Polyimide precursor composition, polyimide film, polyimide film / substrate laminate, flexible electronic device, and flexible electronic device substrate

Abstract

There is provided a polyimide precursor composition comprising: a polyimide precursor that contains a repeating unit represented by formula (1) and satisfies a specific condition (such as a condition that 50 mol% or more of the total amount of X1 present in the polyimide precursor is a specific tetravalent aromatic group); an alkoxysilane; and an imidazole compound. [In formula (1), X1 is a tetravalent aromatic group or the like; Y1 is a divalent aromatic group or the like; and R1 and R2 are each independently a hydrogen atom or the like].

Description

Polyimide precursor compositions, polyimide films, polyimide film / substrate laminates, flexible electronic devices, and flexible electronic device substrates.

[0001] The present invention relates to a polyimide precursor composition, a polyimide film, a polyimide film / substrate laminate, a flexible electronic device, and a flexible electronic device substrate.

[0002] Polyimide films have been widely used in fields such as electrical and electronic devices and semiconductors due to their excellent heat resistance, chemical resistance, mechanical strength, electrical properties, and dimensional stability. In recent years, the use of polyimide films as plastic substrates to replace glass substrates has been explored, particularly in the field of display devices (such as liquid crystal displays and organic EL displays). Research is underway on various types of polyimide precursor compositions (varnishes, etc.) to efficiently manufacture polyimide films for various applications.

[0003] For example, International Publication No. 2024 / 024901 (Patent Document 1) discloses a polyimide precursor composition containing a polyimide precursor represented by a specific repeating unit and an imidazole compound in an amount of less than 1 mole per mole of the repeating unit of the polyimide precursor.

[0004] International Publication No. 2024 / 024901

[0005] The polyimide precursor composition described in Patent Document 1 above was capable of imparting high levels of transparency and high heat resistance to the polyimide film obtained using it. However, in the field of polyimide films, from the viewpoint of exhibiting properties according to the application, there is a desire for the emergence of new polyimide precursor compositions that can efficiently produce polyimide films with high levels of transparency and even higher levels of heat resistance.

[0006] The present invention has been made in view of the problems of the prior art described above, and aims to provide a polyimide precursor composition that enables the production of a polyimide film having a high level of transparency and a higher level of heat resistance. Furthermore, the present invention aims to provide a polyimide film obtained using the polyimide precursor composition, as well as a polyimide film / substrate laminate, a flexible electronic device, and a flexible electronic device substrate using the polyimide film.

[0007] As a result of diligent research to achieve the above objective, the present inventors have found that by providing a polyimide precursor composition containing repeating units represented by the following formula (1) and satisfying the following conditions (i) and (ii); an alkoxysilane; and an imidazole compound, it is possible to produce a polyimide film with a high level of transparency and a higher level of heat resistance when using this composition to manufacture a polyimide film, thus completing the present invention.

[0008] In other words, the present invention provides the following embodiments.

[0009] [1] A polyimide precursor composition comprising a polyimide precursor containing repeating units represented by the following formula (1) and satisfying the following (i) and (ii), an alkoxysilane, and an imidazole compound.

[0010]

[0011] [In formula (1), X １ Y is a tetravalent aliphatic group or a tetravalent aromatic group. １ R is a divalent aliphatic group or a divalent aromatic group. １ and R ２ Each of these is independently a hydrogen atom, a C1-C6 alkyl group, or a C3-C9 alkylsilyl group. ] (i) X present in the polyimide precursor １ At least 50 mol% of the total amount consists of tetravalent aromatic groups represented by the following formula (1-1).

[0012]

[0013] (ii) 50 mol% or more of the total amount of Y present in the polyimide precursor １ is a p-phenylene group.

[0014] [2] 1 to 30 mol% of the total amount of X present in the polyimide precursor １ is a tetravalent aromatic group represented by the following formula (1-2), the polyimide precursor composition according to [1].

[0015]

[0016] [In formula (1-2), R １０ and R １１ are each independently a single bond or a divalent organic group.].

[0017] [3] 1 to 30 mol% of the total amount of Y present in the polyimide precursor １ is a divalent aromatic group represented by the following formula (1-3), the polyimide precursor composition according to [1] or [2].

[0018]

[0019] [In formula (1-3), R １２ and R １３ are each independently a single bond or a divalent organic group.].

[0020] [4] The polyimide precursor composition according to any one of [1] to [3], wherein the alkoxysilane is an aryltrialkoxysilane.

[0021] [5] The content of the alkoxysilane is 5 to 150 parts by mass when the mass of the polyimide precursor in terms of polyimide is 100 parts by mass, the polyimide precursor composition according to any one of [1] to [4] (here, the "mass of the polyimide precursor in terms of polyimide" means the mass of the polyimide obtained when polyimide is produced from the polyimide precursor (total amount) in the composition by completely imidizing all the repeating units in the polyimide precursor contained in the composition (the total mass of the polyimide obtained when all the polyimide precursors contained in the composition are completely cyclized and imidized).).

[0022] A polyimide film obtained from the polyimide precursor composition described in any one of items [6], [1], to [5].

[0023] A polyimide film / substrate laminate comprising the polyimide film described in [7] and [6] and a substrate.

[0024] A flexible electronic device comprising the polyimide film described in [8] and [6].

[0025] A flexible electronic device substrate comprising the polyimide film described in [9] and [6].

[0026]

[10] A polyimide film obtained from a polyimide precursor composition containing a repeating unit represented by the following formula (1) and a polyimide precursor satisfying the following (i) and (ii), wherein the silicon content in the polyimide film is 2.0 parts by mass or more per 100 parts by mass of the polyimide film, and the 0.5% weight loss temperature is 535°C or higher.

[0027]

[0028] [In formula (1), X １ Y is a tetravalent aliphatic group or a tetravalent aromatic group. １ R is a divalent aliphatic group or a divalent aromatic group. １ and R ２ Each of these is independently a hydrogen atom, a C1-C6 alkyl group, or a C3-C9 alkylsilyl group. ] (i) X present in the polyimide precursor １ At least 50 mol% of the total amount consists of tetravalent aromatic groups represented by the following formula (1-1).

[0029]

[0030] (ii) Y present in the polyimide precursor １ More than 50 mol% of the total amount consists of p-phenylene groups.

[0031] According to the present invention, it is possible to provide a polyimide precursor composition that enables the production of a polyimide film having a high level of transparency and a higher level of heat resistance. Furthermore, it is possible to provide a polyimide film obtained using the polyimide precursor composition, as well as a polyimide film / substrate laminate, a flexible electronic device, and a flexible electronic device substrate using the polyimide film.

[0032] The present invention will be described in detail below with reference to its preferred embodiments.

[0033] <Polyimide Precursor Composition> The polyimide precursor composition of the present invention contains a polyimide precursor that contains a repeating unit represented by the above formula (1) and satisfies (i) and (ii) above; an alkoxysilane; and an imidazole compound. Hereinafter, the polyimide precursor, the alkoxysilane, and the imidazole compound will be described separately.

[0034] <Polyimide Precursor> The polyimide precursor to be contained in the polyimide precursor composition of the present invention is a repeating unit represented by the following formula (1) (wherein the following formula (1), X １ is a tetravalent aliphatic group or a tetravalent aromatic group, Y １ R is a divalent aliphatic group or a divalent aromatic group. １ and R ２ Each of these is independently a hydrogen atom, a C1-C6 alkyl group, or a C3-C9 alkylsilyl group. The polyimide precursor contains and satisfies the above conditions (i) and (ii). Below, regarding the polyimide precursor, first, the repeating unit represented by formula (1) that the polyimide precursor has as an essential repeating unit will be described, and then each condition will be described.

[0035]

[0036] (Regarding the repeating unit represented by equation (1)) X in equation (1) １ X is a tetravalent aliphatic group or a tetravalent aromatic group. In the present invention, X present in the polyimide precursor １50 mol% or more of the total amount (X contained in the precursor) １ Since 50 mol% or more of the total amount of the structure (group) represented by the above formula (1-1) is a tetravalent aromatic group, X in the precursor １ This will always include a tetravalent aromatic group represented by the above formula (1-1). Here, first, including the tetravalent aromatic group represented by the above formula (1-1), X in formula (1) １ This section describes the bases that can be selected as such.

[0037] X in equation (1) above １ X is a tetravalent aliphatic group or a tetravalent aromatic group. １ The structure is derived from the tetracarboxylic acid component, which is a monomer component used in the production of polyimide precursors (organic group). The "tetracarboxylic acid component" referred to here is a component that can be used as a raw material monomer when producing polyimide and is also present in the polyimide precursor X １ Any compound that can incorporate a tetravalent aliphatic group or a tetravalent aromatic group is acceptable, and the concept includes tetracarboxylic acids, tetracarboxylic dianhydrides, and other tetracarboxylic acid derivatives such as tetracarboxylic silyl esters, tetracarboxylic acid esters, and tetracarboxylic acid chlorides. The tetracarboxylic acid component is not particularly limited, but since it is convenient to use tetracarboxylic dianhydrides in the production of polyimide precursors, the following explanation will mainly focus on the case where tetracarboxylic dianhydrides are used as the tetracarboxylic acid component. For convenience, tetracarboxylic acids may also be used as examples of compounds that can be used as the tetracarboxylic acid component.

[0038] Such X １As the tetravalent aliphatic group that can be selected, residues obtained by removing two acid anhydride groups from known aliphatic tetracarboxylic dianhydrides usable in the production of polyimides (synonymous with residues obtained by removing four carboxylic acid groups from an aliphatic tetracarboxylic acid) can be suitably used. Such aliphatic tetracarboxylic acids and aliphatic tetracarboxylic dianhydrides are not particularly limited, and known ones can be used as appropriate. For example, tetracarboxylic acids (1,2,3,4-cyclobutanetetracarboxylic acid, isopropylidene diphenoxybisphthalic acid, etc.) and their acid dianhydrides can be listed in paragraph

[0080] of International Publication No. 2024 / 024901. １ When is a tetravalent aliphatic group, it is preferable that such aliphatic group is a group having an alicyclic structure. １ As for the tetravalent aliphatic group that can be selected, those known in the field of polyimides (for example, those exemplified in International Publication No. 2024 / 024901) may be used as appropriate.

[0039] Also, the above X １As for the tetravalent aromatic group that can be selected, residues obtained by removing two acid anhydride groups from known aromatic tetracarboxylic dianhydrides usable in the production of polyimides (which are synonymous with residues obtained by removing four carboxylic acid groups from an aromatic tetracarboxylic acid) can be suitably used. Such aromatic tetracarboxylic acids and aromatic tetracarboxylic dianhydrides are not particularly limited, and known ones can be used as appropriate. For example, examples include the aromatic tetracarboxylic dianhydride disclosed in paragraph

[0028] of Japanese Patent Application Publication No. 2022-190149, and the tetracarboxylic acid described in paragraph

[0079] of International Publication No. 2024 / 024901. Examples of such aromatic tetracarboxylic dianhydrides include 3,3',4,4'-biphenyltetracarboxylic dianhydride (s-BPDA), 2,3,3',4'-biphenyltetracarboxylic dianhydride (a-BPDA), pyromellitic dianhydride, 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride, 4-(2,5-dioxotetrahydrofuran-3-yl)-1,2,3,4-tetrahydronaphthalene-1,2-dicarboxylic anhydride, and 3,3',4,4'-benzophenone. Examples of such tetravalent aromatic groups include tetracarboxylic dianhydrides, 4,4'-oxydiphthalic acid dianhydrides (ODPA), 3,4'-oxydiphthalic acid dianhydrides, bis(3,4-dicarboxyphenyl)sulfone dianhydrides, m-terphenyl-3,4,3',4'-tetracarboxylic dianhydrides, p-terphenyl-3,4,3',4'-tetracarboxylic dianhydrides, biscarboxyphenyldimethylsilane dianhydrides, bisdicarboxyphenoxydiphenyl sulfide dianhydrides, sulfonyl diphthalic acid dianhydrides, and the like. Such tetravalent aromatic groups may be those known in the field of polyimides (for example, those exemplified in International Publication No. 2024 / 024901) as appropriate. Furthermore, the group represented by formula (1-2) above can be suitably used as the tetravalent aromatic group.

[0040] Note that X in the precursor １ Regarding this, as mentioned above, X in the precursor １It is sufficient that 50 mol% or more of the total amount consists of a tetravalent aromatic group represented by formula (1-1) (such a group is the same as the residue obtained by removing two acid anhydride groups from s-BPDA), and depending on the application, such a group can be used in combination with other groups other than the tetravalent aromatic group represented by formula (1-1) selected from the aforementioned tetravalent aliphatic groups or tetravalent aromatic groups. １ Groups that can be suitably used in combination with the group represented by formula (1-1) will be described later.

[0041] Also, Y in formula (1) １ Y is a divalent aliphatic group or a divalent aromatic group. In the present invention, Y present in the polyimide precursor １ 50 mol% or more of the total amount (Y contained in the precursor) １ Since more than 50 mol% of the total amount of the structure (group) represented by the precursor is a p-phenylene group, Y １ This will always include a p-phenylene group. Hereafter, including the p-phenylene group, Y in formula (1) １ This section describes the bases that can be selected as such.

[0042] This kind of Y １ The divalent aliphatic group that can be selected is not particularly limited, and residues obtained by removing two amino groups from known aliphatic diamines available for the production of polyimides can be suitably used. Such aliphatic diamines are not particularly limited, and known ones can be used as appropriate. Examples include the diamines described in paragraph

[0101] of International Publication No. 2024 / 024901 (1,4-diaminocyclohexane, 1,4-diamino-2-methylcyclohexane, 1,4-diamino-2-ethylcyclohexane, etc.) and the diamines having an aliphatic structure described in paragraph

[0034] of Japanese Patent Application Publication No. 2023-034768. １ If the aliphatic group is an aliphatic group, it is preferable that the aliphatic group has an alicyclic structure. Furthermore, as such a divalent aliphatic group, those known in the field of polyimides (for example, those exemplified in International Publication No. 2024 / 024901) may be used as appropriate.

[0043] Also, Y １The divalent aromatic group that can be selected is not particularly limited, and residues obtained by removing two amino groups from known aromatic diamines available for the production of polyimides can be suitably used. Such aromatic diamines are not particularly limited, and known ones can be used as appropriate, for example, diamines described in paragraph

[0096] of International Publication No. 2024 / 024901 (p-phenylenediamine, m-phenylenediamine, benzidine, etc.), aromatic diamines described in paragraph

[0047] of Japanese Patent Application Publication No. 2022-000518 (4,4'-diaminobenzanilide, 4,4'-diaminodiphenyl ether, 2,2'-bis(trifluoromethyl)benzidine, 9,9'-bis(4-aminophenyl)fluorene, 4-aminophenyl-4-aminobenzoate, 4,4'-bis(4-aminobenzamide)-3,3'-dihydroxybiphenyl, 4,4'-diaminodiphenylsulfone, etc.). Examples of such aromatic diamines include p-phenylenediamine (PPD), 9,9-bis(4-aminophenyl)fluorene (BAFL), m-phenylenediamine, benzidine, 3,3'-diamino-biphenyl, 2,2'-bis(trifluoromethyl)benzidine, m-tolidine, 3,4'-diaminobenzanilide, 4,4'-diaminobenzanilide, N,N'-bis(4-aminophenyl)terephthalamide, N,N'-p-phenylenebis(p-aminobenzamide), 4-aminophenyl-4-diaminobenzoate, 4,4'-diaminodiphenylsulfone (4,4'-DDS), bis(4-aminophenyl)terephthalate, Biphenyl-4,4'-dicarboxylate bis(4-aminophenyl) ester, p-phenylenebis(p-aminobenzoate), bis(4-aminophenyl)-[1,1'-biphenyl]-4,4'-dicarboxylate, [1,1'-biphenyl]-4,4'-diylbis(4-aminobenzoate), 4,4'-oxydianiline, 3,4'-oxydianiline, 3,3'-oxydianiline, p-methylenebis(phenylenediamine), 1,3-bis(4-aminophenoxy)benzene, 1,3-bis(3-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene, 4,4'-bis(4-aminophenoxy)biphenyl, 4,4'-Bis(3-aminophenoxy)biphenyl, 2,2-Bis(4-(4-aminophenoxy)phenyl)hexafluoropropane, 2,2-Bis(4-aminophenyl)hexafluoropropane, Bis(4-aminophenyl)sulfone, 3,3'-Bis(trifluoromethyl)benzidine, 3,3'-Bis((aminophenoxy)phenyl)propane, 2,2'-Bis(3-amino-4-hydroxyphenyl)hexafluoropropane, Bis(4-(4-aminophenoxy)diphenyl)sulfone, Bis(4-(3-aminophenoxy)diphenyl)sulfone, Octafluorobenzidine, 3,3'-Dimethoxy-4,4'-Diaminobiphenyl, 3,3'-Dichloro-4,4'-Diaminobiphenyl, 3 Examples include 3'-difluoro-4,4'-diaminobiphenyl, 2,4-bis(4-aminoanilino)-6-amino-1,3,5-triazine, 2,4-bis(4-aminoanilino)-6-methylamino-1,3,5-triazine, 2,4-bis(4-aminoanilino)-6-ethylamino-1,3,5-triazine, 2,4-bis(4-aminoanilino)-6-anilino-1,3,5-triazine, 4,4'-(((9H-fluorene-9,9-diyl)bis([1,1'-biphenyl]-5,2-diyl))bis(oxy))diamine, [1,1':4',1''-terphenyl]-4,4''-diamine, and 4,4'-([1,1'-binaphthalene]-2,2'-diylbis(oxy))diamine. Such divalent aromatic groups may be those known in the field of polyimides (for example, those exemplified in International Publication No. 2024 / 024901) as appropriate. Furthermore, as such divalent aromatic groups, the divalent aromatic groups represented by the above formula (1-3) can be suitably used. In formula (1-3), R, １２ and R １３ This will be discussed later.

[0044] Furthermore, Y in the precursor １ Regarding this, as mentioned above, Y present in the precursor １It is sufficient that 50 mol% or more of the total amount consists of p-phenylene groups (such groups are similar to the residue obtained by removing two amino groups from PPD), and depending on the application, other groups besides p-phenylene groups selected from the aforementioned divalent aliphatic groups or divalent aromatic groups can be used in appropriate combination with such groups. １ Groups that are suitably used in combination with the p-phenylene group will be described later.

[0045] Furthermore, in formula (1) above, R １ and R ２ Each of these is independently a hydrogen atom, a C1-C6 alkyl group, or a C3-C9 alkylsilyl group, but from the viewpoint of ease of production, in formula (1) above, R １ and R ２ Preferably, all of these are hydrogen atoms.

[0046] (Conditions for the polyimide precursor, etc.) The polyimide precursor according to the present invention contains repeating units represented by formula (1). Generally, the polyimide precursor containing the repeating units represented by formula (1) is produced by reacting a tetracarboxylic acid component (tetracarboxylic dianhydride) with a diamine. Depending on the reaction conditions used, after the repeating units represented by formula (1) are formed, at least one of the two amide structures (-CONH-) in the structure represented by formula (1) may be -COOR in the same structure. １ and / or - COOR ２ It reacts with to chemically cyclize, and some of the repeating units represented by formula (1) are such that at least one of the two amide structures (-CONH-) in formula (1) is -COOR １ and / or - COOR ２ It can react with and imide-formed repeating units (hereinafter, depending on the case, simply referred to as "repeating units introduced from the repeating units represented by formula (1)"). Therefore, the polyimide precursor according to the present invention, together with the repeating units represented by formula (1), has at least one of the two amide structures (-CONH-) in formula (1) being -COOR１ and / or - COOR ２ It may include repeating units that react with and imide (repeating units introduced from the repeating unit represented by formula (1) above). Note that all formulas in the structure of the repeating unit represented by formula (1) are: -COOR(R is R １ or R ２ The repeating unit formed when a group represented by (showing) and two structures represented by the formula: -CONH- react to form a ring-closed imidized repeating unit is the repeating unit represented by the following formula (2-1) (X in formula (2-1) １ and Y １ These are the X in equation (1) １ and Y １ This is equivalent to the repeating unit of polyimide. Also, one of the two amide structures (-CONH-) in formula (1) is -COOR １ The repeating unit that reacts with and partially imides is the repeating unit represented by the following formula (2-2) (X in formula (2-2) １ , Y １ and R ２ These are the X in equation (1) １ , Y １ and R ２ (This is equivalent to) and one of the two amide structures (-CONH-) in formula (1) becomes -COOR ２ The repeating unit that reacts with and partially imides is the repeating unit represented by the following formula (2-3) (X in formula (2-3) １ , Y １ and R １ These are the X in equation (1) １ , Y １ and R １ This is equivalent to:

[0047]

[0048] Therefore, the polyimide precursor according to the present invention is preferably composed of at least one polymer selected from the group consisting of a polymer (polyamic acid and its derivatives) consisting only of the repeating unit represented by the formula (1); and a polymer (partially imidized polyamic acid and its derivatives) containing the repeating unit represented by the formula (1) and at least one repeating unit (at least one repeating unit selected from the group consisting of the repeating units represented by the formulas (2-1) to (2-3)) introduced derived from the repeating unit represented by the formula (1). All of these polymers are preferably the reaction products and their derivatives of a tetracarboxylic acid component (tetracarboxylic dianhydride) and a diamine, and the tetracarboxylic dianhydride represented by the following formula (3) (X １ in the formula (3) is the same as X １ in the formula (1).), and the formula: H ２ N-Y １ -NH ２ is more preferably the reaction product of the diamine represented by (where Y １ in the formula is the same as Y １ in the formula (1).). When the polyimide precursor according to the present invention contains, together with the repeating unit represented by the formula (1), at least one repeating unit (at least one repeating unit selected from the group consisting of the repeating units represented by the formulas (2-1) to (2-3)) introduced derived from the repeating unit represented by the formula (1), the imidization rate of the polyimide precursor is preferably 60 mol% or less (more preferably 50 mol% or less). Such an imidization rate is obtained by measuring the 1H-NMR spectrum of a measurement sample in which a polyimide precursor composition is diluted with a heavy solvent using a nuclear magnetic resonance apparatus, and assuming that the structure of the formulas (2-1) to (2-3) is not included, that is, in the state of a complete polyamic acid, the integral value α of the peak derived from 1H of the two amide structures (-CONH-) in the formula (1), and from the integral value α, the integral value of the peak derived from 1H of the two amide structures (-CONH-) in the formula (1) obtained by actual measurement １ H-NMR spectrum, and the two amide structures (-CONH-) in the formula (1) when assuming that the structure of the formulas (2-1) to (2-3) is not included, that is, in the state of a complete polyamic acid. １ The integral value α of the peak derived from 1H of the two amide structures (-CONH-) in the formula (1) actually measured from the integral value α of the peak derived from 1H of the two amide structures (-CONH-) in the formula (1) １It can be calculated as the ratio (%) of the value α−β obtained by subtracting the integrated value β of the peak derived from H, and can be determined by the following calculation formula: [Imidation rate (%)]=(α−β)÷α×100. Therefore, the "imidation rate" referred to herein can be determined as the ratio of the molar amount of the structure in which two amide structures (—CONH—) in the formula (1) are cyclized and imidized to the molar amount of the two amide structures (—CONH—) in the formula (1) assuming the state of a complete polyamic acid.

[0049] Thus, in this specification, the "polyimide precursor" is a concept including polyamic acid and its derivatives, partially imidized polyamic acid in which imidization has progressed, and its derivatives. In this specification, the term "polyimide precursor" is used in the sense of a precursor capable of forming a polyimide (for example, a precursor capable of forming a polyimide in a polyimide film).

[0050] Further, the polyimide precursor according to the present invention needs to satisfy the above (i). That is, in the polyimide precursor according to the present invention, 50 mol% or more of the total amount of X １ present in the polyimide precursor is a tetravalent aromatic group represented by the following formula (1-1). In this specification, the "total amount of X １ present in the polyimide precursor" means the total amount of all the structures (groups) represented by X １ contained in the precursor. For example, when the polyimide precursor consists only of the repeating unit represented by the formula (1), it means the total amount of X １ contained in all the repeating units represented by the formula (1). Further, when there are a repeating unit represented by the formula (1) and a repeating unit introduced derived from the repeating unit represented by the formula (1) (for example, a repeating unit represented by the formula (2-1), etc.) in the precursor, X １ in the repeating unit represented by the formula (1) and X １ in the repeating unit introduced derived from the repeating unit represented by the formula (1) are included, and it means the total amount of all X １ contained in the precursor.

[0051]

[0052] X present in the aforementioned polyimide precursor １ When the content of the tetravalent aromatic group represented by formula (1-1) is 50 mol% or more relative to the total amount, it exhibits excellent heat resistance based on the 0.5% weight loss temperature. Furthermore, from the same viewpoint, a higher effect can be obtained, so X present in the polyimide precursor １ The content of the tetravalent aromatic group represented by formula (1-1) relative to the total amount is more preferably 70 mol% or more, even more preferably 80 mol% or more, particularly preferably 85 mol% or more, and most preferably 90 mol% or more. １ There is no particular upper limit on the content of the tetravalent aromatic group represented by formula (1-1) relative to the total amount of X, and it may be, for example, 100 mol%. Therefore, for example, the above X １ Suitable ranges for the content of the tetravalent aromatic group represented by formula (1-1) relative to the total amount include 70-100 mol% and 85-100 mol%.

[0053] Furthermore, the polyimide precursor according to the present invention must satisfy (ii) above. That is, the polyimide precursor according to the present invention must contain Y present in the polyimide precursor. １ More than 50 mol% of the total amount is p-phenylene groups. In this specification, "Y present in the polyimide precursor" １ "Total amount" means the amount of Y contained in the precursor. １ This refers to the total amount of all structures (groups) represented by the formula (1). For example, if the polyimide precursor consists only of repeating units represented by the formula (1), then the amount of Y contained in all repeating units represented by the formula (1) is the total amount of Y. １ This refers to the total amount of Y in the repeating unit represented by formula (1), and if the precursor contains a repeating unit represented by formula (1) and a repeating unit introduced from the repeating unit represented by formula (1) (for example, a repeating unit represented by formula (2-1), etc.), then Y in the repeating unit represented by formula (1) １ And, Y in the repeating unit introduced from the repeating unit represented by formula (1) above １All Y contained in the precursor, including １ This refers to the total amount.

[0054] Y present in the aforementioned polyimide precursor １ When the p-phenylene group content is 50 mol% or more relative to the total amount, it exhibits excellent heat resistance based on the 0.5% weight loss temperature. Furthermore, from the same viewpoint, a higher effect can be obtained, so Y present in the polyimide precursor. １ The content of p-phenylene groups relative to the total amount is more preferably 70 mol% or more, even more preferably 80 mol% or more, particularly preferably 85 mol% or more, and most preferably 90 mol% or more. １ There is no particular upper limit on the content of p-phenylene groups relative to the total amount of Y, and it may be, for example, 100 mol%. Therefore, for example, Y １ Suitable ranges for the p-phenylene group content relative to the total amount include 70 mol to 100 mol% and 85 to 100 mol%.

[0055] Furthermore, in the present invention, X present in the polyimide precursor １ It is sufficient that 50 mol% or more of the total amount is a tetravalent aromatic group represented by the above formula (1-1), and the other groups are X １ It may also be included as follows. Other groups used in combination with the tetravalent aromatic group represented by formula (1-1) include X １From among the tetravalent aliphatic groups and tetravalent aromatic groups that can be selected, groups other than the group represented by formula (1-1) can be appropriately selected and used, and there are no particular restrictions. However, from the viewpoint of improving transparency, it is preferable to use a tetravalent aromatic group other than the group represented by formula (1-1), and among these, it is more preferable to use the group represented by formula (1-2), a residue obtained by removing two acid anhydride groups from 2,3,3',4'-biphenyltetracarboxylic acid dianhydride (a-BPDA), a residue obtained by removing two acid anhydride groups from 4,4'-oxydiphthalic acid dianhydride (ODPA), a residue obtained by removing two acid anhydride groups from 3,4'-oxydiphthalic acid dianhydride, it is even more preferable to use a tetravalent aromatic group represented by formula (1-2), and it is particularly preferable to use a residue obtained by removing two acid anhydride groups from 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride (BPAF). The polyimide precursor according to the present invention is X １ As such, if it contains groups other than the tetravalent aromatic group represented by formula (1-1), X present in the polyimide precursor １ It is preferable that 1 to 30 mol%, more preferably 3 to 20 mol%, and even more preferably 5 to 15 mol%, of the total amount are groups other than the tetravalent aromatic group represented by formula (1-1). １ If the content of groups other than the tetravalent aromatic group represented by formula (1-1) relative to the total amount exceeds the upper limit, the heat resistance decreases, and it tends to become difficult to achieve both high heat resistance and transparency at a higher level. On the other hand, if it is below the lower limit, the effect of improving transparency tends to decrease.

[0056] Furthermore, the polyimide precursor according to the present invention is X present in the polyimide precursor. １ It is preferable that 1 to 30 mol%, more preferably 3 to 20 mol%, and even more preferably 5 to 15 mol%, of the total amount are tetravalent aromatic groups represented by the following formula (1-2). X present in the polyimide precursor １When the content of tetravalent aromatic groups represented by the following formula (1-2) relative to the total amount exceeds the upper limit, the heat resistance tends to decrease compared to the case below the upper limit, making it difficult to achieve both high heat resistance and transparency. On the other hand, when it is below the lower limit, the effect of improving transparency tends to be lower compared to the case above the lower limit.

[0057]

[0058] [R in equation (1-2)] １０ and R １１ Each of these is independently a single-bonded or divalent organic group.

[0059] In equation (1-2), R １０ and R １１ As for the divalent organic group that can be selected, an organic group containing an aromatic ring is preferred, and for example, a group represented by the following formula (1-2-1) can be suitably used.

[0060]

[0061] [In formula (1-2-1), R ２０ and R ２１ Each of them is independently a single bond, -COO-, -OCO-, or -O- (R ２１ When R is bonded to the fluorenyl group, ２０ is -COO-, -OCO- or -O- and R ２１ (Preferably a single bond), n R ３０ Each of these is independently an alkyl group or phenyl group having 1 to 4 carbon atoms (preferably methyl), and n is an integer from 0 to 4 (preferably 1).

[0062] Furthermore, the tetravalent aromatic group represented by formula (1-2) is R in the formula. １０ and R １１ Groups in which both are single bonds are more preferable, and tetravalent aromatic groups represented by the following formula (1-2A) are particularly preferred. Such tetravalent aromatic groups represented by formula (1-2A) can be efficiently introduced by using BPAF as the tetracarboxylic acid component (tetracarboxylic dianhydride) used in the production of polyimide precursors.

[0063]

[0064] In the polyimide precursor according to the present invention, X １ Along with the groups represented by formulas (1-1) and (1-2), other groups can also be appropriately included. In that case, the amount of such other groups should be such that X present in the polyimide precursor, from the viewpoint of achieving both heat resistance and transparency. １ It is preferable that the amount is 30 mol% or less, more preferably 20 mol% or less, and even more preferably 10 mol% or less, relative to the total amount.

[0065] Furthermore, in the present invention, Y present in the polyimide precursor １ It is sufficient that 50 mol% or more of the total amount is a p-phenylene group, and the other groups are combined with the p-phenylene group to form Y １ It may be included as such. The group (Y) used in combination with the p-phenylene group in this way. １ ) as Y １ From among the divalent aliphatic groups and divalent aromatic groups that can be selected, any group other than the p-phenylene group may be appropriately selected and used, and there are no particular restrictions, but from the viewpoint of improving transparency, a divalent aromatic group is preferred, and among them, a divalent aromatic group represented by the above formula (1-3), a residue obtained by removing two amino groups from m-phenylenediamine, a residue obtained by removing two amino groups from 4-aminophenyl-4-aminobenzoate, and two amino groups from bis(4-aminophenyl)sulfone are preferred because they provide an even higher effect in terms of achieving both heat resistance and transparency. Preferably, the residue is a residue with the amino group removed, a residue obtained by removing two amino groups from 2,2'-bis(trifluoromethyl)benzidine, or a residue obtained by removing two amino groups from 4,4'-diaminodiphenylsulfone (4,4'-DDS), more preferably a group represented by formula (1-3), more preferably a residue obtained by removing two amino groups from 4,4'-DDS, more preferably a residue obtained by removing two amino groups from BAFL, more preferably a residue obtained by removing two amino groups from 4,4'-DDS, and particularly preferably a residue obtained by removing two amino groups from BAFL. The polyimide precursor according to the present invention is Y １If it contains groups other than the p-phenylene group, Y present in the polyimide precursor １ It is preferable that 1 mole to 30 mole%, more preferably 3 to 20 mole%, and even more preferably 5 to 15 mole%, of the total amount of groups other than p-phenylene groups. １ If the content of groups other than p-phenylene groups relative to the total amount exceeds the upper limit, the heat resistance tends to decrease, making it difficult to achieve both heat resistance and transparency. If it is below the lower limit, the effect of improving transparency tends to decrease.

[0066] Furthermore, the polyimide precursor according to the present invention is Y present in the polyimide precursor. １ It is more preferable that 1 to 30 mol%, more preferably 3 to 20 mol%, and even more preferably 5 to 15 mol% of the total amount are divalent aromatic groups represented by the following formula (1-3). Y present in the polyimide precursor １ When the content of divalent aromatic groups represented by the following formula (1-3) relative to the total amount exceeds the upper limit, the heat resistance tends to be lower compared to the case below the upper limit, and it tends to be difficult to achieve both high heat resistance and transparency at a higher level. When it is below the lower limit, the effect of improving transparency tends to be lower compared to the case above the lower limit.

[0067]

[0068] [R in equation (1-3)] １２ and R １３ Each of these is independently a single-bonded or divalent organic group.

[0069] In equations (1-3), R １２ and R １３ As for the divalent organic group that can be selected, an organic group containing an aromatic ring is preferred, and for example, a group represented by the following formula (1-3-1) can be suitably used.

[0070]

[0071] [In formula (1-3-1), R ２２ and R ２３ Each of them is independently a single bond, -COO-, -OCO-, or -O- (R ２３ When R is bonded to the fluorenyl group,２２ is -COO-, -OCO- or -O- and R ２３ (Preferably a single bond), n R ３１ Each of these is independently an alkyl group or phenyl group having 1 to 4 carbon atoms (preferably methyl), and n is an integer from 0 to 4 (preferably 1).

[0072] Furthermore, the divalent aromatic group represented by formula (1-3) is R in the formula. １２ and R １３ Groups in which all are single bonds are more preferable, and tetravalent aromatic groups represented by the following formula (1-3A) are particularly preferred. Such tetravalent aromatic groups represented by formula (1-3A) can be efficiently introduced by using BAFL as the diamine used in the production of polyimide precursors.

[0073]

[0074] In the polyimide precursor according to the present invention, Y １ It is possible to include other groups along with the p-phenylene group and the group represented by formula (1-3) as appropriate, but in that case, the content of such other groups is determined from the viewpoint of achieving both heat resistance and transparency, Y １ It is preferable that the amount is 30 mol% or less, more preferably 20 mol% or less, and even more preferably 10 mol% or less, relative to the total amount.

[0075] Furthermore, the polyimide precursor according to the present invention contains repeating units represented by formula (1) from the viewpoint of heat resistance, and X present in the polyimide precursor. １ Preferably, all of these are tetravalent aromatic groups represented by the above formula (1-1), and from the viewpoint of achieving both heat resistance and transparency, it is preferable that they contain repeating units represented by formula (1) and X present in the polyimide precursor. １ 70 to 99 mol% (more preferably 80 to 97 mol%, particularly preferably 85 to 95 mol%) of the total amount is a tetravalent aromatic group represented by the above formula (1-1), and X is present in the polyimide precursor. １It is preferable that 1 to 30 mol% (more preferably 3 to 20 mol%, particularly preferably 5 to 15 mol%) of the total amount are tetravalent aromatic groups represented by the above formula (1-2).

[0076] Furthermore, from the viewpoint of heat resistance, the polyimide precursor according to the present invention contains repeating units represented by formula (1), and Y present in the polyimide precursor. １ Preferably, all of these are p-phenylene groups, and from the viewpoint of achieving both heat resistance and transparency, it is preferable that it contains repeating units represented by formula (1) and Y present in the polyimide precursor. １ 70 to 99 mol% (more preferably 80 to 97 mol%, particularly preferably 85 to 95 mol%) of the total amount is p-phenylene groups, and Y present in the polyimide precursor １ It is preferable that 1 to 30 mol% (more preferably 3 to 20 mol%, particularly preferably 5 to 15 mol%) of the total amount are divalent aromatic groups represented by the above formula (1-3).

[0077] Furthermore, such polyimide precursors are easy to manufacture and are tetracarboxylic dianhydrides represented by the following formula (3) (X in formula (3)). １ X in equation (1) above １ This is equivalent to: ) and formula: H ２ N-Y １ -NH ２ Diamine represented by (Y in the formula) １ Y in equation (1) above １ It is synonymous with ) and preferably an addition polymerization product (reactant) of ).

[0078]

[0079] The polyimide precursor is a tetracarboxylic dianhydride represented by formula (3) (X in formula (3)). １ X in equation (1) above １ This is equivalent to: ) and formula: H ２ N-Y １ -NH ２ Diamine represented by (Y in the formula) １ Y in equation (1) above １This is synonymous with ). When it is an addition polymerization product (polyaddition reaction product) with ) the tetracarboxylic dianhydride represented by formula (3) above must be s-BPDA at a rate of 50 mol% or more of the total amount so that the resulting precursor satisfies (i) above, and the above formula: H ２ N-Y １ -NH ２ As the diamine represented by , 50 mol% or more of the total amount is PPD (formula: H) such that the obtained precursor satisfies (ii) above. ２ N-Y １ -NH ２ Y inside １ It is necessary that the diamine is a p-phenylene group. Thus, when the polyimide precursor is the addition polymer (polyaddition reaction product), the polyimide precursor must be a reaction product (addition polymer) of a tetracarboxylic dianhydride represented by formula (3) containing 50 mol% or more of s-BPDA (tetracarboxylic acid component) and a diamine containing 50 mol% or more of PPD (diamine component). The polyimide precursor consisting of such an addition polymer is a so-called polyamic acid (R １ and R ２ These are polyimide precursors, each consisting of a hydrogen atom.

[0080] Furthermore, if the polyimide precursor is a reaction product of the tetracarboxylic acid component and the diamine component, it is more preferable that the content of s-BPDA in the tetracarboxylic acid component be 70 mol% or more (more preferably 80 mol% or more, particularly preferably 85 mol% or more, and most preferably 90 mol% or more), and it is more preferable that the content of PPD in the diamine component be 70 mol% or more (more preferably 80 mol% or more, particularly preferably 85 mol% or more, and most preferably 90 mol% or more). Furthermore, if the tetracarboxylic acid component contains a component other than s-BPDA, it is preferable that the component is BPAF, 2,3,3',4'-biphenyltetracarboxylic acid dianhydride, 4,4'-oxydiphthalic acid dianhydride, or 3,4'-oxydiphthalic acid dianhydride, and more preferably BPAF. In that case, the content of the component other than s-BPDA in the tetracarboxylic acid component is 1 to 30 mol%, more preferably 3 to 20 mol%, and even more preferably 5 to 15 mol%. Furthermore, when the diamine component contains components other than PPD, the components are preferably BAFL, m-phenylenediamine, 4-aminophenyl-4-aminobenzoate, bis(4-aminophenyl)sulfone, 2,2'-bis(trifluoromethyl)benzidine, and 4,4'-DDS, more preferably BAFL and 4,4'-DDS, and even more preferably BAFL. In that case, the content of components other than PPD in the diamine component is preferably 1 to 30 mol%, more preferably 3 to 20 mol%, and particularly preferably 5 to 15 mol%. Furthermore, the method for obtaining the addition polymer is not particularly limited, and any method known in the field of polyimides may be appropriately adopted, and the method described later in the method for producing polyamic acid may be appropriately adopted.

[0081] Furthermore, the polyimide precursor of the present invention has R in the repeating unit represented by formula (1) above. １ and R ２ Depending on the type, it can be classified into the following 1) to 3). 1) Polyamic acid (R １ and R ２ 1) Polyimide precursors, all of which are hydrogen atoms; 2) Polyamic acid esters (R１ and R ２ 3) Polyimide precursors in which at least a portion is alkyl group, 3) Silyl polyamic acid esters (R １ and R ２ (A polyimide precursor in which at least a portion is an alkylsilyl group) Below, preferred methods for producing each classification of polyimide precursors will be described. However, the methods for producing such polyimide precursors in the present invention are not limited to the following methods.

[0082] 1) Method for producing polyamic acid When the polyimide precursor is polyamic acid, a method can be employed in which polyamic acid is produced in a solvent by reacting a tetracarboxylic dianhydride represented by formula (3) and the diamine in approximately equimolar proportions (preferably a proportion where the molar ratio of diamine to tetracarboxylic dianhydride [number of moles of diamine / number of moles of tetracarboxylic dianhydride] is 0.90 to 1.10, more preferably a proportion where the molar ratio is 0.95 to 1.05) at a relatively low temperature (for example, a temperature of 120°C or lower) while basically suppressing imidation. When such a method is employed, the polyimide precursor can be obtained in the form of a polyimide acid solution (polyimide precursor solution). In other words, a polyimide precursor solution can be produced efficiently by such a method. During the production of such polyimide precursors (polyamic acids), the repeating unit represented by formula (1) is basically formed, but depending on the reaction conditions, after the repeating unit represented by formula (1) is formed, at least one of the two amide structures (-CONH-) in formula (1) becomes -COOR １ and / or - COOR ２ This can lead to a reaction, and partially imidized repeating units may also be formed.

[0083] The method for producing such polyamic acid is not particularly limited, but it is preferable to use a method in which a diamine is dissolved in an organic solvent or water, and a tetracarboxylic dianhydride is gradually added to this solution while stirring, and the mixture is stirred at a temperature of 0 to 120°C, more preferably 5 to 80°C, for 1 to 72 hours to obtain polyamic acid (polyimide precursor). When the reaction is carried out at a temperature higher than 80°C, the molecular weight fluctuates depending on the temperature history during polymerization, and imidation may proceed due to heat, so depending on the type of monomer (tetracarboxylic dianhydride, diamine) used, it may be difficult to stably produce a polyimide precursor of the desired design. Furthermore, when employing such a method, the order of addition of the diamine and tetracarboxylic dianhydride is preferable from the viewpoint of keeping the molecular weight of the polyimide precursor to an appropriate size, but from the viewpoint of reducing precipitates, the order of addition may be reversed. The method for producing polyamic acid is not limited to the above method, and known methods can be appropriately adopted.

[0084] 2) Method for producing polyamic acid esters When the polyimide precursor is a polyamic acid ester, the method for producing it can be, for example, to react the tetracarboxylic dianhydride with any alcohol to obtain a diester dicarboxylic acid, then react it with a chlorinating agent (thionyl chloride, oxalyl chloride, etc.) to obtain a diester dicarboxylic acid chloride, and then react this diester dicarboxylic acid chloride with a diamine at a temperature of -20 to 120°C, preferably -5 to 80°C, while stirring for 1 to 72 hours to produce the polyamic acid ester. When the reaction is carried out at a temperature higher than 80°C, the molecular weight fluctuates depending on the temperature history during polymerization, and imidation proceeds due to heat, so depending on the type of monomer (tetracarboxylic dianhydride, diamine) used, it tends to be difficult to stably produce a polyimide precursor with the desired properties. Alternatively, the polyimide precursor can be produced by dehydrating the diester dicarboxylic acid and diamine obtained as described above using a phosphorus-based condensing agent or a carbodiimide condensing agent, and in this case as well, a polyimide precursor can be easily obtained. The polyimide precursors obtained by these methods are stable and can be purified by adding solvents such as water or alcohol to reprecipitation. The methods for producing such polyamic acid esters are not limited to the above methods, and known methods can be used as appropriate.

[0085] 3) Method for producing silyl polyamic acid esters The method for producing silyl polyamic acid esters will be described below, divided into the so-called indirect method and the so-called direct method.

[0086] 3-1) Method for Producing Silyl Polyamic Acid Esters (Indirect Method) As a method for producing silyl polyamic acid esters, for example, the following procedure can be used. First, a diamine is reacted with a silylating agent to obtain a silylated diamine. At this point, the silylated diamine is purified by distillation or other means as needed. Next, a tetracarboxylic dianhydride is gradually added to the solution obtained by dissolving the silylated diamine in a dehydrated solvent while stirring, and the mixture is stirred at a temperature of 0 to 120°C, preferably 5 to 80°C, for 1 to 72 hours to obtain a polyimide precursor, which is a silyl polyamic acid ester. In such a method, when the reaction is carried out at a temperature higher than 80°C, the molecular weight fluctuates depending on the temperature history during polymerization, and imidation proceeds due to heat. Therefore, depending on the type of monomer used (tetracarboxylic dianhydride, diamine), it tends to be difficult to stably produce a polyimide precursor with the desired properties.

[0087] 3-2) Method for Producing Silyl Polyamic Acid Esters (Direct Method) As a method for producing silyl polyamic acid esters, for example, a method can be employed in which the polyamic acid solution obtained by the method described in 1) above is mixed with a silylating agent, and the mixture is stirred at a temperature of 0 to 120°C, preferably 5 to 80°C, for 1 to 72 hours to obtain silyl polyamic acid esters. In such a method, when the reaction is carried out at a temperature higher than 80°C, the molecular weight fluctuates depending on the temperature history during polymerization, and imidation proceeds due to heat. Therefore, depending on the type of monomer used (tetracarboxylic dianhydride, diamine), it tends to be difficult to stably produce a polyimide precursor with the desired properties.

[0088] As the "silylation agent" used in the methods described in 3-1) and 3-2) above, it is preferable to use a chlorine-free silylation agent because it is not necessary to purify the obtained silylated polyamic acid. Examples of such chlorine-free silylation agents include N,O-bis(trimethylsilyl)trifluoroacetamide, N,O-bis(trimethylsilyl)acetamide, and hexamethyldisilazane. Furthermore, from the viewpoint of not containing fluorine atoms and being low-cost, N,O-bis(trimethylsilyl)acetamide and hexamethyldisilazane are particularly preferred as the silylation agent.

[0089] Furthermore, there are no particular limitations on the solvent that can be used when reacting the tetracarboxylic dianhydride with the diamine in the solvent. Any known solvent that can be used in the production of polyamic acids and polyimides can be used as appropriate. For example, those exemplified as "solvents used when preparing polyimide precursors" in International Publication No. 2024 / 024901 (such as aprotic solvents like N-methyl-2-pyrrolidone (NMP)) can be used as appropriate. Any type of solvent that dissolves the raw material monomer components and the resulting polyimide precursor can be used without any problems, and there are no particular limitations on its structure, but an aprotic solvent is preferred. Furthermore, suitable aprotic solvents include N-methyl-2-pyrrolidone (NMP), N,N-dimethylformamide, N,N-dimethylacetamide, N,N-dimethylpropionamide, N,N-diethylacetamide, N,N-dimethylisobutylamide, N,N-diethylpropionamide, 3-methoxy-N,N-dimethylpropanamide, N-ethyl-2-pyrrolidone, N-butyl-2-pyrrolidone, tetramethylurea, dimethylpropyleneurea, 1,3-dimethyl-2-imidazolidinone, and dimethyl sulfoxide. Such solvents may be used individually or in combination of two or more.

[0090] Furthermore, when a polyimide precursor is obtained by reacting the tetracarboxylic dianhydride with the diamine in a solvent, the solid content concentration of the polyimide precursor (concentration based on the mass in terms of polyimide) is not particularly limited, but it is preferable to charge the monomer and solvent at a concentration such that the solid content concentration is 5 to 45% by mass and carry out the reaction.

[0091] Furthermore, while the logarithmic viscosity of the polyimide precursor is not particularly limited, it is preferable that the logarithmic viscosity in a 0.5 g / dL N-methyl-2-pyrrolidone solution at 30°C is 0.2 dL / g or higher, more preferably 0.3 dL / g or higher, and particularly preferably 0.4 dL / g or higher. When the logarithmic viscosity is 0.2 dL / g or higher, the molecular weight of the polyimide precursor increases, which tends to result in a polyimide with superior mechanical strength and heat resistance.

[0092] Furthermore, the average molecular weight (weight average) of the polyimide precursor is preferably 20,000 to 1,000,000, more preferably 50,000 to 500,000, in order to improve the mechanical strength and heat resistance of the polyimide film obtained using the polyimide precursor composition while making the viscosity of the composition appropriate and easy to handle. Such an average molecular weight can be measured using gel permeation chromatography (GPC).

[0093] <Alkoxysilane> The alkoxysilane used in the present invention is not particularly limited, and known alkoxysilanes can be used as appropriate.

[0094] Such alkoxysilanes are not particularly limited, and the formula is Si-OR ａ Structure represented by (R ａ Compounds having a hydrocarbon group (R) can be used as appropriate, and compounds that do not have a siloxane bond (-Si-O-) and a silanol group (Si-OH) can be used particularly suitably. Such alkoxysilanes include those of the formula: (R ａ O) ｎ Si(R ｂ ) ４－ｎ (n is an integer from 1 to 4, R ａ R is a hydrocarbon group, ｂCompounds represented by (where R is a hydrocarbon group) can be suitably used. ａ R can be any hydrocarbon group, but is more preferably a hydrocarbon group having 10 or fewer carbon atoms (preferably an alkyl group or aryl group, more preferably a linear or branched alkyl group having 1 to 8 carbon atoms (even more preferably 1 to 4 carbon atoms), and particularly preferably a methyl group or an ethyl group). Also, R in these formulas ｂ The hydrocarbon group can be any hydrocarbon group and is not particularly limited, but it is preferably a hydrocarbon group having 10 or fewer carbon atoms (more preferably an alkyl group or aryl group, even more preferably an aryl group, and especially a phenyl group). In the above formula, n is preferably 1 to 3, more preferably 2 or 3, and particularly preferably 3.

[0095] Examples of such alkoxysilanes include tetramethoxysilane, tetraethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, hexyltrimethoxysilane, hexyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, dimethoxydimethylsilane, diethoxydimethylsilane, dimethoxydiphenylsilane, diethoxydiphenylsilane, trimethylmethoxysilane, trimethylethoxysilane, triethylmethoxysilane, triethylethoxysilane, trihexylmethoxysilane, trihexylethoxysilane, triphenylmethoxysilane, and triphenylethoxysilane. Furthermore, among such alkoxysilanes, aryltrialkoxysilane is more preferred from the viewpoint of achieving both heat resistance and transparency, and compatibility with polyamic acids. Phenyltrimethoxysilane, phenyltriethoxysilane, 1-naphthyltrimethoxysilane, 1-naphthyltriethoxysilane, dimethoxydiphenylsilane, and diethoxydiphenylsilane are even more preferred. Phenyltrimethoxysilane, phenyltriethoxysilane, 1-naphthyltrimethoxysilane, and 1-naphthyltriethoxysilane are particularly preferred, and phenyltrimethoxysilane and phenyltriethoxysilane are most preferred. Such alkoxysilanes may be used individually or as a mixture of two or more. The method for producing such alkoxysilanes is not particularly limited, and known methods can be used as appropriate. Commercially available alkoxysilanes may also be used.

[0096] <Imidazole Compounds> The imidazole compounds used in the present invention are not particularly limited and can be any compounds having an imidazole skeleton. Examples of such imidazole compounds include 1,2-dimethylimidazole, 1-methylimidazole, 2-methylimidazole, 2-phenylimidazole, 1-phenylimidazole, imidazole, and benzimidazole. Among these imidazole compounds, 1,2-dimethylimidazole and 2-phenylimidazole are particularly preferred. Such imidazole compounds may be used individually or in combination of two or more. The method for producing such imidazole compounds is not particularly limited and known methods can be used as appropriate. Commercially available imidazole compounds may also be used.

[0097] <Composition and properties of the polyimide precursor composition> The polyimide precursor composition of the present invention is a composition containing the polyimide precursor, the alkoxysilane, and the imidazole compound.

[0098] In such a polyimide precursor composition, the content of the polyimide precursor is not particularly limited, but is preferably 5 to 45% by mass, and more preferably 10 to 30% by mass, based on the total amount of the polyimide precursor composition.

[0099] Furthermore, the alkoxysilane content in the polyimide precursor composition is preferably 5 to 150 parts by mass, more preferably 10 to 120 parts by mass, even more preferably 20 to 100 parts by mass, and particularly preferably 30 to 75 parts by mass, when the polyimide equivalent mass of the polyimide precursor is 100 parts by mass. An alkoxysilane content within the above range is preferable from the viewpoint of improving transparency and suppressing varnish gelation. If the alkoxysilane content is below the lower limit, the effect of improving transparency tends to be low, while if it exceeds the upper limit, the varnish tends to gel. In this specification, "polyimide equivalent mass of the polyimide precursor" refers to the mass (total amount) of polyimide obtained when polyimide is produced from the polyimide precursor (total amount) contained in the composition by completely imidizing all of the repeating units in the polyimide precursor contained in the composition.

[0100] Furthermore, from the viewpoint of improving heat resistance, improving transparency, and suppressing gelation of the varnish, the content of the imidazole compound in the polyimide precursor composition is preferably such that the ratio of the molar amount of the imidazole compound to the total molar amount of repeating units of the polyimide precursor [= ([molar amount of imidazole compound] / [total molar amount of repeating units]) × 100] is 0.1 mol% or more (more preferably 0.5 mol% or more). Also, from the viewpoint of achieving both storage stability of the varnish, transparency, and linear thermal expansion coefficient, the content of the imidazole compound in the composition is preferably such that the ratio of the molar amount of the imidazole compound to the total molar amount of repeating units of the polyimide precursor is 50 mol% or less (more preferably 10 mol% or less).

[0101] Furthermore, it is preferable that the polyimide precursor composition of the present invention further contains a solvent. By including a solvent in this way, the polyimide precursor composition of the present invention can be suitably used as a so-called varnish (resin solution) for the manufacture of polyimide films and the like. Such a solvent can be any solvent capable of dissolving the polyimide precursor, and is not particularly limited; the solvents described as those used in the manufacture of the polyimide precursor can be used. Moreover, aprotic solvents are preferred as such solvents, and N-methyl-2-pyrrolidone (NMP), N,N-dimethylformamide, N,N-dimethylacetamide, N,N-dimethylpropionamide, N,N-diethylacetamide, N,N-dimethylisobutylamide, N,N-diethylpropionamide, 3-methoxy-N,N-dimethylpropanamide, N-ethyl-2-pyrrolidone, N-butyl-2-pyrrolidone, tetramethylurea, dimethylpropyleneurea, 1,3-dimethyl-2-imidazolidinone, and dimethyl sulfoxide can be used more suitably. Such solvents may be used individually or in combination of two or more. For example, if a polyimide precursor solution (e.g., a polyamic acid solution) is obtained by producing the precursor in a solvent during the production of the polyimide precursor, that solution may be used as is in the production of the composition (it may be further diluted with a solvent or concentrated as necessary), and the solvent in such polyimide precursor solution may be used as is as the solvent in the composition.

[0102] Furthermore, if the polyimide precursor composition of the present invention contains a solvent, the solvent content is not particularly limited, but it is preferably 50 to 90% by mass, and more preferably 70 to 90% by mass.

[0103] Furthermore, the polyimide precursor composition of the present invention may further contain various additives as needed. Such additives can be any known compounds that can be used in the production of polyimides, and are not particularly limited. For example, chemical imidizing agents (acid anhydrides such as acetic anhydride, or amine compounds such as pyridine and isoquinoline), antioxidants, ultraviolet absorbers, fillers (inorganic particles such as silica), dyes, pigments, coupling agents such as silane coupling agents, primers, flame retardants, defoaming agents, leveling agents, rheology control agents (flow aids), etc., can be used as appropriate.

[0104] The polyimide precursor composition of the present invention is not particularly limited, but can be measured using an E-type rotational viscometer at a temperature of 25°C and a shear rate of 20 sec. －１ A composition having a viscosity (rotational viscosity) of 0.01 to 1000 Pa·sec, more preferably 0.1 to 100 Pa·sec, as measured under the specified conditions, is preferred. Thixotropy can also be imparted as needed. By setting the viscosity of the polyimide precursor composition within the above range, handling becomes easier during coating and film formation, and repulsion is suppressed, resulting in excellent leveling properties, which makes it possible to efficiently produce a better coating.

[0105] Furthermore, the polyimide precursor composition of the present invention has a viscosity retention rate of preferably 80% or more, more preferably 85% or more, even more preferably 90% or more, and particularly preferably 95% or more. This viscosity retention rate is the ratio of the viscosity of the composition after 30 days to the viscosity of the composition after 24 hours of storage at room temperature (approximately 23°C) under atmospheric pressure after preparation of the polyimide precursor composition. The viscosity of the composition is measured using a TVE-25 E-type viscometer manufactured by Toki Sangyo Co., Ltd., with a measurement temperature of 25°C.

[0106] Furthermore, it is preferable that the polyimide precursor composition of the present invention retains its fluidity even after being stored at atmospheric pressure and room temperature (approximately 23°C) for 30 days after preparation. The fluidity of the composition can be determined by tilting the storage container containing the composition at a 45° angle after 30 days of standing at atmospheric pressure and room temperature (approximately 23°C) and visually checking whether the composition in the container flows.

[0107] Furthermore, the method for producing the polyimide precursor composition of the present invention is not particularly limited, as long as it is a method capable of producing a composition containing the polyimide precursor, the alkoxysilane, and the imidazole compound. For example, a method can be suitably employed in which an imidazole compound or a solution of the imidazole compound is added to the polyimide precursor solution obtained as described above and mixed, and then an alkoxylane is added and mixed to obtain a composition containing the polyimide precursor, the alkoxysilane, and the imidazole compound. In such a method, the composition will contain a solvent. When employing such a method, in order to add the imidazole compound, a solution in which the imidazole compound is dissolved in a solvent may be prepared in advance and this solution may be added to the polyimide precursor solution. When using such a solvent for the imidazole compound, it is preferable that the solid content concentration of the imidazole compound in the solvent be 0.1 to 50% by mass. In the preparation of the polyimide precursor solution, a polyimide precursor solution containing an imidazole compound may be prepared by reacting a tetracarboxylic dianhydride with a diamine in the presence of an imidazole compound, and then adding and mixing the alkoxysilane to this solution to produce the polyimide precursor composition of the present invention.

[0108] Various forms of polyimides can be produced using the polyimide precursor composition of the present invention. The method for producing such polyimides is not particularly limited, and any known imidation method can be suitably applied. Furthermore, suitable forms of the resulting polyimides include films, coatings, powders, beads, molded articles, and foams.

[0109] Furthermore, the polyimide precursor composition of the present invention can also be used to produce a film made of so-called all-aromatic polyimide. In this case, it is possible to obtain a polyimide film that has the advantages of all-aromatic polyimide while simultaneously achieving a high level of transparency to light at a wavelength of 450 nm and a higher level of heat resistance.

[0110] The polyimide precursor composition of the present invention can be suitably used as a composition for "flexible electronic device substrates (particularly preferably flexible display substrates; the same applies hereinafter)". In this specification, when the term "for flexible electronic device substrates" is used for a polyimide precursor composition, it means a polyimide precursor composition that is applied directly onto a substrate when manufacturing a flexible electronic device (a composition for directly manufacturing a polyimide film as a flexible electronic device substrate from such a composition), as described below.

[0111] <Polyimide film, polyimide film / substrate laminate, flexible electronic device, and flexible electronic device substrate> In describing the polyimide film, polyimide film / substrate laminate, flexible electronic device, and flexible electronic device substrate of the present invention, we will first explain the terms used in this specification.

[0112] In this specification, "flexible (electronic) device" means a device that is flexible itself. Typically, such a "flexible (electronic) device" can be obtained by forming a semiconductor layer (such as transistors and diodes as elements) on a flexible substrate. However, the "flexible (electronic) device" referred to herein is distinguished from conventional devices such as COF (Chip On Film), in which "rigid" semiconductor elements such as IC chips are mounted on a conventional FPC (flexible printed circuit board). There is no problem in using the "flexible (electronic) device" referred to herein in conjunction with the "rigid" semiconductor elements such as IC chips by mounting them on a flexible substrate or electrically connecting them to operate or control the "flexible (electronic) device". Examples of "flexible (electronic) devices" that can be suitably used include flexible displays such as liquid crystal displays and organic EL displays, display devices such as electronic paper, solar cells, and light-receiving devices such as CMOS.

[0113] Furthermore, the term "flexible (electronic) device substrate" in this specification does not include flexible wiring boards (also referred to as flexible circuit boards, flexible printed circuit boards, etc.). Copper (or metal) clad laminates are used to manufacture flexible wiring boards (flexible circuit boards, flexible printed circuit boards), therefore, copper (or metal) clad laminates are also not included in the term "flexible (electronic) device substrate" as used herein.

[0114] Furthermore, when the terms "for flexible electronic device substrates" and "for flexible display substrates" are used in this specification in reference to polyimide films, it means that the polyimide film itself is a major component (or the substrate itself) of the substrate present in the final product (flexible electronic device), and does not refer to films and layers that are not present in the final product, or auxiliary layers laminated to the substrate. To give a specific example, a release layer is not a substrate.

[0115] Furthermore, when the terms "for flexible (electronic) device substrates" and "for flexible display substrates" are used in this specification for polyimide precursor compositions, such terms mean that the composition is a polyimide precursor composition used to directly manufacture a polyimide film for substrates. Therefore, a polyimide film for "flexible (electronic) device substrates (including for flexible display substrates; the same applies hereinafter)" is obtained by coating the polyimide precursor composition onto a substrate and imidizing it. For example, when two or more polyimide precursor compositions (intermediate compositions) are mixed and used to manufacture a polyimide film, each individual polyimide precursor composition is not a "for flexible (electronic) device substrates" composition as defined herein. This is because the structure of the resulting polyimide film depends on the structure of the polyimide precursor composition used to directly manufacture the polyimide film.

[0116] Furthermore, as mentioned above, copper (or metal) clad laminates are not used to manufacture flexible (electronic) devices; therefore, polyimide precursor compositions for copper clad laminate manufacturing are not polyimide precursor compositions for "flexible (electronic) device substrates." The definitions of these terms may be explained in more detail below.

[0117] <Polyimide Film and Polyimide Film / Substrate Laminate> One embodiment of the present invention is a polyimide film obtained from the polyimide precursor composition of the present invention described above. Hereinafter, a polyimide film of this embodiment (a polyimide film obtained from the polyimide precursor composition of the present invention described above), a polyimide film / substrate laminate using the same, a flexible electronic device, and a flexible electronic device substrate will be described, and then another embodiment of the polyimide film of the present invention will be described.

[0118] Such a polyimide film of the present invention is obtained from the polyimide precursor composition of the present invention described above. Furthermore, the polyimide film / substrate laminate of the present invention comprises the polyimide film of the present invention and a substrate.

[0119] Such polyimide films can be efficiently manufactured, for example, by forming a coating of the polyimide precursor composition of the present invention on a substrate and then heat-treating it. In this case, a polyimide film / substrate laminate is obtained simultaneously with the manufacture of the polyimide film. As such, it is preferable that the polyimide film of the present invention be a film made from a heat-treated polyimide precursor composition, since it can be easily manufactured by heat-treating after coating formation.

[0120] The thickness of such a polyimide film is preferably 1 μm or more, more preferably 2 μm or more, and even more preferably 5 μm or more. If the thickness is less than 1 μm, the polyimide film cannot maintain sufficient mechanical strength, and for example, when used as a substrate for a flexible electronic device, it may break due to inability to withstand stress. Furthermore, the thickness of the polyimide film is preferably 100 μm or less, more preferably 50 μm or less, and even more preferably 20 μm or less. If the thickness of the polyimide film is too thick, it may become difficult to make the flexible device thinner. To make the film thinner while maintaining sufficient durability as a flexible device, the thickness of the polyimide film is preferably 2 to 50 μm.

[0121] Furthermore, as mentioned above, such polyimide films can be obtained in the form of a polyimide film / substrate laminate, which has a polyimide film and a substrate, by forming a polyimide film on a substrate. In addition, such polyimide films can be applied to various uses in their laminate form.

[0122] Furthermore, the polyimide film / substrate laminate of the present invention may have the polyimide film of the present invention (a polyimide film obtained from the polyimide precursor composition of the present invention) and a substrate, and for example, other layers such as an inorganic thin film may be laminated on the surface of the polyimide film. Hereinafter, the substrate and other layers will be described together with the method for manufacturing the laminate. The polyimide film of the present invention obtained from the polyimide precursor composition of the present invention has particularly excellent heat resistance, for example, and can be appropriately used for work at high temperatures, and layers (for example, inorganic thin films, etc.) can be easily formed on the polyimide film according to the application.Therefore, polyimide film / substrate laminates in which various layers are laminated can be easily formed, and such laminates can be appropriately applied to various applications.

[0123] Furthermore, there are no particular limitations on the method for producing the polyimide film / substrate laminate, which is a laminate of the polyimide film and substrate of the present invention. However, it is possible to suitably employ a method that includes steps (a) to (b): (a) a step of applying a polyimide precursor composition (or "polyimide precursor composition for flexible electronic device substrates" if the resulting polyimide film is to be used for flexible electronic device substrates) onto a substrate; and (b) a step of heat-treating the coating film of the polyimide precursor composition on the substrate to produce a laminate (polyimide film / substrate laminate) in which the polyimide film is laminated on the substrate. After producing the polyimide film / substrate laminate, a step (b2) of forming an inorganic thin film on the surface of the polyimide film may be added to further produce a laminate in which the inorganic thin film / polyimide film / substrate are laminated in that order.

[0124] Step (a) is a step of coating a polyimide precursor composition onto a substrate. The substrate used in such a step is not particularly limited, but it is preferable to use a heat-resistant material. For example, plate-shaped or sheet-shaped substrates such as ceramic materials (glass, alumina, etc.), metal materials (iron, stainless steel, copper, aluminum, etc.), and semiconductor materials (silicon, compound semiconductors, etc.), or film-shaped or sheet-shaped substrates such as heat-resistant plastic materials (polyimide, etc.) can be suitably used. Furthermore, such substrates are preferably flat and smooth plate-shaped. Moreover, from the viewpoint of heat resistance, glass substrates such as soda-lime glass, borosilicate glass, alkali-free glass, and sapphire glass; semiconductor substrates (including compound semiconductors) such as silicon, GaAs, InP, and GaN; and metal substrates such as iron, stainless steel, copper, and aluminum are more preferable.

[0125] Furthermore, glass substrates are particularly preferred as such substrates because they are flat, smooth, and have a large surface area, and are readily available. The thickness of such plate-shaped substrates, such as glass substrates, is not particularly limited, but from the viewpoint of ease of handling, for example, it is preferably 20 μm to 4 mm, more preferably 100 μm to 2 mm. The size of the plate-shaped substrate is not particularly limited, but one side (the longer side in the case of a rectangle) is preferably about 100 mm to 4000 mm, more preferably about 200 mm to 3000 mm, and even more preferably about 300 mm to 2500 mm. Such substrates, such as glass substrates, may have an inorganic thin film (for example, a silicon oxide film) or a resin thin film formed on their surface.

[0126] Furthermore, in step (a), the method for applying the polyimide precursor composition onto the substrate is not particularly limited, but conventionally known methods such as slit coating, die coating, blade coating, spray coating, inkjet coating, nozzle coating, spin coating, screen printing, bar coating, and electrodeposition can be used as appropriate.

[0127] Furthermore, step (b) is a step of heat-treating a coating film of the polyimide precursor composition on a substrate to produce a laminate in which a polyimide film is laminated on the substrate. By such heat treatment, the coating film of the polyimide precursor composition can be converted into a polyimide film, thereby obtaining a polyimide film / substrate laminate. The conditions for such heat treatment are not particularly limited, but for example, it is preferable to dry the coating film in a temperature range of 50 to 150°C and then treat it with a maximum heating temperature in the range of 150 to 600°C (more preferably 200 to 550°C, and even more preferably 250 to 500°C).

[0128] In the present invention, it is preferable that the polyimide film / substrate laminate exhibits minimal warping. This warping characteristic can be evaluated by the residual stress between the polyimide film and the silicon substrate in the polyimide film / silicon substrate (wafer) laminate. Such residual stress will be described later.

[0129] Furthermore, as described above, the polyimide film / substrate laminate of the present invention may have a second layer, such as an inorganic thin film, on the surface of the polyimide film. When manufacturing a laminate having such a second layer, it is preferable to further perform step (b2). That is, from the viewpoint of obtaining a laminate having a desired laminate structure, the method for manufacturing the polyimide film / substrate laminate may further include, for example, a step (b2) of forming an inorganic thin film on the surface of the polyimide film formed on the substrate, in addition to steps (a) and (b).

[0130] Such inorganic thin films are preferably those that function as a barrier layer against water vapor, oxygen (air), etc. Examples of water vapor barrier layers include silicon nitride (SiN). ｘ ), silicon dioxide (SiO ｘ ), silicon oxynitride (SiO ｘ N ｙ ), aluminum oxide (Al ２ O ３ ), titanium oxide (TiO ２ ), zirconium oxide (ZrO ２Examples include inorganic thin films containing inorganic substances selected from the group consisting of metal oxides, metal nitrides, and metal oxynitrides. Generally, known methods for depositing these thin films include physical deposition methods such as vacuum deposition, sputtering, and ion plating, and chemical deposition methods (CVD: chemical vapor deposition) such as plasma CVD and catalytic chemical vapor deposition (Cat-CVD). In these deposition methods, including the CVD method, the film is densified by high-temperature annealing at, for example, 350°C to 450°C after deposition in order to improve the barrier function. In this specification, "inorganic thin film" refers to both the state before and after annealing. If it refers to only one state, it will be explicitly indicated or will be clear from the context. Similarly, "polyimide film / substrate laminate" refers to both those having an "inorganic thin film" and those not having one.

[0131] Such a second layer can consist of multiple layers. In this case, different types of inorganic thin films may be formed, or a resin film and an inorganic thin film may be combined. An example of the latter is the formation of a three-layer structure of a barrier layer / polyimide layer / barrier layer on a polyimide film in a polyimide film / substrate laminate.

[0132] Furthermore, after obtaining the polyimide film / substrate laminate in this manner, the polyimide film can be peeled off the substrate to obtain only the polyimide film. When manufacturing a single polyimide film (one consisting only of polyimide film, not a laminate), the manufacturing method is not particularly limited, and known manufacturing methods can be used as appropriate. In addition to the method of obtaining a single polyimide film by peeling off the polyimide film from the substrate after obtaining the polyimide film / substrate laminate, for example, a method may be employed in which a polyimide precursor composition is applied to the substrate, the coating is heated and dried to produce a self-supporting film, the self-supporting film is peeled off the substrate, and the film is held in a tenter, for example, and heated and imidized from both sides of the film in a state where degassing is possible to obtain a polyimide film.

[0133] <Flexible Electronic Device and Flexible Electronic Device Substrate> The flexible electronic device of the present invention comprises the polyimide film of the present invention. The flexible electronic device substrate of the present invention is made of the polyimide film of the present invention.

[0134] The flexible electronic device of the present invention may be any device comprising the polyimide film of the present invention, and other configurations are not particularly limited. For example, other than providing a substrate made of the polyimide film of the present invention as the flexible electronic device substrate, known configurations in the field of flexible electronic devices can be appropriately adopted depending on the application.

[0135] The method for manufacturing such a flexible electronic device of the present invention is not particularly limited, but a method can be suitably employed that includes (c) forming at least one layer selected from a conductive layer and a semiconductor layer on the polyimide film of the laminate, and (d) peeling the substrate from the polyimide film, using the polyimide film / substrate laminate manufactured in the above-described steps (a) and (b) (preferably further step (b2)). In the method for manufacturing a flexible electronic device, the polyimide precursor composition applied to the substrate in step (a) is a polyimide precursor composition for flexible electronic device substrates.

[0136] Step (c) is the step of forming at least one layer selected from a conductive layer and a semiconductor layer on the polyimide film (including a polyimide film with a second layer, such as an inorganic thin film, laminated on its surface) of the polyimide film / substrate laminate obtained in step (b). These layers may be formed directly on the polyimide film (including the one with the second layer laminated on it), or they may be formed on (i.e., indirectly) on top of other layers required for the device after those other layers have been laminated.

[0137] The conductive layer and / or semiconductor layer are selected to match the elements and circuits required by the target electronic device. In such a step (c), when forming at least one of the conductive layer and semiconductor layer, it is also preferable to form at least one of the conductive layer and semiconductor layer on a polyimide film on which an inorganic film has been formed.

[0138] The conductive layer and semiconductor layer include both those formed over the entire surface of the polyimide film and those formed on a portion of the polyimide film. The present invention may proceed immediately to step (d) after step (c), or it may be possible to form at least one layer selected from the conductive layer and semiconductor layer in step (c), then further form a device structure, and then proceed to step (d).

[0139] Furthermore, when manufacturing a TFT liquid crystal display device as a flexible electronic device, the device may be manufactured by forming, for example, metal wiring, TFTs made of amorphous silicon or polysilicon, and transparent pixel electrodes on a polyimide film (polyimide film for flexible display substrates) on which an inorganic film may be formed over the entire surface as needed. The term "TFT" here includes, for example, a gate metal layer, a semiconductor layer such as an amorphous silicon film, a gate insulating layer, wiring connected to the pixel electrodes, etc. Also, when manufacturing a TFT liquid crystal display device, structures necessary for a liquid crystal display can be formed on the TFT by known methods. In addition, transparent electrodes and color filters may be formed on the polyimide film.

[0140] Furthermore, when manufacturing an organic EL display as a flexible electronic device, for example, an organic EL display may be manufactured by forming a transparent electrode, light-emitting layer, hole transport layer, electron transport layer, etc., in addition to a TFT as necessary, on a polyimide film (polyimide film for flexible display substrates) on which an inorganic film is formed over the entire surface as necessary.

[0141] Since the polyimide film of the present invention has particularly excellent heat resistance, the method for forming the circuits, elements, and other structures required for the device is not particularly limited.

[0142] Step (d) is a step of separating the substrate from the polyimide film. As such a separation method, a mechanical peeling method that physically separates the film by applying external force may be used, but it is particularly preferable to use a so-called laser peeling method, which involves irradiating the substrate surface of the polyimide film / substrate laminate with laser light to separate the film, as this method allows for relatively easy separation even when the polyimide film exhibits high adhesion.

[0143] Alternatively, the polyimide film after the substrate has been peeled off may be used as a substrate for a (semi-)product, and the necessary structures or components for the device may be formed or incorporated into it to complete the device.

[0144] As described above, when a flexible electronic device containing a polyimide film is completed, the polyimide film functions as a flexible electronic device substrate within the flexible electronic device. By manufacturing the flexible electronic device of the present invention in this way, it is possible to manufacture a device equipped with a flexible electronic device substrate made of a polyimide film.

[0145] The method for manufacturing flexible electronic devices is not limited to the above method. For example, after manufacturing a polyimide film / substrate laminate by step (b) above, the polyimide film (polyimide film) may be peeled off from the laminate, and then, using the same steps as in step (c) above except for utilizing the polyimide film, at least one layer selected from a conductive layer and a semiconductor layer and the necessary structure may be formed on the polyimide film, thereby manufacturing a (semi)product using the polyimide film as a substrate.

[0146] (Regarding the properties of the polyimide film) The properties of the polyimide film of the present invention (the polyimide film obtained from the polyimide precursor composition of the present invention described above) will be explained below. In the following, for each property of the polyimide film, multiple numerical ranges will be described (listed) in the order of the first range, second range, third range, ..., nth range, and it will be indicated that these first to nth ranges become more preferable in that order (as the numerical value from 1 to n increases).

[0147] The polyimide film (or polyimide constituting the present invention) has excellent heat resistance, with a 0.5% weight loss temperature of 535°C or higher. Furthermore, such a 0.5% weight loss temperature is more preferably 540°C or higher (first range), 545°C or higher (second range), and 550°C or higher (third range), in that order.

[0148] Furthermore, the temperature at which the polyimide film (or the polyimide constituting it) of the present invention loses 1% of its weight is preferably 555°C or higher (first range), and more preferably 560°C or higher (second range), 565°C or higher (third range), and 570°C or higher (fourth range).

[0149] In this specification, the 0.5% weight loss temperature and the 1% weight loss temperature are determined by using a polyimide film with a thickness of approximately 10 μm as a test specimen, and measuring the weight curve obtained by heating the film from 25°C to 600°C at a heating rate of 10°C / min in a nitrogen stream, with the weight at 150°C being 100%, and measuring the temperatures at which the weight loss reaches 0.5% and 1%, respectively.

[0150] Regarding the polyimide film of the present invention, the transmittance of 450 nm light (450 nm light transmittance) of the polyimide film when measured with a thickness of 10 μm is 73% or more. The 450 nm light transmittance of such a polyimide film is more preferably 74% or more (first range) and 75% or more (second range). Such a 450 nm light transmittance can be determined by measuring it using a UV-Vis spectrophotometer / V-650DS (manufactured by JASCO).

[0151] The silicon content in the polyimide film of the present invention is preferably 2.0 parts by mass or more (first range) per 100 parts by mass of the polyimide film, more preferably 2.5 parts by mass or more (second range), and more preferably 3.0 parts by mass or more (third range). Furthermore, the silicon content in the polyimide film is preferably 6.0 parts by mass or less per 100 parts by mass of the polyimide film. In this specification, the silicon content in the polyimide film is determined by placing the polyimide film and acid in a decomposition container, sealing it tightly, irradiating it with microwaves for thermal decomposition, and then adding ultrapure water to a fixed volume. The solution obtained is used as the test solution and measured using an ICP-AES / ICPE9820 (manufactured by Shimadzu Corporation).

[0152] Furthermore, regarding the polyimide film of the present invention, the yellowness (YI) of the polyimide film when measured with a thickness of 10 μm is preferably 23 or less (first range), more preferably 22 or less (second range), 21 or less (third range), 20 or less (fourth range), and 19 or less (fifth range), in that order. Also, it is preferable that the yellowness (YI) is 0 or greater. Such a YI value can be determined by measuring a polyimide film with a thickness of 10 μm and a size of 5 cm square using a UV-Vis spectrophotometer / V-650DS (manufactured by JASCO Corporation) in accordance with the ASTM E313 standard, with a light source of D65 and a field of view of 2°.

[0153] Furthermore, the haze value of the polyimide film of the present invention, when measured with a film thickness of 10 μm, is preferably less than 1.0% (first range), and more preferably in the order of 0.9% or less (second range), 0.8% or less (third range), 0.7% or less (fourth range), and 0.6% or less (fifth range). Such haze values ​​can be determined by measuring them using a turbidimeter (for example, NDH2000 manufactured by Nippon Denshoku Industries) in accordance with the JIS K7136 standard.

[0154] Depending on the application, the polyimide film of the present invention may require high adhesion to the substrate. Such adhesion can be evaluated by peel strength. When the peel strength between the polyimide film and the substrate in a polyimide film / substrate laminate is measured in accordance with JIS K6854-1, the magnitude of the peel strength measured in a 90° peel test at a tensile speed of 2 mm / min is preferably 3 gf / cm (0.029 N / cm) or more (first range), and more preferably 5 gf / cm (0.049 N / cm) or more (second range), and 7 gf / cm (0.069 N / cm) or more (third range). Furthermore, the upper limit of the magnitude of the peel strength is usually 5 kgf / cm (49.0 N / cm) or less, preferably 3 kgf / cm (29.4 N / cm) or less. Peel strength is usually measured in air or atmosphere. Furthermore, this peel strength can be determined by measuring the peel strength in the 90° direction in air under conditions of a tensile speed of 2 mm / min using the TENSILON RTA-500 manufactured by Orientec Co., Ltd.

[0155] Furthermore, in the present invention, as described above, it is preferable that the polyimide film / substrate laminate has little warping, and the properties of the polyimide film can be evaluated by the residual stress between the polyimide film and the silicon substrate in the polyimide film / silicon substrate (wafer) laminate. Details of the measurement are described in Japanese Patent No. 6798633. However, the polyimide film is assumed to be in a dry state and placed at 23°C. The residual stress evaluated in this way is preferably 25 MPa or less (first range), more preferably 20 MPa or less (second range), and more preferably 15 MPa or less (third range).

[0156] The polyimide film of the present invention can have an extremely low coefficient of linear expansion (CTE) depending on the application. In one preferred embodiment of the polyimide film of the present invention, the coefficient of linear expansion of the polyimide film from 100°C to 300°C, measured on a film with a thickness of 10 μm, is preferably 20 ppm / K or less (first range), and more preferably 18 ppm / K or less (second range), 17 ppm / K or less (third range), 16 ppm / K or less (fourth range), and 15 ppm / K or less (fifth range).

[0157] Furthermore, in a preferred embodiment of the polyimide film of the present invention, the coefficient of linear expansion of the polyimide film from 100°C to 400°C, when measured with a film thickness of 10 μm, is preferably 20 ppm / K or less (first range), and more preferably 18 ppm / K or less (second range), 17 ppm / K or less (third range), 16 ppm / K or less (fourth range), and 15 ppm / K or less (fifth range). Such CTE can be determined by cutting a polyimide film with a thickness of approximately 10 μm into strips with a width of 4 mm to make test pieces, and using a TMA / SS6100 (manufactured by SII Nanotechnology Co., Ltd.), cooling from 400°C to 50°C at a chuck length of 15 mm, a load of 2 g, and a cooling rate of 20°C / min, and calculating the coefficient of linear expansion for the above temperature range (100°C to 300°C range and 100°C to 400°C range) from the obtained TMA curve.

[0158] In a preferred embodiment of the polyimide film of the present invention, the glass transition temperature (Tg) of the polyimide film (or the polyimide constituting it) is preferably 280°C or higher, more preferably 290°C or higher, even more preferably 300°C or higher, and even more preferably 310°C or higher. Such a glass transition temperature (Tg) can be determined from the inflection point of the obtained TMA curve using a thermomechanical analyzer (TMA).

[0159] The polyimide film of the present invention can also exhibit a very high modulus of elasticity depending on the application. The modulus of elasticity of such a polyimide film is preferably 5.5 GPa or higher (first range), and more preferably in the order of 5.9 GPa or higher (second range), 6.1 GPa or higher (third range), 6.3 GPa or higher (fourth range), 6.5 GPa or higher (fifth range), 6.7 GPa or higher (sixth range), and 6.8 GPa or higher (seventh range). The modulus of elasticity can be obtained from a film with a thickness of, for example, 8 to 12 μm.

[0160] Furthermore, in a preferred embodiment of the polyimide film of the present invention, the elongation at the breaking point of the polyimide film is preferably 10% or more (first range) when measured for a film with a thickness of 10 μm, and more preferably 20% or more (second range), 30% or more (third range), and 40% or more (fourth range).

[0161] Furthermore, in a preferred embodiment of the polyimide film of the present invention, the tensile strength of the polyimide film is preferably 320 MPa or higher (first range), and more preferably 330 MPa or higher (second range), 350 MPa or higher (third range), 370 MPa or higher (fourth range), and 380 MPa or higher (fifth range). The tensile strength can be a value obtained from a film with a thickness of, for example, 5 to 100 μm.

[0162] The modulus of elasticity, elongation at break, and breaking strength can each be determined by punching out a dumbbell-shaped test specimen from a polyimide film with a thickness of approximately 10 μm according to the IEC 450 standard, and measuring them using a TENSILON manufactured by ORIENTEC Corporation with a chuck length of 30 mm and a tensile speed of 2 mm / min.

[0163] The polyimide film obtained from the polyimide precursor composition of the present invention and the polyimide film / substrate laminate using the same have been described above. Now, another embodiment of the polyimide film of the present invention will be described below.

[0164] Another embodiment of the polyimide film of the present invention is a polyimide film obtained from a polyimide precursor that contains repeating units represented by the following formula (1) and satisfies the following (i) and (ii) (preferably, a polyimide film obtained from a polyimide precursor composition containing the polyimide precursor), wherein the silicon content in the polyimide film is 2.0 parts by mass or more per 100 parts by mass of the polyimide film, and the 0.5% weight loss temperature is 535°C or higher.

[0165]

[0166] [In formula (1), X １Y is a tetravalent aliphatic group or a tetravalent aromatic group. １ R is a divalent aliphatic group or a divalent aromatic group. １ and R ２ Each of these is independently a hydrogen atom, a C1-C6 alkyl group, or a C3-C9 alkylsilyl group.

[0167] (i) X present in the polyimide precursor １ At least 50 mol% of the total amount is a tetravalent aromatic group represented by the following formula (1-1) (Note that the polyimide precursor contains a repeating unit represented by formula (1) and at least one of the two amide structures in formula (1) is -COOR １ and / or - COOR ２ If there are repeating units that react with and imide-formed, then X present in the polyimide precursor １ The total amount of X in the repeating unit represented by formula (1) above １ And, at least one of the two amide structures in formula (1) is -COOR １ and / or - COOR ２ X in the repeating unit reacts with and imidizes １ All X contained in the precursor, including １ (This refers to the total amount.)

[0168]

[0169] (ii) Y present in the polyimide precursor １ More than 50 mol% of the total amount is a p-phenylene group (Note that the polyimide precursor contains a repeating unit represented by formula (1) and at least one of the two amide structures in formula (1) is -COOR １ and / or - COOR ２ If there are repeating units that react with and imide-formed, Y present in the polyimide precursor １ The total amount of Y in the repeating unit represented by formula (1) above １ And, at least one of the two amide structures in formula (1) is -COOR １ and / or - COOR ２ Y in the repeating unit reacts with and imidizes１ All Y contained in the precursor, including １ (This refers to the total amount.)

[0170] The "polyimide precursor" referred to herein is the same as the "polyimide precursor" described in the polyimide precursor composition of the present invention described above, and its preferred conditions are also the same. Therefore, the repeating unit represented by formula (1), (i) and (ii), and other preferred conditions are all the same as those of the polyimide precursor contained in the polyimide precursor composition of the present invention described above.

[0171] In a polyimide film of this type, it is necessary to satisfy the condition that the silicon content in the polyimide film is 2.0 parts by mass or more per 100 parts by mass of the polyimide film (hereinafter, for convenience, this may be simply referred to as "condition (A)"). By setting the silicon content to 2.0 parts by mass or more, it is possible to greatly improve transparency. Furthermore, it is preferable that the silicon content in the polyimide film be 2.5 parts by mass or more (more preferably 3.0 parts by mass or more) per 100 parts by mass of the polyimide film. Furthermore, it is preferable that the silicon content in the polyimide film be 6.0 parts by mass or less per 100 parts by mass of the polyimide film.

[0172] Furthermore, a polyimide film of this type must satisfy the condition that the 0.5% weight loss temperature is 535°C or higher (hereinafter, for convenience, this will sometimes be simply referred to as "condition (B)"). By setting the 0.5% weight loss temperature to 535°C or higher, it is possible to make the film exhibit high heat resistance. Moreover, it is even more preferable that such a 0.5% weight loss temperature be 540°C or higher (more preferably 545°C or higher, and particularly preferably 550°C or higher).

[0173] Furthermore, the polyimide film of the present invention that satisfies conditions (A) and (B) is preferably a polyimide film obtained from the polyimide precursor composition of the present invention, from the viewpoint that it is possible to efficiently satisfy the above conditions. In this case, a polyimide film in a form that satisfies these conditions can be said to be a preferred embodiment of the aforementioned polyimide film of the present invention obtained from the polyimide precursor composition of the present invention. Also, there are no particular limitations on the method for producing a polyimide film in a form that satisfies conditions (A) and (B), but a method similar to the method for producing the aforementioned polyimide film of the present invention (a polyimide film obtained from the polyimide precursor composition of the present invention) can be employed, except that the production conditions are appropriately selected so that the silicon content in the polyimide film is 2.0 parts by mass or more per 100 parts by mass of the polyimide film. The conditions for making the silicon content in the polyimide film 2.0 parts by mass or more per 100 parts by mass of the polyimide film can be easily adjusted by appropriately changing the heating temperature, heating time, etc., depending on the type of alkoxysilane contained in the composition and its content when producing a polyimide film using the polyimide precursor composition of the present invention.

[0174] Furthermore, for a polyimide film that satisfies the above conditions (A) and (B), it is preferable that the content of the imidazole compound in the polyimide film is 1000 ppm or less, from the viewpoint of preventing a decrease in heat resistance.

[0175] Furthermore, the properties of a polyimide film that satisfies conditions (A) and (B) above are preferably similar to those described in the section "About the properties of polyimide film" above, except that the silicon content in the polyimide film must be 2.0 parts by mass or more per 100 parts by mass of the polyimide film (it is also preferable that the conditions for the preferred properties are the same).

[0176] <Regarding the Uses of Polyimide Films> The polyimide film of the present invention is suitably usable for flexible electronic devices. Furthermore, the uses of the polyimide film of the present invention are not limited to flexible electronic devices, and it can be appropriately used for other applications, such as films for copper (or metal) clad laminates.

[0177] The present invention will be described more specifically below based on examples and comparative examples, but the present invention is not limited to the following examples.

[0178] <Evaluation Methods for Polyimide Films> First, the evaluation methods for the polyimide films obtained in the following examples will be explained.

[0179] [450nm light transmittance] A polyimide film with a thickness of approximately 10 μm (10 μm ± 1 μm) was used as a test specimen, and the light transmittance at 450 nm (450nm light transmittance) was measured using a UV-Vis spectrophotometer / V-650DS (manufactured by JASCO). In this application, a 450nm light transmittance of 73% or higher is considered to indicate high level of transparency.

[0180] [0.5% Weight Loss Temperature] A polyimide film with a thickness of approximately 10 μm (10 μm ± 1 μm) was used as a test specimen. Using a calorimeter (TA Instruments, Q5000IR), the weight curve was measured while the film was heated from 25°C to 600°C at a heating rate of 10°C / min in a nitrogen stream. From the obtained weight curve, the temperature at which the weight decreased by 0.5% (0.5% weight loss temperature), with the weight at 150°C being 100%, was determined. In this application, a 0.5% weight loss temperature of 535°C or higher is considered to indicate a higher level of heat resistance.

[0181] [Silicon content in polyimide film] A polyimide film with a thickness of approximately 10 μm (10 μm ± 1 μm) was used as a test specimen. The test specimen and acid were placed in a decomposition container, sealed tightly, and decomposed by heating with microwave irradiation. The solution obtained by diluting to a fixed volume with ultrapure water was used as the test solution, and the silicon content per 100 parts by mass of the polyimide film was measured using an ICP-AES / ICPE9820 (manufactured by Shimadzu Corporation).

[0182] <Raw Materials> Next, the names and abbreviations of the compounds used as raw materials in the examples and comparative examples will be explained. In the text of the examples and comparative examples and in Tables 1 to 4, the compounds used as raw materials will be expressed using the abbreviations explained below. [Tetracarboxylic acid dianhydrides] ・s-BPDA: 3,3',4,4'-biphenyltetracarboxylic acid dianhydride ・ODPA: 4,4'-oxydiphthalic acid dianhydride ・a-BPDA: 2,3,3',4'-biphenyltetracarboxylic acid dianhydride [Diamines] ・PPD: p-phenylenediamine ・BAFL: 9,9-bis(4-aminophenyl)fluorene ・4,4'-DDS: 4,4'-diaminodiphenylsulfone [Imidazole compounds] ・2-Pz: 2-phenylimidazole ・1,2-DMz: 1,2-dimethylimidazole [Alkoxysilanes] ・Silane compound (A): Phenyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., product name: KBM-103) ・Silane compound (B): Phenyltriethoxysilane (manufactured by Tokyo Chemical Industry Co., Ltd.) • Silane compound (C): Trimethoxy(1-naphthyl)silane (manufactured by Tokyo Chemical Industry Co., Ltd.) [solvent] • NMP: N-methyl-2-pyrrolidone

[0183] (Example 1) [Preparation process for polyimide precursor composition] First, 1.08 g (10 mmol) of PPD as diamine was added to a reaction vessel purged with nitrogen gas. Then, 28.17 g of NMP, the solvent, was added so that the total mass of monomers used in the production of the polyimide precursor (sum of diamine and tetracarboxylic dianhydride) was 12.5% ​​by mass. The mixture was stirred at room temperature (approximately 23°C) for 1 hour to obtain a solution of diamine. Next, 2.94 g (10 mmol) of s-BPDA as tetracarboxylic dianhydride was gradually added to the obtained solution of diamine. The mixture was then stirred at room temperature (approximately 23°C) for 6 hours to react the diamine and tetracarboxylic dianhydride in the solution to form a polyimide precursor (polyamic acid), thereby obtaining a homogeneous and viscous polyimide precursor solution (polyamic acid solution).

[0184] Next, 2-pz was dissolved in 4 times its mass of NMP to obtain a homogeneous solution of 2-pz with a solid content concentration of 20% by mass.

[0185] Next, the imidazole compound solution and the polyimide precursor solution were mixed so that the ratio of the molar amount of the imidazole compound to the total molar amount of repeating units of the polyimide precursor (= ([molar amount of imidazole compound / [total molar amount of repeating units]) × 100, unit: mol%)) was as shown in Table 1. The total molar amount of repeating units was calculated from the amount of monomer used. Next, the silane compound (A) was added to the resulting mixture as an alkoxysilane in a ratio of 20 parts by mass when the mass of the polyimide precursor contained in the final composition (the total mass of polyimide obtained when polyimide is produced from the polyimide precursor (total amount) in the composition by completely imidizing all the repeating units in the polyimide precursor contained in the final composition) was 100 parts by mass, and the mixture was stirred at room temperature for 3 hours to obtain a homogeneous and viscous polyimide precursor composition. The solvent content in the composition was 85.6% by mass.

[0186] [Manufacturing Process for Polyimide Film] First, a circular glass substrate (Eagle-XG®, manufactured by Corning Corporation) with a diameter of 6 inches (500 μm thickness) was prepared as the substrate. Next, a polyimide precursor composition was applied onto the glass substrate using a spin coater, and the mixture was heated on the glass substrate from room temperature to 450°C under a nitrogen atmosphere (oxygen concentration of 200 ppm or less) to perform thermal imidization, thereby obtaining a polyimide film / substrate laminate.

[0187] After obtaining the laminate in this manner, the laminate was immersed in 40°C water to peel the polyimide film from the glass substrate, and then dried to obtain a polyimide film. The thickness of the polyimide film obtained in this manner was approximately 10 μm. The properties of the obtained polyimide film were evaluated using the evaluation method described above. The results are shown in Table 1.

[0188] (Examples 2-25) First, polyimide precursor compositions were manufactured using the same process as described in Example 1's "Preparation Process for Polyimide Precursor Composition" except that the types and amounts of components used were changed to achieve the compositions (amounts) shown in Tables 1-3. Next, polyimide films (film thickness: approximately 10 μm) were manufactured using the same process as described in Example 1's "Production Process for Polyimide Film" except that the polyimide precursor compositions obtained in this way were used. Furthermore, the properties of the polyimide films obtained in each example were evaluated using the method described above, and the results are shown in Tables 1-3.

[0189] Regarding the manufacturing methods used in each example, to give a specific example using Example 9, in Example 9, instead of using PPD (10 mmol) alone as the diamine, a mixture of PPD (9 mmol) and BAFL (1 mmol) was used, and instead of using 20 parts by mass of alkoxysilane when the mass of the polyimide precursor in terms of polyimide equivalent to 100 parts by mass, 5 parts by mass were used. Other than these, the same process as the "Preparation process for polyimide precursor composition" described in Example 1 was adopted to produce the polyimide precursor composition, and a polyimide film (film thickness: approximately 10 μm) was obtained by adopting the same process as the "Production process for polyimide film" described in Example 1, except that the polyimide precursor composition was used.

[0190] (Comparative Example 1) First, a polyimide precursor solution (polyamic acid solution) was prepared by using monomers to obtain the composition (amounts) shown in Table 4, without using imidazole compounds and alkoxysilanes, and by adopting only the steps in the "Preparation Step for Polyimide Precursor Composition" described in Example 1 up to obtaining a "uniform and viscous polyimide precursor solution (polyamic acid solution)". This solution was then used as the comparative polyimide precursor composition. Next, a polyimide film (film thickness: approximately 10 μm) was manufactured by adopting the same steps as the "Production Step for Polyimide Film" described in Example 1, except that the polyimide precursor composition obtained in this way was used. The properties of the obtained polyimide film were evaluated using the method described above, and the results are shown in Table 4.

[0191] (Comparative Example 2) First, without adding alkoxysilane, a mixture of the imidazole compound solution and the polyimide precursor solution was prepared by following the same procedure as in the "Preparation of Polyimide Precursor Composition" described in Example 1, except that the mixture was stirred at room temperature for 3 hours during the mixing step. This mixture was used as the comparative polyimide precursor composition. Next, a polyimide film (film thickness: approximately 10 μm) was manufactured by following the same procedure as in the "Production of Polyimide Film" described in Example 1, except that the polyimide precursor composition obtained in this way was used. The properties of the obtained polyimide film were evaluated using the method described above, and the results are shown in Table 4.

[0192] (Comparative Examples 3-6) First, a mixture of polyimide precursor solution and alkoxysilane was prepared by employing the same procedure as the "Preparation of Polyimide Precursor Composition" described in Example 1, except that the imidazole compound was not added (the step of mixing the imidazole compound solution with the polyimide precursor solution was not performed) and the amount of alkoxysilane was changed to the amount shown in Table 4. This mixture was then used as the comparative polyimide precursor composition. Next, a polyimide film (film thickness: approximately 10 μm) was manufactured by employing the same procedure as the "Production of Polyimide Film" described in Example 1, except that the polyimide precursor composition obtained in this way was used. The properties of the obtained polyimide film were evaluated using the method described above, and the results are shown in Table 4.

[0193] (Comparative Example 7) First, a polyimide precursor solution (polyamic acid solution) was prepared by using monomers to obtain the composition (amount) shown in Table 4, without using imidazole compounds and alkoxysilanes, and by adopting only the steps in the "Preparation Step for Polyimide Precursor Composition" described in Example 1 up to obtaining a "uniform and viscous polyimide precursor solution (polyamic acid solution)," except for changing the type of monomer. This solution was then used as the comparative polyimide precursor composition. A polyimide film (film thickness: approximately 10 μm) was manufactured by adopting the same steps as the "Production Step for Polyimide Film" described in Example 1, except for using the polyimide precursor composition obtained in this way. The properties of the obtained polyimide film were evaluated using the method described above, and the results are shown in Table 4.

[0194] (Comparative Example 8) First, monomers were used to obtain the composition (amounts) shown in Table 4, and the same process as the "Preparation of Polyimide Precursor Composition" described in Example 1 was adopted, except that the amount of alkoxysilane was changed to the amount shown in Table 4, without adding an imidazole compound (the step of mixing the imidazole compound solution with the polyimide precursor solution was not performed), and this mixture of polyimide precursor solution and alkoxysilane was prepared. This mixture was then used as the comparative polyimide precursor composition. A polyimide film (film thickness: approximately 10 μm) was manufactured using the same process as the "Production of Polyimide Film" described in Example 1, except that the polyimide precursor composition obtained in this way was used. The properties of the obtained polyimide film were evaluated using the method described above, and the results are shown in Table 4.

[0195] (Comparative Example 9) First, a polyimide film (film thickness: approximately 10 μm) was manufactured in the same manner as in Comparative Example 2, except that the types and amounts (amounts used) of the components used were changed to achieve the composition (amounts) shown in Table 4. The properties of the obtained polyimide film were evaluated using the method described above, and the results are shown in Table 4.

[0196] (Comparative Examples 10-11) First, polyimide films (film thickness: approximately 10 μm) were manufactured in the same manner as in Comparative Example 1, except that the types and amounts (amounts used) of the components used were changed to achieve the compositions (amounts) shown in Table 4. The properties of the obtained polyimide films were evaluated using the method described above, and the results are shown in Table 4.

[0197]

[0198]

[0199]

[0200]

[0201] As is clear from the results shown in Tables 1 to 4, when the polyimide precursor composition was a composition containing a polyimide precursor, an imidazole compound, and an alkoxysilane (Examples 1 to 25), the resulting polyimide films (corresponding to the polyimide films of the present invention) all had a transmittance of 73% or higher for light at 450 nm (450 nm transmittance), confirming a high level of transparency. Furthermore, the polyimide films obtained in Examples 1 to 25 (corresponding to the polyimide films of the present invention) all had a 0.5% weight loss temperature of 535°C or higher, confirming a high level of heat resistance.

[0202] In contrast, when the polyimide precursor composition did not contain alkoxysilane and imidazole compounds, and the polyamic acid solution was used directly as the polyimide precursor composition (Comparative Examples 1, 7, 10, and 11), the 450 nm transmittance of the resulting polyimide film was 71% or less (70% or less in Comparative Examples 1, 7, and 10). Furthermore, when the polyimide precursor composition used in the production of the polyimide film did not contain alkoxysilane, and the composition consisted of a polyimide precursor and an imidazole compound (Comparative Examples 2 and 9), the transmittance to light at 450 nm (450 nm transmittance) was 70% (Comparative Example 2) and 69% (Comparative Example 9), respectively. Furthermore, when the polyimide precursor composition used in the production of polyimide films did not contain an imidazole compound, and the composition consisted of a polyimide precursor and an alkoxysilane (Comparative Examples 3-6), the transmittance to 450 nm light (450 nm transmittance) was 72% or less (Comparative Examples 3-4 and 6), or the 0.5% weight loss temperature was 530°C or less (Comparative Examples 4-6), making it impossible to achieve a high level of compatibility between transmittance to 450 nm light and the 0.5% weight loss temperature. When the polyimide precursor composition used in the production of polyimide films did not contain an imidazole compound, and the composition consisted of a polyimide precursor and an alkoxysilane, the 0.5% weight loss temperature was 530°C or less when the alkoxysilane content was 50 parts by mass, 75 parts by mass, and 100 parts by mass, respectively, based on a polyimide equivalent mass of 100 parts by mass of the polyimide precursor (Comparative Examples 4-6).

[0203] Furthermore, when PPD and BAFL were used as the diamines, and the polyimide precursor composition did not contain an imidazole compound, and the composition consisted of a polyimide precursor, an alkoxysilane, and a solvent (NMP) (Comparative Example 8), the 0.5% weight loss temperature was 528°C.

[0204] These results indicate that when the polyimide precursor composition is a composition containing a polyimide precursor, an imidazole compound, and an alkoxysilane, and a polyimide film is manufactured using this composition (Examples 1 to 25), it is possible to achieve both a higher level of transparency and a higher level of heat resistance.

[0205] As described above, the present invention makes it possible to provide a polyimide precursor composition that enables the production of a polyimide film having a high level of transparency and a higher level of heat resistance. Furthermore, it makes it possible to provide a polyimide film obtained using the polyimide precursor composition, as well as a polyimide film / substrate laminate, a flexible electronic device, and a flexible electronic device substrate using the polyimide film.

[0206] Therefore, the polyimide precursor composition of the present invention is particularly suitable for use in the production of polyimide films for flexible electronic devices (for example, flexible displays such as liquid crystal displays and organic EL displays; display devices such as electronic paper; and light-receiving devices such as solar cells and CMOS).

Claims

1. A polyimide precursor composition comprising a polyimide precursor containing repeating units represented by the following formula (1) and satisfying the following (i) and (ii), an alkoxysilane, and an imidazole compound. [In formula (1), X １ Y is a tetravalent aliphatic group or a tetravalent aromatic group. １ R is a divalent aliphatic group or a divalent aromatic group. １ and R ２ Each of these is independently a hydrogen atom, a C1-C6 alkyl group, or a C3-C9 alkylsilyl group. ] (i) X present in the polyimide precursor １ At least 50 mol% of the total amount consists of tetravalent aromatic groups represented by the following formula (1-1). (ii) Y present in the polyimide precursor １ More than 50 mol% of the total amount consists of p-phenylene groups.

2. X present in the polyimide precursor １ The polyimide precursor composition according to claim 1, wherein 1 to 30 mol% of the total amount of １ is a tetravalent aromatic group represented by the following formula (1-2). [In formula (1-2), R １０ and R １１ are each independently a single bond or a divalent organic group.] 3. Y present in the polyimide precursor １ The polyimide precursor composition according to claim 1, wherein 1 to 30 mol% of the total amount is a divalent aromatic group represented by the following formula (1-3). [In formula (1-3), R １２ and R １３ Each of these is independently a single-bonded or divalent organic group.

4. The polyimide precursor composition according to claim 1, wherein the alkoxysilane is an aryltrialkoxysilane.

5. The polyimide precursor composition according to claim 1, wherein the content of the alkoxysilane is 5 to 150 parts by mass when the mass of the polyimide precursor in terms of polyimide is 100 parts by mass.

6. A polyimide film obtained from the polyimide precursor composition according to any one of claims 1 to 5.

7. A polyimide film / substrate laminate having the polyimide film according to claim 6 and a substrate.

8. A flexible electronic device comprising the polyimide film described in claim 6.

9. A flexible electronic device substrate made of the polyimide film described in claim 6.

10. A polyimide film obtained from a polyimide precursor composition containing a repeating unit represented by the following formula (1) and a polyimide precursor satisfying the following (i) and (ii), wherein the silicon content in the polyimide film is 2.0 parts by mass or more per 100 parts by mass of the polyimide film, and the 0.5% weight loss temperature is 535°C or higher. [In formula (1), X １ Y is a tetravalent aliphatic group or a tetravalent aromatic group. １ R is a divalent aliphatic group or a divalent aromatic group. １ and R ２ Each of these is independently a hydrogen atom, a C1-C6 alkyl group, or a C3-C9 alkylsilyl group. ] (i) X present in the polyimide precursor １ At least 50 mol% of the total amount consists of tetravalent aromatic groups represented by the following formula (1-1). (ii) Y present in the polyimide precursor １ More than 50 mol% of the total amount consists of p-phenylene groups.

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