阅读说明：本技术 柔性器件基板形成用聚酰亚胺前体树脂组合物 (Polyimide precursor resin composition for forming flexible device substrate ) 是由 三浦则男 成田一贵 中山刚成 于 2018-12-27 设计创作，主要内容包括：本发明涉及一种柔性器件基板形成用聚酰亚胺前体树脂组合物,其包含聚酰胺酸,该聚酰胺酸具有由满足下述式(1)和下述式(2)的成分得到的结构,该成分为：包含3,3’,4,4’-联苯四羧酸二酐和均苯四酸二酐中的至少一者的四羧酸成分；包含对苯二胺和4,4’-二氨基二苯基醚中的至少一者的二胺成分；和羧酸单酸酐。式(1)0.97≤X/Y＜1.00式(2)0.5≤(Z/2)/(Y－X)≤1.05(式中,X表示上述四羧酸成分的摩尔数,Y表示上述二胺成分的摩尔数,Z表示上述羧酸单酸酐的摩尔数。)。(The present invention relates to a polyimide precursor resin composition for forming a flexible device substrate, comprising a polyamic acid having a structure obtained from a component satisfying the following formula (1) and formula (2): a tetracarboxylic acid component containing at least one of 3,3 ', 4, 4' -biphenyltetracarboxylic dianhydride and pyromellitic dianhydride; a diamine component comprising at least one of p-phenylenediamine and 4, 4' -diaminodiphenyl ether; and carboxylic acid monoanhydrides. X/Y is 0.97-1.00 in the formula (1) (Z/2)/(Y-X) is 0.5-1.05 (X represents the number of moles of the tetracarboxylic acid component, Y represents the number of moles of the diamine component, and Z represents the number of moles of the carboxylic acid monoanhydride).)

1. A polyimide precursor resin composition for forming a flexible device substrate, comprising a polyamic acid having a structure obtained from a component satisfying the following formula (1) and the following formula (2), the component being: a tetracarboxylic acid component containing at least one of 3,3 ', 4, 4' -biphenyltetracarboxylic dianhydride and pyromellitic dianhydride; a diamine component comprising at least one of p-phenylenediamine and 4, 4' -diaminodiphenyl ether; and a carboxylic acid mono-anhydride, and,

X/Y is more than or equal to 0.97 and less than 1.00 in the formula (1)

The formula (2) is more than or equal to 0.5 and less than or equal to (Z/2)/(Y-X) and less than or equal to 1.05

Wherein X represents the number of moles of the tetracarboxylic acid component, Y represents the number of moles of the diamine component, and Z represents the number of moles of the carboxylic acid monoanhydride.

2. The polyimide precursor resin composition for forming a flexible device substrate according to claim 1, wherein the content of 3,3 ', 4, 4' -biphenyltetracarboxylic dianhydride is 40 mol% or more of the tetracarboxylic acid component.

3. The polyimide precursor resin composition for forming a flexible device substrate according to claim 1 or 2, wherein a content of p-phenylenediamine is 40 mol% or more of the diamine component.

4. The polyimide precursor resin composition for forming a flexible device substrate according to any one of claims 1 to 3, wherein the carboxylic acid monoanhydride is phthalic anhydride or maleic anhydride.

5. A laminate comprising a glass substrate and a polyimide film obtained from the polyimide precursor resin composition for forming a flexible device substrate according to any one of claims 1 to 4.

6. A flexible device substrate comprising a polyimide film obtained from the polyimide precursor resin composition for forming a flexible device substrate according to any one of claims 1 to 4.

7. A flexible device substrate, comprising: a polyimide film obtained from the polyimide precursor resin composition for flexible device substrate formation according to any one of claims 1 to 4; and an inorganic film containing an inorganic substance selected from the group consisting of silicon nitride, silicon oxide, silicon oxynitride, aluminum oxide, titanium oxide, and zirconium oxide.

8. A flexible device having the TFT mounted on the flexible device substrate according to claim 6 or 7.

9. A method for manufacturing a laminate, the method comprising: a step of casting a polyimide precursor resin composition for forming a flexible device substrate containing a polyamic acid onto a substrate; and a step of forming a polyimide film by imidizing the polyamic acid by heat treatment,

the method for producing the laminate is characterized in that,

the polyamic acid is a polyamic acid having a structure obtained from a component satisfying the following formula (1) and the following formula (2), and the component is: a tetracarboxylic acid component containing at least one of 3,3 ', 4, 4' -biphenyltetracarboxylic dianhydride and pyromellitic dianhydride; a diamine component comprising at least one of p-phenylenediamine and 4, 4' -diaminodiphenyl ether; and a carboxylic acid mono-anhydride, and,

X/Y is more than or equal to 0.97 and less than 1.00 in the formula (1)

The formula (2) is more than or equal to 0.5 and less than or equal to (Z/2)/(Y-X) and less than or equal to 1.05

Wherein X represents the number of moles of the tetracarboxylic acid component, Y represents the number of moles of the diamine component, and Z represents the number of moles of the carboxylic acid monoanhydride.

Technical Field

The present invention relates to a polyimide precursor resin composition for forming a flexible device substrate, a laminate and a flexible device using the same, and a method for producing the laminate.

Background

Conventionally, a glass substrate has been used for electronic devices such as flat panel displays using liquid crystal display elements and organic EL display elements, but glass has the following problems: when the film is made thinner for weight reduction, the strength is insufficient and the film is easily broken. As an alternative to glass substrates, plastic substrates that are lightweight and have excellent flexibility have been developed, and flexible devices using such plastic substrates are expected to be used in various applications. Polyimide, which is a resin material that is lightweight and easily thinned, is suitable for a plastic substrate, and various polyimides have been proposed.

In the manufacture of a typical flexible device, a polyimide film is first formed on a carrier substrate such as glass to produce a flexible device substrate. Further, a barrier layer and a polyimide film may be further formed on the polyimide film to manufacture a flexible device substrate. A semiconductor element such as a TFT is formed on the flexible device substrate thus obtained. In such a step, a polyimide film is required to be firmly laminated on the carrier substrate and the barrier layer. Further, the polyimide film is also required to have high heat resistance so as to withstand high temperature conditions during device fabrication.

Patent documents 1 and 2 propose a method for producing a laminate of a polyimide film and a carrier substrate. Patent documents 3 and 4 propose a polyimide precursor in which an alkoxysilane compound is added or reacted in order to improve the adhesion between a support and a polyimide film. Patent document 5 proposes a technique for treating a carrier substrate with a silane coupling agent.

On the other hand, a method of modifying polyimide to improve the characteristics of polyimide is known. Patent document 6 proposes a polyamic acid whose end is modified with a monoanhydride. Patent document 7 proposes a polyamic acid whose end is modified with an aromatic dicarboxylic anhydride.

Disclosure of Invention

Problems to be solved by the invention

The polyimide films described in patent documents 1 and 2 have a problem that the adhesion to the carrier substrate is low and peeling occurs. The polyimide precursor solutions described in patent documents 3 to 5 are poor in stability, and the obtained polyimide films do not have adhesiveness that can withstand high temperature conditions at the time of device production, and the reliability of flexible devices is impaired.

The polyamic acid described in patent document 6 has improved viscosity stability, mechanical strength and toughness when imidized, but the peel strength is not improved. The polyimide film described in patent document 7 is used as a release layer of a glass substrate, not a flexible device substrate. Naturally, the physical properties and the standards required for the flexible device substrate and the release layer are greatly different.

For a polyimide film used in a flexible device substrate, improvement in peel strength to a carrier substrate is required. The purpose of the present invention is to provide a polyimide precursor resin composition for forming a flexible device substrate, which can obtain a polyimide film having high peel strength to the substrate while ensuring mechanical properties required for use as a flexible device.

Means for solving the problems

The present invention relates to the following items.

1. A polyimide precursor resin composition for forming a flexible device substrate, comprising a polyamic acid having a structure obtained from a component satisfying the following formula (1) and the following formula (2), the component being: a tetracarboxylic acid component containing at least one of 3,3 ', 4, 4' -biphenyltetracarboxylic dianhydride and pyromellitic dianhydride; a diamine component comprising at least one of p-phenylenediamine and 4, 4' -diaminodiphenyl ether; and carboxylic acid monoanhydrides.

X/Y is more than or equal to 0.97 and less than 1.00 in the formula (1)

The formula (2) is more than or equal to 0.5 and less than or equal to (Z/2)/(Y-X) and less than or equal to 1.05

(wherein X represents the number of moles of the tetracarboxylic acid component, Y represents the number of moles of the diamine component, and Z represents the number of moles of the carboxylic acid monoanhydride.)

2. The polyimide precursor resin composition for forming a flexible device substrate according to item 1, wherein the content of 3,3 ', 4, 4' -biphenyltetracarboxylic dianhydride is 40 mol% or more of the tetracarboxylic acid component.

3. The polyimide precursor resin composition for forming a flexible device substrate according to claim 1 or 2, wherein the content of p-phenylenediamine is 40 mol% or more based on the diamine component.

4. The polyimide precursor resin composition for forming a flexible device substrate according to any one of claims 1 to 3, wherein the carboxylic acid monoanhydride is phthalic anhydride or maleic anhydride.

5. A laminate comprising a glass substrate and a polyimide film obtained from the polyimide precursor resin composition for forming a flexible device substrate according to any one of claims 1 to 4.

6. A flexible device substrate comprising a polyimide film obtained from the polyimide precursor resin composition for forming a flexible device substrate according to any one of items 1 to 4.

7. A flexible device substrate, comprising: a polyimide film obtained from the polyimide precursor resin composition for forming a flexible device substrate according to any one of claims 1 to 4; and an inorganic film containing an inorganic substance selected from the group consisting of silicon nitride, silicon oxide, silicon oxynitride, aluminum oxide, titanium oxide, and zirconium oxide.

8. A flexible device having a TFT mounted on the flexible device substrate according to item 6 or 7.

9. A method for manufacturing a laminate, the method comprising: a step of casting a polyimide precursor resin composition for forming a flexible device substrate containing a polyamic acid onto a substrate; and a step of forming a polyimide film by imidizing the polyamic acid by heat treatment,

the method for producing the laminate is characterized in that,

the polyamic acid is a polyamic acid having a structure obtained from a component satisfying the following formula (1) and the following formula (2): a tetracarboxylic acid component containing at least one of 3,3 ', 4, 4' -biphenyltetracarboxylic dianhydride and pyromellitic dianhydride; a diamine component comprising at least one of p-phenylenediamine and 4, 4' -diaminodiphenyl ether; and carboxylic acid monoanhydrides.

X/Y is more than or equal to 0.97 and less than 1.00 in the formula (1)

The formula (2) is more than or equal to 0.5 and less than or equal to (Z/2)/(Y-X) and less than or equal to 1.05

(wherein X represents the number of moles of the tetracarboxylic acid component, Y represents the number of moles of the diamine component, and Z represents the number of moles of the carboxylic acid monoanhydride.)

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, a polyimide precursor resin composition for forming a flexible device substrate can be provided, which can obtain a polyimide film having high peel strength to a substrate while ensuring mechanical properties required for use as a flexible device. The polyimide film obtained from the polyimide precursor resin composition for forming a flexible device substrate of the present invention can be suitably used for a flexible device substrate. Further, the polyimide precursor resin composition for forming a flexible device substrate of the present invention has improved viscosity stability, and can improve the reliability of a flexible device.

Detailed Description

The polyamic acid has a structure obtained from the following components: a tetracarboxylic acid component containing at least one of 3,3 ', 4, 4' -biphenyltetracarboxylic dianhydride and pyromellitic dianhydride; a diamine component comprising at least one of p-phenylenediamine and 4, 4' -diaminodiphenyl ether; and carboxylic acid monoanhydrides. The main chain of the polyamic acid having such a structure is a polymer of a tetracarboxylic acid component containing at least one of 3,3 ', 4,4 ' -biphenyltetracarboxylic dianhydride and pyromellitic dianhydride, and a diamine component containing at least one of p-phenylenediamine and 4,4 ' -diaminodiphenyl ether, and in at least a part of the polyamic acid, the end of the main chain is terminated with a carboxylic acid monoanhydride.

The amount of the 3,3 ', 4, 4' -biphenyltetracarboxylic dianhydride in the tetracarboxylic acid component is preferably 40 mol% or more, more preferably 60 mol% or more, further preferably 80 mol% or more, and may be 100 mol% from the viewpoints of heat resistance, dimensional change rate, and viscosity stability of the polyamic acid. The amount of pyromellitic dianhydride in the tetracarboxylic acid component is preferably 5 mol% or more, and more preferably 10 mol% or more. The amount of pyromellitic dianhydride in the tetracarboxylic acid component is preferably 40 mol% or less, and more preferably 20 mol% or less. The total amount of 3,3 ', 4, 4' -biphenyltetracarboxylic dianhydride and pyromellitic dianhydride in the tetracarboxylic acid component is preferably 40 mol% or more, more preferably 60 mol% or more, further preferably 80 mol% or more, and may be 100 mol%.

The amount of p-phenylenediamine in the diamine component is preferably 40 mol% or more, more preferably 60 mol% or more, further preferably 80 mol% or more, and may be 100 mol% from the viewpoints of heat resistance and dimensional change rate. The amount of 4, 4' -diaminodiphenyl ether in the diamine component is preferably 5 mol% or more, and more preferably 10 mol% or more. The amount of 4, 4' -diaminodiphenyl ether in the diamine component is preferably 60 mol% or less, more preferably 40 mol% or less, and particularly preferably 20 mol% or less. In one embodiment, the diamine component may be comprised of p-phenylenediamine and/or 4, 4' -diaminodiphenyl ether. The total amount of p-phenylenediamine and 4, 4' -diaminodiphenyl ether in the diamine component is preferably 40 mol% or more, more preferably 60 mol% or more, further preferably 80 mol% or more, and may be 100 mol%.

Further, other tetracarboxylic dianhydrides and diamines may be used within a range not to impair the characteristics of the present invention.

The tetracarboxylic dianhydride to be added is not particularly limited, but an aromatic tetracarboxylic dianhydride and an alicyclic tetracarboxylic dianhydride are preferable in view of the characteristics of the polyimide to be obtained. For example, 2,3,3 ', 4' -biphenyltetracarboxylic dianhydride, 2 ', 3, 3' -biphenyltetracarboxylic dianhydride, 3,3 ', 4, 4' -benzophenonetetracarboxylic dianhydride, oxydiphthalic dianhydride, diphenylsulfonetetracarboxylic dianhydride, p-terphenyltetracarboxylic dianhydride, m-terphenyltetracarboxylic dianhydride, cyclobutane-1, 2,3, 4-tetracarboxylic dianhydride, 1,2,4, 5-cyclohexanetetracarboxylic dianhydride, and the like are suitably used. The tetracarboxylic dianhydride does not need to be one, and may be a mixture of two or more kinds.

The diamine to be added is not particularly limited, and examples thereof include aromatic diamines such as 4,4 ' -diaminodiphenylmethane, m-phenylenediamine, 2, 4-diaminotoluene, 1, 3-bis (4-aminophenoxy) benzene, 1, 4-bis (4-aminophenoxy) benzene, 2-bis [4- (4-aminophenoxy) phenyl ] propane, m-xylylenediamine, p-xylylenediamine, 2-bis [4- (4-aminophenoxy) phenyl ] propane, 4 ' -methylenebis (2, 6-xylidine), α ' -bis (4-aminophenyl) -1, 4-diisopropylbenzene, 1, 6-hexamethylenediamine, 1, 7-heptamethylenediamine, 1, 8-octamethylenediamine, 1, 9-nonanediamine, 1-9-nonanediamine, and the like, Aliphatic diamines such as 1, 10-decamethylenediamine, diaminopropyltetramethylene, 3-methylheptamethylenediamine, 2, 11-diaminododecane, and 1, 12-diaminooctadecane. The diamine is not necessarily one kind, and may be a mixture of two or more kinds.

The carboxylic acid monoanhydride is used for capping the end of a polyamic acid obtained by reacting a tetracarboxylic acid component and a diamine component. The polyimide film having the terminals capped with the carboxylic acid monoanhydride has excellent adhesion to the carrier substrate and the barrier layer. In addition, when a polyimide film having a terminal capped with a carboxylic acid monoanhydride is used for a flexible device substrate, the reliability and electrical characteristics of the flexible device to be manufactured may be improved. The carboxylic acid monoanhydride is not particularly limited, and may be an aromatic carboxylic acid monoanhydride or an aliphatic carboxylic acid monoanhydride. Aromatic carboxylic acid monoanhydrides are particularly preferred. In particular applications, the carboxylic acid monoanhydride preferably does not contain other functional groups such as a hydroxyl group, a carbonyl group, a carboxyl group, and an amino group, and dicarboxylic acid monoanhydride is preferable. The aromatic carboxylic acid monoanhydride preferably has an aromatic ring with 6 to 30 carbon atoms, more preferably has an aromatic ring with 6 to 15 carbon atoms, and even more preferably has an aromatic ring with 6 to 10 carbon atoms.

Examples of the carboxylic acid monoanhydrides include aromatic carboxylic acid monoanhydrides such as phthalic anhydride, 2, 3-benzophenone dicarboxylic anhydride, 3, 4-benzophenone dicarboxylic anhydride, 1, 2-naphthalene dicarboxylic anhydride, 2, 3-naphthalene dicarboxylic anhydride, 1, 8-naphthalene dicarboxylic anhydride, 1, 2-anthracene dicarboxylic anhydride, 2, 3-anthracene dicarboxylic anhydride, 1, 9-anthracene dicarboxylic anhydride, and trimellitic anhydride, and alicyclic carboxylic acid monoanhydrides such as maleic anhydride, succinic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, and itaconic anhydride. Among these, phthalic anhydride is preferred. The carboxylic acid monoanhydride may be a carboxylic acid monoanhydride having an ethynyl group such as phenylethynylphthalic anhydride. In particular applications, carboxylic acid mono anhydrides having an ethynyl group are preferred. On the other hand, an ethynyl group may lower the heat resistance of the polyimide, and in particular applications, it is preferable not to include a carboxylic acid monoanhydride having an ethynyl group.

The molar ratios of the tetracarboxylic acid component, the diamine component and the carboxylic acid monoanhydride satisfy the following formulas (1) and (2).

X/Y is more than or equal to 0.97 and less than 1.00 in the formula (1)

The formula (2) is more than or equal to 0.5 and less than or equal to (Z/2)/(Y-X) and less than or equal to 1.05

(wherein X represents the number of moles of the tetracarboxylic acid component, Y represents the number of moles of the diamine component, and Z represents the number of moles of the carboxylic acid monoanhydride.)

When the ratio X/Y is 0.97 or more, the molecular weight of the polyamic acid can be increased, and the strength and heat resistance of the polyimide film obtained can be improved. X/Y is preferably 0.98 or more. When X/Y is less than 1.00, the diamine component is in excess of the tetracarboxylic acid component. This enables formation of an amino group that can be capped with a carboxylic acid monoanhydride. X/Y is preferably 0.99 or less.

Further, (Z/2)/(Y-X) represents the molar ratio of the carboxylic acid monoanhydride to the amino group which may be capped. When X/Y is less than 1.00 and (Z/2)/(Y-X) is 0.5 or more, the end capping ratio of the polyamic acid can be increased, and the adhesion of the resulting polyimide film can be improved. The closer to 1 the (Z/2)/(Y-X) is, the more preferable it is. (Z/2)/(Y-X) is preferably 0.6 or more, more preferably 0.7 or more. By setting (Z/2)/(Y-X) to 1.05 or less, the amount of free carboxylic acid monoanhydride can be reduced, and the strength of the polyimide film obtained can be improved. (Z/2)/(Y-X) is preferably 1.03 or less, more preferably 1.01 or less.

By satisfying the above formulae (1) and (2), a polyimide film exhibiting high peel strength to a substrate can be obtained without impairing the mechanical properties required for flexible device applications.

In the present invention, the logarithmic viscosity of the polyamic acid is not particularly limited, but is preferably 0.2dL/g or more, more preferably 0.4dL/g or more, in an N-methyl-2-pyrrolidone solution having a concentration of 0.5g/dL at 30 ℃. When the logarithmic viscosity is 0.2dL/g or more, the polyamic acid has a high molecular weight, and the polyimide obtained therefrom has excellent mechanical strength and heat resistance. The logarithmic viscosity in a solution of N-methyl-2-pyrrolidone having a concentration of 0.5g/dL at 30 ℃ is usually 4.0dL/g or less.

An imidization catalyst, an organic phosphorus compound, inorganic fine particles, and the like may be added to the polyimide precursor resin composition as necessary.

Examples of the imidization catalyst include a substituted or unsubstituted nitrogen-containing heterocyclic compound, an N-oxide compound of the nitrogen-containing heterocyclic compound, a substituted or unsubstituted amino acid compound, an aromatic hydrocarbon compound having a hydroxyl group, or an aromatic heterocyclic compound, in particular, substituted pyridines such as lower alkyl imidazole such as 1, 2-dimethyl imidazole, N-methyl imidazole, N-benzyl-2-methyl imidazole, 2-ethyl-4-methyl imidazole, and 5-methyl benzimidazole, benzimidazole such as N-benzyl-2-methyl imidazole, isoquinoline, 3, 5-dimethylpyridine, 3, 4-dimethylpyridine, 2, 5-dimethylpyridine, 2, 4-dimethylpyridine, and 4-N-propylpyridine, and the like can be suitably used. The amount of the imidization catalyst to be used is preferably about 0.01 to 2 equivalents, and particularly preferably about 0.02 to 1 equivalent to the amic acid unit of the polyamic acid. By using the imidization catalyst, the physical properties of the obtained polyimide film, particularly the elongation and the edge tear resistance, may be improved.

Examples of the organic phosphorus-containing compound include phosphoric acid esters such as monohexanoyl phosphate, monooctyl phosphate, monolauryl phosphate, monomyristyl phosphate, monocetyl phosphate, monostearyl phosphate, monophosphates of triethylene glycol monotridecyl ether, monophosphates of tetraethylene glycol monolauryl ether, monophosphates of diethylene glycol monostearate, dihexyl phosphate, dioctyl phosphate, didecanyl phosphate, dilauryl phosphate, dimyristyl phosphate, dicetyl phosphate, distearyl phosphate, diphosphoric acid ester of tetraethylene glycol neopentyl ether, diphosphoric acid ester of triethylene glycol monotridecyl ether, diphosphoric acid ester of tetraethylene glycol monolauryl ether, diphosphoric acid ester of diethylene glycol monostearate, and amine salts of these phosphoric acid esters. Examples of the amine include ammonia, monomethylamine, monoethylamine, monopropylamine, monobutylamine, dimethylamine, diethylamine, dipropylamine, dibutylamine, trimethylamine, triethylamine, tripropylamine, tributylamine, monoethanolamine, diethanolamine, and triethanolamine.

Examples of the inorganic fine particles include inorganic oxide powders such as fine particulate titanium dioxide powder, silica (silica) powder, magnesia powder, alumina (alumina) powder, and zinc oxide powder, fine particulate silicon nitride powder, inorganic nitride powder such as titanium nitride powder, inorganic carbide powder such as silicon carbide powder, and inorganic salt powders such as fine particulate calcium carbonate powder, calcium sulfate powder, and barium sulfate powder. These inorganic fine particles may be used in combination of two or more kinds. In order to uniformly disperse these inorganic fine particles, a means known per se can be applied.

In one embodiment, the polyimide precursor resin composition preferably does not contain a silane coupling agent such as an alkoxysilane. In a polyimide film using a silane coupling agent, the silane coupling agent may bleed out. This causes problems such as a decrease in the adhesion of the polyimide film, expansion of the laminate, and a decrease in the reliability of the semiconductor device. Further, when a silane coupling agent is added or reacted to the polyamic acid solution, there is a problem that the viscosity stability of the polyamic acid solution is lowered. In order to avoid such a problem, it is preferable not to use a silane coupling agent. The polyimide film obtained from the polyimide precursor resin composition of the present invention has improved peel strength to a substrate, and provides a good flexible device substrate even without using a silane coupling agent.

The polyimide precursor resin composition of the present invention may contain a solvent. The solvent is not particularly limited as long as the polyamic acid is dissolved, and examples thereof include the same solvents as used in the preparation of the polyamic acid. The solvent may be a mixture of 2 or more.

The solvent used in the preparation of the polyamic acid is not particularly limited, and examples thereof include amide solvents such as N, N-dimethylformamide, N-dimethylacetamide, N-diethylacetamide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, and N-vinyl-2-pyrrolidone, cyclic ester solvents such as γ -butyrolactone, γ -valerolactone, γ -caprolactone, and α -methyl- γ -butyrolactone, carbonate solvents such as ethylene carbonate and propylene carbonate, glycol solvents such as triethylene glycol, phenol solvents such as m-cresol, p-cresol, 3-chlorophenol, and 4-chlorophenol, acetophenone, 1, 3-dimethyl-2-imidazolidinone, and the like, Sulfolane, dimethyl sulfoxide, and the like. Further, as other common organic solvents, for example, alcohol solvents such as methanol and ethanol, phenol, o-cresol, butyl acetate, ethyl acetate, isobutyl acetate, propylene glycol methyl acetate, ethyl cellosolve, butyl cellosolve, 2-methyl cellosolve acetate, ethyl cellosolve acetate, butyl cellosolve acetate, tetrahydrofuran, dimethoxyethane, diethoxyethane, dibutyl ether, diethylene glycol dimethyl ether, methyl isobutyl ketone, diisobutyl ketone, cyclopentanone, cyclohexanone, methyl ethyl ketone, acetone, butanol, ethanol, xylene, toluene, chlorobenzene, N-methylcaprolactam, hexamethylphosphoric triamide, bis (2-methoxyethyl) ether, 1, 2-bis (2-methoxyethoxy) ethane, bis [2- (2-methoxyethoxy) ethyl ] ether, and the like can be used, 1, 4-dioxane, dimethyl sulfoxide, dimethyl sulfone, diphenyl ether, diphenyl sulfone, tetramethylurea, anisole, terpene, mineral oil, naphtha solvent, biodegradable methyl lactate, ethyl lactate, butyl lactate, etc. One or two or more organic solvents may be used.

In the polyimide precursor resin composition of the present invention, the solid content concentration derived from the polyamic acid is not particularly limited, and is preferably 5 to 45 mass%, more preferably 7 to 40 mass%, and still more preferably 9 to 30 mass% with respect to the total amount of the polyamic acid and the solvent. If the solid content concentration is less than 5% by mass, the productivity and handling during use may be deteriorated, and if it is more than 45% by mass, the fluidity of the solution may be lost.

The polyimide precursor resin composition of the present invention has a solution viscosity at 30 ℃ not particularly limited, but is preferably 1000 pas or less, more preferably 0.1 to 500 pas, still more preferably 0.1 to 300 pas, and particularly preferably 0.1 to 200 pas. When the solution viscosity exceeds 1000 pas, the fluidity is lost, and uniform coating on a carrier substrate such as metal or glass may be difficult, and when the solution viscosity is less than 0.1 pas, sagging, shrinkage, and the like may occur when the solution is coated on a carrier substrate such as metal or glass, and a polyimide film having high properties may be difficult to obtain.

The polyimide precursor resin composition of the present invention has excellent storage stability because the ends are capped with the carboxylic acid monoanhydride. The polyimide precursor resin composition of the present invention preferably has a viscosity change rate of ± 10% or less, more preferably ± 5% or less, and still more preferably ± 3% or less. When the viscosity change rate is in this range, the viscosity change after long-term retention is small, and the occurrence of unevenness can be suppressed when the coating composition is applied to various substrates. Here, the "viscosity change rate" means a change in viscosity when the polyimide precursor resin composition is held at 25 ℃ for 30 days. Specifically, the viscosity of the polyimide precursor resin composition after being held at 25 ℃ for 30 days (viscosity after holding) and the viscosity of the polyimide precursor resin composition before being held at 25 ℃ for 30 days (viscosity before holding) were determined by the following calculation method.

(viscosity change rate (%)) { (viscosity after Retention) - (viscosity before Retention) }/(viscosity before Retention) × 100

The method for producing the polyimide precursor resin composition of the present invention generally comprises: a step 1 of reacting a tetracarboxylic acid component and a diamine component in a solvent at a molar ratio satisfying formula (1) to obtain a polyamic acid having an amino group at an end; and a step 2 of reacting the obtained polyamic acid with a carboxylic acid monoanhydride in a molar ratio satisfying the formula (2) to terminate the end of the polyamic acid.

In the step 1, the imidization reaction is suppressed at a relatively low temperature of, for example, 100 ℃ or lower, preferably 80 ℃ or lower. Although not limited, the reaction temperature is usually 25 to 100 ℃, preferably 40 to 80 ℃, more preferably 50 to 80 ℃, and the reaction time is usually about 0.1 to 24 hours, preferably about 2 to 12 hours. When the reaction temperature and the reaction time are set to the above ranges, a solution composition of polyamic acid having a high molecular weight can be efficiently obtained. The reaction may be carried out under an air atmosphere, and is usually carried out under an inert gas atmosphere, preferably under a nitrogen atmosphere.

In the step 2, the reaction temperature can be appropriately set, and from the viewpoint of reliably capping the ends of the polyamic acid, it is preferably from 25 to 70 ℃, more preferably from 25 to 60 ℃, and still more preferably from 25 to 50 ℃. The reaction time is usually about 0.1 to 24 hours.

A flexible device substrate can be manufactured using the polyimide precursor resin composition of the present invention. Further, a flexible device can be manufactured using the obtained flexible device substrate.

In the production of a flexible device substrate, first, the polyimide precursor resin composition of the present invention is cast on a support substrate, and imidized by heat treatment to form a polyimide film. The resulting polyimide film can be used for a flexible device substrate. The carrier substrate is not limited, and a glass substrate such as soda lime glass, borosilicate glass, or alkali-free glass, or a metal substrate such as iron or stainless steel is generally used. The method for casting the polyamic acid solution onto the support substrate is not particularly limited, and examples thereof include conventionally known methods such as spin coating, screen printing, bar coating, and electrodeposition. The heat treatment conditions are not particularly limited, but it is preferable to dry the substrate at a temperature ranging from 50 ℃ to 150 ℃ and then perform the treatment at a maximum heating temperature of 150 ℃ to 600 ℃, preferably 200 ℃ to 550 ℃, and more preferably 250 ℃ to 500 ℃.

The thickness of the polyimide film is preferably 1 μm or more. If the thickness is less than 1 μm, the polyimide film may not retain sufficient mechanical strength, and may not withstand stress and be broken when used as a flexible device substrate. The thickness of the polyimide film is preferably 20 μm or less. If the thickness of the polyimide film is increased to more than 20 μm, it becomes difficult to make the flexible device thin. The thickness of the polyimide film is more preferably 2 to 10 μm in order to maintain sufficient resistance as a flexible device and to further reduce the thickness of the film.

The polyimide film obtained from the polyimide precursor resin composition of the present invention is firmly laminated on a glass substrate. The peel strength between the glass substrate and the polyimide film is usually 50mN/mm or more, preferably 100mN/mm or more, more preferably 200mN/mm or more, and further preferably 300mN/mm or more, measured in accordance with JIS K6854-1.

In addition, a flexible device substrate may be formed by laminating a 2 nd layer such as a resin film or an inorganic film on a polyimide film obtained from the polyimide precursor resin composition of the present invention. In particular, an inorganic film can be used as a water vapor barrier layer, and is suitable. Examples of the water vapor barrier layer include a water vapor barrier layer containing a material selected from the group consisting of silicon nitride (SiN)_x) Silicon oxide (SiO)_x) Silicon oxynitride (SiO)_xN_y) Alumina (Al)₂O₃) Titanium oxide (TiO)₂) Zirconium oxide (ZrO)₂) Iso-metal oxide, metal nitrideAn inorganic film of an inorganic substance in the group consisting of an inorganic substance and a metal oxynitride. Generally, as a method for forming these thin films, a vacuum deposition method, a sputtering method, a physical deposition method such as ion plating, a chemical deposition method (chemical vapor deposition method) such as a plasma CVD method or a catalytic chemical vapor deposition method (Cat-CVD method), and the like are known.

The polyimide film obtained from the polyimide precursor resin composition of the present invention may be laminated on a resin film or an inorganic film to form a flexible device substrate. The polyimide film can be laminated on a resin film or an inorganic film using the polyimide precursor resin composition of the present invention by the same method as in the case of the carrier substrate.

The polyimide film obtained from the polyimide precursor resin composition of the present invention can be firmly laminated even when the inorganic film is a substrate. The peel strength between the polyimide film and the inorganic film (e.g., silicon oxide film) is usually 50mN/mm or more, preferably 100mN/mm or more, more preferably 200mN/mm or more, and still more preferably 300mN/mm or more, as measured in accordance with JIS K6854-1.

In the manufacture of a flexible device, a circuit required for a display device or a light-receiving device is formed on a flexible device substrate (particularly, a polyimide film) thus formed. This process differs depending on the kind of device. In the case of manufacturing a TFT liquid crystal display device, a TFT such as amorphous silicon is formed on a polyimide film. The TFT includes, for example, a semiconductor layer such as a gate metal layer or an amorphous silicon film, a silicon nitride gate dielectric layer, and an ITO pixel electrode. Further, a structure required for a liquid crystal display can be formed thereon by a known method. The polyimide film obtained in the present invention is excellent in various properties such as heat resistance and toughness, and thus a method for forming a circuit or the like is not particularly limited.

The flexible device substrate (particularly, the polyimide film) having the circuit and the like formed on the surface thereof as described above is peeled off from the carrier substrate. The peeling method is not particularly limited, and peeling can be performed by, for example, irradiating laser light or the like from the carrier substrate side.

Examples of the flexible device in the present invention include display devices such as liquid crystal displays, organic EL displays, and electronic paper, and light-receiving devices such as solar cells and CMOS. The present invention is particularly suitable for use in devices that are thin and where it is desirable to impart flexibility.