WO2023063202A1

WO2023063202A1 - Polyamic acid, polyamic acid composition, polyimide, polyimide film, laminate, method for producing laminate, and electronic device

Info

Publication number: WO2023063202A1
Application number: PCT/JP2022/037393
Authority: WO
Inventors: 博文中山
Original assignee: 株式会社カネカ
Priority date: 2021-10-12
Filing date: 2022-10-06
Publication date: 2023-04-20

Abstract

The polyamic acid has a 3,3',4,4'-biphenyltetracarboxylic dianhydride residue and a 4,4'-(hexafluoroisopropylidene)diphthalic anhydride residue as tetracarboxylic dianhydride residues and a 4-aminophenyl-4-aminobenzoate residue as a diamine residue. The content of 3,3',4,4'-biphenyltetracarboxylic dianhydride residues is 65-97 mol% (inclusive) relative to the total tetracarboxylic dianhydride residues. The content of 4,4'-(hexafluoroisopropylidene)diphthalic anhydride residues is 3-35 mol% (inclusive) relative to the total tetracarboxylic dianhydride residues. The content of 4-aminophenyl-4-aminobenzoate residues is 50 mol% or more relative to the total diamine residues.

Description

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

The present invention relates to polyamic acids, polyamic acid compositions, polyimides, polyimide films, laminates, methods for producing laminates, and electronic devices. The present invention further provides electronic device materials using polyimide, thin film transistor (TFT) substrates, flexible display substrates, color filters, printed matter, optical materials, image display devices (more specifically, liquid crystal display devices, organic EL, electronic paper, etc.), 3D displays, solar cells, touch panels, transparent conductive film substrates, and substitute materials for members currently using glass.

With the rapid progress of displays such as liquid crystal displays, organic EL, and electronic paper, as well as electronic devices such as solar cells and touch panels, devices are becoming thinner, lighter, and more flexible. In these devices, polyimide is used as the substrate material instead of the glass substrate.

In these devices, various electronic elements, such as thin film transistors and transparent electrodes, are formed on the substrate, and high-temperature processes are required to form these electronic elements. Polyimide has sufficient heat resistance to adapt to high-temperature processes, and its coefficient of thermal expansion (CTE) is similar to that of glass substrates and electronic devices. be.

Aromatic polyimides are generally colored yellowish brown due to intramolecular conjugation and formation of charge transfer (CT) complexes. Transparency is not required, and conventional aromatic polyimides have been used. However, in cases where the light emitted from the display element passes through the substrate, such as in transparent displays, bottom-emission organic EL, and liquid crystal displays, and in smartphones, etc., where full-screen displays (notchless) are required, sensors and When the camera module is arranged on the back surface of the substrate, the substrate is also required to have high optical properties (more specifically, transparency, etc.).

Against this background, there is a demand for a material that has the same heat resistance as existing aromatic polyimides, but also has reduced coloration and excellent transparency.

In order to reduce the coloring of polyimide, a technique for suppressing the formation of a CT complex using an aliphatic monomer (Patent Documents 1 and 2), and a technique for improving transparency by using a monomer having a fluorine atom (Patent Document 3) )It has been known.

The polyimides described in Patent Documents 1 and 2 have high transparency and a low CTE, but because they have an aliphatic structure, they have a low thermal decomposition temperature and are difficult to apply to high-temperature processes when forming electronic elements.

Although the polyimide described in Patent Document 3 has excellent transparency, it may be colored during the high-temperature process of forming electronic elements.

JP 2016-29177 A JP 2012-41530 A JP 2014-70139 A

The present invention has been accomplished in view of the above circumstances, and an object of the present invention is to provide a polyimide and a polyamic acid as a precursor thereof that are excellent in transparency and capable of reducing coloration in high-temperature processes. Another object of the present invention is to provide a product or member that is produced using the polyimide and polyamic acid and that requires transparency. In particular, it is an object of the present invention to provide a product or member in which the polyimide film of the present invention is formed on the surface of an inorganic material such as glass, metal, metal oxide, or single crystal silicon.

<Aspect of the present invention>
The present invention includes the following aspects.

[1] Tetracarboxylic dianhydride residue, 3,3′,4,4′-biphenyltetracarboxylic dianhydride residue and 4,4′-(hexafluoroisopropylidene)diphthalic anhydride residue and having a 4-aminophenyl-4-aminobenzoate residue as a diamine residue,
The content of the 3,3',4,4'-biphenyltetracarboxylic dianhydride residue is 65 mol% or more and 97 mol% or less with respect to the total tetracarboxylic dianhydride residue,
The content of the 4,4'-(hexafluoroisopropylidene)diphthalic anhydride residue is 3 mol% or more and 35 mol% or less with respect to all tetracarboxylic dianhydride residues,
Polyamic acid, wherein the content of the 4-aminophenyl-4-aminobenzoate residue is 50 mol% or more with respect to all diamine residues.

[2] When the content of the 4-aminophenyl-4-aminobenzoate residue is less than 100 mol% of all diamine residues, diamine residues other than the 4-aminophenyl-4-aminobenzoate residue groups are p-phenylenediamine residue, 9,9-bis(4-aminophenyl)fluorene residue, 2,2′-bis(trifluoromethyl)-4,4′-diaminodiphenyl ether residue, and 1, The polyamic acid according to [1] above, which is at least one selected from the group consisting of 4-cyclohexanediamine residues.

[3] The polyamic acid according to [1] above, wherein the content of the 4-aminophenyl-4-aminobenzoate residue is 100 mol% with respect to all diamine residues.

[4] The above-mentioned [2], wherein the content of diamine residues other than the 4-aminophenyl-4-aminobenzoate residue is 5 mol% or more and 50 mol% or less with respect to all diamine residues. polyamic acid.

[5] A polyamic acid composition containing the polyamic acid according to any one of [1] to [4] and an organic solvent.

[6] The polyamic acid composition according to [5] above, which further contains an imidization accelerator.

[7] The polyamic acid composition according to [6], wherein the amount of the imidization accelerator is 0.1 parts by weight or more and 10 parts by weight or less with respect to 100 parts by weight of the polyamic acid.

[8] A polyimide which is an imidized product of the polyamic acid according to any one of [1] to [4].

[9] A polyimide film containing the polyimide described in [8] above.

[10] The polyimide film according to [9] above, which has a yellowness index of 20 or less.

[11] A laminate comprising a support and the polyimide film described in [9] or [10] above.

[12] The support is a glass substrate,
The laminate according to [11], wherein the internal stress between the polyimide film and the glass substrate is 25 MPa or less.

[13] A method for producing a laminate having a support and a polyimide film,
By applying the polyamic acid composition according to any one of [5] to [7] on a support, a coating film containing the polyamic acid is formed, and the coating film is heated to obtain the polyamide A method for producing a laminate by imidating an acid.

[14] An electronic device comprising the polyimide film described in [9] or [10] above, and an electronic element disposed on the polyimide film.

The polyimide produced using the polyamic acid according to the present invention has excellent transparency and can reduce coloration in high-temperature processes. Therefore, the polyimide produced using the polyamic acid according to the present invention is suitable as a material for electronic devices that require transparency.

Preferred embodiments of the present invention will be described in detail below, but the present invention is not limited to these.

First, the terms used in this specification will be explained. A "structural unit" refers to a repeating unit that constitutes a polymer. A "polyamic acid" is a polymer containing a structural unit represented by the following general formula (1) (hereinafter sometimes referred to as "structural unit (1)").

In the general formula (1), A ¹ represents a tetracarboxylic dianhydride residue (tetravalent organic group derived from tetracarboxylic dianhydride), A ² represents a diamine residue (divalent organic group derived from diamine organic group).

The content of the structural unit (1) with respect to all structural units constituting the polyamic acid is, for example, 50 mol% or more and 100 mol% or less, preferably 60 mol% or more and 100 mol% or less, more preferably 70 mol%. 100 mol % or more, more preferably 80 mol % or more and 100 mol % or less, even more preferably 90 mol % or more and 100 mol % or less, and may be 100 mol %.

"1% weight loss temperature" is the measurement temperature when the weight of polyimide at a measurement temperature of 150°C is taken as the reference (100% by weight), and the weight is reduced by 1% by weight with respect to the reference weight.

In the following, "system" may be added after the name of the compound to generically refer to the compound and its derivatives. When the polymer name is expressed by adding "system" after the compound name, it means that the repeating unit of the polymer is derived from the compound or its derivative. Moreover, a tetracarboxylic dianhydride may be described as an "acid dianhydride". In addition, unless otherwise specified, the components, functional groups, and the like exemplified in this specification may be used alone or in combination of two or more.

<Preferred embodiment of the present invention>
Polyamic acid according to the present embodiment (hereinafter sometimes referred to as "polyamic acid (1)") is a tetracarboxylic dianhydride residue, 3,3',4,4'-biphenyltetracarboxylic acid It has a dianhydride residue and a 4,4′-(hexafluoroisopropylidene)diphthalic anhydride residue, and has a 4-aminophenyl-4-aminobenzoate residue as a diamine residue. That is, polyamic acid (1) is a polymer containing a structural unit represented by the following chemical formula (2) and a structural unit represented by the following chemical formula (3).

3,3′,4,4′-biphenyltetracarboxylic dianhydride residue is 3,3′,4,4′-biphenyltetracarboxylic dianhydride (hereinafter sometimes referred to as “BPDA” ) is the partial structure derived from 4,4'-(Hexafluoroisopropylidene) diphthalic anhydride residue is a portion derived from 4,4'-(hexafluoroisopropylidene) diphthalic anhydride (hereinafter sometimes referred to as "6FDA") Structure. A 4-aminophenyl-4-aminobenzoate residue is a partial structure derived from 4-aminophenyl-4-aminobenzoate (hereinafter sometimes referred to as “4-BAAB”).

In general, polyimides obtained from polyamic acids having BPDA residues and 4-BAAB residues have a high glass transition temperature (Tg) (excellent heat resistance) and a low CTE due to their rigid structure. In addition, it is possible to reduce the internal stress (hereinafter sometimes simply referred to as "internal stress") generated when a polyimide film is formed on a support to obtain a laminate. However, a polyimide obtained from a polyamic acid having only a BPDA residue as a tetracarboxylic dianhydride residue and only a 4-BAAB residue as a diamine residue tends to have a high haze. It is not suitable for applications that require durability.

In general, polyimides obtained from polyamic acid having 6FDA residues and 4-BAAB residues exhibit excellent transparency. tends to be easier. For this reason, polyimide obtained from polyamic acid having an excessively high content of 6FDA residues is difficult to reduce coloration in high-temperature processes.

As a result of intensive studies, the present inventors have found that BPDA residues and 6FDA residues are in a specific ratio, and the content of 4-BAAB residues is obtained from a polyamic acid (polyamic acid (1)) having a specific range. We have found that polyimide can reduce coloration in high-temperature processes while having excellent transparency. Specifically, in polyamic acid (1), the content of BPDA residues is 65 mol% or more and 97 mol% or less with respect to all tetracarboxylic dianhydride residues, and the content of 6FDA residues is 3 mol % or more and 35 mol % or less with respect to all tetracarboxylic dianhydride residues. In polyamic acid (1), the content of 4-BAAB residues is 50 mol % or more with respect to all diamine residues.

In order to obtain a polyimide that can reduce internal stress while further reducing coloration in a high-temperature process and has excellent heat resistance, the content of BPDA residues is the total tetracarboxylic acid dianhydride that constitutes polyamic acid (1). It is preferably 70 mol % or more, more preferably 75 mol % or more, even more preferably 80 mol % or more, and even more preferably 85 mol % or more, relative to the residue. In addition, in order to obtain a polyimide with excellent transparency, the content of BPDA residues should be 95 mol% or less with respect to all tetracarboxylic dianhydride residues constituting the polyamic acid (1). Preferably, it is 90 mol % or less.

In order to obtain a polyimide with excellent transparency, the content of 6FDA residues is preferably 5 mol% or more with respect to the total tetracarboxylic dianhydride residues constituting the polyamic acid (1), It is more preferably 10 mol % or more, and even more preferably 15 mol % or more. In addition, in order to obtain a polyimide that can reduce internal stress while further reducing coloration in high-temperature processes and has excellent heat resistance, the content of 6FDA residues must be such that the content of all tetracarboxylic acids constituting polyamic acid (1) is It is preferably 30 mol % or less relative to the anhydride residue.

In order to obtain a polyimide that can reduce internal stress while further reducing coloration in a high-temperature process and has excellent heat resistance, the content of 4-BAAB residues is the total diamine residues that make up polyamic acid (1). On the other hand, it is preferably 55 mol% or more, more preferably 60 mol% or more, still more preferably 65 mol% or more, even more preferably 70 mol% or more, and 75 mol% Above, 80 mol % or more, 85 mol % or more, 90 mol % or more, 95 mol % or more, or 100 mol % may be sufficient.

When synthesizing polyamic acid (1), acid dianhydrides other than BPDA and 6FDA may be used as monomers within a range that does not impair its performance. Acid dianhydrides other than BPDA and 6FDA include, for example, pyromellitic dianhydride, p-phenylenebis(trimellitate anhydride), 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1,2 ,5,6-naphthalenetetracarboxylic dianhydride, 2,2′,3,3′-biphenyltetracarboxylic dianhydride, 3,3′,4,4′-benzophenonetetracarboxylic dianhydride, 4 ,4'-oxydiphthalic anhydride, dicyclohexyl-3,3',4,4'-tetracarboxylic dianhydride, 1,2,4,5-cyclohexanetetracarboxylic dianhydride, 1,2,3, 4-Cyclobutanetetracarboxylic dianhydride, 2′-oxodispiro[bicyclo[2.2.1]heptane-2,1′-cyclopentane-3′,2″-bicyclo[2.2.1]heptane] -5,6:5'',6''-tetracarboxylic dianhydrides and derivatives thereof, which may be used singly or in combination of two or more.

In order to obtain a polyimide that can reduce internal stress while further reducing coloration in high-temperature processes and has excellent heat resistance and transparency, the total content of BPDA residues and 6FDA residues constitutes polyamic acid (1) It is preferably 70 mol% or more, more preferably 75 mol% or more, still more preferably 80 mol% or more, with respect to the total tetracarboxylic dianhydride residue, 85 mol% or more is even more preferable, and may be 90 mol % or more, 95 mol % or more, or 100 mol %.

When synthesizing polyamic acid (1), a diamine other than 4-BAAB may be used as a monomer within a range that does not impair its performance. Examples of diamines other than 4-BAAB include p-phenylenediamine (hereinafter sometimes referred to as "PDA") and 9,9-bis(4-aminophenyl)fluorene (hereinafter referred to as "BAFL"). 2,2′-bis(trifluoromethyl)-4,4′-diaminodiphenyl ether (hereinafter sometimes referred to as “6FODA”), 1,4-cyclohexanediamine (hereinafter referred to as “CHDA” ), 4,4′-diaminobenzanilide, 2,2′-bis(trifluoromethyl)benzidine, m-phenylenediamine, 4,4′-oxydianiline, 3,4′-oxy Dianiline, N,N'-bis(4-aminophenyl)terephthalamide, 4,4'-diaminodiphenylsulfone, m-tolidine, o-tolidine, 4,4'-bis(4-aminophenoxy)biphenyl, 2 -(4-aminophenyl)-6-aminobenzoxazole, 3,5-diaminobenzoic acid, 4,4'-diamino-3,3'-dihydroxybiphenyl, 4,4'-methylenebis(cyclohexanamine), 1, 3-bis(3-aminopropyl)tetramethyldisiloxane and derivatives thereof may be mentioned, and these may be used alone or in combination of two or more.

When polyamic acid (1) has diamine residues other than 4-BAAB residues, that is, in polyamic acid (1), the content of 4-BAAB residues is less than 100 mol% with respect to all diamine residues. In that case, in order to obtain a polyimide that has excellent transparency and can further reduce coloring in a high-temperature process, diamine residues other than 4-BAAB residues include PDA residues, BAFL residues, 6FODA residues and One or more diamine residues selected from the group consisting of CHDA residues are preferred. Hereinafter, one or more diamine residues selected from the group consisting of PDA residues, BAFL residues, 6FODA residues and CHDA residues may be referred to as "optional diamine residues".

In order to obtain a polyimide that has excellent transparency and can further reduce coloring in a high-temperature process, polyamic acid (1) has only a 4-BAAB residue as a diamine residue, or 4- as a diamine residue. It is preferred to have only BAAB residues and optional diamine residues. That is, in polyamic acid (1), the content of 4-BAAB residues is 100 mol% with respect to all diamine residues, or the total content of 4-BAAB residues and optional diamine residues is It is preferably 100 mol % with respect to diamine residues.

When the polyamic acid (1) has an optional diamine residue, in order to obtain a polyimide that has excellent transparency and can further reduce coloration in a high-temperature process, the content of the optional diamine residue is the polyamic acid (1). It is preferably 5 mol% or more and 50 mol% or less, more preferably 5 mol% or more and 40 mol% or less, and 5 mol% or more and 35 mol% or less with respect to all the constituent diamine residues. is more preferably 5 mol % or more and 30 mol % or less, and particularly preferably 10 mol % or more and 30 mol % or less. In addition, when polyamic acid (1) has multiple types of arbitrary diamine residues, "the content rate of arbitrary diamine residues" represents the total content rate of multiple types of arbitrary diamine residues.

When polyamic acid (1) has an optional diamine residue, a PDA residue is preferable as the optional diamine residue in order to obtain a polyimide with excellent heat resistance while further reducing coloration in high-temperature processes.

When the polyamic acid (1) has an optional diamine residue, in order to obtain a polyimide with excellent transparency, the optional diamine residue is one selected from the group consisting of a BAFL residue, a 6FODA residue and a CHDA residue. The above diamine residues are preferred.

When polyamic acid (1) has an optional diamine residue, a BAFL residue is preferable as the optional diamine residue in order to obtain a polyimide that has excellent transparency and can further reduce coloration in high-temperature processes.

In order to obtain a polyimide that can further reduce coloration in a high-temperature process while still having excellent transparency, the polyamic acid (1) preferably satisfies the following condition 1, more preferably satisfies the following condition 2, and the following conditions 3 is more preferably satisfied.
Condition 1: having only 4-BAAB residues as diamine residues, or having only 4-BAAB residues and optional diamine residues as diamine residues, and the total content of BPDA residues and 6FDA residues is 90 mol % or more with respect to all acid dianhydride residues.
Condition 2: having only 4-BAAB residues and PDA residues as diamine residues, or having only 4-BAAB residues and BAFL residues as diamine residues, and BPDA residues and 6FDA residues The total content is 90 mol % or more with respect to all acid dianhydride residues.
Condition 3: It has only 4-BAAB residues and BAFL residues as diamine residues, and the total content of BPDA residues and 6FDA residues is 90 mol% or more with respect to all acid dianhydride residues. .

Polyamic acid (1) can be synthesized by a known general method, and can be obtained, for example, by reacting a diamine and a tetracarboxylic dianhydride in an organic solvent. An example of a specific method for synthesizing polyamic acid (1) will be described. First, a diamine solution is prepared by dissolving or dispersing a diamine in an organic solvent in an inert gas atmosphere such as argon or nitrogen. Then, the tetracarboxylic dianhydride is added to the diamine solution after dissolving it in an organic solvent or dispersing it in a slurry state, or in a solid state.

When synthesizing a polyamic acid using a diamine and a tetracarboxylic dianhydride, the substance amount of the diamine (when using multiple types of diamines, the substance amount of each diamine) and the substance amount of the tetracarboxylic dianhydride (When using multiple types of tetracarboxylic dianhydrides, the amount of each tetracarboxylic dianhydride) is adjusted to obtain the desired polyamic acid (polymer of diamine and tetracarboxylic dianhydride ) can be obtained. The molar fraction of each residue in polyamic acid (1) matches, for example, the molar fraction of each monomer (diamine and tetracarboxylic dianhydride) used in synthesizing polyamic acid (1). Polyamic acid (1) containing multiple types of tetracarboxylic dianhydride residues and multiple types of diamine residues can also be obtained by blending two types of polyamic acids. The temperature conditions for the reaction between the diamine and the tetracarboxylic dianhydride, that is, the synthesis reaction of the polyamic acid (1) are not particularly limited, but are, for example, in the range of 20°C or higher and 150°C or lower. The reaction time for the synthetic reaction of polyamic acid (1) is, for example, in the range of 10 minutes or more and 30 hours or less.

The organic solvent used for synthesizing polyamic acid (1) is preferably a solvent capable of dissolving the tetracarboxylic dianhydride and diamine used, and more preferably a solvent capable of dissolving polyamic acid (1) to be produced. Examples of organic solvents used for synthesizing polyamic acid (1) include urea-based solvents such as tetramethylurea and N,N-dimethylethylurea; sulfoxide-based solvents such as dimethylsulfoxide; diphenylsulfone and tetramethylsulfone. Sulfone-based solvents such as; N,N-dimethylacetamide (DMAC), N,N-dimethylformamide (DMF), N,N-diethylacetamide, N-methyl-2-pyrrolidone (NMP), 3-methoxy-N , N-dimethylpropanamide (MPA), hexamethylphosphoric triamide and other amide solvents; γ-butyrolactone and other ester solvents; chloroform, methylene chloride and other halogenated alkyl solvents; benzene, toluene and other aromatic carbonization Hydrogen-based solvents; phenolic solvents such as phenol and cresol; ketone-based solvents such as cyclopentanone; Ether-based solvents such as cresol methyl ether are included. These solvents are usually used alone, but if necessary, two or more of them may be used in combination. In order to increase the solubility and reactivity of the polyamic acid (1), the organic solvent used in the synthetic reaction of the polyamic acid (1) consists of amide solvents, ketone solvents, ester solvents and ether solvents. One or more solvents selected from the group are preferred, and amide solvents (more specifically, DMF, DMAC, NMP, MPA, etc.) are more preferred. Further, the synthetic reaction of polyamic acid (1) is preferably carried out in an inert gas atmosphere such as argon or nitrogen.

The weight average molecular weight of the polyamic acid (1) is preferably in the range of 10,000 or more and 1,000,000 or less, and more preferably in the range of 20,000 or more and 500,000 or less, depending on the application. More preferably, it is in the range of 30,000 or more and 200,000 or less. If the weight-average molecular weight is 10,000 or more, polyamic acid (1) or polyimide obtained using polyamic acid (1) can be easily formed into a coating film or a polyimide film (film). On the other hand, when the weight-average molecular weight is 1,000,000 or less, it exhibits sufficient solubility in a solvent, so a coating film or polyimide film having a smooth surface and a uniform thickness using a polyamic acid composition described later is obtained. The weight average molecular weight used here means a polyethylene oxide equivalent value measured using gel permeation chromatography (GPC).

In addition, as a method for controlling the molecular weight of the polyamic acid (1), a method of using either an acid dianhydride or a diamine in excess, a monofunctional acid anhydride such as phthalic anhydride or aniline, or an amine A method of quenching the reaction by reacting is included. When either the acid dianhydride or the diamine is used excessively for polymerization, a polyimide film having sufficient strength can be obtained if the molar ratio of these charged is between 0.95 and 1.05. In addition, the molar ratio of the charge is the ratio of the total amount of diamines used in the synthesis of polyamic acid (1) to the total amount of acid dianhydrides used in the synthesis of polyamic acid (1) (total amount of diamines amount/total substance amount of acid dianhydride). Further, by terminal-capping with phthalic anhydride, maleic anhydride, aniline, or the like, coloring of the polyimide obtained using the polyamic acid (1) can be further reduced.

The polyamic acid composition according to the present embodiment contains polyamic acid (1) and an organic solvent. Examples of the organic solvent contained in the polyamic acid composition according to the present embodiment include the organic solvents exemplified as the organic solvent that can be used in the synthesis reaction of the polyamic acid (1), such as amide solvents and ketone solvents. , ester solvents and ether solvents are preferable, and amide solvents (more specifically, DMF, DMAC, NMP, MPA, etc.) are more preferable. When polyamic acid (1) is obtained by the method described above, the reaction solution (solution after reaction) itself may be used as the polyamic acid composition according to the present embodiment. Alternatively, the solid polyamic acid (1) obtained by removing the solvent from the reaction solution may be dissolved in an organic solvent to prepare the polyamic acid composition according to the present embodiment. The content of polyamic acid (1) in the polyamic acid composition according to the present embodiment is not particularly limited, but is, for example, 1% by weight or more and 80% by weight or less based on the total amount of the polyamic acid composition.

In addition, the polyamic acid composition according to the present embodiment may contain an imidization accelerator and/or a dehydration catalyst in order to shorten the heating time and develop properties.

Although not particularly limited, a tertiary amine can be used as the imidization accelerator. A heterocyclic tertiary amine is preferred as the tertiary amine. Preferable specific examples of heterocyclic tertiary amines include pyridine, picoline, quinoline, isoquinoline and imidazoles. Preferred specific examples of the dehydration catalyst include acetic anhydride, propionic anhydride, n-butyric anhydride, benzoic anhydride, and trifluoroacetic anhydride.

From the viewpoint of shortening the heating time and the expression of properties, the amount of the imidization accelerator is preferably 0.1 parts by weight or more and 10 parts by weight or less with respect to 100 parts by weight of the polyamic acid (1). It is more preferably 0.5 parts by weight or more and 5 parts by weight or less. In addition, from the viewpoint of shortening the heating time and developing properties, the amount of the dehydration catalyst is preferably 0.1 parts by weight or more and 10 parts by weight or less with respect to 100 parts by weight of the polyamic acid (1). It is more preferably 0.5 parts by weight or more and 5 parts by weight or less.

As the imidization accelerator, imidazoles are preferable. In the present specification, imidazoles refer to compounds having a 1,3-diazole ring (1,3-diazole ring structure). The imidazoles that can be added to the polyamic acid composition according to the present embodiment are not particularly limited. imidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-methylimidazole, 1-benzyl-2-phenylimidazole and the like. Among these, 1,2-dimethylimidazole, 1-benzyl-2-methylimidazole and 1-benzyl-2-phenylimidazole are preferred, and 1,2-dimethylimidazole and 1-benzyl-2-methylimidazole are more preferred. .

The content of the imidazole is preferably 0.005 mol or more and 0.1 mol or less, and 0.01 mol or more and 0.08 mol or less, relative to 1 mol of the amide group of the polyamic acid (1). is more preferably 0.015 mol or more and 0.050 mol or less. By containing 0.005 mol or more of imidazoles, the film strength and transparency of the polyimide can be improved, and by making the content of imidazoles 0.1 mol or less, polyamic acid (1) can be stored stably. It is possible to improve the heat resistance while maintaining the properties. In the present specification, "amide group of polyamic acid (1)" refers to an amide group produced by a polymerization reaction of diamine and tetracarboxylic dianhydride.

The method of mixing polyamic acid (1) and imidazoles is not particularly limited. From the viewpoint of ease of controlling the molecular weight of polyamic acid (1), it is preferable to add imidazoles to polyamic acid (1) after polymerization. At this time, the imidazole may be added as it is to the polyamic acid (1), or the imidazole may be dissolved in a solvent in advance and this solution may be added to the polyamic acid (1). Not restricted. The polyamic acid composition according to the present embodiment may be prepared by adding imidazoles to a solution containing polyamic acid (1) after polymerization (solution after reaction).

Various organic or inorganic low-molecular-weight compounds or high-molecular-weight compounds may be added as additives to the polyamic acid composition according to the present embodiment. Examples of additives that can be used include plasticizers, antioxidants, dyes, surfactants, leveling agents, silicones, fine particles, and sensitizers. The fine particles include organic fine particles made of polystyrene, polytetrafluoroethylene, etc., inorganic fine particles made of colloidal silica, carbon, layered silicate, etc. They may have a porous structure or a hollow structure. The function and form of the fine particles are not particularly limited, and may be, for example, pigments, fillers, or fibrous particles.

In addition, the polyamic acid composition according to the present embodiment can contain a silane coupling agent in order to exhibit appropriate adhesion to the support. As the type of silane coupling agent, known ones can be used without particular limitation, but compounds containing an amino group are particularly preferred from the viewpoint of reactivity with polyamic acid (1).

The mixing ratio of the silane coupling agent to 100 parts by weight of polyamic acid (1) is preferably 0.01 parts by weight or more and 0.50 parts by weight or less, and 0.01 parts by weight or more and 0.10 parts by weight or less. more preferably 0.01 parts by weight or more and 0.05 parts by weight or less. By setting the mixing ratio of the silane coupling agent to 0.01 parts by weight or more, the effect of suppressing peeling from the support is sufficiently exhibited, and by setting the mixing ratio of the silane coupling agent to 0.50 parts by weight or less, Since the decrease in the molecular weight of the polyamic acid (1) is suppressed, embrittlement of the polyimide film can be suppressed.

The polyimide according to this embodiment is an imidized product of polyamic acid (1) described above. The polyimide according to this embodiment can be obtained by a known method, and the production method is not particularly limited. An example of a method for imidating the polyamic acid (1) to obtain the polyimide according to the present embodiment will be described below. Imidation is carried out by dehydration and ring closure of polyamic acid (1). This dehydration ring closure can be carried out by an azeotropic method using an azeotropic solvent, a thermal method, or a chemical method. In addition, imidization of polyamic acid (1) to polyimide can take any ratio of 1% or more and 100% or less. That is, a partially imidized polyamic acid (1) may be synthesized. In particular, when imidization is performed by heating, the ring closure reaction from polyamic acid (1) to polyimide and the hydrolysis of polyamic acid (1) proceed simultaneously, and the molecular weight of polyamic acid (1) when converted to polyimide is Since there is a possibility that the molecular weight is lower than the molecular weight of the polyamic acid composition, before forming the polyimide film described later, it is preferable to pre-imidize a portion of the polyamic acid (1) in the polyamic acid composition from the viewpoint of improving mechanical properties. preferable. In this specification, a partially imidized polyamic acid may also be referred to as a "polyamic acid".

The dehydration ring closure of the polyamic acid (1) may be performed by heating the polyamic acid (1). The method of heating the polyamic acid (1) is not particularly limited, but for example, the polyamic acid composition according to the present embodiment is applied onto a support such as a glass substrate, a metal plate, or a PET film (polyethylene terephthalate film). After that, the polyamic acid (1) may be heat-treated at a temperature in the range of 40°C or higher and 500°C or lower. According to this method, a laminate according to the present embodiment, which has a support and a polyimide film (specifically, a polyimide film containing an imidized product of polyamic acid (1)) disposed on the support, is obtained. be done. Alternatively, the polyamic acid composition is directly put into a container that has been subjected to release treatment such as coating with a fluororesin, and the polyamic acid composition is heated and dried under reduced pressure to effect dehydration ring closure of the polyamic acid (1). can also be done. Polyimide can be obtained by dehydration ring closure of polyamic acid (1) by these techniques. The heating time for each of the above treatments varies depending on the amount of the polyamic acid composition to be subjected to dehydration ring closure and the heating temperature, but is generally in the range of 1 minute or more and 300 minutes or less after the treatment temperature reaches the maximum temperature. It is preferable to

The polyimide film according to the present embodiment (specifically, the polyimide film containing the imidized product of polyamic acid (1)) is colorless and transparent, has a low degree of yellowness, and has a glass transition temperature (heat resistance) that can withstand the TFT manufacturing process. Therefore, it is suitable as a transparent substrate material for flexible displays. The content of polyimide (specifically, imidized polyamic acid (1)) in the polyimide film according to the present embodiment is, for example, 70% by weight or more, and 80% by weight or more with respect to the total amount of the polyimide film. is preferable, more preferably 90% by weight or more, and may be 100% by weight. Components other than polyimide in the polyimide film include, for example, the additives described above (more specifically, fine particles and the like).

An electronic device (more specifically, a flexible device or the like) according to this embodiment has a polyimide film according to this embodiment and an electronic element directly or indirectly arranged on this polyimide film. When manufacturing the electronic device according to the present embodiment for a flexible display, first, an inorganic substrate such as glass is used as a support, and a polyimide film is formed thereon. Then, an electronic device is formed on the support by arranging (forming) an electronic element such as a TFT on the polyimide film. The process of forming a TFT is generally carried out in a wide temperature range of 150° C. or higher and 650° C. or lower. is formed, and in some cases, a-Si or the like is further crystallized by a laser or the like.

At this time, if the thermal decomposition temperature of the polyimide film is low, outgassing is generated during the formation of the electronic device, and the sublimate adheres to the inside of the oven, causing contamination inside the oven. The 1% weight loss temperature of polyimide is preferably 500° C. or higher because there is a possibility that a barrier film (to be described later) and electronic elements may peel off. The upper limit of the 1% weight loss temperature of polyimide is preferably 600° C., for example, although the higher the better. The 1% weight loss temperature can be adjusted, for example, by changing the content of residues having a rigid structure (more specifically, BPDA residues and the like). More specifically, before forming the TFT, an inorganic film such as a silicon oxide film (SiOx film) or a silicon nitride film (SiNx film) is formed as a barrier film on the polyimide film. At this time, if the heat resistance of the polyimide is low, if the imidization has not progressed completely, or if there is a large amount of residual solvent, volatile components such as the decomposition gas of the polyimide in the high-temperature process after lamination of the inorganic film may cause In some cases, the polyimide and the inorganic film are separated from each other. Therefore, in addition to the 1% weight loss temperature of the polyimide being 500° C. or higher, the weight loss rate when the polyimide is kept isothermally at a temperature within the range of 400° C. or higher and 450° C. or lower must be less than 1%. desirable.

In addition, according to the studies of the present inventors, polyimides having a relatively high content of residues derived from fluorine-containing monomers generate corrosive gases such as hydrogen fluoride as outgassing in high-temperature processes such as the fabrication of TFT elements. It turned out to do. When corrosive gas is generated in a high-temperature process, the barrier film or the like laminated on the polyimide film corrodes, and peeling or the like may occur at the interface of the laminated body. The polyamic acid (polyamic acid (1)) of the present embodiment has a 6FDA residue content of 3 mol% or more and 35 mol% or less with respect to the acid dianhydride residue, so polyamic acid (1) is used. The polyimide thus obtained can suppress the generation of corrosive gas in a high-temperature process.

Further, if the glass transition temperature (Tg) of the polyimide is significantly lower than the process temperature, there is a possibility that misalignment or the like may occur during the formation of the electronic device. It is more preferably 350° C. or higher, still more preferably 400° C. or higher, and even more preferably 420° C. or higher. The upper limit of Tg of polyimide is preferably 470° C., although the higher the better. Further, since the coefficient of thermal expansion of the glass substrate is generally smaller than that of resin, internal stress is generated between the glass substrate and the polyimide film. If the internal stress of the laminated body of the glass substrate or electronic element used as a support and the polyimide film is high, the laminated body including the polyimide film expands in the TFT formation process at a high temperature and then shrinks when cooled to room temperature. However, problems such as warping or breakage of the glass substrate and peeling of the polyimide film from the glass substrate arise. Therefore, the internal stress between the polyimide film and the glass substrate is preferably 40 MPa or less, more preferably 35 MPa or less, still more preferably 30 MPa or less, and even more preferably 25 MPa or less. The lower limit of the internal stress is better, and may be 0 MPa. The method for measuring the internal stress is the same method as in Examples described later or a method based thereon.

If there is a float at the interface between the polyimide film and the support (for example, a glass substrate), the polyimide film may peel off during the formation of the electronic device, or the yield may decrease when the polyimide film is peeled off after the electronic device is formed. There is The term “floating” refers to the adhesion between the polyimide film and other material layers (more specifically, glass substrates, barrier films, etc.) due to secondary components and residual solvents generated during imidization. Refers to a state in which a defect has occurred. Specific examples of "floating" include a state in which the polyimide film is lifted from the glass substrate, a state in which a portion of the polyimide film is destroyed and delamination occurs between the polyimide film and another material layer, and a barrier from the polyimide film. A state in which the film is lifted may be mentioned. In general, a polyimide film obtained from a polyamic acid having a BPDA residue and a 4-BAAB residue has densely packed molecular chains and poor outgassing properties. Floating is likely to occur in Since the polyamic acid (polyamic acid (1)) of the present embodiment contains a 6FDA residue having a bulky structure, the polyimide film obtained using the polyamic acid (1) has good gas release properties. . Therefore, according to the polyimide obtained using the polyamic acid (1), it is possible to suppress the occurrence of floating.

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

First, the polyamic acid composition according to the present embodiment is applied (cast) onto a support to form a coated film-containing laminate comprising a coated film containing polyamic acid (1) and the support. Next, the coated film-containing layered product is heated, for example, at a temperature of 40° C. or higher and 200° C. or lower. The heating time at this time is, for example, 3 minutes or more and 120 minutes or less. A multi-step heating process may be provided, such as heating the coating film-containing laminate at a temperature of 50° C. for 30 minutes and then heating it at a temperature of 100° C. for 30 minutes. Next, in order to promote imidization of polyamic acid (1) in the coating film, the coating film-containing laminate is heated, for example, at a maximum temperature of 200° C. or higher and 500° C. or lower. The heating time (heating time at the maximum temperature) at this time is, for example, 1 minute or more and 300 minutes or less. At this time, it is preferable to gradually raise the temperature from the low temperature to the maximum temperature. The heating rate is preferably 2° C./min or more and 10° C./min or less, more preferably 4° C./min or more and 10° C./min or less. Also, the maximum temperature is preferably in the range of 250° C. or higher and 450° C. or lower. When the maximum temperature is 250° C. or higher, imidization proceeds sufficiently, and when the maximum temperature is 450° C. or lower, thermal deterioration and coloration of the polyimide can be suppressed. Also, any temperature may be maintained for any length of time until the maximum temperature is reached. The imidization reaction can be carried out under air, under reduced pressure, or in an inert gas such as nitrogen, but in order to develop higher transparency, it is carried out under reduced pressure or in an inert gas such as nitrogen. is preferred. As the heating device, known devices such as a hot air oven, an infrared oven, a vacuum oven, an inert oven and a hot plate can be used. Polyamic acid (1) in the coating film is imidized through these steps, and a laminate of a support and a polyimide film (a film containing an imidized product of polyamic acid (1)) (that is, according to the present embodiment) laminate) can be obtained.

A known method can be used to peel off the polyimide film from the obtained laminate of the support and the polyimide film. For example, it may be peeled off by hand, or may be peeled off using a mechanical device such as a driving roll or a robot. Furthermore, a method of providing a peeling layer between a support and a polyimide film, a method of forming a silicon oxide film on a support having a large number of grooves, forming a polyimide film using the silicon oxide film as a base layer, and forming a polyimide film on the support It is also possible to adopt a method of exfoliating the polyimide film by infiltrating a silicon oxide etchant between the film and the silicon oxide film. Alternatively, a method of separating the polyimide film by laser light irradiation may be employed.

The transparency of the polyimide film can be evaluated by total light transmittance (TT) according to JIS K7361-1:1997 and haze according to JIS K7136-2000. When the polyimide film is used for applications requiring high transparency, the total light transmittance of the polyimide film is preferably 75% or more, more preferably 80% or more. Further, when a polyimide film is used in applications requiring high transparency, the haze of the polyimide film is preferably 1.5% or less, more preferably 1.2% or less, and 1.0%. It is more preferably less than, and may be 0%. For applications that require high transparency, polyimide films are required to have high transmittance over the entire wavelength range. often colored. In order to use the polyimide film in applications requiring high transparency, it is preferable that the polyimide film is less colored. Specifically, in order to use the polyimide film for applications requiring high transparency, the yellowness index (YI) of the polyimide film is preferably 25 or less, more preferably 20 or less, It can be 0. YI can be measured according to JIS K7373-2006. YI can be adjusted, for example, by changing the content of 6FDA residues in polyamic acid (1). Thus, the polyimide film with reduced coloration and imparted with transparency is suitable for transparent substrates such as glass substitutes, and substrates on which a sensor or camera module is provided on the back surface.

In addition, there are two types of light extraction methods for flexible displays: the top emission method, in which light is extracted from the front surface of the TFT, and the bottom emission method, in which light is extracted from the back surface of the TFT. The top-emission method is easy to increase the aperture ratio because the light is not blocked by the TFT, and high-definition image quality can be obtained. Characteristic. If the TFT is transparent, it is possible to improve the aperture ratio even in the bottom emission method, so there is a tendency to adopt the bottom emission method, which is easy to manufacture, for large displays. Since the polyimide film according to this embodiment has a low YI and excellent heat resistance, it can be applied to either of the above light extraction methods.

Further, in a batch-type device manufacturing process in which a polyamic acid composition is applied to a support such as a glass substrate, heated to imidize, an electronic element or the like is formed, and then the polyimide film is peeled off, the support and the like are used. It is preferable to have excellent adhesion to the polyimide film. Adhesion here means adhesion strength. In the manufacturing process of peeling off the polyimide film on which the electronic elements and the like are formed from the support after forming the electronic elements on the polyimide film on the support, if the adhesion between the polyimide film and the support is excellent, the electronic element etc. can be formed or implemented more accurately. In the manufacturing process of arranging an electronic element or the like on a support via a polyimide film, the peel strength between the support and the polyimide film should be as high as possible from the viewpoint of improving productivity. Specifically, the peel strength is preferably 0.05 N/cm or more, more preferably 0.1 N/cm or more.

In the manufacturing process described above, when peeling the polyimide film from the laminate of the support and the polyimide film, the polyimide film is often peeled off from the support by laser irradiation. In this case, since the polyimide film needs to absorb the laser light, the cutoff wavelength of the polyimide film is required to be longer than the wavelength of the laser light used for peeling. Since a XeCl excimer laser with a wavelength of 308 nm is often used for laser peeling, the cutoff wavelength of the polyimide film is preferably 312 nm or longer, more preferably 330 nm or longer. On the other hand, if the cutoff wavelength is long, the polyimide film tends to be colored yellow, so the cutoff wavelength of the polyimide film is preferably 390 nm or less. The cutoff wavelength of the polyimide film is preferably 320 nm or more and 390 nm or less, more preferably 330 nm or more and 380 nm or less, from the viewpoint of achieving both transparency (low degree of yellowness) and workability of laser peeling. The term "cutoff wavelength" as used herein means a wavelength at which the transmittance is 0.1% or less as measured by an ultraviolet-visible spectrophotometer.

The polyamic acid composition and polyimide according to the present embodiment may be used as they are for coating and molding processes for producing products and members, but the molded product molded in the form of a film is further subjected to coating and other treatments. It can also be used as a material for For use in coating or molding processes, the polyamic acid composition or polyimide, optionally dissolved or dispersed in an organic solvent, and optionally a photocurable component, a thermosetting component, a non-polymeric binder, A composition comprising polyamic acid (1) or polyimide may be prepared by blending the resin and other ingredients.

Various inorganic thin films such as metal oxide thin films and transparent electrodes may be formed on the surface of the polyimide film according to this embodiment. The method for forming these inorganic thin films is not particularly limited, and examples thereof include PVD methods such as sputtering, vacuum deposition, and ion plating, and CVD methods.

In addition to heat resistance, low thermal expansion, and transparency, the polyimide film according to the present embodiment generates little internal stress when forming a laminate with a glass substrate, ensuring adhesion with inorganic materials during high-temperature processes. Therefore, it is preferably used in fields and products where these properties are useful. For example, the polyimide film according to the present embodiment can be used for liquid crystal display devices, organic EL devices, image display devices such as electronic paper, printed matter, color filters, flexible displays, optical films, 3D displays, touch panels, transparent conductive film substrates, solar cells, and the like. It is more preferable to use it as a substitute material for parts where glass is currently used. In these uses, the thickness of the polyimide film is, for example, 1 μm or more and 200 μm or less, preferably 5 μm or more and 100 μm or less. The thickness of the polyimide film can be measured using a laser hologram.

In addition, the polyamic acid composition according to the present embodiment is prepared by coating the polyamic acid composition on a support, imidizing it by heating, forming an electronic element or the like, and then peeling off the polyimide film for batch-type device fabrication. It can be suitably used for the process. Therefore, in the present embodiment, the production of an electronic device including the step of applying a polyamic acid composition on a support, imidizing it by heating, and forming an electronic element or the like on a polyimide film formed on the support A method is also included. Moreover, the method for producing such an electronic device may further include a step of peeling off the polyimide film on which the electronic elements and the like are formed from the support.

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

<Method for measuring physical properties>
First, a method for measuring physical properties of polyimide (polyimide film) will be described.

[Internal stress]
Each polyamic acid composition prepared in Examples and Comparative Examples described later on a glass substrate manufactured by Corning (material: non-alkali glass, thickness: 0.7 mm, size: 100 mm × 100 mm) whose amount of warpage had been measured in advance. was applied with a spin coater, heated in air at 120° C. for 30 minutes, and then heated at 430° C. in a nitrogen atmosphere for 30 minutes to obtain a laminate having a polyimide film having a thickness of 10 μm on a glass substrate. In order to eliminate the influence of water absorption of the polyimide film, the laminate was dried at 120 ° C. for 10 minutes, and then the amount of warpage of the laminate in a nitrogen atmosphere at a temperature of 25 ° C. was measured using a thin film stress measurement device (manufactured by KLA-Tencor Co., Ltd. "FLX-2320-S"). Then, the internal stress generated between the glass substrate and the polyimide film was calculated from the amount of warpage of the glass substrate before the formation of the polyimide film and the amount of warpage of the laminate by the Stoney equation.

[Yellowness index (YI)]
For the polyimide film in each laminate obtained in Examples and Comparative Examples described later, an ultraviolet-visible near-infrared spectrophotometer (manufactured by JASCO Corporation "V-650") was used to measure light with a wavelength of 200 nm or more and 800 nm or less. The transmittance was measured, and the yellowness index (YI) of the polyimide film was calculated from the formula described in JIS K7373-2006.

[Yellowness change (ΔYI)]
Each polyamic acid composition prepared in Examples and Comparative Examples described later was spun on a glass substrate manufactured by Corning (trade name: Eagle XG, material: non-alkali glass, thickness: 0.7 mm, size: 100 mm × 100 mm). After coating with a coater and heating at 120° C. for 30 minutes in the air, the solution was heated at 430° C. for 30 minutes in a nitrogen atmosphere to form a polyimide film having a thickness of 10 μm on the glass substrate. Then, a SiOx film (thickness: 1 μm) was laminated on the obtained polyimide film by a plasma CVD method. For the obtained laminate, the transmittance of light with a wavelength of 200 nm or more and 800 nm or less is measured using an ultraviolet-visible-near-infrared spectrophotometer (manufactured by JASCO Corporation "V-650"), and the transmittance is described in JIS K7373-2006. The yellowness index (YI) of the laminate was calculated from the formula. Hereinafter, the yellowness index (YI) obtained here is referred to as "pre-annealing YI".

Next, the laminate after measuring the pre-annealing YI was heated (annealed) at 430°C for 120 minutes in a nitrogen atmosphere. Then, for the laminate after annealing, the transmittance of light with a wavelength of 200 nm or more and 800 nm or less was measured using an ultraviolet-visible-near-infrared spectrophotometer (manufactured by JASCO Corporation "V-650"). The yellowness index (YI) of the laminate was calculated from the formula described. Hereinafter, the yellowness index (YI) obtained here is referred to as "post-annealing YI". Then, the change in yellowness (ΔYI) was calculated according to the formula “ΔYI=YI after annealing−YI before annealing”. When ΔYI was less than 10, it was evaluated as "coloring in high-temperature process can be reduced". On the other hand, when ΔYI was 10 or more, it was evaluated as "coloring in high temperature process cannot be reduced".

[Total light transmittance (TT)]
For the polyimide film peeled from each laminate obtained in Examples and Comparative Examples described later, using an integrating sphere haze meter ("HM-150N" manufactured by Murakami Color Research Laboratory Co., Ltd.), JIS K7361-1: 1997 Total light transmittance (TT) was measured by the method described in .

[Haze]
For the polyimide film peeled from each laminate obtained in Examples and Comparative Examples described later, using an integrating sphere haze meter ("HM-150N" manufactured by Murakami Color Research Laboratory), described in JIS K7136-2000. Haze was measured by the method of. When the haze was less than 1.0%, it was evaluated as "excellent in transparency". On the other hand, when the haze was 1.0% or more, it was evaluated as "not excellent in transparency".

[Glass transition temperature (Tg)]
A polyimide film having a width of 3 mm and a length of 10 mm was sampled from each laminate obtained in Examples and Comparative Examples, which will be described later, and used as a sample for Tg measurement. Using a thermal analyzer ("TMA/SS7100" manufactured by Hitachi High-Tech Science), a load of 98.0 mN was applied to the sample, the temperature was raised from 20 ° C. to 450 ° C. at 10 ° C./min, and the temperature and strain amount (elongation ) to obtain the TMA curve. The temperature at the inflection point of the obtained TMA curve (the temperature corresponding to the peak in the differential curve of the TMA curve) was defined as the glass transition temperature (Tg).

<Preparation of polyimide film>
Methods for producing polyimide films (laminates) of Examples and Comparative Examples will be described below. Compounds and reagents are abbreviated below. Moreover, preparation of the polyamic acid composition used for preparation of the polyimide film was carried out under a nitrogen atmosphere.
NMP: N-methyl-2-pyrrolidone BPDA: 3,3',4,4'-biphenyltetracarboxylic dianhydride 6FDA: 4,4'-(hexafluoroisopropylidene)diphthalic anhydride 4-BAAB: 4 -aminophenyl-4-aminobenzoate PDA: p-phenylenediamine BAFL: 9,9-bis(4-aminophenyl)fluorene 6FODA: 2,2'-bis(trifluoromethyl)-4,4'-diaminodiphenyl ether CHDA : 1,4-cyclohexanediamine DMI: 1,2-dimethylimidazole

[Example 1]
A 300 mL glass separable flask equipped with a stirrer equipped with a stainless steel stir bar and a nitrogen inlet was charged with 48.0 g of NMP as an organic solvent for polymerization. 5.026 g of 4-BAAB was then added to the flask and dissolved while stirring the flask contents. After adding 1.467 g of 6FDA and 5.507 g of BPDA to the contents of the flask, the contents of the flask were stirred for 24 hours under an atmosphere of 25° C. to obtain a polyamic acid composition. The resulting polyamic acid composition was applied onto a glass substrate (manufactured by Corning, material: non-alkali glass, thickness: 0.7 mm, size: 100 mm x 100 mm) using a spin coater, and coated in air at 120°C. After heating for 30 minutes, it was heated at 430° C. for 30 minutes in a nitrogen atmosphere to obtain a laminate (laminate of Example 1) having a polyimide film having a thickness of 10 μm on a glass substrate.

[Example 2]
A 300 mL glass separable flask equipped with a stirrer equipped with a stainless steel stir bar and a nitrogen inlet was charged with 48.0 g of NMP as an organic solvent for polymerization. 5.026 g of 4-BAAB was then added to the flask and dissolved while stirring the flask contents. After adding 1.467 g of 6FDA and 5.507 g of BPDA to the contents of the flask, the contents of the flask were stirred for 24 hours under an atmosphere at a temperature of 25°C. Next, DMI was added to the contents of the flask to obtain a polyamic acid composition. The amount of DMI added was 1 part by weight per 100 parts by weight of polyamic acid in the contents of the flask. The resulting polyamic acid composition was applied onto a glass substrate (manufactured by Corning, material: non-alkali glass, thickness: 0.7 mm, size: 100 mm x 100 mm) using a spin coater, and coated in air at 120°C. After heating for 30 minutes, it was heated at 430° C. for 30 minutes in a nitrogen atmosphere to obtain a laminate (laminate of Example 2) having a polyimide film having a thickness of 10 μm on a glass substrate.

[Examples 3 to 8 and Comparative Examples 1 to 3]
Examples 3 and 5 to 8 and Comparative Examples were prepared in the same manner as in Example 1 except that the acid dianhydride used and its charging ratio, and the diamine used and its charging ratio were as shown in Table 1. Laminates 1 and 2 were obtained, respectively. In addition, the acid dianhydride used and its charging ratio, and the diamine used and its charging ratio were as shown in Table 1, in the same manner as in Example 2. A laminate was obtained, respectively. Incidentally, in both Examples 3 to 8 and Comparative Examples 1 to 3, the total substance amount of the acid dianhydride in preparing the polyamic acid composition was the same as in Examples 1 and 2. Further, in all of Examples 3 to 8 and Comparative Examples 1 to 3, the total substance amount of diamine in preparing the polyamic acid composition was the same as in Examples 1 and 2.

Table 1 shows the materials used and the measurement results of physical properties for each of Examples 1 to 8 and Comparative Examples 1 to 3. In Table 1, "-" means that the component was not used. In Table 1, the numerical values in the "acid dianhydride" column are the content of each acid dianhydride relative to the total amount of acid dianhydride used (unit: mol%). In Table 1, the numerical values in the "diamine" column are the content of each diamine relative to the total amount of diamines used (unit: mol %). In Table 1, the numerical value in the "DMI" column is the amount of DMI (unit: parts by weight) per 100 parts by weight of polyamic acid. In addition, in both Examples 1 to 8 and Comparative Examples 1 to 3, the molar fraction of each residue of polyamic acid in the prepared polyamic acid composition was different from each monomer (diamine and tetracarboxylic dianhydride).

The polyamic acids in the polyamic acid compositions prepared in Examples 1-8 had BPDA residues and 6FDA residues, and had 4-BAAB residues. In the polyamic acids in the polyamic acid compositions prepared in Examples 1 to 8, the content of BPDA residues was 65 mol% or more and 97 mol% or less with respect to all tetracarboxylic dianhydride residues. . In the polyamic acids in the polyamic acid compositions prepared in Examples 1 to 8, the content of 6FDA residues was 3 mol% or more and 35 mol% or less with respect to all tetracarboxylic dianhydride residues. . In the polyamic acids in the polyamic acid compositions prepared in Examples 1 to 8, the content of 4-BAAB residues was 50 mol% or more with respect to the total diamine residues.

In Examples 1 to 8, ΔYI was less than 10. Therefore, the polyimides obtained in Examples 1 to 8 were able to reduce coloring in high-temperature processes. Examples 1-8 had a haze of less than 1.0%. Therefore, the polyimides obtained in Examples 1 to 8 were excellent in transparency.

The polyamic acid in the polyamic acid composition prepared in Comparative Example 1 did not have 6FDA residues. In the polyamic acids in the polyamic acid compositions prepared in Comparative Examples 2 and 3, the content of 6FDA residues exceeded 35 mol % with respect to the total tetracarboxylic dianhydride residues.

In Comparative Examples 1 and 3, the haze was 1.0% or more. Therefore, the polyimides obtained in Comparative Examples 1 and 3 were not excellent in transparency. In Comparative Examples 2 and 3, ΔYI was 10 or more. Therefore, the polyimides obtained in Comparative Examples 2 and 3 were not able to reduce the coloring in the high-temperature process.

From the above results, it was shown that the polyimide obtained from the polyamic acid composition according to the present invention has excellent transparency and can reduce coloration in high-temperature processes.

Claims

As tetracarboxylic dianhydride residues, 3,3',4,4'-biphenyltetracarboxylic dianhydride residues and 4,4'-(hexafluoroisopropylidene) diphthalic anhydride residues , and having a 4-aminophenyl-4-aminobenzoate residue as a diamine residue,
The content of the 3,3',4,4'-biphenyltetracarboxylic dianhydride residue is 65 mol% or more and 97 mol% or less with respect to the total tetracarboxylic dianhydride residue,
The content of the 4,4'-(hexafluoroisopropylidene)diphthalic anhydride residue is 3 mol% or more and 35 mol% or less with respect to all tetracarboxylic dianhydride residues,
Polyamic acid, wherein the content of the 4-aminophenyl-4-aminobenzoate residue is 50 mol% or more with respect to all diamine residues.
When the content of the 4-aminophenyl-4-aminobenzoate residue is less than 100 mol% with respect to all diamine residues, diamine residues other than the 4-aminophenyl-4-aminobenzoate residue are p-phenylenediamine residue, 9,9-bis(4-aminophenyl)fluorene residue, 2,2′-bis(trifluoromethyl)-4,4′-diaminodiphenyl ether residue, and 1,4-cyclohexane The polyamic acid according to claim 1, which is one or more selected from the group consisting of diamine residues.
The polyamic acid according to claim 1, wherein the content of said 4-aminophenyl-4-aminobenzoate residues is 100 mol% with respect to all diamine residues.
The polyamic acid according to claim 2, wherein the content of diamine residues other than the 4-aminophenyl-4-aminobenzoate residues is 5 mol% or more and 50 mol% or less with respect to all diamine residues.
A polyamic acid composition containing the polyamic acid according to claim 1 and an organic solvent.
The polyamic acid composition according to claim 5, further comprising an imidization accelerator.
The polyamic acid composition according to claim 6, wherein the amount of the imidization accelerator is 0.1 parts by weight or more and 10 parts by weight or less with respect to 100 parts by weight of the polyamic acid.
A polyimide which is an imidized product of the polyamic acid according to claim 1.
A polyimide film containing the polyimide according to claim 8.
The polyimide film according to claim 9, which has a yellowness index of 20 or less.
A laminate comprising a support and the polyimide film according to claim 9.
The support is a glass substrate,
12. The laminate according to claim 11, wherein the internal stress between said polyimide film and said glass substrate is 25 MPa or less.
A method for producing a laminate having a support and a polyimide film,
Manufacture of a laminate by applying the polyamic acid composition according to claim 5 onto a support to form a coating film containing the polyamic acid, and heating the coating film to imidize the polyamic acid. Method.
An electronic device comprising the polyimide film according to claim 9 and an electronic element arranged on the polyimide film.