CN113166409A

CN113166409A - Polyimide precursor, polyimide resin film, and flexible device

Info

Publication number: CN113166409A
Application number: CN201980071725.0A
Authority: CN
Inventors: 佐伯昭典; 宫内拓也; 宫崎大地
Original assignee: Toray Industries Inc
Current assignee: Toray Industries Inc
Priority date: 2018-11-09
Filing date: 2019-10-24
Publication date: 2021-07-23
Anticipated expiration: 2039-10-24
Also published as: JP7384037B2; TW202030226A; WO2020095693A1; JPWO2020095693A1; CN113166409B; KR20210088551A

Abstract

The polyimide precursor comprises a structure represented by general formula (1) and a structural unit represented by general formula (2). (in the general formula (1), R¹And R²Each independently represents a monovalent organic group having 1 to 20 carbon atoms. m represents an integer of 1 to 200 inclusive. ) (in the general formula (2), R³Represents a divalent organic group represented by the general formula (3). R⁴Represents an aromatic tetracarboxylic acid residue. X¹And X²Each independently represents a hydrogen atom, a monovalent organic group having 1 to 10 carbon atoms, or a monovalent alkylsilyl group having 1 to 10 carbon atoms. )

Description

Polyimide precursor, polyimide resin film, and flexible device

Technical Field

The present invention relates to a polyimide precursor, a polyimide resin film, and a flexible device.

Background

The organic film has advantages of being more flexible, less likely to break, and lighter than glass. Recently, the flexibility of flat panel displays has been actively improved by replacing substrates of the flat panel displays with organic films.

Examples of the resin that can be used for the organic film include polyester, polyamide, polyimide, polycarbonate, polyethersulfone, acrylic resin, epoxy resin, and cycloolefin polymer. Among these, polyimide is a highly heat-resistant resin and is therefore suitable as a display substrate. However, a general polyimide resin is colored brown or yellow due to a high aromatic ring density, and has low transmittance in a visible light region, and thus is difficult to apply to a field requiring transparency.

In order to solve the problem of improving the transparency of such a polyimide resin, patent document 1 discloses a polyimide resin film using an amine having an alicyclic acid dianhydride and a hydroxyl group, specifically 2, 2-bis [3- (3-aminobenzamido) -4-hydroxyphenyl ] hexafluoropropane (HFHA), as a polyimide resin film having high heat resistance and light transmittance.

Patent document 2 discloses a method for obtaining a flexible touch panel using a transparent polyimide resin film obtained by baking in air.

Documents of the prior art

Patent document

Patent document 1: international publication No. 2013/24849

Patent document 2: international publication No. 2018/84067

Disclosure of Invention

Problems to be solved by the invention

Patent document 1 discloses a polyimide having high transparency and low in-plane/out-of-plane birefringence. However, the polyimide described in patent document 1 needs to be fired in an inert oven (inert oven) for a long time in order to produce a polyimide resin film, and therefore, there is a problem that it takes much cost and time to form the polyimide resin film.

Patent document 2 discloses that a transparent polyimide resin film is obtained by firing in air for 30 minutes. However, the transparent polyimide resin film described in patent document 2 has a glass transition temperature of about 220 to 230 ℃, and has a problem that the glass transition temperature is low as a resin film used for devices such as touch panels and displays. When a polyimide resin film having a low glass transition temperature is used in a device, for example, when an inorganic film is formed on the polyimide resin film and then a touch panel or a color filter is formed, the inorganic film is wrinkled and the surface smoothness is degraded in order to improve the reliability of the touch panel.

As described above, a method for efficiently obtaining a polyimide having high transparency, high glass transition temperature, low in-plane/out-of-plane birefringence, and good substrate adhesion is not known.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a polyimide precursor which can efficiently obtain a polyimide having high transparency, a high glass transition temperature, low in-plane/out-of-plane birefringence, and good adhesion to a supporting substrate. The 2 nd object of the present invention is to provide a polyimide obtained using such a polyimide precursor, a polyimide resin film, and a flexible device.

Means for solving the problems

In order to solve the above problems and achieve the object, the polyimide precursor according to the present invention is characterized by containing a structure represented by general formula (1) and a structural unit represented by general formula (2).

[ chemical formula 1]

(general formula (A)1) In, R¹And R²Each independently represents a monovalent organic group having 1 to 20 carbon atoms. m represents an integer of 1 to 200 inclusive. )

[ chemical formula 2]

(in the general formula (2), R³Represents a divalent organic group represented by the general formula (3). R⁴Represents an aromatic tetracarboxylic acid residue. X¹And X²Each independently represents a hydrogen atom, a monovalent organic group having 1 to 10 carbon atoms, or a monovalent alkylsilyl group having 1 to 10 carbon atoms. )

[ chemical formula 3]

The polyimide precursor according to the present invention is characterized by containing the structure represented by the general formula (1) in an amount of 0.1 to 30% by mass, based on 100% by mass of the total amount of the polyimide precursor in the above invention.

In the polyimide precursor according to the present invention, the polyimide precursor is characterized in that the polyimide precursor contains 30 mol% or more of the structural units of the divalent organic group represented by the general formula (3) in all diamine residues contained in the polyimide precursor.

In the polyimide precursor according to the present invention, the acid anhydride residue having a fluorene skeleton is contained in an amount of 5 mol% or more and 55 mol% or less of all the acid dianhydride residues contained in the polyimide precursor.

The polyimide precursor according to the present invention is characterized by containing a residue of a compound represented by the following general formula (4) in the above invention.

[ chemical formula 4]

(in the general formula (4), a plurality of R⁵Each independently represents a single bond or a divalent organic group having 1 to 10 carbon atoms. Plural R⁶And R⁷Each independently a monovalent aliphatic hydrocarbon group having 1 to 3 carbon atoms or an aromatic group having 6 to 10 carbon atoms. L is a group comprising an amino group or a reactive derivative thereof or an acid dianhydride structure or a reactive derivative thereof. y is an integer of 1 to 199 inclusive. )

The polyimide precursor according to the present invention is characterized by containing both a residue of the compound represented by the general formula (4) wherein y is 1 or more and 20 or less and a residue of the compound represented by the general formula (4) wherein y is 21 or more and 60 or less.

The polyimide precursor according to the present invention is characterized by containing a residue of a diamine represented by the following general formula (9) in the above invention.

[ chemical formula 5]

(in the general formula (9), R⁸Is a substituted or unsubstituted phenyl group. s represents an integer of 1 to 4 inclusive. )

The polyimide according to the present invention is characterized by being formed by imidizing the polyimide precursor according to any one of the above inventions.

The polyimide according to the present invention is characterized by containing a structure represented by general formula (1) and a structural unit represented by general formula (14).

[ chemical formula 6]

(in the general formula (1), R¹And R²Each independently represents a monovalent organic group having 1 to 20 carbon atoms. m represents an integer of 1 to 200 inclusive. )

[ chemical formula 7]

(in the general formula (14), R³Represents a divalent organic group represented by the general formula (3). R⁴Represents an aromatic tetracarboxylic acid residue. )

[ chemical formula 8]

The polyimide according to the present invention is characterized by containing a structure represented by the general formula (1) in an amount of 0.1 to 30% by mass, based on 100% by mass of the total amount of the polyimide in the above invention.

In the polyimide according to the present invention, the structural unit of the divalent organic group represented by the general formula (3) is contained in an amount of 30 mol% or more based on the total diamine residues contained in the polyimide.

The polyimide resin film according to the present invention is characterized by containing the polyimide according to any one of the above inventions.

Further, the polyimide resin film according to the present invention is characterized in that the density is 1.20g/cm in the above invention³Above and 1.43g/cm³The following.

In the polyimide resin film according to the present invention, the in-plane/out-of-plane birefringence is 0.01 or less.

The polyimide resin film according to the present invention is characterized in that the yellowness index is 3 or less in the above-described invention.

The flexible device according to the present invention is characterized by comprising the polyimide resin film according to any one of the above inventions.

ADVANTAGEOUS EFFECTS OF INVENTION

The present invention can provide a polyimide precursor which can efficiently obtain a polyimide having high transparency, high glass transition temperature, low in-plane/out-of-plane birefringence and good adhesion to a supporting substrate by heating in air for a short time. The polyimide and the polyimide resin film obtained from the polyimide precursor of the present invention can be suitably used as a flexible substrate for a display such as a touch panel or a color filter. By using such a flexible substrate, a highly accurate and highly reliable flexible display (an example of a flexible device) can be manufactured.

Drawings

FIG. 1 is a schematic cross-sectional view showing one example of the structure of a color filter including a polyimide resin film according to an embodiment of the present invention.

Detailed Description

Hereinafter, specific embodiments of the present invention will be described in detail with reference to the accompanying drawings. The present invention is not limited to the following embodiments. The drawings referred to in the following description are only schematic representations of shapes, sizes, and positional relationships to an extent that the contents of the present invention can be understood. That is, the present invention is not limited to the shapes, sizes, and positional relationships illustrated in the drawings.

< polyimide precursor >

The polyimide precursor according to an embodiment of the present invention includes a structure represented by general formula (1) and a structural unit represented by general formula (2).

[ chemical formula 9]

In the general formula (1), R¹And R²Each independently represents carbonA monovalent organic group having 1 to 20 atoms. m represents an integer of 1 to 200 inclusive.

[ chemical formula 10]

In the general formula (2), R³Represents a divalent organic group represented by the general formula (3). R⁴Represents an aromatic tetracarboxylic acid residue. X¹And X²Each independently represents a hydrogen atom, a monovalent organic group having 1 to 10 carbon atoms, or a monovalent alkylsilyl group having 1 to 10 carbon atoms.

[ chemical formula 11]

The phrase "the number of carbon atoms is 1 to 10" means "the number of carbon atoms is 1 or more and 10 or less. The same description in the present invention means the same meaning.

The polyimide precursor according to the embodiment of the present invention can exhibit the following effects by containing the structure represented by the general formula (1) and the structural unit represented by the general formula (2). That is, by heating the polyimide precursor in air for a short time, a polyimide having high transparency, high glass transition temperature (Tg), low in-plane/out-of-plane birefringence, and good substrate adhesion can be efficiently obtained.

The structural unit represented by the general formula (2) is a structural unit of a compound repeated in the polyimide precursor according to the embodiment of the present invention. Hereinafter, the structural unit is referred to as a "repeating structural unit" or simply as a "repeating unit", as appropriate. This is not limited to the structural unit represented by the general formula (2), and the same applies to structural units represented by general formulae other than the general formula (2).

The polyimide precursor according to the embodiment of the present invention has a structure represented by general formula (1) in at least one of an acid dianhydride residue and a diamine residue constituting a polyimide. This improves the adhesion strength between the polyimide obtained from the polyimide precursor and the glass support substrate. This is considered to be because the structure represented by the general formula (1) forms a hydrogen bond with a silanol group present on the glass surface, and a strong interaction occurs.

As R¹And R²In the (C1-C20) monovalent organic group, examples include a hydrocarbon group, an alkoxy group, and an epoxy group. As R¹And R²Examples of the hydrocarbon group in (1) include an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, and an aryl group having 6 to 20 carbon atoms.

The alkyl group having 1 to 20 carbon atoms is preferably an alkyl group having 1 to 10 carbon atoms, and specific examples thereof include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tert-butyl group, a pentyl group, and a hexyl group. The cycloalkyl group having 3 to 20 carbon atoms is preferably a cycloalkyl group having 3 to 10 carbon atoms, and specific examples thereof include a cyclopentyl group and a cyclohexyl group. The aryl group having 6 to 20 carbon atoms is preferably an aryl group having 6 to 12 carbon atoms, and specific examples thereof include a phenyl group, a tolyl group, a naphthyl group and the like.

As R¹And R²Examples of the alkoxy group in (1) include a methoxy group, an ethoxy group, a propoxy group, an isopropoxy group, a butoxy group, a phenoxy group, a propenyloxy group, and a cyclohexyloxy group.

R in the general formula (1)¹And R²Preferably a monovalent aliphatic hydrocarbon group having 1 to 3 carbon atoms or an aromatic group having 6 to 10 carbon atoms. The reason is that the polyimide precursor composition has good storage stability, and the obtained polyimide has high heat resistance. Here, the monovalent aliphatic hydrocarbon having 1 to 3 carbon atoms is preferably a methyl group. The aromatic group having 6 to 10 carbon atoms is preferably a phenyl group.

R in the general formula (1)¹And R²At least 1 of which preferably comprises an aromatic group. The reason is that a polyimide having high transparency can be obtained by suppressing phase separation due to the structure represented by the general formula (1). In this case, all R in the structure represented by the general formula (1)¹And R²In the above (1-3) ratio of the number of moles of the aliphatic hydrocarbon group M1 to the number of moles of the aromatic group M2 having 6-10 carbon atoms (M1 + M2 is 100) is preferably M1: M2 is 90-10: 10-90, more preferably M1: M2 is 85-15: 15-85, and further preferably M1: M2 is 85-30: 15-70. When the ratio is within the above range, the haze of the polyimide due to phase separation can be suppressed, and a polyimide resin film having high transparency can be obtained.

The polyimide precursor according to the embodiment of the present invention preferably contains the structure represented by the general formula (1) in an amount of 0.1 mass% to 30 mass% with respect to 100 mass% of the total amount of the polyimide precursor. In addition, the polyimide precursor preferably contains 5% by mass or more and 25% by mass or less of the structure represented by the general formula (1), more preferably contains 8% by mass or more and 23% by mass or less of the structure represented by the general formula (1), and still more preferably contains 10% by mass or more and 22% by mass or less of the structure represented by the general formula (1).

When the proportion of the structure represented by the general formula (1) contained in the polyimide precursor is within the above range, the obtained polyimide can be inhibited from clouding, lowering in glass transition temperature, and increasing in the amount of generated gas during heating.

M in the general formula (1) is an integer of 1 to 200, preferably an integer of 2 to 150, more preferably an integer of 5 to 100, and still more preferably an integer of 10 to 60. When the integer m is within the above range, the adhesion between the polyimide and the glass substrate can be improved. Further, the occurrence of white turbidity in the polyimide resin film, the decrease in the mechanical strength of the polyimide resin film, and the residual stress of the polyimide resin film can be suppressed.

In the present invention, "residual stress" refers to stress remaining inside a film after the resin composition is applied to a substrate such as a glass substrate to form the film, and is a criterion for "warpage" that may occur in the film. Specifically, the measurement can be carried out by the method described in the following examples.

The polyimide precursor according to the embodiment of the present invention preferably contains a residue of a compound represented by the following general formula (4) and a structure represented by the general formula (1) as described above. Such a polyimide precursor can be obtained by using a compound represented by general formula (4) as one of the monomer components.

[ chemical formula 12]

In the general formula (4), a plurality of R⁵Each independently represents a single bond or a divalent organic group having 1 to 10 carbon atoms. Plural R⁶And R⁷Each independently a monovalent aliphatic hydrocarbon group having 1 to 3 carbon atoms or an aromatic group having 6 to 10 carbon atoms. L is a group comprising an amino group or a reactive derivative thereof or an acid dianhydride structure or a reactive derivative thereof. y is an integer of 1 to 199 inclusive. The integer y is preferably 1 or more and 100 or less, and more preferably 1 or more and 60 or less.

In the general formula (4), as R⁵The divalent organic group having 1 to 10 carbon atoms in (A) includes an alkylene group having 1 to 10 carbon atoms, a cycloalkylene group having 3 to 10 carbon atoms, an arylene group having 6 to 10 carbon atoms, and the like. Examples of the alkylene group having 1 to 10 carbon atoms include a methylene group, a 1, 2-ethylene (dimethylene) group, a 1, 3-propylene group, a 1, 4-butylene group, a 1, 5-pentylene group, and a 1, 6-hexylene group. Examples of the cycloalkylene group having 3 to 10 carbon atoms include a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, and a cycloheptylene group. The arylene group having 6 to 10 carbon atoms is preferably an aromatic group having 6 to 10 carbon atoms, and examples thereof include a phenylene group and a naphthylene group. As R⁵The divalent organic group having 1 to 10 carbon atoms, and among these, a divalent aliphatic hydrocarbon group having 1 to 10 carbon atoms is preferable.

As R⁶And R⁷Preferable specific examples of the groups in (2) include those represented by the general formula (1) above¹And R²The "monovalent aliphatic hydrocarbon group having 1 to 3 carbon atoms" or the "aromatic group having 6 to 10 carbon atoms" in the above-mentioned examples are the same.

Examples of the reactive derivative of an amino group in L in the general formula (4) include an isocyanate group, a bis (trialkylsilyl) amino group and the like. Specific examples of the residue of the compound represented by the general formula (4) in the case where L is an amino group include X22-1660B-3 (number average molecular weight of 4,400, y is 39 to 41, phenyl: methyl: 25:75 mol%), X22-9409 (number average molecular weight of 1,340, y is 10 to 11, phenyl: methyl: 25:75 mol%), X22-9681 (number average molecular weight of 2,840, y is 25 to 26, phenyl: methyl: 25:75 mol%), X22-161A (number average molecular weight of 1,600, y is 19 to 20) as a both-terminal amino group-modified dimethylpolysiloxane, X22-161B (number average molecular weight of 3,000, y is 80138 to 39, KF 2, a number average molecular weight of 4,400, y 57), BY16-835U (ltd. company, Dow Corning Toray co., number average molecular weight 900, y 9-10), Silaplane FM3311 (manufactured BY Chisso Corporation, number average molecular weight 1000, y 11-12), 1, 3-bis (3-aminopropyl) tetramethyldisiloxane (number average molecular weight 248.5, y 1), and the like. Hereinafter, "1, 3-bis (3-aminopropyl) tetramethyldisiloxane" is referred to as "SiDA".

In addition, as the reactive derivative of the acid anhydride structure in L in the general formula (4), an acid ester of a dicarboxylic acid, an acid chloride of a dicarboxylic acid, and the like can be exemplified. Specific examples of the group containing an acid anhydride structure as L include groups represented by the following formulae.

[ chemical formula 13]

Specific examples of the compound represented by the general formula (4) in the case where L is a group having an acid anhydride structure include X22-168AS (manufactured by shin-Etsu chemical Co., Ltd., number average molecular weight: 1,000), X22-168A (manufactured by shin-Etsu chemical Co., Ltd., number average molecular weight: 2,000), X22-168B (manufactured by shin-Etsu chemical Co., Ltd., number average molecular weight: 3,200), X22-168-P5-B (manufactured by shin-Etsu chemical Co., Ltd., number average molecular weight: 4,200, y: 34 to 38, phenyl group: 25:75 mol%), DMS-Z21 (manufactured by Gelest, Inc., number average molecular weight: 600 to 800, y: 3 to 6), and the like.

L in the general formula (4) is more preferably an amino group from the viewpoint of increasing the molecular weight of the polyimide precursor, avoiding white turbidity of a varnish formed from the polyimide precursor and a solvent, from the viewpoint of cost, and from the viewpoint of heat resistance of the polyimide to be obtained.

The polyimide precursor according to the embodiment of the present invention preferably contains both a residue of the compound represented by general formula (4) in which y is 1 or more and 20 or less (hereinafter, referred to as "residue of the 1 st compound represented by general formula (4)") and a residue of the compound represented by general formula (4) in which y is 21 or more and 60 or less (hereinafter, referred to as "residue of the 2 nd compound represented by general formula (4)"). By including a residue of the 1 st compound represented by the general formula (4) in the polyimide precursor, a polyimide having good adhesion to a supporting substrate, low haze and good transparency can be obtained. Further, by including a residue of the 2 nd compound represented by the general formula (4) in the polyimide precursor, a polyimide which has good adhesion to a supporting substrate, a high glass transition temperature, a small residual stress, and an excellent elongation at break can be obtained. Therefore, by including both the residue of the 1 st compound and the residue of the 2 nd compound represented by the general formula (4) in the polyimide precursor, a polyimide which has good adhesion to the supporting substrate, high transparency, a high glass transition temperature, a small residual stress, and excellent elongation at break can be obtained.

Y in the general formula (4) can be calculated, for example, by the following formula. The compound represented by the general formula (4) is a compound wherein "both terminals are aminopropyl groups and R in the general formula (4)⁶And R⁷In the case of the condition of "all compounds being methyl or phenyl", the following formula holds.

y { (number average molecular weight of the compound represented by general formula (4) — (molecular weight of both terminal groups (aminopropyl) ═ 116.2) + (atomic weight of oxygen atom ═ 16.0) }/{ (R in general formula (4) }/{ (atomic weight of R in general formula (4) } {)⁶And R⁷Molecular weight of repeating structural unit of 74.15 × (A) when all methyl groups are presentMol% of radical) X0.01 + (R in the general formula (4)⁶And R⁷The molecular weight of the repeating structural unit in the case of all phenyl groups is 198.29 × 0.01} -1 in mol% of phenyl groups

On the other hand, in the general formula (2), X is¹And X²The monovalent organic group having 1 to 10 carbon atoms in (A) includes monovalent hydrocarbon groups having 1 to 10 carbon atoms. Examples of the monovalent hydrocarbon group having 1 to 10 carbon atoms include alkyl groups having 1 to 10 carbon atoms. Specific examples of the alkyl group having 1 to 10 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tert-butyl group, a pentyl group, and a hexyl group.

In addition, as X¹And X²In the (C1-10) monovalent alkylsilyl group, a monovalent alkylsilyl group to which an alkyl group having 1-10 carbon atoms is bonded is mentioned. Specific examples of the monovalent alkylsilyl group having 1 to 10 carbon atoms include a trimethylsilyl group, a triethylsilyl group, and the like.

In the general formula (2), R³As described above, the divalent organic group represented by the general formula (3) is preferably a diamine residue. R⁴Is a residue of an aromatic tetracarboxylic acid or a derivative thereof. R⁴The number of carbon atoms of (C) is preferably 6 to 40.

As provision of R³Examples of the diamine of (3) include 2,2 '-bis (trifluoromethyl) -4, 4' -diaminodiphenyl ether (6FODA), 2 '-bis (trifluoromethyl) -3, 3' -diaminodiphenyl ether, and 3,3 '-bis (trifluoromethyl) -4, 4' -diaminodiphenyl ether.

R in the general formula (2)³In the case of a diamine residue having a structure represented by the general formula (3), the diamine residue has a soft ether bond at the center of the structure. Therefore, the polyimide precursor according to the embodiment of the present invention can be inhibited from being imidized to obtain a polyimide resin film having a small in-plane/out-of-plane birefringence. Further, as the above R³The diamine residue of (3) has a trifluoromethyl group as an electron-withdrawing functional group. Therefore, intramolecular and intermolecular electron transfer in the polyimide precursor can be suppressed, and a polyimide resin film having high transparency can be obtained。

The polyimide precursor according to the embodiment of the present invention preferably contains 30 mol% or more, and more preferably 50 mol% or more, of the structural units of the divalent organic group represented by the general formula (3) in all diamine residues contained in the polyimide precursor. The upper limit of the content of the structural unit is not particularly limited, and is preferably 100 mol% or less.

As provision of R in the formula (2)⁴Examples of the tetracarboxylic acid of (a) include pyromellitic acid, 3,3 ', 4, 4' -biphenyltetracarboxylic acid, 2,3,3 ', 4' -biphenyltetracarboxylic acid, 2 ', 3, 3' -biphenyltetracarboxylic acid, 3,3 ', 4, 4' -benzophenonetetracarboxylic acid, bis (3, 4-dicarboxyphenyl) sulfone, bis (3, 4-dicarboxyphenyl) ether, 2-bis (4- (3, 4-dicarboxyphenoxy) phenyl) propane, and 9, 9-bis [4- (3, 4-dicarboxyphenoxy) phenyl ] propane]Fluorene, 4' - (hexafluoroisopropylidene)) diphthalic acid, and the like.

These tetracarboxylic acids may be used as they are, or may be used in the form of tetracarboxylic acid derivatives such as acid anhydrides, active esters, and active amides. Among these tetracarboxylic acid derivatives, anhydrides are preferably used because they do not generate by-products during polymerization. These tetracarboxylic acid derivatives may be used in combination of 2 or more.

In addition, R in the general formula (2)⁴The tetravalent organic group represented by the following general formula (5) is preferable.

[ chemical formula 14]

In the general formula (5), Y¹A divalent organic group having 1 to 3 carbon atoms which is directly bonded or may be substituted with 1 or more selected from the group consisting of an oxygen atom, a sulfur atom, a sulfonyl group and a halogen atom, or a divalent crosslinked structure selected from the group consisting of an ester bond, an amide bond, a carbonyl group, a thioether bond and an organic group having 1 to 20 carbon atoms and having an aromatic ring.

Examples of the compound providing the structure represented by the general formula (5) include 3,3 ', 4,4 ' -biphenyltetracarboxylic acid, 2,3,3 ', 4 ' -biphenyltetracarboxylic acid, 2 ', 3,3 ' -biphenyltetracarboxylic acid, 3,3 ', 4,4 ' -benzophenonetetracarboxylic acid, bis (3, 4-dicarboxyphenyl) sulfone, bis (3, 4-dicarboxyphenyl) ether, 9-bis [4- (3, 4-dicarboxyphenoxy) phenyl ] fluorene, and 4,4 ' - (hexafluoroisopropylidene) diphthalic acid.

For R in the formula (2)⁴Among them, aromatic tetracarboxylic acid residues having 1 or more structures selected from the group consisting of the structure represented by the general formula (6), the structure represented by the general formula (7), and the structure represented by the general formula (8) are particularly preferable. By reacting the compound with R⁴By including the structure represented by the general formula (6), a polyimide having a high glass transition temperature can be obtained. In addition, by making the R⁴By including the structure represented by the general formula (7), a polyimide having high transparency, small in-plane/out-of-plane birefringence and high glass transition temperature can be obtained. In addition, by making the R⁴By including the structure represented by the general formula (8), a polyimide having high transparency and small in-plane/out-of-plane birefringence can be obtained.

[ chemical formula 15]

The polyimide precursor according to the embodiment of the present invention preferably contains 5 mol% or more and 55 mol% or less, and more preferably 10 mol% or more and 45 mol% or less, of all acid dianhydride residues contained in the polyimide precursor. This can provide polyimide having less in-plane/out-of-plane birefringence. Examples of the structure of the acid anhydride residue having a fluorene skeleton include the structure represented by the above general formula (7).

The polyimide precursor according to the embodiment of the present invention preferably contains a residue of a diamine represented by the general formula (9).

[ chemical formula 16]

In the general formula (9), R⁸Is a substituted or unsubstituted phenyl group. s represents an integer of 1 to 4 inclusive.

R⁸Preferably phenyl or phenyl substituted by phenyl. For example, R⁸Is phenyl or biphenyl.

The diamine represented by the general formula (9) is a structure which must contain a carboxyl group. Therefore, in the polyimide precursor containing the residue of the diamine represented by the general formula (9), hydrogen bonds are strongly formed between molecules, and the intermolecular interaction is enhanced. By using such a polyimide precursor, a polyimide having a high glass transition temperature and excellent mechanical strength can be obtained.

The diamine represented by the general formula (9) includes, for example, a diamine represented by the following general formula (10).

[ chemical formula 17]

The diamine represented by the general formula (10) is specifically 3, 5-diaminobenzoic acid, 3, 4-diaminobenzoic acid, 2, 3-diaminobenzoic acid, or 2, 6-diaminobenzoic acid. In the present invention, the diamine represented by the general formula (9) is not limited to the specific examples of the diamines represented by the general formula (10).

The polyimide precursor according to the embodiment of the present invention preferably contains 1 mol% to 50 mol% of the residue of the diamine represented by the general formula (9) when the total amount of the polyimide precursor is 100 mol%. The polyimide precursor more preferably contains 5 to 40 mol% of the residue of the diamine represented by the general formula (9), and still more preferably contains 10 to 35 mol% of the residue of the diamine represented by the general formula (9).

The polyimide precursor according to the embodiment of the present invention may contain a triamine skeleton. The triamine has 3 amino groups and forms a branched molecular chain by bonding to 3 tetracarboxylic dianhydride components. The triamine skeleton introduces a branched chain structure into the molecular chain of the polyamic acid to form branched polyamic acid. This can increase the viscosity of the varnish in which the polyimide precursor is dissolved, and can improve the film thickness uniformity when coating is performed with a slit. Further, the molecular weight of the polyimide obtained from the polyimide precursor having a branched structure is larger than that in the case of not having a branched structure, and therefore, a polyimide resin film having excellent mechanical strength can be obtained. Such a polyimide precursor having a triamine skeleton can be obtained by using a triamine compound as one of polymerization components.

Specific examples of the triamine compound having no aliphatic group include 2,4,4 '-triaminodiphenyl ether (TAPE), 1,3, 5-tris (4-aminophenoxy) benzene (1,3,5-TAPOB), 1,2, 3-tris (4-aminophenoxy) benzene (1,2,3-TAPOB), tris (4-aminophenyl) amine, 1,3, 5-tris (4-aminophenyl) benzene, 3,4, 4' -triaminodiphenyl ether and the like. Specific examples of the aliphatic group-containing triamine compound include tris (2-aminoethyl) amine (TAEA) and tris (3-aminopropyl) amine.

As described above, the triamine constitutes a branch chain of the crosslinked structure in the molecular chain of the polyimide resin. Since the crosslinked structure of the polyimide resin is lost when the triamine is thermally decomposed, it is preferable to use a triamine component which does not have an aliphatic group and is not easily thermally decomposed. That is, 2,4, 4' -triaminodiphenyl ether (TAPE), 1,3, 5-tris (4-aminophenoxy) benzene (1,3,5-TAPOB), 1,2, 3-tris (4-aminophenoxy) benzene (1,2,3-TAPOB), and the like are preferably used.

In addition, the polyimide precursor according to the embodiment of the present invention may contain a tetraamine skeleton. Tetraamine has 4 amino groups and forms a branched molecular chain by bonding to 4 tetracarboxylic dianhydride components. The tetramine skeleton introduces a branched chain structure into the molecular chain of the polyamic acid to form the branched polyamic acid. This can increase the viscosity of the varnish in which the polyimide precursor is dissolved, and can improve the film thickness uniformity when coating is performed with a slit. Further, since the molecular weight of the polyimide obtained from the polyimide precursor having a branched structure is larger than that in the case of not having a branched structure, a polyimide having excellent mechanical strength can be obtained. Further, the glass transition temperature of the polyimide can be increased by including a tetraamine skeleton. This is considered to be because, when a tetracarboxylic dianhydride is reacted with a tetraamine, a benzimidazole structure having high heat resistance is partially formed. Such a polyimide precursor having a tetraamine skeleton can be obtained by using a tetraamine compound as one of the polymerization components.

Specific examples of the tetraamine compound include 1,2,4, 5-tetraaminobenzene, 3 ', 4, 4' -tetraaminobiphenyl, 3 ', 4, 4' -tetraaminodiphenyl sulfone, 3 ', 4, 4' -tetraaminodiphenyl ether, 3 ', 4, 4' -tetraaminodiphenyl sulfide, 2,3,6, 7-tetraaminonaphthalene, and 1,2,5, 6-tetraaminonaphthalene. Alternatively, specific examples of the tetraamine compound include compounds obtained by substituting a part of hydrogen bonded to an aromatic ring included in the polyamine compound or the diamine compound with a hydrocarbon or a halogen.

As the tetraamine component, a component which does not have an aliphatic group and is less likely to be thermally decomposed is preferably used, and further, from the viewpoint of improving transparency, an electron-withdrawing group is preferably used, similarly to the above-mentioned triamine. That is, 3 ', 4, 4' -tetraaminodiphenylsulfone and the like are preferably used.

In the present invention, the Hammett substituent constant (p, σ p) of the electron-withdrawing group is usually more than 0, preferably 0.01 or more, more preferably 0.1 or more, and particularly preferably 0.5 or more. The substituent constant of Hammett is described in "chemical review" edited by the chemical society of japan, modified 5 th edition, volume II, pill corporation, 2 months 2004, and 380 pages, for example. Examples of the electron-withdrawing group include a halogen atom, a cyano group, a carbonyl group having a hydrogen atom or a substituent, a perfluoroalkyl group such as a nitro group or a trifluoromethyl group, a sulfonyl group, and the like. Examples of the halogen atom include a fluorine atom, a bromine atom, a chlorine atom, and an iodine atom.

The polyimide precursor according to the embodiment of the present invention may contain other constituent units than the above-described constituent units within a range not to impair the effects of the present invention. Examples of the other structural units include polyimide as a dehydrated closed ring body of polyamic acid, polybenzoxazole as a dehydrated closed ring body of polyhydroxyamide, and the like.

Examples of the acid dianhydride that can be used in another structural unit include aromatic acid dianhydride, alicyclic acid dianhydride, and aliphatic acid dianhydride described in international publication No. 2017/099183. Examples of the diamine compound that can be used in other structural units include aromatic diamines, alicyclic diamines, and aliphatic diamines described in international publication No. 2017/099183.

In the polyimide precursor according to the embodiment of the present invention, a part of the structural unit (for example, the structural unit represented by the general formula (2)) included in the polyimide precursor may be imidized. By imidizing a part of the polyimide precursor, the viscosity stability of the resin solution containing the polyimide precursor during storage at room temperature can be improved. The imidization ratio of the polyimide precursor is preferably in the range of 1% to 50% from the viewpoint of solubility in a solution and viscosity stability. The lower limit of the imidization ratio is more preferably 5% or more. The upper limit of the imidization ratio is more preferably 30% or less.

Examples of the polyimide precursor partially imidized include resins having a repeating unit represented by general formula (11), resins having a repeating unit represented by general formula (12), and resins having a repeating unit represented by general formula (13).

[ chemical formula 18]

In the general formulae (11) to (13), R⁹Represents a divalent organic group. R¹⁰Represents a tetravalent organic group. W¹And W²Each independently represents a hydrogen atom, a monovalent organic group having 1 to 10 carbon atoms, or a monovalent alkylsilyl group having 1 to 10 carbon atoms. As R⁹The divalent organic group (2) is the same as the diamine residue described above. As R¹⁰The tetravalent organic group (2) is the same as the tetracarboxylic acid residue described above.

The polyimide precursor according to an embodiment of the present invention preferably has a weight average molecular weight (Mw) of 10,000 to 1,000,000, more preferably 10,000 to 500,000, and still more preferably 20,000 to 400,000. The number average molecular weight (Mn) of the polyimide precursor is 5,000 to 1,000,000, preferably 5,000 to 500,000, and particularly preferably 15,000 to 300,000. When the weight average molecular weight and the number average molecular weight of the polyimide precursor are within the above ranges, the strength of the polyimide resin film obtained after curing can be improved without deteriorating the flatness of the coating film of the polyimide resin obtained.

In the present invention, the weight average molecular weight, the number average molecular weight and the molecular weight distribution were measured by using DP-8020 type GPC apparatus manufactured by TOSOH (protective column: TSK guard Colomn, ALPHA column: TSK-GEL. ALPHA. -M, developing solvent: N, N' -dimethylacetamide (DMAc), 0.05M-LiCl and 0.05% phosphoric acid were added).

The polyimide precursor according to the embodiment of the present invention may be a polyimide precursor whose end is blocked with a blocking agent. The molecular weight of the polyimide precursor can be adjusted to a preferred range by reacting the terminal of the polyimide precursor with an end-capping agent. When the terminal monomer in the polyimide precursor is a diamine compound, a dicarboxylic anhydride, a monocarboxylic acid chloride compound, a monocarboxylic acid active ester compound, a dialkyl dicarbonate, or the like can be used as a capping agent in order to block the amino group of the diamine compound. When the terminal monomer in the polyimide precursor is an acid dianhydride, a monoamine, a monool, or the like may be used as an end-capping agent in order to block an acid anhydride group of the acid dianhydride.

< polyimide precursor composition >

The polyimide precursor according to the embodiment of the present invention may be mixed with appropriate components to form a polyimide precursor composition. The components that can be contained in the polyimide precursor composition are not particularly limited, and examples thereof include a solvent, an ultraviolet absorber, a coupling agent, a thermal crosslinking agent, an inorganic filler, a surfactant, an internal release agent, and a colorant.

(solvent)

The solvent contained in the polyimide precursor composition is not particularly limited, and a known solvent can be used. Examples of the solvent include N-methyl-2-pyrrolidone, N-dimethylformamide, N-dimethylacetamide, N-dimethylisobutyramide, 3-methoxy-N, N-dimethylpropionamide, 3-butoxy-N, N-dimethylpropionamide, γ -butyrolactone, ethyl lactate, 1, 3-dimethyl-2-imidazolidinone, N' -dimethylpropyleneurea, 1,3, 3-tetramethylurea, dimethyl sulfoxide, sulfolane, propylene glycol monomethyl ether acetate, diethylene glycol ethyl methyl ether, diethylene glycol dimethyl ether, water, and a solvent described in international publication No. 2017/099183. These can be used alone, or in combination of 2 or more. Among these solvents, aprotic polar solvents such as N-methyl-2-pyrrolidone and N, N-dimethylformamide are preferably contained, and N-methyl-2-pyrrolidone is particularly preferably contained.

The lower limit of the content of the solvent in the polyimide precursor composition is preferably 200 parts by weight or more, and more preferably 300 parts by weight or more, based on 100 parts by weight of the polyimide precursor. The upper limit of the content of the solvent is preferably 2,000 parts by weight or less, and more preferably 1,500 parts by weight or less. When the content of the solvent is in the range of 200 parts by weight or more and 2,000 parts by weight or less, the concentration and viscosity of the polyimide precursor composition are those suitable for coating. As a result, when the polyimide precursor composition is coated by a slit coater, good film thickness uniformity can be obtained.

(surfactant)

The polyimide precursor composition according to the embodiment of the present invention may contain a surfactant. Examples of the surfactant include fluorine-based surfactants such as Fluorad (trade name, manufactured by Sumitomo 3M Co.), MEGAFAC (trade name, manufactured by DIC Co.), and Surflon (trade name, manufactured by Asahi glass Co.). Examples of the surfactant include organosiloxane surfactants such as KP341 (trade name, product of shin-Etsu chemical industries, Ltd.), POLYFLOW, GLANOL (trade name, product of Kyowa chemical industries, Ltd.), and BYK (product of BYK Chemie). Examples of the surfactant include polyoxyalkylene lauryl ether, polyoxyethylene oleyl ether and polyoxyethylene cetyl ether surfactants such as EMULMIN (manufactured by sanyo chemical industries, Ltd.). Further, as the surfactant, an acrylic polymer surfactant such as POLYFLOW (trade name, manufactured by Kyoeisha chemical Co., Ltd.) can be given. The content of the surfactant contained in the polyimide precursor composition is preferably 0.001 parts by weight or more and 1 part by weight or less with respect to 100 parts by weight of the polyimide precursor.

(coupling agent)

The polyimide precursor composition according to the embodiment of the present invention may be added with a coupling agent such as a silane coupling agent or a titanium coupling agent in order to improve adhesion to a base material. As the above-mentioned coupling agent, known coupling agents can be used. In addition, the coupling agent can also be used in combination with 2 or more. The content of the coupling agent contained in the polyimide precursor composition is preferably 0.01 wt% or more and 2 wt% or less with respect to 100 wt% of the polyimide precursor.

(ultraviolet absorber)

The polyimide precursor composition according to the embodiment of the present invention may contain an ultraviolet absorber. By incorporating an ultraviolet absorber into a polyimide precursor composition, deterioration of physical properties such as transparency and mechanical properties of a polyimide obtained from the polyimide precursor composition can be greatly suppressed when the polyimide is exposed to sunlight for a long period of time.

As the ultraviolet absorber, known ones can be used without particular limitation, and from the viewpoint of transparency and non-coloring property, benzotriazole-based compounds, benzophenone-based compounds, and triazine-based compounds are preferably used.

The content of the ultraviolet absorber contained in the polyimide precursor composition is preferably 0.1 part by weight or more and 10 parts by weight or less with respect to 100 parts by weight of the polyimide precursor. By containing the ultraviolet absorber in the above range in the polyimide precursor composition, the light resistance of the polyimide can be improved without impairing the transparency of the polyimide obtained.

< method for producing polyimide precursor >

The polyimide precursor can be synthesized by polymerization of a diamine compound and a tetracarboxylic acid or a derivative thereof, as exemplified by polyamic acid, polyamic acid ester, polyamic acid silyl ester, and the like. Examples of the tetracarboxylic acid derivative include an acid anhydride, an active ester, and an active amide of the tetracarboxylic acid. The reaction method of the above polymerization reaction is not particularly limited as long as the target polyimide precursor can be produced, and a known reaction method can be used.

Specific reaction methods of the above polymerization reaction include the following: and (2) charging a predetermined amount of the diamine component and the solvent into a reactor, dissolving the diamine component in the solvent, charging a predetermined amount of the acid dianhydride component into the reaction vessel, and stirring at room temperature to 120 ℃ for 0.5 to 30 hours. The polyimide precursor obtained by such a reaction method can be formed into a polyimide precursor composition by appropriately adding the aforementioned components such as a solvent, a surfactant, an internal mold release agent, and a coupling agent.

The water content in the polyimide precursor or the polyimide precursor composition obtained in the above manner is preferably 0.05 mass% or more and 3.0 mass% or less. When the water content is in the above range, the viscosity storage stability of the polyimide precursor or the polyimide precursor composition can be improved. The water content here means a value obtained by adjusting the liquid temperature of the target solution to 23 ℃ and measuring the solution at the liquid temperature by the karl fischer method. In order to measure the water content by the Karl Fischer method, the water content was measured by a volumetric titration method in accordance with JIS K0068(2001) using a Karl Fischer water content titration apparatus (for example, "MKS-520" (trade name, manufactured by Kyoto electronics industries, Ltd.).

< polyimide >

The polyimide according to an embodiment of the present invention is a polyimide formed by imidizing the polyimide precursor. The polyimide precursor composition is obtained by adding the above-described components such as the solvent to the polyimide precursor according to the embodiment of the present invention, and includes the polyimide precursor. That is, the polyimide according to the embodiment of the present invention may be synthesized by imidizing the polyimide precursor composition. Hereinafter, a polyimide obtained by imidizing a polyimide precursor will be described as an example.

The method of imidization is not particularly limited, and as the method of imidization in the present invention, imidization by heating and chemical imidization can be exemplified. Among them, thermal imidization is preferred from the viewpoint of heat resistance and transparency in the visible light region of the polyimide obtained.

For the imidization by heating, it is preferable to convert a polyimide precursor into a polyimide by heating it in a range of 180 ℃ or more and 550 ℃ or less. Hereinafter, imidation by heating is appropriately referred to as thermal imidation. The step of performing thermal imidization is appropriately referred to as a thermal imidization step. When a coating film is formed from a solution of a polyimide precursor and the polyimide precursor is thermally imidized, the thermal imidization step may be performed after a step of evaporating a solvent from the coating film of the polyimide precursor (hereinafter, appropriately referred to as a drying step) and after several steps.

In the drying step, specifically, the coating film of the polyimide precursor may be dried under vacuum or heated, and it is preferable to evaporate the solvent without clouding in view of the transparency of the polyimide resin film after imidization. In the drying step, a hot plate, an oven, infrared rays, a vacuum chamber, or the like is used to dry the coating film of the polyimide precursor. The heating temperature for drying is varied depending on the kind and purpose of the object to be heated, and is preferably in the range of room temperature to 170 ℃ for 1 minute to several hours. The room temperature is usually 20 to 30 ℃ and preferably 25 ℃. Further, the drying process may be performed a plurality of times under the same conditions or different conditions.

The atmosphere in the thermal imidization step is not particularly limited, and may be air or an inert gas such as nitrogen or argon. The polyimide precursor according to the embodiment of the present invention has high resistance to oxidation. Therefore, in the thermal imidization step, the coating film of the polyimide precursor is heated in an oven under an atmospheric atmosphere for 30 minutes to 2 hours to obtain a transparent polyimide resin film.

In addition, the time required until the heating temperature for thermal imidization is reached is not particularly limited, and a temperature raising method suitable for the heating form of the production line may be selected. For example, the coating film of the polyimide precursor formed on the substrate may be heated in an oven while being heated from room temperature to a heating temperature for thermal imidization for 5 to 120 minutes. Alternatively, the polyimide precursor coating film formed on the substrate may be put into an oven heated to a temperature in the range of 180 ℃ to 550 ℃ in advance, and heated, while maintaining the original state. If necessary, the coating film of the polyimide precursor may be heated under reduced pressure.

In the above-described embodiments, the polyimide formed by imidizing the polyimide precursor is exemplified, but the present invention is not limited thereto, and the polyimide may be obtained by imidizing the polyimide precursor composition. For example, the target polyimide can be obtained by performing the above steps by replacing the "polyimide precursor" in the thermal imidization step and the drying step with the "polyimide precursor composition".

The polyimide according to the embodiment of the present invention may be represented by a polyimide containing a structure represented by general formula (1) and a structural unit represented by general formula (14).

[ chemical formula 19]

In the general formula (1), R¹And R²Each independently represents a monovalent organic group having 1 to 20 carbon atoms. m represents an integer of 1 to 200 inclusive.

[ chemical formula 20]

In the general formula (14), R³Represents a divalent organic group represented by the general formula (3). R⁴Represents an aromatic tetracarboxylic acid residue.

[ chemical formula 21]

R in the general formulae (1) and (14)¹～R⁴The details of (a) are the same as those described for the polyimide precursor.

The polyimide preferably contains a structure represented by the general formula (1) in an amount of 0.1 to 30% by mass, based on 100% by mass of the total amount of the polyimide. In addition, the polyimide preferably contains 30 mol% or more of the structural unit of the divalent organic group represented by the general formula (3) in all diamine residues contained in the polyimide.

< polyimide resin film >

The polyimide resin film according to the embodiment of the present invention is a film containing the polyimide according to the embodiment of the present invention. Hereinafter, the polyimide resin film according to the embodiment of the present invention is appropriately abbreviated as "polyimide resin film".

In the present invention, the polyimide resin film can be obtained, for example, by the following method. Examples of a method for forming a polyimide resin film include a coating film forming step of forming a coating film by applying a polyimide precursor according to an embodiment of the present invention onto a substrate, a drying step of evaporating a solvent from the coating film, and an imidization step of imidizing the polyimide precursor.

In the method for forming a polyimide resin film, the coating film of the polyimide precursor can be formed by applying the polyimide precursor onto a substrate in the coating film forming step. Examples of a method for forming a coating film by applying the polyimide precursor to a substrate include a roll coating method, a spin coating method, a slit coating method, and a method of coating using a doctor blade, a coater, and the like. In the coating film forming step, the thickness, surface smoothness, and the like of the coating film can be controlled by repetition of coating. Among them, the slit die coating method is preferable from the viewpoint of surface smoothness of the coating film and uniformity of film thickness.

The thickness of the coating film is not particularly limited, and may be suitably selected depending on the intended use, and is, for example, 1 to 500. mu.m, preferably 2 to 250. mu.m, and particularly preferably 5 to 125. mu.m. Examples of the substrate include a polyethylene terephthalate (PET) film, a polyethylene naphthalate (PEN) film, a polybutylene terephthalate (PBT) film, a silicon wafer, a glass wafer, an oxide wafer, a glass substrate, a Cu substrate, and a SUS plate. Among them, a glass substrate is preferable from the viewpoint of surface smoothness and dimensional stability during heating. As the glass constituting the glass substrate, alkali-free glass is particularly preferable from the viewpoint of dimensional stability.

Next, in the drying step, the solvent is evaporated from the coating film on the substrate, thereby drying the coating film. Specifically, in the drying step, the coating film may be dried under vacuum or heated, and it is preferable to evaporate the solvent without cloudiness in view of the transparency of the polyimide resin film after imidization. In the drying step, a hot plate, an oven, infrared rays, a vacuum chamber, or the like is used for drying the coating film.

The heating temperature for drying is varied depending on the kind and purpose of the object to be heated such as a coating film, and is preferably in the range of room temperature to 170 ℃ for 1 minute to several hours. The room temperature is usually 20 to 30 ℃ and preferably 25 ℃. Further, the drying process may be performed a plurality of times under the same conditions or different conditions.

Then, in the imidization step, the polyimide precursor in the coating film on the substrate is imidized, thereby forming a polyimide resin film on the substrate. The polyimide resin film obtained through the above steps may be used after being peeled from the substrate, or may be used as it is without being peeled.

The thickness of the polyimide resin film obtained in the above manner can be appropriately selected depending on the intended use, and is preferably 1 to 100 μm, more preferably 5 to 30 μm, and particularly preferably 7 to 20 μm.

In the above-described embodiment, a polyimide resin film formed by imidizing a coating film of a polyimide precursor is exemplified, but the present invention is not limited thereto, and a polyimide resin film may be obtained by imidizing a coating film of a polyimide precursor composition. For example, the desired polyimide resin film can be obtained by performing the above steps by replacing the "polyimide precursor" in the above steps such as the thermal imidization step with the "polyimide precursor composition".

The glass transition temperature of the polyimide resin film obtained in the above manner (i.e., the polyimide resin film according to the embodiment of the present invention) is preferably 240 ℃ or higher, and more preferably 250 ℃ or higher.

The density of the polyimide resin film according to the embodiment of the present invention is preferably 1.20g/cm³Above and 1.43g/cm³Hereinafter, more preferably 1.23g/cm³Above and 1.40g/cm³The following. The density of the polyimide resin film is related to the intermolecular interaction, and when the intermolecular interaction is strong, the density becomes high. Therefore, when the density of the polyimide resin film is high, the polyimide resin film having a high glass transition temperature can be obtained. On the other hand, when the intermolecular interaction is weak, voids can be present between the molecules, and therefore a polyimide resin film having small in-plane/out-of-plane birefringence can be obtained. Further, since the internal stress can be relaxed by the void, warpage of the substrate made of the polyimide resin film can be suppressed. Thus, the density of the polyimide resin film was 1.20g/cm³Above and 1.43g/cm³In the following case, since the intermolecular interaction is in a preferable range, a polyimide resin film having a high glass transition temperature, a small in-plane/out-of-plane birefringence, and suppressed substrate warpage can be obtained.

The polyimide resin film according to the embodiment of the present invention preferably has an in-plane/out-of-plane birefringence of 0.01 or less, and more preferably 0.005 or less. By setting the in-plane/out-of-plane birefringence of the polyimide resin film to 0.01 or less, color shift when viewed from an oblique direction can be prevented, and external light reflection when a circularly polarizing film is used can be suppressed.

The polyimide resin film according to the embodiment of the present invention preferably has a yellowness index of 3 or less. By setting the yellowness index of the polyimide resin film to 3 or less, a flexible substrate in which the yellowness is suppressed can be formed. Further, by using the flexible substrate, a flexible device in which yellow tone is suppressed can be manufactured.

< use >)

The polyimide precursor, the polyimide, and the polyimide resin film containing the polyimide precursor and the polyimide according to the embodiment of the present invention are useful for electronic devices. More specifically, the present invention is applicable to a display device such as a liquid crystal display, an organic EL display, a touch panel, electronic paper, a color filter, a Micro LED display, a solar cell, a light receiving device such as a CMOS, and the like. These electronic devices are preferably flexible devices. The flexible device according to the embodiment of the present invention includes the polyimide resin film. The polyimide resin film described above can be preferably used as a substrate in an electronic device such as a flexible device, particularly a flexible substrate.

Examples

The present invention will be described below by way of examples, but the present invention is not limited to the following examples. First, materials used in the following examples and comparative examples, and measurement and evaluation performed thereon will be described.

< Material >

As the acid dianhydride, the following acid dianhydrides can be suitably used.

ODPA: 3,3 ', 4, 4' -Diphenyl Ether Tetraformic dianhydride

BPAF: 9, 9-bis [4- (3, 4-dicarboxyphenoxy) phenyl ] fluorene dianhydride

X-22-168-P5-B: carboxylic anhydride-modified methylphenylsilicone oil having a number average molecular weight of 4,200, y of 34 to 38, phenyl group of 25:75 mol%, manufactured by shin-Etsu chemical Co., Ltd.)

CBDA: cyclobutanetetracarboxylic dianhydride

As the diamine compound, the diamine compounds shown below can be suitably used.

6 FODA: bis (trifluoromethyl) -4, 4' -diaminodiphenyl ether

CHDA: trans-1, 4-diaminocyclohexane

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

SiDA: 1, 3-bis (3-aminopropyl) tetramethyldisiloxane

X-22-9409: amine-modified methylphenylsilicone oil having both ends (number average molecular weight of 1,340, y: 10 to 11, phenyl: methyl: 25:75 mol%, manufactured by shin-Etsu chemical Co., Ltd.)

X22-1660B-3: amine-modified methylphenylsilicone oil having both ends (number average molecular weight of 4,400, y: 39 to 41, phenyl: methyl: 25:75 mol%, manufactured by shin-Etsu chemical Co., Ltd.)

As the solvent, the following solvents can be suitably used.

NMP: n-methyl-2-pyrrolidone

GBL: gamma-butyrolactone

MMBAc: acetic acid 3-methoxy-3-methyl-1-butyl ester

< evaluation >

(item 1: preparation of polyimide resin film (on item 1: glass substrate))

Item 1 describes a method for producing a polyimide resin film (on item 1 glass substrate). The polyimide resin film of item 1 was prepared by applying the varnish prepared in each of the following examples and comparative examples to a 100mm × 100mm × 0.5mm thick alkali-free glass substrate (AN-100, Asahi glass Co., Ltd.) using a spin coater (MS-A200) manufactured by Chilo corporation so that the cured film thickness became 10. + -. 0.5. mu.m. Then, pre-baking of the varnish coating film was performed using a hot plate. As the hot plate, a hot plate heated to 120 ℃ in advance was used to dry the varnish coating film over 6 minutes. The pre-baked film obtained as described above was cured in an oven ("IHPS-222"; manufactured by ESPEC corp.) at 240 ℃ for 60 minutes in air, thereby producing a polyimide resin film on the alkali-free glass substrate (1 st glass substrate).

(item 2: preparation of polyimide resin film (Release film))

In item 2, a method for producing a polyimide resin film (release film) is described. The polyimide resin film according to item 2 is produced by forming a notch in a portion 1cm from the four side end of the polyimide resin film (on the 1 st glass substrate) shown in item 1, using a single-blade knife, and immersing the polyimide resin film in hot water heated to 60 ℃ for 60 minutes. Then, the polyimide resin film was peeled from the 1 st glass substrate, thereby obtaining a polyimide resin film as a release film.

(item 3: preparation of polyimide resin film (on the 2 nd glass substrate))

In item 3, a method for producing a polyimide resin film (on the 2 nd glass substrate) will be described. The polyimide resin film of item 3 was produced on the 2 nd glass substrate in the same manner as in item 1 above, except that a glass substrate (TEMPAX) having a thickness of 50mm × 50mm × 1.1mm was used as the 2 nd glass substrate.

(item 4: preparation of polyimide resin film (on the 3 rd glass substrate))

In item 4, a method for producing a polyimide resin film (on the 3 rd glass substrate) will be described. The varnish prepared in each of the following examples and comparative examples was applied to a glass substrate (AN-100, manufactured by asahi glass company) having a thickness of 730mm × 920mm × 0.5mm, which is a 3 rd glass substrate, using a slit coater (manufactured by Toray Engineering co., ltd.) so that the cured film thickness becomes 10 ± 0.5 μm in the production of the polyimide resin film according to the 4 th item. Then, a heating vacuum dryer and a hot plate were used to pre-bake the varnish coating film. In the heating type vacuum dryer, the drying of the coating film of the varnish was performed under the following conditions: the upper plate was heated to 60 ℃ and the lower plate was heated to 40 ℃ to reduce the internal pressure to 60Pa over 150 seconds. As the hot plate, a hot plate heated to 120 ℃ in advance was used to dry the varnish coating film over 6 minutes. The prebaked film obtained as described above was cured in an oven at 240 ℃ for 60 minutes in air, thereby producing a polyimide resin film on the 3 rd glass substrate.

(item 5: production of polyimide resin film (on silicon substrate))

In item 5, a method for producing a polyimide resin film (on a silicon substrate) is described. The polyimide resin film of item 5 was produced by spin-coating the varnish prepared in each of the following examples and comparative examples on a 6-inch silicon substrate using a coating and developing apparatus (Mark-7) manufactured by Tokyo Electron limited so that the cured film thickness became 10 ± 0.5 μm. Then, a pre-baking treatment was performed at 120 ℃ for 6 minutes on the varnish coating film on the silicon substrate using a hot plate of Mark-7. The pre-baked film obtained as described above was cured in an oven at 240 ℃ for 60 minutes in air, thereby producing a polyimide resin film on a silicon substrate.

(item 6: measurement of Density)

In item 6, the measurement of the density of the polyimide resin film is described. For the density measurement in item 6, the polyimide resin film (release film) described in item 2 above was cut into a size of 40mm × 40mm as a measurement sample, and a specific gravity measurement set (AD-1653-BM, A)&D Company, manufactured by Limited) at room temperature of 25 ℃ in an atmosphere having a relative humidity of 65%, and the density of the sample was measured by the Archimedes method. At this time, water was used as an immersion liquid for immersing the measurement sample. For the density measurement, one measurement sample was subjected to 2 times, and the average value thereof was taken as the density (g/cm) of the measurement sample³)。

(item 7: measurement of in-plane/out-of-plane birefringence)

In item 7, the measurement of in-plane/out-of-plane birefringence of a polyimide resin film is described. In the measurement of in-plane/out-of-plane birefringence according to item 7, the TE refractive index (n (TE)) and the TM refractive index (n (TM)) at a wavelength of 632.8nm were measured using a prism coupler (PC 2010, manufactured by METRICON corporation). n (TE) and n (TM) are refractive indices in a direction parallel to and perpendicular to the surface of the polyimide resin film, respectively. The in-plane/out-of-plane birefringence is calculated as the difference (n (TE) -n (TM)) between n (TE) and n (TM). In this measurement, the polyimide resin film (release film) shown in the above item 2 was used. Further, the in-plane/out-of-plane birefringence was evaluated for excellent, good, and defective properties by the following evaluation methods.

Excellent (A): in-plane/out-of-plane birefringence less than 0.0021

Good (B): in-plane/out-of-plane birefringence of 0.0021 to less than 0.0030

Good (C): in-plane/out-of-plane birefringence of 0.0030 or more and less than 0.0050

Failure (D): in-plane/out-of-plane birefringence of 0.0050 or more

(item 8: measurement of yellowness)

In item 8, the measurement of the yellowness of the polyimide resin film is described. The yellowness index of the polyimide resin film was measured using a colorimeter (SM-T45, manufactured by Suga Test Instruments co., ltd.) in the measurement of the yellowness index in item 8. The yellow index was measured in a transmitted light mode using a C light source as a light source. In this measurement, the polyimide resin film (on the 2 nd glass substrate) described in the above item 3 was used.

(item 9: measurement of haze value)

In item 9, the measurement of the haze value of the polyimide resin film is described. For the measurement of the haze value in the item 9, the haze value (%) of the polyimide resin film (on the 2 nd glass substrate) shown in the above item 3 was measured using a direct-reading haze computer (Suga Test Instruments co., ltd. HGM2DP, light source C). As each value, an average value of 3 measurements was used.

(item 10: measurement of 1% weight loss temperature (Td 1))

In item 10, the measurement of the 1% weight loss temperature of the polyimide resin film is described. The 1% weight loss temperature in item 10 was measured under a nitrogen gas flow using a thermogravimetric apparatus (TGA-50, manufactured by shimadzu corporation). The temperature raising method is performed under the following conditions. In the 1 st stage, the temperature was raised to 150 ℃ at a rate of 3.5 ℃/min to remove the water adsorbed on the sample of the polyimide resin film, and in the 2 nd stage, the sample was cooled to room temperature at a rate of 5 ℃/min. In the 3 rd stage, a formal measurement was performed at a temperature increase rate of 10 ℃/min, and the 1% thermal weight reduction temperature of the polyimide resin film was determined. In this measurement, the polyimide resin film (release film) shown in the above item 2 was used.

(item 11: measurement of glass transition temperature (Tg))

In item 11, the measurement of the glass transition temperature of the polyimide resin film is described. For the measurement of the glass transition temperature in the item 11, the measurement was performed under a nitrogen gas flow using a thermomechanical analyzer (EXSTAR 6000TMA/SS6000, manufactured by SII NanoTechnology Inc.). The temperature raising method is performed under the following conditions. In the 1 st stage, the temperature was raised to 150 ℃ at a rate of 5 ℃/min to remove the water adsorbed on the sample of the polyimide resin film, and in the 2 nd stage, the sample was air-cooled to room temperature at a rate of 5 ℃/min. In the 3 rd stage, the glass transition temperature of the sample was determined by performing a main measurement at a temperature increase rate of 5 ℃/min. In this measurement, the polyimide resin film (release film) shown in the above item 2 was used.

(item 12: measurement of elongation at Break)

In item 12, the measurement of the elongation at break of the polyimide resin film is described. The measurement of elongation at break in item 12 is carried out by cutting the polyimide resin film (release film) described in item 2 above into long strips having a width of 1cm and a length of 9cm, preparing samples, and stretching the samples using TENSILON (RTM-100, ORIENTEC corporation) to measure the elongation at break. In this case, the sample was stretched at a stretching rate of 50mm/min in an atmosphere of 23.0 ℃ at room temperature and 45.0% RH, with an initial length of 50 mm. For each sample of the polyimide resin film, 10 samples were subjected to the measurement of elongation at break, and of the measurement results of the 10 samples, the average value of 5 samples ranked in the top five was determined as the elongation at break. Further, the following evaluation methods were used to determine the elongation at break as excellent, good, or bad.

Excellent (A): elongation at break of 40% or more

Good (B): the elongation at break is more than 25 percent and less than 40 percent

Good (C): the elongation at break is more than 10 percent and less than 25 percent

Failure (D): the elongation at break is less than 10 percent

(item 13: measurement of residual stress)

In item 13, the measurement of the residual stress of the polyimide resin film is described. The residual stress in item 13 was measured using a thin film stress measuring apparatus (FLX-3300-T) manufactured by KLA-Tencor Corporation. For this measurement, the polyimide resin film (on a silicon substrate) shown in the above item 5 was used. In this case, the polyimide resin film was dehydrated and baked by heating at 150 ℃ for 30 minutes in a nitrogen atmosphere before measurement, and then cooled to 30 ℃ in a nitrogen atmosphere, and the residual stress of the polyimide resin film after drying at 30 ℃ was measured.

(item 14: measurement of warpage of substrate)

In item 14, the measurement of the substrate warpage will be described. In the measurement of the warpage of the substrate in item 14, a test plate was placed on a precision stone plate (1000mm × 1000mm) manufactured by MITUTOYO corporation such that the glass of the test plate was in contact with the precision stone plate. At this time, the polyimide resin film (on the 3 rd glass substrate) shown in the above item 4 was used as a test plate. Then, the amount (distance) of the test plate floating from the precision stone plate was measured using a feeler gauge for the total of 8 points of the respective midpoints and vertices of the 4 sides of the test plate, and the average value of these was used as the amount of warpage of the test plate, that is, the amount of substrate warpage. The measurement was performed at room temperature of 23 ℃ and humidity of 55%. The substrate warpage was evaluated for excellence, goodness, and defectiveness by the following evaluation methods.

Excellent (A): the warpage of the substrate is less than 0.21mm

Good (B): the warpage of the substrate is more than 0.21mm and less than 0.28mm

Good (C): the warpage of the substrate is more than 0.28mm and less than 0.35mm

Failure (D): the warpage of the substrate is more than 0.35mm

(item 15: measurement of substrate adhesion force (90 ℃ peeling test))

In item 15, the measurement of the substrate adhesion force is described. The measurement of the substrate adhesion force according to the 15 th item is carried out by cutting the polyimide resin film (on the 1 st glass substrate) described in the 1 st item into pieces having a width of 10mm and a length of 100mm, subjecting the pieces to a dehydration baking treatment at 120 ℃ for 6 minutes using a hot plate, and then carrying out a 90 ° peel test at a tensile rate of 50 mm/min. In the 90 ° peel test, the 90 ° peel strength (N/cm) of the polyimide resin film with respect to the 1 st glass substrate in the test sample was measured using an adhesion tester (manufactured by yamamoto gilding tester) in accordance with JIS C6481(1996, copper clad laminate test method for printed wiring boards). Further, the substrate adhesion force of the polyimide resin film was determined to be excellent, good, and defective by the following evaluation methods based on the measurement results of the 90 ° peel strength.

Excellent (A): a 90 DEG peel strength of 1.5N/cm or more

Good (B): a 90 DEG peel strength of 1.0N/cm or more and less than 1.5N/cm

Good (C): a 90 DEG peel strength of 0.5N/cm or more and less than 1.0N/cm

Failure (D): the 90-degree peel strength is less than 0.5N/cm

(item 16: preparation of laminate and appearance confirmation)

In item 16, the production and appearance of the laminate will be described. For the production of the laminate and the visual inspection of the appearance in the 16 th item, a SiON film was produced on the polyimide resin film (on the 3 rd glass substrate) shown in the 4 th item by plasma CVD (deposition temperature: 240 ℃ C., film thickness: 100 nm). Thus, a laminate of the polyimide resin film and the SiON film was produced. Then, the appearance of the laminate was confirmed at a magnification of 50 times using an optical microscope (OPTIPHOT 300, manufactured by Nikon corporation). The appearance of the laminate after production was confirmed to be excellent, good, and defective by the following evaluation method.

Excellent (A): no wrinkles were observed on the entire surface of the laminate, and the surface of the laminate was smooth

Good (B): the occurrence of wrinkles was observed in a part of the laminate, but the area of the position where wrinkles occurred was 5% or less of the entire laminate surface

Good (C): the occurrence of wrinkles was observed in a part of the laminate, but the area of the position where wrinkles occurred was 15% or less of the entire laminate surface

Failure (D): the area of the wrinkle-forming site is greater than 30% of the entire surface of the laminate

(item 17: production of color Filter Using laminate)

In item 17, the production of a color filter using a laminate containing a polyimide resin film will be described. In the production of a color filter according to item 17, the production of a resin black matrix and the production of a colored layer are carried out by the following methods, and the target color filter is produced through these steps.

Production example 1 production of resin Black matrix

In production example 1, a black resin composition (black resin composition for a resin black matrix) composed of polyamic acid in which a black pigment was dispersed was spin-coated on the SiON film of the laminate shown in item 16, and the coating film of the black resin composition was dried at 130 ℃ for 10 minutes by a hot plate to form a black resin coating film. Next, a positive photoresist ("SRC-100" manufactured by Shipley corporation) was spin-coated on the black resin coating film, and prebaked with a hot plate at 120 ℃ for 5 minutes using an ultra-high pressure mercury lamp at 100mJ/cm²The mask exposure was performed by irradiating ultraviolet rays (in terms of i-line). Then, development of the positive photoresist and etching of the black resin coating film were simultaneously carried out using a 2.38% aqueous tetramethylammonium hydroxide solutionThis step forms a pattern of the black resin coating film. Then, the black resin coating film patterned by stripping the positive photoresist with methyl cellosolve acetate was heated in an oven at 240 ℃ for 60 minutes to imidize the black resin coating film, thereby forming a resin black matrix in which carbon black was dispersed in a polyimide resin. In production example 1, a resin laminate having a resin black matrix patterned on the SiON film of the laminate was obtained in the above manner. The thickness of the resin black matrix was measured, and found to be 1.4. mu.m.

Production example 2 production of colored layer

In production example 2, an acrylic photosensitive red resist was spin-coated on the resin laminate having the resin black matrix formed by patterning, which was produced in production example 1, so that the film thickness at the opening of the black matrix after the heat treatment became 2.0 μm, and prebaked with a hot plate at 100 ℃ for 10 minutes. Thereby, a red colored layer was obtained. Next, using an ultraviolet exposure machine (PLA-5011, manufactured by Canon corporation), a chromium photomask was used to transmit light in an island shape at a rate of 100mJ/cm²The acrylic photosensitive red resist in the black matrix opening and a part of the area on the resin black matrix was exposed under the conditions (i-line conversion). The exposed acrylic photosensitive red resist was developed by immersing it in a developer containing 0.2% aqueous tetramethylammonium hydroxide. Next, the red color layer was washed with pure water, and then subjected to heat treatment in an oven at 230 ℃ for 30 minutes, thereby producing a red pixel. In the same manner as above, a green pixel formed of an acrylic photosensitive green resist and a blue pixel formed of an acrylic photosensitive blue resist were produced. As a result, the target color filter is obtained. Next, the rotational speed of the rotator was adjusted so that the thickness of the colored layer portion after the heat treatment became 2.5 μm, and the transparent resin composition was applied to the pixels and the resin black matrix. Then, the coating film of the transparent resin composition was subjected to a heat treatment in an oven at 230 ℃ for 30 minutes to prepare a cover coat layer.

Fig. 1 is a schematic cross-sectional view showing one example of the structure of a color filter including a polyimide resin film according to an embodiment of the present invention. As shown in fig. 1, the color filter 6 includes a polyimide resin film 1 and a gas barrier layer 2. The polyimide resin film 1 is an example of the polyimide resin film according to the embodiment of the present invention, and can be produced, for example, by the method described in any one of items 1 to 5 above. The gas barrier layer 2 is a layer for protecting the polyimide resin film 1 from a gas such as oxygen, and is formed of, for example, the SiON film shown in the above 16 th item. As shown in fig. 1, a gas barrier layer 2 is formed on a polyimide resin film 1. These polyimide resin film 1 and gas barrier layer 2 constitute the laminate shown in item 16 above.

As shown in fig. 1, the color filter 6 includes a black matrix 3, red pixels 4R, green pixels 4G, blue pixels 4B, and a cover coat layer 5 on the gas barrier layer 2. The black matrix 3 is, for example, a resin black matrix formed on the gas barrier layer 2 by the method shown in the above-described manufacturing example 1. The red pixel 4R is a red colored pixel. The green pixel 4G is a green colored pixel. The blue pixel 4B is a blue colored pixel. The red pixel 4R, the green pixel 4G, and the blue pixel 4B can be formed by the method shown in manufacturing example 2. The overcoat layer 5 is a layer covering the black matrix 3, the red pixels 4R, the green pixels 4G, and the blue pixels 4B, and can be formed by the method shown in manufacturing example 2.

(item 18: peeling confirmation of Black matrix and colored Pixel)

Item 18 describes the confirmation of the peeling of the black matrix and the colored pixels. In the confirmation of the peeling of the black matrix and the colored pixels in item 18, the appearances (presence or absence of peeling) of the black matrix and the colored pixels of the color filter shown in item 17 above were confirmed at a magnification of 50 times using an optical microscope (optiphoto 300, manufactured by Nikon corporation). In addition, the following evaluation methods were used to determine whether the peeling was excellent, good, or bad.

Excellent (A): non-black matrix and stripping of colored pixels

Good (B): the black matrix and the colored pixels are partially peeled off (the ratio of the peeling to the whole of the black matrix and the colored pixels is less than 5%)

Good (C): the black matrix and the colored pixels are partially peeled off (the ratio of the peeling to the whole of the black matrix and the colored pixels: more than 5% and less than 15%)

Failure (D): there is a peeling in a part of the black matrix and the colored pixel (the ratio of the peeling to the whole of the black matrix and the colored pixel: 15% or more)

(example 1)

In example 1, 6FODA (12.60g (37.5mmol)), X-22-9409(4.48g (3.35mmol)), ODPA (12.79g (41.2mmol)), and NMP (100g) were charged into a200 mL four-necked flask under a dry nitrogen gas flow, and the mixture was heated and stirred at 80 ℃. After 5 hours, the mixture was cooled to prepare a varnish.

(example 2)

In example 2, 6FODA (15.29g (45.5mmol)), SiDA (0.15g (0.60mmol)), ODPA (14.43g (46.5mmol)), and NMP (100g) were charged into a200 mL four-necked flask under a dry nitrogen gas flow, and heated and stirred at 80 ℃. After 5 hours, the mixture was cooled to prepare a varnish.

(example 3)

In example 3, 6FODA (12.75g (37.9mmol)), X-22-1660B-3(1.78g (0.40mmol)), X-22-9409(2.70g (2.02mmol)), ODPA (12.64g (40.8mmol)), and NMP (100g) were charged in a200 mL four-necked flask under a dry nitrogen gas flow, and heated and stirred at 80 ℃. After 5 hours, the mixture was cooled to prepare a varnish.

(example 4)

In example 4, 6FODA (12.81g (38.1mmol)), X-22-1660B-3(2.30g (0.52mmol)), X-22-9409(2.16g (1.61mmol)), ODPA (12.61g (40.6mmol)), and NMP (100g) were charged in a200 mL four-necked flask under a dry nitrogen gas flow, and heated and stirred at 80 ℃. After 5 hours, the mixture was cooled to prepare a varnish.

(example 5)

In example 5, 6FODA (12.84g (38.2mmol)), X-22-1660B-3(3.50g (0.80mmol)), X-22-9409(1.07g (0.80mmol)), ODPA (12.46g (40.2mmol)), and NMP (100g) were charged into a200 mL four-necked flask under a dry nitrogen gas flow, and heated and stirred at 80 ℃. After 5 hours, the mixture was cooled to prepare a varnish.

(example 6)

In example 6, 6FODA (8.78g (26.1mmol)), BAFL (4.14g (11.9mmol)), X-22-1660B-3(3.48g (0.79mmol)), X-22-9409(1.06g (0.79mmol)), ODPA (12.40g (40.0mmol)), and NMP (100g) were charged in a200 mL four-necked flask under a dry nitrogen gas flow, and heated and stirred at 80 ℃. After 5 hours, the mixture was cooled to prepare a varnish.

(example 7)

In example 7, 6FODA (12.87g (38.3mmol)), X-22-1660B-3(2.25g (0.51mmol)), X-22-9409(0.68g (0.51mmol)), ODPA (8.62g (27.8mmol)), BPAF (5.46g (11.9mmol)), and NMP (100g) were charged in a200 mL four-necked flask under a dry nitrogen gas flow, and heated and stirred at 80 ℃. After 5 hours, the mixture was cooled to prepare a varnish.

(example 8)

In example 8, 6FODA (12.01g (35.8mmol)), X-22-1660B-3(3.45g (0.78mmol)), X-22-9409(1.05g (0.78mmol)), ODPA (8.18g (26.4mmol)), BPAF (5.18g (11.3mmol)), and NMP (100g) were charged in a200 mL four-necked flask under a dry nitrogen gas flow, and heated and stirred at 80 ℃. After 5 hours, the mixture was cooled to prepare a varnish.

(example 9)

In example 9, 6FODA (7.87g (23.4mmol)), 3,5-DABA (2.54g (16.7mmol)), X-22-1660B-3(3.48g (0.79mmol)), X-22-9409(1.06g (0.79mmol)), ODPA (9.14g (29.5mmol)), BPAF (5.79g (12.6mmol)), and NMP (100g) were charged in a200 mL four-necked flask under a dry nitrogen gas flow, and heated and stirred at 80 ℃. After 5 hours, the mixture was cooled to prepare a varnish.

(example 10)

In example 10, a200 mL four-necked flask was charged with 6FODA (10.06g (29.9mmol)), 3,5-DABA (1.20g (7.87mmol)), X-22-1660B-3(3.46g (0.79mmol)), X-22-9409(1.06g (0.79mmol)), ODPA (8.63g (27.8mmol)), BPAF (5.47g (11.9mmol)), and NMP (100g) under a dry nitrogen gas flow, and heated and stirred at 80 ℃. After 5 hours, the mixture was cooled to prepare a varnish.

(example 11)

In example 11, 6FODA (11.11g (33.0mmol)), 3,5-DABA (0.59g (3.84mmol)), X-22-1660B-3(3.38g (0.77mmol)), X-22-9409(1.03g (0.77mmol)), ODPA (8.43g (27.2mmol)), BPAF (5.34g (11.6mmol)), and NMP (100g) were charged in a200 mL four-necked flask under a dry nitrogen gas flow, and heated and stirred at 80 ℃. After 5 hours, the mixture was cooled to prepare a varnish.

(example 12)

In example 12, 6FODA (11.15g (33.2mmol)), X-22-1660B-3(4.66g (1.06mmol)), X-22-9409(1.42g (1.06mmol)), ODPA (7.74g (25.0mmol)), BPAF (4.90g (10.7mmol)), and NMP (100g) were charged in a200 mL four-necked flask under a dry nitrogen gas flow, and heated and stirred at 80 ℃. After 5 hours, the mixture was cooled to prepare a varnish.

(example 13)

In example 13, 6FODA (10.38g (30.9mmol)), X-22-1660B-3(5.75g (1.31mmol)), X-22-9409(1.75g (1.31mmol)), ODPA (7.34g (23.7mmol)), BPAF (4.65g (10.2mmol)), and NMP (100g) were charged in a200 mL four-necked flask under a dry nitrogen gas flow, and heated and stirred at 80 ℃. After 5 hours, the mixture was cooled to prepare a varnish.

(example 14)

In example 14, 6FODA (9.61g (28.6mmol)), X-22-1660B-3(6.83g (1.55mmol)), X-22-9409(2.08g (1.55mmol)), ODPA (6.95g (22.4mmol)), BPAF (4.40g (9.60mmol)), and NMP (100g) were charged in a200 mL four-necked flask under a dry nitrogen gas flow, and heated and stirred at 80 ℃. After 5 hours, the mixture was cooled to prepare a varnish.

(example 15)

In example 15, 6FODA (13.15g (39.1mmol)), X-22-9409(1.07g (0.80mmol)), ODPA (12.26g (39.5mmol)), X-22-168-P5-B (3.39g (0.81mmol)), and NMP (100g) were charged in a200 mL four-necked flask under a dry nitrogen gas flow, and heated and stirred at 80 ℃. After 5 hours, the mixture was cooled to prepare a varnish.

(example 16)

In example 16, a200 mL four-necked flask was charged with 6FODA (13.22g (39.3mmol)), ODPA (11.98g (38.6mmol)), X-22-168-P5-B (4.67g (1.11mmol)), and NMP (100g) under a dry nitrogen gas flow, and heated and stirred at 80 ℃. After 5 hours, the mixture was cooled to prepare a varnish.

(example 17)

In example 17, a200 mL four-necked flask was charged with 6FODA (12.95g (38.5mmol)), X-22-1660B-3(4.53g (1.03mmol)), ODPA (12.39g (40.0mmol)), and NMP (100g) under a dry nitrogen gas flow, and the mixture was heated and stirred at 80 ℃. After 5 hours, the mixture was cooled to prepare a varnish.

Comparative example 1

In comparative example 1, a200 mL four-necked flask was charged with TFMB (12.31g (38.4mmol)), X-22-9409(4.48g (3.34mmol)), ODPA (13.09g (42.2mmol)), and NMP (100g) under a dry nitrogen gas flow, and the mixture was heated and stirred at 80 ℃. After 5 hours, the mixture was cooled to prepare a varnish.

Comparative example 2

In comparative example 2, a200 mL four-necked flask was charged with 6FODA (15.46g (46.0mmol)), ODPA (14.41g (46.4mmol)), and NMP (100g) under a dry nitrogen gas flow, and heated and stirred at 80 ℃. After 5 hours, the mixture was cooled to prepare a varnish.

Comparative example 3

In comparative example 3, 6FODA (15.58g (46.3mmol)), X-22-9409(4.46g (3.33mmol)), CBDA (9.84g (50.2mmol)), and NMP (100g) were charged into a200 mL four-necked flask under a dry nitrogen gas flow, and the mixture was heated and stirred at 80 ℃. After 5 hours, the mixture was cooled to prepare a varnish.

Using the varnishes of examples 1 to 17 and comparative examples 1 to 3, the polyimide resin films, the laminates and the color filters including the same, and the measurements and evaluations related thereto were performed as described in the above items 1 to 18. The results of examples 1 to 17 and comparative examples 1 to 3 are shown in tables 1 to 4. The varnishes synthesized in examples 1 to 17 and comparative examples 1 to 3 were each filtered with a tetrafluoroethylene resin (PTFE) filter having a pore size of 1 μm and used. However, in comparative example 2, since the substrate warpage was large, it was not possible to form a SiON film on the polyimide resin film, and therefore, evaluation after the formation of the laminate was not possible.

As shown in tables 1 to 4, in examples 1 to 17 of the present invention, the evaluation as the object was not satisfactory at all. On the other hand, in comparative examples 1 to 3 to the present invention, at least one of the target evaluations was poor. Specifically, the evaluation of in-plane/out-of-plane birefringence in comparative example 1, the evaluation of substrate warpage and the evaluation of substrate adhesion force in comparative example 2, and the evaluation of elongation at break and the evaluation of appearance after laminate formation in comparative example 3 were poor results. In particular, it is considered that in comparative example 1, since TFMB having high linearity was used, polyimide was aligned, and the in-plane/out-of-plane birefringence of the obtained polyimide resin film was increased. It is considered that in comparative example 3, since CBDA, which is an alicyclic acid dianhydride, was used, oxidative decomposition proceeded to cause yellowing when curing was performed in an air atmosphere.

[ Table 1]

[ Table 2]

[ Table 3]

[ Table 4]

Industrial applicability

As described above, the polyimide precursor, the polyimide resin film, and the flexible device according to the present invention are suitable for efficiently providing a polyimide having high transparency, a high glass transition temperature, low in-plane/out-of-plane birefringence, and good adhesion to a supporting substrate, and a polyimide resin film and a flexible device using the polyimide.

Description of the reference numerals

1 polyimide resin film

2 gas barrier layer

3 black matrix

4R red pixel

4G green pixel

4B blue pixel

5 overlay coating

6 color filter

Claims

1. A polyimide precursor characterized by containing a structure represented by the general formula (1) and a structural unit represented by the general formula (2),

[ chemical formula 1]

In the general formula (1), R¹And R²Each independently represents a monovalent organic group having 1 to 20 carbon atoms, m represents an integer of 1 to 200 inclusive,

[ chemical formula 2]

In the general formula (2), R³Represents a divalent organic group represented by the general formula (3), R⁴Represents an aromatic tetracarboxylic acid residue, X¹And X²Each independently represents a hydrogen atom, a monovalent organic group having 1 to 10 carbon atoms, or a monovalent alkylsilyl group having 1 to 10 carbon atoms,

[ chemical formula 3]

2. The polyimide precursor according to claim 1, wherein the structure represented by the general formula (1) is contained in an amount of 0.1 to 30% by mass, based on 100% by mass of the entire polyimide precursor.

3. The polyimide precursor according to claim 1 or 2, wherein 30 mol% or more of the structural units of the divalent organic group represented by the general formula (3) are contained in all diamine residues contained in the polyimide precursor.

4. The polyimide precursor according to any one of claims 1 to 3, wherein 5 mol% or more and 55 mol% or less of all acid dianhydride residues contained in the polyimide precursor contain an acid anhydride residue having a fluorene skeleton.

5. The polyimide precursor according to any one of claims 1 to 4, comprising a residue of a compound represented by the following general formula (4),

[ chemical formula 4]

In the general formula (4), a plurality of R⁵Each independently a single bond or a divalent organic group having 1 to 10 carbon atoms, a plurality of R⁶And R⁷Each independently a monovalent aliphatic hydrocarbon group having 1 to 3 carbon atoms or an aromatic group having 6 to 10 carbon atoms, L is a group containing an amino group or a reactive derivative thereof or an acid dianhydride structure or a reactive derivative thereof, and y is an integer of 1 to 199 inclusive.

6. The polyimide precursor according to claim 5, comprising both a residue of the compound represented by the general formula (4) wherein y is 1 or more and 20 or less and a residue of the compound represented by the general formula (4) wherein y is 21 or more and 60 or less.

7. The polyimide precursor according to any one of claims 1 to 6, comprising a residue of a diamine represented by the following general formula (9),

[ chemical formula 5]

In the general formula (9), R⁸Is a substituted or unsubstituted phenyl group, and s represents an integer of 1 to 4 inclusive.

8. A polyimide obtained by imidizing the polyimide precursor according to any one of claims 1 to 7.

9. A polyimide characterized by containing a structure represented by the general formula (1) and a structural unit represented by the general formula (14),

[ chemical formula 6]

[ chemical formula 7]

In the general formula (14), R³Represented by the general formula (3)A divalent organic radical of (2), R⁴Represents an aromatic tetracarboxylic acid residue,

[ chemical formula 8]

10. The polyimide according to claim 9, wherein the structure represented by the general formula (1) is contained in an amount of 0.1 to 30% by mass, based on 100% by mass of the total polyimide.

11. The polyimide according to claim 9 or 10, wherein 30 mol% or more of the structural units of the divalent organic group represented by the general formula (3) are contained in all diamine residues contained in the polyimide.

12. A polyimide resin film comprising the polyimide according to any one of claims 8 to 11.

13. The polyimide resin film according to claim 12, wherein the density is 1.20g/cm³Above and 1.43g/cm³The following.

14. The polyimide resin film according to claim 12 or 13, wherein the in-plane/out-of-plane birefringence is 0.01 or less.

15. The polyimide resin film according to any one of claims 12 to 14, wherein a yellowness index is 3 or less.

16. A flexible device comprising the polyimide resin film according to any one of claims 12 to 15.