WO2020137870A1

WO2020137870A1 - Method for producing polyimide resin

Info

Publication number: WO2020137870A1
Application number: PCT/JP2019/050059
Authority: WO
Inventors: 絵美大久保; 奈津美西山; 皓史宮本
Original assignee: 住友化学株式会社
Priority date: 2018-12-26
Filing date: 2019-12-20
Publication date: 2020-07-02

Abstract

Provided is a method for producing a polyimide resin capable of forming a film which has a high flex resistance. A method for producing a polyimide resin, which comprises: process (I) for preparing an intermediate (K), said process including step (A) for reacting a diamine compound with a carboxylic acid compound having 3 or more carbonyl groups; and process (II) for further reacting the intermediate (K) with a diamine compound.

Description

Method for producing polyimide resin

The present invention relates to a method for producing a polyimide resin used as a material for a flexible display device or the like.

Display devices such as liquid crystal display devices and organic EL display devices are widely used in various applications such as mobile phones and smart watches. Although glass has been used as a front plate of such a display device, it is difficult to use it as a front plate material of a flexible display device because glass is very rigid and easily broken. There is a polyimide resin as one of the materials replacing the glass, and a film using the polyimide resin has been studied (Patent Document 1).

JP, 2017-203984, A

When applying such a film to a flexible display device, the film is required to have bending resistance that can withstand breakage even when repeatedly bent. However, according to the study by the present inventors, it has been found that a film formed of a polyimide resin may not have sufficient flex resistance.

Therefore, an object of the present invention is to provide a method for producing a polyimide resin capable of forming a film having excellent flex resistance.

MEANS TO SOLVE THE PROBLEM As a result of earnestly studying in order to solve the said subject, in the manufacturing process of a polyimide resin, when a diamine compound was divided and reacted twice or more, it found out that the said subject can be solved, and this invention is carried out. It came to completion. That is, the present invention includes the following preferred modes.

[1] A step (I) of obtaining an intermediate (K), which comprises a step (A) of reacting a diamine compound with a carboxylic acid compound having three or more carbonyl groups, and the intermediate (K) further comprises a diamine. Step (II) of reacting a compound
A method for producing a polyimide resin, comprising:
[2] The amount of the diamine compound reacted in the step (I) is 80 to 99.99 mol, when the total amount of the diamine compound reacted in the steps (I) and (II) is 100 mol. The manufacturing method according to [1].
[3] The production method according to [1] or [2], wherein the step (I) further includes a step (B) of reacting a dicarboxylic acid compound after the step (A).

According to the manufacturing method of the present invention, it is possible to obtain a polyimide resin capable of forming a film having excellent flex resistance.

[Method for producing polyimide resin]
The production method of the present invention comprises a step (I) of obtaining an intermediate (K) comprising a step (A) of reacting a diamine compound with a carboxylic acid compound having three or more carbonyl groups, and the intermediate (K). In addition, the step (II) of reacting a diamine compound is further included. The polyimide resin obtained by the production method of the present invention means a polyimide resin, a polyamideimide resin, a polyimide resin precursor, or a polyamideimide resin precursor. The polyimide resin precursor and the polyamide-imide resin precursor may be collectively referred to as a polyimide resin precursor. The polyimide resin is a polymer containing a repeating structural unit containing an imide group, for example, a repeating structural unit derived from a diamine compound and a repeating structural unit derived from a carboxylic acid compound having three or more carbonyl groups (for example, tetracarboxylic acid). And a repeating structural unit derived from an acid compound). The polyamide-imide resin is a polymer containing both a repeating structural unit containing an imide group and a repeating structural unit containing an amide group, and has, for example, a repeating structural unit derived from a diamine compound and three or more carbonyl groups. A resin containing a repeating structural unit derived from a carboxylic acid compound (for example, a repeating structural unit derived from a tricarboxylic acid compound), a repeating structural unit derived from a diamine compound, and a repeating structural unit derived from a carboxylic acid compound having three or more carbonyl groups. (For example, a repeating structural unit derived from a tetracarboxylic acid compound) and a repeating structural unit derived from a dicarboxylic acid compound. The polyimide resin precursor indicates a precursor before producing a polyimide resin by imidization, and the polyamideimide resin precursor indicates a precursor before producing a polyamideimide resin by imidization. In addition, in this specification, a "repeating structural unit" may be called a "structural unit." Further, the “original constitutional unit” may be simply referred to as a “unit”, and for example, the compound-derived constitutional unit may be referred to as a compound unit.

<Process (I)>
Step (I) is a step of obtaining an intermediate (K) including a step (A) of reacting a diamine compound with a carboxylic acid compound having three or more carbonyl groups.

(Step A)
Examples of the diamine compound used in Step A include aliphatic diamines such as acyclic or cycloaliphatic diamines, aromatic diamines, and mixtures thereof. In addition, in this embodiment, the “aromatic diamine” represents a diamine in which an amino group is directly bonded to an aromatic ring, and an aliphatic group or another substituent may be included in a part of its structure. The aromatic ring may be a single ring or a condensed ring, and examples thereof include a benzene ring, a naphthalene ring, an anthracene ring and a fluorene ring, but are not limited thereto. The "aliphatic diamine" represents a diamine in which an amino group is directly bonded to the aliphatic group, and may have an aromatic ring or other substituent in a part of its structure. The diamine compounds may be used alone or in combination of two or more.

In one embodiment of the present invention, the diamine compound has, for example, the formula (1)

It is preferable to include a compound represented by (may be referred to as a diamine compound (1)). When two or more kinds of diamine compounds are used, two or more kinds of diamine compounds having different kinds of X in the diamine compound (1) may be used.

In the formula (1), X represents a divalent organic group, preferably a divalent organic group having 4 to 40 carbon atoms, and more preferably a divalent organic group having 4 to 40 carbon atoms and having a cyclic structure. Represent Examples of the cyclic structure include an alicyclic structure, an aromatic ring structure, and a heterocyclic structure. The organic group, the hydrogen atom in the organic group may be substituted with a hydrocarbon group or a fluorine-substituted hydrocarbon group, in which case, the carbon number of the hydrocarbon group and the fluorine-substituted hydrocarbon group is preferably Is 1 to 8. X is represented by formula (10), formula (11), formula (12), formula (13), formula (14), formula (15), formula (16), formula (17) and formula (18). A group represented by the formulas (10) to (18) in which a hydrogen atom is substituted with a methyl group, a fluoro group, a chloro group or a trifluoromethyl group; and a group having 6 or less carbon atoms. A chain hydrocarbon group is exemplified.

In formulas (10) to (18), * represents a bond,
V ^1, ^{V 2} and ^{V 3} independently of one another, a single _{_{bond, -O -, - S -,}} - CH 2 -, - CH 2 -CH 2 -, - CH (CH 3) -, - C (CH ₃ ) ₂ −, —C(CF ₃ ) ₂ —, —SO ₂ —, —CO— or —N(Q)—. Here, Q represents a monovalent hydrocarbon group having 1 to 12 carbon atoms which may be substituted with a halogen atom.
One example is that V ¹ and V ³ are single bonds, —O— or —S—, and V ² is —CH ₂ —, —C(CH ₃ ) ₂ —, —C(CF ₃ ) ₂ -Or-SO ₂ -. The bonding position of each of V ¹ and V ² with respect to each ring and the bonding position of each of V ² and V ³ with respect to each ring are preferably a meta position or a para position with respect to each ring, and in the para position. More preferably.

Among the groups represented by the formulas (10) to (18), the formula (13) and the formula (14) are preferable from the viewpoint of easily improving the elastic modulus, flex resistance and surface hardness of the film containing the polyimide resin. ), Formula (15), Formula (16) and Formula (17) are preferable, and the group represented by Formula (14), Formula (15) and Formula (16) is more preferable. Further, V ¹ , V ² and V ³ are each independently a single bond, —O— from the viewpoint of easily improving the elastic modulus, flexibility, bending resistance and surface hardness of a film containing a polyimide resin. Alternatively, —S— is preferable, and a single bond or —O— is more preferable.

In a preferred embodiment of the present invention, X in formula (1) is represented by formula (2):

[In the formula (2), R ¹ to R ⁸ each independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or an aryl group having 6 to 12 carbon atoms, The hydrogen atoms contained in R ¹ to R ⁸ may be independently substituted with a halogen atom, and * represents a bond.]
Is a group represented by. When the compound in which X in the formula (1) is a group represented by the formula (2) is contained as the diamine compound, the optical film containing the polyimide resin has high elastic modulus, bending resistance and optical characteristics. Easy to develop.

In the formula (2), R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or a carbon number 1 It represents an alkoxy group having 6 to 6 or an aryl group having 6 to 12 carbon atoms.
Examples of the alkyl group having 1 to 6 carbon atoms include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, sec-butyl group, tert-butyl group, n-pentyl group and 2-methyl- group. Examples thereof include a butyl group, a 3-methylbutyl group, a 2-ethyl-propyl group, and an n-hexyl group.
Examples of the alkoxy group having 1 to 6 carbon atoms include methoxy group, ethoxy group, propyloxy group, isopropyloxy group, butoxy group, isobutoxy group, tert-butoxy group, pentyloxy group, hexyloxy group and cyclohexyloxy group. Can be mentioned.
Examples of the aryl group having 6 to 12 carbon atoms include phenyl group, tolyl group, xylyl group, naphthyl group and biphenyl group. R ¹ to R ⁸ independently of each other preferably represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, more preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, wherein R ¹ to R ⁸ The hydrogen atoms contained in R ⁸ may be independently substituted with a halogen atom. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom and an iodine atom. R ¹ to R ⁸ are, independently of each other, more preferably a hydrogen atom, a methyl group or a fluoro group from the viewpoint of easily improving the surface hardness, optical properties, elastic modulus and flex resistance of the film containing a polyimide resin. , A chloro group or a trifluoromethyl group, and even more preferably, R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ are hydrogen atoms, R ⁷ and R ⁸ are hydrogen atoms, a methyl group and a fluoro group. , Chloro group or trifluoromethyl group, particularly preferably R ⁷ and R ⁸ represent methyl group or trifluoromethyl group.

In a preferred embodiment of the present invention, the formula (2) is the formula (2'):

It is represented by. When the diamine compound contains a compound in which X in the formula (2) is a group represented by the formula (2′), the film containing the polyimide resin has a haze and a yellowness index (hereinafter, referred to as YI value). Sometimes)), and it is easy to improve optical characteristics. Further, the skeleton containing the elemental fluorine improves the solubility of the polyimide resin in the solvent, and the viscosity of the resin varnish can be easily suppressed to a low level.

Specifically, examples of the aliphatic diamine include acyclic aliphatic diamine such as hexamethylenediamine, 1,3-bis(aminomethyl)cyclohexane, 1,4-bis(aminomethyl)cyclohexane, norbornanediamine. And cycloaliphatic diamines such as 4,4′-diaminodicyclohexylmethane. These may be used alone or in combination of two or more.

Examples of aromatic diamines include p-phenylenediamine, m-phenylenediamine, 2,4-toluenediamine, m-xylylenediamine, p-xylylenediamine, 1,5-diaminonaphthalene, and 2,6-diaminonaphthalene. , An aromatic diamine having one aromatic ring, 4,4′-diaminodiphenylmethane, 4,4′-diaminodiphenylpropane, 4,4′-diaminodiphenyl ether, 3,4′-diaminodiphenyl ether, 3,3′- Diaminodiphenyl ether, 4,4'-diaminodiphenyl sulfone, 3,4'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfone, 1,4-bis(4-aminophenoxy)benzene, 1,3-bis(4 -Aminophenoxy)benzene, bis[4-(4-aminophenoxy)phenyl]sulfone, bis[4-(3-aminophenoxy)phenyl]sulfone, 2,2-bis[4-(4-aminophenoxy)phenyl] Propane, 2,2-bis[4-(3-aminophenoxy)phenyl]propane, 2,2'-dimethylbenzidine, 2,2'-bis(trifluoromethyl)-4,4'-diaminodiphenyl (TFMB and May be mentioned), 4,4'-bis(4-aminophenoxy)biphenyl, 9,9-bis(4-aminophenyl)fluorene, 9,9-bis(4-amino-3-methylphenyl)fluorene And aromatic diamines having two or more aromatic rings, such as 9,9-bis(4-amino-3-chlorophenyl)fluorene and 9,9-bis(4-amino-3-fluorophenyl)fluorene. These may be used alone or in combination of two or more.

The aromatic diamine is preferably 4,4′-diaminodiphenylmethane, 4,4′-diaminodiphenylpropane, 4,4′-diaminodiphenyl ether, 3,3′-diaminodiphenyl ether, 4,4′-diaminodiphenylsulfone, 3,3′-diaminodiphenyl sulfone, 1,4-bis(4-aminophenoxy)benzene, bis[4-(4-aminophenoxy)phenyl]sulfone, bis[4-(3-aminophenoxy)phenyl]sulfone, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 2,2-bis[4-(3-aminophenoxy)phenyl]propane, 2,2′-dimethylbenzidine, 2,2′-bis (Trifluoromethyl)-4,4′-diaminodiphenyl (TFMB) and 4,4′-bis(4-aminophenoxy)biphenyl, more preferably 4,4′-diaminodiphenylmethane and 4,4′-diamino Diphenylpropane, 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylsulfone, 1,4-bis(4-aminophenoxy)benzene, bis[4-(4-aminophenoxy)phenyl]sulfone, 2,2 -Bis[4-(4-aminophenoxy)phenyl]propane, 2,2'-dimethylbenzidine, 2,2'-bis(trifluoromethyl)-4,4'-diaminodiphenyl (TFMB), 4,4' -Bis(4-aminophenoxy)biphenyl. These may be used alone or in combination of two or more.

Among the above diamine compounds, from the viewpoint of high surface hardness, high transparency, high elastic modulus, high flexibility, high bending resistance and low colorability of a film containing a polyimide resin, an aromatic compound having a biphenyl structure It is preferable to use at least one selected from the group consisting of diamines. One selected from the group consisting of 2,2′-dimethylbenzidine, 2,2′-bis(trifluoromethyl)benzidine, 4,4′-bis(4-aminophenoxy)biphenyl and 4,4′-diaminodiphenyl ether It is more preferable to use the above, and it is more preferable to use 2,2′-bis(trifluoromethyl)-4,4′-diaminodiphenyl (TFMB).

Among the diamine compounds used in step A, a diamine compound in which X in formula (1) is a group represented by formula (2), for example, X in formula (1) is represented by formula (2′). The ratio of the diamine compound as a group is preferably 30 mol% or more, more preferably 50 mol% or more, further preferably 70 mol% or more, and particularly preferably, with respect to the total molar amount of the diamine compound used in Step A. It is 80 mol% or more, and preferably 100 mol% or less. When the proportion of the diamine compound in which X in the formula (1) is a group represented by the formula (2) is in the above range, the film containing the polyimide resin has a solvent of the resin due to the skeleton containing elemental fluorine. Solubility in the resin varnish, the viscosity of the resin varnish can be suppressed to a low level, the YI value and haze of the film can be reduced, and the optical characteristics can be easily improved. The ratio of the diamine compound in which X in the formula (1) is a group represented by the formula (2) may be calculated from the charging ratio of the raw materials.

The carboxylic acid compound having three or more carbonyl groups used in step A is preferably a tricarboxylic acid compound or a tetracarboxylic acid compound, and more preferably a tetracarboxylic acid compound.

The tetracarboxylic acid compound indicates a tetracarboxylic acid or a tetracarboxylic acid derivative. Examples of the tetracarboxylic acid derivative include tetracarboxylic acid anhydrides and acid chlorides, and preferably tetracarboxylic acid dianhydrides.
Examples of the tetracarboxylic acid compound include aromatic tetracarboxylic acid and its anhydride, preferably aromatic tetracarboxylic acid compound such as its dianhydride; aliphatic tetracarboxylic acid and its anhydride, preferably its dianhydride and the like. And the like. These tetracarboxylic acid compounds may be used alone or in combination of two or more.

In one embodiment of the present invention, the tetracarboxylic acid compound is preferably tetracarboxylic dianhydride. Examples of the tetracarboxylic dianhydride include compounds represented by the formula (3)

It is preferable that it is a compound represented by (hereinafter sometimes referred to as a tetracarboxylic acid compound (3)). The tetracarboxylic acid compounds can be used alone or in combination of two or more kinds. When two or more kinds of tetracarboxylic acid compounds are used, two or more kinds of tetracarboxylic acid compounds having different kinds of Y in the tetracarboxylic acid compound (3) are different from each other. You may use.

In formula (3), Y's each independently represent a tetravalent organic group, preferably a tetravalent organic group having 4 to 40 carbon atoms, and more preferably 4 to 40 carbon atoms having a cyclic structure. Represents a tetravalent organic group. Examples of the cyclic structure include an alicyclic structure, an aromatic ring structure, and a heterocyclic structure. The organic group is an organic group in which a hydrogen atom in the organic group may be substituted with a hydrocarbon group or a fluorine-substituted hydrocarbon group, in which case, a hydrocarbon group and a fluorine-substituted hydrocarbon group The carbon number is preferably 1-8. As Y, the following formula (20), formula (21), formula (22), formula (23), formula (24), formula (25), formula (26), formula (27), formula (28) And a group represented by the formula (29); a group in which a hydrogen atom in the group represented by the formula (20) to the formula (29) is substituted with a methyl group, a fluoro group, a chloro group or a trifluoromethyl group. And a chain hydrocarbon group having 4 or less carbon atoms and 6 or less.

In formulas (20) to (29),
* Represents a bond,
W ¹ represents a single _{_{_{bond, -O -, - CH 2 -}}} , - CH 2 -CH 2 -, - CH (CH 3) -, - C (CH 3) 2 -, - C (CF 3) 2 -, _{-Ar -, - SO 2 -,} - CO -, - O-Ar-O -, - Ar-O-Ar -, - Ar-CH 2 -Ar -, - Ar-C (CH 3) 2 -Ar- Alternatively, it represents —Ar—SO ₂ —Ar—. Ar represents an arylene group having 6 to 20 carbon atoms in which a hydrogen atom may be replaced by a fluorine atom, and a specific example thereof is a phenylene group.

Among the groups represented by the formulas (20) to (29), the formula (26), the formula (28) or the formula (29) is used from the viewpoint of easily improving the elastic modulus, flex resistance and surface hardness of the film. The group represented by the formula (26) is preferable, and the group represented by the formula (26) is more preferable. Further, W ^1, the elastic modulus of the film, tends to improve the flexing resistance and surface hardness, and from the viewpoint of easily improve optical properties, preferably a single bond, -O -, - CH 2 - , - CH 2 - It represents a group represented by CH ₂ —, —CH(CH ₃ )—, —C(CH ₃ ) ₂ — or —C(CF ₃ ) ₂ —, more preferably a single bond, —O—, —CH ₂ Represents a group represented by --, --CH(CH ₃ )--, --C(CH ₃ ) ₂ --, or --C(CF ₃ ) ₂ --, more preferably a single bond, --C(CH ₃ ) ₂ --, or It represents a group represented by —C(CF ₃ ) ₂ —.

In a preferred embodiment of the present invention, Y in formula (3) is represented by formula (4)

[In the formula (4), R ⁹ to R ¹⁶ each independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or an aryl group having 6 to 12 carbon atoms, The hydrogen atoms contained in R ⁹ to R ¹⁶ may be independently substituted with a halogen atom, and * represents a bond.
Is a group represented by. When a compound in which Y in the formula (3) is a group represented by the formula (4) is contained as a tetracarboxylic acid compound, the elastic modulus, the optical property, the flex resistance and the surface of the film containing the polyimide resin are included. Easy to improve hardness. Further, the solubility of the resin in the solvent is improved, the viscosity of the resin varnish can be suppressed to a low level, and the film production becomes easy.

In formula (4), preferably R ⁹ , R ¹⁰ , R ¹¹ , R ¹² , R ¹³ , R ¹⁴ , R ¹⁵ and R ¹⁶ are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms or a carbon atom. It represents an alkoxy group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms. Examples of the alkyl group having 1 to 6 carbon atoms, the alkoxy group having 1 to 6 carbon atoms or the aryl group having 6 to 12 carbon atoms include an alkyl group having 1 to 6 carbon atoms and an alkoxy group having 1 to 6 carbon atoms in the formula (2). Examples of the group or the aryl group having 6 to 12 carbon atoms include those exemplified above. R 9 ^~ R ¹⁶ are, independently of one another, preferably hydrogen atom or an alkyl group having 1 to 6 carbon atoms, more preferably represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, wherein, R ⁹ ~ The hydrogen atoms contained in R ¹⁶ may be independently substituted with a halogen atom. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom and an iodine atom. R ⁹ to R ¹⁶ are, independently of each other, more preferably a hydrogen atom, a methyl group or a fluoro group, from the viewpoint of easily improving the elastic modulus, optical properties, flex resistance and surface hardness of the film containing a polyimide resin. , A chloro group or a trifluoromethyl group, more preferably R ⁹ , R ¹⁰ , R ¹¹ , R ¹² , R ¹³ and R ¹⁴ are hydrogen atoms, R ¹⁵ and R ¹⁶ are hydrogen atoms, a methyl group and fluoro. Represents a group, a chloro group or a trifluoromethyl group, and particularly preferably R ¹⁵ and R ¹⁶ represent a methyl group or a trifluoromethyl group.

In a preferred embodiment of the present invention, the formula (4) is the formula (4′):

It is represented by. When a compound in which Y in the formula (4) is a group represented by the formula (4′) is contained as a tetracarboxylic acid compound, the film containing the polyimide resin has a modulus of elasticity, optical characteristics, and bending resistance. Also, it is easy to increase the surface hardness. Further, the skeleton containing the elemental fluorine improves the solubility of the resin in the solvent, the viscosity of the resin varnish can be suppressed low, and the film production becomes easy.

Specific examples of the aromatic tetracarboxylic dianhydride include a non-condensed polycyclic aromatic tetracarboxylic dianhydride, a monocyclic aromatic tetracarboxylic dianhydride and a condensed polycyclic aromatic tetraanhydride. Examples include carboxylic acid dianhydride. Examples of the non-condensed polycyclic aromatic tetracarboxylic acid dianhydride include 4,4′-oxydiphthalic acid dianhydride, 3,3′,4,4′-benzophenone tetracarboxylic acid dianhydride and 2,2 ',3,3'-Benzophenonetetracarboxylic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 2,2',3,3'-biphenyltetracarboxylic dianhydride ,3,3',4,4'-diphenylsulfone tetracarboxylic acid dianhydride, 2,2-bis(3,4-dicarboxyphenyl)propane dianhydride, 2,2-bis(2,3-di) Carboxyphenyl)propane dianhydride, 2,2-bis(3,4-dicarboxyphenoxyphenyl)propane dianhydride, 4,4′-(hexafluoroisopropylidene)diphthalic acid dianhydride (described as 6FDA , 1,2-bis(2,3-dicarboxyphenyl)ethane dianhydride, 1,1-bis(2,3-dicarboxyphenyl)ethane dianhydride, 1,2-bis(3,3) 4-dicarboxyphenyl)ethane dianhydride, 1,1-bis(3,4-dicarboxyphenyl)ethane dianhydride, bis(3,4-dicarboxyphenyl)methane dianhydride, bis(2,3 -Dicarboxyphenyl)methane dianhydride, 4,4'-(p-phenylenedioxy)diphthalic acid dianhydride and 4,4'-(m-phenylenedioxy)diphthalic acid dianhydride. In addition, examples of the monocyclic aromatic tetracarboxylic dianhydride include 1,2,4,5-benzenetetracarboxylic dianhydride, and condensed polycyclic aromatic tetracarboxylic dianhydrides. Examples thereof include 2,3,6,7-naphthalenetetracarboxylic dianhydride.

Among these, 4,4′-oxydiphthalic acid dianhydride, 3,3′,4,4′-benzophenone tetracarboxylic acid dianhydride and 2,2′,3,3′-benzophenone tetracarboxylic acid dianhydride are preferable. Anhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 2,2',3,3'-biphenyltetracarboxylic dianhydride, 3,3',4,4'-diphenyl Sulfone tetracarboxylic acid dianhydride, 2,2-bis(3,4-dicarboxyphenyl)propane dianhydride, 2,2-bis(2,3-dicarboxyphenyl)propane dianhydride, 2,2- Bis(3,4-dicarboxyphenoxyphenyl)propane dianhydride, 4,4'-(hexafluoroisopropylidene)diphthalic acid dianhydride (6FDA), 1,2-bis(2,3-dicarboxyphenyl) Ethane dianhydride, 1,1-bis(2,3-dicarboxyphenyl)ethane dianhydride, 1,2-bis(3,4-dicarboxyphenyl)ethane dianhydride, 1,1-bis(3 ,4-Dicarboxyphenyl)ethane dianhydride, bis(3,4-dicarboxyphenyl)methane dianhydride, bis(2,3-dicarboxyphenyl)methane dianhydride, 4,4'-(p- Examples thereof include phenylenedioxy)diphthalic acid dianhydride and 4,4′-(m-phenylenedioxy)diphthalic acid dianhydride, and more preferably 4,4′-oxydiphthalic acid dianhydride, 3,3′, 4,4'-biphenyltetracarboxylic dianhydride, 2,2',3,3'-biphenyltetracarboxylic dianhydride, 4,4'-(hexafluoroisopropylidene)diphthalic dianhydride (6FDA) , Bis(3,4-dicarboxyphenyl)methane dianhydride and 4,4′-(p-phenylenedioxy)diphthalic dianhydride. These may be used alone or in combination of two or more.

Examples of the aliphatic tetracarboxylic acid dianhydride include cyclic or acyclic aliphatic tetracarboxylic acid dianhydride. The cycloaliphatic tetracarboxylic dianhydride is a tetracarboxylic dianhydride having an alicyclic hydrocarbon structure, and specific examples thereof include 1,2,4,5-cyclohexanetetracarboxylic dianhydride. Compounds, cycloalkanetetracarboxylic dianhydrides such as 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,3,4-cyclopentanetetracarboxylic dianhydride, bicyclo[2.2 .2] Oct-7-ene-2,3,5,6-tetracarboxylic dianhydride, dicyclohexyl-3,3',4,4'-tetracarboxylic dianhydride and positional isomers thereof. To be These may be used alone or in combination of two or more. Specific examples of the acyclic aliphatic tetracarboxylic dianhydride include 1,2,3,4-butanetetracarboxylic dianhydride and 1,2,3,4-pentanetetracarboxylic dianhydride. These may be used alone or in combination of two or more. Moreover, you may use combining cycloaliphatic tetracarboxylic dianhydride and acyclic aliphatic tetracarboxylic dianhydride.

Among the above tetracarboxylic dianhydrides, 4,4′-oxydiphthalic dianhydride, from the viewpoint of high surface hardness, high transparency, high flexibility, high elastic modulus, high bending resistance and low colorability of the film, 3,3',4,4'-benzophenone tetracarboxylic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 2,2',3,3'-biphenyltetracarboxylic acid Dianhydride, 3,3′,4,4′-diphenylsulfone tetracarboxylic acid dianhydride, 2,2-bis(3,4-dicarboxyphenyl)propane dianhydride, 4,4′-(hexafluoro Isopropylidene)diphthalic acid dianhydride, and mixtures thereof are preferable, and 3,3′,4,4′-biphenyltetracarboxylic acid dianhydride and 4,4′-(hexafluoroisopropylidene)diphthalic acid dianhydride , And a mixture thereof are more preferable, and 4,4′-(hexafluoroisopropylidene)diphthalic acid dianhydride (6FDA) is further preferable.

Among the tetracarboxylic acid compounds used in step A, a tetracarboxylic acid compound in which Y in formula (3) is a group represented by formula (4), for example, Y in formula (3) is represented by formula (4′) The ratio of the tetracarboxylic acid compound which is a group represented by is preferably 30 mol% or more, more preferably 50 mol% or more, and further preferably, based on the total molar amount of the tetracarboxylic acid compound used in Step A. It is 70 mol% or more, particularly preferably 80 mol% or more, and preferably 100 mol% or less. When the ratio of the tetracarboxylic acid compound that is the group represented by Formula (4) in which Y in Formula (3) is in the above range, the film containing the polyimide-based resin has elastic modulus, optical characteristics, and bending resistance. It is easy to increase the hardness and surface hardness. Further, the skeleton containing the elemental fluorine improves the solubility of the resin in the solvent, the viscosity of the resin varnish can be suppressed low, and the film production becomes easy. The ratio of the tetracarboxylic acid compound in which Y in the formula (3) is a group represented by the formula (4) may be calculated from the raw material charging ratio.

The tetracarboxylic acid compound is preferably tetracarboxylic acid dianhydride, but tetracarboxylic acid monoanhydride may be used. The tetracarboxylic acid monoanhydride has the formula (5)

And the like (hereinafter, sometimes referred to as tetracarboxylic acid compound (5)). The tetracarboxylic acid compound (5) can be used alone or in combination of two or more kinds. When two or more kinds of the tetracarboxylic acid compound (5) are used, two kinds of the tetracarboxylic acid compound (5) in which Y ¹ is different from each other are used. You may use the above tetracarboxylic acid compound (5).

In the formula (5), Y ¹ is a tetravalent organic group, preferably an organic group in which a hydrogen atom in the organic group may be substituted with a hydrocarbon group or a fluorine-substituted hydrocarbon group. As Y ¹ , the formula (20), the formula (21), the formula (22), the formula (23), the formula (24), the formula (25), the formula (26), the formula (27), the formula (28), or A group represented by the formula (29), a group in which a hydrogen atom in the group represented by the formulas (20) to (29) is substituted with a methyl group, a fluoro group, a chloro group or a trifluoromethyl group, And a chain hydrocarbon group having 4 or less carbon atoms and 6 or less. R ¹⁷ and R ¹⁸ are each independently —OH, —OMe, —OEt, —OPr, —OBu or —Cl, and preferably —Cl.

The tricarboxylic acid compound indicates a tricarboxylic acid or a tricarboxylic acid derivative, and examples of the tricarboxylic acid derivative include acid chlorides, anhydrides and ester forms of tricarboxylic acid.

In one embodiment of the present invention, the tricarboxylic acid compound may be, for example, a compound of formula (8)

And the like (hereinafter, sometimes referred to as tricarboxylic acid compound (8)) and the like. The tricarboxylic acid compounds may be used alone or in combination of two or more, and when two or more tricarboxylic acid compounds are used, two or more tricarboxylic acid compounds (8) in which the Y ² types of the tricarboxylic acid compound (8) are different from each other are used. You may use. In the formula (8), R ³⁴ is —OH, —OMe, —OEt, —OPr, —OBu or —Cl, and preferably —Cl.

In formula (8), Y ² is a trivalent organic group, preferably an organic group in which a hydrogen atom in the organic group may be substituted with a hydrocarbon group or a fluorine-substituted hydrocarbon group. As Y ² , formula (20), formula (21), formula (22), formula (23), formula (24), formula (25), formula (26), formula (27), formula (28) or Examples thereof include a group in which any one of the bonds of the group represented by the formula (29) is replaced with a hydrogen atom, and a trivalent chain hydrocarbon group having 6 or less carbon atoms.

Examples of the tricarboxylic acid compound include aromatic tricarboxylic acids, aliphatic tricarboxylic acids and their derivatives (eg, acid chloride, acid anhydride, etc.), and specific examples thereof include 1,3,5-benzenetricarboxylic acid and The acid chloride, an anhydride of 1,2,4-benzenetricarboxylic acid; 2,3,6-naphthalenetricarboxylic acid-2,3-anhydride; a single bond of phthalic anhydride and benzoic acid, -O-, Examples of the compound include —CH ₂ —, —C(CH ₃ ) ₂ —, —C(CF ₃ ) ₂ —, —SO ₂ — or a phenylene group. These tricarboxylic acid compounds can be used alone or in combination of two or more kinds.

The amount of the carboxylic acid compound having three or more carbonyl groups to be reacted in step (A) can be appropriately selected according to the ratio of the constituent units in the desired polyimide resin, and in steps (I) and (II) When the total amount of diamine compounds to be reacted is 100 mol, preferably 1 mol or more, more preferably 5 mol or more, further preferably 10 mol or more, preferably 150 mol or less, more preferably 100 mol or less, It is preferably 80 mol or less, and particularly preferably 50 mol or less. When the amount of the carboxylic acid compound having three or more carbonyl groups used is within the above range, the imide skeleton is appropriately introduced, and the flex resistance of the film after film formation is likely to be improved.

The amount of the diamine compound to be reacted in the step (I) is preferably 80 mol or more, more preferably 85 mol or more, when the total amount of the diamine compounds reacted in the process (I) and the process (II) is 100 mol. , More preferably 90 mol or more, still more preferably 95 mol or more, particularly preferably 98 mol or more, and preferably 99.99 mol or less. When the amount of the diamine compound to be reacted in the step (I) is within the above range, the flex resistance of the film containing the polyimide resin can be more easily improved.

The reaction in step (I) is preferably carried out in a solvent inert to the reaction. The solvent is not particularly limited as long as it does not affect the reaction, and for example, water, methanol, ethanol, ethylene glycol, isopropyl alcohol, propylene glycol, ethylene glycol methyl ether, ethylene glycol butyl ether, 1-methoxy-2-propanol, Alcohol solvents such as 2-butoxyethanol and propylene glycol monomethyl ether; ester solvents such as ethyl acetate, butyl acetate, ethylene glycol methyl ether acetate, γ-butyrolactone, γ-valerolactone, propylene glycol methyl ether acetate and ethyl lactate; Ketone solvents such as acetone, methyl ethyl ketone, cyclopentanone, cyclohexanone, 2-heptanone, methyl isobutyl ketone; aliphatic hydrocarbon solvents such as pentane, hexane, heptane; alicyclic hydrocarbon solvents such as ethylcyclohexane; toluene, xylene Aromatic hydrocarbon solvent such as acetonitrile; Nitrile solvent such as acetonitrile; Ether solvent such as tetrahydrofuran and dimethoxyethane; Chlorine-containing solvent such as chloroform and chlorobenzene; Amide such as N,N-dimethylacetamide, N,N-dimethylformamide Examples thereof include system solvents; sulfur-containing solvents such as dimethyl sulfone, dimethyl sulfoxide, and sulfolane; carbonate solvents such as ethylene carbonate and propylene carbonate; and combinations thereof. Among these, the amide solvent can be preferably used from the viewpoint of solubility of the diamine compound and the tetracarboxylic acid compound.

The amount of the solvent used is preferably 0.5 to 30 parts by mass, more preferably 1 to 20 parts by mass, and further 1 part by mass of the total amount of the diamine compound and the carboxylic acid compound having three or more carbonyl groups. It is preferably 5 to 15 parts by mass. When the content of the solvent is at least the above lower limit, it is advantageous from the viewpoint of suppressing an increase in the viscosity of the reaction system, and when it is at most the above upper limit, it is advantageous from the viewpoint of the polymerization reaction.

When a solvent is used, one of the diamine compound and the carboxylic acid compound having three or more carbonyl groups may be added to the solution prepared by dissolving the solvent in the solvent, and the other may be reacted by stirring or the like. Alternatively, the diamine compound and the carboxylic acid compound having three or more carbonyl groups may be separately dissolved in a solvent to obtain a solution, and then the solutions may be mixed and stirred to react with each other. Alternatively, both may be reacted together by adding them together and stirring.

The reaction temperature of step (A) is not particularly limited, but may be, for example, −5 to 100° C., preferably 0 to 50° C., and more preferably 5 to 30° C. The reaction time may be, for example, 1 minute to 72 hours, preferably 10 minutes to 24 hours, more preferably 30 minutes to 10 hours. The reaction may be carried out in air or in an atmosphere of an inert gas such as nitrogen or argon with stirring, and may be carried out under normal pressure, under pressure or under reduced pressure. In a preferred embodiment, the treatment is carried out under normal pressure and/or the above-mentioned inert gas atmosphere while stirring.

When the step (I) is constituted by the step (A), the obtained intermediate (K) has a constitutional unit derived from a diamine compound and a constitutional unit derived from a carboxylic acid compound having three or more carbonyl groups. Have. In a preferred embodiment of the present invention, the intermediate (K) contains a repeating structural unit represented by the formula (A) obtained by reacting the diamine compound (1) and the tetracarboxylic acid compound (3).

[In the formula (A), G ¹ is the same as Y in the formula (3), and X ¹ is the same as X in the formula (1)].

When there are two or more kinds of the diamine compound (1) and/or the tetracarboxylic acid compound (3), the intermediate (K) has two or more kinds of repeating structural units represented by the formula (A). The intermediate (K) having a structural unit derived from a diamine compound and a structural unit derived from a tetracarboxylic acid compound may be referred to as an intermediate (K-1).

In one embodiment of the present invention, the step (I) may include a step (B) of reacting a dicarboxylic acid compound after the step (A).

(Step B)
The dicarboxylic acid compound used in step (B) represents a dicarboxylic acid or a dicarboxylic acid derivative, and examples of the dicarboxylic acid derivative include acid chlorides and ester forms of the dicarboxylic acid. In one embodiment of the present invention, examples of the dicarboxylic acid compound include compounds represented by the formula (6)

It is preferable that it is a compound represented by (hereinafter sometimes referred to as a dicarboxylic acid compound (6)). The dicarboxylic acid compounds may be used alone or in combination of two or more kinds. When two or more kinds of dicarboxylic acid compounds are used, two or more kinds of dicarboxylic acid compounds (6) having different W types of dicarboxylic acid compounds (6) are used. You can In formula (6), R ¹⁹ and R ²⁰ independently of each other are —OH, —OMe, —OEt, —OPr, —OBu or —Cl, and preferably —Cl.

In the formula (6), W is a divalent organic group, preferably carbon which may be substituted with a hydrocarbon group having 1 to 8 carbon atoms or a fluorine-substituted hydrocarbon group having 1 to 8 carbon atoms. It is a divalent organic group having 4 to 40 carbon atoms, more preferably a cyclic structure which may be substituted with a hydrocarbon group having 1 to 8 carbon atoms or a fluorine-substituted hydrocarbon group having 1 to 8 carbon atoms. It is a divalent organic group having 4 to 40 carbon atoms. Examples of the cyclic structure include an alicyclic structure, an aromatic ring structure, and a heterocyclic structure. As the organic group of W, formula (20), formula (21), formula (22), formula (23), formula (24), formula (25), formula (26), formula (27), formula (28) Further, among the bonds of the group represented by the formula (29), two groups which are not adjacent to each other are replaced by hydrogen atoms, and a divalent chain hydrocarbon group having 6 or less carbon atoms are exemplified. From the viewpoint of easily reducing the YI value of the film containing the polyimide resin, the groups represented by the formulas (20) to (27) are preferable.

Examples of the organic group of W include formula (20′), formula (21′), formula (22′), formula (23′), formula (24′), formula (25′), formula (26′), and formula (26′) (27'), Equation (28') and Equation (29'):

[In the formulas (20′) to (29′), W ¹ and * are as defined in the formulas (20) to (29)]
A divalent organic group represented by is more preferable. The hydrogen atom on the ring in the formulas (20) to (29) and the formulas (20′) to (29′) is a hydrocarbon group having 1 to 8 carbon atoms or 1 to 8 carbon atoms substituted with fluorine. May be substituted with a hydrocarbon group of, a C 1-6 alkoxy group, or a fluorine-substituted C 1-6 alkoxy group.

When the dicarboxylic acid compound contains a compound in which W in the formula (6) is represented by any one of the above formulas (20′) to (29′), W in the formula (6) is, When the compound represented by formula (6a) is included, the dicarboxylic acid compound may have the following formula (d1) in addition to the compound represented by formula (6a) in which W in formula (6):

[In the formula (d1), R ^c's each independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or an aryl group having 6 to 12 carbon atoms, and R ^d is , R ^c or —C(═O)R ^e , R ^e independently of each other represents —OH, —OMe, —OEt, —OPr, —OBu or —Cl, and * represents a bond.
It is preferable to further include the compound represented by (hereinafter, sometimes referred to as compound (d1)) from the viewpoint of easily improving the film forming property of the varnish and easily improving the uniformity of the film containing the polyimide resin.

In R ^c , the alkyl group having 1 to 6 carbon atoms, the alkoxy group having 1 to 6 carbon atoms, and the aryl group having 6 to 12 carbon atoms are, respectively, an alkyl group having 1 to 6 carbon atoms and a carbon atom in formula (2). Examples of the alkoxy group having 1 to 6 carbon atoms or the aryl group having 6 to 12 carbon atoms are given. As the compound (d1), specifically, a compound in which R ^c and R ^d are both hydrogen atoms, a compound in which both R ^c are hydrogen atoms and R ^d is —C(═O)R ^e Etc.

The dicarboxylic acid compound in the present invention may include a plurality of types of W as W in the formula (6), and the plurality of types of W may be the same as or different from each other. Among them, W in the formula (6) is preferably the formula (6a): from the viewpoint of easily increasing the surface hardness, water resistance, optical properties, elastic modulus, yield point strain and bending resistance of the optical film.

[In the formula (6a), R ^a and R ^b independently represent a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or an aryl group having 6 to 12 carbon atoms. , R ^a and R ^b may each independently be substituted with a halogen atom,
A and * are the same as A and * in the formula (7b), respectively,
m is an integer from 0 to 4,
t is an integer of 0 to 4,
u is an integer from 0 to 4]
And more preferably formula (7a);

[In the formula (7a), R ²¹ to R ²⁴ each independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or an aryl group having 6 to 12 carbon atoms,
The hydrogen atoms contained in R ²¹ to R ²⁴ may be independently substituted with a halogen atom,
m2 is an integer of 1 to 4,
* Represents a bond]
It is represented by. When the compound of formula (6) in which W in formula (6) is a group represented by formula (7a) is contained as the dicarboxylic acid compound, the film containing the polyimide resin has excellent elastic modulus, flex resistance and optical properties. Easy to develop. A compound in which W in the formula (6) is a group represented by the formula (7a) and a compound in which W in the formula (6) is a group represented by the formula (6a) are respectively dicarboxylic acid compounds ( 7a) and dicarboxylic acid compound (6a).

In the formula (6a), the bond of each benzene ring may be bonded to any of the ortho position, the meta position or the para position with respect to -A-, preferably the meta position or the para position. May be. R ^a and R ^b each independently represent a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or an aryl group having 6 to 12 carbon atoms. In the formula (6a), t and u are preferably 0, but when t and/or u is 1 or more, R ^a and R ^b are independently of each other, preferably an alkyl group having 1 to 6 carbon atoms. It represents a group, more preferably an alkyl group having 1 to 3 carbon atoms. In R ^a and R ^b in the formula (6a), a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms and an aryl group having 6 to 12 carbon atoms are respectively represented by the formula (2 Examples of the halogen atom, the alkyl group having 1 to 6 carbon atoms, the alkoxy group having 1 to 6 carbon atoms or the aryl group having 6 to 12 carbon atoms in ).

In formula (6a), t and u are each independently an integer of 0 to 4, preferably an integer of 0 to 2, more preferably 0 or 1, and even more preferably 0.

In the formula (6a), m is an integer in the range of 0 to 4, and when m is in this range, the flex resistance and elastic modulus of the film containing the polyimide resin are good. In the formula (6a), m is preferably an integer in the range of 0 to 3, more preferably an integer in the range of 0 to 2, still more preferably 0 or 1, and most preferably 0. When m is in this range, the flexural resistance and elastic modulus of the film containing the polyimide resin are good, and at the same time, the availability of the raw materials is relatively good. The compound represented by formula (6a) in which m is 0 is, for example, terephthalic acid or isophthalic acid or a derivative thereof, and the compound is a compound in which m in formula (6a) is 0 and u is 0. It is preferable to have. Further, the dicarboxylic acid compound may contain one or more compounds in which W in the formula (6) is represented by the formula (6a), and the elastic modulus and resistance of the film containing the polyimide resin are From the viewpoint of improving the flexibility and reducing the YI value, two or more kinds of compounds having different values of m, preferably two kinds of compounds having different values of m may be contained.

From the viewpoint of improving the elastic modulus and bending resistance of a film containing a polyimide resin and reducing the yellowness (YI value), a compound represented by the formula (6a) in which m in the formula (6a) is 0 is used. It is preferable to include, and it is more preferable to further include a compound represented by the formula (6a) in which m is 1, in addition to the compound.

In the formula (7a), R ²¹ , R ²² , R ²³ and R ²⁴ are independently of each other a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or an alkyl group having 6 to 12 carbon atoms. Represents an aryl group. Examples of the alkyl group having 1 to 6 carbon atoms, the alkoxy group having 1 to 6 carbon atoms or the aryl group having 6 to 12 carbon atoms include an alkyl group having 1 to 6 carbon atoms and an alkoxy group having 1 to 6 carbon atoms in the formula (2). Examples of the group or the aryl group having 6 to 12 carbon atoms include those exemplified above. From the viewpoint of easily improving the surface hardness, flexibility and bending resistance of a film containing a polyimide resin, R ²¹ to R ²⁴ are independently of each other, preferably a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. , More preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and further preferably a hydrogen atom. Here, the hydrogen atoms contained in R ²¹ to R ²⁴ may be independently substituted with a halogen atom.

In the formula (7a), m2 is preferably an integer of 1 to 3, more preferably 1 or 2, and even more preferably 1 from the viewpoint of easily increasing the bending resistance and elastic modulus of the film containing a polyimide resin. is there. When all of R ²¹ to R ²⁴ are hydrogen atoms, it is advantageous in terms of improving the elastic modulus and flex resistance of the film containing the polyimide resin.

In a preferred embodiment of the present invention, from the viewpoint that a film containing a polyimide resin is likely to exhibit good bending resistance, the dicarboxylic acid compound has two or more aromatic hydrocarbon rings each having a single bond or an aromatic ring. It includes an aromatic dicarboxylic acid compound linked by a divalent group excluding a group. Examples of the aromatic hydrocarbon ring include a monocyclic hydrocarbon ring such as a benzene ring; a condensed bicyclic hydrocarbon ring such as naphthalene; and a polycyclic hydrocarbon ring such as a ring-assembled hydrocarbon ring such as biphenyl. , Preferably a benzene ring.

Specifically, in the aromatic dicarboxylic acid compound in which two or more aromatic hydrocarbon rings are linked by a single bond or a divalent group excluding an aromatic group, in the formula (6), W is represented by the formula (7b )

[In the formula (7b), R ²⁵ to R ³² each independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or an aryl group having 6 to 12 carbon atoms, hydrogen atoms contained in R ²⁵ ~ ^{R 32,} independently of one another, may be substituted with a halogen atom, a is a single _{_{bond, -O -, - CH 2 -}} , - CH 2 -CH 2 -, - CH(CH ₃ )−, —C(CH ₃ ) ₂ —, —C(CF ₃ ) ₂ —, —SO ₂ —, —S—, —CO— or —N(R ³³ )—, and R ³³ Represents a hydrogen atom or a monovalent hydrocarbon group having 1 to 12 carbon atoms which may be substituted with a halogen atom, m ¹ is an integer of 1 to 4, and * represents a bond.]
The compound is a group represented by. When the compound of formula (6) in which W in formula (6) is a group represented by formula (7b) is contained as the dicarboxylic acid compound, the film containing the polyimide resin has excellent elastic modulus, flex resistance and optical properties. Easy to develop. The compound in which W in the formula (6) is a group represented by the formula (7b) may be referred to as a dicarboxylic acid compound (7b).

In the formula (7b) and the formula (6a), A is a single _{_{_{bond, -O -, - CH 2 -}}} , - CH 2 -CH 2 -, - CH (CH 3) -, - C (CH 3) 2 - , -C(CF ₃ ) ₂ -, -SO ₂ -, -S-, -CO- or -N(R ³³ )-, and improves the elastic modulus and flex resistance of a film containing a polyimide resin. From the viewpoint of facilitation, it preferably represents —O— or —S—, more preferably —O—. Examples of the alkyl group having 1 to 6 carbon atoms, the alkoxy group having 1 to 6 carbon atoms or the aryl group having 6 to 12 carbon atoms include an alkyl group having 1 to 6 carbon atoms and an alkoxy group having 1 to 6 carbon atoms in the formula (2). Examples of the group or the aryl group having 6 to 12 carbon atoms include those exemplified above. From the viewpoint of easily improving the surface hardness, flexibility and bending resistance of a film containing a polyimide resin, R ²⁵ to R ³² are each independently a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. , More preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and further preferably a hydrogen atom. Here, the hydrogen atoms contained in R ²⁵ to R ³² may be independently substituted with a halogen atom. R ³³ represents a hydrogen atom or a monovalent hydrocarbon group having 1 to 12 carbon atoms which may be substituted with a halogen atom. Examples of the monovalent hydrocarbon group having 1 to 12 carbon atoms include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, sec-butyl group, tert-butyl group, n-pentyl group, Examples include 2-methyl-butyl group, 3-methylbutyl group, 2-ethyl-propyl group, n-hexyl, n-heptyl group, n-octyl group, tert-octyl group, n-nonyl group and n-decyl group. And these may be substituted with a halogen atom. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom and an iodine atom. When m ¹ is 2 to 4, A may be the same or different.

In the formula (7b), m ¹ is an integer of 1 to 4, and when m ¹ is in this range, the flex resistance and elastic modulus of the film containing the polyimide resin are likely to be good. In the formula (7b), m ¹ is preferably an integer of 1 to 3, more preferably 1 or 2, and even more preferably 1. If m ¹ is within this range, the flex resistance of the film and The elastic modulus tends to be good.

From the viewpoint of improving the elastic modulus and bending resistance of a film containing a polyimide resin and reducing the YI value, it is possible to use a dicarboxylic acid compound (7a) or (7b) as the dicarboxylic acid compound in step (B). Preferably, the dicarboxylic acid compound (7a) and the dicarboxylic acid compound (7b) are used in combination.

In a more preferred embodiment of the present invention, the formula (7a) is the formula (7a'):

It is represented by. Further, the formula (7b) is the formula (7b′):

It is represented by. As the dicarboxylic acid compound, when W in the formula (6) is a compound represented by the formula (7a′) or a compound represented by the formula (7b′), or both of them are used, It is easy to obtain a film having a further improved elastic modulus and bending resistance.

Specific examples of the dicarboxylic acid compound include aromatic dicarboxylic acids, aliphatic dicarboxylic acids, and related acid chloride compounds, acid anhydrides, and the like, and two or more kinds may be used in combination. Specific examples thereof include terephthalic acid; isophthalic acid; naphthalenedicarboxylic acid; 4,4′-biphenyldicarboxylic acid; 3,3′-biphenyldicarboxylic acid; a chain hydrocarbon having 8 or less carbon atoms, and a dicarboxylic acid compound and 2 A compound in which two benzoic acids are linked by a single bond, —CH ₂ —, —C(CH ₃ ) ₂ —, —C(CF ₃ ) ₂ —, —SO ₂ — or a phenylene group, and their acid chloride compounds are Can be mentioned. Among these dicarboxylic acid compounds, 4,4′-oxybisbenzoic acid, terephthalic acid or acid chlorides thereof are preferable from the viewpoint of easily improving the elastic modulus and flex resistance of the film containing a polyimide resin, As described above, 4,4′-oxybis(benzoyl chloride) and terephthaloyl chloride are more preferable, and it is further preferable to use 4,4′-oxybis(benzoyl chloride) and terephthaloyl chloride in combination.

When the step (I) includes the step (B), the intermediate (K-1) obtained in the step (A) may be isolated and used in the step (B), but it is usually continuous without isolation. Then, step (B) is performed.

In a preferred embodiment of the present invention, the amount of the dicarboxylic acid compound to be reacted in step (B) can be appropriately selected according to the ratio with the constituent unit of the desired polyimide resin, and for example, the step (I) and When the total amount of the diamine compound reacted in (II) is 100 mol, preferably 5 mol or more, more preferably 20 mol or more, further preferably 30 mol or more, still more preferably 40 mol or more, and particularly preferably 50 mol. The amount is at least mol, particularly preferably at least 60 mol, preferably at most 95 mol, more preferably at most 90 mol, further preferably at most 85 mol, particularly preferably at most 80 mol. When the amount of the dicarboxylic acid compound used is in the above range, the elastic modulus and flex resistance of the film containing the polyimide resin can be easily improved.

In a preferred embodiment of the present invention, in the dicarboxylic acid compound used in the step (I) (step (B)), the ratio of the dicarboxylic acid compound (6a) is the total amount of the dicarboxylic acid compound used in the step (B). The molar amount is preferably 30 mol% or more, more preferably 50 mol% or more, further preferably 70 mol% or more, particularly preferably 80 mol% or more, and preferably 100 mol% or less. When the proportion of the dicarboxylic acid compound (6a) is within the above range, the film containing the polyimide resin tends to have higher elastic modulus, optical properties, bending resistance and surface hardness. Further, the skeleton containing the elemental fluorine improves the solubility of the resin in the solvent, the viscosity of the resin varnish can be suppressed low, and the film production becomes easy. The ratio of the dicarboxylic acid compound (6a) may be calculated from the charging ratio of raw materials.

In a preferred embodiment of the present invention, of the dicarboxylic acid compounds used in step (B), the total proportion of dicarboxylic acid compounds (7a) and (7b) is the total amount of dicarboxylic acid compounds used in step (B). The molar amount is preferably 30 mol% or more, more preferably 50 mol% or more, further preferably 70 mol% or more, particularly preferably 80 mol% or more, and preferably 100 mol% or less. When the total ratio of the dicarboxylic acid compounds (7a) and (7b) is in the above range, the film containing the polyimide resin tends to have higher elastic modulus, optical characteristics, flex resistance and surface hardness. Further, the skeleton containing the elemental fluorine improves the solubility of the resin in the solvent, the viscosity of the resin varnish can be suppressed low, and the film production becomes easy. The total ratio of the dicarboxylic acid compounds (7a) and (7b) may be calculated from the raw material charging ratio.

In a preferred embodiment of the present invention, it is preferable to use the dicarboxylic acid compounds (7a) and (7b) together as the dicarboxylic acid compound. The amount of the dicarboxylic acid compound (7b) used is preferably 0.01 mol or more, more preferably 0.05 mol or more, still more preferably 0.1 mol or more, relative to 1 mol of the dicarboxylic acid compound (7a). It is preferably 20 mol or less, more preferably 15 mol or less, still more preferably 10 mol or less, still more preferably 1 mol or less, particularly preferably 0.5 mol or less, and particularly preferably 0.3 mol or less. When the amount of the dicarboxylic acid compound (7b) used is in the above range, the film after film formation tends to have both flex resistance and elastic modulus.

In one embodiment of the present invention, a solvent may be further added in step (B). By adding the solvent in step (B), it is possible to suppress a rapid increase in the viscosity of the reaction system and maintain a uniformly stirrable state for a long time. Therefore, the polymerization reaction can proceed sufficiently, and the molecular weight of the polyimide resin and the flex resistance of the obtained film can be easily improved. Examples of the solvent to be added include those exemplified in the section of (Step (A)), and these solvents can be used alone or in combination of two or more kinds. An amide solvent can be preferably used from the viewpoint of good solubility and easy improvement of the molecular weight of the polyimide resin and the flex resistance of the resulting film. The solvent added in step (B) may be the same as or different from the solvent used in step (A), but it is the same from the viewpoint of improving the molecular weight and flex resistance of the resin. Is preferred. The solvent may be added at once, or may be dividedly added in plural times.

The amount of the solvent added in step (B) is preferably 1 part by mass or more, more preferably 5 parts by mass or more, and further preferably 10 parts by mass with respect to 1 part by mass of the dicarboxylic acid compound used in step (B). Parts or more, particularly preferably 20 parts by mass or more, preferably 300 parts by mass or less, more preferably 200 parts by mass or less, further preferably 100 parts by mass or less, particularly preferably 50 parts by mass or less. When the amount of the solvent added in step (B) is in the above range, it is easy to improve the molecular weight of the polyimide resin and the flex resistance of the obtained film.

In step (B), the dicarboxylic acid compound may be added all at once or in portions. When added in portions, it is easy to suppress a rapid increase in the viscosity of the reaction system, and it is easy to maintain a uniformly stirrable state for a long time. Therefore, the polymerization reaction easily proceeds, and the molecular weight of the obtained polyimide resin and the bending resistance of the obtained film are easily improved.

In step (B), the number of divisions when the dicarboxylic acid compound is dividedly added can be appropriately selected depending on the reaction scale, the type of raw material, etc., and is preferably 2 to 20 times, more preferably 2 to 10 times, and further preferably 2 times. ~6 times. When the number of divisions is within the above range, it is easy to improve the molecular weight of the polyimide resin and the flex resistance of the resulting film.

The dicarboxylic acid compound may be divided and added in an equal amount, or may be divided and added in an uneven amount. The time between each addition (hereinafter sometimes referred to as an addition interval) may be the same or different. When two or more dicarboxylic acid compounds are added, the term “divided addition” means that the total amount of all dicarboxylic acid compounds is divided and added, and the method of dividing each dicarboxylic acid compound is not particularly limited. However, each dicarboxylic acid compound may be added separately or collectively or in a divided manner, each dicarboxylic acid compound may be added in a divided manner together, or a combination thereof may be used.

In one embodiment of the present invention, when there are two kinds of dicarboxylic acid compounds (hereinafter referred to as a first dicarboxylic acid compound and a second dicarboxylic acid compound, respectively), for example, the first dicarboxylic acid compound is added all at once, and the second dicarboxylic acid compound is added. The dicarboxylic acid compound may be added all at once, the first dicarboxylic acid compound and the second dicarboxylic acid compound may be separately added separately, or the first dicarboxylic acid compound and the second dicarboxylic acid compound may be added together separately. It is also possible to add the remainder separately or separately after adding the remainder separately, or after adding separately separately and then adding the remainder together or one remainder. .. From the viewpoint of increasing the molecular weight of the polyimide-based resin and increasing the flex resistance of the resulting film, the first dicarboxylic acid compound and the second dicarboxylic acid compound are added in a divided manner together, or after the addition is made in a divided manner, the remaining one is It is preferable to add.

In the step (B), when a solvent is further added, the solvent may be added together with the dicarboxylic acid compound, may be added separately from the dicarboxylic acid, or when the dicarboxylic acid is dividedly added. May be a combination of these.

The reaction temperature of step (B) is not particularly limited, but may be, for example, -5 to 100°C, preferably 0 to 50°C, more preferably 5 to 30°C. The reaction time may be, for example, 1 minute to 72 hours, preferably 10 minutes to 24 hours, more preferably 30 minutes to 10 hours. The reaction may be carried out in air or in an inert gas atmosphere (for example, nitrogen, argon, etc.) with stirring, and may be carried out under normal pressure, under pressure or under reduced pressure. In a preferred embodiment, it is carried out under normal pressure and/or an inert gas atmosphere with stirring.

In step (B), the intermediate (K) is obtained by adding the dicarboxylic acid compound and then stirring and reacting for a predetermined time.

When the step (I) is composed of steps (A) and (B), the intermediate (K) is a structural unit derived from a diamine compound and a structural unit derived from a carboxylic acid compound having three or more carbonyl groups. And a structural unit derived from a dicarboxylic acid compound. In a preferred embodiment of the present invention, the intermediate (K) comprises a repeating structural unit represented by the formula (A) obtained by reacting a diamine compound (1) with a tetracarboxylic acid compound (3), and a diamine compound ( A) and a repeating structural unit represented by the formula (B) obtained by reacting the dicarboxylic acid compound (6).

[In the formulas (A) and (B), G ² is the same as W in the formula (6),
G ¹ is the same as Y in formula (3),
X ¹ and X ² are respectively the same as X in formula (1), and X ¹ and X ² may be the same or different]

When at least one selected from the diamine compound (1), the tetracarboxylic acid compound (3) and the dicarboxylic acid compound (5) is two or more, the intermediate (K) has a repeating structure represented by the formula (A). It has two or more kinds of units and/or repeating structural units represented by the formula (B). The intermediate (K) having a structural unit derived from a diamine compound, a structural unit derived from a tetracarboxylic acid compound, and a dicarboxylic acid compound may be referred to as an intermediate (K-2).

When a polyimide-based resin is produced, the intermediate (K) may be isolated and then subjected to the step (II) described below, but the viewpoint of the bending resistance of the film containing the polyimide-based resin and the production efficiency. From the viewpoint of, it is directly subjected to the step (II) without isolation.

<Step (II)>
Step (II) is a step of reacting the intermediate (K) with a diamine compound. The present invention is characterized by including the step (II), that is, performing the reaction (divided reaction) by dividing the diamine compound into two or more times. Surprisingly, the present inventors have found that when the step (II) is included in the process for producing a polyimide resin, the resulting film has improved flex resistance and a polyimide resin having excellent flex resistance is obtained. Found. In the present specification, the bending resistance refers to a property capable of suppressing or preventing the occurrence of breakage or the like even when bending is repeated. In a preferred embodiment of the present invention, the film formed from the polyimide resin of the present invention does not break even when repeatedly bent, for example, 150,000 times or more, preferably 200,000 times or more.

Examples of the diamine compound to be reacted in the step (II) include those exemplified above as the diamine compound to be reacted in the step (A). The diamine compounds may be used alone or in combination of two or more.

Among the diamine compounds reacted in the step (II), a diamine compound in which X in the formula (1) is a group represented by the formula (2), for example, X in the formula (1) is represented by the formula (2′). The ratio of the diamine compound which is a group is preferably 30 mol% or more, more preferably 50 mol% or more, further preferably 70 mol% or more with respect to the total molar amount of the diamine compound used in the step (II). It is particularly preferably 80 mol% or more, and preferably 100 mol% or less. When the proportion of the diamine compound in which X in the formula (1) is a group represented by the formula (2) is in the above range, the film containing the polyimide resin has a solvent of the resin due to the skeleton containing elemental fluorine. Solubility in the resin varnish, the viscosity of the resin varnish can be suppressed to a low level, the YI value and haze of the film can be reduced, and the optical characteristics can be easily improved. The ratio of the diamine compound in which X in the formula (1) is a group represented by the formula (2) may be calculated from the charging ratio of the raw materials.

In one embodiment of the present invention, at least the diamine compound to be reacted in the step (I) and the diamine compound to be reacted in the step (II) are at least from the viewpoint of further improving the bending resistance of the film containing the polyimide resin. It is preferable that one compound is the same. When the diamine compound to be reacted in the step (I) is the diamine compound (I) and the diamine compound to be reacted in the step (II) is the diamine compound (II), "at least one compound is the same" means the diamine compound ( When I) is one type and diamine compound (II) is one type, it means that these diamine compounds (I) and (II) are the same, and one diamine compound (I) is, and When the diamine compound (II) is two or more kinds, it means that at least one kind of the diamine compound (II) is the same as the diamine compound (I). Moreover, when two or more kinds of diamine compounds (I) and one kind of diamine compounds (II) are used, it means that one or more kinds of diamine compounds (I) are the same as the diamine compounds (II). However, when the diamine compound (I) is two or more kinds and the diamine compound (II) is two or more kinds, it means that one or more kinds are the same as each other. In a further preferred embodiment, all the diamine compounds reacted in the step (I) and the diamine compound reacted in the step (II) are from the viewpoint of easily improving the bending resistance of the film containing the polyimide resin. It is preferably the same.

In step (II), the diamine compound may be added all at once or may be added in portions. In the present specification, the divided addition means that the compound to be added is divided and added several times, more specifically, the compound to be added is divided into a specific amount and added at a predetermined interval or a predetermined time. Means Since the predetermined interval or predetermined time includes a very short interval or time, the divided addition also includes continuous addition or continuous feed.

When the diamine compound is dividedly added in the step (II), the number of divisions, the amount of division, and the method of divisional addition include the number of divisions of the dicarboxylic acid compound in step (B), the amount of division, and the method of divisional addition. Examples of the above are given.
In step (II), a solvent may be further added. When the solvent is further added, it may be added together with the diamine compound, may be added separately from the diamine compound, or may be a combination of these when the diamine compound is dividedly added.

Examples of the solvent to be added include those exemplified in the section of (Step (A)), and these solvents can be used alone or in combination of two or more kinds. When the solvent is added, it may be the same as or different from the solvent used in step (A), but from the viewpoint of improving the molecular weight of the polyimide resin and the flex resistance of the film, the step (A It is preferred that it is the same as the solvent used in (). The solvent may be added all at once, or may be added dividedly in multiple times.

The amount of the diamine compound to be reacted in the step (II) is preferably 0.01 or more, preferably 20 when the total amount of the diamine compound to be reacted in the steps (I) and (II) is 100 mol. The amount is not more than 15 mol, more preferably not more than 15 mol, further preferably not more than 10 mol, still more preferably not more than 5 mol, and particularly preferably not more than 2 mol. When the amount of the diamine compound to be reacted in the step (II) is within the above range, the flex resistance of the film containing the polyimide resin can be more easily improved.

The total amount of diamine compounds reacted in steps (I) and (II) is preferably 10.0 to 1,000 moles, more preferably 50, when the carboxylic acid compound reacted in step (I) is 100 moles. 0.0 to 150 mol, more preferably 80.0 to 120 mol, even more preferably 90.0 to 110 mol, particularly preferably 95.0 to 100, particularly preferably 97.0 to 99.9, and especially It is preferably 98.0 to 99.9. When the total amount of the diamine compound to be reacted in steps (I) and (II) is in the above range, the flex resistance of the film containing the polyimide resin can be more easily improved. The carboxylic acid compound means a carboxylic acid compound including the dicarboxylic acid compound, the tetracarboxylic acid compound, and the tricarboxylic acid compound used in steps (I) and (II).

The reaction temperature in step (II) is not particularly limited, but may be, for example, -5 to 100°C, preferably 0 to 50°C, more preferably 5 to 30°C. The reaction time may be, for example, 1 minute to 72 hours, preferably 10 minutes to 24 hours, more preferably 30 minutes to 10 hours. The reaction may be carried out in air or in an atmosphere of an inert gas such as nitrogen or argon with stirring, and may be carried out under normal pressure, under pressure or under reduced pressure. In a preferred embodiment, the treatment is carried out under normal pressure and/or the above-mentioned inert gas atmosphere while stirring.

By the step (II), a polyimide resin precursor or a polyamide-imide resin precursor is obtained. More specifically, the polyimide resin precursor is obtained by reacting the intermediate (K-1) obtained in step (A) in step (I) with a diamine compound in step (II). Therefore, the polyimide resin precursor contains a structural unit derived from a diamine compound and a structural unit derived from a tetracarboxylic acid compound, and in a preferred embodiment, a repeating structural unit represented by the formula (A). The polyamideimide precursor is obtained by reacting the intermediate (K-2) obtained in step (B) in step (I) with a diamine compound in step (II). Therefore, the polyamide-imide resin contains a constitutional unit derived from a diamine compound, a constitutional unit derived from a tetracarboxylic acid compound, and a constitutional unit derived from a dicarboxylic acid compound, and in a preferred embodiment, a repeating structural unit represented by the formula (A): And a repeating structural unit represented by the formula (B). Note that the polyimide resin precursor or the polyamide-imide precursor can be prepared by adding a large amount of water, methanol, or the like to a reaction solution containing the resin precursor to precipitate the resin precursor, and filtering, concentrating, drying, or the like. Can be separated.

When producing a polyimide resin or a polyamide-imide resin, after isolating the polyimide resin precursor or the polyamide-imide resin precursor, it may be subjected to the step (III) described below, but from the viewpoint of production efficiency, without isolation It is preferable to directly provide the step (III).

<Step (III)>
Step (III) is a step of imidizing the polyimide resin precursor in the presence of an imidization catalyst. For example, by subjecting a polyimide resin precursor containing a repeating structural unit represented by the formula (A) to step (III), the repeating structural unit portion represented by the formula (A) is imidized (ring closed), A polyimide resin containing a repeating structural unit represented by the formula (C) can be obtained. Further, for example, by providing a polyamideimide precursor containing a repeating structural unit represented by the formula (A) and a repeating structural unit represented by the formula (B) to the step (III), the constitution of the polyamideimide precursor Of the units, the repeating structural unit part represented by the formula (A) is imidized (closed) to form a repeating structural unit represented by the formula (C) and a repeating structural unit represented by the formula (B). It is possible to obtain a polyamide-imide resin containing the same.

[In the formulas (B) and (C), G ¹ is the same as Y in the formula (3),
G ² is the same as W in formula (6),
X ¹ and X ² are respectively the same as X in formula (1), and X ¹ and X ² may be the same or different]

Examples of the imidization catalyst include aliphatic amines such as tripropylamine, diisopropylethylamine, dibutylpropylamine and ethyldibutylamine; N-ethylpiperidine, N-propylpiperidine, N-butylpyrrolidine, N-butylpiperidine, and N- Alicyclic amine (monocyclic) such as propylhexahydroazepine; azabicyclo[2.2.1]heptane, azabicyclo[3.2.1]octane, azabicyclo[2.2.2]octane, and azabicyclo[3 2.2.2] Alicyclic amine (polycyclic) such as nonane; and pyridine, 2-methylpyridine (2-picoline), 3-methylpyridine (3-picoline), 4-methylpyridine (4-picoline) , 2-ethylpyridine, 3-ethylpyridine, 4-ethylpyridine, 2,4-dimethylpyridine, 2,4,6-trimethylpyridine, 3,4-cyclopentenopyridine, 5,6,7,8-tetrahydro Isoquinoline, and aromatic amines such as isoquinoline. These imidization catalysts can be used alone or in combination of two or more.

The imidization catalyst is used in an amount of preferably 0.1 to 10 mol, more preferably 1 to 5 mol, per 1 mol of the carboxylic acid compound having three or more carbonyl groups used in step (A). is there.

In the step (III), it is preferable to use an acid anhydride together with the imidization catalyst from the viewpoint of facilitating the imidization reaction. Examples of the acid anhydride include conventional acid anhydrides used in imidization reaction, and specific examples thereof include aliphatic acid anhydrides such as acetic anhydride, propionic anhydride, butyric anhydride, and aromatics such as phthalic acid. Examples thereof include acid anhydrides.

When an acid anhydride is used, the amount of the acid anhydride used is preferably 0.5 to 25 mol, more preferably 1 to 20 mol, relative to 1 mol of the carboxylic acid compound having three or more carbonyl groups. More preferably, it is 1 to 15 mol.

The reaction temperature in step (III) is not particularly limited, but may be, for example, −5 to 100° C., preferably 0 to 90° C., and more preferably 5 to 80° C. The reaction time may be, for example, 1 minute to 72 hours, preferably 10 minutes to 24 hours, more preferably 30 minutes to 10 hours. The reaction may be carried out in air or in an atmosphere of an inert gas such as nitrogen or argon with stirring, and may be carried out under normal pressure, under pressure or under reduced pressure. In a preferred embodiment, it is carried out under normal pressure and/or the aforementioned inert gas atmosphere while stirring.

The polyimide resin obtained in the step (III) can be separated and purified by a conventional method, for example, separation means such as filtration, concentration, extraction, crystallization, recrystallization, column chromatography or a combination of these separation means. May be isolated, in a preferred embodiment, a reaction solution containing a polyimide resin, a large amount of water, methanol or the like is added to precipitate the polyimide resin, and the polyimide resin can be isolated by performing concentration, filtration, drying or the like. it can.

[Polyimide resin]
According to the production method of the present invention, a polyimide resin capable of forming a film having excellent flex resistance can be obtained. Therefore, the film containing the polyimide resin in the present invention can be suitably used as a front plate material for a display device such as a liquid crystal display device or an organic EL display device, and particularly for a flexible display device.

The weight average molecular weight (Mw) of the polyimide resin is, in terms of standard polystyrene, preferably 150,000 or more, more preferably 200,000 or more, further preferably 250,000 or more, and particularly preferably 300,000 or more, It is preferably 1,000,000 or less, more preferably 800,000 or less, further preferably 700,000 or less, and particularly preferably 500,000 or less. When the weight average molecular weight is not less than the above lower limit, the elastic modulus of the film containing a polyimide resin, the bending resistance and the surface hardness are easily improved, and when it is not more than the above upper limit, the gel of the resin varnish is obtained. It is easy to suppress film formation and improve the optical characteristics of the film. The weight average molecular weight can be determined, for example, by gel permeation chromatography (GPC) measurement, and can be determined by standard polystyrene conversion. For example, it can be determined by the method described in Examples.

The viscosity of the polyimide resin at 25° C. when dissolved in N,N-dimethylacetamide at a concentration of 10% by mass is preferably 1,000 mPa·s or more, more preferably 5,000 mPa·s or more, and further preferably 10 mPa·s or more. 2,000 mPa·s or more, particularly preferably 20,000 mPa·s or more, preferably 70,000 mPa·s or less, more preferably 60,000 mPa·s or less, further preferably 50,000 mPa·s or less, particularly preferably It is 40,000 mPa·s or less. When the viscosity of the polyimide-based resin is the above lower limit or more, the interaction between molecules becomes large, and it is easy to improve the bending resistance and mechanical strength, and when it is the above upper limit or less, the film forming property becomes good. , Easy to form a uniform film. The viscosity can be measured by a Brookfield viscometer, for example, by the method described in Examples.

Among the polyimide-based resins obtained by the production method of the present invention, the polyimide resin preferably has at least a structural unit derived from a diamine compound and a structural unit derived from a tetracarboxylic acid compound, and in a preferred embodiment, has the formula (C) Including a repeating structural unit represented by. The polyamide-imide resin preferably has at least a structural unit derived from a diamine compound, a structural unit derived from a tetracarboxylic acid compound, and a structural unit derived from a dicarboxylic acid compound, and in a preferred embodiment, is represented by the formula (C). And a repeating structural unit represented by the formula (B). The polyimide resin may be composed of a constitutional unit derived from a diamine compound and a constitutional unit derived from a tricarboxylic acid compound, and in the preferred embodiment, may further include a constitutional unit derived from a tricarboxylic acid compound. A polyimide resin containing a structural unit derived from a tetracarboxylic acid compound and a structural unit derived from a tricarboxylic acid compound, for example, a tricarboxylic acid compound may be added together with or separately from the tetracarboxylic acid compound in step (A). It may be produced by adding a tricarboxylic acid compound in (B) together with or separately from the dicarboxylic acid compound.

In one embodiment of the present invention, the polyimide resin having at least a constitutional unit derived from a diamine compound (1) and a constitutional unit derived from a tetracarboxylic acid compound (3) contains a repeating constitutional unit represented by the formula (C). Further, at least one structural unit selected from the group consisting of a structural unit derived from the diamine compound (1), a structural unit derived from the tetracarboxylic acid compound (3) and a structural unit derived from the tricarboxylic acid compound (8), and a dicarboxylic acid. The polyamideimide resin having at least the structural unit derived from the acid compound (6) is represented by the repeating structural unit represented by the formula (B), the repeating structural unit represented by the formula (C) and the formula (D). And at least one structural unit selected from the group consisting of repeating structural units.

[In formula (D), G ³ is the same as Y ² in formula (8), and X ³ is the same as X in formula (1)]

In one embodiment of the present invention, at least one selected from the group consisting of a constitutional unit derived from a diamine compound (1), a constitutional unit derived from a tetracarboxylic acid compound (3) and a constitutional unit derived from a tetracarboxylic acid compound (5). The polyamide-imide resin having at least a structural unit of a species and a structural unit derived from the dicarboxylic acid compound (6) has a repeating structural unit represented by the formula (B), a repeating structural unit represented by the formula (C), and And at least one structural unit selected from the group consisting of repeating structural units represented by formula (E).

Wherein (E), ^{G 4} is the same as ^{Y 1} in the formula (5), ^{X 4} is the same as X in the formula ^{(1), R 18} is ^{R 18} in the formula (5) Is the same as]

[the film]
The polyimide resin in the present invention can be formed into a film, preferably an optical film. In the present invention, since the step (II) is particularly included, a film having excellent bending resistance can be obtained. The film is not particularly limited, for example, the following steps:
(A) a step of preparing a liquid containing the polyimide resin (sometimes referred to as a resin varnish) (varnish preparation step),
(B) a step of applying a resin varnish to a support material to form a coating film (application step), and (c) a step of drying the applied liquid (coating film) to form a film (film forming step)
Can be manufactured by a method including.

In the varnish preparation step, the polyimide resin is dissolved in a solvent, and if necessary, additives are added and mixed by stirring to prepare. Examples of the additives include fillers, ultraviolet absorbers, bluing agents, antioxidants, release agents, stabilizers, flame retardants, pH adjusters, dispersants, lubricants, thickeners, and leveling agents. .. The solvent used for preparing the resin varnish is not particularly limited as long as it can dissolve the polyimide resin. Examples of such a solvent include the solvents exemplified in the section (step (A)). Among these solvents, an amide solvent or a lactone solvent can be preferably used. These solvents can be used alone or in combination of two or more.

The solid content concentration of the resin varnish is preferably 1 to 25% by mass, more preferably 5 to 20% by mass. The solid content indicates a component obtained by removing the solvent from the resin varnish, and the solid content concentration indicates the mass of the solid content with respect to the mass of the resin varnish.

In the coating process, a resin varnish is applied on the support material to form a coating film. Examples of the coating method include a wire bar coating method, a reverse coating method, a roll coating method such as gravure coating, a die coating method, a comma coating method, a lip coating method, a spin coating method, a screen coating method, a fountain coating method, a dipping method, and a spray method. , A spout molding method and the like.

In the film forming process, the film can be formed by drying the coating film and peeling it from the support material. You may perform the drying process which dries a film further after peeling. The coating film can be dried usually at a temperature of 50 to 350°C. If necessary, the coating film may be dried under an inert atmosphere or a reduced pressure condition.

Examples of the support material include a metal belt such as SUS, and a resin film such as a PET film, a PEN film, another polyimide film, a polyamide film, and a polyamideimide film. Among them, a PET film, a PEN film, and the like are preferable from the viewpoint of excellent heat resistance, and a PET film is more preferable from the viewpoints of adhesion with the film during film formation, easy peeling property, and cost.

The thickness of the film can be appropriately selected according to the application, and is preferably 25 μm or more, more preferably 30 μm or more, preferably 100 μm or less, more preferably 80 μm or less, still more preferably 60 μm or less. The thickness of the film can be measured using, for example, a micrometer.

In a preferred embodiment of the present invention, the film containing the polyimide resin in the present invention is an optical film. The optical film has excellent optical characteristics in addition to bending resistance. In the present specification, the optical property refers to a property that can be optically evaluated, including total light transmittance, YI, and haze, for example.

The total light transmittance of the optical film having a thickness of 50 μm is preferably 80% or more, more preferably 85% or more, further preferably 88% or more, and particularly preferably 90% or more. When the total light transmittance is equal to or more than the above lower limit, the transparency becomes good, and when it is used for a front plate of a display device, it can contribute to high visibility. The upper limit of the total light transmittance is usually 100% or less. The total light transmittance can be measured by using a haze computer in accordance with JIS K 7361-1:1997, for example.

The haze of the optical film is preferably 3.0% or less, more preferably 2.0% or less, further preferably 1.0% or less, particularly preferably 0.5% or less, and usually 0.01% or more. is there. When the haze of the optical film is less than or equal to the above upper limit, the transparency becomes good, and when used for a front plate of a display device, for example, it can contribute to high visibility. The haze can be measured using a haze computer according to JIS K 7136:2000.

The YI value of the optical film is preferably 8 or less, more preferably 5 or less, further preferably 3 or less, particularly preferably 2 or less, and usually -5 or more, preferably -2 or more. When the YI value of the optical film is less than or equal to the above upper limit, the transparency is good, and when it is used for a front plate of a display device, it can contribute to high visibility. The YI value was measured in accordance with JIS K 7373:2006 using a UV-visible near-infrared spectrophotometer to measure the transmittance for light of 300 to 800 nm, and the tristimulus values (X, Y, Z) were calculated. It can be calculated and calculated based on the formula of YI=100×(1.2769X−1.0592Z)/Y.

The use of the film is not particularly limited and may be used for various purposes. As described above, the film may be a single layer or a laminate, and the film may be used as it is, or may be used as a laminate with another film. In addition, when a film is a laminated body, all layers laminated on one side or both sides of the film are referred to as a film.

When the film is a laminate, it is preferable to have one or more functional layers on at least one surface of the film. Examples of the functional layer include an ultraviolet absorbing layer, a hard coat layer, a primer layer, a gas barrier layer, an adhesive layer, a hue adjusting layer and a refractive index adjusting layer. The functional layers may be used alone or in combination of two or more.

The ultraviolet absorbing layer is a layer having a function of absorbing ultraviolet rays, and for example, a main material selected from a transparent resin of an ultraviolet curable type, a transparent resin of an electron beam curable type, and a transparent resin of a thermosetting type, and the main material It is composed of dispersed ultraviolet absorbers.

The adhesive layer is a layer having an adhesive function and has a function of adhering the film to other members. A commonly known material can be used as the material for forming the adhesive layer. For example, a thermosetting resin composition or a photocurable resin composition can be used. In this case, the thermosetting resin composition or the photocurable resin composition can be polymerized and cured by supplying energy afterwards.

The adhesive layer may be a layer called pressure sensitive adhesive (Pressure Sensitive Adhesive, PSA) that is attached to an object by pressing. The pressure-sensitive adhesive may be an adhesive that is "a substance that has adhesiveness at room temperature and that adheres to an adherend with a light pressure" (JIS K 6800), or "a protective film (microcapsule) for specific components. ), and a capsule type adhesive which is an adhesive (JIS K6800) capable of maintaining stability until the coating is broken by an appropriate means (pressure, heat, etc.).

The hue adjustment layer is a layer that has a hue adjustment function, and is a layer that can adjust the film to a desired hue. The hue adjustment layer is, for example, a layer containing a resin and a colorant. Examples of the colorant include titanium oxide, zinc oxide, rouge, titanium oxide-based calcined pigment, ultramarine blue, cobalt aluminate, and inorganic pigments such as carbon black; azo-based compounds, quinacridone-based compounds, anthraquinone-based compounds, Organic pigments such as perylene compounds, isoindolinone compounds, phthalocyanine compounds, quinophthalone compounds, slene compounds, and diketopyrrolopyrrole compounds; extender pigments such as barium sulfate and calcium carbonate; and basic dyes, Examples include acid dyes and mordant dyes.

The refractive index adjusting layer is a layer having a refractive index adjusting function, and has a refractive index different from that of, for example, a single-layer film, and is a layer capable of imparting a predetermined refractive index to the film. The refractive index adjusting layer may be, for example, a resin layer containing an appropriately selected resin and optionally a pigment, or a metal thin film. Examples of the pigment for adjusting the refractive index include silicon oxide, aluminum oxide, antimony oxide, tin oxide, titanium oxide, zirconium oxide and tantalum oxide. The average primary particle diameter of the pigment may be 0.1 μm or less. By setting the average primary particle diameter of the pigment to 0.1 μm or less, diffuse reflection of light passing through the refractive index adjusting layer can be prevented, and a decrease in transparency can be prevented. Examples of the metal used for the refractive index adjusting layer include metals such as titanium oxide, tantalum oxide, zirconium oxide, zinc oxide, tin oxide, silicon oxide, indium oxide, titanium oxynitride, titanium nitride, silicon oxynitride, and silicon nitride. An oxide or a metal nitride is mentioned.

The film may further include a protective layer (also referred to as a protective film). The protective layer may be laminated on one side or both sides of the film. When the functional layer is provided on one side of the film, the protective layer may be laminated on the surface on the film side or the surface on the functional layer side, or may be laminated on both the film side and the functional layer side. When the film has functional layers on both sides, the protective layer may be laminated on one of the functional layer-side surfaces or on both functional layer-side surfaces. The protective layer is a layer for temporarily protecting the surface of the film or the functional layer, and is not particularly limited as long as it is a peelable layer capable of protecting the surface of the film or the functional layer. Examples of the protective layer include polyester resin films such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; polyolefin resin films such as polyethylene and polypropylene films; acrylic resin films; polyolefin resin films, polyethylene terephthalate. It is preferably selected from the group consisting of an acrylic resin film and an acrylic resin film. When the film has two protective layers, each protective layer may be the same or different.

The thickness of the protective layer is not particularly limited, but is usually 10 to 100 μm, preferably 10 to 80 μm, and more preferably 10 to 50 μm. When the optical film has two protective layers, the thickness of each protective layer may be the same or different.

The film containing the polyimide resin obtained by the present invention has excellent bending resistance and optical characteristics, and is therefore suitable as a front plate of a display device, particularly a flexible display device (hereinafter, may be referred to as a window film). Can be used for The front plate has a function of protecting the display element of the flexible display device. Examples of the display device include TVs, smartphones, mobile phones, car navigations, tablet PCs, portable game machines, electronic papers, indicators, bulletin boards, watches, and wearable devices such as smart watches. Examples of the flexible display include display devices having flexible characteristics, such as televisions, smartphones, mobile phones, and smart watches.

[Flexible display device]
The flexible display device includes a flexible display device laminate and an organic EL display panel. The flexible display device laminate is arranged on the viewing side of the organic EL display panel and is configured to be bendable. The laminate for a flexible display device may contain the window film, the polarizing plate, and the touch sensor, and the lamination order thereof is arbitrary, but from the viewing side, the window film, the polarizing plate, the touch sensor or the window film, It is preferable that the touch sensor and the polarizing plate are laminated in this order. The presence of the polarizing plate on the viewing side of the touch sensor is preferable because the pattern of the touch sensor is less visible and the visibility of the display image is improved. Each member can be laminated using an adhesive, a pressure-sensitive adhesive or the like. Further, a light-shielding pattern formed on at least one surface of any one of the window film, the polarizing plate, and the touch sensor may be provided.

[Window film]
The window film is arranged on the viewing side of the flexible display device and plays a role of protecting the other constituent elements from external impacts or environmental changes such as temperature and humidity. Conventionally, glass has been used as such a protective layer, but the window film in the flexible display device is not rigid and rigid like glass, but has flexible characteristics. The window film may include a hard coat layer on at least one surface.

(Hard coat)
A hard coat layer may be provided on at least one surface of the window film. The thickness of the hard coat layer is not particularly limited and may be, for example, 2 to 100 μm. When the thickness of the hard coat layer is within the above range, sufficient scratch resistance can be ensured, bending resistance is unlikely to decrease, and a problem of curling due to curing shrinkage tends not to occur. ..
The hard coat layer can be formed by curing a hard coat composition containing a reactive material capable of forming a crosslinked structure by irradiation with active energy rays or application of heat energy, and irradiation with active energy rays is preferable. Active energy rays are defined as energy rays capable of decomposing compounds that generate active species to generate active species, such as visible light, ultraviolet rays, infrared rays, X-rays, α rays, β rays, γ rays and electron rays. And the like, and preferably ultraviolet rays. The hard coat composition contains at least one polymer of a radically polymerizable compound and a cationically polymerizable compound.

The radical polymerizable compound is a compound having a radical polymerizable group. The radical polymerizable group contained in the radical polymerizable compound may be any functional group capable of causing a radical polymerization reaction, and examples thereof include a group containing a carbon-carbon unsaturated double bond, and specifically, a vinyl group. And (meth)acryloyl group. When the radical-polymerizable compound has two or more radical-polymerizable groups, these radical-polymerizable groups may be the same or different. The number of radically polymerizable groups contained in one molecule of the radically polymerizable compound is preferably 2 or more from the viewpoint of improving the hardness of the hard coat layer. From the viewpoint of high reactivity, the radically polymerizable compound is preferably a compound having a (meth)acryloyl group. Specifically, 2 to 6 (meth)acryloyl groups are included in one molecule. A compound called a polyfunctional acrylate monomer, an epoxy (meth)acrylate, a urethane (meth)acrylate, or a polyester (meth)acrylate, which has several (meth)acryloyl groups in the molecule, has a molecular weight of from several hundred. Thousands of oligomers may be mentioned, preferably one or more selected from epoxy (meth)acrylate, urethane (meth)acrylate and polyester (meth)acrylate.

The cationically polymerizable compound is a compound having a cationically polymerizable group such as an epoxy group, an oxetanyl group and a vinyl ether group. The number of cationically polymerizable groups contained in one molecule of the cationically polymerizable compound is preferably 2 or more, and more preferably 3 or more, from the viewpoint of improving the hardness of the hard coat layer.
In addition, as the cationically polymerizable compound, among others, a compound having at least one of an epoxy group and an oxetanyl group as a cationically polymerizable group is preferable. A cyclic ether group such as an epoxy group or an oxetanyl group is preferable from the viewpoint that the shrinkage accompanying the polymerization reaction is small. In addition, compounds having an epoxy group among cyclic ether groups are easily available as compounds having various structures, do not adversely affect the durability of the obtained hard coat layer, and easily control the compatibility with the radically polymerizable compound. There is an advantage that. In addition, the oxetanyl group of the cyclic ether group tends to have a higher degree of polymerization than the epoxy group, accelerates the network formation rate obtained from the cationically polymerizable compound of the obtained hard coat layer, and is mixed with the radically polymerizable compound. Even in the area to be filled, there is an advantage that an independent network is formed without leaving unreacted monomer in the film.
As the cationically polymerizable compound having an epoxy group, for example, a polyglycidyl ether of a polyhydric alcohol having an alicyclic ring or a cyclohexene ring, a cyclopentene ring-containing compound, hydrogen peroxide, with a suitable oxidizing agent such as peracid Alicyclic epoxy resin obtained by epoxidation; polyglycidyl ether of aliphatic polyhydric alcohol or alkylene oxide adduct thereof, polyglycidyl ester of aliphatic long-chain polybasic acid, homopolymer of glycidyl (meth)acrylate, Aliphatic epoxy resins such as copolymers; glycidyl ethers produced by the reaction of bisphenol A, bisphenol F, bisphenols such as hydrogenated bisphenol A, or derivatives thereof such as alkylene oxide adducts and caprolactone adducts with epichlorohydrin, And glycidyl ether type epoxy resins derived from bisphenols, such as novolac epoxy resins.

The hard coat composition may further include a polymerization initiator. Examples of the polymerization initiator include radical polymerization initiators, cationic polymerization initiators, radical and cationic polymerization initiators, etc., which are appropriately selected and used. These polymerization initiators are decomposed by at least one of irradiation with active energy rays and heating to generate radicals or cations to promote radical polymerization and cation polymerization.
The radical polymerization initiator may be any one that can release a substance that initiates radical polymerization by at least one of irradiation with active energy rays and heating. Examples of thermal radical polymerization initiators include hydrogen peroxide, organic peroxides such as perbenzoic acid, and azo compounds such as azobisbutyronitrile.
As the active energy ray radical polymerization initiator, a Type 1 type radical polymerization initiator that produces a radical by decomposition of a molecule and a Type 2 type radical polymerization initiator that produces a radical by a hydrogen abstraction type reaction coexisting with a tertiary amine Yes, they are used alone or in combination.
Any cationic polymerization initiator may be used as long as it can release a substance that initiates cationic polymerization by irradiation with active energy rays and/or heating. As the cationic polymerization initiator, an aromatic iodonium salt, an aromatic sulfonium salt, a cyclopentadienyl iron(II) complex or the like can be used. These can initiate cationic polymerization either by irradiation with active energy rays or by heating, or both, depending on the difference in structure.

The polymerization initiator may preferably be contained in an amount of 0.1 to 10% by mass based on 100% by mass of the entire hard coat composition. When the content of the polymerization initiator is in the above range, curing can be sufficiently advanced, and the mechanical properties and adhesion of the finally obtained coating film can be set in a good range, and Poor adhesion due to curing shrinkage, cracking and curling tend to occur less easily.

The hard coat composition may further include one or more selected from the group consisting of a solvent and an additive.
The solvent is a solvent that can dissolve or disperse the polymerizable compound and the polymerization initiator, if the solvent is known as a solvent of the hard coat composition of the present technical field, does not impair the effects of the present invention Can be used in a range.
The additive may further include inorganic particles, a leveling agent, a stabilizer, a surfactant, an antistatic agent, a lubricant, an antifouling agent, and the like.

[Polarizer]
The flexible display device including the optical film of the present invention may further include a polarizing plate, preferably a circularly polarizing plate. The polarizing plate is a functional layer having a function of transmitting only the right circularly polarized light component or the left circularly polarized light component by laminating a λ/4 retardation plate on a linear polarizing plate. For example, by converting the external light into right circularly polarized light and blocking the external light reflected by the organic EL panel to become left circularly polarized light, and transmitting only the luminescent component of the organic EL, the influence of reflected light is suppressed and the image is displayed. It is used to make it easier to see. In order to achieve the circular polarization function, the absorption axis of the linear polarizing plate and the slow axis of the λ/4 retardation plate are theoretically required to be 45°, but they are practically 45±10°. The linearly polarizing plate and the λ/4 retardation plate are not necessarily required to be laminated adjacent to each other as long as the relationship between the absorption axis and the slow axis satisfies the above range. It is preferable to achieve perfect circularly polarized light at all wavelengths, but this is not necessary in practice, so the circularly polarizing plate in the present invention also includes an elliptically polarizing plate. It is also preferable to further laminate a λ/4 retardation film on the visible side of the linearly polarizing plate to make the emitted light circularly polarized light to improve the visibility in the state of wearing polarized sunglasses.

The linearly polarizing plate is a functional layer having a function of transmitting light oscillating in the transmission axis direction but blocking polarized light of an oscillating component perpendicular thereto. The linear polarizing plate may be configured to include a linear polarizer alone or a linear polarizer and a protective film attached to at least one surface thereof. The thickness of the linear polarizing plate may be 200 μm or less, preferably 0.5 to 100 μm. When the thickness is in the above range, the flexibility tends to be difficult to decrease.
The linear polarizer may be a film-type polarizer manufactured by dyeing and stretching a polyvinyl alcohol (PVA) film. A dichroic dye such as iodine is adsorbed on a PVA-based film oriented by stretching or is stretched in a state of being adsorbed on PVA, whereby the dichroic dye is oriented and exhibits polarization performance. The production of the film-type polarizer may further include steps such as swelling, crosslinking with boric acid, washing with an aqueous solution, and drying. The stretching and dyeing steps may be performed on the PVA film alone, or may be performed in a state of being laminated with another film such as polyethylene terephthalate. The thickness of the PVA-based film used is preferably 10 to 100 μm, and the stretching ratio is preferably 2 to 10 times.
Further, as another example of the polarizer, a liquid crystal coating type polarizer formed by coating a liquid crystal polarizing composition may be used. The liquid crystal polarizing composition may include a liquid crystal compound and a dichroic dye compound. The liquid crystalline compound is only required to have a property of exhibiting a liquid crystal state, and it is preferable to have a higher order alignment state such as a smectic phase because high polarization performance can be exhibited. It is also preferable that the liquid crystal compound has a polymerizable functional group.

The dichroic dye is a dye that is aligned with the liquid crystal compound and exhibits dichroism, and the dichroic dye itself may have liquid crystallinity or has a polymerizable functional group. You can also Any of the compounds in the liquid crystal polarizing composition has a polymerizable functional group.
The liquid crystal polarizing composition may further include an initiator, a solvent, a dispersant, a leveling agent, a stabilizer, a surfactant, a cross-linking agent, a silane coupling agent and the like.
The liquid crystal polarizing layer is manufactured by applying a liquid crystal polarizing composition on the alignment film to form a liquid crystal polarizing layer.
The liquid crystal polarizing layer can be formed thinner than a film type polarizer. The thickness of the liquid crystal polarizing layer may be preferably 0.5 to 10 μm, more preferably 1 to 5 μm.
The alignment film can be produced, for example, by applying the composition for forming an alignment film on a substrate and imparting the alignment property by rubbing, irradiation of polarized light, or the like. The composition for forming an alignment film may contain a solvent, a cross-linking agent, an initiator, a dispersant, a leveling agent, a silane coupling agent and the like in addition to the alignment agent. As the alignment agent, for example, polyvinyl alcohols, polyacrylates, polyamic acids, and polyimides can be used. When photo-alignment is applied, it is preferable to use an aligning agent containing a cinnamate group. The weight average molecular weight of the polymer used as the aligning agent may be about 10,000 to 1,000,000. The thickness of the alignment film is preferably 5 to 10,000 nm, more preferably 10 to 500 nm, from the viewpoint of the alignment regulating force. The liquid crystal polarizing layer can be peeled from the base material and transferred to be laminated, or the base material can be laminated as it is. It is also preferable that the base material plays a role as a protective film, a retardation plate, or a window film.

The protective film may be a transparent polymer film, and specifically, the polymer film used has a monomer unit containing polyethylene, polypropylene, polymethylpentene, norbornene or cycloolefin. Polyolefins such as cycloolefin derivatives, (modified)celluloses such as diacetylcellulose, triacetylcellulose, propionylcellulose, acrylics such as methylmethacrylate (co)polymers, polystyrenes such as styrene (co)polymers, acrylonitrile -Butadiene-styrene copolymers, acrylonitrile-styrene copolymers, ethylene-vinyl acetate copolymers, polyvinyl chlorides, polyvinylidene chlorides, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polycarbonate, poly Films such as polyesters such as arylate, polyamides such as nylon, polyimides, polyamideimides, polyetherimides, polyethersulfones, polysulfones, polyvinyl alcohols, polyvinyl acetals, polyurethanes, epoxy resins, etc. Of these, polyamide, polyamideimide, polyimide, polyester, olefin, acrylic, or cellulose-based films are preferable in terms of excellent transparency and heat resistance. These polymers can be used alone or in admixture of two or more. These films are used as unstretched films or as uniaxially or biaxially stretched films. Cellulose type films, olefin type films, acrylic films and polyester type films are preferable. It may be a coating type protective film obtained by applying and curing a cationically curable composition such as an epoxy resin or a radical curable composition such as an acrylate. If necessary, plasticizers, ultraviolet absorbers, infrared absorbers, colorants such as pigments and dyes, optical brighteners, dispersants, heat stabilizers, light stabilizers, antistatic agents, antioxidants, lubricants, solvents, etc. May be included. The protective film may have a thickness of 200 μm or less, preferably 1 to 100 μm. When the thickness of the protective film is within the above range, the flexibility of the protective film does not easily deteriorate.

The λ/4 retardation plate is a film that gives a λ/4 retardation in a direction orthogonal to the traveling direction of incident light (in-plane direction of the film). The λ/4 retardation plate may be a stretchable retardation plate produced by stretching a polymer film such as a cellulose-based film, an olefin-based film, or a polycarbonate-based film. If necessary, retarder, plasticizer, ultraviolet absorber, infrared absorber, colorant such as pigment or dye, fluorescent brightening agent, dispersant, heat stabilizer, light stabilizer, antistatic agent, antioxidant. , A lubricant, a solvent, etc. may be contained. The thickness of the stretchable retardation plate may be 200 μm or less, preferably 1 to 100 μm. When the thickness is in the above range, the flexibility of the film tends to be less likely to decrease.
Further, another example of the λ/4 retardation plate may be a liquid crystal coating type retardation plate formed by applying a liquid crystal composition. The liquid crystal composition contains a liquid crystal compound having a property of exhibiting a liquid crystal state such as nematic, cholesteric, or smectic. Any compound in the liquid crystal composition, including the liquid crystal compound, has a polymerizable functional group. The liquid crystal coated retardation plate may further contain an initiator, a solvent, a dispersant, a leveling agent, a stabilizer, a surfactant, a cross-linking agent, a silane coupling agent and the like. The liquid crystal coating type retardation plate can be manufactured by coating and curing the liquid crystal composition on the alignment film to form the liquid crystal retardation layer as in the case of the liquid crystal polarizing layer. The liquid crystal coating type retardation plate can be formed thinner than the stretched type retardation plate. The thickness of the liquid crystal polarizing layer may be usually 0.5 to 10 μm, preferably 1 to 5 μm. The liquid crystal coating type retardation plate can be peeled from the base material and transferred to be laminated, or the base material can be laminated as it is. It is also preferable that the base material plays a role as a protective film, a retardation plate, or a window film.

In general, many materials exhibit large birefringence at shorter wavelengths and smaller birefringence at longer wavelengths. In this case, since a phase difference of λ/4 cannot be achieved in the entire visible light region, an in-plane phase difference of 100 to 180 nm, preferably 130, which is λ/4 near 560 nm where the visibility is high. Often designed to be ~150 nm. It is preferable to use an inverse dispersion λ/4 retardation plate using a material having a birefringence wavelength dispersion characteristic opposite to the usual one because the visibility can be improved. As such a material, it is also preferable to use the materials described in JP-A-2007-232873 in the case of a stretched retardation plate and the JP-A-2010-30979 in the case of a liquid crystal coated retardation plate. ..
As another method, there is also known a technique for obtaining a broadband λ/4 retardation plate by combining it with a λ/2 retardation plate (Japanese Patent Laid-Open No. 10-90521). The λ/2 retardation plate is also manufactured by the same material method as that of the λ/4 retardation plate. The combination of the stretched retardation plate and the liquid crystal coating type retardation plate is arbitrary, but it is preferable to use the liquid crystal coating type retardation plate for both because the thickness can be reduced.
There is also known a method of laminating a positive C plate on the circularly polarizing plate in order to enhance visibility in an oblique direction (Japanese Patent Laid-Open No. 2014-224837). The positive C plate may be a liquid crystal coating type retardation plate or a stretching type retardation plate. The retardation in the thickness direction is -200 to -20 nm, preferably -140 to -40 nm.

[Touch sensor]
The touch sensor is used as an input means. As the touch sensor, various types such as a resistance film type, a surface acoustic wave type, an infrared type, an electromagnetic induction type, and a capacitance type have been proposed, and any type may be used. Of these, the capacitance method is preferable. The capacitive touch sensor is divided into an active region and a non-active region located outside the active region. The active region is a region corresponding to a region where the screen is displayed on the display panel (display unit), and is a region where the user's touch is sensed, and the inactive region is a region where the screen is not displayed on the display device (non-display region). It is an area corresponding to the display part). The touch sensor includes a substrate having flexible characteristics; a sensing pattern formed in an active region of the substrate; formed in an inactive region of the substrate and connected to an external driving circuit through the sensing pattern and a pad unit. Each sensing line can be included. As the substrate having flexible characteristics, the same material as the polymer film can be used. The toughness of the substrate of the touch sensor is preferably 2,000 MPa% or more from the viewpoint of suppressing cracks in the touch sensor. More preferably, the toughness may be 2,000 to 30,000 MPa%. Here, the toughness is defined as the area under the curve to the breaking point in a stress (MPa)-strain (%) curve (Stress-strain curve) obtained through a tensile test of a polymer material.

The sensing pattern may include a first pattern formed in the first direction and a second pattern formed in the second direction. The first pattern and the second pattern are arranged in different directions. The first pattern and the second pattern are formed on the same layer, and the respective patterns must be electrically connected in order to detect a touched point. The first pattern has a structure in which the unit patterns are connected to each other through a joint, but the second pattern has a structure in which the unit patterns are separated from each other in an island shape. A separate bridge electrode is required to make the connection. A known transparent electrode material can be applied to the sensing pattern. For example, indium tin oxide (ITO), indium zinc oxide (IZO), zinc oxide (ZnO), indium zinc tin oxide (IZTO), indium gallium zinc oxide (IGZO), cadmium tin oxide (CTO). , PEDOT (poly(3,4-ethylenedioxythiophene)), carbon nanotube (CNT), graphene, metal wire, and the like, and these may be used alone or in combination of two or more. Preferably ITO can be used. The metal used for the metal wire is not particularly limited, and examples thereof include silver, gold, aluminum, copper, iron, nickel, titanium, selenium, and chromium. These may be used alone or in combination of two or more.

The bridge electrode may be formed on the sensing layer via an insulating layer, and the bridge electrode may be formed on the substrate, and the insulating layer and the sensing pattern may be formed on the bridge electrode. The bridge electrode may be formed of the same material as the sensing pattern, and may be formed of a metal such as molybdenum, silver, aluminum, copper, palladium, gold, platinum, zinc, tin, titanium, or an alloy of two or more of these. You can also do it. Since the first pattern and the second pattern must be electrically insulated, an insulating layer is formed between the sensing pattern and the bridge electrode. The insulating layer may be formed only between the joint of the first pattern and the bridge electrode, or may be formed in the structure of the layer covering the sensing pattern. In the latter case, the bridge electrode can connect the second pattern through a contact hole formed in the insulating layer. The touch sensor has a difference in transmittance between a pattern area where a pattern is formed and a non-pattern area where a pattern is not formed, specifically, a light transmittance which is induced by a difference in refractive index in these areas. An optical adjustment layer may be further included between the substrate and the electrode as a means for appropriately compensating the difference, and the optical adjustment layer may include an inorganic insulating material or an organic insulating material. The optical adjustment layer may be formed by coating a photocurable composition containing a photocurable organic binder and a solvent on a substrate. The photocurable composition may further include inorganic particles. The inorganic particles may increase the refractive index of the optical adjustment layer.
The photocurable organic binder may include, for example, a copolymer of each monomer such as an acrylate-based monomer, a styrene-based monomer, and a carboxylic acid-based monomer. The photocurable organic binder may be, for example, a copolymer containing different repeating units such as an epoxy group-containing repeating unit, an acrylate repeating unit, and a carboxylic acid repeating unit.
The inorganic particles can include, for example, zirconia particles, titania particles, alumina particles, and the like. The photocurable composition may further include various additives such as a photopolymerization initiator, a polymerizable monomer, and a curing aid.

[Adhesive layer]
A film member such as a linear polarizing plate and a λ/4 retardation plate that forms each layer such as a window film, a polarizing plate, and a touch sensor that forms the laminated body for a flexible display device and each layer may be bonded with an adhesive. it can. As the adhesive, a water-based adhesive, an organic solvent-based adhesive, a solvent-free adhesive, a solid adhesive, a solvent volatilization type adhesive, a water-based solvent volatilization type adhesive, a moisture-curable adhesive, a heat-curable adhesive, Anaerobic curable adhesives, active energy ray curable adhesives, curing agent mixed adhesives, heat-meltable adhesives, pressure-sensitive adhesives, pressure-sensitive adhesives, rewet adhesives, etc. Can be used. Of these, water-based solvent volatilizing adhesives, active energy ray-curing adhesives, and pressure-sensitive adhesives are often used. The thickness of the adhesive layer can be appropriately adjusted according to the required adhesive strength and the like, and is, for example, 0.01 to 500 μm, preferably 0.1 to 300 μm, and the adhesive layer is the laminate for a flexible display device. There may be a plurality of them, but the thickness of each and the type of adhesive used may be the same or different.

As the water-based solvent volatilizing adhesive, polyvinyl alcohol-based polymer, water-soluble polymer such as starch, water-dispersed polymer such as ethylene-vinyl acetate emulsion, styrene-butadiene emulsion can be used as the main polymer. In addition to water and the base polymer, a cross-linking agent, a silane compound, an ionic compound, a cross-linking catalyst, an antioxidant, a dye, a pigment, an inorganic filler, an organic solvent and the like may be added. In the case of bonding with the water-based solvent volatile adhesive, the water-based solvent volatile adhesive may be injected between the adhered layers to bond the adhered layers and then dried to impart adhesiveness. The thickness of the adhesive layer when the water-based solvent volatilizing adhesive is used may be 0.01 to 10 μm, preferably 0.1 to 1 μm. When the above-mentioned aqueous solvent volatilization type adhesive is used for forming a plurality of layers, the thickness of each layer and the type of the adhesive may be the same or different.

The active energy ray-curable adhesive can be formed by curing an active energy ray-curable composition containing a reactive material that irradiates an active energy ray to form an adhesive layer. The active energy ray-curable composition can contain at least one polymer of a radically polymerizable compound and a cationically polymerizable compound similar to the hard coat composition. The radical-polymerizable compound is the same as the hard coat composition, and the same kind as the hard coat composition can be used. As the radically polymerizable compound used in the adhesive layer, a compound having an acryloyl group is preferable. It is also preferable to include a monofunctional compound in order to reduce the viscosity of the adhesive composition.

The cationically polymerizable compound is the same as that used in the hard coat composition, and the same kind as the hard coat composition can be used. An epoxy compound is preferable as the cationically polymerizable compound used in the active energy ray-curable composition. It is also preferable to include a monofunctional compound as a reactive diluent in order to reduce the viscosity of the adhesive composition.
The active energy ray composition may further contain a polymerization initiator. Examples of the polymerization initiator include radical polymerization initiators, cationic polymerization initiators, radical and cationic polymerization initiators, etc., which can be appropriately selected and used. These polymerization initiators are decomposed by at least one of irradiation with active energy rays and heating to generate radicals or cations to promote radical polymerization and cation polymerization. In the description of the hard coat composition, an initiator capable of initiating radical polymerization and/or cationic polymerization by irradiation with active energy rays can be used.

The active energy ray-curable composition is further an ion scavenger, an antioxidant, a chain transfer agent, an adhesion promoter, a thermoplastic resin, a filler, a flow viscosity modifier, a plasticizer, a defoaming agent solvent, an additive, a solvent. Can be included. In the case of adhering with the active energy ray-curable adhesive, the active energy ray-curable composition is applied to either or both of the adherend layers and then laminated, and activated through either adherent layer or both adherent layers. It can be adhered by irradiating it with an energy ray and curing it. The thickness of the adhesive layer when the active energy ray-curable adhesive is used may be 0.01 to 20 μm, preferably 0.1 to 10 μm. When the active energy ray-curable adhesive is used for forming a plurality of layers, the thickness of each layer and the type of adhesive used may be the same or different.

The pressure-sensitive adhesive may be classified into an acrylic pressure-sensitive adhesive, a urethane-based pressure-sensitive adhesive, a rubber-based pressure-sensitive adhesive, a silicone-based pressure-sensitive adhesive, etc. depending on the base polymer, and any of these may be used. In addition to the base polymer, the adhesive may contain a crosslinking agent, a silane compound, an ionic compound, a crosslinking catalyst, an antioxidant, a tackifier, a plasticizer, a dye, a pigment, an inorganic filler, and the like. The components constituting the pressure-sensitive adhesive are dissolved and dispersed in a solvent to obtain a pressure-sensitive adhesive composition, and the pressure-sensitive adhesive composition is applied onto a substrate and then dried to form a pressure-sensitive adhesive layer adhesive layer. It The adhesive layer may be directly formed, or may be separately formed on a substrate and transferred. It is also preferable to use a release film to cover the adhesive surface before adhesion. When the pressure-sensitive adhesive is used, the thickness of the adhesive layer may be 1 to 500 μm, preferably 2 to 300 μm. When the pressure-sensitive adhesive is used for forming a plurality of layers, the thickness of each layer and the type of pressure-sensitive adhesive used may be the same or different.

[Shading pattern]
The light blocking pattern may be applied as at least a part of a bezel or a housing of the flexible display device. The visibility of the image is improved by hiding the wiring arranged at the peripheral portion of the flexible display device by the light-shielding pattern and making it difficult to see. The light-shielding pattern may be in the form of a single layer or multiple layers. The color of the light-shielding pattern is not particularly limited, and may have various colors such as black, white and metallic colors. The light-shielding pattern can be formed of a pigment for realizing color and a polymer such as acrylic resin, ester resin, epoxy resin, polyurethane, or silicone. These may be used alone or as a mixture of two or more kinds. The light-shielding pattern can be formed by various methods such as printing, lithography and inkjet. The thickness of the light-shielding pattern is usually 1 to 100 μm, preferably 2 to 50 μm. It is also preferable to give a shape such as an inclination in the thickness direction of the light pattern.

Hereinafter, the present invention will be described more specifically based on Examples and Comparative Examples, but the present invention is not limited to the following Examples. Unless otherwise specified, "%" and "parts" in the examples mean% by mass and parts by mass. First, the measuring method will be described.

<Measurement of weight average molecular weight (Mw)>
The measurements were performed using gel permeation chromatography (GPC). The method for preparing the measurement sample and the measurement conditions are as follows.
(1) Sample preparation method 20 mg of a polyimide resin was weighed and 10 mL of a DMF eluent (10 mM lithium bromide solution) was added and completely dissolved. This solution was filtered through a chromatodisc (pore size 0.45 μm) to give a sample solution.
(2) Measurement condition device: HLC-8020GPC
Column: Guard column + TSKgel α-M (300 mm × 7.8 mm diameter) × 2 + α-2500 (300 mm × 7.8 mm diameter) × 1 Eluent: DMF (10 mM lithium bromide added)
Flow rate: 1.0 mL/min Detector: RI detector Column temperature: 40°C
Injection volume: 100 μL
Molecular weight standard: Standard polystyrene

<Measurement of viscosity>
(1) Sample Preparation Method A polyimide-based resin was dissolved in DMAc in an amount of 10% by mass to prepare a measurement sample.
(2) Measurement conditions Device name: LVDV-II+Pro (manufactured by Brookfield)
Measurement temperature: 25℃
Spindle: CPE-52
Sample volume: 0.6mL
Rotor rotation speed: 3.0 rpm

<Measurement of film thickness>
The thickness of the films obtained in Examples and Comparative Examples was measured with an ABS Digimatic Indicator (“ID-C112BS” manufactured by Mitutoyo Corporation).

<Flexibility test>
The films obtained in Examples and Comparative Examples were cut into a size of 10 mm×100 mm using a dumbbell cutter. The cut film is set in the body of the MIT folding fatigue tester (“MIT-DA” type: 0530 manufactured by Toyo Seiki Seisaku-sho, Ltd.), the test speed is 175 cpm, the bending angle is 135°, the load is 750 g, and the bending clamp is R 1. A bending test was conducted in both front and back directions under the condition of 0.0 mm to measure the number of times of flexing resistance of each film (the number of times bending was possible without breaking).
When the number of flexing cycles was 150,000 or more, it was marked as good, and when less than 150,000, it was marked as bad and marked with x. In addition, good (○) indicates that the number of flexing in both front and back directions is 150,000 or more, and poor (x) indicates that the number of flexing in either or both front and back is less than 150,000. Indicates.

[Example 1: Synthesis of polyimide resin]
Nitrogen was introduced into a sufficiently dried reaction vessel equipped with a stirrer and a thermometer, and the inside of the vessel was replaced with nitrogen. The inside of the reaction vessel was cooled to 10° C., 1907.2 parts of N,N-dimethylacetamide (DMAc) was put into the vessel, and 2,2′-bis(trifluoromethyl)benzidine (TFMB) 111.37 parts and 4, 4′-(Hexafluoroisopropylidene)diphthalic acid dianhydride (6FDA) (46.82 parts) was added, and the mixture was stirred for 3 hours.
Then, 10.37 parts of 4,4′-oxybis(benzoyl chloride) (OBBC) and 38.54 parts of terephthaloyl chloride (TPC) were added and stirred. To the resulting reaction solution, 1907.2 parts of DMAc and 4.28 parts of TPC were added, and the mixture was further stirred at 10° C. for 1 hour (step (I)). Further, 0.56 part of TFMB was added and stirred for 2 hours (step (II)).
Then, 31.80 parts of diisopropylethylamine and 75.32 parts of acetic anhydride were added and stirred for 30 minutes while maintaining the temperature at 10°C, 22.90 parts of 4-picoline was added, and the temperature of the reaction vessel was raised to 75°C. The mixture was further stirred for 3 hours to obtain a reaction liquid. The obtained reaction liquid was cooled, and when the temperature dropped to 40° C. or lower, 1147.1 parts of methanol was added. Then, nitrogen was introduced into a reaction vessel equipped with a stirrer and a thermometer, and the inside of the vessel was replaced with nitrogen. The above reaction liquid was put into a reaction vessel while stirring at 20°C. Further, 4575.1 parts of methanol was dropped, and then 2861.7 parts of ion-exchanged water was dropped to deposit a white solid. The deposited white solid was collected by centrifugal filtration and washed with methanol to obtain a wet cake containing a polyimide resin. The resulting wet cake was dried at 78° C. under reduced pressure to obtain a polyimide resin (powder) (step (III)).
As described above, the diamine compound used in the production of the polyimide resin is TFMB, and the addition amount of the diamine compound in the step (I) (first addition amount) and the addition amount of the diamine compound in the step (II) (second amount) The addition ratio) was 99.5:0.5.

[Example 2]
A polyimide resin was obtained in the same manner as in Example 1 except that the first addition amount of the diamine compound was 110.26 parts and the second addition amount was 1.679 parts.

[Example 3]
A polyimide resin was obtained in the same manner as in Example 1 except that the first addition amount of the diamine compound was 111.60 parts and the second addition amount was 0.448 parts.

[Example 4]
A polyimide resin was obtained in the same manner as in Example 1 except that the first addition amount of the diamine compound was 110.60 parts and the second addition amount was 0.045 parts.

[Example 5]
A polyimide resin was obtained in the same manner as in Example 1 except that the first addition amount of the diamine compound was 110.60 parts and the second addition amount was 0.179 parts.

[Example 6]
A polyimide resin was obtained in the same manner as in Example 1 except that the first addition amount of the diamine compound was 110.60 parts and the second addition amount was 0.067 parts.

[Comparative Example 1]
A polyimide resin was obtained in the same manner as in Example 1 except that the first addition amount of the diamine compound was 111.37 parts and the step (II) was not performed (the second addition was not performed). ..

[Comparative example 2]
A polyimide resin was obtained in the same manner as in Example 1 except that the first addition amount of the diamine compound was 110.81 parts and the step (II) was not carried out (the second addition was not carried out). ..

In Examples 1 to 6 and Comparative Examples 1 and 2, the molar ratio of each component (6FDA, TPC, OBBC, and TFMB) used in the production of the polyimide resin is shown in Table 1.

[Production of film]
The polyimide resins prepared in Examples 1 to 6 and Comparative Examples 1 and 2 were dissolved in DMAc to obtain polyimide resin varnish having a polyimide resin concentration of 10% by mass. The obtained resin varnish was applied on a smooth surface of a polyester substrate (manufactured by Toyobo Co., Ltd., trade name “A4100”) using an applicator so that the thickness of the self-supporting film was 55 μm, and the temperature was 50° C. for 30 minutes. Then, after drying at 140° C. for 15 minutes, the obtained coating film was peeled off from the polyester base material to obtain a self-supporting film. The self-supporting film was fixed to a metal frame and further dried in the atmosphere at 200° C. for 40 minutes to obtain a polyimide resin film having a thickness of 50 μm.
A flex resistance test was conducted on the obtained polyimide resin film. Molar ratio of amine in each component (referred to as final amine ratio), presence or absence of second addition (step (II)), molar ratio of first addition amount and second addition amount, weight average molecular weight of polyimide resin ( Table 2 shows Mw), the viscosity of the polyimide resin varnish at 25° C., and the evaluation results of the bending resistance test.

As shown in Table 2, it was confirmed that the films of Examples 1 to 6 were evaluated as good in the flex resistance test and were excellent in flex resistance. On the other hand, the films of Comparative Examples 1 and 2 formed from the polyimide-based resin produced without passing through the step (II) were found to be poorly evaluated in the flex resistance test.

Claims

Step (I) of obtaining an intermediate (K), which comprises a step (A) of reacting a diamine compound with a carboxylic acid compound having three or more carbonyl groups, and further reacting the intermediate (K) with a diamine compound. Step (II)
A method for producing a polyimide resin, comprising:
The amount of the diamine compound to be reacted in the step (I) is 80 to 99.99 mol, when the total amount of the diamine compound to be reacted in the steps (I) and (II) is 100 mol. The manufacturing method described in.
The production method according to claim 1 or 2, wherein the step (I) further includes a step (B) of reacting a dicarboxylic acid compound after the step (A).