in constituent unit B [(B1) / ((B2)+(B3)+(B4)+(B5)+(B6))] is 50 / 50 to 99 / 1. Claim 8 A polyimide resin according to any one of claims 1 to 7, wherein the proportion of a trans-type structure derived from (1R,2S,4S,5R)-cyclohexanetetracarboxylic acid dianhydride included in the constituent unit (A1) is 30 mol% or more of the constituent unit (A1). Claim 9 A polyimide varnish formed by dissolving a polyimide resin described in any one of claims 1 to 8 in an organic solvent. Claim 10 A polyimide film comprising a polyimide resin described in any one of claims 1 to 8. Claim 11 A polyimide film according to claim 10, wherein, when the thickness is 50 μm, the YI is 7.5 or less, the total light transmittance is 80% or more, the haze is 1.0% or less, the tensile fracture point elongation is 5% or more when a tensile test is performed under conditions of a test specimen of 50 μm × 10 mm × 120 mm, a tensile speed of 20 mm / min, and a chuck spacing of 50 mm in an environment of 23°C and 50% RH, and the tensile modulus calculated by the slope of the least squares method in the strain range from 0.1 mm to 0.5 mm in the stress-strain curve obtained by the tensile test is 3.7 GPa or more. Claim 12 A polyimide film having a thickness of 5 to 100 μm, according to claim 10 or 11.

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