Polymer Composition, Varnish, and Polyimide Film

Abstract

A polymer composition comprising a polymer (X) and a compound (Y) represented by the following general formula (3), wherein the polymer (X) comprises at least one selected from the group consisting of repeating units represented by the following general formula (1) and repeating units represented by the following general formula (2). (In formula (1), X 1 is a tetravalent group having an alicyclic structure or an aromatic ring, and X is a single bond or the like. In formula (2), X 2 is a tetravalent group having an alicyclic structure or an aromatic ring, R 1 and R 2 are each independently hydrogen, an alkyl group having 1 to 6 carbon atoms or the like, and X is a single bond or the like. In formula (3), R 3 is an alkyl group having 1 to 30 carbon atoms or the like, and n is 0 to 2.)

Description

Technical Field

[0001] The present invention relates to a polymer composition, a varnish, and a polyimide film. Background Art

[0002] Polyimide resins have excellent mechanical properties and heat resistance, and thus various uses are being studied in fields such as electrical / electronic components. For example, it is desired to replace a glass substrate used in an image display device such as a liquid crystal display or an OLED display with a polyimide film substrate, and a polyimide resin that satisfies the performance as an optical material has been developed.

[0003] However, in recent years, due to the high functionality of electronic devices, electronic components need to satisfy various required performances at the same time. Therefore, for the polyimide resin used in a display, an attempt has also been made to impart new properties or improve the original properties of the resin by blending various additives.

[0004] For example, in Patent Document 1, for the purpose of preventing crystallization and shortening the layer formation time in addition to heat resistance and mechanical properties, a polyimide precursor composition containing a specific polyamic acid and a specific phosphorus compound is disclosed. The polyamic acid can be used to produce a polyimide film having a large water vapor transmission coefficient by performing a heat treatment under the condition that the maximum heating temperature is set to 300 to 500°C.

[0005] In addition, in Patent Document 2, for the purpose of obtaining a polyimide having transparency, heat resistance, and a low linear thermal expansion coefficient, a polyimide precursor composition is disclosed, which includes: a polyimide precursor having a specific repeating unit; and a phosphorus compound containing a phosphorus atom and having a boiling point below the decomposition temperature and 350°C or lower under 1 atmosphere.

[0006] Prior Art Documents

[0007] Patent Documents

[0008] Patent Document 1: International Publication No. 2016 / 121817

[0009] Patent Document 2: International Publication No. 2015 / 080139 Summary of the Invention

[0010] Problems to be Solved by the Invention

[0011] As described above, replacing the glass substrate with a polyimide film requires not only mechanical properties and heat resistance but also high colorless transparency. Further, when manufacturing an image display device, for example, in the TFT process, heat treatment is performed in a state where an inorganic film is laminated on the polyimide, so that the gas released from the polyimide remains between the polyimide and the inorganic film, and sometimes yellowing occurs. It is required that there is no change in hue during heat treatment in a state where an inorganic film is laminated. However, it is difficult to balance these properties, and even if the heat resistance is improved by compounding additives, it is difficult to prevent yellowing and the like.

[0012] In addition, in order to make the polyimide itself exhibit colorless transparency, aliphatic diamines and fluorine-containing diamines are usually used to inhibit the formation of charge transfer complexes between molecules or within molecules. However, for example, in the process of manufacturing TFTs when manufacturing a display, under such severe conditions of 350 °C or higher, aliphatic diamines lack rigidity compared to aromatic diamines, so it is difficult to exhibit heat resistance. In addition, fluorine-containing diamines have a problem of yellowing at high temperatures. Therefore, there is a need for a polyimide film that is particularly excellent in heat resistance, has little change in hue after heat treatment, and further has a low yellowness degree.

[0013] The present invention has been completed in view of such circumstances, and the subject of the present invention is to provide: a polymer composition capable of obtaining a polyimide film excellent in heat resistance, having little change in hue after heat treatment, and further having a low yellowness degree, a varnish containing the composition, and a polyimide film excellent in heat resistance and having a low yellowness degree.

[0014] Means for Solving the Problems

[0015] The present inventors have found that a polymer composition containing a polymer and a specific phosphorus compound can solve the above problems, and the polymer contains a specific fluorine-containing diamine and a repeating unit derived from a tetracarboxylic acid having an alicyclic structure or an aromatic ring, and thus the present invention has been completed.

[0016] That is, the present invention relates to the following [1] to

[10] .

[0017] [1] A polymer composition comprising a polymer (X) and a compound (Y) represented by the following general formula (3), wherein the polymer (X) contains at least one selected from the group consisting of a repeating unit represented by the following general formula (1) and a repeating unit represented by the following general formula (2).

[0018]

[0019] (In formula (1), X 1 is a tetravalent group having an alicyclic structure or an aromatic ring, and X is at least one selected from the group consisting of a single bond, -NHCO-, -CONH-, -COO- and -OCO-.

[0020] In formula (2), X 2 is a tetravalent group having an alicyclic structure or an aromatic ring, R 1 and R 2 are each independently hydrogen, an alkyl group having 1 to 6 carbon atoms, or an alkylsilyl group having 3 to 9 carbon atoms, and X is at least one selected from the group consisting of a single bond, -NHCO-, -CONH-, -COO-, and -OCO-.

[0021] In formula (3), R 3 is at least one selected from the group consisting of an alkyl group having 1 to 30 carbon atoms, a phenyl group, an alkoxy group, an acryloyl group, a methacryloyl group, an acryloyloxyethyl group, and a methacryloyloxyethyl group, and n is 0 to 2.)

[0022] [2] The polymer composition according to [1] above, wherein the polymer (X) contains at least one selected from the group consisting of a repeating unit represented by the following general formula (1-2) and a repeating unit represented by the following general formula (2-2).

[0023]

[0024] (In formula (1-2), X 1 is a tetravalent group having an alicyclic structure or an aromatic ring, and X is at least one selected from the group consisting of a single bond, -NHCO-, -CONH-, -COO-, and -OCO-. In formula (2-2), X 2 is a tetravalent group having an alicyclic structure or an aromatic ring, R 1 and R 2 are each independently hydrogen, an alkyl group having 1 to 6 carbon atoms, or an alkylsilyl group having 3 to 9 carbon atoms, and X is at least one selected from the group consisting of a single bond, -NHCO-, -CONH-, -COO-, and -OCO-.)

[0025] [3] The polymer composition according to [1] above, wherein X in the aforementioned formula (1) and the aforementioned formula (2) is a single bond.

[0026] [4] The polymer composition according to any one of [1] to [3] above, wherein the polymer (X) contains at least one selected from the group consisting of a repeating unit represented by the following general formula (1-2-1) and a repeating unit represented by the following general formula (2-2-1).

[0027]

[0028] (In formula (1-2-1), X 1 is a tetravalent group having an alicyclic structure or an aromatic ring. In formula (2-2-1), X 2is a tetravalent group having an alicyclic structure or an aromatic ring, R 1 and R 2 are each independently hydrogen, an alkyl group having 1 to 6 carbon atoms, or an alkylsilyl group having 3 to 9 carbon atoms.)

[0029] [5] The polymer composition according to any one of the foregoing [1] to [4], wherein the repeating unit represented by the foregoing formula (1) is 10 mol% or more with respect to all the repeating units of the foregoing polymer (X).

[0030] [6] The polymer composition according to any one of the foregoing [1] to [5], wherein the repeating unit represented by the foregoing formula (2) is 10 mol% or more with respect to all the repeating units of the foregoing polymer (X).

[0031] [7] The polymer composition according to any one of the foregoing [1] to [6], wherein the content of the compound (Y) is 10 ppm or more and 10000 ppm or less with respect to the polymer (X).

[0032] [8] A varnish obtained by dissolving the polymer composition according to any one of the foregoing [1] to [7] in an organic solvent.

[0033] [9] A polyimide film obtained by coating the varnish according to the foregoing [8] on a support and heating it.

[0034]

[10] A method for producing a polyimide film, wherein the varnish according to the foregoing [8] is coated on a support and heated.

[0035] Effects of the Invention

[0036] According to the present invention, there can be provided: a polymer composition having excellent heat resistance, little change in hue after heat treatment, and further capable of obtaining a polyimide film having a low yellowness; a varnish containing the composition; and a polyimide film having excellent heat resistance, little change in hue after heat treatment, and a low yellowness. Detailed Description

[0037] [Polymer Composition]

[0038] The polymer composition of the present invention contains a polymer (X) and a compound (Y) represented by the following general formula (3), and the polymer (X) contains at least one selected from the group consisting of a repeating unit represented by the following general formula (1) and a repeating unit represented by the following general formula (2).

[0039]

[0040] (In formula (1), X 1is a tetravalent group having an alicyclic structure or an aromatic ring, and X is at least one selected from the group consisting of a single bond, -NHCO-, -CONH-, -COO- and -OCO-.

[0041] In formula (2), X 2 is a tetravalent group having an alicyclic structure or an aromatic ring, and R 1 and R 2 are each independently hydrogen, an alkyl group having 1 to 6 carbon atoms, or an alkylsilyl group having 3 to 9 carbon atoms, and X is at least one selected from the group consisting of a single bond, -NHCO-, -CONH-, -COO- and -OCO-.

[0042] In formula (3), R 3 is at least one selected from the group consisting of an alkyl group having 1 to 30 carbon atoms, a phenyl group, an alkoxy group, an acryloyl group, a methacryloyl group, an acryloyloxyethyl group, and a methacryloyloxyethyl group, and n is 0 to 2.)

[0043] The polymer composition of the present invention is excellent as a raw material for polyimide films, and the obtained polyimide films have excellent heat resistance. The reason for the small hue change after heat treatment and the excellent property of having a low yellowness is not clear, but the following considerations can be made.

[0044] It is considered that: the polymer composition of the present invention contains a specific phosphorus compound, and the phosphorus compound coordinates to the ends of the polyimide obtained by imidizing the polymer or reacts with the ends of the polyimide, thereby being able to suppress side reactions or decomposition deterioration at the ends especially at high temperatures, and further being able to suppress the detachment of fluorine from the fluorinated diamine. It is considered that heat resistance and low yellowness can be achieved at the same time, and further, hue change can be suppressed even during heat treatment.

[0045] <Polymer (X)>

[0046] The polymer (X) contained in the polymer composition of the present invention contains at least one selected from the group consisting of a repeating unit represented by the following general formula (1) and a repeating unit represented by the following general formula (2).

[0047]

[0048] (In formula (1), X 1 is a tetravalent group having an alicyclic structure or an aromatic ring, and X is at least one selected from the group consisting of a single bond, -NHCO-, -CONH-, -COO- and -OCO-.

[0049] In formula (2), X 2 is a tetravalent group having an alicyclic structure or an aromatic ring, and R 1 and R2 are each independently hydrogen, an alkyl group having 1 to 6 carbon atoms, or an alkylsilyl group having 3 to 9 carbon atoms, and X is at least one selected from the group consisting of a single bond, -NHCO-, -CONH-, -COO-, and -OCO-.

[0050] From the viewpoint of heat resistance, X in the aforementioned formula (1) is preferably a single bond. Further, from the viewpoint of heat resistance, X in the aforementioned formula (2) is preferably a single bond. More preferably, X in the aforementioned formula (1) and the aforementioned formula (2) is a single bond.

[0051] That is, the polymer (X) contained in the polymer composition of the present invention preferably contains at least one selected from the group consisting of repeating units represented by the following general formula (1-1) and repeating units represented by the following general formula (2-1).

[0052]

[0053] (In formula (1-1), X 1 is a tetravalent group having an alicyclic structure or an aromatic ring.

[0054] In formula (2-1), X 2 is a tetravalent group having an alicyclic structure or an aromatic ring, and R 1 and R 2 are each independently hydrogen, an alkyl group having 1 to 6 carbon atoms, or an alkylsilyl group having 3 to 9 carbon atoms.)

[0055] The repeating unit represented by the aforementioned general formula (1) contained in the polymer (X) is preferably a repeating unit represented by the following general formula (1-2).

[0056]

[0057] (In formula (1-2), X 1 is a tetravalent group having an alicyclic structure or an aromatic ring, and X is at least one selected from the group consisting of a single bond, -NHCO-, -CONH-, -COO-, and -OCO-.

[0058] Examples of the repeating unit represented by the aforementioned formula (1-2) contained in the polymer (X) include repeating units represented by the following formulas (1-2-1) to (1-2-5). From the viewpoint of heat resistance, the repeating unit represented by formula (1-2-1) is preferred.

[0059] That is, in the aforementioned formula (1-2), X is at least one selected from the group consisting of a single bond, -NHCO-, -CONH-, -COO-, and -OCO-. From the viewpoint of heat resistance, X is preferably a single bond.

[0060]

[0061] (In formulas (1-2-1) to (1-2-5), X 1 is a tetravalent group having an alicyclic structure or an aromatic ring.)

[0062] The repeating unit represented by the above general formula (2) contained in the polymer (X) is preferably a repeating unit represented by the following general formula (2-2).

[0063]

[0064] (In formula (2-2), X 2 is a tetravalent group having an alicyclic structure or an aromatic ring, R 1 and R 2 are each independently hydrogen, an alkyl group having 1 to 6 carbon atoms, or an alkylsilyl group having 3 to 9 carbon atoms, and X is at least one selected from the group consisting of a single bond, -NHCO-, -CONH-, -COO-, and -OCO-.)

[0065] Examples of the repeating unit represented by the above formula (2-2) contained in the polymer (X) include repeating units represented by the following formulas (2-2-1) to (2-2-5). From the viewpoint of heat resistance, the repeating unit represented by formula (2-2-1) is preferred.

[0066] That is, in the above formula (2-2), X is at least one selected from the group consisting of a single bond, -NHCO-, -CONH-, -COO-, and -OCO-. From the viewpoint of heat resistance, X is preferably a single bond.

[0067]

[0068] (In formulas (2-2-1) to (2-2-5), X 2 is a tetravalent group having an alicyclic structure or an aromatic ring, R 1 and R 2 are each independently hydrogen, an alkyl group having 1 to 6 carbon atoms, or an alkylsilyl group having 3 to 9 carbon atoms.)

[0069] Based on the above, the polymer (X) contained in the polymer composition of the present invention preferably contains at least one selected from the group consisting of a repeating unit represented by the following general formula (1-2) and a repeating unit represented by the following general formula (2-2), and more preferably contains at least one selected from the group consisting of a repeating unit represented by the following general formula (1-2-1) and a repeating unit represented by the following general formula (2-2-1).

[0070]

[0071] (In formula (1-2), X 1is a tetravalent group having an alicyclic structure or an aromatic ring, and X is at least one selected from the group consisting of a single bond, -NHCO-, -CONH-, -COO-, and -OCO-. In formula (2-2), X 2 is a tetravalent group having an alicyclic structure or an aromatic ring, and R 1 and R 2 are each independently hydrogen, an alkyl group having 1 to 6 carbon atoms, or an alkylsilyl group having 3 to 9 carbon atoms, and X is at least one selected from the group consisting of a single bond, -NHCO-, -CONH-, -COO-, and -OCO-. In formula (1-2-1), X 1 is a tetravalent group having an alicyclic structure or an aromatic ring. In formula (2-2-1), X 2 is a tetravalent group having an alicyclic structure or an aromatic ring, and R 1 and R 2 are each independently hydrogen, an alkyl group having 1 to 6 carbon atoms, or an alkylsilyl group having 3 to 9 carbon atoms.)

[0072] The polymer (X) contains at least one selected from the group consisting of the repeating unit represented by the aforementioned general formula (1) and the repeating unit represented by the aforementioned general formula (2), and may contain only the repeating unit represented by the aforementioned general formula (1) or the repeating unit represented by the aforementioned general formula (2), or may contain both.

[0073] That is, the polymer composition of the present invention may be a polyimide composition containing a polyimide containing a repeating unit represented by the following general formula (1) and a compound (Y) represented by the following general formula (3),

[0074]

[0075] (In formula (1), X 1 is a tetravalent group having an alicyclic structure or an aromatic ring, and X is at least one selected from the group consisting of a single bond, -NHCO-, -CONH-, -COO-, and -OCO-. In formula (3), R 3 is at least one selected from the group consisting of an alkyl group having 1 to 30 carbon atoms, a phenyl group, an alkoxy group, an acryloyl group, a methacryloyl group, acryloyloxyethyl, and methacryloyloxyethyl, and n is 0 to 2.)

[0076] It may also be a polyamic acid composition containing a polyamic acid containing a repeating unit represented by the following general formula (2) and a compound (Y) represented by the following general formula (3).

[0077]

[0078] (In formula (2), X 2 is a tetravalent group having an alicyclic structure or an aromatic ring, and R1 and R 2 are each independently hydrogen, an alkyl group having 1 to 6 carbon atoms, or an alkylsilyl group having 3 to 9 carbon atoms, and X is at least 1 selected from the group consisting of a single bond, -NHCO-, -CONH-, -COO-, and -OCO-. In formula (3), R 3 is at least 1 selected from the group consisting of an alkyl group having 1 to 30 carbon atoms, a phenyl group, an alkoxy group, an acryloyl group, a methacryloyl group, an acryloyloxyethyl group, and a methacryloyloxyethyl group, and n is 0 to 2.)

[0079] The polymer (X) preferably contains the repeating unit represented by the aforementioned general formula (1), and more preferably contains both the repeating unit represented by the aforementioned general formula (1) and the repeating unit represented by the aforementioned general formula (2).

[0080] In the aforementioned formula (1), X 1 is a tetravalent group having an alicyclic structure or an aromatic ring. X 1 is preferably obtained by removing 2 dicarboxylic anhydride moieties (4 carboxyl moieties) from a tetracarboxylic dianhydride which is a raw material for the structural unit A derived from a tetracarboxylic dianhydride described later.

[0081] Similarly, in formula (1-1), formula (1-2), formula (1-2-1), formula (1-2-2), formula (1-2-3), formula (1-2-4), and formula (1-2-5), X 1 are each a tetravalent group having an alicyclic structure or an aromatic ring. X 1 is preferably obtained by removing 2 dicarboxylic anhydride moieties (4 carboxyl moieties) from a tetracarboxylic dianhydride which is a raw material for the structural unit A derived from a tetracarboxylic dianhydride described later.

[0082] In the aforementioned formula (2), X 2 is a tetravalent group having an alicyclic structure or an aromatic ring. X 2 is preferably obtained by removing 2 dicarboxylic anhydride moieties (4 carboxyl moieties) from a tetracarboxylic dianhydride which is a raw material for the structural unit A derived from a tetracarboxylic dianhydride described later.

[0083] In the aforementioned formula (2), R 1 and R 2 are each independently hydrogen, an alkyl group having 1 to 6 carbon atoms, or an alkylsilyl group having 3 to 9 carbon atoms, and are preferably hydrogen.

[0084] Similarly, in formula (2-1), formula (2-2), formula (2-2-1), formula (2-2-2), formula (2-2-3), formula (2-2-4), and formula (2-2-5), X 1 are each a tetravalent group having an alicyclic structure or an aromatic ring. X 1Preferably, it is obtained by removing two dicarboxylic anhydride moieties (four carboxyl moieties) from a tetracarboxylic dianhydride which is a raw material for a structural unit A derived from a tetracarboxylic dianhydride described later.

[0085] (Constitution of polymer (X))

[0086] As described above, polymer (X) contains at least one selected from the group consisting of the repeating unit represented by the aforementioned general formula (1) and the repeating unit represented by the aforementioned general formula (2). It may contain only either the repeating unit represented by the aforementioned general formula (1) or the repeating unit represented by the aforementioned general formula (2), or may contain both. In particular, from the viewpoints of reducing yellowness and improving transparency, the repeating unit represented by the aforementioned formula (1) is preferably 10 mol% or more, more preferably 30 mol% or more, further preferably 50 mol% or more, still more preferably 70 mol% or more, still more preferably 90 mol% or more, and 100 mol% or less with respect to all the repeating units of the aforementioned polymer (X).

[0087] In addition, from the viewpoints of maintaining low yellowness and improving heat resistance, the repeating unit represented by the aforementioned formula (2) is preferably 10 mol% or more, more preferably 30 mol% or more, further preferably 50 mol% or more, still more preferably 70 mol% or more, still more preferably 90 mol% or more, and 100 mol% or less with respect to all the repeating units of the aforementioned polymer (X).

[0088] In addition, when both the repeating unit represented by the aforementioned general formula (1) and the repeating unit represented by the aforementioned general formula (2) are included, the molar ratio [(1) / (2)] of the repeating unit represented by the aforementioned general formula (1) to the repeating unit represented by the aforementioned general formula (2) is preferably 10 / 90 to 70 / 30, more preferably 20 / 80 to 60 / 40, and further preferably 25 / 75 to 55 / 45.

[0089] <Each structural unit of polymer (X)>

[0090] Polymer (X) contains at least one selected from the group consisting of the repeating unit represented by the aforementioned general formula (1) and the repeating unit represented by the aforementioned general formula (2). The structural units constituting the polymer will be described below.

[0091] Polymer (X) has a structural unit A derived from a tetracarboxylic dianhydride and a structural unit B derived from a diamine.

[0092] It should be noted that in the repeating unit represented by the aforementioned general formula (1), the structural unit A and the structural unit B form an imide structure, and in the repeating unit represented by the aforementioned general formula (2), the structural unit A and the structural unit B form an amic acid structure. The structural units derived from the tetracarboxylic dianhydride are collectively referred to as the structural unit A, and the structural units derived from the diamine are collectively referred to as the structural unit B.

[0093] (Structural unit A)

[0094] The structural unit A is a structural unit derived from a tetracarboxylic dianhydride and is at least one selected from the group consisting of a structural unit derived from an alicyclic tetracarboxylic dianhydride and a structural unit derived from an aromatic tetracarboxylic dianhydride. From the viewpoints of low yellowness and transparency, a structural unit derived from an alicyclic tetracarboxylic dianhydride is preferred, and from the viewpoint of heat resistance, a structural unit derived from an aromatic tetracarboxylic dianhydride is preferred.

[0095] Examples of the alicyclic tetracarboxylic dianhydride that provides the structural unit derived from an alicyclic tetracarboxylic dianhydride include 1,2,4,5-cyclohexanetetracarboxylic dianhydride, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, norbornane-2-spiro-α-cyclopentanone-α'-spiro-2''-norbornane-5,5'',6,6''-tetracarboxylic dianhydride, bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxylic dianhydride, dicyclohexyltetracarboxylic dianhydride, 5,5'-(1,4-phenylene)-bis[hexahydro-4,7-methanoisobenzofuran-1,3-dione], 5,5'-bis-2-norbornene-5,5',6,6'-tetracarboxylic-5,5',6,6'-dianhydride, or their positional isomers, etc.

[0096] Among these, from the viewpoints of low yellowness and transparency, a compound represented by the following formula (a1) is preferred, and the structural unit A preferably contains the structural unit (A1) derived from the compound represented by the formula (a1).

[0097]

[0098] The compound represented by the formula (a1) is norbornane-2-spiro-α-cyclopentanone-α'-spiro-2''-norbornane-5,5'',6,6''-tetracarboxylic dianhydride.

[0099] Examples of the aromatic tetracarboxylic dianhydride that provides the structural unit derived from an aromatic tetracarboxylic dianhydride include biphenyltetracarboxylic dianhydride (BPDA), 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride (BPAF), pyromellitic dianhydride, 3,3',4,4'-(hexafluoroisopropylidene)diphthalic anhydride, 3,3',4,4'-diphenylsulfonetetracarboxylic dianhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride, 2,2',3,3'-benzophenonetetracarboxylic dianhydride, etc.

[0100] Among these, from the viewpoint of achieving both heat resistance and low yellowness, at least one selected from the group consisting of the compound represented by the following formula (a2) and the compound represented by the following formula (a3) is preferred, and the compound represented by the following formula (a2) is more preferred.

[0101] That is, the structural unit A preferably contains at least one selected from the group consisting of the structural unit (A2) derived from the compound represented by the following formula (a2) and the structural unit (A3) derived from the compound represented by the following formula (a3), and more preferably contains the structural unit (A2) derived from the compound represented by the following formula (a2).

[0102]

[0103] The compound represented by the formula (a2) is biphenyltetracarboxylic dianhydride (BPDA). Specific examples thereof include 3,3',4,4'-biphenyltetracarboxylic dianhydride (s-BPDA) represented by the following formula (a2s), 2,3,3',4'-biphenyltetracarboxylic dianhydride (a-BPDA) represented by the following formula (a2a), and 2,2',3,3'-biphenyltetracarboxylic dianhydride (i-BPDA) represented by the following formula (a2i). Among them, 3,3',4,4'-biphenyltetracarboxylic dianhydride (s-BPDA) represented by the following formula (a2s) is preferred.

[0104]

[0105] The compound represented by the formula (a3) is 9,9'-bis(3,4-dicarboxyphenyl)fluorene dianhydride (BPAF).

[0106] When the polymer (X) contained in the polymer composition of the present invention contains both the repeating unit represented by the aforementioned general formula (1) and the repeating unit represented by the aforementioned general formula (2), it is preferred that: the repeating unit (polyimide unit) represented by the aforementioned general formula (1) contains at least one selected from the group consisting of the structural unit (A1) and the structural unit (A3), and the repeating unit (polyamic acid unit) represented by the aforementioned general formula (2) contains the structural unit (A2).

[0107] The structural unit A may contain a structural unit other than an aromatic tetracarboxylic dianhydride and an alicyclic tetracarboxylic dianhydride. The tetracarboxylic dianhydride providing such a structural unit is not particularly limited, and examples thereof include aliphatic tetracarboxylic dianhydrides such as 1,2,3,4-butane tetracarboxylic dianhydride.

[0108] The structural unit optionally contained in the structural unit A may be one kind or two or more kinds.

[0109] It should be noted that in this specification, an aromatic tetracarboxylic dianhydride refers to a tetracarboxylic dianhydride containing one or more aromatic rings, an alicyclic tetracarboxylic dianhydride refers to a tetracarboxylic dianhydride containing one or more alicyclic rings and no aromatic rings, and an aliphatic tetracarboxylic dianhydride refers to a tetracarboxylic dianhydride containing neither aromatic rings nor alicyclic rings.

[0110] (Structural unit B)

[0111] Structural unit B is a structural unit derived from a diamine and contains a structural unit (B1) derived from a compound represented by formula (b1).

[0112] Since structural unit B contains structural unit (B1), it has excellent heat resistance. In particular, when combined with compound (Y), it has an excellent effect of reducing yellowness.

[0113] The ratio of structural unit (B1) in structural unit B is preferably 45 mol% or more, more preferably 70 mol% or more, still more preferably 90 mol% or more, and particularly preferably 99 mol% or more. The upper limit of the ratio is not particularly limited and is 100 mol% or less.

[0114]

[0115] (In formula (b1), X is at least one selected from the group consisting of a single bond, -NHCO-, -CONH-, -COO-, and -OCO-.)

[0116] Structural unit (B1) preferably contains a structural unit (B11) derived from a compound represented by the following formula (b11).

[0117]

[0118] In addition, structural unit (B1) preferably contains a structural unit (B12) derived from a compound represented by the following formula (b12).

[0119]

[0120] (In formula (1), X is at least one selected from the group consisting of a single bond, -NHCO-, -CONH-, -COO-, and -OCO-.)

[0121] The structural unit (B12) contains at least one selected from the group consisting of a structural unit (B121) derived from a compound represented by the following formula (b121), a structural unit (B122) derived from a compound represented by the following formula (b122), and a structural unit (B123) derived from a compound represented by the following formula (b123). From the viewpoint of heat resistance, it preferably contains the structural unit (B121) derived from the compound represented by the following formula (b121), and more preferably is the structural unit (B121) derived from the compound represented by the following formula (b121).

[0122]

[0123] The compound represented by the formula (b121) is 2,2'-bis(trifluoromethyl)benzidine (TFMB).

[0124] Since the structural unit B contains the structural unit (B1), it has excellent heat resistance. Especially when combined with the compound (Y), it has an excellent effect of reducing yellowness.

[0125] The structural unit B may contain structural units other than the structural unit (B1). The diamine for providing such a structural unit is not particularly limited, and examples thereof include aromatic diamines such as 3,5-diaminobenzoic acid (3,5-DABA), 9,9-bis(4-aminophenyl)fluorene (BAFL), 4-aminophenyl-4-aminobenzoate (4-BAAB), 1,4-phenylenediamine, p-xylylenediamine, 1,5-diaminonaphthalene, 2,2'-dimethylbiphenyl-4,4'-diamine, 2,2'-dimethylbiphenyl-4,4'-diamine, 4,4'-diaminodiphenylmethane, 1,4-bis[2-(4-aminophenyl)-2-propyl]benzene, 2,2-bis(4-aminophenyl)hexafluoropropane, 4,4'-diaminobenzanilide, 1-(4-aminophenyl)-2,3-dihydro-1,3,3-trimethyl-1H-inden-5-amine, α,α'-bis(4-aminophenyl)-1,4-diisopropylbenzene, N,N'-bis(4-aminophenyl)terephthalamide, 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane, and 1,4-bis(4-aminophenoxy)benzene; alicyclic diamines such as 1,3-bis(aminomethyl)cyclohexane and 1,4-bis(aminomethyl)cyclohexane; and aliphatic diamines such as ethylenediamine and hexamethylenediamine.

[0126] Among these, at least one selected from the group consisting of a compound represented by the following formula (b21), a compound represented by the following formula (b22), and a compound represented by the following formula (b3) is preferred, and from the viewpoints of improving low yellowness, transparency, and heat resistance, a compound represented by the following formula (b21) is more preferred.

[0127] That is, the structural unit B preferably contains at least one selected from the group consisting of the structural unit (B2) and the structural unit (B3). The structural unit (B2) is at least one selected from the group consisting of the structural unit (B21) derived from the compound represented by the following formula (b21) and the structural unit (B22) derived from the compound represented by the following formula (b22). The structural unit (B3) is derived from the compound represented by the following formula (b3). More preferably, it contains the structural unit (B2) which is at least one selected from the group consisting of the structural unit (B21) derived from the compound represented by the following formula (b21) and the structural unit (B22) derived from the compound represented by the following formula (b22). Even more preferably, it contains the structural unit (B21) derived from the compound represented by the following formula (b21).

[0128]

[0129] The compound represented by the formula (b21) is 3,5-diaminobenzoic acid (3,5-DABA).

[0130] The compound represented by the formula (b22) is 9,9-bis(4-aminophenyl)fluorene (BAFL).

[0131] When the structural unit B contains the structural unit (B2), the molar ratio [(B1) / (B2)] of the structural unit (B1) to the structural unit (B2) is preferably 20 / 80 to 95 / 5, more preferably 50 / 50 to 90 / 10, and even more preferably 70 / 30 to 90 / 10.

[0132]

[0133] The compound represented by the formula (b3) is 4-aminophenyl-4-aminobenzoate (4-BAAB).

[0134] It should be noted that in this specification, an aromatic diamine refers to a diamine containing one or more aromatic rings, an alicyclic diamine refers to a diamine containing one or more alicyclic rings and no aromatic rings, and an aliphatic diamine refers to a diamine containing neither an aromatic ring nor an alicyclic ring.

[0135] The structural unit optionally contained in the structural unit B can be one kind or two or more kinds.

[0136] (Method for manufacturing the polymer (X))

[0137] The polymer (X) can be manufactured by any method, but the following method is preferred.

[0138] As described above, the polymer (X) contains either or both of the repeating units represented by the aforementioned general formula (1) (i.e., imide moiety) and the repeating units represented by the aforementioned general formula (2) (i.e., amic acid moiety), and they can be adjusted by changing the manufacturing method.

[0139] Specifically, in the manufacturing method when both the repeating units represented by formula (1) and the repeating units represented by formula (2) are included (manufacturing method of imide-amic acid copolymer), by only using the process for manufacturing the part mainly containing the repeating units represented by formula (1) (polyimide part), a polymer (X) (polyimide) substantially formed of the repeating units represented by formula (1) can be obtained, and by only using the process for manufacturing the part mainly containing the repeating units represented by formula (2) (polyamic acid part), a polymer (X) (polyamic acid) substantially formed of the repeating units represented by formula (2) can be obtained.

[0140] The polymer (X) containing both the repeating units represented by formula (1) and the repeating units represented by formula (2) (hereinafter also referred to as imide-amic acid copolymer) is preferably based on a method having the following step 1 and step 2.

[0141] Step 1: A step of reacting a tetracarboxylic acid component constituting the imide moiety with a diamine component to obtain an imide oligomer

[0142] Step 2: A step of reacting the imide oligomer obtained in step 1 with a tetracarboxylic acid component and a diamine component constituting the amic acid moiety to obtain an imide-amic acid copolymer

[0143] It should be noted that by reacting all the tetracarboxylic acid components with the diamine component in step 1, a polymer (X) (polyimide) substantially formed of the repeating units represented by formula (1) can be obtained. Specifically, in the manufacturing method of the polymer (X) (polyimide) substantially formed of the repeating units represented by formula (1), the aforementioned step 1 can be understood as "a step of reacting a tetracarboxylic acid component constituting the polyimide with a diamine component to obtain a polyimide".

[0144] In addition, by not performing step 1 and reacting all the tetracarboxylic acid components with the diamine component in step 2, a polymer (X) (polyamic acid) substantially formed of the repeating units represented by formula (2) can be obtained. Specifically, in the manufacturing method of the polymer (X) (polyamic acid) substantially formed of the repeating units represented by formula (2), the aforementioned step 2 can be understood as "a step of reacting a tetracarboxylic acid component constituting the polyamic acid with a diamine component to obtain a polyamic acid".

[0145] 〔Step 1〕

[0146] Step 1 is a step of reacting a tetracarboxylic acid component constituting the imide moiety with a diamine component to obtain an imide oligomer.

[0147] As the tetracarboxylic acid component used in Step 1, a compound providing structural unit (A1) is preferably included, and preferably all of its amount is used in Step 1. A tetracarboxylic acid component other than the compound providing structural unit (A1) may also be included. As the tetracarboxylic acid component other than the compound providing structural unit (A1), a compound providing structural unit (A2) or a compound providing structural unit (A3) is preferred, and a compound providing structural unit (A3) is more preferred.

[0148] As the diamine component used in Step 1, a compound providing structural unit (B1) is preferably included. Within the range not impairing the effects of the present invention, a diamine component other than the compound providing structural unit (B1) may also be included. As the tetracarboxylic acid component other than the compound providing structural unit (B1), a compound providing structural unit (B2) or a compound providing structural unit (B3) is preferred.

[0149] In Step 1, relative to the tetracarboxylic acid component, the diamine component is preferably 1.01 to 2 moles, more preferably 1.05 to 1.9 moles, and still more preferably 1.1 to 1.7 moles.

[0150] It should be noted that in the case of obtaining a polymer (X) (polyimide) substantially formed of the repeating unit represented by formula (1), relative to the tetracarboxylic acid component, the diamine component is preferably 0.9 to 1.1 moles.

[0151] In Step 1, the method for reacting the tetracarboxylic acid component with the diamine component to obtain the imide oligomer is not particularly limited, and a known method can be used.

[0152] As specific reaction methods, the following methods can be cited: (1) A method of charging the tetracarboxylic acid component, the diamine component, and a reaction solvent into a reactor, stirring at 10 to 110 °C for 0.5 to 30 hours, and then raising the temperature to carry out an imidization reaction; (2) A method of charging the diamine component and the reaction solvent into a reactor to dissolve them, then charging the tetracarboxylic acid component, and stirring at 10 to 110 °C for 0.5 to 30 hours as needed, and then raising the temperature to carry out an imidization reaction; (3) A method of charging the tetracarboxylic acid component, the diamine component, and the reaction solvent into a reactor and immediately raising the temperature to carry out an imidization reaction, etc.

[0153] In the imidization reaction, it is preferable to use a Dean-Stark apparatus or the like to carry out the reaction while removing the water generated during production. By carrying out such an operation, the degree of polymerization and the imidization rate can be further improved.

[0154] In the above imidization reaction, known imidization catalysts can be used. Examples of the imidization catalyst include a base catalyst or an acid catalyst.

[0155] Examples of the base catalyst include organic base catalysts such as pyridine, quinoline, isoquinoline, α-methylpyridine, β-methylpyridine, 2,4-dimethylpyridine, 2,6-dimethylpyridine, trimethylamine, triethylamine, 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.

[0156] In addition, examples of the acid catalyst include crotonic acid, acrylic acid, trans-3-hexenoic acid, cinnamic acid, benzoic acid, methylbenzoic acid, hydroxybenzoic acid, terephthalic acid, benzenesulfonic acid, p-toluenesulfonic acid, naphthalenesulfonic acid, etc. The above imidization catalyst can be used alone or in combination of two or more.

[0157] Among the above, from the viewpoint of processability, a base catalyst is preferred, an organic base catalyst is more preferred, one or more selected from triethylamine and triethylenediamine are further preferred, and triethylamine is even more preferred.

[0158] From the viewpoints of reaction rate and suppression of gelation, etc., the temperature of the imidization reaction is preferably 120 to 250 °C, more preferably 160 to 200 °C. In addition, the reaction time is preferably 0.5 to 10 hours after the start of distillation of the generated water.

[0159] The imide oligomer obtained in Step 1 preferably has an imide repeating structural unit formed from a compound providing a structural unit (A1) and a compound providing a structural unit (B1).

[0160] By the above method, a solution containing an imide oligomer dissolved in a solvent can be obtained. In the solution containing the imide oligomer obtained in Step 1, within the range not impairing the effects of the present invention, at least a part of the components used as the tetracarboxylic acid component and the diamine component in Step 1 can also be contained as unreacted monomers.

[0161] 〔Step 2〕

[0162] Step 2 in the production method of the present invention is a step of reacting the imide oligomer obtained in Step 1 with a tetracarboxylic acid component and a diamine component constituting the amic acid part to obtain an imide-amic acid copolymer.

[0163] As the tetracarboxylic acid component used in Step 2, a compound providing structural unit (A1) is preferably included, and a tetracarboxylic acid component other than the compound providing structural unit (A1) may also be included. As the tetracarboxylic acid component other than the compound providing structural unit (A1), a compound providing structural unit (A2) or a compound providing structural unit (A3) is preferred.

[0164] When the production method of the present invention includes both Step 1 and Step 2, as the tetracarboxylic acid component used in Step 2, a compound providing structural unit (A2) is preferred.

[0165] As the diamine component used in Step 2, a compound providing structural unit (B1) is preferably included, and a diamine component other than the compound providing structural unit (B1) may also be included within the range not impairing the effects of the present invention. As the tetracarboxylic acid component other than the compound providing structural unit (B1), a compound providing structural unit (B2) or a compound providing structural unit (B3) is preferred.

[0166] When the production method of the present invention has both Step 1 and Step 2, as the diamine component used in Step 2, a compound providing structural unit (B3) is preferred.

[0167] It should be noted that when a polymer (X) (polyamic acid) substantially formed of the repeating unit represented by formula (2) is obtained by only performing Step 2, the diamine component is preferably 0.9 to 1.1 moles relative to the tetracarboxylic acid component.

[0168] The method of reacting the tetracarboxylic acid component and the diamine component with the imide oligomer obtained in Step 1 in Step 2 is not particularly limited, and a known method can be used.

[0169] As specific reaction methods, the following methods can be cited: (1) A method of charging the imide oligomer obtained in Step 1, the tetracarboxylic acid component, the diamine component, and a solvent into a reactor and stirring for 1 to 72 hours within the range of 0 to 120°C, preferably 5 to 80°C; (2) A method of charging the imide oligomer obtained in Step 1 and a solvent into a reactor to dissolve it, and then charging the tetracarboxylic acid component and the diamine component and stirring for 1 to 72 hours within the range of 0 to 120°C, preferably 5 to 80°C, etc.

[0170] When reacting at 80°C or lower, the molecular weight of the copolymer obtained in Step 2 does not vary depending on the temperature profile during polymerization, and the progress of thermal imidization can also be suppressed, so that the copolymer can be stably produced.

[0171] By using the above method, a copolymer solution containing an imide-amido acid copolymer dissolved in a solvent can be obtained. In addition, a polyimide solution containing polyimide can be obtained only by performing Step 1, and a polyamic acid solution containing polyamic acid can be obtained only by performing Step 2.

[0172] The concentration of the copolymer in the obtained solution is usually in the range of 1 to 50% by mass, preferably 3 to 35% by mass, and more preferably 5 to 30% by mass.

[0173] In addition, the concentration of the polyimide in the obtained solution is usually in the range of 1 to 50% by mass, preferably 3 to 35% by mass, and more preferably 5 to 30% by mass.

[0174] Furthermore, the concentration of the polyamic acid in the obtained solution is usually in the range of 1 to 50% by mass, preferably 3 to 35% by mass, and more preferably 5 to 30% by mass.

[0175] From the viewpoint of the mechanical strength of the obtained polyimide film, the number average molecular weight of the imide-amido acid copolymer obtained in the above manufacturing method is preferably 5,000 to 500,000. In addition, from the same viewpoint, the weight average molecular weight (Mw) is preferably 10,000 to 800,000, and more preferably 100,000 to 300,000. It should be noted that the number average molecular weight and the weight average molecular weight of this copolymer can be obtained, for example, by the conversion value of standard polymethyl methacrylate (PMMA) measured by gel filtration chromatography.

[0176] From the viewpoint of the mechanical strength of the obtained polyimide film, the number average molecular weight of the polyimide obtained in the above manufacturing method is preferably 5,000 to 500,000. In addition, from the same viewpoint, the weight average molecular weight (Mw) is preferably 10,000 to 800,000, and more preferably 100,000 to 300,000.

[0177] From the viewpoint of the mechanical strength of the obtained polyimide film, the number average molecular weight of the polyamic acid obtained in the above manufacturing method is preferably 5,000 to 500,000. In addition, from the same viewpoint, the weight average molecular weight (Mw) is preferably 10,000 to 800,000, and more preferably 100,000 to 300,000.

[0178] The raw materials and the like used in this manufacturing method will be described below.

[0179] 〔Tetracarboxylic acid component〕

[0180] Regarding the tetracarboxylic acid component used as a raw material in this manufacturing method, as the compound providing the structural unit (A1), the compound represented by the formula (a1) can be cited, but it is not limited thereto, and within the range of providing the same structural unit, it can be its derivative. As such a derivative, the tetracarboxylic acid corresponding to the compound represented by the formula (a1) and the alkyl ester of this tetracarboxylic acid can be cited. As the compound providing the structural unit (A1), the compound represented by the formula (a1) is preferred.

[0181] Similarly, as the compound providing the structural unit (A2), the compound represented by the formula (a2) can be cited, but it is not limited thereto, and within the range of providing the same structural unit, it can be its derivative. As such a derivative, the tetracarboxylic acid corresponding to the compound represented by the formula (a2) and the alkyl ester of this tetracarboxylic acid can be cited. As the compound providing the structural unit (A2), the compound represented by the formula (a2) is preferred.

[0182] Furthermore, as the compound providing the structural unit (A3), the compound represented by the formula (a3) can be cited, but it is not limited thereto, and within the range of providing the same structural unit, it can be its derivative. As such a derivative, the tetracarboxylic acid corresponding to the compound represented by the formula (a3) and the alkyl ester of this tetracarboxylic acid can be cited. As the compound providing the structural unit (A3), the compound represented by the formula (a3) is preferred.

[0183] 〔Diamine component〕

[0184] Regarding the diamine component used as a raw material in this manufacturing method, as the compound providing the structural unit (B1), diamine can be cited, but it is not limited thereto, and within the range of providing the same structural unit, it can be its derivative. As such a derivative, the diisocyanate corresponding to the diamine can be cited. As the compound providing the structural unit (B1), diamine is preferred.

[0185] Similarly, as the compound providing the structural unit (B2), diamine can be cited, but it is not limited thereto, and within the range of providing the same structural unit, it can be its derivative. As such a derivative, the diisocyanate corresponding to the diamine can be cited. As the compound providing the structural unit (B2), diamine is preferred.

[0186] Furthermore, as the compound providing the structural unit (B3), diamine can be cited, but it is not limited thereto, and within the range of providing the same structural unit, it can be its derivative. As such a derivative, the diisocyanate corresponding to the diamine can be cited. As the compound providing the structural unit (B3), diamine is preferred.

[0187] In the present invention, for the input ratio of the tetracarboxylic acid component to the diamine component used in all steps of copolymer production including Step 1 and Step 2, relative to 1 mole of the tetracarboxylic acid component, the diamine component is preferably 0.9 to 1.1 moles.

[0188] 〔End-capping agent〕

[0189] In addition, in the production of polymer (X), an end-capping agent can be used in addition to the aforementioned tetracarboxylic acid component and diamine component. When performing the two steps of Step 1 and Step 2, it is preferable to use the end-capping agent in Step 2.

[0190] As the end-capping agent, monoamines or dicarboxylic acids are preferred. Relative to 1 mole of the tetracarboxylic acid component, the input amount of the introduced end-capping agent is preferably 0.0001 to 0.1 mole, and particularly preferably 0.001 to 0.06 mole. As the monoamine end-capping agent, for example, methylamine, ethylamine, propylamine, butylamine, benzylamine, 4-methylbenzylamine, 4-ethylbenzylamine, 4-dodecylbenzylamine, 3-methylbenzylamine, 3-ethylbenzylamine, aniline, 3-methylaniline, 4-methylaniline, etc. can be recommended. Among them, benzylamine and aniline can be suitably used. As the dicarboxylic acid end-capping agent, dicarboxylic acids are preferred, and a part of them can be made to form a ring. For example, phthalic acid, phthalic anhydride, 4-chlorophthalic acid, tetrafluorophthalic acid, 2,3-benzophenonedicarboxylic acid, 3,4-benzophenonedicarboxylic acid, cyclopentane-1,2-dicarboxylic acid, 4-cyclohexene-1,2-dicarboxylic acid, etc. can be recommended. Among them, phthalic acid and phthalic anhydride can be suitably used.

[0191] 〔Solvent〕

[0192] In the production method of polymer (X), the solvent used only needs to be able to dissolve the generated imide-amidic acid copolymer. For example, aprotic solvents, phenolic solvents, ether solvents, carbonate solvents, etc. can be cited.

[0193] As specific examples of aprotic solvents, amide solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, N-methylcaprolactam, 1,3-dimethylimidazolidinone, tetramethylurea, etc. can be cited; lactone solvents such as γ-butyrolactone, γ-valerolactone, etc.; phosphorus-containing amide solvents such as hexamethylphosphoric triamide, hexamethylphosphonamide, etc.; sulfur-containing solvents such as dimethyl sulfone, dimethyl sulfoxide, sulfolane, etc.; ketone solvents such as acetone, methyl ethyl ketone, cyclohexanone, methylcyclohexanone, etc.; ester solvents such as propylene glycol methyl ether acetate, etc. can be cited.

[0194] As specific examples of phenolic solvents, 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. can be cited.

[0195] Specific examples of the ether 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, and the like.

[0196] Specific examples of the carbonate solvents include diethyl carbonate, methyl ethyl carbonate, ethylene carbonate, propylene carbonate, and the like.

[0197] Among the above reaction solvents, amide solvents or lactone solvents are preferred, amide solvents are more preferred, and N-methyl-2-pyrrolidone is even more preferred. The above reaction solvents can be used alone or in combination of two or more.

[0198] <Compound (Y)>

[0199] Compound (Y) contained in the polymer composition of the present invention is represented by the following general formula (3).

[0200]

[0201] (In formula (3), R 3 is at least one selected from the group consisting of an alkyl group having 1 to 30 carbon atoms, a phenyl group, an alkoxy group, an acryloyl group, a methacryloyl group, an acryloyloxyethyl group, and a methacryloyloxyethyl group, and n is 0 to 2.)

[0202] Due to the inclusion of compound (Y), a film having heat resistance and low yellowness can be obtained, and furthermore, the transparency of the film can also be improved.

[0203] In formula (3), R 3 is at least one selected from the group consisting of an alkyl group having 1 to 30 carbon atoms, a phenyl group, an alkoxy group, an acryloyl group, a methacryloyl group, an acryloyloxyethyl group, and a methacryloyloxyethyl group, and is preferably an alkyl group having 1 to 30 carbon atoms.

[0204] Multiple Rs 3 may be the same or different, and are preferably the same.

[0205] n is 0 to 2, and is preferably 1 to 2.

[0206] Compound (Y) is a phosphorus compound. Specific examples of compound (Y) include at least one selected from the group consisting of acidic phosphates and phosphoric acid, and acidic phosphates are preferred.

[0207] Examples of the acidic phosphate include isotridecyl acid phosphate, dibutyl phosphate, etc., and isotridecyl acid phosphate is preferred.

[0208] The content of compound (Y) is preferably 10 ppm or more and 10,000 ppm or less, more preferably 100 ppm or more and 5,000 ppm or less, and still more preferably 500 ppm or more and 2,000 ppm or less, relative to polymer (X). Since the amount of compound (Y) is in this range, a film having heat resistance and low yellowness can be obtained, and furthermore, the transparency of the film can also be improved. It should be noted that in this specification, "ppm" represents parts per million by mass.

[0209] [Varnish]

[0210] The varnish of the present invention is obtained by dissolving the above-mentioned polymer composition in an organic solvent. That is, the varnish of the present invention is obtained by dissolving polymer (X) and compound (Y) in an organic solvent. The varnish of the present invention contains polymer (X), compound (Y) and an organic solvent, and polymer (X) and compound (Y) are dissolved in this organic solvent.

[0211] The organic solvent only needs to dissolve polymer (X) and compound (Y), and there is no particular limitation. As the solvent used in the production of polymer (X), it is preferable to use the above-mentioned compounds alone or in combination of two or more.

[0212] The varnish of the present invention may be obtained by mixing and dissolving compound (Y) in the above-mentioned polymer (X) solution, or a dilution solvent may be further added.

[0213] When the polymer (X) contained in the varnish of the present invention contains a repeating unit (amic acid part) represented by formula (2), from the viewpoint of effectively imidizing the amic acid part, an imidization catalyst and a dehydration catalyst may be further contained. As the imidization catalyst, any imidization catalyst having a boiling point of 40°C or more and 180°C or less can be used, and amine compounds having a boiling point of preferably 180°C or less can be exemplified. If the imidization catalyst has a boiling point of 180°C or less, the film will be colored during drying at a high temperature after film formation, and there is a concern about damaging the appearance. On the other hand, if the imidization catalyst has a boiling point of 40°C or more, the possibility of volatilization before sufficient imidization can be avoided.

[0214] As the amine compound suitable for use as the imidization catalyst, pyridine or methylpyridine can be exemplified. The above-mentioned imidization catalyst can be used alone or in combination of two or more.

[0215] As the dehydration catalyst, acid anhydrides such as acetic anhydride, propionic anhydride, n-butyric anhydride, benzoic anhydride, trifluoroacetic anhydride, etc.; carbodiimide compounds such as dicyclohexylcarbodiimide, etc. can be exemplified. These can be used alone or in combination of two or more.

[0216] The polymer (X) contained in the varnish of the present invention has solvent solubility, and thus a high-concentration varnish can be prepared. The varnish of the present invention preferably contains 3 to 40% by mass of the polymer (X), more preferably 5 to 40% by mass, and still more preferably 10 to 30% by mass. The viscosity of the varnish is preferably 0.1 to 100 Pa·s, more preferably 0.1 to 20 Pa·s. The viscosity of the varnish is a value measured at 25 °C using an E-type viscometer.

[0217] In addition, the varnish of the present invention may contain various additives such as inorganic fillers, adhesion promoters, release agents, flame retardants, ultraviolet stabilizers, surfactants, leveling agents, defoaming agents, fluorescent brighteners, crosslinking agents, polymerization initiators, and photosensitizers within the range that does not impair the required properties of the polyimide film.

[0218] The method for producing the varnish of the present invention is not particularly limited, and known methods can be applied.

[0219] [Polyimide Film and Method for Producing Polyimide Film]

[0220] When the polymer (X) contains the repeating unit (amic acid moiety) represented by the formula (2), the polyimide film of the present invention contains: a polyimide resin obtained by imidizing the amic acid moiety of the polymer (X), and a compound (Y). In addition, when the polymer (X) is a polyimide, the polyimide film of the present invention contains the polyimide or a polyimide resin having an adjusted molecular weight by further heating; and a compound (Y). Therefore, the polyimide film of the present invention has excellent heat resistance and low yellowness.

[0221] The polyimide film of the present invention can be produced using the aforementioned varnish.

[0222] The method for producing a polyimide film using the varnish of the present invention is not particularly limited, and the following method is preferred.

[0223] That is, a method of coating the above-mentioned varnish on a support and heating is preferred. Specifically, a method of coating a varnish obtained by dissolving the polymer (X) and the compound (Y) in an organic solvent on a support and heating is preferred.

[0224] In addition, as the polyimide film of the present invention, a polyimide film obtained by coating the above-mentioned varnish on a support and heating is preferred. Specifically, a polyimide film obtained by coating a varnish obtained by dissolving the polymer (X) and the compound (Y) in an organic solvent on a support and heating is preferred.

[0225] Examples of the support include a smooth glass plate, a metal plate, and plastics.

[0226] After applying a varnish to a support or forming it into a film shape, organic solvents such as reaction solvents and diluting solvents contained in the varnish are removed by heating to obtain a polymer film. When the polymer contained in the polymer film has an amic acid part, it is imidized (dehydration cyclization) by heating, and then peeled off from the support, whereby a polyimide film can be manufactured.

[0227] From the viewpoint of the mechanical strength of the film, the weight-average molecular weight (Mw) of the polyimide resin contained in the polyimide film of the present invention is preferably 10,000 to 800,000, more preferably 30,000 to 500,000, further preferably 50,000 to 400,000, and still more preferably 100,000 to 300,000. It should be noted that the weight-average molecular weight of the copolymer can be determined, for example, by the conversion value of standard polymethyl methacrylate (PMMA) measured by gel filtration chromatography.

[0228] As the heating temperature when drying the varnish of the present invention to obtain a polymer film, it is preferably 50 to 150°C. As the heating temperature when imidizing the polymer by heating, it is preferably 200 to 500°C, more preferably 250 to 450°C, and further preferably 300 to 430°C. In addition, the heating time is usually 1 minute to 6 hours, preferably 5 minutes to 2 hours, and more preferably 15 minutes to 1 hour.

[0229] Examples of the heating atmosphere include air, nitrogen, oxygen, hydrogen, and nitrogen / hydrogen mixed gas. In order to suppress the coloring of the obtained polyimide resin, nitrogen with an oxygen concentration of 100 ppm or less or a nitrogen / hydrogen mixed gas with a hydrogen concentration of 0.5% or less is preferred.

[0230] It should be noted that the method of imidization is not limited to thermal imidization, and chemical imidization can also be applied.

[0231] The thickness of the polyimide film of the present invention can be appropriately selected according to the use and the like, and is preferably 1 to 250 μm, more preferably 5 to 100 μm, and further preferably 5 to 50 μm. By making the thickness 1 to 250 μm, practical use as a self-supporting film can be achieved.

[0232] The thickness of the polyimide film can be easily controlled by adjusting the solid content concentration and viscosity of the varnish.

[0233] By using the polymer composition of the present invention, a polyimide film having excellent heat resistance, little change in hue after heat treatment, and low yellowness can be obtained. The obtained polyimide film of the present invention has excellent heat resistance, little change in hue after heat treatment, and low yellowness. The suitable physical property values of the film are as follows.

[0234] When forming a film with a thickness of 10 μm, the total light transmittance is preferably 84% or more, more preferably 87% or more, and further preferably 90% or more.

[0235] When forming a film with a thickness of 10 μm, the yellowness index (YI) is preferably 16 or less, more preferably 12 or less, and from the viewpoint of excellent achromaticity, it is preferably 6 or less, more preferably 4 or less.

[0236] In addition, the 1% weight loss temperature is preferably 430 °C or more, more preferably 480 °C or more, further preferably 500 °C or more, and even more preferably 510 °C or more. Here, the 1% weight loss temperature is the temperature at which the polyimide film is heated at a heating rate of 10 °C / minute from 40 to 550 °C and the weight is reduced by 1% compared to the weight at 300 °C.

[0237] It should be noted that the above physical property values in the present invention can be specifically measured by the methods described in the examples.

[0238] The polyimide film of the present invention can be suitably used as a film for various components such as color filters, flexible displays, semiconductor components, and optical members. The polyimide film of the present invention is particularly suitable for use as a substrate for image display devices such as liquid crystal displays and OLED displays.

[0239] Examples

[0240] The present invention will be specifically described below by way of examples. However, the present invention is not limited by any of these examples.

[0241] The physical properties of the films obtained in the examples and comparative examples were measured by the methods shown below.

[0242] (1) Film thickness

[0243] The film thickness was measured using a micrometer manufactured by Mitutoyo Corporation.

[0244] It should be noted that the film thicknesses of Examples 9 to 10 and Comparative Examples 8 to 9 were measured using a film thickness meter Filmetrics F20 (manufactured by FILMETRICS).

[0245] (2) Total light transmittance, yellowness index (YI)

[0246] The total light transmittance was measured in accordance with JIS K7105:1981, and the YI was measured in accordance with ASTM D1925 (C light source, 2°) using a color / turbidity simultaneous measuring instrument "COH7700" manufactured by Nippon Denshoku Industries Co., Ltd.

[0247] (3) 1% weight loss temperature (Td1%)

[0248] Using the differential thermal - thermogravimetric simultaneous measurement device "NEXTA STA200RV" manufactured by Hitachi High - Tech Science Corporation. The sample was heated at a heating rate of 10 °C / minute to 40 - 150 °C, held at 150 °C for 30 minutes to remove moisture, and then heated to 550 °C. The temperature at which the weight decreased by 1% compared to the weight after holding at 150 °C for 30 minutes was defined as the 1% weight loss temperature. The larger the value of the weight loss temperature, the better.

[0249] (4) Laminated film evaluation

[0250] Imitating the manufacturing process of the display for an image display device, a laminated film was manufactured, heat - treated, and the hue change after heat - treatment was evaluated visually. The laminated film was fabricated as follows.

[0251] Without peeling the polyimide films obtained in the examples and comparative examples, a SiO2 film with a thickness of 300 nm was formed on the polyimide film by sputtering, and an ITO (indium tin oxide) film with a thickness of 1230 nm was formed thereon, followed by annealing (heating) for 1 hour. For the annealing (heating) temperature, Examples 1 - 8 and Comparative Examples 1 - 7 were carried out at 360 °C, and Examples 9 - 10 and Comparative Examples 8 - 9 were carried out at 400 °C.

[0252] The presence or absence of yellowing (increase in the color concentration of the yellow color system) of the laminated film before and after annealing was evaluated visually according to the following criteria.

[0253] None (no yellowing): No yellowing was observed on the laminated film before and after annealing (no hue change)

[0254] Yes (yellowing): Yellowing was observed on the laminated film before and after annealing (hue change)

[0255] If none (no yellowing), then the hue change after heat - treatment is small and good.

[0256] The tetracarboxylic acid components, diamine components, and their abbreviations used in the examples and comparative examples are as follows.

[0257] <Tetracarboxylic acid component>

[0258] CpODA: Norbornane - 2 - spiro - α - cyclopentanone - α'-spiro - 2'' - norbornane - 5,5'',6,6'' - tetracarboxylic dianhydride (compound shown in formula (a1))

[0259] s - BPDA: 3,3',4,4' - Biphenyltetracarboxylic dianhydride (manufactured by Mitsubishi Chemical Corporation, compound shown in formula (a2s))

[0260] BPAF: 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride (manufactured by JFE Chemical Corporation; compound represented by formula (a3))

[0261] <Diamine component>

[0262] TFMB: 2,2'-bis(trifluoromethyl)benzidine (compound represented by formula (b121))

[0263] 3,5-DABA: 3,5-diaminobenzoic acid (compound represented by formula (b21))

[0264] 4-BAAB: 4-aminophenyl-4-aminobenzoate (manufactured by Nippon Junyaku Co., Ltd.; compound represented by formula (b3))

[0265] <Phosphorus compound>

[0266] JP-513: Iso-tridecyl acid phosphate (manufactured by Johoku Chemical Industry Co., Ltd., in formula (3), the compound where R 3 is iso-tridecyl and n is 1, and the 1:1 mixture of the compound where R 3 is iso-tridecyl and n is 2)

[0267] DBP: Dibutyl phosphate (manufactured by Johoku Chemical Industry Co., Ltd., in formula (3), the compound where R 3 is butyl and n is 2)

[0268] Phosphoric acid: The compound where n is 0 in formula (3)

[0269] Trimethyl phosphate: The compound where R 3 is methyl and n is 3 in formula (3)

[0270] Triphenylphosphine: The compound where R 3 is phenyl and n is 3 in formula (3)

[0271] <Other compounds>

[0272] Irganox 1010 (antioxidant): Pentaerythritol tetra[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (manufactured by BASF Japan Ltd.)

[0273] <Surface modifier>

[0274] BYK-378: Organosilicon-based surface modifier (manufactured by BYK Japan KK)

[0275] The abbreviations of solvents, catalysts, etc. used in the examples and comparative examples are as follows.

[0276] NMP: N-methyl-2-pyrrolidone (manufactured by Tokyo Junyaku Kogyo Co., Ltd.)

[0277] GBL: γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation)

[0278] TEA: triethylamine (manufactured by Kanto Chemical Co., Inc.)

[0279] <Example 1>

[0280] In a 1 L five-necked round-bottom flask equipped with a stainless-steel semi-circular stirring blade, a nitrogen inlet tube, a Dean-Stark apparatus equipped with a cooling tube, a thermometer, and a glass end cap, 32.024 g (0.100 mol) of TFMB and 196.627 g of NMP were charged, and the mixture was stirred at a system temperature of 50 °C, under a nitrogen atmosphere, and at a rotation speed of 150 rpm to obtain a solution.

[0281] To this solution, 29.422 g (0.100 mol) of s-BPDA and 49.157 g of NMP were charged all at once, and the mixture was stirred for 7 hours while being maintained at 50 °C in a hooded heater.

[0282] Then, 307.230 g of NMP was added, and the mixture was further stirred for about 3 hours for homogenization to obtain a polyamic acid varnish having a solid component concentration of 10.0 mass%.

[0283] To 100 g of the obtained varnish, 0.01 g of JP-513 (1000 ppm relative to polyamic acid) and 0.01 g of BYK-378 (1000 ppm relative to polyamic acid) were added, and the mixture was stirred for 30 minutes for homogenization to obtain a polyamic acid composition varnish.

[0284] Next, the obtained polyamic acid composition varnish was spin-coated onto a glass plate, held at 80 °C on a hot plate for 20 minutes, then transferred to a hot air dryer, heated to 420 °C at a heating rate of 5 °C / minute under a nitrogen atmosphere, and heated at 420 °C in the hot air dryer for 60 minutes in a nitrogen atmosphere to evaporate the solvent and cause thermal imidization to obtain a polyimide film. The results are shown in Table 1.

[0285] <Examples 2 to 3 and Comparative Examples 2 to 4>

[0286] Instead of 0.01 g of JP-513 (1000 ppm relative to polyamic acid), 0.01 g each of the phosphorus compounds or other compounds shown in Table 1 (1000 ppm relative to polyamic acid) was used, and otherwise, a polyimide film was obtained in the same manner as in Example 1. The results are shown in Table 1.

[0287] <Comparative Example 1>

[0288] JP-513 was not used, and a polyimide film was obtained in the same manner as in Example 1 except for this. The results are shown in Table 1.

[0289] <Example 4>

[0290] In a 1 L five-necked round-bottom flask equipped with a stainless-steel semi-circular stirring blade, a nitrogen inlet tube, a Dean-Stark apparatus equipped with a cooling tube, a thermometer, and a glass end cap, 26.644 g (0.083 mol) of TFMB, 3.165 g (0.021 mol) of 3,5-DABA, and 163.792 g of GBL were charged, and the mixture was stirred at a system temperature of 70 °C, under a nitrogen atmosphere, and at a rotation speed of 150 rpm to obtain a solution.

[0291] To this solution, 38.438 g (0.100 mol) of CpODA and 40.948 g of GBL were added all at once, and then 0.506 g of TEA as an imidization catalyst and 0.056 g of triethylenediamine (manufactured by Tokyo Chemical Industry Co., Ltd.) were charged. The mixture was heated in a hooded heater, and the temperature inside the reaction system was raised to 190 °C in about 20 minutes. The components removed by distillation were trapped, the rotation speed was adjusted as the viscosity increased, and the temperature inside the reaction system was maintained at 190 °C and refluxed for 3 hours.

[0292] Then, GBL was added so that the solid content concentration became 10% by mass. After cooling the temperature inside the reaction system to 120 °C, the mixture was further stirred for about 1 hour for homogenization to obtain a polyimide varnish.

[0293] To 100 g of the obtained varnish, 0.01 g of JP-513 (1000 ppm relative to polyimide) and 0.01 g of BYK-378 (1000 ppm relative to polyimide) were added, and the mixture was stirred for 30 minutes for homogenization to obtain a polyimide composition varnish.

[0294] Next, the obtained polyimide composition varnish was coated on a glass plate by spin coating, and held at 80 °C on a hot plate for 20 minutes. Then, it was transferred to a hot air dryer, and the temperature was raised to 420 °C at a rate of 5 °C / minute under a nitrogen atmosphere, and heated at 420 °C in the hot air dryer for 60 minutes under a nitrogen atmosphere to evaporate the solvent, obtaining a polyimide film. The results are shown in Table 1.

[0295] <Examples 5 and 6>

[0296] Instead of 0.01 g of JP-513 (1000 ppm relative to polyamic acid), 0.01 g of each of the phosphorus compounds shown in Table 1 (1000 ppm relative to polyamic acid) was used respectively, and a polyimide film was obtained in the same manner as in Example 4 except for this. The results are shown in Table 1.

[0297] <Comparative Example 5>

[0298] JP-513 was not used, and a polyimide film was obtained in the same manner as in Example 4 except for this. The results are shown in Table 1.

[0299] <Example 7>

[0300] In a 1 L five-necked round-bottom flask equipped with a stainless-steel semi-circular stirring blade, a nitrogen inlet tube, a Dean-Stark equipped with a cooling tube, a thermometer, and a glass end cap, 25.619 g (0.080 mol) of TFMB, 3.043 g (0.020 mol) of 3,5-DABA, and 156.713 g of GBL were charged, and stirring was carried out at a system temperature of 70 °C, under a nitrogen atmosphere, and at a rotation speed of 150 rpm to obtain a solution.

[0301] To this solution, 30.750 g (0.080 mol) of CpODA, 5.884 g (0.020 mol) of s-BPDA, and 39.178 g of GBL were added all at once, and then 0.506 g of TEA (triethylamine, manufactured by Tokyo Chemical Industry Co., Ltd.) and 0.056 g of triethylenediamine as an imidization catalyst were charged, and heating was carried out in a hood heater. It took about 20 minutes to raise the temperature inside the reaction system to 190 °C. The components removed by distillation were trapped, the rotation speed was adjusted as the viscosity increased, and the temperature inside the reaction system was maintained at 190 °C for 2 hours of reflux.

[0302] Then, GBL was added so that the solid content concentration became 10% by mass. After cooling the temperature inside the reaction system to 120 °C, stirring was further carried out for about 1 hour for homogenization to obtain a polyimide varnish with a solid content concentration of 10% by mass.

[0303] To 100 g of the obtained varnish, 0.01 g of JP-513 (1000 ppm relative to polyimide) and 0.01 g of BYK-378 (1000 ppm relative to polyimide) were charged, and stirring was carried out for 30 minutes for homogenization to obtain a polyimide composition varnish.

[0304] Next, the obtained polyimide composition varnish was coated on a glass plate by spin coating, held at 80 °C on a hot plate for 20 minutes, then transferred to a hot air dryer, heated to 420 °C at a heating rate of 5 °C / minute under a nitrogen atmosphere, and heated at 420 °C in the hot air dryer for 60 minutes under a nitrogen atmosphere to evaporate the solvent, obtaining a polyimide film. The results are shown in Table 1.

[0305] <Comparative Example 6>

[0306] JP-513 was not used, and a polyimide film was obtained in the same manner as in Example 7 except for this. The results are shown in Table 1.

[0307] <Example 8>

[0308] In a 1 L five-necked round-bottom flask equipped with a stainless-steel semi-circular stirring blade, a nitrogen inlet tube, a Dean-Stark apparatus equipped with a cooling tube, a thermometer, and a glass end cap, 32.024 g (0.100 mol) of TFMB and 169.109 g of NMP were charged, and the mixture was stirred at a system temperature of 70 °C, under a nitrogen atmosphere, and at a rotation speed of 150 rpm to obtain a solution.

[0309] To this solution, 38.438 g (0.100 mol) of CpODA and 42.277 g of NMP were added all at once, and then 0.506 g of TEA and 0.056 g of triethylenediamine (manufactured by Tokyo Chemical Industry Co., Ltd.), which were used as imidization catalysts, were charged. The mixture was heated in a hooded heater, and the temperature inside the reaction system was raised to 190 °C in about 20 minutes. The components removed by distillation were trapped, the rotation speed was adjusted as the viscosity increased, and the temperature inside the reaction system was maintained at 190 °C for 2 hours of reflux.

[0310] Then, NMP was added so that the solid content concentration became 10% by mass. After cooling the temperature inside the reaction system to 120 °C, the mixture was further stirred for about 1 hour for homogenization to obtain a polyimide varnish.

[0311] 0.01 g of JP-513 (1000 ppm relative to polyimide) and 0.01 g of BYK-378 (1000 ppm relative to polyimide) were added to 100 g of the obtained varnish, and the mixture was stirred for 30 minutes for homogenization to obtain a polyimide composition varnish.

[0312] Next, the obtained polyimide composition varnish was coated on a glass plate by spin coating, held at 80 °C on a hot plate for 20 minutes, and then transferred to a hot air dryer. The temperature was raised to 420 °C at a rate of 5 °C / minute under a nitrogen atmosphere, and the mixture was heated at 420 °C in the hot air dryer for 60 minutes to evaporate the solvent, obtaining a polyimide film. The results are shown in Table 1.

[0313] <Comparative Example 7>

[0314] A polyimide film was obtained in the same manner as in Example 8 except that JP-513 was not used. The results are shown in Table 1.

[0315] <Example 9>

[0316] In a 500 mL five-necked round-bottom flask equipped with a stainless-steel semi-circular stirring blade, a nitrogen inlet tube, a Dean-Stark apparatus equipped with a cooling tube, a thermometer, and a glass end cap, 12.810 g (0.040 mol) of TFMB and 44.603 g of NMP were charged, and the mixture was stirred at 200 rpm under a nitrogen atmosphere at a system temperature of 70 °C to obtain a solution.

[0317] To this solution, 11.531 g (0.030 mol) of CpODA and 11.151 g of NMP were added all at once, and then 0.152 g of TEA as an imidization catalyst was charged. The mixture was heated with a covered heater, and the temperature inside the reaction system was raised to 190 °C over about 20 minutes. The components removed by distillation were trapped, the rotation speed was adjusted as the viscosity increased, and the temperature inside the reaction system was maintained at 190 °C for 1 hour of reflux. Then, 92.065 g of NMP was added, and the temperature inside the reaction system was cooled to 50 °C to obtain a solution containing an oligomer having an imide repeating structural unit.

[0318] To the obtained solution, 20.595 g (0.070 mol) of s-BPDA, 13.695 g (0.060 mol) of 4-BAAB, and 16.199 g of NMP were added all at once, and the mixture was stirred at 50 °C for 5 hours. Then, NMP was added to make the solid content concentration approximately 15% by mass for homogenization, thereby obtaining a varnish (imide-amido acid copolymer varnish) containing a copolymer having an imide repeating structural unit and an amido acid structural unit.

[0319] To 100 g of the obtained varnish, 0.015 g of JP-513 (1000 ppm with respect to the imide-amido acid copolymer) and 0.015 g of BYK-378 (1000 ppm with respect to the imide-amido acid copolymer) were charged, and the mixture was stirred for 30 minutes for homogenization to obtain an imide-amido acid copolymer composition varnish.

[0320] Next, the obtained imide-amido acid copolymer composition varnish was spin-coated onto a glass plate, held at 80 °C on a hot plate for 20 minutes, then transferred to a hot air dryer, and heated to 420 °C at a heating rate of 5 °C / minute under a nitrogen atmosphere. The solvent was evaporated by heating at 420 °C for 60 minutes in a nitrogen atmosphere in the hot air dryer to cause thermal imidization, obtaining a polyimide film. The results are shown in Table 1.

[0321] 〈Comparative Example 8〉

[0322] JP-513 was not used, and a polyimide film was obtained in the same manner as in Example 9 except for this. The results are shown in Table 1.

[0323] Note that the polyimide film obtained in Comparative Example 8 could not be peeled off from the glass plate. Therefore, the total light transmittance and yellowness index (YI) of Example 9 and Comparative Example 8 were measured in a manner including the glass plate. In addition, for the polyimide film obtained in Comparative Example 8, the 1% weight loss temperature (Td1%) was not measured.

[0324] <Example 10>

[0325] Into a 500 mL five-necked round-bottom flask equipped with a stainless-steel semi-circular stirring blade, a nitrogen inlet tube, a Dean-Stark with a condenser tube, a thermometer, and a glass end cap, 9.607 g (0.030 mol) of TFMB and 46.380 g of NMP were charged, and the mixture was stirred at 200 rpm under a nitrogen atmosphere at a system temperature of 70 °C to obtain a solution.

[0326] To this solution, 9.169 g (0.020 mol) of BPAF and 11.595 g of NMP were added all at once, and then 0.152 g of TEA as an imidization catalyst was added. The mixture was heated with a covered heater, and the temperature inside the reaction system was raised to 190 °C over about 20 minutes. The components removed by distillation were trapped, the rotation speed was adjusted as the viscosity increased, and the temperature inside the reaction system was maintained at 190 °C for 1 hour of reflux. Then, 95.849 g of NMP was added, and the temperature inside the reaction system was cooled to 50 °C to obtain a solution containing an oligomer having an imide repeating structural unit.

[0327] To the obtained solution, 23.538 g (0.080 mol) of s-BPDA, 15.978 g (0.070 mol) of 4-BAAB, and 16.858 g of NMP were added all at once, and the mixture was stirred at 50 °C for 5 hours. Then, NMP was added to make the solid content concentration approximately 15% by mass for homogenization, thereby obtaining a varnish (imide-amidic acid copolymer varnish) containing a copolymer having an imide repeating structural unit and an amidic acid structural unit.

[0328] Into 100 g of the obtained varnish, 0.015 g of JP-513 (1000 ppm with respect to the imide-amidic acid copolymer) and 0.015 g of BYK-378 (1000 ppm with respect to the imide-amidic acid copolymer) were added, and the mixture was stirred for 30 minutes for homogenization to obtain an imide-amidic acid copolymer composition varnish.

[0329] Next, the obtained imide-acid copolymer composition varnish was coated on a glass plate by spin coating, held at 80 °C on a hot plate for 20 minutes, then transferred to a hot air dryer, heated to 430 °C at a heating rate of 5 °C / minute under a nitrogen atmosphere, and heated in the hot air dryer at 430 °C for 60 minutes to evaporate the solvent, followed by thermal imidization to obtain a polyimide film. The results are shown in Table 1.

[0330] 〈Comparative Example 9〉

[0331] JP-513 was not used, and a polyimide film was obtained in the same manner as in Example 10 except for this. The results are shown in Table 1.

[0332] It should be noted that the polyimide film obtained in Comparative Example 9 could not be peeled off from the glass plate. Therefore, the total light transmittance and yellowness index (YI) of Example 10 and Comparative Example 9 were measured in a manner including the glass plate. In addition, for the polyimide film obtained in Comparative Example 9, the 1% weight loss temperature (Td1%) was not measured.

[0333] [Table 1]

[0334]

[0335] As shown in Table 1, it can be seen that the polyimide film obtained from the polymer composition of the present invention has excellent heat resistance and colorlessness after heat treatment, and also has a low yellowness degree. In addition, it can be seen that the polyimide film of the example is also excellent in transparency compared with the polyimide film of the corresponding comparative example.

Claims

1. A polymer composition comprising a polymer (X) and a compound (Y) represented by the following general formula (3), The polymer (X) comprises at least one selected from the group consisting of repeating units represented by the following general formula (1) and repeating units represented by the following general formula (2), In formula (1), X 1 is a tetravalent group having an alicyclic structure or an aromatic ring, and X is at least one selected from the group consisting of a single bond, -NHCO-, -CONH-, -COO- and -OCO-, In formula (2), X 2 is a tetravalent group having an alicyclic structure or an aromatic ring, R 1 and R 2 are each independently hydrogen, an alkyl group having 1 to 6 carbon atoms, or an alkylsilyl group having 3 to 9 carbon atoms, and X is at least one selected from the group consisting of a single bond, -NHCO-, -CONH-, -COO- and -OCO-, In formula (3), R 3 is an alkyl group having 1 to 30 carbon atoms, and n is 1 to 2, wherein, The content of the compound (Y) is 10 ppm or more and 10,000 ppm or less relative to the polymer (X).

2. The polymer composition according to claim 1, wherein, The polymer (X) contains at least one selected from the group consisting of repeating units represented by the following general formula (1-2) and repeating units represented by the following general formula (2-2). In formula (1-2), X 1 is a tetravalent group having an alicyclic structure or an aromatic ring, X is at least one selected from the group consisting of a single bond, -NHCO-, -CONH-, -COO- and -OCO-, and in formula (2-2), X 2 is a tetravalent group having an alicyclic structure or an aromatic ring, R 1 and R 2 are each independently hydrogen, an alkyl group having 1 to 6 carbon atoms, or an alkylsilyl group having 3 to 9 carbon atoms, and X is at least one selected from the group consisting of a single bond, -NHCO-, -CONH-, -COO- and -OCO-.

3. The polymer composition according to claim 1, wherein, X in the formula (1) and the formula (2) is a single bond.

4. The polymer composition according to any one of claims 1 to 3, wherein, The polymer (X) contains at least one selected from the group consisting of repeating units represented by the following general formula (1-2-1) and repeating units represented by the following general formula (2-2-1). In formula (1-2-1), X 1 is a tetravalent group having an alicyclic structure or an aromatic ring. In formula (2-2-1), X 2 is a tetravalent group having an alicyclic structure or an aromatic ring, R 1 and R 2 are each independently hydrogen, an alkyl group having 1 to 6 carbon atoms, or an alkylsilyl group having 3 to 9 carbon atoms.

5. The polymer composition according to any one of claims 1 to 3, wherein, The repeating units represented by the formula (1) are 10 mol% or more relative to all the repeating units of the polymer (X).

6. The polymer composition according to any one of claims 1 to 3, wherein, The repeating units represented by the formula (2) are 10 mol% or more relative to all the repeating units of the polymer (X).

7. A varnish obtained by dissolving the polymer composition according to any one of claims 1 to 6 in an organic solvent.

8. A polyimide film obtained by coating the varnish according to claim 7 on a support and heating.

9. A method for manufacturing a polyimide film, wherein, The varnish according to claim 7 is coated on a support and heated.

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