WO2023276888A1

WO2023276888A1 - Polyamic acid, polyamic acid composition, polyimide, polyimide film, laminate, production method for laminate, and electronic device

Info

Publication number: WO2023276888A1
Application number: PCT/JP2022/025343
Authority: WO
Inventors: 博文中山; 友貴白井
Original assignee: 株式会社カネカ
Priority date: 2021-07-01
Filing date: 2022-06-24
Publication date: 2023-01-05
Also published as: CN117580893A; TW202319445A; KR20240027771A; JPWO2023276888A1

Abstract

According to the present invention, a polyamic acid includes a structural unit represented by general formula (1) and has a fluorine atom content of no more than 5 weight%. In general formula (1), R¹ and R² each independently represent a hydrogen atom, a monovalent aliphatic group, or a monovalent aromatic group, and X¹ represents a bivalent organic group. According to the present invention, a polyamic acid composition contains an organic solvent and a polyamic acid that includes a structural unit represented by general formula (1) and has a fluorine atom content of no more than 5 weight%. According to the present invention, a polyimide is an imide compound of a polyamic acid that includes a structural unit represented by general formula (1) and has a fluorine atom content of no more than 5 weight%.

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), a technique for increasing transparency using a monomer having a fluorene skeleton (Patent Document 3), and a technique of increasing transparency by using a monomer having a fluorine atom (Patent Document 4).

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 Taiwan Patent Application Publication No. 201713726 WO2019/195148

The polyimide described in Patent Document 3 has high transparency and high heat resistance due to the introduction of a fluorene skeleton. However, the polyimide described in Patent Document 3 has a high coefficient of thermal expansion (CTE). internal stress tends to increase. For this reason, when a laminate is formed using the polyimide described in Patent Document 3, the laminate is likely to warp, which may make it difficult to apply to electronic devices.

In addition, the technique described in Patent Document 4 also reduces the internal stress between the support and the polyimide film (hereinafter sometimes simply referred to as "internal stress"), while the polyimide having excellent transparency and heat resistance is difficult to obtain.

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 excellent transparency and heat resistance while reducing internal stress, and a polyamic acid as a precursor thereof. 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 containing a structural unit represented by the following general formula (1) and having a fluorine atom content of 5% by weight or less.

In general formula (1), R ¹ and R ² each independently represent a hydrogen atom, a monovalent aliphatic group or a monovalent aromatic group, and X ¹ represents a divalent organic group.

[2] The polyamic acid according to [1], wherein both R ¹ and R ² in the general formula (1) represent a hydrogen atom.

[3] In the general formula (1), X ¹ is a divalent organic group represented by the following chemical formula (2-1) and a divalent organic group represented by the following general formula (2-2) Polyamic acid according to the above [1] or [2], which is one or more selected from the group consisting of.

In the general formula (2-2), Y ¹ is a divalent organic group represented by the following chemical formula (3-1), a divalent organic group represented by the following chemical formula (3-2), a divalent organic group represented by (3-3), a divalent organic group represented by the following chemical formula (3-4), a divalent organic group represented by the following chemical formula (3-5), and It is one or more selected from the group consisting of divalent organic groups represented by the following chemical formula (3-6).

[4] The polyamic acid according to any one of [1] to [3], further comprising a structural unit represented by the following general formula (4).

In the general formula (4), R ³ and R ⁴ each independently represent a hydrogen atom, a monovalent aliphatic group or a monovalent aromatic group, X ² represents a divalent organic group, Y ² is a tetravalent organic group represented by the following chemical formula (5-1), a tetravalent organic group represented by the following chemical formula (5-2), or a tetravalent organic group represented by the following chemical formula (5-3). It is one or more selected from the group consisting of a valent organic group and a tetravalent organic group represented by the following chemical formula (5-4).

[5] The polyamic acid according to any one of [1] to [4], which has a fluorine atom content of less than 1% by weight.

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

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

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

[9] A polyimide which is an imidized polyamic acid according to any one of [1] to [5].

[10] The polyimide according to [9] above, which has a 1% weight loss temperature of 500°C or higher.

[11] The polyimide according to the above [9] or [10], which has a glass transition temperature of 420°C or higher.

[12] A polyimide film containing the polyimide according to any one of [9] to [11].

[13] The polyimide film according to [12] above, which has a yellowness index of 25 or less.

[14] A laminate comprising a support and the polyimide film described in [12] or [13] above.

[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 [6] to [8] 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 described in [12] or [13] 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 heat resistance 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 heat resistance 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 (6) (hereinafter sometimes referred to as "structural unit (6)"). In this specification, not only polyamic acid but also polyamic acid esters (polyamic acid alkyl esters, polyamic acid aryl esters, etc.) are referred to as "polyamic acid".

In general formula (6), R ⁵ and R ⁶ each independently represent a hydrogen atom, a monovalent aliphatic group or a monovalent aromatic group, A ¹ is, for example, a tetracarboxylic dianhydride residue group (tetravalent organic group derived from tetracarboxylic dianhydride), and ^A2 represents, for example, a diamine residue (divalent organic group derived from diamine).

The content of the structural unit (6) 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. The method for measuring the 1% weight loss temperature is the same method as in Examples described later or a method based thereon.

"m/z" is a measurement that can be read from the horizontal axis of the mass spectrum, which is the 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>
The polyamic acid according to the present embodiment includes a structural unit represented by the following general formula (1) (hereinafter sometimes referred to as "structural unit (1)"), and has a fluorine atom content of 5% by weight or less. is.

In general formula (1), R ¹ and R ² each independently represent a hydrogen atom, a monovalent aliphatic group or a monovalent aromatic group, and X ¹ represents a divalent organic group. In order to facilitate imidization, R ¹ and R ² each independently preferably represent a hydrogen atom, a methyl group or an ethyl group, and more preferably both R ¹ and R ² represent a hydrogen atom. . Hereinafter, unless otherwise specified, a structural unit in which R ¹ and R ² in general formula (1) each represent a hydrogen atom is referred to as structural unit (1).

Structural unit (1) is spiro[11H-diflo[3,4-b:3′,4′-i]xanthene-11,9′-[9H]fluorene]-1,3,7,9-tetrone ( hereinafter, it may be referred to as “SFDA”). That is, structural unit ( ¹ ) has an SFDA residue as A1 in general formula (6) described above.

Since the polyamic acid according to the present embodiment contains the structural unit (1) and has a fluorine atom content of 5% by weight or less, the polyimide produced using the polyamic acid according to the present embodiment has internal stress. Excellent transparency and heat resistance while reducing The reason is presumed as follows.

Since SFDA has a rigid structure derived from the xanthene skeleton, it is suitable as a raw material (monomer) for polyimide with a high glass transition temperature (excellent in heat resistance), and is also a raw material (monomer) for polyimide with a low CTE. ) is suitable as In addition, SFDA is suitable as a raw material (monomer) for highly transparent polyimide due to its fluorene skeleton. In addition, the polyamic acid containing the structural unit (1) has a xanthene skeleton in the main chain and a fluorene skeleton in the side chain. Therefore, the polyimide film produced using the polyamic acid containing the structural unit (1) Shows low retardation.

On the other hand, according to the studies of the present inventors, when SFDA and a fluorine-containing monomer are used together as monomers for synthesizing polyamic acid, the orientation between polymer chains of polyamic acid tends to decrease and the CTE tends to increase. It turned out that there is In contrast, since the polyamic acid according to the present embodiment has a fluorine atom content of 5% by weight or less, the decrease in orientation between polymer chains is suppressed.

Therefore, the polyamic acid according to the present embodiment has an SFDA residue that contributes to a low CTE and has a fluorine atom content of 5% by weight or less, so that a polyimide film is formed on the support to form a laminate It is possible to reduce the internal stress generated when obtaining Therefore, the polyimide produced using the polyamic acid according to the present embodiment can have reduced internal stress.

In addition, since the polyamic acid according to the present embodiment has an SFDA residue that contributes to transparency and heat resistance, the polyimide produced using the polyamic acid according to the present embodiment has excellent transparency and heat resistance.

In order to further reduce the internal stress, the fluorine atom content of the polyamic acid (hereinafter sometimes referred to as "polyamic acid (1)") according to the present embodiment is preferably less than 1% by weight. , more preferably less than 0.5% by weight, more preferably less than 0.1% by weight, and substantially 0% by weight (polyamic acid (1) contains residues derived from fluorine-containing monomers not included) is particularly preferred. The fluorine atom content (unit: % by weight) is the ratio of the fluorine atom weight to the total weight of the polyamic acid. Polyamic acid is a polyadduct of diamine and tetracarboxylic dianhydride, and the total weight of diamine and tetracarboxylic dianhydride before polymerization is equal to the weight of polyamic acid after polymerization. That is, the fluorine atom content of the polyamic acid is the value obtained by dividing the "total weight of fluorine atoms contained in the monomers for forming the polyamic acid" by the "total weight of the monomers for forming the polyamic acid". obtained by multiplying Therefore, the fluorine atom content of polyamic acid can be calculated based on the following formula.

In the above formula, ni is the amount (unit: mol) of diamine component _i , and nj is the amount (unit: mol) of tetracarboxylic dianhydride _j . M _i is the molecular weight of diamine component i and M _j is the molecular weight of tetracarboxylic dianhydride j. F _i is the number of fluorine atoms contained in one molecule of diamine component i, and F _j is the number of fluorine atoms contained in one molecule of tetracarboxylic dianhydride j. 19.00 is the atomic weight of fluorine. For example, as diamines, 0.05 mol of 2,2′-bis(trifluoromethyl)benzidine (molecular weight: 320.2, number of fluorine atoms: 6) and 0.95 mol of 4-aminophenyl-4-aminobenzoate ( molecular weight: 228.3, number of fluorine atoms: 0), and 0.3 mol of SFDA (molecular weight: 472.4, number of fluorine atoms: 0) and 0.7 mol of 3,3 as tetracarboxylic dianhydride The fluorine atom content of polyamic acid polymerized using ',4,4'-biphenyltetracarboxylic dianhydride (molecular weight 294.2, number of fluorine atoms: 0) is 100 × 19.00 × (0.05 x 6)/(0.05 x 320.2 + 0.95 x 228.3 + 0.3 x 472.4 + 0.7 x 294.2) = 0.98 wt%.

Structural unit (1) has an SFDA residue and a diamine residue (a divalent organic group represented by X ¹ in general formula (1)). In order to further reduce the internal stress, diamines containing no fluorine atoms are preferred as the diamines that give X ¹ in the general formula (1).

Examples of diamines containing no fluorine atom include p-phenylenediamine (hereinafter sometimes referred to as "PDA") and 4-aminophenyl-4-aminobenzoate (hereinafter referred to as "4-BAAB"). ), 4,4′-diaminobenzanilide (hereinafter sometimes referred to as “DABA”), 1,4-bis(4-aminobenzoyloxy)benzene (hereinafter referred to as “BABB”) ), N,N'-(1,4-phenylene)bis(4-aminobenzamide) (hereinafter sometimes referred to as "PBAB"), bis(4-aminophenyl) terephthalate (hereinafter "BATP" ), N,N'-di(4-aminophenyl)terephthalamide (hereinafter sometimes referred to as "DATA"), 1,3-bis(3-aminopropyl)tetramethyldi Siloxane (hereinafter sometimes referred to as "PAM-E"), 1,4-diaminocyclohexane, m-phenylenediamine, 9,9-bis(4-aminophenyl)fluorene, 4,4'-oxydianiline , 3,4′-oxydianiline, 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) and derivatives thereof, and these alone Alternatively, two or more types may be used.

In order to obtain a polyimide that is more excellent in transparency and heat resistance while further reducing internal stress, X ¹ in general formula (1) is a PDA residue, a 4-BAAB residue, a DABA residue, a BABB residue. , PBAB residues, BATP residues and DATA residues.

A PDA residue is a divalent organic group represented by the following chemical formula (2-1). 4-BAAB residue is a divalent organic group represented by the following general formula (2-2), and represented by the following chemical formula (3-1) as Y ¹ in the general formula (2-2) It has a divalent organic group that DABA residue is a divalent organic group represented by the following general formula (2-2), and 2 represented by the following chemical formula (3-2) as Y ¹ in general formula (2-2) have a valent organic group. BABB residue is a divalent organic group represented by the following general formula (2-2), and 2 represented by the following chemical formula (3-3) as Y ¹ in general formula (2-2) have a valent organic group. The PBAB residue is a divalent organic group represented by the following general formula (2-2), and 2 represented by the following chemical formula (3-4) as Y ¹ in the general formula (2-2) have a valent organic group. BATP residue is a divalent organic group represented by the following general formula (2-2), and 2 represented by the following chemical formula (3-5) as Y ¹ in the general formula (2-2) have a valent organic group. DATA residue is a divalent organic group represented by the following general formula (2-2), and 2 represented by the following chemical formula (3-6) as Y ¹ in general formula (2-2) have a valent organic group.

In order to obtain a polyimide with even better heat resistance, X ¹ in general formula (1) is preferably a PDA residue. In order to obtain a polyimide with further excellent transparency, X ¹ in the general formula (1) is preferably one or more selected from the group consisting of 4-BAAB residues, BABB residues and BATP residues, 4-BAAB residues are more preferred. In order to obtain a polyimide that can further reduce internal stress, X ¹ in general formula (1) is preferably one or more selected from the group consisting of DABA residues, PBAB residues and DATA residues. A residue is more preferred.

In order to obtain a polyimide that is more excellent in transparency and heat resistance while further reducing internal stress, PDA residues, 4-BAAB residues, DABA residues, The content of one or more residues selected from the group consisting of BABB residues, PBAB residues, BATP residues and DATA residues (if two or more are included, the total content) is 30 mol% or more. is preferably 40 mol% or more, more preferably 50 mol% or more, even more preferably 60 mol% or more, 70 mol% or more, 80 mol% or more, or 90 mol % or more, or 100 mol %.

In addition, in order to impart appropriate adhesion to inorganic materials (eg, glass substrates, etc.), the polyamic acid (1) preferably contains a PAM-E residue. More preferably, the content of PAM-E residues relative to diamine residues is 0.01 mol % or more and 1 mol % or less.

When synthesizing polyamic acid (1), an acid dianhydride other than SFDA may be used as a monomer. In order to further reduce the internal stress, acid dianhydrides other than SFDA are preferably acid dianhydrides containing no fluorine atoms.

Acid dianhydrides containing no fluorine atom include, for example, pyromellitic dianhydride (hereinafter sometimes referred to as "PMDA") and 3,3',4,4'-biphenyltetracarboxylic dianhydride. (hereinafter sometimes referred to as "BPDA"), 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride (hereinafter sometimes referred to as "BPAF"), 4,4 '-Oxydiphthalic anhydride (hereinafter sometimes referred to as "ODPA"), 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride 2,2′,3,3′-biphenyltetracarboxylic dianhydride, 3,3′,4,4′-benzophenonetetracarboxylic dianhydride, dicyclohexyl-3,3′,4,4′- Tetracarboxylic dianhydride, 1,2,4,5-cyclohexanetetracarboxylic dianhydride, 1,2,3,4-cyclobutanetetracarboxylic dianhydride and derivatives thereof, which may be used alone or Two or more types may be used.

In order to obtain a polyimide that is more excellent in transparency and heat resistance while further reducing internal stress, polyamic acid (1) contains, as acid dianhydride residues other than SFDA residues, PMDA residues, BPDA residues, It preferably contains one or more selected from the group consisting of BPAF residues and ODPA residues. In other words, in order to obtain a polyimide that is more excellent in transparency and heat resistance while further reducing internal stress, the polyamic acid (1) is a structural unit represented by the following general formula (4) (hereinafter, “structural unit ( 4)”) is preferably further included.

In general formula (4), R ³ and R ⁴ each independently represent a hydrogen atom, a monovalent aliphatic group or a monovalent aromatic group, X ² represents a divalent organic group, Y ² is a tetravalent organic group represented by the following chemical formula (5-1), a tetravalent organic group represented by the following chemical formula (5-2), a tetravalent organic group represented by the following chemical formula (5-3) and a tetravalent organic group represented by the following chemical formula (5-4).

A PMDA residue is a tetravalent organic group represented by the chemical formula (5-1). A BPDA residue is a tetravalent organic group represented by the chemical formula (5-2). A BPAF residue is a tetravalent organic group represented by the chemical formula (5-3). The ODPA residue is a tetravalent organic group represented by chemical formula (5-4).

In general formula (4), preferred groups for R ³ , R ⁴ and X ² are, for example, the same as the preferred groups for R ¹ , R ² and X ¹ in general formula (1). .

In order to obtain a polyimide that is more excellent in transparency and heat resistance while further reducing internal stress, the content of SFDA residues with respect to all acid dianhydride residues constituting polyamic acid (1) is 5 mol% or more. is preferably 10 mol% or more, more preferably 15 mol% or more, even more preferably 20 mol% or more, 30 mol% or more, 40 mol% or more, or It may be 50 mol % or more, or 100 mol %.

In order to obtain a polyimide that is more excellent in transparency and heat resistance while further reducing internal stress, PMDA residue, BPDA residue, BPAF residue for all acid dianhydride residues constituting polyamic acid (1) and the content of one or more residues selected from the group consisting of ODPA residues (if two or more are included, the total content) is preferably 5 mol% or more, and 10 mol% or more. is more preferably 20 mol% or more, even more preferably 30 mol% or more, 40 mol% or more, 50 mol% or more, 60 mol% or more, 70 mol% or more or 80 mol% or more. In addition, in order to obtain a polyimide that is more excellent in transparency and heat resistance while further reducing internal stress, PMDA residue, BPDA residue, BPAF with respect to all acid dianhydride residues constituting polyamic acid (1) The content of one or more residues selected from the group consisting of residues and ODPA residues (if two or more are included, the total content) is preferably 95 mol% or less, and 90 mol% or less. It is more preferable to have

In order to obtain a polyimide having further excellent transparency and heat resistance while further reducing internal stress, the polyamic acid (1) may contain a BPDA residue as an acid dianhydride residue other than the SFDA residue. preferable. When the polyamic acid (1) contains a BPDA residue, in order to obtain a polyimide having further excellent transparency and heat resistance while further reducing the internal stress, the substance amount ratio of the SFDA residue to the BPDA residue (SFDA residue group/BPDA residue) is preferably 10/90 or more and 50/50 or less, more preferably 10/90 or more and 40/60 or less, and further preferably 10/90 or more and 35/65 or less. It is more preferably 10/90 or more and 30/70 or less.

The polyamic acid (1) may contain only the structural unit (1) as a structural unit, or may contain only the structural unit (1) and the structural unit (4), and the structural unit (1) and the structural A structural unit (another structural unit) other than the unit (4) may be included. In order to obtain a polyimide having excellent transparency and heat resistance while further reducing internal stress, the content of the structural unit (1) with respect to the total structural units constituting the polyamic acid (1) is 5 mol% or more. is preferably 10 mol% or more, more preferably 15 mol% or more, even more preferably 20 mol% or more, 30 mol% or more, 40 mol% or more, or 50 mol% % or more, or 100 mol %.

When the polyamic acid (1) contains the structural unit (4), in order to obtain a polyimide having excellent transparency and heat resistance while further reducing the internal stress, for all the structural units constituting the polyamic acid (1), The total content of structural unit (1) and structural unit (4) is preferably 60 mol% or more and 100 mol% or less, more preferably 70 mol% or more and 100 mol% or less, and 80 mol% or more. It is more preferably 100 mol % or less, even more preferably 90 mol % or more and 100 mol % or less, and may be 100 mol %.

In order to obtain a polyimide having further excellent transparency and heat resistance while further reducing the internal stress, the polyamic acid (1) preferably satisfies the following condition 1, more preferably satisfies the following condition 2. It is more preferable to satisfy condition 3.
Condition 1: Polyamic acid (1) contains a BPDA residue as an acid dianhydride residue other than an SFDA residue, and does not contain a residue derived from a fluorine-containing monomer.
Condition 2: satisfying condition 1 above, and polyamic acid (1) is selected from the group consisting of a PDA residue, a 4-BAAB residue, a DABA residue, a BABB residue, a PBAB residue, a BATP residue and a DATA residue It contains one or more selected diamine residues.
Condition 3: Satisfies Condition 2 above, and the substance amount ratio of SFDA residues to BPDA residues (SFDA residues/BPDA residues) is 10/90 or more and 35/65 or less.

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), and include 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 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 added to the polyamic acid composition according to the present embodiment are not particularly limited, but examples include 1H-imidazole, 2-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 1,2-dimethyl 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. Regarding the improvement of transparency, it is known that a polymerization solvent such as NMP forms a complex by hydrogen bonding with the carboxy group of polyamic acid (1). It may remain in the film and cause coloration when oxidized or decomposed. When imidazoles are added, the imidazoles coordinate to the carboxy groups of polyamic acid (1) and promote imidization, so that NMP and the like are less likely to remain in the polyimide film, and at the same time polyamic acid ( Since the decomposition of 1) is also suppressed, it is thought that the transparency is improved. 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.

In addition, adding imidazoles to polyamic acid promotes imidization, and in the initial stage of thermal imidization, in-plane orientation is induced starting from imidized rigid units. However, when an imidazole is added to a polyamic acid composed of BPDA and PDA, which is highly oriented without using imidazoles, the imidazole acts as a plasticizer and conversely causes the orientation of the molecular chains. sometimes disturb. On the other hand, since polyamic acid (1) has an SFDA residue, the internal stress can be reduced even if imidazoles are added.

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 plasticizer is preferably a compound that dissolves in the organic solvent used for polymerization of the polyamic acid (1) and that exists as a liquid during imidization. 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.

The amount of the plasticizer is 0.001 part by weight or more with respect to 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. It is preferably 20 parts by weight or less, more preferably 0.01 parts by weight or more and 15 parts by weight or less, still more preferably 0.05 parts by weight or more and 10 parts by weight or less, and 0.05 parts by weight or more. Even more preferably, it is 5 parts by weight or less.

The plasticizer not only improves molecular motion when polyamic acid (1) undergoes dehydration ring closure to polyimide, but can also add functions such as adjustment of the glass transition temperature and flame retardancy. As the plasticizer, for example, one or more of known plasticizers can be appropriately selected and used.

In order to impart sufficient molecular mobility to the polyamic acid (1), the plasticizer is preferably one or more selected from the group consisting of phosphorus-containing compounds, polyalkylene glycols and aliphatic dibasic acid esters.

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-t-butylphenyl) phosphite, tri isodecylphosphite, 3,9-bis(2,6-di-t-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., and “FP-600” manufactured by ADEKA Corporation.

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

Polyalkylene glycol includes polypropylene glycol, polyethylene glycol, and the like.

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 phthalimide compounds such as phthalimide, N-phenylphthalimide, N-glycidylphthalimide, N-hydroxyphthalimide, and cyclohexylthiophthalimide; Examples include 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.

Examples of the antioxidant include phenolic compounds, and phenolic compounds that dissolve in the organic solvent used for polymerization of the polyamic acid (1) and that exist as a liquid during imidization are preferred. From the viewpoint of suppressing the coloring of the polyimide film, it is desirable that it remains during imidization. It is more preferable that it is above. Phenolic compounds that do not have a decomposition temperature below the boiling point are preferred.

Examples of the phenolic compound include hindered type, semi-hindered type, less hindered type, etc. Specific examples include dibutylhydroxytoluene, 1,3,5-tris(3,5-di-t-butyl -4-hydroxyphenylmethyl)-2,4,6-trimethylbenzene, 2-t-butyl-4-methyl-6-(2-hydroxy-3-t-butyl-5-methylbenzyl)phenyl acrylate, and the like. mentioned.

Phenolic compounds mainly capture peroxy radicals, convert them to hydroperoxides, and function as primary antioxidants that suppress autoxidation of polymers, so they have the function of suppressing coloration due to oxidation of polymers. Furthermore, by combining a phenolic compound with a phosphite or the like that functions as a secondary antioxidant that converts hydroperoxide into a stable alcohol compound, coloration due to oxidation of polyimide can be further suppressed. For example, the coloring of the polyimide can be effectively suppressed by using the phosphite ester in the range of equivalent weight or more and 10 equivalents or less with respect to the phenolic compound.

In order to obtain a sufficient antioxidant effect, the amount of the phenolic compound is preferably 0.001 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 from 0.02 part by weight to 5 parts by weight, and even more preferably from 0.02 part by weight to 1 part by weight. The phenolic compound may be dissolved in an organic solvent before polymerization of polyamic acid (1), or may be added to the polyamic acid solution after polymerization.

In order to improve the heat resistance while maintaining the transparency of the polyimide film, nanosilica particles may be used as the additive, and the polyamic acid (1) and the nanosilica particles may be combined. From the viewpoint of maintaining the transparency of the polyimide film, the average primary particle size of the nanosilica particles is preferably 200 nm or less, more preferably 100 nm or less, even more preferably 50 nm or less, and 30 nm or less. may On the other hand, from the viewpoint of ensuring dispersibility in the polyamic acid (1), the average primary particle size of the nanosilica particles is preferably 5 nm or more, more preferably 10 nm or more. As a method for combining polyamic acid (1) and nanosilica particles, a known method can be used, for example, a method using an organosilica sol in which nanosilica particles are dispersed in an organic solvent. As a method of combining polyamic acid (1) and nanosilica particles using organosilica sol, after synthesizing polyamic acid (1), a method of mixing synthesized polyamic acid (1) and organosilica sol is used. However, in order to disperse the nanosilica particles in the polyamic acid (1) to a higher degree, it is preferable to synthesize the polyamic acid (1) in an organosilica sol.

In addition, the nanosilica particles can be surface-treated with a surface treatment agent in order to enhance the interaction with the polyamic acid (1). As the surface treatment agent, a known agent such as a silane coupling agent can be used. As a silane coupling agent, an alkoxysilane compound having an amino group, a glycidyl group, or the like as a functional group is widely known, and can be appropriately selected. In order to further enhance the interaction with the polyamic acid (1), the silane coupling agent is preferably an amino group-containing alkoxysilane. Examples of amino group-containing alkoxysilanes include 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropylmethyldimethoxysilane, 3-aminopropylmethyldiethoxysilane, 3-(2-aminoethyl ) aminopropyltrimethoxysilane, 3-phenylaminopropyltrimethoxysilane, 2-aminophenyltrimethoxysilane and 3-aminophenyltrimethoxysilane. Silanes are preferably used. As a surface treatment method of nanosilica particles, a method of stirring a mixture obtained by adding a silane coupling agent to a dispersion (organosilica sol) at an ambient temperature of 20° C. or higher and 80° C. or lower may be mentioned. The stirring time at this time is, for example, 1 hour or more and 10 hours or less. At this time, a catalyst or the like that promotes the reaction may be added.

A nanosilica-polyamic acid composite obtained by combining polyamic acid (1) and nanosilica particles contains 1 part by weight or more and 30 parts by weight or less of nanosilica particles with respect to 100 parts by weight of polyamic acid (1). and more preferably in the range of 1 part by weight or more and 20 parts by weight or less. When the content of the nanosilica particles is 1 part by weight or more, the heat resistance of the nanosilica particle-containing polyimide can be improved and the internal stress can be sufficiently reduced. Adverse effects on the mechanical properties of polyimide containing nanosilica particles can be suppressed.

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. Examples of components other than polyimide in the polyimide film include the additives described above (more specifically, nanosilica 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, SFDA residues, BPDA residues, etc.). 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.

Further, 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, 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. In order to suppress the generation of corrosive gas, the fluorine atom content of polyamic acid (1) is preferably less than 1% by weight, more preferably less than 0.5% by weight, and more preferably less than 0.1% by weight. It is more preferably less than % by weight, and particularly preferably substantially 0 % by weight (polyamic acid (1) does not contain residues derived from fluorine-containing monomers).

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, the internal stress between the polyimide film and the glass substrate is preferably 40 MPa or less, more preferably 35 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.

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 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 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, 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 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, a method for producing an electronic device includes a step of applying a polyamic acid composition onto a support, imidizing it by heating, and forming an electronic element or the like on a polyimide film formed on the support. 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.

[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".

[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 Examples and Comparative Examples, which will be described later, and used as a sample for Tg measurement. Using a thermal analysis device ("TMA/SS7100" manufactured by Hitachi High-Tech Science), a load of 29.8 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). When Tg was 420°C or higher, it was evaluated as "excellent in heat resistance". On the other hand, when Tg was less than 420°C, it was evaluated as "not excellent in heat resistance".

[1% weight loss temperature (TD1)]
Each polyimide film (specifically, a polyimide film sampled from each laminate so that the weight is 10 mg) obtained in Examples and Comparative Examples to be described later is used as a sample for measurement, and a simultaneous differential thermogravimetric measurement device (Hitachi Hi-tech Science Co., Ltd. "TG / DTA7200"), the temperature is raised from 25 ° C. to 650 ° C. under the conditions of 20 ° C./min under a nitrogen atmosphere, and the weight of the sample at a measurement temperature of 150 ° C. is used as a standard. The measurement temperature when the weight was reduced by 1% was taken as the 1% weight loss temperature (TD1).

[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, each polyimide film obtained in a comparative example described later (in detail, , the polyimide film sampled from each laminate so that the mass was 140 mg) was heated and the gas generated from the polyimide film when the atmospheric temperature reached 470 ° C. was analyzed with the quadrupole 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.

<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 SFDA: spiro[11H-diflo[3,4-b:3′,4′-i]xanthene-11,9′-[9H]fluorene]-1,3,7, 9-Tetrone BPDA: 3,3′,4,4′-biphenyltetracarboxylic dianhydride BPAF: 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride 6FDA: 4,4′-( Hexafluoroisopropylidene) diphthalic anhydride PDA: p-phenylenediamine 4-BAAB: 4-aminophenyl-4-aminobenzoate DABA: 4,4'-diaminobenzanilide DATA: N,N'-di(4-amino Phenyl)terephthalamide PAM-E: 1,3-bis(3-aminopropyl)tetramethyldisiloxane TFMB: 2,2'-bis(trifluoromethyl)benzidine DMI: 1,2-dimethylimidazole

[Example 1]
A 300 mL glass separable flask equipped with a stirrer with a stainless steel stir bar and a nitrogen inlet was charged with 88.0 g of NMP as an organic solvent for polymerization. 2.240 g of PDA was then added to the flask and dissolved while stirring the flask contents. After adding 9.760 g of SFDA 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 with a stainless steel stir bar and a nitrogen inlet was charged with 88.0 g of NMP as an organic solvent for polymerization. 2.240 g of PDA was then added to the flask and dissolved while stirring the flask contents. After adding 9.760 g of SFDA 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 17 and Comparative Examples 1 to 8]
Examples 3, 5, and 6 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 Tables 1 and 2. , 8, 10, 12, 13, 15 and 17 and the laminates of Comparative Examples 1, 2, 3 and 5, respectively. In addition, in the same manner as in Example 2, except that the acid dianhydride used and its charging ratio, and the diamine used and its charging ratio were as shown in Tables 1 and 2, Examples 4 and 7 , 9, 11, 14 and 16 and the laminates of Comparative Examples 4, 6, 7 and 8, respectively. In addition, in all of Examples 3 to 17 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 Examples 1 and 2. Further, in all of Examples 3-17 and Comparative Examples 1-8, the total substance amount of diamines in preparing polyamic acid compositions was the same as in Examples 1 and 2.

In addition, in Tables 1 and 2, "-" means that the component was not used. In Tables 1 and 2, 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 Tables 1 and 2, the numerical values in the "diamine" column are the content of each diamine relative to the total amount of diamines used (unit: mol%). In Tables 1 and 2, the numerical value in the "DMI" column is the amount of DMI (unit: parts by weight) per 100 parts by weight of polyamic acid. Further, in all of Examples 1 to 17 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).

<Measurement results of physical properties>
Table 3 shows the measurement results of the physical properties of Examples 1 to 17 and Comparative Examples 1 to 8. In Table 3, "-" means not measured. Further, in Table 3, the "fluorine atom content" is a calculated value calculated by the above formula.

The polyamic acid in the polyamic acid compositions prepared in Examples 1 to 17 contained the structural unit (1) and had a fluorine atom content of 5% by weight or less. As shown in Table 3, in Examples 1 to 17, the internal stress was 40 MPa or less. Therefore, the polyimides obtained in Examples 1 to 17 were able to reduce the internal stress. Examples 1-17 had a haze of less than 1.0%. Therefore, the polyimides obtained in Examples 1 to 17 were excellent in transparency. In Examples 1 to 17, Tg was 420° C. or higher. Therefore, the polyimides obtained in Examples 1 to 17 were excellent in heat resistance.

The polyamic acid in the polyamic acid compositions prepared in Comparative Examples 1 and 2 had a fluorine atom content of more than 5% by weight. The polyamic acid in the polyamic acid compositions prepared in Comparative Examples 3-8 did not contain the structural unit (1). As shown in Table 3, in Comparative Examples 1, 2 and 6-8, the internal stress exceeded 40 MPa. Therefore, the polyimides obtained in Comparative Examples 1, 2 and 6-8 could not reduce the internal stress. In Comparative Examples 3-5, the Tg was less than 420°C. Therefore, the polyimides obtained in Comparative Examples 3 to 5 were not excellent in heat resistance.

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 heat resistance while reducing internal stress.

Claims

Including a structural unit represented by the following general formula (1),
A polyamic acid having a fluorine atom content of 5% by weight or less.

(In the general formula (1),
R 1 and R 2 each independently represent a hydrogen atom, a monovalent aliphatic group or a monovalent aromatic group,
X 1 represents a divalent organic group. )
The polyamic acid according to claim 1, wherein both R1 and R2 in the general formula (1) represent a hydrogen atom.
In the general formula (1), X 1 is a group consisting of a divalent organic group represented by the following chemical formula (2-1) and a divalent organic group represented by the following general formula (2-2) The polyamic acid according to claim 1, which is one or more selected from.

(In the general formula (2-2), Y 1 is a divalent organic group represented by the following chemical formula (3-1), a divalent organic group represented by the following chemical formula (3-2), a divalent organic group represented by the chemical formula (3-3), a divalent organic group represented by the following chemical formula (3-4), a divalent organic group represented by the following chemical formula (3-5), and one or more selected from the group consisting of divalent organic groups represented by the following chemical formula (3-6).)
The polyamic acid according to claim 1, further comprising a structural unit represented by the following general formula (4).

(In the general formula (4),
R 3 and R 4 each independently represent a hydrogen atom, a monovalent aliphatic group or a monovalent aromatic group,
X 2 represents a divalent organic group,
Y 2 is a tetravalent organic group represented by the following chemical formula (5-1), a tetravalent organic group represented by the following chemical formula (5-2), or a tetravalent organic group represented by the following chemical formula (5-3). It is one or more selected from the group consisting of a valent organic group and a tetravalent organic group represented by the following chemical formula (5-4). )
The polyamic acid according to claim 1, wherein the fluorine atom content is less than 1% by weight.
A polyamic acid composition containing the polyamic acid according to claim 1 and an organic solvent.
The polyamic acid composition according to claim 6, further comprising an imidization accelerator.
The polyamic acid composition according to claim 7, wherein the amount of the imidization accelerator is 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.
The polyimide according to claim 9, which has a 1% weight loss temperature of 500°C or higher.
The polyimide according to claim 9, which has a glass transition temperature of 420°C or higher.
A polyimide film containing the polyimide according to claim 9.
The polyimide film according to claim 12, which has a yellowness index of 25 or less.
A laminate comprising a support and the polyimide film according to claim 12.
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 6 onto a support to form a coating film containing the polyamic acid, and heating the coating film to imidize the polyamic acid. Method.
13. An electronic device comprising the polyimide film according to claim 12 and an electronic element arranged on the polyimide film.