WO2023157790A1

WO2023157790A1 - Polyamide acid, polyamide acid composition, polyimide, polyimide film, laminate, method for producing laminate, and electronic device

Info

Publication number: WO2023157790A1
Application number: PCT/JP2023/004720
Authority: WO
Inventors: 博文中山; 友貴白井
Original assignee: 株式会社カネカ
Priority date: 2022-02-16
Filing date: 2023-02-13
Publication date: 2023-08-24

Abstract

A polyamide acid according to the present invention has a tetracarboxylic acid dianhydride residue and a diamine residue. The tetracarboxylic dianhydride residue includes a 3,3',4,4'-biphenyltetracarboxylic dianhydride residue and a spiro[11H-difuro[3,4-b:3',4'-i]xanthene-11,9'-[9H]fluorene]-1,3,7,9-tetrone residue. The diamine residue comprises a 2,2'-bis(trifluoromethyl)benzidine residue. The content of the 3,3',4,4'-biphenyltetracarboxylic dianhydride residue is more than 50 mol% with respect to the total amount of tetracarboxylic dianhydride residue. The content of the spiro[11H-difuro[3,4-b:3',4'-i]xanthene-11,9'-[9H]fluorene]-1,3,7,9-tetrone residue is greater than or equal to 1 mol% and less than 50 mol% with respect to the total amount of the tetracarboxylic dianhydride residue.

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.

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

In applications where transparency is required, from the viewpoint of color reproducibility, particularly high transmittance of blue light (light with a wavelength of around 470 nm) is required. is required to be high. The inventors' studies have revealed that the polyimide described in Patent Document 3 has a relatively low transmittance for light with a wavelength of 400 nm.

Further, when a polyimide having a high CTE is used when forming a polyimide film on a support to obtain a laminate, internal stress generated at the interface between the support and the polyimide film is large due to heating and cooling in the laminate formation process. tend to become Therefore, when a laminate is formed using polyimide having a high CTE, the laminate is likely to warp, which may make it difficult to apply the laminate to electronic devices.

With only the technique described in Patent Document 3, the internal stress between the support and the polyimide film (hereinafter sometimes simply referred to as "internal stress") is reduced, while the transmittance of light with a wavelength of 400 nm is high. Obtaining polyimide is difficult.

The present invention has been accomplished in view of the above circumstances, and an object of the present invention is to provide a polyimide having a high transmittance for light with a wavelength of 400 nm and a polyamic acid as its precursor while reducing internal stress. 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 heat resistance and 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] A polyamic acid having a tetracarboxylic dianhydride residue and a diamine residue,
The tetracarboxylic dianhydride residues include 3,3′,4,4′-biphenyltetracarboxylic dianhydride residues and spiro[11H-difuro[3,4-b:3′,4′- i]xanthene-11,9′-[9H]fluorene]-1,3,7,9-tetrone residues,
The diamine residue comprises a 2,2′-bis(trifluoromethyl)benzidine residue,
The content of the 3,3′,4,4′-biphenyltetracarboxylic dianhydride residue is more than 50 mol% with respect to the total amount of the tetracarboxylic dianhydride residue,
The spiro[11H-diflo[3,4-b:3′,4′-i]xanthene-11,9′-[9H]fluorene]-1,3,7,9-tetrone residue content is A polyamic acid that is 1 mol % or more and less than 50 mol % relative to the total amount of the tetracarboxylic dianhydride residue.

[2] The above-mentioned [1], wherein the content of the 2,2'-bis(trifluoromethyl)benzidine residue is 50 mol% or more and 100 mol% or less with respect to the total amount of the diamine residue. polyamic acid.

[3] A polyamic acid composition containing the polyamic acid according to [1] or [2] above and an organic solvent.

[4] The polyamic acid composition according to [3] above, which further contains a plasticizer.

[5] The polyamic acid composition according to [4], wherein the amount of the plasticizer is 20 parts by weight or less with respect to 100 parts by weight of the polyamic acid.

[6] The polyamic acid composition according to [4] or [5], wherein the plasticizer is one or more selected from the group consisting of phosphorus-containing compounds, polyalkylene glycols and aliphatic dibasic acid esters.

[7] The polyamic acid composition according to any one of [3] to [6], further comprising an imidization accelerator.

[8] The polyamic acid composition according to [7], wherein the amount of the imidization accelerator is 0.1 parts by weight or more and 20 parts by weight or less with respect to 100 parts by weight of the polyamic acid.

[9] The polyamic acid composition according to [7] or [8], wherein the imidization accelerator has a 1,3-diazole ring.

[10] A polyimide which is an imidized polyamic acid according to [1] or [2].

[11] A polyimide film containing the polyimide described in [10] above.

[12] The polyimide film according to [11] above, which has a transmittance of 45% or more for light having a wavelength of 400 nm.

[13] The polyimide film according to [11] or [12] above, which has a haze of 1.0% or less.

[14] A laminate comprising a support and the polyimide film according to any one of [11] to [13].

[15] The support is a glass substrate,
The laminate according to [14], wherein the internal stress between the polyimide film and the glass substrate is 40 MPa or less.

[16] A method for producing a laminate having a support and a polyimide film,
By applying the polyamic acid composition according to any one of [3] to [9] 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.

[17] An electronic device comprising the polyimide film according to any one of [11] to [13] and an electronic element disposed on the polyimide film.

The polyimide produced using the polyamic acid according to the present invention has high transmittance for light with a wavelength of 400 nm while reducing internal stress. Therefore, the polyimide produced using the polyamic acid according to the present invention is suitable as a material for electronic devices that require transparency and are produced through high-temperature processes.

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 %.

"Plasticizer" refers to a material that exists as a liquid during the imidization of at least a portion of polyamic acid.

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

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)") has a tetracarboxylic dianhydride residue and a diamine residue.

In polyamic acid (1), the tetracarboxylic dianhydride residue is 3,3′,4,4′-biphenyltetracarboxylic dianhydride residue, and spiro[11H-difuro[3,4-b: 3′,4′-i]xanthene-11,9′-[9H]fluorene]-1,3,7,9-tetrone residues. That is, polyamic acid (1) contains, as tetracarboxylic dianhydride residues, 3,3′,4,4′-biphenyltetracarboxylic dianhydride residues and spiro[11H-diflo[3,4- b: Contains 3′,4′-i]xanthene-11,9′-[9H]fluorene]-1,3,7,9-tetrone residues.

In addition, in polyamic acid (1), the diamine residue includes a 2,2'-bis(trifluoromethyl)benzidine residue. That is, polyamic acid (1) contains a 2,2'-bis(trifluoromethyl)benzidine residue as a diamine residue.

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 Spiro[11H-diflo[3,4-b:3′,4′-i]xanthene-11,9′-[9H]fluorene]-1,3,7,9-tetrone residue is spiro[11H- Diflo[3,4-b:3′,4′-i]xanthene-11,9′-[9H]fluorene]-1,3,7,9-tetrone (hereinafter sometimes referred to as “SFDA” ) is the partial structure derived from The 2,2'-bis(trifluoromethyl)benzidine residue is a partial structure derived from 2,2'-bis(trifluoromethyl)benzidine (hereinafter sometimes referred to as "TFMB"). The SFDA residue is a tetravalent organic group represented by the following chemical formula (2).

In polyamic acid (1), the content of BPDA residues is more than 50 mol% relative to the total amount of tetracarboxylic dianhydride residues. In polyamic acid (1), the content of SFDA residues is 1 mol % or more and less than 50 mol % with respect to the total amount of tetracarboxylic dianhydride residues.

BPDA has a highly linear structure, and by combining it with a rigid and highly linear diamine such as TFMB, it is possible to easily achieve a low CTE. ing.

SFDA has a bulky fluorene structure like 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride (hereinafter sometimes referred to as "BPAF"), which has a similar structure. Therefore, it suppresses the aggregation of molecules and contributes to the improvement of transparency. Therefore, SFDA is suitable as a raw material (monomer) for polyimide having a high transmittance for light with a wavelength of 400 nm (hereinafter sometimes referred to as "400 nm transmittance"). In addition, since SFDA has a xanthene structure, it has high linearity and can easily achieve a low CTE compared to BPAF. Therefore, compared with BPAF, SFDA is suitable as a polyimide raw material (monomer) capable of reducing internal stress.

In general, polyimide formed from BPDA and TFMB is imidized at a high temperature exceeding 400° C., resulting in a high film haze due to crystallization. In contrast, polyimide formed from polyamic acid (1) can suppress crystallization and reduce haze by using SFDA, which has a bulky structure, together with BPDA.

　TFMB has high linearity and can easily achieve a low CTE, so it is suitable as a raw material (monomer) for polyimide that can reduce internal stress. Moreover, TFMB contributes to improvement in transparency because it has a trifluoromethyl group. Therefore, TFMB is suitable as a raw material (monomer) for polyimide with high 400 nm transmittance.

As a result of intensive studies, the present inventors found that polyamic acid (polyamic acid (1) ) has a high transmittance for light with a wavelength of 400 nm while reducing internal stress. Specifically, in polyamic acid (1), the content of BPDA residues is more than 50 mol% with respect to the total amount of tetracarboxylic dianhydride residues, and the content of SFDA residues is It is 1 mol % or more and less than 50 mol % with respect to the total amount of acid dianhydride residues.

When synthesizing polyamic acid (1), an acid dianhydride other than BPDA and SFDA may be used as a monomer within a range that does not impair its performance. Acid dianhydrides other than BPDA and SFDA include, for example, pyromellitic dianhydride (hereinafter sometimes referred to as "PMDA"), p-phenylene bis(trimellitate anhydride), 1,2,5, 6-naphthalenetetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 2,2′,3,3′-biphenyltetracarboxylic dianhydride, 3,3′,4 ,4'-benzophenonetetracarboxylic dianhydride, 4,4'-dioxydiphthalic anhydride, dicyclohexyl-3,3',4,4'-tetracarboxylic dianhydride, 1,2,4,5-cyclohexane Tetracarboxylic 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, and these may be used alone or in combination of two or more. good.

In order to obtain a polyimide that can further reduce internal stress, the content of BPDA residues is 55 mol% or more with respect to the total amount of tetracarboxylic dianhydride residues constituting polyamic acid (1). is preferably 58 mol % or more, more preferably 60 mol % or more, and even more preferably 65 mol % or more. Further, in order to obtain a polyimide with a higher 400 nm transmittance, the content of BPDA residues is 99 mol% or less with respect to the total amount of tetracarboxylic dianhydride residues constituting polyamic acid (1). is preferably 95 mol% or less, more preferably 90 mol% or less, even more preferably 85 mol% or less, 80 mol% or less, 75 mol% or less, or 70 It may be mol % or less.

In order to obtain a polyimide with a higher 400 nm transmittance, the content of SFDA residues is 3 mol% or more with respect to the total amount of tetracarboxylic dianhydride residues constituting polyamic acid (1). is preferably 5 mol% or more, more preferably 10 mol% or more, even more preferably 15 mol% or more, 20 mol% or more, 25 mol% or more, or 30 mol% or more. Further, in order to obtain a polyimide that can further reduce the internal stress, the content of the SFDA residue is 45 mol% or less with respect to the total amount of the tetracarboxylic dianhydride residue constituting the polyamic acid (1). preferably 42 mol % or less, even more preferably 40 mol % or less, even more preferably 35 mol % or less.

In order to obtain a polyimide with a higher 400 nm transmittance while further reducing internal stress, the total content of BPDA residues and SFDA residues is a tetracarboxylic acid dianhydride residue that constitutes polyamic acid (1) It is preferably 60 mol% or more, more preferably 70 mol% or more, still more preferably 80 mol% or more, and even more preferably 90 mol% or more, relative to the total amount of It may be 100 mol %.

When synthesizing polyamic acid (1), a diamine other than TFMB may be used as a monomer within a range that does not impair its performance. Examples of diamines other than TFMB include p-phenylenediamine, 4-aminophenyl-4-aminobenzoate, 9,9-bis(4-aminophenyl)fluorene, 2,2′-bis(trifluoromethyl)-4 ,4'-diaminodiphenyl ether, 1,4-cyclohexanediamine, 4,4'-diaminobenzanilide, m-phenylenediamine, 4,4'-oxydianiline, 3,4'-oxydianiline, 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-amino propyl)tetramethyldisiloxane and derivatives thereof, and these may be used singly or in combination of two or more.

In order to obtain a polyimide with a higher 400 nm transmittance while further reducing internal stress, the content of TFMB residues is 50 mol% or more with respect to the total amount of diamine residues constituting polyamic acid (1). It is preferably 100 mol% or less, more preferably 60 mol% or more and 100 mol% or less, even more preferably 70 mol% or more and 100 mol% or less, and 80 mol% or more and 100 mol% or less. is even more preferable, and it is particularly preferably 90 mol % or more and 100 mol % or less, and may be 100 mol %.

In order to obtain a polyimide having a higher 400 nm transmittance while further reducing the internal stress, the polyamic acid (1) preferably satisfies the following condition 1, more preferably satisfies the following condition 2, and the following condition 3. is more preferably satisfied.
Condition 1: The total content of BPDA residues and SFDA residues is 100 mol% with respect to the total amount of tetracarboxylic dianhydride residues constituting polyamic acid (1).
Condition 2: Condition 1 above is satisfied, and the content of TFMB residues is 100 mol % with respect to the total amount of diamine residues constituting polyamic acid (1).
Condition 3: The condition 2 above is satisfied, and the content of the SFDA residue is 5 mol% or more and 35 mol% or less with respect to the total amount of the tetracarboxylic dianhydride residue constituting the polyamic acid (1). .

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 polyamic acid (1) 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 tetracarboxylic dianhydride By adjusting the amount of substance (when using multiple types of tetracarboxylic dianhydrides, the amount of each tetracarboxylic dianhydride), the desired polyamic acid (1) (diamine and tetracarboxylic acid dianhydride polymer with anhydride) 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 acid. 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 appropriate 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 include the organic solvents exemplified as the organic solvent that can be used in the synthesis reaction of the polyamic acid (1), including amide solvents, ketone solvents, ester solvents and One or more solvents selected from the group consisting of 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 20 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 20 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.

The effect of the plasticizer that can be blended in the polyamic acid composition according to the present embodiment will be described. In general, when trying to obtain a transparent polyimide film, in principle, it is sufficient to design a polyimide with a large bandgap between HOMO and LUMO. is. On the other hand, TFMB, which has a low electron-donating property, is expected to have a low reaction rate and a low imidization rate due to its low nucleophilicity. When the present inventors examined the imidization rate, the following findings were obtained. That is, when the imidization rate of a general colored polyimide obtained from BPDA and p-phenylenediamine and a transparent polyimide obtained from PMDA or BPDA and TFMB were compared, the colored polyimide had an imidization reaction temperature of 300°C. At an imidization reaction temperature of 350°C, the imidation was 90% or more, and nearly 100%. However, a clear difference in the imidization rate was observed.

In general, the driving force during dehydration ring closure from polyamic acid to polyimide by thermal imidization is largely due to molecular motion due to heat and the plasticizing effect of the solvent. should be treated. However, when a rigid acid dianhydride such as BPDA is combined with TFMB, the resulting polyimide has a glass transition temperature exceeding 400° C., sometimes higher than the heat treatment temperature during film formation. Therefore, in the imidization reaction between a rigid acid dianhydride such as BPDA and TFMB, the imidization may not proceed completely. For this reason, for example, in a high-temperature process using a polyimide film (for example, dehydrogenation treatment of TFT elements), imidization of unreacted sites in the polyimide film progresses, and outgassing ( For example, hydrogen fluoride, etc.) is generated, which may cause peeling of the barrier film, corrosion of the TFT, and the like. In contrast, by adding a plasticizer to the polyamic acid composition, sufficient molecular motion is imparted during the imidization of the polyamic acid (1), and not only the imidization proceeds completely, but also the polyamic acid (1) ) is also suppressed, and the generation of outgassing (in particular, hydrogen fluoride) can be suppressed. Furthermore, by blending a plasticizer in the polyamic acid composition, the solvent is also easily removed by imparting molecular motion to the polyamic acid (1), the amount of residual solvent in the film (polyimide film) is reduced, Film coloration is also reduced.

As a plasticizer that can be used in this embodiment, a material that dissolves in the solvent used for imidizing the polyamic acid (1) is preferable. Moreover, the plasticizer preferably does not volatilize at low temperatures in order to impart sufficient molecular mobility to the polyamic acid (1) during imidization. Therefore, the boiling point of the plasticizer is preferably 50°C or higher, more preferably 100°C or higher, and even more preferably 150°C or higher. Moreover, the plasticizer preferably does not have a decomposition temperature below the boiling point in order to impart sufficient molecular mobility to the polyamic acid (1) during imidization.

From the viewpoint of avoiding decomposition of the plasticizer itself, the amount of the plasticizer is preferably 20 parts by weight or less, more preferably 10 parts by weight or less, relative to 100 parts by weight of polyamic acid (1). In addition, the amount of the plasticizer is 0.001 weight per 100 parts by weight of the polyamic acid (1) from the viewpoint of imparting sufficient molecular mobility to the polyamic acid (1) and avoiding decomposition of the plasticizer itself. parts by weight or more and 20 parts by weight or less, more preferably 0.01 parts by weight or more and 10 parts by weight or less, still more preferably 0.01 parts by weight or more and 8 parts by weight or less, and 0.1 parts by weight Part or more and 6 parts by weight or less is even more preferable.

In order to further suppress the generation of hydrogen fluoride when used in high-temperature processes, the plasticizer should be selected from the group consisting of phosphorus-containing compounds (compounds containing phosphorus), polyalkylene glycols, and aliphatic dibasic acid esters. It is preferable to use one or more of the

Preferred examples of phosphorus-containing compounds include phosphoric acid compounds, phosphorous acid compounds, phosphonic acid compounds, phosphinic acid compounds, phosphine compounds, phosphine oxide compounds, phosphorane compounds, phosphazene compounds, and the like. . The phosphorus-containing compound may be an ester of the compounds listed above or a condensate thereof, may contain a cyclic structure, or may form a salt with an amine or the like. Further, some of these phosphorus-containing compounds have a tautomeric relationship, such as a phosphorous acid-based compound and a phosphonic acid-based compound, but they may exist in either state.

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

Specific examples of phosphorous acid compounds include triphenylphosphite, trisnonylphenylphosphite, tricresylphosphite, triethylphosphite, triisobutylphosphite, tris(2-ethylhexyl)phosphite and tridecylphosphite. , trilauryl phosphite, tris (tridecyl) phosphite, diphenyl phosphite, diethyl phosphite, dibutyl phosphite, dimethyl phosphite, diphenyl mono (2-ethylhexyl) phosphite, diphenyl monodecyl phosphite, diphenyl mono (tridecyl) phosphites, trilauryl trithiophosphite, diethyl hydrogen phosphite, bis(2-ethylhexyl) hydrogen phosphite, dilauryl hydrogen phosphite, dioleyl hydrogen phosphite, diphenyl hydrogen phosphite, tetraphenyl dipropylene glycol diphosphite, bis (decyl) pentaerythritol diphosphite, bis (tridecyl) pentaerythritol diphosphite, tristearyl phosphite, distearyl pentaerythritol diphosphite, tris (2,4-di-tert-butylphenyl) phosphite, tri isodecylphosphite, 3,9-bis(2,6-di-tert-butyl-4-methylphenoxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane and the like mentioned.

Examples of the condensates include condensed phosphate esters. Specific examples of the condensed phosphate include trialkyl polyphosphate, resorcinol polyphenyl phosphate, resorcinol poly(di-2,6-xylyl) phosphate, hydroquinone poly(2,6-xylyl) phosphate, and the like. Commercially available condensed phosphate esters include, for example, "CR-733S" manufactured by Daihachi Chemical Industry Co., Ltd., "CR-741" manufactured by Daihachi Chemical Industry Co., Ltd., "PX-200" manufactured by Daihachi Chemical Industry Co., Ltd., and ADEKA. and "FP-600" manufactured by K.K.

Specific examples of phosphazene compounds include phenoxycyclophosphazene (“FP-110” manufactured by Fushimi Pharmaceutical Co., Ltd.), cyclic cyanophenoxyphosphazene (“FP-300” manufactured by Fushimi Pharmaceutical Co., Ltd.), and the like.

Specific examples of polyalkylene glycol include polypropylene glycol and polyethylene glycol.

Specific examples of aliphatic dibasic acid esters include dibutyl adipate, diisobutyl adipate, bis(2-ethylhexyl) adipate, diisononyl adipate, diisodecyl adipate, bis[2-(2-butoxyethoxy)ethyl]adipate, bis(2- ethylhexyl)azelate, dibutyl sebacate, bis(2-ethylhexyl) sebacate, diethyl succinate and the like.

In addition, the plasticizer may be a low-molecular-weight organic compound or a thermoplastic resin as long as it exhibits a plasticizing effect. Examples of the low-molecular-weight organic compounds include organic compounds having a molecular weight of about 1,000 or less, such as phenolic compounds; Phthalimide compounds; maleimide compounds such as N,Np-phenylenebismaleimide and 2,2'-(ethylenedioxy)bis(ethylmaleimide). Examples of the thermoplastic resin include polyimide and polyamide having an asymmetric structure.

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 from 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 may be lower than the molecular weight of the polyamic acid composition, before forming the polyimide film described later, a part of the polyamic acid (1) in the polyamic acid composition may be pre-imidized 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. Examples of components other than polyimide in the polyimide film include 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, the present inventors' studies have revealed that polyimides obtained using fluorine-containing monomers generate corrosive gases such as hydrogen fluoride as outgassing in high-temperature processes such as the fabrication of TFT elements. . When corrosive gas is generated in a high-temperature process, a barrier film or the like laminated on the polyimide film may corrode. In order to suppress the generation of corrosive gas, it is preferable to add the plasticizer described above to the polyamic acid composition according to the present embodiment.

As an indicator of the amount of hydrogen fluoride gas generated when the imidized product of polyamic acid (1) (the polyimide according to the present embodiment) is used in a high-temperature process, detection intensity obtained from a mass spectrum can be mentioned. Specifically, first, the polyimide is heated from an atmospheric temperature of 60° C. at a rate of 10° C./min under a helium gas stream, and the gas generated from the polyimide when the atmospheric temperature reaches 470° C. Analyze with a type mass spectrometer. Then, from the obtained mass spectrum (specifically, the mass spectrum showing the results of analysis of the components of the gas generated from the polyimide when the ambient temperature reached 470 ° C.), m / The detected intensity of the peak at z=20 (hereinafter sometimes referred to as "20 peak intensity") is read. The 20 peak intensity tends to increase as the amount of hydrogen fluoride generated increases. The flow rate of the helium gas when analyzing with a quadrupole mass spectrometer may be set so that the gas generated from the polyimide can be analyzed in real time with the quadrupole mass spectrometer. minutes or more and 150 mL/minute or less, preferably 80 mL/minute or more and 120 mL/minute or less.

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, in a laminate (laminate according to the present embodiment) having a glass substrate (support) and a polyimide film, the internal stress between the polyimide film and the glass substrate is preferably 40 MPa or less, and 35 MPa or less. It is more preferable to have 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.

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 release layer between a support and a polyimide film, a method of forming a silicon oxide film on a substrate having a large number of grooves, forming a polyimide film using the silicon oxide film as a base layer, and oxidizing the substrate and the polyimide film. A method of exfoliating the polyimide film by infiltrating a silicon oxide etchant between it and the silicon film can also be adopted. 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 below, 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 SFDA 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, as described above, in applications where transparency is required, from the viewpoint of color reproducibility, it is particularly required that the transmittance of blue light (light near the wavelength of 470 nm) is high. is required to have high light transmittance (400 nm transmittance). From the viewpoint of color reproducibility, etc., the 400 nm transmittance of the polyimide film is preferably 45% or more, more preferably 50% or more, even more preferably 55% or more, and 60% or more. is even more preferred. The upper limit of the 400 nm transmittance of the polyimide film is not particularly limited, and may be 100%.

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. In the top emission method, light is not blocked by the TFT, so it is easy to increase the aperture ratio and obtain high-definition image quality. 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 and the like 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 suitable for a method for producing a polyimide film, in which the polyamic acid composition is applied onto a support, imidized by heating, and then the polyimide film is peeled off from the support. can be used. Further, the polyamic acid composition according to the present embodiment is coated with a polyamic acid composition on a support, imidized by heating, and after forming an electronic element or the like on the formed polyimide film, from the support, It can be suitably used for a batch-type device manufacturing process for peeling off a polyimide film on which electronic elements and the like are formed. Therefore, in the present embodiment, the production of an electronic device includes the step of applying a polyamic acid composition on a support, imidizing it by heating, and forming an electronic element or the like on the 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.

[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.

[Cutoff wavelength]
Of the transmittance of light with a wavelength of 200 nm or more and 800 nm or less when measured by the above [yellowness index (YI)] measurement method, the wavelength at which the transmittance was 0.1% or less was taken as the cutoff wavelength.

[400 nm transmittance]
For the polyimide film in each laminate obtained in Examples and Comparative Examples described later, the transmittance of light with a wavelength of 400 nm ( 400 nm transmittance) was measured. When the 400 nm transmittance was 45% or more, it was evaluated as "high transmittance of light with a wavelength of 400 nm". On the other hand, when the 400 nm transmittance was less than 45%, it was evaluated as "the transmittance of light with a wavelength of 400 nm is not high".

[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.

[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. When the internal stress was 40 MPa or less, it was evaluated as "the internal stress can be reduced." On the other hand, when the internal stress exceeded 40 MPa, it was evaluated as "the internal stress cannot be reduced."

[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 Example 3 and Comparative Example 1, 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 500 ° 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). In Example 3, the Tg was 440°C. In Comparative Example 1, Tg was 355°C.

[Analysis of gas generated from polyimide film]
Using an analysis device that combines a thermogravimetric measurement device (“STA449 F5” manufactured by NETZSCH) and a quadrupole mass spectrometer (“JMS-Q1500GC” manufactured by JEOL Ltd.), the polyimide film generated during heating Gas was analyzed. The analysis procedure will be described below.

First, using perfluorotributylamine as a standard substance, the voltage of the quadrupole mass spectrometer was adjusted so that the detection intensity of the peak at m/z=69 was 800,000. Then, using the thermogravimetry apparatus, the temperature was increased from 60 ° C. to 10 ° C./min under a helium gas flow at a flow rate of 100 mL / min. Each polyimide film (specifically, a polyimide film sampled from each laminate so that the mass is 140 mg) is heated and the gas generated from the polyimide film when the atmospheric temperature reaches 470 ° C. is Analyzed by mass spectrometer. By heating the polyimide film under a helium gas stream using the analyzer, the helium gas becomes a carrier gas, and the gas generated from the polyimide film can be analyzed in real time by the quadrupole mass spectrometer. It's like

Then, from the mass spectrum obtained by analyzing the gas generated from the polyimide film when the atmospheric temperature reached 470 ° C. with the quadrupole mass spectrometer, the detection intensity of the peak at m / z = 20 (20 peaks intensity) was read. The baseline of the mass spectrum was adjusted so that the peak intensity at a temperature of 60° C. was 2000±100. Example 2, which did not use a plasticizer, had a 20 peak intensity of 37,726. On the other hand, the 20 peak intensities of Examples 7, 8 and 9 using a plasticizer were 16760, 9636 and 17533, respectively. From this result, it was shown that the amount of hydrogen fluoride generated can be suppressed by using a plasticizer.

<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 PMDA: pyromellitic dianhydride BPDA: 3,3′,4,4′-biphenyltetracarboxylic dianhydride SFDA: spiro[11H-diflo[3,4-b: 3′,4′-i]xanthene-11,9′-[9H]fluorene]-1,3,7,9-tetrone 6 FDA: 4,4′-(hexafluoroisopropylidene)diphthalic anhydride BPAF: 9 ,9-bis (3,4-dicarboxyphenyl) fluorene dianhydride TFMB: 2,2'-bis (trifluoromethyl) benzidine DMI: 1,2-dimethylimidazole TMP: trimethyl phosphate PX-200: Daihachi Chemical Resorcinol poly(di-2,6-xylyl) phosphate manufactured by Kogyosha

[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 40.0 g of NMP as an organic solvent for polymerization. Then, while stirring the flask contents, 5.137 g of TFMB was added to the flask and dissolved. After adding 0.379 g of SFDA and 4.484 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, Example 3, Example 6, and Comparative Examples 1 to 8]
Example 2, Example 3, Example 6, and Comparative Examples 1 to 8 were prepared in the same manner as in Example 1 except that the acid dianhydride used and the charging ratio thereof were as shown in Table 1. A laminate was obtained, respectively. In addition, in all of Examples 2, 3, 6, and Comparative Examples 1 to 8, the total substance amount of the acid dianhydride when preparing the polyamic acid composition was the same as in Example 1. there were.

[Examples 4, 5 and 7 to 9]
The acid dianhydride used and its charging ratio were as shown in Table 1, and after stirring the contents of the flask for 24 hours, DMI or a plasticizer was added to the contents of the flask in the amount shown in Table 1, Laminates of Examples 4, 5 and 7 to 9 were obtained in the same manner as in Example 1, except that the polyamic acid composition was obtained. Incidentally, in all of Examples 4, 5 and 7 to 9, the total substance amount of the acid dianhydride when preparing the polyamic acid composition was the same as in Example 1.

For Examples 1-9 and Comparative Examples 1-8, Table 1 shows the acid dianhydrides used and their charging ratio, the amount of DMI added, the amount of plasticizer added, and the measurement results of physical properties. In Table 1, "-" means that the component was not used. Moreover, in Table 1, "CO" means a cutoff wavelength. 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 value in the "DMI" column is the amount of DMI (unit: parts by weight) per 100 parts by weight of polyamic acid. In Table 1, the numerical values in the "Plasticizer" column are the amount (unit: parts by weight) of the plasticizer relative to 100 parts by weight of polyamic acid. Further, in all of Examples 1 to 9 and Comparative Examples 1 to 8, 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 acid in the polyamic acid compositions prepared in Examples 1-9 contained BPDA residues, SFDA residues and TFMB residues. In the polyamic acids in the polyamic acid compositions prepared in Examples 1 to 9, the content of BPDA residues was more than 50 mol% with respect to the total amount of tetracarboxylic dianhydride residues. In the polyamic acids in the polyamic acid compositions prepared in Examples 1 to 9, the content of SFDA residues was 1 mol% or more and less than 50 mol% with respect to the total amount of tetracarboxylic dianhydride residues. Ta.

As shown in Table 1, in Examples 1 to 9, the 400 nm transmittance was 45% or more. Therefore, the polyimides obtained in Examples 1 to 9 had high transmittance for light with a wavelength of 400 nm. In Examples 1 to 9, the internal stress was 40 MPa or less. Therefore, the polyimides obtained in Examples 1 to 9 were able to reduce the internal stress.

In the polyamic acids in the polyamic acid compositions prepared in Comparative Examples 1, 2 and 4, the content of SFDA residues was less than 1 mol% with respect to the total amount of tetracarboxylic dianhydride residues. In the polyamic acids in the polyamic acid compositions prepared in Comparative Examples 3 and 5 to 8, the content of SFDA residues was 50 mol% or more with respect to the total amount of tetracarboxylic dianhydride residues. In the polyamic acids in the polyamic acid compositions prepared in Comparative Examples 3 to 8, the content of BPDA residues was 50 mol% or less with respect to the total amount of tetracarboxylic dianhydride residues.

As shown in Table 1, in Comparative Example 1, the 400 nm transmittance was less than 45%. Therefore, the polyimide obtained in Comparative Example 1 did not have a high transmittance for light with a wavelength of 400 nm. In Comparative Examples 2-8, the internal stress exceeded 40 MPa. Therefore, the polyimides obtained in Comparative Examples 2 to 8 could not reduce the internal stress.

From the above results, it was shown that the polyimide obtained from the polyamic acid composition according to the present invention has high transmittance for light with a wavelength of 400 nm while reducing internal stress.

Claims

A polyamic acid having a tetracarboxylic dianhydride residue and a diamine residue,
The tetracarboxylic dianhydride residues include 3,3′,4,4′-biphenyltetracarboxylic dianhydride residues and spiro[11H-difuro[3,4-b:3′,4′- i]xanthene-11,9′-[9H]fluorene]-1,3,7,9-tetrone residues,
The diamine residue comprises a 2,2′-bis(trifluoromethyl)benzidine residue,
The content of the 3,3′,4,4′-biphenyltetracarboxylic dianhydride residue is more than 50 mol% with respect to the total amount of the tetracarboxylic dianhydride residue,
The spiro[11H-diflo[3,4-b:3′,4′-i]xanthene-11,9′-[9H]fluorene]-1,3,7,9-tetrone residue content is A polyamic acid that is 1 mol % or more and less than 50 mol % relative to the total amount of the tetracarboxylic dianhydride residue.
The polyamic acid according to claim 1, wherein the content of the 2,2'-bis(trifluoromethyl)benzidine residue is 50 mol% or more and 100 mol% or less with respect to the total amount of the diamine residue.
A polyamic acid composition containing the polyamic acid according to claim 1 and an organic solvent.
The polyamic acid composition according to claim 3, which further contains a plasticizer.
The polyamic acid composition according to claim 4, wherein the amount of said plasticizer is 20 parts by weight or less with respect to 100 parts by weight of said polyamic acid.
The polyamic acid composition according to claim 4, wherein the plasticizer is one or more selected from the group consisting of phosphorus-containing compounds, polyalkylene glycols and aliphatic dibasic acid esters.
The polyamic acid composition according to claim 3, further comprising an imidization accelerator.
The polyamic acid composition according to claim 7, wherein the amount of the imidization accelerator is 0.1 parts by weight or more and 20 parts by weight or less with respect to 100 parts by weight of the polyamic acid.
The polyamic acid composition according to claim 7, wherein the imidization accelerator has a 1,3-diazole ring.
A polyimide that is an imidized product of the polyamic acid according to claim 1.
A polyimide film containing the polyimide according to claim 10.
The polyimide film according to claim 11, which has a transmittance of 45% or more for light with a wavelength of 400 nm.
The polyimide film according to claim 11, which has a haze of 1.0% or less.
A laminate comprising a support and the polyimide film according to claim 11.
The support is a glass substrate,
15. The laminate according to claim 14, wherein the internal stress between said polyimide film and said glass substrate is 40 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 3 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 11 and an electronic element arranged on the polyimide film.