Flexible device substrate-forming composition

Abstract

Provided is a flexible device substrate-forming composition which is transparent even without containing fluorine atoms, has high heat resistance, and can form a resin thin film having good adhesion to an inorganic insulating film when forming an electrode on a polyimide.　This flexible device substrate-forming composition contains component (A) and at least one of component (B) and component (C).　Component (A): A polyimide precursor that does not include fluorine atoms, that has a structure derived from a diamine having a structure represented by formula (0-d) and from a tetracarboxylic dianhydride having a structure represented by formula (0-t) or (0-d) or a derivative thereof, and that also has one or both of a structure derived from a tetracarboxylic dianhydride satisfying condition (i) or a derivative thereof and a structure derived from a diamine satisfying condition (ii). Component (B): An imidization promoter. Component (C): A silane coupling agent.　(Condition (i) and condition (ii) are as described in the description.)

Description

Composition for forming flexible device substrate

[0001] The present invention relates to a polyimide precursor resin composition that can be used to obtain a polyimide film having excellent transparency, a small coefficient of linear thermal expansion, high heat resistance, and excellent adhesion to an inorganic insulating film.The present invention also relates to a polyimide, a polyimide film, and a substrate that have excellent transparency, a small coefficient of linear thermal expansion, high heat resistance, and excellent adhesion to an inorganic insulating film.

[0002] In recent years, the development of thin display devices such as liquid crystal displays (LCDs) and organic electroluminescent displays (OLEDs) has led to demands for thinner, lighter, and more flexible devices. These display devices currently use glass substrates, but replacing the glass material with flexible, lightweight resin materials could enable thinner, lighter, and more flexible devices. Against this backdrop, polyimides have attracted attention as a potential glass replacement and are being actively investigated. In particular, OLEDs, which are easily made flexible because they are constructed by laminating thin films such as hole injection layers and light-emitting layers onto electrodes, have led to the development of flexible OLEDs using polyimide films. These display devices require the formation of various electronic elements, such as inorganic insulating films, thin-film transistors, and transparent electrodes, on a substrate. Therefore, the materials used for the substrate must have high heat resistance (e.g., 400°C or higher) to withstand the process temperatures required for forming these electronic elements. Furthermore, polyimides for these applications must not only be heat-resistant and flexible, but also, in most cases, possess transparency comparable to that of glass.

[0003] Aromatic fluorinated polyimides are widely used as materials with high flexibility, excellent heat resistance, and transparency. However, in recent years, there has been a growing movement to curb their use due to environmental concerns about fluorine atoms.

[0004] Methods have also been proposed for imparting flexibility to the polyimide main chain and introducing bulky side chain groups to inhibit the formation of intramolecular conjugation and charge-transfer complexes, thereby achieving transparency. For example, Patent Document 1 discloses an aromatic polyimide having flexibility imparted to the polymer main chain, and Patent Document 2 discloses a polyimide having bulky side chain groups. While these polyimides have excellent transparency, they may have poor heat resistance or may have poor flexibility due to the bulky side chains, making it difficult to achieve the flex resistance required for flexible displays. When using polyimide as a substrate, a method known as laser lift-off (Patent Document 3) has been considered, in which electronic elements are formed on polyimide formed on a support substrate, and then the polyimide is peeled off from the support substrate by irradiating a laser from the support substrate side. In this case, if the flexibility of the polyimide film is insufficient, problems such as destruction of the display element during peeling and damage to the display element during repeated winding and unwinding of the display element may occur. In contrast, a substrate in which a polyimide film is formed on thin glass has been proposed as a method for achieving both excellent flexibility and low processing costs (Patent Document 4). This document discloses that by forming a polyimide film of several tens of micrometers on a 70-micrometer-thick glass, it is possible to produce a display element with excellent flexibility without the need to peel off the polyimide film using a costly laser lift-off method.

[0005] However, depending on the application, when forming an electrode on polyimide, the adhesion between the inorganic insulating film and polyimide is poor, and the inorganic insulating film may peel off from the polyimide during high-temperature treatment during electrode formation.

[0006] Japanese Patent Application Laid-Open No. 2012-146905 Japanese Patent Application Laid-Open No. 2005-306983 Japanese Patent Application Laid-Open No. 2007-512568 Japanese Patent Application Laid-Open No. 2021-26232

[0007] An object of the present invention is to provide a composition for forming a flexible device substrate, which is transparent and highly heat-resistant even without containing fluorine atoms, and which is capable of forming a resin thin film that has good adhesion to an inorganic insulating film when forming an electrode on a polyimide.

[0008] As a result of extensive research into solving the above problems, the present inventors have found that a composition containing a specific polymer and a specific additive can solve the above problems, and have completed the present invention.

[0009] Accordingly, the present invention provides the following composition for forming a flexible device substrate and flexible device substrate. [1] A composition for forming a flexible device substrate, comprising component (A) and at least one of component (B) and component (C). Component (A): A polyimide precursor containing a tetracarboxylic dianhydride or a derivative thereof having a structure represented by formula (0-t) or (0-d) below and a structure derived from a diamine having a structure represented by formula (0-d) below, and further containing one or both of a structure derived from a tetracarboxylic dianhydride or a derivative thereof satisfying the following condition (i) and a structure derived from a diamine satisfying the following condition (ii), and containing no fluorine atoms; condition (i): The polyimide precursor has two dicarboxylic acid anhydride moieties directly bonded to aromatic rings in the molecule, and, if there are multiple aromatic rings bonded to the dicarboxylic acid anhydride moieties, the aromatic rings bonded to the dicarboxylic acid anhydride moieties are bonded to each other by a single bond, bonded to each other via an aromatic ring, or formed as a fused ring. Condition (ii): The molecule has two amino groups directly bonded to aromatic rings, and when there are multiple aromatic rings bonded to amino groups, the aromatic rings bonded to the amino groups are bonded to each other by a single bond, or via an aromatic ring, or are fused together. (In the formula, the hydrogen atom on the benzene ring may be substituted with a group selected from a halogen atom, an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, and a phenyl group which may have a substituent; the two benzene rings bonded to the 9-position of the fluorene may be bonded to each other by a single bond or an ether bond; and the benzene ring of the fluorene skeleton may be replaced with a naphthalene ring. The dashed line in formula (0-t) represents a bond to the acid anhydride moiety, and the dashed line in formula (0-d) represents a bond to a group having an acid anhydride moiety in the case of a tetracarboxylic dianhydride, or a bond to a group having an amino group in the case of a diamine.) Component (B): imidization accelerator; Component (C): silane coupling agent.

[0010] By using the composition for forming a flexible device substrate of the present invention, it is possible to reproducibly obtain a resin thin film that has excellent adhesion to the substrate and the inorganic insulating film, as well as transparency and heat resistance. In particular, since the above-mentioned adhesion and transparency are well maintained even after the heat treatment in the TFT process, the composition functions as a permanent film that maintains transparency even after the manufacturing process of a flexible electronic device without damaging the circuit, etc. Therefore, the composition for forming a flexible device substrate of the present invention can contribute to simplifying the manufacturing process of a flexible electronic device and improving its yield.

[0011] The present invention will be described in more detail below. The composition for forming a flexible device substrate of the present invention contains component (A) and at least one of component (B) and component (C). Component (A): A polyimide precursor having a tetracarboxylic dianhydride or a derivative thereof having a structure represented by the following formula (0-t) or (0-d) and a structure derived from a diamine having a structure represented by the following formula (0-d), and further having one or both of a structure derived from a tetracarboxylic dianhydride or a derivative thereof satisfying the following condition (i) and a structure derived from a diamine satisfying the following condition (ii), and containing no fluorine atoms; Condition (i): The polyimide precursor has two dicarboxylic acid anhydride moieties directly bonded to an aromatic ring in the molecule, and when there are multiple aromatic rings bonded to the dicarboxylic acid anhydride moieties, the aromatic rings bonded to the dicarboxylic acid anhydride moieties are bonded to each other by a single bond, bonded via an aromatic ring, or formed as a fused ring. Condition (ii): The molecule has two amino groups directly bonded to aromatic rings, and when there are multiple aromatic rings bonded to amino groups, the aromatic rings bonded to the amino groups are bonded to each other by a single bond, or via an aromatic ring, or are fused together. (In the formula, the hydrogen atoms on the benzene rings may be substituted with groups selected from halogen atoms, alkyl groups having 1 to 3 carbon atoms, alkoxy groups having 1 to 3 carbon atoms, and phenyl groups which may have a substituent; the two benzene rings bonded to the 9-position of the fluorene may be bonded together with a single bond or an ether bond; and the benzene rings of the fluorene skeleton may be replaced with naphthalene rings. The dashed line in formula (0-t) represents a bond to the acid anhydride moiety, and the dashed line in formula (0-d) represents a bond to a group having an acid anhydride moiety in the case of a tetracarboxylic dianhydride, or a bond to a group having an amino group in the case of a diamine.) Component (B): imidization accelerator; Component (C): silane coupling agent. Each component will be described in detail below.

[0012] [(A) Polyimide Precursor] The polyimide precursor of component (A) is a polyimide precursor that contains no fluorine atoms and has a structure derived from a tetracarboxylic dianhydride having a structure represented by the above formula (0-t) or (0-d) (in the present invention, this is also referred to as tetracarboxylic dianhydride (t0)) or a derivative thereof and a diamine having a structure represented by the above formula (0-d) (in the present invention, this is also referred to as diamine (d0)), and further has one or both of a structure derived from a tetracarboxylic dianhydride (in the present invention, this is also referred to as tetracarboxylic dianhydride (t1)) or a derivative thereof that satisfies the above condition (i) and a structure derived from a diamine (in the present invention, this is also referred to as diamine (d1)) that satisfies the above condition (ii).

[0013] Examples of the tetracarboxylic acid derivative include tetracarboxylic acid dianhydride, tetracarboxylic acid, tetracarboxylic acid dihalide, tetracarboxylic acid dialkyl ester, tetracarboxylic acid dialkyl ester dihalide, etc. Examples of the substituent of the phenyl group which may have a substituent in formula (0-t) and formula (0-d) include a halogen atom other than a fluorine atom, an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, a cyano group, etc.

[0014] Examples of the tetracarboxylic dianhydride (t0) include compounds represented by the following formulas (t0-1) to (t0-5).

[0015] The diamine (d0) is preferably a compound represented by the following formula (0-d-1): In formula (0-d-1), P １ and P ２ each independently represents a single bond, —O—, —S—, —CO—, or —NR ７ --CO-NR ７ -, -NR ７ —CO— or —NR ７ -CO-NR ７ - represents. ７ represents a hydrogen atom, a monovalent hydrocarbon group having 1 to 10 carbon atoms, a monovalent group in which one or more hydrogen atoms of the hydrocarbon group have been substituted with a halogen atom other than a fluorine atom or a cyano group, or a monovalent thermally labile group. The monovalent thermally labile group may be any group that is substituted with a hydrogen atom by heating, and preferred examples include a tert-butoxycarbonyl group and a 9-fluorenylmethyloxycarbonyl group. １ and Q ２ R each independently represent a divalent aromatic hydrocarbon ring group. The divalent aromatic hydrocarbon ring group is a group obtained by removing two hydrogen atoms from the ring portion of a substituted or unsubstituted aromatic hydrocarbon ring. Examples of the aromatic hydrocarbon ring include a benzene ring and a naphthalene ring, and a benzene ring is preferred. １ and R ２ each independently represents a hydrogen atom, a halogen atom other than a fluorine atom, an alkyl group having 1 to 3 carbon atoms, or an alkoxy group having 1 to 3 carbon atoms, or R １ and R ２ and are combined together to form *-X-* (X represents a single bond or an oxygen atom, and * represents a bond to the benzene ring). ３ and R ４ R each independently represents a halogen atom other than a fluorine atom, an alkyl group having 1 to 3 carbon atoms, or an alkoxy group having 1 to 3 carbon atoms. ５ and R ６ each independently represents a halogen atom other than a fluorine atom, an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, or a phenyl group. １ and n ２are each independently an integer of 0 to 2. ３ and n ４ are each independently an integer of 0 to 3. ５ and n ６ are each independently an integer of 0 to 4. ７ and n ８ are each independently an integer of 0 to 1. １ , P ２ , Q １ , Q ２ , R ３ , R ４ , R ５ , R ６ and R ７ If there are multiple of each, multiple P １ , P ２ , Q １ , Q ２ , R ３ , R ４ , R ５ , R ６ and R ７ may be the same or different from each other.

[0016] Examples of the diamine (d0) include compounds represented by the following formulas (d0-1) to (d0-22).

[0017] The tetracarboxylic acid dianhydride (t1) is not particularly limited as long as it satisfies the above condition (i), but aromatic tetracarboxylic acid dianhydrides containing 1 to 5 benzene rings are preferred.

[0018] Specific examples thereof include pyromellitic dianhydride, benzene-1,2,3,4-tetracarboxylic dianhydride, naphthalene-1,2,3,4-tetracarboxylic dianhydride, naphthalene-1,2,5,6-tetracarboxylic dianhydride, naphthalene-1,2,6,7-tetracarboxylic dianhydride, naphthalene-1,2,7,8-tetracarboxylic dianhydride, naphthalene-2,3,5,6-tetracarboxylic dianhydride, and naphthalene-2,3,6,7-tetracarboxylic dianhydride. tetracarboxylic dianhydride, naphthalene-1,4,5,8-tetracarboxylic dianhydride, biphenyl-2,2',3,3'-tetracarboxylic dianhydride, biphenyl-2,3,3',4'-tetracarboxylic dianhydride, biphenyl-3,3',4,4'-tetracarboxylic dianhydride, anthracene-1,2,3,4-tetracarboxylic dianhydride, anthracene-1,2,5,6-tetracarboxylic dianhydride, anthracene-1,2,6,7-tetracarboxylic dianhydride anthracene-1,2,7,8-tetracarboxylic dianhydride, anthracene-2,3,6,7-tetracarboxylic dianhydride, phenanthrene-1,2,3,4-tetracarboxylic dianhydride, phenanthrene-1,2,5,6-tetracarboxylic dianhydride, phenanthrene-1,2,6,7-tetracarboxylic dianhydride, phenanthrene-1,2,7,8-tetracarboxylic dianhydride, phenanthrene-1,2,9, phenanthrene-10-tetracarboxylic dianhydride, phenanthrene-2,3,5,6-tetracarboxylic dianhydride, phenanthrene-2,3,6,7-tetracarboxylic dianhydride, phenanthrene-2,3,9,10-tetracarboxylic dianhydride, phenanthrene-3,4,5,6-tetracarboxylic dianhydride, phenanthrene-3,4,9,10-tetracarboxylic dianhydride, and the like, and these may be used alone or in combination of two or more.

[0019] Among these, from the viewpoint of improving the function of the obtained film, aromatic carboxylic acid dianhydrides having one or two benzene rings are preferred. Specifically, one or more aromatic tetracarboxylic acid dianhydrides represented by any one of formulas (C1) to (C12) are preferred, and one or more aromatic tetracarboxylic acid dianhydrides represented by any one of formulas (C1) to (C7) and (C9) to (C11) are more preferred.

[0020]

[0021] Other tetracarboxylic dianhydrides may be used in combination with the tetracarboxylic dianhydride (t1) as long as they do not adversely affect the resulting resin layer. Specific examples of other tetracarboxylic dianhydrides include alicyclic tetracarboxylic dianhydrides such as 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 2,3,4,5-tetrahydrofurantetracarboxylic dianhydride, 1,2,4,5-cyclohexanoic dianhydride, 3,4-dicarboxy-1-cyclohexylsuccinic dianhydride, 3,4-dicarboxy-1,2,3,4-tetrahydro-1-naphthalenesuccinic dianhydride, and bicyclo[3.3.0]octane-2,4,6,8-tetracarboxylic dianhydride.

[0022] In the present invention, when the tetracarboxylic dianhydride (t0) or a derivative thereof is used together with the tetracarboxylic dianhydride (t1) or a derivative thereof, the amount used is preferably 5:95 to 95:5, more preferably 10:90 to 90:10, and even more preferably 20:80 to 80:20, in terms of the molar ratio of (t0):(t1).

[0023] In the present invention, the total amount of the tetracarboxylic dianhydride (t0) or a derivative thereof and the tetracarboxylic dianhydride (t1) or a derivative thereof used is preferably 70 mol % or more, more preferably 80 mol % or more, even more preferably 90 mol % or more, still more preferably 95 mol % or more, and most preferably 100 mol % of the total tetracarboxylic acid components. By adopting such amounts, a film having excellent adhesion to the substrate and the inorganic insulating film and excellent heat resistance can be obtained with good reproducibility.

[0024] The diamine (d1) is not particularly limited as long as it satisfies the above condition (ii), but is preferably an aromatic diamine containing 1 to 5 benzene rings.

[0025] Specific examples of the diamine (d1) include diamines having one benzene ring such as 1,4-diaminobenzene (p-phenylenediamine), 1,3-diaminobenzene (m-phenylenediamine), 1,2-diaminobenzene (o-phenylenediamine), 2,4-diaminotoluene, 2,5-diaminotoluene, 2,6-diaminotoluene, 4,6-dimethyl-m-phenylenediamine, 2,5-dimethyl-p-phenylenediamine, 2,6-dimethyl-p-phenylenediamine, 2,4,6-trimethyl-1,3-phenylenediamine, and 2,3,5,6-tetramethyl-p-phenylenediamine; 1,2-naphthalenediamine, 1,3-naphthalenediamine, 1,4-naphthalenediamine, 1,5-naphthalenediamine, 1,6-naphthalenediamine, 1,7-naphthalenediamine, 1,8-naphthalenediamine, and 2 Examples of the diamine include, but are not limited to, diamines having two benzene rings such as 1,3-naphthalenediamine, 2,6-naphthalenediamine, 4,4'-biphenyldiamine, 3,3'-dimethylbenzidine, and 2,2'-dimethylbenzidine; and diamines having three benzene rings such as 1,5-diaminoanthracene, 2,6-diaminoanthracene, 9,10-diaminoanthracene, 1,8-diaminophenanthrene, 2,7-diaminophenanthrene, 3,6-diaminophenanthrene, 9,10-diaminophenanthrene, 1,3-bis(3-aminophenyl)benzene, 1,3-bis(4-aminophenyl)benzene, 1,4-bis(3-aminophenyl)benzene, 1,4-bis(4-aminophenyl)benzene, 4,4''-diamino-p-terphenyl, and 4,4''-diamino-m-terphenyl. These may be used alone or in combination of two or more.

[0026] Among these, p-phenylenediamine, m-phenylenediamine, 2,2'-dimethylbenzidine, 4,4''-diamino-p-terphenyl, etc. are preferred from the viewpoint of improving the function of the resulting film.

[0027] Furthermore, other diamines may be used in combination with the diamine (d1) as long as they do not adversely affect the resulting resin layer. Specific examples of other diamines include 1,4-diaminocyclohexane, 1,4-cyclohexanebis(methylamine), 4,4'-diaminodicyclohexylmethane, bis(4-amino-3-methylcyclohexyl)methane, 3(4),8(9)-bis(aminomethyl)tricyclo[5.2.1.0]methylpropane ... 2,6 ]decane, 2,5(6)-bis(aminomethyl)bicyclo[2.2.1]heptane, 1,3-diaminoadamantane, 3,3'-diamino-1,1'-biadamantyl, 1,6-diaminodiamantane (1,6-aminopentacyclo[7.3.1.1 4,12 , 0 2,7 .0 6,11 cycloaliphatic diamines such as tetramethylenediamine and hexamethylenediamine; and the like.

[0028] In the present invention, when the diamine (d1) is used together with the diamine (d0), the amount of use is preferably 5:95 to 95:5, more preferably 10:90 to 90:10, and even more preferably 20:80 to 80:20, in terms of the molar ratio of (d0):(d1).

[0029] In the present invention, the total amount of diamine (d0) and diamine (d1) used in the entire diamine component is preferably 70 mol % or more, more preferably 80 mol % or more, even more preferably 90 mol % or more, and even more preferably 95 mol % or more. By adopting such an amount, a film having excellent adhesion to the substrate and the inorganic insulating film and excellent heat resistance can be obtained with good reproducibility.

[0030] The charging ratio of the diamine component to the tetracarboxylic acid component cannot be generally defined because it is appropriately determined taking into consideration the target molecular weight, molecular weight distribution, the type of diamine, and the type of tetracarboxylic dianhydride or derivative thereof, but the total number of moles of the tetracarboxylic acid components is preferably 0.8 to 1.2 when the total number of moles of the diamine components is 1.0. When the total number of moles of the tetracarboxylic acid components is less than 1.0, i.e., when the total number of moles of the tetracarboxylic acid components is smaller than the number of moles of the diamine components, the polymer will have an amino group structure at its terminal, and when it is greater than 1.0, i.e., when the total number of moles of the tetracarboxylic acid components is greater than the number of moles of the diamine components, the polymer will have a carboxylic acid anhydride or dicarboxylic acid structure at its terminal.

[0031] The organic solvent used in the synthesis of polyamic acid is not particularly limited as long as it does not adversely affect the reaction, and specific examples include m-cresol, 2-pyrrolidone, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, N-vinyl-2-pyrrolidone, N,N-dimethylacetamide, N,N-dimethylformamide, 3-methoxy-N,N-dimethylpropylamide, 3-ethoxy-N,N-dimethylpropylamide, 3-propoxy-N,N-dimethylpropylamide, 3-isopropoxy-N,N-dimethylpropylamide, 3-butoxy-N,N-dimethylpropylamide, 3-sec-butoxy-N,N-dimethylpropylamide, 3-tert-butoxy-N,N-dimethylpropylamide, γ-butyrolactone, etc. The organic solvents may be used alone or in combination of two or more.

[0032] The reaction temperature during synthesis of polyamic acid may be set appropriately within the range from the melting point to the boiling point of the solvent used, and is usually about 0 to 100° C. However, from the viewpoint of preventing imidization in the resulting polyamic acid solution and maintaining a high content of polyamic acid units, the temperature can be preferably about 0 to 70° C., more preferably about 0 to 60° C., and even more preferably about 0 to 50° C. The reaction time cannot be generally determined because it depends on the reaction temperature and the reactivity of the raw materials, but is usually about 1 to 100 hours.

[0033] The weight-average molecular weight of the polyamic acid thus obtained is usually about 5,000 to 500,000, but from the viewpoint of improving the functionality of the resulting film, it is preferably about 6,000 to 200,000, more preferably about 7,000 to 150,000. In the present invention, the weight-average molecular weight is a polystyrene-equivalent value measured by gel permeation chromatography (GPC).

[0034] [(B) Imidization Accelerator] The imidization accelerator, which is the component (B), is a compound for accelerating imidization, and is preferably a compound having a basic site (e.g., a primary amino group, an aliphatic heterocycle (e.g., a pyrrolidine skeleton), an aromatic heterocycle (e.g., an imidazole ring, an indole ring), or a guanidino group), or a compound that generates the basic site upon baking. More preferably, it is a compound that generates the basic site upon baking, and preferred specific examples include amino acids in which some or all of the basic sites of the amino acid are protected with protecting groups, or compounds in which the NH of a nitrogen-containing aromatic heterocycle is protected with a protecting group. Examples of the protecting group for the basic site of the amino acid or nitrogen-containing aromatic heterocycle include carbamate-based protecting groups such as a tert-butoxycarbonyl group or a 9-fluorenylmethoxycarbonyl group. Specific examples of the amino acids include glycine, alanine, cysteine, methionine, asparagine, glutamine, valine, leucine, phenylalanine, tyrosine, tryptophan, proline, hydroxyproline, arginine, histidine, lysine, and ornithine.

[0035] The molecular weight of the compound for promoting imidization may be 2,000 or less, 1,000 or less, or 500 or less.

[0036] More preferred specific examples of the compound for promoting imidization include N-α-(9-fluorenylmethoxycarbonyl)-N-τ-(tert-butoxycarbonyl)-L-histidine, N-α-(tert-butoxycarbonyl)-N-τ-(tert-butoxycarbonyl)-L-histidine, and 1-tert-butoxycarbonylimidazole.

[0037] The content of the compound for promoting imidization contained in the composition of the present invention is preferably 0.1 to 30 parts by mass, more preferably 0.1 to 20 parts by mass, and even more preferably 0.5 to 10 parts by mass, per 100 parts by mass of the polyimide precursor contained in the composition.

[0038] [(C) Silane Coupling Agent] The silane coupling agent is added, for example, for the purpose of improving the adhesion between the resin film and the object to be protected by the resin film (for example, an inorganic insulating film).

[0039] Examples of the silane coupling agent include the following silane compounds: amine-based silane coupling agents such as 3-aminopropyltriethoxysilane, 3-(2-aminoethyl)aminopropyltrimethoxysilane, 3-(2-aminoethyl)aminopropylmethyldimethoxysilane, 3-aminopropyltrimethoxysilane, 3-phenylaminopropyltrimethoxysilane, 3-triethoxysilyl-N-(1,3-dimethyl-butylidene)propylamine, and 3-aminopropyldiethoxymethylsilane; vinyl-based silane coupling agents such as vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris(2-methoxyethoxy)silane, vinylmethyldimethoxysilane, vinyltriacetoxysilane, vinyltriisopropoxysilane, allyltrimethoxysilane, and p-styryltrimethoxysilane; Epoxy-based silane coupling agents such as 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane; methacrylic-based silane coupling agents such as 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, and 3-methacryloxypropyltriethoxysilane; acrylic-based silane coupling agents such as 3-acryloxypropyltrimethoxysilane; ureido-based silane coupling agents such as 3-ureidopropyltriethoxysilane; sulfide-based silane coupling agents such as bis(3-(triethoxysilyl)propyl)disulfide and bis(3-(triethoxysilyl)propyl)tetrasulfide; Mercapto-based silane coupling agents such as 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane, and 3-octanoylthio-1-propyltriethoxysilane; isocyanate-based silane coupling agents such as 3-isocyanatepropyltriethoxysilane and 3-isocyanatepropyltrimethoxysilane, and silane coupling agents in which the isocyanate group is protected with a thermally cleavable group;Aldehyde-based silane coupling agents such as triethoxysilylbutyraldehyde; Carbamate-based silane coupling agents such as triethoxysilylpropylmethylcarbamate and (3-triethoxysilylpropyl)-t-butylcarbamate;

[0040] The molecular weight of the silane coupling agent may be not more than 2000, not more than 1000, or not more than 500. The silane coupling agent may be one type or a combination of two or more types.

[0041] The content of the silane coupling agent is not particularly limited, but is preferably 0.10 parts by mass to 30.0 parts by mass, more preferably 1.0 parts by mass to 15.0 parts by mass, and even more preferably 3.0 parts by mass to 10.0 parts by mass, relative to 100 parts by mass of the polyimide precursor.

[0042] The composition for forming a flexible device substrate of the present invention contains an organic solvent. As this organic solvent, the same as the specific example of the reaction solvent for the above reaction can be used, but it is particularly preferable that the organic solvent contains at least one selected from the group consisting of amides represented by the following formula (S1), amides represented by the formula (S2), and amides represented by the formula (S3), because they dissolve the polyimide precursor of the present invention well and make it easy to prepare a highly uniform composition.

[0043]

[0044] In the above formula, R ３０ ~R ３５ R each independently represents an alkyl group having 1 to 10 carbon atoms. ３６ represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms. b represents an integer of 1 or more, preferably an integer of 1 to 5, and more preferably an integer of 1 to 3. Specific examples of the alkyl group having 1 to 10 carbon atoms include the same as those mentioned above.

[0045] Specific examples of the organic solvents represented by the above formulas (S1) to (S3) include 3-methoxy-N,N-dimethylpropionamide, N,N-dimethylformamide, N,N-dimethylacetamide, N,N-dimethylpropionamide, N,N-dimethylbutanamide, N-methyl-2-pyrrolidone, and N-ethyl-2-pyrrolidone, with N-methyl-2-pyrrolidone being preferred. These organic solvents may be used alone or in combination of two or more.

[0046] A solvent that does not dissolve the polyimide precursor by itself can also be used to prepare the composition, as long as the polyimide precursor does not precipitate. In particular, solvents having low surface tension, such as ethyl cellosolve, butyl cellosolve, ethyl carbitol, butyl carbitol, ethyl carbitol acetate, ethylene glycol, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, 1-butoxy-2-propanol, 1-phenoxy-2-propanol, propylene glycol monoacetate, propylene glycol diacetate, propylene glycol-1-monomethyl ether-2-acetate, propylene glycol-1-monoethyl ether-2-acetate, dipropylene glycol, 2-(2-ethoxypropoxy)propanol, methyl lactate, ethyl lactate, n-propyl lactate, n-butyl lactate, and isoamyl lactate, can be mixed in an appropriate amount. This is known to improve the uniformity of the coating film when applied to the substrate, and can be suitably used in the present invention.

[0047] The flexible device substrate forming composition of the present invention can be prepared by a conventional method. A preferred example of the preparation method is to filter the reaction solution containing the target polyimide precursor obtained by the method described above, and adjust the concentration of the obtained filtrate to a predetermined concentration using the organic solvent described above. By adopting such a method, it is possible to reduce the inclusion of impurities that may cause deterioration in the adhesion, heat resistance, etc. of the resin film produced from the obtained composition, and also to efficiently obtain the flexible device substrate forming composition.

[0048] The concentration of the polyimide precursor in the composition for forming a flexible device substrate of the present invention is set appropriately taking into consideration the thickness of the resin film to be produced, the viscosity of the composition, etc., but is typically about 1 to 30% by mass, preferably about 1 to 20% by mass. By setting such a concentration, a resin film having a thickness of about 0.05 to 5 μm can be reproducibly obtained. The concentration of the polyimide precursor can be adjusted by adjusting the amounts of the diamine component and tetracarboxylic dianhydride component used as raw materials for the polyimide precursor, or by adjusting the amounts of the isolated polyimide precursor when dissolved in a solvent.

[0049] The viscosity of the composition for forming a flexible device substrate of the present invention is set appropriately taking into consideration the thickness of the resin film to be produced, etc., but when the objective is to reproducibly obtain a film having a thickness of about 0.05 to 5 μm, the viscosity is usually about 5 to 10,000 mPa·s at 25° C., and preferably about 10 to 5,000 mPa·s.

[0050] Here, the viscosity can be measured using a commercially available viscometer for measuring the viscosity of liquids, for example, by referring to the procedure described in JIS K7117-2, at a composition temperature of 25°C. Preferably, a cone-plate type rotational viscometer is used as the viscometer, and more preferably, the same type of viscometer is used with a 1°34' x R24 standard cone rotor, and the viscosity can be measured at a composition temperature of 25°C. An example of such a rotational viscometer is the TVE-25L manufactured by Toki Sangyo Co., Ltd.

[0051] The composition for forming a flexible device substrate of the present invention may contain a crosslinking agent or the like in addition to the polyimide precursor, at least one of an imidization accelerator and a silane coupling agent, and an organic solvent, for example, to improve film strength.

[0052] The composition for forming a flexible device substrate of the present invention described above is applied to a substrate, and the resulting coating film is heated to thermally imidize the polyimide precursor, thereby obtaining a resin film having excellent adhesion to the substrate and inorganic insulating film and heat resistance.

[0053] When forming such a resin film of the present invention on a substrate, the resin film may be formed on a part of the substrate surface or on the entire surface. Formation of a resin film on a part of the substrate surface includes a form in which the resin film is formed only on a predetermined area of ​​the substrate surface, and a form in which the resin film is formed in a pattern such as a dot pattern or a line and space pattern on the entire substrate surface. In the present invention, the substrate refers to a substrate on whose surface the composition for forming a flexible device substrate of the present invention is applied and which is used in the manufacture of flexible electronic devices, etc.

[0054] Examples of substrates (base materials) include glass, plastics (polycarbonate, polymethacrylate, polystyrene, polyester, polyolefin, epoxy, melamine, triacetyl cellulose, ABS, AS, norbornene-based resins, etc.), metals (silicon wafers, etc.), wood, paper, slate, etc. In the present invention, glass substrates are particularly suitable because the resin film has sufficient adhesion. The substrate surface may be composed of a single material, or two or more materials. Examples of substrate surface configurations composed of two or more materials include a configuration in which a certain area of ​​the substrate surface is composed of one material and the remaining area is composed of another material, and a configuration in which a material in a pattern such as a dot pattern or line and space pattern is present among other materials across the entire substrate surface.

[0055] The method for applying the composition for forming a flexible device substrate of the present invention to a substrate is not particularly limited, and examples thereof include cast coating, spin coating, blade coating, dip coating, roll coating, bar coating, die coating, inkjet printing, and printing methods (relief printing, intaglio printing, lithography, screen printing, etc.).

[0056] The heating temperature for imidization is typically determined appropriately within the range of 50 to 550°C, but is preferably greater than 150°C and up to 510°C. Setting the heating temperature in this manner allows the imidization reaction to proceed sufficiently while preventing the resulting film from becoming brittle. The heating time cannot be generally specified because it varies depending on the heating temperature, but is typically 5 minutes to 5 hours. The imidization rate may be in the range of 50 to 100%. The imidization rate referred to in this specification refers to the proportion of imide groups in the total amount of imide groups derived from tetracarboxylic dianhydride or a derivative thereof and carboxyl groups (or derivatives thereof).

[0057] A preferred example of the heating mode in the present invention is a method in which heating is performed at 50 to 150°C for 5 minutes to 2 hours, followed by gradually increasing the heating temperature to a temperature of more than 150°C to 510°C for 30 minutes to 4 hours. In particular, it is preferred to heat at 50 to 150°C for 5 minutes to 2 hours, then heat at a temperature of more than 150°C to 350°C for 5 minutes to 2 hours, and finally heat at a temperature of more than 350°C to 450°C for 30 minutes to 4 hours.

[0058] Examples of heating equipment include a hot plate, an oven, etc. The heating atmosphere may be air or an inert gas, and may be atmospheric pressure or reduced pressure.

[0059] The thickness of the resin film is usually about 0.01 to 50 μm, and preferably about 0.05 to 20 μm from the viewpoint of productivity. The desired thickness can be achieved by adjusting the thickness of the coating film before heating.

[0060] The resin film described above has excellent adhesion to a substrate, particularly a glass substrate, adhesion to an inorganic insulating film, transparency, and heat resistance, and furthermore, these properties do not change even before and after heat treatment, particularly in a TFT process, etc., and the performance is stable. Therefore, the resin film of the present invention functions as a permanent film that maintains its transparency even after the manufacturing process of a flexible electronic device without damaging the resin substrate of the device.

[0061] An example of a method for manufacturing a flexible electronic device using a resin film of the present invention will be described below. A resin film is formed on a glass substrate by the above-mentioned method using the composition for forming a flexible device substrate of the present invention. To ensure insulation, an insulating film is further formed on this resin film. This method can be performed by a known method, for example, N ２ or O ２ Examples of the method include gas reactive sputtering and plasma CVD.

[0062] When sputtering is used, the sputtering conditions are as follows: the target is Si, and the sputtering gas is Ar and N ２ or O ２ The target-substrate distance is 50 to 200 mm, the process pressure is 0.1 to 0.7 Pa, the RF output is 200 to 400 W, and the sputtering time is 10 to 30 minutes.

[0063] The thickness of the resulting insulating film is preferably 100 to 1,000 nm, and more preferably 250 to 800 nm. The TFT wiring layer is completed by repeatedly performing metal (e.g., Al or Cu) sputtering, lithography patterning, chemical vapor deposition, annealing, and other processes on this insulating film. If necessary, the glass substrate can be further etched to adjust the substrate thickness, thereby enhancing the flexibility of the electronic device. Examples of insulating films that can be used include inorganic insulating films such as silicon nitride, silicon dioxide, PSG (phosphosilicate glass), and BPSG (boron phosphosilicate glass), and organic insulating films such as polyimide resins and silicone. These insulating films may be used alone or in combination.

[0064] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. The abbreviations for compounds and solvents are as follows: (Organic solvents) NMP: N-methyl-2-pyrrolidone GBL: γ-butyrolactone BCS: Butyl cellosolve (Diamines) DA-1 to DA-6: Compounds represented by the following structural formulas (DA-1) to (DA-6), respectively Of the above diamines, DA-1, DA-5, and DA-6 are included in the range of diamine (d0), and DA-2 and DA-3 are included in the range of diamine (d1).

[0065] (Tetracarboxylic acid dianhydrides) CA-1 to CA-5: Compounds represented by the following structural formulas (CA-1) to (CA-5), respectively Of the above tetracarboxylic dianhydrides, CA-1 and CA-3 are included in the range of tetracarboxylic dianhydrides (t0), and CA-2 and CA-4 are included in the range of tetracarboxylic dianhydrides (t1).

[0066] (Additives (Imidization Accelerators)) Add-B1 to Add-B3: Compounds represented by the following structural formulas (Add-B1) to (Add-B3) (wherein Boc represents a tert-butoxycarbonyl group)

[0067] (Additives (Silane Coupling Agents)) Add-C1: Compound represented by the following structural formula (Add-C1) Add-C2: X-12-1195 (Shin-Etsu Chemical Co., Ltd., blocked isocyanate type silane coupling agent) Add-C3: X-12-1293 (Shin-Etsu Chemical Co., Ltd., blocked isocyanate type silane coupling agent) Add-C4: X-12-1308ES (Shin-Etsu Chemical Co., Ltd., blocked isocyanate type silane coupling agent) Add-C5 to C7: Compounds represented by the following structural formulas (Add-C5) to (Add-C7) (In the above formula, Me represents a methyl group, and Et represents an ethyl group.)

[0068] <Viscosity Measurement> Measurement was carried out at 25°C using an E-type viscometer TVE-22H (manufactured by Toki Sangyo Co., Ltd.) with a sample volume of 1.1 mL and a cone rotor TE-1 (1°34', R24). <Molecular Weight Measurement> Measurement was carried out under the following conditions using the following room temperature GPC (gel permeation chromatography) apparatus, and Mn (number average molecular weight) and Mw (weight average molecular weight) were calculated as values ​​converted into polyethylene glycol and polyethylene oxide. GPC apparatus: GPC-101 (manufactured by Resonac Inc.), Column: GPC KD-803 and GPC KD-805 (manufactured by Resonac Inc.) in series, Column temperature: 50°C, Eluent: N,N-dimethylformamide (containing lithium bromide monohydrate (LiBr.H) as an additive), ２ o) at 30 mmol / L, anhydrous crystalline phosphoric acid (o-phosphoric acid) at 30 mmol / L, tetrahydrofuran (THF) at 10 mL / L), flow rate: 1.0 mL / min. Standard sample for creating a calibration curve: EasiVial PEG / PEO polyethylene glycol oxide PL2080-0201 (molecular weight: approximately 1,500, approximately 4,000, approximately 13,000, approximately 30,000, approximately 70,000, approximately 130,000, approximately 500,000, approximately 1,000,000, approximately 1,500,000) (manufactured by GL Sciences).

[0069] <Synthesis of Diamine> (Synthesis Example 1: Synthesis of DA-5) 11H-Benzo[b]fluoren-11-one (3.91 g, 17.0 mmol), aniline hydrochloride (2.20 g, 17.0 mmol), and aniline (7.9 g) were added to a 100 mL four-neck flask and stirred at 150°C for 24 hours. After the reaction was completed, ethyl acetate (100 g) was added at room temperature and the mixture was washed three times with pure water (50 g). The organic layer was completely concentrated and purified by column chromatography using heptane / ethyl acetate (1:1 (volume ratio)). When the resulting solution was concentrated, crystals precipitated. These were repulped and washed with 2-propanol (20 g) to obtain DA-5 (yield: 5.5 g, 13.8 mmol, 81% yield). １ H-NMR (DMSO-d ６): 8.34 (1H, s), 8.00 (1H, d), 7.96 (1H, d), 7.86 (1H, d), 7.79 (1H, s), 7.30-7.49 (5H, m), 6.81 (4H, d), 6.42 (4H, d), 4.92 (4H, s) (Monomer Synthesis Example 2: Synthesis of DA-6) DA-6 was synthesized using 2,7-Dibromo-9,9'-spirobio[9H-fluorene] as a raw material with reference to the synthesis method described in JP-A-2019-529616. １ H-NMR (DMSO-d ６ δ (ppm) = 7.95 (2H, d), 7.33-7.39 (4H, m), 7.10-7.17 (2H, m), 6.66 (2H, d), 6.48 (2H, dd), 5.77 (2H, d), 4.83 (4H, s) <Synthesis of Polymer> (Polymerization Example 1) DA-1 (25.1 g, 72.0 mmol) and NMP (142 g) were added to a 300 mL four-neck flask equipped with a stirrer and a nitrogen inlet tube, and dissolved by stirring at room temperature (25 ° C) while supplying nitrogen. Thereafter, CA-1 (8.25 g, 18.0 mmol) and NMP (46.8 g) were added, and the mixture was stirred at 40 ° C for 1 hour. Thereafter, CA-2 (11.6 g, 53.3 mmol) and NMP (65.6 g) were added and stirred at 40° C. for 16 hours to obtain a polyamic acid solution (A-1) (viscosity: 704 mPa s) with a solids concentration of 15% by mass. The polyamic acid had an Mn of 14,232 and an Mw of 37,167.

[0070] (Polymerization Examples 2 to 19) Polyamic acid solutions (A-2) to (A-19) each having a solid content concentration of 15 mass% were obtained by polymerizing polyamic acid in the same manner as in Polymerization Example 1, except that the types and amounts of the diamine component and tetracarboxylic acid component used were changed. The amounts of the diamine and tetracarboxylic acid components used in the polymerization of the polyamic acid, and the viscosity, Mn, and Mw of the obtained polymers are summarized in Table 1.

[0071]

[0072] <Preparation of Composition for Forming Flexible Device Substrate> (Preparation Example 1) Polyamic acid solution A-1 (2.13 g) was placed in a 20 mL screw tube, Add-B1 (0.0160 g) as additive 1 and Add-C1 (5 mass % NMP solution, 0.320 g) as additive 2 were added, and the mixture was stirred at room temperature (25°C) for 5 hours to obtain a composition for forming a flexible device substrate (B-1) having a polymer solids concentration of 13 mass %. In addition, polyamic acid solution A-1 (2.13 g), Add-B1 (0.0160 g) as additive 1, and Add-C1 (5 mass % NMP solution, 0.320 g) as additive 2 were added to another 20 mL screw tube, and NMP (1.55 g), GBL (2.40 g), and BCS (1.60 g) were further added to dilute the mixture, and the mixture was stirred at room temperature (25° C.) for 5 hours, thereby obtaining a composition (C-1) for forming a flexible device substrate having a polymer solids concentration of 4 mass %.

[0073] (Preparation Examples 2 to 37) Compositions (B-2) to (B-37) for forming a flexible device substrate having a polymer solids concentration of 13% by mass and compositions (C-2) to (C-37) for forming a flexible device substrate having a polymer solids concentration of 4% by mass were obtained by performing the same operation as in Preparation Example 1, except that the types and amounts of the polyamic acid solution and additives / solvent used were changed as shown in Table 2 below. Note that the additives Add-C1 to Add-C7 in Table 2 were each added as an NMP solution containing 5% by mass.

[0074]

[0075] <Evaluation of Polyimide Properties> (Example 1) Using the compositions (B-1) and (C-1) for forming flexible device substrates obtained in Preparation Example 1, transmittance, TGA (thermogravimetric analysis), and silicon nitride film adhesion were evaluated according to the methods described below.

[0076] [Transmittance Evaluation] The composition (C-1) for forming a flexible device substrate obtained in Preparation Example 1 was spin-coated onto a 5 cm square, 0.7 mm thick alkali-free glass substrate (Eagle-XG). The substrate was baked on a hot plate at 70°C for 90 seconds, then baked in an infrared heating furnace at 230°C under a nitrogen atmosphere for 30 minutes, and then baked in a clean oven at 400°C under a nitrogen atmosphere for 30 minutes to produce an alkali-free glass substrate with a polyimide film of 50 nm thickness. This polyimide film-coated substrate was measured using a Shimadzu UV-3600 at a temperature of 25°C and a scanning wavelength of 350 to 800 nm. An uncoated alkali-free glass substrate was used as a reference. The transmittance at a wavelength of 450 nm was used for evaluation, and the value was 93.2%.

[0077] [TGA Evaluation] The composition (B-1) for forming a flexible device substrate obtained in Preparation Example 1 was spin-coated onto a 4-inch silicon wafer and baked on a hot plate at 70°C for 900 seconds. The wafer was then baked in an infrared oven at 230°C under a nitrogen atmosphere for 30 minutes, and then baked in a clean oven at 400°C under a nitrogen atmosphere for 30 minutes to produce a silicon wafer with a polyimide film having a thickness of 5 μm. The polyimide film was cut from the silicon wafer using a cutter and weighed to 8.0 mg in a 100 μL aluminum pan. The aluminum pan containing the sample was placed in the furnace of a thermogravimetric analyzer TGA / DSC 3+ (manufactured by METTLER TOLEDO), and the weight loss was measured as the temperature was increased from 25°C to 550°C at a rate of 10°C / min. In order to eliminate the influence of moisture due to moisture absorption, the weight at 150°C was set as 100%, and the temperature at which the weight became less than 99.0% was evaluated as Td1 (1% weight loss temperature), which was 487°C.

[0078] [Silicon nitride film adhesion test] The composition for forming a flexible device substrate (C-1) obtained in Preparation Example 1 was spin-coated onto a 5 cm square, 0.7 mm thick alkali-free glass substrate (Eagle-XG (registered trademark) manufactured by Corning Incorporated), baked on a hot plate at 70°C for 90 seconds, then baked in an infrared heating furnace at 230°C under a nitrogen atmosphere for 30 minutes, and further baked in a clean oven at 400°C under a nitrogen atmosphere for 30 minutes to produce an alkali-free glass substrate with a polyimide film of 50 nm in thickness. The obtained alkali-free glass substrate with a polyimide film was placed in the chamber of an RF sputtering apparatus SRS-700T / LL (manufactured by Sanyu Electronics Co., Ltd.) so that the polyimide film surface side faced the Si surface of the target. Furthermore, a silicon nitride film was formed on the polyimide film under the conditions shown below. ２ The film was formed by gas reactive sputtering (sputtering conditions: target: Si, sputtering gas: Ar and N ２, target-substrate distance: 100 mm, process pressure: 0.4 Pa, RF output: 300 W, sputtering time: 17 minutes, silicon nitride film thickness: 300 nm). The obtained alkali-free glass substrate with a silicon nitride film and polyimide film was then placed in a muffle furnace at 400°C for 30 minutes, then rapidly cooled to room temperature, and evaluated for peeling of the silicon nitride film and polyimide substrate. Those that showed peeling were rated as "poor" and those that did not show peeling were rated as "good," resulting in a "good" rating. The substrate was then placed in a muffle furnace at 450°C for 30 minutes, then rapidly cooled to room temperature, and evaluated for peeling of the silicon nitride film and polyimide substrate due to thermal expansion. Those that showed peeling were rated as "poor" and those that did not show peeling were rated as "good," resulting in a "good" rating. The composition (B-1) for forming a flexible device substrate obtained in Preparation Example 1 was spin-coated onto a 5 cm square, 0.7 mm thick alkali-free glass substrate (Eagle-XG (registered trademark) manufactured by Corning Incorporated), baked on a hot plate at 70°C for 900 seconds, baked in an infrared heating furnace at 230°C under a nitrogen atmosphere for 30 minutes, and further baked in a clean oven at 400°C under a nitrogen atmosphere for 30 minutes to produce an alkali-free glass substrate with a polyimide film having a thickness of 5 μm. The silicon nitride film was then coated with N using the same procedure as in the case of the alkali-free glass substrate with a 50 nm thick polyimide film. ２ The film was formed by gas reactive sputtering. The obtained alkali-free glass substrate with the silicon nitride film and polyimide film was placed in a muffle furnace at 400°C for 30 minutes, then rapidly cooled to room temperature, and evaluated for peeling of the silicon nitride film and polyimide substrate due to thermal expansion. Those that showed peeling were rated as "poor," and those that did not show peeling were rated as "good." The result was "good."

[0079] (Examples 2 to 29, Comparative Examples 1 to 8) The transmittance, TGA (thermogravimetric analysis), and silicon nitride film adhesion were evaluated in the same manner as in Example 1, except that the compositions for forming flexible device substrates used were changed to (B-2) to (B-37) and (C-2) to (C-37), respectively. The evaluation results are shown in Table 3 below.

[0080]

[0081] As is clear from Table 3, by using a composition for forming a flexible device substrate that contains a polyamic acid using tetracarboxylic dianhydride (t0) and diamine (d0), and one or both of tetracarboxylic dianhydride (t1) and diamine (d1), and further contains an imidization accelerator or a silane coupling agent as an additive, it was possible to obtain a polyimide film that has high transmittance and high heat resistance and does not peel off the silicon nitride film even after annealing at 400 ° C. Furthermore, when both the imidization accelerator and the silane coupling agent were used as additives, the silicon nitride film did not peel off even after annealing at 450 ° C., and it was revealed that the adhesion of the silicon nitride film was improved.

[0082] The entire contents of the specification, claims and abstract of Japanese Patent Application No. 2023-210348 filed on December 13, 2023 are hereby incorporated by reference as the disclosure of the present invention.

Claims

1. A composition for forming a flexible device substrate, comprising component (A) and at least one of components (B) and (C): Component (A): a polyimide precursor having a tetracarboxylic dianhydride or a derivative thereof having a structure represented by the following formula (0-t) or (0-d) and a structure derived from a diamine having a structure represented by the following formula (0-d), and further having one or both of a structure derived from a tetracarboxylic dianhydride or a derivative thereof satisfying the following condition (i) and a structure derived from a diamine satisfying the following condition (ii), and containing no fluorine atoms; Condition (i): having two dicarboxylic anhydride moieties directly bonded to aromatic rings in the molecule, and when there are a plurality of aromatic rings bonded to the dicarboxylic anhydride moieties, the aromatic rings bonded to the dicarboxylic anhydride moieties are bonded to each other by a single bond, bonded via an aromatic ring, or formed as a condensed ring. Condition (ii): The molecule has two amino groups directly bonded to aromatic rings, and when there are multiple aromatic rings bonded to the amino groups, the aromatic rings bonded to the amino groups are bonded to each other by a single bond, bonded via an aromatic ring, or formed as a condensed ring. (In the formula, the hydrogen atom on the benzene ring may be substituted with a group selected from a halogen atom, an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms and a phenyl group which may have a substituent, the two benzene rings bonded to the 9-position of the fluorene may be bonded to each other by a single bond or an ether bond, and the benzene ring of the fluorene skeleton may be replaced with a naphthalene ring. The dashed line in formula (0-t) represents a bond to the acid anhydride moiety, and the dashed line in formula (0-d) represents a bond to a group having an acid anhydride moiety in the tetracarboxylic dianhydride, and represents a bond to a group having an amino group in the diamine.) Component (B): an imidization accelerator; Component (C): a silane coupling agent.

2. A composition for forming a flexible device substrate according to claim 1, comprising components (B) and (C).

3. A flexible electronic device having a resin film obtained from the composition for forming a flexible device substrate according to claim 1 or 2.

4. A flexible electronic device having a glass substrate on one side of a resin film obtained from the composition for forming a flexible device substrate according to claim 1 or 2, and an insulating film on the other side.

5. A composition for forming a flexible device substrate according to claim 1 or 2, wherein the component (B) is a compound having a basic site, a compound having an aromatic heterocycle, or a compound that generates the basic site upon firing.

6. A composition for forming a flexible device substrate according to claim 1 or 2, wherein the content of the component (B) is 0.1 to 30 parts by mass per 100 parts by mass of the polyimide precursor.

7. A composition for forming a flexible device substrate according to claim 1 or 2, wherein the component (C) is an amine-based silane coupling agent, a vinyl-based silane coupling agent, an epoxy-based silane coupling agent, a methacryl-based silane coupling agent, an acrylic-based silane coupling agent, a ureido-based silane coupling agent, a sulfide-based silane coupling agent, a mercapto-based silane coupling agent, an isocyanate-based silane coupling agent and a silane coupling agent in which the isocyanate group is protected with a thermally detachable group, an aldehyde-based silane coupling agent, or a carbamate-based silane coupling agent.

8. A composition for forming a flexible device substrate according to claim 1 or 2, wherein the content of the component (C) is 0.10 parts by mass to 30.0 parts by mass per 100 parts by mass of the polyimide precursor.

9. The composition for forming a flexible device substrate according to claim 1 or 2, further comprising an organic solvent.

10. The flexible electronic device according to claim 3, wherein the resin film has a thickness of 0.05 to 20 μm.

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