KR20230027146A - Polyamic acid, polyamic acid solution, polyimide, polyimide film, laminate, method for manufacturing laminate and electronic device - Google Patents

Abstract

A polyamic acid contains a structural unit represented by following formula (1). The polyamic acid solution contains a polyamic acid containing a structural unit represented by the following formula (1) and an organic solvent. A polyimide is an imide of a polyamic acid containing a structural unit represented by the following formula (1). The polyimide film contains an imide of a polyamic acid containing a structural unit represented by the following formula (1). The layered product has a support and a polyimide film containing an imide of polyamic acid containing a structural unit represented by the following formula (1). An electronic device has a polyimide film containing an imide of a polyamic acid containing a structural unit represented by the following formula (1), and an electronic element disposed on the polyimide film.

Description

Polyamic acid, polyamic acid solution, polyimide, polyimide film, laminate, method for manufacturing laminate and electronic device

The present invention relates to a polyamic acid, a polyamic acid solution, a polyimide, a polyimide film, a laminate, a method for manufacturing the laminate, and an electronic device. The present invention also relates to electronic device materials using polyimide, thin film transistor (TFT) substrates, flexible display substrates, color filters, printed materials, 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 currently using glass.

DESCRIPTION OF RELATED ART With the rapid progress of displays, such as a liquid crystal display, organic EL, and electronic paper, and electronic devices, such as a solar cell and a touch panel, thinning, weight reduction, and flexibility of devices are progressing. 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 high-temperature processes are required to form these electronic elements. Polyimide has sufficient heat resistance to be able to adapt to high-temperature processes, and its coefficient of thermal expansion (CTE) is close to that of glass substrates and electronic elements, so internal stress is unlikely to occur, making it suitable for substrate materials such as flexible displays.

In general, aromatic polyimide is colored yellowish brown due to intramolecular conjugation or formation of charge transfer (CT) complexes. Instead, conventional aromatic polyimide has been used. However, when light emitted from a display element is emitted through a substrate, such as a transparent display, a bottom emission type organic EL, or a liquid crystal display, or a sensor or camera module is used to make a smartphone or the like a full-surface display (notchless). In the case of disposing on the back side of a substrate, high optical properties (more specifically, transparency, etc.) are required of the substrate as well.

From such a background, a material having excellent transparency while having heat resistance equal to that of existing aromatic polyimides has been demanded.

In order to reduce the coloring of polyimide, a technique for suppressing the formation of a CT complex using an aliphatic monomer (Patent Documents 1 and 2) and a technique for increasing transparency using a monomer having a fluorine atom or a sulfur atom (Patent Documents 1 and 2) 3) is known.

Although the polyimides described in Patent Literatures 1 and 2 have high transparency and low CTE, they have a low thermal decomposition temperature because they have an aliphatic structure, and it is difficult to apply them to high-temperature processes when forming electronic elements.

Japanese Unexamined Patent Publication No. 2016-29177 Japanese Unexamined Patent Publication No. 2012-41530 Japanese Unexamined Patent Publication No. 2014-70139

Although the polyimide described in Patent Literature 3 has high transparency, since it contains fluorine atoms, a decrease in surface free energy reduces adhesion to a barrier film formed on a polyimide substrate or an electronic element, and in a high-temperature process. It became clear by the present inventor's examination that peeling may occur at the interface with polyimide. Further, the polyimide described in Patent Literature 3 has a possibility of causing poor adhesion between the polyimide and the barrier film or electronic element due to fluorine-based decomposition gas generated in a high-temperature process.

The present invention has been made in view of the above situation, and has excellent transparency, high heat resistance, and a polyimide capable of securing adhesion to an inorganic material (more specifically, a glass substrate, a barrier film, etc.) in a high-temperature process, and its It aims to provide a polyamic acid as a precursor. Another object is to provide a product or member manufactured using the polyimide and polyamic acid and requiring heat resistance and transparency. In particular, it is an object of the present invention to provide a product or member in which the polyimide film of the present invention is formed on the surface of an inorganic material such as glass, metal, metal oxide, and single crystal silicon.

As a result of intensive studies, the present inventors have found that a polyimide obtained by imidizing a specific polyamic acid having a fluorene skeleton (fluorene structure) has excellent transparency, high heat resistance, and can be used as a glass substrate or barrier film in a high-temperature process. It was found that adhesion to the surface could be secured, and the present invention was completed.

The polyamic acid according to the present invention includes a structural unit represented by the following formula (1).

The polyamic acid according to one embodiment of the present invention further includes a structural unit represented by the following general formula (2).

In the general formula (2), X represents a tetravalent organic group different from the tetracarboxylic dianhydride residue in the general formula (1).

In one embodiment of the polyamic acid according to the present invention, X in the general formula (2) is composed of a tetravalent organic group represented by the following formula (3) and a tetravalent organic group represented by the following formula (4) It is one or more types selected from the group.

In one embodiment of the polyamic acid according to the present invention, the content of the structural unit represented by the above formula (1) is 1 mol% or more with respect to all structural units.

In one embodiment of the polyamic acid according to the present invention, the ratio of the amount of substances obtained by dividing the total amount of tetracarboxylic acid dianhydride residues by the total amount of diamine residues is 0.900 or more and less than 1.100.

The polyamic acid solution according to the present invention contains the polyamic acid according to the present invention and an organic solvent.

The polyimide according to the present invention is an imide of a polyamic acid according to the present invention.

It is preferable that the 1% weight loss temperature of the polyimide concerning this invention is 500 degreeC or more. Moreover, it is preferable that the glass transition temperature of the polyimide concerning this invention is 400 degreeC or more.

The polyimide film according to the present invention includes the polyimide according to the present invention.

It is preferable that the yellowness of the polyimide film concerning this invention is 25 or less. Moreover, it is preferable that the haze of the polyimide film concerning this invention is less than 1.0 %.

A laminate according to the present invention has a support and a polyimide film according to the present invention.

In the method for producing a laminate according to the present invention, a coating film containing the polyamic acid is formed by applying the polyamic acid solution according to the present invention onto a support, and the coating film is heated to dissolve the polyamic acid. to degenerate

An electronic device according to the present invention includes a polyimide film according to the present invention and an electronic element disposed on the polyimide film.

The polyimide produced using the polyamic acid according to the present invention is excellent in transparency and heat resistance, and can secure adhesion to inorganic materials during a high-temperature process. Therefore, the polyimide produced using the polyamic acid according to the present invention is suitable as a material for electronic devices that require transparency and heat resistance and are manufactured through a high-temperature process.

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

First, terms used in this specification will be described. A "structural unit" refers to a repeating unit constituting a polymer. "Polyamic acid" is a polymer containing a structural unit represented by the following general formula (5) (hereinafter sometimes referred to as "structural unit (5)").

In general formula (5), A represents a tetracarboxylic dianhydride residue (a tetravalent organic group derived from tetracarboxylic dianhydride), and B represents a diamine residue (a divalent organic group derived from diamine). .

The content of the structural unit (5) relative 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, more preferably It is 70 mol% or more and 100 mol% or less, More preferably, it is 80 mol% or more and 100 mol% or less, Even more preferably, it is 90 mol% or more and 100 mol% or less, 100 mol% may be sufficient.

"1% weight reduction temperature" is a measurement temperature when the weight of polyimide at a measurement temperature of 150°C is reduced by 1% by weight relative to the reference weight (100% by weight). The measuring method of 1% weight loss temperature is the same method as that of the Example mentioned later, or a method similar to it.

Hereinafter, "system" is appended to the name of a compound to collectively refer to a compound and its derivatives in some cases. When a polymer name is indicated by attaching "system" to the end of the compound name, it means that the repeating unit of the polymer is derived from a compound or a derivative thereof. In addition, tetracarboxylic dianhydride may be described as "acid dianhydride".

The polyamic acid according to the present embodiment includes a structural unit represented by the following formula (1) (hereinafter sometimes referred to as “structural unit (1)”).

Structural unit (1) has a partial structure derived from 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride (hereinafter sometimes referred to as "BPAF"), and 4-aminophenyl-4- It has a partial structure derived from aminobenzoate (hereinafter sometimes referred to as "4-BAAB"). That is, structural unit (1) has a BPAF residue as A in the above-mentioned general formula (5), and also has a 4-BAAB residue as B in general formula (5).

Since 4-BAAB has a rigid structure, it is suitable as a raw material (monomer) of polyimide having a high glass transition temperature (excellent in heat resistance). In addition, 4-BAAB having a rigid structure is also suitable as a raw material (monomer) of polyimide having high mechanical strength while suppressing generation of internal stress. Since BPAF has a bulky fluorene structure, it is suitable as a raw material (monomer) of polyimide having excellent heat resistance and transparency.

When synthesizing the polyamic acid according to the present embodiment, a diamine other than 4-BAAB may be used as a monomer within a range not impairing its performance. Examples of diamines other than 4-BAAB include 1,4-diaminocyclohexane, p-phenylenediamine, m-phenylenediamine, 4,4'-oxydianiline, and 3,4'-oxydianiline. , 2,2'-bis (trifluoromethyl) -4,4'-diaminodiphenyl ether, 4,4'-diaminobenzanilide, N, N'-bis (4-aminophenyl) terephthalamide, 4,4'-diaminodiphenylsulfone, m-tolidine, o-tolidine, 4,4'-bis(aminophenoxy)biphenyl, 2-(4-aminophenyl)-6-aminobenzoxazole , 3,5-diaminobenzoic acid, 4,4'-diamino-3,3'dihydroxybiphenyl, 4,4'-methylenebis(cyclohexanamine), 1,3-bis(3-aminopropyl ) tetramethyldisiloxane and derivatives thereof, and these may be used alone or in combination of two or more. From the viewpoint of improving heat resistance, improving mechanical strength, and reducing internal stress, as diamines other than 4-BAAB, at least one selected from the group consisting of p-phenylenediamine and 4,4'-diaminobenzanilide is preferable, p-phenylenediamine is more preferred. From the viewpoints of improving transparency, improving heat resistance, improving mechanical strength, and reducing internal stress, the content of 4-BAAB residues relative to all diamine residues constituting the polyamic acid is preferably 50 mol% or more, and more preferably 70 mol% or more. It is preferable, and it is more preferable that it is 80 mol% or more, and it does not matter even if it is 100 mol%.

The polyamic acid according to the present embodiment is a structural unit represented by the following general formula (2) in addition to the structural unit (1) from the viewpoint of improving transparency and reducing internal stress (hereinafter referred to as “structural unit (2)”). It is preferable to include). When the polyamic acid according to the present embodiment includes the structural unit (1) and the structural unit (2), the arrangement of the structural unit (1) and the structural unit (2) in the polyamic acid may be random, or a block may be continued

In general formula (2), X represents a tetravalent organic group different from the tetracarboxylic dianhydride residue in general formula (1). X may be 1 type or 2 or more types may be sufficient as it.

Preferable examples of the acid dianhydride (an acid dianhydride giving X in general formula (2)) for forming the structural unit (2) include pyromellitic dianhydride (hereinafter sometimes referred to as "PMDA"), 3,3'4,4'-biphenyltetracarboxylic dianhydride (hereinafter sometimes referred to as "BPDA"), p-phenylene bis(trimellitate anhydride), 2,3,6,7 -Naphthalenetetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 2,2',3,3'-biphenyltetracarboxylic dianhydride, 3,3',4 ,4'-benzophenonetetracarboxylic dianhydride, 4,4'-oxydiphthalic anhydride, 4,4'-(hexafluoroisopropylidene)diphthalic anhydride, dicyclohexyl-3,3',4 ,4'-tetracarboxylic dianhydride, 1,2,4,5-cyclohexanetetracarboxylic dianhydride, cyclobutanetetracarboxylic dianhydride, 2'-oxodispiro[bicyclo[2.2.1 ]heptane-2,1''-cycloheptane-3,2''-bicyclo[2.2.1]heptane]-5,5'-6,6'-tetracarboxylic dianhydride and derivatives thereof; may be used alone or in combination of two or more.

From the viewpoint of improving heat resistance, improving mechanical strength, and reducing internal stress, as the acid dianhydride giving X in the general formula (2), at least one selected from the group consisting of PMDA and BPDA is preferable, and BPDA is more preferable. . When PMDA is used as the acid dianhydride, X in the general formula (2) is a tetravalent organic group represented by the following general formula (3). In the case of using BPDA as the acid dianhydride, X in the general formula (2) is a tetravalent organic group represented by the following general formula (4).

When the polyamic acid according to the present embodiment contains at least one of a PMDA residue and a BPDA residue, from the viewpoints of improving transparency, improving heat resistance, improving mechanical strength, and reducing internal stress, all acid dianhydride residues constituting the polyamic acid The total content of BPAF residue, PMDA residue and BPDA residue is preferably 60 mol% or more, more preferably 70 mol% or more, still more preferably 80 mol% or more, and may be 100 mol%.

Particularly, the BPAF residue has a bulky structure derived from a fluorene structure, and contributes to improvement in heat resistance, improvement in transparency, and reduction in yellowness, while containing only a small amount can suppress polyimide crystallization. Therefore, the content of the structural unit (1) containing the BPAF residue is preferably 1 mol% or more, more preferably 3 mol% or more, based on all structural units of the polyamic acid according to the present embodiment. It is more preferable that it is mol% or more, and it is still more preferable that it is 10 mol% or more. Further, from the viewpoint of reducing internal stress, the content of the structural unit (1) containing a BPAF residue is preferably 50 mol% or less, and 40 mol% or less, based on all structural units of the polyamic acid according to the present embodiment. It is more preferable, and it is still more preferable that it is 30 mol% or less.

By setting the content of the structural unit (1) within the above range, a polyimide having high transparency, low yellowness and high heat resistance can be obtained while suppressing generation of internal stress.

When the polyamic acid according to the present embodiment includes the structural unit (1) and the structural unit (2), the overall structure constituting the polyamic acid from the viewpoints of improving transparency, improving heat resistance, improving mechanical strength, and reducing internal stress The total content of structural unit (1) and structural unit (2) relative to the unit is preferably 50 mol% or more, more preferably 70 mol% or more, still more preferably 80 mol% or more, even if it is 100 mol% Does not matter.

In order to obtain a polyimide that is more excellent in transparency and heat resistance and can more reliably secure adhesion to an inorganic material during a high-temperature process, the polyamic acid according to the present embodiment preferably satisfies the following condition 1, It is more preferable to satisfy the following condition 2, more preferably to satisfy the following condition 3, and even more preferably to satisfy the following condition 4.

Condition 1: the polyamic acid contains at least one of PMDA residues and BPDA residues, and the total content of BPAF residues, PMDA residues, and BPDA residues relative to all tetracarboxylic dianhydride residues constituting the polyamic acid is 100 is mol%.

Condition 2: The condition 1 above is satisfied, and the content of 4-BAAB residues relative to all diamine residues constituting the polyamic acid is 50 mol% or more and 100 mol% or less.

Condition 3: The condition 1 above is satisfied, and the content of the structural unit (1) is 1 mol% or more and 30 mol% or less with respect to all the structural units of the polyamic acid.

Condition 4: The condition 2 above is satisfied, and the content of the structural unit (1) is 1 mol% or more and 30 mol% or less with respect to all the structural units of the polyamic acid.

From the viewpoint of suppressing the decrease in transparency due to the remaining unreacted monomer at the time of polyimide formation, the ratio (molar ratio) of the total amount of tetracarboxylic dianhydride residues divided by the total amount of diamine residues is 0.900 or more and less than 1.100. It is preferably 0.950 or more and 1.080 or less, more preferably 1.000 or more and 1.050 or less. By adjusting the material amount ratio within the above range, a polyimide excellent in transparency is obtained.

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

In the case of synthesizing polyamic acid using diamine and tetracarboxylic dianhydride, the amount of substance of diamine (substance amount of each diamine when using plural types of diamine) and the amount of substance of tetracarboxylic dianhydride (tetracarboxylic dianhydride) When using multiple types of acid dianhydride, desired polyamic acid (polymer of diamine and tetracarboxylic dianhydride) can be obtained by adjusting the amount of substance of each tetracarboxylic dianhydride. The mass ratio (molar ratio) of each residue in the polyamic acid corresponds to, for example, the mass ratio of each monomer (diamine and tetracarboxylic dianhydride) used in the synthesis of the polyamic acid. Further, by blending two types of polyamic acid, a polyamic acid containing plural types of tetracarboxylic dianhydride residues and plural 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, are not particularly limited, but are, for example, in the range of 20°C or more and 150°C or less. The reaction time of the synthesis reaction of polyamic acid is in the range of, for example, 10 minutes or more and 30 hours or less.

The organic solvent used for synthesis of the polyamic acid is preferably a solvent capable of dissolving the tetracarboxylic dianhydride and diamine used, and more preferably a solvent capable of dissolving the resulting polyamic acid. Examples of organic solvents used for synthesis of polyamic acid include urea solvents such as tetramethylurea and N,N-dimethylethylurea; sulfoxide-based solvents such as dimethyl sulfoxide; sulfone solvents such as diphenyl sulfone and tetramethyl sulfone; N,N-dimethylacetamide (DMAC), N,N-dimethylformamide (DMF), N,N-diethylacetamide, N-methyl-2-pyrrolidone (NMP), hexamethylphosphate triamide, etc. of amide-based solvent; ester solvents such as γ-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; 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; can Although these solvents are usually used individually, you may use them combining 2 or more types suitably as needed. In order to increase the solubility and reactivity of polyamic acid, as an organic solvent used in the synthesis reaction of polyamic acid, at least one solvent selected from the group consisting of amide solvents, ketone solvents, ester solvents and ether solvents is used. It is preferable, and an amide solvent (more specifically, DMF, DMAC, NMP, etc.) is more preferable. In addition, it is preferable to carry out the synthesis reaction of polyamic acid under an inert gas atmosphere such as argon or nitrogen.

The weight average molecular weight of the polyamic acid according to the present embodiment varies depending on the application, 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, and is in the range of 30,000 or more and 200,000 or less. It is more preferable to be When the weight average molecular weight is 10,000 or more, it becomes easy to use polyamic acid or polyimide obtained using polyamic acid as a coating film or a polyimide film (film). On the other hand, if the weight average molecular weight is 1,000,000 or less, sufficient solubility in solvents is exhibited, so that a coated film or polyimide film having a smooth surface and uniform thickness can be obtained using a polyamide acid solution described later. The weight average molecular weight used in this specification refers to the value in terms of polyethylene oxide measured using gel permeation chromatography (GPC).

The polyimide according to the present embodiment is an imide of the polyamic acid according to the present embodiment described above. The polyimide according to the present embodiment can be obtained by a known method, and the production method thereof is not particularly limited. Hereinafter, an example of a method of imidizing the polyamic acid to obtain the polyimide according to the present embodiment will be described. Imidation is performed by dehydration ring closure of polyamic acid. This dehydration ring closure can be performed by an azeotropic method using an azeotrope solvent, a thermal method, or a chemical method. In addition, imidation from polyamic acid to polyimide can take an arbitrary ratio of 1% or more and 100% or less. That is, you may synthesize|combine the polyamic acid which was partially imidized. In particular, when imidation is performed by heating, the ring closure reaction from polyamic acid to polyimide and the hydrolysis of polyamic acid proceed simultaneously, and the molecular weight of polyimide is lower than that of polyamic acid. , there is a possibility of coloring due to oxidation of diamine generated by hydrolysis, etc., therefore, before forming the polyimide film described later, it is recommended to imidize a part of the polyamic acid in the polyamic acid solution in advance to improve transparency and mechanical properties. It is desirable from the point of view of improvement. In this specification, a polyamic acid partially imidated is sometimes described as "polyamic acid".

The polyamic acid solution according to the present embodiment contains the polyamic acid according to the present embodiment described above and an organic solvent. Here, examples of the organic solvent contained in the polyamic acid solution include organic solvents exemplified as organic solvents that can be used for the synthesis reaction of the polyamic acid, and amide solvents, ketone solvents, ester solvents, and ether solvents One or more solvents selected from the group consisting of are preferable, and amide solvents (more specifically, DMF, DMAC, NMP, etc.) are more preferable. When polyamic acid is obtained by the method described above, the reaction solution (the solution after the reaction) itself may be the polyamic acid solution according to the present embodiment. Alternatively, the polyamic acid solution according to the present embodiment may be prepared by dissolving the solid polyamic acid obtained by removing the solvent from the reaction solution in a solvent. The content of the polyamic acid in the polyamic acid solution 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 solution.

The dehydration ring closure of the polyamic acid may be performed by heating the polyamic acid. The method of heating the polyamic acid is not particularly limited. For example, the polyamic acid solution according to the present embodiment described above is applied onto a support such as a glass substrate, a metal plate, or a PET film (polyethylene terephthalate film). After that, the polyamic acid may be heat-treated within a temperature range of 40°C or more and 500°C or less. According to this method, according to the present embodiment having a support and a polyimide film (specifically, a polyimide film containing an imide of polyamic acid according to the present embodiment) disposed on the support. A laminate is obtained. Alternatively, the polyamic acid solution may be directly put into a container subjected to release treatment such as coating with a fluorine-based resin, and the polyamic acid solution may be heated and dried under reduced pressure to dehydrate the polyamic acid. Polyimide can be obtained by dehydration ring closure of polyamic acid by these methods. The heating time of each of the above treatments varies depending on the treatment amount and heating temperature of the polyamic acid solution subjected to dehydration ring closure, but in general, it is preferable to set the treatment temperature within the range of 1 minute or more and 300 minutes or less after the treatment temperature reaches the maximum temperature. desirable. In addition, in order to shorten the heating time or develop characteristics, an imidation agent and/or a dehydration catalyst are added to a polyamic acid solution, and the polyamic acid solution to which the imidation agent and/or a dehydration catalyst is added is heated by the above method. You can imidize it.

Although it does not specifically limit as said imidation agent, A tertiary amine can be used. As the tertiary amine, a heterocyclic tertiary amine is preferable. Preferable specific examples of the heterocyclic tertiary amine include pyridine, picoline, quinoline, isoquinoline, and 1,2-dimethylimidazole. Preferable examples of the dehydration catalyst include acetic anhydride, propionic anhydride, n-butyric anhydride, benzoic anhydride, and trifluoroacetic anhydride.

The addition amount of the imidizing agent is preferably 0.5 times the molar equivalent or more and 5.0 times the molar equivalent or less, more preferably 0.7 times the molar equivalent or more and 2.5 times the molar equivalent or less, and 0.8 times the molar equivalent or more and 2.0 times or less with respect to the amide group of the polyamic acid. A molar equivalent or less is more preferred. The addition amount of the dehydration catalyst is preferably 0.5-fold molar equivalent or more and 10.0-fold molar equivalent or less, more preferably 0.7-fold molar equivalent or more and 5.0-fold molar equivalent or less, and 0.8-fold molar equivalent or more with respect to the amide group of the polyamic acid, 3.0 A pear molar equivalent or less is more preferred. In addition, in this specification, "the amide group of a polyamic acid" refers to the amide group produced|generated by the polymerization reaction of diamine and tetracarboxylic dianhydride. When adding an imidation agent and/or a dehydration catalyst to the polyamic acid solution, it may be added directly without dissolving in an organic solvent, or may be added dissolved in an organic solvent. In the method of adding directly without dissolving in an organic solvent, the reaction proceeds rapidly before the imidation agent and/or the dehydration catalyst diffuse, and a gel may be formed. Therefore, it is more preferable to add a solution obtained by dissolving the imidation agent and/or the dehydration catalyst in an organic solvent to the polyamic acid solution.

The polyimide film according to the present embodiment (specifically, the polyimide film containing an imide of polyamic acid according to the present embodiment) is colorless and transparent, has a low yellowness, and can withstand the TFT fabrication process. Since it has a certain glass transition temperature (heat resistance), it is suitable for a transparent substrate material of a flexible display. The content of polyimide in the polyimide film according to the present embodiment (specifically, the imidide of polyamic acid according to the present embodiment) is, for example, 70% by weight or more with respect to the total amount of the polyimide film, It is preferably 80% by weight or more, more preferably 90% by weight or more, and may be 100% by weight. Examples of components other than the polyimide in the polyimide film include additives described later (more specifically, nanosilica particles and the like).

An electronic device according to this embodiment includes the polyimide film according to this embodiment and an electronic element disposed on the polyimide film. In the case of manufacturing the electronic device according to the present embodiment for a flexible display, first, a polyimide film is formed on an inorganic substrate such as glass as a support. And an electronic device is formed on a support body by arrange|positioning (forming) electronic elements, such as TFT, on a polyimide film. The process of forming a TFT is generally carried out in a wide temperature range of 150°C or more and 650°C or less. In some cases, a-Si or the like is crystallized by a laser or the like.

At this time, when the thermal decomposition temperature of the polyimide film is low, outgas is generated during the formation of the electronic element and adheres to the oven as a sublimated product, causing contamination in the furnace, or an inorganic film formed on the polyimide film (a barrier film described later). etc.) or electronic elements may peel off, so the 1% weight loss temperature of polyimide is preferably 500°C or higher. The higher the upper limit of the 1% weight loss temperature of polyimide, the better, but it is, for example, 520°C. The 1% weight reduction temperature can be adjusted by, for example, changing the content of residues having a rigid structure (more specifically, 4-BAAB residues, BPDA residues, etc.). More specifically, 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 before forming the TFT. When the heat resistance of the polyimide is low, the polyimide and the inorganic film may separate from each other due to volatile components such as decomposition gas of the polyimide in a high-temperature process after the inorganic film is laminated. For this reason, in addition to the 1% weight reduction temperature of polyimide being 500°C or higher, it is preferable that the weight reduction rate when isothermally maintaining the polyimide at a temperature within the range of 400°C or higher and 450°C or lower is less than 1%.

Further, as verified by the present inventors, a clear difference was observed in the adhesion between the polyimide film and the inorganic film between the polyimide film containing fluorine atoms and the polyimide film not containing fluorine atoms. This is considered to be due to the remarkably low surface free energy of the polyimide film containing fluorine atoms. Therefore, in order to suppress separation between the inorganic film and the polyimide film in a high-temperature process, a polyimide having a small content of fluorine atoms is preferable, and a polyimide derived from a monomer containing no fluorine atoms is more preferable.

In the case where the glass transition temperature (Tg) of polyimide is significantly lower than the process temperature, misalignment or the like may occur during electronic element formation. Therefore, the Tg of polyimide is preferably 300°C or higher, and 350°C It is more preferable that it is above, and it is more preferable that it is 400 degreeC or more. The higher the upper limit of the Tg of polyimide, the better, but is, for example, 450°C. Also, 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. When the internal stress of a laminate of a glass substrate or electronic device used as a support and a polyimide film is high, the laminate containing the polyimide film expands in the high-temperature TFT formation step and then contracts when cooled to room temperature, resulting in the loss of the glass substrate. Problems such as warpage, breakage, and peeling of the polyimide film from the glass substrate occur. Therefore, the internal stress generated in the laminate of the polyimide film and the glass substrate is preferably 30 MPa or less, more preferably 25 MPa or less, and still more preferably 20 MPa or less.

The polyimide according to this embodiment can be suitably used as a material for display substrates such as TFT substrates and touch panel substrates. When polyimide is used for the above applications, a method of forming an electronic device (specifically, an electronic device in which electronic elements are formed on a polyimide film) on a support as described above, and then peeling the polyimide film from the support is adopted. often do Moreover, as a material of a support body, an alkali-free glass is used suitably. Hereinafter, an example of the manufacturing method of the laminated body of a polyimide film and a support body is demonstrated in detail.

First, the polyamic acid solution according to the present embodiment is applied onto a support to form a coating film-containing laminate comprising a coating film containing polyamic acid and a support. Next, the coating film-containing laminate is heated under conditions of, for example, a temperature of 40°C or higher and 200°C or lower. The heating time at this time is 3 minutes or more and 120 minutes or less, for example. Further, for example, a multi-step heating step may be provided, such as heating the coated film-containing laminate at a temperature of 50°C for 30 minutes and then heating at a temperature of 100°C for 30 minutes. Next, in order to advance imidation of the polyamic acid in the coating film, the coating film-containing laminate is heated under conditions of, for example, a maximum temperature of 200°C or more and 500°C or less. 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 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. Further, the maximum temperature is preferably in the range of 250°C or more and 450°C or less. When the maximum temperature is 250°C or higher, imidization proceeds sufficiently, and when the maximum temperature is 450°C or lower, thermal deterioration and coloring of the polyimide can be suppressed. Further, it may be held at any temperature for any length of time until reaching the maximum temperature. Although the imidation reaction can be performed under air, under reduced pressure, or in an inert gas such as nitrogen, in order to develop higher transparency, it is preferable to carry out under reduced pressure or in an inert gas such as nitrogen. In addition, as a heating apparatus, well-known apparatuses, such as a hot-air oven, an infrared oven, a vacuum oven, an inert oven, and a hot plate, can be used. Through these steps, the polyamic acid in the coated film is imidized, and a laminate of the support and the polyimide film (imide compound of polyamic acid) can be obtained. In addition, in order to shorten the heating time or develop characteristics, an imidation agent or a dehydration catalyst may be added to the polyamic acid solution, and the solution may be heated by the above method to imidize.

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

If the interface between the polyimide film and the support (for example, glass substrate) is lifted, the polyimide film may be peeled off during the formation of the electronic element, or the yield may be lowered when the polyimide film is peeled after the electronic element is formed. there is In addition, "floating" refers to a material layer different from the polyimide film (more specifically, a glass substrate, a barrier film, etc. ) refers to a state in which poor adhesion has occurred between As specific "floating", a state in which the polyimide film was lifted from the glass substrate, a state in which a part of the polyimide film was destroyed and interlayer separation occurred between the polyimide film and another material layer, a state in which the barrier film was lifted from the polyimide film, etc. can be heard For example, a polyimide formed of BPDA and 4-BAAB has highly oriented molecular chains densely packed, and the degassing of subcomponents generated during imidation is poor, and lifting is likely to occur. The present inventor's study revealed that lifting can be prevented by introducing a bulky structure in the middle of the molecular chain or at the end thereof. In addition, the present inventors' studies have revealed that both good gas release and high Tg can be achieved by using 4-BAAB together with BPAF, which has a bulky structure with a low degree of rotational freedom. According to the polyamic acid of this embodiment, since it has structural unit (1) containing a BPAF residue and a 4-BAAB residue, generation|occurrence|production of exfoliation can be suppressed. Therefore, according to the polyamic acid according to this embodiment, adhesion to the inorganic material during a high-temperature process can be ensured.

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 a use requiring high transparency, the total light transmittance of the polyimide film is preferably 75% or more, and more preferably 80% or more. Further, when the polyimide film is used for applications requiring high transparency, the haze of the polyimide film is preferably 1.5% or less, more preferably 1.2% or less, still 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 absorb short wavelength light, and the film itself is often colored yellow. In order to use the polyimide film for applications requiring high transparency, the yellowness index (YI) of the polyimide film is preferably 25 or less, more preferably 20 or less, still more preferably 15 or less, and may be 0. YI can be measured according to JIS K7373-2006. The polyimide film imparted with transparency in this way is suitable for a transparent substrate for use as a substitute for glass or a substrate on which a sensor or camera module is provided on the back surface.

In addition, there are two types of light extraction methods of flexible displays: a top emission method in which light is extracted from the TFT element side and a bottom emission method in which light is extracted from the back side of the TFT element. In the top emission method, since light is not blocked to the TFT element, it is easy to increase the aperture ratio, and there is a feature that high-definition image quality is obtained. There is a feature that Since the aperture ratio can be improved even in the bottom emission method if the TFT element is transparent, the bottom emission method, which is easy to manufacture, tends to be adopted for large-sized 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 light extraction methods described above.

In addition, in a batch-type device manufacturing process in which a polyamic acid solution is applied onto a support such as a glass substrate, heated to imidize, and an electronic element or the like is formed, the polyimide film is peeled off. It is more preferable that the adhesion between the mid films is excellent. Adhesion as used herein means adhesion strength. In the production process of forming the electronic element or the like on the polyimide film on the support and then peeling the polyimide film on which the electronic element or the like is formed from the support, when the adhesion between the polyimide film and the support is excellent, the electronic element or the like can be formed more accurately. It can be formed or mounted. In the manufacturing process of arranging an electronic element or the like on a support through a polyimide film, the higher the peel strength between the support and the polyimide film, the better, from the viewpoint of productivity improvement. Specifically, the peel strength is preferably 0.05 N/cm or more, and more preferably 0.1 N/cm or more.

In the manufacturing process as described above, when peeling the polyimide film from the laminate of the support and the polyimide film, the polyimide film is often peeled from the support by laser irradiation. In this case, since it is necessary to make the polyimide film absorb the laser beam, the cutoff wavelength of the polyimide film is required to be longer than the wavelength of the laser beam used for peeling. Since a XeCl excimer laser with a wavelength of 308 nm is often used for laser ablation, the cutoff wavelength of the polyimide film is preferably 312 nm or more, and more preferably 330 nm or more. On the other hand, since the polyimide film tends to be colored yellow when the cutoff wavelength is a long wavelength, the cutoff wavelength of the polyimide film is preferably 390 nm or less. From the viewpoint of achieving both transparency (low yellowness) and laser ablation processability, 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|permeability measured by the ultraviolet-visible spectrophotometer becomes 0.1 % or less.

The polyamic acid and polyimide according to the present embodiment may be used as they are in a coating or molding process for producing products or members, but may be used as materials for further processing such as coating on a molded article molded into a film. may be For use in the coating or molding process, polyamic acid or polyimide is dissolved or dispersed in an organic solvent as necessary, and a photocurable component, thermosetting component, non-polymerizable binder resin and other components are blended as necessary. Thus, a polyamic acid composition or a polyimide resin composition may be prepared.

In order to impart processing characteristics and various functionalities to the polyamic acid and polyimide according to the present embodiment, various organic or inorganic low-molecular compounds or high-molecular compounds may be blended as additives. As additives, dyes, surfactants, leveling agents, plasticizers, silicones, fine particles, sensitizers and the like can be used, for example. The fine particles include organic fine particles made of polystyrene, polytetrafluoroethylene, etc., inorganic fine particles made of colloidal silica, carbon, layered silicate, etc., and they may have a porous structure or a hollow structure. In addition, the function and shape of the fine particles are not particularly limited, and may be, for example, pigments, fillers, or fibrous particles.

In order to improve the heat resistance while maintaining the transparency of the polyimide film, nanosilica particles may be used as the additive, and polyamic acid and nanosilica particles may be composited. 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, still more preferably 50 nm or less, and may be 30 nm or less. On the other hand, from the viewpoint of securing the dispersibility to polyamic acid, 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 compounding the polyamic acid and the nanosilica particles, a known method can be used. For example, a method of using an organosilica sol obtained by dispersing nanosilica particles in an organic solvent is exemplified. As a method of compounding polyamic acid and nanosilica particles using organosilica sol, after synthesizing polyamic acid, the synthesized polyamic acid and organosilica sol may be mixed. In order to disperse in the inside, it is preferable to synthesize the polyamic acid in organosilica sol.

In addition, in order to increase the interaction with polyamic acid, the surface of the nano-silica particles may be treated with a surface treatment agent. As a surface treatment agent, known things, such as a silane coupling agent, can be used. As a silane coupling agent, the alkoxysilane compound etc. which have an amino group or a glycidyl group etc. as a functional group are widely known, and can select suitably. In order to further enhance the interaction with the polyamic acid, an amino group-containing alkoxysilane is preferable as the silane coupling agent. Examples of the amino group-containing alkoxysilane include 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropylmethyldimethoxysilane, 3-aminopropylmethyldiethoxysilane, and 3-(2-aminoethyl). ) Aminopropyltrimethoxysilane, 3-phenylaminopropyltrimethoxysilane, 2-aminophenyltrimethoxysilane and 3-aminophenyltrimethoxysilane, etc. Preference is given to using propyltriethoxysilane. As a method of surface treatment of nanosilica particles, a method of stirring a mixture obtained by adding a silane coupling agent to a dispersion (organosilica sol) at an atmospheric temperature of 20°C or higher and 80°C or lower is exemplified. The stirring time at this time is 1 hour or more and 10 hours or less, for example. At this time, you may add a catalyst etc. which promote reaction.

The polyamic acid composition containing nanosilica particles in which polyamic acid and nanosilica particles are combined preferably contains nanosilica particles in an amount of 1 part by weight or more and 30 parts by weight or less with respect to 100 parts by weight of polyamic acid, It is more preferable to include within the range of 1 part by weight or more and 20 parts by weight or less. When 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. Adverse effects on mechanical properties and transparency can be suppressed.

Imidazoles may be added to the polyamic acid according to the present embodiment as an additive for imparting the functionality described above. In this specification, imidazole refers to a compound having a 1,3-diazole ring (1,3-diazole ring structure). The imidazoles added to the polyamic acid according to the present embodiment are not particularly limited, and examples thereof include 1H-imidazole, 2-methylimidazole, 2-undecylimidazole, and 2-heptadecyl. Imidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-methyl Midazole, 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 preferable.

The content of the 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, and still more preferably 0.015 mol or more and 0.050 mol or less with respect to 1 mol of the amide group of the polyamic acid. By containing 0.005 mol or more of imidazoles, the film strength and transparency of polyimide can be improved, and by making the content of imidazoles 0.1 mol or less, Tg and heat resistance can be improved while maintaining the storage stability of polyamic acid. can To explain the improvement in transparency, it is known that a polymerization solvent such as NMP forms a complex with a carboxy group of polyamic acid by hydrogen bonding. B. Decomposition may cause discoloration. When imidazoles are added, imidazoles coordinate with the carboxyl group of polyamic acid to promote imidation, making it difficult for NMP and the like to remain in the polyimide film, and at the same time, polyamic acid in the thermal imidation process. Since decomposition is also suppressed, it is thought that transparency improves.

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

In addition, the polyamic acid solution according to the present embodiment may contain a silane coupling agent in order to develop appropriate adhesion to the support. A known type of silane coupling agent can be used without particular limitation, but a compound containing an amino group is particularly preferred from the viewpoint of reactivity with polyamic acid.

The blending ratio of the silane coupling agent to 100 parts by weight of polyamic acid is preferably 0.01 part by weight or more and 0.50 part by weight or less, more preferably 0.01 part by weight or more and 0.10 part by weight or less, and 0.01 part by weight or more and 0.05 part by weight or less. more preferable When the blending ratio of the silane coupling agent is 0.01 part by weight or more, the peeling inhibitory effect on the support is sufficiently exhibited, and when the blending ratio of the silane coupling agent is 0.50 part by weight or less, the molecular weight decrease of the polyamic acid is suppressed. The embrittlement of the mid film can be suppressed.

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

In addition to heat resistance, low thermal expansion, and transparency, the polyimide film according to the present embodiment has low internal stress generated when a laminate is formed with a glass substrate, and adhesion to inorganic materials can be secured during a high-temperature process. , it is preferred to be used in fields and products in which these properties are effective. For example, the polyimide film according to the present embodiment is used in image display devices such as liquid crystal display devices, organic EL and electronic paper, printed materials, color filters, flexible displays, optical films, 3D displays, touch panels, and transparent conductive film substrates. , solar cells, etc., and it is more preferable to use it as a substitute material for the part where glass is currently used. In these applications, 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.

In addition, the polyamic acid solution according to the present embodiment is a batch-type device in which the polyimide film is peeled off after applying the polyamic acid solution on a support, imidizing it by heating, and forming an electronic element or the like. It can be used appropriately for the manufacturing process. Therefore, this embodiment also includes a method for manufacturing an electronic device including a step of applying a polyamic acid solution on a support, imidizing it by heating, and forming an electronic element or the like in the polyimide film formed on the support. . Moreover, the manufacturing method of such an electronic device may further include the process of peeling the polyimide film in which the electronic element etc. were formed from the support body.

Example

Hereinafter, examples of the present invention will be described, 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 will be described.

[Yellowness Index (YI)]

For the polyimide films obtained in Examples and Comparative Examples described later, the light transmittance at a wavelength of 200 nm or more and 800 nm or less was measured using a spectrophotometer ("V-650" manufactured by Nippon Bunko Co., Ltd.), and JIS K7373 - From the formula described in 2006, the yellowness (YI) of the polyimide film was calculated.

[Haze]

For the polyimide films obtained in Examples and Comparative Examples described later, haze was measured by the method described in JIS K7136-2000 using an integrating sphere haze meter ("HM-150N" manufactured by Murakami Shikisai Kijutsu Genkyujo Co., Ltd.) did

[Internal Stress]

Each polyamic acid solution prepared in Examples and Comparative Examples described later was applied to a glass substrate (material: non-alkali glass, thickness: 0.7 mm, size: 100 mm × 100 mm) manufactured by Corning, the amount of warp of which was measured in advance, by a spin coater. was applied, heated in air at 120°C for 30 minutes, and then heated at 430°C for 30 minutes in a nitrogen atmosphere to obtain a laminate comprising a polyimide film having a thickness of 10 µm on a glass substrate. In order to eliminate the effect of absorption of the polyimide film, after drying the laminate at 120 ° C. for 10 minutes, the amount of warping of the laminate in a nitrogen atmosphere at a temperature of 25 ° C. was measured using a thin film stress measuring device (“FLX- 2320-S”) was used. Then, the internal stress generated between the glass substrate and the polyimide film was calculated by Stoney's equation from the amount of warp of the glass substrate before formation of the polyimide film and the amount of warp of the laminate.

[Glass Transition Temperature (Tg)]

Polyimide films obtained in Examples and Comparative Examples described later were sampled at a width of 3 mm and a length of 10 mm to obtain samples for Tg measurement. Using a thermal analysis device (“TMA/SS7100” manufactured by Hitachi High-Tech Science Co., Ltd.), a load of 98.0 mN was applied to the obtained sample, the temperature was raised from 20° C. to 450° C. at 10° C./min, and the temperature and strain amount (elongation) were plotted. to obtain the TMA curve. The temperature of the inflection point of the obtained TMA curve (the temperature corresponding to the peak in the differential curve of the TMA curve) was taken as the glass transition temperature (Tg).

[1% Weight Loss Temperature (TD1)]

Regarding the polyimide film (sample) obtained in Examples and Comparative Examples described later, a differential thermal thermogravimetric simultaneous measuring device (“TG/DTA7200” manufactured by Hitachi High-Tech Science Co., Ltd.) was used in a nitrogen atmosphere at 20° C./min. The temperature was raised from 25 ° C. to 650 ° C., and the measured temperature when the sample weight at the measured temperature of 150 ° C. was reduced by 1% by weight relative to the standard weight was taken as the 1% weight loss temperature (TD1). .

[Presence or absence of lifting between the glass substrate and the polyimide film]

Each polyamic acid solution prepared in Examples and Comparative Examples described later was applied on a glass substrate (material: non-alkali glass, thickness: 0.7 mm, size: 100 mm × 100 mm) manufactured by Corning Corporation by a spin coater, and then in the air. After heating at 120°C for 30 minutes, it was heated at 430°C for 30 minutes in a nitrogen atmosphere to obtain a laminate comprising a polyimide film having a thickness of 10 µm on a glass substrate. About the obtained laminated body, the presence or absence of the floating between the glass substrate and the polyimide film|membrane was visually confirmed.

[Presence or absence of lifting between the SiOx film and the polyimide film]

Each polyamic acid solution prepared in Examples and Comparative Examples described later was applied on a glass substrate (material: non-alkali glass, thickness: 0.7 mm, size: 100 mm × 100 mm) manufactured by Corning Corporation by a spin coater, and then in the air. After heating at 120 ° C. for 30 minutes, heating at 430 ° C. for 30 minutes in a nitrogen atmosphere to form a polyimide film having a thickness of 10 μm on a glass substrate. Subsequently, a SiOx film (thickness: 1 μm) was laminated on the obtained polyimide film by a plasma CVD method, and the obtained laminate was heated at 430° C. for 60 minutes in a nitrogen atmosphere. And about the laminated body after heating, the presence or absence of lifting between the SiOx film and the polyimide film was visually confirmed.

<Production of Polyimide Film>

Hereinafter, the manufacturing method of the polyimide film (laminate|laminate) of an Example and a comparative example is demonstrated. In addition, in the following, compounds and reagents are described with the following abbreviations. In both Examples and Comparative Examples, synthesis of polyamic acid was performed under a nitrogen atmosphere.

NMP: N-methyl-2-pyrrolidone

BPAF: 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride

BPDA: 3,3'-4,4'-biphenyltetracarboxylic dianhydride

PMDA: pyromellitic dianhydride

4-BAAB: 4-aminophenyl-4-aminobenzoate

PDA: p-phenylenediamine

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

DMI: 1,2-dimethylimidazole

[Example 3]

39.6 g of NMP was placed as an organic solvent for polymerization in a 300 mL glass separable flask equipped with a stirrer with a stainless steel stirrer and a nitrogen inlet tube. Then, while stirring the contents of the flask, 3.030 g of 4-BAAB was added to the flask and dissolved. Next, after adding 0.183 g of BPAF to the contents of the flask, 3.788 g of BPDA was added, and the contents of the flask were stirred for 24 hours in an atmosphere at a temperature of 25°C to obtain a polyamic acid solution. The obtained polyamic acid solution was coated on a glass substrate (manufactured by Corning, material: alkali-free glass, thickness: 0.7 mm, size: 100 mm × 100 mm) using a spin coater, and in air at 120 ° C. for 30 minutes. After heating, it heated at 430 degreeC for 30 minutes in nitrogen atmosphere, and obtained the laminated body provided with the polyimide film of thickness 10 micrometers on the glass substrate.

[Example 4]

39.6 g of NMP was placed as an organic solvent for polymerization in a 300 mL glass separable flask equipped with a stirrer with a stainless steel stirrer and a nitrogen inlet tube. Then, while stirring the contents of the flask, 3.030 g of 4-BAAB was added to the flask and dissolved. Next, after adding 0.183 g of BPAF to the contents of the flask, 3.788 g of BPDA was added, and the contents of the flask were stirred for 24 hours in an atmosphere at a temperature of 25°C. Next, 1 part by weight of DMI was added to the flask with respect to 100 parts by weight of polyamic acid in the contents of the flask to obtain a polyamic acid solution. The obtained polyamic acid solution was coated on a glass substrate (manufactured by Corning, material: alkali-free glass, thickness: 0.7 mm, size: 100 mm × 100 mm) using a spin coater, and in air at 120 ° C. for 30 minutes. After heating, it heated at 430 degreeC for 30 minutes in nitrogen atmosphere, and obtained the laminated body provided with the polyimide film of thickness 10 micrometers on the glass substrate.

[Examples 1, 5, 7, 9 and 11]

Except for changing the input ratio of BPAF and BPDA to the ratio described in Table 1, a laminate provided with a polyimide film having a thickness of 10 μm was obtained on a glass substrate by the same method as in Example 3. In addition, in any of Examples 1, 5, 7, 9 and 11, the total amount of acid dianhydride was the same as in Example 3.

[Examples 2, 6, 8, 10 and 12]

A laminate comprising a polyimide film having a thickness of 10 μm was obtained on a glass substrate in the same manner as in Example 4, except that the ratio of BPAF and BPDA added was changed to the ratio shown in Table 1. In addition, for any of Examples 2, 6, 8, 10 and 12, the total amount of acid dianhydride was the same as in Example 4.

[Examples 13 and 15]

The same method as in Example 3 except that the input ratio of BPAF and BPDA was changed to the ratio shown in Table 1, and that 4-BAAB and PDA were used as diamines for synthesis of polyamic acid in the ratio shown in Table 1. Thus, a laminate comprising a polyimide film having a thickness of 10 μm was obtained on a glass substrate. In addition, for any of Examples 13 and 15, the total amount of acid dianhydride and the total amount of diamine were the same as in Example 3.

[Examples 14 and 16]

The same method as in Example 4 except that the input ratio of BPAF and BPDA was changed to the ratio shown in Table 1, and 4-BAAB and PDA were used as diamines for synthesis of polyamic acid in the ratio shown in Table 1 Thus, a laminate comprising a polyimide film having a thickness of 10 μm was obtained on a glass substrate. In addition, for any of Examples 14 and 16, the total amount of acid dianhydride and the total amount of diamine were the same as in Example 4.

[Example 17]

Except for using PMDA instead of BPDA and using BPAF and PMDA at the input ratios shown in Table 1, in the same manner as in Example 4, a laminate having a polyimide film having a thickness of 10 μm was obtained on a glass substrate. . In addition, the total amount of acid dianhydrides used in Example 17 was the same as the total amount of acid dianhydrides used in Example 4.

[Comparative Example 1]

39.6 g of NMP was placed as an organic solvent for polymerization in a 300 mL glass separable flask equipped with a stirrer with a stainless steel stirrer and a nitrogen inlet tube. Then, while stirring the contents of the flask, 3.058 g of 4-BAAB was added to the flask and dissolved. Next, 3.942 g of BPDA was added to the contents of the flask, and the contents of the flask were stirred for 24 hours in an atmosphere at a temperature of 25°C to obtain a polyamic acid solution. The obtained polyamic acid solution was coated on a glass substrate (manufactured by Corning, material: alkali-free glass, thickness: 0.7 mm, size: 100 mm × 100 mm) using a spin coater, and in air at 120 ° C. for 30 minutes. After heating, it heated at 430 degreeC for 30 minutes in nitrogen atmosphere, and obtained the laminated body provided with the polyimide film of thickness 10 micrometers on the glass substrate.

[Comparative Example 2]

39.6 g of NMP was placed as an organic solvent for polymerization in a 300 mL glass separable flask equipped with a stirrer with a stainless steel stirrer and a nitrogen inlet tube. Then, while stirring the contents of the flask, 3.058 g of 4-BAAB was added to the flask and dissolved. Next, 3.942 g of BPDA was added to the contents of the flask, and the contents of the flask were stirred for 24 hours in an atmosphere at a temperature of 25°C. Next, 1 part by weight of DMI was added to the flask with respect to 100 parts by weight of polyamic acid in the contents of the flask to obtain a polyamic acid solution. The obtained polyamic acid solution was coated on a glass substrate (manufactured by Corning, material: alkali-free glass, thickness: 0.7 mm, size: 100 mm × 100 mm) using a spin coater, and in air at 120 ° C. for 30 minutes. After heating, it heated at 430 degreeC for 30 minutes in nitrogen atmosphere, and obtained the laminated body provided with the polyimide film of thickness 10 micrometers on the glass substrate.

[Comparative Example 3]

Except for using PDA instead of 4-BAAB, a laminate provided with a polyimide film having a thickness of 10 µm was obtained on a glass substrate in the same manner as in Comparative Example 1. In addition, the amount of PDA used in Comparative Example 3 was the same as that of 4-BAAB used in Comparative Example 1.

[Comparative Example 4]

Except for using TFMB instead of 4-BAAB, a laminate provided with a polyimide film having a thickness of 10 μm was obtained on a glass substrate by the same method as in Comparative Example 2. In addition, the substance amount of TFMB used in Comparative Example 4 was the same as the substance amount of 4-BAAB used in Comparative Example 2.

[Comparative Example 5]

A polyimide film having a thickness of 10 μm was formed on a glass substrate in the same manner as in Example 4, except that TFMB was used instead of 4-BAAB and the input ratio of BPAF and BPDA was changed to the ratio shown in Table 1. A laminate was obtained. In addition, the substance amount of TFMB used in Comparative Example 5 was the same as the substance amount of 4-BAAB used in Example 4. In addition, the total amount of acid dianhydrides used in Comparative Example 5 was the same as the total amount of acid dianhydrides used in Example 4.

For each of Examples 1 to 17 and Comparative Examples 1 to 5, the materials used and their ratios are shown in Table 1, and the physical properties and evaluation are shown in Table 2. In Table 1, "-" means that the component was not used. In addition, in Table 1, the numerical value of the "acid dianhydride" column is the content rate (unit: mol%) of each acid dianhydride with respect to the total amount of the acid dianhydride used. In addition, the numerical value of the column of "diamine" is the content rate (unit: mol%) of each diamine with respect to the whole amount of diamine used. In addition, the numerical value in the column of "additives" is the addition amount of the additive with respect to 100 parts by weight of polyamic acid in the contents of the flask (unit: parts by weight).

As shown above, in this Example using the polyamic acid having the structural unit (1), all conditions (1) to (4) below were satisfied.

(1) TD1 exceeds 500°C.

(2) YI is 25 or less.

(3) Internal stress is 30 MPa or less.

(4) Tg exceeds 400°C.

In Comparative Examples 1 and 2, although Tg and TD1 were high, the haze was high, and lifting occurred between the glass substrate and the polyimide film. In Comparative Example 3, although Tg and TD1 were high, YI was high, and lifting occurred between the glass substrate and the polyimide film. In Examples 1 to 17, Tg and TD1 were high, and YI and haze were low. Further, in Examples 1 to 17, there was no lifting between the glass substrate and the polyimide film, and no lifting between the SiOx film and the polyimide film.

In Comparative Examples 4 and 5 containing fluorine atoms, YI was low, but lifting occurred between the SiOx film and the polyimide film.

From the above results, it was shown that the polyimide obtained from the polyamic acid according to the present invention is excellent in transparency and heat resistance, and can secure adhesion to inorganic materials during a high-temperature process.

Claims (15)

A polyamic acid containing a structural unit represented by the following formula (1).

The polyamic acid according to claim 1, further comprising a structural unit represented by the following general formula (2).

(In the above general formula (2), X represents a tetravalent organic group different from the tetracarboxylic dianhydride residue in the above general formula (1).) The method according to claim 2, wherein X in the general formula (2) is at least one member selected from the group consisting of a tetravalent organic group represented by the following general formula (3) and a tetravalent organic group represented by the following general formula (4), polyamic acid.

The polyamic acid according to any one of claims 1 to 3, wherein the content of the structural unit represented by the general formula (1) is 1 mol% or more with respect to all structural units. The polyamic acid according to any one of claims 1 to 4, wherein a ratio of the total amount of tetracarboxylic acid dianhydride residues divided by the total amount of diamine residues is 0.900 or more and less than 1.100. A polyamic acid solution containing the polyamic acid according to any one of claims 1 to 5 and an organic solvent. A polyimide which is an imide product of the polyamic acid according to any one of claims 1 to 5. The polyimide according to claim 7, wherein the 1% weight loss temperature is 500°C or higher. The polyimide according to claim 7 or 8, having a glass transition temperature of 400°C or higher. A polyimide film comprising the polyimide according to any one of claims 7 to 9. The polyimide film according to claim 10, having a yellowness of 25 or less. The polyimide film according to claim 10 or 11, having a haze of less than 1.0%. A laminate comprising a support and the polyimide film according to any one of claims 10 to 12. As a method for producing a laminate having a support and a polyimide film,
A method for producing a laminate comprising applying the polyamic acid solution according to claim 6 onto a support to form a coating film containing the polyamic acid, and imidizing the polyamic acid by heating the coating film. An electronic device comprising the polyimide film according to any one of claims 10 to 12 and an electronic element disposed on the polyimide film.