WO2023248810A1

WO2023248810A1 - Polyamic acid composition, polyimide production method, laminate production method, and electronic device production method

Info

Publication number: WO2023248810A1
Application number: PCT/JP2023/021312
Authority: WO
Inventors: 博文中山; 萌子加藤; 隆之介滝; 伸明田中; 友貴白井; 越生堀井
Original assignee: 株式会社カネカ
Priority date: 2022-06-24
Filing date: 2023-06-08
Publication date: 2023-12-28
Also published as: TW202409147A

Abstract

This polyamic acid composition contains a polyamic acid and an organic solvent. The polyamic acid has a residue including a divalent organic group represented by chemical formula (1), a 3,3',4,4'-biphenyl tetracarboxylic dianhydride residue, and a p-phenylene diamine residue. The organic solvent contains at least one compound selected from the group consisting of compounds represented by general formula (2) and compounds represented by general formula (3). In general formula (2), R¹, R², and R³ each independently represent a hydrogen atom or a monovalent organic group having one or more carbon atoms, and at least one of R¹, R², and R³ represents a monovalent organic group having two or more carbon atoms. In general formula (3), R⁴ represents a monovalent organic group having two or more carbon atoms.　

Description

Polyamic acid composition, polyimide manufacturing method, laminate manufacturing method, and electronic device manufacturing method

The present invention relates to a polyamic acid composition, a method for producing a polyimide, a method for producing a laminate, and a method for producing an electronic device. The present invention further provides electronic device materials using polyimide, thin film transistor (TFT) substrates, flexible display substrates, color filters, printed matter, optical materials, image display devices (more specifically, liquid crystal display devices, organic EL, electronic paper, etc.), 3D displays, solar cells, touch panels, transparent conductive film substrates, and alternative materials for members in which glass is currently used.

With the rapid advancement 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 the substrate, and high-temperature processes are required to form these electronic elements. Polyimide has sufficient heat resistance to be applicable to high-temperature processes, and its coefficient of thermal expansion (CTE) is similar to that of glass substrates and electronic devices, making it less susceptible to internal stress and suitable for substrate materials such as flexible displays. be.

The above-mentioned substrate material is produced by coating a support with a solution in which polyamic acid is dissolved (polyamic acid composition) and imidizing the polyamic acid to form a polyimide film, and then electronic devices are laminated on top of the polyimide film. Manufactured by

Solvents for dissolving polyamic acid are usually those with a relatively small number of carbon atoms, such as N,N-dimethylformamide (DMF), N-methyl-2-pyrrolidone (NMP), and N,N-dimethylacetamide (DMAC). Amide solvents are currently used, but from the perspective of their impact on the environment and the human body, there is a growing need to switch to safer solvents.

As an example of preparing a polyamic acid composition using a highly safe solvent, an example is known in which a polyamic acid salt is used and water is used as a solvent (Patent Document 1, etc.). In addition, examples are known in which polyamic acids are synthesized using alkoxy-N-substituted propanamides as solvents with low concern for teratogenicity (Patent Documents 2 and 3, etc.).

JP2012-36382A Special table 2017-517582 publication International Publication No. 2022/054850

As a result of verification by the present inventors, when the polyamic acid compositions described in Patent Documents 1 to 3 are applied onto a support and the polyamic acid is imidized, the adhesiveness between the obtained polyimide film and the support increases. It has been found that defects tend to occur more easily and internal stress generated at the interface between the polyimide film and the support tends to increase. Hereinafter, poor adhesion between the polyimide film and the support may be simply referred to as "poor adhesion." Further, the internal stress generated at the interface between the polyimide film and the support may be simply referred to as "internal stress." If the internal stress increases, it may become difficult to apply it to electronic devices.

The present invention has been achieved in view of the above circumstances, and provides a polyamic acid composition that can suppress the occurrence of poor adhesion and reduce internal stress while using a highly safe solvent, and the polyamic acid composition. An object of the present invention is to provide a method for manufacturing polyimide, a method for manufacturing a laminate, and a method for manufacturing an electronic device using a composition.

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

[1] A polyamic acid composition containing a polyamic acid and an organic solvent,
The polyamic acid contains a residue containing a divalent organic group represented by the following chemical formula (1), a 3,3',4,4'-biphenyltetracarboxylic dianhydride residue, and p-phenylenediamine. has a residue,
The organic solvent is a polyamic acid composition containing one or more compounds selected from the group consisting of a compound represented by the following general formula (2) and a compound represented by the following general formula (3).

In the general formula (2), R ¹ , R ² and R ³ each independently represent a ^hydrogen atom or ^a monovalent organic group having ¹ or more carbon atoms; At least one represents a monovalent organic group having 2 or more carbon atoms,
In the general formula (3), R ⁴ represents a monovalent organic group having 2 or more carbon atoms.

[2] The residue containing the divalent organic group represented by the chemical formula (1) above may be a tetravalent organic group represented by the following chemical formula (4) or a tetravalent organic group represented by the following chemical formula (5). The polyamic acid composition according to [1] above, which is one or more residues selected from the group consisting of an organic group and a divalent organic group represented by the following chemical formula (6).

[3] The content of residues containing a divalent organic group represented by the chemical formula (1) is equal to or less than all tetracarboxylic dianhydride residues constituting the polyamic acid and all diamines constituting the polyamic acid. The polyamic acid composition according to [1] or [2] above, wherein the polyamic acid composition is 15 mol% or less with respect to a total of 100 mol% with residues.

[4] The above [1] to [3], wherein the organic solvent is 3-methoxy-N,N-dimethylpropanamide, 3-butoxy-N,N-dimethylpropanamide, or 1-butyl-2-pyrrolidone. The polyamic acid composition according to any one of .

[5] The polyamic acid composition according to any one of [1] to [4] above, wherein the polyamic acid further has a 1,3-bis(3-aminopropyl)tetramethyldisiloxane residue.

[6] The content of the 1,3-bis(3-aminopropyl)tetramethyldisiloxane residue is 0.1 mol% or more and 1.0 mol% or more based on the total amount of diamine residues constituting the polyamic acid. The polyamic acid composition according to [5] above, wherein the polyamic acid composition is mol % or less.

[7] The polyamic acid composition according to any one of [1] to [6] above, further comprising a silane coupling agent.

[8] A method for producing polyimide, which comprises heating the polyamic acid composition according to any one of [1] to [7] above to imidize the polyamic acid.

[9] A method for producing a laminate having a support and a polyimide film, comprising:
A coating film containing the polyamic acid is formed by coating the polyamic acid composition according to any one of [1] to [7] above on a support, and the coating film is heated to form a coating film containing the polyamide acid. A method for producing a laminate by imidizing acid.

[10] Step Sa of heating the polyamic acid composition according to any one of [1] to [7] to imidize the polyamic acid;
A method for manufacturing an electronic device, comprising a step Sb of arranging an electronic element on the polyimide film obtained in the step Sa.

According to the present invention, a polyamic acid composition that can suppress the occurrence of poor adhesion and reduce internal stress while using a highly safe solvent, and a method for producing polyimide using the polyamic acid composition, A method for manufacturing a laminate and a method for manufacturing an electronic device can be provided.

Hereinafter, preferred embodiments of the present invention will be described in detail, but the present invention is not limited thereto. In addition, all academic literature and patent literature described in this specification are incorporated herein by reference.

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 (7) (hereinafter sometimes referred to as "structural unit (7)").

In general formula (7), A ¹ represents a tetracarboxylic dianhydride residue (tetravalent organic group derived from tetracarboxylic dianhydride), and A ² represents a diamine residue (divalent organic group derived from diamine). represents an organic group).

The content of the structural unit (7) with respect to all the 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 70 mol%. It is 100 mol% or more, more preferably 80 mol% or more and 100 mol% or less, even more preferably 90 mol% or more and 100 mol% or less, and may be 100 mol%.

The "1% weight loss temperature" is the measurement temperature at which the weight of polyimide at a measurement temperature of 150° C. is a reference (100% by weight) and the weight is reduced by 1% by weight with respect to the above-mentioned reference weight. The method for measuring the 1% weight loss temperature is the same method as in the examples described later or a method similar thereto.

Both "alkyl group" and "alkoxyalkyl group" are linear or branched and unsubstituted.

Hereinafter, the compound and its derivatives may be collectively referred to by adding "system" after the compound name. Furthermore, when a polymer name is expressed by adding "system" after the compound name, it means that the repeating unit of the polymer is derived from the compound or its derivative, unless otherwise specified. Moreover, tetracarboxylic dianhydride may be described as "acid dianhydride." Moreover, unless otherwise specified, the components, functional groups, etc. illustrated in this specification may be used alone, or two or more types may be used in combination.

<Preferred embodiment of the present invention>
The polyamic acid composition according to this embodiment includes a polyamic acid and an organic solvent. The polyamic acid (hereinafter sometimes referred to as "specific polyamic acid") contained in the polyamic acid composition according to the present embodiment is a residue containing a divalent organic group represented by the following chemical formula (1) ( (hereinafter sometimes referred to as "residue (1)"), a 3,3',4,4'-biphenyltetracarboxylic dianhydride residue, and a p-phenylenediamine residue. The organic solvent contained in the polyamic acid composition according to the present embodiment is a compound represented by the following general formula (2) (hereinafter sometimes referred to as "compound (2)") and a compound represented by the following general formula (3). It includes one or more compounds selected from the group consisting of the compounds represented by (hereinafter sometimes referred to as "compound (3)"). Hereinafter, one or more compounds (organic solvent) selected from the group consisting of compound (2) and compound (3) may be referred to as a "specific organic solvent." Further, 3,3',4,4'-biphenyltetracarboxylic dianhydride may be referred to as "BPDA". Furthermore, p-phenylenediamine is sometimes written as "PDA".

In general formula (2), R ¹ , R ² and R ³ each independently represent a hydrogen atom or a monovalent organic group having 1 or more carbon atoms, and at least one of R ¹ , R ² and R ³ One represents a monovalent organic group having 2 or more carbon atoms. Further, in the general formula (3), R ⁴ represents a monovalent organic group having 2 or more carbon atoms.

In general, polyamic acid compositions are made from amide-based compounds with a relatively small number of carbon atoms, such as N,N-dimethylformamide, N-methyl-2-pyrrolidone, and N,N-dimethylacetamide, from the viewpoint of improving solubility and properties. Solvents are used, but these solvents have come to be viewed as problematic due to their health hazards. On the other hand, specific organic solvents have less impact on the environment and the human body and are highly safe.

In order to improve safety, R ¹ , R ² and R ³ in general formula (2) are each independently preferably a monovalent organic group having 1 or more carbon atoms, and preferably a monovalent organic group having 1 or more carbon atoms. The following monovalent organic groups are more preferred. In order to further improve safety, R ¹ and R ² in general formula (2) are each independently preferably an alkyl group having 1 or more carbon atoms, and an alkyl group having 1 or more and 6 or less carbon atoms. More preferred. In order to further improve safety, R ³ in general formula (2) is preferably an alkoxyalkyl group having 2 or more carbon atoms, more preferably an alkoxyalkyl group having 2 or more and 6 or less carbon atoms.

In order to improve safety, R ⁴ in general formula (3) is preferably a monovalent organic group having 2 or more and 6 or less carbon atoms. In order to further improve safety, R ⁴ in general formula (3) is preferably an alkyl group having 2 or more and 6 or less carbon atoms.

Examples of the compound (2) include 3-methoxy-N,N-dimethylpropanamide, 3-butoxy-N,N-dimethylpropanamide, N,N-diethylacetamide, N,N-dimethylpropionamide, and the like. It will be done. Among these, 3-methoxy-N,N-dimethylpropanamide or 3-butoxy-N,N-dimethylpropanamide is preferred from the viewpoint of safety.

Examples of the compound (3) include 1-ethyl-2-pyrrolidone and 1-butyl-2-pyrrolidone. Among these, 1-butyl-2-pyrrolidone is preferred from the viewpoint of safety.

The polyamic acid composition according to the present embodiment may contain only compound (2), only compound (3), or both compound (2) and compound (3) as the specific organic solvent. good. In order to increase safety, the specific organic solvent is preferably 3-methoxy-N,N-dimethylpropanamide, 3-butoxy-N,N-dimethylpropanamide or 1-butyl-2-pyrrolidone; More preferred are methoxy-N,N-dimethylpropanamide or 1-butyl-2-pyrrolidone.

The specific polyamic acid has a rigid structure because it contains a BPDA residue and a PDA residue. Therefore, the specific polyamic acid can reduce internal stress.

On the other hand, the present inventors have found that when a polyimide film is formed using a polyamic acid composition containing a polyamic acid having a rigid structure and a specific organic solvent, floating occurs at the interface between the polyimide film and the support. It turned out to be easier. If there is any floating at the interface between the polyimide film and the support, the polyimide film may peel off during the formation of electronic devices, or the yield may decrease when peeling the polyimide film from the support after forming the electronic device. . Note that "lifting" is caused by the adhesion between the polyimide film and other material layers (more specifically, the glass substrate, sacrificial layer, etc.) due to subcomponents and residual solvent generated during imidization. Refers to a state where a defect has occurred. Specific examples of "lifting" include a state in which the polyimide film is lifted from the support, a state in which part of the polyimide film is destroyed and delamination occurs between the polyimide film and another material layer, and the like.

In general, polyimide films obtained from polyamic acids having BPDA residues and PDA residues have densely packed molecular chains, so if a solvent with a relatively large number of carbon atoms, such as a specific organic solvent, is used, Gas release tends to be poor. Therefore, in the process of coating a polyamic acid composition containing a polyamic acid with a rigid structure onto a support and imidizing it, residual solvent and molecules released during imidization are trapped, and the polyimide membrane and the support are It is assumed that floating is likely to occur at the interface. On the other hand, as a result of intensive studies by the present inventors, when a polyamic acid (specific polyamic acid) having a BPDA residue, a PDA residue, and a residue (1) is used, the residue (1) becomes bulky. It has been found that the structure allows for good gas release while reducing internal stress. That is, according to the polyamic acid composition according to the present embodiment, since it contains a specific polyamic acid and a specific organic solvent, it is possible to use a highly safe solvent while suppressing the occurrence of poor adhesion due to good gas release properties. Not only that, but the internal stress can be reduced.

Since the residue (1) is a residue contained in polyamic acid, it is one or more residues selected from the group consisting of tetracarboxylic dianhydride residues and diamine residues. The specific polyamic acid may have only a tetracarboxylic dianhydride residue as the residue (1), or may have only a diamine residue, or may have a tetracarboxylic dianhydride residue and a diamine residue. It may have both groups.

Examples of the tetracarboxylic dianhydride for forming the residue (1) include spiro[11H-difuro[3,4-b:3',4'-i]xanthene-11,9'-[9H ] Fluorene]-1,3,7,9-tetrone (hereinafter sometimes referred to as "SFDA"), 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride (hereinafter referred to as "BPAF") ), 9,9-bis[4-(3,4-dicarboxyphenoxy)phenyl]fluorene dianhydride, 5,5'-[9H-fluoren-9-ylidene bis(2-methyl -4,1-phenylene)]bis(1,3-dihydro-1,3-dioxo-5-isobenzofurancarboxylate), N,N'-(9H-fluorene-9-ylidene-4,1-phenylene) Bis[1,3-dihydro-1,3-dioxo-5-isobenzofurancarboxamide], 5,5'-spiro[9H-fluorene-9,9'-[9H]xanthene]-3',6'- Examples include diylbis(1,3-dihydro-1,3-dioxo-5-isobenzofurancarboxylate) and the like. In order to further suppress the occurrence of poor adhesion, SFDA or BPAF is preferable as the tetracarboxylic dianhydride for forming the residue (1).

Examples of the diamine for forming the residue (1) include 9,9-bis(4-aminophenyl)fluorene (hereinafter sometimes referred to as "BAFL"), 3,3'-(9H- Examples include fluorene-9,9-diyl)dianiline, 4,4'-(9H-fluorene-9-ylidene)bis[2-fluorobenzenamine], and the like. In order to further suppress the occurrence of poor adhesion, BAFL is preferable as the diamine for forming the residue (1).

In order to further suppress the occurrence of poor adhesion, residue (1) is preferably one or more residues selected from the group consisting of SFDA residues, BPAF residues, and BAFL residues. The SFDA residue is a tetravalent organic group represented by the following chemical formula (4). The BPAF residue is a tetravalent organic group represented by the following chemical formula (5). The BAFL residue is a divalent organic group represented by the following chemical formula (6).

Among these, the SFDA residue has a rigid structure derived from the xanthene structure, so in order to further reduce the internal stress and further suppress the occurrence of poor adhesion, the SFDA residue (1) should be used as the residue (1). Particularly preferred are groups.

In order to suppress an increase in the coefficient of thermal expansion, the content of residue (1) (if more than one type of residue (1) is included, the total content) must be lower than all the tetracarboxylic acids constituting the specific polyamic acid. It is preferably 15 mol% or less, more preferably 10 mol% or less, and 5 mol% or less, based on the total 100 mol% of the acid dianhydride residue and all the diamine residues constituting the specific polyamic acid. % or less. In addition, in order to further suppress the occurrence of poor adhesion, it is necessary to ensure that the content of residue (1) (if multiple types of residue (1) are included, their total content) constitutes the specific polyamic acid. It is preferably 0.1 mol% or more, and preferably 0.5 mol% or more with respect to the total 100 mol% of all tetracarboxylic dianhydride residues and all diamine residues constituting the specific polyamic acid. More preferably, it is 1 mol% or more.

When synthesizing the specific polyamic acid, an acid dianhydride other than BPDA and the acid dianhydride for forming the residue (1) may be used as a monomer to the extent that its performance is not impaired. Examples of acid dianhydrides other than the acid dianhydride for forming BPDA and residue (1) include pyromellitic dianhydride, p-phenylene bis(trimelitate anhydride), 1,2,5, 6-naphthalenetetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 2,2',3,3'-biphenyltetracarboxylic dianhydride, 3,3',4 , 4'-benzophenone tetracarboxylic dianhydride, 4,4'-oxydiphthalic anhydride, dicyclohexyl-3,3',4,4'-tetracarboxylic dianhydride, 1,2,4,5-cyclohexane Tetracarboxylic dianhydride, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 2'-oxodispiro[bicyclo[2.2.1]heptane-2,1'-cyclopentane-3',2 Examples include ''-bicyclo[2.2.1]heptane]-5,6:5'',6''-tetracarboxylic dianhydride and derivatives thereof, and these may be used alone or in combination of two or more. good.

In order to further reduce internal stress, the content of BPDA residues should be 70 mol% or more with respect to the total amount (100 mol%) of tetracarboxylic dianhydride residues constituting the specific polyamic acid. is preferable, more preferably 80 mol% or more, still more preferably 90 mol% or more, and may be 100 mol%.

When residue (1) is a residue derived from an acid dianhydride (SFDA residue, BPAF residue, etc.), in order to further suppress the occurrence of poor adhesion, the content of residue (1) must be , is preferably 0.1 mol% or more, more preferably 0.5 mol% or more, based on the total amount (100 mol%) of the tetracarboxylic dianhydride residues constituting the specific polyamic acid. . In addition, when the residue (1) is a residue derived from an acid dianhydride (SFDA residue, BPAF residue, etc.), in order to further reduce internal stress, the content of the residue (1) must be It is preferably 10 mol% or less, more preferably 8 mol% or less, based on the total amount (100 mol%) of the tetracarboxylic dianhydride residues constituting the specific polyamic acid.

In order to further reduce internal stress while further suppressing the occurrence of poor adhesion, the total content of acid dianhydride-derived residues (1) and BPDA residues should be lower than that of the tetracarboxylic acid constituting the specific polyamic acid. It is preferably 60 mol% or more, more preferably 70 mol% or more, even more preferably 80 mol% or more, and 90 mol% based on the total amount (100 mol%) of dianhydride residues. % or more, and may be 100 mol%.

When synthesizing the specific polyamic acid, a diamine other than the diamine for forming PDA and the residue (1) may be used as a monomer to the extent that its performance is not impaired. Examples of diamines other than diamine for forming PDA and residue (1) include 4-aminophenyl-4-aminobenzoate, 2,2'-bis(trifluoromethyl)-4,4'-diaminodiphenyl ether , 1,4-cyclohexanediamine, 4,4'-diaminobenzanilide, m-phenylenediamine, 4,4'-oxydianiline, 3,4'-oxydianiline, N,N'-bis(4-amino Phenyl) terephthalamide, 4,4'-diaminodiphenylsulfone, m-tolidine, o-tolidine, 4,4'-bis(4-aminophenoxy)biphenyl, 2-(4-aminophenyl)-6-aminobenzoxazole , 3,5-diaminobenzoic acid, 4,4'-diamino-3,3'-dihydroxybiphenyl, 4,4'-methylenebis(cyclohexaneamine), 1,3-bis(3-aminopropyl)tetramethyldisiloxane (hereinafter sometimes referred to as "PAM-E") and derivatives thereof, and these may be used alone or in combination of two or more.

In order to improve the adhesion between the polyimide membrane and the support, PAM-E is preferred as the diamine other than the diamine for forming PDA and the residue (1). That is, in order to improve the adhesion between the polyimide membrane and the support, it is preferable that the specific polyamic acid has a PAM-E residue.

In order to further improve the adhesion between the polyimide membrane and the support, the content of PAM-E residues should be 0.05 mol based on the total amount (100 mol%) of diamine residues constituting the specific polyamic acid. % or more, more preferably 0.1 mol% or more, and may be 0.2 mol% or more. In addition, in order to suppress a decrease in yield when peeling the polyimide film from the support after forming an electronic device, it is necessary to adjust the content of PAM-E residues to the total amount of diamine residues constituting the specific polyamic acid ( 100 mol%), it is preferably 1.0 mol% or less, more preferably 0.9 mol% or less, even more preferably 0.8 mol% or less, and even more preferably 0.7 mol%. % or less is even more preferable, and may be 0.6 mol% or less.

In order to further reduce internal stress, the content of PDA residues is preferably 70 mol% or more, and 80 mol% or more, based on the total amount (100 mol%) of diamine residues constituting the specific polyamic acid. % or more, more preferably 90 mol% or more, and may be 100 mol%.

When the residue (1) is a diamine-derived residue (such as a BAFL residue), in order to further suppress the occurrence of poor adhesion, the content of the residue (1) must be such that the content of the specific polyamic acid is It is preferably 0.1 mol% or more, more preferably 0.5 mol% or more, based on the total amount (100 mol%) of diamine residues. In addition, when the residue (1) is a diamine-derived residue (BAFL residue, etc.), in order to further reduce the internal stress, it is necessary to adjust the content of the residue (1) to the diamine that constitutes the specific polyamic acid. It is preferably at most 10 mol%, more preferably at most 8 mol%, even more preferably at most 5 mol%, based on the total amount of residues (100 mol%).

In order to further reduce internal stress while further suppressing the occurrence of poor adhesion, the total content of diamine-derived residues (1) and PDA residues should be adjusted to the total content of diamine residues constituting the specific polyamic acid ( 100 mol%), preferably 60 mol% or more, more preferably 70 mol% or more, even more preferably 80 mol% or more, and particularly preferably 90 mol% or more. , 100 mol%.

When the specific polyamic acid has a PAM-E residue, the polyamic acid composition can further reduce internal stress while further suppressing the occurrence of poor adhesion, and can further improve the adhesion between the polyimide film and the support. In order to obtain , the total content of PAM-E residues, diamine-derived residues (1), and PDA residues should be such that the total content of diamine residues (100 mol%) constituting the specific polyamic acid is as follows: It is preferably 60 mol% or more, more preferably 70 mol% or more, even more preferably 80 mol% or more, particularly preferably 90 mol% or more, even if it is 100 mol%. good.

In order to further suppress the occurrence of poor adhesion while further reducing internal stress, the specific polyamic acid preferably satisfies the following condition 1, more preferably satisfies the following condition 2, and satisfies the following condition 3. It is more preferable, and it is particularly preferable that Condition 4 below is satisfied.
Condition 1: The total content of residue (1), BPDA residue, and PDA residue is the same as that of all the tetracarboxylic dianhydride residues that make up the specific polyamic acid and all the diamine residues that make up the specific polyamic acid. It is 90 mol% or more with respect to the total 100 mol%.
Condition 2: Satisfies Condition 1 above and further has a PAM-E residue.
Condition 3: Condition 2 above is satisfied, and the content of PAM-E residue is 0.1 mol% or more and 1.0 mol based on the total amount (100 mol%) of diamine residues constituting the specific polyamic acid. % or less.
Condition 4: The above condition 3 is satisfied, and the total content of residue (1), BPDA residue, PDA residue, and PAM-E residue is all the tetracarboxylic dianhydride residues constituting the specific polyamic acid. It is 95 mol% or more and 100 mol% or less with respect to the total 100 mol% of all the diamine residues constituting the specific polyamic acid.

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

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

The organic solvent used in the synthesis of the specific polyamic acid is preferably a solvent that can dissolve the tetracarboxylic dianhydride and diamine used, and more preferably a solvent that can dissolve the specific polyamic acid to be produced. From the viewpoint of safety, the above-mentioned specific organic solvents are preferable as the organic solvent used in the synthesis of the specific polyamic acid. Furthermore, organic solvents other than the specific organic solvent may be used in the synthesis of the specific polyamic acid. Examples of organic solvents other than specific organic solvents include urea-based solvents such as tetramethylurea and N,N-dimethylethylurea; sulfoxide-based solvents such as dimethyl sulfoxide; and sulfone-based solvents such as diphenyl sulfone and tetramethyl sulfone. Solvent: Amide solvent other than specific organic solvents such as N,N-dimethylacetamide (DMAC), N,N-dimethylformamide (DMF), N-methyl-2-pyrrolidone (NMP), hexamethylphosphoric triamide; γ - Ester solvents such as butyrolactone; halogenated alkyl solvents such as chloroform and methylene chloride; aromatic hydrocarbon solvents such as benzene and toluene; phenolic solvents such as phenol and cresol; ketone solvents such as cyclopentanone; Examples include ether 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. Usually, these solvents are used alone, but two or more types may be used in combination as necessary. Further, the synthesis reaction of the specific polyamic acid is preferably carried out under an inert gas atmosphere such as argon or nitrogen.

The polyamic acid composition according to this embodiment contains a specific polyamic acid and a specific organic solvent. When the specific polyamic acid is obtained by the method described above, the reaction solution (solution after reaction) itself may be used as the polyamic acid composition according to the present embodiment. When the reaction solution itself is used as the polyamic acid composition according to the present embodiment, the above-mentioned specific organic solvents are preferable as the organic solvent used for synthesizing the specific polyamic acid. Alternatively, the solid specific polyamic acid obtained by removing the solvent from the reaction solution may be dissolved in a specific organic solvent to prepare the polyamic acid composition according to the present embodiment.

The polyamic acid composition according to this embodiment may contain an organic solvent other than the specific organic solvent. However, from the viewpoint of safety, the content of the specific organic solvent in the polyamic acid composition according to this embodiment is preferably 70% by weight or more based on the total amount of organic solvent in the polyamic acid composition. , more preferably 80% by weight or more, still more preferably 90% by weight or more, and particularly preferably 100% by weight. Note that the content of the specific polyamic acid in the polyamic acid composition according to the present embodiment is not particularly limited, but is, for example, 1% by weight or more and 80% by weight or less based on the total amount of the polyamic acid composition.

The weight average molecular weight of the specific polyamic acid depends on its use, but is preferably in the range of 10,000 or more and 1,000,000 or less, more preferably in the range of 20,000 or more and 500,000 or less. , more preferably in the range of 30,000 or more and 200,000 or less. When the weight average molecular weight is 10,000 or more, the specific polyamic acid or the polyimide obtained using the specific polyamic acid can be easily formed into a coating film or a polyimide film. On the other hand, when the weight average molecular weight is 1,000,000 or less, sufficient solubility in solvents is exhibited, so that a coating film or polyimide film with a smooth surface and a uniform thickness can be obtained using the polyamic acid composition. It will be done. The weight average molecular weight used here refers to a polyethylene oxide equivalent value measured using gel permeation chromatography (GPC).

In addition, methods for controlling the molecular weight of specific polyamic acids include adding an excess of either acid dianhydride or diamine, or reacting with monofunctional acid anhydrides or amines such as phthalic anhydride or aniline. One method is to quench the reaction by When polymerizing with an excess of either acid dianhydride or diamine, a polyimide film having sufficient strength can be obtained if the molar ratio of these is between 0.95 and 1.05. The above charging molar ratio is the ratio of the total amount of diamine used in the synthesis of the specific polyamic acid to the total amount of acid dianhydride used in the synthesis of the specific polyamic acid (total amount of diamine/acid dianhydride). total amount of anhydride). Further, by end-capping with phthalic anhydride, maleic anhydride, aniline, etc., coloring of polyimide obtained using a specific polyamic acid can be further reduced.

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

The above-mentioned 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 the heterocyclic tertiary amine include pyridine, picoline, quinoline, isoquinoline, and imidazoles. Preferred specific examples of the dehydration catalyst include acetic anhydride, propionic anhydride, n-butyric anhydride, benzoic anhydride, trifluoroacetic anhydride, and the like.

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 20 parts by weight or less, and 0.1 parts by weight or more and 20 parts by weight or less, based on 100 parts by weight of the specific polyamic acid. More preferably, the amount is 5 parts by weight or more and 20 parts by weight or less. Further, from the viewpoint of shortening the heating time and developing characteristics, the amount of the dehydration catalyst is preferably 0.1 parts by weight or more and 10 parts by weight or less, and 0.1 parts by weight or more and 10 parts by weight or less, based on 100 parts by weight of the specific polyamic acid. More preferably, the amount is 5 parts by weight or more and 5 parts by weight or less.

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

The content of imidazoles 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, per 1 mol of the amide group of the specific polyamic acid. It is preferably 0.015 mol or more and 0.050 mol or less. By containing 0.005 mol or more of imidazoles, the film strength and transparency of polyimide can be improved, and by controlling the content of imidazoles to 0.1 mol or less, the storage stability of specific polyamic acid can be improved. It is possible to improve heat resistance while maintaining the same. In addition, in this specification, "the amide group of a specific polyamic acid" refers to the amide group produced|generated by the polymerization reaction of a diamine and a tetracarboxylic dianhydride.

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

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

Furthermore, the polyamic acid composition according to the present embodiment may contain a silane coupling agent in order to develop appropriate adhesion to the support. Any known silane coupling agent can be used without particular limitation. In order to develop good adhesion to the support, the usable silane coupling agent is preferably a compound containing an amino group, such as 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropyldiethoxymethylsilane, 3-(ethoxydimethylsilyl)propylamine, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyl More preferably, one or more compounds selected from the group consisting of dimethoxysilane and N-phenyl-3-aminopropyltrimethoxysilane, and more preferably selected from the group consisting of 3-aminopropyltriethoxysilane and 3-aminopropyldiethoxymethylsilane. More preferred are one or more compounds, with 3-aminopropyltriethoxysilane being particularly preferred.

The blending ratio of the silane coupling agent to 100 parts by weight of the specific polyamic acid is preferably 0.01 parts by weight or more and 0.50 parts by weight or less, and 0.01 parts by weight or more and 0.30 parts by weight or less. is more preferable, and even more preferably 0.01 part by weight or more and 0.20 part by weight or less. By setting the blending ratio of the silane coupling agent to 0.01 parts by weight or more, the peeling suppressing effect on the support can be sufficiently exhibited, and by setting the blending ratio of the silane coupling agent to 0.50 parts by weight or less, Since molecular weight reduction of the specific polyamic acid is suppressed, embrittlement of the polyimide film can be suppressed.

In organic solvents with a high pH such as 3-methoxy-N,N-dimethylpropanamide, the reaction rate of the silane coupling agent may increase, making it difficult to control the condensation reaction of the generated silanol groups. It is preferable to reduce the number of alkoxy groups as necessary or to use a silane coupling agent having an alkoxy group with low reactivity. Specifically, by using 3-aminopropyltriethoxysilane, 3-aminopropyldiethoxymethylsilane, 3-(ethoxydimethylsilyl)propylamine, etc., the condensation reaction of silanol groups can be controlled and the support can be bonded to the support. Good adhesion and releasability can be achieved.

The method for producing polyimide according to the present embodiment includes a step of heating the polyamic acid composition according to the present embodiment to imidize the specific polyamic acid. The method of imidizing the specific polyamic acid is not particularly limited, and any known method can be employed. An example of a method for imidizing a specific polyamic acid will be described below. Imidization is performed by dehydrating and ring-closing a specific polyamic acid. This dehydration ring closure can be performed by an azeotropic method using an azeotropic solvent, a thermal method, or a chemical method. Alternatively, the polyamic acid composition may be placed directly into a container that has been subjected to mold release treatment such as coating with a fluororesin, and the polyamic acid composition may be heated and dried under reduced pressure to perform dehydration and ring closure of the specific polyamic acid. You can also do it. Polyimide can be obtained by dehydration and ring closure of specific polyamic acids using these methods. The heating time for each of the above treatments varies depending on the amount of polyamic acid composition to be treated and the heating temperature that undergoes dehydration and ring closure, but generally it is in the range of 1 minute to 300 minutes after the treatment temperature reaches the maximum temperature. It is preferable that

Further, the imidization of the specific polyamic acid to polyimide can be performed at any ratio of 1% or more and 100% or less. In other words, a partially imidized specific polyamic acid may be synthesized. In particular, when imidization is performed by heating and increasing temperature, the ring-closing reaction from the specific polyamic acid to polyimide and the hydrolysis of the specific polyamic acid proceed simultaneously, and the molecular weight when converted into polyimide becomes lower than the molecular weight of the specific polyamic acid. Therefore, from the viewpoint of improving mechanical properties, it is preferable to imidize a part of the specific polyamic acid in the polyamic acid composition before forming the polyimide film described below. In this specification, a partially imidized polyamic acid may also be referred to as a "polyamic acid".

The method for manufacturing a laminate according to the present embodiment is a method for manufacturing a laminate having a support and a polyimide film (specifically, a polyimide film containing an imidized product of a specific polyamic acid). In the method for manufacturing a laminate according to the present embodiment, the specific polyamic acid is dehydrated and ring-closed by heating the specific polyamic acid, and is imidized. The method of heating the specific polyamic acid is not particularly limited, but for example, a coating film containing the specific polyamic acid is formed by coating the polyamic acid composition according to the present embodiment described above on a support. For example, a method of heat-treating the coated film at a temperature of 40° C. or higher and 500° C. or lower may be mentioned. Examples of the support include a glass substrate, a metal plate, a PET film (polyethylene terephthalate film), and a glass substrate with a sacrificial layer in which an amorphous silicon layer (a-Si layer) is laminated on a glass substrate. According to this method, a laminate including a support and a polyimide film (specifically, a polyimide film containing an imidized product of a specific polyamic acid) disposed on the support can be obtained.

The polyimide film (specifically, the polyimide film containing an imidide of a specific polyamic acid) formed by the method for manufacturing a laminate according to the present embodiment is colorless and transparent, has a low degree of yellowness, and has a glass transition temperature that can withstand the TFT manufacturing process. (heat resistance), it is suitable as a transparent substrate material for flexible displays. The content of polyimide (specifically, an imidized product of a specific polyamic acid) in the polyimide film is, for example, 70% by weight or more, preferably 80% by weight or more, and 90% by weight, based on the total amount of the polyimide film. It is more preferable that the amount is above, and may be 100% by weight. Examples of components other than polyimide in the polyimide film include the above-mentioned additives (more specifically, fine particles, etc.).

The method for manufacturing an electronic device (more specifically, a flexible device, etc.) according to the present embodiment includes a step Sa of heating the polyamic acid composition according to the present embodiment to imidize a specific polyamic acid, and a step Sa. and step Sb of arranging an electronic element on the obtained polyimide film. Step Sa is, for example, the same as the method for manufacturing the laminate according to the present embodiment described above. In step Sb, for example, an electronic element (such as a TFT) is placed directly or indirectly on the polyimide film obtained in step Sa.

When manufacturing an electronic device for a flexible display, first, a polyimide film is formed on an inorganic base material such as glass as a support. Then, an electronic device is formed on the support by arranging (forming) an electronic element such as a TFT on the polyimide film. The process of forming TFTs is generally carried out over a wide temperature range of 150°C to 650°C, but in order to actually achieve the desired performance, the oxide semiconductor layer or a-Si layer must be heated at 300°C or higher. In some cases, a-Si or the like may be further crystallized using a laser or the like.

At this time, if the thermal decomposition temperature of the polyimide film is low, outgas is generated during the formation of electronic devices and adheres to the oven as a sublimate, causing contamination inside the oven. It is preferable that the 1% weight loss temperature of the polyimide is 500° C. or higher because there is a possibility that the barrier film (described later) or the electronic device may peel off. 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, BPDA residues, PDA residues, etc.). More specifically, before forming the TFT, an inorganic film such as a silicon oxide film (SiOx film) or a silicon nitride film (SiNx film) is formed as a barrier film on the polyimide film. At this time, if the heat resistance of polyimide is low, if imidization has not progressed completely, or if there is a large amount of residual solvent, it may be caused by volatile components such as polyimide decomposition gas during the high temperature process after laminating the inorganic film. The polyimide and the inorganic film may peel off. For this reason, in addition to the 1% weight loss temperature of polyimide being 500°C or higher, the weight loss rate when polyimide is maintained isothermally at a temperature within the range of 400°C to 450°C is less than 1%. desirable.

Furthermore, if the glass transition temperature (Tg) of the polyimide is significantly lower than the process temperature, positional shift etc. may occur during the formation of electronic devices, so the Tg of the polyimide is preferably 300°C or higher. The temperature is more preferably 350°C or higher, even more preferably 400°C or higher, and even more preferably 420°C or higher. The upper limit of the Tg of polyimide is, for example, 470°C, although the higher the better. Furthermore, since the coefficient of thermal expansion of a glass substrate is generally smaller than that of a 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 a support and the polyimide film is high, the laminate including the polyimide film expands during the high-temperature TFT formation process and then contracts when cooled to room temperature. However, problems such as warpage and breakage of the glass substrate and peeling of the polyimide film from the glass substrate occur. Therefore, in a laminate having a support and a polyimide film, the internal stress between the polyimide film and the support is preferably 40 MPa or less, more preferably 30 MPa or less, and even more preferably 20 MPa. , 10 MPa or less is particularly preferable. The lower the lower limit of the internal stress, the better, and may be 0 MPa. The method for measuring internal stress is the same method as in the examples described later or a method similar thereto.

The polyimide obtained by the manufacturing method according to this embodiment can be suitably used as a material for display substrates such as TFT substrates and touch panel substrates. When using polyimide for the above-mentioned purposes, a method is used in which an electronic device (more specifically, an electronic device in which an electronic element is formed on a polyimide film) is formed on a support as described above, and then the polyimide film is peeled from the support. Often adopted. Further, as the material of the support, alkali-free glass is suitably used. An example of a method for producing a laminate of a polyimide film and a support will be described in detail below.

First, the polyamic acid composition according to the present embodiment is applied (cast) onto a support to form a coating film-containing laminate consisting of a coating film containing the specific polyamic acid and the support. Next, the coating film-containing laminate is heated, for example, at a temperature of 40° C. or higher and 200° C. or lower. The heating time at this time is, for example, 3 minutes or more and 120 minutes or less. Note that a multi-step heating process may be provided, such as heating the coating film-containing laminate at a temperature of 50° C. for 30 minutes and then heating it at a temperature of 100° C. for 30 minutes. Next, in order to promote imidization of the specific polyamic acid in the coating film, the coating film-containing laminate is heated at a maximum temperature of 200° C. or more and 500° C. or less, for example. The heating time (heating time at the highest temperature) at this time is, for example, 1 minute or more and 300 minutes or less. At this time, it is preferable to gradually raise the temperature from a low temperature to a maximum temperature. The temperature increase rate is preferably 2°C/min or more and 10°C/min or less, more preferably 4°C/min or more and 10°C/min or less. Moreover, it is preferable that the maximum temperature is in the range of 250°C or more and 480°C or less. If the maximum temperature is 250°C or higher, imidization will proceed sufficiently, and if the maximum temperature is 480°C or lower, thermal deterioration and coloring of polyimide can be suppressed. Further, the temperature may be maintained at any temperature for any period of time until the maximum temperature is reached. The imidization reaction can be carried out under air, under reduced pressure, or in an inert gas such as nitrogen, but in order to achieve higher transparency, it is carried out under reduced pressure or in an inert gas such as nitrogen. It is preferable. Further, as the heating device, a known device such as a hot air oven, an infrared oven, a vacuum oven, an inert oven, a hot plate, etc. can be used. Through these steps, the specific polyamic acid in the coating film is imidized, and a laminate of the support and the polyimide film (a film containing an imidized product of the specific polyamic acid) 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, it may be peeled off by hand or using a mechanical device such as a drive roll or a robot. Furthermore, we have proposed a method of providing a peeling layer between the support and the polyimide film, or forming a silicon oxide film on a substrate with many grooves, forming a polyimide film using the silicon oxide film as a base layer, and separating the substrate and the oxide film. It is also possible to adopt a method in which the polyimide film is peeled off by infiltrating a silicon oxide etching solution between the polyimide film and the silicon film. Alternatively, a method in which the polyimide film is separated by irradiation with 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 applications requiring high transparency, the total light transmittance of the polyimide film is preferably 75% or more, more preferably 80% or more. Furthermore, when using a polyimide film in applications that require high transparency, the haze of the polyimide film is preferably 1.5% or less, more preferably 1.2% or less, and 1.0% or less. It is more preferably less than or equal to 0%. In applications that require high transparency, polyimide films are required to have high transmittance over the entire wavelength range, but polyimide films tend to absorb light at shorter wavelengths, causing the film itself to turn yellow. Often colored. In order to use a polyimide film in applications requiring high transparency, it is preferable that the polyimide film has reduced coloring. Specifically, in order to use a polyimide film in applications that require high transparency, the yellow index (YI) of the polyimide film is preferably 25 or less, more preferably 20 or less, It may be 0. YI can be measured according to JIS K7373-2006. YI can be adjusted, for example, by changing the content of residue (1) in the specific polyamic acid. A polyimide film with reduced coloration and imparted transparency is suitable for a transparent substrate used as a substitute for glass, or a substrate on which a sensor or camera module is provided on the back side.

Furthermore, there are two types of light extraction methods for flexible displays: a top emission method in which light is extracted from the front side of the TFT, and a bottom emission method in which light is extracted from the back side of the TFT. The top-emission method is characterized by the fact that light is not blocked by the TFT, making it easy to increase the aperture ratio and providing high-definition image quality, while the bottom-emission method is easy to manufacture because it is easy to align the TFT and pixel electrode. It has characteristics. If the TFT is transparent, it is possible to improve the aperture ratio even in the bottom emission method, so there is a tendency for the bottom emission method, which is easy to manufacture, to be adopted for large displays. The polyimide film obtained by the manufacturing method according to this embodiment has a low YI and excellent heat resistance, so it can be applied to either of the above light extraction methods.

In addition, in a batch-type device manufacturing process in which a polyamic acid composition is coated on a support such as a glass substrate, heated to imidize to form an electronic element, and then the polyimide film is peeled off, the support and It is preferable to have excellent adhesion with the polyimide film. Adhesion here means adhesion strength. In the manufacturing process of forming electronic devices, etc. on a polyimide film on a support, and then peeling off the polyimide film on which the electronic devices, etc. are formed, from the support, if the adhesion between the polyimide film and the support is excellent, the electronic device etc. can be formed or implemented more accurately. In a manufacturing process in which electronic devices and the like are placed on a support via a polyimide film, from the viewpoint of improving productivity, the peel strength between the support and the polyimide film is preferably 0.05 N/cm or more. , more preferably 0.1 N/cm or more. The method for measuring the peel strength is the same method as in the examples described later or a method similar thereto.

In the manufacturing process as described above, 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, since it is necessary for the polyimide film 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, more preferably 330 nm or more. On the other hand, if the cutoff wavelength is a long wavelength, 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 (low yellow degree) and workability for 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. Note that the cutoff wavelength in this specification means a wavelength at which the transmittance is 0.1% or less as measured by an ultraviolet-visible spectrophotometer.

The polyamic acid composition according to the present embodiment and the polyimide obtained by the manufacturing method according to the present embodiment may be used as they are in coating or molding processes for producing products or members, but they can also be molded into a film. It can also be used as a material for further processing such as coating on the molded product. For use in coating or molding processes, the polyamic acid composition or polyimide is optionally dissolved or dispersed in an organic solvent, and optionally a photocurable component, a thermosetting component, and a non-polymerizable binder. A composition containing the specific polyamic acid or polyimide may be prepared by blending the resin and other components.

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

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

Furthermore, the polyamic acid composition according to the present embodiment is suitable for a method for producing a polyimide film, in which the polyamic acid composition is applied onto a support, heated to imidize, and then the polyimide film is peeled off from the support. Can be used. In addition, the polyamic acid composition according to the present embodiment is prepared by coating the polyamic acid composition on a support, heating it to imidize it, forming electronic devices, etc. on the formed polyimide film, and then applying the polyamic acid composition to the support. It can be suitably used in a batch-type device manufacturing process in which a polyimide film on which electronic elements and the like are formed is peeled off. Therefore, the method for manufacturing an electronic device according to the present embodiment may include the step of peeling off the polyimide film on which the electronic elements and the like are formed from the support.

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

<Methods for measuring and evaluating physical properties>
First, a method for measuring and evaluating physical properties of polyimide (polyimide film) will be explained.

[Internal stress]
The samples were prepared in the Examples and Comparative Examples described later on a glass substrate manufactured by Corning Inc. (product name: Eagle Each of the polyamic acid compositions prepared above was applied using a spin coater, heated in air at 120°C for 30 minutes, and then heated at 460°C for 45 minutes in a nitrogen atmosphere to form a laminate with a 10 μm thick polyimide film on a glass substrate. I got it. In order to eliminate the influence of water absorption by the polyimide film, the laminate was dried at 120°C for 10 minutes, and the amount of warpage of the laminate was measured in a nitrogen atmosphere at 25°C using a thin film stress measuring device (manufactured by KLA-Tencor). "FLX-2320-S"). Then, from the amount of warpage of the glass substrate before forming the polyimide film and the amount of warpage of the laminate, the internal stress generated between the glass substrate and the polyimide film was calculated using Stoney's equation. When the internal stress was 30 MPa or less, it was evaluated that "the internal stress was reduced." On the other hand, when the internal stress exceeded 30 MPa, it was evaluated that the internal stress could not be reduced.

[1% weight loss temperature (TD1)]
A polyimide film sampled from each laminate obtained in the Examples and Comparative Examples described later (more specifically, a polyimide film sampled so that the weight was 10 mg) was used as a measurement sample, and a simultaneous differential thermogravimetric measurement device ( Using the Hitachi High-Tech Science Co., Ltd. "TG/DTA7200"), the temperature was raised from 25°C to 650°C at 20°C/min in a nitrogen atmosphere, and the sample weight at the measurement temperature of 150°C was used as the standard. The measurement temperature at which the weight decreased by 1% by weight was defined as the 1% weight loss temperature (TD1).

[Film forming property]
(Film forming property on glass substrate)
Each polyamic acid composition prepared in the Examples and Comparative Examples described below was spun on a glass substrate manufactured by Corning Inc. (product name: Eagle XG, material: alkali-free glass, thickness: 0.7 mm, size: 100 mm x 100 mm). It was coated with a coater, heated in air at 120° C. for 30 minutes, and then heated at 460° C. for 45 minutes in a nitrogen atmosphere to obtain a laminate comprising a 10 μm thick polyimide film on a glass substrate. The resulting laminate was visually checked to see if there was any floating between the glass substrate and the polyimide film.

(Film forming property on a-Si layer)
After laminating an a-Si layer (thickness: 100 nm) on a Corning glass substrate (product name: Eagle XG, material: alkali-free glass, thickness: 0.7 mm, size: 100 mm x 100 mm), Each polyamic acid composition prepared in Examples and Comparative Examples described below was applied onto the layer using a spin coater. Next, the substrate coated with the polyamic acid composition was heated in air at 120°C for 30 minutes and then in a nitrogen atmosphere at 460°C for 45 minutes to form an a-Si layer and a 10 μm thick layer on the glass substrate. A laminate including polyimide films sequentially was obtained. The resulting laminate was visually checked to see if there was any floating between the a-Si layer and the polyimide film.

(Evaluation criteria for film formability)
When there was no lifting between the glass substrate and the polyimide film and between the a-Si layer and the polyimide film, it was evaluated that "occurrence of poor adhesion was suppressed and film formability was good". On the other hand, if there is floating between the glass substrate and the polyimide film, or between the a-Si layer and the polyimide film, "the occurrence of poor adhesion is not suppressed, and the film formability is not good." ”

[Peel strength]
In accordance with the ASTM D1876-01 standard, a cut with a width of 10 mm was made in the polyimide film of each laminate obtained in the Examples and Comparative Examples described below using a cutter knife, and the film was tested using a tensile tester ("Strograph VES1D" manufactured by Toyo Seiki Co., Ltd.). Peel strength is the average value of the peel strength when 50 mm of the polyimide film is peeled off from the glass substrate under the conditions of a temperature of 23°C and a humidity of 55% RH, a pulling speed of 50 mm/min, and a peeling angle of 90°. And so.

<Preparation of polyimide film>
Hereinafter, methods for producing polyimide films (laminates) of Examples and Comparative Examples will be described. In addition, below, compounds and reagents are described by the following abbreviations. Furthermore, the preparation of the polyamic acid composition used for producing the polyimide film was performed under a nitrogen atmosphere.
MPA: 3-methoxy-N,N-dimethylpropanamide NBP: 1-butyl-2-pyrrolidone BPDA: 3,3',4,4'-biphenyltetracarboxylic dianhydride BPAF: 9,9-bis(3 ,4-dicarboxyphenyl)fluorene dianhydride SFDA: spiro[11H-difuro[3,4-b:3',4'-i]xanthene-11,9'-[9H]fluorene]-1,3, 7,9-tetrone PDA: p-phenylenediamine BAFL: 9,9-bis(4-aminophenyl)fluorene PAM-E: 1,3-bis(3-aminopropyl)tetramethyldisiloxane ODA: 4,4' -Oxydianiline APS: 3-aminopropyltriethoxysilane APDE: 3-aminopropyldiethoxymethylsilane

[Example 1]
A 300 mL glass separable flask equipped with a stirrer equipped with a stainless steel stirring bar and a nitrogen inlet tube was charged with 85.0 g of MPA as an organic solvent for polymerization. Then, 4.037 g of PDA was added to the flask and dissolved while stirring the flask contents. Next, 0.171 g of BPAF and 10.792 g of BPDA were added to the flask contents, and then the flask contents were stirred for 6 hours in an atmosphere at a temperature of 25°C. Next, after adding 0.005 g of APS to the contents of the flask, the contents of the flask were further stirred for 6 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 (product name: Eagle After heating at 120° C. for 30 minutes in a nitrogen atmosphere, heating was performed at 460° C. for 45 minutes in a nitrogen atmosphere to obtain a laminate comprising a 10 μm thick polyimide film on a glass substrate (the laminate of Example 1).

[Examples 2 to 21 and Comparative Examples 1 to 7]
Except that the acid dianhydride used and its charging ratio, the diamine used and its charging ratio, the silane coupling agent used and its addition amount, and the type of solvent were as shown in Tables 1 and 2. By the same method as in Example 1, laminates of Examples 2 to 21 and Comparative Examples 1 to 7 were obtained, respectively. In addition, in Examples 2 to 4, 9 to 14, 17, 19, and 21, and Comparative Examples 1, 3, and 5 to 7, in which no silane coupling agent was used, all the acid dianhydride was placed in the flask. Thereafter, the contents of the flask were stirred for 6 hours in an atmosphere at a temperature of 25°C to obtain a polyamic acid composition. Furthermore, in all of Examples 2 to 21 and Comparative Examples 1 to 7, the total amount of acid dianhydride in preparing the polyamic acid composition was the same as in Example 1. Further, in all of Examples 2 to 21 and Comparative Examples 1 to 7, the total amount of diamine in preparing the polyamic acid composition was the same as in Example 1.

For Examples 1 to 21 and Comparative Examples 1 to 7, the acid dianhydride, diamine, silane coupling agent and solvent used, as well as internal stress, TD1, film formability and peel strength are shown in Tables 1 and 2. . In addition, in Tables 1 and 2, "-" in the column of acid dianhydride, diamine, and silane coupling agent means that the corresponding component was not used. Furthermore, in Tables 1 and 2, "-" in the peel strength column means that the peel strength was not measured.

Furthermore, in Tables 1 and 2, the numerical values in the "Acid dianhydride" column are the content (unit: mol %) of each acid dianhydride relative to the total amount of diamine used (100 mol %). Furthermore, in Tables 1 and 2, the numerical values in the "diamine" column are the content rates (unit: mol %) of each diamine relative to the total amount (100 mol %) of diamines used. Furthermore, in Tables 1 and 2, the numerical values in the "Silane coupling agent" column are the amount of the silane coupling agent added (unit: parts by weight) with respect to 100 parts by weight of polyamic acid. In addition, for both Examples 1 to 21 and Comparative Examples 1 to 7, the molar fraction of each residue of polyamic acid in the prepared polyamic acid composition was determined by the mole fraction of each monomer (diamine and (tetracarboxylic dianhydride).

The polyamic acids in the polyamic acid compositions used in Examples 1 to 21 had residues (1), BPDA residues, and PDA residues. The polyamic acid compositions used in Examples 1 to 21 contained specific organic solvents.

As shown in Tables 1 and 2, in Examples 1 to 21, the internal stress was 30 MPa or less. Therefore, in Examples 1 to 21, the internal stress was able to be reduced. In Examples 1 to 21, there was no lifting between the glass substrate and the polyimide film and between the a-Si layer and the polyimide film. Therefore, in Examples 1 to 21, occurrence of poor adhesion was suppressed and film formability was good.

The polyamic acids in the polyamic acid compositions used in Comparative Examples 1 to 7 had BPDA residues and PDA residues, but did not have residue (1). The polyamic acid compositions used in Comparative Examples 1 to 7 contained specific organic solvents.

As shown in Table 2, in Comparative Examples 1 to 6, there was some lifting between the glass substrate and the polyimide film and between the a-Si layer and the polyimide film. Therefore, in Comparative Examples 1 to 6, the occurrence of poor adhesion was not suppressed, and the film formability was poor. In Comparative Example 7, the internal stress exceeded 30 MPa. Therefore, in Comparative Example 7, the internal stress could not be reduced.

The above results indicate that, according to the present invention, it is possible to suppress the occurrence of poor adhesion and reduce internal stress while using a highly safe solvent.

Claims

A polyamic acid composition comprising a polyamic acid and an organic solvent,
The polyamic acid contains a residue containing a divalent organic group represented by the following chemical formula (1), a 3,3',4,4'-biphenyltetracarboxylic dianhydride residue, and p-phenylenediamine. has a residue,
The organic solvent is a polyamic acid composition containing one or more compounds selected from the group consisting of a compound represented by the following general formula (2) and a compound represented by the following general formula (3).

(In the general formula (2), R 1 , R 2 and R 3 each independently represent a hydrogen atom or a monovalent organic group having 1 or more carbon atoms, and among R 1 , R 2 and R 3 At least one of represents a monovalent organic group having 2 or more carbon atoms,
In the general formula (3), R 4 represents a monovalent organic group having 2 or more carbon atoms. )
The residue containing the divalent organic group represented by the chemical formula (1) is a tetravalent organic group represented by the following chemical formula (4), a tetravalent organic group represented by the following chemical formula (5), and the polyamic acid composition according to claim 1, which is one or more residues selected from the group consisting of divalent organic groups represented by the following chemical formula (6).
The content of the residue containing the divalent organic group represented by the chemical formula (1) is the same as that of all the tetracarboxylic dianhydride residues constituting the polyamic acid and all the diamine residues constituting the polyamic acid. The polyamic acid composition according to claim 1, wherein the polyamic acid composition is 15 mol% or less based on a total of 100 mol%.
The polyamic acid composition according to claim 1, wherein the organic solvent is 3-methoxy-N,N-dimethylpropanamide, 3-butoxy-N,N-dimethylpropanamide, or 1-butyl-2-pyrrolidone.
The polyamic acid composition according to claim 1, wherein the polyamic acid further has a 1,3-bis(3-aminopropyl)tetramethyldisiloxane residue.
The content of the 1,3-bis(3-aminopropyl)tetramethyldisiloxane residue is 0.1 mol% or more and 1.0 mol% or less with respect to the total amount of diamine residues constituting the polyamic acid. The polyamic acid composition according to claim 5.
The polyamic acid composition according to claim 1, further comprising a silane coupling agent.
A method for producing polyimide, which comprises heating the polyamic acid composition according to claim 1 to imidize the polyamic acid.
A method for producing a laminate having a support and a polyimide film, the method comprising:
Manufacturing a laminate by coating the polyamic acid composition according to claim 1 on a support to form a coating film containing the polyamic acid, and heating the coating film to imidize the polyamic acid. Method.
a step Sa of heating the polyamic acid composition according to claim 1 to imidize the polyamic acid;
A method for manufacturing an electronic device, comprising a step Sb of arranging an electronic element on the polyimide film obtained in the step Sa.