KR20240027771A - Polyamic acid, polyamic acid composition, polyimide, polyimide film, laminate, method for producing laminate, and electronic device - Google Patents

Abstract

The polyamic acid contains a structural unit represented by the following general formula (1), and has a fluorine atom content of 5% by weight or less. In the following 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. The polyamic acid composition contains a polyamic acid containing a structural unit represented by the following general formula (1) and a fluorine atom content of 5% by weight or less, and an organic solvent. Polyimide is an imidized product of 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.

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 also relates to electronic device materials, thin film transistor (TFT) substrates, flexible display substrates, color filters, printed materials, optical materials, and image display devices (more specifically, liquid crystal display devices, organic EL, and electronic paper) using polyimide. etc.), 3D displays, solar cells, touch panels, transparent conductive film substrates, and alternative materials for members currently using glass.

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

In these devices, various electronic elements, such as thin film transistors and transparent electrodes, are formed on a substrate, and formation of these electronic elements requires a high-temperature process. Polyimide has sufficient heat resistance to adapt to high-temperature processes, and its coefficient of thermal expansion (CTE) is close to that of glass substrates and electronic devices, so it is difficult to generate internal stress, making it suitable for substrate materials such as flexible displays.

Generally, aromatic polyimides are colored yellow-brown due to intramolecular conjugation or formation of charge transfer (CT) complexes, but in top-emission organic EL, etc., light is extracted from the opposite side of the substrate, so the substrate is required to be transparent. However, conventional aromatic polyimides have been used. However, in cases where the light emitted from the display element is emitted through the substrate, such as in transparent displays or bottom-emission organic EL or liquid crystal displays, or in order to use full-screen displays (notchless) in smartphones, etc., sensors or camera modules are used. When placed on the back of a substrate, high optical properties (more specifically, transparency, etc.) have been required for the substrate.

Against this background, there is a demand for a material that has heat resistance equivalent to existing aromatic polyimide, has reduced coloring, and is excellent in transparency.

In order to reduce coloring of polyimide, a technology to suppress the formation of CT complexes using aliphatic monomers (Patent Documents 1 and 2), a technology to increase transparency using a monomer with a fluorene skeleton (Patent Document 3), and A technique for increasing transparency by using a monomer having a fluorine atom (patent document 4) is known.

The polyimides described in Patent Documents 1 and 2 have high transparency and low CTE, but because they have an aliphatic structure, their thermal decomposition temperature is low, making it difficult to apply them to high-temperature processes when forming electronic devices.

Japanese Patent Publication No. 2016-29177 Japanese Patent Publication No. 2012-41530 Taiwan Patent Application Publication No. 201713726 International Publication No. 2019/195148

The polyimide described in Patent Document 3 has high transparency and high heat resistance due to the introduction of a fluorene skeleton. However, since the polyimide described in Patent Document 3 has a high coefficient of thermal expansion (CTE), internal heat generated at the interface between the support and the polyimide film is generated by heating and cooling when forming a polyimide film on a support to obtain a laminate. Stress tends to increase. For this reason, when a laminated body is formed using the polyimide described in Patent Document 3, the laminated body tends to be warped, which may make application to an electronic device difficult.

Moreover, even with the technology described in Patent Document 4, it is difficult to obtain a polyimide with excellent transparency and heat resistance while reducing the internal stress between the support and the polyimide film (hereinafter sometimes simply referred to as “internal stress”).

The present invention has been made in consideration of the above circumstances, and its purpose is to provide a polyimide with excellent transparency and heat resistance while reducing internal stress, and a polyamic acid as a precursor thereof. Another object is to provide products or members that require heat resistance and transparency and are manufactured using the polyimide and polyamic acid. In particular, the object of the present invention is 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.

<Aspects 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 the 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] above, wherein in the general formula (1), both R ¹ and R ² represent hydrogen atoms.

[3] In the general formula ( ¹ ), One or more types of polyamic acid according to [1] or [2] above.

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

[4] The polyamic acid according to any one of [1] to [3] above, 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, and Y ² is represented by the following formula (5) A tetravalent organic group represented by -1), a tetravalent organic group represented by the following formula (5-2), a tetravalent organic group represented by the following formula (5-3), and a tetravalent organic group represented by the following formula (5-4) It is one or more types selected from the group consisting of tetravalent organic groups.

[5] The polyamic acid according to any one of [1] to [4] above, wherein the fluorine atom content is less than 1% by weight.

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

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

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

[9] A polyimide that is an imidized product of the polyamic acid according to any one of [1] to [5] above.

[10] The polyimide according to [9] above, wherein the 1% weight loss temperature is 500°C or higher.

[11] The polyimide according to [9] or [10] above, 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] above.

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

[14] A laminate having a support and the polyimide film according to [12] or [13] above.

[15] The support is a glass substrate,

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

[16] A method of manufacturing a laminate having a support and a polyimide film,

By applying the polyamic acid composition according to any one of [6] to [8] above on a support, a coating film containing the polyamic acid is formed, and the coating film is heated to imidize the polyamic acid. Method for manufacturing a laminate.

[17] An electronic device having the polyimide film according to [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 manufactured using the polyamic acid according to the present invention requires transparency and heat resistance, and is suitable as a material for electronic devices manufactured through a high temperature process.

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

First, the terms used in this specification will be explained. “Structural unit” refers to a repeating unit that constitutes a polymer. “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 addition, in this specification, not only polyamic acid but also polyamic acid ester (polyamic acid alkyl ester, polyamic acid aryl ester, etc.) is described 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, and A ¹ is, for example, a tetracarboxylic dianhydride residue (tetracarboxylic acid represents a tetravalent organic group derived from acid dianhydride), and A ² represents, for example, a diamine residue (a divalent organic group derived from diamine).

The content rate of structural unit (6) relative 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, and more preferably It is 70 mol% or more and 100 mol% or less, more preferably 80 mol% or more and 100 mol% or less, and 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 the polyimide at a measurement temperature of 150°C (100% by weight) is reduced by 1% by weight relative to the weight of the reference. The method of measuring the 1% weight loss temperature is the same as or a method similar to that in the Examples described later.

“m/z” is a measured value that can be read from the horizontal axis of the mass spectrum, which is the measurement result of mass spectrometry, and “the dimensionless quantity obtained by dividing the mass of the ion by the unified atomic mass unit (Dalton) is again calculated as the charge number of the ion. It is a dimensionless quantity obtained by dividing by its absolute value.”

Hereinafter, “system” may be added to the name of the compound, and the compound and its derivatives may be collectively referred to as a generic term. When “system” is added to the end of a compound name to indicate a polymer name, it means that the repeating unit of the polymer is derived from the compound or its derivative. Additionally, tetracarboxylic dianhydride may be described as “acid dianhydride.” In addition, unless otherwise specified, the components, functional groups, etc. exemplified in this specification may be used individually or two or more types may be used in combination.

<Suitable embodiments of the present invention>

The polyamic acid according to the present embodiment contains a structural unit (hereinafter sometimes referred to as “structural unit (1)”) represented by the general formula (1) below, and has 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. In order to easily perform imidization, R ¹ and R ² are each independently preferably a hydrogen atom, a methyl group, or an ethyl group, and it is more preferable that both R ¹ and R ² represent a hydrogen atom. Hereinafter, unless otherwise specified, a structural unit in which both R ¹ and R ² in general formula (1) represent hydrogen atoms is referred to as structural unit (1).

Structural unit (1) is spiro[11H-dipro[3,4-b:3',4'-i]xanthene-11,9'-[9H]fluorene]-1,3,7,9 -Has a partial structure derived from tetron (hereinafter sometimes referred to as “SFDA”). That is, structural unit (1) has an SFDA residue as A ¹ in the general formula (6) described above.

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

SFDA is derived from the xanthene skeleton and has a rigid structure, so it is suitable as a raw material (monomer) for polyimide with a high glass transition temperature (excellent heat resistance) and is also suitable as a raw material (monomer) for polyimide with low CTE. do. Additionally, SFDA is derived from a fluorene skeleton and is suitable as a highly transparent polyimide raw material (monomer). In addition, the polyamic acid containing structural unit (1) has a xanthene skeleton in the main chain and a fluorene skeleton in the side chain, so the polyamic acid produced using the polyamic acid containing structural unit (1) The mid film exhibits low phase difference.

On the other hand, through examination by the present inventors, it was found that when SFDA and a fluorine-containing monomer are used together as monomers for synthesizing polyamic acid, the orientation between the polymer chains of the polyamic acid tends to decrease and the CTE tends to increase. It has been done. 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, since the polyamic acid according to the present embodiment has an SFDA residue that contributes to low CTE and has a fluorine atom content of 5% by weight or less, the internal stress generated when forming a polyimide film on a support to obtain a laminate can be reduced. Therefore, the polyimide manufactured using the polyamic acid according to this embodiment can reduce internal stress.

Additionally, since the polyamic acid according to this embodiment has an SFDA residue that contributes to transparency and heat resistance, the polyimide manufactured using the polyamic acid according to this embodiment is excellent in transparency and heat resistance.

In order to further reduce 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, and is preferably 0.5% by weight. It is more preferable that it is less than %, it is still more preferable that it is less than 0.1 weight%, and it is especially preferable that it is substantially 0 weight% (polyamic acid (1) does not contain a residue derived from a fluorine-containing monomer). In addition, the fluorine atom content (unit: weight%) is the ratio of the weight of the fluorine atom 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. In other words, the fluorine atom content of the polyamic acid is calculated 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” multiplied by 100. obtained. Therefore, the fluorine atom content of polyamic acid can be calculated based on the following equation.

In the above formula, n _i is the amount (unit: mol) of diamine component i, and n _j 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. Additionally, 19.00 is the atomic weight of fluorine. For example, 0.05 mole of 2,2'-bis(trifluoromethyl)benzidine (molecular weight: 320.2, number of fluorine atoms: 6) and 0.95 mole of 4-aminophenyl-4-aminobenzoate (molecular weight: 6) as diamine. 228.3, number of fluorine atoms: 0), 0.3 mole of SFDA (molecular weight: 472.4, number of fluorine atoms: 0) and 0.7 mole of 3,3',4,4'-biphenyl as tetracarboxylic dianhydride. The fluorine atom content of polyamic acid polymerized using tetracarboxylic dianhydride (molecular weight 294.2, number of fluorine atoms: 0) is 100 ×472.4+0.7×294.2)=0.98% by weight.

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 internal stress, a diamine that does not contain a fluorine atom is preferable as the diamine giving X ¹ in General Formula (1).

Diamines that do not contain a fluorine atom include, for example, 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”) may be described), N,N'-(1,4-phenylene)bis(4-aminobenzamide) (hereinafter sometimes described as “PBAB”), bis(4-aminophenyl)tere Phthalate (hereinafter sometimes referred to as “BATP”), N,N’-di(4-aminophenyl)terephthalamide (hereinafter sometimes referred to as “DATA”), 1,3-bis(3 -Aminopropyl) tetramethyldisiloxane (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 may be used alone or in two or more types.

In order to obtain a ^polyimide with better transparency and heat resistance while further reducing the internal stress, It is preferable that it is one or more types selected from the group consisting of residues.

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

In order to obtain a polyimide with better heat resistance, it is preferable that X ¹ in General Formula (1) is a PDA residue. In order to obtain a ^polyimide with better transparency, it is preferable that desirable. In order to obtain a ^polyimide that can further reduce internal stress, it is preferable that desirable.

In order to further reduce internal stress and obtain a polyimide with better transparency and heat resistance, the PDA residue, 4-BAAB residue, DABA residue, BABB residue, and PBAB residue for all diamine residues constituting polyamic acid (1). , the content of one or more residues selected from the group consisting of a BATP residue and a DATA residue (if two or more are included, the total content) is preferably 30 mol% or more, more preferably 40 mol% or more, and 50 mol%. It is more preferable that it is % or more, and it is still more preferable that it is 60 mol% or more, and it may be 70 mol% or more, 80 mol% or more, or 90 mol% or more, and may be 100 mol% or more.

In addition, in order to provide appropriate adhesion to an inorganic material (e.g., a glass substrate, etc.), it is preferable that the polyamic acid (1) contains a PAM-E residue, and the entire polyamic acid (1) constituting the polyamic acid (1) It is more preferable that the content of the PAM-E residue relative to the diamine residue is 0.01 mol% or more and 1 mol% or less.

When synthesizing polyamic acid (1), acid dianhydrides other than SFDA may be used as monomers. In order to further reduce internal stress, an acid dianhydride other than SFDA that does not contain a fluorine atom is preferable.

Examples of acid dianhydride that does not contain a fluorine atom include pyromellitic dianhydride (hereinafter sometimes referred to as “PMDA”), 3,3',4,4'-biphenyltetracarboxylic dianhydride Water (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 Water, 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. These may be used alone or in two or more types.

In order to obtain a polyimide with better transparency and heat resistance while further reducing internal stress, polyamic acid (1) is an acid dianhydride residue other than the SFDA residue, and consists of a PMDA residue, a BPDA residue, a BPAF residue, and an ODPA residue. It is preferable to include one or more types selected from the group. That is, in order to obtain a polyimide with superior transparency and heat resistance while further reducing the internal stress, polyamic acid (1) is a structural unit (hereinafter referred to as “structural unit (4)”) represented by the following general formula (4) It is desirable to further include (sometimes written as).

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

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

In General Formula (4), preferred groups for R ³ , R ⁴ and X ² are the same as those exemplified as preferred groups for R ¹ , R ^{2 and}

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

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

In order to further reduce internal stress and obtain a polyimide with better transparency and heat resistance, it is preferable that the polyamic acid (1) contains a BPDA residue as an acid dianhydride residue other than the SFDA residue. When the polyamic acid (1) contains a BPDA residue, in order to obtain a polyimide with better transparency and heat resistance while further reducing the internal stress, the mass ratio of the SFDA residue to the BPDA residue (SFDA residue/BPDA residue) is It is preferable that it is 10/90 or more and 50/50 or less, more preferably 10/90 or more and 40/60 or less, more preferably 10/90 or more and 35/65 or less, and even more preferably 10/90 or more and 30/70 or less. do.

Polyamic acid (1) may contain only structural unit (1) as a structural unit, or may contain only structural unit (1) and structural unit (4), or may contain only structural unit (1) and structural unit (4). ) may contain structural units other than those (other structural units). In order to obtain a polyimide with superior transparency and heat resistance while further reducing internal stress, the content of structural unit (1) relative to all structural units constituting polyamic acid (1) is preferably 5 mol% or more, It is more preferable that it is 10 mol% or more, it is still more preferable that it is 15 mol% or more, and it is even more preferable that it is 20 mol% or more, and it may be 30 mol% or more, 40 mol% or more, or 50 mol% or more, and it may be 100 mol% or more. does not exist.

When the polyamic acid (1) contains the structural unit (4), in order to further reduce the internal stress and obtain a polyimide with better transparency and heat resistance, the entire structural unit constituting the polyamic acid (1) must be , 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 and 100 mol% or less. It is more preferable, and it is even more preferable that it is 90 mol% or more and 100 mol% or less, and 100 mol% may be sufficient.

In order to obtain a polyimide with better 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, and the following conditions It is more desirable to satisfy 3.

Condition 1: The polyamic acid (1) contains a BPDA residue as an acid dianhydride residue other than the SFDA residue, and does not contain a residue derived from a fluorine-containing monomer.

Condition 2: Condition 1 is satisfied above, and the polyamic acid (1) is at least one 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. Contains a diamine moiety.

Condition 3: Condition 2 above is satisfied, and the substance amount ratio of SFDA residue to BPDA residue (SFDA residue/BPDA residue) is 10/90 or more and 35/65 or less.

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

When synthesizing polyamic acid (1) using diamine and tetracarboxylic dianhydride, the amount of diamine (when using multiple types of diamine, the amount of each diamine) and the amount of tetracarboxylic dianhydride ( When using multiple types of tetracarboxylic dianhydride, the desired polyamic acid (1) (polymer of diamine and tetracarboxylic dianhydride) can be obtained by adjusting the amount of each tetracarboxylic dianhydride. The mole fraction of each residue in polyamic acid (1) corresponds to the mole fraction of each monomer (diamine and tetracarboxylic dianhydride) used in the synthesis of polyamic acid (1), for example. Additionally, by blending two types of polyamic acids, polyamic acid (1) containing multiple types of tetracarboxylic dianhydride residues and multiple types of diamine residues can be obtained. The temperature conditions for the reaction between diamine and tetracarboxylic dianhydride, that is, the synthesis reaction of polyamic acid (1), are not particularly limited, but are, for example, in the range of 20°C or more and 150°C or less. The reaction time for the synthesis 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 in the synthesis of polyamic acid (1) is preferably a solvent that can dissolve the tetracarboxylic dianhydride and diamine used, and a solvent that can dissolve the resulting polyamic acid (1) is more preferable. Organic solvents used in the synthesis of polyamic acid (1) include, for example, urea-based solvents such as tetramethylurea and N,N-dimethylethylurea; Sulfoxide-based solvents such as dimethyl sulfoxide; Sulfone-based solvents such as diphenyl sulfone and tetramethyl sulfone; N,N-dimethylacetamide (DMAC), N,N-dimethylformamide (DMF), N,N-diethylacetamide, N-methyl-2-pyrrolidone (NMP), 3-methoxy-N , amide-based solvents such as N-dimethylpropanamide (MPA) and hexamethyl phosphate triamide; Ester solvents such as γ-butyrolactone; Halogenated alkyl solvents such as chloroform and methylene chloride; Aromatic hydrocarbon-based solvents such as benzene and toluene; Phenol-based solvents such as phenol and cresol; Ketone-based solvents such as cyclopentanone; Ether-based solvents such as tetrahydrofuran, 1,3-dioxolane, 1,4-dioxane, dimethyl ether, diethyl ether, diethylene glycol diethyl ether, diethylene glycol dimethyl ether, and p-cresol methyl ether. You can. Usually, these solvents are used individually, but two or more types may be used in appropriate combination as needed. In order to increase the solubility and reactivity of polyamic acid (1), the organic solvent used in the synthesis reaction of polyamic acid (1) is selected from the group consisting of amide-based solvents, ketone-based solvents, ester-based solvents and ether-based solvents. One or more types of solvents are preferred, and amide-based solvents (more specifically, DMF, DMAC, NMP, MPA, etc.) are more preferred. In addition, the synthesis reaction of polyamic acid (1) is preferably performed under an inert gas atmosphere such as argon or nitrogen.

The weight average molecular weight of polyamic acid (1) varies depending on its use, but is preferably in the range of 10,000 to 1,000,000, more preferably in the range of 20,000 to 500,000, and even more preferably in the range of 30,000 to 200,000. desirable. When the weight average molecular weight is 10,000 or more, it becomes easy to use polyamic acid (1) or polyimide obtained using polyamic acid (1) into a coating film or polyimide film (film). On the other hand, if the weight average molecular weight is 1,000,000 or less, since it exhibits sufficient solubility in solvents, a coating film or polyimide film with a smooth surface and uniform thickness can be obtained using the polyamic acid composition described later. The weight average molecular weight used here refers to the polyethylene oxide conversion value measured using gel permeation chromatography (GPC).

Additionally, as a method of controlling the molecular weight of polyamic acid (1), either an excess of acid dianhydride or diamine is used, or reaction is carried out with a monofunctional acid anhydride or amine such as phthalic anhydride or aniline. There are ways to quench it. When polymerizing either acid dianhydride or diamine in excess, a polyimide film with sufficient strength can be obtained if the molar ratio of these added is between 0.95 and 1.05. In addition, the above-mentioned molar ratio is the ratio of the total material amount of diamine used in the synthesis of polyamic acid (1) to the total material amount of acid dianhydride used in the synthesis of polyamic acid (1) (total material amount of diamine/acid dianhydride) total amount of material). Additionally, coloring of the polyimide obtained using polyamic acid (1) can be further reduced by end-sealing with phthalic anhydride, maleic anhydride, aniline, etc.

The polyamic acid composition according to the present embodiment contains polyamic acid (1) and an organic solvent. Organic solvents contained in the polyamic acid composition include the organic solvents exemplified as organic solvents usable in the synthesis reaction of polyamic acid (1), including amide-based solvents, ketone-based solvents, ester-based solvents, and ether-based solvents. One or more solvents selected from the group consisting of solvents are preferable, and amide-based solvents (more specifically, DMF, DMAC, NMP, MPA, etc.) are more preferable. When polyamic acid (1) is obtained by the above-described method, the reaction solution (solution after reaction) itself may be used as the polyamic acid composition according to the present embodiment. Additionally, 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. In addition, the content rate 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 with respect to the total amount of the polyamic acid composition.

Additionally, 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 improve properties.

The imidization accelerator is not particularly limited, but a tertiary amine can be used. As the tertiary amine, a heterocyclic tertiary amine is preferable. Preferred specific examples of heterocyclic tertiary amines include pyridine, picoline, quinoline, isoquinoline, and imidazole. Preferred 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 developing properties, the amount of the imidization accelerator is preferably 0.1 parts by weight or more and 10 parts by weight or less, and 0.5 parts by weight or more and 5 parts by weight or less, based on 100 parts by weight of polyamic acid (1). It is more desirable. In addition, from the viewpoint of shortening the heating time and developing characteristics, the amount of the dehydration catalyst is preferably 0.1 part by weight or more and 10 parts by weight or less, and 0.5 parts by weight or more 5 parts by weight, based on 100 parts by weight of polyamic acid (1). It is more preferable that it is below.

As an imidization accelerator, imidazoles are preferable. In addition, in this 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, and 2-heptadecyl. Midazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-methylimidazole Sol, 1-benzyl-2-phenylimidazole, etc. are mentioned. Among these, 1,2-dimethylimidazole, 1-benzyl-2-methylimidazole, and 1-benzyl-2-phenylimidazole are preferable, and 1,2-dimethylimidazole and 1-benzyl -2-methylimidazole is more preferred.

The content of imidazole is preferably 0.005 mol or more and 0.1 mol or less, more preferably 0.01 mol or more and 0.08 mol or less, and even more preferably 0.015 mol or more and 0.050 mol or less, based on 1 mole of amide groups of polyamic acid (1). desirable. By containing 0.005 mol or more of imidazole, the film strength and transparency of the polyimide can be improved, and by setting the imidazole content to 0.1 mol or less, heat resistance is improved while maintaining the storage stability of the polyamic acid (1). You can do it. Regarding the improvement in transparency, it is known that polymerization solvents such as NMP form a complex by hydrogen bonding with the carboxyl group of polyamic acid (1), and when the imidization rate is slow, NMP, etc., is incorporated into the polyimide film. There is a possibility that it may remain and cause discoloration by oxidation or decomposition. When imidazoles are added, the imidazoles coordinate with the carboxyl group of polyamic acid (1) and promote imidization, making it difficult for NMP and the like to remain in the polyimide film, and increasing the thermal imidization process. It is thought that transparency is improved because decomposition of polyamic acid (1) is also suppressed. In addition, in this specification, "the amide group of polyamic acid (1)" refers to an amide group produced by the polymerization reaction of diamine and tetracarboxylic dianhydride.

Additionally, imidization is promoted by adding imidazole to polyamic acid, and in the initial stage of thermal imidization, in-plane orientation is induced starting from the imidized rigid unit. However, when imidazoles are added to polyamic acids that are highly oriented without using imidazoles, such as polyamic acids containing BPDA and PDA, the imidazoles act as plasticizers and, conversely, disrupt the orientation of the molecular chains. There are cases of trees. In contrast, since polyamic acid (1) has an SFDA residue, internal stress can be reduced even if imidazoles are added.

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

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

As the plasticizer, a compound that dissolves in the organic solvent used in the polymerization of polyamic acid (1) and exists as a liquid during imidization is preferable. In addition, the plasticizer is preferably one that does not volatilize at low temperatures in order to provide 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. In addition, the plasticizer preferably does not have a decomposition temperature below the boiling point in order to provide sufficient molecular mobility to the polyamic acid (1) during imidization.

The amount of the plasticizer is preferably 0.001 parts by weight or more and 20 parts by weight or less, based on 100 parts by weight of the polyamic acid (1), from the viewpoint of providing sufficient molecular mobility to the polyamic acid (1) and avoiding decomposition of the plasticizer itself. It is more preferable that it is 0.05 parts by weight or more and 15 parts by weight or less, more preferably 0.05 parts by weight or more and 10 parts by weight or less, and even more preferably 0.05 parts by weight or more and 5 parts by weight or less.

The plasticizer not only improves the molecular motion when the polyamic acid (1) is dehydrated and ring-closed to the polyimide, but can also provide functions such as adjustment of the glass transition temperature and flame retardancy. As the plasticizer, for example, one or two or more types can be appropriately selected and used from among known plasticizers.

In order to provide sufficient molecular mobility to the polyamic acid (1), the plasticizer is preferably at least one 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-based compounds, phosphorous acid-based compounds, phosphonic acid-based compounds, phosphinic acid-based compounds, phosphine-based compounds, phosphine oxide-based compounds, phospholane-based compounds, and phosphazene-based compounds. 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. In addition, among these phosphorus-containing compounds, some exist in a tautomeric relationship, such as phosphorous acid-based compounds and phosphonic acid-based compounds, but may exist in any state.

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

Specific examples of phosphorous acid-based compounds include triphenyl phosphite, trisnonylphenyl phosphite, tricresyl phosphite, triethyl phosphite, triisobutyl phosphite, tris(2-ethylhexyl) phosphite, and tridecyl phosphite. , trilauryl phosphite, tris(tridecyl) phosphite, diphenyl phosphite, diethyl phosphite, dibutyl phosphite, dimethyl phosphite, diphenyl mono(2-ethylhexyl) phosphite, diphenyl monodecyl Phosphite, diphenyl mono(tridecyl) phosphite, trilauryl trithio phosphite, diethyl hydrogen phosphite, bis(2-ethylhexyl) hydrogen phosphite, dilauryl hydrogen phosphite, dioleyl hydro. Gene phosphite, diphenyl hydrogen phosphite, tetraphenyldipropylene glycol diphosphite, bis(decyl)pentaerythritol diphosphite, bis(tridecyl)pentaerythritol diphosphite, tristearyl phosphite, distearyl penta Erythritol diphosphite, tris (2,4-di-t-butylphenyl) phosphite, triisodecyl phosphite, 3,9-bis (2,6-di-t-butyl-4-methylphenoxy)- 2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane, etc. can be mentioned.

Examples of the condensate include condensed phosphoric acid ester. Specific examples of condensed phosphoric acid esters include trialkyl polyphosphate, resorcinol polyphenyl phosphate, resorcinol poly(di-2,6-xylyl) phosphate, and hydroquinone poly(2,6-xylyl) phosphate. You can. Commercially available products of condensed phosphate esters include, for example, "CR-733S" manufactured by Daihachi Chemical Industries, Ltd., "CR-741" manufactured by Daihachi Chemical Industries, Ltd., and "FP-600" manufactured by ADEKA Corporation.

Specific examples of phosphazene-based compounds include phenoxycyclophosphazene (“FP-110” manufactured by Fushimi Seiyakuso Co., Ltd.), cyclic cyanophenoxyphosphazene (“FP-300” manufactured by Fushimi Seiyakuso Co., Ltd.), etc. You can.

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, and bis[2-(2-butoxy). Ethoxy) ethyl] adipate, bis (2-ethylhexyl) azelate, dibutyl sebacate, bis (2-ethylhexyl) sebacate, diethyl succinate, etc.

Additionally, the plasticizer may be a low molecular weight organic compound or a thermoplastic resin as long as it exerts 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, N-phenylphthalimide, N-glycidylphthalimide, N-hydroxyphthalimide, Phthalimide-based compounds such as cyclohexylthiophthalimide; Maleimide-based compounds such as N,N-p-phenylenebismaleimide and 2,2'-(ethylenedioxy)bis(ethylmaleimide) can be mentioned. 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 in the polymerization of polyamic acid (1) and exist as a liquid during imidization are preferred. In order to suppress coloring of the polyimide film, it is preferable that it remains during imidization, so the boiling point of the phenolic compound is preferably 50°C or higher, more preferably 100°C or higher, and even more preferably 150°C or higher. do. Additionally, phenol-based compounds that do not have a decomposition temperature below the boiling point are preferable.

Phenol-based compounds include hindered type, semi-hindered type, and less hindered type. Specifically, 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 acrylic acid etc. can be mentioned.

Phenol-based compounds mainly capture peroxy radicals and convert them into hydroperoxides, functioning as primary antioxidants that suppress auto-oxidation of polymers, and thus have the function of suppressing coloring due to oxidation of polymers. Additionally, by combining a phenol-based compound with a phosphorous acid ester or the like that has the function of a secondary antioxidant that converts hydroperoxide into a stable alcohol compound, coloring due to oxidation of the polyimide can be further suppressed. For example, coloring of polyimide can be effectively suppressed by using phosphorous acid ester in the range of more than 10 equivalents and less than 10 equivalents with respect to the phenol-based compound.

In order to sufficiently obtain the antioxidant effect, the amount of the phenolic compound is preferably 0.001 parts by weight or more and 10 parts by weight or less, and more preferably 0.01 parts by weight or more and 5 parts by weight or less, based on 100 parts by weight of polyamic acid (1). It is more preferable that it is 0.02 parts by weight or more and 1 part by weight or less. 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 heat resistance while maintaining the transparency of the polyimide film, nanosilica particles may be used as the additive, and polyamic acid (1) and nanosilica particles may be complexed. From the viewpoint of maintaining the transparency of the polyimide film, the average primary particle diameter of the nanosilica particles is preferably 200 nm or less, more preferably 100 nm or less, further preferably 50 nm or less, and may be 30 nm or less. On the other hand, from the viewpoint of ensuring dispersibility in polyamic acid (1), the average primary particle diameter of the nanosilica particles is preferably 5 nm or more, and more preferably 10 nm or more. As a method of complexing polyamic acid (1) and nanosilica particles, known methods can be used, for example, a method using organosilica sol in which nanosilica particles are dispersed in an organic solvent. As a method of complexing polyamic acid (1) and nano-silica particles using organosilica sol, the polyamic acid (1) is synthesized and then the synthesized polyamic acid (1) and organosilica sol are mixed. This method may be used, but in order to more highly disperse the nano-silica particles in the polyamic acid (1), it is preferable to synthesize the polyamic acid (1) in organosilica sol.

Additionally, in order to increase the interaction with polyamic acid (1), nanosilica particles may be surface treated with a surface treatment agent. As a surface treatment agent, known agents such as silane coupling agents can be used. As silane coupling agents, alkoxysilane compounds having an amino group, glycidyl group, etc. as a functional group are widely known and can be selected appropriately. In order to further increase the interaction with polyamic acid (1), an amino group-containing alkoxysilane is preferable as a silane coupling agent. Examples of amino group-containing alkoxysilanes include 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropylmethyldimethoxysilane, 3-aminopropylmethyldiethoxysilane, and 3-(2-aminoethyl). )Aminopropyltrimethoxysilane, 3-phenylaminopropyltrimethoxysilane, 2-aminophenyltrimethoxysilane, and 3-aminophenyltrimethoxysilane, etc., but from the viewpoint of the stability of the raw material, 3-aminopropyltrimethoxysilane It is preferred to use propyltriethoxysilane. A surface treatment method for nanosilica particles includes a method of stirring a mixture of a dispersion (organosilica sol) with a silane coupling agent under an atmospheric temperature of 20°C or higher and 80°C or lower. The stirring time at this time is, for example, 1 hour or more and 10 hours or less. At this time, a catalyst that promotes the reaction may be added.

The nanosilica-polyamic acid complex, which is a composite of polyamic acid (1) and nanosilica particles, contains nanosilica particles in the range of 1 part by weight to 30 parts by weight based on 100 parts by weight of polyamic acid (1). It is preferable to include it, and it is more preferable to include it within the range of 1 weight part or more and 20 weight parts or less. If the content of the nano silica particles is 1 part by weight or more, the heat resistance of the polyimide containing nano silica particles can be improved and the internal stress can be sufficiently reduced, and if the content of the nano silica particles is 30 parts by weight or less, the polyimide containing nano silica particles The adverse effects on the mechanical properties of mead can be suppressed.

Additionally, the polyamic acid composition according to the present embodiment may contain a silane coupling agent in order to develop appropriate adhesion to the support. Although known types of silane coupling agents can be used without particular limitation, compounds containing an amino group are particularly preferable 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 to 0.50 parts by weight, more preferably 0.01 to 0.10 parts by weight, and 0.01 to 0.05 parts by weight. It is more preferable that it is less than or equal to 100%. 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 exerted, and by setting the mixing ratio of the silane coupling agent to 0.50 parts by weight or less, the decrease in the molecular weight of the polyamic acid (1) is suppressed. Therefore, embrittlement of the polyimide film can be suppressed.

The polyimide according to the present embodiment is an imidized product of the polyamic acid (1) described above. The polyimide according to this embodiment can be obtained by a known method, and its production method is not particularly limited. Hereinafter, an example of a method of imidizing polyamic acid (1) to obtain the polyimide according to the present embodiment will be described. Imidization is performed by dehydrating and ring-closing polyamic acid (1). This dehydration ring closure can be performed by an azeotropic method using an azeotropic solvent, a thermal method, or a chemical method. In addition, the imidization from polyamic acid (1) to polyimide can take any ratio of 1% or more and 100% or less. That is, you may synthesize polyamic acid (1) in which part of the polyamic acid is imidated. In particular, in the case of imidization by heating and increasing temperature, the ring-closure reaction from polyamic acid (1) to polyimide and the hydrolysis of polyamic acid (1) proceed simultaneously, and the molecular weight when converted to polyimide is polyamide. Since the molecular weight may be lower than that of acid (1), it is preferable from the viewpoint of improving mechanical properties to imidize a part of polyamic acid (1) in the polyamic acid composition in advance before forming the polyimide film described later. . In this specification, polyamic acid partially imidized may also be described as “polyamic acid.”

Dehydration and ring closure of the polyamic acid (1) can 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 described above may be placed on a support such as a glass substrate, a metal plate, or a PET film (polyethylene terephthalate film). After application, the polyamic acid (1) may be heat treated within a temperature range of 40°C or higher and 500°C or lower. According to this method, a laminate according to the present embodiment is obtained, which has a support and a polyimide film (specifically, a polyimide film containing an imidized product of polyamic acid (1)) disposed on the support. . Alternatively, the polyamic acid (1) can be dehydrated and ring-closed by putting the polyamic acid composition directly into a container that has been subjected to release treatment such as coating with a fluorine-based resin, and heating and drying the polyamic acid composition under reduced pressure. Polyimide can be obtained by dehydration ring closure of polyamic acid (1) using these methods. In addition, the heating time for each of the above treatments varies depending on the treatment amount and heating temperature of the polyamic acid composition to be dehydrated and ring-closed, but generally, it is within the range of 1 minute to 300 minutes after the treatment temperature reaches the maximum temperature. It is desirable.

The polyimide film (specifically, the polyimide film containing the imidide of polyamic acid (1)) according to the present embodiment is colorless and transparent, has a low yellowness, and has a glass transition temperature ( Since it has heat resistance, it is suitable as a transparent substrate material for flexible displays. The content of polyimide (specifically, imidized product of polyamic acid (1)) in the polyimide film according to the present embodiment is, for example, 70% by weight or more, and 80% by weight, based on the total amount of the polyimide film. It is preferable that it is more than 90 weight%, and it is more preferable that it is 90 weight% or more, and 100 weight% may be sufficient. Components other than polyimide in the polyimide film include, for example, the additives described above (more specifically, nanosilica particles, etc.).

An electronic device (more specifically, a flexible device, etc.) according to the present embodiment has a polyimide film according to the present embodiment, and an electronic element disposed directly or indirectly on the polyimide film. When manufacturing the electronic device according to the present embodiment for use in 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 disposing (forming) an electronic element such as a TFT on the polyimide film. The process of forming TFT is generally carried out in a wide temperature range of 150℃ to 650℃, but in order to actually achieve the desired performance, an oxide semiconductor layer or a-Si layer is formed at 300℃ or higher, and in some cases, In some cases, a-Si, etc. are crystallized again using a laser, etc.

At this time, if the thermal decomposition temperature of the polyimide film is low, outgas is generated during the formation of the electronic device and adheres to the oven as a sublimated product, causing contamination in the furnace, or the inorganic film formed on the polyimide film (a barrier film to be described later). etc.) or the electronic device may peel off, so the 1% weight loss temperature of the polyimide is preferably 500°C or higher. The upper limit of the 1% weight loss temperature of polyimide is, for example, 600°C, although the higher the temperature, 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.). To explain in more detail, 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, in cases where the heat resistance of the polyimide is low, imidization has not progressed completely, or there is a lot of residual solvent, the polyimide and There are cases where the inorganic membrane peels off. For this reason, in addition to the 1% weight loss temperature of the polyimide being 500°C or higher, it is preferable that the weight loss rate when the polyimide is isothermally maintained at a temperature within the range of 400°C or more and 450°C or less is less than 1%.

Furthermore, through examination by the present inventors, it has been revealed that polyimide obtained using a fluorine-containing monomer generates corrosive gases such as hydrogen fluoride as outgas in high-temperature processes such as the production of TFT elements, for example. If corrosive gas is generated during a high-temperature process, the barrier film laminated on the polyimide film may corrode, causing peeling, etc. 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, even more preferably less than 0.1% by weight, and is substantially 0. % by weight (polyamic acid (1) does not contain residues derived from fluorine-containing monomers) is particularly preferred.

As an indicator of the amount of hydrogen fluoride gas generated when the imidide of polyamic acid (1) (polyimide according to the present embodiment) is used in a high temperature process, the detection intensity obtained from the mass spectrum can be cited. In detail, first, under a helium gas stream, the polyimide is heated from an ambient temperature of 60°C at a temperature increase rate of 10°C/min, and when the ambient temperature reaches 470°C, the gas generated from the polyimide is measured using a quadrupole mass spectrometer. Analyze as And, from the obtained mass spectrum (specifically, a mass spectrum showing the results of analyzing the components of the gas generated from the polyimide when the atmospheric temperature reached 470°C), m/z = 20, which is estimated to be caused by hydrogen fluoride, The detected intensity of the peak (hereinafter sometimes referred to as “20 peak intensity”) is read. As the amount of hydrogen fluoride generated increases, the intensity of peak 20 tends to increase. In addition, the flow rate of helium gas when analyzing with a quadrupole mass spectrometer can be set so that the gas generated from the polyimide can be analyzed by the quadrupole mass spectrometer in real time, for example, 50 mL/min or more 150 mL/min. minutes or less, preferably 80 mL/min or more and 120 mL/min or less.

Additionally, when the glass transition temperature (Tg) of the polyimide is significantly lower than the process temperature, positional misalignment, etc. may occur during the formation of the electronic device, so the Tg of the polyimide is preferably 300°C or higher, and 350°C. It is more preferable that it is more than 400°C, and it is even more preferable that it is 420°C or more. The higher the upper limit of the Tg of polyimide, the better, but for example, it is 470°C. Additionally, since the thermal expansion coefficient of the glass substrate is generally small compared to that of the resin, internal stress occurs between the glass substrate and the polyimide film. If the internal stress of the laminate of the glass substrate or electronic device used as the support and the polyimide film is high, the laminate containing the polyimide film expands in the high-temperature TFT formation process and then contracts when cooled to room temperature, resulting in glass. Problems such as bending or damage of the substrate or peeling of the polyimide film from the glass substrate occur. Therefore, the internal stress between the polyimide film and the glass substrate is preferably 40 MPa or less, and more preferably 35 MPa or less. The lower the lower limit of the internal stress, the better, and it may be 0 MPa. The method of measuring internal stress is the same as or a method similar to that in the Examples described later.

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 purpose, a method of forming an electronic device (specifically, an electronic device with an electronic element formed on a polyimide film) on a support as described above and then peeling the polyimide film from the support is adopted. There are many cases where it is done. Additionally, as a material for the support, alkali-free glass is suitably used. Hereinafter, an example of a method for producing a laminate of a polyimide film and a support will be described in detail.

First, the polyamic acid composition according to the present embodiment is applied (flexed) on a support to form a laminate containing a coating film containing the polyamic acid (1) and a support. Next, the coating film-containing laminate is heated under conditions of, for example, a temperature of 40°C or more and 200°C or less. The heating time at this time is, for example, 3 minutes or more and 120 minutes or less. In addition, 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 advance imidization of the polyamic acid (1) in the coating film, the coating film-containing laminate is heated, for example, under conditions of a maximum temperature of 200°C or more and 500°C or less. The heating time at this time (heating time at the highest temperature) is, for example, 1 minute or more and 300 minutes or less. At this time, it is desirable to gradually increase the temperature from the low temperature to the highest temperature. The temperature increase rate is preferably 2°C/min or more and 10°C/min or less, and more preferably 4°C/min or more and 10°C/min or less. Additionally, the maximum temperature is preferably in the range of 250°C or more and 450°C or less. If the maximum temperature is 250°C or higher, imidization sufficiently progresses, and if the maximum temperature is 450°C or lower, thermal deterioration and coloring of the polyimide can be suppressed. Additionally, the temperature may be maintained at any temperature for any 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 achieve higher transparency, it is preferable to carry out under reduced pressure or in an inert gas such as nitrogen. Additionally, as the heating device, known devices such as a hot air oven, an infrared oven, a vacuum oven, an inner oven, and a hot plate can be used. Through these steps, the polyamic acid (1) in the coating film is imidized, and a laminate of the support and the polyimide film (film containing the imidized product of polyamic acid (1)) (i.e., in the present embodiment) is imidized. laminate) can be obtained.

A known method can be used to peel the polyimide film from the obtained laminate of the support and the polyimide film. For example, the peeling may be done by hand or using a mechanical device such as a drive roll or robot. Furthermore, there is a method of providing a release layer between the support and the polyimide film, or forming a silicon oxide film on a substrate with a plurality of grooves, forming a polyimide film with the silicon oxide film as a base layer, and forming a release layer between the substrate and the silicon oxide film. A method of peeling off the polyimide film can also be adopted by infiltrating the polyimide film with an etching solution of silicon oxide. Additionally, a method of separating the polyimide film by irradiation of laser light can also be adopted.

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 using a polyimide film for an application requiring high transparency, the total light transmittance of the polyimide film is preferably 75% or more, and more preferably 80% or more. Additionally, when using a polyimide film for an application requiring high transparency, the haze of the polyimide film is preferably 1.5% or less, more preferably 1.2% or less, even more preferably less than 1.0%, and may be 0%. In applications requiring high transparency, the polyimide film is required to have high transmittance in the entire wavelength range, but the polyimide film tends to easily absorb light at short wavelengths, and the film itself is often colored yellow. In order to use a polyimide film for applications requiring high transparency, it is desirable that the coloring of the polyimide film is reduced. Specifically, in order to use the polyimide film for applications requiring high transparency, the yellowness (YI) of the polyimide film is preferably 25 or less, more preferably 20 or less, and may 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). In this way, the polyimide film with reduced coloring and imparted transparency is suitable for transparent substrates such as those used to replace glass, or substrates on which a sensor or camera module is provided on the back.

Additionally, there are two types of light extraction methods for flexible displays: a top emission method that extracts light from the front side of the TFT, and a bottom emission method that extracts light from the back side of the TFT. The top emission method is characterized by the fact that light is not blocked by the TFT, so it is easy to increase the aperture ratio and obtain high-precision image quality, while the bottom emission method is characterized by the ease of alignment of the TFT and the pixel electrode, making it easy to manufacture. . If the TFT is transparent, it becomes possible to improve the aperture ratio even in the bottom emission method, so the bottom emission method, which is easy to manufacture, tends to be adopted for large displays. Since the polyimide film according to the present embodiment has a low YI and excellent heat resistance, it can be applied to any of the above light extraction methods.

In addition, in the batch-type device manufacturing process in which a polyamic acid composition is applied onto a support such as a glass substrate, heated to imidize, formed an electronic element, etc., and then the polyimide film is peeled, the support and the polyimide are used. It is desirable to have excellent adhesion between membranes. Adhesion here means adhesion strength. In the manufacturing process of peeling the polyimide film on which the electronic devices etc. are formed from the support after forming the electronic devices on the polyimide film on the support, if the adhesion between the polyimide film and the support is excellent, the electronic devices, etc. can be formed more accurately. Or it can be mounted. In the manufacturing process of disposing electronic devices, etc. through a polyimide film on a support, from the viewpoint of improving productivity, the higher the peeling strength between the support and the polyimide film, the better. Specifically, the peeling strength is preferably 0.05 N/cm or more, and more preferably 0.1 N/cm or more.

In the above-described manufacturing process, when peeling a polyimide film from a laminate of a support and a polyimide film, the polyimide film is often peeled from the support by laser irradiation. In this case, because 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 more, and more preferably 330 nm or more. 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. From the viewpoint of achieving both transparency (light yellowness) and processability of laser peeling, the cutoff wavelength of the polyimide film is preferably 320 nm or more and 390 nm or less, and more preferably 330 nm or more and 380 nm or less. In addition, the cutoff wavelength in this specification means the 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 is in coating or molding processes for manufacturing products or members, but may be used as a material for performing coating or other treatments on molded articles molded into a film shape. It may be possible. For use in a coating or molding process, the polyamic acid composition or polyimide is dissolved or dispersed in an organic solvent as needed, and also blended with a photocurable component, a thermosetting component, a non-polymerizable binder resin, and other components as needed. Thus, a composition containing polyamic acid (1) or polyimide may be prepared.

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

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

In addition, the polyamic acid composition according to the present embodiment is a batch-type device manufacturing process in which the polyamic acid composition is applied onto a support, heated to imidize, forms an electronic device, etc., and then the polyimide film is peeled off. It can be used appropriately. Therefore, the present embodiment also includes a method of manufacturing an electronic device including the step of applying a polyamic acid composition on a support, heating and imidizing the polyamic acid composition, and forming an electronic element, etc. on the polyimide film formed on the support. . In addition, the manufacturing method of such an electronic device may further include a step of peeling the polyimide film on which the electronic element or the like is formed from the support.

Example

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

<Method of measuring physical properties>

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

[Yellowness (YI)]

For the polyimide film in each laminate obtained in the examples and comparative examples described later, the transmittance of light with a wavelength of 200 nm to 800 nm was measured using an ultraviolet, visible, near-infrared spectrophotometer (“V-650” manufactured by Nippon Bunko Corporation). Then, the yellowness (YI) of the polyimide film was calculated from the formula described in JIS K7373-2006.

[Hayes]

The polyimide film peeled from each laminate obtained in the examples and comparative examples described later was measured using an integrating sphere haze meter (“HM-150N” manufactured by Murakami Shikisai Gijutsu Kenkyujo Co., Ltd.) according to JIS K7136-2000. Haze was measured by the method. When the haze was less than 1.0%, it was evaluated as “excellent transparency.” On the other hand, when the haze was 1.0% or more, it was evaluated that “transparency is not excellent.”

[Internal stress]

Each polyamic acid composition prepared in the Examples and Comparative Examples described below was applied to a glass substrate (material: alkali-free glass, thickness: 0.7 mm, size: 100 mm x 100 mm) manufactured by Corning, whose warpage was previously measured, using a spin coater. It was applied and heated at 120°C for 30 minutes in the air, and then heated at 430°C for 30 minutes under a nitrogen atmosphere to obtain a laminate including a polyimide film with a thickness of 10 μm on a glass substrate. In order to exclude 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 measuring device (“FLX-, manufactured by KLA Tenco). 2320-S”). Then, from the amount of warping of the glass substrate and the amount of warping of the laminate before forming the polyimide film, the internal stress generated between the glass substrate and the polyimide film was calculated using Stoney's equation. When the internal stress was 40 MPa or less, it was evaluated that “the internal stress can be reduced.” On the other hand, when the internal stress exceeded 40 MPa, it was evaluated that “the internal stress cannot be reduced.”

[Glass transition temperature (Tg)]

A polyimide film sampled to a size of 3 mm in width and 10 mm in length from each laminate obtained in the examples and comparative examples described later was 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 (elongation) were plotted. A TMA curve was obtained. The inflection point temperature of the obtained TMA curve (temperature corresponding to the peak in the differential curve of the TMA curve) was called the glass transition temperature (Tg). When Tg was 420°C or higher, it was evaluated as “excellent heat resistance.” On the other hand, when Tg was less than 420°C, it was evaluated that “heat resistance is not excellent.”

[1% weight loss temperature (TD1)]

Each polyimide film (specifically, a polyimide film sampled from each laminate so that the weight was 10 mg) obtained in the examples and comparative examples described later was used as a sample for measurement, and a differential heat thermogravimetric simultaneous measurement device ( Using "TG/DTA7200" manufactured by Hitachi High-Tech Science, Inc., the temperature was raised from 25°C to 650°C under nitrogen atmosphere at 20°C/min, and the weight of the sample at the measurement temperature of 150°C was used as the standard. The measurement temperature when the weight decreased by 1% by weight was referred to as the 1% weight loss temperature (TD1).

[Analysis of gas generated from polyimide film]

The gas generated from the polyimide film during heating was analyzed using an analysis device combining a thermogravimetric measurement device (“STA449 F5” manufactured by NETZSCH) and a quadrupole mass spectrometer (“JMS-Q1500GC” manufactured by Nippon Electronics). Below, the analysis procedure will be explained.

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. Next, using the thermogravimetric measurement device, each polyimide film obtained in the comparative example described later (in detail, The polyimide film sampled from each laminate was heated to a mass of 140 mg and the gas generated from the polyimide film when the ambient temperature reached 470°C was analyzed using the quadrupole mass spectrometer. Additionally, by heating the polyimide film under a helium gas stream using the analysis device, 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. Then, from the mass spectrum obtained by analyzing the gas generated from the polyimide film when the ambient temperature reached 470°C with the quadrupole mass spectrometer, the detection intensity of the peak at m/z = 20 (20 peak intensity) was read. In addition, the base line of the mass spectrum was adjusted so that the peak intensity at a temperature of 60°C was 2000 ± 100.

<Production of polyimide film>

Hereinafter, the manufacturing method of the polyimide film (laminated body) of Examples and Comparative Examples will be described. In addition, below, compounds and reagents are described by the following abbreviated names. In addition, preparation of the polyamic acid composition used for producing the polyimide film was all carried out under a nitrogen atmosphere.

NMP: N-methyl-2-pyrrolidone

SFDA: spiro[11H-dipro[3,4-b:3',4'-i]xanthene-11,9'-[9H]fluorene]-1,3,7,9-tetron

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-aminophenyl)terephthalamide

PAM-E: 1,3-bis(3-aminopropyl)tetramethyldisiloxane

TFMB: 2,2'-bis(trifluoromethyl)benzidine

DMI: 1,2-dimethylimidazole

[Example 1]

88.0 g of NMP was added as an organic solvent for polymerization to a 300 mL glass separable flask equipped with a stirrer equipped with a stainless steel stirring rod and a nitrogen introduction tube. Next, while stirring the flask contents, 2.240 g of PDA was added to the flask and dissolved. Next, 9.760 g of SFDA was added to the flask contents, and then the flask contents were stirred for 24 hours in an atmosphere at a temperature of 25°C to obtain a polyamic acid composition. The obtained polyamic acid composition was applied onto a glass substrate (manufactured by Corning, material: alkali-free glass, thickness: 0.7 mm, size: 100 mm x 100 mm) using a spin coater, and coated in air at 120°C for 30 minutes. After heating, it was heated at 430°C for 30 minutes in a nitrogen atmosphere to obtain a laminate (laminated body of Example 1) including a polyimide film with a thickness of 10 μm on a glass substrate.

[Example 2]

88.0 g of NMP was added as an organic solvent for polymerization to a 300 mL glass separable flask equipped with a stirrer equipped with a stainless steel stirring rod and a nitrogen introduction tube. Next, while stirring the flask contents, 2.240 g of PDA was added to the flask and dissolved. Next, 9.760 g of SFDA was added to the flask contents, and then the flask contents were stirred for 24 hours in an atmosphere at a temperature of 25°C. Next, DMI was added to the flask contents to obtain a polyamic acid composition. The amount of DMI added was 1 part by weight based on 100 parts by weight of polyamic acid in the flask contents. The obtained polyamic acid composition was applied onto a glass substrate (manufactured by Corning, material: alkali-free glass, thickness: 0.7 mm, size: 100 mm x 100 mm) using a spin coater, and coated in air at 120°C for 30 minutes. After heating, it was heated at 430°C for 30 minutes in a nitrogen atmosphere to obtain a laminate (laminated body of Example 2) including a polyimide film with a thickness of 10 μm on a glass substrate.

[Examples 3 to 17 and Comparative Examples 1 to 8]

Examples 3, 5, 6, and 8 were prepared in the same manner as in Example 1, except that the acid dianhydride used and its input ratio, and the diamine used and its input ratio were as shown in Tables 1 and 2. , 10, 12, 13, 15, and 17, and Comparative Examples 1, 2, 3, and 5 were obtained, respectively. In addition, Examples 4, 7, and 9 were prepared in the same manner as in Example 2, except that the acid dianhydride used and its input ratio, and the diamine used and its input ratio were as shown in Tables 1 and 2. , 11, 14, and 16, and comparative examples 4, 6, 7, and 8 were obtained, respectively. In addition, for all of Examples 3 to 17 and Comparative Examples 1 to 8, the total amount of acid dianhydride when producing the polyamic acid composition was the same as that in Examples 1 and 2. In addition, for all of Examples 3 to 17 and Comparative Examples 1 to 8, the total amount of diamine when producing the polyamic acid composition was the same as that in Examples 1 and 2.

In addition, in Tables 1 and 2, “-” means that the component in question was not used. In addition, in Tables 1 and 2, the numerical value in the “acid dianhydride” column is the content rate (unit: mol%) of each acid dianhydride relative to the total amount of acid dianhydride used. In Tables 1 and 2, the numerical value in the “diamine” column is the content rate (unit: mol%) of each diamine relative to the total amount of diamine used. In Tables 1 and 2, the numerical value in the “DMI” column is the amount of DMI (unit: parts by weight) relative to 100 parts by weight of polyamic acid. In addition, for all of Examples 1 to 17 and Comparative Examples 1 to 8, the mole fraction of each residue of the polyamic acid in the prepared polyamic acid composition was determined by each monomer (diamine and tetracarboxylic acid) used in the synthesis of the polyamic acid. It was consistent with the mole fraction of acid dianhydride).

<Measurement results of physical properties>

For each of Examples 1 to 17 and Comparative Examples 1 to 8, the measurement results of physical properties are shown in Table 3. In addition, in Table 3, “-” means not measured. In addition, in Table 3, “fluorine atom content” is a calculated value calculated using the above-mentioned formula.

The polyamic acid in the polyamic acid composition prepared in Examples 1 to 17 contained 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 internal stress. In Examples 1 to 17, the haze was less than 1.0%. Therefore, the polyimides obtained in Examples 1 to 17 had excellent transparency. In Examples 1 to 17, Tg was 420°C or higher. Therefore, the polyimides obtained in Examples 1 to 17 had excellent heat resistance.

The polyamic acid in the polyamic acid composition prepared in Comparative Examples 1 and 2 had a fluorine atom content exceeding 5% by weight. The polyamic acid in the polyamic acid composition prepared in Comparative Examples 3 to 8 did not contain structural unit (1). As shown in Table 3, in Comparative Examples 1, 2, and 6 to 8, the internal stress exceeded 40 MPa. Therefore, the internal stress of the polyimides obtained in Comparative Examples 1, 2, and 6 to 8 was not reduced. In Comparative Examples 3 to 5, 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 was excellent in transparency and heat resistance while reducing internal stress.

Claims (17)

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

(In the above 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 in the general formula (1), R ¹ and R ² both represent hydrogen atoms. The method according to claim 1, wherein in the general formula ( ¹ ), One or more polyamic acids selected from.

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

The polyamic acid according to claim 1, further comprising a structural unit represented by the following general formula (4).

(In the above 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 formula (5-1), a tetravalent organic group represented by the following formula (5-2), a tetravalent organic group represented by the following formula (5-3), and It is one or more types selected from the group consisting of tetravalent organic groups represented by the 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 based on 100 parts by weight of the polyamic acid. A polyimide, which is an imidized product of the polyamic acid according to claim 1. 10. The polyimide according to claim 9, wherein the 1% weight loss temperature is at least 500°C. The polyimide according to claim 9, wherein the glass transition temperature is 420°C or higher. A polyimide film comprising the polyimide according to claim 9. The polyimide film according to claim 12, wherein the polyimide film has a yellowness of 25 or less. A laminate comprising a support and the polyimide film according to claim 12. 15. The method of claim 14, wherein the support is a glass substrate,
A laminate wherein the internal stress between the polyimide film and the glass substrate is 40 MPa or less. A method for manufacturing a laminate having a support and a polyimide film,
A method for producing a laminate, comprising forming a coating film containing the polyamic acid by applying the polyamic acid composition according to claim 6 on a support, and heating the coating film to imidize the polyamic acid. An electronic device comprising the polyimide film according to claim 12 and an electronic element disposed on the polyimide film.