Polyamic acid, polyamic acid composition, polyimide, polyimide film, laminate, method for producing laminate, and electronic device

Abstract

To provide a polyimide excellent in transparency and capable of suppressing generation of hydrogen fluoride during a high-temperature process, and a polyamic acid as a precursor thereof.SOLUTION: The polyamic acid has a tetracarboxylic dianhydride residue containing a tetravalent organic group represented by the following formula (12) and a diamine residue containing a divalent organic group represented by the following formula (1). In the formula (1), R1 and R2 represent a trifluoromethoxy group or the like.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a polyamic acid, a polyamic acid composition, a polyimide, a polyimide film, a laminate, a method for producing the laminate, and an electronic device. The present invention also relates to an electronic device material using the polyimide, a thin film transistor (TFT) substrate, a flexible display substrate, a color filter, a printed matter, an optical material, an image display device (more specifically, a liquid crystal display device, an organic electroluminescence (EL) display, an electronic paper, etc.), a 3D display, a solar cell, a touch panel, a transparent conductive film substrate, and a substitute material for a component currently using glass. [Background technology]

[0002] Rapid advances in electronic devices, such as displays (LCDs, OLEDs, electronic paper, etc.), solar cells, and touch panels, have led to devices becoming thinner, lighter, and more flexible. In these devices, polyimide is being used as the substrate material instead of glass.

[0003] These devices require various electronic elements, such as thin-film transistors and transparent electrodes, to be formed on the substrate, and high-temperature processes are required to form these electronic elements. Polyimide has sufficient heat resistance to be applicable to high-temperature processes, and its coefficient of thermal expansion (CTE) is close to that of glass substrates and electronic elements, making it less susceptible to internal stress and suitable for use as a substrate material for flexible displays and other applications.

[0004] Aromatic polyimides are generally colored yellowish-brown due to intramolecular conjugation and the formation of charge-transfer (CT) complexes, but in top-emission organic electroluminescence (OLED) and other displays, where light is extracted from the opposite side of the substrate, transparency is not required for the substrate, and conventional aromatic polyimides have been used. However, in cases where light emitted from the display element is emitted through the substrate, such as in transparent displays, bottom-emission organic electroluminescence (OLED) and LCD displays, or when sensors or camera modules are placed on the back of the substrate to make smartphones and other devices full-screen (notchless), high optical properties (more specifically, transparency, etc.) are now required for the substrate as well.

[0005] In light of this, there is a demand for materials that have heat resistance equivalent to that of existing aromatic polyimides, but that are less colored and have excellent transparency.

[0006] To reduce the coloration of polyimides, there are known techniques for suppressing the formation of CT complexes using aliphatic monomers (Patent Documents 1 and 2), and for increasing transparency by using monomers containing fluorine atoms (Patent Document 3).

[0007] The polyimides described in Patent Documents 1 and 2 have high transparency and low CTE, but because they have an aliphatic structure, they have a low thermal decomposition temperature, making them difficult to apply to high-temperature processes when forming electronic devices. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-29177 [Patent Document 2] Japanese Patent Application Laid-Open No. 2012-41530 [Patent Document 3] Japanese Patent Application Laid-Open No. 2014-70139 Summary of the Invention [Problem to be solved by the invention]

[0009] Furthermore, the polyimide described in Patent Document 3 has excellent transparency, but the inventors have found through their studies that, because it contains fluorine atoms, hydrogen fluoride may be generated during high-temperature processes. The generation of hydrogen fluoride may result in poor adhesion between the polyimide and a barrier film or the like, or may cause corrosion of electronic elements provided on the polyimide film.

[0010] The present invention has been made in view of the above circumstances, and aims to provide a polyimide that has excellent transparency and is capable of suppressing the generation of hydrogen fluoride during high-temperature processes, and a polyamic acid as its precursor. Another aim of the present invention is to provide a product or member that is produced using the polyimide or polyamic acid and that is required to be transparent. [Means for solving the problem]

[0011] <Aspects of the present invention> The present invention includes the following aspects.

[0012] [1] A polyamic acid having a tetracarboxylic dianhydride residue and a diamine residue, The diamine residue contains a divalent organic group represented by the following general formula (1): The tetracarboxylic dianhydride residue is a polyamic acid containing a tetravalent organic group represented by the following chemical formula (12):

[0013] [ka]

[0014] In the general formula (1), R 1 and R 2 each independently represents a trifluoromethoxy group, a pentafluoroethoxy group, or a heptafluoropropoxy group; a represents an integer of 1 or more and 4 or less; b represents an integer of 0 or more and 4 or less; when a represents an integer of 2 or more and 4 or less, a plurality of R 1 may be the same or different, and when b represents an integer of 2 or more and 4 or less, a plurality of R2 may be the same or different, and n represents an integer of 0 or more and 3 or less.

[0015] [2] The polyamic acid according to [1] above, wherein the tetracarboxylic dianhydride residue further comprises one or more selected from the group consisting of a tetravalent organic group represented by the following chemical formula (2), a tetravalent organic group represented by the following chemical formula (3), a tetravalent organic group represented by the following chemical formula (4), a tetravalent organic group represented by the following chemical formula (5), a tetravalent organic group represented by the following chemical formula (6), a tetravalent organic group represented by the following chemical formula (7), a tetravalent organic group represented by the following chemical formula (8), a tetravalent organic group represented by the following chemical formula (9), and a tetravalent organic group represented by the following chemical formula (10).

[0016] [ka]

[0017] [3] The polyamic acid according to [2] above, wherein the tetracarboxylic dianhydride residue further contains one or more groups selected from the group consisting of a tetravalent organic group represented by the following chemical formula (11) and a tetravalent organic group represented by the following chemical formula (13):

[0018] [ka]

[0019] [4] A polyamic acid composition comprising the polyamic acid according to any one of [1] to [3] above and an organic solvent.

[0020] [5] The polyamic acid composition according to [4] above, further comprising one or more compounds selected from the group consisting of tertiary amines, phosphorus-containing compounds, and phenolic compounds.

[0021] [6] The polyamic acid composition according to [5], wherein the amount of the one or more compounds selected from the group consisting of tertiary amines, phosphorus-containing compounds, and phenolic compounds is 0.001 parts by weight or more and 20 parts by weight or less per 100 parts by weight of the polyamic acid.

[0022] [7] A polyimide which is an imidized product of the polyamic acid according to any one of [1] to [3] above.

[0023] [8] The polyimide according to [7] above, wherein the polyimide is heated in a helium gas flow from an ambient temperature of 60°C to 500°C at a heating rate of 10°C / min, and the gas generated from the polyimide is analyzed with a quadrupole mass spectrometer. In the resulting mass spectrum, the detected intensity of the peak at m / z=20 at an ambient temperature of 450°C divided by the detected intensity of the peak at m / z=20 at an ambient temperature of 100°C is 3.0 or less.

[0024] [9] A polyimide film comprising the polyimide according to [7] or [8].

[0025]

[10] The polyimide film according to [9] above, which has a transmittance of 30% or more for light with a wavelength of 400 nm.

[0026]

[11] The polyimide film according to [9] or

[10] above, which has a haze of 1.0% or less.

[0027]

[12] A laminate comprising a support and the polyimide film according to any one of [9] to

[11] above.

[0028]

[13] A method for producing a laminate having a support and a polyimide film, comprising: A method for producing a laminate, comprising applying the polyamic acid composition according to any one of [4] to [6] above onto a support to form a coating film containing the polyamic acid, and heating the coating film to imidize the polyamic acid.

[0029]

[14] An electronic device comprising the polyimide film according to any one of [9] to

[11] above and an electronic element disposed on the polyimide film. [Effects of the Invention]

[0030] The polyimide produced using the polyamic acid according to the present invention has excellent transparency and can suppress the generation of hydrogen fluoride during high-temperature processes, making it suitable as a material for electronic devices that require transparency and are manufactured through high-temperature processes. DETAILED DESCRIPTION OF THE INVENTION

[0031] Preferred embodiments of the present invention will be described in detail below, but the present invention is not limited thereto. In addition, all academic and patent documents described in this specification are incorporated herein by reference.

[0032] First, the terms used in this specification will be explained. A "structural unit" refers to a repeating unit that constitutes a polymer. A "polyamic acid" is a polymer containing a structural unit represented by the following general formula (14) (hereinafter, sometimes referred to as "structural unit (14)").

[0033] [ka]

[0034] In general formula (14), A 1 represents a tetracarboxylic dianhydride residue (a tetravalent organic group derived from a tetracarboxylic dianhydride), and A 2 represents a diamine residue (a divalent organic group derived from a diamine).

[0035] The content of the structural unit (14) relative to all structural units constituting the polyamic acid is, for example, 50 mol% or more and 100 mol% or less, preferably 60 mol% or more and 100 mol% or less, more preferably 70 mol% or more and 100 mol% or less, even more preferably 80 mol% or more and 100 mol% or less, still more preferably 90 mol% or more and 100 mol% or less, and may be 100 mol%.

[0036] "m / z" is a measurement value that can be read from the horizontal axis of a mass spectrum, which is the measurement result of mass spectrometry. It is "a dimensionless quantity obtained by dividing the mass of an ion by the unified atomic mass unit (Dalton), and then dividing that quantity by the absolute value of the charge on the ion."

[0037] Hereinafter, the compound name may be followed by "system" to collectively refer to the compound and its derivatives. Furthermore, when the compound name is followed by "system" to represent the name of a polymer, unless otherwise specified, it means that the repeating unit of the polymer is derived from the compound or its derivative. Furthermore, tetracarboxylic acid dianhydrides may be referred to as "acid dianhydrides." Furthermore, unless otherwise specified, the components and functional groups exemplified in this specification may be used alone or in combination of two or more types.

[0038] <Preferred embodiment of the present invention> The polyamic acid according to this embodiment (hereinafter, may be referred to as "specific polyamic acid") has a tetracarboxylic dianhydride residue and a diamine residue.

[0039] In the specific polyamic acid, the diamine residue contains a divalent organic group represented by the following general formula (1) (hereinafter, sometimes referred to as a "specific diamine residue"). That is, the specific polyamic acid contains a specific diamine residue as the diamine residue. Furthermore, in the specific polyamic acid, the tetracarboxylic dianhydride residue contains a tetravalent organic group represented by the following chemical formula (12). That is, the specific polyamic acid contains a tetravalent organic group represented by the following chemical formula (12) as the tetracarboxylic dianhydride residue.

[0040] [ka]

[0041] In general formula (1), R 1 and R 2 each independently represents a trifluoromethoxy group, a pentafluoroethoxy group, or a heptafluoropropoxy group; a represents an integer of 1 or more and 4 or less; b represents an integer of 0 or more and 4 or less; when a represents an integer of 2 or more and 4 or less, a plurality of R 1 may be the same or different, and when b represents an integer of 2 or more and 4 or less, a plurality of R 2 may be the same or different, and n represents an integer of 0 or more and 3 or less. In general formula (1), a and b may be the same or different.

[0042] The tetravalent organic group represented by chemical formula (12) is a residue derived from 2,3,6,7-naphthalenetetracarboxylic dianhydride (hereinafter, sometimes referred to as "NTCDA"). That is, in the specific polyamic acid, the tetracarboxylic dianhydride residue includes an NTCDA residue.

[0043] Polyimides produced using specific polyamic acids have excellent transparency and can suppress the generation of hydrogen fluoride during high-temperature processes. The reasons for this are presumed to be as follows.

[0044] The specific polyamic acid has a specific diamine residue containing a fluorine atom. Therefore, in the polyimide produced using the specific polyamic acid, the formation of a CT complex is suppressed. Therefore, the polyimide produced using the specific polyamic acid has excellent transparency.

[0045] Furthermore, since the specific polyamic acid has an NTCDA residue, which has a rigid structure, polyimides produced using the specific polyamic acid have excellent heat resistance. Furthermore, in the specific diamine residue contained in the specific polyamic acid, a fluoroalkyl group is bonded to an aromatic ring via an oxygen atom. Therefore, even when a polyimide produced using the specific polyamic acid is exposed to a high-temperature environment, hydrogen fluoride is unlikely to be generated. Therefore, polyimides produced using the specific polyamic acid can suppress the generation of hydrogen fluoride during high-temperature processes.

[0046] Furthermore, since the specific polyamic acid has an NTCDA residue, which has a rigid structure, it can reduce the internal stress between the support and the polyimide film when a polyimide film, which will be described later, is formed.

[0047] The specific polyamic acid may contain a residue (e.g., 2,2'-bis(trifluoromethyl)benzidine residue, 4,4'-(hexafluoroisopropylidene)diphthalic anhydride residue) having a structure in which a fluoroalkyl group (e.g., trifluoromethyl group, pentafluoroethyl group, heptafluoropropyl group, etc.) is directly bonded to a carbon atom, as long as its performance is not impaired. However, in order to further suppress the generation of hydrogen fluoride during high-temperature processes, the content of residues having a structure in which a fluoroalkyl group is directly bonded to a carbon atom is preferably 0.1 wt% or less, and more preferably 0.01 wt% or less, relative to the total amount (100 wt%) of the specific polyamic acid. In order to further suppress the generation of hydrogen fluoride during high-temperature processes, the specific polyamic acid is preferably a polyamic acid that does not contain a residue having a structure in which a fluoroalkyl group is directly bonded to a carbon atom.

[0048] In order to further suppress the generation of hydrogen fluoride during a high-temperature process, R 1 and R 2preferably represents a trifluoromethoxy group. In order to further suppress the generation of hydrogen fluoride during a high-temperature process, a in general formula (1) is preferably 1 or 2, and more preferably 1. In order to further suppress the generation of hydrogen fluoride during a high-temperature process, b in general formula (1) is preferably an integer of 0 or more and 2 or less, and more preferably 0 or 1.

[0049] In order to increase the solubility of the specific polyamic acid in organic solvents while reducing the CTE of the resulting polyimide, n in general formula (1) is preferably 1 or 2, and more preferably 1.

[0050] In order to obtain a polyimide that is more excellent in transparency and can further suppress the generation of hydrogen fluoride during a high-temperature process, the specific diamine residue is preferably one or more selected from the group consisting of residues derived from 2,2′-bis(trifluoromethoxy)benzidine (hereinafter sometimes referred to as “TFMOB”), residues derived from 3,3′-bis(trifluoromethoxy)benzidine, and residues derived from 2,3′-bis(trifluoromethoxy)benzidine, and more preferably a TFMOB residue.

[0051] The specific polyamic acid containing the specific diamine residue has excellent solubility due to the fluorine content, and by imparting photosensitivity to the specific polyamic acid, it can be used as a pattern-forming material or a material requiring planarization performance.

[0052] When synthesizing the specific polyamic acid, a diamine monomer (another diamine) other than the diamine for forming the specific diamine residue can also be used. Examples of other diamines include 4-aminophenyl-4-aminobenzoate (hereinafter sometimes referred to as "4-BAAB"), p-phenylenediamine, 1,3-bis(3-aminopropyl)tetramethyldisiloxane, 9,9-bis(4-aminophenyl)fluorene, 4,4'-diaminodiphenyl sulfone, 4,4'-diaminobenzanilide, m-phenylenediamine, 4,4'-oxydianiline, 3,4'-oxydianiline, N,N'-bis(4-aminophenyl)terephthalamide, m-tolidine, o-tolidine, 4,4'-bis(4-aminophenoxy)biphenyl, 2-(4-aminophenyl)-6-aminobenzoxazole, 3,5-diaminobenzoic acid, 4,4'-diamino-3,3'-dihydroxybiphenyl, 4,4'-methylenebis(cyclohexanamine), and derivatives thereof, and these may be used alone or in combination.

[0053] In order to obtain a polyimide capable of reducing internal stress while maintaining transparency, 4-BAAB is preferred as the other diamine. In other words, in order to obtain a polyimide capable of reducing internal stress while maintaining transparency, the specific polyamic acid preferably has a 4-BAAB residue.

[0054] In order to obtain a polyimide having superior transparency, the content of the specific diamine residue is preferably 50 mol% or more, more preferably 70 mol% or more, even more preferably 80 mol% or more, and even more preferably 90 mol% or more, relative to the total amount (100 mol%) of diamine residues constituting the specific polyamic acid, and may be 100 mol%.

[0055] In order to obtain a polyimide that can further reduce internal stress while maintaining transparency, the content of 4-BAAB residues is preferably 1 mol % or more and 20 mol % or less, more preferably 3 mol % or more and 18 mol % or less, and even more preferably 5 mol % or more and 15 mol % or less, relative to the total amount (100 mol %) of diamine residues constituting the specific polyamic acid.

[0056] In order to obtain a polyimide having excellent transparency while further reducing internal stress, the total content of the specific diamine residues and 4-BAAB residues is preferably 80 mol % or more, more preferably 90 mol % or more, and may be 100 mol %, relative to the total amount (100 mol %) of diamine residues constituting the specific polyamic acid.

[0057] The specific polyamic acid may have an acid dianhydride residue other than the NTCDA residue (another acid dianhydride residue). In order to obtain a polyimide having superior transparency, the other acid dianhydride residue is preferably one or more residues selected from the group consisting of a tetravalent organic group represented by the following chemical formula (2), a tetravalent organic group represented by the following chemical formula (3), a tetravalent organic group represented by the following chemical formula (4), a tetravalent organic group represented by the following chemical formula (5), a tetravalent organic group represented by the following chemical formula (6), a tetravalent organic group represented by the following chemical formula (7), a tetravalent organic group represented by the following chemical formula (8), a tetravalent organic group represented by the following chemical formula (9), and a tetravalent organic group represented by the following chemical formula (10) (hereinafter, these may be referred to as "specific acid dianhydride residues").

[0058] [ka]

[0059] The tetravalent organic group represented by chemical formula (2) is a partial structure (residue) derived from 2,3,3',4'-biphenyltetracarboxylic dianhydride (hereinafter sometimes referred to as "a-BPDA"). The tetravalent organic group represented by chemical formula (3) is a partial structure (residue) derived from 2,2',3,3'-biphenyltetracarboxylic dianhydride (hereinafter sometimes referred to as "i-BPDA"). The tetravalent organic group represented by chemical formula (4) is a partial structure (residue) derived from 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride (hereinafter sometimes referred to as "BPAF"). The tetravalent organic group represented by chemical formula (5) is a partial structure (residue) derived from spiro[11H-difuro[3,4-b:3',4'-i]xanthene-11,9'-[9H]fluorene]-1,3,7,9-tetrone (hereinafter sometimes referred to as "SFDA"). The tetravalent organic group represented by chemical formula (6) is a partial structure (residue) derived from 3,4'-oxydiphthalic anhydride (hereinafter sometimes referred to as "a-ODPA"). The tetravalent organic group represented by chemical formula (7) is a partial structure (residue) derived from 4,4'-oxydiphthalic anhydride (hereinafter sometimes referred to as "ODPA"). The tetravalent organic group represented by chemical formula (8) is a partial structure (residue) derived from decahydro-1H,3H-4,10:5,9-dimethanonaphtho[2,3-c:6,7-c']difuran-1,3,6,8-tetraone (hereinafter sometimes referred to as "DNDA"). The tetravalent organic group represented by chemical formula (9) is a partial structure (residue) derived from 5,5'-bis-2-norbornene-5,5',6,6'-tetracarboxylic acid-5,5',6,6'-dianhydride (hereinafter, sometimes referred to as "BNBDA"). The tetravalent organic group represented by chemical formula (10) is a partial structure (residue) derived from norbornane-2-spiro-α-cyclopentanone-α'-spiro-2"-norbornane-5,5",6,6"-tetracarboxylic acid dianhydride (hereinafter, sometimes referred to as "CpODA").

[0060] In order to obtain a polyimide having excellent transparency, the specific acid dianhydride residue is preferably one or more residues selected from the group consisting of an ODPA residue, a BPAF residue, and an SFDA residue.

[0061] To obtain a polyimide having excellent heat resistance and transparency, the specific acid dianhydride residue is preferably one or more residues selected from the group consisting of BPAF residues and SFDA residues. To obtain a polyimide having excellent mechanical properties, the specific acid dianhydride residue is preferably ODPA residues. To further suppress the formation of CT complexes, the specific acid dianhydride residue is preferably one or more residues selected from the group consisting of DNDA residues, BNBDA residues, and CpODA residues.

[0062] When synthesizing the specific polyamic acid, an acid dianhydride other than NTCDA and an acid dianhydride for forming the specific acid dianhydride residue may be used. Examples of the acid dianhydride other than NTCDA for forming the specific acid dianhydride residue include pyromellitic dianhydride (hereinafter sometimes referred to as "PMDA"), 3,3',4,4'-biphenyltetracarboxylic dianhydride (hereinafter sometimes referred to as "s-BPDA"), 1,2,5,6-naphthalenetetracarboxylic dianhydride, p-phenylenebis(trimellitate anhydride), 3,3',4,4'-benzophenonetetracarboxylic dianhydride, dicyclohexyl-3,3',4,4'-tetracarboxylic dianhydride, 1,2,4,5-cyclohexanetetracarboxylic dianhydride, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, and derivatives thereof, and these may be used alone or in combination of two or more.

[0063] In particular, when the specific polyamic acid has a specific acid dianhydride residue, in order to obtain a polyimide that has excellent heat resistance and can reduce CTE, the specific polyamic acid preferably has one or more selected from the group consisting of s-BPDA residues and PMDA residues. The s-BPDA residue is a tetravalent organic group represented by the following chemical formula (11). The PMDA residue is a tetravalent organic group represented by the following chemical formula (13).

[0064] [ka]

[0065] In order to obtain a polyimide that can further reduce internal stress while further suppressing the generation of hydrogen fluoride during a high-temperature process, the content of NTCDA residues relative to the total amount (100 mol%) of tetracarboxylic dianhydride residues constituting the specific polyamic acid is preferably 5 mol% to 90 mol% inclusive, more preferably 5 mol% to 80 mol% inclusive, even more preferably 10 mol% to 80 mol% inclusive, still more preferably 15 mol% to 70 mol% inclusive, and may be 20 mol% to 60 mol% inclusive, 25 mol% to 60 mol% inclusive, 30 mol% to 60 mol% inclusive, 35 mol% to 60 mol% inclusive, or 40 mol% to 60 mol% inclusive.

[0066] To obtain a polyimide having excellent transparency, the content of the specific acid dianhydride residue (when multiple types of specific acid dianhydride residues are used, the total content thereof) is preferably 5 mol% or more, more preferably 10 mol% or more, and even more preferably 20 mol% or more, and may be 30 mol% or more, 40 mol% or more, 50 mol% or more, 60 mol% or more, 70 mol% or more, or 80 mol% or more, based on the total amount (100 mol%) of tetracarboxylic dianhydride residues constituting the specific polyamic acid. Furthermore, to obtain a polyimide having excellent heat resistance, the content of the specific acid dianhydride residue (when multiple types of specific acid dianhydride residues are used, the total content thereof) is preferably 95 mol% or less, more preferably 90 mol% or less, based on the total amount (100 mol%) of tetracarboxylic dianhydride residues constituting the specific polyamic acid.

[0067] When the specific polyamic acid has a BPAF residue as the specific acid dianhydride residue, in order to obtain a polyimide having excellent transparency, the content of the BPAF residue is preferably from 1 mol % to 20 mol % and more preferably from 5 mol % to 15 mol % relative to the total amount (100 mol %) of the tetracarboxylic dianhydride residues constituting the specific polyamic acid.

[0068] When the specific polyamic acid has an SFDA residue as the specific acid dianhydride residue, in order to obtain a polyimide having superior transparency, the content of the SFDA residue is preferably 10 mol % or more and 90 mol % or less, and more preferably 20 mol % or more and 80 mol % or less, relative to the total amount (100 mol %) of the tetracarboxylic dianhydride residues constituting the specific polyamic acid.

[0069] When the specific polyamic acid has an ODPA residue as the specific acid dianhydride residue, in order to obtain a polyimide having superior transparency, the content of the ODPA residue is preferably 1 mol % or more and 20 mol % or less, and more preferably 5 mol % or more and 15 mol % or less, relative to the total amount (100 mol %) of the tetracarboxylic dianhydride residues constituting the specific polyamic acid.

[0070] In order to obtain a polyimide that is superior in heat resistance and can further reduce the CTE, the content of one or more residues selected from the group consisting of s-BPDA residues and PMDA residues is preferably 5 mol % or more and 60 mol % or less, and more preferably 10 mol % or more and 50 mol % or less, relative to the total amount (100 mol %) of tetracarboxylic dianhydride residues constituting the specific polyamic acid.

[0071] In order to obtain a polyimide that can further reduce internal stress while further suppressing the generation of hydrogen fluoride during a high-temperature process and that has excellent transparency, the total content of NTCDA residues, specific acid dianhydride residues, s-BPDA residues, and PMDA residues is preferably 80 mol % or more, more preferably 90 mol % or more, and may even be 100 mol %, relative to the total amount (100 mol %) of tetracarboxylic dianhydride residues constituting the specific polyamic acid.

[0072] In order to obtain a polyimide that has even better transparency and can further suppress the generation of hydrogen fluoride during a high-temperature process, the specific polyamic acid preferably satisfies the following condition 1, more preferably satisfies the following condition 2, and even more preferably satisfies the following condition 3. Furthermore, in order to obtain a polyimide that has even better transparency while reducing internal stress and can further suppress the generation of hydrogen fluoride during a high-temperature process, the specific polyamic acid preferably satisfies the following condition 4, and more preferably satisfies the following condition 5. Condition 1: The content of the specific diamine residue is 80 mol % or more relative to the total amount (100 mol %) of diamine residues constituting the specific polyamic acid, and the content of NTCDA residues is 10 mol % or more relative to the total amount (100 mol %) of tetracarboxylic dianhydride residues constituting the specific polyamic acid. Condition 2: The above condition 1 is satisfied, and the specific polyamic acid has an SFDA residue. Condition 3: The above condition 2 is satisfied, and the content of SFDA residues is 10 mol % or more and 90 mol % or less based on the total amount (100 mol %) of tetracarboxylic dianhydride residues constituting the specific polyamic acid. Condition 4: The above condition 1 is satisfied, and the specific polyamic acid has a 4-BAAB residue. Requirement 5: The above requirement 4 is satisfied, and the content of 4-BAAB residues is 1 mol % or more and 20 mol % or less relative to the total amount (100 mol %) of diamine residues constituting the specific polyamic acid.

[0073] The specific polyamic acid can be synthesized by a known general method, for example, by reacting a diamine with a tetracarboxylic dianhydride in an organic solvent. An example of a specific method for synthesizing the specific polyamic acid will be described. First, a diamine is dissolved or dispersed in a slurry state in an organic solvent in an inert gas atmosphere such as argon or nitrogen to prepare a diamine solution. Then, the tetracarboxylic dianhydride is added to the diamine solution after being dissolved or dispersed in a slurry state in the organic solvent, or in a solid state.

[0074] When synthesizing a specific polyamic acid using a diamine and a tetracarboxylic dianhydride, the desired specific polyamic acid (a polymer of a diamine and a tetracarboxylic dianhydride) can be obtained by adjusting the molar amount of the diamine (or, if multiple diamines are used, the molar amount of each diamine) and the molar amount of the tetracarboxylic dianhydride (or, if multiple tetracarboxylic dianhydrides are used, the molar amount of each tetracarboxylic dianhydride). The molar fraction of each residue in the specific polyamic acid corresponds, for example, to the molar fraction of each monomer (each monomer corresponding to each residue) used in the synthesis of the specific polyamic acid. Furthermore, blending two types of polyamic acid can also produce a specific polyamic acid containing multiple tetracarboxylic dianhydride residues and multiple diamine residues. The temperature conditions for the reaction between the diamine and the tetracarboxylic dianhydride, i.e., the synthesis reaction of the specific polyamic acid, are not particularly limited, but are, for example, in the range of 20°C to 150°C. The reaction time for the synthesis reaction of the specific polyamic acid is, for example, in the range of 10 minutes to 30 hours.

[0075] The organic solvent used for synthesizing the specific polyamic acid is preferably a solvent capable of dissolving the tetracarboxylic dianhydride and diamine used, and more preferably a solvent capable of dissolving the specific polyamic acid to be produced. Examples of organic solvents used in the synthesis of the specific polyamic acid include urea-based solvents such as tetramethylurea and N,N-dimethylethylurea; sulfoxide-based solvents such as dimethyl sulfoxide; sulfone-based solvents such as diphenyl sulfone and tetramethyl sulfone; amide-based solvents such as N,N-dimethylacetamide (DMAC), N,N-dimethylformamide (DMF), N,N-diethylacetamide, N-methyl-2-pyrrolidone (NMP), 3-methoxy-N,N-dimethylpropanamide (MPA), and hexamethylphosphoric triamide; ester-based solvents such as γ-butyrolactone; alkyl halide-based solvents such as chloroform and methylene chloride; aromatic hydrocarbon-based solvents such as benzene and toluene; phenol-based solvents such as phenol and cresol; ketone-based solvents such as cyclopentanone; and ether-based solvents such as tetrahydrofuran, 1,3-dioxolane, 1,4-dioxane, dimethyl ether, diethyl ether, diethylene glycol diethyl ether, diethylene glycol dimethyl ether, and p-cresol methyl ether. These solvents are usually used alone, but two or more may be used in combination as needed. In order to increase the solubility and reactivity of the specific polyamic acid, the organic solvent used in the synthesis reaction of the specific polyamic acid is preferably one or more solvents selected from the group consisting of amide solvents, ketone solvents, ester solvents, and ether solvents, and more preferably an amide solvent (more specifically, DMF, DMAC, NMP, MPA, etc.). In addition, the synthesis reaction of the specific polyamic acid is preferably carried out under an inert gas atmosphere such as argon or nitrogen.

[0076] The weight-average molecular weight of the specific polyamic acid varies depending on its application, but is preferably in the range of 10,000 to 1,000,000, more preferably 20,000 to 500,000, and even more preferably 30,000 to 200,000. A weight-average molecular weight of 10,000 or more facilitates the formation of coating films or polyimide films from the specific polyamic acid or polyimides obtained using the specific polyamic acid. On the other hand, a weight-average molecular weight of 1,000,000 or less exhibits sufficient solubility in solvents, allowing the use of the polyamic acid composition described below to produce coating films or polyimide films with smooth surfaces and uniform thicknesses. The weight-average molecular weight used here refers to a polyethylene oxide equivalent value measured using gel permeation chromatography (GPC).

[0077] Methods for controlling the molecular weight of specific polyamic acids include using an excess of either the acid dianhydride or the diamine, or quenching the reaction by reacting with a monofunctional acid anhydride or amine, such as phthalic anhydride or aniline. When polymerizing with an excess of either the acid dianhydride or the diamine, a polyimide film with sufficient strength can be obtained if the molar ratio of the diamines used to synthesize the specific polyamic acid is between 0.95 and 1.05. The molar ratio is the ratio of the total amount of diamines used to synthesize the specific polyamic acid to the total amount of dianhydrides used to synthesize the specific polyamic acid (total amount of diamines / total amount of dianhydrides). Furthermore, end-capping with phthalic anhydride, maleic anhydride, aniline, or the like can further reduce the coloration of polyimides obtained using specific polyamic acids.

[0078] The polyamic acid composition according to the present embodiment contains a specific polyamic acid and an organic solvent. Examples of the organic solvent contained in the polyamic acid composition include those listed above as examples of organic solvents that can be used in the synthesis reaction of the specific polyamic acid. Preferred are one or more solvents selected from the group consisting of amide solvents, ketone solvents, ester solvents, and ether solvents, with amide solvents (more specifically, DMF, DMAC, NMP, MPA, etc.) being more preferred. When the specific polyamic acid is obtained by the above-described method, the reaction solution (post-reaction solution) itself may serve as the polyamic acid composition according to the present embodiment. Alternatively, the polyamic acid composition according to the present embodiment may be prepared by dissolving the solid specific polyamic acid obtained by removing the solvent from the reaction solution in an organic solvent. The content of the specific polyamic acid in the polyamic acid composition according to the present embodiment is not particularly limited, but is, for example, 1% by weight to 80% by weight based on the total weight of the polyamic acid composition.

[0079] The polyamic acid composition according to the present embodiment may further contain one or more compounds (hereinafter, sometimes referred to as "specific additives") selected from the group consisting of tertiary amines, phosphorus-containing compounds, and phenolic compounds. In this specification, the specific additive is a compound different from the polyamic acid and the solvent. When the polyamic acid composition according to the present embodiment contains the specific additive, sufficient molecular motion is imparted to the specific polyamic acid during imidization. As a result, the imidization of the specific polyamic acid proceeds rapidly, and depolymerization of the specific polyamic acid is suppressed, further suppressing the generation of outgassing (particularly hydrogen fluoride). To further enhance the molecular motion of the specific polyamic acid during imidization, the specific additive is preferably one or more compounds selected from the group consisting of tertiary amines and phosphorus-containing compounds.

[0080] In order to further increase the molecular mobility of the specific polyamic acid during imidization, the specific additive is preferably a compound having a molecular weight of 1500 or less. In order to further increase the molecular mobility of the specific polyamic acid during imidization, the specific additive is preferably a compound that dissolves in an organic solvent in the polyamic acid composition.

[0081] Furthermore, in order to further enhance the molecular mobility of the specific polyamic acid during imidization, the specific additive is preferably a compound having a boiling point of 150°C or higher, more preferably a compound having a boiling point of 200°C or higher, and even more preferably a compound having a boiling point of 250°C or higher. In order to further enhance the molecular mobility of the specific polyamic acid during imidization, the specific additive is preferably a compound that does not have a decomposition temperature within a temperature range below the boiling point. In order to further enhance the molecular mobility of the specific polyamic acid during imidization, it is preferable that the boiling point of the specific additive is higher than the boiling point of the organic solvent in the polyamic acid composition.

[0082] In order to further increase the molecular mobility of the specific polyamic acid during imidization while suppressing deterioration in the properties of the polyimide due to decomposition of the specific additive, the amount of the specific additive is preferably 0.001 parts by weight or more and 20 parts by weight or less, more preferably 0.01 parts by weight or more and 15 parts by weight or less, and even more preferably 0.1 parts by weight or more and 10 parts by weight or less, per 100 parts by weight of the specific polyamic acid.

[0083] The method for mixing the specific polyamic acid and the specific additive is not particularly limited, but from the viewpoint of ease of molecular weight control of the specific polyamic acid, it is preferable to add the specific additive to the specific polyamic acid after polymerization. At this time, the specific additive may be added to the specific polyamic acid as is, or the specific additive may be dissolved in a solvent in advance and this solution may be added to the specific polyamic acid; the addition method is not particularly limited. The specific additive may be added to a solution containing the specific polyamic acid after polymerization (post-reaction solution) to prepare the polyamic acid composition according to this embodiment.

[0084] The tertiary amine used as the specific additive coordinates with the carboxyl groups of the specific polyamic acid, and therefore also functions as an imidization accelerator (described later). By incorporating 0.001 parts by weight or more of the tertiary amine per 100 parts by weight of the specific polyamic acid, the strength and transparency of the resulting polyimide film can be increased while also reducing the CTE of the resulting polyimide film. Examples of tertiary amines include alkylamine compounds such as triethylamine, diisopropylamine, dibutylamine, and N,N-dimethylbutylamine; and heterocyclic compounds such as pyridine, 3,5-lutidine, and imidazole compounds.

[0085] In particular, since imidazole compounds are easily coordinated to the carboxyl groups of the specific polyamic acid, the use of an imidazole compound as a tertiary amine leads to more rapid imidization of the specific polyamic acid. This makes it difficult for organic solvents such as NMP to remain in the polyimide film during thermal imidization, and also suppresses decomposition of the specific polyamic acid, which is thought to improve the transparency of the resulting polyimide film.

[0086] In this specification, the term "imidazole compound" refers to a compound having a 1,3-diazole ring (1,3-diazole ring structure). The imidazole compound that can be added to the polyamic acid composition according to this embodiment is not particularly limited, and examples thereof include 1H-imidazole, 2-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-methylimidazole, and 1-benzyl-2-phenylimidazole. Of these, 2-phenylimidazole, 1,2-dimethylimidazole, 1-benzyl-2-methylimidazole, and 1-benzyl-2-phenylimidazole are preferred, and 2-phenylimidazole, 1,2-dimethylimidazole, and 1-benzyl-2-methylimidazole are more preferred.

[0087] Examples of the phosphorus-containing compound include compounds represented by the following general formulas (15-1) to (15-10): 5 , R 6 and R 7 each independently represents a hydrogen atom, a monovalent organic group, or a polyvalent organic group; R 8 represents a polyvalent organic group, and m represents the degree of polymerization.

[0088] [ka]

[0089] Preferred examples of phosphorus-containing compounds include phosphoric acid compounds, phosphorous acid compounds, phosphonic acid compounds, phosphinic acid compounds, phosphine compounds, phosphine oxide compounds, phosphorane compounds, and phosphazene compounds. The phosphorus-containing compounds may be esters of the above-listed compounds or condensates thereof, may contain a cyclic structure, or may form a salt with an amine or the like. Furthermore, some of these phosphorus-containing compounds are in a tautomeric relationship, such as phosphorous acid compounds and phosphonic acid compounds, and may exist in either state.

[0090] Specific examples of phosphoric acid compounds include trimethyl phosphate, triethyl phosphate, tributyl phosphate, tri(2-ethylhexyl) phosphate, tributoxyethyl phosphate, triphenyl phosphate, tricresyl phosphate, trixylenyl phosphate, tris(isopropylphenyl) phosphate, trinaphthyl phosphate, cresyl diphenyl phosphate, xylenyl diphenyl phosphate, diphenyl(2-ethylhexyl) phosphate, di(isopropylphenyl)phenyl phosphate, monoisodecyl phosphate, 2-acryloyloxyethyl acid phosphate, 2-methacryloyloxyethyl acid phosphate, diphenyl-2-acryloyloxyethyl phosphate, diphenyl-2-methacryloyloxyethyl phosphate, melamine phosphate, dimelamine phosphate, bisphenol A bis(diphenyl phosphate), and tris(β-chloropropyl) phosphate.

[0091] Specific examples of phosphorous compounds include triphenyl phosphite, trisnonylphenyl phosphite, tricresyl phosphite, triethyl phosphite, triisobutyl phosphite, tris(2-ethylhexyl) phosphite, tridecyl phosphite, trilauryl phosphite, tris(tridecyl) phosphite, diphenyl phosphite, diethyl phosphite, dibutyl phosphite, dimethyl phosphite, diphenyl mono(2-ethylhexyl) phosphite, diphenyl monodecyl phosphite, diphenyl mono(tridecyl) phosphite, trilauryl trithio phosphite, diethyl hydrogen phosphite, bis(2-ethylhexyl) phosphite, Hydrogen phosphite, dilauryl hydrogen phosphite, dioleyl hydrogen phosphite, diphenyl hydrogen phosphite, tetraphenyl dipropylene glycol diphosphite, bis(decyl)pentaerythritol diphosphite, bis(tridecyl)pentaerythritol diphosphite, tristearyl phosphite, distearyl pentaerythritol diphosphite, tris(2,4-di-tert-butylphenyl)phosphite, triisodecyl phosphite, 3,9-bis(2,6-di-tert-butyl-4-methylphenoxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane, and the like.

[0092] The condensate may be a condensed phosphate ester. Specific examples of the condensed phosphate ester include trialkyl polyphosphate, resorcinol polyphenyl phosphate, resorcinol poly(di-2,6-xylyl)phosphate, and hydroquinone poly(2,6-xylyl)phosphate. Commercially available condensed phosphate esters include "CR-733S" manufactured by Daihachi Chemical Industry Co., Ltd., "CR-741" manufactured by Daihachi Chemical Industry Co., Ltd., "PX-200" manufactured by Daihachi Chemical Industry Co., Ltd., and "FP-600" manufactured by ADEKA Corporation.

[0093] Specific examples of the phosphazene compound include phenoxycyclophosphazene ("FP-110" manufactured by Fushimi Pharmaceutical Co., Ltd.), cyclic cyanophenoxyphosphazene ("FP-300" manufactured by Fushimi Pharmaceutical Co., Ltd.), and the like.

[0094] Examples of phenolic compounds include hindered, semi-hindered, and less hindered types, and specific examples include dibutylhydroxytoluene, 1,3,5-tris(3,5-di-t-butyl-4-hydroxyphenylmethyl)-2,4,6-trimethylbenzene, and 2-t-butyl-4-methyl-6-(2-hydroxy-3-t-butyl-5-methylbenzyl)phenyl acrylate.

[0095] Phenolic compounds also function as primary antioxidants, capturing peroxy radicals and converting them to hydroperoxides, thereby inhibiting autoxidation of polymers. Therefore, phenolic compounds also function to inhibit discoloration due to polymer oxidation. Furthermore, by combining phenolic compounds with phosphites or other compounds that function as secondary antioxidants, converting hydroperoxides to stable alcohol compounds, discoloration of polyimides due to oxidation can be further inhibited. For example, discoloration of polyimides can be effectively inhibited by using phosphites in the range of 1 to 10 equivalents relative to the phenolic compound.

[0096] The polyamic acid composition according to this embodiment may also contain an imidization accelerator and / or a dehydration catalyst in order to shorten the heating time and to develop properties.

[0097] The imidization accelerator is not particularly limited, but a tertiary amine can be used. The tertiary amine is preferably a heterocyclic tertiary amine. Specific preferred examples of the heterocyclic tertiary amine include pyridine, picoline, quinoline, isoquinoline, and imidazole compounds. Specific preferred examples of the dehydration catalyst include acetic anhydride, propionic anhydride, n-butyric anhydride, benzoic anhydride, and trifluoroacetic anhydride.

[0098] The amount of imidization accelerator added is preferably 0.5 to 5.0 molar equivalents, more preferably 0.7 to 2.5 molar equivalents, and even more preferably 0.8 to 2.0 molar equivalents, relative to the amide groups of the specific polyamic acid. The amount of dehydration catalyst added is preferably 0.5 to 10.0 molar equivalents, more preferably 0.7 to 5.0 molar equivalents, and even more preferably 0.8 to 3.0 molar equivalents, relative to the amide groups of the specific polyamic acid. In this specification, "amide groups of the specific polyamic acid" refers to amide groups formed by the polymerization reaction of a diamine and a tetracarboxylic dianhydride. The imidization accelerator and / or dehydration catalyst may be added directly to the polyamic acid composition without dissolving them in an organic solvent, or they may be dissolved in an organic solvent before addition. If the imidization accelerator and / or dehydration catalyst are added directly without dissolving them in an organic solvent, the reaction may proceed too quickly before the imidization accelerator and / or dehydration catalyst can diffuse, resulting in the formation of a gel. Therefore, it is preferable to add a solution obtained by dissolving the imidization accelerator and / or dehydration catalyst in an organic solvent to the polyamic acid composition.

[0099] The polyamic acid composition according to this embodiment may contain various organic or inorganic low-molecular-weight compounds or polymeric compounds as additives other than the specific additives described above. Examples of additives other than the specific additives include plasticizers, antioxidants, dyes, surfactants, leveling agents, silicones, fine particles, and sensitizers. Examples of fine particles include organic fine particles made of polystyrene, polytetrafluoroethylene, and the like, and inorganic fine particles made of colloidal silica, carbon, layered silicates, and the like, which may have a porous or hollow structure. Furthermore, the function and form of the fine particles are not particularly limited, and they may be, for example, pigments, fillers, or fibrous particles.

[0100] To improve the heat resistance while maintaining the transparency of the resulting polyimide film, nanosilica particles may be used as the additive to composite the specific polyamic acid with the nanosilica particles. From the viewpoint of further enhancing the transparency of the polyimide film, the average primary particle diameter of the nanosilica particles is preferably 200 nm or less, more preferably 100 nm or less, even more preferably 50 nm or less, and may even be 30 nm or less. On the other hand, from the viewpoint of ensuring dispersibility in the specific polyamic acid, the average primary particle diameter of the nanosilica particles is preferably 5 nm or more, more preferably 10 nm or more. Methods for composite the specific polyamic acid with the nanosilica particles can be known, such as a method using an organosilica sol in which nanosilica particles are dispersed in an organic solvent. A method for composite the specific polyamic acid with the nanosilica particles using an organosilica sol may be used, such as synthesizing the specific polyamic acid and then mixing the synthesized specific polyamic acid with the organosilica sol. However, to more highly disperse the nanosilica particles in the specific polyamic acid, it is preferable to synthesize the specific polyamic acid in the organosilica sol.

[0101] Furthermore, to enhance the interaction with the specific polyamic acid, the nanosilica particles can be surface-treated with a surface treatment agent. Known surface treatment agents, such as silane coupling agents, can be used. Silane coupling agents include alkoxysilane compounds having functional groups such as amino groups or glycidyl groups, and these can be selected appropriately. To further enhance the interaction with the specific polyamic acid, amino group-containing alkoxysilanes are preferred. Examples of amino group-containing alkoxysilanes include 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropylmethyldimethoxysilane, 3-aminopropylmethyldiethoxysilane, 3-(2-aminoethyl)aminopropyltrimethoxysilane, 3-phenylaminopropyltrimethoxysilane, 2-aminophenyltrimethoxysilane, and 3-aminophenyltrimethoxysilane. However, from the viewpoint of raw material stability, 3-aminopropyltriethoxysilane is preferred. A surface treatment method for nanosilica particles includes stirring a mixture of a dispersion (organosilica sol) and a silane coupling agent at an ambient temperature of 20°C to 80°C. The stirring time is, for example, 1 hour to 10 hours. A catalyst or the like may be added to accelerate the reaction.

[0102] A nanosilica-polyamic acid composite obtained by combining a specific polyamic acid with nanosilica particles preferably contains 1 to 30 parts by weight, and more preferably 1 to 20 parts by weight, of nanosilica particles per 100 parts by weight of the specific polyamic acid. When the content of nanosilica particles is 1 part by weight or more, the heat resistance of the nanosilica particle-containing polyimide can be improved and internal stress can be sufficiently reduced, while when the content of nanosilica particles is 30 parts by weight or less, adverse effects on the mechanical properties and transparency of the nanosilica particle-containing polyimide can be suppressed.

[0103] The polyamic acid composition according to the present embodiment may contain a silane coupling agent to achieve appropriate adhesion to the support. Any known silane coupling agent may be used without particular limitation, but compounds containing an amino group are particularly preferred in terms of reactivity with the specific polyamic acid.

[0104] The blending ratio of the silane coupling agent to 100 parts by weight of the specific polyamic acid is preferably 0.01 to 0.50 parts by weight, more preferably 0.01 to 0.10 parts by weight, and even more preferably 0.01 to 0.05 parts by weight. By making the blending ratio of the silane coupling agent 0.01 parts by weight or more, the peeling suppression effect on the support is sufficiently exhibited, and by making the blending ratio of the silane coupling agent 0.50 parts by weight or less, the decrease in molecular weight of the specific polyamic acid is suppressed, and therefore embrittlement of the polyimide film can be suppressed.

[0105] The polyimide according to this embodiment is an imidized product of the specific polyamic acid described above. The polyimide according to this embodiment can be obtained by known methods, and its manufacturing method is not particularly limited. An example of a method for obtaining the polyimide according to this embodiment by imidizing the specific polyamic acid is described below. Imidization is performed by dehydration ring-closing the specific polyamic acid. This dehydration ring-closing can be performed by an azeotropic method using an azeotropic solvent, a thermal method, or a chemical method. Furthermore, the imidization of the specific polyamic acid to polyimide can be performed at any ratio of 1% to 100%. In other words, a partially imidized specific polyamic acid may be synthesized. In particular, when imidization is performed by heating, the ring-closing reaction from the specific polyamic acid to polyimide and the hydrolysis of the specific polyamic acid proceed simultaneously, which may result in a polyimide with a lower molecular weight than the specific polyamic acid. Therefore, from the perspective of improving mechanical properties, it is preferable to partially imidize the specific polyamic acid in the polyamic acid composition before forming the polyimide film described below. In this specification, partially imidized polyamic acid may also be referred to as "polyamic acid."

[0106] The dehydration ring closure of the specific polyamic acid can be carried out by heating the specific polyamic acid. The method for heating the specific polyamic acid is not particularly limited. For example, the polyamic acid composition according to the present embodiment described above can be applied to a support such as a glass substrate, a metal plate, or a PET (polyethylene terephthalate) film, followed by heat treatment of the specific polyamic acid at a temperature ranging from 40°C to 500°C. This method can produce a laminate according to the present embodiment, which has a support and a polyimide film (more specifically, a polyimide film containing an imidized product of the specific polyamic acid) disposed on the support. Alternatively, the dehydration ring closure of the specific polyamic acid can be carried out by placing the polyamic acid composition directly in a container that has been subjected to a release treatment, such as coating with a fluorine-based resin, and then heating and drying the polyamic acid composition under reduced pressure. Polyimides can be obtained by dehydration ring closure of the specific polyamic acid using these methods. The heating time for each of the above treatments varies depending on the amount of polyamic acid composition to be treated and the heating temperature, but it is generally preferable to set the heating time within the range of 1 minute to 300 minutes after the treatment temperature reaches the maximum temperature.

[0107] The polyimide film according to this embodiment (specifically, a polyimide film containing an imidized product of a specific polyamic acid) is colorless, transparent, and has a low yellowness and a glass transition temperature (heat resistance) that can withstand the TFT fabrication process, making it suitable as a transparent substrate material for flexible displays. The content of polyimide (specifically, an imidized product of a specific polyamic acid) in the polyimide film according to this embodiment is, for example, 70% by weight or more, preferably 80% by weight or more, more preferably 90% by weight or more, and may be 100% by weight, based on the total weight of the polyimide film. Examples of components other than polyimide in the polyimide film include the additives described above (more specifically, fine particles, etc.).

[0108] An electronic device according to this embodiment (more specifically, a flexible device, etc.) includes the polyimide film according to this embodiment and electronic elements disposed directly or indirectly on the polyimide film. When manufacturing an electronic device according to this embodiment for use in a flexible display, a polyimide film is first formed on an inorganic substrate such as glass as a support. Electronic elements such as TFTs are then disposed (formed) on the polyimide film to form an electronic device on the support. The TFT formation process is generally carried out over a wide temperature range of 150°C to 650°C, but to actually achieve the desired performance, an oxide semiconductor layer or a-Si layer is formed at 300°C or higher, and in some cases, the a-Si or other layer may be further crystallized using a laser or the like.

[0109] If the thermal decomposition temperature of the polyimide film is low, outgassing may occur during the formation of electronic devices. The outgassing may adhere to the oven interior as sublimate, causing contamination inside the oven and possibly peeling off inorganic films (such as the barrier film described below) and electronic devices formed on the polyimide film. Therefore, the 1% weight loss temperature of the polyimide is preferably 500°C or higher. The upper limit of the 1% weight loss temperature of the polyimide is preferably 600°C, although the higher the better. The 1% weight loss temperature can be adjusted, for example, by changing the content of residues with rigid structures (more specifically, NTCDA residues). More specifically, before TFT formation, an inorganic film such as a silicon oxide film (SiOx film) or a silicon nitride film (SiNx film) is formed on the polyimide film as a barrier film. If the polyimide has low heat resistance, if imidization is not complete, or if there is a large amount of residual solvent, volatile components such as polyimide decomposition gas may cause peeling between the polyimide and the inorganic film during the high-temperature process after lamination of the inorganic film. Therefore, it is desirable that the 1% weight loss temperature of the polyimide is 500°C or higher, and that the weight loss rate when the polyimide is isothermally maintained at a temperature in the range of 400°C to 450°C is less than 1%.

[0110] As described above, polyimides produced using specific polyamic acids can suppress the generation of hydrogen fluoride during high-temperature processes. The detection intensity ratio obtained from mass spectrometry can be used as an indicator of the amount of hydrogen fluoride gas generated when an imidized product of a specific polyamic acid (the polyimide according to this embodiment) is used in a high-temperature process. Specifically, a polyimide is first heated in a helium gas flow from an ambient temperature of 60°C to 500°C at a temperature increase rate of 10°C / min, and the gas generated from the polyimide is analyzed using a quadrupole mass spectrometer. The detected intensity of the m / z=20 peak (presumably due to hydrogen fluoride) at an ambient temperature of 450°C in the obtained mass spectrum is then calculated by dividing the detected intensity of the m / z=20 peak at an ambient temperature of 100°C by the detected intensity of the m / z=20 peak at an ambient temperature of 100°C. Hereinafter, the above "value obtained by dividing the detected intensity of the m / z=20 peak at an ambient temperature of 450°C by the detected intensity of the m / z=20 peak at an ambient temperature of 100°C" may be referred to as the HF intensity ratio. The HF intensity ratio tends to increase as the amount of hydrogen fluoride gas generated during the high-temperature process increases. The flow rate of helium gas used in the quadrupole mass spectrometer analysis may be set so that the gas generated from the polyimide can be analyzed in real time by the quadrupole mass spectrometer, and is, for example, in the range of 50 mL / min to 150 mL / min, preferably 80 mL / min to 120 mL / min.

[0111] In order to obtain a polyimide that can further suppress the generation of hydrogen fluoride during a high-temperature process, the HF intensity ratio is preferably 3.0 or less, and more preferably 2.5 or less. The lower limit of the HF intensity ratio is not particularly limited and may be 0.

[0112] Furthermore, if the glass transition temperature (Tg) of the polyimide is significantly lower than the process temperature, misalignment or the like may occur during the formation of electronic elements. Therefore, the Tg of the polyimide is preferably 300°C or higher, more preferably 350°C or higher, even more preferably 400°C or higher, and even more preferably 420°C or higher. The upper limit of the Tg of the polyimide is preferably as high as possible, for example, 470°C. Furthermore, since the thermal expansion coefficient of a glass substrate is generally smaller than that of a resin, internal stress occurs between the glass substrate and the polyimide film. If the internal stress of a laminate consisting of a glass substrate or electronic element used as a support and a polyimide film is high, the laminate containing the polyimide film will expand during the high-temperature TFT formation process and then shrink when cooled to room temperature, resulting in problems such as warping or breakage of the glass substrate and peeling of the polyimide film from the glass substrate. Therefore, in a laminate (laminate according to this embodiment) having a glass substrate (support) and a polyimide film, the internal stress between the polyimide film and the glass substrate is preferably 50 MPa or less, more preferably 45 MPa or less, even more preferably 40 MPa or less, even more preferably 35 MPa or less, and particularly preferably 30 MPa or less. The lower limit of the internal stress is the better. The method for measuring the internal stress is the same as or similar to the method described in the examples below.

[0113] The polyimide according to this embodiment can be suitably used as a material for display substrates such as TFT substrates and touch panel substrates. When using polyimide for the above applications, a method is often adopted in which an electronic device (specifically, an electronic device in which electronic elements are formed on a polyimide film) is formed on a support as described above, and then the polyimide film is peeled off from the support. In addition, alkali-free glass is suitably used as the material for the support. An example of a method for producing a laminate of a polyimide film and a support will be described in detail below.

[0114] First, the polyamic acid composition according to this embodiment is applied (cast) onto a support to form a coating film-containing laminate consisting of a coating film containing the specific polyamic acid and the support. Next, the coating film-containing laminate is heated, for example, at a temperature of 40°C to 200°C. The heating time is, for example, 3 minutes to 120 minutes. A multi-stage heating process may be performed, for example, by heating the coating film-containing laminate at 50°C for 30 minutes and then at 100°C for 30 minutes. Next, to promote imidization of the specific polyamic acid in the coating film, the coating film-containing laminate is heated, for example, at a maximum temperature of 200°C to 500°C. The heating time (heating time at the maximum temperature) is, for example, 1 minute to 300 minutes. It is preferable to gradually increase the temperature from a low temperature to the maximum temperature. The heating rate is preferably 2°C / min to 10°C / min, more preferably 4°C / min to 10°C / min. The maximum temperature is preferably in the range of 250°C or higher and 480°C or lower. If the maximum temperature is 250°C or higher, imidization proceeds sufficiently, while if the maximum temperature is 480°C or lower, thermal degradation of the polyimide can be suppressed. The reaction may be maintained at any temperature for any time until the maximum temperature is reached. The imidization reaction can be carried out in air, under reduced pressure, or in an inert gas such as nitrogen. To achieve higher transparency, however, it is preferable to carry out the reaction under reduced pressure or in an inert gas such as nitrogen. Known heating devices such as hot air ovens, infrared ovens, vacuum ovens, inert ovens, and hot plates can be used. Through these steps, the specific polyamic acid in the coating film is imidized, and a laminate (i.e., the laminate according to this embodiment) of the support and the polyimide film (a film containing an imidized product of the specific polyamic acid) can be obtained.

[0115] The polyimide film can be peeled from the resulting laminate of the support and the polyimide film by known methods. For example, the film may be peeled by hand, or by using a mechanical device such as a drive roll or a robot. Furthermore, a method of providing a peeling layer between the support and the polyimide film, or a method of forming a silicon oxide film on a substrate having a large number of grooves, forming a polyimide film using the silicon oxide film as an underlayer, and then peeling the polyimide film by infiltrating a silicon oxide etchant between the substrate and the silicon oxide film can also be employed. Another method of separating the polyimide film by irradiation with laser light can also be employed.

[0116] The transparency of a polyimide film can be evaluated by its total light transmittance (TT) according to JIS K7361-1:1997 and its haze according to JIS K7136-2000. When a polyimide film is used in an application requiring high transparency, the total light transmittance of the polyimide film is preferably 75% or more, more preferably 80% or more. When a polyimide film is used in an application requiring high transparency, the haze of the polyimide film is preferably 1.5% or less, more preferably 1.2% or less, even more preferably 1.0% or less, even more preferably 0.8% or less, and may even be 0%. In applications requiring high transparency, the polyimide film is required to have high transmittance across the entire wavelength range, but polyimide films tend to absorb light at short wavelengths, often resulting in yellow coloration of the film itself. To use a polyimide film in an application requiring high transparency, it is preferable that the coloration of the polyimide film be reduced. Specifically, in order to use a polyimide film in an application requiring high transparency, the yellowness index (YI) of the polyimide film is preferably 20 or less, more preferably 15 or less, and may be 0. YI can be measured in accordance with JIS K7373-2006. A polyimide film having reduced coloration and transparency is thus suitable for transparent substrates such as glass replacement substrates, and substrates having a sensor or camera module provided on the back surface.

[0117] Furthermore, in applications requiring transparency, from the viewpoint of color reproducibility, etc., high transmittance is required, particularly for blue light (light with a wavelength of around 470 nm), and practically, high transmittance for light with a wavelength of 400 nm (400 nm transmittance) is required. From the viewpoint of color reproducibility, etc., the 400 nm transmittance of the polyimide film is preferably 30% or more, more preferably 40% or more, even more preferably 50% or more, and even more preferably 60% or more. The upper limit of the 400 nm transmittance of the polyimide film is not particularly limited and may be 100%.

[0118] Furthermore, there are two types of light extraction methods for flexible displays: a top-emission method in which light is extracted from the front side of the TFT, and a bottom-emission method in which light is extracted from the back side of the TFT. The top-emission method is characterized by its ease of increasing the aperture ratio because light is not blocked by the TFT, resulting in high-definition image quality. The bottom-emission method is characterized by its ease of manufacturing, as it simplifies the alignment of the TFT and pixel electrode. Since the aperture ratio can be improved even in the bottom-emission method if the TFT is transparent, the bottom-emission method, which is easy to manufacture, tends to be adopted for large displays. The polyimide film according to this embodiment has a low YI and excellent heat resistance, making it applicable to both of the above light extraction methods.

[0119] Furthermore, in a batch-type device production process in which a polyamic acid composition is applied to a support such as a glass substrate, heated to imidize, and then electronic elements or the like are formed, followed by peeling off the polyimide film, excellent adhesion between the support and the polyimide film is preferred. Here, adhesion refers to adhesion strength. In this production process in which electronic elements or the like are formed on the polyimide film on the support, and then the polyimide film on which the electronic elements or the like are formed is peeled off from the support, excellent adhesion between the polyimide film and the support allows for more accurate formation or mounting of electronic elements or the like. In a production process in which electronic elements or the like are arranged on a support via a polyimide film, the higher the peel strength between the support and the polyimide film, the better, from the viewpoint of improving productivity. Specifically, the peel strength is preferably 0.05 N / cm or more, and more preferably 0.1 N / cm or more.

[0120] In the manufacturing process described above, when peeling a polyimide film from a laminate of a support and a polyimide film, the polyimide film is often peeled from the support by laser irradiation. In this case, since the polyimide film needs to absorb the laser light, the cutoff wavelength of the polyimide film is required to be longer than the wavelength of the laser light used for peeling. Since a XeCl excimer laser with a wavelength of 308 nm is often used for laser peeling, the cutoff wavelength of the polyimide film is preferably 312 nm or longer, and more preferably 330 nm or longer. On the other hand, since a longer cutoff wavelength tends to cause the polyimide film to turn yellow, the cutoff wavelength of the polyimide film is preferably 390 nm or shorter. From the viewpoint of achieving both transparency (low yellowness) and ease of laser peeling, the cutoff wavelength of the polyimide film is preferably 320 nm or longer to 390 nm or shorter, and more preferably 330 nm or longer to 390 nm or shorter. In this specification, the cutoff wavelength means a wavelength at which the transmittance is 0.1% or less as measured by an ultraviolet-visible spectrophotometer.

[0121] The polyamic acid composition and polyimide according to the present embodiment may be used as they are in coating or molding processes for producing products or components, or may be used as materials for further coating or other treatments on molded articles formed into films. For use in coating or molding processes, the polyamic acid composition or polyimide may be dissolved or dispersed in an organic solvent as needed, and further blended with a photocurable component, a thermosetting component, a non-polymerizable binder resin, and other components as needed to prepare a composition containing the specific polyamic acid or polyimide.

[0122] On the surface of the polyimide film according to this embodiment, various inorganic thin films such as metal oxide thin films, transparent electrodes, etc. The method for forming these inorganic thin films is not particularly limited, and examples thereof include PVD methods such as sputtering, vacuum deposition, and ion plating, and CVD methods.

[0123] The polyimide film according to the present embodiment is heat-resistant, has low thermal expansion, and is transparent. Furthermore, it generates little internal stress when laminated with a glass substrate, ensuring good adhesion to inorganic materials during high-temperature processes. Therefore, it is preferable for use in fields and products where these properties are valuable. For example, the polyimide film according to the present embodiment is preferably used in image display devices such as liquid crystal displays, organic electroluminescence (EL) displays, and electronic paper, as well as printed materials, color filters, flexible displays, optical films, 3D displays, touch panels, transparent conductive film substrates, solar cells, and more preferably as a replacement material for glass. In these applications, the thickness of the polyimide film is, for example, 1 μm to 200 μm, preferably 5 μm to 100 μm. The thickness of the polyimide film can be measured using a laser hologram.

[0124] The polyamic acid composition according to this embodiment can be suitably used in a method for producing a polyimide film, which involves applying the polyamic acid composition to a support, heating it to imidize it, and then peeling the polyimide film from the support. The polyamic acid composition according to this embodiment can also be suitably used in a batch-type device production process, which involves applying the polyamic acid composition to a support, heating it to imidize it, forming electronic elements or the like on the formed polyimide film, and then peeling the polyimide film with the electronic elements or the like formed on it from the support. Therefore, this embodiment also includes a method for producing an electronic device, which includes the steps of applying the polyamic acid composition to a support, heating it to imidize it, and then forming electronic elements or the like on the polyimide film formed on the support. Such an electronic device production method may further include the step of peeling the polyimide film with the electronic elements or the like formed on it from the support. [Example]

[0125] Examples of the present invention will be described below, but the scope of the present invention is not limited to the following examples.

[0126] <Methods for measuring physical properties> First, the method for measuring the physical properties of polyimide (polyimide film) will be described.

[0127] [Yellowness (YI)] The polyimide film in each laminate obtained in the Examples and Comparative Examples described below was measured for transmittance of light with a wavelength of 200 nm or more and 800 nm or less using an ultraviolet-visible-near-infrared spectrophotometer ("V-650" manufactured by JASCO Corporation), and the yellowness index (YI) of the polyimide film was calculated using the formula described in JIS K7373-2006. When the YI was 15 or less, the film was evaluated as having "excellent transparency." On the other hand, when the YI was greater than 15, the film was evaluated as having "poor transparency."

[0128] [400nm transmittance] The polyimide film in each laminate obtained in the examples and comparative examples described below was measured for transmittance at a wavelength of 400 nm (400 nm transmittance) using an ultraviolet-visible-near-infrared spectrophotometer ("V-650" manufactured by JASCO Corporation).

[0129] Internal Stress Each polyamic acid composition prepared in the following Examples and Comparative Examples was spin-coated onto a Corning glass substrate (material: alkali-free glass, thickness: 0.7 mm, size: 100 mm x 100 mm) whose warpage had been measured in advance. The substrate was then heated in air at 120°C for 30 minutes and then in a nitrogen atmosphere at 430°C for 30 minutes to obtain a laminate with a 10 μm-thick polyimide film on the glass substrate. To eliminate the influence of water absorption by the polyimide film, the laminate was dried at 120°C for 10 minutes, and the warpage of the laminate was measured at 25°C in a nitrogen atmosphere using a thin film stress analyzer (KLA-Tencor Corporation, "FLX-2320-S"). The internal stress generated between the glass substrate and the polyimide film was calculated using the Stoney equation from the warpage of the glass substrate before the polyimide film formation and the warpage of the laminate.

[0130] [Analysis of gas evolved from polyimide film] The gas generated from the polyimide film during heating was analyzed using an analytical device combining a thermogravimetric analyzer (NETZSCH "STA449 F5") and a quadrupole mass spectrometer (JEOL "JMS-Q1500GC"). The analytical procedure is described below.

[0131] First, using octafluoronaphthalene as a standard substance, the voltage of the quadrupole mass spectrometer was adjusted so that the detection intensity of the peak at m / z=69 was 800,000. Next, using the thermogravimetric analyzer, each polyimide film obtained in the following Examples and Comparative Examples (specifically, each polyimide film sampled from each laminate so as to have a mass of 140 mg) was heated from an ambient temperature of 60°C to 500°C at a heating rate of 10°C / min under a helium gas flow at a flow rate of 100 mL / min. The gas evolved from the polyimide during heating was analyzed with the quadrupole mass spectrometer to obtain a mass spectrum. The HF intensity ratio was calculated from the obtained mass spectrum. Note that by using the analyzer to heat the polyimide film under a helium gas flow, the helium gas served as a carrier gas, allowing the gas evolved from the polyimide film to be analyzed in real time with the quadrupole mass spectrometer.

[0132] When the HF intensity ratio was 3.0 or less, it was evaluated as "the generation of hydrogen fluoride was suppressed during high-temperature processes." On the other hand, when the HF intensity ratio was over 3.0, it was evaluated as "the generation of hydrogen fluoride was not suppressed during high-temperature processes."

[0133] <Preparation of polyimide film> The methods for producing polyimide films (laminates) in Examples and Comparative Examples are described below. In the following, compounds and reagents are abbreviated as follows. Furthermore, the preparation of polyamic acid compositions used for producing polyimide films was carried out in a nitrogen atmosphere. NMP: N-methyl-2-pyrrolidone PMDA: Pyromellitic dianhydride ODPA: 4,4'-oxydiphthalic anhydride BPAF: 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride SFDA: spiro[11H-difuro[3,4-b:3',4'-i]xanthene-11,9'-[9H]fluorene]-1,3,7,9-tetrone s-BPDA: 3,3',4,4'-biphenyltetracarboxylic dianhydride NTCDA: 2,3,6,7-naphthalenetetracarboxylic dianhydride TFMOB: 2,2'-bis(trifluoromethoxy)benzidine 4-BAAB: 4-aminophenyl-4-aminobenzoate TFMB: 2,2'-bis(trifluoromethyl)benzidine 2PhI: 2-phenylimidazole

[0134] [Example 1] A 300 mL glass separable flask equipped with a stainless steel stirrer and a nitrogen inlet tube was charged with 80.0 g of NMP as the polymerization organic solvent. Next, while stirring the contents of the flask, 10.04 g of TFMOB was added to the flask and dissolved. Next, 1.14 g of NTCDA, 4.67 g of SFDA, and 4.15 g of s-BPDA were added to the flask, and the contents were stirred for 24 hours at 25°C to obtain a polyamic acid composition. The resulting polyamic acid composition was applied to a glass substrate (manufactured by Corning Incorporated, material: alkali-free glass, thickness: 0.7 mm, size: 100 mm x 100 mm) using a spin coater. After heating at 80°C for 30 minutes in air, the substrate was heated from 80°C to 180°C at a heating rate of 6°C / min under a nitrogen atmosphere. Subsequently, the substrate was heated at 180°C for 30 minutes in a nitrogen atmosphere, and then the temperature was increased from 180°C to 250°C at a rate of 6°C / min. Subsequently, the substrate was heated at 250°C for 30 minutes in a nitrogen atmosphere, and then the temperature was increased from 250°C to 450°C at a rate of 6°C / min. Subsequently, the substrate was heated at 450°C for 10 minutes in a nitrogen atmosphere, to obtain a laminate (laminate of Example 1) comprising a 10 μm-thick polyimide film on a glass substrate.

[0135] [Examples 3 to 5, Example 8, Example 11, Comparative Example 1 and Comparative Example 2] The laminates of Examples 3 to 5, 8, 11, Comparative Examples 1 and 2 were obtained in the same manner as in Example 1, except that the acid dianhydrides used and their charging ratios, the diamines used and their charging ratios, and the thicknesses of the polyimide films were as shown in Table 1. In all of Examples 3 to 5, 8, 11, Comparative Examples 1 and 2, the total amount of acid dianhydrides used in preparing the polyamic acid compositions was the same as in Example 1.

[0136] [Examples 2, 6, 7, 9, 12 and 17] The laminates of Examples 2, 6, 7, 9, 12, and 17 were obtained in the same manner as in Example 1, except that the acid dianhydrides used and their charging ratios and the diamines used and their charging ratios were as shown in Table 1, that the contents of the flask were stirred for 24 hours and then 2PhI was added to the contents of the flask in the amount shown in Table 1 to obtain polyamic acid compositions, and that the thicknesses of the polyimide films were as shown in Table 1. In all of Examples 2, 6, 7, 9, 12, and 17, the total amount of acid dianhydrides used in preparing the polyamic acid compositions was the same as in Example 1.

[0137] [Example 10] A 300 mL separable glass flask equipped with a stainless steel stirrer and a nitrogen inlet tube was charged with 80.0 g of NMP as the polymerization organic solvent. Next, 6.50 g of TFMOB was added and dissolved while stirring the contents of the flask. Next, 1.93 g of NTCDA and 2.97 g of s-BPDA were added to the contents of the flask, and the contents of the flask were stirred for 1 hour under an atmosphere at 25°C. Next, 3.61 g of TFMOB was added and dissolved, followed by the addition of 4.09 g of SFDA and 0.89 g of ODPA, in that order, and the contents of the flask were stirred for 24 hours under an atmosphere at 25°C. Next, 2PhI was added to the contents of the flask in the amount shown in Table 1 to obtain a polyamic acid composition. A 10 μm-thick polyimide film was formed on a glass substrate using the same method as in Example 1 described above, except that the resulting polyamic acid composition was used, yielding the laminate of Example 10.

[0138] [Examples 13, 15 and 16] The laminates of Examples 13, 15, and 16 were obtained in the same manner as in Example 10, except that the acid dianhydrides used and their charging ratios, and the diamines used and their charging ratios were as shown in Table 1. PMDA was added to the flask after the addition of NTCDA and before the addition of s-BPDA. 4-BAAB was added to the flask after the second addition of TFMOB and before the addition of SFDA. The total amount of acid dianhydrides used in preparing the polyamic acid compositions of Examples 13, 15, and 16 was the same as in Example 10.

[0139] [Example 14] The laminate of Example 14 was obtained in the same manner as in Example 10, except that the acid dianhydrides used and their charging ratios, and the diamines used and their charging ratios were as shown in Table 1, and that 2PhI was not used. The timing for adding PMDA to the flask was after the addition of NTCDA and before the addition of s-BPDA. The total amount of acid dianhydrides used in preparing the polyamic acid composition of Example 14 was the same as in Example 10.

[0140] Table 1 shows the acid dianhydrides used and their charging ratios, the diamines used and their charging ratios, the amount of 2PhI, and the thickness of the polyimide film for Examples 1 to 17 and Comparative Examples 1 and 2. In Table 1, "-" indicates that the corresponding component was not used. In Table 1, the values ​​in the "Acid Dianhydride" column indicate the content (unit: mol%) of each acid dianhydride relative to the total amount (100 mol%) of acid dianhydrides used. In Table 1, the values ​​in the "Diamine" column indicate the content (unit: mol%) of each diamine relative to the total amount (100 mol%) of acid dianhydrides used. In Table 1, the values ​​in the "Amount of 2PhI" column indicate the amount (unit: parts by weight) of 2PhI used relative to 100 parts by weight of polyamic acid. Furthermore, in all of Examples 1 to 17 and Comparative Examples 1 and 2, the molar fraction of each polyamic acid residue in the prepared polyamic acid composition was consistent with the molar fraction of each monomer (each monomer corresponding to each residue) used in the synthesis of the polyamic acid.

[0141] Furthermore, Table 2 shows the internal stress, 400 nm transmittance, YI, and HF intensity ratio for Examples 1 to 17 and Comparative Examples 1 and 2. In Table 2, "-" means that no measurement was performed.

[0142] [Table 1]

[0143] [Table 2]

[0144] As shown in Table 1, the polyamic acids in the polyamic acid compositions prepared in Examples 1 to 17 had a specific diamine residue (TFMOB residue) and an NTCDA residue.

[0145] As shown in Table 2, the HF intensity ratio was 3.0 or less in Examples 1 to 17. Therefore, the polyimide films obtained in Examples 1 to 17 were able to suppress the generation of hydrogen fluoride during high-temperature processes. Furthermore, as shown in Table 2, the YI was 15 or less in Examples 1 to 17. Therefore, the polyimide films obtained in Examples 1 to 17 were excellent in transparency.

[0146] As shown in Table 1, the polyamic acid in the polyamic acid compositions prepared in Comparative Examples 1 and 2 did not contain a specific diamine residue. Also, as shown in Table 1, the polyamic acid in the polyamic acid composition prepared in Comparative Example 1 did not contain an NTCDA residue.

[0147] As shown in Table 2, the HF intensity ratios exceeded 3.0 in Comparative Examples 1 and 2. Therefore, the polyimide films obtained in Comparative Examples 1 and 2 were unable to suppress the generation of hydrogen fluoride during the high-temperature process. Furthermore, as shown in Table 2, the YI exceeded 15 in Comparative Example 1. Therefore, the polyimide film obtained in Comparative Example 1 did not have excellent transparency.

[0148] The above results demonstrate that the polyimide obtained from the polyamic acid composition according to the present invention has excellent transparency and can suppress the generation of hydrogen fluoride during high-temperature processes.

Claims

1. A polyamic acid having a tetracarboxylic dianhydride residue and a diamine residue, The diamine residue contains a divalent organic group represented by the following general formula (1): The tetracarboxylic dianhydride residue of the polyamic acid contains a tetravalent organic group represented by the following chemical formula (12): 【Chemistry 1】 (In the general formula (1), R １ and R ２ each independently represents a trifluoromethoxy group, a pentafluoroethoxy group, or a heptafluoropropoxy group; a represents an integer of 1 or more and 4 or less; b represents an integer of 0 or more and 4 or less; when a represents an integer of 2 or more and 4 or less, a plurality of R １ may be the same or different, and when b represents an integer of 2 or more and 4 or less, a plurality of R ２ may be the same or different, and n represents an integer of 0 to 3.

2. The polyamic acid according to claim 1, wherein the tetracarboxylic dianhydride residue further comprises one or more selected from the group consisting of a tetravalent organic group represented by the following chemical formula (2), a tetravalent organic group represented by the following chemical formula (3), a tetravalent organic group represented by the following chemical formula (4), a tetravalent organic group represented by the following chemical formula (5), a tetravalent organic group represented by the following chemical formula (6), a tetravalent organic group represented by the following chemical formula (7), a tetravalent organic group represented by the following chemical formula (8), a tetravalent organic group represented by the following chemical formula (9), and a tetravalent organic group represented by the following chemical formula (10). 【Chemistry 2】

3. 3. The polyamic acid according to claim 2, wherein the tetracarboxylic dianhydride residue further comprises at least one selected from the group consisting of a tetravalent organic group represented by the following chemical formula (11) and a tetravalent organic group represented by the following chemical formula (13): 【Transformation 3】

4. A polyamic acid composition comprising the polyamic acid according to claim 1 and an organic solvent.

5. The polyamic acid composition according to claim 4, further comprising one or more compounds selected from the group consisting of tertiary amines, phosphorus-containing compounds, and phenolic compounds.

6. 6. The polyamic acid composition according to claim 5, wherein the amount of the one or more compounds selected from the group consisting of tertiary amines, phosphorus-containing compounds, and phenolic compounds is 0.001 parts by weight or more and 20 parts by weight or less per 100 parts by weight of the polyamic acid.

7. A polyimide which is an imidized product of the polyamic acid according to claim 1.

8. 8. The polyimide according to claim 7, wherein the polyimide is heated in a helium gas flow from an ambient temperature of 60°C to 500°C at a heating rate of 10°C / min, and the gas generated from the polyimide is analyzed with a quadrupole mass spectrometer to obtain a mass spectrum, in which the detected intensity of the peak at m / z = 20 at an ambient temperature of 450°C divided by the detected intensity of the peak at m / z = 20 at an ambient temperature of 100°C is 3.0 or less.

9. A polyimide film comprising the polyimide according to claim 7.

10. 10. The polyimide film according to claim 9, which has a transmittance of 30% or more for light with a wavelength of 400 nm.

11. 10. The polyimide film according to claim 9, having a haze of 1.0% or less.

12. A laminate comprising a support and the polyimide film according to claim 9.

13. A method for producing a laminate having a support and a polyimide film, comprising the steps of: A method for producing a laminate, comprising applying the polyamic acid composition according to claim 4 onto a support to form a coating film containing the polyamic acid, and heating the coating film to imidize the polyamic acid.

14. An electronic device comprising the polyimide film according to claim 9 and an electronic element disposed on the polyimide film.

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