Polyamic acid composition, polyimide, polyimide film, laminate, method for producing laminate, and electronic device

Abstract

The polyamic acid composition contains a polyamic acid containing a structural unit shown in the following general formula (1) and a plasticizer. Polyimide is an imide of a polyamic acid containing a structural unit shown in the following general formula (1). The polyimide film contains an imide of a polyamic acid containing a structural unit shown in the following general formula (1). The laminate has a support and a polyimide film, and the polyimide film contains an imide of a polyamic acid containing a structural unit shown in the following general formula (1). The electronic device has a polyimide film and an electronic component configured on the polyimide film, and the polyimide film contains an imide of a polyamic acid containing a structural unit shown in the following general formula (1).

Description

Technical Field

[0001] The present invention relates to a polyamic acid composition, a polyimide, a polyimide film, a laminate, a method for manufacturing a laminate, and an electronic device. The present invention also relates to an electronic device material using polyimide, a thin film transistor (TFT) substrate, a flexible display substrate, a color filter, a printed matter, an optical material, an image display device (more specifically, a liquid crystal display device, an organic EL, an electronic paper, etc.), a 3D display, a solar cell, a touch panel, a transparent conductive film substrate, and an alternative material for a component currently using glass. Background Art

[0002] With the rapid progress of electronic devices such as LCDs, organic EL, and electronic paper, solar cells, and touch panels, the devices are becoming thinner, lighter, and more flexible. In these devices, polyimide can be used as a substrate material instead of a glass substrate.

[0003] In these devices, various electronic components such as thin film transistors and transparent electrodes are formed on the substrate, and the formation of these electronic components requires high temperature processes. Polyimide has sufficient heat resistance to adapt to high temperature processes, and its coefficient of thermal expansion (CTE) is close to that of glass substrates and electronic components, so it is not easy to generate internal stress, and is suitable for substrate materials such as flexible displays.

[0004] Generally, aromatic polyimide is colored yellow-brown due to intramolecular conjugation and formation of charge transfer (CT) complexes, but in top-emitting organic EL, etc., since light is extracted from the opposite side of the substrate, transparency is not required for the substrate, and conventional aromatic polyimide is used. However, in the case where light emitted from a display element is emitted through a substrate, such as in a transparent display, bottom-emitting organic EL, or liquid crystal display, or in the case where a sensor or camera module is arranged on the back of a substrate in order to make a smartphone or the like a full-surface display (without a notch), the substrate is also required to have high optical properties (more specifically, transparency, etc.).

[0005] Under such circumstances, a material having heat resistance equivalent to that of conventional aromatic polyimides and having reduced coloration and excellent transparency has been sought.

[0006] In order to reduce the coloring of polyimide, there are known technologies of suppressing the formation of CT complexes using aliphatic monomers (Patent Documents 1 and 2) and technologies of improving transparency using monomers having fluorine atoms or sulfur atoms (Patent Document 3).

[0007] The polyimides described in Patent Documents 1 and 2 have high transparency and low CTE, but have an aliphatic structure and therefore have low thermal decomposition temperatures, making them difficult to apply to high-temperature processes for forming electronic components.

[0008] Prior art literature

[0009] Patent Literature

[0010] Patent Document 1: Japanese Patent Application Publication No. 2016-29177

[0011] Patent Document 2: Japanese Patent Application Publication No. 2012-41530

[0012] Patent Document 3: Japanese Patent Application Publication No. 2014-70139 Summary of the invention

[0013] Problem that the invention aims to solve

[0014] According to the research conducted by the present inventors, the polyimide described in Patent Document 3 contains fluorine atoms, and therefore hydrogen fluoride may be generated in a high-temperature process. If hydrogen fluoride is generated, poor adhesion may occur between the polyimide and a barrier film, etc., or corrosion may occur in electronic components provided on the polyimide film.

[0015] The present invention is completed in view of the above-mentioned actual situation, and its object is to provide a polyimide and a polyamic acid composition as its precursor that are colored and reduced, excellent in transparency, have high heat resistance, and can suppress the generation of hydrogen fluoride in high temperature processes. Further, the object of the present invention is also to provide a product or component manufactured using the polyimide and polyamic acid composition, requiring heat resistance and transparency. Particularly, its object is to provide a product or component that the polyimide film of the present invention is formed on the surface of inorganic substances such as glass, metal, metal oxide, single crystal silicon.

[0016] Solutions for solving problems

[0017] The present inventors have conducted intensive studies and have found that a polyimide obtained from a composition containing a specific polyamic acid and a plasticizer has reduced coloration, excellent transparency, high heat resistance, and can suppress the generation of hydrogen fluoride in a high-temperature process, thereby completing the present invention.

[0018] The polyamic acid composition of the present invention contains a polyamic acid and a plasticizer, wherein the polyamic acid contains a structural unit represented by the following general formula (1).

[0019]

[0020] In the above general formula (1), R 1 and R 2 Each independently represents a hydrogen atom, a monovalent aliphatic group or a monovalent aromatic group, and X represents a tetravalent organic group.

[0021] In the polyamic acid composition of one embodiment of the present invention, R in the general formula (1) is 1 and R 2 Both represent hydrogen atoms.

[0022] In the polyamic acid composition of one embodiment of the present invention, X in the general formula (1) is one or more selected from the group consisting of a tetravalent organic group represented by the following chemical formula (2), a tetravalent organic group represented by the following chemical formula (3), a tetravalent organic group represented by the following chemical formula (4), and a tetravalent organic group represented by the following chemical formula (5).

[0023]

[0024] In the polyamic acid composition according to one embodiment of the present invention, the content of the structural unit represented by the general formula (1) is 50 mol% or more and 100 mol% or less relative to all structural units of the polyamic acid.

[0025] In the polyamic acid composition according to one embodiment of the present invention, the amount of the plasticizer is 20 parts by weight or less based on 100 parts by weight of the polyamic acid.

[0026] In the polyamic acid composition according to one embodiment of the present invention, the plasticizer is at least one selected from the group consisting of phosphorus-containing compounds, polyalkylene glycols, and aliphatic dibasic acid esters.

[0027] The polyamic acid composition according to one embodiment of the present invention further contains an organic solvent.

[0028] The polyimide of the present invention is an imidate of the polyamic acid contained in the polyamic acid composition of the present invention.

[0029] The 1% weight loss temperature of the polyimide of the present invention is preferably 500° C. or higher.

[0030] The polyimide film of the present invention comprises the polyimide of the present invention.

[0031] The yellowness index of the polyimide film of the present invention is preferably 20 or less.

[0032] The laminate of the present invention comprises a support and the polyimide film of the present invention.

[0033] The method for producing a laminate of the present invention comprises applying the polyamic acid composition of one embodiment of the present invention on a support to form a coating film containing a polyamic acid and a plasticizer, and heating the coating film to imidize the polyamic acid.

[0034] The electronic device of the present invention comprises the polyimide film of the present invention and an electronic element disposed on the polyimide film.

[0035] Effects of the Invention

[0036] The polyimide manufactured using the polyamic acid composition of the present invention has reduced coloration, excellent transparency and heat resistance, and can suppress the generation of hydrogen fluoride in high temperature processes. Therefore, the polyimide manufactured using the polyamic acid composition of the present invention is suitable as a material for electronic devices requiring low coloration, transparency and heat resistance and manufactured through high temperature processes. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 This is a graph showing the results of analyzing the polyimide films of Example 18 and Comparative Example 5 using a quadrupole mass spectrometer. DETAILED DESCRIPTION

[0038] Hereinafter, preferred embodiments of the present invention will be described in detail, but the present invention is not limited to these embodiments.

[0039] First, the terms used in this specification are explained. "Structural unit" refers to a repeating unit constituting a polymer. "Polyamic acid" is a polymer comprising a structural unit represented by the following general formula (6) (hereinafter, sometimes described as "structural unit (6)"). It should be noted that in this specification, not only polyamic acid is described as "polyamic acid", but also polyamic acid esters (polyamic acid alkyl esters, polyamic acid aryl esters, etc.) are also described as "polyamic acid".

[0040]

[0041] In the general formula (6), R 3 and R 4 Each independently represents a hydrogen atom, a monovalent aliphatic group or a monovalent aromatic group, A 1 For example, it represents a tetracarboxylic dianhydride residue (a tetravalent organic group derived from tetracarboxylic dianhydride), A 2 For example, it represents a diamine residue (a divalent organic group derived from a diamine).

[0042] The content of the structural unit (6) relative to all the structural units constituting the polyamic acid is, for example, 50 mol% to 100 mol%, preferably 60 mol% to 100 mol%, more preferably 70 mol% to 100 mol%, further preferably 80 mol% to 100 mol%, further preferably 90 mol% to 100 mol%, and may be 100 mol%.

[0043] The "1% weight loss temperature" is the temperature at which the weight of the polyimide at a measurement temperature of 150° C. is reduced by 1% by weight relative to the weight of the reference (100% by weight). The 1% weight loss temperature is measured by the same method as in the examples described below or a method based thereon.

[0044] “m / z” is a measurement value that can be read from the horizontal axis of a mass spectrum as a measurement result of mass spectrometry, and is “a dimensionless quantity obtained by dividing the mass of an ion by a unified atomic mass unit (Dalton) by the absolute value of the charge number of the ion.”

[0045] The "plasticizer" refers to a material that exists in a liquid form when at least a portion of the polyamic acid is imidized.

[0046] In the following, sometimes "system" is added after the compound name to collectively refer to the compound and its derivatives. When "system" is added after the compound name to indicate the name of a polymer, it means that the repeating unit of the polymer is derived from the compound or its derivatives. In addition, tetracarboxylic dianhydride is sometimes recorded as "acid dianhydride".

[0047] The polyamic acid composition of the present embodiment contains a polyamic acid and a plasticizer. The polyamic acid contains a structural unit represented by the following general formula (1) (hereinafter, sometimes described as “structural unit (1)”).

[0048]

[0049] In the general formula (1), R 1 and R 2 Each independently represents a hydrogen atom, a monovalent aliphatic group or a monovalent aromatic group, and X represents a tetravalent organic group. 1 and R 2 , preferably each independently represents a hydrogen atom, a methyl group or an ethyl group, more preferably R 1 and R 2 Hereinafter, unless otherwise specified, R in the general formula (1) is 1 and R 2 Structural units each representing a hydrogen atom are referred to as structural units (1).

[0050] The polyamic acid composition of the present embodiment contains a polyamic acid containing the structural unit (1) and a plasticizer. Therefore, when a polyimide is produced using the polyamic acid composition of the present embodiment, a polyimide having reduced coloration, excellent transparency and heat resistance, and capable of suppressing generation of hydrogen fluoride in a high temperature process can be obtained.

[0051] The structural unit (1) has a partial structure derived from 2,2'-bis(trifluoromethyl)benzidine (hereinafter sometimes referred to as "TFMB"). That is, the structural unit (1) has a TFMB residue as A in the above general formula (6). 2 .

[0052] TFMB has a rigid structure and is suitable as a raw material (monomer) for polyimide having a high glass transition temperature (excellent heat resistance). In addition, TFMB has a trifluoromethyl group and is therefore suitable as a raw material (monomer) for polyimide having reduced coloration and high transparency.

[0053] When synthesizing a polyamic acid containing a structural unit (1) (hereinafter, sometimes described as "polyamic acid (1)"), diamines other than TFMB may be used as monomers within a range that does not impair its performance. Examples of diamines other than TFMB include, for example, 4-aminobenzoic acid-4-aminophenyl ester (hereinafter, sometimes described as "4-BAAB"), 1,4-diaminocyclohexane, p-phenylenediamine, m-phenylenediamine, 9,9-bis(4-aminophenyl)fluorene, 4,4'-oxydiphenylamine, 3,4'-oxydiphenylamine, 2,2'-bis(trifluoromethyl)-4,4'-diaminodiphenyl ether, 4,4'-diaminobenzanilide, N,N'-bis(4-aminophenyl)fluorene, phenyl) terephthalamide, 4,4'-diaminodiphenyl sulfone, 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(cyclohexylamine), 1,3-bis(3-aminopropyl)tetramethyldisiloxane and their derivatives can be used alone or in combination of two or more.

[0054] From the viewpoint of improving heat resistance, 4-BAAB is preferred as a diamine other than TFMB. Therefore, from the viewpoint of improving heat resistance, polyamic acid (1) preferably has a 4-BAAB residue. 4-BAAB has a rigid structure and is therefore suitable as a raw material (monomer) for a polyimide having excellent heat resistance. In addition, 4-BAAB having a rigid structure is also suitable as a raw material (monomer) for a polyimide having high mechanical strength and suppressing the generation of internal stress.

[0055] In order to obtain a polyimide with further reduced coloration, better heat resistance and higher transparency, the polyamic acid (1) preferably has only a TFMB residue as a diamine residue, or only a TFMB residue and a 4-BAAB residue as diamine residues.

[0056] In order to obtain a polyimide with further reduced coloration and better heat resistance, the content of TFMB residues relative to all diamine residues constituting the polyamic acid (1) is preferably 30 mol% or more, more preferably 40 mol% or more, further preferably 50 mol% or more, further preferably 60 mol% or more, and can be 70 mol% or more, 80 mol% or more, or 90 mol% or more, and can also be 100 mol%.

[0057] In order to obtain a polyimide with further reduced coloration and better heat resistance, the content of the structural unit (1) is preferably 30 mol% to 100 mol%, more preferably 40 mol% to 100 mol%, further preferably 50 mol% to 100 mol%, further preferably 60 mol% to 100 mol%, and may be 70 mol% to 100 mol%, 80 mol% to 100 mol%, or 90 mol% to 100 mol%, or 100 mol%.

[0058] When the polyamic acid (1) has 4-BAAB residues, in order to obtain a polyimide with better heat resistance, the content of 4-BAAB residues relative to all diamine residues constituting the polyamic acid (1) is preferably 10 mol% or more, more preferably 20 mol% or more, and further preferably 30 mol% or more. In addition, when the polyamic acid (1) has 4-BAAB residues, in order to obtain a polyimide with further reduced coloration, the content of 4-BAAB residues relative to all diamine residues constituting the polyamic acid (1) is preferably 70 mol% or less, more preferably 60 mol% or less, further preferably 50 mol% or less, and further preferably 40 mol% or less.

[0059] When the polyamic acid (1) has TFMB residues and 4-BAAB residues, in order to obtain a polyimide with further reduced coloration, better heat resistance and higher transparency, the total content of TFMB residues and 4-BAAB residues is preferably 50 mol% or more, more preferably 60 mol% or more, further preferably 70 mol% or more, further preferably 80 mol% or more, and may be 90 mol% or more, or may be 100 mol% relative to all diamine residues constituting the polyamic acid (1).

[0060] Examples of the tetracarboxylic dianhydride (the acid dianhydride providing X in the general formula (1)) used for synthesizing the polyamic acid (1) include pyromellitic dianhydride (hereinafter, sometimes referred to as "PMDA"), 3,3',4,4'-biphenyltetracarboxylic dianhydride (hereinafter, sometimes referred to as "BPDA"), p-phenylenebistrimellitate dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 2,2',3,3'-biphenyltetracarboxylic dianhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride, 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride (hereinafter, sometimes referred to as "BPAF"), ), 4,4'-oxydiphthalic anhydride (hereinafter sometimes referred to as "ODPA"), 4,4'-(hexafluoroisopropylidene)diphthalic anhydride, 9,9-bis(trifluoromethyl)oxanthenetetracarboxylic dianhydride, dicyclohexyl-3,3',4,4'-tetracarboxylic dianhydride, 1,2,4,5-cyclohexanetetracarboxylic dianhydride, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 2'-oxydispiro[bicyclo[2.2.1]heptane-2,1'-cyclopentane-3',2"-bicyclo[2.2.1]heptane]-5,6:5",6"-tetracarboxylic dianhydride and their derivatives can be used alone or in combination of two or more.

[0061] In order to obtain a polyimide capable of further suppressing the generation of hydrogen fluoride in a high temperature process, the acid dianhydride providing X in the general formula (1) is preferably an acid dianhydride containing no fluorine atoms. That is, in order to obtain a polyimide capable of further suppressing the generation of hydrogen fluoride in a high temperature process, it is preferred that the acid dianhydride residue constituting the polyamic acid (1) contains no fluorine atoms.

[0062] The acid dianhydride providing X in the general formula (1) is preferably one or more selected from the group consisting of PMDA, BPDA, BPAF and ODPA. That is, the polyamic acid (1) preferably has one or more selected from the group consisting of PMDA residue, BPDA residue, BPAF residue and ODPA residue as X in the general formula (1).

[0063] The PMDA residue is a tetravalent organic group represented by the following chemical formula (2). The BPDA residue is a tetravalent organic group represented by the following chemical formula (3). The BPAF residue is a tetravalent organic group represented by the following chemical formula (4). The ODPA residue is a tetravalent organic group represented by the following chemical formula (5).

[0064]

[0065] In order to obtain a polyimide having better heat resistance, reduced internal stress, and high mechanical strength, the polyamic acid (1) preferably has one or more selected from the group consisting of PMDA residues and BPDA residues. In order to obtain a polyimide having higher transparency, the polyamic acid (1) preferably has one or more selected from the group consisting of BPAF residues and ODPA residues.

[0066] When the polyamic acid (1) has one or more selected from the group consisting of PMDA residues, BPDA residues, BPAF residues and ODPA residues, the total content of the PMDA residues, BPDA residues, BPAF residues and ODPA residues is preferably 60 mol% or more, more preferably 70 mol% or more, further preferably 80 mol% or more, further preferably 90 mol% or more, and may be 100 mol% relative to all the acid dianhydride residues constituting the polyamic acid (1). When the total content of the PMDA residues, BPDA residues, BPAF residues and ODPA residues is 60 mol% or more relative to all the acid dianhydride residues constituting the polyamic acid (1), a polyimide having better transparency and heat resistance, reduced internal stress and high mechanical strength can be obtained.

[0067] When the polyamic acid (1) has a PMDA residue, in order to obtain a polyimide having better heat resistance, reduced internal stress, and high mechanical strength, the content of the PMDA residue is preferably 30 mol% to 100 mol%, more preferably 40 mol% to 90 mol%, and even more preferably 50 mol% to 80 mol%, relative to all the acid dianhydride residues constituting the polyamic acid (1).

[0068] When the polyamic acid (1) has a BPDA residue, in order to obtain a polyimide having better heat resistance, reduced internal stress, and high mechanical strength, the content of the BPDA residue is preferably 10 mol% to 100 mol%, more preferably 10 mol% to 90 mol%, relative to all the acid dianhydride residues constituting the polyamic acid (1).

[0069] When the polyamic acid (1) has a BPAF residue, in order to obtain a polyimide with higher transparency, the content of the BPAF residue is preferably 1 mol% or more, more preferably 3 mol% or more, further preferably 5 mol% or more, and may be 10 mol% or more relative to all the acid dianhydride residues constituting the polyamic acid (1). In addition, when the polyamic acid (1) has a BPAF residue, in order to reduce internal stress, the content of the BPAF residue is preferably 50 mol% or less, more preferably 40 mol% or less, and further preferably 30 mol% or less relative to all the acid dianhydride residues constituting the polyamic acid (1).

[0070] When the polyamic acid (1) has an ODPA residue, in order to obtain a polyimide with higher transparency, the content of the ODPA residue is preferably 1 mol% or more, more preferably 3 mol% or more, and further preferably 5 mol% or more relative to all the acid dianhydride residues constituting the polyamic acid (1). In addition, when the polyamic acid (1) has an ODPA residue, in order to reduce internal stress, the content of the ODPA residue is preferably 50 mol% or less, more preferably 40 mol% or less, and further preferably 30 mol% or less relative to all the acid dianhydride residues constituting the polyamic acid (1).

[0071] Polyamic acid (1) can be synthesized by a known general method, for example, by reacting diamine and tetracarboxylic dianhydride in an organic solvent. An example of a specific synthesis method of polyamic acid (1) is described. First, in an inert gas environment such as argon or nitrogen, diamine is dissolved in an organic solvent or dispersed in a slurry to prepare a diamine solution. Then, tetracarboxylic dianhydride is made into a state of being dissolved in an organic solvent or dispersed in a slurry, or added to the above-mentioned diamine solution in a solid state.

[0072] When a polyamic acid (1) is synthesized using a diamine and a tetracarboxylic dianhydride, the desired polyamic acid (1) (polymer of a diamine and a tetracarboxylic dianhydride) can be obtained by adjusting the amount of the diamine substance (when a plurality of diamines are used, the amount of each diamine substance) and the amount of the tetracarboxylic dianhydride substance (when a plurality of tetracarboxylic dianhydrides are used, the amount of each tetracarboxylic dianhydride substance). The molar fraction of each residue in the polyamic acid (1) is consistent with the molar fraction of each monomer (diamine and tetracarboxylic dianhydride) used in the synthesis of the polyamic acid (1). In addition, by mixing two kinds of polyamic acids, a polyamic acid (1) containing a plurality of tetracarboxylic dianhydride residues and a plurality of diamine residues can also be obtained. The temperature conditions for the reaction of the diamine and the tetracarboxylic dianhydride, i.e., the synthesis reaction of the polyamic acid (1) are not particularly limited, and are, for example, in the range of 20°C or more and 150°C or less. The reaction time of the synthesis reaction of the polyamic acid (1) is, for example, in the range of 10 minutes or more and 30 hours or less.

[0073] The organic solvent used in the synthesis of the polyamic acid (1) is preferably a solvent that can dissolve the tetracarboxylic dianhydride and diamine used, and more preferably a solvent that can dissolve the produced polyamic acid (1). Examples of the organic solvent used in the synthesis of polyamic acid (1) include urea solvents such as tetramethylurea and N,N-dimethylethylurea; sulfoxide solvents such as dimethyl sulfoxide; sulfone solvents such as diphenyl sulfone and tetramethyl sulfone; amide solvents such as N,N-dimethylacetamide (DMAC), N,N-dimethylformamide (DMF), N,N-diethylacetamide, N-methyl-2-pyrrolidone (NMP), and hexamethylphosphoric acid triamide; ester solvents such as γ-butyrolactone; halogenated alkyl solvents such as chloroform and dichloromethane; aromatic hydrocarbon solvents such as benzene and toluene; phenol 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. These solvents are usually used alone, but two or more of them can be used in combination as needed. In order to improve the solubility and reactivity of polyamic acid (1), the organic solvent used in the synthesis reaction of polyamic acid (1) is preferably one or more solvents selected from the group consisting of amide solvents, ketone solvents, ester solvents and ether solvents, and more preferably amide solvents (more specifically, DMF, DMAC, NMP, etc.). In addition, the synthesis reaction of polyamic acid (1) is preferably carried out in an inert gas environment such as argon and nitrogen.

[0074] The weight average molecular weight of polyamic acid (1) is different according to its use, preferably more than 10000 and the scope below 1000000, more preferably more than 20000 and the scope below 500000, more preferably more than 30000 and the scope below 200000. If the weight average molecular weight is more than 10000, then polyamic acid (1) or the polyimide obtained using polyamic acid (1) is easily made into coating film or polyimide film (film). On the other hand, when the weight average molecular weight is less than 1000000, due to showing sufficient solubility to the solvent, the polyamic acid composition described later can obtain a coating film or polyimide film with smooth surface and uniform thickness. The weight average molecular weight used herein refers to the polyethylene oxide conversion value measured using gel permeation chromatography (GPC).

[0075] In addition, as a method for controlling the molecular weight of polyamic acid (1), there can be cited a method of making any one of the acid dianhydride and the diamine excessive, and a method of terminating the reaction by reacting with a monofunctional acid anhydride or amine such as phthalic anhydride or aniline. In the case of making any one of the acid dianhydride and the diamine excessive and polymerizing, as long as their feed molar ratio is between 0.95 and 1.05, a polyimide film with sufficient strength can be obtained. It should be noted that the above-mentioned feed molar ratio is the ratio of the total amount of diamine used in the synthesis of polyamic acid (1) to the total amount of acid dianhydride used in the synthesis of polyamic acid (1) (total amount of diamine / total amount of acid dianhydride). In addition, by end-capping with phthalic anhydride, maleic anhydride, aniline, etc., the coloring of the polyimide obtained using polyamic acid (1) can also be further reduced.

[0076] Next, the effect of the plasticizer (hereinafter, sometimes simply recorded as "plasticizer") contained in the polyamic acid composition of the present embodiment is described. Usually, when it is desired to obtain a transparent polyimide film, in principle, it is sufficient to design a polyimide with a large band gap between HOMO and LUMO, so TFMB with low electron donation is effective for obtaining a transparent polyimide film. On the other hand, it is speculated that TFMB with low electron donation has a slow reaction rate and a slow imidization rate due to its low nucleophilicity. Regarding the imidization rate, the present inventors conducted research and obtained the following insights. That is, the imidization rates of the conventional colored polyimide obtained from BPDA and paraphenylenediamine and the transparent polyimide obtained from PMDA, BPDA and TFMB were compared. The results showed that the colored polyimide was imidized by more than 90% at an imidization reaction temperature of 300°C, and was close to 100% at an imidization reaction temperature of 350°C, but the transparent polyimide was imidized by only about 75% at an imidization reaction temperature of 300°C, and was imidized by only about 80% at an imidization reaction temperature of 350°C. Clear differences were seen in the imidization rates.

[0077] Generally, the driving force for the dehydration and ring closure of polyamic acid to form polyimide by thermal imidization is largely due to the molecular motion caused by heat and the plasticizing effect caused by the solvent. In order to completely imidize it, it is preferably treated above the glass transition temperature of the polyimide. However, in the combination of rigid acid dianhydrides such as PMDA and TFMB, the glass transition temperature of the obtained polyimide exceeds 400°C, and the glass transition temperature is sometimes higher than the heat treatment temperature during film formation. Therefore, in the imidization reaction of rigid acid dianhydrides such as PMDA and TFMB, imidization may not be completely carried out. Therefore, for example, in a high-temperature process using a polyimide film (such as annealing treatment of TFT), imidization of unreacted sites in the polyimide film is carried out, resulting in degassing (such as hydrogen fluoride, etc.) caused by the generation of low molecular weight components from the polyimide film, which may cause peeling of the barrier film or corrosion of the TFT. In contrast, the polyamic acid composition of the present embodiment uses a plasticizer to impart sufficient molecular motion during imidization of the polyamic acid (1), so that not only the imidization is completely carried out, but also the depolymerization of the polyamic acid (1) is suppressed, and the generation of degassing (especially hydrogen fluoride) can be suppressed. Furthermore, the polyamic acid composition of the present embodiment imparts molecular motion to the polyamic acid (1), so that the solvent is easily removed, the amount of residual solvent in the film (polyimide film) is reduced, and the coloring of the film is also reduced.

[0078] The inventors of the present invention have conducted research, and the results show that by imidizing in the presence of a plasticizer, the amount of residual solvent in the film is reduced, and the degassing itself is also greatly reduced. In particular, when TFMB is used as a monomer, by imidizing in the presence of a plasticizer, the amount of hydrogen fluoride gas generated when the obtained polyimide is used in a high-temperature process can be suppressed. The polyamic acid composition of the present embodiment can suppress the generation of hydrogen fluoride in a high-temperature process because it contains a plasticizer. Therefore, the polyamic acid composition of the present embodiment, for example, in the manufacturing process of a flexible display, can suppress the corrosion of the barrier film formed on the polyimide film and the glass as the supporting substrate, so that the reliability of the flexible display can be improved (not easy to produce obstacles). In addition, the polyamic acid composition of the present embodiment can be given sufficient molecular motion during the imidization of polyamic acid (1), so that imidization can be promoted to obtain a polyimide with excellent heat resistance. It should be noted that the plasticizer can remain in the polyimide film, or it can be decomposed and removed from the polyimide film during the imidization process. When the plasticizer remains in the polyimide film, in order to obtain a polyimide film with better heat resistance, the content of the plasticizer is preferably 0.01 wt % or less, more preferably 0.001 wt % or less, and further preferably 0.0001 wt % or less based on the total amount of the polyimide film.

[0079] Furthermore, since the polyamic acid composition of the present embodiment contains a plasticizer, even if the content of the TFMB residue is high (for example, even if it is 50 mol % or more relative to all diamine residues), generation of hydrogen fluoride when the obtained polyimide is used in a high temperature process can be suppressed.

[0080] As an index of the amount of hydrogen fluoride gas generated when the imide compound (polyimide of the present embodiment) of polyamic acid (1) is used in a high temperature process, the detection intensity obtained by the mass spectrum can be cited. In detail, first, under a helium gas flow, the above-mentioned polyimide is heated at a heating rate of 10°C / minute from a gas ambient temperature of 60°C, and when the gas ambient temperature reaches 470°C, the gas generated by the above-mentioned polyimide is analyzed using a quadrupole mass spectrometer. Then, from the obtained mass spectrum (in detail, a mass spectrum representing the result of analyzing the components of the gas generated by the above-mentioned polyimide when the gas ambient temperature reaches 470°C), the detection intensity of the peak of m / z=20, which is presumed to be caused by hydrogen fluoride, is read (hereinafter, sometimes recorded as "20 peak intensity"). The more hydrogen fluoride is generated, the greater the 20 peak intensity tends to be. It should be noted that the flow rate of helium gas during analysis using a quadrupole mass spectrometer only needs to be set so that the gas generated by the above-mentioned polyimide can be analyzed in real time using the above-mentioned quadrupole mass spectrometer, for example, in the range of 50 mL / min to 150 mL / min, preferably in the range of 80 mL / min to 120 mL / min.

[0081] The results of the research conducted by the present inventors show that the 20 peak intensity shows a very high correlation with the adhesion between the barrier film and the polyimide film after the heating test. In addition, the results of the research conducted by the present inventors show that by making a laminated body in which a polyimide film and an inorganic film or glass are laminated, the temperature at which hydrogen fluoride starts to be generated becomes lower and the amount of generation becomes larger than that of a single-layer structure composed of a polyimide film. It is speculated that the reason is that since the laminated body is made, the components containing free radicals generated by heat cannot be volatilized, which promotes the cycle of auto-oxidation of polyimide.

[0082] As the plasticizer used in the present embodiment, a material that is dissolved in the solvent used when the polyamic acid (1) is imidized is preferred. In addition, in order to give sufficient molecular mobility to the polyamic acid (1) during imidization, the plasticizer is preferably non-volatile at low temperatures. Therefore, the boiling point of the plasticizer is preferably above 50°C, more preferably above 100°C, and further preferably above 150°C. In addition, in order to give sufficient molecular mobility to the polyamic acid (1) during imidization, the plasticizer preferably does not have a decomposition temperature below the boiling point.

[0083] From the viewpoint of avoiding the self-decomposition of the plasticizer, the amount of the plasticizer is preferably 20 parts by weight or less relative to 100 parts by weight of the polyamic acid (1). Furthermore, from the viewpoint of imparting sufficient molecular mobility to the polyamic acid (1) and avoiding the self-decomposition of the plasticizer, the amount of the plasticizer is preferably 0.001 parts by weight or more and 20 parts by weight or less, more preferably 0.01 parts by weight or more and 15 parts by weight or less, further preferably 0.05 parts by weight or more and 10 parts by weight or less, and even more preferably 0.05 parts by weight or more and 5 parts by weight or less.

[0084] The plasticizer can not only enhance the molecular motion of the polyamic acid (1) when it undergoes dehydration ring closure to form polyimide, but also provide functions such as adjusting the glass transition temperature and imparting flame retardancy. As the plasticizer, for example, one or more kinds of plasticizers can be appropriately selected from known plasticizers.

[0085] In order to further suppress the generation of hydrogen fluoride when used in a high-temperature process, the plasticizer is preferably at least one selected from the group consisting of phosphorus-containing compounds, polyalkylene glycols, and aliphatic dibasic acid esters.

[0086] Examples of the phosphorus-containing compound include compounds represented by the following general formulae (7-1) to (7-10). In the following general formulae (7-1) to (7-10), R 5 , R 6 and R 7 Each independently represents a hydrogen atom, a monovalent organic group or a polyvalent organic group, and R 8 represents a polyvalent organic group, and n represents the degree of polymerization.

[0087]

[0088] As preferred examples of phosphorus-containing compounds, phosphoric acid compounds, phosphorous acid compounds, phosphonic acid compounds, phosphine acid compounds, phosphine compounds, phosphine oxide compounds, phosphorane compounds, phosphazene compounds, etc. can be cited. The phosphorus-containing compound can be an esterified product or a condensate of the above-mentioned compounds, can contain a cyclic structure, and can also form a salt with amines, etc. In addition, among these phosphorus-containing compounds, there are also compounds in a tautomeric relationship such as phosphorous acid compounds and phosphonic acid compounds, which can exist in any state.

[0089] Specific examples of the phosphoric acid compound include trimethyl phosphate, triethyl phosphate, tributyl phosphate, tri(2-ethylhexyl) phosphate, tributoxyethyl phosphate, triphenyl phosphate, tricresyl phosphate, tri(xylyl) phosphate, tri(isopropylphenyl) phosphate, trinaphthyl phosphate, cresyl diphenyl phosphate, xylyl diphenyl phosphate, diphenyl(2-ethylhexyl) phosphate, di(isopropylphenyl)phenyl phosphate, monoisodecyl phosphate, 2-acryloyloxyethyl acid phosphate, 2-methacryloyloxyethyl acid phosphate, diphenyl-2-acryloyloxyethyl phosphate, diphenyl-2-methacryloyloxyethyl phosphate, melamine phosphate, dimelamine phosphate, bisphenol A bis(diphenyl phosphate), and tris(β-chloropropyl) phosphate.

[0090] Specific examples of the phosphorous acid compound include triphenyl phosphite, trisnonylphenyl phosphite, tricresyl phosphite, triethyl phosphite, triisobutyl phosphite, tris(2-ethylhexyl) phosphite, tridecyl phosphite, trilauryl phosphite, tri(tridecyl) phosphite, diphenyl phosphite, diethyl phosphite, dibutyl phosphite, dimethyl phosphite, diphenyl mono(2-ethylhexyl) phosphite, diphenyl monodecyl phosphite, diphenyl mono(tridecyl) phosphite, trilauryl trithiophosphite, diethyl hydrogen phosphite, Bis(2-ethylhexyl)phosphite, dilauryl hydrogen phosphite, dioleyl hydrogen phosphite, diphenyl hydrogen phosphite, tetraphenyl dipropylene glycol diphosphite, bis(decyl)pentaerythritol diphosphite, bis(tridecyl)pentaerythritol diphosphite, tristearyl phosphite, distearylpentaerythritol diphosphite, tris(2,4-di-tert-butylphenyl)phosphite, triisodecyl phosphite, 3,9-bis(2,6-di-tert-butyl-4-methylphenoxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane, and the like.

[0091] As the above-mentioned condensation product, condensed phosphoric acid ester can be cited. As specific examples of condensed phosphoric acid ester, trialkyl polyphosphate, resorcinol polyphenyl phosphate, resorcinol poly (di-2,6-xylyl) phosphate, hydroquinone poly (2,6-xylyl) phosphate, etc. can be cited. As commercial products of condensed phosphoric acid ester, for example, "CR-733S" manufactured by Daihachi Chemical Industry Co., Ltd., "CR-741" manufactured by Daihachi Chemical Industry Co., Ltd., "FP-600" manufactured by ADEKA Co., Ltd., etc. can be cited.

[0092] Specific examples of the phosphazene-based compound include phenoxy cyclophosphazene ("FP-110" manufactured by Fushimi Pharmaceutical Co., Ltd.), cyclic cyanophenoxyphosphazene ("FP-300" manufactured by Fushimi Pharmaceutical Co., Ltd.), and the like.

[0093] Examples of the polyalkylene glycol include polypropylene glycol represented by the following general formula (8-1) and polyethylene glycol represented by the following general formula (8-2). In the following general formulas (8-1) and (8-2), n represents the degree of polymerization.

[0094]

[0095] In order to improve the compatibility with the polyamic acid (1), the number average degree of polymerization of the polyalkylene glycol is preferably 10 to 10,000, more preferably 10 to 6,000, and even more preferably 10 to 4,000.

[0096] Specific examples of aliphatic dibasic acid esters include dibutyl adipate, diisobutyl adipate, bis(2-ethylhexyl) adipate, diisononyl adipate, diisodecyl adipate, bis[2-(2-butoxyethoxy)ethyl] adipate, bis(2-ethylhexyl) azelaic acid, dibutyl sebacate, bis(2-ethylhexyl) sebacate, and diethyl succinate.

[0097] In addition, the plasticizer can be a low molecular weight organic compound or a thermoplastic resin as long as it exerts a plasticizing effect. As the above-mentioned low molecular weight organic compound, organic compounds with a molecular weight of about 1000 or less can be listed, for example, phenolic compounds; phthalimide compounds such as phthalimide, N-phenylphthalimide, N-glycidylphthalimide, N-hydroxyphthalimide, cyclohexylthiophthalimide, etc.; maleimide compounds such as N,N-paraphenylene bismaleimide, 2,2-(ethylenedioxy)bis(ethylmaleimide). As the above-mentioned thermoplastic resin, polyimide or polyamide with an asymmetric structure can be listed.

[0098] In order to further suppress the generation of hydrogen fluoride when used in a high-temperature process, the plasticizer is preferably a phosphite compound, more preferably a phosphite ester, and still more preferably triphenyl phosphite.

[0099] In order to obtain a polyimide with further reduced coloration, better transparency and heat resistance, and capable of further suppressing the generation of hydrogen fluoride in a high-temperature process, the polyamic acid composition of the present embodiment preferably satisfies the following condition 1, more preferably satisfies the following condition 2, further preferably satisfies the following condition 3, and further preferably satisfies the following condition 4.

[0100] Condition 1: The content of TFMB residues relative to all diamine residues constituting the polyamic acid (1) is 50 mol% to 100 mol%, and the polyamic acid (1) has one or more selected from the group consisting of PMDA residues, BPDA residues, BPAF residues, and ODPA residues.

[0101] Condition 2: The above condition 1 is satisfied, and the polyamic acid (1) has only a TFMB residue as a diamine residue, or has only a TFMB residue and a 4-BAAB residue as diamine residues.

[0102] Condition 3: The above condition 2 is satisfied, and the total content of the PMDA residue, the BPDA residue, the BPAF residue and the ODPA residue relative to all the acid dianhydride residues constituting the polyamic acid (1) is 100 mol%.

[0103] Condition 4: The above condition 3 is satisfied, and the plasticizer is a phosphorous acid-based compound.

[0104] The polyamic acid composition of the present embodiment may further contain an organic solvent in addition to containing polyamic acid (1) and a plasticizer. As the organic solvent contained in the polyamic acid composition, an organic solvent exemplified as an organic solvent that can be used for the synthesis reaction of the above-mentioned polyamic acid (1) can be cited, preferably one or more solvents selected from the group consisting of an amide solvent, a ketone solvent, an ester solvent and an ether solvent, more preferably an amide solvent (more specifically, DMF, DMAC, NMP, etc.). In the case of obtaining polyamic acid (1) by the above method, the solution itself to which a plasticizer is added in the reaction solution (solution after the reaction) can be used as the polyamic acid composition of the present embodiment. In addition, the solid polyamic acid (1) and the plasticizer obtained by removing the solvent from the reaction solution can also be dissolved in an organic solvent to prepare the polyamic acid composition of the present embodiment. It should be noted that the content of the polyamic acid (1) in the polyamic acid composition of the present embodiment is not particularly limited, for example, relative to the total amount of the polyamic acid composition, it is more than 1% by weight and less than 80% by weight.

[0105] The polyimide of the present embodiment is an imide of the above-mentioned polyamic acid (1). The polyimide of the present embodiment can be obtained by a known method, and its manufacturing method is not particularly limited. Below, an example of a method for obtaining the polyimide of the present embodiment by imidizing polyamic acid (1) is described. Imidization is carried out by dehydrating and ring-closing polyamic acid (1). The dehydration and ring-closing can be carried out by an azeotropic method, a thermal method or a chemical method using an azeotropic solvent. In addition, the imidization from polyamic acid (1) to polyimide can adopt any ratio of more than 1% and less than 100%. That is, a part of imidized polyamic acid (1) can be synthesized. In particular, when imidization is performed by heating, the ring-closure reaction from polyamic acid (1) to polyimide and the hydrolysis of polyamic acid (1) are performed simultaneously, and the molecular weight when the polyimide is prepared may be lower than the molecular weight of polyamic acid (1). Therefore, from the viewpoint of improving mechanical properties, it is preferred to imidize a part of the polyamic acid (1) in the polyamic acid composition before forming the polyimide film described later. In this specification, a part of the polyamic acid imidized is sometimes also recorded as "polyamic acid".

[0106] The dehydration ring closure of polyamic acid (1) is as long as polyamic acid (1) is heated. There is no particular restriction on the method of heating polyamic acid (1). For example, after applying the polyamic acid composition of the present embodiment (preferably a polyamic acid composition comprising polyamic acid (1), a plasticizer and an organic solvent) on a support such as a glass substrate, a metal plate, a PET film (polyethylene terephthalate film), etc., the heat treatment of polyamic acid (1) is performed within a temperature range of 40°C or more and 500°C or less. According to this method, a laminate of the present embodiment having a support and a polyimide film (specifically, a polyimide film containing an imide of polyamic acid (1)) arranged on the support can be obtained. Alternatively, the polyamic acid composition can be directly placed in a container subjected to a demoulding process such as coating with a fluorine-based resin, and the polyamic acid composition is heated and dried under reduced pressure to perform dehydration ring closure of polyamic acid (1). By utilizing the dehydration ring-closure of the polyamic acid (1) carried out by these methods, polyimide can be obtained. It should be noted that the heating time of each of the above-mentioned processes is different according to the treatment amount and the heating temperature of the polyamic acid composition for dehydration ring-closure, and is usually preferably set to the scope of more than 1 minute and less than 300 minutes after the treatment temperature reaches the maximum temperature. In addition, in order to shorten the heating time or show characteristics, an imidizing agent and / or a dehydration catalyst can be added to the polyamic acid composition, and the polyamic acid composition added with the imidizing agent and / or the dehydration catalyst is heated and imidized using the above method.

[0107] The imidizing agent is not particularly limited, and a tertiary amine can be used. As the tertiary amine, a heterocyclic tertiary amine is preferred. Preferred specific examples of the heterocyclic tertiary amine include pyridine, picoline, quinoline, isoquinoline, 1,2-dimethylimidazole, etc. Preferred specific examples of the dehydration catalyst include acetic anhydride, propionic anhydride, n-butyric anhydride, benzoic anhydride, trifluoroacetic anhydride, etc.

[0108] As the addition amount of the imidizing agent, relative to the amide group of polyamic acid (1), preferably 0.5 times of molar equivalent or more and 5.0 times of molar equivalent or less, more preferably 0.7 times of molar equivalent or more and 2.5 times of molar equivalent or less, more preferably 0.8 times of molar equivalent or more and 2.0 times of molar equivalent or less. In addition, as the addition amount of the dehydration catalyst, relative to the amide group of polyamic acid (1), preferably 0.5 times of molar equivalent or more and 10.0 times of molar equivalent or less, more preferably 0.7 times of molar equivalent or more and 5.0 times of molar equivalent or less, more preferably 0.8 times of molar equivalent or more and 3.0 times of molar equivalent or less. It should be noted that in this specification, "amide group of polyamic acid (1)" refers to the amide group generated by the polymerization reaction of diamine and tetracarboxylic dianhydride. When adding the imidizing agent and / or dehydration catalyst in the polyamic acid composition, it can be insoluble in an organic solvent and directly added, or a substance dissolved in an organic solvent can be added. In the method of adding directly without dissolving in an organic solvent, the reaction may proceed rapidly before the imidization agent and / or dehydration catalyst diffuses, and a gel may be formed. Therefore, it is preferred to add a solution obtained by dissolving the imidization agent and / or dehydration catalyst in an organic solvent to the polyamic acid composition.

[0109] The polyimide film of the present embodiment (specifically, the polyimide film containing the imide compound of polyamic acid (1)) is colorless and transparent and has a low yellow index, and has a glass transition temperature (heat resistance) that can withstand the TFT manufacturing process, and is therefore suitable for a transparent substrate material for a flexible display. Relative to the total amount of the polyimide film, the content of the polyimide (specifically, the imide compound of polyamic acid (1)) in the polyimide film of the present embodiment is, for example, 70% by weight or more, preferably 80% by weight or more, more preferably 90% by weight or more, and may also be 100% by weight. As components other than the polyimide in the polyimide film, for example, additives described later (more specifically, nano silica particles, etc.) may be cited.

[0110] The electronic device of this embodiment has the polyimide film of this embodiment and the electronic component arranged on the polyimide film. In the case of manufacturing the electronic device of this embodiment for a flexible display, first, an inorganic substrate such as glass is used as a support, and a polyimide film is formed thereon. Then, by configuring (forming) electronic components such as TFT on the polyimide film, an electronic device is formed on the support. The process of forming TFT is generally carried out in a wide temperature range of 150°C to 650°C, but in fact, in order to achieve the desired performance, an oxide semiconductor layer and an a-Si layer are formed at more than 300°C, and depending on the situation, a-Si is sometimes crystallized using a laser or the like.

[0111] At this time, if the thermal decomposition temperature of the polyimide film is low, degassing occurs during the formation of electronic components, and the sublimates adhere to the oven, which may cause contamination in the oven, or the inorganic film (barrier film described later, etc.) and electronic components formed on the polyimide film may peel off, so the 1% weight loss temperature of the polyimide is preferably above 500°C. The upper limit of the 1% weight loss temperature of the polyimide is as high as possible, for example, 520°C. The 1% weight loss temperature can be adjusted, for example, by changing the content of residues having a rigid structure (more specifically, TFMB residues, PMDA residues, BPDA residues, etc.). In more detail, before the TFT is formed, an inorganic film such as a silicon oxide film (SiOx film) and a silicon nitride film (SiNx film) is formed on the polyimide film as a barrier film. At this time, when the heat resistance of the polyimide is low, when imidization is not completely carried out, or when there is a lot of residual solvent, the polyimide and the inorganic film may be peeled off due to volatile components such as decomposition gas of the polyimide in the high-temperature process after the inorganic film is stacked. Therefore, it is ideal that in addition to the 1% weight loss temperature of the polyimide being 500° C. or higher, the weight loss rate of the polyimide when isothermally maintained at a temperature in the range of 400° C. to 450° C. is less than 1%.

[0112] In addition, when the glass transition temperature (Tg) of the polyimide is significantly lower than the process temperature, positional displacement may occur during the formation of the electronic component, so the Tg of the polyimide is preferably above 300°C, more preferably above 350°C, and further preferably above 400°C. The higher the upper limit of the Tg of the polyimide, the better, for example, 450°C. In addition, in general, the thermal expansion coefficient of the glass substrate is smaller than that of the resin, so internal stress is generated between the glass substrate and the polyimide film. If the internal stress of the laminate of the glass substrate, the electronic component and the polyimide film used as a support is high, the laminate containing the polyimide film expands in the high-temperature TFT formation process, and shrinks when cooled to room temperature, resulting in problems such as warping, breakage of the glass substrate, and peeling of the polyimide film from the glass substrate. Therefore, the internal stress generated in the laminate of the polyimide film and the glass substrate is preferably below 30MPa, more preferably below 25MPa, and further preferably below 20MPa.

[0113] The polyimide of the present embodiment can be used as a material for display substrates such as TFT substrates and touch panel substrates. When polyimide is used for the above-mentioned purposes, most of them adopt the method of peeling the polyimide film from the support after forming an electronic device on the support as described above (in detail, an electronic device with electronic components formed on the polyimide film). In addition, as a material for the support, alkali-free glass is preferably used. Below, an example of a method for manufacturing a laminate of a polyimide film and a support is described in detail.

[0114] First, the polyamic acid composition of the present embodiment (preferably a polyamic acid composition comprising polyamic acid (1), a plasticizer and an organic solvent) is coated on a support to form a coating film-containing laminate composed of a coating film comprising polyamic acid (1) and a plasticizer and a support. Next, the laminate containing the coating film is heated, for example, under conditions of a temperature of 40°C or more and 200°C or less. The heating time at this time is, for example, 3 minutes or more and 120 minutes or less. It should be noted that, for example, a heating process of multiple stages may be provided, such as heating the laminate containing the coating film 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 imidize the polyamic acid (1) in the coating film, the laminate containing the coating film is heated, for example, under conditions of a maximum temperature of 200°C or more and 500°C or less. The heating time at this time (heating time at the maximum temperature) is, for example, 1 minute or more and 300 minutes or less. At this time, it is preferred to slowly heat up from a low temperature to a maximum temperature. The heating rate is preferably 2°C / min or more and 10°C / min or less, more preferably 4°C / min or more and 10°C / min or less. In addition, the maximum temperature is preferably in the range of 250°C or more and 450°C or less. If the maximum temperature is above 250°C, imidization is fully carried out, and if the maximum temperature is below 450°C, thermal degradation and coloring of the polyimide can be suppressed. In addition, any time can be maintained at any temperature before reaching the maximum temperature. The imidization reaction can be carried out in air, under reduced pressure or in an inert gas such as nitrogen, but in order to show higher transparency, it is preferably carried out under reduced pressure or in an inert gas such as nitrogen. In addition, as a heating device, a known device such as a hot air oven, an infrared oven, a vacuum oven, an inert oven, a heating plate, etc. can be used. Through these steps, the polyamic acid (1) in the coating film is imidized, and a laminate (i.e., the laminate of the present embodiment) of a support and a polyimide film (a film containing an imide product of the polyamic acid (1)) can be obtained. In addition, in order to shorten the heating time and exhibit the characteristics, an imidizing agent and a dehydration catalyst can be added to the polyamic acid composition, and the solution can be heated by the above method to perform imidization.

[0115] The method for peeling off the polyimide film from the obtained support and the laminated body of the polyimide film can use a known method. For example, it can be peeled off by hand, or it can be peeled off using mechanical devices such as drive rollers and robots. Further, it is also possible to adopt a method in which a peeling layer is provided between the support and the polyimide film, a silicon oxide film is formed on a substrate having a plurality of grooves, and a polyimide film is formed using the silicon oxide film as a base layer, so that the etching solution of silicon oxide is infiltrated between the substrate and the silicon oxide film, thereby the method of peeling off the polyimide film. In addition, it is also possible to adopt a method in which the polyimide film is separated by irradiation of a laser.

[0116] If there is floating at the interface of polyimide film and support body (such as glass substrate), there is the worry that the yield rate is reduced when the polyimide film is peeled off in the formation of electronic components and the polyimide film is peeled off after the electronic components are formed. It should be noted that "floating" refers to the state of poor adhesion between polyimide film and other material layers (more specifically, glass substrate, barrier film, etc.) due to the byproducts (more specifically, hydrogen fluoride, etc.) produced during imidization and residual solvent. As specific "floating", the state of polyimide film floating from glass substrate, the state of interlayer peeling between polyimide film and other material layers produced by a part of polyimide film being destroyed, and the state of barrier film floating from polyimide film, etc. can be cited. The polyamic acid composition of the present embodiment can suppress the generation of hydrogen fluoride when the obtained polyimide is used in a high temperature process, so the generation of floating can be suppressed.

[0117] The transparency of the polyimide film can be evaluated by the total light transmittance (TT) based on JIS K7361-1:1997 and the haze based on JIS K7136-2000. When the polyimide film is used in applications requiring high transparency, the total light transmittance of the polyimide film is preferably 75% or more, and more preferably 80% or more. In addition, when the polyimide film is used in applications requiring high transparency, the haze of the polyimide film is preferably 1.5% or less, more preferably 1.2% or less, further preferably less than 1.0%, and may also be 0%. In applications requiring high transparency, the polyimide film requires high transmittance in the entire wavelength region, but the polyimide film has a tendency to easily absorb light on the short wavelength side, and the film itself is mostly colored yellow. In order to use the polyimide film in applications requiring high transparency, it is preferred to reduce the coloring of the polyimide film. Specifically, in order to use the polyimide film in applications requiring high transparency, the yellowness index (YI) of the polyimide film is preferably 20 or less, more preferably 18 or less, further preferably 15 or less, further preferably 12 or less, particularly preferably 8 or less, and may be 0. YI can be measured in accordance with JIS K7373-2006. YI can be adjusted, for example, by changing the content of TFMB residues in the polyamic acid (1). The polyimide film with reduced coloration and imparted transparency is suitable for transparent substrates for glass replacement applications, etc., and substrates having sensors or camera modules disposed on the back.

[0118] In addition, there are two light extraction methods for flexible displays: a top emission method that extracts light from the TFT side and a bottom emission method that extracts light from the back side of the TFT. In the top emission method, since the light is not blocked by the TFT, it has the characteristics of easily increasing the aperture ratio and obtaining high-definition image quality. The bottom emission method has the characteristics of being easy to align the positions of the TFT and the pixel electrode and easy to manufacture. If the TFT is transparent, the aperture ratio can be increased even in the bottom emission method, so there is a tendency to adopt the bottom emission method that is easy to manufacture in large displays. The polyimide film of this embodiment has a low YI and excellent heat resistance, so it can also be applied to any of the above-mentioned light extraction methods.

[0119] In addition, a polyamic acid composition is applied on a support such as a glass substrate, heated and imidized, and in a batch device manufacturing process such as a polyimide film is peeled off after forming an electronic component, etc., it is preferred that the adhesion between the support and the polyimide film is excellent. Adhesion described herein refers to adhesion strength. After forming an electronic component, etc. on the polyimide film on the support, the polyimide film formed with the electronic component, etc. is peeled off from the support in the manufacturing process, if the polyimide film and the support have excellent adhesion, then the electronic component, etc. can be formed or installed more accurately. In the manufacturing process of configuring the electronic component, etc. across the polyimide film on the support, from the viewpoint of improving productivity, the peel strength between the support and the polyimide film is the higher the better. Specifically, the above-mentioned peel strength is preferably more than 0.05N / cm, more preferably more than 0.1N / cm.

[0120] In the manufacturing process as described above, when the polyimide film is peeled off from the laminate of the support and the polyimide film, the polyimide film is peeled off from the support by laser irradiation in most cases. At this time, it is necessary to make the polyimide film absorb the laser, so the cut-off wavelength of the polyimide film is required to be a wavelength longer than the wavelength of the laser used in the peeling. Laser peeling mostly uses a XeCl excimer laser with a wavelength of 308nm, so the cut-off wavelength of the polyimide film is preferably more than 312nm, more preferably more than 330nm. On the other hand, if the cut-off wavelength is a long wavelength, there is a tendency for the polyimide film to be colored yellow, so the cut-off wavelength of the polyimide film is preferably less than 390nm. From the viewpoint of both transparency (low yellowness) and the processability of laser peeling, the cut-off wavelength of the polyimide film is preferably more than 320nm and less than 390nm, more preferably more than 330nm and less than 380nm. It should be noted that the cutoff wavelength in this specification refers to a wavelength at which the transmittance is 0.1% or less as measured by an ultraviolet-visible spectrophotometer.

[0121] The polyamic acid composition and polyimide of the present embodiment can be directly used in the coating and molding process for making products and components, and can also be used as a material for further coating and other treatments on a film-shaped molded product. In order to be used in the coating or molding process, the polyamic acid composition or polyimide can be dissolved or dispersed in an organic solvent as required, and then, a photocurable component, a thermosetting component, a non-polymerizable binder resin and other components are mixed as required to prepare a composition containing polyamic acid (1) or polyimide.

[0122] In order to give processing characteristics and various functionalities to the polyamic acid composition and polyimide of the present embodiment, as additives, various organic or inorganic low molecular compounds or polymer compounds can be mixed. As additives, for example, dyes, surfactants, leveling agents, plasticizers, organosilicon, microparticles, sensitizers, etc. can be used. Microparticles include organic microparticles formed by polystyrene, polytetrafluoroethylene, etc., inorganic microparticles formed by colloidal silicon dioxide, carbon, layered silicates, etc., and they can be porous structures, hollow structures. In addition, the function and form of microparticles are not particularly limited, for example, can be pigments, can also be fillers, can also be fibrous particles.

[0123] In order to improve the heat resistance while maintaining the transparency of the polyimide film, nano-silica particles can also be used as the above-mentioned additive, and polyamic acid (1) and nano-silica particles are composited. From the viewpoint of maintaining the transparency of the polyimide film, the average primary particle size of the nano-silica particles is preferably less than 200nm, more preferably less than 100nm, further preferably less than 50nm, and can also be less than 30nm. On the other hand, from the viewpoint of ensuring the dispersibility in the polyamic acid (1), the average primary particle size of the nano-silica particles is preferably more than 5nm, more preferably more than 10nm. As a method for composite polyamic acid (1) with nano-silica particles, a known method can be used, for example, a method of using an organosilica sol formed by dispersing nano-silica particles in an organic solvent can be cited. As a method for compounding polyamic acid (1) and nano-silica particles using an organic silica sol, a method can be used in which, after synthesizing polyamic acid (1), the synthesized polyamic acid (1) is mixed with the organic silica sol. However, in order to disperse the nano-silica particles in the polyamic acid (1) to a higher degree, it is preferred to synthesize the polyamic acid (1) in an organic silica sol.

[0124] In addition, in order to improve the interaction with polyamic acid (1), the nano silicon dioxide particles can also be surface treated with a surface treatment agent. As a surface treatment agent, a known surface treatment agent such as a silane coupling agent can be used. As a silane coupling agent, alkoxysilane compounds having amino or glycidyl groups as functional groups are widely known and can be appropriately selected. In order to further improve the interaction with polyamic acid (1), as a silane coupling agent, an amino-containing alkoxysilane is preferably used. As an example of an amino-containing alkoxysilane, 3-aminopropyl trimethoxysilane, 3-aminopropyl triethoxysilane, 3-aminopropyl methyl dimethoxysilane, 3-aminopropyl methyl diethoxysilane, 3-(2-aminoethyl) aminopropyl trimethoxysilane, 3-phenylaminopropyl trimethoxysilane, 2-aminophenyl trimethoxysilane and 3-aminophenyl trimethoxysilane, etc. can be cited. From the viewpoint of the stability of the raw material, 3-aminopropyl triethoxysilane is preferably used. As a surface treatment method for nano-silica particles, a method of stirring a mixture of a silane coupling agent added to a dispersion (organic silica sol) at an ambient temperature of 20° C. to 80° C. can be cited. The stirring time at this time is, for example, 1 hour to 10 hours. At this time, a catalyst that promotes the reaction can be added.

[0125] In the nano-silica-polyamic acid composite formed by compounding polyamic acid (1) with nano-silica particles, the content of nano-silica particles is preferably in the range of 1 part by weight or more and 30 parts by weight or less, and more preferably in the range of 1 part by weight or more and 20 parts by weight or less, relative to 100 parts by weight of polyamic acid (1). If the content of 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 fully reduced. If the content of nano-silica particles is 30 parts by weight or less, the adverse effects on the mechanical properties and transparency of the polyimide containing nano-silica particles can be suppressed.

[0126] In the polyamic acid composition of the present embodiment, as the above-mentioned additive for imparting functionality, imidazoles can also be added. In this specification, imidazoles refer to compounds with 1,3-oxadiazole rings (1,3-oxadiazole ring structures). As imidazoles added to the polyamic acid composition of the present embodiment, there is no particular limitation, and examples thereof include 1H-imidazole, 2-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-methylimidazole, 1-benzyl-2-phenylimidazole, etc. Among them, preferably 1,2-dimethylimidazole, 1-benzyl-2-methylimidazole, 1-benzyl-2-phenylimidazole, more preferably 1,2-dimethylimidazole, 1-benzyl-2-methylimidazole.

[0127] Relative to 1 mole of the amide group of polyamic acid (1), the content of imidazoles is preferably more than 0.005 mole and less than 0.1 mole, more preferably more than 0.01 mole and less than 0.08 mole, further preferably more than 0.015 mole and less than 0.050 mole.By containing more than 0.005 mole of imidazoles, the film strength and transparency of polyimide can be improved, by setting the content of imidazoles to less than 0.1 mole, it is possible to improve Tg, heat resistance while maintaining the storage stability of polyamic acid (1).If the improvement of transparency is explained, the known polymerization solvent such as NMP forms a complex with the carboxyl group of polyamic acid (1) by hydrogen bond, and when imidization speed is slow, NMP etc. remain in the polyimide film, and it is possible to become the cause of coloring due to oxidation and decomposition. It is believed that when imidazoles are added, imidazoles coordinate with the carboxyl group of polyamic acid (1) to promote imidization, so NMP etc. are not easy to remain in the polyimide film, and the decomposition of polyamic acid (1) in the thermal imidization process is also suppressed, so the transparency is improved. According to the polyamic acid composition of the present embodiment, by using a plasticizer, sufficient molecular motion can be given during the imidization of polyamic acid (1), therefore, imidazoles may not be used in the present embodiment.

[0128] The mixing method of polyamic acid (1) and imidazoles is not particularly limited. From the viewpoint of the ease of molecular weight control of polyamic acid (1), it is preferred to add imidazoles to the polyamic acid (1) after polymerization. At this time, imidazoles can be directly added to polyamic acid (1), or imidazoles can be dissolved in a solvent in advance and the solution can be added to polyamic acid (1), and the adding method is not particularly limited. It is also possible to add imidazoles and plasticizers to a solution (reacted solution) containing polyamic acid (1) after polymerization to prepare the polyamic acid composition of the present embodiment.

[0129] The polyamic acid composition of the present embodiment may contain a silane coupling agent in order to exhibit appropriate adhesion to a support. The type of the silane coupling agent may be any known silane coupling agent, and amino group-containing compounds are particularly preferred from the viewpoint of reactivity with the polyamic acid (1).

[0130] The blending ratio of the silane coupling agent to 100 parts by weight of the polyamic acid (1) is preferably 0.01 parts by weight or more and 0.50 parts by weight or less, more preferably 0.01 parts by weight or more and 0.10 parts by weight or less, and further preferably 0.01 parts by weight or more and 0.05 parts by weight or less. By setting the blending ratio of the silane coupling agent to 0.01 parts by weight or more, the peeling-inhibiting effect on the support can be fully exerted, and by setting the blending ratio of the silane coupling agent to 0.50 parts by weight or less, the molecular weight reduction of the polyamic acid (1) can be suppressed, thereby suppressing the embrittlement of the polyimide film.

[0131] Various inorganic thin films such as metal oxide thin films and transparent electrodes can be formed on the surface of the polyimide film of this embodiment. The film-forming methods of these inorganic thin films are not particularly limited, and examples thereof include PVD methods such as sputtering, vacuum evaporation, and ion plating, and CVD methods.

[0132] The polyimide film of the present embodiment has small internal stress when forming a laminate with a glass substrate in addition to heat resistance, low thermal expansion and transparency, and can ensure the adhesion with inorganic materials in high temperature processes, so it is preferably used in fields and products where these characteristics are considered to be effective. For example, the polyimide film of the present embodiment is preferably used for 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 film substrates, solar cells, etc., and further, more preferably as an alternative material for the part currently using glass. In these uses, the thickness of the polyimide film is, for example, more than 1 μm and less than 200 μm, preferably more than 5 μm and less than 100 μm. The thickness of the polyimide film can be measured using a laser holographic micrometer.

[0133] In addition, the polyamic acid composition of the present embodiment can be applied to the following batch device manufacturing process: the polyamic acid composition is coated on the support, heated and imidized, and after the electronic components are formed, the polyimide film is peeled off. Therefore, the present embodiment also includes a method for manufacturing an electronic device including the following steps: the polyamic acid composition is coated on the support, heated and imidized, and the electronic components are formed on the polyimide film formed on the support. In addition, the method for manufacturing the electronic device can further include the step of peeling off the polyimide film formed with the electronic components from the support.

[0134] Example

[0135] Hereinafter, examples of the present invention will be described, but the scope of the present invention is not limited to the following examples.

[0136] <Methods for measuring physical properties and evaluating adhesion>

[0137] First, a method for measuring the physical properties of a polyimide (polyimide film) and a method for evaluating the adhesiveness will be described.

[0138] [Yellow Index (YI)]

[0139] For the polyimide film in each laminate obtained in the examples and comparative examples described later, the transmittance of light with a wavelength of 200 nm or more and 800 nm or less was measured using an ultraviolet-visible-near-infrared spectrophotometer ("V-650" manufactured by JASCO Corporation), and the yellow index (YI) of the polyimide film was calculated by the formula described in JIS K7373-2006. When the YI is 20 or less, it is evaluated as "the coloring of the polyimide film can be reduced". On the other hand, when the YI exceeds 20, it is evaluated as "the coloring of the polyimide film cannot be reduced".

[0140] [Haze]

[0141] The haze of the polyimide film peeled off from each laminate obtained in the examples and comparative examples described below was measured using an integrating sphere haze meter ("HM-150N" manufactured by Murakami Color Research Laboratory Co., Ltd.) by the method described in JIS K7136-2000. When the haze was less than 1.0%, it was evaluated as "excellent transparency". On the other hand, when the haze was 1.0% or more, it was evaluated as "not excellent transparency".

[0142] [Internal stress]

[0143] On a glass substrate (material: alkali-free glass, thickness: 0.7mm, size: 100mm×100mm) made by Corning Inc., the amount of warpage was measured in advance, and each polyamic acid composition prepared in the embodiments and comparative examples described later was applied with a spin coater, and heated at 120°C for 30 minutes in air, and then heated at 430°C for 30 minutes in a nitrogen environment to obtain a laminate having a polyimide film with a thickness of 10 μm on a glass substrate. In order to eliminate the influence of water absorption of the polyimide film, the laminate was dried at 120°C for 10 minutes, and the amount of warpage of the laminate under a nitrogen environment at a temperature of 25°C was measured using a thin film stress measuring device ("FLX-2320-S" made by KLA-Tencor). Then, the internal stress generated between the glass substrate and the polyimide film was calculated by the Stoney formula from the amount of warpage of the glass substrate before the polyimide film was formed and the amount of warpage of the laminate.

[0144] [Glass transition temperature (Tg)]

[0145] The polyimide film obtained by sampling each laminate obtained from the embodiments and comparative examples described later with a width of 3 mm and a length of 10 mm was used as a sample for Tg determination. Using a thermal analyzer ("TMA / SS7100" manufactured by Hitachi High-Tech Science Corporation), a load of 98.0 mN was applied to the sample, and the temperature was raised from 20°C to 450°C at 10°C / min, and the temperature and strain (elongation) were plotted to obtain a 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 used as the glass transition temperature (Tg). When Tg is above 350°C, it is evaluated as "excellent heat resistance". On the other hand, when Tg is less than 350°C, it is evaluated as "not excellent heat resistance".

[0146] [1% weight loss temperature (TD1)]

[0147] The polyimide films obtained in the examples and comparative examples described later (specifically, polyimide films sampled from each laminate with a weight of 10 mg) were used as samples for measurement. A differential thermal and thermogravimetric simultaneous measurement apparatus ("TG / DTA7200" manufactured by Hitachi High-Tech Science Corporation) was used. The temperature was raised from 25°C to 650°C at 20°C / min under a nitrogen environment. The weight of the sample at a measurement temperature of 150°C was used as a reference, and the measurement temperature when the weight was reduced by 1% by weight relative to the reference was taken as the 1% weight loss temperature (TD1).

[0148] [Whether there is any lifting between the glass substrate and the polyimide film]

[0149] Each polyamic acid composition prepared in the following examples and comparative examples was applied by a spin coater on a glass substrate (material: alkali-free glass, thickness: 0.7 mm, size: 100 mm×100 mm) manufactured by Corning Incorporated, and heated at 120° C. for 30 minutes in air, and then heated at 430° C. for 30 minutes in a nitrogen environment to obtain a laminate having a polyimide film having a thickness of 10 μm on the glass substrate. For the obtained laminate, the presence or absence of floating between the glass substrate and the polyimide film was visually confirmed.

[0150] [SiO x Whether there is floating between the film and the polyimide film]

[0151] On a glass substrate (material: alkali-free glass, thickness: 0.7 mm, size: 100 mm×100 mm) manufactured by Corning, each polyamic acid composition prepared in the examples and comparative examples described below was applied by a spin coater, and then heated at 120° C. for 30 minutes in air, and then heated at 430° C. for 30 minutes in a nitrogen atmosphere, to form a polyimide film having a thickness of 10 μm on the glass substrate. Next, SiO x The obtained laminate was heated under a nitrogen atmosphere under the heating conditions shown in Table 4 described below. Then, the SiO x The presence or absence of floating between the film and the polyimide film. x Check whether there is any floating between the film and the polyimide film.

[0152] [Analysis of Gas Emitted from Polyimide Film]

[0153] The gas generated from the polyimide film during heating was analyzed using an analysis device in which a thermogravimetric analyzer (“STA449F5” manufactured by NETZSCH) and a quadrupole mass spectrometer (“JMS-Q1500GC” manufactured by JEOL Ltd.) were combined. The analysis procedure is described below.

[0154] First, using perfluorotributylamine as a standard substance, the voltage of the quadrupole mass spectrometer is adjusted so that the detection intensity of the peak of m / z=69 reaches 800000. Next, using the thermogravimetric measuring device, each polyimide film obtained in the following examples and comparative examples (in detail, a polyimide film sampled from each laminate with a mass of 140 mg) is heated from an ambient temperature of 60°C at a heating rate of 10°C / min under a helium gas flow of 100 mL / min, and the gas generated from the polyimide film when the ambient temperature reaches 470°C is analyzed using the quadrupole mass spectrometer. It should be noted that by using the above-mentioned analysis device to heat the polyimide film under a helium gas flow, the helium becomes a carrier gas, and the gas generated from the polyimide film can be analyzed in real time using the quadrupole mass spectrometer. Then, the gas generated from the polyimide film when the ambient temperature reaches 470°C is analyzed by the quadrupole mass spectrometer, and the detection intensity of the peak of m / z=20 (20 peak intensity) is read from the obtained mass spectrum. When the 20 peak intensity is 60,000 or less, it is evaluated as "the generation of hydrogen fluoride can be suppressed in the high temperature process". On the other hand, when the 20 peak intensity exceeds 60,000, it is evaluated as "the generation of hydrogen fluoride cannot be suppressed in the high temperature process".

[0155] <Production of Polyimide Film>

[0156] The following is a description of the methods for preparing the polyimide films (laminated bodies) of the examples and comparative examples. It should be noted that the compounds and reagents are described below using the following abbreviations. In addition, the preparation of the polyamic acid solution used in the preparation of the polyimide film was carried out under a nitrogen atmosphere.

[0157] NMP: N-methyl-2-pyrrolidone

[0158] PMDA: Pyromellitic Dianhydride

[0159] BPAF: 9,9-bis(3,4-dicarboxyphenyl)fluorene anhydride

[0160] BPDA: 3,3',4,4'-biphenyltetracarboxylic dianhydride

[0161] ODPA: 4,4'-oxydiphthalic anhydride

[0162] 4-BAAB: 4-aminophenyl-4-aminobenzoate

[0163] PDA: p-phenylenediamine

[0164] TFMB: 2,2'-bis(trifluoromethyl)benzidine

[0165] ODA: 4,4'-oxydiphenylamine

[0166] TPP: Triphenyl phosphate

[0167] TMP: Trimethyl phosphate

[0168] DEPi: diethyl phosphite

[0169] TPPi: triphenyl phosphite

[0170] PEP-36: 3,9-bis(2,6-di-tert-butyl-4-methylphenoxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane

[0171] 3010: Triisodecyl phosphite

[0172] PX-200: Resorcinol poly(di-2,6-xylyl) phosphate

[0173] CR-741: Condensed phosphate ester ("CR-741" manufactured by Daihachi Chemical Industry)

[0174] DBA: Dibutyl adipate

[0175] BXA-N: Bis[2-(2-butoxyethoxy)ethyl adipate]

[0176] PEG600: Polyethylene glycol (average molecular weight 560-640)

[0177] [Preparation of polyamic acid solution]

[0178] (Preparation of polyamic acid solution PA-2)

[0179] In a 300 mL glass detachable flask equipped with a stirrer with a stainless steel stirring rod and a nitrogen inlet tube, 40.0 g of NMP was added as an organic solvent for polymerization. Then, while stirring the contents of the flask, 5.453 g of TFMB was added to the flask to dissolve it. Then, after adding 2.439 g of PMDA, 0.788 g of BPAF and 1.265 g of BPDA to the contents of the flask, the contents of the flask were stirred for 24 hours at a temperature of 25 ° C to obtain a polyamic acid solution PA-2.

[0180] (Preparation of polyamic acid solutions PA-1 and PA-3 to PA-10)

[0181] Polyamic acid solutions PA-1 and PA-3 to PA-10 were prepared respectively by the same method as polyamic acid solution PA-2, except that the acid dianhydride used and its charging ratio, the diamine used and its charging ratio, and the ratio of the total amount of diamine used to the total amount of acid dianhydride used were set as shown in Table 1. It should be noted that, for any of polyamic acid solutions PA-1 and PA-3 to PA-10, the total amount of acid dianhydride was the same as that of polyamic acid solution PA-2.

[0182] It should be noted that in Table 1, "-" means that the component is not used. In addition, in Table 1, the numerical value in the "acid dianhydride" column is the content of each acid dianhydride relative to the total amount of acid dianhydrides used (unit: mol %). In Table 1, the numerical value in the "diamine" column is the content of each diamine relative to the total amount of diamines used (unit: mol %). In Table 1, "ratio" refers to the ratio of the total amount of diamines used to the total amount of acid dianhydrides used (total amount of diamines / total amount of acid dianhydrides). In addition, with respect to any one of the polyamic acid solutions PA-1 to PA-10, the molar fraction of each residue of the polyamic acid in the prepared polyamic acid solution is consistent with the molar fraction of each monomer (diamine and tetracarboxylic dianhydride) used in the synthesis of the polyamic acid.

[0183] Table 1:

[0184]

[0185] [Example 1]

[0186] Under nitrogen environment, TMP as plasticizer is added in polyamic acid solution PA-1, the mixture obtained is stirred for 5 minutes, and polyamic acid composition is obtained. Relative to 100 weight parts of polyamic acid in polyamic acid solution PA-1, the addition amount of TMP is 1 weight part. Spin coater is used to apply the obtained polyamic acid composition on glass substrate (Corning company system, material: alkali-free glass, thickness: 0.7mm, size: 100mm×100mm), after heating at 120°C for 30 minutes in air, under nitrogen environment, heating at 430°C for 30 minutes, obtain the laminated body of polyimide film having thickness 10 μm on glass substrate.

[0187] [Examples 2 to 20 and Comparative Examples 1 to 10]

[0188] The type of polyamic acid solution used, the type of plasticizer used and the amount added are shown in Table 2. In addition, a laminate having a polyimide film with a thickness of 10 μm on a glass substrate was obtained by the same method as in Example 1. It should be noted that in Table 2, "-" means that no plasticizer is used. Therefore, in Comparative Examples 1 to 10, polyamic acid solutions PA-1 to PA-10 are used as polyamic acid compositions, respectively. In addition, in Table 2, the amount of plasticizer added is the amount added relative to 100 parts by weight of polyamic acid in the polyamic acid solution used (unit: parts by weight).

[0189] Table 2:

[0190]

[0191] <Physical properties and evaluation results>

[0192] The physical properties and evaluation results of Examples 1 to 20 and Comparative Examples 1 to 10 are shown in Tables 3 and 4, respectively. It should be noted that in Table 3, "-" means not measured. In addition, in Table 3, "whether there is floating between the glass substrate" means whether there is floating between the glass substrate and the polyimide film. In addition, in Table 4, "whether there is floating between the glass substrate and the polyimide film" means whether there is floating between the glass substrate and the polyimide film. x Whether there is floating between the films is SiO x Check whether there is any floating between the film and the polyimide film.

[0193] in addition, Figure 1 The results of analyzing the gas generated from the polyimide membrane using a quadrupole mass spectrometer according to the method described in the above-mentioned [Analysis of Gas Generated from Polyimide Membrane] for Example 18 and Comparative Example 5 are shown in FIG. Figure 1 In the figure, the vertical axis represents the detection intensity and the horizontal axis represents the temperature (ambient temperature). Figure 1In FIG. 1 , the solid line represents the change in the detection intensity of the peak at m / z=20 in Comparative Example 5, and the dotted line represents the change in the detection intensity of the peak at m / z=20 in Example 18. Figure 1 As shown, it can be seen that Example 18 has a smaller detection intensity of the peak at m / z=20 near the ambient temperature of 470° C. than Comparative Example 5, and thus the generation of hydrogen fluoride can be suppressed when used in a high-temperature process.

[0194] Table 3:

[0195]

[0196] Table 4:

[0197]

[0198] As described above, in Examples 1 to 20 using the polyamic acid composition containing the polyamic acid having the structural unit (1) and a plasticizer, all of the following conditions (1) to (6) were satisfied.

[0199] (1) YI is 20 or less.

[0200] (2) The haze is less than 1.0%.

[0201] (3) The internal stress is less than 30 MPa.

[0202] (4) Tg is 350°C or higher.

[0203] (5) TD1 is 500°C or higher.

[0204] (6) The 20 peak intensity is less than 60,000.

[0205] In Comparative Examples 1 to 7, the 20 peak intensity exceeds 60,000. Therefore, the polyimide films obtained in Comparative Examples 1 to 7 cannot suppress the generation of hydrogen fluoride in the high temperature process. In Comparative Examples 8 and 9, Tg is less than 350°C. Therefore, the polyimide films obtained in Comparative Examples 8 and 9 do not have excellent heat resistance. In Comparative Example 10, YI exceeds 20. Therefore, the coloring of the polyimide film obtained in Comparative Example 10 is not reduced.

[0206] The above results show that the polyimide obtained from the polyamic acid composition of the present invention has low coloring, excellent transparency and heat resistance, and can suppress the generation of hydrogen fluoride in a high-temperature process.

Claims

1. A polyamic acid composition comprising a polyamic acid and a plasticizer, wherein the polyamic acid comprises a structural unit represented by the following general formula (1): In the general formula (1), R 1 and R 2 each independently represents a hydrogen atom, a monovalent aliphatic group or a monovalent aromatic group, X includes a tetravalent organic group represented by the following chemical formula (4), and includes one or more selected from the group consisting of a tetravalent organic group represented by the following chemical formula (2), a tetravalent organic group represented by the following chemical formula (3), and a tetravalent organic group represented by the following chemical formula (5), The content of the tetravalent organic group represented by the chemical formula (4) is 5 mol% or more and 30 mol% or less relative to all tetracarboxylic dianhydride residues constituting the polyamic acid, The amount of the plasticizer is 0.05 parts by weight or more and 5 parts by weight or less relative to 100 parts by weight of the polyamic acid. The plasticizer is one or more selected from the group consisting of triphenyl phosphate, trimethyl phosphate, diethyl phosphite, triphenyl phosphite, 3,9-bis(2,6-di-tert-butyl-4-methylphenoxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane, triisodecyl phosphite, resorcinol poly(di-2,6-xylyl) phosphate, condensed phosphate, dibutyl adipate, bis[2-(2-butoxyethoxy)ethyl adipate], and polyethylene glycol. The total content of the tetravalent organic group represented by the chemical formula (2), the tetravalent organic group represented by the chemical formula (3), the tetravalent organic group represented by the chemical formula (4), and the tetravalent organic group represented by the chemical formula (5) is 100 mol % relative to all tetracarboxylic dianhydride residues constituting the polyamic acid. The polyamic acid has only a 2,2'-bis(trifluoromethyl)benzidine residue as a diamine residue, or has only a 2,2'-bis(trifluoromethyl)benzidine residue and a 4-aminobenzoic acid-4-aminophenyl ester residue as a diamine residue, When the polyamic acid has a 4-aminobenzoic acid-4-aminophenyl ester residue as a diamine residue, the content of the 4-aminobenzoic acid-4-aminophenyl ester residue is 20 mol% or more and 70 mol% or less relative to all diamine residues constituting the polyamic acid.

2. The polyamic acid composition according to claim 1, wherein In the general formula (1), R 1 and R 2 Both represent hydrogen atoms.

3. The polyamic acid composition according to claim 1 or 2, wherein The content of the structural unit represented by the general formula (1) is 50 mol% or more and 100 mol% or less based on all the structural units of the polyamic acid.

4. The polyamic acid composition according to claim 1, wherein The polyamic acid has a tetravalent organic group represented by the chemical formula (2), The content of the tetravalent organic group represented by the chemical formula (2) is 40 mol% or more and 90 mol% or less based on all tetracarboxylic dianhydride residues constituting the polyamic acid.

5. The polyamic acid composition according to claim 1, wherein The polyamic acid has a tetravalent organic group represented by the chemical formula (3), The content of the tetravalent organic group represented by the chemical formula (3) is 10 mol% or more and 90 mol% or less based on all tetracarboxylic dianhydride residues constituting the polyamic acid. The polyamic acid composition according to claim 1 or 2, further comprising an organic solvent. 7 . A polyimide, which is an imidate of the polyamic acid contained in the polyamic acid composition according to claim 1 . The polyimide according to claim 7, which has a 1% weight loss temperature of 500°C or higher. 9 . A polyimide film comprising the polyimide according to claim 7 or 8 . 10 . The polyimide film according to claim 9 , which has a yellowness index of 20 or less. 11 . A laminate comprising a support and the polyimide film according to claim 9 or 10.

12. A method for producing a laminated body, which is a method for producing a laminated body having a support and a polyimide film, wherein: The polyamic acid composition according to claim 6 is applied onto a support to form a coating film containing the polyamic acid and the plasticizer, and the coating film is heated to imidize the polyamic acid. 13 . An electronic device comprising the polyimide film according to claim 9 or 10 and an electronic element disposed on the polyimide film.

14. A method for manufacturing an electronic device, wherein: The method comprises coating the polyamic acid composition according to claim 6 on a support to form a coating film comprising the polyamic acid. The polyamic acid is imidized by heating the coating film to form a polyimide film, forming electronic components on the polyimide film, The polyimide film on which the electronic element is formed is peeled off from the support.

Images